Sealing sheet and display having resin composition layer

Abstract

To provide a sealing sheet that is excellent in embedability and die shift suppression when applied to the sealing of micro LEDs in a display employing micro LEDs as a light source.SOLUTION: A sealing sheet for sealing micro LEDs used in a display that employs micro LEDs as a light source comprises a first film, a resin composition layer and a second film arranged in this order. The first film has a release layer on the surface facing the resin composition layer. The thickness Ta of the resin composition layer is 2 to 100 μm, and the thickness Th of the second film is 12 to 188 μm, where Ta and Th satisfy the relational expression 0.1≤Ta / Th≤2. The maximum value of the loss tangent (maximum tanδ) in the range of -50°C to 80°C obtained by dynamic viscoelasticity measurement of the resin composition layer is from 0.6 to 2.2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a sealing sheet, and more particularly to a sealing sheet including a resin composition layer for sealing micro LEDs used in a display using micro LEDs as a light source, and a display on which the resin composition layer is mounted.

Background Art

[0002] In recent years, displays have been actively developed using various light-emitting elements for further performance improvement. Specifically, various display specifications such as backlight-type displays using liquid crystals, quantum dots, etc., displays using self-emitting elements such as mini / micro LEDs and organic ELs, plasma displays, electrophoretic displays, etc. are being studied, and their applications range from large displays such as signage and TVs to small sizes such as tablets, personal computers, smartphones, wearable devices, etc. are widely being considered. In particular, the development of displays using LEDs has been progressing day by day, and thermosetting resin compositions for sealing LED elements are described in Patent Documents 1 and 2. Patent Document 3 describes a method for manufacturing a micro LED light-emitting device that seals micro LEDs by deforming a barrier layer by applying pressure. The most attention-grabbing next-generation display technology is the micro LED display.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in LED elements that have been miniaturized, the distance between LED elements and the distance from the substrate have become narrower. The resin sheet for encapsulating the optoelectronic elements described in Patent Documents 1 and 2 is excellent in heat resistance and handleability, but the fluidity of the resin is insufficient, and it is not sufficient to fill the airspace following the micro-sized LED elements (embeddability). When there is a gap between the LED element and the encapsulating resin composition, light refracts and reflects at the gap portion, and the mixing of light has an adverse effect on the visibility of the display. On the other hand, when embedding micro LEDs using the encapsulating sheet described in Patent Document 3, stress is applied to the micro LEDs in one direction due to non-uniform flow of the resin, and displacement (die shift) occurs where the micro LEDs move away from the substrate. When die shift occurs, the micro LEDs have poor light emission, and a process for repairing the defective portion is required, which is a problem because production time and cost increase.

[0005] The present disclosure has been made in view of the above problems, and an object is to provide a display having a sealing sheet and a resin composition layer that are excellent in embeddability and suppression of die shift (die shift property) even when applied to a display using micro LEDs as a light source. Another object is to provide a display having a sealing sheet and a resin composition layer that are excellent in light controllability in order to prevent a decrease in the visibility of the display due to refraction and reflection of light. [Means for Solving the Problems]

[0006] As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by the following sealing sheet, and the present invention as described in [1] to [8] below has been completed. [1]: A sealing sheet for sealing micro LEDs used in a display having micro LEDs as a light source, wherein the sealing sheet has a first film, a resin composition layer, and a second film arranged in this order, the first film has a release layer on the surface facing the resin composition layer, the thickness Ta of the resin composition layer is 2 to 100 μm, the thickness Th of the second film is 12 to 188 μm, Ta and Th satisfy formula (1), and the maximum value of the loss tangent obtained by dynamic viscoelasticity measurement of the resin composition layer in the range of -50 to 80 °C is 0.6 to 2.2. Formula (1) 0.1 ≦ Ta / Th ≦ 2 [2]: The sealing sheet according to [1], wherein the Young's modulus of the second film is 1 to 6 GPa. [3]: The sealing sheet according to [1], wherein the ratio of the root mean square height Sq defined by ISO 25178 on the surface of the first film in contact with the resin composition layer to the thickness Ta of the resin composition layer is 30% or less. [4]: The sealing sheet according to [1], wherein the pencil hardness of the resin composition layer is 5B to 2H. [5]: The resin composition layer contains resin (A), The sealing sheet according to any one of [1] to [4], wherein the resin (A) contains at least one selected from the group consisting of acrylic resin (a1), urethane resin (a2), and epoxy resin (a3). [6]: The sealing sheet according to [5], wherein the resin composition layer contains a colorant (B). [7]: The sealing sheet according to [6], wherein the resin composition layer contains a polymerization initiator (C). [8]: A display having a micro LED as a light source and having a resin composition layer of the sealing sheet according to [5].

Advantages of the Invention

[0007] The present disclosure has been made in view of the above problems, and it has become possible to provide a sealing sheet and a display having a resin composition layer that are excellent in embedding property and suppression of die shift even when applied to a display having micro LEDs as a light source. In addition, according to the present disclosure, in addition to the above, it has also become possible to provide a display having a sealing sheet and a resin composition layer that are excellent in light control properties in order to prevent a decrease in the visibility of the display due to refraction and reflection of light.

Brief Description of Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the present disclosure will be described in detail. The embodiments described below illustrate an example of the present disclosure. The present disclosure is not limited to the following embodiments, and also includes modified examples implemented within the scope of not changing the gist of the present disclosure. In this specification, the numerical range specified using "~" shall include the numerical values described before and after "~" as the range of the lower limit value and the upper limit value. (Meth)acrylic acid refers to acrylic acid and methacrylic acid. In addition, various components appearing in this specification may be used alone or in combination of two or more, respectively, unless otherwise noted. When two or more are used in combination, the content rate uses the total value.

[0010] [Form of Sealing Sheet] As shown in FIG. 1, the sealing sheet of the present disclosure has a first film, a resin composition layer, and a second film arranged in this order. A plurality of resin composition layers can be provided. When adopting the three-layer structure shown in FIG. 1, a manufacturing method in which the resin composition layer is formed on the second film and then the first film is bonded is preferable. After manufacturing the sealing sheet or while manufacturing the sealing sheet, a sealing sheet roll can be obtained by winding the sealing sheet around a core in a roll form. The winding length can be designed according to the application. From the viewpoint of improving productivity, it is preferably 50 m or more, and more preferably 100 m or more. The winding length is preferably 10,000 m or less from the viewpoint of manufacturing yield. When the sealing sheet is in a roll form, it is preferably provided on the outer side of the first film roll.

[0011] The sealing sheet of the present disclosure is used for sealing micro LEDs used in a display having micro LEDs as light sources. The resin composition layer is preferably directly adhered to the micro LED for sealing. The micro LED is not particularly limited, but is preferably disposed on a substrate such as acrylic, urethane, polycarbonate, epoxy, polyimide, glass, paper, cloth, aluminum, ceramic, or polyethylene terephthalate, and preferably has an electrode portion. The micro LEDs are arranged singly or in plurality.

[0012] Since the resin composition layer has high followability to the uneven surface, a method of using it to follow the micro LED and fill the space between the micro LEDs is suitable. By filling the space between the micro LEDs with the resin composition layer, a sealing layer made of the resin composition layer is formed. The sealing layer has a function of fixing adjacent micro LEDs and preventing detachment. In particular, it is more preferable to use the resin composition layer as a sealing layer of a micro LED display panel. A micro LED is a fine LED element (chip) of 50 μm or 100 μm or less. By mounting a plurality of such micro LEDs on a substrate on which wirings and circuits are formed, a display having a plurality of optical semiconductor elements as light sources is formed. The micro LED is formed from an LED element such as GaAs, GaP, AlGaInP, InGaN, a sealing resin for sealing it, a package substrate, electrodes, etc., and the operating temperature is 25 to 60 °C. Hereinafter, an example of the process of forming the sealing layer will be described with reference to FIG. 2.

[0013] Step (a): Step of placing the sealing sheet As shown in Fig. 2(a), after peeling the first film from the sealing sheet to expose the resin composition layer, the resin composition layer of the sealing sheet is placed on the substrate having the micro LEDs so as to directly cover the micro LEDs. In this specification, the number of micro LEDs is not particularly limited. In display applications, the number of micro LEDs used is determined by the display size and the number of pixels. Also, the emission color of the micro LEDs is not particularly limited, and examples of the color development include red, green, and blue. The size of the micro LED is preferably such that the thickness is 100 μm or less and the area in plan view is 40,000 μm 2 The following are preferred, the thickness is 50 μm or less and the area in plan view is 10,000 μm 2 The following are more preferred, the thickness is 20 μm or less and the area in plan view is 2,500 μm 2 The following are even more preferred. The interval between the micro LEDs placed on the substrate is, for example, 10 to 5,000 μm. When red, green, and blue micro LEDs are set as one pixel and placed on the substrate, the interval between the pixels is, for example, 10 to 2,000 μm, preferably 20 to 1,800 μm, and more preferably 500 to 1,500 μm. The interval between the micro LEDs in one pixel is, for example, 10 to 200 μm, preferably 10 to 100 μm, and more preferably 20 to 60 μm.

[0014] Step (b): Pressing step As shown in Fig. 2(b), the resin composition layer is made to flow by pressing and filled around the micro LEDs and between the micro LEDs. The resin composition layer filled around the micro LEDs and between the micro LEDs becomes a sealing layer. The pressing method is not particularly limited, but hot pressing and vacuum pressing are preferred. From the viewpoint of the filling property of the resin composition layer, the temperature during pressing is preferably 20 to 200 °C, more preferably 30 to 150 °C, even more preferably 40 to 130 °C, and most preferably 60 to 110 °C. In order to enhance the adhesion between the micro-LED and the adherend, after pressing, heat aging may be further performed. The heating temperature is preferably 40 to 250 °C, more preferably 80 to 220 °C, and even more preferably 100 to 190 °C. The heating time is preferably 30 to 300 minutes, more preferably 60 to 240 minutes, and even more preferably 90 to 180 minutes. By setting the heating temperature and heating time as described above, the residual stress in the resin composition layer can be removed, and the adhesion surface can be smoothed. The heat aging may be performed after step (c) described later. The second film may be peeled off before heat aging or after heat aging.

