TW202146229A - Light-emitting device - Google Patents

Abstract

The provided light-emitting device includes a self-luminescent element, a low-refractive-index layer positioned further toward the viewing side than the self-luminescent element, and a high-refractive-index adhesive layer layered in direct contact with a low-refractive-index adhesive layer. The high-refractive-index adhesive layer has a refractive index n1 of more than 1.570, the total light transmittance thereof is 86% or greater, and the haze value thereof is 3.0% or less.

Description

light-emitting device

The present invention relates to a light-emitting device, and in particular, to a light-emitting device having an adhesive layer disposed on a viewing side of a self-light-emitting element. This application claims to rely on Japanese Patent Application No. 2020-052408 filed on March 24, 2020, Japanese Patent Application No. 2020-166428 filed on September 30, 2020, and filed in 2021 Priority is granted to Japanese Patent Application No. 2021-049061 filed on March 23, and the entire contents of these applications are incorporated herein by reference.

Generally speaking, adhesives (also known as pressure-sensitive adhesives, the same below) exhibit a soft solid (viscoelastic) state at a temperature near room temperature, and have the ability to be easily adhered to the adherend by pressure. nature. Taking advantage of this property, adhesives are widely used for the purpose of bonding, fixing, and protection in various industrial fields ranging from home appliances to automobiles, various machinery, electrical equipment, and electronic equipment. An example of the application of the adhesive includes the application of bonding polarizing films, retardation films, cover window members, various other light-transmitting members, and other members in display devices such as liquid crystal display devices and organic EL display devices. Patent documents 1 and 2 are mentioned as technical documents about the adhesive for optical members. prior art literature Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-169382 Patent Document 2: Japanese Patent Application Laid-Open No. 2017-128732

The problem to be solved by the invention Patent Documents 1 and 2 propose an adhesive composition containing a (meth)acrylate polymer as a main component, and an adhesive obtained by crosslinking the adhesive composition, and the (meth)acrylate The polymer contains a monomer having a plurality of aromatic rings as a monomer unit, but no specific adhesive with a refractive index greater than 1.570 is disclosed. On the other hand, there is also known a technique for increasing the refractive index by mixing particles made of inorganic materials with high refractive index (for example, inorganic particles such as zirconia particles or titanium oxide particles) into resins to increase the refractive index. Adhesives are difficult to apply in the field of adhesives because the refractive index and adhesive properties (such as peel strength, flexibility, etc.) are in a trade-off relationship. For example, in order to increase the refractive index of the adhesive layer disposed on the visible side of the self-light-emitting element in a light-emitting device, it is also necessary to take into account the effects on optical properties (such as total light transmittance, haze, etc.) when mixing inorganic particles. etc.) effects.

The present invention has been made in view of the above-mentioned situation, and its object is to provide a light-emitting device in which a high-refractive-index and optical-quality adhesive layer is disposed on the viewing side of the self-light-emitting element.

Means for Solving the Problem The light-emitting device provided by this specification includes: a self-luminous element; a low-refractive-index layer disposed on the viewing side of the self-luminous element; and a high-refractive-index adhesive layer in direct contact The said low-refractive-index layer is laminated|stacked. _{The refractive index n 1 of} the high-refractive-index adhesive layer is greater than 1.570, the total light transmittance is more than 86%, and the haze value is less than 3.0%.

In several aspects, the refractive index of the high refractive index n ₁ of the adhesive agent layer ₂ of the above-described ratio of the low refractive index layer of n (n ₁ / n ₂₎ should be about 1.05 or more.

In several aspects, the arithmetic mean roughness Ra of the surface of the high-refractive-index adhesive layer is preferably 100 nm or less.

In several aspects, a thickness of the high refractive index layer of _an adhesive agent with a thickness of the low refractive index layer is the ratio of T ₂ T (T ₁ / T ₂₎ should be approximately in the range of 0.5 to 5.

_{In several aspects, the thickness T 1 of} the high-refractive-index adhesive layer is preferably 5 µm or more.

In some aspects, the laminated sheet (adhesive sheet) composed of the high-refractive-index adhesive layer and the low-refractive index layer preferably has a total light transmittance of 86% or more and a haze value of 3.0% or less.

In addition, an appropriate combination of the various elements described in this specification can also be included in the scope of the invention for which patent protection is sought by this patent application.

Preferred embodiments of the present invention will be described below. Matters not specifically mentioned in this specification that are required for the implementation of the present invention can be understood by those skilled in the art based on the teachings on the implementation of the invention described in this specification and the technical common sense at the time of application. The present invention can be implemented according to the contents disclosed in this specification and common technical knowledge in the field. In addition, in the following drawings, the same code|symbol is attached|subjected to the member and the part which perform the same function and it demonstrates, and the repeated description may abbreviate|omit or simplify. In addition, the embodiment described in the drawings is schematic for clearly explaining the present invention, and does not completely accurately represent the size or scale of the product actually provided.

In this specification, a self-luminous element means a light-emitting element whose light-emitting luminance can be controlled by the current value flowing therethrough. The self-luminous element may be configured as a single body or as an aggregate. Specific examples of self-luminous elements include light emitting diodes (LEDs) and organic ELs, but are not limited thereto. The light-emitting device disclosed herein includes the self-luminous element as a constituent element. In the above example of the light-emitting device, a light source module device (such as a planar light-emitting body module) used for illumination or a display device formed with pixels is also included, but not limited thereto.

The technical matters disclosed by this specification include: a light-emitting device, a high-refractive-index adhesive layer and an adhesive composition for forming the same, a low-refractive-index layer and a composition for forming the same, including a high-refractive index adhesive layer and A laminated sheet (adhesive sheet) of a low refractive index layer, a laminated sheet with a release liner in which the adhesive surface of the laminated sheet is protected by a release liner, etc.

<Configuration example of light-emitting device> A configuration example of the light-emitting device provided by this specification is shown in FIG. 1 . The light-emitting device 100 shown in FIG. 1 includes: a self-light-emitting element 70; a low-refractive-index layer 12, which is disposed on the viewing side of the self-light-emitting element 70; and a high-refractive-index adhesive layer 11, which is in direct contact with the low-refractive index layer 12 and stacked layers. The light-emitting device 100 may further include a cover window member 80 disposed on the viewing side of the high-refractive-index adhesive layer 11 . In the light-emitting device 100 shown in FIG. 1 , a laminate 10 composed of a high-refractive-index adhesive layer 11 and a low-refractive index layer 12 is disposed between the self-luminous element 70 and the cover window member 80 . Between the self-luminous element 70 and the low-refractive-index layer 12, between the high-refractive-index adhesive layer 12 and the cover window member 80, and on the more visible side of the cover window member 80, one or more layers may be interposed independently, respectively. The layers not shown in the figure may not be interposed therebetween. In addition, contrary to FIG. 1 , the high-refractive-index adhesive layer 11 may be arranged on the self-luminous element side, and the low-refractive index layer 12 may be arranged on the cover window member side.

In the technology disclosed herein, the low refractive index layer may be adhesive or non-adhesive. In several aspects, the low refractive index layer is preferably an adhesive layer, ie, a low refractive index adhesive layer. Thereby, the laminated sheet (adhesive sheet) of the low-refractive-index adhesive layer and the high-refractive-index adhesive layer becomes double-sided adhesiveness, thereby improving the assemblability in the manufacture of the light-emitting device. Before the laminated sheet is incorporated into the light-emitting device, for example, as shown in FIG. 2 , it can be in the form of a laminated sheet with a release liner: it is composed of a high-refractive-index adhesive layer 11 and a low-refractive-index adhesive layer 12 . The laminated sheet 10 (double-sided adhesive sheet 2 without base material), and the surface (first surface) 10A on the side of the high-refractive-index adhesive layer 11 of the laminated sheet 10 becomes the first adhesive surface, and the low-refractive-index adhesive layer The surface (second surface) 10B on the 12th side becomes the second adhesive surface, and these adhesive surfaces are protected by release liners 31 and 32, respectively.

<High Refractive Index Adhesive Layer> The light-emitting device disclosed herein includes a high-refractive index adhesive layer, which is laminated in direct contact with a low-refractive index layer included in the light-emitting device. The high-refractive-index adhesive layer is a layer having a relatively higher refractive index than the above-mentioned low-refractive index layer. _{Preferably, the refractive index n 1 of} the high-refractive-index adhesive layer is greater than 1.570, the total light transmittance is more than 86%, and the haze value is preferably less than 3.0%.

(Refractive Index) The light-emitting device disclosed herein has a high-refractive-index adhesive layer _{with a refractive index n 1 greater than 1.570.} The high-refractive-index adhesive layer can be realized by forming at least one surface (adhesive surface) of the high-refractive-index adhesive layer with an adhesive (viscoelastic material) with a refractive index greater than 1.570.

In addition, in this specification, the refractive index of an adhesive means the refractive index of the surface (adhesion surface) of this adhesive. The refractive index of the adhesive can be measured under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C using a commercially available refractive index measuring device (Abbé refractometer). For example, the Abbe refractometer can use the model "DR-M4" manufactured by ATAGO or its equivalent. As the measurement sample, an adhesive layer composed of the adhesive to be evaluated can be used. Specifically, the refractive index of the adhesive can be measured by the method described in the following Examples. The refractive index of the adhesive can be adjusted by, for example, the composition of the adhesive (for example, the composition of the monomer components constituting the base polymer, additives that can be used according to needs, etc.).

The technical matters provided by this specification include: an adhesive layer with a refractive index greater than 1.570 (high-refractive-index adhesive layer), an adhesive composition capable of forming the adhesive layer, and a laminate comprising the above-mentioned high-refractive-index adhesive layer piece. The above-mentioned laminated sheet may be, for example, a laminated adhesive layer composed of the above-mentioned high-refractive-index adhesive layer and a low-refractive-index layer (typically a low-refractive-index adhesive layer), or may be sequentially or sequentially on one surface of the supporting substrate. A high-refractive-index adhesive layer and a low-refractive index layer are laminated in reverse order.

In several aspects, the refractive index of the high refractive index adhesive layer is preferably 1.580 or higher, more preferably 1.585 or higher, and more preferably 1.590 or higher (eg, 1.595 or higher). By having a high refractive index adhesive layer with said refractive index, the relative refractive index of the high refractive index adhesive layer and the low refractive index layer (typically a low refractive index adhesive layer) directly adjacent to it can be utilized relationship to effectively control the behavior of light transmitted through the high-refractive-index adhesive layer. In several aspects of the techniques disclosed herein, the refractive index of the high refractive index adhesive layer may be, for example, 1.600 or more or 1.600, 1.605 or more or more than 1.605, or 1.610 or more or more than 1.610. The ideal upper limit of the refractive index of the high-refractive-index adhesive layer can vary according to the refractive index of the adjacent layer, etc., so it is not limited to a specific range. In several aspects, the refractive index of the high-refractive-index adhesive layer may be, for example, 1.700 or less, 1.670 or less, or 1.650 or less, in consideration of a balance with adhesive properties or transparency.

(total light transmittance) In the technology disclosed herein, the total light transmittance of the high-refractive-index adhesive layer is suitably 86% or more, preferably 88% or more, more preferably 90% or more (eg, more than 90.0%), and may be 90.5% or more , which can be more than 93% or more than 95%. The upper limit of the total light transmittance is theoretically a value obtained by excluding the light loss (Fresnel loss) caused by reflection at the air interface by 100%. About 96% or less, and also about 95% or less. In several aspects, the total light transmittance of the high refractive index adhesive layer may be about 94% or less, about 93% or less, or about 92% or less, considering the refractive index or adhesion properties. The total light transmittance is measured using a commercially available transmittance meter in accordance with JIS K 7136:2000. For the transmittance meter, the trade name "HAZEMETER HM-150" manufactured by Murakami Color Technology Laboratory or its equivalent can be used. More specifically, for example, the total light transmittance of the high-refractive-index adhesive layer can be measured according to the following examples. The total light transmittance of the high-refractive-index adhesive layer can be adjusted by, for example, selecting the composition or thickness of the high-refractive-index adhesive layer.

(Haze value) The haze value of the high-refractive-index adhesive layer is suitably 3.0% or less, preferably 2.0% or less, more preferably 1.0% or less, and more preferably 0.9% or less. The low haze value of the high-refractive-index adhesive layer is beneficial for applications requiring high light transmittance (such as optical applications), or applications requiring good visibility of the properties of the adherend through the high-refractive-index adhesive layer . In several aspects, the haze value of the high refractive index adhesive layer may be 0.8% or less, 0.5% or less, or 0.3% or less. The lower limit of the haze value of the high-refractive-index adhesive layer is not particularly limited, and from the viewpoint of improving transparency, the smaller the haze value, the better. On the other hand, in several aspects, considering the refractive index or the adhesive properties, the haze value of the high-refractive index adhesive layer may be, for example, 0.05% or more, 0.1% or more, 0.2% or more, or 0.3% or more, or 0.4% or more. These haze values of the high-refractive-index adhesive layer can also be suitably applied to the haze of a laminated sheet composed of the high-refractive-index adhesive layer and a low-refractive-index layer (typically, a low-refractive-index adhesive layer) to be described later. degree value.

Here, the "haze value" means the ratio of diffusely transmitted light to total transmitted light when a measurement object is irradiated with visible light. Also known as Haze Value. The haze value can be represented by the following formula. Th(%)=Td/Tt×100 In the above formula, Th is the haze value (%), Td is the scattered light transmittance, and Tt is the total light transmittance. The measurement of the haze value can be performed according to the method described in the following examples. The haze value of the adhesive layer can be adjusted by, for example, selecting the composition or thickness of the adhesive layer.

(Storage elastic modulus G') In the technology disclosed herein, the storage elastic modulus G' (hereinafter also referred to as "storage elastic modulus G' _V1 (25)") of the high-refractive index adhesive layer at 25°C can be Appropriately set according to the purpose of use or the state of use, etc., and are not limited to a specific range. The storage elastic modulus G' _V1 (25) may be, for example, about 700 kPa or less. In some aspects, from the viewpoint of the easiness of attachment to the adherend, etc., it _{is advantageous that the storage elastic modulus G' V1} (25) is about 600 kPa or less, preferably 500 kPa or less, more preferably 400 kPa or less (For example, 350kPa or less). In several aspects, from the viewpoint of improving the flexibility of the high-refractive-index adhesive layer in the room temperature region (eg, 25°C), it is easy to adhere to the adherend, the storage elastic modulus G' _V1 (25 ) is advantageously about 330 kPa or less, and preferably 300 kPa or less. In several aspects where adherence or softness in the room temperature region is more important, the storage elastic modulus G' _V1 (25) may be, for example, less than 270 kPa or less than 250 kPa, and less than 200 kPa is advantageous, and preferably less than 180kPa, preferably less than 160kPa (for example, less than 140kPa). In several aspects, the storage elastic modulus G' _V1 ( 25 ) can be less than 100 kPa or less than 90 kPa. The lower limit of the storage elastic modulus G' _V1 (25) is not particularly limited, but may be, for example, 30 kPa or more, 50 kPa or more, or 70 kPa or more from the viewpoint of processability and handling properties. In several aspects, considering the high refractive index, the storage elastic modulus G' _V1 (25) may be 100 kPa or more, 150 kPa or more, 200 kPa or more, 250 kPa or more, or 300 kPa or more.

In the technology disclosed herein, the storage elastic modulus G' (hereinafter also referred to as "storage elastic modulus G' _V1 (50)") of the high-refractive index adhesive layer at 50°C is not particularly limited, for example, it may be less than 100 kPa. In several aspects, the storage elastic modulus G' _V1 (50) is suitably less than 60 kPa, preferably less than 40 kPa, preferably less than 38 kPa (eg, less than 36 kPa). For example, the high refractive index adhesive layer with limited storage elastic modulus G' _V1 (50) can easily improve the adhesion to the adherend by performing moderate heating as required, thereby improving the adhesion to the adherend. Adhesion of the adhesive. The lower limit of the storage elastic modulus G' _V1 (50) is not particularly limited. _{In some aspects, the storage elastic modulus G' V1} (50) may be, for example, 10 kPa or more, 15 kPa or more, 20 kPa or more, or 23 kPa or more from the viewpoint of heat resistance properties and the like.

In several aspects of the technology disclosed herein, the high-refractive-index adhesive layer preferably satisfies at least one of the following conditions: (a) The storage elastic modulus G' _V1 (25) is below 350 kPa (preferably less than 200 kPa _, such as 180 kPa) and (b) the storage elastic modulus G' _V1 (50) is less than 60 kPa (preferably less than 50 kPa, more preferably less than 40 kPa, eg less than 38 kPa). A high-refractive-index adhesive layer that satisfies at least the above-mentioned condition (a) is ideal from the viewpoint of adhesion or flexibility to the adherend in a room temperature region (eg, 25° C.). The high-refractive-index adhesive layer that satisfies at least the above-mentioned condition (b) is preferable because the adhesiveness (adhesion) to the adherend can be easily improved by heating to a temperature slightly higher than room temperature. An adhesive sheet having a high-refractive-index adhesive layer that does not satisfy the above condition (a) and satisfies the above (b) can be used as a heat-activated adhesive sheet. good adhesion), and the peeling strength from the adherend can be effectively improved by heating to a temperature slightly higher than room temperature. The above-mentioned thermal activation can also be performed by heating the adhesive sheet to a temperature slightly higher than room temperature when it is attached to an adherend. The above-mentioned temperature slightly higher than room temperature is, for example, about 60°C or less, and preferably about 55°C or less (for example, about 50°C or less).

In several aspects of the technology disclosed herein, the ratio of storage elastic modulus G' _V1 (50) [kPa] to storage elastic modulus G' _V1 (25) [kPa], ie, storage elastic modulus ratio G' _V1 (50)/G' _V1 (25) may be, for example, 70% or less, 40% or less, 30% or less, or 20% or less. An adhesive sheet having a high refractive index adhesive layer with a small G' _V1 (50)/G' _V1 (25) is suitable for use as the above-mentioned heat-activated adhesive sheet. The lower limit of G' _V1 (50)/G' _V1 (25) is not particularly limited. G' _V1 (50)/G' _V1 (25) is, for example, 5% or more, but from the viewpoint of heat resistance, it is preferably 10% or more, may be 12% or more, or may be 15% or more.

The storage elastic moduli G' _V1 (25) and G' _V1 (50) can be obtained by dynamic viscoelasticity measurement, and G' _V1 (50)/G' _V1 (25) can be calculated from the results. The dynamic viscoelasticity measurement can be performed by a conventional method using a commercially available dynamic viscoelasticity measuring apparatus, for example, ARES or its equivalent manufactured by TA Instruments can be used under the following measurement conditions. As the measurement sample, the adhesive layer of the evaluation object was adjusted to a thickness of about 1.5 mm by laminating or the like according to requirements. [Measurement conditions] Deformation mode: Torsion measurement frequency: 1 Hz Heating rate: 5°C/min Shape: parallel plate 7.9mmφ

Storage elastic modulus G' _V1 (25), G' _V1 (50) and storage elastic modulus ratio (G' _V1 (50)/G' _V1 (25)) can be determined by selecting the base polymer constituting the adhesive The composition of the monomer components (for example, the selection of the type and content of the monomer (m1) described later), whether to use a crosslinking agent, the selection of types and amounts, whether to use the later-mentioned refractive index enhancer or plasticizing material, and selection of types and use amount, etc. to adjust. For example, as the monomer (m1), in addition to the first monomer which is the main component of the monomer (m1), a smaller amount of the second monomer having a different chemical structure from the first monomer may be used and By using the above-mentioned first monomer in combination, in addition to the reduction of G' _V1 (50) _{when the first monomer is used alone as the monomer (m1), G' V1} (50)/G' _V1 (25 )reduce.

(Surface smoothness of adhesive surface) In several aspects, the surface (adhesion face) of the high refractive index adhesive layer desirably has high surface smoothness.

For example, the arithmetic mean thickness Ra of the above-mentioned adhesive surfaces is preferably limited to a predetermined value or less. From the viewpoint of optical homogeneity, it is preferable to have an adhesive surface designed to have a low arithmetic mean roughness Ra. By limiting the arithmetic mean roughness Ra, for example, in the use state where light is captured through the above-mentioned adhesive surface (the adhesive sheet arranged on the viewpoint side of the light-emitting device in a light-emitting device, etc.), it is possible to exert a restraint due to sticking. The effect of uneven brightness occurs due to the surface state of the agent layer. The fact that the arithmetic mean roughness Ra of the adhesive surface is low also helps to suppress optical strain, and the suppression of optical strain also helps to improve optical homogeneity. The laminated sheet (adhesive sheet) disclosed here is in the form of a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface (for example, a laminated sheet composed of a high-refractive-index adhesive layer and a low-refractive-index adhesive layer shape), at least the arithmetic mean roughness Ra of the first adhesive surface should be limited to a predetermined value or less, and preferably the arithmetic average roughness Ra of the two adhesion surfaces are both limited to a predetermined value or less. Since each adhesive surface of the double-sided adhesive sheet has high surface smoothness, it is possible to suitably realize the bonding with excellent optical homogeneity.

In several aspects, the arithmetic mean roughness Ra of the adhesive surface is preferably about 70 nm or less, preferably about 65 nm or less, more preferably about 55 nm or less, may be less than 50 nm, may be less than 45 nm, and may be less than 40 nm. From the viewpoint of production efficiency and the like, in several aspects, the arithmetic mean roughness Ra of the adhesive surface may be, for example, about 10 nm or more, about 20 nm or more, or about 30 nm or more (eg, about 40 nm or more). In the aspect in which the laminated sheet has the first adhesive surface and the second adhesive surface, the arithmetic mean thickness Ra of the first adhesive surface and the arithmetic mean thickness Ra of the second adhesive surface may be the same or different.

Also, for example, the maximum height Rz of the above-mentioned adhesive surface is preferably limited to a predetermined value or less. From the viewpoint of optical homogeneity, it is preferable to have a structure with an adhesive surface designed to have a lower maximum height Rz. By limiting the maximum height Rz, the effect of suppressing uneven brightness due to the surface state of the adhesive layer can be exhibited, for example, in the use aspect in which light is captured through the adhesive surface as described above. The fact that the maximum height Rz of the adhesive surface is low is also beneficial for suppressing optical strain. When the laminated sheet disclosed here is in the form of a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface, it is preferable that at least the maximum height Rz of the first adhesive surface is limited to a predetermined value or less, preferably the height of the two adhesive surfaces The maximum heights Rz are all limited below a predetermined value. Since each adhesive surface of the double-sided adhesive sheet has high surface smoothness, it is possible to suitably realize the bonding with excellent optical homogeneity.

In several aspects, the maximum height Rz of the adhesive surface is preferably about 600 nm or less, preferably about 500 nm or less, more preferably about 450 nm or less, especially about 400 nm or less, may be less than 350 nm, may be less than 300 nm, or less than 250nm. From the viewpoint of production efficiency and the like, in several aspects, the maximum height Rz of the adhesive surface may be, for example, about 10 nm or more, about 50 nm or more, about 100 nm or more, or about 200 nm or more. In an aspect having a first adhesive surface and a second adhesive surface, the maximum height Rz of the first adhesive surface and the maximum height Rz of the second adhesive surface may be the same or different.

The arithmetic mean roughness Ra and the maximum height Rz of the adhesive surface were measured using a non-contact surface roughness measuring device. As the non-contact surface roughness measuring device, an optical interference method surface roughness measuring device can be used, for example, a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO Corporation) or its equivalent can be used. Specifically, the arithmetic mean roughness Ra and the maximum height Rz can be measured by, for example, the following measurement method or by setting the measurement operation or measurement conditions so as to obtain the same or corresponding results as in the case of using the measurement method.

That is, using a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO Corporation), the surface shape of the measurement sample was measured under the following conditions in an environment of 23°C and 50% RH. From the measured data, the arithmetic surface roughness Ra was calculated in accordance with JIS B 0601-2001. The maximum height Rz is based on the data obtained by the above measurement (roughness curve), and the height Rp from the average line of the thickness curve to the highest top on the upper side and the depth Rv from the average line to the deepest valley on the lower side are obtained. and. Five determinations were performed (ie, N=5), and the average of these was used. The measurement sample can be prepared by cutting, for example, an adhesive layer to be measured or an adhesive sheet including the adhesive layer into a size of about 150 mm in length and 50 mm in width. When the adhesive surface has been protected by the release liner, peel off the release liner smoothly (for example, under the conditions of a stretching speed of 300 mm/min and a peeling angle of 180°) to expose the adhesive surface. After exposing the adhesive surface, it is advisable to stand for about 30 minutes before measuring. [Measurement conditions] Measurement area: 5.62mm×4.22mm (objective lens: 2.5 times, inner lens: 0.5 times) Parsing mode: Remove: Cylinder Data Fill: ON (Max: 25) Remove Spikes: ON (xRMS: 1) Filter: OFF

The arithmetic mean roughness Ra and the maximum height Rz of the adhesive surface can be determined by the composition or properties (viscosity, leveling, etc.) of the adhesive composition used to form the adhesive layer, the surface of the release liner protecting the adhesive surface (peeling surface) properties, etc. to adjust.

(water absorption rate) In several aspects, the water absorption of the high refractive index adhesive layer is desirably limited below a predetermined value. By limiting the water absorption rate of the high-refractive index adhesive layer, it is possible to suppress the fluctuation of the moisture content in the high-refractive index adhesive layer (such as the absorption and release of moisture such as moisture in the environment) causing the high-refractive index adhesive layer. Tendency to change in size. Thereby, the high-refractive-index adhesive layer can be suppressed from being caused by the inconsistency of the dimensional change between the high-refractive-index adhesive layer and the adjacent layers (it can be a low-refractive-index layer, a support substrate, a release liner, an adherend, etc.) Or warpage of the optical laminate including the high-refractive-index adhesive layer. It is also preferable from the viewpoint that the flatness, transparency, refractive index, etc. of the high-refractive-index pressure-sensitive adhesive layer can be kept constant because the fluctuation of the moisture content in the high-refractive-index pressure-sensitive adhesive layer can be suppressed. In addition, the high-refractive-index adhesive layer with a low water absorption rate does not easily absorb water, and is therefore suitable as a constituent element of a member or a product including an element that does not like water, such as an organic EL element.

In several aspects, the water absorption of the high refractive index adhesive layer is suitably about 1.0% or less, preferably 0.7% or less, more preferably 0.5% or less (eg less than 0.5%), and may be 0.4% or less, It may be 0.3% or less, or 0.2% or less. The lower limit of the water absorption rate of the high-refractive-index adhesive layer is not particularly limited, and from the practical viewpoints of taking into account the adhesive properties and the like, it may be, for example, 0.01% or more, 0.05% or more, 0.1% or more, or 0.15%. % or more, or 0.25% or more. The water absorption rate of the low-refractive index layer may be the same as that of the high-refractive index adhesive layer, or it may be different. From the viewpoint of obtaining a higher effect, the water absorption rates of the high-refractive index adhesive layer and the low-refractive index layer are preferably limited to a predetermined value or less.

