Optical Adhesive Composition and Optical Laminate

Abstract

To provide an optical adhesive composition and an optical laminate appropriate for manufacturing a self-luminous type display device such as a mini / micro LED display device with improved antireflection function of metal wiring and contrast, and excellent in step absorbency and processability.SOLUTION: A optical adhesive composition includes a (meth)acrylic block copolymer and a coloring agent. The (meth)acrylic block copolymer includes a high Tg segment having glass-transition temperature of 0 to 100°C, and a low Tg segment having glass-transition temperature of -100°C or higher and lower than 0°C, having a peak of tanδ in an area of 0°C or higher and an area lower than 0°C, respectively. Here, the glass-transition temperature is calculated with FOX equation from a monomer component composition composing each segment. An optical laminate includes a substrate and an adhesive layer formed with the optical adhesive composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an optical adhesive composition and an optical laminate suitable for encapsulating light-emitting elements of self-emitting display devices such as mini / micro LEDs.

Background Art

[0002] In recent years, as a next-generation display device, a self-emitting display device typified by a mini / micro LED display device (Mini / Micro Light Emitting Diode Display) has been devised. In the mini / micro LED display device, as a basic configuration, a substrate on which a large number of minute LED light-emitting elements (LED chips) are arranged densely is used as a display panel, the LED chips are encapsulated with a sealing material, and a cover member such as a resin film or a glass plate is laminated on the outermost layer.

[0003] There are several methods for self-emitting display devices such as mini / micro LED display devices, such as a white backlight method, a white light-emitting color filter method, and an RGB method. In the white light-emitting color filter method and the RGB method, a black sealing material may be used for antireflection of metal wirings and metal oxides such as ITO arranged on the substrate of the display panel (see, for example, Patent Documents 1 to 3). Among them, in the RGB-type mini / micro LED display device in which LED chips are arranged, the black sealing material can also contribute to preventing color mixing of RGB and improving contrast.

[0004] As the black sealing material, a liquid curable resin containing a black colorant (dye or pigment) is used. When using a liquid curable resin containing a black colorant, there is a problem that unevenness in blackness occurs due to uneven thickness. Also, since pigments are often selected because they are superior to dyes in both heat resistance and weather resistance, when using a liquid curable resin in which pigments are dispersed, in addition to the above-mentioned uneven thickness, problems such as uneven filling during filling of the liquid curable resin and uneven dispersion of pigments during flow also occur. Further, since there is no adhesion on the surface of the liquid curable resin cured after sealing, there is also a problem that it is necessary to laminate a cover member using an adhesive or the like, resulting in additional man-hours and components.

[0005] To address problems such as unevenness in blackness, the use of an adhesive containing a black colorant is considered. Since adhesives have lower fluidity than liquid curable resins, unevenness due to thickness, dispersion, and sedimentation of pigments is less likely to occur. Also, since the adhesive force is maintained even after sealing the LED chip, there is an advantage that it is not necessary to use an adhesive or the like to laminate the cover member, and man-hours and components can be simplified.

[0006] On the other hand, in mini / micro LED display devices, LED chips are densely laid on a substrate, and there are many fine steps in the gaps between the LED chips. Therefore, the sealing material used for mini / micro LED display devices is required to have the performance of filling steps, that is, excellent step absorption (also referred to as "step following"). In order to improve the above-mentioned step absorption, a method of reducing the elastic modulus of the adhesive to improve flexibility has been attempted (for example, Patent Document 4).

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] Although the pressure-sensitive adhesive with a low elastic modulus is excellent in step absorption, there is a problem that the processability such as shape stability and handleability deteriorates. For example, a laminate having a pressure-sensitive adhesive layer with a low elastic modulus is likely to have glue shortage during cutting, and the pressure-sensitive adhesive layer is likely to protrude or sag from the end during storage, and foreign matter may adhere to the protruding pressure-sensitive adhesive layer.

[0009] As a pressure-sensitive adhesive that achieves both the above-mentioned step absorption and processability, a hybrid pressure-sensitive adhesive is used. A hybrid pressure-sensitive adhesive is a pressure-sensitive adhesive that is formulated with two types of polymerization initiators and crosslinking agents having different curing start conditions and cures step by step. In the hybrid pressure-sensitive adhesive, first, it has a high fluidity and is in a semi-cured state excellent in step absorption, so that it can sufficiently follow the steps, and then the curing is completed, which has the advantage of improving the processability. However, the pressure-sensitive adhesive in the semi-cured stage excellent in step absorption has low processability and has problems in handleability in the process before final curing.

[0010] The present invention has been conceived under the above circumstances, and the object of the present invention is to be suitable for manufacturing a self-luminous display device such as an anti-reflection function for metal wiring and a mini / micro LED display device with improved contrast, and to provide an optical pressure-sensitive adhesive composition excellent in step absorption and processability. Another object of the present invention is to be suitable for manufacturing a self-luminous display device such as an anti-reflection function for metal wiring and a mini / micro LED display device with improved contrast, and to provide an optical laminate excellent in step absorption and processability.

Means for Solving the Problems

[0011] As a result of intensive studies to achieve the above object, the inventors of the present invention have adopted, as the polymer contained in the optical adhesive composition, a (meth)acrylic block copolymer having a high Tg segment and a low Tg segment having a specific glass transition temperature range. As a result, near room temperature (for example, 25°C), it exhibits a high storage elastic modulus, is hard and has good processability. In a region exceeding 50°C, the storage elastic modulus significantly decreases to become highly fluid, and the step absorption property is good. Further, by blending a colorant into the (meth)acrylic block copolymer, it has been found that it is suitable for the production of an antireflection function such as a metal wiring and a self-luminous display device with improved contrast. The present invention has been completed based on these findings.

[0012] That is, a first aspect of the present invention is an optical adhesive composition containing a (meth)acrylic block copolymer and a colorant, wherein the (meth)acrylic block copolymer has a high Tg segment having a glass transition temperature of 0°C or higher and 100°C or lower, a low Tg segment having a glass transition temperature of -100°C or higher and lower than 0°C, and characterized by having a peak of tanδ in a region of 0°C or higher and a region of lower than 0°C, respectively, and provides an optical adhesive composition. Here, the glass transition temperature is calculated by the FOX formula from the monomer component composition constituting each segment.

[0013] The optical adhesive composition of the present invention contains a (meth)acrylic block copolymer having the high-Tg segment and the low-Tg segment, and having peaks of tanδ in the region of 0°C or higher and the region of less than 0°C, respectively. Due to this, in the vicinity of room temperature (for example, 25°C), only the low-Tg segment of the (meth)acrylic block copolymer undergoes transition and fluidization, while the high-Tg segment does not undergo transition. Therefore, the (meth)acrylic block copolymer as a whole exhibits a high storage modulus, is hard, and has good processability. And in the region exceeding 50°C, the high-Tg segment also undergoes transition and fluidization, and the storage modulus of the whole (meth)acrylic block copolymer decreases to achieve high fluidity.

[0014] When the adhesive layer formed from the optical adhesive composition of the present invention is bonded to a display panel in which light-emitting elements (LED chips) are densely arranged, for example, by bonding under heating conditions (for example, 50°C or higher) such as an autoclave, high fluidity is achieved, and it sufficiently follows the fine steps between the light-emitting elements (LED chips) and adheres closely without leaving gaps or bubbles. Then, when stored after returning to room temperature (for example, 25°C), the storage modulus becomes high and the processability becomes good.

[0015] In addition, the configuration that the optical adhesive composition of the present invention further contains a colorant is preferable for preventing reflection by metal wirings or the like on the display panel and preventing color mixing between the arranged light-emitting elements (LED chips) to improve the contrast, with the adhesive filled without gaps in the fine steps between the LED chips.

[0016] In the optical adhesive composition according to the first aspect of the present invention, it is preferable that the maximum value of the peak of tanδ in the region of 0°C or higher is 0.5 to 3.0. This configuration is preferable in that it can realize the excellent processability and shape stability of the (meth)acrylic block copolymer.

[0017] In the pressure-sensitive adhesive composition for optics according to the first aspect of the present invention, it is preferable that the (meth)acrylic block copolymer is an ABA type triblock copolymer. This configuration is suitable in terms of ease of manufacturing the (meth)acrylic block copolymer.

[0018] In the ABA type triblock copolymer in the pressure-sensitive adhesive composition for optics according to the first aspect of the present invention, an embodiment in which the A segment is the high Tg segment and the B segment is the low Tg segment is preferable. This configuration is suitable for realizing the excellent step absorption and processability of the present invention.

[0019] In the pressure-sensitive adhesive composition for optics according to the first aspect of the present invention, as the monomer component constituting the high Tg segment in the (meth)acrylic block copolymer, it preferably contains at least one selected from the group consisting of (meth)acrylic acid alkyl esters having a linear alkyl group with 1 to 3 carbon atoms, (meth)acrylic acid alkyl esters having a branched alkyl group with 3 or 4 carbon atoms, and alicyclic monomers, and (meth)acrylic acid alkyl esters having a branched alkyl group with 3 or 4 carbon atoms are more preferable. As the alicyclic monomer, (meth)acrylic acid cycloalkyl esters having a cycloalkyl group with 4 to 10 carbon atoms which may have a substituent are preferable. This configuration controls the high Tg segment to have a predetermined glass transition temperature and the (meth)acrylic block copolymer to have a peak of tanδ in the region of 0°C or higher, and is suitable for realizing the excellent step absorption and processability of the present invention.

[0020] In the optical adhesive composition according to the first aspect of the present invention, as the monomer component constituting the low Tg segment in the (meth)acrylic block copolymer, it is preferable to contain at least one selected from the group consisting of (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 4 to 18 carbon atoms and hydroxyl group-containing monomers. This configuration controls the low Tg segment to have a predetermined glass transition temperature and the (meth)acrylic block copolymer to have a peak of tan δ in the region below 0°C, which is suitable for realizing the excellent step absorption property and processability of the present invention.

[0021] In the optical adhesive composition according to the first aspect of the present invention, it is preferable to contain 1% by weight or more of a hydroxyl group-containing monomer based on the total amount (100% by weight) of the monomer components constituting the low Tg segment in the (meth)acrylic block copolymer. This configuration controls the low Tg segment to a predetermined glass transition temperature and is suitable for realizing the excellent step absorption property and processability of the present invention.

[0022] In the optical adhesive composition according to the first aspect of the present invention, the weight average molecular weight of the (meth)acrylic block copolymer is preferably 200,000 or more. This configuration is preferable in that it is easy to obtain good hardness and processability near room temperature in the optical adhesive composition of the present invention.

[0023] In the optical adhesive composition according to the first aspect of the present invention, the molecular weight distribution of the (meth)acrylic block copolymer is preferably greater than 1 and 5 or less. This configuration is preferable in that the uniformity of the (meth)acrylic block copolymer is high and it is easy to obtain an adhesive with high transparency in the optical adhesive composition of the present invention.

[0024] In the optical adhesive composition according to the first aspect of the present invention, the ratio of the storage modulus at 25°C to the storage modulus at 50°C (storage modulus at 25°C / storage modulus at 50°C) is preferably 3 or more. This configuration is preferable in that, in the optical adhesive composition of the present invention, the difference between the storage modulus at room temperature (25°C) and the storage modulus during heating (50°C) becomes sufficiently wide, and it exhibits high fluidity during heating and excellent step absorption properties, and becomes hard at room temperature and exhibits excellent processability.

[0025] In the optical adhesive composition according to the first aspect of the present invention, the storage modulus at 25°C is preferably 1 MPa or more, and the storage modulus at 50°C is preferably 0.5 MPa or less. This configuration is preferable in that, in the optical adhesive composition of the present invention, the difference between the storage modulus at room temperature (25°C) and the storage modulus during heating (50°C) becomes sufficiently wide, and it exhibits high fluidity during heating and excellent step absorption properties, and becomes hard at room temperature and exhibits excellent processability.

[0026] In the optical adhesive composition according to the first aspect of the present invention, the coloring agent preferably has an average transmittance of 80% or less in the wavelength range of 400 to 700 nm. This configuration is preferable in that it imparts sufficient light-shielding properties to visible light to the adhesive filled without gaps in the fine steps between light-emitting elements (LED chips), prevents reflection by metal wirings etc. on the display panel, and prevents color mixing between the arranged light-emitting elements (LED chips) to improve the contrast.

[0027] Further, the second aspect of the present invention provides an adhesive layer formed of the optical adhesive composition according to the first aspect of the present invention. Further, the third aspect of the present invention provides an optical laminate including a base material and the adhesive layer according to the second aspect of the present invention. These configurations are such that the adhesive layer serves as a sealing material for sealing LED chips arranged on the display panel, and the base material serves as the outermost cover member, so there is no need to separately laminate a cover member after sealing, the number of processes and necessary members can be reduced, and the manufacturing efficiency is improved.

[0028] In the optical laminate according to the third aspect of the present invention, it is preferable that the surface of the base material where the adhesive layer is not laminated is subjected to an antireflection treatment and / or an antiglare treatment. The antireflection treatment and / or antiglare treatment is preferably an antiglare layer provided on one side of the base material. The antiglare layer is formed using an antiglare layer forming material containing a resin, particles, and a thixotropy imparting agent, and it is preferable that the antiglare layer has an agglomerated portion that forms convex portions on the surface of the antiglare layer due to the agglomeration of the particles and the thixotropy imparting agent. In the convex portions on the surface of the antiglare layer, the average inclination angle θa (°) is preferably in the range of 0.1 to 5.0. These configurations impart an antireflection function and / or an antiglare function to the surface of the optical laminate according to the third aspect of the present invention, and are preferable from the viewpoints of preventing a decrease in visibility due to reflection of external light, reflection of images, etc., and adjusting the appearance such as glossiness.

[0029] The optical laminate according to the third aspect of the present invention may further have a surface protection film laminated on the surface of the base material where the adhesive layer is not laminated. Such a configuration is suitable for preventing the adhesion of scratches and dirt during the production, transportation, and shipment of the optical laminate and optical products including the same.

[0030] Further, the fourth aspect of the present invention is a self-luminous display device including a display panel in which a plurality of light-emitting elements are arranged on one side of a substrate and the optical laminate according to the third aspect of the present invention, and provides a self-luminous display device in which the surface on which the light-emitting elements of the display panel are arranged and the adhesive layer of the optical laminate are laminated. In the self-luminous display device according to the fourth aspect of the present invention, the display panel may be an LED panel in which a plurality of LED chips are arranged on one side of a substrate. Such a configuration is preferable in that, in the self-luminous display device according to the fourth aspect of the present invention, an adhesive containing a colorant that fills the fine steps between the light-emitting elements (LED chips) without gaps can prevent reflection of metal wiring on the substrate, prevent color mixing of RGB, and improve contrast.

Advantages of the Invention

[0031] Since the optical adhesive composition and the optical laminate of the present invention have the above configurations, they are excellent in step absorption and processability, and have high light shielding properties against visible light. Therefore, by using the optical adhesive composition and the optical laminate of the present invention in the manufacture of a self-luminous display device, a self-luminous display device with improved antireflection function and contrast such as metal wiring can be efficiently manufactured.

Brief Description of Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0033] [Optical Adhesive Composition] The optical adhesive composition according to the first aspect of the present invention contains a (meth)acrylic block copolymer and a colorant.

[0034] In the optical adhesive composition of the first aspect of the present invention, "optical" means being used for optical applications, and more specifically, being used in the manufacture of products (optical products) using optical members. Examples of optical products include input devices such as image display devices and touch panels, but self-emitting display devices such as mini / micro LED display devices and organic EL (electroluminescence) display devices are preferred, and in particular, it can be suitably used in the manufacture of mini / micro LED display devices. The same applies to "optical" in the optical laminate of the third aspect of the present invention.

[0035] <(meth)acrylic block copolymer> The (meth)acrylic block copolymer has a high Tg segment having a glass transition temperature of 0°C or higher and 100°C or lower, and a low Tg segment having a glass transition temperature of -100°C or higher and lower than 0°C, and has a peak of tanδ in the region of 0°C or higher and the region of lower than 0°C, respectively.

[0036] In this specification, the "high Tg segment having a glass transition temperature of 0°C or higher and 100°C or lower" is simply referred to as the "high Tg segment", the "low Tg segment having a glass transition temperature of -100°C or higher and lower than 0°C" is simply referred to as the "low Tg segment", the peak of tanδ in the region of 0°C or higher is simply referred to as the "high temperature region tanδ peak", the peak of tanδ in the region of lower than 0°C is simply referred to as the "low temperature region tanδ peak", and the (meth)acrylic block copolymer having the high Tg segment, the low Tg segment, the high temperature region tanδ peak, and the low temperature region tanδ peak is referred to as "(meth)acrylic block copolymer A", and the optical adhesive composition containing the (meth)acrylic block copolymer A and a colorant may be referred to as "optical adhesive composition A".

[0037] Note that “(meth)acryl” means “acryl” and / or “methacryl” (either one or both of “acryl” and “methacryl”), and the same applies hereinafter. Also, “(meth)acryloyl group” means “acryloyl group” and / or “methacryloyl group” (either one or both of “acryloyl group” and “methacryloyl group”), and the same applies hereinafter.