[0015] Step (c): Etching step In step (c), etching may be performed as necessary to remove or thin the encapsulation layer on the optoelectronic semiconductor element. When performing step (c), it is preferably performed after peeling off the second film. By removing the excessive encapsulation layer, the luminance of the micro-LED is improved, and the visibility during light emission is ensured. The thickness of the encapsulation layer after etching is preferably about the same as the thickness of the micro-LED as shown in Fig. 2(c-1) or less than the thickness of the micro-LED as shown in Fig. 2(c-2). Note that even if the encapsulation layer is not completely removed from above the micro-LED, it is sufficient if it is substantially removed, and a state where some thin film remains is also acceptable. In addition, if sufficient luminance can be ensured, step (c) may be omitted. The etching method is not particularly limited, but wet etching methods such as chemical polishing using a chemical agent, physical polishing using an abrasive, laser etching, plasma etching using argon plasma or oxygen plasma, and dry etching methods such as ion beam etching are preferred examples. From the viewpoint of reducing surface irregularities, it is preferable to use plasma etching or a combination of a wet etching method and a dry etching method. In addition, as the conditions for plasma etching, for example, in an anisotropic plasma apparatus, a mixed gas of CF 4 / O 2 / N 2 may be used for dry etching under the conditions of an output of 1500 to 3000 W and 180 to 600 seconds. At this time, CF 4The gas supply amount is, for example, 50 to 100 sccm, and for O 2 The gas supply amount is, for example, 500 to 1000 sccm, and for N 2 The gas supply amount may be, for example, 50 to 100 sccm.

[0016] As described above, through steps (a) to (c), the sealing sheet of the present disclosure can form a sealing layer from the resin composition layer. Next, the constituent components of the sealing sheet of the present disclosure will be described in detail while giving preferred examples.

[0017] [First Film] The first film is not particularly limited. For example, polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polypropylene and polyethylene, polyvinyl chloride films, polyurethane films, nylon films, polyolefin films, triacetyl cellulose films, cycloolefin films, and other plastic films can be mentioned. From the perspective of handling, polyester films and polyolefin films are preferred.

[0018] The first film has a release layer on the surface facing the resin composition layer. The release layer is preferably formed by applying a release agent such as a silicone resin, an alkyd resin, a fluororesin, or a melamine resin to the film. From the perspective of handling (preventing separation), a release layer using a silicone resin is more preferred. The release force Pl of the first film is preferably 0.1 to 3 gf / 20 mm, more preferably 0.3 to 2 gf / 20 mm, and even more preferably 0.5 to 1 gf / 20 mm. The release force Pl of the first film can be adjusted by the release treatment of the release layer. For example, it can be adjusted by the type of release agent, the coating amount of the release agent, and the surface roughness of the release layer. When it is desired to reduce the value of the release force, treatments such as increasing the surface roughness and increasing the coating amount of the release agent are effective. When it is desired to increase the value of the release force, the opposite adjustment can be made. The peel strength Pl of the first film can be measured, for example, by attaching the second film of the sealing sheet to a SUS plate and peeling the first film from the resin composition layer at a peeling angle of 180° and a peeling speed of 300 mm / min in an environment of 23°C and a relative humidity of 50%. The first film may have a functional layer in addition to the release layer. Specific examples of the functional layer include an antistatic layer and an antiblocking layer.

[0019] The thickness Tl of the first film is preferably 2 to 250 μm, more preferably 10 to 100 μm, and even more preferably 20 to 60 μm. When a release layer or a functional layer is provided on the first film, the thickness Tl is a value including the release layer. By setting the thickness within the above range, it is possible to control the transfer of the undulation of the first film to the resin composition layer and form a uniform resin composition layer. The first film is preferably directly laminated with the resin composition layer. When the first film is directly laminated with the resin composition layer, the ratio of the root mean square height Sq of the surface roughness conforming to ISO 25178 to the thickness Ta of the resin composition layer on the surface of the first film in contact with the resin composition layer is preferably 30% or less, more preferably 15% or less, and even more preferably 7.5% or less. By setting the ratio within the above range, the surface roughness transferred to the resin composition layer can be controlled, and the resin composition layer is sufficiently smoothed in the pressing process described later, so that the die shift property and the adhesion property are improved. The root mean square height Sq can be measured, for example, by the method described in the examples below. The root mean square height Sq value is preferably 0.01 to 2 μm, more preferably 0.04 to 1.5 μm, and even more preferably 0.1 to 1.5 μm. Further, the root mean square height Sq can be adjusted by the release treatment of the release layer surface of the first film. For example, it can be adjusted by the type of release agent, the coating amount of the release agent, and the coating method of the release agent. When it is desired to increase the value of the root mean square height Sq, treatments such as reducing the coating amount of the release agent, accelerating the drying after the release agent coating, and including a filler in the release agent are effective. When it is desired to decrease the value of the root mean square height Sq, the opposite adjustment may be made. In addition, a method of transferring unevenness using a film or carrier material having a predetermined root mean square height Sq can also be applied.

[0020] [Second film] The second film is not particularly limited. For example, polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polypropylene and polyethylene, polyvinyl chloride films, polyurethane films, nylon films, polyolefin films, triacetyl cellulose films, cycloolefin films, and other plastic films can be mentioned. From the viewpoint of handling, polyester films and polyolefin films are preferred. The second film is preferably directly laminated with the resin composition layer. The Young's modulus of the second film is preferably 1 to 6 GPa, more preferably 2 to 5 GPa, and even more preferably 3 to 5 GPa. By setting it within the above range, the flow of the resin composition layer can be controlled while uniformly applying pressure to the resin composition layer in the pressing step described later, and the embedding property becomes good. The Young's modulus of the second film can be adjusted by the crystal state and the orientation direction. By increasing the crystallinity or converting random amorphous chains into oriented amorphous chains, a high Young's modulus can be exhibited. When it is desired to lower the Young's modulus, the opposite adjustment may be made. When setting the Young's modulus within the above range, it is preferable to use a polyester film or a polyolefin film, and more preferably polyethylene terephthalate. The Young's modulus of the second film can be measured, for example, by the method described in the examples below.

[0021] It is preferable that the second film has a release layer on the surface facing the resin composition layer. The release layer is preferably formed by applying a release agent such as a silicone resin, an alkyd resin, a fluororesin, or a melamine resin to the film, and a release layer using a silicone resin is more preferable from the viewpoint of handling (preventing separation). The peel force Ph of the second film is preferably 0.5 to 5 gf / 20 mm, more preferably 0.8 to 4 gf / 20 mm, and even more preferably 1.0 to 3 gf / 20 mm. The peel force Ph of the second film can be adjusted by the release treatment of the release layer. For example, it can be adjusted by the type of the release agent, the coating amount of the release agent, and the surface roughness of the release layer. When it is desired to reduce the value of the peel force, treatments such as increasing the surface roughness and increasing the coating amount of the release agent are effective, and when it is desired to increase the value of the peel force, the opposite adjustment can be made. It is preferable that the peel force Ph of the second film is greater than the peel force Pl of the first film. Specifically, the value of Ph / Pl is more preferably 1.1 to 11, and even more preferably 1.1 to 6. The peel force Ph of the second film can be measured, for example, after peeling the first film from the sealing sheet, attaching the exposed resin composition layer to a SUS plate, and further peeling the second film from the resin composition layer at a peeling angle of 180° and a peeling speed of 300 mm / min in an environment of 23°C and a relative humidity of 50%. The second film may have a functional layer in addition to the release layer. Specific examples of the functional layer include an antistatic layer and an antiblocking layer. The thickness Th of the second film is 12 to 188 μm, more preferably 12 to 100 μm, and even more preferably 20 to 60 μm. When a release layer or a functional layer is provided on the second film, the thickness Th is a value including the release layer and the functional layer. By setting the thickness within the above range, the pressure transmission applied to the resin composition layer in the pressing process described later is controlled, and the resin composition layer flows uniformly, so that the embedability, die shift property, and adhesion are improved.

[0022] [Resin composition layer] The resin composition layer preferably contains resin (A), more preferably contains a colorant (B) and / or a polymerization initiator (C), and may also contain other components. In the present disclosure, resin (A) is a substance having a function of adhering and fixing objects as a binder. Specific examples include a substrate having micro LEDs and a function of adhering and fixing to micro LEDs.

[0023] For the resin composition layer of the present disclosure, the maximum value (tanδ maximum value) of the loss tangent in the range of -50 to 80 °C obtained by dynamic viscoelasticity measurement is 0.6 to 2.2, more preferably 0.9 to 1.7, and even more preferably 1.1 to 1.5. The tanδ maximum value is, for example, the value of the loss tangent (tanδ) when the tanδ curve reaches a maximum. In the case where there are two or more maximum values, it indicates the value of the largest loss tangent (tanδ). When the tanδ maximum value is 0.6 or more, the pressure transferability to the resin composition layer in the pressing process is good, the stress applied to the micro LED is small, and the die shift property is improved. When the tanδ maximum value is 2.2 or less, the pressure absorbability of the resin composition layer in the pressing process is good, and the embedding property follows the unevenness of the micro LED and is improved. It should be noted that the tanδ maximum value of the present disclosure can be adjusted by the type and composition of resin (A), the type of colorant (B), the dispersion state and content, the type and content of polymerization initiator (C), and the type and content of other components such as crosslinking agents and monomers. When containing (meth)acrylic resin (a1) as resin (A), the tanδ maximum value can be made higher than when containing urethane resin (a2), but this is not always the case depending on the resin composition. When resin (A) contains (meth)acrylic resin (a1), the tanδ maximum value can be lowered by increasing the content of alkyl methacrylate such as methyl methacrylate, and if it is desired to increase the tanδ maximum value, the opposite adjustment can be made. When carbon black is contained as the colorant (B), the maximum value of tanδ can be made lower than when a metal oxide pigment is contained, but this is not always the case depending on the dispersion state of the particles. When the colorant (B) contains carbon black, the maximum value of tanδ can be lowered by increasing the content of carbon black. If it is desired to increase the maximum value of tanδ, the opposite adjustment may be made. When a thermal polymerization initiator is contained as the polymerization initiator (C), the maximum value of tanδ can be increased by increasing the content. If it is desired to lower the maximum value of tanδ, the opposite adjustment may be made. When the resin composition layer contains a crosslinking agent as another component, the maximum value of tanδ can be increased by increasing the content. If it is desired to lower the maximum value of tanδ, the opposite adjustment may be made. By increasing the content of a monomer having a low viscosity, the maximum value of tanδ can be lowered. If it is desired to increase the maximum value of tanδ, the opposite adjustment may be made. Specific examples of the monomer having a low viscosity include 1,6 - hexanediol diacrylate.