In addition, the water absorption rate (also called moisture content) of the high-refractive-index adhesive layer was measured by the following method. The water absorption rate of the low refractive index layer was also measured by the same method. [Measurement of Moisture Content] The adhesive layer of the evaluation object was cut into a size of 4cm×5cm (area: 20cm ² ) together with two release liners arranged on one side and the other side, and the peeling on one side was removed. After liner, fit to pre-weighed aluminum foil. Next, the release liner on the other side of the adhesive layer was removed, put into a constant temperature and humidity tank with a temperature of 60° C. and a relative humidity of 90%, and taken out after 72 hours. After weighing the test piece laminated with the adhesive layer and the aluminum foil, a moisture meter (Mitsubishi Chemical Analytech CA-200 type) equipped with a heating vaporization device (Mitsubishi Chemical Analytech VA-200 type) was used. The coulometric titration method measures the moisture content under the following conditions. Anolyte: AQUAMICRON AKX (manufactured by Mitsubishi Chemical) Catholyte: AQUAMICRON CXU (manufactured by Mitsubishi Chemical) Heating vaporization temperature: 150°C

(gel fraction) The gel fraction of the high-refractive-index adhesive layer can be appropriately set according to the purpose of use or the state of use, and is not limited to a specific range. The said gel fraction is suitably about 99% or less, for example, about 97% or less. From the viewpoint of easiness to properly balance high refractive index and adhesive properties, in several ideal aspects, the gel fraction is about 95% or less, preferably about 92% or less (eg, about 90% or less). The reason that the gel fraction is not too high can be properly followed by the concavities and convexities existing on the surface of the adherend (for example, the concavo-convex structure provided in the light-emitting device to improve the light extraction efficiency, etc.), and it is also good from the viewpoint of good adhesion. In several aspects, the gel fraction may be about 88% or less, about 75% or less, or about 65% or less. In addition, from the viewpoint of imparting appropriate cohesiveness to the adhesive to appropriately exhibit adhesive properties, the gel fraction is, for example, about 10% or more, preferably about 20% or more, and may be about 30% or more. . From the viewpoint of the deformation resistance of the adhesive layer (prevention of overflow due to pressure or air bubbles due to entrapment of foreign objects, etc.), the above-mentioned gel fraction is preferably about 30% or more, more preferably about 40% or more, It can be about 45% or more, it can be about 50% or more, it can be about 65% or more, and it can be about 75% or more. Gel of a laminated sheet comprising a high-refractive-index adhesive layer and a low-refractive-index layer (typically, a laminated sheet in the form of a substrate-less double-sided adhesive sheet composed of a high-refractive-index adhesive layer and a low-refractive index layer) It is also preferable to set the fraction in the range exemplified above. The gel fraction can be adjusted by the molecular weight or molecular structure, concentration, cross-linking degree, etc. of the base polymer. The gel fraction was measured by the following method.

[Determination of Gel Fraction] A predetermined amount of adhesive sample (weight Wg _{1 ) was wrapped into a small bag with a porous polytetrafluoroethylene membrane (weight Wg 2} ) with an average pore diameter of 0.2 µm, and a kite string (weight Wg ₃ ) Tie the opening. The above-mentioned porous polytetrafluoroethylene (PTFE) film used the trade name "Nitoflon (registered trademark) NTF1122" available from Nitto Denko Corporation (average pore diameter 0.2 µm, porosity 75%, thickness 85 µm) or its equivalent. The package was immersed in a sufficient amount of ethyl acetate and kept at room temperature (typically 23° C.) for 7 days, and only the sol in the adhesive was eluted out of the film, and then the package was taken out and adhered by wiping. The bale was dried at 130°C for 2 hours with ethyl acetate on the outer surface, and the weight (Wg ₄ ) of the bale was determined. The gel fraction of the adhesive layer can be obtained by substituting each value into the following formula. Gel fraction (%)=[(Wg ₄ -Wg ₂ -Wg ₃ )/Wg ₁ ]×100

The gel fraction of the high-refractive index adhesive layer and the gel fraction of the low-refractive index layer may be the same or different. In several aspects, the gel fraction of the low refractive index layer can be made higher than the gel fraction of the adhesive layer of lower refractive index. According to this configuration, the overall flexibility can be easily improved by the contribution of the low-refractive-index layer with a relatively low gel fraction. Thereby, a high refractive index and flexibility can be achieved in a balanced manner.

In several aspects of the technology disclosed herein, the peak temperature of the tan δ of the adhesive constituting the high refractive index adhesive layer is preferably about -50°C or higher, and preferably about 50°C or lower. Here, the tanδ (loss tangent) of the adhesive means the ratio of the loss elastic modulus G" to the storage elastic modulus G' of the adhesive. That is, tanδ=G"/G'. The tanδ of the adhesive can be used to sandwich a disc-shaped adhesive sample with a thickness of about 2mm and a diameter of 7.9mm with parallel plates, while applying a shear strain with a frequency of 1Hz using a viscoelasticity test device, while measuring the temperature range -60 ℃ Under the conditions of ~60°C and heating rate of 5°C/min, the temperature dispersion test of the adhesive was carried out in shear mode, and the storage elastic modulus G'(Pa) and loss elastic modulus G"(Pa) It is obtained by the following formula: tanδ=G"/G'. The peak temperature of tanδ of the adhesive can be obtained from the transition of tanδ in the above-mentioned temperature range (it may be referred to as Tpeak hereinafter). As the viscoelasticity test device, ARES or its equivalent manufactured by TA Instruments can be used.

In several aspects, it is advantageous for the Tpeak of the high refractive index adhesive layer to be 45°C or lower, or 35°C or lower, and preferably 30°C or lower (eg, 25°C or lower), 20°C or lower, or 15°C or lower. ℃ or lower. With an adhesive with a lower Tpeak, there is a tendency to easily obtain good initial adhesion or adhesion in the room temperature region. On the other hand, the fact that the Tpeak of the adhesive is not too low is ideal from the viewpoint of imparting moderate cohesiveness to the adhesive, and it tends to be suitable for both high refractive index. From this viewpoint, in several aspects, the Tpeak of the adhesive may be, for example, -40°C or higher, -30°C or higher, -20°C or higher, -5°C or higher, or 5°C or higher. ℃ or higher, may be 15°C or higher, more preferably 25°C or higher. When the adhesive with higher Tpeak is attached to the adherend, it can be used in a state where one or both of the adhesive and the adherend are heated to a temperature slightly higher than room temperature as required. . The Tpeak of the adhesive can be adjusted by selecting the composition of the adhesive (for example, the composition of the monomer components constituting the base polymer, whether or not to use a refractive index enhancer or plasticizing material, and the selection of types and amounts used). The Tpeak of the above-mentioned adhesive is preferably applied to at least the high-refractive index adhesive layer, and is preferably applied to both the high-refractive index adhesive layer and the low-refractive index layer. The Tpeak of the high-refractive index adhesive layer and the Tpeak of the low-refractive index layer may be the same or different.

(base polymer) In the technique disclosed herein, the type of the adhesive constituting the high-refractive-index adhesive layer is not particularly limited. The above-mentioned adhesives may include acrylic polymers, rubber-based polymers (natural rubber, synthetic rubber, mixtures of these, etc.), polyester-based polymers, urethane-based polymers that can be used in the field of adhesives , polyether-based polymers, polysiloxane-based polymers, polyamide-based polymers, fluorine-based polymers, etc., one or more of various rubber-like polymers as adhesive polymers (meaning that the adhesive The structural polymer shaped by the agent, hereinafter also referred to as the "base polymer"). From the viewpoints of adhesive performance, cost, and the like, an adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be suitably used. Among them, it is suitable to use an acrylic polymer as the adhesive (acrylic adhesive) of the base polymer. The techniques disclosed herein are suitably implemented in the form of using an acrylic adhesive.

Hereinafter, the high-refractive-index adhesive layer composed of the acrylic adhesive is mainly described, but the high-refractive-index adhesive layer in the technique disclosed herein is not intended to be limited to the acrylic adhesive layer.

In addition, in this specification, the "base polymer" of the adhesive means the main component of the rubber-like polymer contained in the adhesive, and no limited explanation is given other than that. The aforementioned rubbery polymer refers to a polymer that exhibits rubbery elasticity in a temperature region around room temperature. In addition, in this specification, the "main component" means containing more than 50 weight% of components unless it mentions in particular. In addition, in this specification, "acrylic polymer" means a polymer including, as a monomer unit constituting the polymer, a monomer unit derived from a molecule having at least one (methyl) base) acrylyl monomer. Hereinafter, a monomer having at least one (meth)acryloyl group in one molecule is also referred to as an "acrylic monomer". Therefore, the acrylic polymer in this specification is defined as a polymer containing a monomer unit derived from an acrylic monomer. A typical example of the acrylic polymer can be a polymer whose ratio of the acrylic monomer in the total monomers that can be used for the synthesis of the acrylic polymer is greater than 50% by weight (preferably greater than 70% by weight, eg, greater than 90% by weight). In addition, in this specification, a "(meth)acryloyl group" means an acryl group and a methacryloyl group in general. Similarly, "(meth)acrylate" means acrylate and methacrylate collectively, and "(meth)acrylic acid" means acrylic acid and methacrylic acid collectively. Therefore, the concept of the acrylic monomer mentioned here may include both a monomer having an acryl group (acrylic monomer) and a monomer having a methacryloyl group (methacrylic monomer).

(Acrylic polymer (A)) The high-refractive-index adhesive layer disclosed herein is suitably implemented in a state comprising the following acrylic adhesive layer: refractive index greater than 1.570, storage elastic modulus at 25°C G' _V1 is 30kPa~700kPa, the total light transmittance is 86% or more, and the haze value is 1.0% or less. The acrylic polymer which is the base polymer of the above-mentioned acrylic adhesive layer preferably contains an aromatic ring-containing monomer (m1) as a monomer component constituting the acrylic polymer. That is, the acrylic polymer containing the aromatic ring-containing monomer (m1) as a monomer unit is suitable. Hereinafter, the acrylic polymer is also referred to as "acrylic polymer (A)". Here, the term "monomer components constituting an acrylic polymer" in this specification means whether it is contained in the adhesive composition in the form of a pre-formed polymer (which may be an oligomer), or is not contained in the adhesive composition. The form of the polymerized monomer is included in the adhesive composition, and all of the monomers constitute the repeating unit of the acrylic polymer in the adhesive formed from the adhesive composition. That is, the monomer component which comprises an acrylic polymer can be contained in the said adhesive composition in any form of a polymer, a non-polymer, and a partial polymer. From the viewpoint of the ease of preparation of the adhesive composition, in several aspects, substantially all (for example, 95% by weight or more, preferably 99% by weight or more) of the monomer component is preferably contained in the form of a polymer. adhesive composition. The adhesive composition containing substantially all of the monomer components in the form of a polymer is also preferable from the viewpoint of easily forming a laminated sheet with little strain or warpage.

(Single (m1)) As the monomer (m1), a compound containing at least one aromatic ring and at least one ethylenically unsaturated group in one molecule can be used. The monomer (m1) may be used alone or in combination of two or more of these compounds.

As an example of the said ethylenically unsaturated group, a (meth)acryloyl group, a vinyl group, a (meth)allyl group etc. are mentioned. A (meth)acryloyl group is preferable from the viewpoint of polymerization reactivity, and an acryl group is preferable from the viewpoint of flexibility and adhesiveness. From the viewpoint of suppressing the decrease in the flexibility of the adhesive, a compound (ie, a monofunctional monomer) having a number of ethylenically unsaturated groups contained in one molecule of the monomer (m1) can be suitably used.

The number of aromatic rings contained in one molecule of the compound that can be used as the monomer (m1) may be one, or two or more. The upper limit of the number of aromatic rings contained in the monomer (m1) is not particularly limited, and may be, for example, 16 or less. In some aspects, the number of the above-mentioned aromatic rings may be, for example, 12 or less, preferably 8 or less, more preferably 6, from the viewpoint of the ease of preparation of the acrylic polymer (A) or the transparency of the adhesive. Hereinafter, 5 or less may be sufficient, 4 or less may be sufficient, 3 or less may be sufficient, and 2 or less may be sufficient.

The compound which can be used as the monomer (m1) has an aromatic ring such as a benzene ring (which may be a benzene ring constituting a part of a biphenyl structure or a perylene structure); The carbocyclic ring such as the condensed ring, etc.; can also be, for example, a pyridine ring, a pyrimidine ring, a pyridine ring, a pyridine ring, a triazole ring, a pyrrole ring, a pyrazole ring, an imidazole ring, a triazole ring, an oxazole ring, an isoxazole ring azole ring, thiazole ring, thiophene ring and other heterocycles. The heteroatom contained as a ring constituent atom in the above-mentioned heterocycle may be, for example, one or two or more kinds selected from the group consisting of nitrogen, sulfur, and oxygen. In several aspects, the heteroatoms that make up the heterocycle can be one or both of nitrogen and sulfur. The monomer (m1) may have a structure in which 1 or more carbocycles and 1 or more heterocycles have been condensed like a dinaphthothiophene structure, for example.

The above-mentioned aromatic ring (preferably a carbocyclic ring) may have one or more substituents on the atoms constituting the ring, or may not have a substituent. When having a substituent, the substituent may be exemplified by an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkoxy group, and a glycidoxy group. basis, but not subject to such restrictions. In the substituent containing carbon atoms, the number of carbon atoms contained in the substituent is preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example. In several aspects, the aromatic ring may be an aromatic ring having no substituents on the ring constituent atoms, or may have a ring constituent atom selected from an alkyl group, an alkoxy group, and a halogen atom (eg, bromine) Atom) is an aromatic ring of 1 or 2 or more substituents in the group. Moreover, the aromatic ring which the monomer (m1) has has a substituent on a ring constituent atom means that this aromatic ring has a substituent other than the substituent which has an ethylenically unsaturated group.

The aromatic ring and the ethylenically unsaturated group may be directly bonded or bonded via a linking group. The above-mentioned linking group, for example, may include 1 or 2 selected from alkylene, oxyalkylene, poly(oxyalkylene), phenyl, alkylphenyl, alkoxyphenyl, and these groups. Groups with one or more structures in which the above hydrogen atoms are replaced by hydroxyl groups (such as hydroxyalkylene groups), oxy groups (-O- groups), thiooxy groups (-S- groups), etc. . In several aspects, an aromatic ring-containing monomer having a structure in which an aromatic ring and an ethylenically unsaturated group are directly bonded, or an aromatic ring-containing monomer selected from the group consisting of alkylene, oxyalkylene, and poly(oxyalkylene) can be suitably used. Aromatic ring-containing monomer of a structure in which the linking group in the group constituted by the group is bonded. The number of carbon atoms in the alkylene group and the oxyalkylene group is preferably 1 to 4, more preferably 1 to 3, for example, 1 or 2. The repeating number of the oxyalkylene unit in the above-mentioned poly(oxyalkylene) group may be, for example, 2-3.

Examples of the compound that can be suitably used as the monomer (m1) include aromatic ring-containing (meth)acrylates and aromatic ring-containing vinyl compounds. The aromatic ring-containing (meth)acrylate and the aromatic ring-containing vinyl compound can be used alone or in combination of two or more. You may use it in combination of 1 type or 2 or more types of aromatic ring-containing (meth)acrylates and 1 type or 2 or more types of aromatic ring-containing vinyl compounds.

The content of the monomer (m1) in the monomer component constituting the acrylic polymer (A) is not particularly limited, and can be set to achieve both the desired refractive index and adhesive properties (eg peel strength, flexibility, etc.) and/or Or the adhesive layer of optical properties (such as total light transmittance, haze value, etc.). In several aspects, the content of the monomer (m1) in the monomer component may be, for example, 30% by weight or more, preferably 50% by weight or more, 60% by weight or more, or 70% by weight or more . From the viewpoint of easily obtaining a higher refractive index, in several ideal aspects, the content of the above-mentioned monomer (m1) may be, for example, more than 70% by weight, may be more than 75% by weight, may be more than 80% by weight, and may be It may be 85% by weight or more, 90% by weight or more, or 95% by weight or more. The upper limit of the content of the monomer (m1) in the above-mentioned monomer component is 100% by weight. From the viewpoint of balancing high refractive index with adhesive properties and/or optical properties, it is advantageous to set the content of the above-mentioned monomer (m1) to be less than 100 wt %, for example, preferably about 99 wt % or less, more preferably 98 wt %. % by weight or less may be 97% by weight or less, or may be 96% by weight or less. In several aspects, the content of the monomer (m1) may be 93 wt % or less, 90 wt % or less, 80 wt % or less, or 75 wt % or less. In some aspects that place more emphasis on adhesive properties and/or optical properties, the content of the above-mentioned monomer (m1) in the above-mentioned monomer component may be 70% by weight or less, 60% by weight or less, or 45% by weight. %the following.

In several aspects of the technology disclosed herein, a monomer having two or more aromatic rings (preferably carbocyclic rings) in one molecule can be suitably used as the monomer in view of the ease of obtaining a higher refractive index enhancement effect. (m1). Examples of monomers having two or more aromatic rings in one molecule (hereinafter also referred to as "monomers containing plural aromatic rings") include: Monomers having a structure in which two or more non-condensed aromatic rings are bonded via a linking group. monomers, monomers with a structure in which two or more non-condensed aromatic rings are directly (that is, not separated by other atoms) chemically bonded, monomers with a condensed aromatic ring structure, monomers with a perylene structure, and a dinaphthothiophene structure monomers, monomers with dibenzothiophene structure, etc. The monomer containing a plurality of aromatic rings can be used alone or in combination of two or more.

The above-mentioned linking group can be, for example, an oxy group (-O-), a thiooxy group (-S-), an oxyalkylene group (such as -O-(CH ₂ ) _n - group, where n is 1-3, and It is preferably 1), a thiooxyalkylene group (such as -S-(CH ₂ ) _n - group, where n is 1 to 3, and is preferably 1), a straight-chain alkylene group (that is, -(CH _{2 )} ) _n -group, where n is 1 to 6, and is preferably 1 to 3), the alkylene in the above-mentioned oxyalkylene, the above-mentioned thiooxyalkylene and the above-mentioned straight-chain alkylene has been partially halogenated or Fully halogenated groups, etc. From the viewpoint of the flexibility of the adhesive, etc., suitable examples of the above-mentioned linking group include an oxy group, a thiooxy group, an oxyalkylene group, and a straight-chain alkylene group. Specific examples of the monomer having a structure in which two or more non-condensed aromatic rings are bonded via a linking group include phenoxybenzyl (meth)acrylate (for example, m-phenoxybenzyl (meth)acrylate) , thiophenoxybenzyl (meth)acrylate, benzyl benzyl (meth)acrylate, etc.

The above-mentioned monomers with a structure in which two or more non-condensed aromatic rings are directly chemically bonded can be, for example, (meth)acrylate containing biphenyl structure, (meth)acrylate containing triphenyl structure, and biphenyl containing vinyl group. Wait. Specific examples thereof include o-phenylphenol (meth)acrylate, biphenylmethyl (meth)acrylate, and the like.

Examples of the monomer having a condensed aromatic ring structure include naphthalene ring-containing (meth)acrylate, anthracene ring-containing (meth)acrylate, vinyl naphthalene, vinyl anthracene, and the like. Specific examples include: 1-naphthylmethyl (meth)acrylate (alias: 1-naphthylmethyl (meth)acrylate), hydroxyethylated β-naphthol acrylate, 2-naphthylethyl ( Meth)acrylate, 2-naphthoxyethylacrylate, 2-(4-methoxy-1-naphthyloxy)ethyl (meth)acrylate, and the like.

Specific examples of the monomers having the above-mentioned fluoride structure include 9,9-bis(4-hydroxyphenyl) fluoride (meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl ] Fluorine (meth)acrylate, etc. In addition, the monomer having a pyrene structure is included in the concept of a monomer having a structure in which two or more non-condensed aromatic rings are directly chemically bonded because it includes a structural moiety in which two benzene rings are directly chemically bonded.

Examples of the monomer having the above-mentioned dinaphthothiophene structure include (meth)acryloyl group-containing dinaphthothiophene, vinyl group-containing dinaphthothiophene, and (meth)allyl group-containing dinaphthothiophene. Specific examples include: (meth)acryloyloxymethyl dinaphthothiophene (for example, CH ₂ CH(R ¹ )C(O)OCH ₂ - A compound of the structure; here, R ¹ is a hydrogen atom or a methyl group), (meth)acryloyloxyethyl dinaphthothiophene (for example, a CH is bonded to the 5- or 6-position of the dinaphthothiophene ring) ₂ CH(R ¹ )C(O)OCH(CH ₃ )- or CH ₂ CH(R ¹ )C(O)OCH ₂ CH ₂ - structure; here, R ¹ is a hydrogen atom or a methyl group) , vinyl dinaphthothiophene (for example, a compound in which a vinyl group is bonded to the 5-position or 6-position of the naphthothiophene ring), (meth)allyloxydinaphthothiophene, and the like. In addition, the monomer system having a dinaphthothiophene structure is also included in the concept of the monomer having a condensed aromatic ring structure by including a naphthalene structure and a structure having a thiophene ring and two naphthalene structures that have been condensed .

Examples of the monomer having the above-mentioned dibenzothiophene structure include (meth)acryloyl group-containing dibenzothiophene, vinyl group-containing dibenzothiophene, and the like. In addition, the monomer having a dibenzothiophene structure is included in the concept of the monomer having a condensed aromatic ring structure because it has a structure in which a thiophene ring and two benzene rings have been condensed. In addition, neither the dinaphthothiophene structure nor the dibenzothiophene structure belongs to a structure in which two or more non-condensed aromatic rings are directly chemically bonded.

As the monomer (m1) of the technique disclosed here, a monomer having one aromatic ring (preferably a carbocyclic ring) in one molecule can also be used. A monomer having one aromatic ring in one molecule contributes to, for example, improving the flexibility of the adhesive, adjusting the adhesive properties, improving transparency, and the like. In some aspects, from the viewpoint of raising the refractive index of the adhesive, a monomer having one aromatic ring per molecule is preferably used in combination with a monomer having a plurality of aromatic rings.

Examples of monomers having one aromatic ring in one molecule include benzyl (meth)acrylate, methoxybenzyl (meth)acrylate, phenyl (meth)acrylate, and ethoxylated phenol (methyl) (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxybutyl (meth)acrylate, cresyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, Carbon-containing aromatic ring (meth)acrylates such as chlorobenzyl (meth)acrylate; 2-(4,6-dibromo-2-tertiary butylphenoxy)ethyl (meth)acrylate, 2-(4,6-Dibromo-2-isopropylphenoxy)ethyl(meth)acrylate, 6-(4,6-dibromo-2-tertiarybutylphenoxy)hexyl ( Meth)acrylate, 6-(4,6-dibromo-2-isopropylphenoxy)hexyl(meth)acrylate, 2,6-dibromo-4-nonylphenylacrylate, 2 ,6-dibromo-4-dodecylphenyl acrylate and other bromine-substituted aromatic ring (meth)acrylates; styrene, α-methylstyrene, vinyltoluene, tertiary butylstyrene, etc. Carboaromatic vinyl compounds; N-vinylpyridine, N-vinylpyrimidine, N-vinylpyridine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole and other heteroaromatic rings have vinyl substituents compounds, etc.

As the monomer (m1), a monomer having a structure in which an oxyethyl-extended chain is sandwiched between the ethylenically unsaturated group and the aromatic ring in the above-mentioned various aromatic ring-containing monomers can also be used. As described above, a monomer in which an oxyethyl-extended chain is sandwiched between an ethylenically unsaturated group and an aromatic ring can be regarded as an ethoxylate of the original monomer. The repeating number of the oxyethylidene unit (-CH ₂ CH ₂ O-) in the above oxyethylidene chain is typically 1 to 4, preferably 1 to 3, more preferably 1 to 2, and for example, 1. Specific examples of ethoxylated aromatic ring-containing monomers include: ethoxylated o-phenylphenol (meth)acrylate, ethoxylated nonylphenol (meth)acrylate, ethoxylated methyl Phenol (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol di(meth)acrylate, and the like.

The content of the monomer containing a plurality of aromatic rings in the monomer (m1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In several aspects, the content of the monomer containing a plurality of aromatic rings in the monomer (m1) may be, for example, 50% by weight or more, from the viewpoint of easily realizing an adhesive with a higher refractive index, and it is suitable It may be 70% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The monomer (m1) may be substantially 100% by weight of the monomer containing a plurality of aromatic rings. That is, as the monomer (m1), only one type or two or more types of monomers containing plural aromatic rings may be used. In addition, in several aspects, for example, considering the balance between high refractive index and adhesive properties and/or optical properties, the content of the monomer containing a plurality of aromatic rings in the monomer (m1) may be less than 100% by weight, and may be It may be 98 wt % or less, 90 wt % or less, 80 wt % or less, or 65 wt % or less. In several aspects, in consideration of adhesive properties and/or optical properties, the content of the monomer containing a plurality of aromatic rings in the monomer (m1) may be 70 wt % or less, may be 50 wt % or less, may be 25% by weight or less, or 10% by weight or less. The technique disclosed here can be implemented even if the content of the monomer containing a plurality of aromatic rings in the monomer (m1) is less than 5% by weight. A monomer containing a plurality of aromatic rings may not be used.

The content of the monomer containing a plurality of aromatic rings in the monomer component constituting the acrylic polymer is not particularly limited, and can be set to achieve both the desired refractive index and adhesion properties (such as peel strength, flexibility, etc.) and/or Or the adhesive layer of optical properties (such as total light transmittance, haze value, etc.). The content of the monomer containing a plurality of aromatic rings in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In several aspects, from the viewpoint of easily realizing an adhesive with a higher refractive index, the content of the monomer containing a plurality of aromatic rings in the above-mentioned monomer components may be, for example, greater than 35 wt %, preferably greater than 50 wt % %, may be greater than 70% by weight, may be greater than or equal to 75% by weight, may be greater than or equal to 85% by weight, may be greater than or equal to 90% by weight, or greater than or equal to 95% by weight. The content of the monomer containing a plurality of aromatic rings in the above-mentioned monomer components may be 100% by weight, but from the viewpoint of balancing high refractive index and adhesive properties and/or optical properties, it is advantageous to set it to less than 100% by weight is preferably about 99 wt % or less, preferably 98 wt % or less, can be 96 wt % or less, can be 93 wt % or less, can be 90 wt % or less, can be 85 wt % or less, can be 80 wt % or less The weight % or less may be 75 weight % or less. In several aspects, considering the adhesive properties and/or optical properties, the content of the monomers containing a plurality of aromatic rings in the above-mentioned monomer components may be 70 wt % or less, 50 wt % or less, and 25 wt % or less. % by weight or less may be 15% by weight or less, or may be 5% by weight or less. The technique disclosed here can be implemented even in the state in which the content of the monomer containing a plurality of aromatic rings in the above-mentioned monomer components is less than 3% by weight.