[0038] In the high-Tg segment and the low-Tg segment, “segment” refers to the partial structure that constitutes each block unit of the (meth)acrylic block copolymer A.

[0039] The structure of the (meth)acrylic block copolymer A of the present invention may be a linear block copolymer, a branched (star-shaped) block copolymer, or a mixture thereof. Such a block copolymer structure may be appropriately selected according to the required physical properties of the block copolymer. However, from the viewpoints of cost and ease of production, a linear block copolymer is preferably used. Also, the linear block copolymer may have any structure (arrangement). However, from the viewpoints of the physical properties of the linear block copolymer or the physical properties of the pressure-sensitive adhesive composition A for optics, a block copolymer having at least one structure selected from the group consisting of (A-B) n type, (A-B) n -A type (n is an integer of 1 or more, for example, an integer of 1 to 3) is preferably used. In these structures, A and B mean segments composed of different monomer compositions. In this specification, the segment represented by A that constitutes the linear block copolymer may be referred to as “A segment”, and the segment represented by B may be referred to as “B segment”.

[0040] Among these, from the viewpoints of ease of production, physical properties of the optical adhesive composition A, etc., an AB-type diblock copolymer represented by A-B and an ABA-type triblock copolymer represented by A-B-A are preferable, and more preferably an ABA-type triblock copolymer. In the ABA-type triblock copolymer, the crosslinked structure between the block copolymers becomes more advanced due to the pseudo-crosslinking between the A segments at both ends, the cohesive force of the block copolymer is improved, and it is considered that higher adhesiveness (adhesive strength) can be exhibited. In the ABA-type triblock copolymer, the two A segments located at both ends may be the same as or different from each other.

[0041] When the (meth)acrylic block copolymer A is an ABA-type triblock copolymer, in the two A segments and one B segment (a total of three), at least one may be a high-Tg segment and at least one of the others may be a low-Tg segment. From the viewpoints of ease of production, physical properties of the optical adhesive composition A, etc., an ABA-type triblock copolymer in which the A segment is the high-Tg segment and the B segment is the low-Tg segment is preferable. In that case, an ABA-type triblock copolymer in which at least one of the two A segments is a high-Tg segment and the B segment is a low-Tg segment is preferable, and an ABA-type triblock copolymer in which both of the two A segments are high-Tg segments and the B segment is a low-Tg segment is more preferable.

[0042] (Meth)acrylic block copolymer A has a glass transition temperature (Tg) of the high-Tg segment of 0 °C or higher and 100 °C or lower as described above. When the Tg of the high-Tg segment is within this range, it becomes easier to highly control the storage elastic modulus of the optical adhesive composition A at room temperature (25 °C), resulting in a hard and excellent processability, and a tendency to become a highly fluid adhesive composition with a significantly reduced storage elastic modulus in the region exceeding 50 °C. From the viewpoint of improving the processability of the optical adhesive composition A at room temperature (25 °C), the Tg of the high-Tg segment is preferably 4 °C or higher, more preferably 6 °C or higher, still more preferably 8 °C or higher, even more preferably 10 °C or higher, and particularly preferably 12 °C or higher. On the other hand, from the viewpoint that the storage elastic modulus (G') of the optical adhesive composition A significantly decreases and becomes highly fluid in the region exceeding 50 °C, the Tg of the high-Tg segment is preferably 90 °C or lower, more preferably 85 °C or lower, still more preferably 60 °C or lower, even more preferably 50 °C or lower, and particularly preferably 35 °C or lower.

[0043] (Meth)acrylic block copolymer A has a Tg of the low-Tg segment of -100 °C or higher and less than 0 °C as described above. When the glass Tg of the low-Tg segment is within this range, only the low-Tg segment is fluidized at room temperature (25 °C), and there is a tendency to ensure processability and impart appropriate adhesiveness to the optical adhesive composition A. From the viewpoint that the storage elastic modulus of the optical adhesive composition A hardly decreases and the processability can be improved at room temperature (25 °C), the Tg of the low-Tg segment is preferably -95 °C or higher, more preferably -90 °C or higher, still more preferably -80 °C or higher. On the other hand, from the viewpoint that appropriate adhesiveness and processability of the optical adhesive composition A can be improved at room temperature (25 °C), the Tg of the low-Tg segment is preferably -5 °C or lower, more preferably -10 °C or lower, still more preferably -20 °C or lower, even more preferably -30 °C or lower, and particularly preferably -40 °C or lower.

[0044] (Meta) The difference in Tg between the high-Tg segment and the low-Tg segment that make up the acrylic block copolymer A (Tg of the high-Tg segment - Tg of the low-Tg segment) is not particularly limited. However, from the perspective of easily controlling the storage modulus of the optical adhesive composition A at room temperature (25°C) to be high, having excellent hardness and processability, and the storage modulus significantly decreasing in the region exceeding 50°C to form a highly fluid adhesive composition, it is preferably 30°C or higher, more preferably 35°C or higher, still more preferably 40°C or higher, even more preferably 45°C or higher, further preferably 50°C or higher, particularly preferably 55°C or higher, and preferably 120°C or lower, more preferably 115°C or lower, still more preferably 110°C or lower, even more preferably 105°C or lower, further preferably 100°C or lower, particularly preferably 95°C or lower.

[0045] (Meta) The glass transition temperatures (Tg) of the high-Tg segment and the low-Tg segment that make up the acrylic block copolymer A are the calculated glass transition temperatures calculated from the following Fox's equation. This calculated glass transition temperature is calculated based on the types and amounts of the monomer components that make up the high-Tg segment or the low-Tg segment of the (meta)acrylic block copolymer A. Therefore, it can be adjusted by selecting the types and amounts of the monomer components of each segment, etc.

[0046] The calculated glass transition temperature (calculated Tg) can be calculated from the following Fox's equation [1]. 1 / calculated Tg = W1 / Tg(1) + W2 / Tg(2) + ··· + Wn / Tg(n) [1] Here, W1, W2, ···, Wn represent the weight fractions (wt%) of each monomer component (1), monomer component (2), ···, monomer component (n) that make up the copolymer with respect to all monomer components, and Tg(1), Tg(2), ···, Tg(n) represent the glass transition temperatures (unit: absolute temperature: K) of the homopolymers of monomer component (1), monomer component (2), ···, monomer component (n). Incidentally, the glass transition temperatures of homopolymers are known from various documents, catalogs, etc. For example, they are described in J. Brandup, E. H. Immergut, E. A. Grulke: Polymer Handbook: JOHN WILEY & SONS, INC. For monomers without numerical values in various documents, values measured by general thermal analysis, such as differential thermal analysis or dynamic viscoelasticity measurement methods, can be adopted.

[0047] (Meth)acrylic block copolymer A has a high-temperature region tanδ peak that appears in a temperature range of 0 °C or higher (for example, 0 °C or higher and 100 °C or lower) as described above. Since the high-temperature region tanδ peak is within this temperature range, it becomes easier to control the storage modulus of the optical adhesive composition A at room temperature (25 °C) to be high, resulting in a hard and excellent processability. Moreover, in the region exceeding 50 °C, the storage modulus tends to significantly decrease, resulting in a highly fluid adhesive composition. From the perspective of improving the processability of the optical adhesive composition A at room temperature (25 °C), the temperature at which the high-temperature region tanδ peak appears is preferably 3 °C or higher, more preferably 6 °C or higher, still more preferably 9 °C or higher, even more preferably 12 °C or higher, and particularly preferably 15 °C or higher. On the other hand, from the perspective that the storage modulus (G’) of the optical adhesive composition A tends to significantly decrease and become highly fluid in the region exceeding 50 °C, the temperature at which the high-temperature region tanδ peak appears is preferably 90 °C or lower, more preferably 80 °C or lower, still more preferably 70 °C or lower, even more preferably 65 °C or lower, and particularly preferably 60 °C or lower.

[0048] (Meta)acrylic block copolymer A has a temperature range where the tanδ peak in the low-temperature region appears, which is less than 0 °C (for example, -100 °C or higher and less than 0 °C) as described above. Due to the tanδ peak in the low-temperature region being within this temperature range, only the low-Tg segment is fluidized at room temperature (25 °C), and there is a tendency to be able to impart appropriate adhesiveness to the optical adhesive composition A while ensuring processability. From the perspective that the storage modulus of the optical adhesive composition A is less likely to decrease and the processability can be improved at room temperature (25 °C), the temperature at which the tanδ peak in the low-temperature region appears is preferably -95 °C or higher, more preferably -90 °C or higher, still more preferably -80 °C or higher, and even more preferably -70 °C or higher. On the other hand, from the perspective that appropriate adhesiveness and processability of the optical adhesive composition A can be improved at room temperature (25 °C), the temperature at which the tanδ peak in the low-temperature region appears is preferably -5 °C or lower, more preferably -10 °C or lower, still more preferably -20 °C or lower, even more preferably -30 °C or lower, and particularly preferably -40 °C or lower.

[0049] The maximum value of the tanδ peak in the high-temperature region is not particularly limited, but is preferably 0.5 to 3.0. When the maximum value of the tanδ peak in the high-temperature region is within this range, it is preferable in terms of realizing excellent processability and shape stability of the (meta)acrylic block copolymer. The maximum value of the tanδ peak in the high-temperature region is preferably 0.6 or higher, more preferably 0.7 or higher, in terms of realizing excellent processability. Also, the maximum value of the tanδ peak in the high-temperature region is preferably 2.5 or lower, more preferably 2.2 or lower, from the point that indentations are less likely to occur.

[0050] The maximum value of the tanδ peak in the low-temperature region is not particularly limited, but is preferably 0.1 to 2.0. When the maximum value of the tanδ peak in the low-temperature region is within this range, it is preferable in terms of realizing excellent processability and shape stability of the (meta)acrylic block copolymer. The maximum value of the tanδ peak in the high-temperature region is preferably 0.2 or higher, more preferably 0.3 or higher, in terms of realizing excellent processability. Also, the maximum value of the tanδ peak in the low-temperature region is preferably 1.5 or lower, more preferably 1 or lower, from the point that indentations are less likely to occur.

[0051] Incidentally, the high-temperature region tan δ peak, the low-temperature region tan δ peak, the temperatures at which they appear, and the maximum values are measured by the dynamic viscoelasticity measurement described in the examples below.

[0052] (Meth)acrylic block copolymer A is composed of a plurality of segments (including high-Tg segments and low-Tg segments) obtained by polymerizing monomer components, and the monomer components include a monomer having a (meth)acryloyl group in the molecule (acrylic monomer). (Meth)acrylic block copolymer A or each of its segments preferably contains 70% by weight or more, more preferably 80% by weight or more, and particularly preferably 90% by weight or more of the acrylic monomer based on the total amount of the monomer components (100% by weight).

[0053] As the acrylic monomer constituting (meth)acrylic block copolymer A or each of its segments (including high-Tg segments and low-Tg segments), a monomer component derived from an acrylic acid alkyl ester having a linear or branched alkyl group and / or a methacrylic acid alkyl ester having a linear or branched alkyl group is included as the main monomer unit having the largest weight ratio.

[0054] (Meth)acrylic acid alkyl esters having a linear or branched alkyl group for forming segments of the (meth)acrylic block copolymer A, that is, (meth)acrylic acid alkyl esters having a linear or branched alkyl group contained in the monomer component for forming the segments include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate, etc., (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 1 to 20 carbon atoms can be mentioned. As the (meth)acrylic acid alkyl ester for the segments, one kind of (meth)acrylic acid alkyl ester may be used, or two or more kinds of (meth)acrylic acid alkyl esters may be used. In the present embodiment, as the (meth)acrylic acid alkyl ester for the segments, preferably, at least one selected from the group consisting of methyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, t-butyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, and isononyl acrylate is used.

[0055] The segment of the (meth)acrylic block copolymer A may contain monomer units derived from an alicyclic monomer. Examples of the alicyclic monomer that forms the monomer units of the segment, i.e., the alicyclic monomer contained in the monomer component for forming the segment, include (meth)acrylic acid cycloalkyl esters having a cycloalkyl group with 4 to 10 carbon atoms, (meth)acrylic acid esters having a bicyclic hydrocarbon ring, and (meth)acrylic acid esters having a tricyclic or higher hydrocarbon ring. The cycloalkyl group, bicyclic hydrocarbon ring, and tricyclic or higher hydrocarbon ring may have substituents. Examples of the substituent include a halogen atom (e.g., fluorine atom, chlorine atom, bromine atom, iodine atom), a linear or branched alkyl group with 1 to 6 carbon atoms (e.g., methyl group, ethyl group, n-propyl group, isopropyl group, etc.). The number of the substituents is not particularly limited and can be appropriately selected from 1 to 6. When there are two or more substituents, the two or more substituents may be the same or different.

[0056] (Meta) acrylic acid cycloalkyl esters include, for example, cyclopentyl (meta) acrylate, cyclohexyl (meta) acrylate, 3,3,5-trimethylcyclohexyl (meta) acrylate, cycloheptyl (meta) acrylate, and cyclooctyl (meta) acrylate. Examples of (meta) acrylic acid esters having a bicyclic hydrocarbon ring include bornil (meta) acrylate and isobornyl (meta) acrylate. Examples of (meta) acrylic acid esters having a tricyclic or higher hydrocarbon ring include dicyclopentanyl (meta) acrylate, dicyclopentanyloxyethyl (meta) acrylate, tricyclopentanyl (meta) acrylate, 1-adamantyl (meta) acrylate, 2-methyl-2-adamantyl (meta) acrylate, and 2-ethyl-2-adamantyl (meta) acrylate. As the alicyclic monomer for the segment, one kind of alicyclic monomer may be used, or two or more kinds of alicyclic monomers may be used. In the present embodiment, as the alicyclic monomer for the segment, preferably, a cycloalkyl group having 4 to 10 carbon atoms which may have a substituent (e.g., a linear or branched alkyl group having 1 to 6 carbon atoms) is used. (Meta) acrylic acid cycloalkyl ester, more preferably, at least one selected from the group consisting of cyclohexyl acrylate and 3,3,5-trimethylcyclohexyl (meta) acrylate is used.

[0057] (Meta) acrylic block copolymer A segments may contain monomer units derived from hydroxyl group-containing monomers. A hydroxyl group-containing monomer is a monomer that has at least one hydroxyl group in the monomer unit. When the segment in the (meta) acrylic block copolymer A contains a hydroxyl group-containing monomer unit, it is easy to obtain adhesiveness and appropriate cohesive force in the optical adhesive composition A.

[0058] The hydroxyl group-containing monomers for forming the monomer units of the segment, that is, the hydroxyl group-containing monomers contained in the monomer components for forming the segment, include, for example, hydroxyl group-containing (meth)acrylic acid esters, vinyl alcohol, and allyl alcohol. Examples of the hydroxyl group-containing (meth)acrylic acid esters include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, hydroxyoctyl (meth)acrylate, hydroxydecyl (meth)acrylate, hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxyl group-containing monomer for the segment, one kind of hydroxyl group-containing monomer may be used, or two or more kinds of hydroxyl group-containing monomers may be used. In the present embodiment, as the hydroxyl group-containing monomer for the segment, preferably, a hydroxyl group-containing (meth)acrylic acid ester is used, and more preferably, at least one selected from the group consisting of 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, and 4-hydroxybutyl methacrylate is used.

[0059] (The segment of the (meth)acrylic block copolymer A may contain monomer units derived from a nitrogen atom-containing monomer. The nitrogen atom-containing monomer is a monomer having at least one nitrogen atom in the monomer unit. When the segment of the (meth)acrylic block copolymer A contains a nitrogen atom-containing monomer unit, it is easy to obtain hardness and good adhesion reliability in the optical adhesive composition A.)

[0060] Examples of the nitrogen atom-containing monomer for forming the segment, that is, the nitrogen atom-containing monomer included in the monomer component for forming the segment, include N-vinyl cyclic amides and (meth)acrylamides. Examples of the N-vinyl cyclic amide as the nitrogen atom-containing monomer include N-vinyl-2-pyrrolidone, N-vinyl-2-piperidone, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, and N-vinyl-3,5-morpholinedione. Examples of the (meth)acrylamides as the nitrogen atom-containing monomer include (meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-n-butyl(meth)acrylamide, N-octyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, and N,N-diisopropyl(meth)acrylamide. As the nitrogen atom-containing monomer for the acrylic polymer, one kind of nitrogen atom-containing monomer may be used, or two or more kinds of nitrogen atom-containing monomers may be used. In the present embodiment, N-vinyl-2-pyrrolidone is preferably used as the nitrogen atom-containing monomer for the segment.

[0061] (The segment of the (meth)acrylic block copolymer A may contain a monomer unit derived from a carboxy group-containing monomer. The carboxy group-containing monomer is a monomer having at least one carboxy group in the monomer unit. When the segment of the (meth)acrylic block copolymer A contains a carboxy group-containing monomer unit, good adhesion reliability may be obtained in the optical adhesive composition A.)