[0024] Also, the loss tangent (tanδ40) at 40°C obtained by dynamic viscoelasticity measurement of the resin composition layer of the present disclosure is preferably 0.6 to 2.0, more preferably 0.8 to 1.9, and even more preferably 1.1 to 1.5. By setting tanδ40 within the above range, the pressure applied to the resin composition layer in the pressing step is appropriately transmitted, and the embedding property and die shift property are improved. In order to control the diffusibility of the pressure applied to the resin composition layer in the range of 20 to 200°C, which is a preferable temperature range for the pressing step, by adjusting the loss tangent (tanδ40) at 40°C to the above range, the loss tangent at 20 to 40°C and the loss tangent at 40 to 200°C can be balanced without bias. tanδ40 can be adjusted depending on the type and composition of the resin (A) and the type and dispersion state of the colorant (B). Specifically, the same adjustment method as for the tanδ peak intensity can be mentioned.

[0025] The peak top temperature of the loss tangent (tanδ peak temperature) obtained by measuring the dynamic viscoelasticity of the resin composition layer of the present disclosure refers to the temperature at which the tanδ curve reaches its maximum. When there are two or more peaks, it indicates the peak temperature on the lowest temperature side. The tanδ peak temperature is preferably -30 to 70°C, more preferably -20 to 50°C, even more preferably -10 to 30°C, and most preferably -10 to 10°C. When the tanδ peak temperature is within the above range, the residual stress of the resin can be sufficiently removed in the heat aging process, so the adhesion to the adherend is improved. Note that the tanδ peak temperature of the present disclosure can be adjusted according to the type and composition of the resin (A). When the resin (A) contains a (meth)acrylic resin (a1), the tanδ peak temperature can be increased by increasing the content of the monomer with a high glass transition temperature (Tg) of the homopolymer. When it is desired to lower the tanδ peak temperature, the opposite adjustment can be made. The glass transition temperature (Tg) of the homopolymer in the present disclosure can use the values described in POLYMER HANDBOOK, 1999, FOURTH EDITION.

[0026] The above-mentioned loss tangent (tanδ) is the ratio of the loss elastic modulus to the storage elastic modulus obtained by measuring the dynamic viscoelasticity in the tensile mode at a frequency of 10 Hz and -50 to 150°C. The dynamic viscoelasticity and loss tangent (tanδ) in the present disclosure were measured by the method described in the examples below. Note that when the resin composition layer contains either a polymerization initiator (C) or a crosslinking agent, the polymerization / crosslinking reaction during measurement is in an incomplete state. Also, for the above measurement, it is preferable to measure a sheet with a thickness of 50 μm or more. When measuring a sheet less than this, prepare two sets of sealing sheets without the first film, laminate the resin composition layers together with a laminator to produce a laminate of the second film / resin composition layer / second film, and further peel off the second film on one side of the above laminate, and repeatedly laminate the resin composition layers of the sealing sheets so that the thickness becomes 50 μm or more, and then the dynamic viscoelasticity may be measured.

[0027] From the viewpoints of embedability and die shift property, the thickness Ta of the resin composition layer is 2 to 100 μm, preferably 5 to 60 μm, more preferably 10 to 40 μm, still more preferably 10 to 30 μm, and most preferably 13 to 30 μm from the viewpoint of light shielding property. By setting the thickness Ta of the resin composition layer within the above range, the pressure applied to the resin composition layer in the pressing process is appropriately dispersed and sufficiently homogenized, so that the embedability and die shift property are improved. The resin composition layer may be a single layer or in any form of a laminate of two or more layers. In the case of two or more layers, it refers to the total thickness. The thickness Ta of the resin composition layer can be adjusted by the method for forming the resin composition layer described later. The thickness Ta in the present disclosure is measured by the method described in the examples below.

[0028] The thickness Ta of the resin composition layer satisfies the formula (1) 0.1 ≦ Ta / Th ≦ 2 representing the ratio to the thickness Th of the second film, more preferably 0.2 ≦ Ta / Th ≦ 1.5, and still more preferably 0.2 ≦ Ta / Th ≦ 1.2. By setting it within the above range, the pressure transmission applied to the resin composition layer in the pressing process described later is controlled, and the resin composition layer flows uniformly, so that the embedability and die shift property are improved.

[0029] From the viewpoints of embedability and die shift property, the pencil hardness of the resin composition layer is preferably 5B to 2H, more preferably 4B to H, and still more preferably 3B to F. By setting the pencil hardness of the resin composition layer within the above range, the pressure applied to the resin composition layer in the pressing process is appropriately dispersed and sufficiently homogenized, so that the embedability and die shift property are improved. The pencil hardness of the resin composition layer can be adjusted by the type of the resin (A), the content of the polymerization initiator (C), and the content of the monomer. Increasing the content of the polymerization initiator (C) can make it harder, and increasing the content of the monomer can make it softer. The pencil hardness of the resin composition layer in the present disclosure was measured by the method described in the examples below. When the resin composition layer contains either a polymerization initiator (C) or a crosslinking agent, the polymerization / crosslinking reaction during measurement is incomplete.

[0030] [Method for forming the resin composition layer] The method for forming the resin composition layer is not particularly limited, but a preferred example is a method of forming a resin composition layer by applying a resin composition in which an arbitrary solvent is added to the components constituting the resin composition layer. The addition of the solvent is for the purpose of adjusting to a viscosity level suitable for coating and adjusting the film thickness. For coating, known coating machines and techniques such as comma coater, die coater, roll coater, lip coater, reverse coater, gravure coater, bar coater, curtain coater, dip coating, spin coating, silk screen, casting can be used. The solvent contained in the resin composition can be removed by a drying process after coating. As a preferred embodiment, after applying the resin composition to a support such as a first film or a second film, the coated film is heated and dried using a hot air oven, an infrared heater, etc., so that a resin composition layer can be formed on one surface of the support. Further, in order to increase the crosslinking density of the resin composition layer, it is preferable to perform an aging treatment such as standing under specific temperature conditions or irradiate with UV or the like. Also, after coating, it may be transferred to another support such as a first film, a second film, or a substrate using a laminator.

[0031] [Resin composition] The resin composition can be obtained by mixing while stirring a solvent and the components constituting the resin composition layer. As a component constituting the resin composition layer, it is preferable to contain resin (A), more preferably to contain a colorant (B) and / or a polymerization initiator (C), and other components may also be contained. An arbitrary solvent is used for the purpose of adjusting processing suitability such as viscosity when mixing the components constituting the resin composition layer. For example, those compatible with resin (A) such as ester-based, ether ester-based, ether-based, alcohol-based, and aromatic-based ones can be appropriately used. Specifically, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, cyclohexanone, toluene, xylene, isopropyl alcohol, N-methyl-2-pyrrolidone, etc. are given as preferred examples. For stirring, a known stirring device can be used, and a disper, mixer, shaker, homogenizer, etc. are preferable. In order to obtain the resin composition, first, a mixture is prepared by mixing a colorant (B) into resin (A) and an arbitrary solvent, and second, a manufacturing process of two or more steps may be taken in which resin (A), a polymerization initiator (C), and other components are added as necessary.

[0032] [Resin (A)] The weight average molecular weight (Mw) of resin (A) is preferably 1,000,000 or less. More preferably 300,000 or less, and even more preferably 150,000 or less. By setting the weight average molecular weight (Mw) of resin (A) to 1,000,000 or less, the entanglement of molecular chains in the heat aging process is likely to be loosened, and the adhesion is improved. The lower limit of the weight average molecular weight (Mw) of resin (A) is not particularly limited, but it is preferably 400 or more, more preferably 900 or more, even more preferably 3,000 or more, still more preferably 5,000 or more, and most preferably 10,000 or more. By setting the weight average molecular weight (Mw) of resin (A) to 400 or more, the coating film strength of the resin composition layer is improved. Note that the weight average molecular weight (Mw) is a value in terms of polystyrene measured by the gel permeation chromatography (GPC) method. The weight average molecular weight (Mw) in the present disclosure was measured by the method described in the examples below.

[0033] The glass transition temperature (Tg) of the resin (A) is preferably from -30°C to 80°C, more preferably from -20°C to 60°C, still more preferably from -15°C to 40°C, even more preferably from -10°C to 20°C, and most preferably from -10°C to 10°C. By setting the range as above, the residual stress of the resin (A) after the pressing process is reduced, and thus the adhesion becomes suitable. In the present disclosure, when the polymerization / crosslinking reaction of the resin (A) occurs due to heat or light, the polymerization / crosslinking reaction at the time of measurement is in an incomplete state. The glass transition temperature (Tg) of the resin (A) in the present disclosure is measured by the method described in the examples below.

[0034] The resin (A) can be used alone or in combination of two or more. The content of the resin (A) is preferably 10 to 98% by mass, more preferably 25 to 95% by mass, and still more preferably 60 to 90% by mass based on the total amount (100% by mass) of the resin composition layer. When two or more types of the resin (A) are included, the content of each resin (A) is preferably 5% by mass or more, and the total content is preferably within the above range. By setting the content of the resin (A) within the above range, the compatibility with the colorant (B) becomes good and the light-shielding property is improved.

[0035] Preferable examples of the resin (A) include (meth)acrylic resins (a1), urethane resins (a2) such as polyurethane resins and polyurethane-urea resins, epoxy resins (a3), maleic resins, styrene-maleic acid copolymers, polystyrene resins, polybutadiene resins, polyester resins, condensation-type polyester resins, addition-type polyester resins, melamine resins, polycarbonate resins, oxetane resins, phenoxy resins, polyimide resins, polyamideimide resins, alkyd resins, amino resins, polyamide resins, polylactic acid resins, oxazoline resins, benzoxazine resins, silicone resins, fluorine resins, butyral resins, chlorinated polyethylene, chlorinated polypropylene, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, vinyl-based resins, rubber-based resins, cyclized rubber-based resins, celluloses, polyethylene (HDPE, LDPE), etc. From the viewpoint of embeddability, it is preferable to contain at least one of (meth)acrylic resins (a1), urethane resins (a2), and epoxy resins (a3). Further, from the viewpoint of adhesion, it is more preferable to contain (meth)acrylic resins (a1).