In several aspects of the technology disclosed herein, a high refractive index monomer may preferably be employed as at least a portion of the monomer (m1). Here, the "high refractive index monomer" means a monomer whose refractive index is, for example, about 1.510 or more, preferably about 1.530 or more, and more preferably about 1.550 or more. The upper limit of the refractive index of the high-refractive-index monomer is not particularly limited, but from the viewpoint of ease of preparation of the adhesive composition or ease of compatibility with flexibility suitable for use as an adhesive, it is, for example, 3.000 or less, and may be 2.500 Hereinafter, it may be 2.000 or less, 1.900 or less, 1.800 or less, or 1.700 or less. A high refractive index monomer can be used individually by 1 type or in combination of 2 or more types. In addition, the refractive index of the monomer was measured under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25°C using an Abbe refractometer. The Abbe refractometer can use the type "DR-M4" manufactured by ATAGO or its equivalent. When there is a nominal value of the refractive index at 25°C provided from the manufacturer or the like, the nominal value can be used.

The above-mentioned high-refractive-index monomers can be appropriately used from among the compounds included in the concept of the aromatic ring-containing monomer (m1) disclosed herein (for example, the compounds and compound groups exemplified above) having such a refractive index. Specific examples include: m-phenoxybenzyl acrylate (refractive index: 1.566, Tg of homopolymer: -35°C), 1-naphthalene methacrylate (refractive index: 1.595, Tg of homopolymer: 31) ℃), ethoxylated o-phenylphenol acrylate (repetition number of oxyethylidene units: 1, refractive index: 1.578), benzyl acrylate (refractive index (nD20): 1.519, Tg of homopolymer: 6 ℃), phenoxyethyl acrylate (refractive index (nD20): 1.517, Tg of homopolymer: 2℃), phenoxydiethylene glycol acrylate (refractive index: 1.510, Tg of homopolymer: -35 ℃), 6-acryloyloxymethyl dinaphthothiophene (6MDNTA, refractive index: 1.75), 6-methacrylooxymethyl dinaphthothiophene (6MDNTMA, refractive index: 1.726), 5-propene Ethyloxyethyldinaphthothiophene (5EDNTA, refractive index: 1.786), 6-propenyloxyethyldinaphthothiophene (6EDNTA, refractive index: 1.722), 6-vinyldinaphthothiophene (6VDNT, Refractive index: 1.802), 5-vinyldinaphthothiophene (abbreviation: 5VDNT, refractive index: 1.793), etc., but not limited thereto.

The content of the high-refractive-index monomer (that is, the aromatic-ring-containing monomer with a refractive index of about 1.510 or more, preferably about 1.530 or more, preferably about 1.550 or more) in the monomer (m1) is not particularly limited, for example, it can be 5% by weight or more, 25% by weight or more, 35% by weight or more, or 40% by weight or more. In several aspects, from the viewpoint of easily obtaining a higher refractive index, the content of the high refractive index monomer in the monomer (m1) may be, for example, 50 wt % or more, preferably 70 wt % or more, or It may be 85% by weight or more, 90% by weight or more, or 95% by weight or more. The monomer (m1) may be substantially 100% by weight of the high refractive index monomer. In addition, in several aspects, for example, from the viewpoint of balancing high refractive index with adhesive properties and/or optical properties, the content of the high refractive index monomer in the monomer (m1) may be less than 100 wt %, and may be It may be 98 wt % or less, 90 wt % or less, 80 wt % or less, or 65 wt % or less. In several aspects, the content of the high refractive index monomer in the monomer (m1) may be 70 wt % or less, may be 50 wt % or less, and may be 25 wt % in consideration of adhesive properties and/or optical properties Hereinafter, it may be 15% by weight or less, or 10% by weight or less. The technique disclosed here can be implemented even in a state where the content of the high refractive index monomer in the monomer component (m1) is less than 5 wt %. It is also possible not to use a high refractive index monomer.

The content of the high-refractive-index monomer in the monomer component constituting the acrylic polymer is not particularly limited, and can be set to achieve both the desired refractive index and adhesive properties (such as peel strength, flexibility, etc.) and/or optical properties (such as total light transmittance, haze value, etc.) of the adhesive layer. The content of the high refractive index monomer in the monomer component may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In several aspects, from the viewpoint of easily realizing an adhesive with a higher refractive index, the content of the high-refractive-index monomer in the above-mentioned monomer components may be, for example, greater than 35% by weight, preferably greater than 50% by weight, or It may be more than 70% by weight, 75% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The content of the high-refractive-index monomer in the above-mentioned monomer components may be 100% by weight, but from the viewpoint of balancing high refractive index and adhesive properties and/or optical properties, it is advantageous to set it to less than 100% by weight. 99 wt % or less, preferably 98 wt % or less, 96 wt % or less, 93 wt % or less, 90 wt % or less, 85 wt % or less, 80 wt % or less, It may be 75% by weight or less. In several aspects, in consideration of adhesive properties and/or optical properties, the content of the high-refractive index monomer in the monomer component may be 70 wt % or less, 50 wt % or less, or 25 wt % or less , may be 15 wt % or less, or 5 wt % or less. The technique disclosed here can be implemented even in the state where the content of the high-refractive-index monomer in the above-mentioned monomer components is less than 3% by weight.

In several desirable aspects of the technology disclosed herein, at least a part of the monomer (m1) is a homopolymer with a Tg of 10°C or less (preferably 5°C or less, or 0°C or less, preferably -10°C) Hereinafter, the aromatic ring-containing monomer (hereafter referred to as "monomer L") is more preferably -20°C or lower, for example, -25°C or lower. When increasing the aromatic ring-containing monomer (m1) in the monomer component (especially the aromatic ring-containing monomer (m1) corresponding to one or both of the above-mentioned monomers containing a plurality of aromatic rings and high-refractive index monomers )), the storage elastic modulus G' of the adhesive tends to increase substantially, but by using the monomer L as a part or all of the monomer (m1), the storage elastic modulus G' can be suppressed. rise. Thereby, the flexibility suitable as an adhesive can be maintained better, and the refractive index can be raised. The lower limit of the Tg of the monomer L is not particularly limited. Considering the balance with the refractive index raising effect, in several aspects, the Tg of the monomer L may be, for example, -70°C or higher, -55°C or higher, or -45°C or higher. The monomer L can be used alone or in combination of two or more.

As the monomer L, one having the Tg can be appropriately used from among the compounds included in the concept of the aromatic ring-containing monomer (m1) disclosed herein (for example, the compounds and compound groups exemplified above). A suitable example of the aromatic ring-containing monomer that can be used as the monomer L includes m-phenoxybenzyl acrylate (Tg of homopolymer: -35°C). Another suitable example is phenoxydiethylene glycol acrylate (Tg of homopolymer: -35°C).

The content of the monomer L in the monomer (m1) is not particularly limited, and may be, for example, 5% by weight or more, 25% by weight or more, or 40% by weight or more. In several aspects, the content of the monomer L in the monomer (m1) may be, for example, 50 wt It may be 60% by weight or more, 70% by weight or more, 75% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The monomer (A1) may be substantially the monomer L in 100% by weight. In addition, in several aspects, for example, from the viewpoint of balancing flexibility suitable for use as an adhesive and high refractive index, the content of the monomer L in the monomer (m1) may be less than 100% by weight, and may be 98% by weight. % by weight or less, 90% by weight or less, 80% by weight or less, 70% by weight or less, 50% by weight or less, 25% by weight or less, or 10% by weight or less. The technique disclosed here can be implemented even in the state in which the content of the monomer L in the monomer (m1) is less than 5 wt %. Monomer L may not be used.

The content of the monomer L in the monomer component constituting the acrylic polymer may be, for example, 3% by weight or more, 10% by weight or more, or 25% by weight or more. In several aspects, the content of the monomer L in the monomer component may be, for example, greater than 35 wt %, and may be greater than 50 wt %, from the viewpoint of easily obtaining an adhesive with a higher level of high refractive index and flexibility. %, may be greater than 70% by weight, may be greater than or equal to 75% by weight, may be greater than or equal to 85% by weight, may be greater than or equal to 90% by weight, or greater than or equal to 95% by weight. The content of the monomer L in the above-mentioned monomer components may be 100% by weight, but considering the balance between high refractive index and adhesive properties and/or optical properties, it is advantageous to set it to less than 100% by weight, and preferably about 99% by weight % or less, preferably 98 wt % or less, 96 wt % or less, 95 wt % or less, 93 wt % or less, 90 wt % or less, 85 wt % or less, 80 wt % or less % or less, and may be 75% by weight or less. In several aspects, the content of the monomer L in the above-mentioned monomer components may be 70 wt % or less, 50 wt % or less, 25 wt % or less, 15 wt % or less, or 5 wt % or less. % by weight or less. The technique disclosed here can be implemented even in the state where the content of the monomer L in the above-mentioned monomer components is less than 3% by weight.

In several aspects, from the viewpoint of the flexibility of the adhesive, it _{is advantageous for the glass transition temperature Tg m1 to} be about 20°C or lower, preferably 10°C or lower (eg, 5°C), depending on the composition of the monomers (m1). below), preferably 0°C or lower, more preferably -10°C or lower, may be -20°C or lower, or -25°C or lower. The lower limit of the glass transition temperature Tg _{m1 is not particularly limited.} Considering the balance with the refractive index raising effect, in several aspects, the glass transition temperature Tg _m1 may be, for example, -70°C or higher, -55°C or higher, or -45°C or higher. The technique disclosed herein can be suitably implemented even when the glass transition temperature Tg _m1 is, for example, -40°C or higher, -35°C or higher, -33°C or higher, -30°C or higher, or -25°C or higher.

Here, the glass transition temperature Tg _m1 based on the composition of the monomer (m1) means the Tg obtained by the Fox formula described later only based on the composition of the monomer (m1) in the monomer component constituting the acrylic polymer. The glass transition temperature Tg _m1 can be obtained by applying the below-described Fox formula only for the monomer (m1) constituting the monomer components of the acrylic polymer, and from the average of each aromatic ring-containing monomer used as the monomer (m1). The glass transition temperature of the polymer and the weight fraction of each aromatic ring-containing monomer in the total amount of monomers (m1) were calculated. In an aspect in which only one monomer is used as the monomer (m1), the Tg of the homopolymer of the monomer corresponds to the glass transition temperature Tg _m1 .

In several aspects, the aromatic ring-containing monomer (m1) can be combined with the monomer L (that is, the Tg of the homopolymer is 10°C or lower, preferably 5°C or lower, or 0°C or lower, preferably -10°C). ℃ or lower, more preferably -20 ℃ or lower, for example, -25 ℃ or less aromatic ring-containing monomer) and monomer H whose Tg is higher than 10 ℃ are used. The Tg of the monomer H may be higher than 10°C, higher than 15°C, or higher than 20°C, for example. By combining the monomer L and the monomer H, for example, in the composition with a large content of the aromatic ring-containing monomer (m1) in the monomer component, the high refractive index and flexibility of the adhesive can be taken into account at a higher level. . The usage-amount ratio of the monomer L and the monomer H can be set so that the effect can be appropriately exhibited, and is not particularly limited. For example, it is preferable to set the usage ratio of the monomer L to the monomer H so as to satisfy any one of the above-mentioned glass transition temperatures Tg _m1 .

In several aspects, the aromatic ring-containing monomer (m1) can be suitably selected from compounds that do not contain a structure in which two or more non-condensed aromatic rings are directly chemically bonded (eg, a biphenyl structure). For example, it is suitable to be an acrylic polymer composed of the following monomer components: the content of the compound containing a structure in which two or more non-condensed aromatic rings are directly chemically bonded is less than 5% by weight (preferably less than 3% by weight, may also be 0% by weight). Limiting the amount of the compound containing two or more non-condensed aromatic rings that are directly chemically bonded as described above is advantageous from the viewpoint of realizing an adhesive that balances flexibility or adhesiveness with a high refractive index.

(Single (m2)) In some aspects of the technology disclosed herein, the monomer component constituting the acrylic polymer may further contain a monomer (m2) in addition to the above-mentioned monomer (m1). The above-mentioned monomer (m2) is a monomer corresponding to at least one of a hydroxyl group-containing monomer (hydroxyl group-containing monomer) and a carboxyl group-containing monomer (carboxyl group-containing monomer). The above-mentioned hydroxyl group-containing monomer is a compound having at least one hydroxyl group and at least one ethylenically unsaturated group in one molecule. The above-mentioned carboxyl group-containing monomer is a compound containing at least one carboxyl group and at least one ethylenically unsaturated group in one molecule. The monomer (m2) contributes to the introduction of a crosslinking point into the acrylic polymer, or to impart appropriate cohesiveness to the adhesive. A monomer (m2) can be used individually by 1 type or in combination of 2 or more types. Monomer (m2) is typically a monomer that does not contain an aromatic ring.

As an example of the ethylenically unsaturated group which the monomer (m2) has, a (meth)acryloyl group, a vinyl group, a (meth)allyl group, etc. are mentioned. A (meth)acryloyl group is preferable from the viewpoint of polymerization reactivity, and an acryl group is preferable from the viewpoint of flexibility and adhesiveness. From the viewpoint of suppressing the decrease in the flexibility of the adhesive, a compound (ie, a monofunctional monomer) having a number of ethylenically unsaturated groups contained in one molecule can be suitably used as the monomer (m2).

Examples of hydroxyl-containing monomers include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxy (meth)acrylate Hexyl ester, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, (4-hydroxymethylcyclohexyl)methyl (methyl) ) acrylates and other hydroxyalkyl (meth)acrylates, but not limited thereto. Examples of the hydroxyl group-containing monomer that can be suitably used include 4-hydroxybutyl acrylate (Tg: -40°C) and 2-hydroxyethyl acrylate (Tg: -15°C). From the viewpoint of improving the flexibility in the room temperature region, 4-hydroxybutyl acrylate having a lower Tg is preferred. In an ideal aspect, more than 50 wt % (eg, greater than 50 wt %, greater than 70 wt %, or greater than 85 wt %) of the monomer (m2) may be 4-hydroxybutyl acrylate. The hydroxyl group-containing monomer may be used alone or in combination of two or more.

In several aspects using a hydroxyl-containing monomer as a monomer (m2), the said hydroxyl-containing monomer may be 1 type or 2 or more types selected from the compound which does not have a methacryloyl group. Suitable examples of the hydroxyl group-containing monomer having no methacryloyl group include the aforementioned various hydroxyalkyl acrylates. For example, more than 50% by weight, more than 70% by weight or more than 85% by weight of the hydroxyl group-containing monomer used as the monomer (m2) is preferably hydroxyalkyl acrylate. By using hydroxyalkyl acrylate, a hydroxyl group that contributes to providing a crosslinking point or imparting moderate cohesiveness can be introduced into the acrylic polymer, and it is easier to obtain than the case of using only the corresponding hydroxyalkyl methacrylate Adhesives with good softness or adhesion at room temperature.

In addition to acrylic monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, and carboxypentyl (meth)acrylate, examples of carboxyl group-containing monomers include itonic acid, maleic acid, fumaric acid, Crotonic acid and isocrotonic acid, etc., but not limited thereto. Examples of carboxyl group-containing monomers that can be suitably used include acrylic acid and methacrylic acid. The carboxyl group-containing monomer can be used alone or in combination of two or more. A hydroxyl group-containing monomer and a carboxyl group-containing monomer may be used in combination.

The content of the monomer (m2) in the monomer component constituting the acrylic polymer is not particularly limited, and can be set according to the purpose. In several aspects, the content of the above-mentioned monomer (m2) may be, for example, 0.01 wt % or more, 0.1 wt % or more, or 0.5 wt % or more. From the viewpoint of obtaining a higher use effect, in several aspects, the content of the above-mentioned monomer (A2) is preferably 1% by weight or more, may be 2% by weight or more, and may be 4% by weight. above. The upper limit of the content of the monomer (m2) in the monomer component is set so that the total of the content of the other monomers does not exceed 100% by weight. In some aspects, the content of the above-mentioned monomer (m2) is suitable, for example, to be 30 wt % or less or 25 wt % or less, and it is easy to increase the refractive index by making the content of the monomer (m1) relatively large. From a viewpoint, it is preferably 20 wt % or less, more preferably 15 wt % or less, may be less than 12 wt %, may be less than 10 wt %, or may be less than 7 wt %.

In the aspect of using the hydroxyl group-containing monomer as the monomer (m2), the content of the hydroxyl group-containing monomer in the monomer component is not particularly limited, for example, it may be 0.01% by weight or more (preferably 0.1% by weight or more, 0.5% by weight or more). In several aspects, the content of the hydroxyl group-containing monomer is preferably 1 wt % or more of the monomer component, may be 2 wt % or more, and may be 4 wt % or more. The upper limit of the content of the hydroxyl group-containing monomer in the monomer component is set so that the total content of the other monomers does not exceed 100% by weight. From the viewpoint that the content of the body (m1) is relatively large and the refractive index is easily increased, it is preferably 20 wt % or less, more preferably 15 wt % or less, may be less than 12 wt %, may be less than 10 wt %, or May be less than 7% by weight.

In the aspect of using the carboxyl group-containing monomer as the monomer (m2), the content of the carboxyl group-containing monomer in the monomer component is not particularly limited, for example, it may be 0.01% by weight or more (preferably 0.1% by weight or more, more preferably 0.3% by weight or more). In some aspects, the content of the carboxyl group-containing monomer may be 1% by weight or more, 2% by weight or more, or 4% by weight or more. The upper limit of the content of the carboxyl group-containing monomer in the monomer component is set so that the total amount of the other monomers does not exceed 100% by weight. From the viewpoint that the content of the monomer (m1) is relatively large and the refractive index is easily increased, it is preferably 20% by weight or less, more preferably 15% by weight or less, may be less than 12% by weight, or may be less than 10% by weight . In several aspects, from the viewpoint of improving the flexibility of the adhesive, it is advantageous to set the content of the carboxyl group-containing monomer to less than 7% by weight, preferably less than 5% by weight, and may be less than 3% by weight %, may be less than 1% by weight, or may be less than 0.5% by weight. The technique disclosed here can be suitably implemented, for example, in a state in which only a hydroxyl group-containing monomer is used as the monomer (m2), that is, in a state in which a carboxyl group-containing monomer is not used.

The total content of the monomer (m1) and the monomer (m2) in the monomer components constituting the acrylic polymer may be, for example, 31% by weight or more, preferably 51% by weight or more, 61% by weight or more, or It is 71 weight% or more. In some aspects, the total content of the monomer (m1) and the monomer (m2) in the monomer components constituting the acrylic polymer may be, for example, from the viewpoint that the effects of these monomers are easily exerted appropriately. 76 wt % or more, preferably 81 wt % or more, 86 wt % or more, 91 wt % or more, 96 wt % or more, 99 wt % or more, or substantially 100 wt %.

(single m3) The monomer components constituting the acrylic polymer may also contain monomers other than the above-mentioned monomer (m1) and the above-mentioned monomer (m2) as required. An example of the said arbitrary component is an alkyl (meth)acrylate (henceforth "monomer (m3)"). The monomer (m3) helps to adjust the flexibility of the adhesive or improve the compatibility within the adhesive.

The monomer (m3) can be suitably used for an alkyl (meth)acrylate having a linear or branched alkyl group _{having 1 to 20 carbon atoms (ie, C 1-20) at the ester end.} Specific examples of (meth)acrylate C _1-20 alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and isopropyl (meth)acrylate , n-butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, tertiary butyl (meth)acrylate, amyl (meth)acrylate, (meth)acrylate ) isoamyl acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate , nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, ten (meth)acrylate Diester, Tridecyl (meth)acrylate, Myristyl (meth)acrylate, Pentadecyl (meth)acrylate, Cetyl (meth)acrylate, Heptadecyl (meth)acrylate, (meth)acrylate base) octadecyl acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, eicosyl (meth)acrylate, etc., but not limited thereto.

In several aspects, at least a portion of the monomer (m3) may suitably be an alkane (meth)acrylate whose Tg of the homopolymer is below -20°C (preferably below -40°C, eg, below -50°C). base ester. The low Tg alkyl (meth)acrylate helps to improve the softness of the adhesive. The lower limit of Tg of the above-mentioned alkyl (meth)acrylate is not particularly limited, but may be, for example, -85°C or higher, -75°C or higher, -65°C or higher, or -60°C or higher. Specific examples of the above-mentioned low Tg (meth)acrylate alkyl ester include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), isononyl acrylate (iNA), and the like.

In some aspects using the monomer (m3), it is preferable that at least a part of the above-mentioned monomer (m3) is an alkyl acrylate from the viewpoint of flexibility, adhesiveness, and the like. For example, 50% by weight or more (preferably 75% by weight or more, more preferably 90% by weight or more) of the monomer (m3) is preferably an alkyl acrylate. As a monomer (m3), only 1 type or 2 or more types of alkyl acrylates may be used, and the aspect which does not use alkyl methacrylates may be sufficient.

In the aspect in which the monomer component contains the alkyl (meth)acrylate, the content of the alkyl (meth)acrylate in the monomer component can be set so that its use effect can be appropriately exhibited. In several aspects, the content of the above-mentioned alkyl (meth)acrylate may be, for example, 1 wt % or more, 3 wt % or more, 5 wt % or more, or 8 wt % or more. In several aspects, the content of the above-mentioned alkyl (meth)acrylate may be 15% by weight or more, 30% by weight or more, or 45% by weight or more. The upper limit of the content of the monomer (m3) in the monomer component is set so that the total of the content of other monomers does not exceed 100% by weight, for example, it may be less than 50% by weight. In several aspects, the content of the aforementioned monomer (m3) may be, for example, less than 35% by weight. Generally speaking, the refractive index of alkyl (meth)acrylate is low. Therefore, in order to increase the refractive index, the content of the monomer (m3) in the monomer component is limited and the content of the monomer (m1) is relatively large. is beneficial. From this point of view, it is advantageous that the content of the monomer (m3) is 24% by weight or less of the monomer components, preferably less than 23% by weight, more preferably less than 20% by weight, may be less than 17% by weight, may be less than 12% by weight %, may be less than 7% by weight, may be less than 3% by weight, and may also be less than 1% by weight. The monomer (m3) may not be used substantially.

(other monomers) The monomer components constituting the acrylic polymer may also include monomers other than the above-mentioned monomers (m1), (m2), and (m3) (hereinafter referred to as "other monomers") as required. The other monomers mentioned above can be used, for example, to adjust the Tg of the acrylic polymer, adjust the adhesive properties, improve the compatibility in the adhesive layer, and the like. These other monomers can be used alone or in combination of two or more.

As an example of the said other monomer, the monomer (functional group containing monomer) which has a functional group other than a hydroxyl group and a carboxyl group is mentioned. For example, as other monomers which can improve the cohesive force or heat resistance of the adhesive, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, and the like can be mentioned. In addition, as a monomer that can introduce a functional group that can become a cross-linking point in an acrylic polymer, or can contribute to improving peel strength or improving compatibility in the adhesive layer, an amide group-containing monomer can be mentioned. monomers (such as (meth)acrylamide, N-methylol (meth)acrylamide, etc.), amine group-containing monomers (such as amine ethyl (meth)acrylate, N,N-dimethyl amine ethyl (meth)acrylate, etc.), monomers with nitrogen-containing rings (such as N-vinyl-2-pyrrolidone, N-(meth)acryloyl mofolin, etc.), Imine-based monomers, epoxy-containing monomers, ketone-containing monomers, isocyanate-containing monomers, alkoxysilicon-containing monomers, etc. In addition, among the monomers having a nitrogen atom-containing ring, for example, N-vinyl-2-pyrrolidone is also equivalent to an amide group-containing monomer. The same applies to the relationship between the above-mentioned monomer having a nitrogen atom-containing ring and an amine group-containing monomer.

Other monomers that can be used in addition to the above-mentioned functional group-containing monomers include: vinyl ester-based monomers such as vinyl acetate; (Meth)acrylate; Olefin-based monomers such as ethylene, butadiene, isobutylene; Chlorine-containing monomers such as vinyl chloride; Methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylic acid Esters, ethoxyethoxyethyl (meth)acrylate and other alkoxy-containing monomers; vinyl ether-based monomers such as methyl vinyl ether, etc. A suitable example of other monomers used for the purpose of improving the flexibility of the adhesive is ethoxyethoxyethyl acrylate (alias: ethyl carbitol acrylate, homopolymer Tg: -67 °C).

When the above-mentioned other monomers are used, the usage amount thereof is not particularly limited, and can be appropriately set within the range that the total amount of the monomer components does not exceed 100% by weight. In several aspects, the content of the above-mentioned other monomers in the monomer component may be, for example, about 35% by weight or less, from the viewpoint of easily exerting the refractive index raising effect obtained by using the monomer (m1). 25% by weight or less (eg, 0 to 25% by weight) is suitable, about 20% by weight or less (eg, 0 to 20% by weight), about 10% by weight or less, about 5% by weight or less, or about 1% by weight or less. % by weight or less. The techniques disclosed herein may suitably be implemented in a state where the monomer component is substantially free of the other monomers described above.

In several aspects, the monomer component constituting the acrylic polymer may be a composition in which the usage amount of the methacryloyl group-containing monomer is suppressed below a predetermined level. The use amount of the methacryloyl group-containing monomer in the monomer component may be, for example, less than 5% by weight, may be less than 3% by weight, may be less than 1% by weight, or may be less than 0.5% by weight. Limiting the amount of the methacryloyl group-containing monomer to be used as described above is advantageous from the viewpoint of realizing an adhesive that balances flexibility or tackiness with a high refractive index. The monomer component constituting the acrylic polymer may be a composition that does not contain a methacryloyl group-containing monomer (for example, a composition that is composed of only an acryl group-containing monomer).

In several aspects, the monomer component of the base polymer (eg, acrylic polymer) constituting the high-refractive-index adhesive layer, from the viewpoint of inhibiting coloring or discoloration (eg, yellowing) of the adhesive layer, contains The amount of the carboxyl monomer used should be limited. The use amount of the carboxyl group-containing monomer in the monomer component may be, for example, less than 1% by weight, preferably less than 0.5% by weight, preferably less than 0.3% by weight, may be less than 0.1% by weight, or may be less than 0.05% by weight. If the use amount of the carboxyl group-containing monomer is limited, the corrosion of metal materials (such as metal wirings or metal films that may exist on the adherend) that can be in contact with or disposed adjacent to the high-refractive index adhesive layer is suppressed by inhibiting corrosion. It is also beneficial from a point of view. The techniques disclosed herein can be suitably implemented in a state in which the above-mentioned monomer components do not contain a carboxyl group-containing monomer. For the same reason, in several aspects, the monomer component of the base polymer constituting the high-refractive index adhesive layer has an acidic functional group (in addition to the carboxyl group, it also contains a sulfonic acid group, a phosphoric acid group, etc.) among the monomers The amount of use should be limited. The use amount of the acid functional group-containing monomer in the monomer component of the aspect can be applied to the above-mentioned ideal use amount of the carboxyl group-containing monomer. The technique disclosed herein can be suitably implemented in the state in which the above-mentioned monomer components do not contain an acid group-containing monomer (that is, the state in which the base polymer of the high-refractive index adhesive layer is acid-free).