[0062] Examples of the carboxy group-containing monomer for forming the monomer unit of the segment, i.e., the carboxy group-containing monomer included in the monomer component for forming the segment, include (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. As the carboxy group-containing monomer for the segment, one kind of carboxy group-containing monomer may be used, or two or more kinds of carboxy group-containing monomers may be used. In the present embodiment, acrylic acid is preferably used as the carboxy group-containing monomer for the segment.

[0063] Furthermore, examples of the monomer unit for forming the segment include the above-mentioned (meth)acrylic acid alkyl ester, alicyclic monomer, hydroxyl group-containing monomer, nitrogen atom-containing monomer, and monomers other than the carboxy group-containing monomer (which may be referred to as "other monomers"). Examples of other monomers include (meth)acrylic acid alkoxyalkyl esters [e.g., 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxy triethylene glycol (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate, etc.]; epoxy group-containing monomers [e.g., glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, etc.]; sulfonic acid group-containing monomers [e.g., sodium vinyl sulfonate, etc.]; phosphoric acid group-containing monomers; (meth)acrylic acid esters having an aromatic hydrocarbon group [e.g., phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, etc.]; vinyl esters [e.g., vinyl acetate, vinyl propionate, etc.]; aromatic vinyl compounds [e.g., styrene, vinyltoluene, etc.]; olefins or dienes [e.g., ethylene, propylene, butadiene, isoprene, isobutylene, etc.]; vinyl ethers [e.g., vinyl alkyl ether, etc.]; vinyl chloride, etc.

[0064] As long as the content of other monomers in the monomer units constituting the segment of the (meth)acrylic block copolymer A is 30% by weight or less based on the total amount of the monomer components (100% by weight), it is not particularly limited and is appropriately selected within the range that does not impair the effects of the present invention.

[0065] As the monomer components constituting the high-Tg segment of the (meth)acrylic block copolymer A, from the viewpoint of easily controlling the Tg of the high-Tg segment within a predetermined range and imparting desired physical properties to the (meth)acrylic block copolymer A, (meth)acrylic acid alkyl esters having a linear alkyl group with 1 to 3 carbon atoms (hereinafter sometimes referred to as "(meth)acrylic acid C 1-3 linear alkyl esters"), (meth)acrylic acid alkyl esters having a branched alkyl group with 3 or 4 carbon atoms (hereinafter sometimes referred to as "(meth)acrylic acid C 3-4 branched alkyl esters") and at least one selected from the group consisting of alicyclic monomers are preferably contained. Since the homopolymers of these monomers have a relatively high Tg, by containing the monomers selected therefrom as the monomer components constituting the high-Tg segment, it is easy to control the Tg of the high-Tg segment within the predetermined range of the present invention.

[0066] As the alicyclic monomer, (meth)acrylic acid cycloalkyl esters having a cycloalkyl group with 4 to 10 carbon atoms which may have a substituent (e.g., a linear or branched alkyl group with 1 to 6 carbon atoms) are preferred, (meth)acrylic acid cycloalkyl esters having a cycloalkyl group with 4 to 10 carbon atoms which may have a substituent (e.g., a linear or branched alkyl group with 1 to 6 carbon atoms) are more preferred, and cyclohexyl acrylate (Tg of homopolymer: 15°C), 3,3,5-trimethylcyclohexyl (meth)acrylate (Tg of homopolymer: 52°C) are particularly preferred.

[0067] When the high-Tg segment contains an alicyclic monomer as a monomer component, the content of the alicyclic monomer with respect to the total amount (100% by weight) of the monomer components is preferably 10% by weight or more (for example, 10 to 100% by weight), more preferably 20% by weight or more, more preferably 30% by weight or more, more preferably 30% by weight or more, more preferably 40% by weight or more, more preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more, from the viewpoint that it is easy to control the Tg of the high-Tg segment within a predetermined range and desired physical properties can be imparted to the (meth)acrylic block copolymer A.

[0068] The (meth)acrylic acid C 1-3 As the linear alkyl ester, acrylic acid C 1-3 A linear alkyl ester is preferred, and methyl acrylate (Tg of homopolymer: 8 °C) is particularly preferred. The (meth)acrylic acid C 3-4 As the branched-chain alkyl ester, acrylic acid C 3-4 A branched-chain alkyl ester is preferred, and t-butyl acrylate (Tg of homopolymer: 35 °C) is particularly preferred.

[0069] When the monomer component constituting the high-Tg segment contains a (meth)acrylic acid C 1-3 linear alkyl ester and / or a (meth)acrylic acid C 3-4 branched-chain alkyl ester, the (meth)acrylic acid C 1-3 linear alkyl ester and / or the (meth)acrylic acid C 3-4The content with respect to the total amount (100% by weight) of the monomer components of the branched-chain alkyl ester is preferably 10% by weight or more (for example, 10 to 100% by weight), more preferably 20% by weight or more, more preferably 30% by weight or more, more preferably 30% by weight or more, more preferably 40% by weight or more, more preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, particularly preferably 95% by weight or more, from the viewpoint of easily controlling the Tg of the high-Tg segment within a predetermined range and imparting desired physical properties to the (meth)acrylic block copolymer A.

[0070] As the monomer component constituting the low-Tg segment of the (meth)acrylic block copolymer A, from the viewpoint of easily controlling the Tg of the low-Tg segment within a predetermined range and imparting desired physical properties to the (meth)acrylic block copolymer A, it preferably contains at least one selected from the group consisting of (meth)acrylic acid alkyl esters having a linear or branched alkyl group with 4 to 18 carbon atoms (hereinafter sometimes referred to as "(meth)acrylic acid C 4-18 alkyl ester") and hydroxyl group-containing monomers. That is, since the homopolymer of (meth)acrylic acid C 4-18 alkyl ester has a relatively low Tg, by containing this as the monomer component constituting the low-Tg segment, it is easy to control the Tg of the low-Tg segment within the predetermined range of the present invention. On the other hand, the hydroxyl group-containing monomer also has a relatively low Tg, and furthermore, it is easy to obtain adhesiveness and appropriate cohesive force in the (meth)acrylic block copolymer A. Therefore, it is more preferable to contain both (meth)acrylic acid C 4-18 alkyl ester and the hydroxyl group-containing monomer as the monomer component constituting the low-Tg segment of the (meth)acrylic block copolymer A.

[0071] As the (meth)acrylic acid C 4-18 alkyl ester, acrylic acid C 4-18An alkyl ester is preferred, and butyl acrylate (Tg of homopolymer: -55°C), 2-ethylhexyl acrylate (Tg of homopolymer: -70°C), n-hexyl acrylate (Tg of homopolymer: -57°C), n-octyl acrylate (Tg of homopolymer: -65°C), and isononyl acrylate (Tg of homopolymer: -58°C) are particularly preferred.

[0072] As a monomer component constituting the low-Tg segment, (meth)acrylic acid C 4-18 When containing an alkyl ester, (meth)acrylic acid C 4-18 The content with respect to the total amount (100% by weight) of the monomer components of the alkyl ester is preferably 10% by weight or more (for example, 10 to 100% by weight), more preferably 20% by weight or more, more preferably 30% by weight or more, more preferably 30% by weight or more, more preferably 40% by weight or more, more preferably 50% by weight or more, more preferably 60% by weight or more, more preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more from the viewpoint of easily controlling the Tg of the low-Tg segment within a predetermined range and imparting desired physical properties to the (meth)acrylic block copolymer A.

[0073] As the hydroxyl group-containing monomer, a hydroxyl group-containing (meth)acrylic acid alkyl ester is preferred, and 4-hydroxybutyl acrylate (Tg of homopolymer: -65°C) and 2-hydroxyethyl acrylate (Tg of homopolymer: -15°C) are particularly preferred.

[0074] When a hydroxyl group-containing monomer is contained as a monomer component constituting the low Tg segment, the content of the hydroxyl group-containing monomer relative to the total amount of monomer components (100% by weight) is preferably 1% by weight or more, more preferably 1.5% by weight or more, more preferably 2% by weight or more, even more preferably 2.5% by weight or more, and particularly preferably 3% by weight or more, from the viewpoint of easily controlling the Tg of the low Tg segment within a predetermined range and imparting desired physical properties to the (meth)acrylic block copolymer A. On the other hand, the content of the hydroxyl group-containing monomer relative to the total amount of monomer components (100% by weight) is preferably 50% by weight or less, more preferably 40% by weight or less, more preferably 30% by weight or less, more preferably 20% by weight or less, even more preferably 10% by weight or less, and particularly preferably 5% by weight or less.

[0075] As a monomer component constituting the low Tg segment of the (meth)acrylic block copolymer A, (meth)acrylic acid C 4-18 In the case where both an alkyl ester and a hydroxyl group-containing monomer are contained, the hydroxyl group-containing monomer and (meth)acrylic acid C 4-18 Ratio of alkyl ester (hydroxyl group-containing monomer / (meth)acrylic acid C 4-18 The alkyl ester) is not particularly limited, but the lower limit is preferably 1 / 99, more preferably 1.5 / 98.5, more preferably 2 / 98, even more preferably 2.5 / 97.5, and particularly preferably 3 / 97, while the upper limit is 50 / 50, more preferably 40 / 60, more preferably 30 / 70, and even more preferably 20 / 80.

[0076] The (meth)acrylic block copolymer A can be produced by a living radical polymerization method of the above-mentioned monomer components. The living radical polymerization method is preferable in that, while maintaining the simplicity and versatility of conventional radical polymerization methods, termination reactions and chain transfer are unlikely to occur, and the growing end grows without being deactivated, making it easy to precisely control the molecular weight distribution and produce a polymer with a uniform composition.

[0077] In the living radical polymerization method, a high-Tg segment may be produced first, and a monomer of a low-Tg segment may be polymerized to the high-Tg segment; or a low-Tg segment may be produced first, and a monomer of a high-Tg segment may be polymerized to the low-Tg segment.

[0078] When the (meth)acrylic block copolymer A is an ABA type triblock copolymer, from the viewpoint of ease of production, it is preferable to produce the A segment first and polymerize the monomer of the B segment to the A segment.

[0079] The living radical polymerization method can be used without particularly limiting known methods. Depending on the method of stabilizing the polymerization growing end, there are methods using a transition metal catalyst (ATRP method); methods using a sulfur-based reversible addition-fragmentation chain transfer agent (RAFT agent) (RAFT method); methods using an organic tellurium compound (TERP method), etc. Among these methods, from the viewpoints of the variety of monomers that can be used, ease of controlling the molecular weight, and no metal remaining in the optical adhesive composition, it is preferable to use the RAFT method.

[0080] The RAFT method can be used without particularly limiting known methods. For example, for example, Step 1 (first RAFT polymerization) of preparing a first segment by polymerizing a monomer component using a RAFT agent, and Step 2 (second RAFT polymerization) of adding and polymerizing a monomer component different from the monomer composition in Step 1 to the first segment obtained in Step 1 to attach the second segment to the first segment. After the second RAFT polymerization, further third, fourth,... RAFT polymerizations may be carried out in the same manner as the second RAFT polymerization to further attach the third, fourth,... segments.

[0081] The above-mentioned Step 1 and Step 2 can be carried out by known and commonly used methods. For example, solution polymerization methods, emulsion polymerization methods, bulk polymerization methods, polymerization methods by heat or active energy ray irradiation (heat polymerization methods, active energy ray polymerization methods), etc. can be mentioned. Among them, from the viewpoints of transparency, water resistance, cost, etc., the solution polymerization method is preferable. In addition, the polymerization is preferably carried out while avoiding contact with oxygen from the viewpoint of suppressing polymerization inhibition by oxygen. For example, it is preferable to carry out the polymerization under a nitrogen atmosphere.

[0082] When the (meth)acrylic block copolymer A is an ABA type triblock copolymer, it is preferable to prepare the A segment in the above-mentioned Step 1 and add the B segment in the above-mentioned Step 2 to the obtained A segment for preparation. In this case, it is preferable that the A segment is a high Tg segment and the B segment is a low Tg segment.

[0083] As the above-mentioned RAFT agent, known ones can be used without particular limitation. For example, compounds represented by the following formula (1), formula (2), or formula (3) (trithiocarbonate, dithioester, dithiocarbonate) are preferable.

Chemical formula

Chemical formula

Chemical formula

[0084] In formula (1), formula (2), or formula (3) [formulas (1) to (3)], R 1a and R 1b represent the same or different hydrogen atoms, hydrocarbon groups, or cyano groups. R 1c represents a hydrocarbon group which may have a cyano group. The above R 1a , R 1b , and R 1cExamples of the hydrocarbon group as such include hydrocarbon groups having 1 to 20 carbon atoms (such as linear, branched, or cyclic saturated or unsaturated hydrocarbon groups), and among them, hydrocarbon groups having 1 to 12 carbon atoms are preferred. Specific examples of the hydrocarbon group include linear, branched, or cyclic alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, cyclohexyl group, dodecyl group, octadecyl group; aryl groups having 6 to 12 carbon atoms such as phenyl group; arylalkyl groups having a total of 7 to 10 carbon atoms such as benzyl group and phenethyl group. The above R 1c Examples of the hydrocarbon group having a cyano group as such include groups in which 1 to 3 hydrogen atoms of the above-described hydrocarbon group are substituted with cyano groups.

[0085] In formulas (1) to (3), R 2 represents a hydrocarbon group or a group in which a part of the hydrogen atoms of the hydrocarbon group is substituted with a carboxyl group (for example, a carboxyalkyl group). Examples of the hydrocarbon group include hydrocarbon groups having 1 to 20 carbon atoms (such as linear, branched, or cyclic saturated or unsaturated hydrocarbon groups), and among them, hydrocarbon groups having 1 to 12 carbon atoms are preferred. Specific examples of the hydrocarbon group include linear, branched, or cyclic alkyl groups having 1 to 12 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, cyclohexyl group, dodecyl group, octadecyl group; arylalkyl groups having a total of 7 to 10 carbon atoms such as benzyl group and phenethyl group.

[0086] In the RAFT method, the polymerization proceeds by reacting such that the raw material monomer is inserted between the sulfur atom and the methylene group adjacent to the sulfur atom in the RAFT agent represented by formulas (1) to (3).

[0087] Many of the above-mentioned RAFT agents are commercially available. Those that are not commercially available can be easily synthesized by known or conventional methods. In the present invention, the RAFT agent can be used alone or in combination of two or more kinds.

[0088] Examples of the RAFT agent include trithiocarbonates such as dibenzyl trithiocarbonate and S-cyanomethyl-S-dodecyl trithiocarbonate; dithioesters such as cyanoethyl dithiopropionate, benzyl dithiopropionate, benzyl dithiobenzoate, and acetoxyethyl dithiobenzoate; dithiocarbonates such as O-ethyl-S-(1-phenylethyl) dithiocarbonate, O-ethyl-S-(2-propoxyethyl) dithiocarbonate, and O-ethyl-S-(1-cyano-1-methylethyl) dithiocarbonate. Among these, trithiocarbonates are preferred, and trithiocarbonates having a symmetric structure in formula (1) are more preferred. Particularly, dibenzyl trithiocarbonate and bis{4-[ethyl-(2-acetoxyethyl)carbamoyl]benzyl} trithiocarbonate are preferred.

[0089] Step 1 can be carried out by polymerizing the monomer component in the presence of a RAFT agent. The amount of the RAFT agent used in Step 1 is usually 0.05 to 20 parts by weight, preferably 0.05 to 10 parts by weight, based on 100 parts by weight of the total amount of the monomer component. With such an amount used, the reaction control is easy, and it is also easy to control the weight-average molecular weight of the obtained segment. Step 2 can be carried out by adding a monomer component to the polymerization reaction mixture obtained in Step 1 and further polymerizing it.

[0090] The RAFT method is preferably carried out in the presence of a polymerization initiator. Examples of the polymerization initiator include ordinary organic polymerization initiators, specifically, peroxides and azo compounds. Among these, azo compounds are preferred. The polymerization initiator can be used alone or in combination of two or more kinds.

[0091] Examples of the peroxide-based polymerization initiator include benzoyl peroxide and tert-butyl permaleate. Examples of the azo compound include 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2-(carbamoylazo)isobutyronitrile, 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(N,N'-dimethylenebis(isobutylamidine)), 2,2'-azobis(isobutyramide) dihydrate, 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(2-cyanopropanol), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0092] The amount of the polymerization initiator used is usually 0.001 to 2 parts by weight, preferably 0.002 to 1 part by weight, based on 100 parts by weight of the total amount of the monomer components. With such an amount used, it is easy to control the weight-average molecular weight of the resulting segment.

[0093] The RAFT method may be bulk polymerization without using a polymerization solvent, but it is preferred to use a polymerization solvent. Examples of the polymerization solvent include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cycloheptane, and cyclooctane; halogenated hydrocarbons such as chloroform, carbon tetrachloride, 1,2-dichloroethane, and chlorobenzene; ethers such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane, dibutyl ether, tetrahydrofuran, dioxane, anisole, phenylethyl ether, and diphenyl ether; esters such as ethyl acetate, propyl acetate, butyl acetate, and methyl propionate; ketones such as acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, and cyclohexanone; amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; nitriles such as acetonitrile and benzonitrile; and sulfoxides such as dimethyl sulfoxide and sulfolane. The polymerization solvent can be used alone or in combination of two or more.