[0036] The resin (A) preferably has one or more functional groups that can be used for polymerization / crosslinking reactions by heat or light. The functional groups can be appropriately selected according to the reactivity with the resins (A) themselves, the polymerization initiator (C) described later, and the crosslinking agent, and may be self-crosslinkable functional groups. Examples of the functional groups include a hydroxyl group, a carboxy group, an amino group, an epoxy group, an oxetanyl group, an oxazoline group, an oxazine group, an aziridine group, a thiol group, an isocyanate group, a blocked isocyanate group, a silanol group, a (meth)acryloyl group, an N-vinyl group, a vinyl ether group, an allyl group, an unsaturated carboxylic acid group, etc. The (meth)acryloyl group, N-vinyl group, vinyl ether group, allyl group, and unsaturated carboxylic acid group, which are radically polymerizable functional groups, are preferable.

[0037] [(meth)acrylic resin (a1)] In the present disclosure, the (meth)acrylic resin (a1) is an acrylic copolymer obtained by copolymerizing (meth)acrylic acid ester monomers, and is a polymer having constitutional units based on 2 to 20,000 monomers. Preferable examples of the (meth)acrylic acid ester monomers include (meth)acrylic acid alkyl ester monomers. When introducing functional groups that can be used in the polymerization / crosslinking reaction, a (meth)acrylic copolymer obtained by copolymerizing a functional group-containing monomer and a (meth)acrylic acid ester monomer is preferable. Note that, with respect to the (meth)acrylic resin (a1) of the present disclosure, a compound containing two or more urethane bonds in one molecule and a compound having two or more epoxy groups in one molecule are excluded.

[0038] (Meth)acrylic acid alkyl ester monomers are compounds obtained by esterifying (meth)acrylic acid to introduce an alkyl group or a cycloalkyl group, and the alkyl group or cycloalkyl group may be any of a linear, branched, or cyclic saturated aliphatic hydrocarbon group. The saturated aliphatic hydrocarbon group is preferably a saturated aliphatic hydrocarbon group having 1 to 20 carbon atoms, more preferably a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms. Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and the like. Among these, particularly from the viewpoint of the dispersibility of the colorant (B), it is particularly preferable to use methyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, and most preferably to use methyl (meth)acrylate and n-butyl (meth)acrylate.

[0039] With respect to 100% by mass of the (meth)acrylic resin (a1), the structural unit derived from the (meth)acrylic acid alkyl ester monomer is preferably 1 to 100% by mass, more preferably 20 to 99.5% by mass, and even more preferably 80 to 99% by mass from the viewpoint of adhesion.

[0040] The (meth)acrylic resin (a1) preferably has a structural unit derived from a functional group-containing monomer and / or an unsaturated bond. Examples of the functional group-containing monomer include a carboxy group-containing monomer, a hydroxy group-containing monomer, an epoxy group-containing monomer, and an amino group-containing monomer. By containing the functional group-containing monomer, the cohesive force of the resin (A) is improved, and a tough resin composition layer can be obtained. In particular, it is preferable to contain a carboxy group-containing monomer, a hydroxy group-containing monomer, and an epoxy group-containing monomer.

[0041] Examples of the carboxy group-containing monomer include (meth)acrylic acid, β-carboxyethyl (meth)acrylate, p-carboxybenzyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, and isocrotonic acid. Among these, (meth)acrylic acid is preferable from the viewpoint of adhesion.

[0042] Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Among these, 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate are more preferable from the viewpoint of adhesion.

[0043] Examples of the amino group-containing monomer include (meth)acrylic acid monoalkylamino esters such as monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, and monoethylaminopropyl (meth)acrylate.

[0044] For the purpose of introducing an unsaturated bond into the (meth)acrylic resin (a1), an epoxy group-containing monomer can also be used. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, and 6-methyl-3,4-epoxycyclohexylmethyl (meth)acrylate. Among these, from the viewpoint of reactivity, it is preferable to contain glycidyl (meth)acrylate. Further, it is preferable to react the epoxy group of the epoxy group-containing monomer with the carboxy group of a carboxy group-containing monomer such as (meth)acrylic acid to introduce an unsaturated bond such as a (meth)acryloyl group into the (meth)acrylic resin (a1). At this time, the number of epoxy groups in one molecule is preferably 1 or less, and it is preferable that no epoxy group remains.

[0045] With respect to 100% by mass of the (meth)acrylic resin (a1), the total of the structural units derived from the functional group-containing monomer is preferably 0.1 to 20% by mass. By setting it within the above range, the cohesive force can be adjusted. With respect to 100% by mass of the (meth)acrylic resin (a1), the constituent unit derived from the carboxy group-containing monomer is preferably 0.1 to 10% by mass. By being within the above range, the adhesion can be enhanced. With respect to 100% by mass of the (meth)acrylic resin (a1), the constituent unit derived from the hydroxy group-containing monomer is preferably 0.1 to 10% by mass. By being within the above range, the adhesion can be enhanced.

[0046] (Meta)acrylic resin (a1) may contain structural units derived from (meta)alkyl acrylate and other monomers copolymerizable with functional group-containing monomers. For example, monomers having an alkyleneoxy group and other vinyl monomers can be mentioned. For example, methoxyethyl acrylate, methoxydiethylene glycol acrylate, vinyl acetate, vinyl crotonate, styrene, acrylonitrile, acrylamide can be exemplified. The structural units derived from the other monomers are preferably 0.1 to 20% by mass in 100% by mass of the (meta)acrylic copolymer.

[0047] (Meta)acrylic resin (a1) can be obtained by polymerizing an acrylic monomer mixture. During polymerization, a polymerization initiator can be used as necessary. The content of the polymerization initiator is, for example, 0.01 to 10% by mass based on 100% by mass of the monomer mixture. The polymerization method is not limited. For example, it can be polymerized by solution polymerization, bulk polymerization, emulsion polymerization, suspension polymerization, and solution polymerization is most preferred because of the ease of polymerization control. Solvents used in solution polymerization can be exemplified by, for example, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, butyl acetate, toluene, xylene, anisole, cyclohexanone, isopropyl alcohol. The polymerization temperature can be, for example, 60 to 120°C, and the polymerization time can be about 2 to 12 hours.

[0048] The polymerization initiator is preferably a radical polymerization initiator. As the radical polymerization initiator, peroxides and azo compounds are suitable. Any of the thermal radical polymerization initiators described later can be used, and specifically, 2,2'-azobisisobutyronitrile (abbreviation: AIBN) is preferred.

[0049] [Urethane resin (a2)] In the present disclosure, the urethane resin (a2) is a compound containing two or more urethane bonds in one molecule. The urethane resin can be obtained by reacting a polyisocyanate with a polyol. The polyisocyanate may be any one having two or more isocyanate groups in one molecule. From the viewpoint of the dispersibility of the colorant (B), diisocyanate or triisocyanate is preferable, and diisocyanate is more preferable. As the diisocyanate, it can be appropriately selected and used from known aliphatic diisocyanates such as hexamethylene diisocyanate and known aromatic diisocyanates such as benzene-1,3-diisocyanate. Further, an isocyanate group-terminated prepolymer obtained by reacting a polyol and an excess of polyisocyanate may be used as an intermediate of the urethane resin. The polyol may be any one having two or more hydroxyl groups in one molecule. From the viewpoint of the dispersibility of the colorant (B), diol or triol is preferable, and diol is more preferable. As the diol, it can be appropriately selected and used from known aliphatic diols such as ethylene glycol and known aromatic diols such as benzene diol. Further, prepolymers such as polyether polyol, polyester polyol, and polycarbonate polyol may be used.

[0050] The urethane resin (a2) may further be a polyurethane-urea resin having a urea bond. The polyurethane-urea resin can be synthesized, for example, by reacting a polyamine with a urethane resin having an isocyanate group at the terminal. The polyamine may be any one having two or more amino groups in one molecule. From the viewpoint of the dispersibility of the colorant (B), diamine or triamine is preferable, and diamine is more preferable. As the diamine, it can be appropriately selected and used from known aliphatic diamines such as ethylenediamine and known aromatic diamines such as phenylenediamine.

[0051] From the perspective of the dispersibility of the colorant (B), the urethane resin (a2) preferably further has a radically polymerizable functional group such as a (meth)acryloyl group, N-vinyl group, vinyl ether group, allyl group, unsaturated carboxylic acid group, etc. as a functional group, and more preferably has a (meth)acryloyl group. Specifically, a (meth)acryloyl group can be introduced by subjecting the aforementioned polyol, diisocyanate or triisocyanate to an addition reaction with an acrylate having a hydroxyl group.

[0052] [Epoxy resin (a3)] In the present disclosure, the epoxy resin (a3) is a compound having two or more epoxy groups in one molecule. The epoxy resin (a3) also includes a compound obtained by adding a functional group. As the functional group, it preferably has a radically polymerizable functional group such as a (meth)acryloyl group, N-vinyl group, vinyl ether group, allyl group, unsaturated carboxylic acid group, etc., and more preferably has a (meth)acryloyl group. As the property of the epoxy resin (a3), the adhesion can be improved by using a liquid state, and the film-forming property of the resin composition layer can be improved by using a solid state. Examples of the epoxy resin (a3) include glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, cycloaliphatic (alicyclic) epoxy resins, bisphenol type epoxy resins, hydrogenated bisphenol type epoxy resins, etc. are preferable. Further, from the perspective of adhesion, the epoxy resin (a3) is more preferably a bisphenol type epoxy resin or a high-purity hydrogenated epoxy resin. As a compound obtained by adding a radically polymerizable functional group as a functional group to one or more epoxy groups, bisphenol A type diglycidyl ether diacrylate is preferable.

[0053] Examples of the glycidyl ether type epoxy resin include cresol novolak type epoxy resin, tris(glycidyloxyphenyl)methane, and tetrakis(glycidyloxyphenyl)ethane. Examples of glycidylamine type epoxy resins include tetraglycidyl diaminodiphenylmethane and tetraglycidyl metaxylylenediamine. Examples of glycidyl ester type epoxy resins include diglycidyl phthalate, diglycidyl hexahydrophthalate, diglycidyl tetrahydrophthalate, and the like. Examples of alicyclic (alicyclic type) epoxy resins include epoxycyclohexylmethyl-epoxycyclohexanecarboxylate, bis(epoxycyclohexyl) adipate, and the like. Examples of bisphenol type epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy crosslinking agent, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, and the like. In particular, bisphenol A type epoxy resin is preferable from the viewpoint of adhesion. Examples of hydrogenated bisphenol type epoxy resins include hydrogenated bisphenol A type epoxy resin, hydrogenated bisphenol F type epoxy resin, and the like. In particular, hydrogenated bisphenol A type epoxy resin is preferable from the viewpoint of adhesion.

