Adhesive sheet

Abstract

The present application provides an adhesive sheet having an increased refractive index. The adhesive sheet provided by the present application has an adhesive layer. The adhesive layer contains particles P HRI . In addition, the average particle diameter of the particles P HRI present in the above-mentioned adhesive layer is less than 100 nm, and the standard deviation is 20 nm or less. Here, the average particle diameter and the standard deviation are the average particle diameter and the standard deviation, respectively, calculated from the number-based particle size distribution based on TEM observation.

Description

TECHNICAL FIELD

[0001] The present application relates to an adhesive sheet. This application claims priority based on Japanese Patent Application No. 2020-15790 filed on January 31, 2020, the entire contents of which are incorporated herein by reference. BACKGROUND

[0002] Generally, an adhesive (also referred to as a pressure-sensitive adhesive. The same applies hereinafter.) exhibits a state of a soft solid (a viscoelastic body) in a temperature range around room temperature, and has a property of easily adhering to an adherend by pressure. Exploiting such a property, an adhesive is widely used for the purpose of joining, fixing, protecting, and the like of members in a portable electronic device such as a mobile phone. For example, in a portable electronic device such as a mobile phone, a tape substrate having an adhesive layer with a light-shielding property is used for the purpose of preventing light leakage from a light source such as a backlight module of a liquid crystal display device, a self-luminous element such as an organic EL (electroluminescence), and the like, reducing reflection, and the like. As a document related to such a technology, Patent Literature 1 can be cited. In addition, an adhesive sheet attached to a polarizing film of a liquid crystal display device or the like is disclosed in Patent Literatures 2 and 3.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2017-57375

[0006] Patent Literature 2: International Publication No. 2015 / 108159

[0007] Patent Literature 3: Japanese Patent Application Publication No. 2019-196468 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] In the above-described various devices such as a portable electronic device, for the purpose of operation of the device, sensing of an approaching object, detection of brightness (ambient light) of the surroundings, data communication, and the like, a light sensor using light rays such as infrared rays, visible light, ultraviolet rays, and the like is used. The light rays used in the light sensor transmit through the material constituting the device to exert a target function, but if the light rays are shielded by reflection or the like in the above-described device, the operation accuracy of the sensor is affected, or becomes a cause of poor response of the sensor. With respect to an adhesive sheet used in the above-described device, when the refractive index difference with a member to which the adhesive sheet is attached is large, reflection of the light rays can occur at the interface thereof, and adversely affect the operation accuracy of the light sensor.

[0010] For example, in the case of adhering an adhesive sheet to a member having a higher refractive index than the adhesive, the refractive index of the adhesive sheet can be increased by containing particles capable of increasing the refractive index (high-refractive-index particles) in the adhesive layer. However, in order to significantly increase the refractive index of the adhesive sheet, a considerable amount of high-refractive-index particles need to be added, and the compatibility of the adhesive components with the high-refractive-index particles becomes important. If the high-refractive-index particles do not have good compatibility with the adhesive components such as polymers, the refractive index will not increase as expected. In addition, particles such as inorganic particles in the adhesive often become a limiting factor for the adhesive properties such as adhesive force and impact resistance, and thus the state of compatibility of the high-refractive-index particles in the adhesive is also important from the viewpoint of maintaining the adhesive properties. Furthermore, for high-refractive-index particles that do not have good compatibility with the adhesive components, problems such as gelation of the adhesive composition are also likely to occur.

[0011] The present application was made in view of the above circumstances, and aims to provide an adhesive sheet in which the refractive index is effectively increased using high-refractive-index particles that have good compatibility with adhesive components.

[0012] Means for solving the problem

[0013] According to the present specification, an adhesive sheet having an adhesive layer is provided. The adhesive layer contains high-refractive-index particles P HRI . Furthermore, the average particle diameter of the particles P HRI present in the above adhesive layer is less than 100 nm, and the standard deviation is 20 nm or less. Here, the average particle diameter and the standard deviation are the average particle diameter and the standard deviation, respectively, calculated from the number-based particle size distribution based on TEM observation.

[0014] In addition, according to the present specification, an adhesive sheet having an adhesive layer is provided. The adhesive layer contains particles P HRI containing a metal oxide. Furthermore, the average particle diameter of the particles P HRI present in the above adhesive layer is less than 100 nm, and the standard deviation is 20 nm or less. Here, the average particle diameter and the standard deviation are the average particle diameter and the standard deviation, respectively, calculated from the number-based particle size distribution based on TEM observation.

[0015] The particles P HRI containing a metal oxide and the like are usually handled in the form of a dispersion liquid dispersed in a dispersion medium such as an organic solvent, and when added to the adhesive layer, the dispersion medium forms the adhesive layer, and has a different dispersion state and particle size distribution from that in the dispersion liquid. It is considered that the refractive index of the adhesive sheet depends on the state (compatibility, dispersion state, particle size distribution, etc.) of the particles P HRI in the adhesive layer, and thus the state of compatibility of the particles P HRIaccurately evaluate the state of the particles P HRI The inventors have found that it is important to accurately evaluate the state of the particles P HRI The inventors have found that it is important to accurately evaluate the state of the particles P HRI The inventors have found that it is important to accurately evaluate the state of the particles P HRI The inventors have found that it is important to accurately evaluate the state of the particles P HRI The inventors have found that it is important to accurately evaluate the state of the particles P

[0016] The adhesive layer disclosed herein can contain at least one particle P HRI The inventors have found that it is important to accurately evaluate the state of the particles P HRI .

[0017] In some preferred modes, the average particle size of the particles P HRI present in the adhesive layer is less than 80 nm. According to such a configuration, the refractive index of the adhesive sheet is more effectively increased.

[0018] In some preferred modes, the adhesive layer contains the particles P HRI at a proportion of more than 20% by weight. By containing the particles P HRI in the adhesive layer in an amount of more than a predetermined amount, the refractive index of the adhesive sheet can be further increased.

[0019] In some preferred modes, the adhesive layer is a solvent-type adhesive layer formed from a solvent-type adhesive composition. In the mode having the solvent-type adhesive layer formed from the solvent-type adhesive composition, the refractive index increasing effect brought about by the use of the particles P HRI can be preferably achieved.

[0020] The adhesive layer disclosed herein can be an acrylic adhesive layer containing an acrylic polymer as a base polymer. In the configuration having the acrylic adhesive layer, the effect of increasing the refractive index brought about by the technology disclosed herein can be preferably achieved.

[0021] In some preferred embodiments, the above-mentioned particle P HRI A hydrophobic surface treatment is implemented. By using the particle P HRI , on which a hydrophobic surface treatment is implemented HRI is well compatible with the adhesive component, and the effect of increasing the refractive index of the adhesive sheet is easily obtained.

[0022] In some preferred embodiments, the thickness of the above-mentioned adhesive sheet is in the range of 10 μm to 50 μm. By setting the thickness of the adhesive sheet to 10 μm or more, it is possible to increase the refractive index while preferably achieving the desired adhesive properties. By setting the thickness of the adhesive sheet to 50 μm or less, it is possible to well respond to the requirements of thickness reduction and light weight. The above-mentioned thickness can preferably be applied to a substrate-free double-sided adhesive sheet composed only of an adhesive layer. The substrate-free double-sided adhesive sheet does not have a substrate, and accordingly can be reduced in thickness, which can contribute to the miniaturization and space saving of products in which the double-sided adhesive sheet is applied. In addition, according to the substrate-free adhesive sheet, the effects of the adhesive layer such as adhesion and impact resistance can be maximally exerted.

[0023] The adhesive sheet disclosed herein can be preferably used, for example, to join (typically, fix) members of a portable electronic device. The portable electronic device can have a light sensor built in, and by using the adhesive sheet disclosed herein to suppress light reflection, it is possible to reduce the influence on the operation of the light sensor. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a cross-sectional view schematically showing one configuration example of an adhesive sheet.

[0025] Figure 2 is a cross-sectional view schematically showing another configuration example of an adhesive sheet.

[0026] Figure 3 is a cross-sectional view schematically showing another configuration example of an adhesive sheet.

[0027] Figure 4 is a schematic exploded perspective view schematically showing one configuration example of a liquid crystal display device.

[0028] Figure 5 is a histogram of the particle P HRI based on the number basis of TEM observation of the adhesive of Example 2.

[0029] Figure 6 is a histogram of the particle P HRI based on the number basis of TEM observation of the adhesive of Example 8. DETAILED DESCRIPTION

[0030] The preferred embodiments of the present invention will now be described. It should be noted that matters necessary for implementing the present invention, other than those specifically mentioned in this specification, can be understood by those skilled in the art based on the teachings on implementation of the invention as described in this specification and common technical knowledge at the time of application. The present invention can be implemented based on the disclosure in this specification and common technical knowledge in the field. Furthermore, in the following drawings, components / parts that perform the same function are sometimes labeled with the same reference numerals, and repeated descriptions may be omitted or simplified. Additionally, for the purpose of clearly illustrating the present invention, the embodiments described in the drawings are schematic and do not necessarily accurately represent the dimensions or scale of the adhesive sheet of the present invention actually provided as a product.

[0031] In this specification, "adhesive" refers to a material that, as described above, is a soft solid (viscoelastic) in a temperature range near room temperature and has the property of easily adhering to the substrate under pressure. The adhesive referred to here, as defined in "CADahlquist, 'Adhesion: Fundamental and Practice', McLaren & Sons, (1966) p. 143," can generally be a material having a complex tensile modulus E. ＊ (1Hz) < 10 7 dyne / cm 2 Materials with the properties described above (typically, materials that have the properties described above at 25°C).

[0032] <Example of adhesive sheet composition>

[0033] The adhesive sheet disclosed herein can be a substrate-supported adhesive sheet having the aforementioned adhesive layer on one or both sides of a non-peelable substrate (supporting substrate), or a substrate-free adhesive sheet (i.e., an adhesive sheet without a non-peelable substrate) in which the aforementioned adhesive layer is held on a release liner. The concept of adhesive sheet herein can include items referred to as adhesive tape, adhesive label, adhesive film, etc. It should be noted that the adhesive sheet disclosed herein can be in roll form or in single sheet form. Alternatively, it can be an adhesive sheet further processed into various shapes.

[0034] The structure of a double-sided adhesive substrate-free adhesive sheet (substrate-free double-sided adhesive sheet) is illustrated in the figure. Figure 1 , 2 middle. Figure 1 The adhesive sheet 1 shown has a structure in which both sides 21A and 21B of the substrate-free adhesive layer 21 are protected by release liner 31 and 32, which at least the adhesive layer side serves as the release surface. Figure 2The illustrated adhesive sheet 2 has a configuration in which one surface (adhesive surface) 21A of the adhesive layer 21 without a substrate is protected by the release liner 31 whose both surfaces are release surfaces, and when the adhesive sheet 2 is wound, the other surface (adhesive surface) 21B of the adhesive layer 21 is in contact with the back surface of the release liner 31, whereby the other surface 21B is also protected by the release liner 31. The technology disclosed herein can be preferably implemented in the form of an adhesive sheet without a substrate from the viewpoint of reducing the thickness of the adhesive sheet. An adhesive sheet without a substrate is easily thinned, and is also advantageous from the viewpoint of being able to maximize the adhesive properties such as adhesive strength and impact resistance.

[0035] The adhesive sheet disclosed herein can be, for example, an adhesive sheet having Figure 3 a cross-sectional structure schematically illustrated in FIG. 1. Figure 3 The illustrated adhesive sheet 3 has a support substrate 10 and first and second adhesive layers 21 and 22 supported by the first and second surfaces 10A and 10B, respectively, of the support substrate 10. The first and second surfaces 10A and 10B are both non-release surfaces (non-release surfaces). The adhesive sheet 3 is used by adhering the surface (first adhesive surface) 21A of the first adhesive layer 21 and the surface (second adhesive surface) 22A of the second adhesive layer 22 to adherends, respectively. That is, the adhesive sheet 3 is configured as a double-sided adhesive sheet (double-sided adhesive adhesive sheet). The adhesive sheet 3 before use has a configuration in which the first and second adhesive surfaces 21A and 22A are protected by release liners 31 and 32 whose at least the adhesive surface sides are surfaces (release surfaces) having release properties. Alternatively, the release liner 32 can be omitted, and a release liner whose both surfaces are release surfaces can be used as the release liner 31, and the adhesive sheet 3 can be wound such that the second adhesive surface 22A is in contact with the back surface of the release liner 31, whereby the second adhesive surface 22A is also protected by the release liner 31.

[0036] The technology disclosed herein is preferably implemented in the form of the above-described adhesive sheet without a substrate or the double-sided adhesive sheet with a substrate for the fixation and joining of members. Alternatively, the adhesive sheet disclosed herein, although not specifically illustrated, can be in the form of a single-sided adhesive sheet with a substrate having an adhesive layer on only one surface of a non-release substrate (support substrate). As an example of the form of a single-sided adhesive sheet, an adhesive sheet having a support substrate and an adhesive layer on one surface of the support substrate can be cited. Figure 3 The illustrated configuration does not have either of the first and second adhesive layers 21 and 22.

[0037] <Adhesive Layer>

[0038] (Particle P HRI in the Adhesive Layer)

[0039] The adhesive layer constituting the adhesive sheet disclosed herein contains a particle P HRI . Specifically, the adhesive layer contains an adhesive component such as a base polymer, and also contains a particle PHRI Furthermore, the particles P HRI have an average particle diameter of less than 100 nm. Here, the particles P HRI present in the adhesive layer refer to particles P HRI having an average particle diameter of less than 100 nm. The average particle diameter of the particles P HRI present in the adhesive layer refers to an average particle diameter calculated from a number-based particle diameter distribution based on TEM observation, and is specifically measured using a cryo-ultrathin section of the adhesive. The particles P HRI present in the adhesive layer have an average particle diameter of less than 100 nm. This can mean that a certain amount of the particles P HRI are present in the adhesive layer in a good compatible state. Thereby, the effect of increasing the refractive index of the adhesive layer by using the particles P HRI is effectively exerted. The average particle diameter is preferably less than 80 nm, more preferably less than 60 nm, further preferably less than 40 nm, and can be less than 30 nm. The lower limit of the average particle diameter is not particularly limited, and is preferably about 1 nm or more, more preferably about 5 nm or more, and further preferably about 10 nm or more, from the viewpoint of appropriately exerting the effect of increasing the refractive index. The particles P HRI present in the adhesive layer typically exist in a dispersed state in the adhesive layer. In other words, the adhesive layer contains an adhesive component such as a base polymer, and the particles P HRI can be dispersed in such an adhesive layer.

[0040] Furthermore, the particles P HRI present in the adhesive layer disclosed herein have a standard deviation of the number-based particle diameter distribution based on the TEM observation of 20 nm or less (e.g., less than 20 nm). Thereby, the effect of increasing the refractive index by using the particles P HRI is effectively exerted. The standard deviation is more preferably less than 15 nm, further preferably less than 10 nm, and particularly preferably less than 8 nm. The lower limit of the standard deviation is not particularly limited, and can be about 1 nm or more, for example, about 2 nm or more (typically about 3 nm or more).

[0041] The particles P HRI present in the adhesive layer disclosed herein have a ratio of particles having a particle diameter of 50 nm or more in the number-based particle diameter distribution based on the TEM observation of about 5% or less. A small ratio of large-diameter particles having a particle diameter of 50 nm or more can mean that the amount of aggregated particles is limited. In such a configuration, the effect of the particles P HRI being well compatible with the adhesive component can be more appropriately exerted. In the particle diameter distribution, the ratio of particles having a particle diameter of 50 nm or more is preferably about 3% or less.

[0042] There is no particular limitation on the particles PHRI The proportion of particles having a particle diameter of less than 15 nm in the particle diameter distribution based on the number basis of the above TEM observation is preferably limited. This is because the particles having a particle diameter of less than 15 nm contain small-diameter particles that are considered to have a small contribution to the increase in the refractive index. From such a viewpoint, the proportion of particles having a particle diameter of less than 15 nm in the above particle diameter distribution is preferably about 30% or less, more preferably about 20% or less, and further preferably about 15% or less. In view of the difficulty of completely controlling the particle diameter distribution and the like, the proportion of particles having a particle diameter of less than 15 nm in the above particle diameter distribution can be about 1% or more, for example, 2% or more (and further about 3% or more).

[0043] The average particle diameter, the standard deviation, and other particle diameter distribution characteristics calculated from the particle diameter distribution based on the number basis of the above TEM observation can be measured by the particle P HRI The selection of the type, the composition of the binder (mainly the monomer composition of the base polymer, the type and amount of the crosslinking agent, and the like), the surface treatment of the above particle P HRI suitable for the binder, the selection of the type and amount of the dispersant, the particle P HRI The addition form (dispersion liquid, dispersion medium, and the like), the addition conditions, and the like in the binder composition are achieved. For example, by combining different particles P HRI , surface treatment methods, and binder components to thereby produce a variety of binders, and performing a screening using the above TEM observation (if necessary, repeating the operation), a binder containing a particle P HRI having desired particle diameter distribution characteristics can be obtained. The particle P HRI type and the surface treatment method thereof can be selected based on the properties of the binder containing the particle P HRI in accordance with the content described in the present specification and technical common sense. The average particle diameter, the standard deviation, and other particle diameter characteristics calculated from the particle diameter distribution based on the number basis of the above TEM observation are specifically measured by the methods described in the Examples described later.

[0044] (Particle P HRI )

[0045] In the technology disclosed herein, the particle P HRI is a particle capable of increasing the refractive index of a binder (layer), and HRI refers to high refractive index. In this sense, the particle P HRI may be referred to as a high refractive index particle. By containing the particle P HRI in a binder layer, the refractive index of a bonded sheet can be increased. The particle P HRI may be used alone or in combination with two or more.

[0046] As the particle P HRIVarious materials capable of increasing the refractive index of the adhesive can be used. The refractive index of a general adhesive known in the art is less than 1.50 (for example, about 1.47), and for such a basic adhesive, the refractive index of the adhesive sheet can be increased by containing an appropriate amount of, for example, particles containing a material having a refractive index greater than 1.50 within the adhesive layer. As the particles P HRI One or two or more of, for example, particles composed of a material having a refractive index of 1.60 or more, preferably 1.70 or more, more preferably 1.80 or more, further preferably 2.00 or more (for example, 2.20 or more) can be used. The upper limit of the refractive index of the material constituting the particles P HRI is not particularly limited, and from the viewpoint of handling properties in consideration of compatibility with the adhesive, for example, 3.00 or less, 2.80 or less, further 2.50 or less, or 2.20 or less can be used. The refractive index of the material constituting the particles P HRI is the refractive index measured at 23°C using a commercially available ellipsometer on a single layer film of the material (the film thickness is set to be able to measure the refractive index). The wavelength region of the measurement is the same as the refractive index of the adhesive sheet. As the ellipsometer, for example, a product name "EC-400" (manufactured by JA. Woolam) or an equivalent thereof can be used.

