Adhesive sheet and display body

Abstract

Provided is an adhesive sheet 1 having an adhesive layer 11, wherein, taking the haze value (%) of the adhesive layer 11 by 450 nm light as H(450) and the haze value by 650 nm light as H(650), the absolute value of slope S1 represented by formula (1) is more than 0.026, the haze value of the adhesive layer 11 is 10-100%, and the adhesive force of the adhesive sheet 1 to soda lime glass is 1 N / 25 mm or more.　S1 = (H(650) - H(450)) / 200 … (1) According to the adhesive sheet 1, the lighting color can be adjusted to a color other than white while manifesting a concealing property.

Description

Adhesive sheets and displays

[0001] The present invention relates to a pressure-sensitive adhesive sheet and a display.

[0002] In recent years, liquid crystal display devices have been widely used as display devices in electronic devices such as mobile phones, smartphones, tablet devices, game consoles, etc. Since a display unit made of a liquid crystal panel or the like does not emit light itself, display devices using such a display unit are equipped with a backlight that illuminates the display unit.

[0003] Until now, the most common method of arranging the light source of the backlight in such display devices has been a sidelight type, in which the light source is arranged on the side of the light guide plate. Recently, however, from the viewpoint of screen brightness and contrast, a direct-type backlight, in which the light source is arranged directly below the display unit, has been proposed. In direct-type backlights, it has been proposed to provide a large number of light emitters, typically light-emitting diodes (LEDs), on a substrate in order to increase the amount of light and, when used as a display device, to make the amount of light uniform between the center and edges of the screen.

[0004] In a display device equipped with a direct backlight having a large number of light emitters, the arrangement of the light emitters and the electronic circuit are visible from the display unit, so concealment is required. In response to this, Patent Document 1 proposes providing an adhesive layer containing light-scattering particles on the light emitters of the backlight. This makes it possible to conceal the arrangement of the light emitters and the electronic circuit by the light scattering effect of the light-scattering particles.

[0005] Patent No. 5590582

[0006] Here, when it is desired to make the light emitted from the backlight white, it is usually desirable not to color the light emitted by the adhesive layer. On the other hand, there are cases where it is desired to color the light emitted from the backlight to a desired color.

[0007] The present invention has been made in consideration of the above-described circumstances, and aims to provide an adhesive sheet and a display that can exhibit hiding properties while adjusting the emitted color to a color other than white.

[0008] In order to achieve the above object, first, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein the absolute value of the slope S1 expressed by the following formula (1) exceeds 0.026, where H(450) is the haze value (%) of the pressure-sensitive adhesive layer measured with light having a wavelength of 450 nm, and H(650) is the haze value (%) of the pressure-sensitive adhesive layer measured with light having a wavelength of 650 nm, the haze value of the pressure-sensitive adhesive layer is 10% or more and 100% or less, and the adhesive strength of the pressure-sensitive adhesive sheet to soda-lime glass is 1 N / 25 mm or more (Invention 1): S1 = (H(650) - H(450)) / 200 ... (1)

[0009] Second, the present invention provides a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein, when the haze value (%) of the pressure-sensitive adhesive layer measured with light having a wavelength of 450 nm is H(450), the haze value (%) of the pressure-sensitive adhesive layer measured with light having a wavelength of 550 nm is H(550), and the haze value (%) of the pressure-sensitive adhesive layer measured with light having a wavelength of 650 nm is H(650), at least one of the absolute value of the slope S2 expressed by the following formula (2) and the absolute value of the slope S3 expressed by the following formula (3) is 0.032 or greater, the haze value of the pressure-sensitive adhesive layer is 10% or greater and 100% or less, and the adhesive strength of the pressure-sensitive adhesive sheet to soda-lime glass is 1 N / 25 mm or greater (Invention 2). S2 = (H(550) - H(450)) / 100 (2) S3 = (H(650) - H(550)) / 100 (3)

[0010] In the above inventions (Inventions 1 and 2), when the absolute value of the slope S1 or at least one of the absolute values ​​of the slopes S2 and S3 is large as described above, it becomes easier to adjust the emitted color of the resulting display, particularly a display having a blue light source, a green light source, and a red light source, to a color other than white. Furthermore, when the haze value of the pressure-sensitive adhesive layer is within the above range, excellent concealing properties are exhibited, and for example, the arrangement of light emitters and electronic circuits in a direct-type backlight having multiple light emitters can be prevented from being seen from the display unit. Furthermore, when the adhesive strength is within the above value, the adhesive strength becomes suitable for bonding display component members together, and the desired durability can be obtained.

[0011] In the above invention (invention 1), the slope S1 may be a negative value (invention 3).

[0012] In the above invention (invention 2), the slopes S2 and S3 may each exhibit a negative value (invention 4).

[0013] In the above inventions (Inventions 1 and 2), when the haze value (%) of the pressure-sensitive adhesive layer measured by light with a wavelength of 550 nm is H(550), the slope S3 expressed by the following formula (3) may be 0 or more and 0.015 or less (Invention 5): S3 = (H(650) - H(550)) / 100 (3)

[0014] In the above inventions (Inventions 1 and 2), when the haze value (%) of the pressure-sensitive adhesive layer measured by light with a wavelength of 550 nm is H(550), the slope S3 expressed by the following formula (3) may be greater than 0.015 (Invention 6): S3 = (H(650) - H(550)) / 100 (3)

[0015] In the above inventions (Inventions 1 to 6), it is preferable that the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is 20% or more and 100% or less (Invention 7).

[0016] In the above inventions (Inventions 1 to 7), it is preferable that the adhesive constituting the adhesive layer contains light-diffusing fine particles (Invention 8).

[0017] In the above invention (Invention 8), it is preferable that the average particle size of the light-diffusing fine particles is 0.1 μm or more and 20 μm or less (Invention 9).

[0018] In the above inventions (Inventions 8 and 9), it is preferable that the refractive index of the light-diffusing fine particles is 1.30 or more and 2.00 or less (Invention 10).

[0019] In the above inventions (Inventions 8 to 10), it is preferable that the content of the light-diffusing fine particles in the adhesive is 1% by mass or more and 70% by mass or less (Invention 11).

[0020] In the above inventions (Inventions 8 to 11), it is preferable that the light-diffusing fine particles are light-diffusing fine particles made of silicone resin (Invention 12).

[0021] In the above inventions (Inventions 1 to 12), the adhesive constituting the adhesive layer is preferably an acrylic adhesive (Invention 13).

[0022] In the above inventions (Inventions 1 to 13), it is preferable that the thickness of the pressure-sensitive adhesive layer is 10 μm or more and 2000 μm or less (Invention 14).

[0023] In the above inventions (Inventions 1 to 14), it is preferable that the pressure-sensitive adhesive sheet comprises two release sheets, and the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to contact the release surfaces of the two release sheets (Invention 15).

[0024] In the above inventions (Inventions 1 to 15), it is preferable that the adhesive is used to bond two display component members in a display having a blue light source, a green light source, and a red light source (Invention 16).