[0054] [Colorant (B)] As the colorant (B), any of inorganic pigments, organic pigments, and dyes can be used, and color adjustment can also be performed by a mixed system. The color tone is not particularly limited, but black is preferable from the viewpoint of light shielding properties. A mixed system colorant can obtain black by subtractive mixing of a plurality of pigments. A black pigment is more preferable from the viewpoint of dispersibility. Examples of black pigments include carbon black, ketjen black, carbon nanotubes (CNT), perylene black, titanium black, iron black, aniline black, acetylene black, chromium oxide iron, and the like. From the viewpoint of adhesion, carbon black is preferable.

[0055] As the carbon black used in the present disclosure, known carbon blacks such as channel black, furnace black, thermal black, and lamp black can be used. Specific examples of carbon black include "Raven3500, 1180, 1080Ultra, 1060Ultra, 1040" manufactured by Birla Carbon, "TOKABLACK #8300, #7360SB" manufactured by Tokai Carbon, "Special Black350, 250, 100, 550, 5, 4, 4A, 6", "Nipex160IQ, 170IQ", "PrintexU, V, 140U, 140V, 95, 90, 85, 80, 75, 55, 45, P, 60, L6, L, 300, 30, 3, 35, 25, A, G", "ColorBlackFW200, FW2, S170" manufactured by Orion Engineered Carbons, "REGAL400R, 330R, 250R", "MOGUL E, L", "MONARCH1300, 280" manufactured by Cabot, and "MA7, 8, 11, 14, 77, 100, 100R, 100S, 220, 230", "#2650, #2600, #2350, #2300, #1000, #980, #970, #960, #950, #900, #850, #750B, #650B, #52, #47, #45, #45L, #44, #40, #33, #32, #30, #25, #20, #10, #5, #95" manufactured by Mitsubishi Chemical, etc. From the perspective of dispersibility, carbon black preferably has a specific surface area of 50 to 400 m 2 / g, a volatile content of 0.1 to 10% by weight, and a pH value of 2 to 10. Those having a pH value of 3 to 8 are more preferred, and those having a pH value of 3 to 6 are even more preferred.

[0056] The colorant (B) preferably has an average primary particle diameter (hereinafter referred to as particle diameter) of 10 to 100 nm. By setting the particle diameter to 10 nm or more, it is easy to maintain the viscosity of the resin composition at a level suitable for coating. Also, by setting the particle diameter to 100 nm or less, the blackness is improved and high light-shielding performance is exhibited. When the particle shape of the colorant (B) has an average aspect ratio (major axis length / minor axis length) of 1.5 or more, the particle diameter is determined by averaging the major axis lengths. The particle diameter of the colorant (B) can be determined from the average value of about 20 primary particles observable from an image magnified about 50,000 to 1,000,000 times by a transmission electron microscope (TEM).

[0057] The content rate of the colorant (B) is preferably 5 to 45% by mass, more preferably 15 to 35% by mass, and still more preferably 20 to 30% by mass based on the total amount (100% by mass) of the light-shielding layer. This is because when the content rate of the colorant (B) is within the above range, an excellent light-shielding property can be achieved.

[0058] From the viewpoint of adjusting the film-forming property and light-shielding property of the resin composition layer, it is preferable that the colorant (B) is dispersed in the resin (A) and used as a dispersion. As the dispersion treatment, any commonly used disperser for mechanical comminution may be used, and examples thereof include a ball mill, a roll mill, a sand mill, a bead mill, and a nanomizer. Among them, a bead mill is preferably used. Examples of such bead mills include Super Mill, Sand Grinder, Agitator Mill, Glen Mill, Dyno Mill, Pearl Mill, and Kobol Mill (all are trade names).

[0059] In the present disclosure, from the viewpoint of the storage stability of the dispersion, it is preferable to use a dispersant for the dispersion treatment of the colorant (B). In the present disclosure, the dispersant has a function of imparting a repulsive force between particles so that the particles divided through the above-described dispersion treatment do not aggregate again. As the dispersant, conventionally known compounds can be used, and examples thereof include cationic, anionic, or nonionic surfactants, cationic, anionic, or nonionic polymer dispersants, and pigment derivative type dispersants. From the viewpoint of the storage stability of the dispersion, pigment derivative type dispersants are preferable.

[0060] The pigment-induced type dispersant is a compound having an acidic group, a basic group, a neutral group, etc. in an organic dye residue. For example, compounds having an acidic substituent such as a sulfo group, a carboxyl group, or a phosphate group, as well as amine salts thereof, compounds having a basic substituent such as a sulfonamide group, an amide group, or a tertiary amino group at the terminal, and compounds having a neutral substituent such as a phenyl group or a phthalimide alkyl group can be mentioned. Organic dyes include, for example, phthalocyanine-based pigments, diketopyrrolopyrrole-based pigments, anthraquinone-based pigments, quinacridone-based pigments, dioxazine-based pigments, perinone-based pigments, perylene-based pigments, thiazine indigo-based pigments, triazine-based pigments, benzimidazolone-based pigments, indole-based pigments such as benzisoindole, isoindoline-based pigments, isoindolinone-based pigments, quinophthalone-based pigments, naphthol-based pigments, fluorene-based pigments, metal complex-based pigments, azo pigments such as azo, disazo, and polyazo, etc. By using these pigment dispersants, it is possible to prevent the aggregation over time of the colorant (B) contained in the resin composition and maintain good light-shielding properties.

[0061] The content rate of the pigment dispersant (when two or more types are included, the total content rate) is preferably 0.01 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total amount (100% by mass) of the resin composition layer. By containing 0.01% by mass or more of the pigment dispersant, the light-shielding property becomes good, and by being 10% by mass or less, the viscosity of the black dispersion becomes in a suitable range and the coating suitability becomes good.

[0062] [Polymerization initiator (C)] In this embodiment, either a photoinitiator or a thermal initiator can be used, and it is preferable to use a thermal initiator from the viewpoints of the film-forming property and adhesion of the resin composition layer. When using either a photoinitiator or a thermal initiator, the resin (A) preferably has one or more radical polymerizable functional groups as functional groups in one molecule. Examples of the radical polymerizable functional group include, for example, (meth)acryloyl group, N-vinyl group, vinyl ether group, allyl group, unsaturated carboxylic acid group, etc.

[0063] Examples of the photopolymerization initiator include triazine-based photopolymerization initiators, borate-based photopolymerization initiators, carbazole-based photopolymerization initiators, acetophenone-based photopolymerization initiators, and oxime ester-based photopolymerization initiators. Acetophenone-based photopolymerization initiators and oxime ester-based photopolymerization initiators are preferred because they cause less yellowing during the heat aging process. From the viewpoint of yellowing, the content of the photopolymerization initiator is preferably 0.5 to 10% by mass, more preferably 0.5 to 5% by mass, based on the total amount (100% by mass) of the resin composition layer.

[0064] In this embodiment, a thermal cationic polymerization initiator or a thermal radical polymerization initiator can be used as the thermal polymerization initiator. From the viewpoint of the storage stability of the resin composition layer, a thermal radical polymerization initiator is preferred. The thermal cationic polymerization initiator has a function of generating ions by heat. Examples of the thermal cationic polymerization initiator include sulfonium cations, quaternary ammonium cations, and iodonium cations as the cation component. Examples of the anion component include antimony hexafluoride anion, phosphorus hexafluoride anion, tetrakis(pentafluorophenyl)borate anion, and trifluoromethanesulfonic acid. The thermal radical polymerization initiator has a function of generating radicals by heat. Examples of the thermal radical polymerization initiator include organic peroxide polymerization initiators and azo thermal polymerization initiators.

[0065] Examples of the organic peroxide polymerization initiator include dialkyl peroxides such as diacetyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, dicumyl peroxide, t-butyl cumyl peroxide, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexine-3, 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, 1,3-bis(t-butylperoxyisopropyl)hexane, and (2-ethylhexanoyl)(t-butyl) peroxide; Peroxy esters such as dipropionyl peroxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, bis(3,5,5-trimethylhexanoyl)peroxide, 1,1,3,3-tetramethylbutyl peroxyneodecanoate, α-cumyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butyl peroxyneoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, di-t-butyl peroxyhexahydroterephthalate, 1,1,3,3-tetramethylbutyl peroxy-3,5,5-trimethylhexanoate, t-amyl peroxy 3,5,5-trimethylhexanoate, t-butyl peroxy-3,5,5-trimethylhexanoate, dibutyl peroxytrimethyladipate, 2,5-dimethyl-2,5-di-2-ethylhexanoylperoxyhexane, t-hexyl peroxy-2-ethylhexanoate, t-hexyl peroxyl isopropyl monocarbonate, t-butyl peroxylaurate, t-butyl peroxyl isopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl monocarbonate; Ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetylacetone peroxide, cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, t-butyl benzoate, pivaloyl t-butyl peroxide; Peroxyketals such as 2,2-bis(t-butylperoxy)butane, 2,2-bis(4,4-di-t-butylperoxycyclohexyl)propane, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane, 1,1-bis(t-hexylperoxy)cyclohexane, butyl 4,4-bis(t-butylperoxy)pentanoate; Hydroperoxides such as t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylcyclohexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, p-menthane hydroperoxide; Diacyl peroxides such as dibenzoyl peroxide, didecanoyl peroxide, dilauroyl peroxide, diisobutyryl peroxide, bis-3,5,5-trimethylhexanol peroxide, m-toluoylbenzoyl peroxide, succinic peroxide, 2,4-dichlorobenzoyl peroxide; Peroxydicarbonates such as bis(t-butylcyclohexyl) peroxydicarbonate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyisopropyl carbonate, di-2-ethylhexyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di-3-methoxybutyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, t-amyl peroxyisopropyl carbonate, t-butyl peroxy-2-ethylhexyl carbonate, 6-bis(t-butylperoxycarbonyloxy)hexane and the like, but not limited thereto. From the viewpoint of storage stability, dialkyl peroxides are preferred, and di-t-butyl peroxide is more preferred.