[0047] The kind of the particles P HRI is not particularly limited, and one or two or more of a material capable of increasing the refractive index of the adhesive sheet can be used selected from among metal particles, metal compound particles, organic particles, and organic-inorganic composite particles. As the particles P HRI , an inorganic oxide (for example, a metal oxide) capable of increasing the refractive index of the adhesive sheet can be preferably used from among inorganic oxides. As a preferred example of the material constituting the particles P HRI , inorganic oxides (specifically, metal oxides) such as titanium dioxide (titanium oxide, TiO2), zirconium dioxide (zirconium oxide, ZrO2), cerium oxide, aluminum oxide, zinc oxide, tin oxide, copper oxide, barium titanate, and niobium oxide (Nb2O5or the like) can be listed. The particles containing these inorganic oxides (for example, metal oxides) can be used alone or in combination with two or more. Among them, particles containing titanium dioxide and zirconium dioxide are preferred, and particles containing zirconium dioxide are particularly preferred. In addition, as metal particles, for example, iron-based materials, zinc-based materials, tungsten-based materials, and platinum-based materials can have a high refractive index. As organic particles, the refractive index of particles containing a styrene-based resin, a phenol-based resin, a polyester-based resin, a polycarbonate-based resin, or the like is relatively high. As organic-inorganic composite particles, a composite of the above-described inorganic material and an organic material, a material obtained by coating an inorganic particle with an organic material such as a resin, or the like can be listed. Note that the particles P HRIThe particle P HRI does not include a light-absorbing black colorant.

[0048] In addition, as the particle P HRI from the viewpoint of compatibility with the binder component, it is preferable to use a particle obtained by surface-treating the aforementioned organic particle, inorganic particle, with a surface-treating agent. Such surface-treatment can bring about an effect of effectively improving compatibility for a nano-sized particle having an average particle diameter of less than 1 μm. The surface-treatment can be appropriately selected depending on the kind of core particle, the kind of dispersion medium, and the like, and is not limited to a particular treatment. The surface-treatment is typically a treatment in which a surface-treating agent modifies the core particle (for example, inorganic particle such as metal oxide). The surface-treating agent can be a compound having a functional group (carboxyl group, sulfonic acid group, phosphoric acid group, hydroxyl group, amino group, isocyanate group, vinyl group, alkoxysilyl group, and the like) that is reactive with the core particle (for example, inorganic particle such as metal oxide), and an alkyl group or alkenyl group, (meth)acryloyl group, phenyl group, or the like aliphatic; alicyclic; aromatic; and other organic group. The aforementioned organic group has a prescribed hydrophobicity (lipophilicity), and thus, by the aforementioned surface-treatment, the surface of the core particle (for example, inorganic particle such as metal oxide) is hydrophobized, and compatibility with the binder component including a polymer such as an acrylic, rubber, or the like is good. Such surface-treatment can be referred to as a hydrophobic surface-treatment (hydrophobization treatment). The aforementioned surface-treatment can preferably be a treatment in which a reactive group such as an alkenyl group or (meth)acryloyl group constitutes the surface of the particle P HRI . As the surface-treating agent, an organic acid such as an aliphatic carboxylic acid, an anionic surfactant (sulfonic acid type, phosphoric acid type, fatty acid type, and the like), and other surfactants (including reactive surfactants having a reactive functional group), a (meth)acrylate having a functional group, a silane coupling agent or silane compound such as an alkoxysilane, a siloxane compound, a silazane compound, a titanium coupling agent, and the like can be exemplified. The surface-treating agent can be used alone or in combination with two or more. The surface-treating agent can be used for surface-treatment of the core particle under appropriate methods and conditions (amount of surface-treating agent used, presence or absence of use of a reaction aid, solvent, temperature, time, and the like) known to those skilled in the art.

[0049] In some preferable modes, a surface-treatment using a sulfonic acid compound (hydrophobization treatment) can be employed for the core particle (for example, inorganic particle such as metal oxide) of the particle P HRI . As the sulfonic acid compound, an alkylbenzenesulfonate such as a nonylbenzenesulfonate, dodecylbenzenesulfonate, and the like; a naphthalenesulfonate such as a dodecyl naphthalenesulfonate; an alkyl diphenyl ether disulfonate such as a dodecyl diphenyl ether disulfonate; and the like sulfonic acid surfactant can be used. The sulfonic acid compound can be used alone or in combination with two or more.

[0050] In some other ways, particle P can be... HRI For inorganic particles (such as metal oxides), surface treatment (hydrophobic treatment) is performed using saturated or unsaturated aliphatic carboxylic acids or carboxyl-containing compounds such as methacrylic acid as surface treatment agents. In other methods, surface treatment (hydrophobic treatment) can be performed using isocyanate-containing (meth)acrylates such as methacryloxyethyl isocyanate (MOI) and polyfunctional (meth)acrylates such as dipentaerythritol hexaacrylate (DPHA) as surface treatment agents. In still other methods, surface treatment (hydrophobic treatment) can be performed using vinyl-containing alkoxysilanes such as vinyltrimethoxysilane (VTMS) and alkoxysilanes containing (meth)acryloyl groups as surface treatment agents.

[0051] Particle P HRI For example, it can be added to the adhesive composition in the form of a surface-treated particle dispersion. There are no particular limitations on the dispersion medium used for the above dispersion, taking into account the particle P... HRI To ensure dispersion within the adhesive layer, a suitable dispersion medium can be used. From particle P... HRI From the viewpoint of dispersibility within the adhesive layer, organic solvents are preferred. Examples of dispersion media include: alcohols such as methanol, ethanol, isopropanol, and ethylene glycol; ketones such as acetone, methyl ethyl ketone (MEK), methyl isobutyl ketone, methyl propyl ketone (MPK), cyclohexanone, and cyclopentanone; ethers such as diethyl ether, tetrahydrofuran, dioxane, anisole, propylene glycol monomethyl ether (PGME), and propylene glycol monomethyl ether acetate; esters such as ethyl acetate, butyl acetate, and methyl acetate; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-hexane and cyclohexane; amides such as dimethylformamide and dimethylacetamide (DMA); and cellosols such as methyl cellosol, ethyl cellosol, and butyl cellosol. These dispersion media can be used alone or in combination of two or more. Ketones and amides are preferred, methyl ethyl ketone, methyl isobutyl ketone, and dimethylacetamide are more preferred, and dimethylacetamide is even more preferred. From the viewpoint of compatibility with adhesive components (such as components of acrylic adhesives), it is preferable not to use alcohols or ethers. Containing particles P HRI Particles P in the dispersion HRI There is no particular limitation on the concentration of P; from the viewpoint of good dispersibility in the adhesive layer, the concentration of P particles is acceptable. HRI Particles P in the dispersion HRI The concentration is from about 1% to about 50% by weight (e.g., from about 15% to about 35% by weight).

[0052] Particle P HRIThere are no particular limitations on the average particle size; particles of an appropriate size that can achieve the desired increase in refractive index can be used depending on the thickness of the adhesive layer, the type of adhesive, etc. Particle P HRI The average particle size can be set to approximately 1 nm or more, with approximately 5 nm or more being appropriate. From the perspective of improving refractive index, compatibility, and operability, particle P... HRI The average particle size is preferably about 10 nm or more, and can be about 20 nm or more, or about 30 nm or more. Regarding the upper limit of the above-mentioned average particle size, from the viewpoint of maintaining adhesive properties, for example, about 100 nm or less is appropriate, and from the viewpoint of improving the refractive index, it is preferably about 80 nm or less, more preferably about 70 nm or less, and even more preferably about 50 nm or less, and can also be about 35 nm or less (for example, about 25 nm or less).

[0053] It should be noted that the aforementioned particle P HRI The average particle size refers to the volume average particle size, specifically, the particle size distribution measured using a particle size distribution measuring device based on laser scattering / diffraction. HRI The particle size at which the cumulative value in the particle size distribution of the dispersion is 50% (50% volume average particle size; hereinafter sometimes simply referred to as D). 50 As a measuring device, for example, the product manufactured by Microtrac Bell under the name "Microtrac MT3000II" or its equivalent can be used.

[0054] Particles P in the adhesive layer HRI There are no particular restrictions on the content of the above-mentioned particles P. HRI The content of [amount] can vary depending on the refractive index of the target adhesive sheet. For example, for the aforementioned particle P... HRI The content of [specific component] can be appropriately set to achieve a refractive index exceeding the specified value, taking into account the required adhesive properties. Additionally, the aforementioned particle P... HRI The content can also be adjusted according to the type of adhesive and particle size. HRI The particle size varies depending on factors such as compatibility with the adhesive. The particles P in the adhesive layer... HRI The content of P can be more than about 1% by weight or more than about 10% by weight. From the viewpoint of effectively increasing the refractive index of the adhesive sheet, the above-mentioned P particles... HRI The content of P in the adhesive layer is preferably about 20% by weight or more (e.g., greater than 20% by weight), more preferably about 25% by weight or more, more preferably about 30% by weight or more, even more preferably about 35% by weight or more, particularly preferably about 40% by weight or more, and may also be about 45% by weight or more. From the viewpoint of maintaining compatibility with adhesive components, adhesion strength, impact resistance, and other adhesive properties, the content of P in the adhesive layer is... HRIThe content of the particle P can be set to about 75% by weight or less, about 60% by weight or less is appropriate, preferably about 50% by weight or less, and can also be about 40% by weight or less.

[0055] In addition, the particle P HRI The content of the particle P can also be determined in relation to the base polymer (for example, an acrylic polymer) of the adhesive described later. The content of the particle P HRI The content of the particle P can be set to about 75% by weight or less, about 60% by weight or less is appropriate, preferably about 50% by weight or less, and can also be about 40% by weight or less. HRI The content of the particle P can be set to about 75% by weight or less, about 60% by weight or less is appropriate, preferably about 50% by weight or less, and can also be about 40% by weight or less. HRI The content of the particle P can be set to about 75% by weight or less, about 60% by weight or less is appropriate, preferably about 50% by weight or less, and can also be about 40% by weight or less.

[0056] (Base Polymer)

[0057] In the technology disclosed herein, the type of adhesive that constitutes the adhesive layer is not particularly limited. The above-described adhesive can be an adhesive that contains one or two or more of various rubber-like polymers such as an acrylic polymer, a rubber-based polymer (natural rubber, synthetic rubber, a mixture thereof, etc.), a polyester-based polymer, a urethane-based polymer, a polyether-based polymer, a polysiloxane-based polymer, a polyamide-based polymer, a fluorine-containing polymer, etc., as an adhesive polymer (refers to a structural polymer that forms an adhesive, hereinafter also referred to as "base polymer") that can be used in the field of adhesives. From the viewpoints of adhesion performance, cost, etc., an adhesive that contains an acrylic polymer or a rubber-based polymer as a base polymer can be preferably used. Among them, an adhesive in which an acrylic polymer is used as a base polymer (an acrylic adhesive) is preferable. By applying the technology disclosed herein, an acrylic adhesive having a refractive index of 1.50 or more can be appropriately obtained.

[0058] Hereinafter, an adhesive sheet having an adhesive layer composed of an acrylic adhesive, i.e., an acrylic adhesive layer will be mainly described, but the adhesive layer of the adhesive sheet disclosed herein is not intended to be limited to one composed of an acrylic adhesive.

[0059] Note that the "base polymer" of the adhesive refers to the main component of the rubbery polymer contained in the adhesive, and is not otherwise defined. The above-mentioned rubbery polymer refers to a polymer that exhibits rubber elasticity in the temperature range around room temperature. Also, in the present specification, the "main component" refers to a component having a content of greater than 50% by weight, unless otherwise specified.

[0060] Also, the "acrylic polymer" refers to a polymer that contains monomer units derived from a monomer having at least one (meth)acryloyl group in one molecule as the monomer units constituting the polymer. Hereinafter, the monomer having at least one (meth)acryloyl group in one molecule will also be referred to as an "acrylic monomer". Thus, the acrylic polymer of the present specification is defined as a polymer that contains monomer units derived from an acrylic monomer. As a typical example of the acrylic polymer, an acrylic polymer in which the proportion of the acrylic monomer among all the monomer components used in the synthesis of the acrylic polymer is greater than 50% by weight can be cited.

[0061] Also, the "(meth)acryloyl group" refers to an acryloyl group and a methacryloyl group collectively. Similarly, the "(meth)acrylate" refers to an acrylate and a methacrylate collectively, and the "(meth)acrylic acid" refers to an acrylic acid and a methacrylic acid collectively.

[0062] (Acrylic Polymer)

[0063] As the acrylic polymer in the technology disclosed herein, a polymer that contains, for example, an alkyl (meth)acrylate as a main monomer, and can further contain a monomer raw material of a sub monomer that is copolymerizable with the main monomer is preferable. Here, the main monomer refers to a component that accounts for greater than 50% by weight of the monomer composition of the above-mentioned monomer raw material.

[0064] As the alkyl (meth)acrylate, a compound represented by the following formula (1), for example, can be preferably used.

[0065] CH2=C(R 1 )COOR 2 (1)

[0066] wherein R 1 in the above-mentioned formula (1) is a hydrogen atom or a methyl group. Also, R 2 is a chain alkyl group having a carbon atom number of 1 to 20. Hereinafter, such a range of the carbon atom number will be sometimes expressed as "C 1-20 ". From the viewpoint of the storage modulus of the adhesive, and the like, R 2 is C 1-14 (for example, C 1-10 , typically C 4-8Alkyl (meth)acrylates with chain-like alkyl groups are suitable as the main monomer. From the viewpoint of adhesive properties, R is preferred. 1 It is a hydrogen atom and R 2 C 4-8 Alkyl acrylates with chain-like alkyl groups (hereinafter also referred to as C acrylates) 4-8 Alkyl esters are used as the main monomers.

[0067] As R 2 C 1-20 Specific examples of alkyl (meth)acrylates with chain-like alkyl groups are not particularly limited, and examples include: methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate. Alkyl methacrylate, nonyl methacrylate, isononyl methacrylate, decyl methacrylate, isodecanyl methacrylate, undecyl methacrylate, dodecyl methacrylate, tridecyl methacrylate, tetradecyl methacrylate, pentadecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, octadecyl methacrylate, nonadecanyl methacrylate, eicosyl methacrylate, etc. These alkyl methacrylates can be used alone or in combination of two or more. Preferred examples of alkyl methacrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

[0068] The proportion of alkyl (meth)acrylates in the monomer components constituting acrylic polymers is typically greater than 50% by weight, for example, it can be set to 70% by weight or more, 85% by weight or more, or 90% by weight or more. There is no particular upper limit to the proportion of alkyl (meth)acrylates, but it is preferably set to 99.5% by weight or less (e.g., 99% by weight or less), or, from the viewpoint of preferably utilizing the properties (e.g., cohesiveness) of secondary monomers such as carboxyl-containing monomers, it can be set to 98% by weight or less (e.g., less than 97% by weight). Alternatively, the acrylic polymer may also be a polymer obtained by substantially polymerizing only alkyl (meth)acrylates.

[0069] In addition, using acrylic C 4-8 When alkyl esters are used as monomer components, in the (meth)acrylate alkyl esters contained in these monomer components, acrylic acid C 4-8The proportion of the alkyl ester is preferably 70% by weight or more, and more preferably 90% by weight or more. The technology disclosed herein can be preferably implemented in a manner that BA is 50% by weight or more (typically 60% by weight or more) of the total monomer component. In some preferred modes, the proportion of BA in the total monomer component can be 70% by weight or more, 80% by weight or more, and further 90% by weight or more. The total monomer component described above can further contain 2EHA in a proportion less than BA.

[0070] The technology disclosed herein can be preferably implemented in a manner that the monomer component described above contains 50% by weight or more of the (meth)acrylic acid C 1-4 The (meth)acrylic acid C 1-4 The proportion of the alkyl ester in the monomer component is set to 70% by weight or more, and can be set to 85% by weight or more (for example, 90% by weight or more). On the other hand, from the viewpoint of obtaining good coagulation, the proportion of the alkyl ester of the (meth)acrylic acid C 1-4 It is appropriate that the proportion of the alkyl ester of the (meth)acrylic acid C

[0071] The technology disclosed herein can be preferably implemented in a manner that the monomer component described above contains 50% by weight or more (for example, 70% by weight or more, or 85% by weight or more, or 90% by weight or more) of the acrylic acid C 2-4 The technology disclosed herein can be preferably implemented in a manner that the monomer component described above contains 50% by weight or more (for example, 70% by weight or more, or 85% by weight or more, or 90% by weight or more) of the acrylic acid C 2-4 Specific examples of the acrylic acid C 2-4 The alkyl ester can be used alone or in combination with two or more. In this way, an adhesive sheet with good adhesion to an adherend is easily achieved. Among them, as a preferred mode, a mode in which the monomer component described above contains more than 50% by weight (for example, 70% by weight or more, or 85% by weight or more, or 90% by weight or more) of BA can be cited. By using the acrylic acid C 2-4 The alkyl ester (for example, BA) can, for example, in the case where a black colorant such as carbon black is incorporated in the adhesive, allow the colorant to be well dispersed in the layer and maintain good adhesive properties such as adhesive force. On the other hand, from the viewpoint of obtaining good coagulation, the proportion of the alkyl ester of the (meth)acrylic acid C 2-4 It is appropriate that the proportion of the alkyl ester of the (meth)acrylic acid C

[0072] In some other modes, the above monomer component can be implemented in a manner containing 50% by weight or more (for example, 70% by weight or more, or 85% by weight or more, or 90% by weight or more) of the (meth)acrylic acid C 5-20 alkyl ester. As the (meth)acrylic acid C 5-20 alkyl ester, preferably the (meth)acrylic acid C 6-14 alkyl ester. In some modes, it can be preferable to use the acrylic acid C 6-10 alkyl ester (for example, the acrylic acid C 8-10 alkyl ester).

[0073] The acrylic polymer in the technology disclosed herein can be copolymerized with a co-monomer. As the co-monomer capable of introducing a functional group capable of becoming a crosslinking point in the acrylic polymer, or capable of contributing to the improvement of adhesive strength, there can be cited: a carboxyl group-containing monomer, a hydroxyl group (OH group)-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, a cyano group-containing monomer, a ketone group-containing monomer, a monomer having a ring containing a nitrogen atom, a monomer containing an alkoxysilyl group, an imide group-containing monomer, and the like. The above co-monomer can be used alone or in combination with two or more.

[0074] As a preferred example of the acrylic polymer in the technology disclosed herein, there can be cited an acrylic polymer copolymerized with a carboxyl group-containing monomer as the above co-monomer. As the carboxyl group-containing monomer, there can be cited: acrylic acid (AA), methacrylic acid (MAA), (meth)acrylic acid carboxyethyl ester, (meth)acrylic acid carboxypentyl ester, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and the like. Among these, AA and MAA are preferable.