[0094] The amount of the polymerization solvent used is not particularly limited. For example, it is preferably 0.01 mL or more, more preferably 0.05 mL or more, and still more preferably 0.1 mL or more per 1 g of the monomer component, and preferably 50 mL or less, more preferably 10 mL or less, and still more preferably 1 mL or less.

[0095] The reaction temperature in the RAFT method is usually 60 to 120 °C, preferably 70 to 110 °C, and is usually carried out in an inert gas atmosphere such as nitrogen gas. This reaction can be carried out under any conditions of normal pressure, increased pressure, and reduced pressure, and is usually carried out under normal pressure. The reaction time is usually 1 to 20 hours, preferably 2 to 14 hours.

[0096] The polymerization reaction conditions of the above RAFT method can be applied to each of Step 1 and Step 2.

[0097] After the coincidence reaction is completed, the target (meth)acrylic block copolymer A can be separated from the obtained reaction mixture by ordinary separation and purification means such as removing the used solvent and residual monomers.

[0098] When preparing the high-Tg segment or low-Tg segment of the (meth)acrylic block copolymer A in the above step 1, the weight-average molecular weight (Mw) of the high-Tg segment or low-Tg segment is not particularly limited, but is preferably 10,000 to 1,000,000, more preferably 50,000 to 500,000, and still more preferably 100,000 to 300,000. The Mw of the high-Tg segment or low-Tg segment being within this range is suitable for the effects of the present invention described above. When there are two or more high-Tg segments or low-Tg segments in the (meth)acrylic block copolymer A, the above Mw is the sum of the Mws.

[0099] The weight-average molecular weight (Mw) of the (meth)acrylic block copolymer A is not particularly limited, but is preferably 200,000 or more, more preferably 300,000 to 5,000,000, and still more preferably 400,000 to 2,500,000. The Mw of the (meth)acrylic block copolymer A being within this range is suitable for the effects of the present invention described above.

[0100] The molecular weight distribution (Mw / Mn) of the (meth)acrylic block copolymer A is not particularly limited, but is preferably greater than 1, more preferably 1.5 or more, still more preferably 2 or more, particularly preferably 2.5 or more, preferably 5 or less, more preferably 4.5 or less, still more preferably 4 or less, and particularly preferably 3.5 or less.

[0101] The above weight-average molecular weight (Mw) and molecular weight distribution (Mw / Mn) are measured by the GPC method described in the examples below.

[0102] The content ratio of the high-Tg segment in the (meth)acrylic block copolymer A is preferably 10% by weight or more, more preferably 20% by weight or more, still more preferably 25% by weight or more, particularly preferably 30% by weight or more, and preferably 95% by weight or less, more preferably 90% by weight or less, still more preferably 85% by weight or less, in 100% by weight of the whole (meth)acrylic block copolymer A.

[0103] The content ratio of the low-Tg segment in the (meth)acrylic block copolymer A is preferably 5% by weight or more, more preferably 10% by weight or more, still more preferably 15% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less, still more preferably 40% by weight or less, particularly preferably 30% by weight or less, in 100% by weight of the whole (meth)acrylic block copolymer A.

[0104] The fact that the low-Tg segment and the content ratio or the ratio thereof of the low-Tg segment are within the above ranges is suitable for the effects of the present invention described above. The content ratio and the ratio thereof of each segment can be calculated from each segment obtained in each step of the RAFT method or the weight average molecular weight (Mw) of the (meth)acrylic block copolymer A, and can be controlled by the charging ratio of the monomers when forming each segment, the polymerization rate of each monomer, etc.

[0105] The content of the (meth)acrylic block copolymer A in the optical adhesive composition A is not particularly limited, but from the viewpoint of obtaining excellent processability at room temperature (25°C) and excellent step absorption property in a region exceeding 50°C, it is preferably 50% by weight or more (for example, 50 to 100% by weight), more preferably 60% by weight or more, still more preferably 80% by weight or more, particularly preferably 90% by weight or more, based on the total amount (total weight, 100% by weight) of the optical adhesive composition A.

[0106] <Colorant> The optical adhesive composition according to the first aspect of the present invention contains a colorant. By containing the colorant in the optical adhesive composition A, the transparency to visible light is reduced. The adhesive layer formed by the optical adhesive composition with reduced transparency to visible light seals the fine step between the metal wiring layer and the light-emitting element (LED chip) of the self-luminous display device (mini / micro LED display device) without gaps, thereby preventing reflection by the metal wiring or the like, preventing color mixing of the light-emitting element (LED chip), and improving the contrast of the image.

[0107] The colorant may be a dye or a pigment as long as it can be dissolved or dispersed in the optical adhesive composition. Dyes are preferred because low haze can be achieved even with a small amount of addition, and they are easily and uniformly distributed without sedimentation like pigments. Also, pigments are preferred because high color expressibility can be achieved even with a small amount of addition. When using a pigment as the colorant, it is preferably one with low or no conductivity. Also, when using a dye, it is preferably used in combination with an antioxidant or the like described later.

[0108] As the colorant, as long as it absorbs visible light (wavelength 400 to 700 nm), those showing transparency to ultraviolet light (wavelength 330 to 400 nm) or those showing absorbability to ultraviolet light can be used without limitation. The transmittance of the colorant is measured using a solution or dispersion diluted with an appropriate solvent such as tetrahydrofuran (THF) or a dispersion medium (an organic solvent with low absorption in the wavelength range of 330 to 700 nm) so that the transmittance at a wavelength of 400 nm is about 50 to 60%.

[0109] The average transmittance of the colorant in the wavelength range of 400 to 700 nm (visible light region) is, for example, 80% or less, and may also be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less.

[0110] Examples of the black pigment with ultraviolet light permeability include "9050BLACK", "UVBK-0001", etc. manufactured by Tokushi Kasei Co., Ltd. Examples of the black dye with ultraviolet light absorption include "VALIFAST BLACK 3810", "NUBIAN Black PA-2802", etc. manufactured by Orient Chemical Industries Co., Ltd. Examples of the black pigment with ultraviolet light absorption include carbon black, titanium black, etc.

[0111] The content of the colorant in the optical adhesive composition is, for example, about 0.01 to 20 parts by weight with respect to 100 parts by weight of the total amount of monomers used in the preparation of the (meth)acrylic block copolymer A, and may be appropriately set according to the type of the colorant, the color tone and light transmittance of the adhesive layer, etc. The colorant may be added to the composition as a solution or dispersion dissolved or dispersed in an appropriate solvent.

[0112] In addition to the (meth)acrylic block copolymer A and the colorant, the optical adhesive composition A may contain additives as long as the effects of the present invention are not impaired. Examples of such additives include, for example, a polymerization initiator, a silane coupling agent, a solvent, a crosslinking accelerator, a tackifier resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), an antioxidant, a filler, an ultraviolet absorber, an antioxidant, a chain transfer agent, a plasticizer, a softening agent, a surfactant, an antistatic agent, a rust preventive agent, etc. The additives may be used alone or in combination of two or more.

[0113] Examples of the polymerization initiator include a photopolymerization initiator (photoinitiator) and a thermal polymerization initiator. The polymerization initiator may be used alone or in combination of two or more. Since the adhesive layer formed by the optical adhesive composition A has sufficient shape stability, it may not contain a polymerization initiator.

[0114] The photoinitiator is not particularly limited, and examples thereof include benzoin ether-based photoinitiators, acetophenone-based photoinitiators, α-ketol-based photoinitiators, aromatic sulfonyl chloride-based photoinitiators, photoactive oxime-based photoinitiators, benzoin-based photoinitiators, benzyl-based photoinitiators, benzophenone-based photoinitiators, ketal-based photoinitiators, and thioxanthone-based photoinitiators.

[0115] Examples of the benzoin ether-based photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, anisole methyl ether, and the like. Examples of the acetophenone-based photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloroacetophenone, and the like. Examples of the α-ketol-based photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one, and the like. Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalenesulfonyl chloride, and the like. Examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime, and the like. Examples of the benzoin-based photopolymerization initiator include benzoin, and the like. Examples of the benzyl-based photopolymerization initiator include benzyl, and the like. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoyl benzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal-based photopolymerization initiator include benzyldimethyl ketal, and the like. Examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

[0116] When the photoinitiator is used, the amount used is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.05 to 0.5 part by weight, based on 100 parts by weight of the monomer component constituting the (meth)acrylic block copolymer A.

[0117] Examples of the thermal polymerization initiator include azo polymerization initiators, peroxide polymerization initiators (e.g., dibenzoyl peroxide, tert-butyl permaleate, etc.), and redox polymerization initiators. Among them, azo polymerization initiators are preferred. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid)dimethyl, 4,4'-azobis-4-cyanovaleric acid, and the like.

[0118] When the azo polymerization initiator is used, the amount used is not particularly limited, but is preferably 0.05 to 0.5 part by weight, more preferably 0.1 to 0.3 part by weight, based on 100 parts by weight of the monomer component constituting the (meth)acrylic block copolymer A.

[0119] The optical adhesive composition A may contain a silane coupling agent as long as the effects of the present invention are not impaired. When the optical adhesive composition A contains a silane coupling agent, the adhesion reliability to glass (especially the adhesion reliability to glass under high temperature and high humidity environments) is improved, which is preferable.

[0120] The silane coupling agent is not particularly limited, but γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-phenyl-aminopropyltrimethoxysilane, etc. are preferably mentioned. Among them, γ-glycidoxypropyltrimethoxysilane is preferred. Also, as a commercial product, for example, the product name "KBM-403" (manufactured by Shin-Etsu Chemical Co., Ltd.) can be mentioned. Note that the silane coupling agent may be used alone or in combination of two or more.

[0121] The content of the silane coupling agent in the optical adhesive composition A is not particularly limited, but is preferably 0.01 to 1 part by weight, more preferably 0.03 to 0.5 part by weight, based on 100 parts by weight of the (meth)acrylic block copolymer A.

[0122] Further, the optical adhesive composition A may contain a solvent. The solvent is not particularly limited, and examples thereof include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; and organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. The solvent may be used alone or in combination of two or more.

[0123] The optical adhesive composition A may be an adhesive composition in any form, and examples thereof include an emulsion type, a solvent type (solution type), and a hot melt type (hot melt type). Among them, the solvent type adhesive composition is preferably mentioned as the optical adhesive composition A.

[0124] The method for preparing the optical adhesive composition A is not particularly limited, and examples thereof include known methods. For example, the solvent type optical adhesive composition A is prepared by mixing the (meth)acrylic block copolymer A, a solvent, and components that may be added as necessary (for example, the above-mentioned silane coupling agent, solvent, additive, etc.).

[0125] The storage elastic modulus (G’25) of the optical adhesive composition A at 25°C is not particularly limited, but from the viewpoint of improving the processability at room temperature, it is preferably 1 MPa or more, more preferably 1.5 MPa or more, more preferably 2 MPa or more, more preferably 2.5 MPa or more, more preferably 3 MPa or more, and from the viewpoint of improving the adhesion reliability at room temperature, it is preferably 50 MPa or less, more preferably 45 MPa or less, more preferably 40 MPa or less, more preferably 35 MPa or less, more preferably 30 MPa or less.

[0126] The storage elastic modulus (G’50) of the optical adhesive composition A at 50°C is not particularly limited, but from the viewpoint of improving the step absorption property in the region exceeding 50°C, it is preferably 0.5 MPa or less, more preferably 0.45 MPa or less, more preferably 0.4 MPa or less, more preferably 0.35 MPa or less, more preferably 0.3 MPa or less. From the viewpoint of improving the handleability in the region exceeding 50°C, it is preferably 0.0001 MPa or more, more preferably 0.0005 MPa or more, more preferably 0.001 MPa or more, more preferably 0.005 MPa or more, more preferably 0.01 MPa or more.

[0127] The ratio (G’25 / G’50) of the storage elastic modulus of the optical adhesive composition A at 25°C to the storage elastic modulus at 50°C is not particularly limited, but from the viewpoints of improving the processability at room temperature and the step absorption property in the region exceeding 50°C, it is preferably 3 or more, more preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, particularly preferably 20 or more. From the viewpoints of adhesive reliability, handleability, etc., it is preferably 100 or less, more preferably 95 or less, more preferably 90 or less, still more preferably 85 or less, particularly preferably 80 or less.

[0128] The storage elastic modulus (G’25) at 25°C, the storage elastic modulus (G’25) at 50°C, and their ratio (G’25 / G’50) are measured by the dynamic viscoelasticity measurement described in the examples below.

[0129] Hereinafter, embodiments of the present invention will be described in relation to the drawings, but the present invention is not limited thereto and is merely illustrative.

[0130] [Adhesive layer] The pressure-sensitive adhesive layer of the second aspect of the present invention is formed from the optical pressure-sensitive adhesive composition A. In this specification, the pressure-sensitive adhesive layer formed from the optical pressure-sensitive adhesive composition A may be referred to as "pressure-sensitive adhesive layer A". FIG. 1 is a schematic diagram (cross-sectional view) showing an embodiment of the pressure-sensitive adhesive layer A of the second aspect of the present invention. In FIG. 1, 2 is the pressure-sensitive adhesive layer A, and S1 and S2 are release films.

[0131] The pressure-sensitive adhesive layer 2 (pressure-sensitive adhesive layer A) may have release films (separators) S1 and S2 provided on the adhesive surface until use. The form in which the adhesive surface of the pressure-sensitive adhesive layer 2 is protected by the release films S1 and S2 is not particularly limited, but may be a form in which each adhesive surface is protected by two release films S1 and S2, or by being wound in a roll shape, a single release film with both sides being release surfaces, and each adhesive surface being protected. The release films S1 and S2 are used as protective materials for the pressure-sensitive adhesive layer 2 and are peeled off when pasted onto an adherend. In the pressure-sensitive adhesive layer 2, the release films S1 and S2 also serve as a support for the pressure-sensitive adhesive layer 2. Note that the release films S1 and S2 do not necessarily have to be provided.

[0132] The pressure-sensitive adhesive layer A is not particularly limited, but is formed by applying (coating) the optical pressure-sensitive adhesive composition A onto a suitable support such as a base material or a release film, and heating and drying and / or curing as necessary. For example, when forming the optical pressure-sensitive adhesive layer A from a solvent-type optical pressure-sensitive adhesive composition A, the optical pressure-sensitive adhesive composition A is applied (coated) onto a support and formed by heating and drying. The adhesive surface formed after heating and drying may be protected by a release film or the like.

[0133] The release film is not particularly limited, and examples thereof include a base material having a release treatment layer, a low-adhesion base material made of a fluoropolymer, and a low-adhesion base material made of a nonpolar polymer. Examples of the base material having the release treatment layer include a plastic film or paper surface-treated with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide. Examples of the fluoropolymer in the low-adhesion base material made of the fluoropolymer include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer, and the like. Examples of the nonpolar polymer include olefin resins (e.g., polyethylene, polypropylene, etc.). Note that the separator is formed by a known or conventional method. Also, the thickness of the separator is not particularly limited.

[0134] In addition, a known coating method may be used for the above coating (painting). For example, a conventional coater, specifically, a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater, etc. may be used.

[0135] The gel fraction of the pressure-sensitive adhesive layer A is 50 to 90% by weight, preferably 50 to 80% by weight, and more preferably 50 to 70% by weight. By setting the gel fraction to 90% by weight or less, the cohesive force of the pressure-sensitive adhesive layer A becomes somewhat smaller, and the pressure-sensitive adhesive layer A becomes softer, so that the pressure-sensitive adhesive layer can easily follow the stepped portion, and excellent stepped absorption can be obtained. On the other hand, by setting the gel fraction to 50% by weight or more, the problem that the pressure-sensitive adhesive layer becomes too soft and the processability of the pressure-sensitive adhesive sheet decreases can be suppressed, and the generation of bubbles and floating can be suppressed in a high-temperature environment or a high-temperature and high-humidity environment, and the adhesion reliability can be improved. The gel fraction can be controlled, for example, by the type and content (usage amount) of the above cross-linking agent.

[0136] The above gel fraction (ratio of solvent-insoluble content) can be determined as the ethyl acetate-insoluble content. Specifically, it is determined as the weight fraction (unit: wt%) of the insoluble content after immersing the adhesive layer in ethyl acetate at room temperature (23°C) for 7 days with respect to the sample before immersion. More specifically, the above gel fraction is a value calculated by the following "Method for Measuring Gel Fraction". (Method for Measuring Gel Fraction) Collect about 1 g of the adhesive layer, measure its weight, and regard this weight as the "weight of the adhesive layer before immersion". Next, after immersing the collected adhesive layer in 40 g of ethyl acetate for 7 days, collect all the components (insoluble parts) that are insoluble in ethyl acetate, dry the collected total insoluble parts at 130°C for 2 hours to remove ethyl acetate, and then measure its weight to obtain the "dry weight of the insoluble part" (weight of the adhesive layer after immersion). Then, substitute the obtained numerical values into the following formula for calculation. Gel fraction (wt%) = [(dry weight of the insoluble part) / (weight of the adhesive layer before immersion)] × 100

[0137] Also, the melting point of the adhesive layer A is not particularly limited, but it is preferably -60 to 20°C, more preferably -40 to 10°C, and even more preferably -30 to 0°C. If the above melting point is higher than 20°C, the adhesive force cannot be exhibited at room temperature.