[0025] Thirdly, the present invention provides a display having a backlight having a blue light source, a green light source, and a red light source, characterized in that a display component positioned closer to the display surface than the backlight is bonded to another display component via the adhesive layer of the adhesive sheet (Inventions 1 to 16) (Invention 17).

[0026] In the above invention (Invention 17), it is preferable that the blue light source, the green light source, and the red light source are each a light emitting diode (Invention 18).

[0027] The pressure-sensitive adhesive sheet and display according to the present invention can adjust the luminescent color to a color other than white while exhibiting hiding properties.

[0028] 1A and 1B are cross-sectional views of a pressure-sensitive adhesive sheet according to one embodiment of the present invention, a display body according to one embodiment of the present invention, and a display body according to another embodiment of the present invention.

[0029] Hereinafter, an embodiment of the present invention will be described. [Adhesive Sheet] An adhesive sheet according to one embodiment of the present invention has an adhesive layer. In the adhesive layer, when the haze value (%) of the adhesive layer measured with light having a wavelength of 450 nm is H(450), the haze value (%) of the adhesive layer measured with light having a wavelength of 550 nm is H(550), and the haze value (%) of the adhesive layer measured with light having a wavelength of 650 nm is H(650), it is preferable that the absolute value of S1 is greater than 0.026, or at least one of the absolute values ​​of the slopes S2 and S3 is 0.032 or greater. Note that each haze value in this specification is a value measured in accordance with JIS K7136:2000. S1=(H(650)-H(450)) / 200...(1) S2=(H(550)-H(450)) / 100...(2) S3=(H(650)-H(550)) / 100...(3)

[0030] When the absolute value of the slope S1 or at least one of the absolute values ​​of the slopes S2 and S3 is large as described above, it becomes easier to adjust the emitted light color of the resulting display, particularly a display having a blue light source, a green light source, and a red light source (hereinafter sometimes referred to as an "RGB light source"), to a color other than white. The reason for this is thought to be that when the absolute value of the slope S1 or at least one of the absolute values ​​of the slopes S2 and S3 is large as described above, the diffusion of the blue, green, and red light becomes uneven, which causes the colors to mix unevenly and results in a color other than white.

[0031] From the above viewpoints, the absolute value of the slope S1 is more preferably 0.027 or more, particularly preferably 0.028 or more. From the viewpoint of making it easier to emphasize colors other than white, the absolute value of the slope S1 is preferably 0.029 or more, more preferably 0.050 or more, particularly preferably 0.070 or more, and even more preferably 0.080 or more. On the other hand, from the viewpoint of preventing colors other than white from being overemphasized, the upper limit of the absolute value of the slope S1 is preferably 0.20 or less, more preferably 0.15 or less, particularly preferably 0.10 or less, and even more preferably 0.09 or less. Furthermore, from the viewpoint of giving colors other than white a soft and gentle impression, the upper limit is preferably 0.20 or less, more preferably 0.12 or less, particularly preferably 0.08 or less, and even more preferably 0.04 or less, and even more preferably less than 0.029.

[0032] Similarly, from the above viewpoint, at least one of the absolute value of the slope S2 and the absolute value of the slope S3 is preferably 0.034 or more, more preferably 0.040 or more, particularly preferably 0.050 or more, even more preferably 0.060 or more, and of these, preferably 0.070 or more. On the other hand, from the viewpoint of preventing colors other than white from being overemphasized, the upper limit of the absolute value of the slope S2 and the absolute value of the slope S3 is preferably 0.20 or less, more preferably 0.15 or less, and particularly preferably 0.10 or less.

[0033] Here, when adjusting the luminous color of the resulting display, particularly a display having an RGB light source, to yellow, it is preferable to set the slope S1 or the slopes S2 and S3 to negative values. As described above, when the absolute value of the slope S1 or at least one of the absolute values ​​of the slopes S2 and S3 is equal to or greater than a predetermined value and these slopes are negative values, blue light is more likely to be diffused and green to yellow to red light is less likely to be diffused, resulting in a stronger yellow light.

[0034] When the luminous color of the resulting display, particularly a display having an RGB light source, is adjusted to pale yellow, the slope S3 is preferably 0.000 to 0.015, more preferably 0.004 to 0.014, particularly preferably 0.008 to 0.013, and even more preferably 0.010 to 0.012. As described above, when the absolute value of the slope S1 or at least one of the absolute values ​​of the slopes S2 and S3 is equal to or greater than a predetermined value, and the slope S3 is small as described above, it is thought that blue, green, and yellow light is less likely to diffuse and red is more likely to be mixed into the blue, green, and yellow, resulting in a pale yellow color.

[0035] When the emitted light color is adjusted to pale yellow as described above, the slope S2 is preferably 0.038 to 0.075, more preferably 0.040 to 0.070, particularly preferably 0.041 to 0.060, and further preferably 0.042 to 0.050.

[0036] When the emitted color of the resulting display, particularly a display having an RGB light source, is adjusted to blue, it is preferable that the slope S3 be greater than 0.015, more preferably 0.018 to 0.050, particularly preferably 0.020 to 0.040, and even more preferably 0.022 to 0.030. As described above, when the absolute value of the slope S1 or at least one of the absolute values ​​of the slopes S2 and S3 is equal to or greater than a predetermined value, and the slope S3 is large as described above, it is thought that blue, green, and yellow light is less likely to be diffused and red is less likely to be mixed into the blue, green, and yellow colors, resulting in a stronger blue light.

[0037] When the emitted light color is adjusted to blue as described above, the slope S2 is preferably 0.010 to 0.037, more preferably 0.020 to 0.036, particularly preferably 0.030 to 0.035, and further preferably 0.032 to 0.034.

[0038] The haze value of the pressure-sensitive adhesive layer in this embodiment is preferably 10 to 100%. This provides excellent concealing properties, and, for example, can prevent the arrangement of light emitters or electronic circuits in a direct-type backlight having multiple light emitters from being visible from the display unit. From this perspective, the lower limit of the haze value is more preferably 30% or more, particularly preferably 50% or more, and even more preferably 60% or more. From the perspective of ensuring the light intensity of the backlight and the clarity of the image, the upper limit of the haze value is more preferably 100% or less, particularly preferably 95% or less, and even more preferably 90% or less.

[0039] The haze value (H(450)) of the pressure-sensitive adhesive layer measured by light with a wavelength of 450 nm is preferably 10 to 100%, more preferably 30 to 99%, particularly preferably 50 to 95%, and even more preferably 60 to 90%, which makes it easier to satisfy the above-mentioned slopes S1, S2, and haze value.

[0040] When the luminescent color is adjusted to yellow, the haze value (H(450)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 450 nm is preferably 50 to 100%, more preferably 70 to 94%, particularly preferably 80 to 92%, and even more preferably 84 to 88%.