(Glass Transition Temperature Tg _{T of} Base Polymer) In several aspects, in the base polymer (eg, acrylic polymer) of the adhesive layer, the glass transition temperature Tg according to the composition of the monomer components constituting the polymer _T is preferably about 20°C or lower, preferably about 10°C or lower, more preferably 0°C or lower, may be -10°C or lower, may be -20°C or lower, may be -25°C or lower, and may be -28°C or lower , can also be below -30 ℃. From the viewpoint of improving the flexibility of the adhesive, it is advantageous _{that the glass transition temperature Tg T is low.} In addition, the glass transition temperature Tg _T may be, for example, -60°C or higher, but from the viewpoint of easily increasing the refractive index of the adhesive, it is preferably -50°C or higher, more preferably higher than -45°C, and may be higher than - 40°C, higher than -35°C, higher than -25°C, higher than -15°C, or higher than -5°C.

Here, the glass transition temperature Tg _{T of} a polymer means the glass transition temperature obtained by Fox's formula from the composition of the monomer components constituting the polymer, unless otherwise specified. As shown below, Fox's formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer after each of the monomers constituting the copolymer is homopolymerized. 1/Tg=Σ(Wi/Tgi) In the above formula of Fox, Tg represents the glass transition temperature of the copolymer (unit: K), and Wi represents the weight fraction of the monomer i in the copolymer (the copolymerization ratio based on weight). ), Tgi represents the glass transition temperature (unit: K) of the homopolymer of monomer i. As for the glass transition temperature of the homopolymer used for the calculation of Tg, the value described in known data such as "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) was used. Regarding the monomers with a plurality of values described in the above-mentioned Polymer Handbook, the highest value is used. When the Tg of the homopolymer is not described in the known data, the value obtained by the measurement method described in JP-A-2007-51271 is used.

(Preparation method of base polymer) In the technique disclosed here, the method for obtaining the base polymer of the adhesive layer (for example, the acrylic polymer (A) composed of the above-mentioned monomer components) is not particularly limited, and solution polymerization, emulsion polymerization can be appropriately used well-known polymerization methods such as polymerization method, bulk polymerization method, suspension polymerization method, and photopolymerization method. In several aspects, solution polymerization methods may be suitably employed. The polymerization temperature during solution polymerization can be appropriately selected according to the type of monomer and solvent used, the type of polymerization initiator, etc., for example, it can be set to about 20°C to 170°C (typically, about 40°C to 140°C).

The solvent (polymerization solvent) used for the solution polymerization can be appropriately selected from conventionally known organic solvents. For example, any one solvent or a mixed solvent of two or more selected from the following can be used: aromatic compounds (typically aromatic hydrocarbons) such as toluene; acetates such as ethyl acetate; hexane or cyclohexane Aliphatic or alicyclic hydrocarbons such as hexane; haloalkanes such as 1,2-dichloroethane; lower alcohols such as isopropanol (such as monohydric alcohols with 1 to 4 carbon atoms); tertiary butyl methyl Ethers such as ethers; ketones such as methyl ethyl ketone, etc.

The initiator used for the polymerization can be appropriately selected from known polymerization initiators according to the type of the polymerization method. For example, one type or two or more types of azo-based polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be suitably used. Other examples of polymerization initiators include: persulfates such as potassium persulfate; peroxide-based initiators such as benzyl peroxide and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; Aromatic carbonyl compounds, etc. Still another example of the polymerization initiator may be a redox-based initiator in which a peroxide and a reducing agent are combined. A polymerization initiator can be used individually by 1 type or in combination of 2 or more types. The usage-amount of the polymerization initiator may be an ordinary usage-amount, for example, it can be selected from the range of about 0.005-1 weight part (typically about 0.01-1 weight part) with respect to 100 weight part of monomer components.

In the above-mentioned polymerization, various chain transfer agents known in the past can be used as necessary. For example, thiols such as n-dodecyl mercaptan, tertiary dodecyl mercaptan, thioglycolic acid, and α-thioglycerol can be used. Alternatively, chain transfer agents containing no sulfur atoms (non-sulfur-tethered chain transfer agents) may also be used. Examples of non-sulfur chain transfer agents include anilines such as N,N-dimethylaniline and N,N-diethylaniline; terpenoids such as α-pinene and terpinolene; α-methylbenzene Styrenics such as ethylene, α-methylstyrene dimer, etc. A chain transfer agent can be used individually by 1 type or in combination of 2 or more types. When a chain transfer agent is used, the usage-amount can be about 0.01-1 weight part with respect to 100 weight part of monomer raw materials, for example.

The weight average molecular weight (Mw) of the base polymer is not particularly limited, and may be, for example, in the range of about 10×10 ⁴ to 500×10 ⁴ . From the viewpoint of adhesive properties, the Mw of the base polymer is preferably about 20×10 ⁴ to 400×10 ⁴ (preferably about 30×10 ⁴ to 150×10 ⁴ , for example, about 50×10 ⁴ to 130×10 . ⁴ ) within the range.

Here, the Mw of the polymer can be obtained by converting it into polystyrene by gel permeation chromatography (GPC). Specifically, it can be obtained by measuring under the following conditions using a trade name "HLC-8220GPC" (manufactured by Tosoh Corporation) as a GPC measuring device. [Measurement conditions of GPC] Sample concentration: 0.2% by weight (tetrahydrofuran solution) Sample injection volume: 10µL Eluent: Tetrahydrofuran (THF) Flow (flow rate): 0.6mL/min Column temperature (measurement temperature): 40°C String: Sample column: 1 trade name "TSKguardcolumn SuperHZ-H" + 2 trade name "TSKgel SuperHZM-H" (manufactured by Tosoh Corporation) Reference column: 1 piece of trade name "TSKgel SuperH-RC" (manufactured by Tosoh Corporation) Detector: Differential Refractometer (RI) Standard sample: polystyrene

(Refractive index enhancer) In several aspects of the technology disclosed herein, the high refractive index adhesive layer (eg, acrylic adhesive layer) may optionally contain a refractive index enhancer in addition to the base polymer. Here, the refractive index enhancer in this specification means a material that can increase the refractive index of the adhesive layer by using it. As the refractive index enhancer, a material having a higher refractive index than that of the adhesive layer containing the refractive index enhancer can be suitably used. Moreover, as a refractive index improver, the material whose refractive index is higher than the base polymer (for example, acrylic polymer (A)) of the adhesive layer containing this refractive index improver can be used suitably. By properly using the refractive index enhancer, a higher refractive index and practical adhesive performance can be suitably balanced. In several aspects, the refractive index enhancer is preferably an organic material. The organic material that can be used as a refractive index enhancer can be a polymer or a non-polymer. Moreover, it may have a polymerizable functional group, and may not have a polymerizable functional group. A refractive index enhancer can be used individually by 1 type or in combination of 2 or more types.

The refractive index of the refractive index enhancer (such as the additive ((H _RO )) described later can be set to an appropriate range in relation to the refractive index of the base polymer, so it is not limited to a specific range. The refractive index is, for example, greater than 1.55, greater than 1.56, or greater than 1.57, and can be selected from a range higher than the refractive index of the base polymer. From the viewpoint of high refractive index of the adhesive, in several aspects, the refractive index The refractive index of the rate-enhancing agent is advantageously 1.58 or more, preferably 1.60 or more, more preferably 1.63 or more, 1.65 or more, 1.70 or more, or 1.75 or more. As for the enhancer, the target refractive index can be achieved even by using a relatively small amount of the refractive index enhancer. This is ideal from the viewpoint of suppressing the decrease in adhesion properties or optical properties. The upper limit of the refractive index of the refractive index enhancer is not particularly limited. However, from the viewpoints of compatibility in the adhesive, high refractive index, and ease of compatibility with flexibility suitable for use as an adhesive, for example, it is 3.000 or less, may be 2.500 or less, may be 2.000 or less, and may be 1.950 or less, may be 1.900 or less, or 1.850 or less.

In several aspects, the refractive index improvers (e.g., later-described additives (H _RO)) of the refractive index n _B of the polymer substrate and the refractive index n of _a difference, i.e. n _b -n _a (hereinafter known as "Δn _A ”) is set to be greater than 0. In several aspects, Δn _A may be, for example, 0.02 or more, 0.05 or more, 0.07 or more, 0.10 or more, 0.15 or more, 0.20 or more, or 0.25 or more. By selecting the base polymer and the refractive index enhancer so as to increase Δn _A , the effect of increasing the refractive index using the refractive index enhancer tends to increase. _{Moreover, in several aspects, Δn A} may be, for example, 0.70 or less, 0.60 or less, 0.50 or less, from the viewpoint of compatibility in the adhesive layer, transparency of the adhesive layer, etc. is 0.40 or less or 0.35 or less.

In several aspects, the difference between the refractive index n _b of a refractive index enhancer (eg, an additive (H _{RO ) described later) and the refractive index n T} of the adhesive layer comprising the refractive index enhancer, ie n _b −n _T (hereinafter also referred to as "Δn _B ") is set to be larger than 0. In several aspects, Δn _B may be, for example, 0.02 or more, 0.05 or more, 0.07 or more, 0.10 or more, 0.15 or more, 0.20 or more, or 0.25 or more. By selecting the composition of the adhesive layer and the refractive index enhancer so as to increase Δn _B , the effect of increasing the refractive index using the refractive index enhancer tends to increase. In addition, from the viewpoints of compatibility in the adhesive layer, transparency of the adhesive layer, etc., in several aspects, Δn _B may be, for example, 0.70 or less, 0.60 or less, 0.50 or less, or may be is 0.40 or less or 0.35 or less.

The usage-amount of the refractive index enhancer with respect to 100 parts by weight of the base polymer (the total amount of the refractive index enhancer when using a plurality of types of refractive index enhancers) is not particularly limited, and can be set according to the purpose. From the viewpoint of increasing the refractive index of the adhesive, the amount of the refractive index enhancer to be used relative to 100 parts by weight of the base polymer can be, for example, 1 part by weight or more, and it is advantageous to set it as 3 parts by weight or more, and preferably 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or 20 parts by weight or more. In addition, in several aspects, the amount of the refractive index enhancer to be used relative to 100 parts by weight of the base polymer can be set to, for example, 80 parts by weight or less, so as to balance the high refractive index of the adhesive and the anti-adhesion properties or optical properties of the adhesive. From the viewpoint of lowering the properties, it is advantageous to be 60 parts by weight or less, and preferably 45 parts by weight or less. In some aspects where more emphasis is placed on adhesive properties or optical properties, the amount of the refractive index enhancer to be used relative to 100 parts by weight of the base polymer may be, for example, 30 parts by weight or less, 20 parts by weight or less, or 15 parts by weight Hereinafter, it may be 10 parts by weight or less, 5 parts by weight or less, or 3 parts by weight or less. The technique disclosed herein can be suitably implemented even if the amount of the refractive index enhancer used is less than 1 part by weight relative to 100 parts by weight of the base polymer in the adhesive layer, or the refractive index enhancer is not substantially used. Here, substantially non-use means at least unintentional use.

(Additive ( _HRO )) In several aspects, the refractive index enhancer may suitably employ an organic material having a higher refractive index than the base polymer. Hereinafter, the above-mentioned organic material may be expressed as "additive (H _RO )". Here, the above-mentioned “H _RO ” means an organic material with a high refractive index (High Refractive index). By combining a base polymer (such as an acrylic polymer, preferably an acrylic polymer (A)) and an additive (H _RO ), it can be achieved that the refractive index and adhesive properties (peel strength, flexibility, etc. ) and/or adhesives for optical properties (total light transmittance, haze value, etc.). The organic material that can be used as the additive (H _RO ) can be a polymer or a non-polymer. Moreover, it may have a polymerizable functional group, and may not have a polymerizable functional group. The additives (H _RO ) may be used alone or in combination of two or more.

The refractive index of the additive (H _RO ) was measured under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25° C. using an Abbe refractometer in the same manner as the refractive index of the monomer. When there is a nominal value of the refractive index at 25°C provided from the manufacturer or the like, the nominal value can be used.

The molecular weight of the organic material used as the additive (H _RO ) is not particularly limited and can be selected according to the purpose. The molecular weight of the additive (H _RO ) can be selected from, for example, a range of 30,000 or less. Also, the additive (H _RO ) is preferably a polymer or non-polymer having a lower molecular weight than the base polymer. In several aspects, the molecular weight of the _{additive (H RO ) is about less than} 10000 is suitable, preferably less than 5000, more preferably less than 3000 (eg less than 1000), may be less than 800, may be less than 600, may be less than 500, and may be less than 400. The fact that _{the molecular weight of the additive (H RO} ) is not too large is advantageous from the viewpoint of improving the compatibility in the adhesive layer. Moreover, the molecular weight of an additive (H _RO ) may be 130 or more, for example, and 150 or more may be sufficient as it. In several _{aspects, from the viewpoint of increasing} the refractive index of the additive (H _RO ), the molecular weight of the additive (H RO ) is preferably 170 or more, more preferably 200 or more, may be 230 or more, and may be 250 or more More than 270 may be sufficient, 500 or more may be sufficient, 1000 or more may be sufficient, and 2000 or more may be sufficient. In several aspects, a polymer having a molecular weight of about 1,000 to 10,000 (eg, 1,000 or more and less than 5,000) can be used as an additive (H _RO ). The molecular weight of the additive (H _RO ) can be calculated based on the chemical structure for a polymer with a non-polymer or a low degree of polymerization (eg, about 2 to 5 polymers). When the additive (H _RO ) is a polymer with a higher degree of polymerization, the weight average molecular weight (Mw) based on GPC performed under appropriate conditions can be used. When there is a nominal value of molecular weight provided from the manufacturer or the like, the nominal value can be used.

Examples of organic materials that can be an _{option for the additive (H RO} ) include organic compounds having an aromatic ring, organic compounds having a heterocyclic ring (which may be an aromatic ring or a non-aromatic heterocyclic ring), etc. etc. limited.

The aromatic ring possessed by the above-mentioned organic compound having an aromatic ring (hereinafter also referred to as "aromatic ring-containing compound") that can be used as an additive (H _{RO ) can be derived from the aroma possessed by the compound that can be used as a monomer (m1).} Ring the same thing to choose.

The said aromatic ring may have 1 or 2 or more substituents on a ring constituent atom, and may not have a substituent. When having a substituent, the substituent may be exemplified by an alkyl group, an alkoxy group, an aryloxy group, a hydroxyl group, a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, etc.), a hydroxyalkyl group, a hydroxyalkoxy group, and a glycidoxy group. basis, but not subject to such restrictions. In the substituent containing carbon atoms, the number of carbon atoms contained in the substituent is, for example, 1 to 10, preferably 1 to 6, preferably 1 to 4, more preferably 1 to 3, and may be 1 or 2, for example. In several aspects, the aromatic ring may be an aromatic ring having no substituents on the ring constituent atoms, or may have a ring constituent atom selected from an alkyl group, an alkoxy group, and a halogen atom (eg, bromine) Atom) is an aromatic ring of 1 or 2 or more substituents in the group.

Examples of the aromatic ring-containing compound usable as the additive (H _RO ) include: a compound usable as a monomer (m1); an oligomer including a compound usable as a monomer (m1) as a monomer unit ; Removal of a group having an ethylenically unsaturated group (which may be a substituent bound to a ring constituent atom) or a portion of the group constituting an ethylenically unsaturated group from the compound that can be used as a monomer (m1) and Substituted into a hydrogen atom or a group without an ethylenically unsaturated group (such as a hydroxyl group, an amine group, a halogen atom, an alkyl group, an alkoxy group, a hydroxyalkyl group, a hydroxyalkoxy group, a glycidoxy group, etc.) Compounds, etc., but are not limited by these. Non-limiting specific examples of the aromatic ring-containing compound that can be used as the additive (H _RO ) include: benzyl acrylate, m-phenoxybenzyl acrylate, 2-(o-phenylphenoxy)ethyl acrylate, Phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxy polyethylene glycol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, the above-mentioned monomers with a perylene structure, with two Monomers with naphthothiophene structure, monomers with dibenzothiophene structure and other aromatic ring-containing monomers; 3-phenoxybenzyl alcohol, dinaphthothiophene and their derivatives (such as bonds on the dinaphthothiophene ring Aromatic ring-containing compounds without ethylenically unsaturated groups such as compounds with one or more structures of one or more substituents selected from hydroxyl, methanol, diethanol and glycidyl) Wait. In addition, the aromatic ring-containing compound may be an oligomer comprising the aromatic ring-containing monomer as a monomer unit (preferably an oligomer with a molecular weight of about 5000 or less, more preferably about 1000 or less; for example, a 2-5 polymer low polymer around). The above-mentioned oligomers can be, for example: homopolymers of aromatic ring-containing monomers; copolymers of one or more aromatic ring-containing monomers; copolymers of one or more aromatic ring-containing monomers and other monomers things etc. As the other monomers mentioned above, one type or two or more types of monomers which do not have an aromatic ring can be used.

In some aspects, since it is easy to obtain a high refractive index-enhancing effect, an organic compound having two or more aromatic rings in one molecule (hereinafter also referred to as "compound containing plural aromatic rings") can be suitably used. as an additive (H _RO ). The compound containing a plurality of aromatic rings may or may not have a polymerizable functional group such as an ethylenically unsaturated group. In addition, the compound containing a plurality of aromatic rings may be a polymer or a non-polymer. In addition, the above-mentioned polymer may be an oligomer containing a monomer containing a plurality of aromatic rings as a monomer unit (preferably an oligomer with a molecular weight of about 5,000 or less, more preferably about 1,000 or less; for example, 2-5 polymers low polymer around). The above-mentioned oligomers can be, for example: homopolymers of monomers containing plural aromatic rings; copolymers of one or more monomers containing plural aromatic rings; one or more than two types of monomers containing plural aromatic rings Copolymers of its monomers and other monomers, etc. The above-mentioned other monomer may be an aromatic ring-containing monomer which is not a monomer containing a plurality of aromatic rings, a monomer without an aromatic ring, or a combination thereof.

Non-limiting examples of compounds containing a plurality of aromatic rings include: compounds having a structure in which two or more non-condensed aromatic rings are bonded via a linking group, compounds having two or more non-condensed aromatic rings directly (that is, without intervening other atoms) ) compounds with chemically bonded structures, compounds with condensed aromatic ring structures, compounds with perylene structures, compounds with dinaphthothiophene structures, compounds with dibenzothiophene structures, and the like. The compound containing a plurality of aromatic rings can be used alone or in combination of two or more.

In addition to the above-mentioned monomer having a fluoride structure, or an oligomer of a homopolymer or a copolymer of the above-mentioned monomer, 9,9-bis(4-hydroxybenzene can also be mentioned as a specific example of the compound having a fluoride structure. base) fluoride (refractive index: 1.68), 9,9-bis(4-aminophenyl) fluoride (refractive index: 1.73), 9,9-bis(4-hydroxy-3-methylphenyl) fluoride ( Refractive index: 1.68), 9,9-bis[4-(2-hydroxyethoxy)phenyl] fluoride (refractive index: 1.65), etc. 9,9-bisphenyl fluoride and its derivatives.

In addition to the above-mentioned monomers having a dinaphthothiophene structure, or oligomers of homopolymers or copolymers of the monomers, specific examples of the above-mentioned compounds having a dinaphthothiophene structure may also include: dinaphthothiophene Thiophene (refractive index: 1.808); hydroxyalkyldinaphthothiophene such as 6-hydroxymethyldinaphthothiophene (refractive index: 1.766); 2,12-dihydroxydinaphthothiophene (refractive index: 1.750), etc. Dihydroxydinaphthothiophene; 2,12-dihydroxyethyloxydinaphthothiophene (refractive index: 1.677) and other dihydroxyalkyloxydinaphthothiophenes; 2,12-diglycidyl Diglycidoxydinaphthothiophene such as oxydinaphthothiophene (refractive index 1.723); 2,12-diallyloxydinaphthothiophene (abbreviation: 2,12-DAODNT, refractive index 1.729) and the like having two or more ethylenically unsaturated groups such as dinaphthothiophenes and their derivatives.

In addition to the above-mentioned monomer having a dibenzothiophene structure, or an oligomer of a homopolymer or a copolymer of the above-mentioned monomer, dibenzothiophene can also be cited as a specific example of the compound having the dibenzothiophene structure. (refractive index: 1.607), 4-dimethyldibenzothiophene (refractive index: 1.617), 4,6-dimethyldibenzothiophene (refractive index: 1.617), and the like.

Examples of the organic compound having a heterocyclic ring (hereinafter also referred to as a heterocyclic ring-containing organic compound) which can be an option of the additive (H _{RO ) include a thioepoxy compound, a compound having a tricyclic ring, and the like.} Examples of the thioepoxy compound include bis(2,3-epithiopropyl)disulfide and polymers thereof (refractive index 1.74) described in Japanese Patent No. 3712653. As an example of the compound having a tris' ring, a compound having at least one (eg, 3 to 40, preferably 5 to 20) tris' rings in one molecule can be mentioned. In addition, the tricyclic ring is aromatic, so the compound having the tricyclic ring is also included in the concept of the above-mentioned aromatic ring-containing compound, and the compound having a plurality of tricyclic rings is also included in the above-mentioned compound containing a plurality of aromatic rings. in the concept.

In several aspects, compounds without ethylenically unsaturated groups may suitably be employed as additives (H _RO ). Thereby, deterioration of the adhesive composition due to heat or light (deterioration of leveling properties due to progress of gelation or increase in viscosity) can be suppressed, and storage stability can be improved. The use of an additive (H _RO ) without an ethylenically unsaturated group suppresses ethylenic unsaturation in an adhesive layer containing the additive (H _RO ) or a laminate (such as a laminate) containing the adhesive layer, etc. It is also preferable from the viewpoint of dimensional change or deformation (warpage, waviness, etc.), generation of optical strain, etc. caused by the reaction of the base.

In the case of using an oligomer as the additive (H _RO ), the oligomer can be obtained by polymerizing the corresponding monomer components by a known method. When the above-mentioned oligomer is produced by radical polymerization, a polymerization initiator, a chain transfer agent, an emulsifier, etc. that can be used for radical polymerization can be appropriately added to the above-mentioned monomer components, and the polymerization can be carried out. The above-mentioned polymerization initiators, chain transfer agents, emulsifiers, etc. that can be used for radical polymerization are not particularly limited, and can be appropriately selected and used. In addition, the weight-average molecular weight of the oligomer can be controlled by the usage amount of the polymerization initiator and the chain transfer agent, and the reaction conditions, and the usage amount can be appropriately adjusted according to the types of these. The above-mentioned chain transfer agent can be, for example, lauryl mercaptan, glycidyl mercaptan, thioacetic acid, 2-mercaptoethanol, α-thioglycerol, thioglycolic acid, 2-ethylhexyl thioglycolic acid, 2, 3-dimercapto-1-propanol, etc. A chain transfer agent may be used individually by 1 type, and may be used in mixture of 2 or more types. The amount of the chain transfer agent used can be set so that an oligomer having a desired weight average molecular weight can be obtained according to the composition of the monomer components that can be used in the synthesis of the oligomer, the type of the chain transfer agent, and the like. In several aspects, the chain transfer agent is suitably used in an amount of about 15 parts by weight or less with respect to 100 parts by weight of the total amount of monomers that can be used for oligomer synthesis, and may be 10 parts by weight or less, or It may be about 5 parts by weight or less. The lower limit of the use amount of the chain transfer agent relative to 100 parts by weight of the total amount of monomers that can be used for oligomer synthesis is not particularly limited, for example, it can be 0.01 part by weight or more, 0.1 part by weight or more, and 0.5 part by weight The above may be 1 part by weight or more.

In the aspect of using the additive (H _RO ) as the refractive index enhancer, the amount of the additive (H _RO ) to be used relative to 100 parts by weight of the base polymer (when using a plurality of compounds, the total amount of the same) is not particularly limited, It can be set according to the purpose. From the viewpoint of increasing the refractive index of the adhesive, the amount of the additive (H _RO ) used relative to 100 parts by weight of the base polymer can be, for example, 1 part by weight or more, and it is advantageous to set it as 3 parts by weight or more. It may be 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, and 20 parts by weight or more. In several aspects, the amount of the additive (H _RO ) to be used relative to 100 parts by weight of the base polymer can be, for example, 80 parts by weight or less, so as to achieve a balance between the high refractive index of the adhesive and the anti-adhesion properties or optical properties From the viewpoint of reduction, it is advantageous to be 60 parts by weight or less, and preferably 45 parts by weight or less. In several aspects where more emphasis is placed on adhesive properties or optical properties, the amount of additive (H _RO ) used relative to 100 parts by weight of the base polymer may be, for example, 30 parts by weight or less, 20 parts by weight or less, or 15 parts by weight. Below, it may be 10 parts by weight or less.

(Plasticizing Material) In several aspects, the high refractive index adhesive layer may comprise a plasticizing material having a lower molecular weight than the base polymer of the adhesive layer. By using a plasticized material, the flexibility of the high-refractive-index adhesive layer can be improved, thereby improving the adhesion to the adherend, the overall flexibility, and the followability to deformation. From the viewpoint of compatibility or transparency in the adhesive layer, an organic material can be suitably used as the plasticizing material. The plasticizing material may also be a material that can be used as the above-mentioned refractive index enhancer (eg, the above-mentioned additive (H _RO )).

The molecular weight of the plasticizing material may be lower than that of the base polymer, which is not particularly limited. In several aspects, the molecular weight of the plasticizing material may be less than 30,000, less than 25,000, less than 10,000, preferably less than 5,000, preferably less than 3,000 (eg, less than 1,000) from the viewpoint of easily exhibiting the plasticizing effect. , can be less than 800, can be less than 600, can be less than 500, can also be less than 400. The fact that the molecular weight of the plasticizing material is not too large is advantageous from the viewpoint of enhancing the compatibility in the adhesive layer. In addition, in several aspects, from the viewpoint of easily exerting a sufficient plasticizing effect, the molecular weight of the plasticizing material is preferably 130 or more, preferably 150 or more, more preferably 170 or more, and may be 200 or more , which can be more than 250 or more than 300. In several aspects, the molecular weight of the plasticizing material may be greater than 500, greater than or equal to 1000, or greater than or equal to 2000. The fact that the molecular weight of the plasticizing material is not too low is also desirable from the viewpoint of the heat resistance of the adhesive layer or the suppression of contamination by the adhesive.

Non-limiting examples of compounds that can be used as options for plasticizing materials include: compounds that can be used as monomers (m1) (such as (meth)acrylates with aromatic rings such as benzyl, phenoxy, naphthyl, etc., structural monomers, monomers having a dinaphthothiophene structure, monomers having a dibenzothiophene structure, etc.); oligomers containing compounds that can be used as monomers (m1) as monomer units; The compound used for the monomer (m1) is a compound having a structure in which a part having an ethylenically unsaturated group is removed and replaced with a hydrogen atom or a group without an ethylenically unsaturated group (for example, 3-phenoxybenzyl alcohol). From the viewpoint of improving flexibility, low Tg monomers such as n-butyl acrylate or 2-ethylhexyl Copolymerization. As the plasticizing material, well-known plasticizers (for example, phthalate-based, terephthalate-based, adipate-based, adipic acid-based polyester, ethylene benzoate, etc.) can also be used. etc.) one or more of them.