[0075] As another preferred example, there can be cited an acrylic polymer copolymerized with a hydroxyl group-containing monomer as the above co-monomer. As examples of the hydroxyl group-containing monomer, there can be cited: (meth)acrylic acid 2-hydroxyethyl ester, (meth)acrylic acid 2-hydroxypropyl ester, (meth)acrylic acid 3-hydroxypropyl ester, (meth)acrylic acid 2-hydroxybutyl ester, (meth)acrylic acid 4-hydroxybutyl ester, and the like (meth)acrylic acid hydroxyalkyl esters; polypropylene glycol mono(meth)acrylate; N-hydroxyethyl (meth)acrylamide; and the like. As a preferable hydroxyl group-containing monomer among these, there can be cited a linear (meth)acrylic acid hydroxyalkyl ester in which the alkyl group is a linear alkyl group having 2 to 4 carbon atoms.

[0076] As the amide group-containing monomer, for example, there can be cited: (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, N-hydroxymethylpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide.

[0077] As the amino group-containing monomer, for example, aminoethyl (meth) acrylate, N,N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate can be exemplified.

[0078] As the monomer having an epoxy group, for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether can be exemplified.

[0079] As the monomer containing a cyano group, for example, acrylonitrile, methacrylonitrile can be exemplified.

[0080] As the monomer containing a ketone group, for example, diacetone (meth) acrylamide, diacetone (meth) acrylate, methyl vinyl ketone, ethyl vinyl ketone, allyl acetoacetate, vinyl acetoacetate can be exemplified.

[0081] As the monomer having a nitrogen atom-containing ring, for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyl oxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth) acryloylmorpholine can be exemplified.

[0082] As the monomer containing an alkoxysilyl group, for example, 3-(meth) acryloyloxypropyl trimethoxysilane, 3-(meth) acryloyloxypropyl triethoxysilane, 3-(meth) acryloyloxypropyl methyl dimethoxysilane, 3-(meth) acryloyloxypropyl methyl diethoxysilane can be exemplified.

[0083] In the case where the monomer component constituting the acrylic polymer contains the above-mentioned functional group-containing monomer, the content of the functional group-containing monomer in the monomer component is not particularly limited. From the viewpoint of appropriately exerting the effects brought about by the use of the functional group-containing monomer, the content of the functional group-containing monomer in the monomer component can be set to 0.1% by weight or more, it is appropriate to set it to 0.5% by weight or more, and it can also be set to 1% by weight or more. In addition, from the viewpoint of easily obtaining a balance of adhesion properties in relation to the main monomer, it is appropriate to set the content of the functional group-containing monomer in the monomer component to 40% by weight or less, it is preferable to set it to 20% by weight or less, and it can also be set to 10% by weight or less (for example, 5% by weight or less).

[0084] In the base polymer of some preferred modes, the monomer component constituting the base polymer (e.g., acrylic polymer) can include a carboxyl group-containing monomer. By including a carboxyl group-containing monomer in the monomer component, an adhesive sheet that exhibits good adhesive properties (cohesion, etc.) is easily obtained. In addition, it is also advantageous in improving the adhesion of the adhesive layer to the adherend. Furthermore, by copolymerizing an appropriate amount of a carboxyl group-containing monomer, for example, in the case where a black colorant such as carbon black is incorporated in the adhesive, it is also easy to cause the colorant to be well dispersed within the layer, and the adhesive properties can be preferably maintained.

[0085] In the mode in which a carboxyl group-containing monomer is copolymerized in the base polymer, the content of the carboxyl group-containing monomer in the monomer component constituting the base polymer is not particularly limited, and can be set to 0.2% by weight or more (typically 0.5% by weight or more) of the monomer component, and it is appropriate to set it to 1% by weight or more, and it can be set to 2% by weight or more, or it can be set to 3% by weight or more. By setting the content of the carboxyl group-containing monomer to more than 3% by weight, a better effect can be exerted. In some modes, the content of the carboxyl group-containing monomer can be set to 3.2% by weight or more, 3.5% by weight or more, 4% by weight or more, or 4.5% by weight or more of the monomer component. The upper limit of the content of the carboxyl group-containing monomer is not particularly limited, and can be set to 15% by weight or less, 12% by weight or less, or 10% by weight or less, for example. The technology disclosed herein can be preferably implemented in a mode in which the content of the carboxyl group-containing monomer is 7% by weight or less (typically less than 7% by weight, such as 6.8% by weight or less, or 6.0% by weight or less) of the monomer component.

[0086] For the purpose of improving cohesiveness and the like, the monomer component constituting the acrylic polymer can also contain other copolymerization components other than the above-described comonomer. As examples of the other copolymerization components, there can be mentioned: vinyl ester-based monomers such as vinyl acetate, vinyl propionate, vinyl laurate, and the like; aromatic vinyl compounds such as styrene, substituted styrenes (a-methylstyrene and the like), vinyltoluene, and the like; cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, cyclopentyl (meth)acrylate, isobornyl (meth)acrylate, and the like; (meth)acrylates containing an aromatic ring such as (meth)acrylate phenyl ester, (meth)acrylate phenoxyalkyl ester (e.g., (meth)acrylate phenoxyethyl ester), (meth)acrylate aralkyl ester (e.g., (meth)acrylate benzyl ester), and the like; olefin-based monomers such as ethylene, propylene, isoprene, butadiene, isobutylene, and the like; chlorine-containing monomers such as vinyl chloride, vinylidene chloride, and the like; isocyanate group-containing monomers such as 2-(meth)acryloyloxyethyl isocyanate, and the like; alkoxyl group-containing monomers such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and the like; vinyl ether-based monomers such as methyl vinyl ether, ethyl vinyl ether, and the like; multifunctional monomers having two or more (e.g., three or more) polymerizable functional groups (e.g., (meth)acryloyl groups) in one molecule such as 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and the like; and the like.

[0087] The amount of the other copolymerization components can be appropriately selected depending on the purpose and use, and is not particularly limited, but from the viewpoint of appropriately exerting the effects brought about by the use of the other copolymerization components, it is appropriate to set to 0.05% by mass or more, and can be set to 0.5% by mass or more. In addition, from the viewpoint of easily obtaining a balance of adhesive properties, it is appropriate to set the content of the other copolymerization components in the monomer component to 20% by mass or less, and can be set to 10% by mass or less (e.g., 5% by mass or less). The technology disclosed herein can be preferably implemented in such a manner that the monomer component does not substantially contain the other copolymerization components. Here, the monomer component does not substantially contain the other copolymerization components means that the other copolymerization components are not intentionally used, and it can be allowed to unintentionally contain, for example, about 0.01% by mass or less of the other copolymerization components.

[0088] It is appropriate that the copolymerization composition of the acrylic polymer is designed in such a manner that the glass transition temperature (Tg) of the polymer is about -15°C or lower (e.g., about -70°C or higher and -15°C or lower). Here, the Tg of the acrylic polymer refers to the Tg obtained based on the composition of the monomer component used in the synthesis of the polymer and by the Fox equation. The Fox equation is shown below, and the Fox equation is a relational expression of the Tg of a copolymer and the glass transition temperatures Tgi of homopolymers obtained by homopolymerization of the respective monomers constituting the copolymer.

[0089] 1 / Tg =∑(Wi / Tgi)

[0090] Note that in the above Fox equation, Tg represents the glass transition temperature of the copolymer (unit: K), Wi represents the weight fraction of monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi represents the glass transition temperature of the homopolymer of monomer i (unit: K).

[0091] As the glass transition temperature of the homopolymer used in the calculation of Tg, the value described in the publicly known literature can be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomer.

[0092]

[0093] For the glass transition temperature of the homopolymer of monomers other than the above examples, the value described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) is used. For monomers for which multiple values are described in this document, the highest value is adopted. In cases not described in the above Polymer Handbook, the value obtained by the measurement method described in Japanese Patent Application Publication No. 2007-51271 is used.

[0094] Although not particularly limited, it is advantageous for the Tg of the acrylic polymer to be about -25°C or lower from the viewpoint of impact resistance and adhesion to the adherend, and it is preferably about -35°C or lower, and more preferably about -40°C or lower. In some modes, the Tg of the acrylic polymer can be about -65°C or higher, for example, can be about -60°C or higher, or can be about -55°C or higher, from the viewpoint of cohesive force. The technology disclosed herein can be preferably implemented in a mode in which the Tg of the acrylic polymer is about -65°C or higher and -35°C or lower (for example, about -55°C or higher and -40°C or lower). The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (i.e., the kind, usage ratio of monomers used for the synthesis of the polymer).

[0095] The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as the synthesis method of the acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, a photopolymerization method, and the like, can be appropriately used. For example, a solution polymerization method can be preferably used. The polymerization temperature when solution polymerization is performed can be appropriately selected depending on the kind of monomer and solvent used, the kind of polymerization initiator, and the like, and can be set to about 20°C to about 170°C (typically, about 40°C to about 140°C), for example.

[0096] The solvent used for the solution polymerization (polymerization solvent) can be appropriately selected from among conventionally known organic solvents. For example, any one solvent selected from the group consisting of aromatic compounds (typically, aromatic hydrocarbons) such as toluene; acetate esters such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane, cyclohexane; halogenated alkanes such as 1,2-dichloroethane; lower alcohols (for example, monohydric alcohols having 1 to 4 carbon atoms) such as isopropyl alcohol; ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; and the like, or a mixed solvent of two or more kinds thereof can be used.

[0097] The initiator used for the polymerization can be appropriately selected from among conventionally known polymerization initiators depending on the kind of the polymerization method. For example, one or two or more kinds of azo-based polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. As other examples of the polymerization initiator, there can be mentioned: persulfates such as potassium persulfate; peroxide-based initiators such as benzoyl peroxide, hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; aromatic carbonyl compounds; and the like. As still other examples of the polymerization initiator, there can be mentioned redox-based initiators based on the combination of a peroxide and a reducing agent. Such polymerization initiators can be used singly or in combination of two or more kinds. The amount of the polymerization initiator used can be a usual amount, for example, can be selected from the range of about 0.005 parts by weight to about 1 part by weight (typically, about 0.01 parts by weight to about 1 part by weight) with respect to 100 parts by weight of the monomer component.

[0098] By the above-described solution polymerization, a polymerization reaction liquid in which an acrylic polymer is dissolved in an organic solvent can be obtained. The adhesive layer in the technology disclosed herein can be formed of an adhesive composition including the above-described polymerization reaction liquid or an acrylic polymer solution obtained by subjecting the reaction liquid to an appropriate post-treatment. As the above-described acrylic polymer solution, a reaction liquid obtained by making the above-described polymerization reaction liquid have an appropriate viscosity (concentration) as needed can be used. Alternatively, an acrylic polymer solution prepared by synthesizing an acrylic polymer by a polymerization method other than the solution polymerization (for example, emulsion polymerization, photopolymerization, bulk polymerization, or the like) and dissolving the acrylic polymer in an organic solvent can be used.

[0099] The weight average molecular weight (Mw) of the base polymer (preferably, the acrylic polymer) in the technology disclosed herein is not particularly limited, and for example, can be in the range of about 10 x 10 4 to about 500 x 10 4 . From the viewpoint of the adhesive properties, the Mw of the base polymer is preferably in the range of about 30 x 10 4 to about 200 x 10 4 , more preferably about 45 x 10 4 to about 150 x 10 4 , and typically about 65 x 10 4~ 130 x 10 4 By using a base polymer having a high Mw, there is a tendency that better impact resistance is easily obtained with the cohesive force of the polymer itself. Here, Mw refers to a value converted to standard polystyrene by GPC (gel permeation chromatography). As the GPC device, for example, a model name "HLC-8320 GPC" (column: TSKgel GMH-H (S), manufactured by Tosoh Corporation) can be used.

[0100] (Coloring agent)

[0101] A coloring agent can be contained in the adhesive layer. By this, the light transmittance (light shielding property) of the adhesive sheet can be adjusted. As the coloring agent, various materials capable of attenuating light traveling in the adhesive layer by absorption can be used. The coloring agent can be, for example, a black, gray, red, blue, yellow, green, yellow-green, orange, purple, or the like. The coloring agent described above can typically be contained in the adhesive layer in a state of being dispersed in the constituent material of the adhesive layer (may be in a state of being dissolved). As the coloring agent, one or two or more kinds of materials capable of reducing the total light transmittance among the pigments and dyes conventionally known can be used. As the pigments, inorganic pigments and organic pigments can be listed. As the dyes, for example, azo dyes, anthraquinones, quinophthalones, styryl dyes, diphenylmethane, triphenylmethane, oxazines, triazines, xanthan gum, methanes, azomethines, acridines, diazines can be listed. The coloring agent can be used alone or in combination of two or more kinds as appropriate.

[0102] (Black coloring agent)

[0103] Since the light shielding property can be efficiently adjusted with a small amount of coloring agent, a black coloring agent can be preferably used. As specific examples of the black coloring agent, carbon black, graphite, aniline black, perylene black, cyanine black, activated carbon, molybdenum disulfide, chromium complex, anthraquinone coloring agent, or the like can be listed. The black coloring agent can be used alone or in combination of two or more kinds as appropriate.

[0104] (Carbon black particles)

[0105] In some preferable modes, the adhesive layer contains carbon black particles. As the carbon black particles used, carbon black particles generally referred to as carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, pine smoke, or the like) can be used without particular limitation. In addition, as the carbon black particles, surface-modified carbon black particles having a functional group such as a carboxyl group, an amino group, a sulfonic acid group, a silicon-containing group (for example, an alkoxysilyl group, an alkylsilyl group), or the like can also be used. Such surface-modified carbon black particles are also referred to as self-dispersing carbon black, and do not require the addition of a dispersant, or can reduce the amount of the dispersant to be added. The carbon black particles described above can be used alone or in combination of two or more kinds.

[0106] In the manner in which the adhesive layer contains carbon black particles, the content of the colorant other than the carbon black particles in the adhesive layer is not particularly limited, and can be set to less than 13% by weight, preferably less than 10% by weight, for example, can be less than 5% by weight, and can be set to less than 3.0% by weight (for example, less than 2.0% by weight, further less than 1% by weight). The technology disclosed herein can preferably be implemented in a manner in which the adhesive layer has substantially no colorant other than the carbon black particles. Note that, in the present specification, "substantially no" means no intentional addition, and for example, the content in the adhesive layer can be 0.3% by weight or less (for example, 0.1% by weight or less, typically 0.01% by weight or less).

[0107] Since the light-blocking property of the adhesive layer can be efficiently adjusted with a small amount of colorant, a particulate colorant (pigment) can be preferably used. In some preferred manners, a colorant having an average particle diameter of about 10 nm or more (for example, about 30 nm or more) can be used (for example, a particulate black colorant such as carbon black). The average particle diameter described above can be, for example, about 50 nm or more, can be about 100 nm or more, and can be about 150 nm or more. The upper limit of the average particle diameter of the colorant described above is not particularly limited, and can be, for example, about 3000 nm or less, and can be about 1000 nm or less. From the viewpoint of improving the light-blocking property, it is appropriate that the average particle diameter of the colorant described above be about 500 nm or less, is preferably about 300 nm or less, is more preferably about 250 nm or less, and is further preferably 200 nm or less (for example, about 120 nm or less, further about 100 nm or less).

[0108] Note that, in the present specification, the average particle diameter of the colorant refers to the volume average particle diameter, and specifically refers to the particle diameter at which the cumulative value in the particle size distribution measured using a particle size distribution measuring device based on the laser scattering / diffraction method is 50% (50% volume average particle diameter; hereinafter, sometimes abbreviated as D 50 As the measuring device, for example, a product manufactured by Microtrac Bell Co., Ltd., product name "Microtrac MT3000II", or an equivalent thereof can be used.

[0109] In the technology disclosed herein, there are no particular limitations on the form in which the colorant (preferably a black colorant such as carbon black particles) is added to the adhesive composition. The colorant, such as carbon black particles, can be added to the adhesive composition in the form of a dispersion in which the particles are dispersed in a dispersion medium. There are no particular limitations on the dispersion medium constituting the dispersion, and examples include: water (ion-exchanged water, reverse osmosis water, distilled water, etc.), various organic solvents (alcohols such as ethanol; ketones such as acetone; ethers such as butyl cellosolve and propylene glycol monomethyl ether acetate; esters such as ethyl acetate; aromatic hydrocarbons such as toluene; and mixed solvents thereof), and aqueous mixtures of water and the aforementioned organic solvents. The aforementioned dispersion may contain the aforementioned dispersant. By mixing the aforementioned dispersion into the adhesive composition, the adhesive composition contains a colorant (preferably a black colorant such as carbon black particles) and may also contain a dispersant.

[0110] The content of the colorant (preferably a black colorant such as carbon black particles) is not particularly limited and can be appropriately set considering the thickness of the adhesive layer, the desired opacity, and the required adhesive properties. It is appropriate for the colorant content in the adhesive layer to be about 0.1% by weight or more. From the viewpoint of opacity, it is preferably about 0.5% by weight or more, more preferably about 1% by weight or more, further preferably about 2% by weight or more, particularly preferably about 2.5% by weight or more, and for example, about 3% by weight or more. Furthermore, the content of the aforementioned colorant (preferably a black colorant such as carbon black particles) can be set to about 50% by weight or less, and about 30% by weight or less is appropriate. From the viewpoint of adhesive properties, it is preferably about 10% by weight or less. When prioritizing increasing the refractive index and emphasizing adhesive properties such as adhesive strength, the content of the aforementioned colorant (preferably a black colorant such as carbon black particles) is preferably about 7% by weight or less, more preferably about 5% by weight or less, and can be about 3% by weight or less.

[0111] The technology disclosed herein has the following characteristics: it contains the aforementioned particle P. HRI When implemented in the manner of a binder layer containing a colorant (e.g., a black colorant, preferably carbon black particles), the particles P HRI The ratio of colorant to particle P is set to achieve the target refractive index and opacity, and therefore is not limited to a specific range. HRI The ratio of the colorant to the binder is preferably set to a range that does not impair the dispersibility, compatibility, etc., of both within the adhesive layer. For example, particle P HRI Content C HRI The content of carbon black particles as a colorant, C CB weight ratio (C) HRI / C CB The value can be set within the range of 1 to 100. This allows for better utilization of particle P. HRI From the perspective of effectiveness, the above ratio (C) HRI / CCB ) is preferably 10 or more, more preferably 20 or more, further preferably 25 or more, and can be 30 or more. From the viewpoint of appropriately exhibiting the coloring effect (blackening) due to the carbon black particles in the composition containing the particles P HRI , the above ratio (C HRI / C CB ) is preferably 70 or less, more preferably 50 or less, and further preferably 40 or less, and can be 35 or less.