[0041] When the luminescent color is adjusted to pale yellow, the haze value (H(450)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 450 nm is preferably 20 to 100%, more preferably 35 to 88%, particularly preferably 50 to 77%, and even more preferably 60 to 66%.

[0042] When the luminescent color is adjusted to blue, the haze value (H(450)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 450 nm is preferably 50 to 100%, more preferably 60 to 92%, particularly preferably 70 to 88%, and even more preferably 79 to 84%.

[0043] The haze value (H(550)) of the pressure-sensitive adhesive layer measured by light with a wavelength of 550 nm is preferably 10 to 100%, more preferably 30 to 99%, particularly preferably 50 to 95%, and even more preferably 60 to 90%, which makes it easier to satisfy the above-mentioned slopes S2, S3, and haze value.

[0044] When the luminescent color is adjusted to yellow, the haze value (H(550)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 550 nm is preferably 40 to 100%, more preferably 50 to 92%, particularly preferably 60 to 85%, and even more preferably 70 to 80%.

[0045] When the luminescent color is adjusted to pale yellow, the haze value (H(550)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 550 nm is preferably 10 to 100%, more preferably 30 to 85%, particularly preferably 50 to 75%, and even more preferably 60 to 70%.

[0046] When the luminescent color is adjusted to blue, the haze value (H(550)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 550 nm is preferably 50 to 100%, more preferably 70 to 95%, particularly preferably 80 to 92%, and even more preferably 85 to 90%.

[0047] The haze value (H(650)) of the pressure-sensitive adhesive layer measured by light with a wavelength of 650 nm is preferably 10 to 100%, more preferably 30 to 99%, particularly preferably 50 to 95%, and even more preferably 60 to 90%, which makes it easier to satisfy the above-mentioned slopes S1, S3, and haze value.

[0048] When the luminescent color is adjusted to yellow, the haze value (H(650)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 650 nm is preferably 30 to 100%, more preferably 40 to 85%, particularly preferably 50 to 75%, and even more preferably 60 to 69%.

[0049] When the luminescent color is adjusted to pale yellow, the haze value (H(650)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 650 nm is preferably 40 to 100%, more preferably 50 to 90%, particularly preferably 60 to 85%, and even more preferably 69 to 80%.

[0050] When the luminescent color is adjusted to blue, the haze value (H(650)) of the pressure-sensitive adhesive layer when exposed to light with a wavelength of 650 nm is preferably 50 to 100%, more preferably 65 to 97%, particularly preferably 70 to 93%, and even more preferably 80 to 90%.

[0051] The ratio (H(450) / H(550)) of the haze value (H(450)) of the pressure-sensitive adhesive layer measured by light with a wavelength of 450 nm to the haze value (H(550)) of the pressure-sensitive adhesive layer measured by light with a wavelength of 550 nm is preferably 0.80 to 1.20, more preferably 0.85 to 1.15, particularly preferably 0.90 to 1.12, and even more preferably 0.93 to 1.10. This makes it easier to satisfy the above-mentioned slope S2. From the viewpoint of making it easier to emphasize colors other than white, it is also preferable that the range excluding the range of 0.98 to 1.02 from the above-mentioned range.

[0052] The ratio (H(650) / H(550)) of the haze value (H(450)) of the pressure-sensitive adhesive layer measured with light having a wavelength of 650 nm to the haze value (H(550)) measured with light having a wavelength of 550 nm is preferably 0.80 to 1.20, more preferably 0.85 to 1.15, particularly preferably 0.90 to 1.10, and even more preferably 0.95 to 1.05. This makes it easier to satisfy the above-mentioned slope S3. From the viewpoint of making it easier to emphasize colors other than white, it is also preferable that the range excluding the range of 0.99 to 1.01 is used.

[0053] The adhesive strength of the adhesive sheet according to this embodiment to soda lime glass is preferably 1 N / 25 mm or more. This provides an adhesive strength suitable for bonding display component members together, and allows for desired durability. From this perspective, the adhesive strength is more preferably 6 N / 25 mm or more, particularly preferably 12 N / 25 mm or more, and even more preferably 18 N / 25 mm or more.

[0054] The upper limit of the adhesive strength is preferably 60 N / 25 mm or less, more preferably 45 N / 25 mm or less, particularly preferably 30 N / 25 mm or less, and even more preferably 25 N / 25 mm or less, which provides good reworkability and enables the reuse of expensive display component parts in the event of a lamination error.

[0055] Here, the adhesive strength in this specification basically refers to the adhesive strength measured by the 180-degree peel method in accordance with JIS Z0237:2022, and the measurement sample is 25 mm wide and 100 mm long, and the measurement sample is attached to an adherend and pressurized at 0.5 MPa and 50°C for 20 minutes, and then left to stand for 24 hours under conditions of normal pressure, 23°C, and 50% RH, and then measured at a peel speed of 300 mm / min.

[0056] The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in this embodiment preferably contains light-diffusing fine particles, which have a light-diffusing effect that allows the aforementioned slopes S1, S2, S3 and haze value to be adjusted to desired values.

[0057] The average particle size of the light-diffusing fine particles (as measured by centrifugal sedimentation light transmission method) is preferably 0.1 to 20 μm, more preferably 0.5 to 16 μm, particularly preferably 1 to 12 μm, and even more preferably 2 to 10 μm. The light-diffusing effect based on the particle size makes it easy to adjust the slopes S1, S2, and S3 and the haze value to desired values.

[0058] The average particle size measured by the centrifugal sedimentation light transmission method was measured using a centrifugal automatic particle size distribution analyzer (manufactured by Horiba, Ltd., product name "CAPA-700") using a measurement sample prepared by thoroughly stirring 1.2 g of light-diffusing microparticles and 98.8 g of isopropyl alcohol.

[0059] The content of the light-diffusing microparticles in the pressure-sensitive adhesive is preferably 1 to 70% by mass, more preferably 2 to 55% by mass, particularly preferably 3 to 40% by mass, even more preferably 4 to 30% by mass, and most preferably 4.5 to 25% by mass. The light-diffusing effect based on this content makes it easy to adjust the slopes S1, S2, S3, and haze value described above to desired values.

[0060] When the emitted light color is adjusted to yellow, it is preferable to select light-diffusing fine particles having an average particle size of preferably 0.1 to 20 μm, more preferably 0.5 to 12 μm, particularly preferably 1 to 8 μm, and even more preferably 2 to 4 μm, and to set the content of the light-diffusing fine particles in the adhesive to preferably 1 to 20 mass %, more preferably 2 to 12 mass %, particularly preferably 3 to 8 mass %, and even more preferably 4 to 6 mass %. This makes it easier to make the slope of the haze value a negative value, and makes it easier to adjust the emitted light color to yellow.

[0061] When adjusting the luminescent color to pale yellow, it is preferable to select light-diffusing microparticles having an average particle size of preferably 0.1 to 20 μm, more preferably 1 to 12 μm, particularly preferably 2 to 8 μm, and even more preferably 3 to 5 μm, and to set the content of the light-diffusing microparticles in the adhesive to preferably 0.1 to 20 mass %, more preferably 1 to 12 mass %, particularly preferably 2 to 8 mass %, and even more preferably 4 to 6 mass %. This makes it easier to set the aforementioned slope S3 to a predetermined value, and makes it easier to adjust the luminescent color to pale yellow.