[0066] Examples of azo thermal polymerization initiators include 2,2'-azobisbutyronitrile such as 2,2'-azobisisobutyronitrile and 2,2'-azobis(2-methylbutyronitrile); 2,2'-azobisvaleronitrile such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), and 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile); 1,1'-azobis-1-alkanenitrile such as 1,1'-azobis(cyclohexane-1-carbonitrile); 2,2'-azobispropionitrile such as 2,2'-azobis(2-hydroxymethylpropionitrile) and 2,2'-azobis(2-hydroxymethylpropionitrile); 2,2'-azobispropionamide such as 2,2'-azobis(N-butyl-2-methylpropionamide) and 2,2'-azobis(N-cyclohexyl-2-methylpropionamide); Other examples include dimethyl 2,2'-azobis(2-methylpropionate), 2,2'-azobis[2-(2-imidazolin-2-yl)propane], and 1-[(1-cyano-1-methylethyl)azo]formamide; Examples of azo compounds having a carboxyl group or a hydroxyl group include, but are not limited to, 4,4'-azobis(4-cyanopentanoic acid), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-methyl-N-(2-hydroxyethyl)propionamide), 2,2'-azobis(N-(carboxyethyl)-2-methylpropionamidine) tetrahydrate, etc. From the viewpoint of storage stability, 2,2'-azobispropionamides are preferred, and 2,2'-azobis(N-butyl-2-methylpropionamide) is more preferred.

[0067] The 10-hour half-life temperature of the thermal radical polymerization initiator is preferably 60 to 200°C, more preferably 80 to 180°C, still more preferably 100 to 150°C, and most preferably 105 to 130°C. By setting it at 60°C or higher, the storage stability of the resin composition layer can be improved, and by setting it at 200°C or lower, the heating aging process of the sealing layer can be shortened.

[0068] The 10-hour half-life temperature is the temperature at which the thermal polymerization initiator decreases to half of its initial value after 10 hours due to thermal decomposition. Specifically, a thermal polymerization initiator solution is prepared using a solvent inert to the radicals of the thermal polymerization initiator, and sealed in a glass tube that has been purged with nitrogen. This is immersed in a constant temperature layer set at a predetermined temperature for 10 hours for thermal decomposition, and the amount of the remaining thermal polymerization initiator is measured. By performing this series of operations at several temperatures and plotting, the half-life can be obtained from the resulting straight line.

[0069] The content of the thermal radical polymerization initiator is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, and still more preferably 0.1 to 5% by mass based on the total amount (100% by mass) of the resin composition layer. By setting the above content, the adhesion can be suitably adjusted.

[0070] [Other Components] The resin composition layer of the present disclosure may contain other components as long as the object of the present disclosure is not impaired. For example, a crosslinking agent, a monomer, an inorganic filler, a surface conditioning additive, a curing accelerator, a curing retarder, a softening agent, an antistatic agent, a lubricant, an antiblocking agent, an adhesion improver, etc. can be added. From the viewpoint of controlling the film-forming property of the resin composition layer, it is preferable to contain a crosslinking agent and a monomer.

[0071] Examples of the inorganic filler include inorganic compounds such as silica, alumina, magnesium hydroxide, barium sulfate, calcium carbonate, titanium oxide, zinc oxide, antimony trioxide, magnesium oxide, zirconium oxide, talc, kaolinite, mica, basic magnesium carbonate, sericite, montmorillonite, kaolinite, bentonite, boron nitride, aluminum nitride, titanium nitride, etc. Among these, from the viewpoint of the coating film resistance to scratches, titanium oxide, titanium nitride, silica, and zirconium oxide are preferable.

[0072] The curing accelerator may be contained to adjust the crosslinking rate of the resin composition layer of the present disclosure. The curing accelerator is not particularly limited and can be appropriately selected. Specific examples of the curing accelerator include, for example, amine-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators.

[0073] [Crosslinking agent] The resin composition layer of the present disclosure may contain a crosslinking agent. The crosslinking agent enhances the cohesive force of the resin composition layer and improves the adhesion by undergoing a crosslinking reaction with the reactive functional groups of the resin (A) during hot pressing or heat aging in the pressing process. The crosslinking agent has a plurality of functional groups capable of reacting with the functional groups of the resin (A). Examples of the crosslinking agent include known compounds such as silane coupling agents, acid anhydride group-containing compounds, imidazole compounds, isocyanate compounds, aziridine compounds, and amine compounds. From the viewpoint of adjusting the loss tangent (tanδ) of the resin composition layer, silane coupling agents, aziridine compounds, and imidazole compounds are preferable.

[0074] Examples of the aziridine compound include trimethylolpropane tris[3-(aziridin-1-yl)propionate], tetramethylolmethane-tri-β-aziridinylpropionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane, etc.

[0075] The imidazole compounds include imidazole compounds such as 2-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-dimethylimidazole, 2-phenylimidazole, imidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2-phenylimidazole isocyanurate adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, etc. Further, compounds with improved storage stability such as those in which the imidazole compound is encapsulated in microcapsules are included.

[0076] The isocyanate compound is an isocyanate having two or more isocyanate groups. Preferred isocyanate compounds are, for example, isocyanate monomers such as aromatic polyisocyanates, aliphatic polyisocyanates, araliphatic polyisocyanates, alicyclic polyisocyanates, and their burette forms, nurate forms, and adduct forms. From the perspective of forming a sufficient cross-linked structure, a trifunctional isocyanate compound is preferred. More preferably, the isocyanate compound is an adduct obtained by reacting an isocyanate monomer with a trifunctional low-molecular-weight active hydrogen-containing compound, or a nurate. Preferred isocyanate compounds include trimethylolpropane adducts of hexamethylene diisocyanate, nurates of hexamethylene diisocyanate, trimethylolpropane adducts of tolylene diisocyanate, nurates of tolylene diisocyanate, trimethylolpropane adducts of isophorone diisocyanate, and nurates of isophorone diisocyanate. More preferred are trimethylolpropane adducts of hexamethylene diisocyanate, trimethylolpropane adducts of tolylene diisocyanate, and trimethylolpropane adducts of isophorone diisocyanate.

[0077] The silane coupling agent is a compound in which a hydrolyzable group such as a methoxy group or an ethoxy group and a functional group such as an epoxy group are bonded to an Si atom via an alkylene group. Examples of the silane coupling agent include alkoxysilane compounds having a (meth)acryloxy group such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltripropoxysilane, 3-(meth)acryloxypropyltributoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, and 3-(meth)acryloxypropylmethyldiethoxysilane; alkoxysilane compounds having a vinyl group such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltributoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; Alkoxysilane compounds having an amino group such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltripropoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane; Alkoxysilane compounds having a mercapto group such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropylmethyldiethoxysilane; Alkoxysilane compounds having one epoxy group such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyltripropoxysilane, 3-glycidoxypropyltributoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; Tetraalkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane; 3-chloropropyltrimethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-decyltrimethoxysilane, n-decyltriethoxysilane, styryltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, 1,3,5-tris(3-trimethoxysilylpropyl)isocyanurate, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, hexamethyldisilazane, silicone resins having an alkoxysilyl group in the molecule, and the like can be mentioned. From the viewpoint of adhesion, alkoxysilane compounds are preferred, and 3-glycidoxypropyltrimethoxysilane is more preferred.

[0078] The content rate of the crosslinking agent is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and further preferably 0.1 to 10% by mass based on the total amount (100% by mass) of the resin composition layer. By setting the above content rate, the adhesion can be suitably adjusted.

[0079] [Monomer] In the present embodiment, the monomer means a compound having a radically polymerizable functional group as the minimum structural unit for constituting the polymer. Examples of the radically polymerizable functional group include (meth)acryloyl group, N-vinyl group, vinyl ether group, allyl group, unsaturated carboxylic acid group, and the like. Further, the monomer may be a monofunctional monomer or a polyfunctional monomer. In this specification, "monofunctional" refers to a compound having only one radically polymerizable functional group in one molecule, and "bifunctional" and "trifunctional" refer to compounds having two and three radically polymerizable functional groups in one molecule, respectively. In this specification, bifunctional or higher is also collectively referred to as "polyfunctional". By containing the monomer, the film-forming property of the resin composition layer can be adjusted and the adhesion becomes good.

[0080] Specific examples of the monomer include, but are not limited to, monofunctional (meth)acrylate monomers having one (meth)acryloyl group in the molecule, monofunctional vinyl monomers having one N-vinyl group in the molecule, bifunctional (meth)acrylate monomers having two (meth)acryloyl groups in the molecule, bifunctional (meth)acrylate monomers having one (meth)acryloyl group and one allyl group in the molecule, trifunctional (meth)acrylate monomers having three (meth)acryloyl groups in the molecule, tetrafunctional (meth)acrylate monomers having four acryloyl groups in the molecule, pentafunctional (meth)acrylate monomers having five (meth)acryloyl groups in the molecule, hexafunctional (meth)acrylate monomers having six (meth)acryloyl groups in the molecule, and the like.

[0081] Among them, from the viewpoint of adhesion, it is preferably included 3-((meth)acryloyloxy)propyltrimethoxysilane and 3-((meth)acryloyloxy)propyltriethoxysilane.

[0082] The content of the monomer is preferably 0.01 to 30% by mass, more preferably 0.05 to 20% by mass, and even more preferably 0.1 to 15% by mass, based on the total amount (100% by mass) of the resin composition layer. By setting the above content, the adhesion can be suitably adjusted.

Examples

[0083] Hereinafter, the present disclosure will be specifically described by way of examples and comparative examples, but the present disclosure is not particularly limited to the examples. In the following description, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0084] (a) Measurement method The numerical values obtained in this example are the values obtained by the following methods.

[0085] [Weight average molecular weight (Mw)] The weight-average molecular weight (Mw) was determined by using a GPC "LC-GPC system" manufactured by Shimadzu Corporation and converting it with polystyrene of known molecular weight as a standard substance to obtain the weight-average molecular weight (Mw). Apparatus name: "Prominence", an LC-GPC system manufactured by Shimadzu Corporation Columns: Four GMHXL columns manufactured by Tosoh Corporation and one HXL-H column manufactured by Tosoh Corporation were connected. Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 mL / min Column temperature: 40 °C

[0086] [Solid content] The mass (W0) of the aluminum cup was measured with an analytical balance. Next, about 1 g of the sample was put into the aluminum cup, and the mass (W1) of the sample in the aluminum cup was measured with an analytical balance. The sample in the aluminum cup was heated in an oven at 150 °C for 120 minutes, then taken out of the oven and returned to room temperature. The residual mass (W2) of the sample in the aluminum cup after heating was measured with an analytical balance. And the solid content was calculated by the formula of (W2 - W0) / (W1 - W0) × 100 (%).