[0112] The adhesive composition disclosed herein can contain a component that helps improve the dispersibility of the above coloring agent. The dispersibility-improving component can be, for example, a polymer, an oligomer, a liquid resin, a surfactant (anionic surfactant, cationic surfactant, nonionic surfactant, amphoteric surfactant), or the like. The dispersibility-improving component can be used alone or in combination with two or more. The above dispersibility-improving component is preferably dissolved in the adhesive composition. The above oligomer can be, for example, a low-molecular-weight polymer (e.g., an acrylic oligomer having a Mw of less than about 10 x 10 4 , preferably less than 5 x 10 4 , which contains one or two or more of the above exemplified monomer components). The above liquid resin can be, for example, a tackifying resin having a softening point of about 50°C or less, more preferably about 40°C or less (typically, a tackifying resin such as a rosin-based, terpene-based, or hydrocarbon-based tackifying resin, e.g., hydrogenated methyl rosin, etc.). With such a dispersibility-improving component, it is possible to suppress uneven dispersion of the coloring agent (e.g., a particulate black coloring agent such as carbon black), and further, it is possible to suppress uneven color of the adhesive layer. Thus, it is possible to form an adhesive sheet having better appearance quality.

[0113] The method of adding the dispersibility-improving component is not particularly limited, and it can be contained in a liquid containing the coloring agent (preferably a black coloring agent such as carbon black particles) before being compounded into the adhesive composition, or it can be supplied to the adhesive composition at the same time as the coloring agent or before or after the coloring agent is added.

[0114] The content of the dispersibility-improving component is not particularly limited, and is desirably set to be 20% by mass or less (preferably 10% by mass or less, more preferably 7% by mass or less, for example, 5% by mass or less) of the adhesive layer as a whole from the viewpoint of suppressing the influence on the adhesion properties (for example, reduction in cohesiveness). In some modes, the content of the dispersibility-improving component can be set to be 10 times or less (preferably 5 times or less, for example, 3 times or less) of the weight of the colorant. On the other hand, the content is desirably set to be 0.2% by mass or more (typically 0.5% by mass or more, preferably 1% by mass or more) of the adhesive layer as a whole from the viewpoint of appropriately exerting the effect of the dispersibility-improving component. In some modes, the content of the dispersibility-improving component can be set to be 0.2 times or more (preferably 0.5 times or more, for example, 1 times or more) of the weight of the colorant.

[0115] (tackifying resin)

[0116] The adhesive layer in the technology disclosed herein can contain a tackifying resin. Thereby, the peel strength of the adhesive sheet can be increased. As the tackifying resin, one or two or more selected from among various tackifying resins known in the art such as phenol-based tackifying resins, terpene-based tackifying resins, modified terpene-based tackifying resins, rosin-based tackifying resins, hydrocarbon-based tackifying resins, epoxy-based tackifying resins, polyamide-based tackifying resins, elastomer-based tackifying resins, ketone-based tackifying resins, and the like can be used.

[0117] Examples of the phenol-based tackifying resin include terpene phenol resins, hydrogenated terpene phenol resins, alkyl phenol resins, and rosin phenol resins.

[0118] The terpene phenol resin refers to a polymer containing a terpene residue and a phenol residue, and is a concept including both a copolymer of a terpene compound and a phenol compound (terpene-phenol copolymer resin) and a resin obtained by phenol-modification of a homopolymer or a copolymer of a terpene compound (phenol-modified terpene resin). As a preferable example of the terpene compound constituting such a terpene phenol resin, monoterpenes such as α-pinene, β-pinene, limonene (containing d-body, l-body, and d / l-body (terpene hydrate)), and the like can be listed. The hydrogenated terpene phenol resin refers to a hydrogenated terpene phenol resin having a structure obtained by hydrogenation of such a terpene phenol resin. It is also sometimes referred to as a hydrogenated terpene phenol resin.

[0119] The alkyl phenol resin is a resin (oily phenol resin) obtained from an alkyl phenol and formaldehyde. As examples of the alkyl phenol resin, novolak type and resol type can be listed.

[0120] Rosin phenol resins are typically phenol-modified products of rosins or various derivatives of rosins described above (including rosin esters, unsaturated fatty acid-modified rosins, and unsaturated fatty acid-modified rosin esters). Examples of rosin phenol resins include rosin phenol resins obtained by a method of adding phenol to rosins or various derivatives of rosins described above with an acid catalyst and performing thermal polymerization, and the like.

[0121] Examples of terpene-based tackifying resins include polymers of terpene-based compounds (typically monoterpenes) such as α-pinene, β-pinene, d-limonene, l-limonene, terpinenes, and the like. The polymers can be homopolymers of one terpene-based compound, or copolymers of two or more terpene-based compounds. As homopolymers of one terpene-based compound, α-pinene polymers, β-pinene polymers, terpinene polymers, and the like can be given. As examples of modified terpene resins, resins obtained by modifying the above-described terpene resins can be given. Specifically, styrene-modified terpene resins, hydrogenated terpene resins, and the like can be given as examples.

[0122] The concept of rosin-based tackifying resins described herein includes both rosins and rosin derivative resins. Examples of rosins include unmodified rosins (crude rosin) such as gum rosin, wood rosin, tall oil rosin, and the like; and modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, and other chemically modified rosins) obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, and the like.

[0123] Rosin derivative resins are typically derivatives of rosins as described above. The concept of rosin resins described herein includes derivatives of unmodified rosins and derivatives of modified rosins (including hydrogenated rosin, disproportionated rosin, and polymerized rosin). Rosin esters such as unmodified rosin esters as esters of unmodified rosins with alcohols, modified rosin esters as esters of modified rosins with alcohols, and the like can be given. Unsaturated fatty acid-modified rosins obtained by modifying rosins with unsaturated fatty acids can be given. Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids can be given. Rosin alcohols obtained by reducing carboxyl groups of rosins or various derivatives of rosins described above (including rosin esters, unsaturated fatty acid-modified rosins, and unsaturated fatty acid-modified rosin esters) can be given. Metal salts of rosins or various derivatives of rosins described above can be given. As specific examples of rosin esters, methyl esters, triethylene glycol esters, glycerol esters, pentaerythritol esters, and the like of unmodified rosins or modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, and the like) can be given.

[0124] As examples of hydrocarbon-based tackifying resins, various resins of hydrocarbons such as aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers and the like), aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, coumarone-based resins, coumarone-indene-based resins, and the like can be given.

[0125] The softening point of the tackifying resin is not particularly limited. From the viewpoint of improving the cohesiveness, in some embodiments, it can be preferable to use a tackifying resin having a softening point (softening temperature) of about 80°C or higher (preferably about 100°C or higher). The technology disclosed herein can be preferably implemented in such a manner that the total amount of the tackifying resin contained in the adhesive layer is set to 100% by weight, of which more than 50% by weight (more preferably more than 70% by weight, for example, more than 90% by weight) is a tackifying resin having the above-mentioned softening point. For example, it can be preferable to use a phenolic tackifying resin (terpene phenol resin or the like) having such a softening point. The tackifying resin can contain, for example, a terpene phenol resin having a softening point of about 135°C or higher (furthermore, about 140°C or higher). The upper limit of the softening point of the tackifying resin is not particularly limited. From the viewpoint of improving the adhesion to the adherend, in some embodiments, it can be preferable to use a tackifying resin having a softening point of about 200°C or lower (more preferably about 180°C or lower). Note that the softening point of the tackifying resin can be measured based on the softening point test method (ring and ball method) prescribed in JIS K2207.

[0126] In some preferred embodiments, the tackifying resin described above can contain one or two or more kinds of phenolic tackifying resins (typically, terpene phenol resins). The technology disclosed herein can be preferably implemented, for example, in such a manner that the total amount of the tackifying resin is set to 100% by weight, of which about 25% by weight or more (more preferably about 30% by weight or more) is a terpene phenol resin. It can be that about 50% by weight or more of the total amount of the tackifying resin is a terpene phenol resin, or it can be that about 80% by weight or more (for example, about 90% by weight or more) is a terpene phenol resin. It can also be that substantially all (for example, about 95% by weight to 100% by weight, further about 99% by weight to 100% by weight) of the tackifying resin is a terpene phenol resin.

[0127] Although not particularly limited, in some embodiments, the tackifying resin described above can contain a tackifying resin having a hydroxyl value higher than 20 mgKOH / g. Of these, a tackifying resin having a hydroxyl value of 30 mgKOH / g or more is preferable. Hereinafter, a tackifying resin having a hydroxyl value of 30 mgKOH / g or more will sometimes be referred to as a “high hydroxyl value resin”. With a tackifying resin containing such a high hydroxyl value resin, it is possible to achieve an adhesive layer that has excellent adhesion to the adherend and high cohesiveness. In some embodiments, the tackifying resin described above can contain a high hydroxyl value resin having a hydroxyl value of 50 mgKOH / g or more (more preferably 70 mgKOH / g or more).

[0128] Note that, as the value of the hydroxyl value described above, a value measured according to the potentiometric titration method prescribed in JIS K0070:1992 can be used.

[0129] As the high-hydroxyl group resin, a resin having a hydroxyl group value of a prescribed value or more among the various tackifying resins described above can be used. The high-hydroxyl group resin can be used alone or in combination with two or more. For example, as the high-hydroxyl group resin, a phenolic tackifying resin having a hydroxyl group value of 30 mgKOH / g or more can be preferably used. In some preferred modes, as the tackifying resin, at least a terpene phenol resin having a hydroxyl group value of 30 mgKOH / g or more is used. The terpene phenol resin is suitable because the hydroxyl group value can be arbitrarily controlled by the copolymerization ratio of the phenol.

[0130] The upper limit of the hydroxyl group value of the high-hydroxyl group resin is not particularly limited. From the viewpoint of compatibility with the base polymer and the like, it is appropriate that the hydroxyl group value of the high-hydroxyl group resin be 200 mgKOH / g or less, preferably 180 mgKOH / g or less, more preferably 160 mgKOH / g or less, and further preferably 140 mgKOH / g or less. The technology disclosed herein can be preferably implemented in a mode in which the tackifying resin contains a high-hydroxyl group resin (for example, a phenolic tackifying resin, preferably a terpene phenol resin) having a hydroxyl group value of 30 mgKOH / g to 160 mgKOH / g. In some modes, it can be preferable to use a high-hydroxyl group resin having a hydroxyl group value of 30 mgKOH / g to 80 mgKOH / g (for example, 30 mgKOH / g to 65 mgKOH / g). In other modes, it can be preferable to use a high-hydroxyl group resin having a hydroxyl group value of 70 mgKOH / g to 140 mgKOH / g.

[0131] Although not particularly limited, in the case of using a high-hydroxyl group resin, the proportion of the high-hydroxyl group resin (for example, a terpene phenol resin) in the entire tackifying resin contained in the adhesive layer can be set to, for example, 25% by mass or more, preferably 30% by mass or more, and more preferably 50% by mass or more (for example, 80% by mass or more, typically 90% by mass or more). It can also be that substantially all (for example, 95% by mass to 100% by mass, further 99% by mass to 100% by mass) of the tackifying resin is a high-hydroxyl group resin.

[0132] In the case where the adhesive layer contains a tackifying resin, the amount of use of the tackifying resin is not particularly limited, and for example, it can be appropriately set in the range of about 1 part by mass to about 100 parts by mass with respect to 100 parts by mass of the base polymer. From the viewpoint of appropriately exerting the effect of improving the peeling strength, it is appropriate that the amount of use of the tackifying resin be set to 5 parts by mass or more, preferably 10 parts by mass or more, and can be set to 15 parts by mass or more with respect to 100 parts by mass of the base polymer (for example, an acrylic polymer). In addition, from the viewpoint of impact resistance and cohesiveness, it is appropriate that the amount of use of the tackifying resin be set to 50 parts by mass or less, can be set to 40 parts by mass or less, and can be set to 30 parts by mass or less with respect to 100 parts by mass of the base polymer (for example, an acrylic polymer).

[0133] (Cross-linking agent)

[0134] In the technology disclosed herein, the adhesive composition used in the formation of the adhesive layer can include a cross-linking agent as needed. The kind of cross-linking agent is not particularly limited, and can be appropriately selected from cross-linking agents known in the art. As such cross-linking agents, for example, isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, hydrazine-based cross-linking agents, amine-based cross-linking agents, silane coupling agents, and the like can be listed. Among them, isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, more preferably isocyanate-based cross-linking agents, epoxy-based cross-linking agents, and particularly preferably isocyanate-based cross-linking agents. By using isocyanate-based cross-linking agents, there is a tendency that the cohesion of the adhesive layer can be obtained, and more excellent impact resistance than other cross-linking systems is obtained. In addition, the use of isocyanate-based cross-linking agents is advantageous from the viewpoint of improving the adhesive force to a polyester resin-made adherend such as PET. The cross-linking agent can be used alone or in combination with two or more.

[0135] As the isocyanate-based cross-linking agent, a polyfunctional isocyanate (refers to a compound having two or more isocyanate groups per molecule, including a substance having an isocyanurate structure.) can be preferably used. The isocyanate-based cross-linking agent can be used alone or in combination with two or more.

[0136] As examples of the polyfunctional isocyanate, aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and the like can be listed.

[0137] As specific examples of the aliphatic polyisocyanate, 1,2-ethylene diisocyanate; 1,2-butylene diisocyanate, 1,3-butylene diisocyanate, 1,4-tetramethylene diisocyanate, and the like butylene diisocyanates; 1,2-hexylene diisocyanate, 1,3-hexylene diisocyanate, 1,4-hexylene diisocyanate, 1,5-hexylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,5-hexylene diisocyanate, and the like hexylene diisocyanates; 2-methyl-1,5-pentane diisocyanate, 3-methyl-1,5-pentane diisocyanate, lysine diisocyanate, and the like can be listed.

[0138] As specific examples of the alicyclic polyisocyanates, there can be mentioned isophorone diisocyanate; 1,2-cyclohexyl diisocyanate, 1,3-cyclohexyl diisocyanate, 1,4-cyclohexyl diisocyanate, and the like; 1,2-cyclopentyl diisocyanate, 1,3-cyclopentyl diisocyanate, and the like; hydrogenated xylene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethyl xylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and the like.

[0139] As specific examples of the aromatic polyisocyanates, there can be mentioned 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthalene 1,4-diisocyanate, naphthalene 1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate, xylylene 1,4-diisocyanate, xylylene 1,3-diisocyanate, and the like.

[0140] As the preferred polyfunctional isocyanate, there can be exemplified a polyfunctional isocyanate having three or more isocyanate groups per molecule on average. The tri- or higher functional isocyanate can be a polymer (typically a dimer or a trimer) of di- or tri- or higher functional isocyanate, a derivative (for example, an addition reaction product of a polyhydric alcohol with two or more molecules of a polyfunctional isocyanate), a polymer, or the like. For example, there can be mentioned a dimer of diphenylmethane diisocyanate or a trimer of diphenylmethane diisocyanate, an isocyanurate of hexamethylene diisocyanate (a trimer addition product of an isocyanurate structure), a reaction product of trimethylolpropane with toluene diisocyanate, a reaction product of trimethylolpropane with hexamethylene diisocyanate, a polymeric methylene polyphenyl isocyanate, a polyether polyisocyanate, a polyester polyisocyanate, and the like. As commercially available products of the polyfunctional isocyanate, there can be mentioned "DURANATE TPA-100" manufactured by Asahi Kasei Chemicals Corporation, "CORONATE L" manufactured by DKS Co., Ltd., "CORONATE HL" of DKS Co., Ltd., "CORONATE HK" of DKS Co., Ltd., "CORONATE HX" of DKS Co., Ltd., "CORONATE 2096" of DKS Co., Ltd., and the like.

[0141] The amount of use of the isocyanate-based crosslinking agent is not particularly limited. For example, it can be set to 0.5 parts by weight or more with respect to 100 parts by weight of the base polymer. From the viewpoint of balancing cohesiveness and adhesion, impact resistance, and the like, the amount of use of the isocyanate-based crosslinking agent can be set to 1.0 parts by weight or more, and can also be set to 1.5 parts by weight or more (typically 2.0 parts by weight or more, for example, 2.5 parts by weight or more) with respect to 100 parts by weight of the base polymer. On the other hand, from the viewpoint of improving adhesion to adherends, it is appropriate that the amount of use of the isocyanate-based crosslinking agent is set to 10 parts by weight or less with respect to 100 parts by weight of the base polymer, and can be set to 8 parts by weight or less, and can also be set to 5 parts by weight or less (for example, 3 parts by weight or less).

[0142] In some preferred modes, as the crosslinking agent, an isocyanate-based crosslinking agent and at least one crosslinking agent different in kind of crosslinkable functional group from the isocyanate-based crosslinking agent can be used in combination. According to the technology disclosed herein, by using in combination a crosslinking agent other than an isocyanate-based crosslinking agent (i.e., a crosslinking agent different in kind of crosslinkable reactive group from the isocyanate-based crosslinking agent. Hereinafter also referred to as "non-isocyanate-based crosslinking agent".) and an isocyanate-based crosslinking agent, excellent cohesiveness can be exerted. For example, in a configuration including a rust preventive such as an azole-based rust preventive, high heat-resistant cohesiveness and excellent metal corrosion prevention can be appropriately balanced. Note that the adhesive layer in the technology disclosed herein can contain the above crosslinking agent in a state after crosslinking reaction, a state before crosslinking reaction, a state in which a part of the crosslinking reaction is performed, an intermediate or a complex of these states, or the like. The above crosslinking agent is typically contained in the adhesive layer mainly in a state after crosslinking reaction.

[0143] The kind of non-isocyanate-based crosslinking agent that can be used in combination with the isocyanate-based crosslinking agent is not particularly limited, and can be appropriately selected from the above crosslinking agents. The non-isocyanate-based crosslinking agent can be used alone or in combination with two or more kinds.

[0144] In some preferred modes, an epoxy-based crosslinking agent can be used as the non-isocyanate-based crosslinking agent. For example, by using an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent in combination, cohesiveness and impact resistance can be easily balanced. As the epoxy-based crosslinking agent, a compound having two or more epoxy groups in one molecule can be used without particular limitation. An epoxy-based crosslinking agent having three to five epoxy groups in one molecule is preferred. The epoxy-based crosslinking agent can be used alone or in combination with two or more kinds.

[0145] While there are no specific restrictions, specific examples of epoxy crosslinking agents include: N,N,N',N'-tetraglycidyl-m-phenylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available epoxy crosslinking agents include: Mitsubishi Gas Chemical Co., Ltd.'s "TETRAD-C" and "TETRAD-X", DIC Corporation's "EPICLON CR-5L", Nagase Chemte X Co., Ltd.'s "Denacol EX-512", and Nissan Chemical Industries Co., Ltd.'s "TEPIC-G".