In several aspects, an organic material having a refractive index of about 1.50 or higher (preferably 1.53 or higher) may be suitably used as the plasticizing material. Specific examples of compounds that can be selected as plasticizing materials include: diethylene glycol dibenzoate (refractive index 1.55), dipropylene glycol dibenzoate (refractive index 1.54), 3-phenoxytoluene ( Refractive index 1.57), 3-ethylbiphenyl (refractive index 1.59), 3-methoxybiphenyl (refractive index 1.61), 4-methoxybiphenyl (refractive index 1.57), polyethylene glycol diphenylmethane Acid ester, 3-phenoxybenzyl alcohol (refractive index 1.59), triphenyl phosphate (refractive index 1.56), benzyl benzoate (refractive index 1.57), 4-(tertiary butyl)phenyldiphenyl Phosphate (refractive index 1.56), trimethylphenyl phosphate (refractive index 1.55), butyl benzyl phthalate (refractive index 1.54), methyl rosin (refractive index 1.53), alkyl benzyl phthalate Ester (refractive index 1.53), butyl (phenylsulfonyl)amine (refractive index 1.53), trimethyl trimellitate (refractive index 1.52), benzyl phthalate (refractive index 1.52), 2- Ethylhexyl diphenyl phosphate (refractive index 1.51), sham (2,4-di-tertiary butylphenyl) phosphite, etc., are not limited by these. From the viewpoint of refractive index and compatibility, for example, diethylene glycol dibenzoate can be suitably used. The upper limit of the refractive index of the plasticizing material is not particularly limited, and may be, for example, 3.00 or less. In some aspects, from the viewpoint of the ease of preparation of the adhesive composition or the compatibility in the adhesive, it is suitable that the refractive index of the plasticizing material is 2.50 or less, and 2.00 or less is advantageous. It may be 1.90 or less, may be 1.80 or less, or may be 1.70 or less. In addition, the refractive index of the plasticizing material was measured under the conditions of a measurement wavelength of 589 nm and a measurement temperature of 25° C. using an Abbe refractometer in the same manner as the refractive index of the monomer. When there is a nominal value of the refractive index at 25°C provided from the manufacturer or the like, the nominal value can be used.

In the aspect of using the plasticizing material, the amount of the plasticizing material to be used relative to 100 parts by weight of the base polymer is not particularly limited, and can be set according to the purpose. From the viewpoint of improving the plasticizing effect, the amount of plasticizing material used relative to 100 parts by weight of the base polymer can be, for example, 0.1 part by weight or more, or 0.5 part by weight or more, so as to obtain a higher plasticizing effect. From a viewpoint, it is preferably 1 part by weight or more, preferably 3 parts by weight or more, 5 parts by weight or more, 7 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, or It may be 20 parts by weight or more. In addition, from the viewpoint of balancing the high refractive index, transparency and plasticizing effect of the adhesive, the amount of plasticizing material used relative to 100 parts by weight of the base polymer is appropriate to be about 100 parts by weight or less. It is 80 parts by weight or less, preferably 60 parts by weight or less, 45 parts by weight or less, 35 parts by weight or less, or 25 parts by weight or less. In some aspects where more emphasis is placed on adhesive properties or optical properties, the amount of plasticizing material used relative to 100 parts by weight of the base polymer may be, for example, 15 parts by weight or less, 10 parts by weight or less, or 5 parts by weight. the following.

(leveler) In several aspects, the adhesive composition used to form the adhesive layer can be used to improve the appearance of the adhesive layer formed from the composition (for example, to improve the uniformity of thickness) or to improve the above-mentioned adhesive composition. Coating properties, etc., contain a leveling agent as required. Non-limiting examples of the leveling agent include acrylic leveling agents, fluorine-based leveling agents, polysiloxane-based leveling agents, and the like. The leveling agent can be appropriately selected from, for example, commercially available leveling agents, and can be used by an ordinary method.

In several aspects, the above-mentioned leveling agent can suitably use the following polymers (hereinafter also referred to as "polymer (B)"), which are monomers comprising a polyorganosiloxane skeleton (hereinafter also referred to as "monomers") S1") and a polymer of a monomer raw material of an acrylic monomer (hereinafter also referred to as "monomer raw material B"). The polymer (B) can be referred to as a copolymer of the monomer S1 and an acrylic monomer. The polymer (B) may be used alone or in combination of two or more.

The monomer S1 is not particularly limited, and any monomer containing a polyorganosiloxane skeleton can be used. Monomer S1 can be suitably used for a structure having a polymerizable reactive group at one end. Among them, one end having a polymerizable reactive group and the other end having no function for cross-linking reaction with the base polymer (eg, acrylic polymer) of the adhesive composition blended with the leveling agent can be suitably used Monomer S1 of the base structure. Commercially available products include, for example, terminal-reactive polysiloxane oil (for example, models such as X-22-174ASX, X-22-2426, X-22-2475, and KF-2012) manufactured by Shin-Etsu Chemical Co., Ltd. Monomer S1 may be used alone or in combination of two or more.

The functional group equivalent of the monomer S1 may be, for example, about 100 g/mol to 30000 g/mol. In several ideal aspects, the functional group equivalent weight may be, for example, 500 g/mol or more, 800 g/mol or more, 1500 g/mol or more, or 2000 g/mol or more. In addition, the functional group equivalent may be, for example, 20,000 g/mol or less, less than 10,000 g/mol, 7,000 g/mol or less, or 5,500 g/mol or less. If the functional group equivalent of the monomer S1 is within the above-mentioned range, it is easy to exhibit a good leveling effect. In addition, when two or more monomers with different functional group equivalents are used as the monomer S1, the functional group equivalent of the monomer S1 can be the sum of the products of the functional group equivalents of various monomers and the weight fraction of the monomer.

Here, "functional group equivalent" means the weight of the main skeleton (eg, polydimethylsiloxane) bonded to each functional group. The relevant labeling unit g/mol is converted into 1 mol of the functional group. The functional group equivalent of the monomer S1 can be ^{calculated, for example, from the spectral intensity of 1} H-NMR (proton NMR) by nuclear magnetic resonance (NMR). Functional group equivalent of the monomer is carried out according to the S1 ¹ H-NMR spectral intensity of (g / mol) is calculated, it can be resolved according to the relevant general ¹ H-NMR spectrum of the structure analysis method, and if necessary, refer to Japanese Patent No. 5951153 i.e. The records in the Bulletin No. In the functional group equivalent of the monomer S1, the above-mentioned functional group means a polymerizable functional group (for example, an ethylenically unsaturated group such as a (meth)acryloyl group, a vinyl group, and an allyl group).

The content of the monomer S1 in the monomer raw material B can adopt an appropriate value within the range in which the desired effect can be exhibited by using the monomer S1, and is not limited to a specific range. In several aspects, the content of the monomer S1 in the monomer raw material B may be, for example, 5 to 60 wt %, 10 to 50 wt %, or 15 to 40 wt %.

The monomer raw material B includes, in addition to the monomer S1, an acrylic monomer that can be copolymerized with the monomer S1. Thereby, the compatibility of the polymer (B) in the adhesive layer can be improved. Examples of acrylic monomers that can be used for the monomer raw material B include acrylic acid alkyl esters. The "alkyl group" referred to here means a chain (including linear and branched) alkyl groups (groups), and does not include the alicyclic hydrocarbon group described later. In several aspects, the monomer raw material B may contain a C _4-12 alkyl (meth)acrylate (preferably a C _4-10 alkyl (meth)acrylate, such as a C _{6- (meth)acrylate) 10} alkyl esters) at least one. In several other aspects, the monomer raw material B may contain a C _1-18 alkyl methacrylate (preferably a C _1-14 alkyl methacrylate, such as a C _1-10 alkyl (meth)acrylate) at least one of esters). The monomer raw material B may contain, for example, one or two or more selected from methyl methacrylate (MMA), n-butyl methacrylate (BMA) and 2-ethylhexyl methacrylate (2EHMA) as acrylic acid monomer.

Another example of the said acryl-type monomer is the (meth)acrylate which has an alicyclic hydrocarbon group. For example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentyl (meth)acrylate, 1-adamantyl (meth)acrylate can be used esters, etc. The (meth)acrylate which has an alicyclic hydrocarbon group may not be used.

The content of the (meth)acrylate having the above-mentioned alkyl (meth)acrylate and the above-mentioned alicyclic hydrocarbon group in the monomer raw material B may be, for example, 10% by weight or more and 95% by weight or less, and may be 20% by weight or more and 95% by weight or less, 30% by weight or more and 90% by weight or less, 40% by weight or more and 90% by weight or less, or 50% by weight or more and 85% by weight or less.

Other examples of the monomers that can be included in the monomer raw material B together with the monomer S1 include the carboxyl group-containing monomers, acid anhydride group-containing monomers, hydroxyl group-containing monomers, Epoxy group-containing monomers, cyano group-containing monomers, isocyanate group-containing monomers, amide group-containing monomers, monomers with nitrogen-containing rings, (meth)acrylate aminoalkyl esters, vinyl esters , vinyl ethers, olefins, (meth)acrylates with aromatic hydrocarbon groups, (meth)acrylates containing halogen atoms, etc.

The Mw of the polymer (B) may be, for example, 5,000 or more, preferably 10,000 or more, or 15,000 or more. Moreover, Mw of the polymer (B) may be, for example, 200,000 or less, preferably 100,000 or less, 50,000 or less, or 30,000 or less. By setting the Mw of the polymer (B) in an appropriate range, good compatibility and leveling properties can be exhibited.

The polymer (B) can be produced by polymerizing the above-mentioned monomers by known methods such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and photopolymerization, for example. In order to adjust the molecular weight of the polymer (B), a chain transfer agent can be used as required. Examples of the chain transfer agent used include compounds having mercapto groups such as tertiary dodecyl mercaptan, mercaptoethanol, and α-thioglycerol; thioglycolic acid esters such as thioglycolic acid and methyl thioglycolate ; α-methylstyrene dimer and so on. The usage-amount of a chain transfer agent is not specifically limited, It can set suitably so that the polymer (B) which has a desired molecular weight can be obtained. In several aspects, the chain transfer agent may be used in an amount of, for example, 0.1 to 5 parts by weight, 0.2 to 3 parts by weight, or 0.5 to 2 parts by weight relative to 100 parts by weight of the monomer.

The amount of the polymer (B) used relative to 100 parts by weight of the base polymer (eg, acrylic polymer) can be set to, for example, 0.001 part by weight or more, and from the viewpoint of obtaining a higher use effect, it can be set to 0.01 part by weight part or more, and may be 0.03 part by weight or more. Moreover, the usage-amount of the said polymer (B) may be, for example, 3 parts by weight or less, but from the viewpoint of reducing the influence on the refractive index, 1 part by weight or less is suitable, it may be 0.5 part by weight or less, or It may be 0.1 part by weight or less.

(Inorganic Particles) The technology disclosed herein can also be suitably implemented without substantially using inorganic particles as a refractive index enhancer. In particular, in several aspects, the use of inorganic particles as a refractive index enhancer is acceptable as long as the desired optical properties (total light transmittance, haze value) are satisfied without significantly impairing the properties as an adhesive. Examples of inorganic particles that can be used as a refractive index enhancer include titanium oxide (titania, TiO ₂ ), zirconia (zirconia, ZrO ₂ ), aluminum oxide, zinc oxide, tin oxide, copper oxide, barium titanate, Inorganic particles composed of inorganic oxides (specifically, metal oxides) such as niobium oxide (Nb ₂ O _{5 , etc.).} The average particle diameter of the above-mentioned inorganic particles (referring to the 50% volume average particle diameter obtained by the laser scattering diffraction method) can be selected from, for example, a range of about 10 nm to 100 nm. In addition, the refractive index of the inorganic particles is measured at a measurement wavelength of 589 nm and a measurement temperature of 23° C. using a commercially available spectroscopic ellipsometry for a single-layer film of the material constituting the inorganic particles (with a film thickness capable of measuring the refractive index). measured under the conditions. As the spectroscopic ellipsometer, for example, the product name "EC-400" (manufactured by JA. Woolam) or its equivalent can be used. When using inorganic particles as a refractive index enhancer, the amount used is preferably less than 5 parts by weight, preferably less than 1 part by weight, relative to 100 parts by weight of the base polymer. In the aspect of the use of additives (H _RO) of, the amount of the inorganic particles (weight basis) or less should be set to 2-fold amount of the additive (H _RO) of, and set to 1 times or less or 0.5 times or less than good.

(crosslinking agent) In the technique disclosed herein, the adhesive composition for forming the adhesive layer may contain a cross-linking agent as required in order to adjust the cohesive force of the adhesive and the like. The cross-linking agent can use isocyanate-based cross-linking agent, epoxy-based cross-linking agent, aziridine-based cross-linking agent, oxazoline-based cross-linking agent, melamine-based resin, metal chelate-based cross-linking agent, etc. Crosslinking agents well known in the art. Among them, an isocyanate-based crosslinking agent can be suitably used. As another example of a crosslinking agent, the monomer which has two or more ethylenically unsaturated groups in 1 molecule, that is, a polyfunctional monomer is mentioned. A crosslinking agent can be used individually by 1 type or in combination of 2 or more types.

As the isocyanate-based crosslinking agent, a bifunctional or more functional isocyanate compound can be used, and examples thereof include aliphatic polyisocyanates such as trimethylene diisocyanate, butylene diisocyanate, hexamethylene diisocyanate (HDI), and dimer acid diisocyanate. cyclopentylene diisocyanate, cyclohexylene diisocyanate, isophorone diisocyanate (IPDI), 1,3-bis(isocyanatomethyl)cyclohexane and other cycloaliphatic isocyanates; 2,4 -Aromatic isocyanates such as toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, and diphenyl diisocyanate (XDI); the isocyanate compounds are converted through allophanate bonds, diurea bonds, trimeric isocyanates Bond, uretdione bond, urea bond, carbodiimide bond, uretonimine bond, urethane bond, etc. modified polyisocyanates, etc. Examples of commercially available products include trade names TAKENATE 300S, TAKENATE 500, TAKENATE 600, TAKENATE D165N, TAKENATE D178N (above, manufactured by Takeda Pharmaceutical Co., Ltd.), Sumidur T80, Sumidur L, Desmodur N3400 (above, manufactured by Sumika Bayer Urethane Co., Ltd.) manufactured), Millionate MR, Millionate MT, Coronate L, Coronate HL, Coronate HX (above, manufactured by Tosoh Corporation), etc. An isocyanate compound can be used individually by 1 type or in combination of 2 or more types. A bifunctional isocyanate compound and a trifunctional or more isocyanate compound may be used in combination.

Examples of epoxy-based crosslinking agents include bisphenol A, epichlorohydrin-type epoxy-based resins, ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether, and glycerol diglycidyl ether. , glycerol triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N , N,N',N'-tetraglycidyl-diamine and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, etc. These can be used individually by 1 type or in combination of 2 or more types.

Examples of the polyfunctional monomer include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate. , Neopentaerythritol di(meth)acrylate, Neopentaerythritol di(meth)acrylate, Neotaerythritol tri(meth)acrylate, Dipivalerythritol hexa(meth)acrylate, Ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate base) acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate, divinylbenzene, bisphenoxyethanol, di(meth)acrylic acid Esters, bisphenol A di(meth)acrylate, epoxy acrylate, polyester acrylate, urethane acrylate, butyl glycol di(meth)acrylate, hexyl glycol di(meth)acrylate Acrylate etc. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

The use amount of the crosslinking agent (which may be a polyfunctional monomer) is not particularly limited, but can be, for example, in the range of about 0.001 parts by weight to 5.0 parts by weight with respect to 100 parts by weight of the base polymer. From the viewpoint of improving the flexibility of the adhesive, in several aspects, the use amount of the crosslinking agent relative to 100 parts by weight of the base polymer is preferably 3.0 parts by weight or less, more preferably 2.0 parts by weight or less, and can be 1.0 part by weight or less, 0.5 part by weight or less, or 0.2 part by weight or less. In addition, from the viewpoint of properly exerting the effect of the cross-linking agent, in several aspects, the amount of the cross-linking agent used relative to 100 parts by weight of the base polymer may be, for example, 0.005 part by weight or more, or 0.01 part by weight. The above may be 0.05 part by weight or more, or 0.08 part by weight or more.

In order to make the crosslinking reaction proceed more efficiently, a crosslinking catalyst may also be used. Examples of the crosslinking catalyst include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetraisopropyl titanate, iron(III) acetylacetonate, butyltin oxide, and dioctyltin dilaurate. Among them, tin-based cross-linking catalysts such as dioctyl tin dilaurate are preferred. The amount of the cross-linking catalyst used is not particularly limited. Taking into account the balance between the speed of the cross-linking reaction and the service life of the adhesive composition, the usage amount of the cross-linking catalyst relative to 100 parts by weight of the base polymer can be, for example, about 0.0001 part by weight or more and 1 part by weight or less. It is preferable to set it as the range of 0.001 weight part or more and 0.5 weight part or less.

The adhesive composition may contain a compound capable of generating keto-enol tautomerism as a crosslinking retarder. Thereby, the effect of extending the service life of the adhesive composition can be achieved. For example, a compound capable of generating keto-enol tautomerism can be suitably used in an adhesive composition containing an isocyanate-based crosslinking agent. Various β-dicarbonyl compounds can be used as compounds that can produce keto-enol tautomerism. For example, β-diketones (acetone acetone, 2,4-hexanedione, etc.) or acetoacetates (methyl acetoacetate, ethyl acetoacetate, etc.) can be suitably used. The compound which can generate keto-enol tautomerism can be used individually by 1 type or in combination of 2 or more types. The amount of the compound that can generate keto-enol tautomerism can be, for example, 0.1 part by weight or more and 20 parts by weight or less, or 0.5 part by weight or more and 10 parts by weight with respect to 100 parts by weight of the base polymer. Hereinafter, it may be 1 part by weight or more and 5 parts by weight or less.

(tackifier) Adhesive agents may also be included in the adhesive layer of the technology disclosed herein. The tackifier can be rosin tackifying resin, terpene tackifying resin, phenol tackifying resin, hydrocarbon tackifying resin, ketone tackifying resin, polyamide tackifying resin, epoxy tackifying resin, Known tackifying resins such as elastic system tackifying resins. These can be used individually by 1 type or in combination of 2 or more types. The amount of tackifier resin to be used is not particularly limited, and can be set so that appropriate adhesive performance can be exerted according to the purpose and application. In some aspects, from the viewpoint of refractive index or transparency, the amount of the tackifier used is appropriately 30 parts by weight or less, preferably 10 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer. The weight part or less is preferably 5 weight parts or less. The techniques disclosed herein may suitably be practiced without the use of tackifiers.

(other additives) In the technology disclosed herein, the adhesive composition for forming the adhesive layer may also contain plasticizers, softeners, colorants, antistatic agents, antiaging agents as required within the scope of not significantly hindering the effects of the present invention. Known additives that can be used for adhesive compositions such as additives, ultraviolet absorbers, antioxidants, light stabilizers, and preservatives. For the above-mentioned various additives, conventionally known ones can be used in accordance with a conventional method, and no particular feature is given to the present invention, so detailed descriptions are omitted.

(peel strength) In several aspects, the peel strength of the adhesive layer disclosed herein to the glass plate is suitably about 1.0N/25mm or more (eg, 1.5N/25mm or more), preferably 2N/25mm or more, preferably 3N /25mm or more, 4N/25mm or more, 6N/25mm or more, 8N/25mm or more, 10N/25mm or more, or 12N/25mm or more. The upper limit of the peel strength is not particularly limited, but may be, for example, 30 N/25 mm or less, 25 N/25 mm or less, or 20 N/25 mm or less.

Here, the above-mentioned peeling strength is obtained by the following method: press-bonding on an alkali glass plate as an adherend, leaving it for 30 minutes in an environment of 23° C. and 50% RH, and then putting it into a pressurized defoaming apparatus ( Autoclave) at a temperature of 50°C and a pressure of 0.5MPa for 30 minutes, and then placed in a gas environment of 23°C and 50% RH for 24 hours. 180° peeling was carried out under the condition of minutes, and the adhesion was measured. During the measurement, a suitable substrate (such as a polyethylene terephthalate (PET) film with a thickness of about 25µm to about 50µm) can be attached to the measurement object for reinforcement as required. More specifically, the peel strength can be measured according to the method described in the examples described later. When the high-refractive-index adhesive layer and the low-refractive-index adhesive layer disclosed herein are laminated to form a laminated sheet in the form of a double-sided adhesive sheet having a first adhesive surface and a second adhesive surface, in several aspects, the above The peel strength should be applied at least to the first adhesive surface (the one composed of the high-refractive-index adhesive layer), and more preferably applied to both the first and second adhesive surfaces. The peeling strength of the first adhesion facing the glass plate and the peeling strength of the second adhesion facing the glass may be the same or different.

<Low Refractive Index Layer> In the technology disclosed herein, the refractive index n _{2 of the} low refractive index layer (preferably the low refractive index adhesive layer) is preferably higher than the refractive index n _{1 of the} adhesive layer with lower refractive index. Thereby, the difference in refractive index between the high-refractive-index adhesive layer and the low-refractive-index layer can be used to control the behavior of light transmitted through the laminate including these layers. The refractive index n _{2 of the} low refractive index layer can be, for example, in the range of about 1.35 to 1.55. _{In several aspects, the refractive index n 2 of the} low-refractive index layer is, for example, from the viewpoint of increasing the refractive index difference with _{the refractive index n 1} of the high-refractive-index adhesive layer to easily improve the frontal brightness enhancement effect described later. It is preferably 1.49 or less, more preferably 1.47 or less (for example, 1.46 or less or 1.45 or less), and may be 1.43 or less, 1.41 or less, or 1.40 or less. In addition, in several aspects, the refractive index n _{2 of the} low-refractive index layer may be, for example, 1.36 or more, 1.38 or more, or 1.38 or more. 1.40 or more, or 1.42 or more.

In several aspects, the high refractive index n ₁ of the adhesive layer and the refractive index of the low refractive index layer ₂ ratio (n ₁ / n _2), for example, may be greater than 1.00 n, it may be about 1.01 or more, about 1.02 or more is suitable, and about 1.03 or more may be used. In several aspects, the ratio (n ₁ /n ₂ ) is advantageously greater than or equal to about 1.05, preferably greater than or equal to about 1.07, preferably greater than or equal to about 1.10, and may be greater than or equal to about 1.11. The upper limit of the ratio (n ₁ /n ₂ ) is not particularly limited. _{In several aspects, the ratio (n 1} /n ₂ ) may be, for example, about 1.20 or less, about 1.18 or less, about 1.16 or less, or about 1.14 or less, from the viewpoint of adhesion properties, transparency, and the like. , may be about 1.12 or less.

In several aspects, the high refractive index n ₁ of the adhesive layer and the refractive index difference between the low refractive index layer of n of _2, i.e., the refractive index difference (n ₁ -n _2), for example, may be greater than 0.00, may be It may be 0.01 or more, 0.02 or more, 0.03 or more, 0.05 or more, 0.10 or more, 0.15 or more, 0.20 or more, or 0.25 or more. The upper limit of the refractive index difference (n ₁ -n ₂ ) is not particularly limited. In several aspects, the refractive index (n ₁ -n ₂ ) may be, for example, 0.30 or less, 0.26 or less, 0.21 or less, 0.18 or less, or is 0.16 or less.

In several ideal conditions, the storage elastic modulus G' of the low-refractive index layer at 25°C (hereinafter referred to as "storage elastic modulus G' _V2 (25)") should be lower than that of the high-refractive index adhesive The storage elastic modulus G' of the agent layer at 25°C (storage elastic modulus G' _V1 (25)). That is, it is preferable that G' _V2 (25)<G' _V1 (25). According to the above configuration, by laminating a high refractive index adhesive and a low refractive index layer, adhesion or flexibility can be imparted, and the followability of height differences and the followability to curved surfaces can be improved, thereby realizing suitable application to various device designs. Laminated sheet (adhesive sheet) for use.

The storage elastic modulus G' _V2 (25) is not particularly limited, and may be, for example, in the range of 1.0 kPa to 500 kPa. From the viewpoint of the effect of enhancing the flexibility imparted by the low-refractive index layer or enhancing the followability to deformation, in several aspects, the storage elastic modulus G' _V2 (25) is appropriate to be 400 kPa or less, and It is preferably 300 kPa or less, more preferably 200 kPa or less (for example, 180 kPa or less or 150 kPa) or less, 120 kPa or less, 90 kPa or less, or 70 kPa or less. In addition, from the viewpoint of imparting appropriate cohesiveness to the low refractive index layer, in some aspects, the storage elastic modulus G' _V2 (25) is preferably 5.0 kPa or more, preferably 10 kPa or more, and may be 15 kPa The above may be 25 kPa or more, 35 kPa or more, 60 kPa or more, or 80 kPa or more. From the viewpoint of easiness to achieve higher cohesion force or adhesion properties, in several _{aspects, the storage elastic modulus G' V2} (25) may be 95 kPa or more, 110 kPa or more, or 140 kPa or more.

When the low-refractive index layer is an adhesive layer, the type of the adhesive constituting the adhesive layer is not particularly limited. The adhesive constituting the low-refractive index adhesive layer may include acrylic polymers, rubber-based polymers (such as natural rubber, synthetic rubber, mixtures thereof, etc.), polyester-based polymers that can be used in the field of adhesives , urethane polymer, polyether polymer, polysiloxane polymer, polyamide polymer, fluorine polymer, etc. various rubber-like polymers one or two or more as the base polymerized thing. From the viewpoints of adhesive performance, cost, and the like, an adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be suitably used. Among them, it is suitable to use an acrylic polymer as the adhesive (acrylic adhesive) of the base polymer. In the state where the high-refractive-index adhesive layer is an acrylic adhesive layer, from the viewpoint of the adhesion between the high-refractive-index adhesive layer and the low-refractive-index adhesive layer, a low-refractive-index adhesive layer can be suitably used It is the composition of the acrylic adhesive layer.

In several aspects, the above-mentioned acrylic polymer is preferably, for example, a polymer of the following monomer raw materials: including (meth)acrylic acid alkyl ester, and may also include copolymerization with the (meth)acrylic acid alkyl ester other monomers (comonomers). In the monomer raw material, the content of the above-mentioned alkyl (meth)acrylate may be, for example, 10% by weight or more, 25% by weight or more, 35% by weight or more, or 45% by weight or more. The above-mentioned acrylic polymer may be a polymer which contains an alkyl (meth)acrylate as a main monomer and further contains the above-mentioned copolymerizable monomer as a monomer component of a sub-monomer. Here, the main monomer means a component whose monomer composition accounts for more than 50% by weight in the above-mentioned monomer raw materials. The above monomer composition may be more than 55% by weight or more than 60% by weight of alkyl (meth)acrylate.

For the alkyl (meth)acrylate, a compound represented by the following formula (1) can be suitably used, for example. ^{_{CH 2 = C (R 1)}} COOR 2 (1) Here, in the above-described formula ⁽¹⁾ R 1 is a hydrogen atom or a methyl group. In addition, R ² is a chain alkyl group having 1 to 20 carbon atoms (hereinafter, the range of the carbon number may be represented as "C _1-20 "). From the viewpoint of the storage elastic modulus of the adhesive, etc., the alkyl (meth)acrylate ^{of which R 2} is a _{chain alkyl group of C 1-12} (eg C _2-10 , typically C _{4-8 )} better. The ^{alkyl (meth)acrylate in which R 2} is a C _1-20 chain alkyl group can be used alone or in combination of two or more. Preferred alkyl (meth)acrylates include n-butyl acrylate and 2-ethylhexyl acrylate.