[0062] When adjusting the emitted color to blue, it is preferable to select light-diffusing fine particles having an average particle size of preferably 0.1 to 20 μm, more preferably 1 to 17 μm, particularly preferably 5 to 14 μm, and even more preferably 8 to 11 μm, and to set the content of the light-diffusing fine particles in the adhesive to preferably 1 to 70 mass %, more preferably 8 to 40 mass %, particularly preferably 16 to 30 mass %, and even more preferably 20 to 25 mass %. This makes it easier to set the aforementioned slope S3 to a predetermined value, and makes it easier to adjust the emitted color to blue.

[0063] The type of adhesive constituting the adhesive layer of the adhesive sheet according to this embodiment is not particularly limited as long as it satisfies the above-described physical properties. For example, it may be any of acrylic adhesives, polyester adhesives, polyurethane adhesives, rubber adhesives, silicone adhesives, etc. Furthermore, the adhesive may be emulsion-type, solvent-type, or solventless, and may be crosslinked or non-crosslinked. Among these, acrylic adhesives are preferred, as they have excellent adhesive properties and optical properties. Crosslinked acrylic adhesives are preferred, and thermally crosslinked acrylic adhesives are even more preferred. Furthermore, the adhesive in this embodiment may be non-curable with active energy rays or curable with active energy rays. From the perspective of the SDGs, the adhesive may be made of a material with a high biomass content, a recyclable or reusable material, or a recycled or reused material.

[0064] Specifically, the adhesive in this embodiment is preferably a crosslinked adhesive composition (hereinafter sometimes referred to as "adhesive composition P") containing a (meth)acrylic acid ester polymer (A), a crosslinking agent (B), and light-diffusing microparticles (C). The adhesive obtained by crosslinking the adhesive composition P is likely to satisfy the above-mentioned physical properties. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Furthermore, the term "polymer" also includes the concept of "copolymer."

[0065] (1) Components of Pressure-Sensitive Adhesive Composition P (1-1) (Meth)acrylic Acid Ester Polymer (A) In the present embodiment, the (meth)acrylic acid ester polymer (A) preferably contains, as a monomer unit constituting the polymer, a reactive group-containing monomer having, in the molecule, a reactive group that reacts with the crosslinking agent (B). The reactive group derived from this reactive group-containing monomer reacts with the crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), thereby obtaining a pressure-sensitive adhesive having the desired cohesive strength.

[0066] Preferred examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), etc. Among these, a hydroxyl group-containing monomer or a carboxyl group-containing monomer, which has excellent reactivity with the crosslinking agent (B), is preferred, and a hydroxyl group-containing monomer is particularly preferred.

[0067] Examples of hydroxyl group-containing monomers include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, from the viewpoints of reactivity with the crosslinking agent (B) and copolymerizability with other monomers, (meth)acrylic acid hydroxyalkyl esters having a hydroxyalkyl group having 1 to 4 carbon atoms are preferred. Specific examples include 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate, with 2-hydroxyethyl acrylate or 4-hydroxybutyl acrylate being particularly preferred. These may be used alone or in combination of two or more.

[0068] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, acrylic acid is preferred in terms of the reactivity of the carboxyl group in the resulting (meth)acrylic acid ester polymer (A) with the crosslinking agent (B) and copolymerizability with other monomers. These may be used alone or in combination of two or more.

[0069] The (meth)acrylic acid ester polymer (A) preferably contains 1 to 40% by mass, more preferably 6 to 36% by mass, particularly preferably 12 to 32% by mass, even more preferably 18 to 28% by mass, and even more preferably 20 to 26% by mass of reactive group-containing monomers as monomer units constituting the polymer. This allows a good crosslinked structure to be formed in the resulting pressure-sensitive adhesive, resulting in favorable cohesive strength. Furthermore, the dispersibility of the light-diffusing fine particles (C) in the resulting pressure-sensitive adhesive tends to be good.

[0070] It is also preferable that the (meth)acrylic acid ester polymer (A) does not contain a carboxy group-containing monomer as a monomer unit constituting the polymer. Since a carboxy group is an acid component, the absence of a carboxy group-containing monomer can suppress acid-induced defects (corrosion, resistance change, etc.) even when the target to which the pressure-sensitive adhesive is applied contains a material that is susceptible to acid-induced defects, such as a transparent conductive film or metal film, such as tin-doped indium oxide (ITO). However, it is acceptable to contain a predetermined amount of a carboxy group-containing monomer to the extent that such defects do not occur. Specifically, it is acceptable for the (meth)acrylic acid ester polymer (A) to contain, as a monomer unit, a carboxy group-containing monomer in an amount of 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001% by mass or less.

[0071] The (meth)acrylic acid ester polymer (A) preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. This allows the polymer to exhibit good adhesiveness. The alkyl group may be linear or branched.

[0072] From the viewpoint of adhesiveness, the (meth)acrylic acid alkyl ester is preferably a (meth)acrylic acid alkyl ester in which the alkyl group has a carbon number of 1 to 20. Examples of the (meth)acrylic acid alkyl ester in which the alkyl group has a carbon number of 1 to 20 include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among these, from the viewpoint of further improving adhesiveness and making it easier to satisfy the above-mentioned physical properties, (meth)acrylic acid esters having an alkyl group containing 4 to 8 carbon atoms are preferred, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or isooctyl (meth)acrylate are particularly preferred, and n-butyl acrylate, 2-ethylhexyl acrylate, or isooctyl acrylate are even more preferred. These may be used alone or in combination of two or more.

[0073] The (meth)acrylic acid ester polymer (A) preferably contains 30 to 99 mass %, more preferably 40 to 90 mass %, particularly preferably 45 to 80 mass %, and even more preferably 50 to 70 mass % of (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. This allows a pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing the (meth)acrylic acid ester polymer (A) to exhibit suitable adhesiveness, and also allows suitable amounts of other monomer components such as reactive functional group-containing monomers to be introduced into the (meth)acrylic acid ester polymer (A).

[0074] The (meth)acrylic acid ester polymer (A) also preferably contains a monomer having an alicyclic structure in the molecule (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. Because the alicyclic structure-containing monomer is bulky, its presence in the polymer is presumed to increase the spacing between polymer molecules, which tends to impart flexibility to the resulting pressure-sensitive adhesive and provide good adhesiveness, and also tends to lower the storage modulus, improving conformability to steps and unevenness (hereinafter sometimes collectively referred to as "step conformability").