[0146] There is no particular limitation on the amount of epoxy crosslinking agent used. For example, the amount of epoxy crosslinking agent used can be set to be greater than 0 parts by weight and less than about 1 part by weight (typically about 0.001 parts by weight to 0.5 parts by weight) relative to 100 parts by weight of the base polymer. From the viewpoint of appropriately exerting the effect of improving cohesion, it is appropriate to set the amount of epoxy crosslinking agent used to be more than about 0.002 parts by weight relative to 100 parts by weight of the base polymer, preferably more than about 0.005 parts by weight, and more preferably more than about 0.008 parts by weight. Furthermore, from the viewpoint of improving the adhesion to the adhered material, it is appropriate to set the amount of epoxy crosslinking agent used to be less than about 0.2 parts by weight relative to 100 parts by weight of the base polymer, preferably less than about 0.1 parts by weight, more preferably less than about 0.05 parts by weight, and even more preferably less than about 0.03 parts by weight (for example, less than about 0.025 parts by weight). By reducing the amount of epoxy crosslinking agent used, there is a tendency to improve impact resistance.

[0147] In the disclosed technology, there are no particular limitations on the relationship between the content of isocyanate crosslinking agents and the content of non-isocyanate crosslinking agents (e.g., epoxy crosslinking agents). The content of non-isocyanate crosslinking agents can, for example, be set to about 1 / 50 or less of the content of isocyanate crosslinking agents. From the viewpoint of more appropriately balancing the adhesion and cohesion of the adhered materials, it is appropriate to set the content of non-isocyanate crosslinking agents, on a weight basis, to be about 1 / 75 or less of the content of isocyanate crosslinking agents, and preferably to be about 1 / 100 or less (e.g., 1 / 150 or less). Furthermore, from the viewpoint of appropriately leveraging the effects of combining isocyanate crosslinking agents and non-isocyanate crosslinking agents (e.g., epoxy crosslinking agents), it is appropriate to set the content of non-isocyanate crosslinking agents to be about 1 / 1000 or more, for example, about 1 / 500 or more of the content of isocyanate crosslinking agents.

[0148] There is no particular limitation on the total amount (total amount) of crosslinking agent used. For example, it can be set to about 10 parts by weight or less relative to 100 parts by weight of the base polymer (preferably an acrylic polymer), and can be selected from a range of about 0.005 parts by weight to 10 parts by weight, more preferably from about 0.01 parts by weight to 5 parts by weight.

[0149] (Rust inhibitor)

[0150] In some preferred embodiments, the adhesive layer may contain a rust inhibitor. Zolidine-based rust inhibitors are preferably used as rust inhibitors. Adhesive layers containing the aforementioned rust inhibitors are preferred when adhesion to metals or other applications requiring protection against metal corrosion. As azole-based rust inhibitors, azole compounds containing a five-membered ring aromatic compound with two or more heteroatoms, at least one of which is a nitrogen atom, are preferably used as the active ingredient. As the aforementioned azole compound, azole compounds not conventionally used as rust inhibitors for metals such as copper can be appropriately employed.

[0151] Examples of azole compounds include: imidazole, pyrazole, etc. azole, isotonic azole, thiazole, isothiazole, selenazole, 1,2,3-triazole, 1,2,4-triazole, 1,2,5- diazole, 1,3,4- oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,3,4-thiadiazole, tetrazole, 1,2,3,4-thiatriazole, and the like. Derivatives thereof; amine salts thereof; metal salts thereof; and the like. As examples of derivatives of oxadiazoles, compounds including a fused ring of an oxadiazole ring and another ring, such as a benzene ring, can be listed. As specific examples, indazoles, benzimidazoles, benzotriazoles (i.e., 1,2,3-benzotriazole as a structure in which an oxadiazole ring of 1,2,3-triazole is fused with a benzene ring), benzothiazoles, and further alkylbenzotriazoles (e.g., 5-methylbenzotriazole, 5-ethylbenzotriazole, 5-n-propylbenzotriazole, 5-isobutylbenzotriazole, 4-methylbenzotriazole) as derivatives thereof, alkoxybenzotriazoles (e.g., 5-methoxybenzotriazole), alkylaminobenzotriazoles, alkylaminosulfonylbenzotriazoles, mercaptobenzotriazoles, hydroxybenzotriazoles, nitrobenzotriazoles (e.g., 4-nitrobenzotriazole), halogenobenzotriazoles (e.g., 5-chlorobenzotriazole), hydroxyalkylbenzotriazoles, hydroxybenzotriazoles, aminobenzotriazoles, (substituted aminomethyl)-tolyltriazoles, carboxybenzotriazoles, N-alkylbenzotriazoles, bisbenzotriazoles, naphthotriazoles, mercaptobenzothiazoles, aminobenzothiazoles, and the like, amine salts thereof, metal salts thereof, and the like can be listed. As other examples of derivatives of oxadiazoles, oxadiazole derivatives of non-fused ring structures, such as compounds having a substituent on a non-fused oxadiazole ring, such as 3-amino-1,2,4-triazole, 5-phenyl-1H-tetrazole, and the like, can be listed. The oxadiazole compounds can be used alone or in combination of two or more.

[0152] As a preferable example of a compound that can be used as an oxadiazole rust preventive, a benzotriazole rust preventive in which a benzotriazole compound is used as an effective ingredient can be listed. The technology disclosed herein can be preferably implemented, for example, in a manner in which the above-mentioned base polymer is an acrylic polymer and the above-mentioned rust preventive is a benzotriazole rust preventive. In such a manner, an adhesive sheet in which metal corrosion resistance is good and adhesive reliability is excellent can be appropriately achieved. As a preferable example of a benzotriazole compound, 1,2,3-benzotriazole, 5-methylbenzotriazole, 4-methylbenzotriazole, carboxybenzotriazole, and the like can be listed.

[0153] As examples of rust preventives other than oxadiazole rust preventives that can be contained in the adhesive layer disclosed herein, there is no particular limitation, and, for example, amine compounds, nitrite salts, benzylamine, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, dicyclohexylamine benzoate, urea, urotropine, thiourea, phenyl carbamate, N-cyclohexyl carbamic acid cyclohexylamine (CHC), and the like can be listed. These rust preventives other than oxadiazoles (non-oxadiazole rust preventives) can be used alone or in combination of two or more. The technology disclosed herein can be preferably implemented in a manner in which non-oxadiazole rust preventives are not substantially used.

[0154] The content of the rust preventive agent (preferably an azole-based rust preventive agent such as a benzotriazole-based rust preventive agent) is not particularly limited, and for example, it can be set to 0.01 parts by weight or more (typically 0.05 parts by weight or more) with respect to 100 parts by weight of the base polymer. From the viewpoint of obtaining a more excellent effect of preventing metal corrosion, the above content can be 0.1 parts by weight or more, can be 0.3 parts by weight or more, or can be 0.5 parts by weight or more. On the other hand, from the viewpoint of improving the cohesiveness of the adhesive, it is appropriate that the content of the rust preventive agent is set to less than 8 parts by weight with respect to 100 parts by weight of the base polymer, can be set to 6 parts by weight or less, or can be set to 5 parts by weight or less.

[0155] (Other additives)

[0156] The adhesive composition can contain various additives commonly used in the field of adhesives, such as a leveling agent, a crosslinking aid, a plasticizer, a softening agent, an antistatic agent, an anti-aging agent, an ultraviolet absorber, an antioxidant, a light stabilizer, and the like, as needed. For such various additives, conventionally known substances can be used by a conventional method, and are not the features of the present application, and thus detailed description is omitted.

[0157] (Adhesive composition)

[0158] The adhesive layer (layer composed of an adhesive) disclosed herein can be an adhesive layer formed of an aqueous adhesive composition, a solvent-type adhesive composition, a hot-melt-type adhesive composition, or a living energy ray-curable adhesive composition that is cured by irradiation of a living energy ray such as ultraviolet rays or electron rays. The aqueous adhesive composition refers to an adhesive composition in a form in which an adhesive (adhesive layer-forming component) is contained in a solvent (aqueous solvent) in which water is the main component, and is typically a so-called water-dispersible adhesive composition (composition in a form in which at least a part of the adhesive is dispersed in water) or the like. In addition, the solvent-type adhesive composition refers to an adhesive composition in a form in which an adhesive is contained in an organic solvent. As the organic solvent contained in the solvent-type adhesive composition, one or two or more of the organic solvents exemplified as the organic solvents that can be used in the above-described solution polymerization (toluene, ethyl acetate, and the like) can be used without particular limitation. The technology disclosed herein can be preferably implemented in a manner in which an adhesive layer formed of a solvent-type adhesive composition is provided, from the viewpoint of adhesive properties and the like. In the manner in which a solvent-type adhesive layer formed of a solvent-type adhesive composition is provided, the effect of increasing the refractive index brought about by the technology disclosed herein can be preferably achieved.

[0159] As described above, according to the present specification, an adhesive composition containing one or two or more of the components that can be contained in the adhesive layer disclosed herein is provided. By using the adhesive composition, an adhesive sheet having an increased refractive index can be obtained. The above-mentioned adhesive composition contains a base polymer and the particles P HRI In addition, a colorant (preferably a black colorant, more preferably carbon black particles) can be contained. Furthermore, the above-mentioned components that can be contained in the adhesive layer can be contained. The content (wt%) of each component that can be contained in the adhesive layer can be referred to as the content (wt%) based on the solid content (also referred to as the non-volatile content) in the adhesive composition. For details of the other adhesive composition, as described in the adhesive layer, therefore, the repeated description is omitted.

[0160] (Formation of the adhesive layer)

[0161] The adhesive layer disclosed herein can be formed by a method known in the art. For example, a method of forming the adhesive layer by applying the adhesive composition on a surface having a releasing property (releasing surface) and drying it can be employed. For the adhesive sheet having a constitution of a support substrate, for example, a method of forming the adhesive layer by directly applying (typically, coating) the adhesive composition on the support substrate and drying it (direct method) can be employed. In addition, a method of forming the adhesive layer on a surface having a releasing property (releasing surface) by applying the adhesive composition on the surface and drying it, and transferring the adhesive layer to the support substrate (transfer method) can be employed. As the above-mentioned releasing surface, for example, the surface of the releasing liner described later can be preferably used. Note that the adhesive layer disclosed herein is typically formed continuously, but is not limited to such a manner, and for example, can be an adhesive layer formed in a regular or irregular pattern such as a dot pattern, a stripe pattern, and the like.

[0162] The coating of the adhesive composition can be performed using a coating machine known in the art such as a gravure coater, a die coater, a bar coater, and the like. Alternatively, the adhesive composition can be coated by dipping, curtain coating, and the like.

[0163] From the viewpoint of promoting the crosslinking reaction, improving the manufacturing efficiency, and the like, the drying of the adhesive composition is preferably performed under heating. The drying temperature can be set to, for example, about 40°C to about 150°C, and is preferably set to about 60°C to about 130°C. After the adhesive composition is dried, further aging can be performed for the purpose of adjusting the transfer of the components within the adhesive layer, the progress of the crosslinking reaction, the relaxation of the strain possibly present within the adhesive layer, and the like.

[0164] The adhesive layer disclosed herein can be a single layer structure, or can be a multilayer structure having two or more layers. From the viewpoint of productivity and the like, the adhesive layer is preferably a single layer structure. Alternatively, in the adhesive layer, the above-mentioned particles PHRI The contained component such as the coloring agent can be biased in the prescribed thickness region on the surface side of the adhesive layer, and the contained component such as the coloring agent can be biased in the prescribed region of the adhesive layer. By such a configuration, an adhesive sheet having an increased refractive index can be obtained. The adhesive layer having the above-described multilayer structure, and the adhesive layer in which the specific component is biased can be obtained by laminating adhesive layers, adhesive compositions having different compositions under appropriate conditions (temperature, lamination speed, etc.), or the like.

[0165] The thickness of the adhesive layer is not particularly limited. From the viewpoint of avoiding the adhesive sheet from becoming too thick, the thickness of the adhesive layer is preferably about 100 μm or less, more preferably about 70 μm or less, and even more preferably about 50 μm or less (for example, about 30 μm or less). The thickness of the adhesive layer can be set to about 35 μm or less, for example, about 25 μm or less, and further, about 15 μm or less. The adhesive layer having a limited thickness can well cope with the requirements of thickness reduction and light weight. The lower limit of the thickness of the adhesive layer is not particularly limited, and from the viewpoint of the adhesion to the adherend, it is advantageous to set to about 1 μm or more, and it is appropriate to set to about 3 μm or more, preferably about 5 μm or more, and more preferably about 8 μm or more. From the viewpoints of adhesiveness, impact resistance, and the like, it is further preferably about 12 μm or more (for example, about 15 μm or more), and particularly preferably about 20 μm or more, can be about 30 μm or more, can be about 35 μm or more, and can be about 40 μm or more. By setting the thickness to the prescribed value or more, the limited light transmittance (for example, light shielding property) and the desired adhesive properties can be preferably achieved. In addition, according to the adhesive layer having a thickness of the prescribed value or more, more excellent impact resistance can be easily obtained.

[0166] <Supporting Substrate>

[0167] In the form of the adhesive sheet disclosed herein as a single-sided or double-sided adhesive sheet with a base material, as a base material supporting (backing) the adhesive layer, a resin film, paper, cloth, a rubber sheet, a foamed sheet, a metal foil, a composite thereof, or the like can be used. As examples of the resin film, polyethylene (PE), polypropylene (PP), an ethylene-propylene copolymer, a polyolefin film, a polyester film such as polyethylene terephthalate (PET), a vinyl chloride resin film, a vinyl acetate resin film, a polyimide resin film, a polyamide resin film, a fluorine-containing resin film, cellophane, and the like can be listed. As examples of the paper, Japanese paper, kraft paper, cellophane, fine paper, synthetic paper, surface-coated paper, and the like can be listed. As examples of the cloth, woven cloth, nonwoven cloth, and the like obtained by using various fiber-like substances alone or in a blend, or the like can be listed. As the fiber-like substances, cotton, spun rayon, abaca, pulp, rayon, acetate fiber, polyester fiber, polyvinyl alcohol fiber, polyamide fiber, polyolefin fiber, and the like can be exemplified. As examples of the rubber sheet, a natural rubber sheet, a butyl rubber sheet, and the like can be listed. As examples of the foamed sheet, a foamed polyurethane sheet, a foamed neoprene sheet, and the like can be listed. As examples of the metal foil, an aluminum foil, a copper foil, and the like can be listed.

[0168] Note that the nonwoven fabric referred to herein is mainly a concept of an adhesive sheet nonwoven fabric used in the field of adhesive tapes and other adhesive sheets, and typically refers to a nonwoven fabric produced using a general paper machine (sometimes referred to as a so-called "paper").

[0169] As the support base material constituting the adhesive sheet with a base material, a support base material containing a resin film as a base film can be preferably used. The base film is typically a member that can independently maintain a shape (independent). The support base material in the technology disclosed herein can be substantially constituted by such a base film. Alternatively, the support base material can include an auxiliary layer in addition to the base film. As examples of the auxiliary layer, a colored layer, a reflective layer, a primer layer, an antistatic layer, and the like provided on the surface of the base film can be listed.

[0170] The resin film is a film in which a resin material is used as a main component (e.g., a component included in the resin film at a content of more than 50% by weight). As examples of the resin film, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, and the like polyolefin-based resin films; polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), and the like polyester-based resin films; vinyl chloride-based resin films; vinyl acetate-based resin films; polyimide-based resin films; polyamide-based resin films; fluorine-containing resin films; cellophane; and the like can be listed. The resin film can be a rubber-based film such as a natural rubber film or a butyl rubber film. Among them, from the viewpoint of workability and processability, a polyester film is preferred, and a PET film is particularly preferred. Note that, in the present specification, the "resin film" is typically a non-porous sheet, and is a concept that is distinguished from (in other words, excludes) so-called nonwoven fabric and woven fabric. The resin film can be any one of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film.

[0171] A coloring agent can be contained in the support base material (e.g., resin film). Thereby, the light transmittance (light blocking property) of the support base material can be adjusted. Adjusting the light transmittance (e.g., vertical light transmittance) of the support base material contributes to adjusting the light transmittance of the support base material, and further adjusting the light transmittance of the adhesive sheet containing the support base material.

[0172] As the coloring agent, the same coloring agent as can be contained in the adhesive layer can be used, and a conventionally known pigment or dye can be used. The coloring agent is not particularly limited, and can be, for example, a black, gray, white, red, blue, yellow, green, yellowish green, orange, purple, gold, silver, pearl, or the like coloring agent.

[0173] In some modes, since the light blocking property (e.g., vertical light transmittance) can be efficiently adjusted by a small amount of coloring agent, as the coloring agent for the support base material, a black coloring agent can be preferably used. As a specific black coloring agent, the black coloring agents exemplified as the coloring agent that can be contained in the adhesive layer can be listed. In some preferred modes, a pigment having an average particle diameter of 10 nm to 500 nm, more preferably 10 nm to 120 nm (e.g., a particulate black coloring agent such as carbon black) can be used.

[0174] The use amount of the coloring agent in the support base material (e.g., resin film) is not particularly limited, and can be set to an amount that is appropriately adjusted in a manner that can impart a desired optical property. The use amount of the coloring agent can be appropriately set to about 0.1% by weight to about 30% by weight of the weight of the support base material, and can be set to, for example, 0.1% by weight to 25% by weight (typically, 0.1% by weight to 20% by weight).

[0175] Various additives such as a filler (inorganic filler, organic filler, etc.), dispersing agent (surfactant, etc.), anti-aging agent, antioxidant, ultraviolet absorber, antistatic agent, lubricant, plasticizer, etc. can be incorporated in the above-mentioned support substrate (e.g., resin film) as needed. The incorporation ratio of the various additives can be about less than 30% by weight (e.g., about less than 20% by weight, typically about less than 10% by weight).

[0176] The above-mentioned support substrate (e.g., resin film) can be a single layer structure or can have a multi-layer structure of two, three, or more layers. From the viewpoint of shape stability, the support substrate is preferably a single layer structure. In the case of a multi-layer structure, at least one layer (preferably all layers) is preferably a layer having a continuous structure of the above-mentioned resin (e.g., polyester-based resin). The manufacturing method of the support substrate (typically resin film) is appropriately adopted from the conventionally known methods without particular limitation. For example, the conventionally known general film molding methods such as extrusion molding, inflation molding, T-die casting molding, calender roll molding, etc. can be appropriately adopted.

[0177] The support substrate can be colored by a colored layer disposed on the surface of the base film (preferably resin film). In the substrate configured to include a base film and a colored layer as such, the above-mentioned base film can or can not contain a coloring agent. The above-mentioned colored layer can be disposed on either surface of the base film or on both surfaces. In the configuration in which the colored layers are respectively disposed on both surfaces of the base film, the configurations of these colored layers can be the same or different.