[0087] [Thickness Tt of the sealing sheet, thickness Ta of the resin composition layer, thickness Tl of the first film, thickness Th of the second film] Ten equally spaced points from one end to the other end in the width direction of the sealing sheet cut to a size of 10 cm × 10 cm were determined, and the thicknesses at those 10 points were measured, and the average value was taken as the thickness Tt of the sealing sheet. Next, the first film was peeled off from the sealing sheet, and the thicknesses of the peeled first films at 10 points corresponding to the same positions as described above were measured. The average value was taken as Tl. Then, further, the second film was peeled off from the resin composition layer, and the thicknesses of the peeled second films at 10 points corresponding to the same positions as described above were measured. The average value was taken as Th. The thickness Ta of the resin composition layer was determined by the formula Ta = Tt - Tl - Th. The thickness was measured using MH-15M (manufactured by Nikon Corporation).

[0088] [Loss tangent (tanδ) of the resin composition layer] A sealing sheet prepared such that the thickness Ta of the resin composition layer is 50 μm was cut into a size of 0.5 cm × 2 cm. The first film and the second film were peeled off, and the obtained resin composition layer was measured for dynamic viscoelasticity using a dynamic viscoelasticity measuring device DVA-200 / L2 (manufactured by IT Measurement & Control Co., Ltd.) at a frequency of 10 Hz, a measurement temperature range of -50 to 150 °C, a heating rate of 5 °C / min, and in a tensile mode, and the loss tangent (tanδ) was plotted. From the obtained graph, the maximum value of the loss tangent (tanδ maximum value), the loss tangent at 40 °C (tanδ40 °C), and the peak top temperature of the loss tangent (tanδ peak temperature) were read.

[0089] [Young's modulus of the second film] The second film was measured for a stress-strain curve using a tensile testing machine "EZ Tester" (manufactured by Shimadzu Corporation) under the conditions of 23 °C, 50% relative humidity, a tensile rate of 50 mm / min, and a gauge length of 25 mm, and the linear regression (slope) in the region where the strain (elongation) was 0.1 to 0.3% was taken as the Young's modulus.

[0090] [Pencil hardness] After peeling off the first film of the sealing sheet, the surface of the exposed resin composition layer was measured according to the test method of JIS K 5600-5-4. The pencil used was a pencil for pencil hardness test (manufactured by Mitsubishi Pencil Co., Ltd.).

[0091] (b) Production of the solution of resin (A) [Production example of the solution of (meth)acrylic resin (a1) (A-1)] Into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube (hereinafter simply referred to as "reaction vessel"), 80 parts of ethyl acetate, 13 parts of n-butyl acrylate, 85 parts of n-butyl methacrylate, 2 parts of methacrylic acid, and 0.1 part of 2,2'-azobisisobutyronitrile as an initiator were charged, and the atmosphere in this reaction vessel was replaced with nitrogen gas. Then, while stirring under a nitrogen atmosphere, it was heated to 65 °C to start the reaction. Thereafter, the reaction solution was reacted at 65 °C for 4 hours. After completion of the reaction, it was cooled and diluted with ethyl acetate to obtain a solution of (meth)acrylic resin (a1) (A-1) having a weight average molecular weight (Mw) of 100,000 and a solid content of 25%.

[0092] [Production Example of Solution of (Meth)acrylic Resin (a1)(A-2)] The (meth)acrylic resin (a1)(A-2) was produced in the same manner as the production of the (meth)acrylic resin (a1)(A-1), except that the blending amounts of the monomers were changed to 20 parts of n-butyl acrylate, 70 parts of n-butyl methacrylate, 5 parts of methacrylic acid, and glycidyl methacrylate. Incidentally, the weight average molecular weight (Mw) was 130,000 and the solid content was 25%.

[0093] [Production Example of Solution of (Meth)acrylic Resin (a1)(A-3)] KRM8912 (manufactured by Daicel Ornex Co., Ltd.) was diluted with ethyl acetate to produce the (meth)acrylic resin (a1)(A-3). Incidentally, the weight average molecular weight (Mw) was 1,000 and the solid content was 25%.

[0094] [Production Example of Solution of Urethane Resin (a2)(A-4)] ART RESIN UN-9000PEP (manufactured by Negami Kogyo Co., Ltd.) was diluted with ethyl acetate to produce the urethane resin (a2)(A-4). Incidentally, the weight average molecular weight (Mw) was 5,000 and the solid content was 25%.

[0095] [Production Example of Solution of Epoxy Resin (a3)(A-5)] jER256B40 (manufactured by Mitsubishi Chemical Corporation) was diluted with ethyl acetate to produce the epoxy resin (a3)(A-5). Incidentally, the weight average molecular weight (Mw) was 45,000 and the solid content was 25%. (c) Production of Dispersion of Colorant (B)

[0096] [Production Example of Dispersion (D-1) of Colorant (B)] 800 parts of the solution of resin (A-1), 800 parts of carbon black MA100 (manufactured by Mitsubishi Chemical Corporation) as the colorant (B-1), and 400 parts of methyl ethyl ketone as the solvent were mixed and preliminarily dispersed with a disper, and then subjected to main dispersion for 2 hours using a Dyno-Mill with a volume of 0.6 L filled with 1800 g of zirconia beads having a diameter of 1.0 mm to obtain the dispersion (D-1).

[0097] [Production Example of Dispersion (D-2) of Colorant (B)] Solution of resin (A-2): 800 parts, carbon black MA100 (manufactured by Mitsubishi Chemical Corporation) as colorant (B-1): 800 parts, methyl ethyl ketone as solvent: 400 parts, Solsperse 5000 (manufactured by Lubrizol Corporation) as pigment derivative type dispersant: 2 parts were mixed, preliminarily dispersed with a disper, and then subjected to main dispersion for 2 hours using a 0.6 L dyno mill filled with 1800 g of zirconia beads with a diameter of 1.0 mm to obtain dispersion (D-2).

[0098] [Production Example of Dispersion (D-3) of Colorant (B)] Solution of resin (A-1): 800 parts, Black 6340 (manufactured by Asahi Kasei Chemicals Corporation), a metal oxide pigment, as colorant (B-2): 800 parts, methyl ethyl ketone as solvent: 400 parts were mixed, preliminarily dispersed with a disper, and then subjected to main dispersion for 2 hours using a 0.6 L dyno mill filled with 1800 g of zirconia beads with a diameter of 1.0 mm to obtain dispersion (D-3).

[0099] (d) Production of Resin Composition [Production Example of Resin Composition of Example 1] Dispersion (D-1): 60 parts (24 parts of colorant (B-1), 6 parts of resin (A-1), 30 parts of solvent), solution of resin (A-1): 276 parts (69 parts of resin (A-1), 207 parts of solvent), Kemite PZ-33 (manufactured by Nippon Shokubai Co., Ltd.), an aziridine compound, as other component: 1 part, toluene as solvent: 63 parts were sequentially added while stirring with a disper, and stirred until thoroughly uniform. Subsequently, filtration was performed with a membrane filter having a pore diameter of 10 μm to remove coarse foreign matters that cause coating unevenness, and a resin composition with a non-volatile content of 33% was obtained. Note that the other component was the solid content converted amount.

[0100] (e) Production of Sealing Sheet [Production Example of Sealing Sheet of Example 1] The resin composition was applied onto the release layer of SP-PET-O3-BU (manufactured by Mitsui Chemicals Toatsu Chemicals, Inc.) as a second film (H-2) with a thickness of 50 μm so that the thickness after drying would be 20 μm, and dried in a hot air oven at 100°C for 3 minutes to form a resin composition layer. Next, the release layer side of (L-2) SP-PET-O1-T (manufactured by Mitsui Chemicals Toatsu Chemicals, Inc.) as a first film with a thickness of 25 μm was bonded to the exposed resin composition layer, and aged at 0°C for 7 days to obtain a sealing sheet of Example 1 laminated in the order of the first film / resin composition layer / second film. The tanδ peak temperature was 29°C.

[0101] (f) Evaluation method of the sealing sheet [Embeddability] A test substrate (a plate with a width of 200 μm for the concave part, a height of 5 μm for the convex part, and a width of 200 μm for the convex part formed on one surface of a glass plate with a size of 25 mm × 25 mm) simulating the unevenness of the micro-LED substrate was prepared. A schematic cross-sectional view of the test substrate is shown in Figure 3. The sealing sheet was cut into a size of 30 mm × 30 mm, the first film was peeled off to expose the resin composition layer, and the resin composition layer was placed on the surface of the test substrate where the uneven parts were formed. Then, as a cushion material on the second film, TPX with a thickness of 50 μm (Opulan X-44B, manufactured by Mitsui Chemicals Toatsu Chemicals, Inc.) and a PVC film with a thickness of 2.0 mm (Celeb T, manufactured by Okamoto Co., Ltd.) were laminated in order, and further, a cardboard was laminated to prevent sticking. The laminate consisting of the glass substrate / resin composition layer / second film / cushion material (TPX / PVC film) / cardboard was pressed from above against the substrate surface under the conditions of 5 MPa and 100°C for 20 minutes to fill the concave part of the test substrate with the resin composition layer, thereby forming a sealing layer. After pressing, the cushion material and the cardboard were peeled off. The sealing layer protruding from the side surface of the obtained test substrate with a sealing layer was roughly removed using a cutter, and further smoothed to remove the sealing layer remaining on the side surface of the test substrate with a sealing layer, exposing the side surface of the test substrate, so that the uneven portions could be observed. For the concave portions of any 15 test substrates, the embedability was evaluated by observing with a microscope. In the concave portion of the test substrate, when the maximum gap between the sealing layer and the test substrate was 1 μm or less, it was considered that the groove was embedded. The evaluation criteria were as follows. A: 14 or more embedded grooves B: 13 or less and 11 or more embedded grooves C: 10 or less and 8 or more embedded grooves D: 7 or less embedded grooves