[0075] The carbon ring of the alicyclic structure in the alicyclic structure-containing monomer may be a saturated structure or may partially contain an unsaturated bond. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure (polycyclic structure) such as a bicyclic or tricyclic structure. From the viewpoint of optimizing the distance between the rings in the resulting (meth)acrylic acid ester polymer (A) and lowering the storage modulus, the alicyclic structure is preferably a polycyclic structure. Furthermore, in consideration of the compatibility of the (meth)acrylic acid ester polymer (A) with other components, the polycyclic structure is particularly preferably a bicyclic to tetracyclic structure. From the same viewpoint as above, the number of carbon atoms in the alicyclic structure (meaning the total number of carbon atoms in the ring, or the total number of carbon atoms in the case where multiple rings are present independently) is typically preferably 5 to 15, and particularly preferably 7 to 10.

[0076] Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among these, dicyclopentanyl (meth)acrylate (alicyclic structure carbon number: 10), adamantyl (meth)acrylate (alicyclic structure carbon number: 10), or isobornyl (meth)acrylate (alicyclic structure carbon number: 7) are preferred, as they exhibit good adhesion and better conformability to uneven surfaces. Isobornyl (meth)acrylate is particularly preferred, and isobornyl acrylate is even more preferred. These may be used alone or in combination of two or more.

[0077] When the (meth)acrylic acid ester polymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the alicyclic structure-containing monomer is preferably contained in an amount of 1 to 40 mass %, more preferably 4 to 32 mass %, particularly preferably 8 to 24 mass %, and even more preferably 12 to 16 mass %, from the viewpoint of lowering the storage modulus.

[0078] The (meth)acrylic acid ester polymer (A) also preferably contains a nitrogen-atom-containing monomer as a monomer unit constituting the polymer. The presence of the nitrogen-atom-containing monomer as a constituent unit in the polymer imparts a predetermined polarity to the pressure-sensitive adhesive, thereby making it possible to achieve excellent affinity even with adherends having a certain degree of polarity, such as glass. As the nitrogen-atom-containing monomer, a monomer having a nitrogen-containing heterocycle is preferred from the viewpoint of imparting appropriate rigidity to the (meth)acrylic acid ester polymer (A). Furthermore, from the viewpoint of increasing the degree of freedom of the nitrogen-atom-containing monomer-derived portion in the higher-order structure of the pressure-sensitive adhesive formed, it is preferable that the nitrogen-atom-containing monomer does not contain a reactive unsaturated double bond group other than one polymerizable group used in polymerization to form the (meth)acrylic acid ester polymer (A).

[0079] Examples of monomers having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine, which exhibits superior adhesive strength, is preferred, and N-acryloylmorpholine is particularly preferred. These may be used alone or in combination of two or more.

[0080] When the (meth)acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the nitrogen atom-containing monomer is preferably contained in an amount of 1 to 30 mass %, more preferably 2 to 20 mass %, particularly preferably 3 to 12 mass %, and even more preferably 4 to 8 mass %, which allows the resulting pressure-sensitive adhesive to fully exhibit excellent adhesive strength to glass.

[0081] The (meth)acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. As the other monomer, a monomer not containing a reactive functional group is preferred so as not to inhibit the above-described action of the reactive functional group-containing monomer. Examples of such monomers include (meth)acrylic acid alkoxyalkyl esters such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

[0082] The (meth)acrylic acid ester polymer (A) is preferably a linear polymer, since the linear polymer makes it easier for molecular chains to become entangled, and is expected to improve cohesive strength.

[0083] The (meth)acrylic acid ester polymer (A) may be a polymer obtained by solution polymerization, a polymer obtained without a solvent, or an emulsion polymerization. Among these, a solution polymer obtained by solution polymerization is preferred. By using a solution polymer, a high molecular weight polymer can be easily obtained, and a pressure-sensitive adhesive having excellent durability can be obtained.

[0084] The polymerization mode of the (meth)acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

[0085] The weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,600,000, particularly preferably 300,000 to 1,200,000, even more preferably 400,000 to 900,000, and most preferably 450,000 to 700,000. This tends to result in favorable storage modulus and adhesive strength of the resulting pressure-sensitive adhesive. Here, the weight-average molecular weight in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0086] In the pressure-sensitive adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more.

[0087] The content of the (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P according to this embodiment is preferably 50 to 99% by mass, more preferably 60 to 98% by mass, particularly preferably 65 to 97% by mass, further preferably 70 to 96% by mass, and particularly preferably 75 to 95% by mass, thereby obtaining good adhesive strength.

[0088] (1-2) Crosslinking Agent (B) The crosslinking agent (B) may be any crosslinking agent capable of reacting with the reactive group of the (meth)acrylic acid ester polymer (A). Examples of the crosslinking agent (B) include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. The crosslinking agent (B) may be used alone or in combination of two or more.

[0089] When the reactive group possessed by the (meth)acrylic acid ester polymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent that has high reactivity with the hydroxyl group.

[0090] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret and isocyanurate forms thereof, as well as adducts thereof that are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate, are preferred from the viewpoint of reactivity with hydroxyl groups.

[0091] The content of the crosslinking agent (B) in the pressure-sensitive adhesive composition P is preferably 0.01 to 2 parts by mass, more preferably 0.04 to 1 part by mass, particularly preferably 0.07 to 0.5 parts by mass, and even more preferably 0.1 to 0.2 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). This makes it easier for the resulting pressure-sensitive adhesive to have favorable cohesive strength and adhesive strength.

[0092] (1-3) Light-diffusing fine particles (C) The light-diffusing fine particles (C) may be any particles as long as they exhibit a predetermined light-diffusing property and enable the resulting pressure-sensitive adhesive layer and pressure-sensitive adhesive sheet to satisfy the above-mentioned physical properties.

[0093] Examples of light-diffusing particles (C) include inorganic light-diffusing particles such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide; organic light-diffusing particles such as acrylic resins, polystyrene resins, polyethylene resins, epoxy resins, and copolymers or mixtures thereof; light-diffusing particles made of silicon-containing compounds having an intermediate structure between inorganic and organic, such as silicone resins (e.g., the Tospearl series manufactured by Momentive Performance Materials Japan Co., Ltd.), and hybrid light-diffusing particles made of organic resins and silicone resins. Among these, light-diffusing particles made of silicone resins (silicon-containing compounds having an intermediate structure between inorganic and organic) are preferred. This makes it easier for the resulting pressure-sensitive adhesive layer to satisfy the above-mentioned physical properties. The above light-diffusing particles (C) may be used alone or in combination of two or more.

[0094] The shape of the light-diffusing fine particles (C) is preferably spherical, which allows uniform light diffusion, and is particularly preferably spherical, but is not limited thereto. The preferred average particle size of the light-diffusing fine particles (C) is as described above.

[0095] The refractive index of the light-diffusing fine particles (C) is preferably 1.30 to 2.00, more preferably 1.35 to 1.85, particularly preferably 1.40 to 1.65, even more preferably 1.42 to 1.55, and most preferably 1.43 to 1.45. The light-diffusing effect based on the difference in refractive index between the light-diffusing fine particles (C) and the matrix (particularly the matrix of the acrylic adhesive) makes it easy to adjust the slopes S1, S2, S3, and haze value to desired values. The refractive index of the light-diffusing fine particles can be determined by Method B of JIS K7142:2008.