[0138] The above melting point is not particularly limited. For example, taking the adhesive layer as a measurement sample, it can be measured in accordance with JIS K 7121 by differential scanning calorimetry (DSC). Specifically, for example, as the measuring device, using the "Q-2000" manufactured by TA instruments, it can be measured under the condition of a heating rate of 10°C / min from -80°C to 80°C.

[0139] The thickness of the pressure-sensitive adhesive layer A containing a colorant is not particularly limited, and may be appropriately set to be equal to or greater than the height of the light-emitting element so as to sufficiently seal the light-emitting elements arranged on the display panel described later. For example, the thickness of the pressure-sensitive adhesive layer A containing a colorant is adjusted to be 1.0 to 4.0 times, preferably 1.1 to 3.0 times, more preferably 1.2 to 2.5 times, and still more preferably 1.3 to 2.0 times the height of the light-emitting element. By setting the above thickness to 1.0 times or more, the pressure-sensitive adhesive layer A easily follows the step, and the step absorption property is improved. Further, by setting the above thickness to 4.0 or less, deformation of the pressure-sensitive adhesive layer A hardly occurs, and the processability is improved.

[0140] The thickness of the pressure-sensitive adhesive layer A containing a colorant is, for example, about 10 to 500 μm, and may be 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The thickness of the pressure-sensitive adhesive layer A containing a colorant may be 400 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. By setting the above thickness to 10 μm or more, the pressure-sensitive adhesive layer A easily follows the stepped portion, and the step absorption property is improved. Further, by setting the above thickness to 500 μm or less, deformation of the pressure-sensitive adhesive layer A hardly occurs, and the processability is improved.

[0141] The average transmittance of the pressure-sensitive adhesive layer A containing a colorant in the wavelength range of 400 to 700 nm (visible light region) is, for example, 80% or less, and may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less.

[0142] The storage elastic modulus (G’25) of the pressure-sensitive adhesive layer A at 25°C is not particularly limited, but from the viewpoint of improving processability at room temperature, it is preferably 1 MPa or more, more preferably 1.5 MPa or more, more preferably 2 MPa or more, more preferably 2.5 MPa or more, and more preferably 3 MPa or more. From the viewpoint of improving adhesive reliability at room temperature, it is preferably 50 MPa or less, more preferably 45 MPa or less, more preferably 40 MPa or less, more preferably 35 MPa or less, and more preferably 30 MPa or less.

[0143] The storage elastic modulus (G’50) of the adhesive layer A at 50°C is not particularly limited, but from the viewpoint of improving the step absorbability in the region exceeding 50°C, it is preferably 0.5 MPa or less, more preferably 0.45 MPa or less, more preferably 0.4 MPa or less, more preferably 0.35 MPa or less, more preferably 0.3 MPa or less. From the viewpoint of improving the handleability in the region exceeding 50°C, it is preferably 0.0001 MPa or more, more preferably 0.0005 MPa or more, more preferably 0.001 MPa or more, more preferably 0.005 MPa or more, more preferably 0.01 MPa or more.

[0144] The ratio (G’25 / G’50) of the storage elastic modulus of the adhesive layer A at 25°C to the storage elastic modulus at 50°C is not particularly limited, but from the viewpoint of improving the processability at room temperature and the step absorbability in the region exceeding 50°C, it is preferably 3 or more, more preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, particularly preferably 20 or more. From the viewpoints of adhesion reliability, handleability, etc., it is preferably 100 or less, more preferably 95 or less, more preferably 90 or less, still more preferably 85 or less, particularly preferably 80 or less.

[0145] In addition, the storage elastic modulus (G’25) at 25°C, the storage elastic modulus (G’25) at 50°C, and the ratio (G’25 / G’50) thereof are measured by dynamic viscoelasticity measurement.

[0146] The adhesive layer A of the present invention may be a constituent member of an adhesive sheet (which may be referred to as "adhesive sheet A" in this specification). That is, the adhesive sheet A is an adhesive sheet having at least one layer of the adhesive layer A. Note that the "adhesive sheet" includes the meaning of "adhesive tape". That is, the adhesive sheet A may be an adhesive tape having a tape-like form.

[0147] The pressure-sensitive adhesive sheet A may be a single-sided pressure-sensitive adhesive sheet in which only one side of the sheet is the surface of the pressure-sensitive adhesive layer (adhesive surface) (i.e., the surface of the pressure-sensitive adhesive layer A), or it may be a double-sided pressure-sensitive adhesive sheet in which both sides of the sheet are the surfaces of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet A is not particularly limited, but from the viewpoint of using it for bonding adherends to each other, etc., it is preferably a double-sided pressure-sensitive adhesive sheet, and more preferably a double-sided pressure-sensitive adhesive sheet in which both sides of the sheet are the surfaces of the pressure-sensitive adhesive layer A.

[0148] The pressure-sensitive adhesive sheet A may be a pressure-sensitive adhesive sheet having no base material (base material layer), a so-called "base material-less type" pressure-sensitive adhesive sheet (sometimes referred to as a "base material-less pressure-sensitive adhesive sheet"), or it may be a pressure-sensitive adhesive sheet having a base material (sometimes referred to as a "pressure-sensitive adhesive sheet with a base material"). Examples of the above base material-less pressure-sensitive adhesive sheet include a double-sided pressure-sensitive adhesive sheet composed only of the pressure-sensitive adhesive layer A, and a double-sided pressure-sensitive adhesive sheet composed of the pressure-sensitive adhesive layer A and a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer A (sometimes referred to as an "other pressure-sensitive adhesive layer"). Examples of the pressure-sensitive adhesive sheet having a base material include a single-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer A on one side of the base material, a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer A on both sides of the base material, and a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer A on one side of the base material and another pressure-sensitive adhesive layer on the other side of the base material.

[0149] Among the above, from the viewpoint of improving optical physical properties such as transparency, a base material-less pressure-sensitive adhesive sheet is preferred, and more preferably, a double-sided pressure-sensitive adhesive sheet having no base material (base material-less double-sided pressure-sensitive adhesive sheet) composed only of the pressure-sensitive adhesive layer A. Further, when the pressure-sensitive adhesive sheet A is a pressure-sensitive adhesive sheet having a base material, it is not particularly limited, but from the viewpoint of processability, it is preferably a double-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer A on both sides of the base material (double-sided pressure-sensitive adhesive sheet with a base material).

[0150] Note that the above "base material (base material layer)" is the portion that is attached to the adherend (such as an optical member) together with the pressure-sensitive adhesive layer when the pressure-sensitive adhesive sheet A is used (attached) to the adherend, and does not include the release film (separator) that is peeled off when the pressure-sensitive adhesive sheet is used (attached).

[0151] The pressure-sensitive adhesive sheet A may be a pressure-sensitive adhesive sheet with a substrate as described above. Examples of such a substrate include various optical films such as plastic films, antireflection (AR) films, polarizing plates, and retardation plates. Examples of materials such as the above plastic films include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, cyclic olefin polymers such as the trade name "Arton" (manufactured by JSR Corporation), and the trade name "Zeonoa" (manufactured by Nippon Zeon Co., Ltd.). These plastic materials may be used alone or in combination of two or more. In addition, the above "substrate" is a part that is attached to the adherend (such as an optical member) together with the adhesive layer when the pressure-sensitive adhesive sheet is attached to the adherend. The release film (separator) that is peeled off during the use (attachment) of the pressure-sensitive adhesive sheet is not included in the "substrate".

[0152] The substrate is preferably transparent. The total light transmittance (in accordance with JIS K7361-1) of the substrate in the visible light wavelength region is not particularly limited, but is preferably 85% or more, more preferably 88% or more. Also, the haze (in accordance with JIS K7136) of the substrate is not particularly limited, but is preferably 1.5% or less, more preferably 1.0% or less. Examples of such transparent substrates include PET films and non-oriented films such as the trade name "Arton" and the trade name "Zeonoa".

[0153] The thickness of the substrate is not particularly limited, but is preferably 12 to 75 μm. The substrate may have either a single-layer or a multi-layer form. In addition, known and commonly used surface treatments such as physical treatments such as corona discharge treatment and plasma treatment, and chemical treatments such as undercoat treatment may be appropriately applied to the surface of the substrate.

[0154] The pressure-sensitive adhesive sheet A may have other pressure-sensitive adhesive layers (pressure-sensitive adhesive layers other than the pressure-sensitive adhesive layer A). The other pressure-sensitive adhesive layers are not particularly limited, and examples thereof include pressure-sensitive adhesive layers formed from known or commonly used pressure-sensitive adhesives such as urethane-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives. The pressure-sensitive adhesives may be used alone or in combination of two or more.

[0155] In addition to the pressure-sensitive adhesive layer A, other adhesive layers, and the base material, the pressure-sensitive adhesive sheet A may have other layers (for example, an intermediate layer, an undercoat layer, etc.) as long as the effects of the present invention are not impaired.

[0156] Until use, a release film (separator) may be provided on the adhesive surface of the pressure-sensitive adhesive sheet A. The form in which the adhesive surface of the optical pressure-sensitive adhesive sheet A is protected by the release film is not particularly limited, and may be a form in which each adhesive surface is protected by two release films, or a form in which both surfaces are protected by a single release film with a release surface, by being wound in a roll shape. The release film is used as a protective material for the pressure-sensitive adhesive layer and is peeled off when attached to the adherend. In the pressure-sensitive adhesive sheet A, the release film also serves as a support for the pressure-sensitive adhesive layer. Note that the release film does not necessarily have to be provided.

[0157] Examples of the method for manufacturing the pressure-sensitive adhesive sheet A include known or commonly used manufacturing methods. The manufacturing method of the pressure-sensitive adhesive sheet A varies depending on the composition of the pressure-sensitive adhesive layer A and the like, and is not particularly limited. For example, methods such as the following (1) to (3) can be mentioned. (1) An optical pressure-sensitive adhesive composition A containing a (meth)acrylic block copolymer A, a colorant, and, if necessary, a silane coupling agent and other additives is applied (coated) on a base material or a separator and cured (for example, thermally cured) to produce the pressure-sensitive adhesive sheet A. (2) An optical adhesive composition A (solution) obtained by dissolving a (meth)acrylic block copolymer A, a colorant, and, if necessary, additives, etc. in a solvent is applied (coated) onto a substrate or a separator, and dried and / or cured to produce an adhesive sheet. (3) The adhesive sheet A produced in the above (1) is further dried.

[0158] The adhesive sheet A is not particularly limited, but from the viewpoint of productivity, it is preferably an adhesive sheet produced by utilizing a heat curing reaction with an optical adhesive composition A containing a (meth)acrylic block copolymer A and a polymerization initiator (such as a thermal polymerization initiator).

[0159] The thickness (total thickness) of the adhesive sheet A is not particularly limited, but is preferably 10 μm to 1 mm, more preferably 100 to 500 μm, and even more preferably 150 to 350 μm. By setting the above thickness to 10 μm or more, the adhesive layer can easily follow the stepped portion, and the stepped absorption property can be improved. Note that the thickness of the adhesive sheet A does not include the thickness of the release film.

[0160] Since the adhesive sheet A has an adhesive layer A, it has excellent processability at room temperature. Also, since the adhesive sheet A has an adhesive layer A, it has excellent stepped absorption property in a region exceeding 50°C. For example, in addition to a step of 5 to 10 μm, it also has excellent stepped absorption property for a high step exceeding 40 μm. Furthermore, it also has stepped absorption property for a high step exceeding 80 μm. Furthermore, since the adhesive sheet A has an adhesive layer A, it has excellent adhesion reliability.

[0161] [Optical laminate] The optical laminate according to the third aspect of the present invention includes a base material and an adhesive layer A. FIGS. 2 to 4 are schematic diagrams (cross-sectional views) showing an embodiment of the optical laminate according to the third aspect of the present invention. In FIG. 2, the optical laminate 20 has a laminated structure in which a base material 1 and an adhesive layer 2 (adhesive layer A) are laminated. In FIG. 3, in the optical laminate 21, an antireflection treatment and / or an antiglare treatment 3 is applied to the surface 1a of the base material 1 where the adhesive layer 2 is not laminated. In FIG. 4, in the optical laminate 22, an antiglare layer 3a is formed as an antireflection treatment and / or an antiglare treatment on the surface 1a of the base material 1 where the adhesive layer 2 is not laminated.

[0162] With the optical laminate of the present embodiment, the adhesive layer 2 serves as a sealing material for sealing light-emitting elements arranged on the display panel, and the base material 1 serves as the outermost cover member. Therefore, there is no need to separately laminate a cover member after sealing, the number of processes and the required members can be reduced, and the manufacturing efficiency is improved.

[0163] <Base material> In the present embodiment, the substrate 1 is not particularly limited, and examples thereof include a glass or a transparent plastic film substrate. The transparent plastic film substrate is not particularly limited, but preferably has excellent visible light transmittance and excellent transparency (preferably having a haze value of 5% or less), and examples thereof include the transparent plastic film substrate described in JP-A-2008-90263. As the transparent plastic film substrate, those having less optical birefringence are preferably used. In the present embodiment, the substrate 1 can also be used, for example, as a cover member of a self-luminous display device. In this case, as the transparent plastic film substrate, a film formed from triacetyl cellulose (TAC), polycarbonate, an acrylic polymer, a polyolefin having a cyclic or norbornene structure, or the like is preferable. Further, in the present embodiment, the substrate 1 may be the cover member itself. With such a configuration, in the manufacture of a self-luminous display device, the step of separately laminating the cover member can be reduced, so that the number of steps and the necessary members can be reduced, and the production efficiency can be improved. Further, with such a configuration, the cover member can be made thinner. When the substrate 1 is a cover member, the surface 1a subjected to an antireflection treatment and / or an antiglare treatment becomes the outermost surface of the self-luminous display device, and serves to prevent a decrease in visibility due to reflection of external light or reflection of an image, and to adjust the appearance such as glossiness.

[0164] In the present embodiment, the thickness of the substrate 1 is not particularly limited. However, for example, in consideration of workability such as strength and handleability, and thin layer properties, the range of 10 to 500 μm is preferable, more preferably the range of 20 to 300 μm, and optimally the range of 30 to 200 μm. The refractive index of the substrate 1 is not particularly limited, but is, for example, in the range of 1.30 to 1.80, preferably in the range of 1.40 to 1.70. The visible light transmittance of the substrate 1 is not particularly limited, but is, for example, 85 to 100%, and may be 88% or more, 90% or more, or 92% or more.

[0165] In the present embodiment, it is preferable that the surface 1a of the base material 1 is subjected to a reflective surface treatment and / or an antiglare treatment 3. When the surface 1a of the base material 1 is subjected to a reflective surface treatment and / or an antiglare treatment 3, the surface 1a becomes the outermost surface of the self-luminous display device, preventing a decrease in visibility due to reflection of external light or reflection of an image, or adjusting the appearance such as glossiness. An antiglare treatment that is easy to manufacture and has a low cost is preferable.

[0166] As the antireflection (AR) treatment, a known AR treatment can be applied without particular limitation. Specifically, it can be carried out by forming an optical thin film with strictly controlled thickness and refractive index or an antireflection layer (AR layer) in which two or more layers of the optical thin film are laminated on one surface 1a of the base material 1. The AR layer exhibits an antireflection function by using the interference effect of light to cancel out the reversed phases of the incident light and the reflected light. The wavelength range of visible light for which the antireflection function is exhibited is, for example, 380 to 780 nm, and particularly the wavelength range with high visual sensitivity is in the range of 450 to 650 nm. It is preferable to design the AR layer so as to minimize the reflectance at the central wavelength of 550 nm.

[0167] Generally, examples of the AR layer include a multilayer antireflection layer having a structure in which two to five optical thin layers (thin films with strictly controlled thickness and refractive index) are laminated. By forming a plurality of layers of components with different refractive indices by a predetermined thickness, the degree of freedom in the optical design of the AR layer is increased, the antireflection effect can be further improved, and the spectral reflection characteristics can also be made uniform (flat) in the visible light region. In the optical thin film, since high thickness accuracy is required, generally, the formation of each layer is carried out by a dry method such as vacuum deposition, sputtering, CVD, etc.

[0168] As the antiglare (AG) treatment, known AG treatments can be applied without particular limitation. For example, it can be carried out by forming an antiglare layer on one side 1a of the base material 1. FIG. 2 is a schematic diagram (cross-sectional view) showing another embodiment of the optical laminate of the first aspect of the present invention. In the optical laminate 11 of the present embodiment, an antiglare layer 3a is formed on one side 1a of the base material 1. As the antiglare layer 3a, known ones can be adopted without limitation, and generally, it is formed as a layer in which inorganic or organic particles are dispersed as an antiglare agent in a resin.