[0102] [Die shift property] A wired LED (SMD, 0402, outer dimension 1.0 × 0.5 mm) was placed on a glass epoxy universal substrate (width 32 mm × depth 53 mm × thickness 1.2 mm, pitch 2.54 mm). After confirming the energization of the LED, it was used as a test substrate. The sealing sheet was cut into a size of 60 mm × 60 mm, the first film was peeled off to expose the resin composition layer, and it was placed so that the resin composition layer was in contact with the LED arranged on the test substrate. Then, as a cushion material on the second film, a 50-μm-thick TPX (Opulran X-44B, manufactured by Mitsui Chemicals Toagosei Co., Ltd.) and a 2.0-mm-thick vinyl chloride film (Celeb T, manufactured by Okamoto Corporation) were laminated in order, and further a cardboard was laminated to prevent sticking. The laminate had a structure of glass substrate / resin composition layer / second film / cushion material (TPX / vinyl chloride film) / cardboard. Next, the test piece was pressed from above under the conditions of 5 MPa and 100 °C for 20 minutes with respect to the substrate surface, and the resin composition layer was filled around the LED to form a sealing layer. After pressing, the cushion material and the cardboard were peeled off. For the obtained test piece after pressing, the energization of the LED was confirmed using an energization tester. Those that did not energize were considered to have a wiring shift due to die shift during embedding and were evaluated as having a wiring shift. This evaluation was carried out 10 times, and the evaluation criteria were as follows. A: There is wiring misalignment 0 to 1 time B: There is wiring misalignment 2 times C: There is wiring misalignment 3 times D: There is wiring misalignment 4 to 10 times

[0103] [Light-shielding property] The first film and the second film of the sealing sheet were peeled off to expose the resin composition layer. The optical density (visual) of the resin composition layer was measured using an optical densitometer (361T desktop transmission densitometer, manufactured by X-RITE). The evaluation criteria were as follows. A: The optical density is 6 or more B: The optical density is 4 or more and less than 6 C: The optical density is less than 4

[0104] [Adhesion] One piece of the sealing sheet cut into 25 mm × 100 mm was prepared, the first film was peeled off to expose the resin composition layer, and it was placed on a glass plate (25 mm × 100 mm × 1.1 mm, blue plate glass, manufactured by Kawamura Kuzo Shoten). Then, as a cushion material on the second film, TPX with a thickness of 50 μm (Opulran X-44B, manufactured by Mitsui Chemicals Tohcellulose Co., Ltd.) and a PVC film with a thickness of 2.0 mm (Celeb T, manufactured by Okamoto Co., Ltd.) were laminated in order, and further, a cardboard was laminated to prevent sticking. The laminate composed of the glass plate / resin composition layer / second film / cushion material (TPX / PVC film) / cardboard was pressed from above against the substrate surface at 5 MPa and 100 °C for 20 minutes to crimp the glass plate and the resin composition layer, and a sealing layer was formed on the glass plate. After pressing, the cushion material, cardboard, and second film were peeled off. A test piece composed of the glass plate and the sealing layer was allowed to stand at 180 °C for 120 minutes to prepare a test piece in which the glass plate and the sealing layer were adhered. In accordance with JIS K 5600-5-6 (cross-cut method), using a cross-cut guide and a cutter knife, a 1 mm square right-angle grid pattern (25 squares) was created on the sealing layer of the test piece. An adhesive tape (CT1835, manufactured by Nichiban Co., Ltd.) was pasted onto the grid-cut portion and firmly adhered to the sealing layer. It was peeled off at an angle close to 60° within 5 minutes after adhesion, taking 0.5 to 1.0 seconds. The state of the peeled sealing layer was observed to evaluate the adhesion. The evaluation criteria were as follows. Also, when the sealing layer and the glass plate were peeled off when peeling the second film, it was rated as C. A: Number of peeled squares is 0 B: Number of peeled squares is 1 - 2 C: Number of peeled squares is 3 - 25

[0105] For any of the above evaluations, the best evaluation was rated as A, the next best as B, followed by a good evaluation as C, and an evaluation that did not meet the target performance as D. Note that those with all performance evaluations of A - C are applicable to this disclosure.

[0106] [Examples 2 - 25], [Comparative Examples 1 - 8] Sealing sheets were prepared in the same manner as in Example 1, except that the content ratios and thickness Ta shown in Tables 1 - 3 were changed, and evaluated in the same way. Note that all other components were added simultaneously. In Tables 1 - 3, resin (A), colorant (B), polymerization initiator (C), and other components are amounts in terms of solid content, and blanks indicate non-blending. Note that the tanδ peak temperature of Example 2 was 22°C.

[0107] The abbreviations in the table are as follows. C-1: Di-t-butyl peroxide (Perbutyl D, manufactured by NOF Corporation) C-2: 2,2’-Azobis(N-butyl-2-methylpropionamide) (VAm-110, manufactured by Fujifilm Wako Pure Chemical Corporation) O-1: Aziridine compound as a crosslinking agent (Chemitite PZ-33, manufactured by Nippon Shokubai Co., Ltd.) O-2: Silane coupling agent as a crosslinking agent (KBE-403, manufactured by Shin-Etsu Silicone Co., Ltd.) O-3: 2-Phenylimidazole (Curezol 2PZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.) as a crosslinking agent O-4: EO-modified (3) trimethylolpropane triacrylate (Miramer M3130, manufactured by MIWON Co., Ltd., trifunctional) as a monomer O-5: 3-Methacryloxypropyltrimethoxysilane (KBE-503, manufactured by Shin-Etsu Silicone Co., Ltd., monofunctional) as a monomer L-1: First film with a thickness of 10 μm (mat film (type M3), manufactured by AIM Co., Ltd., Sq: 1.5 μm) L-2: First film with a thickness of 25 μm (SP-PET-O1-T, manufactured by Mitsui Chemicals Toatsu Co., Ltd., Sq: 0.2 μm) L-3: First film with a thickness of 50 μm (mat film (type M3), manufactured by AIM Co., Ltd., Sq: 1.5 μm) L-4: First film with a thickness of 100 μm (SP-PET-O1-T, manufactured by Mitsui Chemicals Toatsu Co., Ltd., Sq: 0.2 μm) H-1: Second film with a thickness of 12 μm (Torayfan high-end OPP film, manufactured by Toray Industries, Inc., Young's modulus: 3.5 GPa) H-2: Second film with a thickness of 50 μm (SP-PET-O3-BU, manufactured by Mitsui Chemicals Toatsu Co., Ltd., Young's modulus: 4.7 GPa) H-3: Second film with a thickness of 100 μm (release film PE, manufactured by AIM Co., Ltd., Young's modulus: 1.1 GPa) H-4: Second film with a thickness of 188 μm (Cosmopeel E7004, manufactured by Toyobo Co., Ltd., Young's modulus: 5.9 GPa) H-5: Second film with a thickness of 6 μm (Lumirror F53, manufactured by Toray Industries, Inc., Young's modulus: 4.4 GPa) H-6: Second film with a thickness of 250 μm (Lumirror T60, manufactured by Toray Industries, Inc., Young's modulus: 4.8 GPa)

[0108]

Table 1

[0109]

Table 2

[0110]

Table 3

[0111] In the present disclosure, in the case of a sealing sheet where the thickness Ta of the resin composition layer is outside the range of 2 to 100 μm and the relationship of 0.1 ≦ Ta / Th ≦ 2 between Ta and the thickness Th of the second film is not satisfied, as shown in Comparative Examples 1 to 2, it can be seen that there are problems in embedability and die shift properties. Further, in the case of a sealing sheet where the thickness Th of the second film is outside the range of 12 to 188 μm and the relationship of 0.1 ≦ Ta / Th ≦ 2 is not satisfied, as shown in Comparative Examples 3 to 4, it can be seen that there are problems in embedability and die shift properties. Further, in the case of a sealing sheet where the relationship of 0.1 ≦ Ta / Th ≦ 2 is not satisfied, as shown in Comparative Examples 5 to 6, it can be seen that there are problems in one or more of embedability and die shift properties. Further, when the maximum value (tan δ maximum value) in the range of -50 to 80 °C of the loss tangent obtained by dynamic viscoelasticity measurement of the resin composition layer is outside the range of 0.6 to 2.2, as shown in Comparative Examples 7 to 8, it can be seen that there is a problem in either embedability or die shift property. As shown in Table 3, the sealing sheets of Comparative Examples 1 to 8 could not satisfy embedability and die shift properties at a high level with good balance. On the other hand, according to Examples 1 to 25, the sealing sheet of the present disclosure exhibits excellent embedability as described in Tables 1 to 3 and is also excellent in die shift property. Further, since the sealing sheet of the present disclosure is also excellent in light shielding property and adhesion, it prevents light leakage caused by insufficient light shielding power and light leakage from the gap of the sealing layer caused by poor adhesion, and it has been found that the sealing sheet is excellent in light control property that ensures the visibility of the display.

Explanation of Signs

[0112] 1: Sealing sheet 2: Resin composition layer 3: First film 4: Second film 5: Light-emitting element 6: Substrate 7: Glass substrate

Claims

1. A sealing sheet for sealing a micro-LED used in a display having the micro-LED as a light source, wherein the sealing sheet has a first film, a resin composition layer, and a second film arranged in this order, the first film has a release layer on the surface facing the resin composition layer, the thickness Ta of the resin composition layer is 2 to 100 μm, the thickness Th of the second film is 12 to 188 μm, Ta and Th satisfy formula (1), and the maximum value of the loss tangent in the range of -50 to 80 °C obtained by dynamic viscoelasticity measurement of the resin composition layer is 0.6 to 2.

2. Formula (1) 0.1 ≦ Ta / Th ≦ 2

2. The sealing sheet according to claim 1, wherein the Young's modulus of the second film is 1 to 6 GPa.

3. The sealing sheet according to claim 1, wherein the ratio of the root mean square height Sq defined by ISO 25178 on the surface of the first film in contact with the resin composition layer to the thickness Ta of the resin composition layer is 30% or less.

4. The sealing sheet according to claim 1, wherein the pencil hardness of the resin composition layer is 5B to 2H.

5. the resin composition layer contains a resin (A), the resin (A) contains at least one selected from the group consisting of an acrylic resin (a1), a urethane resin (a2), and an epoxy resin (a3). The sealing sheet according to any one of claims 1 to 4.

6. The sealing sheet according to claim 5, wherein the resin composition layer contains a colorant (B).

7. The sealing sheet according to claim 6, wherein the resin composition layer contains a polymerization initiator (C).

8. A display having a micro-LED as a light source and having a resin composition layer of the sealing sheet according to claim 5.

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