The above-mentioned comonomers contribute to the introduction of the crosslinking point into the acrylic polymer or the improvement of the cohesive force of the acrylic polymer. As the above-mentioned copolymerizable monomer, for example, a carboxyl group-containing monomer, a hydroxyl group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amine group-containing monomer, a monomer having a nitrogen atom-containing ring, and a sulfonic acid group-containing monomer can be used. One or more of functional group-containing monomers such as monomers and phosphoric acid group-containing monomers. Other examples of the copolymerizable monomer include vinyl ester-based monomers such as vinyl acetate, aromatic vinyl compounds such as styrene, non-aromatic ring-containing (meth)acrylates, and alkoxy-containing monomers. Specific examples include the above-mentioned monomers that can be used as the base polymer of the high-refractive-index adhesive layer, but are not limited thereto. For example, from the viewpoint of improving the cohesive force, the copolymerizable monomer is preferably an acrylic polymer obtained by copolymerizing a carboxyl group-containing monomer and/or a hydroxyl group-containing monomer. Suitable examples of the carboxyl group-containing monomer include acrylic acid and methacrylic acid. Suitable examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate.

In several aspects, in order to lower the refractive index n _{2 of the} low refractive index layer, a fluorine-containing monomer can be used as the above-mentioned copolymerizable monomer. In the monomer raw material, the content of the fluorine-containing monomer may be, for example, 10% by weight or more, 25% by weight or more, or 35% by weight or more. From the viewpoint of easily realizing a low refractive index layer with a lower refractive index, the content of the above-mentioned fluorine-containing monomer is preferably 40% by weight or more, preferably 45% by weight or more, more preferably 55% by weight or more, and may be 60% by weight. The above may be 75% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The upper limit of the content of the fluorine-containing monomer in the monomer raw material is not particularly limited, and may be 100% by weight. In some aspects, from the viewpoint of cohesion of the low refractive index layer, etc., the content of the above-mentioned fluorine-containing monomer is suitably 99.9 wt % or less, and preferably 99.5 or less, may be 99 wt % or less, and may be It may be 97% by weight or less, and may be 92% by weight or less. A fluorine-containing monomer can be used individually by 1 type or in combination of 2 or more types.

As the fluorine-containing monomer, a fluorine-containing acrylic monomer can be suitably used. The fluorine-containing acrylic monomer is not particularly limited as long as it is an acrylic monomer having at least one fluorine atom in the molecule. For example, fluorine-containing (meth)acrylates can be suitably used. Suitable examples of fluorine-containing (meth)acrylates include those having a fluorinated hydrocarbon group at the end of the ester. As a fluorinated hydrocarbon group, a fluorinated aliphatic hydrocarbon group, a fluorinated alicyclic hydrocarbon group, a fluorinated aromatic hydrocarbon group, etc. are mentioned, for example. The fluorinated hydrocarbon group is preferably a fluorinated aliphatic hydrocarbon group. The fluorinated aliphatic hydrocarbon group includes a fluorinated alkyl group and the like. In the fluorinated aliphatic hydrocarbon group, the aliphatic hydrocarbon moiety may be linear or branched. Further, in the fluorinated aliphatic hydrocarbon group, a fluorine atom may be bonded to any carbon atom in the portion of the aliphatic hydrocarbon group. The number of fluorine atoms bonded to one carbon atom may be singular or plural. The number of carbon atoms to which fluorine atoms are bonded is not particularly limited.

In the fluorinated aliphatic hydrocarbon group (which in turn is a fluorinated alkyl group), the number of carbon atoms in the hydrocarbon group is not particularly limited. In several aspects, considering compatibility with other comonomers, a fluorinated aliphatic hydrocarbon group having a carbon number of, for example, about 1 to 18 (preferably 1 to 12) is preferable. Specific examples of the fluorinated aliphatic hydrocarbon group include fluorinated methyl groups such as trifluoromethyl, difluoromethyl, and monofluoromethyl; pentafluoroethyl, 1,1,2,2-tetrafluoroethyl, 1,1, 2,2,2-tetrafluoroethyl, 1,1,2-trifluoroethyl, 1,2,2-trifluoroethyl, 2,2,2-trifluoroethyl, 1,1-difluoro Fluorinated ethyl groups such as ethyl, 1,2-difluoroethyl, 2,2-difluoroethyl, 1-monofluoroethyl, 2-monofluoroethyl, and the like. The fluorinated alkyl group having 3 or more carbon atoms, like the fluorinated methyl group or fluorinated ethyl group exemplified above, can be exemplified by the single or plural number of fluorine atoms bonded to any one or more carbon atoms of the carbon atoms in the alkyl portion. of various fluorinated alkyl groups.

A fluorinated cycloalkyl group etc. are mentioned as a fluorinated alicyclic hydrocarbon group. Similar to the above-mentioned fluorinated aliphatic hydrocarbon group, in the fluorinated alicyclic hydrocarbon group, the fluorine atom may be bonded to any carbon atom of the alicyclic hydrocarbon group, and the fluorine atom bonded to one carbon atom may be Either singular or plural. Also, the number of carbon atoms to which fluorine atoms are bonded is not particularly limited. Fluorinated alicyclic hydrocarbon groups include, for example: 2-fluorocyclohexyl, 3-fluorocyclohexyl, 4-fluorocyclohexyl and other cyclohexyl groups having one fluorine atom; 2,4-difluorocyclohexyl, 2,6-difluorocyclohexyl Cyclohexyl having 2 fluorine atoms such as fluorocyclohexyl; cyclohexyl having 3 fluorine atoms such as 2,4,6-trifluorocyclohexyl and the like.

The fluorinated hydrocarbon group may have no substituent or may have a substituent. The substituent is not particularly limited, and examples thereof include a hydrocarbon group such as an alkyl group, an alkoxy group, a hydroxyl group, a carboxyl group, an amino group, a nitro group, a cyano group, a halogen atom, and the like. The substituents may be used alone or in combination of two or more.

Fluorine atom-containing (meth)acrylates [fluorinated (meth)acrylates] include, for example: fluorine atom-containing alkyl (meth)acrylates [fluorinated alkyl (meth)acrylates], fluorine-containing (meth)acrylates Atom-based cycloalkyl (meth)acrylate [fluorinated cycloalkyl (meth)acrylate], fluorine-containing aryl (meth)acrylate [fluorinated aryl (meth)acrylate], etc. .

The fluorine atom-containing (meth)acrylates are preferably fluorinated alkyl (meth)acrylates (especially fluorinated alkyl acrylates). Examples of fluorinated alkyl (meth)acrylates include 2,2,2-trifluoroethyl acrylate (trade name "Viscoat 3F" manufactured by Osaka Organic Chemical Industry Co., Ltd.), 2,2,3,3 - Tetrafluoropropyl acrylate (trade name "Viscoat 4F" manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1H,1H,5H-octafluoropentyl acrylate (trade name "Viscoat 4F" manufactured by Osaka Organic Chemical Industry Co., Ltd.) 8F”, etc.), 1H,1H,5H-octafluoropentyl methacrylate (trade name “Viscoat 8FM” manufactured by Osaka Organic Chemical Industry Co., Ltd., etc.), 2-(heptadecafluorononyl)ethyl acrylate (trade name "FA-108", etc., manufactured by Kyōeisha Chemical Co., Ltd.), 1H, 1H, 2H, 2H-tridecafluorooctyl acrylate (trade name "Viscoat 13F" manufactured by Osaka Organic Chemical Industry Co., Ltd., etc.) )Wait.

The number of carbon atoms of the fluorinated alkyl group in the fluorinated alkyl (meth)acrylate is advantageously 3 or more, preferably 4 or more, and preferably 5 or more, from the viewpoint of the effect of lowering the refractive index, flexibility, and the like. Good, more preferably 6 or more or 7 or more, especially 8 or more. From the viewpoint of adhesion performance and the like, the number of carbon atoms of the fluorinated alkyl group is preferably 18 or less, preferably 14 or less, more preferably 12 or less, and may be 10 or less, and may be 9 or less. In several aspects, the carbon number of the above-mentioned fluorinated alkyl group may be 7 or less, or 5 or less. In addition, in several aspects, the (meth)acrylate containing a fluorine atom is preferably a fluorinated alkyl (meth)acrylate in which fluorine is not bonded to the carbon at the 1-position of the alkyl group. For example, 1H can be suitably used. , 1H,2H,2H-tridecafluorooctyl acrylate fluorinated alkyl (meth)acrylate in which fluorine is not bonded to any one of the carbon at the 1-position and the carbon at the 2-position of the alkyl group.

In several aspects, the low refractive index layer is an acrylic adhesive layer and the acrylic polymer of the base polymer of the adhesive can be a polymer of the following monomer raw materials: comprising at least the fluorine-containing acrylic as described above Monomers (eg, fluorinated alkyl (meth)acrylates), and may further include other monomers (co-monomers) that are copolymerizable with the fluorine-containing acrylic monomers. The monomer raw material may or may not contain alkyl (meth)acrylate. In the above-mentioned monomer raw material, the content of the fluorine-containing acrylic monomer may be, for example, 10% by weight or more, 25% by weight or more, or 35% by weight or more. From the viewpoint of easily realizing a low refractive index layer with a lower refractive index, the content of the above-mentioned fluorine-containing acrylic monomer is preferably 40% by weight or more, preferably 45% by weight or more, more preferably 55% by weight or more, and may be 60% by weight or more. % by weight or more, 75% by weight or more, 85% by weight or more, 90% by weight or more, or 95% by weight or more. The upper limit of the content of the fluorine-containing acrylic monomer in the monomer raw material is not particularly limited, and may be 100% by weight. In some aspects, from the viewpoint of cohesion of the low refractive index layer, etc., the content of the fluorine-containing acrylic monomer is preferably 99.9 wt % or less, preferably 99.5 wt % or less, and may be 99 wt % or less , may be 97 wt % or less, or 92 wt % or less. The fluorine-containing acrylic monomers may be used alone or in combination of two or more.

The monomer raw material used to prepare the base polymer of the low-refractive index layer may be composed of a copolymerizable monomer in addition to a fluorine-containing acrylic monomer (eg, fluorinated alkyl (meth)acrylate). The above-mentioned copolymerizable monomers can be used, for example, carboxyl group-containing monomers, hydroxyl group-containing monomers, acid anhydride group-containing monomers, amide group-containing monomers, amine group-containing monomers, monomers having a nitrogen atom-containing ring (such as N-ethylene One or more of functional group-containing monomers such as N-vinyl cyclic amides such as yl-2-pyrrolidone), sulfonic acid group-containing monomers, and phosphoric acid group-containing monomers. Other examples of copolymerizable monomers include vinyl ester-based monomers such as vinyl acetate, aromatic vinyl compounds such as styrene, and non-aromatic compounds such as cycloalkyl (meth)acrylate and isobornyl (meth)acrylate. (meth)acrylates of family rings, alkoxy-containing monomers, etc. Specific examples include the above-mentioned monomers that can be used as the base polymer of the high-refractive-index adhesive layer, but are not limited thereto. For example, from the viewpoint of improving the cohesive force, the copolymerizable monomer is preferably an acrylic polymer obtained by copolymerizing a carboxyl group-containing monomer and/or a hydroxyl group-containing monomer.

In several ideal aspects, the monomer raw material used to modulate the base polymer of the low-refractive index layer may include fluorine-containing monomers (eg, fluorine-containing acrylic monomers such as fluorinated alkyl (meth)acrylates) And it also includes the composition of hydroxyl-containing monomers. Hydroxyl-containing monomers contribute to improving cohesion or introducing cross-linking points. Suitable examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. From the viewpoint of improving flexibility in the room temperature region, 4-hydroxybutyl acrylate can be more suitably used. The content of the hydroxyl group-containing monomer in the monomer raw material is not particularly limited, and may be, for example, 0.01% by weight or more (preferably 0.1% by weight or more, more preferably 0.5% by weight or more). In several aspects, the content of the hydroxyl group-containing monomer may be 0.7% by weight or more, 0.9% by weight or more, or 1.5% by weight or more of the monomer raw material. The upper limit of the content of the hydroxyl group-containing monomer is not particularly limited, but may be, for example, 15% by weight or less or 10% by weight or less. In several aspects, from the viewpoint of lowering the refractive index, it is appropriate that the content of the hydroxyl-containing monomer in the above-mentioned monomer raw material is less than 10% by weight, and preferably less than 5% by weight, and may be less than 3% by weight , may be less than 2.5% by weight or less than 1.5% by weight.

In several aspects, the content of the carboxyl group-containing monomer in the monomer raw material used to prepare the base polymer of the low refractive index layer is suitable from the viewpoint of inhibiting coloring or discoloration (eg, yellowing) of the low refractive index layer. Industry restrictions. The content of the carboxyl group-containing monomer in the above-mentioned monomer raw materials can be, for example, less than 1% by weight, preferably less than 0.5% by weight, preferably less than 0.3% by weight, more preferably less than 0.1% by weight (for example, less than 0.05% by weight). If the content of the carboxyl group-containing monomer is limited, from the viewpoint of suppressing corrosion of metal materials that can be in contact with or disposed adjacent to the low-refractive index layer (for example, metal wiring or metal films that may exist on the adherend) See also beneficial. The techniques disclosed herein can be suitably implemented in a state in which the above-mentioned monomer raw materials do not contain a carboxyl group-containing monomer. For the same reason, in several aspects, the monomer raw materials used to prepare the base polymer of the low refractive index layer have acidic functional groups (in addition to carboxyl groups, sulfonic acid groups, phosphoric acid groups, etc.) The content should be restricted. The content of the acid functional group-containing monomer in the monomer raw material of the aspect can be applied to the above-mentioned ideal content of the carboxyl group-containing monomer. The technology disclosed herein can be suitably implemented in the state in which the above-mentioned monomer raw materials do not contain an acid group-containing monomer (that is, in the state in which the base polymer of the low refractive index layer is acid-free).

The base polymer of the low-refractive index layer and the base polymer of the high-refractive index adhesive layer can be appropriately prepared by a known polymerization method. The weight-average molecular weight (Mw) of the base polymer is not particularly limited, and may be, for example, in the range of about 10×10 ⁴ to 500×10 ⁴ , and may also be in the range of about 20×10 ⁴ to 200×10 ⁴ . In some aspects, from the viewpoint of adhesion to the high-refractive-index adhesive layer, etc., the Mw of the base polymer of the low-refractive-index adhesive layer ^{is suitably 150×10 4} or less, and preferably 120 ×10 ⁴ or less (eg, 95 × 10 ⁴ or less) may be 75 × 10 ⁴ or less, 68 × 10 ⁴ or less, or 60 × 10 ⁴ or less. In addition, in some aspects, from the viewpoint of cohesiveness of the low-refractive index adhesive layer, etc., the Mw of the base polymer may be, for example, 30×10 ⁴ or more, 40×10 ⁴ or more, or 50 ×10 ⁴ or more. In order to adjust Mw, a chain transfer agent known in the past can be used as required.

Although not particularly limited, from the viewpoint of adhesion, the Tg of the base polymer (eg, acrylic polymer) of the low-refractive index layer is advantageously about 0°C or lower, and preferably about -5°C or lower (for example, Tg). below about -15°C or below -25°C). Furthermore, from the viewpoint of the cohesive force of the adhesive layer, the Tg of the base polymer of the low-refractive index layer is about -75°C or higher, and preferably about -70°C or higher (for example, -50°C or higher, and further -30°C). ℃ or higher). The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (ie, the kind of monomers used in synthesizing the polymer or the ratio of the amount used).

A known crosslinking agent can be used for the low refractive index layer. In addition, the low refractive index layer may contain other additives such as tackifiers. The cross-linking agent or tackifier can be appropriately selected from the same ones that can be used for the high-refractive-index adhesive layer, and an appropriate amount can be used.

In the aspect in which the adhesive composition for forming a low-refractive-index adhesive layer contains a crosslinking agent, as the crosslinking agent, for example, an isocyanate-based crosslinking agent can be suitably used. In some aspects, from the viewpoint of adhesion to the high-refractive-index adhesive layer, etc., the amount of the isocyanate-based crosslinking agent to be used may be, for example, less than 100 parts by weight of the base polymer of the above-mentioned adhesive composition. 0.5 parts by weight, may be less than 0.3 parts by weight, may be less than 0.2 parts by weight, and may also be less than 0.15 parts by weight. In addition, from the viewpoint of properly exerting the effect of the crosslinking agent, in several aspects, the amount of the isocyanate-based crosslinking agent used may be, for example, 0.005 parts by weight or more, or may be based on 100 parts by weight of the base polymer. It may be 0.01 part by weight or more, 0.05 part by weight or more, or 0.08 part by weight or more.

<Preparation of the adhesive layer> In the technology disclosed herein, the adhesive constituting the adhesive layer (which may be a high-refractive index adhesive layer and/or a low-refractive index layer; the same applies hereinafter) can be made of a solvent by drying, cross-linking, polymerization, cooling, etc. The adhesive formed by hardening the adhesive composition of the adhesive composition in the form of the type, active energy ray hardening type, water dispersion type, hot melt type, etc., can be the hardened product of the above-mentioned adhesive composition. The hardening means (for example, drying, cross-linking, polymerization, cooling, etc.) of the adhesive composition may be used only in one type, or two or more types may be used simultaneously or in multiple stages. In the case of solvent-based adhesive compositions, the composition can typically be dried (preferably further cross-linked) to form the adhesive. In the active-energy-ray-curable adhesive composition, the adhesive is typically formed by irradiating an active-energy ray to advance a polymerization reaction and/or a cross-linking reaction. When the active energy ray-curable adhesive composition must be dried, the active energy ray can be irradiated after drying.

The adhesive layer of the adhesive sheet in the technology disclosed herein can be formed by hardening the adhesive composition after imparting (eg, coating) the adhesive composition to an appropriate surface. The adhesive composition can be applied by, for example, a gravure roll coater, a reverse roll coater, a touch roll coater, a dip roll coater, a bar coater, a blade coater, a spray coater, and the like. cloth machine to implement.

The adhesive layer in the technology disclosed herein may be an adhesive layer with post-curing properties or an adhesive layer without post-curing properties. Here, the adhesive layer having post-curability refers to an adhesive layer that can be further hardened by irradiation of heat or active energy rays (eg, ultraviolet rays). Examples of the adhesive layer having post-curing properties include an adhesive layer having an unreacted ethylenically unsaturated group in a side chain of a base polymer, or an adhesive layer containing an unreacted polyfunctional monomer. In several aspects, the adhesive layer preferably does not have post-hardening properties. The adhesive layer without post-curing properties does not undergo dimensional changes accompanying the post-curing reaction (that is, the dimensional stability is good), so it is easy to suppress the warpage of the adhesive layer or the adherend to which the adhesive layer is attached. It is also advantageous from the viewpoint of suppressing the optical strain of the adhesive layer that dimensional changes caused by post-hardening (eg, hardening shrinkage) do not occur.

The thickness of the adhesive layer is not particularly limited, and can be, for example, 3 µm or more, and preferably 5 µm or more. With an adhesive layer with a thickness of 5µm or more, good adhesive properties can be easily obtained. In addition, the adhesive layer of the thickness can absorb the unevenness that may exist on the surface of the adherend, and is easily bonded to the adherend with good adhesion. From the viewpoint of preventing coloring or color unevenness caused by light interference, the thickness of the adhesive layer (eg, the thickness of the high-refractive-index adhesive layer) is preferably 5 µm or more. In several aspects, the thickness of the adhesive layer may be greater than 10µm, greater than 20µm, greater than or equal to 30µm, greater than or equal to 50µm, greater than or equal to 70µm, or greater than 85µm. Furthermore, in several aspects, the thickness of the adhesive layer may be, for example, 300 µm or less, 250 µm or less, 200 µm or less, 150 µm or less, or 120 µm or less. The fact that the thickness of the adhesive layer is not too large is advantageous from the viewpoint of thinning of the laminate or light-emitting device including the adhesive layer. For example, the technique disclosed here is suitable to be implemented in a state where the thickness of the adhesive layer is in the range of 3 µm to 200 µm (preferably 5 µm to 100 µm). In several aspects, the thickness of the adhesive layer described above can be applied to at least the thickness T _{1 of the} high refractive index adhesive layer. The thickness of the low refractive index layer of the adhesive agent can be selected from T ₂ in the same range. Regardless of whether it is an adhesive layer or not, the thickness of the above-mentioned adhesive layer can also be applied to the thickness T _{2 of the} low refractive index layer. The thickness of the high refractive index of the adhesive layer thickness T ₁ and T ₂ of the low refractive index layer may be the same level as, or different. The thickness of the high refractive index layer of the adhesive agent T ₁ and the thickness of the low refractive index layer ratio _{(T 1 / T 2) T} 2 of, for example, may be 0.1 or more, 0.3 or more, can be 0.5 or more, 0.8 or more, It is 1.2 or more, and may be 1.5 or more. Moreover, the said ratio (T ₁ /T ₂ ) may be, for example, 20 or less, 10 or less, 5 or less, or 3 or less. In several aspects, the above ratio (T ₁ /T ₂ ) may be less than 2, may be less than 1.5, or may be less than 1.

The method of obtaining a structure (laminated sheet) in which a high-refractive-index adhesive layer and a low-refractive-index layer (typically a low-refractive-index adhesive layer) are laminated can be used, for example: peeling off a release surface (such as a release liner) A high-refractive-index adhesive layer and a low-refractive-index layer are respectively formed on the surface), and the method of laminating them; the composition used to form the low-refractive-index layer is coated on the high-refractive-index adhesive layer and made The method of hardening, or conversely, the method of coating and hardening the adhesive composition for forming the high-refractive-index adhesive layer on the low-refractive index layer, etc., are not limited thereto. When laminating the pre-formed high-refractive-index adhesive layer and low-refractive index layer, a process for promoting the adhesion of the same layers can also be performed as required. For example, autoclave treatment, roll pressing treatment, etc. can be performed, but not limited thereto.

＜Supporting substrate＞ The high-refractive-index adhesive layer and the low-refractive index layer can also be laminated on one surface of the support substrate in sequence or in reverse order. For example, the composition of the high-refractive-index adhesive layer and the low-refractive-index layer laminated on the support substrate can also be regarded as a substrate-attached adhesive sheet. Therefore, according to this specification, there is provided an adhesive sheet (adhesive product) with a base material, which comprises: a laminate composed of a high-refractive-index adhesive layer and a low-refractive-index layer (preferably a low-refractive-index adhesive layer), and a support The supporting substrate of the laminated sheet.

The material of the supporting base material is not particularly limited, and can be appropriately selected according to the purpose of use, the state of use, and the like. Non-limiting examples of substrates that can be used include polyolefin films mainly composed of polyolefins such as polypropylene (PP) or ethylene-propylene copolymer, polyethylene terephthalate (PET), polyethylene terephthalate (PET), polyolefin films, etc. Polyester film mainly composed of polyester such as butylene terephthalate (PBT) and polyethylene naphthalate (PEN), and plastic film such as polyvinyl chloride film mainly composed of polyvinyl chloride; Foamed sheet composed of polyurethane foam, polyethylene (PE) foam, polychloroprene foam and other foams; various fibrous substances (can be natural fibers such as hemp, cotton, etc.) , polyester, vinylon and other synthetic fibers, acetate and other semi-synthetic fibers, etc.) woven and non-woven fabrics alone or blended; Japanese paper, Dowling paper, kraft paper, crepe paper and other papers; aluminum foil, copper foil etc. Metal foil etc. It can also be a base material composed of these composite materials. Examples of the composite base material include, for example, a base material with a structure in which a metal foil and the above-mentioned plastic film are laminated, a plastic base material reinforced with inorganic fibers such as glass cloth, and the like.

In several aspects, various film substrates can be suitably used. The above-mentioned film substrate can be a porous substrate such as a foamed film or a non-woven sheet, a non-porous substrate, or a structure in which a porous layer and a non-porous layer are laminated. substrate. In several aspects, as the above-mentioned film base material, a resin film containing an independent and shape-maintainable (self-supporting or non-dependent) resin film can be suitably used as a base film. Here, the "resin film" refers to a non-porous structure and is typically a resin film substantially free of bubbles (voids). Therefore, the above-mentioned resin film is a concept that can be distinguished from a foamed film or a nonwoven fabric. As the above-mentioned resin film, one that is independent and can maintain its shape (self-supporting or non-dependent) can be suitably used. The above-mentioned resin film may have a single-layer structure, or may have a multilayer structure of two or more layers (for example, a three-layer structure).

The material constituting the resin film may be, for example, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) as main components Polyester resins, polyolefin resins mainly composed of polyolefins such as polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, and ethylene-butene copolymer, and cellulose such as triacetate Resins, acetate-based resins, polyamide-based resins, polyether-based resins, polycarbonate-based resins, nylon 6, nylon 66, polyamide (PA)-based resins such as partially aromatic polyamides, polyamides Cyclic polyolefin resins such as amine (PI) resins, transparent polyimide resins, polyimide imide (PAI), polyether ether ketone (PEEK), polyether ether (PES), and norbornene-based resins , (meth)acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, ethylene-vinyl acetate copolymer resin, ethylene-vinyl alcohol copolymer Resin, polyarylate-based resin, polyphenylene sulfide (PPS)-based resin, polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), polytetrafluoroethylene (PTFE) or fluorinated poly Fluorine resins such as imide, etc.

The said resin film may be formed using the resin material which contains 1 type of the said resin independently, and may be formed using the resin material which mixed 2 or more types. The above-mentioned resin film may be unstretched or stretched (for example, uniaxially stretched or biaxially stretched). For example, PET film, PBT film, PEN film, non-stretch polypropylene (CPP) film, biaxially stretched polypropylene (OPP) film, low density polyethylene (LDPE) film, linear low density polyethylene ( LLDPE) film, PP/PE blend film, etc. From the viewpoint of strength or dimensional stability, examples of desirable resin films include PET films, PEN films, PPS films, and PEEK films. From the viewpoint of ease of acquisition, etc., PET films and PPS films are particularly suitable, and among them, PET films are more preferable.

In the resin film, light stabilizers, antioxidants, antistatic agents, colorants (dyes, pigments, etc.), fillers, slipping agents, Anti-blocking agent and other well-known additives. The blending amount of the additive is not particularly limited, and can be appropriately set according to the application of the adhesive sheet and the like.

The manufacturing method of a resin film is not specifically limited. For example, conventionally known general resin film forming methods, such as extrusion forming, air forming, T-die casting forming, and calender roll forming, can be suitably used.

The above-mentioned base material may be substantially constituted by the base film. Alternatively, the above-mentioned base material may include an auxiliary layer in addition to the above-mentioned base film. Examples of the above-mentioned auxiliary layers include optical property adjustment layers (eg, coloring layers, antireflection layers), printing layers or laminate layers for imparting a desired appearance to a substrate, antistatic layers, and primer layers. , peeling layer and other surface treatment layers.