[0178] Such a colored layer can be typically formed by applying a colored layer-forming composition containing a coloring agent and a binder on the base film. As the coloring agent, the same pigments and dyes as those which can be contained in the adhesive layer, resin film can be used, which are conventionally known. As the binder, a material known in the field of paints or printing can be used without particular limitation. For example, polyurethane, phenol resin, epoxy resin, urea melamine resin, polymethyl methacrylate, etc. can be exemplified. The colored layer-forming composition can be, for example, solvent type, ultraviolet curing type, thermal curing type, etc. The formation of the colored layer can be performed by adopting the means which have been adopted in the formation of the colored layer without particular limitation. For example, a method of forming a colored layer (printed layer) by printing by gravure printing, flexographic printing, offset printing, etc. can be preferably adopted.

[0179] The colored layer can be a single layer structure composed of one layer as a whole, or a multi-layer structure including two or more sub-colored layers. The colored layer of the multi-layer structure including two or more sub-colored layers can be formed, for example, by repeating the coating (e.g., printing) of the colored layer-forming composition. The color and the amount of the colorant contained in each sub-colored layer can be the same or different. In the colored layer for imparting light-shielding properties, it is particularly meaningful to form a multi-layer structure from the viewpoint of improving the reliability of light leakage prevention to prevent the generation of pinholes.

[0180] The thickness of the colored layer as a whole is preferably about 1 μm to about 10 μm, more preferably about 1 μm to about 7 μm, and for example, can be set to about 1 μm to about 5 μm. In the colored layer including two or more sub-colored layers, the thickness of each sub-colored layer is preferably about 1 μm to about 2 μm.

[0181] The thickness of the support substrate is not particularly limited. From the viewpoint of avoiding the adhesion sheet from becoming too thick, the thickness of the support substrate can be set to, for example, about 200 μm or less (e.g., about 100 μm or less). Depending on the purpose of use and the manner of use of the adhesion sheet, the thickness of the support substrate can be about 70 μm or less, about 30 μm or less, or about 15 μm or less (e.g., about 8 μm or less). The lower limit of the thickness of the support substrate is not particularly limited. From the viewpoints of the handleability, processability, and the like of the adhesion sheet, the thickness of the support substrate is preferably about 2 μm or more, more preferably about 5 μm or more, and for example, about 10 μm or more.

[0182] On the surface of the support substrate, a conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, coating of a primer, or the like can be performed. Such a surface treatment can be a treatment for improving the adhesion of the support substrate to the adhesive layer, in other words, the anchoring of the adhesive layer to the support substrate.

[0183] In addition, in the case where the technology disclosed herein is implemented in the form of a single-sided adhesion sheet with a support substrate, a release treatment can be performed on the back surface of the support substrate as needed. The release treatment can be, for example, a treatment in which a typical release treatment agent such as an organic silicone-based, long-chain alkyl-based, or fluorine-based agent is applied in a thin film shape of about 0.01 μm to about 1 μm (e.g., 0.01 μm to 0.1 μm). By performing this release treatment, effects such as easy unwinding of a roll body in which the adhesion sheet is wound in a roll shape can be obtained.

[0184] <Release Liner>

[0185] In the technology disclosed herein, a release liner can be used at the time of formation of the adhesive layer, production of the adhesive sheet, storage of the adhesive sheet before use, circulation, shape processing, and the like. There is no particular limitation on the release liner, and, for example, a release liner having a release-treated layer on the surface of a liner base material such as a resin film, paper, or the like; a release liner including a low-adhesive material containing a fluorine-containing polymer (polytetrafluoroethylene or the like), a polyolefin-based resin (polyethylene, polypropylene, or the like), or the like can be used. The release-treated layer described above can be formed, for example, by surface treatment of the liner base material described above with a silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, or the like.

[0186] <Overall thickness of adhesive sheet>

[0187] The overall thickness of the adhesive sheet (including the adhesive layer, further including the support base material in the configuration having the support base material, but not including the release liner) disclosed herein is not particularly limited. The overall thickness of the adhesive sheet can be set to, for example, about 300 μm or less, and from the viewpoint of thinness, about 200 μm or less is appropriate, and can be about 100 μm or less (for example, about 70 μm or less). The lower limit of the thickness of the adhesive sheet is not particularly limited, and can be set to about 1 μm or more, and it is appropriate, for example, to set it to about 3 μm or more, and preferably to about 6 μm or more, and more preferably to about 10 μm or more (for example, about 15 μm or more). The adhesive sheet having a thickness of the prescribed value or more has a tendency to be excellent in handleability, adhesiveness, and impact resistance. Note that, in the case of the adhesive sheet without a base material, the thickness of the adhesive layer is the overall thickness of the adhesive sheet.

[0188] In some preferred modes, the thickness of the adhesive sheet can be set to about 50 μm or less, and can be, for example, about 35 μm or less, can be about 25 μm or less, and further can be about 15 μm or less or about 10 μm or less (for example, about 7 μm or less). The thickness of the adhesive sheet described above is not particularly limited, and can be preferably applied to the double-coated adhesive sheet without a base material. The lower limit of the thickness of the double-coated adhesive sheet without a base material can be set to about 1 μm or more, and from the viewpoint of adhesive properties such as adhesiveness, it is appropriate to set it to about 3 μm or more (for example, 5 μm or more), and preferably to about 8 μm or more, and more preferably to about 12 μm or more (for example, about 15 μm or more), and from the viewpoint of adhesiveness and impact resistance, further preferably to about 20 μm or more, can be about 30 μm or more, can be about 35 μm or more, and can be about 40 μm or more.

[0189] <Properties of adhesive sheet>

[0190] (Overall light transmittance)

[0191] The total light transmittance of the adhesive sheet disclosed herein can be set according to the purpose of use, the manner of use, and thus is not limited to a particular range. The total light transmittance described above, for example, can be 80% or less. By limiting the total light transmittance to a prescribed value or less, it is possible to adjust the appearance of the adherend through the adhesive sheet, for example, to suppress unevenness in the appearance of the adherend, or to impart design properties. The total light transmittance described above, for example, is less than 80%, and from the viewpoint of improving light shielding properties, can be 75% or less, can be 70% or less, can be 65% or less, or can be 60% or less (for example, 55% or less). In addition, the lower limit of the total light transmittance described above is not particularly limited, and can be substantially 0%, that is, below the detection limit. From the viewpoint of maintaining adhesive properties, including productivity and efficiency in industry, the total light transmittance described above can be greater than 0.01% (for example, greater than 0.05%), and further can be greater than 0.1%, can be 1% or more, for example, can be 3% or more, or can be about 5% or more.

[0192] In some modes, the total light transmittance of the adhesive sheet is greater than 10% and less than or equal to 80%. An adhesive sheet having such light transmittance can adjust the appearance of the adherend through the adhesive sheet, for example, to suppress unevenness in the appearance of the adherend. In addition, it is possible to impart design properties that moderately suppress light transmittance. Furthermore, it is possible to have light shielding properties and have visual recognition properties of the adherend for inspection, etc. In this mode, the total light transmittance described above, for example, is less than 80%, and from the viewpoint of improving light shielding properties, is preferably 75% or less, more preferably 70% or less, further preferably 65% or less, or can be 60% or less (for example, 55% or less). In addition, from the viewpoint of visual recognition properties, design properties, etc. through the adhesive sheet, the total light transmittance described above can be 20% or more, can be 30% or more, can be 50% or more (for example, greater than 50%), or can be greater than 60%.

[0193] In other modes, the total light transmittance of the adhesive sheet is 10% or less. Such an adhesive sheet can have light shielding properties suitable for preventing light leakage and reducing reflection. In this mode, the total light transmittance of the adhesive sheet can be less than 10%. In some preferred modes, the total light transmittance of the adhesive sheet is less than 8.0%, can be less than 6.0%, can be less than 3.0%, more preferably less than 1.00%, further preferably less than 0.50%, and particularly preferably less than 0.30% (for example, less than 0.10%). With an adhesive sheet exhibiting the total light transmittance described above, it is possible to achieve excellent light shielding properties. The lower limit of the total light transmittance described above is not particularly limited, and can be substantially 0%, that is, below the detection limit.

[0194] The total light transmittance of the adhesive sheet can be measured by the method described in the Examples described later. The total light transmittance of the adhesive sheet can be adjusted by the components contained in the adhesive (preferably the kind and the amount of use of the particles such as pigments), the configuration of the colored layer, etc.

[0195] (refractive index)

[0196] The adhesive sheet disclosed herein has an increased refractive index, but since the refractive index can be set according to the purpose of use, the manner of use, it is not limited to a specific range. The refractive index of the adhesive sheet can be, for example, 1.50 or more. Thereby, when pasted on a material having a higher refractive index than the adhesive, light reflection at the interface of the two can be suppressed. For example, for an adhesive sheet having light shielding properties, it is undesirable for light that should be absorbed within the adhesive sheet to be reflected at the interface with the adherend. In such a manner, it is particularly meaningful to suppress light reflection by the constitution having an increased refractive index. From such a viewpoint, the above refractive index is preferably 1.52 or more, can be 1.54 or more, can be 1.56 or more, and can be 1.58 or more. With the adhesive sheet having the above refractive index, in a manner of pasting on a material having a higher refractive index, light reflection at the interface with the adherend can be appropriately suppressed. In some manners, the above refractive index is 1.60 or more, and can be 1.62 or more. With the adhesive sheet having the above refractive index, in a manner of pasting on a material having a higher refractive index, light reflection at the interface with the adherend can be appropriately suppressed. The upper limit of the above refractive index can be different depending on the refractive index of the adherend, etc., and thus is not limited to a specific range, and can be, for example, 1.70 or less, and can be 1.66 or less. The refractive index of the adhesive sheet can be adjusted based on the type of adhesive by the adhesive containing components (such as the monomer composition of the polymer, typically the type, amount of use, arrangement, etc., of the particles P HRI

[0197] In the case of a double-sided adhesive sheet having adhesive faces on both sides, the refractive index of each face (each adhesive face. The first adhesive face and the second adhesive face) can be the same or different. In a manner in which the refractive index of each face (each adhesive face) of the double-sided adhesive sheet is different, one face (for example, the first adhesive face) can have the above refractive index, and the refractive index of the other face (for example, the second adhesive face) can be less than 1.50.

[0198] ​Note that the refractive index of the adhesive sheet in the present specification refers to the refractive index of the surface (adhesive surface) of the adhesive sheet. The refractive index of the adhesive sheet can be measured using a commercially available refractive index measuring device (a multi-wavelength Abbe refractometer or an ellipsometer) under the condition of 23°C. As the multi-wavelength Abbe refractometer, for example, a model "DR-M2" manufactured by ATAGO Co., Ltd. or the like can be used. As the ellipsometer, for example, a product name "EC-400" (manufactured by JA. Woolam Co., Ltd.) or the like can be used. The refractive index of the adhesive sheet can be specifically measured by the method described in the Examples described later. In the refractive index measuring method described later, light having a wavelength of 589 nm is used, but the range of the refractive index to which the technical idea grasped in the present specification is applied is not limited thereto. The concept of the refractive index in the technology disclosed in the present specification includes the refractive index of light having a specific wavelength region selected from the visible light region (380 nm to 780 nm), and can also include the refractive index of light having a specific wavelength region selected from the ultraviolet region (380 nm or less, for example, 100 nm to 380 nm), the infrared region (780 nm or more, for example, 780 nm to 2500 nm).

[0199] (adhesive strength)

[0200] The 180-degree peeling strength (adhesive strength) of the adhesive sheet disclosed herein can vary depending on the purpose of use, the application site, and thus is not limited to a specific range. The adhesive strength of the adhesive sheet can be, for example, 0.3 N / 10 mm or more. From the viewpoint of obtaining good adhesion to the adherend, it is appropriate to set the above 180-degree peeling strength to be about 1.0 N / 10 mm or more, preferably about 2.0 N / 10 mm or more, and more preferably about 3.0 N / 10 mm or more. According to the technology disclosed herein, the adhesive sheet can contain the particles P HRI to achieve a refractive index of a prescribed value or more, and at the same time achieve the above adhesive strength. In some modes, for example, a colorant such as a carbon black particle can be contained to achieve a total light transmittance of a prescribed value or less, and at the same time achieve the above adhesive strength. From the viewpoint of the stability of the adhesion to the adherend, the above adhesive strength can be about 4.0 N / 10 mm or more, or about 5.0 N / 10 mm or more (for example, about 6.0 N / 10 mm or more). The upper limit of the above adhesive strength is not particularly limited, and can be, for example, 12 N / 10 mm or less, or 8 N / 10 mm or less (for example, 5 N / 10 mm or less). The above 180-degree peeling strength can be measured by the method described in the Examples described later.

[0201] (breaking strength)

[0202] The elastic modulus of the adhesive sheet disclosed herein can be appropriately set according to the intended use and application site, and is therefore not limited to a specific range. The tensile strength of some adhesive sheets is about 5000 MPa or less, but can be 1000 MPa or less, or even 100 MPa or less. The tensile strength of some preferred adhesive sheets can be 10 MPa or less. Adhesive sheets with tensile strength below a specified value exhibit good impact resistance and are therefore preferred. The aforementioned tensile strength is, for example, less than 10 MPa, but can be 8 MPa or less, more preferably 7 MPa or less, further preferably 6 MPa or less, particularly preferably 5 MPa or less, and can also be 3 MPa or less (e.g., 1 MPa or less). There is no particular limitation on the lower limit of the aforementioned tensile strength; from the viewpoint of maintaining adhesive properties such as holding force, 0.1 MPa or more is appropriate, preferably 0.5 MPa or more, more preferably 1 MPa or more, and can be 2 MPa or more, 3 MPa or more, or 4 MPa or more. Adhesive sheets with strength above a specified value tend to have excellent operability. The aforementioned tensile strength is determined by the following tensile test.

[0203] [Tension Test]

[0204] Regarding the tensile strength of the adhesive sheet, for a substrateless adhesive sheet without a supporting substrate, the test is conducted under condition (1). For a substrate-supported adhesive sheet with a supporting substrate, the test is conducted under condition (2).

[0205] (Condition (1))

[0206] The adhesive sheet with release film is to be cut into pieces with a length of 150 mm and a cross-sectional area of ​​1 mm². 2 Two release films were peeled off from a test piece of a certain width at 23°C and 50% RH, and the adhesive sheet (adhesive layer) was rolled into a tube. This tube was used as the test piece. Tensile tests were conducted on the test piece using a tensile testing machine (manufactured by Minebea, universal tensile and compression testing machine, device name "Tensile and Compression Testing Machine, TCM-1kNB") with a distance of 120 mm between the clamps and a tensile speed of 50 mm / min. The SS curve was obtained, and the strength (breaking strength) [MPa] of the test piece at fracture was determined.

[0207] (Condition (2))

[0208] A test piece was prepared by cutting an adhesive sheet with a tape peeling film into a size of 10 mm in width and 150 mm in length, and two pieces of the peeling film were peeled off at 23°C and 50% RH to expose the adhesive layer. A tensile test machine (Minebea Co., Ltd., universal tensile compression tester, device name "Tensile Compression Tester, TCM-1kNB") was used to perform a tensile test of the test piece at a distance of 120 mm between the clamps and a tensile speed of 50 mm / min, and a S-S curve was obtained. The strength at the time of breaking of the test piece (breaking strength) was measured [MPa].

[0209] Note that the thickness of the test piece used in the above-described tensile test can be the same as the thickness of the adhesive sheet, or can be different. For example, in the case where the thickness of the adhesive sheet is small, the results obtained by performing the above-described tensile test using a test piece prepared so as to have a thickness of 5 μm or more (for example, about 5 μm to about 200 μm) can be used as the breaking strength of the adhesive sheet. The thickness of the test piece can be adjusted by appropriately overlapping the adhesive sheet, for example. Alternatively, the same adhesive composition as that used in the formation of the adhesive sheet to be measured can be used to prepare a test piece of a thickness that is easy to perform a tensile test, and the above-described tensile test can be performed on the test piece, and the results obtained thereby can be used as the breaking strength of the adhesive sheet. The above-described tensile test can be performed using a test piece having a thickness of about 10 μm to about 50 μm, for example. In addition, it is preferable to apply powder to the adhesive surface at the portion to be clamped at the time of the test, so as to eliminate the influence of tackiness of the adhesive.

[0210] <Usage>

[0211] The adhesive sheet disclosed herein is suitable for use in adhering to a material having a higher refractive index than that of a general adhesive. For example, it is suitable as an adhesive sheet for a portable electronic device. Non-limiting examples of the above-mentioned portable electronic device include: a mobile phone, a smartphone, a tablet personal computer, a notebook personal computer, various wearable devices (for example, a wrist-worn type worn on a wrist like a watch, a modular type worn on a part of a body with a clip, a band, or the like, an eyewear type including a glasses type (a monocular type, a binocular type. Also included are a helmet type.), a clothing type worn on a shirt, a sock, a hat, or the like in the form of, for example, a piece of jewelry, an ear-worn type worn on an ear like an earphone, and the like), a digital still camera, a digital video camera, a sound equipment (a portable music player, a voice recorder, and the like), a calculator (a desk calculator, and the like), a portable game device, an electronic dictionary, an electronic notebook, an electronic book, an in-vehicle information device, a portable radio, a portable television, a portable printer, a portable scanner, a portable modem, and the like. Note that "portable" in the present specification is not sufficient to mean only that it can be carried, but actually has a level of portability that a person (a standard adult) can move relatively easily.

[0212] The adhesive sheet disclosed herein can be preferably used, for example, for the purpose of fixing a pressure-sensitive sensor and other members within a portable electronic device having a pressure-sensitive sensor in such a portable electronic device. In some preferred modes, the adhesive sheet can be used for fixing a pressure-sensitive sensor and other members within an electronic device (typically a portable electronic device) having a function of being able to designate an absolute position on a plate (typically a touch panel) corresponding to a screen by means of a device (typically a pen-type or a mouse-type device) for indicating a position on the screen and a device for detecting the position.

[0213] In addition, the adhesive sheet disclosed herein is also suitable for use in being disposed on the back of a display screen (display portion) such as a touch panel display in a portable electronic device, thereby preventing reflection of light transmitted through the display screen. By disposing the adhesive sheet disclosed herein on the back of the above-mentioned display screen (display portion), it is possible to prevent a decrease in visual recognition of the display screen regardless of the use mode of the portable electronic device. In addition, the above-mentioned reflection can occur due to a metal member disposed on the back side of the display screen, and by using the adhesive sheet disclosed herein for, for example, joining the above-mentioned metal member and the display portion, it is possible to simultaneously achieve joining of the members and imparting light shielding properties.