[0169] In the present embodiment, the antiglare layer 3a is formed using an antiglare layer forming material containing a resin, particles, and a thixotropy imparting agent. By the aggregation of the particles and the thixotropy imparting agent, convex portions are formed on the surface of the antiglare layer 3a. With this configuration, the antiglare layer 3a has excellent display characteristics that achieve both antiglare properties and prevention of white blur. Moreover, despite forming the antiglare layer by utilizing the aggregation of particles, it is possible to prevent the generation of protrusions on the surface of the antiglare layer that would be an appearance defect and improve the product yield.

[0170] Examples of the resin include thermosetting resins and radiation curable resins that cure with ultraviolet rays or light. It is also possible to use commercially available thermosetting resins, ultraviolet curable resins, etc. as the resin.

[0171] Examples of the thermosetting resin and ultraviolet curable resin include curable compounds having at least one of acrylate groups and methacrylate groups that cure with heat, light (such as ultraviolet rays), or electron beams. For example, silicone resins, polyester resins, polyether resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, oligomers or prepolymers such as acrylates and methacrylates of polyfunctional compounds such as polythiol polyene resins and polyhydric alcohols can be mentioned. These may be used alone or in combination of two or more.

[0172] For the resin, for example, a reactive diluent having at least one of an acrylate group and a methacrylate group can also be used. As the reactive diluent, for example, the reactive diluents described in JP-A-2008-88309 can be used, and include, for example, monofunctional acrylate, monofunctional methacrylate, polyfunctional acrylate, polyfunctional methacrylate, and the like. As the reactive diluent, acrylate having three or more functional groups and methacrylate having three or more functional groups are preferable. This is because the hardness of the antiglare layer 3a can be made excellent. Examples of the reactive diluent also include butanediol glycerin ether diacrylate, acrylate of isocyanuric acid, methacrylate of isocyanuric acid, and the like. These may be used alone or in combination of two or more.

[0173] The particles for forming the antiglare layer 3a mainly function to impart antiglare properties by making the surface of the formed antiglare layer 3a uneven, and to control the haze value of the antiglare layer 3a. The haze value of the antiglare layer 3a can be designed by controlling the refractive index difference between the particles and the resin. Examples of the particles include inorganic particles and organic particles. The inorganic particles are not particularly limited, and examples include silicon oxide particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, tin oxide particles, calcium carbonate particles, barium sulfate particles, talc particles, kaolin particles, calcium sulfate particles, and the like. The organic particles are not particularly limited, and examples include polymethyl methacrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polytetrafluoroethylene resin powder, and the like. These inorganic particles and organic particles may be used alone or in combination of two or more.

[0174] The weight average particle size (D) of the particles is preferably in the range of 2.5 to 10 μm. By setting the weight average particle size of the particles within the above range, for example, the antiglare property can be more excellent and white blooming can be prevented. The weight average particle size of the particles is more preferably in the range of 3 to 7 μm. The weight average particle size of the particles can be measured, for example, by the Coulter counter method. For example, using a particle size distribution measuring device utilizing the pore electrical resistance method (trade name: Coulter Multisizer, manufactured by Beckman Coulter, Inc.), the number and volume of the particles are measured by measuring the electrical resistance of the electrolytic solution corresponding to the volume of the particles when the particles pass through the pores, and the weight average particle size is calculated.

[0175] The shape of the particles is not particularly limited. For example, it may be bead-shaped and substantially spherical, or may be amorphous such as powder. However, a substantially spherical shape is preferred, more preferably substantially spherical particles with an aspect ratio of 1.5 or less, and most preferably spherical particles.

[0176] The proportion of the particles in the antiglare layer 3a is preferably in the range of 0.2 to 12 parts by weight, more preferably in the range of 0.5 to 12 parts by weight, and even more preferably in the range of 1 to 7 parts by weight with respect to 100 parts by weight of the resin. By setting the proportion within the above range, for example, the antiglare property can be more excellent and white blooming can be prevented.

[0177] Examples of the thixotropy imparting agent for forming the antiglare layer 3a include organic clay, oxidized polyolefin, modified urea, and the like.

[0178] The organic clay is preferably an organically treated clay in order to improve its affinity with the resin. Examples of the organic clay include layered organic clay. The organic clay may be self-prepared or a commercially available product may be used. Examples of the commercially available products include Lucentite SAN, Lucentite STN, Lucentite SEN, Lucentite SPN, Somasil ME-100, Somasil MAE, Somasil MTE, Somasil MEE, Somasil MPE (trade names, all manufactured by Coop Chemical Co., Ltd.); Esben, Esben C, Esben E, Esben W, Esben P, Esben WX, Esben N-400, Esben NX, Esben NX80, Esben NO12S, Esben NEZ, Esben NO12, Esben NE, Esben NZ, Esben NZ70, Organite, Organite D, Organite T (trade names, all manufactured by Hoejun Co., Ltd.); Kunipia F, Kunipia G, Kunipia G4 (trade names, all manufactured by Kunimine Industries Co., Ltd.); Thixogel VZ, Clayton HT, Clayton 40 (trade names, all manufactured by Rockwood Additives), and the like.

[0179] The oxidized polyolefin may be self-prepared or a commercially available product may be used. Examples of the commercially available products include Disparlon 4200-20 (trade name, manufactured by Kusumoto Chemicals, Ltd.), Flowonon SA300 (trade name, manufactured by Kyoeisha Chemical Co., Ltd.), and the like.

[0180] The modified urea is a reaction product of an isocyanate monomer or its adduct and an organic amine. The modified urea may be self-prepared or a commercially available product may be used. Examples of the commercially available products include BYK410 (manufactured by Big Chemie), and the like.

[0181] The thixotropy imparting agent may be used alone or in combination of two or more kinds.

[0182] In the optical laminate 11 of the present embodiment, it is preferable that the height of the anti-glare layer 3a of the convex portion from the roughness average line is less than 0.4 times the thickness of the anti-glare layer 3a. More preferably, it is in the range of 0.01 times or more and less than 0.4 times, and still more preferably, it is in the range of 0.01 times or more and less than 0.3 times. If it is in this range, it is possible to preferably prevent the formation of protrusions that cause appearance defects on the convex portion. The anti-glare layer 3a of the present embodiment can be less likely to cause appearance defects by having convex portions with such a height. Here, the height from the average line can be measured, for example, by the method described in JP-A-2017-138620.

[0183] The ratio of the thixotropy-imparting agent in the anti-glare layer 3a is preferably in the range of 0.1 to 5 parts by weight, more preferably in the range of 0.2 to 4 parts by weight, based on 100 parts by weight of the resin.

[0184] The thickness (d) of the anti-glare layer 3a is not particularly limited, but is preferably in the range of 3 to 12 μm. By setting the thickness (d) of the anti-glare layer 3a within the above range, for example, the occurrence of curl of the optical laminate 11 can be prevented, and problems such as a decrease in productivity such as poor transportability can be avoided. Further, when the thickness (d) is within the above range, the weight average particle diameter (D) of the particles is preferably within the range of 2.5 to 10 μm as described above. By having the thickness (d) of the anti-glare layer 3a and the weight average particle diameter (D) of the particles in the above combination, the anti-glare property can be further improved. The thickness (d) of the anti-glare layer 3a is more preferably in the range of 3 to 8 μm.

[0185] The relationship between the thickness (d) of the anti-glare layer 3a and the weight average particle diameter (D) of the particles is preferably in the range of 0.3 ≦ D / d ≦ 0.9. By being in such a relationship, the anti-glare property can be further improved, white blur can be prevented, and an anti-glare layer without appearance defects can be obtained.

[0186] In the optical laminate 11 of the present embodiment, as described above, in the antiglare layer 3a, convex portions are formed on the surface of the antiglare layer 3a due to the aggregation of the particles and the thixotropy imparting agent. In the aggregated portions forming the convex portions, the particles exist in a state where a plurality of them are gathered in the plane direction of the antiglare layer 3a. As a result, the convex portions have a gentle shape. By having convex portions of such a shape, the antiglare layer 3a of the present embodiment can maintain antiglare properties, prevent white blur, and further make it less likely to cause appearance defects.

[0187] The surface shape of the antiglare layer 3a can be arbitrarily designed by controlling the aggregation state of the particles contained in the antiglare layer forming material. The aggregation state of the particles can be controlled, for example, by the material of the particles (e.g., the chemical modification state of the particle surface, the affinity for solvents and resins, etc.), the type and combination of the resin (binder) or solvent. Here, in the present embodiment, the aggregation state of the particles can be controlled by the thixotropy imparting agent contained in the antiglare layer forming material. As a result, in the present embodiment, the aggregation state of the particles can be made as described above, and the convex portions can be made to have a gentle shape.

[0188] In the optical laminate 11 of the present embodiment, when the base material 1 is formed of a resin or the like, it is preferable to have a penetration layer at the interface between the base material 1 and the antiglare layer 3a. The penetration layer is formed by the resin component contained in the forming material of the antiglare layer 3a penetrating into the base material 1. When the penetration layer is formed, the adhesion between the base material 1 and the antiglare layer 3a can be improved, which is preferable. The thickness of the penetration layer is preferably in the range of 0.2 to 3 μm, more preferably in the range of 0.5 to 2 μm. For example, when the base material 1 is triacetyl cellulose and the resin contained in the antiglare layer 3a is an acrylic resin, the penetration layer can be formed. The penetration layer can be confirmed, for example, by observing a cross-section of the optical laminate 11 with a transmission electron microscope (TEM), and the thickness can be measured.

[0189] In this embodiment, even when applied to the optical laminate 11 having such a penetration layer, a desired gentle surface uneven shape that achieves both antiglare property and prevention of white blur can be easily formed. The penetration layer is preferably formed thick for improving the adhesion, as the base material 1 having poor adhesion to the antiglare layer 3a is thinner.

[0190] In this embodiment, in the antiglare layer 3a, the number of appearance defects having a maximum diameter of 200 μm or more is preferably 1 or less per 1 m 2 of the antiglare layer 3a. More preferably, there are no such appearance defects.

[0191] In this embodiment, the base material 1 on which the antiglare layer 3a is formed preferably has a haze value in the range of 0 to 10%. The haze value is the haze value (cloudiness) according to JIS K 7136 (2000 edition). The haze value is more preferably in the range of 0 to 5%, and even more preferably in the range of 0 to 3%. In order to make the haze value in the above range, it is preferable to select the particles and the resin so that the refractive index difference between the particles and the resin is in the range of 0.001 to 0.02. When the haze value is in the above range, a clear image can be obtained and the contrast in a dark place can be improved.

[0192] In this embodiment, in the uneven shape on the surface of the antiglare layer 3a, the average inclination angle θa (°) is preferably in the range of 0.1 to 5.0, more preferably in the range of 0.3 to 4.5, even more preferably in the range of 1.0 to 4.0, and particularly preferably 1.6 to 4.0. Here, the average inclination angle θa is a value defined by the following mathematical formula (1). The average inclination angle θa is, for example, a value measured by the method described in JP-A-2017-138620. Average inclination angle θa = tan-1Δa (1)

[0193] In the formula (1), Δa is, as shown in the following formula (2), the value obtained by dividing the sum (h1 + h2 + h3 ··· + hn) of the differences (height h) between the peaks of adjacent ridges and the lowest points of valleys by the reference length L of the roughness curve defined in JIS B 0601 (1994 edition). The roughness curve is a curve obtained by removing surface undulation components longer than a predetermined wavelength from the cross-sectional curve using a phase difference compensation type high-pass filter. The cross-sectional curve is the contour that appears at the cut surface when the target surface is cut by a plane perpendicular to the target surface. Δa = (h1 + h2 + h3 ··· + hn) / L (2)

[0194] When θa is within the above range, the antiglare property is more excellent and white blur can be prevented.

[0195] When forming the antiglare layer 3a, it is preferable that the prepared antiglare layer forming material (coating liquid) exhibits thixotropy, and the Ti value defined below is preferably in the range of 1.3 to 3.5, more preferably in the range of 1.3 to 2.8. Ti value = β1 / β2 Here, β1 is the viscosity measured under the condition of a shear rate of 20 (1 / s) using a Rheostress 6000 manufactured by HAAKE, and β2 is the viscosity measured under the condition of a shear rate of 200 (1 / s) using a Rheostress 6000 manufactured by HAAKE.

[0196] When the Ti value is less than 1.3, appearance defects are likely to occur, and the properties regarding antiglare and white blur deteriorate. Also, when the Ti value exceeds 3.5, the particles are less likely to aggregate and tend to be in a dispersed state.

[0197] The manufacturing method of the antiglare layer 3a of the present embodiment is not particularly limited and may be manufactured by any method. For example, an antiglare layer forming material (coating liquid) containing the resin, the particles, the thixotropy imparting agent, and the solvent is prepared, the antiglare layer forming material (coating liquid) is applied to one side 1a of the base material 1 to form a coating film, and the coating film is cured to form the antiglare layer 3a, whereby it can be manufactured. In the present embodiment, a transfer method using a mold, a method of imparting an uneven shape by an appropriate method such as sandblasting or an embossing roll, etc. can also be used together.

[0198] The solvent is not particularly limited, and various solvents can be used. One type may be used alone, or two or more types may be used in combination. There are optimal solvent types and solvent ratios depending on the composition of the resin, the types and contents of the particles and the thixotropy imparting agent, etc. The solvent is not particularly limited, but for example, alcohols such as methanol, ethanol, isopropyl alcohol, butanol, 2-methoxyethanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone; esters such as methyl acetate, ethyl acetate, butyl acetate; ethers such as diisopropyl ether, propylene glycol monomethyl ether; glycols such as ethylene glycol, propylene glycol; cellosolves such as ethyl cellosolve, butyl cellosolve; aliphatic hydrocarbons such as hexane, heptane, octane; aromatic hydrocarbons such as benzene, toluene, xylene, etc. can be mentioned.

[0199] When, for example, triacetyl cellulose (TAC) is adopted as the base material 1 to form the permeation layer, a good solvent for TAC can be preferably used. Examples of the solvent include ethyl acetate, methyl ethyl ketone, cyclopentanone, etc.

[0200] Also, by appropriately selecting a solvent, the thixotropy of the anti-glare layer forming material (coating liquid) by the thixotropy imparting agent can be favorably exhibited. For example, when using organic clay, toluene and xylene can be preferably used alone or in combination. For example, when using polyolefin oxide, methyl ethyl ketone, ethyl acetate, and propylene glycol monomethyl ether can be preferably used alone or in combination. For example, when using modified urea, butyl acetate and methyl isobutyl ketone can be preferably used alone or in combination.

[0201] Various leveling agents can be added to the anti-glare layer forming material. As the leveling agent, for the purpose of preventing coating unevenness (uniformizing the coating surface), for example, a fluorine-based or silicone-based leveling agent can be used. In this embodiment, when antifouling property is required on the surface of the anti-glare layer 3a, or when a layer including an antireflection layer (low refractive index layer) or an interlayer filler is formed on the anti-glare layer 3a, etc., a leveling agent can be appropriately selected accordingly. In this embodiment, for example, since the thixotropy can be exhibited in the coating liquid by including the thixotropy imparting agent, coating unevenness is less likely to occur. Therefore, this embodiment has an advantage, for example, that the options for the leveling agent can be expanded.

[0202] The blending amount of the leveling agent is, for example, 5 parts by weight or less, preferably in the range of 0.01 to 5 parts by weight with respect to 100 parts by weight of the resin.

[0203] To the anti-glare layer forming material, pigments, fillers, dispersants, plasticizers, ultraviolet absorbers, surfactants, antifouling agents, antioxidants, etc. may be added as necessary within a range that does not impair the performance. These additives may be used alone or in combination of two or more kinds.

[0204] As the anti-glare layer forming material, a conventionally known photopolymerization initiator as described in, for example, Japanese Patent Application Laid-Open No. 2008-88309 can be used.

[0205] The anti-glare layer forming material can be applied to one surface 1a of the substrate 1 by a coating method such as fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, or bar coating.

[0206] The anti-glare layer-forming material is applied to the substrate 1 to form a coating film, and the coating film is cured. Prior to the curing, it is preferable to dry the coating film. The drying may be, for example, natural drying, air drying by blowing air, heat drying, or a combination of these methods.

[0207] The means for curing the coating film of the anti-glare layer-forming material is not particularly limited, but ultraviolet curing is preferred. The irradiation dose of the energy ray source is 50 to 500 mJ / cm2 as the cumulative exposure dose at an ultraviolet wavelength of 365 nm. 2 The irradiation dose is preferably 50 mJ / cm. 2 If the curing rate is 500 mJ / cm or more, the curing is more sufficient, and the hardness of the formed anti-glare layer is more sufficient. 2 If the content is equal to or less than this, coloring of the formed anti-glare layer can be prevented.

[0208] In this manner, the anti-glare layer 3a can be formed on one surface 1a of the substrate 1. The anti-glare layer 3a may be formed by a manufacturing method other than the above-mentioned method. The hardness of the anti-glare layer 3a of this embodiment is preferably a pencil hardness of 2H or more, although it is also affected by the thickness of the layer.

[0209] In this embodiment, the anti-glare layer 3a may have a multi-layer structure in which two or more layers are laminated.