[0096] The content of the light-diffusing microparticles (C) in the adhesive composition P is the same as the content of the light-diffusing microparticles in the adhesive described above, but is preferably 0.1 to 150 parts by mass, more preferably 1 to 100 parts by mass, particularly preferably 2 to 50 parts by mass, even more preferably 3 to 30 parts by mass, and of these, preferably 4 to 26 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A).

[0097] (1-4) Silane Coupling Agent (D) The pressure-sensitive adhesive composition P preferably further contains a silane coupling agent (D). This improves the adhesion of the resulting pressure-sensitive adhesive to a glass member when the adherend is a glass member. Furthermore, even when the adherend is a plastic plate, the resulting pressure-sensitive adhesive improves the adhesion to the plastic plate. This makes it easier for the resulting pressure-sensitive adhesive to achieve the desired adhesive strength.

[0098] The silane coupling agent (D) is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, which has good compatibility with the (meth)acrylic acid ester polymer (A) and has optical transparency.

[0099] Examples of such silane coupling agents (D) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane; silicon compounds having an epoxy structure such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, and 3-mercaptopropyldimethoxymethylsilane; Examples of suitable silicon compounds include hydroxyl group-containing silicon compounds, amino group-containing silicon compounds such as 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane, as well as condensates of at least one of these with alkyl group-containing silicon compounds such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used alone or in combination of two or more.

[0100] The content of the silane coupling agent (D) in the pressure-sensitive adhesive composition P is preferably 0.01 to 1 part by mass, more preferably 0.1 to 0.7 parts by mass, and particularly preferably 0.2 to 0.5 parts by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). This provides good compatibility with blending materials such as the (meth)acrylic acid ester polymer (A), and the resulting pressure-sensitive adhesive easily achieves the desired optical properties described above and exhibits good adhesion to the adherend.

[0101] (1-5) Various Additives If desired, various additives commonly used in acrylic pressure-sensitive adhesives may be added to the pressure-sensitive adhesive composition P, such as an active energy ray-curable component, a photopolymerization initiator, an ultraviolet absorber, an infrared absorber, a refractive index modifier, an antistatic agent, a colorant, a tackifier, a rust inhibitor, an antioxidant, a light stabilizer, a softener, etc. It should be noted that polymerization solvents and dilution solvents described below are not included in the additives constituting the pressure-sensitive adhesive composition P.

[0102] (2) Preparation of adhesive composition P The adhesive composition P can be produced by producing a (meth)acrylic acid ester polymer (A), mixing the obtained (meth)acrylic acid ester polymer (A) with a crosslinking agent (B) and light-diffusing fine particles (C), and optionally adding a silane coupling agent (D), additives, etc.

[0103] The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. The polymerization of the (meth)acrylic acid ester polymer (A) is preferably carried out by a solution polymerization method, using a polymerization initiator as desired. However, the present invention is not limited to this, and the polymerization may be carried out without a solvent. Examples of polymerization solvents include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

[0104] Examples of the polymerization initiator include azo compounds, organic peroxides, etc., and two or more of them may be used in combination. In the polymerization step, the weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

[0105] After the (meth)acrylic acid ester polymer (A) is obtained, the crosslinking agent (B), the light-diffusing fine particles (C), and, if desired, the silane coupling agent (D), additives, dilution solvent, etc. are added to the solution of the (meth)acrylic acid ester polymer (A) and mixed thoroughly to obtain a solvent-diluted adhesive composition P (coating solution). Note that, when any of the above components is used in a solid state, or when precipitation occurs when mixed with other components in an undiluted state, that component may be dissolved or diluted alone in a dilution solvent before being mixed with other components.

[0106] Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0107] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range that allows coating, and can be appropriately selected depending on the situation. For example, the pressure-sensitive adhesive composition P is diluted so that the concentration is 10 to 60 mass %. Note that the addition of a dilution solvent or the like is not a necessary condition for obtaining the coating solution, and as long as the pressure-sensitive adhesive composition P has a viscosity that allows coating, the addition of a dilution solvent is not necessary. In this case, the pressure-sensitive adhesive composition P becomes a coating solution in which the polymerization solvent for the (meth)acrylic acid ester polymer (A) is used as the dilution solvent.

[0108] (3) Formation of Pressure-Sensitive Adhesive Layer The pressure-sensitive adhesive layer in this embodiment preferably comprises a pressure-sensitive adhesive obtained by crosslinking (a coating layer of) the pressure-sensitive adhesive composition P. Crosslinking of the pressure-sensitive adhesive composition P can usually be carried out by a heat treatment. Note that this heat treatment can also serve as a drying treatment for volatilizing diluent solvents and the like from the coating layer of the pressure-sensitive adhesive composition P applied to a desired object.

[0109] The heating temperature for the heat treatment is preferably 50 to 150° C., and particularly preferably 70 to 120° C. The heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 2 minutes.

[0110] After the heat treatment, a curing period of about 1 to 2 weeks may be provided at room temperature (e.g., 23°C, 50% RH), if necessary. If this curing period is required, the pressure-sensitive adhesive is formed after the curing period has elapsed. If no curing period is required, the pressure-sensitive adhesive is formed after the heat treatment has been completed.

[0111] By the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is crosslinked via the crosslinking agent (B), and a pressure-sensitive adhesive is obtained.

[0112] (4) Physical Properties of the Pressure-Sensitive Adhesive (Pressure-Sensitive Adhesive Layer) (4-1) Gel Fraction The gel fraction of the pressure-sensitive adhesive in this embodiment is preferably 20 to 100%, more preferably 30 to 85%, particularly preferably 40 to 70%, even more preferably 45 to 60%, and most preferably 50 to 56%. This allows for good cohesive strength to be exerted, resulting in superior adhesive strength and step-following ability. The method for measuring the gel fraction is as shown in the test examples described below.

[0113] (4-2) Total Light Transmittance The lower limit of the total light transmittance of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to this embodiment is preferably 70% or more, more preferably 80% or more, particularly preferably 90% or more, and even more preferably 99% or more. This improves visibility as a display. Meanwhile, the upper limit of the total light transmittance is not particularly limited, but is usually 100% or less. Here, the total light transmittance in this specification is a value measured in accordance with JIS K7136:2000.

[0114] (4-3) Thickness of Pressure-Sensitive Adhesive Layer The thickness of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to this embodiment (measured in accordance with JIS K7130) is preferably 10 to 2000 μm, more preferably 20 to 1200 μm, particularly preferably 30 to 600 μm, and even more preferably 40 to 200 μm, from the viewpoints of adhesive strength and light diffusion properties.