[0214] In addition, the adhesive sheet disclosed herein is suitable for a portable electronic device in which a light sensor is built in. The above-described portable electronic device and the like can have a light sensor that utilizes light rays such as infrared rays, visible light, and ultraviolet rays for the purpose of operation of the device, sensing of an approach, detection of the brightness of the surroundings (ambient light), data communication, and the like. Although not particularly limited, as the light sensor, an acceleration sensor, a proximity sensor, a brightness sensor (ambient light sensor), and the like can be cited. Such a light sensor has a light-receiving element of light rays such as ultraviolet rays, visible light, and infrared rays, and can also have a light-emitting element of specific light rays such as infrared rays. In other words, the light sensor can contain a light-emitting element and / or a light-receiving element of light rays in a specific wavelength region within a wavelength region including ultraviolet rays, visible light, and infrared rays. For such a device, by applying the technology disclosed herein, reflection of light rays utilized in the light sensor is suppressed, and thus it is possible to prevent a decrease in the operation accuracy of the sensor.

[0215] As a material (object-to-be-adhered material) to which the adhesive sheet disclosed herein is attached, there is no particular limitation, and for example, a metal material such as copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, chromium, zinc, or an alloy containing two or more of these, a resin material such as various resin materials (typically, plastic materials) such as a polyimide-based resin, an acrylic-based resin, a polyether nitrile-based resin, a polyether sulfone-based resin, a polyester-based resin (a PET-based resin, a polyethylene naphthalate-based resin, or the like), a polyvinyl chloride-based resin, a polyphenylene sulfide-based resin, a polyether ether ketone-based resin, a polyamide-based resin (so-called aramid resin, or the like), a polyarylate-based resin, a polycarbonate-based resin, a liquid crystal polymer, or the like, an inorganic material such as alumina, zirconia, soda lime glass, quartz glass, carbon, or the like can be cited. Among these, a metal material such as copper, aluminum, stainless steel, or the like, a polyester-based resin such as PET, a polyimide-based resin, an aramid resin, a polyphenylene sulfide-based resin, or the like (typically, a plastic material) is widely used. The above-described material can be a material of a member constituting a product such as an electronic device. The adhesive sheet disclosed herein can be used by being attached to a member constituted of the above-described material. In addition, the above-described material can be a material of a fixed object (for example, a back member such as an electromagnetic wave shield, a reinforcing plate, or the like) constituting the above-described pressure-sensitive sensor, a display portion, or the like. Note that the fixed object refers to an object to which the adhesive sheet is attached, that is, an object-to-be-adhered. In addition, the back member refers to a member disposed on the opposite side of the surface (the visually recognized side) of the above-described pressure-sensitive sensor, a display portion, or the like in a portable electronic device, for example. In addition, the above-described fixed object can be in any one of a single-layer structure, a multi-layer structure, and the like, and various surface treatments can be applied to the surface (the attachment surface) to which the adhesive sheet is attached. Although not particularly limited, as an example of the fixed object, a back member having a thickness of about 1 pm or more (typically, about 5 pm or more, for example, about 60 pm or more, further, about 120 pm or more) and about 1500 pm or less (for example, about 800 pm or less) can be cited.

[0216] The member, material (at least one adherend in the case of a double-coated adhesive sheet) to which the adhesive sheet disclosed herein is attached can be a member, material containing a material having a higher refractive index than that of a general adhesive. The refractive index of the adherend material is, for example, 1.50 or higher, and there are adherend materials having a refractive index of 1.58 or higher, and adherend materials having a refractive index of 1.62 or higher (for example, about 1.66). Such a high-refractive adherend material is typically a resin material. More specifically, it can be a polyester-based resin such as PET, a polyimide-based resin, an aromatic polyamide resin, a polyphenylene sulfide-based resin, a polycarbonate-based resin, or the like. For such a material, the effect of using the adhesive sheet disclosed herein (suppression of reflection of light caused by a difference in refractive index) can be preferably exerted. The upper limit of the refractive index of the above-mentioned adherend material is, for example, 1.80 or lower, and can be 1.70 or lower. The adhesive sheet disclosed herein can be preferably used in a manner attached to a high-refractive adherend (for example, a member) as described above. As a preferable example of such an adherend, a resin film having a refractive index of 1.50 to 1.80 (preferably, 1.60 to 1.70) can be cited. The above-mentioned refractive index can be measured by the same method as the refractive index of the adhesive sheet.

[0217] In addition, it is appropriate that the difference (refractive index difference) between the refractive index of the member, material (at least one adherend in the case of a double-coated adhesive sheet) to which the adhesive sheet is attached and the refractive index of the adhesive sheet be less than about 0.18. Thereby, reflection of light at the interface of the adherend and the adhesive sheet is preferably suppressed. The above-mentioned refractive index difference is preferably less than 0.12, more preferably less than 0.10, further preferably less than 0.08, and particularly preferably less than 0.05. Note that the above-mentioned refractive index difference is theoretically zero (±0.00), but a difference of about 0.01 or higher (for example, about 0.03 or higher) is practically allowable.

[0218] In addition, the member, material (at least one adherend in the case of a double-coated adhesive sheet) to which the adhesive sheet is attached as an adherend can be a member, material having light transmittance. Such an adherend easily obtains the advantages of the effects brought by the technology disclosed herein (reduction of light reflection at the interface between the adherend and the adhesive sheet) because light from, for example, a sensor reaches the adhesive sheet through the adherend. The total light transmittance of the above-mentioned adherend is, for example, greater than 50%, and can be 70% or more. In some preferred embodiments, the total light transmittance of the above-mentioned adherend is 80% or more, more preferably 90% or more, and can be 95% or more (for example, 95 to 100%). Such a material can be a resin film disposed on the back of an image display portion of various devices such as portable electronic devices. The adhesive sheet disclosed herein can be preferably used in a manner attached to an adherend (for example, a member) having a total light transmittance of 50% or more as described above. The above-mentioned total light transmittance can be measured by the same method as the total light transmittance of the adhesive sheet.

[0219] In some preferred embodiments, the adherend (for example, a member) to which the adhesive sheet is attached can be an adherend having the above-mentioned refractive index and having the above-mentioned total light transmittance. Specifically, the adhesive sheet can be preferably used in a manner attached to an adherend (for example, a member) having a refractive index of 1.50 or more (for example, about 1.58 or more, further about 1.62 or more, typically about 1.66) and a total light transmittance of greater than 50% (for example, can be 70% or more, preferably 80% or more, more preferably 90% or more, further 95% or more). In such a manner of attachment to an adherend material, the effects brought by the technology disclosed herein can be particularly preferably exerted.

[0220] As described above, according to the technology disclosed herein, a laminate having the adhesive sheet disclosed herein and a member to which the adhesive sheet is attached is provided. The member to which the adhesive sheet is attached can be a member having a refractive index of the above-mentioned adherend material. In addition, the difference between the refractive index of the adhesive sheet and the refractive index of the member (refractive index difference) can be the refractive index difference between the above-mentioned adherend and the adhesive sheet. As for the member constituting the laminate, as described as the above-mentioned member, material, adherend, repeated description is not repeated.

[0221] The adhesive sheet disclosed herein is, for example, a light transmittance-limited adhesive sheet, which can be an adhesive sheet having excellent light blocking properties in preferred embodiments, and is thus preferably used for electronic devices containing various light sources such as LEDs (light-emitting diodes), light-emitting elements such as self-luminous organic ELs (electroluminescence). For example, it can be preferably used for electronic devices (typically, portable electronic devices) having liquid crystal display devices that require prescribed optical properties. More specifically, it can be preferably used for the junction of a liquid crystal display module unit (LCD unit) and a backlight module unit (BL unit) in a liquid crystal display device having the LCD unit and the BL unit.

[0222] Figure 4 Fig. 1 is a schematic exploded perspective view showing a configuration example of a liquid crystal display device. As shown in Fig. 1, a portable electronic device 100 has a liquid crystal display device 200. The liquid crystal display device 200 has an LCD unit (member) 210 and a BL unit (member) 220. The liquid crystal display device 200 further includes an adhesive sheet 230 and is configured. In this configuration example, the adhesive sheet 230 is in the form of a double-sided adhesive sheet processed into a frame shape (a frame shape) and is disposed between the BL unit 220 and the LCD unit 210 to join the two. Note that the BL unit 220 is typically configured to include a reflective sheet, a light guide plate, a diffusion sheet, a prism sheet, and the like in addition to a light source. Figure 4

[0223] The adhesive sheet disclosed herein can be used as a joining member processed into various shapes in the joining of, for example, an LCD unit and a BL unit and other joining applications. As a preferable form of such a joining member, a form having a narrow portion with a width of less than 2.0 mm (for example, less than 1.0 mm) can be cited. Some preferable forms of the adhesive sheet can exhibit good light shielding properties and thus can exhibit good performance even when used as a joining member in a form (for example, a frame shape) including a narrow portion as described above. In some forms, the width of the narrow portion described above can be 0.7 mm or less, can be 0.5 mm or less, or can be about 0.3 mm or less. The lower limit of the width of the narrow portion is not particularly limited, and 0.1 mm or more (typically, 0.2 mm or more) is appropriate from the viewpoint of the handleability of the adhesive sheet.

[0224] The narrow portion described above is typically linear. Here, linear means the concept of including a frame shape, a circular shape, and the like, in addition to a straight line shape, a curved line shape, a broken line shape (for example, an L shape), and the like, a composite shape thereof, or an intermediate shape. The circular shape described above is not limited to a circular shape composed of a curved line and is the concept of including a circular shape in which a part or the entire shape is formed in a straight line shape, such as a shape along the outer periphery of a quadrangle (a frame shape), a shape along the outer periphery of a fan shape, and the like. The length of the narrow portion described above is not particularly limited. For example, in a form in which the length of the narrow portion described above is 10 mm or more (typically, 20 mm or more, for example, 30 mm or more), the effects of applying the technology disclosed herein can be appropriately exhibited.

[0225] The matters disclosed in this specification include the following matters.

[0226] [1] A liquid crystal display device having a liquid crystal display module unit, a backlight module unit, and a double-sided adhesive adhesive sheet joining the liquid crystal display module unit and the backlight module unit, wherein

[0227] the adhesive sheet has an adhesive layer, ​

[0228] The adhesive layer contains particles P capable of increasing the refractive index of the adhesive HRI ,

[0229] The particles P present in the adhesive layer HRI have an average particle diameter of less than 100 nm, the particles P present in the adhesive layer HRI have a standard deviation of 20 nm or less, where the average particle diameter and the standard deviation are respectively an average particle diameter and a standard deviation obtained from a number-based particle diameter distribution based on TEM observation.

[0230] [2] The liquid crystal display device according to the above [1], wherein the liquid crystal display device incorporates a light sensor, the light sensor containing a light emitting element and / or a light receiving element that contains light of a specific wavelength region among wavelength regions of ultraviolet rays, visible light and infrared rays.

[0231] [3] The liquid crystal display device according to the above [1] or [2], wherein the particles P present in the adhesive layer HRI have an average particle diameter of less than 80 nm.

[0232] [4] The liquid crystal display device according to any one of the above [1] to [3], wherein the particles P HRI are contained in the adhesive layer at a proportion of more than 20% by weight.

[0233] [5] The liquid crystal display device according to any one of the above [1] to [4], wherein the particles P HRI contain at least one particle selected from the group consisting of metal particles, metal compound particles, organic particles and organic / inorganic composite particles.

[0234] [6] The liquid crystal display device according to any one of the above [1] to [5], wherein the particles P HRI contain a metal oxide.

[0235] [7] The liquid crystal display device according to any one of the above [1] to [6], wherein the adhesive layer is a solvent-type adhesive layer formed from a solvent-type adhesive composition.

[0236] [8] The liquid crystal display device according to any one of the above [1] to [7], wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

[0237] [9] The liquid crystal display device according to any one of the above [1] to [8], wherein the particles P HRI are subjected to surface treatment for hydrophobicity.

[0238]

[10] The liquid crystal display device according to any one of [1] to [9] above, wherein the thickness of the adhesive sheet is in the range of 10 μm to 50 μm.

[0239]

[11] An adhesive sheet which is an adhesive sheet having an adhesive layer, wherein

[0240] the adhesive layer contains high refractive index particles P HRI ,

[0241] the average particle diameter of the particles P HRI existing in the adhesive layer is less than 100 nm, and the standard deviation of the particles P HRI existing in the adhesive layer is 20 nm or less, where the average particle diameter and the standard deviation are respectively an average particle diameter and a standard deviation calculated from a particle size distribution on a number basis based on TEM observation.

[0242]

[12] An adhesive sheet which is an adhesive sheet having an adhesive layer, wherein

[0243] the adhesive layer contains particles P HRI containing a metal oxide,

[0244] the average particle diameter of the particles P HRI existing in the adhesive layer is less than 100 nm, and the standard deviation of the particles P HRI existing in the adhesive layer is 20 nm or less, where the average particle diameter and the standard deviation are respectively an average particle diameter and a standard deviation calculated from a particle size distribution on a number basis based on TEM observation.

[0245]

[13] The adhesive sheet according to

[11] or

[12] above, wherein the average particle diameter of the particles P HRI existing in the adhesive layer is less than 80 nm.

[0246]

[14] The adhesive sheet according to any one of

[11] to

[13] above, wherein the particles P HRI are contained in the adhesive layer at a proportion of more than 20% by weight.

[0247]

[15] The adhesive sheet according to any one of

[11] to

[14] above, wherein the particles P HRI contain at least one particle selected from the group consisting of metal particles, metal compound particles, organic particles, and organic-inorganic composite particles.

[0248]

[16] The adhesive sheet according to

[15] above, wherein the particles P HRI contain a metal oxide.

[0249]

[17] The adhesive sheet according to any one of

[11] to

[16] above, wherein the adhesive layer is a solvent type adhesive layer formed from a solvent type adhesive composition.

[0250]

[18] The adhesive sheet according to any one of

[11] to

[17] above, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

[0251]

[19] The adhesive sheet according to any one of

[11] to

[18] above, wherein the particles P HRI A hydrophobic surface treatment is implemented.

[0252]

[20] The adhesive sheet according to any one of

[11] to

[19] above, wherein the thickness of the adhesive sheet is in the range of 10 μm to 50 μm.

[0253]

[21] The adhesive sheet according to any one of

[11] to

[20] above, wherein the total light transmittance of the adhesive sheet is 80% or less, and the refractive index is 1.50 or more.

[0254]

[22] The adhesive sheet according to

[21] above, wherein the total light transmittance of the adhesive sheet is greater than 10% and 80% or less.

[0255]

[23] The adhesive sheet according to

[21] above, wherein the total light transmittance of the adhesive sheet is 10% or less.

[0256]

[24] The adhesive sheet according to any one of

[21] to

[23] above, wherein the adhesive layer contains at least one particle P HRI .

[0257]

[25] The adhesive sheet according to

[24] above, wherein the adhesive layer contains a particle composed of a metal oxide as the particle P HRI .

[0258]

[26] The adhesive sheet according to

[24] or

[25] above, wherein the average particle diameter of the particle P HRI is in the range of 1 nm to 100 nm.

[0259]

[27] The adhesive sheet according to any one of

[24] to

[26] above, wherein the particle P HRI is contained in the adhesive layer at a proportion of 25% by weight or more.

[0260]

[28] The adhesive sheet according to any one of

[21] to

[27] above, wherein the adhesive layer is an acrylic adhesive layer containing an acrylic polymer as a base polymer.

[0261]

[29] The adhesive sheet according to any one of

[21] to

[28] above, wherein the thickness of the adhesive sheet is in the range of 10 μm to 50 μm.

[0262]

[30] The adhesive sheet according to any one of

[21] to

[29] above, wherein the adhesive layer contains a black colorant.

[0263]

[31] The adhesive sheet according to any one of

[11] to

[30] above, which contains an adhesive layer and is a double-coated adhesive sheet having no substrate, wherein

[0264] the adhesive sheet has a breaking strength of 10 MPa or less.

[0265]

[32] The adhesive sheet according to

[31] above, wherein the adhesive sheet contains at least one kind of particles P selected from the group consisting of metal particles, metal compound particles, organic particles, and organic-inorganic composite particles HRI .

[0266]

[33] The adhesive sheet according to

[32] above, wherein the adhesive sheet contains the particles P in a proportion of 25% by mass to 75% by mass HRI .

[0267]

[34] The adhesive sheet according to

[32] or

[33] above, wherein the particles P have an average particle diameter in the range of 1 nm to 100 nm HRI .

[0268]

[35] The adhesive sheet according to any one of

[32] to

[34] above, wherein the adhesive sheet contains carbon black particles in addition to the particles P HRI .

[0269]

[36] The adhesive sheet according to any one of

[31] to

[35] above, wherein the adhesive sheet has a thickness of 20 μm or more and 50 μm or less.

[0270]

[37] The adhesive sheet according to any one of

[31] to

[36] above, wherein the adhesive sheet contains an acrylic polymer as a base polymer.

[0271]

[38] The adhesive sheet according to any one of

[31] to

[37] above, wherein the adhesive sheet is formed from an adhesive composition containing an isocyanate-based crosslinking agent and / or an epoxy-based crosslinking agent.

[0272]

[39] The adhesive sheet as described in any one of

[31] to

[38] above, wherein the adhesive sheet has a 180-degree peel strength of 2 N / 10 mm or more against the stainless steel sheet.

[0273]

[40] An adhesive sheet as described in any one of

[31] to

[39] above, wherein the adhesive layer comprises a black colorant.

[0274]

[41] An adhesive sheet as described in any one of

[11] to

[40] above, wherein the adhesive layer comprises carbon black particles.

[0275]

[42] The adhesive sheet as described in

[41] above, wherein the volume average particle size of the carbon black particles is less than 500 nm.

[0276]

[43] The adhesive sheet as described in

[41] or

[42] above, wherein the content of the carbon black particles in the adhesive layer is 1% by weight or more.

[0277]

[44] The adhesive sheet as described in any one of

[41] to

[43] above, wherein, in addition to containing the carbon black particles, the adhesive layer also contains at least one particle P selected from metal particles, metal compound particles, organic particles, and organic-inorganic composite particles. HRI .

[0278]

[45] As described in

[44] above, the adhesive sheet wherein the adhesive layer contains particles comprising metal oxides as the particles P HRI .

[0279]

[46] The adhesive sheet as described in

[44] or

[45] above, wherein the particle P HRI The average particle size is in the range of 1 nm to 100 nm.

[0280]

[47] An adhesive sheet as described in any one of

[44] to

[46] above, wherein the particle P HRI Content C HRI Relative to the content C of the carbon black particles CB weight ratio (C) HRI / C CB (In the range of 1 to 100)

[0281]

[48] ​​An adhesive sheet as described in any one of

[41] to

[47] above, wherein the adhesive layer is an acrylic adhesive layer comprising an acrylic polymer as a base polymer.

[0282]

[49] An adhesive composition comprising carbon black particles and particles P that are different from carbon black. HRI ,

[0283] The particle P HRI contains at least one particle selected from the group consisting of metal particles, metal compound particles, organic particles, and organic-inorganic composite particles.