[0210] In this embodiment, the above-described AR layer (low refractive index layer) may be disposed on the antiglare layer 3a. For example, when the optical laminate 11 according to this embodiment is attached to a self-luminous display device, light reflection at the air-antiglare layer interface is one of the factors that deteriorate the visibility of an image. The AR layer reduces such surface reflection. Note that the antiglare layer 3a and the AR layer may each have a multilayer structure in which two or more layers are stacked.

[0211] Further, in order to prevent adhesion of contaminants and improve the ease of removing adhered contaminants, it is preferable to laminate a contamination-preventing layer formed of a fluorine group-containing silane compound, a fluorine group-containing organic compound, or the like on the antiglare layer 3a.

[0212] In this embodiment, it is preferable to perform a surface treatment on at least one of the base material 1 and the antiglare layer 3a. If the surface of the base material 1 is surface-treated, the adhesion to the antiglare layer 3a is further improved. If the surface of the antiglare layer 3a is surface-treated, the adhesion to the AR layer is further improved.

[0213] In order to prevent curling of the base material 1, a solvent treatment may be performed on the other surface of the antiglare layer 3a. Further, in order to prevent curling, a transparent resin layer may be formed on the other surface of the antiglare layer 3a.

[0214] In this embodiment, the optical laminate 20 can be prepared by laminating the adhesive layer 2 on the surface 1b of the base material 1. The optical laminate 21 can be prepared by laminating the adhesive layer 2 on the surface 1b of the base material 1 that has not been subjected to an antireflection treatment and / or an antiglare treatment. The optical laminate 22 can be prepared by laminating the adhesive layer 2 on the surface 1b of the base material 1 on which the antiglare layer 3a is not formed.

[0215] The method of laminating the adhesive layer 2 on the surface 1b of the base material 1 is not particularly limited. For example, it can be carried out by laminating one of the release films S1 and S2 of the adhesive layer 2 shown in FIG. 1 on the surface 1b of the base material 1 after peeling off one of them.

[0216] The thickness of the release film S1 and the thickness of the other release film S2 may be the same or different. The peeling force when peeling off the release film S1 and the peeling force when peeling off the release film S1 may be the same or different. When the peeling forces of both are different, the optical laminate having the adhesive layer 2 of the present embodiment can be produced by peeling off the release film with a relatively small peeling force (light release film) from the adhesive layer 2 first and laminating it on the surface 1b of the base material 1.

[0217] In addition, the optical adhesive composition A is applied to the surface 1b of the base material 1, formed on a sheet, heated and dried, and then, if necessary, a release film is attached to the surface of the coating film in the same manner as above, and the optical laminate of the present embodiment can also be produced.

[0218] As described above, the adhesive layer 2 containing a colorant has light absorption in visible light. The total light transmittance of the optical laminate of the present embodiment is, for example, 80% or less, and may be 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less.

[0219] The optical laminate of the present embodiment may be provided with a release film on the adhesive layer until use. Further, the optical laminate of the present embodiment may have a surface protection film laminated on the surface 1a of the base material 1 where the adhesive layer 2 is not laminated (when the surface 1a is subjected to an antireflection treatment and / or an antiglare treatment, the treated surface). The surface protection film is suitable for preventing the adhesion of scratches and dirt during the manufacture, transportation, and shipment of the optical laminate and optical products including the same.

[0220] In addition to the base material 1, the adhesive layer 2 (adhesive layer A), the release film, and the surface protection film, the optical laminate of the present embodiment may have other layers, such as a base material other than the base material 1, an adhesive layer other than the adhesive layer 2, an intermediate layer, an undercoat layer, etc., on the surface or between any layers, as long as the effects of the present invention are not impaired.

[0221] <Self-luminous display device> The self-luminous display device according to the fourth aspect of the present invention arranges a large number of minute light-emitting elements on a wiring board, and selectively emits light from each light-emitting element by light-emitting control means connected thereto, so that visual information such as characters, images, and moving images can be directly displayed on the display screen by the blinking of each light-emitting element. Examples of the self-luminous display device include a mini / micro LED display device and an organic EL (electroluminescence) display device. The optical laminate according to the third aspect of the present invention is particularly preferably used in the manufacture of a mini / micro LED display device.

[0222] Figs. 5 to 7 are schematic diagrams (cross-sectional views) showing an embodiment of the self-luminous display device (mini / micro LED display device) according to the fourth aspect of the present invention. In Fig. 5, the self-luminous display device (mini / micro LED display device) 30 includes a display panel in which a plurality of LEDs 6 are arranged on one side of a substrate 4, and the optical laminate 20 according to the third aspect of the present invention. The surface on which the LED chips 6 on the display panel are arranged is laminated with the adhesive layer 2 of the optical laminate 20. In Fig. 6, in the self-luminous display device (mini / micro LED display device) 31, the surface 1a of the self-luminous display device (mini / micro LED display device) 30 is subjected to an antireflection treatment and / or an antiglare treatment 3. In Fig. 7, in the self-luminous display device (mini / micro LED display device) 32, the surface 1a of the self-luminous display device (mini / micro LED display device) 30 is formed with an antiglare layer 3a as an antireflection treatment and / or an antiglare treatment.

[0223] In this embodiment, a metal wiring layer 5 for sending a light emission control signal to each LED chip 6 is laminated on a substrate 4 of a display panel. Each LED chip 6 that emits light of each color of red (R), green (G), and blue (B) is alternately arranged on the substrate 4 of the display panel via the metal wiring layer 5. The metal wiring layer 5 is formed of a metal such as copper, reflects the light emission of each LED chip 6, and reduces the visibility of the image. Also, the light emitted by each LED chip 6 of each RGB color is mixed, and the contrast is reduced.

[0224] In the mini / micro LED display device of this embodiment, each LED chip 6 arranged on the display panel is sealed by an adhesive layer 2. Since the adhesive layer 2 is formed of an optical adhesive composition A containing a (meth)acrylic block copolymer A, the storage elastic modulus decreases in a region exceeding 50°C and becomes highly fluid, and it can sufficiently follow the fine steps between the LED chips 6 and seal them without gaps. Also, near room temperature (for example, 25°C), it exhibits a high storage elastic modulus, is hard, and has good processability.

[0225] Also, since the adhesive layer 2 contains a colorant, it has sufficient light shielding properties in the visible light region. Since the fine steps between the LED chips 6 are sealed without gaps by the adhesive layer 2 having high light shielding properties, reflection by the metal wiring layer 5 can be prevented, color mixing between the LED chips 6 can be prevented, and the contrast can be improved.

[0226] As described above, in the optical laminate according to the present embodiment, since the pressure-sensitive adhesive layer contains a colorant, even when a metal adherend is laminated on the pressure-sensitive adhesive layer, reflection and gloss on the metal surface can be prevented. When a metal adherend is laminated on the pressure-sensitive adhesive layer of the optical laminate of the present embodiment, the reflectance of the substrate surface 1a in the visible light region of 5° regular reflection is preferably 50% or less, more preferably 30% or less, still more preferably 15% or less, and particularly preferably 10% or less. The glossiness (based on JIS Z 8741-1997) of the substrate surface 1a when a metal adherend is laminated on the pressure-sensitive adhesive layer of the optical laminate of the present embodiment is preferably 100% or less, more preferably 80% or less, still more preferably 60% or less, and particularly preferably 50% or less. Note that, as the metal adherend, copper, aluminum, stainless steel, etc. can be used.

[0227] In the mini / micro LED display device 31 of the present embodiment, an antireflection treatment and / or an antiglare treatment 3 is performed on the surface 1a of the substrate 1, preventing a decrease in visibility due to reflection of external light and reflection of an image on the substrate surface 1a, or adjusting the appearance such as glossiness. Further, in the mini / micro LED display device 32 of the present embodiment, an antiglare treatment 3a is formed on the surface 1a of the substrate 1, preventing a decrease in visibility due to reflection of external light and reflection of an image on the substrate surface 1a, or adjusting the appearance such as glossiness. The average tilt angle θa (°) of the antiglare layer 3a of the mini / micro LED display device 32 according to the present embodiment is the same as above.

[0228] The self-emitting display device of the present embodiment may include optical members other than the display panel and the optical laminate. The optical members are not particularly limited, and examples include a polarizing plate, a retardation plate, an antireflection film, a viewing angle adjustment film, an optical compensation film, etc. Note that the optical members also include members (design films, decorative films, surface protection plates, etc.) that serve a role of decoration and protection while maintaining the visibility of the display device and the input device.

[0229] The mini / micro LED display device of this embodiment can be manufactured by bonding the adhesive layer 2 of the optical laminate according to the third aspect of the present invention to one side of the substrate on which a plurality of LED chips are arranged.

[0230] The attachment of the display panel and the optical laminate having the adhesive layer is preferably carried out by laminating under heating and / or pressure. Specifically, it is preferable to heat and pressurize at 50°C or higher. By heating and pressurizing at 50°C or higher, the adhesive layer becomes highly fluid and can sufficiently follow the steps of the LED chips arranged on the substrate, enabling close adhesion without gaps. The heating is carried out at 50°C or higher, preferably 60°C or higher, more preferably 70°C or higher. The pressure is not particularly limited, but for example, it is carried out at 1.5 atm or higher, preferably 2 atm or higher, more preferably 3 atm or higher. The heating and pressurization can be carried out using, for example, an autoclave. The mini / micro LED display device thus manufactured has a high storage elastic modulus of the adhesive layer after returning to room temperature (25°C), improving processability and adhesion reliability.

Example

[0231] Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these examples. Note that the various properties in the following production examples were evaluated or measured by the following methods.

[0232] (Surface shape measurement) A glass plate (thickness 1.3 mm) manufactured by Matsunami Glass Industry Co., Ltd. was bonded to the surface of the antiglare film where the antiglare layer was not formed using an adhesive, and the surface shape of the antiglare layer was measured under the condition of a cut-off value of 0.8 mm using a high-precision fine shape measuring instrument (product name; Surf Coader ET4000, manufactured by Kosaka Laboratory Ltd.) to obtain the average tilt angle θa. Note that the high-precision fine shape measuring instrument automatically calculates the average tilt angle θa. The average tilt angle θa is based on JIS B 0601 (1994 edition).

[0233] (Haze) In accordance with the method defined in JIS 7136, a haze meter (manufactured by Murakami Color Research Laboratory, trade name "HN-150") was installed so that light was incident from the anti-glare layer side of the anti-glare film, and the haze value was measured.

[0234] (Visible light transmittance of the adhesive sheet) The release film on one side was peeled off from the adhesive sheet, and non-alkali glass was bonded to the exposed surface. Then, the release film on the other side was peeled off from the adhesive sheet to obtain a sample in which the adhesive sheet was bonded onto a non-alkali glass plate. Using this sample, the transmittance spectrum of the evaluation sample was measured with a visible ultraviolet spectrophotometer (manufactured by Hitachi High-Technologies Corporation, trade name "U-4100"). Taking non-alkali glass (alone) as the baseline, the ratio of the transmittance (transmitted light amount) of the evaluation sample to the transmittance (transmitted light amount) of non-alkali glass was defined as the transmittance of the adhesive sheet. From the transmittance spectrum of the adhesive sheet, the transmittance T VIS at a wavelength of 550 nm was calculated.

[0235] (Visible light transmittance of the anti-glare film) The anti-glare film was installed in a spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation) so that light was incident from the anti-glare layer side, and the transmittance (%) in the visible light region was measured. This transmittance was the Y value measured by the 2-degree field of view (C light source) of JIS Z8701 and subjected to visual sensitivity correction.

[0236] Production Example 1 (Preparation of the anti-glare film) As the resin contained in the antiglare layer, 100 parts by weight of an ultraviolet-curable urethane acrylate resin (manufactured by DIC Corporation, trade name "Unidic 17-806", solid content 80%) was prepared. Per 100 parts by weight of the resin solid content of the resin, 14 parts by weight of styrene cross-linked particles (manufactured by Soken Chemical & Engineering Co., Ltd., trade name "MX-350H", weight average particle diameter: 3.5 μm, refractive index 1.59) as light-diffusing fine particles, 2.5 parts by weight of synthetic smectite which is an organic clay (manufactured by Kunimine Industries Co., Ltd., trade name "Smeton SAN") as a thixotropy-imparting agent, 5 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "OMNIRAD 907"), and 0.5 parts by weight of a leveling agent (manufactured by DIC Corporation, trade name "Megafac F-556", solid content 100%) were mixed. This mixture was diluted with a toluene / ethyl acetate mixed solvent (weight ratio 90 / 10) so that the solid content concentration became 30% by weight to prepare a light-diffusing element forming material (coating liquid). On one side of a triacetyl cellulose (TAC) film (manufactured by Fuji Film Co., Ltd., product name "TG60UL", thickness: 60 μm) that can function as a protective layer, an antiglare layer forming material (coating liquid) was applied using a bar coater to form a coating film. Then, the transparent TAC film substrate on which this coating film was formed was conveyed to a drying process. In the drying process, the coating film was dried by heating at 110°C for 1 minute. Then, ultraviolet rays with an integrated light amount of 300 mJ / cm 2 were irradiated with a high-pressure mercury lamp, and the coating film was cured to form a light-diffusing element with a thickness of 5.0 μm on one side of the TAC film to obtain an antiglare film 1. The haze value of the antiglare film 1 was 42%. The θa (°) of the antiglare layer of the antiglare film 1 was 1.22. The visible light transmittance of the antiglare film 1 was 90%.

[0237] Production Example 2 (Preparation of Antiglare Film) As an optically diffusive particle, 14 parts by weight of amorphous silica (manufactured by Fuji Silysia Chemical Ltd., trade name "Silohobic 100", weight average particle diameter: 2.6 μm) was added, and an anti-glare element was formed on one side of a TAC film in the same manner as in Production Example 1 except that the thickness after the curing treatment was 7.0 μm to obtain an anti-glare film 2. The haze value of the anti-glare film 2 was 11%. The θa (°) of the anti-glare layer of the anti-glare film 2 was 1.43. The visible light transmittance of the anti-glare film 2 was 91%.

[0238] Production Example 3 (Preparation of anti-glare film) As the resin contained in the anti-glare layer forming material, 100 parts by weight of an ultraviolet curable urethane acrylate resin (manufactured by DIC Corporation, trade name "Unidic 17-806", solid content 80%) was prepared. Per 100 parts by weight of the resin solid content of the resin, as anti-glare layer forming particles, 7 parts by weight of amorphous silica (manufactured by Fuji Silysia Co., Ltd., trade name "Silohobic 702"), 6.5 parts by weight of amorphous silica (manufactured by Fuji Silysia Co., Ltd., trade name "Silohobic 100"), 5 parts by weight of a photoinitiator (manufactured by BASF, trade name "OMNIRAD 184"), and 0.5 parts by weight of a leveling agent (manufactured by DIC Corporation, trade name "Megafac F-556") were mixed. This mixture was diluted with toluene so that the solid content concentration became 30% to prepare an anti-glare layer forming material (coating liquid). As a light-transmissive substrate, a transparent plastic film substrate (TAC film, manufactured by Fuji Film Co., Ltd., trade name "TD80UL", thickness: 80 μm) was prepared. On one side of the transparent plastic film substrate, the anti-glare layer forming material (coating liquid) was used to form a coating film using a bar coater. Then, the transparent plastic film substrate on which this coating film was formed was conveyed to a drying process. In the drying process, the coating film was dried by heating at 110 °C for 1 minute. Thereafter, with a high-pressure mercury lamp, the integrated light quantity was 300 mJ / cm 2Ultraviolet rays were irradiated to cure the coating film to form an antiglare layer with a thickness of 5.0 μm, and an antiglare film 3 was obtained. The θa (°) of the antiglare layer of the antiglare film 3 was 3.5. The visible light transmittance of the antiglare film 3 was 91%.

[0239] Production Example 4 (Preparation of antiglare film) As the antiglare layer-forming particles, 6.5 parts by weight of amorphous silica (manufactured by Fuji Silysia Chemical Ltd., trade name "Silohobic 702") and 6.5 parts by weight of amorphous silica (manufactured by Fuji Silysia Chemical Ltd., trade name "Silohobic 200") were added, and 2.5 parts by weight of a thickener (manufactured by Coop Chemical, trade name "Lucentite SAN") was added. An antiglare film 4 was obtained in the same manner as in Production Example 3 except that the thickness after the curing treatment was 8.0 μm. The θa (°) of the antiglare layer of the antiglare film 4 was 2.3. The visible light transmittance of the antiglare film 4 was 91%.