[0115] (5) Specific Configuration of the Pressure-Sensitive Adhesive Sheet A specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment is shown in Figure 1. As shown in Figure 1, the pressure-sensitive adhesive sheet 1 according to one embodiment is composed of two release sheets 12a, 12b and a pressure-sensitive adhesive layer 11 sandwiched between the two release sheets 12a, 12b so as to be in contact with the release surfaces of the two release sheets 12a, 12b. Note that the release surface of the release sheet in this specification refers to the surface of the release sheet that has releasability, and includes both a surface that has been subjected to a release treatment and a surface that exhibits releasability even without being subjected to a release treatment.

[0116] The pressure-sensitive adhesive layer 11 is the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the above-described embodiment, and its physical properties and composition are as described above.

[0117] The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until the pressure-sensitive adhesive sheet 1 is used, and are peeled off when the pressure-sensitive adhesive sheet 1 (pressure-sensitive adhesive layer 11) is to be used. In the pressure-sensitive adhesive sheet 1 according to this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

[0118] Examples of materials that can be used as the release sheets 12a and 12b include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polyethylene naphthalate films, polybutylene terephthalate films, polyurethane films, ethylene vinyl acetate films, ionomer resin films, ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid ester polymer films, polystyrene films, polycarbonate films, polyimide films, and fluororesin films. Crosslinked films of these materials can also be used. Furthermore, laminated films of these materials may also be used. From the perspective of the SDGs, the material constituting the release sheets may be a material with a high biomass content, a recyclable or reusable material, or a recycled or reused material.

[0119] It is preferable that a release treatment be performed on the release surfaces of the release sheets 12 a and 12 b (particularly the surfaces that come into contact with the pressure-sensitive adhesive layer 11). Examples of release agents used for the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents.

[0120] There is no particular limitation on the thickness of the release sheets 12a and 12b, but it is usually about 20 to 150 μm.

[0121] Of the two release sheets 12a, 12b, it is preferred that one of the release sheets be a heavy release type release sheet having a high release strength, and the other be a light release type release sheet having a low release strength.

[0122] (6) Production of Pressure-Sensitive Adhesive Sheet As an example of the production of the pressure-sensitive adhesive sheet 1, the case where the pressure-sensitive adhesive composition P is used will be described. A coating solution of the pressure-sensitive adhesive composition P is applied to the release surface of one of the release sheets 12a (or 12b), and a heat treatment is performed to thermally crosslink the pressure-sensitive adhesive composition P to form a coating layer, after which the release surface of the other release sheet 12b (or 12a) is superimposed on the coating layer. If a curing period is required, a curing period is allowed, or if no curing period is required, the coating layer becomes the pressure-sensitive adhesive layer 11 as is. In this way, the pressure-sensitive adhesive sheet 1 is obtained. The conditions for the heat treatment and curing are as described above.

[0123] In another manufacturing example of the pressure-sensitive adhesive sheet 1, a coating liquid of the pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a, followed by a heat treatment to thermally crosslink the pressure-sensitive adhesive composition P and form a coating layer, thereby obtaining a release sheet 12a with a coating layer. Furthermore, a coating liquid of the pressure-sensitive adhesive composition P is applied to the release surface of the other release sheet 12b, followed by a heat treatment to thermally crosslink the pressure-sensitive adhesive composition P and form a coating layer, thereby obtaining a release sheet 12b with a coating layer. The release sheet 12a with a coating layer and the release sheet 12b with a coating layer are then bonded together so that the two coating layers are in contact with each other. If a curing period is required, a curing period is allowed; if no curing period is required, the laminated coating layers are left as is, forming the pressure-sensitive adhesive layer 11. This manufacturing example allows stable manufacturing even when the pressure-sensitive adhesive layer 11 is thick.

[0124] The coating solution of the pressure-sensitive adhesive composition P can be applied by, for example, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, or the like.

[0125] (7) Uses of the Pressure-Sensitive Adhesive Sheet The pressure-sensitive adhesive sheet 1 according to this embodiment can be suitably used to bond two display component members in a display having an RGB light source. In this display, the pressure-sensitive adhesive layer 11 acts to make it easier to adjust the emitted light color to a color other than white.

[0126] One or both of the two display component members bonded by the pressure-sensitive adhesive layer 11 may be rigid or almost rigid, or may be flexible, such as a film. The pressure-sensitive adhesive sheet 1 according to this embodiment can bond even two rigid bodies well.

[0127] Specifically, as will be described later, the pressure-sensitive adhesive sheet 1 according to the present embodiment can be suitably used for bonding a protective panel to a display module equipped with a backlight or other optical member, or for bonding a backlight to a display unit such as a liquid crystal panel or other optical member. However, the present invention is not limited to this, and the pressure-sensitive adhesive sheet 1 can be used for bonding desired display component members together.

[0128] [Display body] A display body according to one embodiment of the present invention is a display body equipped with a backlight having a blue light source, a green light source, and a red light source, and display body components located on the display surface side of the backlight are bonded to other display body components (including the backlight) via the adhesive layer of the adhesive sheet according to the embodiment described above.

[0129] The blue, green and red light sources are preferably light emitting diodes (LEDs), particularly preferably mini-LEDs or micro-LEDs.

[0130] As shown in Figure 2, a display body 2A according to one embodiment is configured to include a first display body component 21 (one display body component), a second display body component 22 (another display body component), and an adhesive layer 11 located between them and bonding the first display body component 21 and the second display body component 22 to each other.

[0131] One of the first display body component 21 and the second display body component 22 may have irregularities on the surface that is bonded to the adhesive layer 11. In the embodiment shown in Fig. 2, the first display body component 21 has irregularities due to the printing layer 23 on the surface that faces the adhesive layer 11.

[0132] The adhesive layer 11 in the display member 2A is the adhesive layer 11 of the adhesive sheet 1 described above.

[0133] Examples of the display 2A include a liquid crystal display (LCD) having a backlight with an RGB light source, a light emitting diode (LED) display, etc., and may also be a touch panel.

[0134] The first display member 21 is preferably a protective panel made of a glass plate, a plastic plate, or a laminate containing these. In this case, the printing layer 23 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the first display member 21.

[0135] The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda-lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass, etc. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, and preferably 0.2 to 2 mm.

[0136] The plastic plate is not particularly limited, and examples thereof include an acrylic plate, a polycarbonate plate, etc. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, and preferably 0.4 to 3 mm.

[0137] On one or both sides of the glass plate or plastic plate, various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, anti-glare layer, etc.) may be provided, or optical members may be laminated. Furthermore, the transparent conductive film and metal layer may be patterned.

[0138] The second display component 22 is preferably an optical element to be attached to the first display component 21, a display module (e.g., a liquid crystal (LCD) module, a light emitting diode (LED) module, etc.), an optical element as part of a display module, or a laminate including a display module.

[0139] Examples of the optical member include a shatterproof film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retardation film), a viewing angle compensation film, a brightness improvement film, a contrast improvement film, a liquid crystal polymer film, a diffusion film, a semi-transmitting reflective film, a transparent conductive film, etc. An example of the shatterproof film is a hard coat film in which a hard coat layer is formed on one side of a base film.