[0284]

[50] The adhesive sheet according to any one of

[11] to

[48] above, wherein the adhesive sheet is used for fixation of a member in a portable electronic device.

[0285]

[51] The adhesive sheet according to any one of

[11] to

[48] above, wherein the adhesive sheet is disposed on the back of a display portion of a portable electronic device.

[0286]

[52] The adhesive sheet according to any one of

[11] to

[48] above, wherein the adhesive sheet is used for a portable electronic device in which a light sensor is built in.

[0287]

[53] The adhesive sheet according to any one of

[11] to

[48] ,

[50] to

[52] above, wherein the adhesive sheet is attached to a material having a refractive index of 1.50 or more.

[0288]

[54] The adhesive sheet according to

[53] above, wherein the material has a total light transmittance of 80% or more.

[0289]

[55] A laminate, wherein the laminate has the adhesive sheet according to any one of

[11] to

[48] ,

[50] to

[52] above and a member to which the adhesive sheet is attached, and

[0290] the member has a refractive index of 1.50 or more.

[0291]

[56] The laminate according to

[55] above, wherein the member has a total light transmittance of 80% or more.

[0292] Examples

[0293] Hereinafter, some examples of the present application will be described, but the present application is not intended to be limited to the contents shown in these examples. Note that, unless otherwise specified, "parts" in the following description are on a weight basis.

[0294] < Evaluation Method >

[0295] [Total Light Transmittance]

[0296] The total light transmittance of the adhesive sheet [%] is the total light transmittance in the thickness direction of the adhesive sheet peeled from the release liner, and is measured according to JIS K 7136:2000 using a commercially available transmittance meter. As the transmittance meter, a product name "HAZEMETER HM-150" manufactured by Murakami Color Research Laboratory or an equivalent thereof is used.

[0297] [Refractive index]

[0298] As for the refractive index of the adhesive sheet, in the case where the total light transmittance of the adhesive sheet is 50% or more, the measurement is performed under Condition (1). In the case where the above total light transmittance is less than 50%, the measurement is performed under Condition (2).

[0299] (Condition (1))

[0300] The measurement is performed at a wavelength of 589 nm and at 23°C using a multi-wavelength Abbe refractometer. As the multi-wavelength Abbe refractometer, a model "DR-M2" manufactured by ATAGO Co., Ltd. or an equivalent thereof is used.

[0301] (Condition (2))

[0302] The refractive index of the sodium D line (589 nm) is measured at 23°C using an ellipsometer. Specifically, the average surface refractive index from the surface of the adhesive sheet (adhesive surface) from which the release liner has been peeled off is measured. The measurement is performed on the basis that a black plate is attached to the side opposite to the measurement surface (non-measurement surface). As the ellipsometer, a product name "EC-400" manufactured by JA. Woolam Co., Ltd. or an equivalent thereof is used.

[0303] [180-degree peeling strength (adhesive strength)]

[0304] In a measurement environment of 23°C and 50% RH, a PET film having a thickness of 50 μm is attached to one adhesive surface of the double-coated adhesive sheet to back it, and the measurement sample is cut into a size of 10 mm in width and 100 mm in length, whereby the measurement sample is produced. For the produced measurement sample, in an environment of 23°C and 50% RH, a 2-kg roller is reciprocated once, and the adhesive surface of the measurement sample is pressure-bonded to the surface of a stainless steel plate (SUS304BA plate). After it is left in the same environment for 30 minutes, using a universal tensile compression tester, the peeling strength (adhesive strength) [N / 10 mm] is measured according to JIS Z 0237:2000 under the conditions of a tensile speed of 300 mm / minute and a peeling angle of 180 degrees. As the universal tensile compression tester, for example, a "Tensile Compression Tester, TG-1 kN" manufactured by Minebea Co., Ltd. or an equivalent thereof can be used. Note that, in the case of a single-coated adhesive sheet, the above backing with the PET film is not necessary.

[0305] [Particle P in the adhesive layer] HRI [Particle diameter measurement]

[0306] The adhesive sample was rapidly frozen under a liquid nitrogen atmosphere, and the sample was cut into a thickness of about 100 nm using an ultramicrotome (Model "UC7" manufactured by Leica) under a frozen atmosphere at -30°C, thereby obtaining an ultrathin section. For the obtained ultrathin section, TEM observation was performed using a transmission electron microscope (TEM; manufactured by Hitachi High-Technologies Corporation, acceleration voltage 100 kV). Image processing (binarization) was performed on one field of view (10 μm x 10 μm square) of a TEM image enlarged to about 40,000 times, particles were identified, and the area fraction of each particle was calculated for all of the identified particles. Then, the equivalent circle diameter was calculated from the area of each particle. The equivalent circle diameter refers to the diameter of a circle (a true circle) having the same area as that of one particle that is the measurement object. The above operation was performed on four different fields of view in the TEM image (N = 4), and the particles classified by the equivalent circle diameter were histogramed on a number basis, thereby obtaining the particle size distribution (number basis). The number that was the calculation basis of the particle size distribution was found by counting the number of particles present in the above one field of view. The average particle size [nm] and the standard deviation [nm] were found from the obtained particle size distribution. Note that, in identifying the particles, particles located at the end of the image were omitted from the analysis. As the image analysis software, for example, imageJ can be used.

[0307] Example 1

[0308] (Preparation of acrylic polymer)

[0309] In a reaction vessel having a stirrer, a thermometer, a nitrogen gas introduction tube, a reflux condenser, and a dropping funnel, 95 parts of BA and 5 parts of AA as monomer components and 233 parts of ethyl acetate as a polymerization solvent were put in, and stirring was performed for 2 hours while introducing nitrogen gas. Thereby, oxygen in the polymerization system was removed, and then 0.2 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator was added, and solution polymerization was performed at 60°C for 8 hours, thereby obtaining an acrylic polymer solution. The Mw of the acrylic polymer was about 70 x 10 4 .

[0310] (Preparation of adhesive composition)

[0311] In the above acrylic polymer solution, 100 parts of the particle P HRIA dispersion liquid of surface-treated zirconia particles A (Zr02-A), 20 parts of a terpene phenol resin as a tackifying resin, 0.8 parts of 1,2,3-benzotriazole (trade name "BT-120", manufactured by J-CHEM, Co., Ltd.) as a rust preventive, and 3 parts of an isocyanate-based crosslinking agent and 0.01 parts of an epoxy-based crosslinking agent as crosslinking agents were mixed by stirring, whereby an adhesive composition was prepared.

[0312] As Zr02-A, a dispersion liquid of surface-treated zirconia particles obtained by dispersing surface-treated zirconia particles (average particle diameter: 40 nm, surface treatment: sulfonic acid-based hydrophobic treatment, manufactured by CIK NanoTech Co., Ltd.) in dimethylacetamide (DMA) was used. As the terpene phenol resin (tackifying resin), a product with the trade name "YS Polystar T-115" (manufactured by Yasuhara Chemical Co., Ltd., softening point: about 115°C, hydroxyl value: 30 mgKOH / g to 60 mgKOH / g) was used. As the isocyanate-based crosslinking agent, a product with the trade name "CORONATE L" (manufactured by Nippon Polyurethane Industry Co., Ltd., 75% ethyl acetate solution of trimethylolpropane / toluene diisocyanate trimer adduct) was used. As the epoxy-based crosslinking agent, a product with the trade name "TETRAD-C" (manufactured by Mitsubishi Gas Chemical Co., Inc., 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane) was used.

[0313] (Production of adhesive sheet)

[0314] The above-described adhesive composition was applied to the release surface of a polyester release liner (trade name "DIAFOIL MRF", manufactured by Mitsubishi Polyester Film Co., Ltd.) having a thickness of 38 μm, and dried at 100°C for 2 minutes, thereby forming an adhesive layer having a thickness of 10 μm. A release surface of a polyester release liner (trade name "DIAFOIL MRF", manufactured by Mitsubishi Polyester Film Co., Ltd.) having a thickness of 25 μm was attached to the adhesive layer. In this way, a double-coated adhesive sheet having a thickness of 10 μm and no substrate, which was protected by the above-described two polyester release liners, was obtained.

[0315] Examples 2 to 12

[0316] The thickness of the adhesive sheet (thickness of the adhesive layer), the kind and the amount of use of the particles P HRI were set as shown in Table 1. Otherwise, the same as in Example 1 was performed, and the adhesive composition of each example was prepared, and a double-coated adhesive sheet was produced using the adhesive composition. In Examples 11 and 12, the particles P HRI were not used.

[0317] Note that Zr02-B in Table 1 is a surface-treated zirconium oxide particle dispersion liquid B obtained by dispersing surface-treated zirconium oxide particles (average particle diameter: 20 nm, surface treatment: methacrylic reactive group, manufactured by CIK NanoTech) in methyl ethyl ketone (MEK). Ti02-A is a surface-treated titanium dioxide particle dispersion liquid A obtained by dispersing surface-treated titanium dioxide particles (average particle diameter: 15 nm, surface treatment: methacrylic reactive group, manufactured by CIK NanoTech) in MEK. Ti02-B is a surface-treated titanium dioxide particle dispersion liquid B obtained by dispersing surface-treated titanium dioxide particles (average particle diameter: 15 nm, surface treatment: sulfonic acid-based hydrophobic treatment, manufactured by CIK NanoTech) in methyl propyl ketone (MPK). Ti02-C is a surface-treated titanium dioxide particle dispersion liquid C obtained by dispersing surface-treated titanium dioxide particles (average particle diameter: 10 nm, surface treatment: methacrylic reactive group, manufactured by CIK NanoTech) in propylene glycol monomethyl ether (PGME).

[0318] Example 13

[0319] In the preparation of the adhesive composition of Example 1, carbon black particles A (manufactured by Oji-Colorants Co., Ltd., trade name "ATDN101 BLACK", average particle diameter: 350 nm, described as "CB-A" in the table) were further added in such a manner as to achieve 1.0% by weight in the adhesive layer. Otherwise, the same as in Example 1 was performed, and the adhesive composition of the present example was prepared, and a substrate-free double-coated adhesive sheet having a thickness of 25 μm was produced using the adhesive composition.

[0320] Examples 14 to 19

[0321] The thickness of the adhesive sheet (thickness of the adhesive layer) and the kind and the amount of use of the carbon black particles were set as shown in Table 2. Otherwise, the same as in Example 13 was performed, and the adhesive composition of each example was prepared, and a substrate-free double-coated adhesive sheet was produced using the adhesive composition.

[0322] Note that CB-B in Table 2 is carbon black particles B (manufactured by Oji-Colorants Co., Ltd., product number "No. 3057") having an average particle diameter of 90 nm.

[0323] Example 20

[0324] Prepare two polyester release liner materials with a thickness of 38 μm (trade name "DIAFOIL MRF", manufactured by Mitsubishi Polyester Co., Ltd.) and a thickness of 25 μm. Apply an adhesive composition of the same composition as used in Example 14 to the release surfaces of these release liner materials, and allow them to dry to a thickness of 12.5 μm. Dry at 100°C for 2 minutes. This forms an adhesive layer on the release surfaces of both release liner materials.

[0325] A transparent PET film (trade name "Lumirror", manufactured by Toray Industries, Inc.) with a thickness of 5 μm was used as the supporting substrate. Adhesive layers formed on the two release liner sheets were bonded to the first and second surfaces of the supporting substrate, respectively, thus creating the double-sided adhesive sheet with substrate in this example (total thickness 30 μm) (transfer method). The release liner sheets remain directly on the adhesive layer to protect the surface of the adhesive layer (adhesive side).

[0326] <Example 21>

[0327] The thickness of each adhesive layer was changed to 19 μm, and the thickness of the supporting substrate (PET film) was changed to 12 μm. Otherwise, the process was the same as in Example 20, thereby producing the double-sided adhesive sheet with substrate (total thickness of 50 μm) of this example.

[0328] <Example 22>

[0329] Without using particle P HRI The thickness of the adhesive sheet (the thickness of the adhesive layer) was changed to 35 μm, and otherwise the same procedure was performed as in Example 15, thereby producing the substrate-free double-sided adhesive sheet of this example.

[0330] The summary, total transmittance, refractive index, and adhesive strength evaluation results of each example adhesive sheet are shown in Tables 1 and 2.

[0331]

[0332]

[0333] As shown in Table 1, compared with unused particle P HRI Compared to Examples 11 and 12, when using particles containing P HRI In Examples 1-10 of the adhesive sheets with adhesive layers, the refractive index of the adhesive sheets was increased. As shown in Table 2, for adhesives containing colorants (specifically carbon black particles), compared with adhesives without particles P HRI Compared to Example 22, when using particles P HRIIn Examples 13-21 of the adhesive, the refractive index of the adhesive sheet was increased. Furthermore, as can be seen from the comparison of Examples 2 and 6, increasing the particle P within the adhesive layer... HRI The refractive index of the adhesive sheet increases. Furthermore, a comparison of Examples 2, 4, and 8 shows that even with equal amounts of particle P... HRI In this case, depending on the particle P used HRI The degree of increase in refractive index of the adhesive sheet varies depending on the type of adhesive.

[0334] Regarding particle P HRI The adhesives in Examples 2 and 8, which showed significant differences in the degree of refractive index enhancement due to their different types, yielded particle P based on the aforementioned TEM observation benchmark. HRI The particle size distribution was determined, and particle P was calculated. HRI The average particle size [nm] and standard deviation [nm] are shown. The particle size distribution, average particle size [nm], and standard deviation [nm] are presented in... Figures 5-6 In the middle. It should be noted that, Figures 5-6 The particle size range in the figure, for example, "10nm~15nm" means greater than or equal to 10nm and less than 15nm, and the same applies to other particle size ranges in the figure.

[0335] Depend on Figures 5-6 The results show that in Example 2, where the refractive index of the adhesive sheet is highly increased, the particles P present in the adhesive layer... HRI The average particle size is less than 100 nm, and the standard deviation is less than 20 nm. In contrast, in Example 8, where the refractive index increase is relatively low, although particle P... HRI The average particle size is less than 100 nm, but the standard deviation is greater than 20 nm. Based on this result, it can be concluded that within the adhesive layer, the surface-treated zirconia particle dispersion A, with an average particle size less than 100 nm and a standard deviation of less than 20 nm, is well-compatible with the adhesive components, effectively improving the refractive index of the adhesive sheet. Furthermore, in Example 4, which confirmed the same refractive index improvement effect as Example 2, the surface-treated titanium dioxide particle dispersion B used in this example was similarly well-compatible with the adhesive components as the aforementioned surface-treated zirconia particle dispersion A, effectively improving the refractive index of the adhesive sheet. On the other hand, Example 8 uses surface-treated titanium dioxide particle dispersion C as particle P... HRI For example, using an equal amount of particle P HRI Compared to Example 7, which used a surface-treated zirconia particle dispersion A with the same adhesive layer thickness (35 μm), the adhesive strength was significantly reduced. This result also supports the relatively low compatibility between surface-treated titanium dioxide particle dispersion C and the adhesive components.

[0336] Additionally, for adhesives containing colorants (specifically carbon black particles), when using adhesives containing particles P HRI In Examples 13-21 of the adhesive, the same degree of refractive index enhancement as in Example 2 was obtained. Therefore, when using P particles... HRI In the method of coloring agents, it is believed that by selecting appropriate particles P HRI The types achieved good compatibility. In these examples, it is believed that the particles P within the adhesive layer... HRI The average particle size is less than 100 nm and the standard deviation is less than 20 nm.

[0337] The above results show that, based on the particles P present in the adhesive layer... HRI The composition consists of particles with an average particle size of less than 100 nm and a standard deviation of less than 20 nm, and the binder components and particle P HRI It has good compatibility and can effectively improve the refractive index of the adhesive sheet.

[0338] The specific examples of the present invention have been described in detail above, but they are merely illustrative and do not limit the scope of the claims. The technology described in the claims includes the contents obtained by various modifications and alterations to the specific examples described above.

[0339] Label Explanation

[0340] 1, 2, 3 Adhesive sheets

[0341] 10 Supporting substrate

[0342] 10A First Page

[0343] 10B Second Page

[0344] 21 Adhesive layer, first adhesive layer

[0345] 21A Adhesive surface, first adhesive surface

[0346] 21B Adhesive Surface

[0347] 22 Second adhesive layer

[0348] 22A Second Adhesive Surface

[0349] 31, 32 Peeling off the gasket

Claims

1. An adhesive sheet, wherein the adhesive sheet is an adhesive sheet having an adhesive layer, wherein, The adhesive layer is an adhesive layer formed from a water-based adhesive composition, a solvent-based adhesive composition, or a hot-melt adhesive composition, containing an acrylic polymer as a base polymer and high-refractive-index particles P. HRI and carbon black particles, The carbon black particles have an average particle size of 10 nm or more and 200 nm or less. The particles P present in the adhesive layer HRI The average particle size is less than 100 nm. The particles P present in the adhesive layer HRI The standard deviation is below 20 nm. Here, the average particle size and the standard deviation are respectively derived from the particle size distribution based on the number of TEM observations. The total light transmittance of the adhesive sheet is below 70%. The refractive index of the adhesive sheet is below 1.

70.

2. An adhesive sheet, wherein the adhesive sheet is an adhesive sheet having an adhesive layer, wherein, The adhesive layer is an adhesive layer formed from a water-based adhesive composition, a solvent-based adhesive composition, or a hot-melt adhesive composition, containing an acrylic polymer as a base polymer and P particles containing metal oxides. HRI and carbon black particles, The carbon black particles have an average particle size of 10 nm or more and 200 nm or less. The particles P present in the adhesive layer HRI The average particle size is less than 100 nm. The particles P present in the adhesive layer HRI The standard deviation is below 20 nm. Here, the average particle size and the standard deviation are respectively derived from the particle size distribution based on the number of TEM observations. The total light transmittance of the adhesive sheet is below 70%. The refractive index of the adhesive sheet is below 1.

70.

3. The adhesive sheet as described in claim 1 or 2, wherein, The particles P present in the adhesive layer HRI The average particle size is less than 80 nm.

4. The adhesive sheet as described in claim 1 or 2, wherein, The adhesive layer contains particles P in a proportion greater than 20% by weight. HRI .

5. The adhesive sheet as claimed in claim 1, wherein, The particle P HRI It includes at least one particle selected from metal particles, metal compound particles, organic particles, and organic / inorganic complex particles.

6. The adhesive sheet as claimed in claim 1, wherein, The particle P HRI It contains metal oxides.

7. The adhesive sheet as claimed in claim 1 or 2, wherein, The adhesive layer is a solvent-based adhesive layer formed from a solvent-based adhesive composition.

8. The adhesive sheet as claimed in claim 1 or 2, wherein, For the particle P HRI A hydrophobic surface treatment was applied.

9. The adhesive sheet as claimed in claim 1 or 2, wherein, The thickness of the adhesive sheet is in the range of 10μm to 50μm.

Images