In some aspects, a light-transmitting substrate (hereinafter also referred to as a light-transmitting substrate) can be suitably used as the support substrate. Thereby, the adhesive sheet with the light-transmitting base material can be formed. The total light transmittance of the light-transmitting substrate may be greater than 50%, for example, or may be greater than or equal to 70%. In several ideal aspects, the total light transmittance of the support substrate is above 80%, preferably above 90%, and may be above 95% (eg, 95-100%). The above-mentioned total light transmittance is measured using a commercially available transmittance meter according to JIS K 7136:2000. For the transmittance meter, the trade name "HAZEMETER HM-150" manufactured by Murakami Color Technology Laboratory or its equivalent can be used. As a suitable example of the said light-transmitting base material, the resin film which has light-transmitting property is mentioned. The said light-transmitting base material may be an optical film.

The thickness of the base material is not particularly limited, and can be selected according to the purpose of use or the state of use. The thickness of the base material may be, for example, 500 µm or less, but from the viewpoint of handling or workability, preferably 300 µm or less, 150 µm or less, 100 µm or less, 50 µm or less, 25 µm or less, or 10µm or less. When the thickness of the base material becomes smaller, the followability to the surface shape of the adherend tends to improve. In addition, from the viewpoints of handleability and workability, the thickness of the base material may be, for example, 2 µm or more, 10 µm or more, or 25 µm or more.

The side of the substrate on which the adhesive layer is to be laminated can also be subjected to corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and formation of a primer by coating a primer (primer). Conventionally known surface treatment such as coating. The surface treatment may be a treatment for improving the anchorage of the adhesive layer to the substrate. The composition of the primer for forming the primer layer is not particularly limited, and can be appropriately selected from known materials. The thickness of the primer layer is not particularly limited, and is usually about 0.01µm~1µm, and preferably about 0.1µm~1µm. Other treatments that can be performed on the substrate according to requirements include antistatic layer formation treatment, colored layer formation treatment, printing treatment, and the like. These treatments can be applied individually or in combination.

In the technology disclosed herein, when the high-refractive-index adhesive layer and the low-refractive-index layer constitute an adhesive sheet attached to a substrate, the thickness of the adhesive sheet may be, for example, 1000µm or less, 350µm or less, 200µm or less, or 120µm. Below, it may be 75 µm or less, or 50 µm or less. In addition, from the viewpoint of handling properties, the thickness of the adhesive sheet may be, for example, 10 µm or more, 25 µm or more, 80 µm or more, or 130 µm or more. In addition, the thickness of an adhesive sheet means the thickness of the part attached to the adherend. For example, in the double-sided pressure-sensitive adhesive sheet 2 without a base material shown in FIG. 2, it refers to the thickness from the first surface (first adhesive surface) 10A of the adhesive layer to the second surface (second adhesive surface) 10B , excluding the thickness of the release liners 31 and 32 .

<Laminated sheet with release liner> The high-refractive-index adhesive layer and the low-refractive-index layer disclosed herein may be released by making the adhesive surface of the laminate comprising the high-refractive-index adhesive layer and the low-refractive index layer abut against a release liner before being incorporated into the light-emitting device. The form of the adhesive product (laminated sheet with a release liner) in the form of the surface. Therefore, according to this specification, there is provided a laminated sheet (adhesive product) with a release liner, which comprises a laminated sheet of a high-refractive-index adhesive layer and a low-refractive-index layer, and a sheet having a release surface abutting against the adhesive surface of the laminated sheet. Release liner.

The release liner is not particularly limited, for example, a release liner with a release treatment layer on a release liner base material such as a resin film or paper (it can be a paper laminated with a resin such as polyethylene) can be used, or a release liner with a release treatment layer can be used. Release liners, etc., made of resin films made of low-adhesion materials such as fluorine-based polymers (polytetrafluoroethylene, etc.) or polyolefin-based resins (polyethylene, polypropylene, etc.). The said release treatment layer may be formed by surface-treating a release liner base material with a release treatment agent. The release treatment agent may be a known release treatment agent such as a polysiloxane-based release treatment agent, a long-chain alkyl-based release treatment agent, a fluorine-based release treatment agent, and molybdenum (IV) sulfide. In several aspects, a release liner having a release treatment layer obtained with a polysiloxane-based release treatment agent can be suitably used. The thickness and formation method of the release-treated layer are not particularly limited, and can be set so that appropriate release properties can be exhibited on the adhesive surface side surface of the release liner.

In some aspects, from the viewpoint of smoothness of the adhesive surface, etc., a release liner having a release treatment layer on a resin film (hereinafter also referred to as a release film base material) as a release liner base material can be suitably used (hereinafter also referred to as a release film). Various plastic films can be used for the release film substrate. In this specification, the so-called plastic film is typically a non-porous sheet, which is a concept that can be distinguished from non-woven fabrics (that is, non-woven fabrics are not included), for example.

The material of the plastic film can be, for example, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polyethylene terephthalate, etc. (PE), polypropylene (PP), polyolefin-based resins such as ethylene-propylene copolymers and ethylene-butene copolymers, cellulose resins such as cellulose triacetate, acetate-based resins, polysiloxane-based resins, and polyethers Cyclic polyolefin resins such as polyamide-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, norbornene-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, poly Vinylidene chloride based resin, polystyrene based resin, polyvinyl alcohol based resin, ethylene-vinyl acetate copolymer resin, ethylene-vinyl alcohol copolymer resin, polyarylate based resin, polyphenylene sulfide based resin, etc. . A release film substrate formed of any one of these resins or a mixture of two or more of these resins can also be used. Among them, a polyester-based resin film (for example, a PET film) formed of a polyester-based resin can be mentioned as a preferable release film substrate.

The plastic film that can be used as the base material of the peeling film can be any of a non-stretched film, a uniaxially stretched film, and a biaxially stretched film. In addition, the above-mentioned plastic film may be a single-layer structure, or may be a multi-layer structure including two or more sub-layers. The above plastic film can also be mixed with antioxidants, anti-aging agents, heat-resistant stabilizers, light stabilizers, ultraviolet absorbers, colorants such as pigments or dyes, lubricants, fillers, antistatic agents, nucleating agents, etc. A well-known additive that can be used for release film substrates of adhesive sheets. In the multi-layered plastic film, each additive can be mixed in all sub-layers, or only in a part of the sub-layers.

In several desirable aspects, the above-mentioned release film base material (typically a plastic film) can be suitably used in the layer on the release surface side of particles such as inorganic particles (for example, pigments, lubricants, fillers, etc.) can be used. The content is limited, or the particles are not substantially included. The term "substantially not included" here means that the amount of particles (eg, inorganic particles) in the layer is less than 1 wt %, and preferably less than 0.1 wt % (eg, 0-0.01 wt %). The peeling film provided with the peeling film base material tends to have the lower arithmetic mean roughness Ra or maximum height Rz of the peeling surface. When the above-mentioned release film substrate (typically a plastic film) has a multi-layer structure, the particle content in the layer on the release surface side may be 1/10 or less (for example, 1/50) of the particle content in the layers other than the release surface side layer. the following).

In the laminated sheet with a release liner in the form of a release liner having a release liner on each of the first adhesive surface and the second adhesive surface, the release liner (hereinafter, also referred to as one of the release liners) arranged on one of the adhesive surfaces ) and the release liner (hereinafter, also referred to as another release liner) disposed on the other adhesive surface may have the same material and structure, or may have different materials and structures.

The thickness of the release liner (preferably a release film) is not particularly limited, and may be, for example, about 10 µm to 500 µm. From the viewpoint of strength or dimensional stability of the release liner, the thickness of the release liner is suitably 20 µm or more, preferably 30 µm or more, may be 35 µm or more, 40 µm or more, or 45 µm or more. In addition, from the viewpoint of the properties of the release liner (such as ease of winding), the thickness of the release liner is appropriately 300 µm or less, and preferably 250 µm or less, may be 200 µm or less, may be 150 µm or less, or Can be 130µm or less. In several ideal aspects, the thickness of the release liner is about 125µm or less, it can be about 115µm or less, it can be about 105µm or less, it can be about 90µm or less, and it can also be about 70µm or less. By setting the thickness of the release liner to be less than a predetermined value, it is not easy to form a winding trace when it is made into a roll, and it can be removed from the adhesive sheet smoothly, so that the adhesive surface after the release liner is removed. It is easy to obtain a high surface smoothness. sex.

In the laminated sheet with a release liner having the form of one release liner and the other release liner, the thickness of these release liners may be the same or different from each other. In several aspects, from the viewpoint of release workability, etc., one release liner and the other release liner preferably have different thicknesses, for example, the thickness of the thicker release liner is preferably the thickness of the thinner release liner About 1.1 times or more of the thickness (for example, about 1.25 times or more; the upper limit is not particularly limited, for example, 5 times or less).

(Arithmetic mean roughness Ra of the adhesive side surface) In several aspects, the release liner (preferably a release film) from the viewpoint of achieving an adhesive surface with high surface smoothness, the arithmetic mean roughness Ra of the side surface of the adhesive surface is preferably limited to a predetermined value or less (eg about 100 nm or less, further less than 50 nm). In several aspects, the arithmetic mean roughness Ra of the adhesive side surface of the release liner is preferably about 30 nm or less, preferably about 25 nm or less, may be about 20 nm or less, or may be about 18 nm or less. In addition, from the viewpoint of the ease of manufacture and handling of the release liner, in some aspects, the arithmetic mean roughness Ra may be, for example, about 5 nm or more, about 10 nm or more, or about 15 nm or more. . In the laminated sheet with a release liner in which the release liner is arranged on the first adhesive surface and the second adhesive surface, respectively, the adhesive surface side surfaces of both release liners preferably satisfy any one of the above-mentioned arithmetic mean roughness Ra. The arithmetic mean roughness Ra of the adhesive surface side surfaces of the two release liners may be the same or different.

(Maximum height Rz of adhesive side surface) In several aspects, the release liner (preferably a release film) preferably has a maximum height Rz of 700 nm or less on the side surface of the adhesive surface from the viewpoint of realizing an adhesive surface with high surface smoothness. In several aspects, the maximum height Rz of the adhesive side surface of the release liner is preferably about 600 nm or less, may be about 500 nm or less, may be about 400 nm or less, and may be about 300 nm or less. Furthermore, from the viewpoints of ease of manufacture and handling of the release liner, in some aspects, the maximum height Rz may be, for example, about 50 nm or more, about 80 nm or more, about 100 nm or more, or about 100 nm or more. It is about 200 nm or more, and it may be about 300 nm or more. In the laminated sheet with a release liner in a form in which a release liner is arranged on the first and second adhesive surfaces, respectively, the adhesive surface side surfaces of both release liners preferably satisfy any one of the above-mentioned maximum heights Rz. The maximum height Rz of the side surfaces of the adhesive surfaces of the two release liners may be the same or different.

(surface properties on the back) The arithmetic mean roughness Ra or the maximum height Rz of the back surface (opposite to the adhesive layer side) of the release liner (preferably a release film) is not particularly limited. From the viewpoint of productivity and the like, the arithmetic mean roughness Ra of the back surface of the release liner may be, for example, larger than 30 nm (for example, larger than 35 nm, and further about 50 nm or more). From the viewpoint of productivity and the like, the maximum height Rz of the back surface of the release liner may be, for example, greater than 400 nm (eg, about 500 nm or more) or greater than 800 nm (eg, 1000 nm or more).

The arithmetic mean roughness Ra and the maximum height Rz of the surface of the peeling film can be adjusted by the selection of the film material, the forming method, the surface treatment such as peeling treatment, and the like. For example, the smoothness of the layer (anti-adhesion layer, hard coat layer, oligomer preventing layer, etc.) constituting the peelable surface can be adjusted, and the amount of filler particles in the surface layer or the substrate of the peeling film can be reduced or not used (no particles). ), and other adjustment extension conditions, etc.

The arithmetic mean roughness Ra and the maximum height Rz of the surface of the release liner (preferably a release film) are measured using a non-contact surface roughness measuring device. As the non-contact surface roughness measuring device, an optical interference method surface roughness measuring device can be used, for example, a three-dimensional optical profiler (trade name "NewView7300", manufactured by ZYGO Corporation) or its equivalent can be used. For example, a glass plate (a soda lime glass plate manufactured by Matsunami Co., Ltd., thickness 1.3 mm) can be attached to the surface opposite to the measurement surface of the release liner with an adhesive and fixed, using a 3-dimensional optical profiler (trade name "" NewView7300", manufactured by ZYGO Co., Ltd.), the surface shape was measured in an environment of 23°C and 50% RH.

<Application> In the technique disclosed herein, the high-refractive-index adhesive layer can be used by being bonded to various adherends constituting a light-emitting device. The constituent material of the above-mentioned adherend (the adherend material) is not particularly limited, for example, copper, silver, gold, iron, tin, palladium, aluminum, nickel, titanium, chromium, indium, zinc, etc. or including two or more metal materials such as alloys, or, for example, polyimide-based resins, acrylic resins, polyether nitrile-based resins, polyether-based resins, polyester-based resins (PET-based resins, polyethylene naphthalate resins) Diester-based resins, etc.), polyvinyl chloride-based resins, polyphenylene sulfide-based resins, polyetheretherketone-based resins, polyamide-based resins (so-called aramid resins, etc.), polyarylate-based resins, fluorine resins, polycarbonate resins, cellulose polymers such as cellulose diacetate or cellulose triacetate, vinyl butyral polymers, liquid crystal polymers, and carbon materials such as graphene (typically Plastic materials), aluminum oxide, zirconium oxide, titanium oxide, SiO ₂ , ITO (indium tin oxide), ATO (antimony doped tin oxide) and other metal oxides and their mixtures, aluminum nitride, silicon nitride, nitride Titanium, gallium nitride, indium nitride and other nitrides and their composites, alkali glass, alkali-free glass, quartz glass, borosilicate glass, sapphire glass carbon and other inorganic materials. The high-refractive-index adhesive layer disclosed herein can be used by being attached to a member (eg, an optical member) whose surface is made of the above-mentioned material at least. In addition, the low-refractive-index layer (preferably a low-refractive-index adhesive layer) in the technique disclosed here can be used by laminating (eg, laminating) on the above-mentioned various adherends.

The high-refractive-index adhesive layer disclosed here can be used in the following attaching state: after attaching to the adherend, it is not necessary to heat it to a temperature higher than room temperature (for example, 20°C to 35°C). The attached state of the temperature treatment. Moreover, in the case where it is permitted according to the type of the adherend, etc., the heat treatment may be performed at least at any time point after the adherend is pasted, at the time of the pasting, and before the pasting. The heat treatment can be performed for the purpose of improving the adhesion of the adhesive to the adherend or promoting adhesion. The heat treatment temperature can be appropriately set to obtain the desired effect in consideration of the surface state of the adherend, etc., within the allowable range according to the constituent material of the adhesive sheet or the type of the adherend. Below, it may be 80°C or lower, 60°C or lower, or 50°C or lower.

The member or material to which the adhesive layer is attached may be light-transmitting. For the adherend, it is easy to obtain the advantage that the high-refractive-index adhesive layer disclosed herein has high transparency. The total light transmittance of the adherend may be greater than 50%, for example, or may be greater than 70%. In several ideal forms, the total light transmittance of the adherend is above 80%, preferably above 90%, more preferably above 95% (eg, 95-100%). The high-refractive-index adhesive layer disclosed herein is preferably used in a state of being attached to an adherend (eg, an optical member) whose total light transmittance is equal to or greater than a predetermined value. The above-mentioned total light transmittance is measured using a commercially available transmittance meter according to JIS K 7136:2000. For the transmittance meter, the trade name "HAZEMETER HM-150" manufactured by Murakami Color Technology Laboratory or its equivalent can be used.

The refractive index of the adherend and the refractive index of the adhesive layer (high-refractive-index adhesive layer or low-refractive-index layer) disposed in contact with the adherend may be the same or different. For example, by making the refractive index of the adhesive layer relatively high relative to the refractive index of the adherend, the light incident on the adhesive layer at an angle below the critical angle from the adherend side can be refracted on the front side, increasing the frontal brightness. At this time, the refractive index of the adherend may be, for example, 1.55 or less, 1.50 or less, 1.48 or less, 1.45 or less, or less than 1.45, and, for example, may be 1.10 or more, 1.20 or more, 1.30 or more, or 1.35 or more. Moreover, by the adherend having a relatively high refractive index with respect to the adhesive layer, the light incident on the adherend from the adhesive layer side can be refracted on the front side, and the front brightness can be improved. At this time, the refractive index of the adherend may be, for example, 1.60 or more, 1.65 or more, or 1.70 or more, for example, 3.00 or less, 2.50 or less, or 2.00 or less. On the other hand, by narrowing the difference in refractive index between the adhesive layer and the adherend, light reflection at the interface can be suppressed. At this time, the refractive index of the adherend may be about 1.55 to 1.80, about 1.55 to 1.75, or about 1.60 to 1.70. The refractive index of the adherend can be measured in the same way as the refractive index of the adhesive.

In several ideal aspects, the adherend may have any of the above-mentioned refractive indices and any of the above-mentioned total light transmittances. In the light-emitting device in which the high-refractive index adhesive layer and/or the low-refractive index layer is attached or laminated to the adherend, the effects of the technology disclosed herein can be suitably exerted.

The high-refractive-index adhesive layer and the low-refractive index layer disclosed herein can be used by being attached to the above-mentioned various adherends in the form of a laminated sheet including the same. An example of a preferable application is an optical application. More specifically, for example, the laminated sheet disclosed herein can be suitably used for optical applications such as applications that can be used for bonding optical members (for optical member bonding) or production of products (optical products) using the above-mentioned optical members. adhesive sheet to use. The laminated sheet used in this aspect can also be regarded as an interlayer sheet arranged between layers of an optical laminated body.

The above-mentioned optical member refers to a member having optical properties (such as polarization, light refraction, light scattering, light reflectivity, light transmittance, light absorption, light diffraction, optical rotation, visual discrimination, etc.). The above-mentioned optical member is not particularly limited as long as it is a member having optical properties, and examples thereof include members constituting devices (optical devices) such as display devices (image display devices) and input devices, or members used in such devices, and examples include polarized light plate, wave plate, retardation plate, optical compensation film, brightness enhancement film, light guide plate, reflective film, anti-reflection film, hard coating (HC) film, shock absorption film, antifouling film, photochromic film, dimming film , transparent conductive film (ITO film), design film, decorative film, surface protection plate, lens, lens, color filter, transparent substrate, or further laminated components (these are sometimes collectively referred to as "" functional film”), etc. In addition, the above-mentioned "plate" and "film" are set to include forms such as plate, film, sheet, etc., for example, "polarizing film" is set to include "polarizing plate" or "polarizer", and "polarizing film" The "light guide plate" is set to include a "light guide film", a "light guide sheet", or the like. In addition, the above-mentioned "polarizing plate" is assumed to include a circular polarizing plate.

Examples of the display device include liquid crystal display devices, organic EL (electroluminescence) display devices, micro LEDs (µLEDs), mini LEDs (miniLEDs), PDPs (plasma display panels), electronic paper, and the like. Moreover, a touch panel etc. are mentioned as the said input device.

The said optical member is not specifically limited, For example, the member (for example, sheet-like, film-like, plate-like member) which consists of glass, acrylic resin, polycarbonate, polyethylene terephthalate, a metal thin film, etc. is mentioned. In addition, the "optical member" in this specification is also set to include a member (design film, decorative film, surface protection film, etc.) that performs a decorative or protective function while maintaining the visibility of a display device or an input device.

The high-refractive-index adhesive layer (which may be in the form of a laminated sheet with a low-refractive-index layer) disclosed herein can be disposed in, for example, one or more types of light transmission, reflection, diffusion, waveguide, condensing, diffraction, etc. It can be used in a state between an optical film such as a functional film or a fluorescent film and other optical members (which may be other optical films), and can be suitably used for bonding the above-mentioned optical film and the above-mentioned other optical members. Among them, in the bonding of optical films having at least one of the functions of waveguide, condensing, and diffracting light, the entire bonding layer should preferably have a high refractive index, which can be an ideal application object of the technology disclosed herein.

The high-refractive-index adhesive layer disclosed herein can be suitably used for bonding optical films such as light guide films, diffusion films, fluorescent films, toner films, wafers, lenticular films, and microlens array films. In these applications, reduction in thickness and improvement in light extraction efficiency are required from the viewpoint of the tendency of miniaturization of optical members or the improvement of performance. The high-refractive-index adhesive layer disclosed herein can be suitably utilized as an adhesive layer that can meet the requirements. In more detail, for example, in the case of bonding a light guide film or a diffusion film, it is possible to contribute to thinning by adjusting the refractive index (eg, increasing the refractive index) of the adhesive layer serving as the bonding layer. The bonding of the fluorescent films can improve the light extraction efficiency (also regarded as the luminous efficiency) by appropriately adjusting the refractive index difference between the fluorescent light-emitting body and the adhesive. In the bonding of the toner film, by appropriately adjusting the refractive index of the adhesive so that the difference in refractive index with the toner pigment becomes smaller, scattering components can be reduced, thereby contributing to the improvement of light transmittance. During the bonding of the wafer, the lenticular film, the microlens array film, etc., the diffraction of light can be controlled by appropriately adjusting the refractive index of the adhesive, which can help to improve the brightness and/or viewing angle.

The high-refractive-index adhesive layer disclosed herein (which can be in the form of a laminate with a low-refractive layer) can be suitably attached to a high-refractive-index adherend (which can be a high-refractive-index layer or member, etc.) In this case, the interface reflection with the above-mentioned adherend can be suppressed. The high-refractive-index adhesive layer that can be used in the above-mentioned form preferably has a small difference in refractive index with a high-refractive-index adherend and high adhesion at the interface with the adherend as described above. In addition, from the viewpoint of improving the uniformity of the appearance, the thickness of the adhesive layer should preferably be high in homogeneity, for example, the surface smoothness of the adhesive surface should be high. When the thickness of the adherend with high refractive index is small (for example, when it is 5µm or less, 4µm or less, or 2µm or less), from the viewpoint of suppressing coloring or color unevenness caused by the interference of reflected light, the reflection at the interface is suppressed. One thing is particularly meaningful. As an example of the use aspect, the following aspect can be mentioned: in a polarizing plate with a retardation layer including a polarizer, a first retardation layer, and a second retardation layer in sequence, the polarizer and the above-mentioned polarizer can be used. The bonding of the first retardation layer and/or the bonding of the first retardation layer and the second retardation layer.

In addition, the high-refractive-index adhesive layer disclosed here can be suitably used in the form of being attached to a light-emitting layer such as an optical semiconductor (eg, a high-refractive light-emitting layer mainly composed of an inorganic material). By narrowing the refractive index difference between the light-emitting layer and the high-refractive-index adhesive layer, the reflection at these interfaces can be suppressed, and the light extraction efficiency can be improved. In addition, from the viewpoint of preventing deterioration of the self-luminous element due to moisture in advance, the water absorption rate of the high-refractive-index adhesive layer is preferably low. From the viewpoint of improving brightness, the high-refractive-index adhesive layer is preferably low-colored. It is also advantageous from the viewpoint of suppressing unintentional coloring caused by the high-refractive-index adhesive layer.

The high-refractive-index adhesive layer disclosed herein can be suitably used in microlenses and other lens members used as constituent members of cameras, light-emitting devices, etc. (for example, lens members such as microlenses constituting microlens array films or microlenses for cameras). As a coating layer covering the lens surface, a bonding layer of a member facing the lens surface (for example, a member having a surface shape corresponding to the lens surface), a filling layer filled between the lens surface and the member, etc. use. Even if the high-refractive-index adhesive layer disclosed herein is disposed in contact with a high-refractive-index lens (for example, a lens made of a high-refractive-index resin, or a lens having a surface layer made of a high-refractive-index resin), it is possible to reduce and The refractive index difference of the lens. This is advantageous from the viewpoint of thinning of the above-mentioned lens and a product provided with the lens, and also contributes to suppressing aberrations and increasing the Abbe number. In the technique disclosed herein, the adhesive (viscoelastic material) constituting the high-refractive-index adhesive layer can also be used as a lens resin by itself, for example, in the form of filling in recesses or voids of a suitable transparent member.

Use the adhesive layer disclosed herein (the high-refractive-index adhesive layer and/or the low-refractive-index adhesive layer, and preferably the high-refractive-index adhesive layer that can also be laminated on the low-refractive index layer) to bond the optical member The form is not particularly limited, for example, the following forms can be used: (1) a form in which the optical members are bonded to each other through the adhesive layer disclosed herein; or (2) the optical member is attached to each other through the adhesive layer disclosed herein. A state of being attached to a member other than an optical member; (3) the adhesive layer disclosed herein may be in the form of an adhesive sheet including an optical member, and the adhesive sheet may be attached to an optical member or a member other than the optical member state. Moreover, in the aspect of said (3), the adhesive sheet of the form containing an optical member can be, for example, the adhesive sheet whose support body is an optical member (for example, an optical film). The adhesive sheet in the form including the optical member as a support as described above can also be regarded as an adhesive optical member (eg, an adhesive optical film). Also, when the adhesive layer disclosed herein constitutes an adhesive sheet of a type with a support and when the above-mentioned functional film is used as the above-mentioned support, the adhesive sheet can also be regarded as having at least one side of the functional film with the adhesive sheet disclosed herein. "Adhesive-type functional film" for the adhesive layer.

From the above, according to the technology disclosed herein, there is provided an optical laminate including the adhesive layer disclosed herein and a member (for example, a resin film such as an optical film) on which the adhesive layer is laminated by sticking or the like. The member on which the adhesive layer is laminated by sticking or the like may have the refractive index of the above-mentioned adherend material. In addition, the difference (refractive index difference) between the refractive index of the adhesive layer and the refractive index of the member may be the difference in refractive index between the adherend and the adhesive layer. The members constituting the laminate are described above with reference to the members, materials, and adherends, and therefore, the description will not be repeated.

As can be understood from the above description and the following examples, the matters disclosed by this specification include the following matters. [1] An adhesive sheet comprising an adhesive layer; and It has an adhesive surface formed by the above-mentioned adhesive layer; The refractive index of the above-mentioned adhesive layer is greater than 1.570, the total light transmittance is more than 86%, and the haze value is less than 3.0%. [2] The adhesive sheet according to the above [1], wherein the thickness of the above-mentioned adhesive layer is 5 µm or more. [3] The adhesive sheet according to the above [1] or [2], which has a peel strength (adhesive force) to a glass plate of 3 N/25 mm or more. [4] The adhesive sheet according to any one of the above [1] to [3], wherein the arithmetic mean roughness Ra of the adhesive surface is 100 nm or less. [5] The adhesive sheet according to any one of the above [1] to [4], wherein the water absorption rate of the adhesive layer is 1.0% or less. [6] The adhesive sheet according to any one of the above [1] to [5], which is constituted as a laminate including the above-mentioned adhesive layer and a light-transmitting base material. [7] The adhesive sheet according to the above [6], wherein the light-transmitting base material is a resin film. [8] The adhesive sheet according to any one of the above [1] to [5], which is a double-sided adhesive sheet composed of the above-mentioned adhesive layer. [9] An adhesive sheet with a release liner, comprising: The adhesive sheet according to any one of the above [1] to [8]; and A release liner arranged on the adhesive surface of the above-mentioned adhesive sheet. [10] An adhesive composition for forming an adhesive layer of the adhesive sheet according to any one of the above [1] to [8].