[0240] Production Example 5 (Preparation of polymer RAFT solution A1) Into a reaction vessel equipped with a condenser, a nitrogen inlet tube, a thermometer, and a stirrer, 50 parts by weight of cyclohexyl acrylate (CHA) and 50 parts by weight of 3,3,5-trimethylcyclohexyl acrylate (TMCHA) as monomer components, 0.5 part by weight of dibenzyl trithiocarbonate (DBTC) as a RAFT agent, and 100 parts by weight of ethyl acetate as a polymerization solvent were charged, and 0.2 part by weight of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added, and solution polymerization was carried out under a nitrogen atmosphere to obtain a polymer RAFT solution A1 having an Mw of 180,000. (Preparation of acrylic triblock copolymer-containing adhesive solution B1) Into a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirring device, 97 parts by weight of 2-ethylhexyl acrylate (2EHA), 3 parts by weight of 4-hydroxybutyl acrylate (4HBA), 100 parts by weight of the polymer RAFT solution A1 obtained above, and 100 parts by weight of ethyl acetate as a polymerization solvent were charged, and 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, and solution polymerization was carried out under a nitrogen atmosphere to obtain An adhesive solution B1 containing an ABA-type acrylic triblock copolymer with Mw of 400,000 and Mw / Mn of 4.3 was obtained. In the calculated glass transition temperature (Tg) according to the FOX equation, the Tg of segment A of the ABA-type acrylic triblock copolymer is 32 °C, and the Tg of segment B is -70 °C. The measurement of the weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of the above product was carried out as standard polystyrene conversion by gel permeation chromatography (GCP method) under the following measurement conditions. · Measuring device: HLC-8320GPC (manufactured by Tosoh Corporation) · Column: TSKgel GMH-H(S) (manufactured by Tosoh Corporation) · Mobile phase solvent: Tetrahydrofuran · Flow rate: 1.0 cm 3 / min · Column temperature: 40 °C

[0241] Production Example 6 (Polymerization of prepolymer) Into a separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas introduction pipe, 22 parts by weight of 2-ethylhexyl acrylate (2EHA), 60 parts by weight of lauryl acrylate (LA), 10 parts by weight of N-vinylpyrrolidone (NVP), 8 parts by weight of 4-hydroxybutyl acrylate, and 0.1 part by weight of Irgacure 651 as a polymerization initiator were charged. Then, nitrogen gas was passed, and nitrogen substitution was carried out for about 1 hour while stirring. Then, polymerization was carried out by irradiating with UVA at 5 mW / cm 2 to adjust the reaction rate to 5-15% to obtain an acrylic prepolymer solution. (Preparation of adhesive composition) To the acrylic prepolymer solution obtained above (assuming the total amount of the prepolymer is 100 parts by weight), 37 parts by weight of 2-ethylhexyl acrylate (2EHA), 0.1 part by weight of 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name "NK Ester A-HD-N") as a polyfunctional monomer, 0.3 part by weight of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Silicone Co., Ltd., trade name "KBM-403") as a silane coupling agent, and 0.1 part by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF, trade name "Irgacure 651") as a photopolymerization initiator were added to prepare a photocurable pressure-sensitive adhesive composition solution.

[0242] Example 1 (Preparation of Black Pressure-Sensitive Adhesive Composition) To the pressure-sensitive adhesive solution B1 containing the acrylic triblock copolymer obtained in Production Example 5, 0.5 part by weight of a black dye ("VALIFAST BLACK 3810" manufactured by Orient Chemical Industries) was added based on 100 parts by weight of the total amount of the monomers used in Production Example 5 to prepare a black solvent-based pressure-sensitive adhesive composition solution 1. (Preparation of Pressure-Sensitive Adhesive Sheet) Using a 75-μm-thick polyethylene terephthalate (PET) film ("Diafoil MRF75" manufactured by Mitsubishi Chemical Corporation) with a silicone-based release layer on the surface as a substrate, the black solvent-based pressure-sensitive adhesive composition solution 1 prepared above was applied onto the substrate and dried at 130°C for 3 minutes to form a 150-μm-thick pressure-sensitive adhesive layer. Onto this pressure-sensitive adhesive layer, a 75-μm-thick PET film ("Diafoil MRE75" manufactured by Mitsubishi Chemical Corporation) with one side silicone-release-treated was laminated to obtain a pressure-sensitive adhesive sheet 1 with release films attached to both sides in the form of a substrate-free pressure-sensitive adhesive sheet. The visible light transmittance of the pressure-sensitive adhesive sheet 1 was less than 1%. (Preparation of Optical Laminate) One of the release films was peeled off from the pressure-sensitive adhesive sheet 1 obtained above and cut into 20 mm × 20 mm, and the exposed pressure-sensitive adhesive surface was attached to the center of a 45 mm × 50 mm glass plate (visible light transmittance: 93%) to obtain an optical laminate 1 composed of a glass plate / pressure-sensitive adhesive sheet 1 / release film.

[0243] Example 2 (Preparation of Black Adhesive Composition) A black solvent-based adhesive composition solution 2 was prepared in the same manner as in Example 1, except that 1.0 part by weight of a black dye ("VALIFAST BLACK 3810" manufactured by Orient Chemical Industries) was added. (Preparation of Adhesive Sheet) An adhesive sheet 2 with release films attached to both sides was obtained in the form of a substrate-free adhesive sheet in the same manner as in Example 1, except that the black solvent-based adhesive composition solution 2 prepared above was applied onto the substrate. The visible light transmittance of the adhesive sheet 2 was less than 1%. (Preparation of Optical Laminate) An optical laminate 2 composed of a glass plate / adhesive sheet 2 / release film was obtained in the same manner as in Example 1, except that the adhesive sheet 2 obtained above was used.

[0244] Example 3 (Preparation of Black Adhesive Composition) A black solvent-based adhesive composition solution 3 was prepared in the same manner as in Example 1, except that 2.0 parts by weight of a black dye ("VALIFAST BLACK 3810" manufactured by Orient Chemical Industries) was added. (Preparation of Adhesive Sheet) An adhesive sheet 3 with release films attached to both sides was obtained in the form of a substrate-free adhesive sheet in the same manner as in Example 1, except that the black solvent-based adhesive composition solution 3 prepared above was applied onto the substrate. The visible light transmittance of the adhesive sheet 3 was less than 1%. (Preparation of Optical Laminate) An optical laminate 3 composed of a glass plate / adhesive sheet 3 / release film was obtained in the same manner as in Example 1, except that the adhesive sheet 3 obtained above was used.

[0245] Comparative Example 1 (Preparation of Adhesive Sheet) Instead of the black solvent-based pressure-sensitive adhesive composition solution 1, an adhesive sheet 4 with release films attached to both sides was obtained in the form of a substrate-free pressure-sensitive adhesive sheet in the same manner as in Example 1, except that the adhesive solution B1 prepared in Production Example 5 was applied onto the substrate. The visible light transmittance of the adhesive sheet 4 was 90%. (Preparation of the optical laminate) An optical laminate 4 composed of a glass plate / adhesive sheet 4 / release film was obtained in the same manner as in Example 1, except that the adhesive sheet 4 obtained above was used.

[0246] Comparative Example 2 (Preparation of the adhesive sheet) A photocurable pressure-sensitive adhesive composition solution obtained in Production Example 6 was applied onto a release-treated PET film (light release separator) so that the thickness after drying would be 150 μm, and then heat-dried to obtain an adhesive layer. Another PET film (heavy release separator) was laminated and adhered onto this adhesive layer to obtain a photocurable adhesive sheet with separators attached to both sides. From one side of this adhesive sheet, ultraviolet rays were irradiated under the conditions of an illuminance of 5 mW / cm 2 , and an integrated light quantity of 1300 mJ / cm 2 using a black light (manufactured by Toshiba Corporation, product name "FL15BL"). As a result, an adhesive sheet 5 with a thickness of 150 μm in which a photocrosslinkable pressure-sensitive adhesive, which is a cured product of the above adhesive composition, is sandwiched between the above PET films (light release separator, heavy release separator) was obtained in the form of a substrate-free pressure-sensitive adhesive sheet. The value of the illuminance of the above black light is a measured value by an industrial UV checker (manufactured by Topcon Corporation, product name: UVR-T1, light-receiving unit type UD-T36) with a peak sensitivity wavelength of about 350 nm. The visible light transmittance of the adhesive sheet 5 was 90%. (Preparation of the optical laminate) An optical laminate 5 composed of a glass plate / adhesive sheet 5 / release film was obtained in the same manner as in Example 1, except that the adhesive sheet 5 obtained above was used.

[0247] (Evaluation) Using the optical laminates obtained in the above Examples and Comparative Examples, the following evaluations were carried out. The evaluation methods are shown below.

[0248] (1) Evaluation of step following performance (Production of uneven adherend) After laminating a TAC film (thickness 60 μm) and an adhesive (thickness 20 μm) on a 45 mm × 50 mm glass plate, a 10 mm × 10 mm area in the center was linearly etched using a CO2 laser (wavelength 10.6 μm, laser diameter 〇 μm) at a vertical pitch of 150 μm and a horizontal pitch of 225 μm to obtain an adherend A in which the TAC film and the adhesive layer were processed into a lattice-like uneven shape. This adherend A mimics an LED panel in which a plurality of LED films are arranged on a substrate. (Vacuum lamination) The release films of the optical laminates 1 to 5 prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were peeled off, and the exposed adhesive surface and the processed surface of the adherend A were laminated using a vacuum laminating apparatus (manufactured by CRIMB Products, SE340aaH) with an accuracy such that the adhesive sheet could completely cover the processed area of the adherend A, and evaluation samples 1 to 5 each composed of a glass plate / adhesive sheet 1 to 5 / adherend A were obtained. (Evaluation of step following performance) In evaluation samples 1 to 5, when the adhesive sheet could follow the uneven pattern portion, the processed portion of the adherend A was visually recognized as transparent, and the portion that could not be followed was visually recognized as white. Using this property, the area of the white portion was calculated by fixed-point camera photography to evaluate the step following performance. Step following performance (%) = 100 - {[Area of white portion at the time of evaluation] / [Area of white portion before lamination = 1 cm 2 ×100} The step following performance was measured at the stage after autoclaving (60 minutes under the conditions of 50 °C and 0.5 MPa). The results are shown in Table 1.

[0249] (2) Visible light transmittance The optical laminates obtained in the above Examples and Comparative Examples were placed in a spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation) so that light was incident from the glass plate side, and the transmittance (%) in the visible light region was measured. This transmittance is the Y value measured by the 2-degree field of view (C light source) of JIS Z8701 and corrected for visual sensitivity. The results are shown in Table 1.

[0250] (3) Reflectance A plate was prepared by laminating an aluminum foil on a black acrylic plate. The adhesive surface of the optical laminate obtained in the above Examples and Comparative Examples, with the release film peeled off and exposed, was laminated on the aluminum foil side of the above plate to obtain a sample. The obtained sample was placed in a spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation) with the antiglare film / TAC film on the light source side, and the reflectance (%) in the visible light region at 5° regular reflection was measured. The results are shown in Table 1.

[0251]

Table 1

[0252] (1) Storage elastic modulus [G’25, G’50, G’25 / G’50] and peak temperature and maximum value of tanδ Regarding the pressure-sensitive adhesive sheets 1, 4, and 5 obtained in Example 1 and Comparative Examples 1 and 2 above, the storage elastic modulus at 25°C (G’25), the storage elastic modulus at 50°C (G’50), the ratio thereof (G’25 / G’50), the peak temperature and maximum value of tanδ were measured or evaluated. The methods of measurement or evaluation are shown below. The results of measurement or evaluation are shown in Table 2.

[0253] The storage elastic modulus at 25°C and 50°C and the peak temperature and maximum value of tanδ were determined by dynamic viscoelasticity measurement. A sample for measurement was prepared by laminating a plurality of adhesive sheets to a thickness of approximately 1.5 mm. Using a "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific, dynamic viscoelasticity measurement was performed under the following conditions. From the measurement results, the storage elastic modulus (G’ 25 , G’ 50 ), as well as the peak temperature and maximum value of tanδ were read. (Measurement conditions) Deformation mode: torsion Measurement frequency: 1 Hz Temperature rising rate: 5°C / min Measurement temperature: in the range of -100 to 150°C Shape: parallel plate 8.0 mm φ

[0254]

Table 2

[0255] Example 4 (Preparation of optical laminate) One of the release films was peeled off from the adhesive sheet 1 obtained in Example 1 cut into 20 mm × 20 mm, and the exposed adhesive surface was attached to the center of the surface of the antiglare film 1 obtained in Production Example 1 cut into 45 mm × 50 mm where the antiglare layer was not formed, thereby obtaining an optical laminate 6 composed of the antiglare film 1 / adhesive sheet 1 / release film.

[0256] Examples 5 to 7 (Preparation of optical laminate) An optical laminate 7 to 9 composed of the antiglare films 2 to 4 / adhesive sheet 1 / release film was obtained in the same manner as in Example 4, except that the antiglare films 2 to 4 obtained in Production Examples 2 to 4 were used instead of the antiglare film 1.

Explanation of reference numerals

[0257] 10 Adhesive layer (adhesive sheet) 20, 21, 22 Optical laminate 1 Substrate 2 Adhesive layer S1, S2 Release film 3 Anti-reflection treatment and / or anti-glare treatment 3a Anti-glare layer 30, 31, 32 Self-emitting display device (mini / micro LED display device) 4 Substrate 5 Metal wiring layer 6 Light-emitting element (LED chip)

Claims

1. An optical pressure-sensitive adhesive composition comprising a (meth)acrylic block copolymer and a colorant, The (meth)acrylic block copolymer is A high Tg segment having a glass transition temperature of 0° C. or more and 100° C. or less; having a low Tg segment having a glass transition temperature of -100°C or more and less than 0°C; It has tan δ peaks in the region above 0°C and the region below 0°C, the (meth)acrylic block copolymer contains, as a monomer component constituting the high Tg segment, at least one monomer selected from the group consisting of a (meth)acrylic acid alkyl ester having a linear alkyl group with 1 to 3 carbon atoms, a (meth)acrylic acid alkyl ester having a branched alkyl group with 3 or 4 carbon atoms, and an alicyclic monomer; the alicyclic monomer contains a (meth)acrylic acid cycloalkyl ester having a cycloalkyl group having 4 to 10 carbon atoms which may have a substituent, The (meth)acrylic acid cycloalkyl ester is at least one selected from the group consisting of cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Here, the glass transition temperature is calculated from the composition of the monomer components constituting each segment by the FOX formula.

2. The optical pressure-sensitive adhesive composition according to claim 1, wherein the maximum value of tan δ in the region of 0° C. or higher is 0.5 to 3.

0.

3. The optical pressure-sensitive adhesive composition according to claim 1 or 2, wherein the (meth)acrylic block copolymer is an ABA triblock copolymer.

4. The optical pressure-sensitive adhesive composition according to claim 3 , wherein in the ABA triblock copolymer, an A segment is the high Tg segment, and a B segment is the low Tg segment.

5. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 4, comprising a (meth)acrylic acid alkyl ester having a branched alkyl group having 3 or 4 carbon atoms as a monomer component constituting the high Tg segment in the (meth)acrylic block copolymer.

6. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 5, comprising at least one monomer selected from the group consisting of (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms and hydroxyl group-containing monomers, as a monomer component constituting the low Tg segment in the (meth)acrylic block copolymer.

7. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 6, comprising 1 wt% or more of a hydroxyl group-containing monomer relative to a total amount (100 wt%) of monomer components constituting the low Tg segment in the (meth)acrylic block copolymer.

8. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 7, wherein the (meth)acrylic block copolymer has a weight average molecular weight of 200,000 or more.

9. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 8, wherein the (meth)acrylic block copolymer has a molecular weight distribution of more than 1 and not more than 5.

10. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 9, wherein a ratio of a storage modulus at 25°C to a storage modulus at 50°C (storage modulus at 25°C / storage modulus at 50°C) is 3 or more.

11. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 10, having a storage modulus at 25°C of 1 MPa or more and a storage modulus at 50°C of 0.5 MPa or less.

12. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 11, wherein the colorant has an average transmittance of 80% or less at a wavelength of 400 to 700 nm.

13. A pressure-sensitive adhesive layer formed from the optical pressure-sensitive adhesive composition according to any one of claims 1 to 12.

14. An optical laminate comprising a substrate and the pressure-sensitive adhesive layer according to claim 13.

15. The optical laminate according to claim 14 , wherein a surface of the substrate on which the pressure-sensitive adhesive layer is not laminated is subjected to anti-reflection treatment and / or anti-glare treatment.

16. The optical laminate according to claim 15, wherein the antiglare treatment is an antiglare layer provided on one side of the substrate.

17. the anti-glare layer is formed using an anti-glare layer-forming material including a resin, particles, and a thixotropy-imparting agent; The optical laminate according to claim 16, wherein the antiglare layer has aggregated portions in which the particles and the thixotropy-imparting agent aggregate to form convex portions on a surface of the antiglare layer.

18. The optical laminate according to claim 17, wherein the average inclination angle θa (°) of the convex portions on the surface of the antiglare layer is in the range of 0.1 to 1.

5.

19. The optical laminate according to any one of claims 14 to 18, further comprising a surface protection film laminated on the surface of the substrate on which the pressure-sensitive adhesive layer is not laminated.

20. A display panel having a plurality of light-emitting elements arranged on one surface of a substrate; A self-luminous display device comprising the optical laminate according to any one of claims 14 to 19, A self-luminous display device in which the pressure-sensitive adhesive layer of the optical laminate is laminated on a surface of the display panel on which light-emitting elements are arranged.

21. 21. The self-luminous display device according to claim 20, wherein the display panel is an LED panel having a plurality of LED chips arranged on one surface of a substrate.

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