[11] An adhesive composition, comprising: an acrylic polymer (A) comprising an aromatic ring-containing monomer (m1) as a monomer unit; and an additive (H _RO ), the refractive index of which is higher than the above-mentioned acrylic polymer (A) higher organic material. [12] The adhesive composition of the above-mentioned [11], wherein _{the refractive index of the above-mentioned additive (H RO} ) is 1.60 or more. [13] The adhesive composition according to the above [11] or [12], wherein the content of the above-mentioned additive (H _RO ) relative to 100 parts by weight of the above-mentioned acrylic polymer (A) is greater than 0 parts by weight and not more than 60 parts by weight . [14] The adhesive composition according to any one of the above [11] to [13], wherein the additive (H _RO ) comprises at least one selected from the group consisting of an aromatic-ring-containing compound and a heterocyclic-containing compound 1 compound. [15] The adhesive composition according to any one of the above [11] to [14], wherein the additive (H _RO ) includes a compound having two or more aromatic rings in one molecule. [16] The adhesive composition according to the above [15], wherein the additive (H _RO ) contains a compound satisfying at least one of the following as the compound having two or more aromatic rings in one molecule: (i) Two or more aromatic rings are contained: A structure in which non-condensed aromatic rings are directly chemically bonded; and (ii) a structure in which two aromatic rings have been condensed. [17] The adhesive composition according to any one of the above [11] to [16], wherein in the monomer components constituting the above-mentioned acrylic polymer (A), the content of the above-mentioned aromatic ring-containing monomer (m1) is 50% by weight or more. [18] The adhesive composition according to any one of the above [11] to [17], wherein in the monomer components constituting the above-mentioned acrylic polymer (A), the content of the above-mentioned aromatic ring-containing monomer (m1) is greater than 70% by weight and less than 100% by weight, and 50% by weight or more of the above-mentioned aromatic ring-containing monomers (m1) are monomers whose glass transition temperature of the homopolymer is 10°C or lower. [19] The adhesive composition according to any one of the above [11] to [18], wherein the monomer component constituting the above-mentioned acrylic polymer (A) further contains a monomer (m2), and the monomer (m2) Has at least one of a hydroxyl group and a carboxyl group. [20] The adhesive composition according to any one of the above [11] to [18], which is used to form an adhesive layer of the adhesive sheet according to any one of the above [1] to [8]. [21] An adhesive comprising the adhesive composition according to any one of the above [11] to [20], and having a refractive index higher than 1.570. [22] An adhesive sheet comprising an adhesive layer composed of an adhesive, wherein the adhesive is formed from the adhesive composition according to any one of the above [11] to [20]. [23] The pressure-sensitive adhesive sheet according to the above-mentioned [22], wherein the haze value of the pressure-sensitive adhesive layer is 1.0% or less.

[24] An interlayer sheet that is used between layers of a laminate for optical purposes; and which comprises a _{viscoelastic layer V 1 having a refractive index n 1} of 1.570 or more, and satisfies: total light transmittance of 86% or more ; The haze value is below 1.0%; and the storage elastic modulus G' at 25°C is 30kPa~700kPa. [25] The thickness of the interlayer sheet in the above [24] is 5 µm or more. [26] The interlayer sheet according to the above [24] or [25], wherein the viscoelastic layer V ₁ comprises a main polymer and a plasticizing material with a lower molecular weight than the main polymer. [27] The interlayer sheet according to the above [26], wherein the weight average molecular weight of the plasticizing material is 30,000 or less. [28] The interlayer sheet according to any one of the above [24] to [27], further comprising a viscoelastic layer V _{2 laminated on the viscoelastic layer V 1} , and the viscoelastic layer V _{2 is} heated at 25° C. storage elastic modulus G _'V2 viscoelastic layer is less than the V ₁ stored at 25 deg.] C of the elastic modulus G' _V1. [29] As the inter [28] of the plies, wherein the refractive index of the viscoelastic layer of V ₂ n ₂ is less than the refractive index of the viscoelastic layer V ₁ n _1. [30] The interlayer sheet according to any one of the above [24] to [29], wherein the viscoelastic layer V ₁ is a layer formed of the adhesive composition according to any one of the above [11] to [18] . [31] The interlayer sheet according to any one of the above [24] to [29], wherein the viscoelastic layer V ₁ is the adhesive layer in the adhesive sheet according to any one of the above [1] to [5]. [32] An optical laminate comprising: the interlayer sheet according to any one of the above [24] to [31], and a resin film laminated on the interlayer sheet. [33] An interlayer sheet with a release liner, comprising: the interlayer sheet according to any one of the above [24] to [31], and a release liner covering at least one surface of the interlayer sheet.

[34] A light-emitting device, comprising: a self-luminous element; a low-refractive-index layer disposed on the viewing side of the self-luminous element; and a high-refractive-index adhesive layer, which is laminated in direct contact with the low-refractive index layer _{; The refractive index n 1 of} the high-refractive index adhesive layer is greater than 1.570, the total light transmittance is more than 86%, and the haze value is less than 3.0%. [35] As the above-mentioned [34] The light-emitting device, wherein the refractive index of the high refractive index layer of the adhesive agent and said refractive index n ₁ of the low refractive index layer ₂ ratio (n ₁ / n ₂₎ is 1.05 or more n. [36] The light-emitting device according to the above [35] or [36], wherein the arithmetic mean roughness Ra of the surface of the high refractive index adhesive layer is 100 nm or less. [37] As the above-mentioned [34] - [36] the light emitting device of any one of, wherein the thickness of the high refractive index layer of _an adhesive agent with a thickness ratio of the low refractive index layer is a T T ₂ (T ₁ / T ₂ ) is 0.5~5. [38] The light-emitting device according to any one of the above [34] to [37], wherein the thickness T ₁ of the high refractive index adhesive layer is 5 µm or more. [39] The light-emitting device according to any one of the above [34] to [38], wherein the total light transmittance of the laminate composed of the high-refractive-index adhesive layer and the low-refractive index layer is 86% or more, and The haze value is 3.0% or less. [40] The light-emitting device according to any one of the above [34] to [39], wherein the high refractive index adhesive layer is formed of the adhesive composition according to any one of the above [11] to [18] layer. [41] The light-emitting device according to any one of the above [34] to [40], wherein the high refractive index adhesive layer is the adhesive layer in the adhesive sheet according to any one of the above [1] to [5] .

[101] An adhesive, comprising an acrylic polymer (F), and the acrylic polymer (F) comprises a fluorine-containing acrylic monomer (M1) as a monomer unit; the refractive index of the adhesive is 1.46 Below, and its storage elastic modulus G' at 25 degreeC is 1.0 kPa or more and 400 kPa or less. [102] The adhesive according to the above [101], wherein in the monomer components constituting the acrylic polymer (F), the content of the fluorine-containing acrylic monomer (M1) is 25% by weight or more. [103] The adhesive according to the above [101] or [102], wherein the fluorine-containing acrylic monomer (M1) contains a fluorine atom-containing alkyl (meth)acrylate. [104] The adhesive according to any one of the above [101] to [103], wherein the aforementioned acrylic polymer (F) contains a hydroxyl group-containing monomer as a monomer unit. [105] A laminated sheet, comprising: a low-refractive-index adhesive layer formed by the adhesive according to any one of the above [101] to [104]; and a high-refractive index adhesive layer laminated on the aforementioned low-refractive adhesive layer agent layer. [106] The laminated sheet according to the above [105], wherein the ratio (n ₁ /n _{2 ) of the refractive index n 1} of the aforementioned high-refractive-index adhesive layer to the refractive index n ₂ of the aforementioned low-refractive-index adhesive layer (n 1 /n 2 ) is 1.02 or more . [107] The laminated sheet according to the above [105] or [106], wherein the refractive index n _{1 of the} high-refractive-index adhesive layer is greater than 1.570. [108] The laminated sheet according to any one of the above [105] to [107], wherein the storage elastic modulus G' of the high-refractive index adhesive layer at 25°C is 700 kPa or less. [109] The laminated sheet according to any one of the above [105] to [108], which has a total light transmittance of 86% or more and a haze value of 3.0% or less. [110] A light-emitting device, comprising: a self-luminous element and the laminated sheet according to any one of the above [105] to [109]; [111] The adhesive according to any one of the above [101] to [104], which is used for forming the viscoelastic layer V _{2 in the} interlayer sheet according to any one of the above [28] to [31]. [112] The adhesive according to any one of the above [101] to [104], which is used for forming the low refractive index layer in the light-emitting device according to any one of the above [34] to [41].

Example Hereinafter, several experiments related to the present invention will be described. In addition, in the following description, "parts" and "%" indicating the usage amount or content are based on weight unless otherwise specified.

<Preparation of Acrylic Adhesive Composition C1> Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction pipe, and a cooler, phenoxybenzyl acrylate (Kyoeisha Chemical Co., Ltd.) was introduced as a monomer component. Co., Ltd., trade name "LIGHT ACRYLATE POB-A", refractive index: 1.566, Tg of homopolymer: -35°C; hereinafter referred to as "POB-A") 95 parts and 4-hydroxybutyl acrylate (4HBA) 5 parts, 0.2 part of 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator, and 100 parts of toluene as a polymerization solvent, introduce nitrogen gas while stirring slowly, and keep the liquid temperature in the flask The polymerization reaction was performed at around 60° C. for 6 hours to prepare a solution (50%) of the acrylic polymer A1. The polymerization average molecular weight (Mw) of the acrylic polymer A1 was 500,000. In the above-mentioned acrylic polymer A1, Tg according to the composition of the monomer components (ie, Tg _T ) is -35°C, and Tg according to the composition of the aromatic ring-containing monomer (ie, Tg _m1 ) is -35°C. The solution of the above-mentioned acrylic polymer A1 (50%) was diluted to 30% with ethyl acetate, and 334 parts of the solution (100 parts of non-volatile components) was added as a crosslinking agent. Tris of hexamethylene diisocyanate. 10 parts of a 1% ethyl acetate solution (0.1 part of non-volatile content) of a polyisocyanate body (manufactured by Tosoh Corporation, trade name "Coronate HX", trifunctional isocyanate compound), 2 parts of acetylacetone as a crosslinking retarder, as 1 part of a 1% ethyl acetate solution (0.01 part of non-volatile content) of iron (III) acetoacetate as a crosslinking catalyst was mixed with stirring to prepare an acrylic adhesive composition C1.

<Preparation of acrylic adhesive composition C2> Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler, 72 parts of POB-A and 1-naphthyl methacrylate (manufactured by Kyōeisha Chemical Co., Ltd., commodity) were introduced as monomer components. Name "LIGHT ACRYLATE NMT-A", refractive index: 1.595, Tg of homopolymer: 31°C; hereinafter referred to as "NMT-A") 23 parts and 5 parts of 4HBA, 0.2 part of AIBN as a polymerization initiator, and Nitrogen gas was introduced into 100 parts of toluene as a polymerization solvent, and the liquid temperature in the flask was kept at around 60° C. for 6 hours to prepare a solution of acrylic polymer A2 (50%) for 6 hours. The polymerization average molecular weight (Mw) of the acrylic polymer A2 was 500,000. 20 parts of POB-A, 80 parts of NMT-A, 0.2 parts of AIBN as a polymerization initiator, and chain transfer as monomer components were put into a separable flask equipped with a thermometer, a stirrer, a reflux cooling tube, and a nitrogen introduction tube. After adding 3.5 parts of α-thioglycerol and 67 parts of methyl ethyl ketone, nitrogen gas was introduced, and nitrogen substitution was performed for about 1 hour while stirring. Then, the flask was heated to 70° C. and reacted for 12 hours to obtain an acrylic oligomer (oligomer B) having a weight average molecular weight (Mw) of 4000 and a refractive index of 1.63. The solution (50%) of the above-mentioned acrylic polymer A2 was diluted to 30% with ethyl acetate, and 20 parts of the oligomer B prepared above was added to 334 parts of the solution (100 parts of non-volatile components) as a crossover. 10 parts of 1% ethyl acetate solution (0.1 part of non-volatile content) of hexamethylene diisocyanate trimeric isocyanate (manufactured by Tosoh Corporation, trade name "Coronate HX", trifunctional isocyanate compound) as a linking agent 2 parts of acetone acetone as a linking retarder, 1 part of a 1% ethyl acetate solution of iron (III) acetoacetate as a cross-linking catalyst (0.01 part of non-volatile content) and stirred and mixed to prepare an acrylic adhesive composition Substance C2.

<Preparation of acrylic adhesive composition C3> 65 parts of 2-ethylhexyl acrylate, 1H,1H,5H-octafluoropentylacrylate (Osaka Organic Chemical Industry Co., Ltd., trade name: Viscoat 8F) 30 parts, N-vinyl-2-pyrrolidone (NVP, made by Nippon Shokubai) 3 parts and 4HBA 2 parts, AIBN as a polymerization initiator 0.2 parts and Nitrogen gas was introduced into 200 parts of ethyl acetate as a polymerization solvent, and the liquid temperature in the flask was kept at around 60° C. for 9 hours to carry out a polymerization reaction to prepare a solution (33%) of acrylic polymer A3. . The polymerization average molecular weight (Mw) of the said acrylic polymer A3 was 550,000. The solution (33%) of the above-mentioned acrylic polymer A3 was diluted to 30% with ethyl acetate, and a trimerization of hexamethylene diisocyanate as a crosslinking agent was added to 100 parts of non-volatile components (solid content). 10 parts of 1% ethyl acetate solution (0.1 part of non-volatile content) of isocyanate body (Tosoh company make, brand name "Coronate HX", trifunctional isocyanate compound) was stirred and mixed, and the acrylic adhesive composition C3 was prepared.

＜Production of adhesive sheet＞ (example 1) The acrylic adhesive composition C1 prepared above was coated on the polysiloxane-treated surface of the polyethylene terephthalate (PET) film R1 (thickness 50µm) treated with polysiloxane on one side. Heating at 130°C for 2 minutes forms an adhesive layer with a thickness of 25µm. The polysiloxane-treated side of the PET film R2 (thickness 38µm) that has been treated with polysiloxane on one side is pasted on the surface of the above-mentioned adhesive layer. In the above manner, an adhesive layer (high-refractive index adhesive layer) in a form in which both surfaces are protected by the PET films (release liner) R1 and R2 is obtained. Furthermore, release liner R2 is relatively light release compared to release liner R1. In addition, the acrylic adhesive composition C3 prepared above was coated on the polysiloxane-treated surface of the PET film R1 (thickness 50µm) treated with polysiloxane on one side, and heated at 130° C. for 2 minutes to form Adhesive layer with a thickness of 10µm. The polysiloxane-treated side of the PET film R2 (thickness 38µm) that has been treated with polysiloxane on one side is pasted on the surface of the above-mentioned adhesive layer. In the above-described manner, an adhesive layer (low-refractive index adhesive layer) in a form in which both surfaces are protected by the PET films (release liner) R1 and R2 is obtained. The release liner R2 was peeled off from the said high-refractive-index adhesive layer and the said low-refractive-index adhesive layer, the adhesive surfaces were bonded together, and it was press-bonded with a hand ink roller. This layered product was subjected to an autoclave treatment at 50°C and 0.60 MPa for 30 minutes, and then aged at 50°C for 48 hours. In the above-described manner, a laminated sheet (double-sided adhesive sheet without a base material) composed of a two-layer structure of a high-refractive-index adhesive layer/low-refractive-index adhesive layer was obtained. The surface of the adhesive sheet is protected by two release liners R1.

(Example 2) A high-refractive-index adhesive layer/low-refractive-index adhesive layer was obtained in the same manner as in Example 1, except that the type of adhesive composition used to form each adhesive layer and the thickness of each adhesive layer were changed as shown in Table 1. A laminated sheet composed of a two-layer structure of the adhesive layer (double-sided adhesive sheet without substrate).

(Examples 3~5) In the same manner as in Example 1, an adhesive layer of a single-layer structure composed of the acrylic adhesive compositions C1 to C3 and having the thickness shown in Table 1 was produced, and used as the adhesive sheets of Examples 3 to 5.

The obtained adhesive sheet was used for the following measurement and evaluation after fully adapting to the environment of 23 degreeC and 50%RH.

<Measurement and Evaluation (1)> (refractive index) For each adhesive layer, the refractive index was measured using an Abbe refractometer (manufactured by ATAGO CO., LTD., model "DR-M4") at a measurement wavelength of 589 nm and a measurement temperature of 25°C. The results are listed in Table 1.

(stored elastic modulus G') The thickness of each adhesive layer was about 1.5 mm, and it was used as a sample for measurement. Using ARES manufactured by TA Instruments, dynamic viscoelasticity was measured under the following conditions. The storage elastic modulus G' at 25°C was read from the measurement results. The results are listed in Table 1. [Measurement conditions] Deformation Mode: Twist Measurement frequency: 1Hz Heating rate: 5°C/min Shape: parallel plate 7.9mmφ

(Total light transmittance and haze value) Use the test piece in which the adhesive sheet of each example has been attached to alkali-free glass (thickness 0.8~1.0mm, total light transmittance 92%, haze 0.4%), and use a haze meter (manufactured by Murakami Color Institute, Trade name "HAZEMETER HM-150"), the total light transmittance and haze of the above-mentioned test piece were measured in a measurement environment of 23°C. The value obtained by subtracting the total light transmittance and haze of the above-mentioned alkali-free glass from the measured value was used as the total light transmittance and haze value of the adhesive sheet. The results are listed in Table 1.

(peel strength to glass plate) Under the measurement environment of 23°C and 50% RH, the release liner was peeled off from one side of the adhesive sheet of each example (in Examples 1 and 2, the surface of the adhesive layer formed of the adhesive composition C3), and After laminating a PET film with a thickness of 50µm as a substrate, it was cut into a size of 25mm in width and 100mm in length to form a test piece. The release liner on the other side was peeled off from the test piece, and a 2 kg roller was pressed to the surface of an alkali glass plate (manufactured by Matsunami Glass Industrial Co., Ltd., thickness 1.35 mm, cyan plate frosted product) as a to-be-adhered body by one reciprocation. It was placed in this environment for 30 minutes, then put into a pressurized defoaming device (autoclave), and subjected to autoclave treatment for 30 minutes at a temperature of 50°C and a pressure of 0.5MPa, and then at 23°C and 50% RH. After being placed in a gas environment for 24 hours, use a universal tensile and compression tester to measure the peel strength (adhesion) [N/25mm] under the conditions of a tensile speed of 300mm/min and a peel angle of 180 degrees in accordance with JIS Z 0237:2000. . The universal tensile and compressive testing machine used "Tensile Compression Testing Machine, TG-1kN" manufactured by Minebea Corporation.

[Table 1]

As shown in Table 1, the adhesive sheets of Examples 1 to 4 include an _{adhesive layer V1 (high refractive index adhesive layer) with a refractive index n V1} higher than 1.570, and exhibit high transparency in the adhesive sheets. These adhesive sheets exhibit practical peel strength suitable for bonding of optical members.

＜Evaluation of frontal brightness enhancement effect＞ The adhesive sheet of each example was attached to the white LED light source, and the light source was turned on for more than 30 minutes in a dark room to stabilize it. The frontal brightness of the part of the film. Using the average value of the brightness measured three times, the brightness of the light source without the adhesive sheet with a brightness improvement effect of more than 10% was evaluated as G (good), and the brightness improvement by less than 10% was evaluated as P (poor). ). The results are listed in Table 2.

[Table 2]

As shown in Table 2, the adhesive sheets of Examples 1 and 2 according to the adhesive layer of the laminated structure formed by combining the adhesive layer of Example 5 with a low refractive index and the adhesive layers of Examples 3 and 4 with a high refractive index ( Laminated sheet), compared to the case where the adhesive sheet was not used, a positive brightness improvement effect of more than 10% was confirmed. In the adhesive sheets of Examples 3 to 5 in which the adhesive layer of the adhesive sheet has a single-layer structure, the effect of improving the front brightness brought by the adhesive sheet alone was not confirmed.

<Preparation of acrylic adhesive composition C4> In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube and a cooler, 79 parts of POB-A, 20 parts of n-butyl acrylate, 1 part of 4HBA, and AIBN 0.2 as a polymerization initiator were fed as monomer components. 100 parts of toluene as a polymerization solvent, nitrogen was introduced while stirring slowly, and the liquid temperature in the flask was maintained at around 60° C. for 6 hours to carry out a polymerization reaction to prepare a solution of acrylic polymer A4 (50%) . The Mw of the acrylic polymer A4 was 520,000. The solution (50%) of the above-mentioned acrylic polymer A4 was diluted with ethyl acetate to 30%, and 1% ethyl acetate of Coronate HX as a cross-linking agent was added to 334 parts of the solution (100 parts of non-volatile components). 10 parts of solution (0.1 part of non-volatile content), 2 parts of acetoacetone as cross-linking retarder, 1 part of 1% ethyl acetate solution of iron (III) acetoacetate as cross-linking catalyst (0.01 part of non-volatile content) parts) and stirring and mixing to prepare acrylic adhesive composition C4.

<Preparation of acrylic adhesive composition C5> The preparation of the solution of the acrylic polymer A4 is the same as the preparation of the solution of the acrylic polymer A4, except that the composition (weight ratio) of the monomer components is changed to POB-A/ethylcarbitol acrylate (CBA)/4HBA=79/20/1 In this manner, a solution (50%) of the acrylic polymer A5 was prepared. The Mw of the acrylic polymer A5 was 460,000. An acrylic adhesive composition C5 was prepared in the same manner as the preparation of the acrylic adhesive composition C4, except that the solution of the acrylic polymer A5 was used instead of the solution of the acrylic polymer A4.

<Preparation of Acrylic Adhesive Composition C6> Except that the composition (weight ratio) of the monomer components was changed to P2H-A/4HBA=99/1, the same procedure as the preparation of the solution of the acrylic polymer A4 was carried out, A solution (50%) of acrylic polymer A6 was prepared. "P2H-A" in the composition of the above monomer components means phenoxydiethylene glycol acrylate (manufactured by Kyōeisha Chemical Co., Ltd., trade name "LIGHT ACRYLATE P2H-A", refractive index: 1.510, homopolymer Tg: -35°C). The Mw of the acrylic polymer A6 was 1 million. The solution (50%) of an acrylic polymer A6 diluted with ethyl acetate to 30%, and adding 6-ethyl acrylate as an additive (H _RO) to the solution of 334 parts (100 parts of non-volatile components) in the - Dinaphtho[2,1-b:1',2'-d]thiophene (6-acrylooxyethyl dinaphthothiophene manufactured by SUGAI Chemical Industry Co., Ltd., code name: 6EDNTA, refractive index: 1.722) 20 10 parts of 1% ethyl acetate solution of Coronate HX as a cross-linking agent (0.1 part of non-volatile content), 2 parts of acetoacetone as a cross-linking retarder, iron (III) acetoacetone as a cross-linking catalyst ) to 1 part of 1% ethyl acetate solution (0.01 part of non-volatile content) and mixed with stirring to prepare acrylic adhesive composition C6.

<Preparation of acrylic adhesive composition C7> Except for changing the composition (weight ratio) of the monomer components to 2EHA/Viscoat 13F/4HBA=49/50/1, in the same manner as the preparation of the solution of the acrylic polymer A3, the acrylic polymer A7 was prepared. solution (50%). "Viscoat 13F" in the composition of the above-mentioned monomer components represents 1H,1H,2H,2H-tridecafluorooctylacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name "Viscoat 13F"). The Mw of the acrylic polymer A7 was 550,000. An acrylic adhesive composition C7 was prepared in the same manner as the preparation of the acrylic adhesive composition C3, except that the solution of the acrylic polymer A7 was used instead of the solution of the acrylic polymer A3.

＜Production of adhesive sheet＞ (Examples 6~8) A high-refractive-index adhesive layer/low-refractive-index adhesive layer was obtained in the same manner as in Example 1, except that the types of adhesive compositions used to form each adhesive layer and the thickness of each adhesive layer were shown in Table 3. A laminated sheet composed of a two-layer structure of the agent layer (a double-sided adhesive sheet without a base material).

After fully adapting the adhesive sheets obtained in Examples 6 to 8 to an environment of 23° C. and 50% RH, the measurement and evaluation of each item were performed in the same manner as in the above-mentioned “measurement and evaluation (1)”. The results are listed in Table 3.

[table 3]

As shown in Table 3, the adhesive sheets of Examples 6 to 8 exhibited high transparency in the laminated structure of the adhesive layer (high-refractive-index adhesive layer) with a _{refractive index n 1 higher than 1.570 and the low-refractive-index layer.} These adhesive sheets exhibit practical peel strength suitable for bonding of optical members.

The specific examples of the present invention have been described in detail above, but these are only examples and do not limit the scope of the patent application. The technology described in the scope of claims includes the specific examples exemplified above through various modifications and changes.

2: Double-sided adhesive sheet without substrate 10: Laminate sheet (adhesive sheet) 10A: 1st surface (1st adhesive surface) 10B: Second surface (second adhesive surface) 11: High refractive index adhesive layer 12: Low refractive index adhesive layer (low refractive index layer) 31, 32: Release liner 70: Self-luminous element 80: Covering Window Components 100: Lighting device

FIG. 1 is a cross-sectional view schematically showing the structure of a light-emitting device according to an embodiment. FIG. 2 is a cross-sectional view schematically showing the constitution of a laminated sheet used in a light-emitting device of an embodiment.

2: Double-sided adhesive sheet without substrate

10: Laminate sheet (adhesive sheet)

10A: 1st surface (1st adhesive surface)

10B: Second surface (second adhesive surface)

11: High refractive index adhesive layer

12: Low refractive index adhesive layer (low refractive index layer)

70: Self-luminous element

80: Covering Window Components

100: Lighting device

Claims (6)

A light-emitting device, comprising: a self-luminous element; a low-refractive-index layer, which is disposed on the viewing side of the self-luminous element; and a high-refractive-index adhesive layer, which is laminated in direct contact with the low-refractive index layer; _{The refractive index n 1} of the refractive index adhesive layer is greater than 1.570, the total light transmittance is more than 86%, and the haze value is less than 3.0%. The light-emitting device of claim 1, wherein the ratio (n ₁ /n _{2 ) of the refractive index n 1 of the high-refractive-index adhesive layer to the refractive index n 2} of the low-refractive index layer is 1.05 or more. The light-emitting device according to claim 1 or 2, wherein the arithmetic mean roughness Ra of the surface of the high-refractive-index adhesive layer is 100 nm or less. The requested item light-emitting device according to any one of 1 to 3, wherein the thickness of the high refractive index layer of the adhesive agent T ₁ and the ratio of the low refractive index layer is T ₂ (T ₁ / T ₂₎ from 0.5 to 5. The light-emitting device according to any one of claims 1 to 4, wherein the thickness T ₁ of the high-refractive-index adhesive layer is 5 µm or more. The light-emitting device according to any one of claims 1 to 5, wherein the total light transmittance of the laminate composed of the high-refractive-index adhesive layer and the low-refractive index layer is 86% or more, and the haze value is 3.0% the following.

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