[0140] The material constituting the printing layer 23 is not particularly limited, and known printing materials can be used. The thickness of the printing layer 3, i.e., the height of the step, is preferably 0.5 to 50 μm, more preferably 1 to 30 μm, and particularly preferably 3 to 20 μm. When the thickness of the printing layer 3 is within the above range, the step-following ability of the pressure-sensitive adhesive layer 11 is effectively exhibited, and the concealing property that is the purpose of the printing layer 3 can be sufficiently ensured. Note that the printing layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the display component.

[0141] To manufacture the display body 2A, as an example, one of the release sheets 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is attached to the surface of the first display body component 21 on which the printing layer 3 is present.

[0142] Next, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 is bonded to the second display body component 22 to obtain a display body. As another example, the bonding order of the first display body component 21 and the second display body component 22 may be reversed.

[0143] 3, a display 2B according to another embodiment includes a backlight 30, an adhesive layer 11 laminated on the backlight 30, and a display unit 40 laminated on the adhesive layer 11. The backlight 30 in this display 2B corresponds to the second display component, and the display unit 40 corresponds to the first display component. The backlight 30 in this display 2B corresponds to a direct-type backlight.

[0144] A preferred type of display 2B is, for example, a liquid crystal display (LCD), but is not limited to this.

[0145] The adhesive layer 11 in the display body 2B is the adhesive layer 11 of the adhesive sheet 1 described above.

[0146] The backlight 30 is configured to include one or more substrates 31 and a plurality of light emitters 32 provided on the substrates 31. The backlight 30 has projections and recesses due to the plurality of light emitters 32.

[0147] There are no particular limitations on the substrate 31, and a substrate that is generally used for backlights can be used. This substrate 31 is usually a printed circuit board (PCB).

[0148] The substrate 31 may be integrally formed so that a plurality of light emitters 32 are mounted together, or may be formed separately so that one light emitter 32 is mounted on one substrate 31. When formed separately, each substrate 31 is usually fixed to a frame, a support, a housing, etc. In this embodiment, as shown in Fig. 3, the substrate 31 is preferably integrally formed so that a plurality of light emitters 32 are mounted together.

[0149] A reflective layer or a reflective member may be formed on the surface of the substrate 31 facing the pressure-sensitive adhesive layer 11. This can effectively improve the brightness of the backlight 30. Known materials can be used for the reflective layer or the reflective member.

[0150] Examples of types of the light emitter 32 include light-emitting diodes (LEDs), laser diodes (LDs), organic electroluminescence light-emitting elements, inorganic electroluminescence light-emitting elements, etc. Among these, from the viewpoint of adjusting the emitted light color by the pressure-sensitive adhesive layer 11, LEDs are preferred, and mini-LEDs or micro-LEDs are particularly preferred.

[0151] The thickness (height) of the light emitter 32 is preferably 10 to 300 μm, more preferably 30 to 200 μm, particularly preferably 50 to 150 μm, and further preferably 80 to 100 μm.

[0152] The width of the gap between adjacent light emitters 32 is preferably 0.01 to 10 mm, more preferably 0.1 to 4 mm, and even more preferably 0.5 to 2 mm.

[0153] The shape of the light emitter 32 is not particularly limited, but is usually a rectangular parallelepiped, a hemisphere, etc. The size of the light emitter 32 is also not particularly limited, but from the viewpoint of light emitter sealing, the side or diameter in a planar view is preferably 0.01 to 100 mm, more preferably 0.1 to 10 mm, particularly preferably 0.2 to 5 mm, and further preferably 0.5 to 2 mm.

[0154] The display unit 40 may be, for example, a liquid crystal panel, but is not limited to this, and may be, for example, a part of the components of the liquid crystal panel, or an optical member (for example, a light diffusion plate or an ultraviolet absorbing filter) used in combination with the liquid crystal panel to add or enhance its functions. Any known display unit may be used as the display unit 40.

[0155] To manufacture the display body 2B according to this embodiment, for example, one release sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 is attached to the side of the backlight 30 on which the light-emitting body 32 is present.

[0156] Next, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 is bonded to the display unit 40. As another example, the bonding order of the backlight 30 and the display unit 40 may be reversed.

[0157] Here, a desired optical member may be provided between the pressure-sensitive adhesive layer 11 and the display section 40, or on the surface of the display section 40 opposite to the pressure-sensitive adhesive layer 11. Examples of such optical members include a brightness enhancement film, a contrast enhancement film, a viewing angle compensation film, a transparent conductive film, a liquid crystal polymer film, a semi-transmissive reflective film, a shatterproof film, and a light diffusion plate.

[0158] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0159] For example, one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted.

[0160] In this specification, when it is stated that "X to Y" (X and Y are any numbers), it means "X or more and Y or less" unless otherwise specified, and also means "preferably greater than X" or "preferably smaller than Y". Furthermore, when it is stated that "X or more" (X is any number), it means "preferably greater than X" unless otherwise specified, and when it is stated that "Y or less" (Y is any number), it also means "preferably smaller than Y" unless otherwise specified.

[0161] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0162] Example 1 1. Preparation of (meth)acrylic acid ester polymer 27.5 parts by mass of n-butyl acrylate, 27.5 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobornyl acrylate, 5 parts by mass of N-acryloylmorpholine, and 25 parts by mass of 2-hydroxyethyl acrylate were copolymerized by solution polymerization to prepare a (meth)acrylic acid ester polymer (A). The molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described below, and the weight average molecular weight (Mw) was found to be 500,000.

[0163] 2. Preparation of adhesive composition 100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth)acrylic acid ester polymer (A) obtained in the above step (1), 0.15 parts by mass of an isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., product name "Takenate D-101E") as the crosslinking agent (B), 5 parts by mass of light-diffusing fine particles (C1; manufactured by Momentive Performance Materials Japan, Inc., product name "Tospearl 145", average particle size: 4.5 μm, refractive index: 1.43) made of a silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) as the light-diffusing fine particles (C), and 0.26 parts by mass of 3-glycidoxypropyltrimethoxysilane as the silane coupling agent (D) were mixed, thoroughly stirred, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition.

[0164] Here, the formulations (solid content equivalent) of the pressure-sensitive adhesive compositions when the (meth)acrylic acid ester polymer (A) is taken as 100 parts by mass (solid content equivalent) are shown in Table 1. Details of the abbreviations and the like shown in Table 1 are as follows. [(Meth)acrylic acid ester polymer (A)] BA: n-butyl acrylate 2EHA: 2-ethylhexyl acrylate IBXA: isobornyl acrylate ACMO: N-acryloylmorpholine HEA: 2-hydroxyethyl acrylate [Light-diffusing particles (C)] C1: light-diffusing particles made of silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "Tospearl 145", average particle size: 4.5 μm, refractive index: 1.43). C2: light-diffusing particles made of silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "Tospearl 120", average particle size: 2.0 μm, refractive index: 1.43). C3: Light-diffusing fine particles made of silicone resin (a silicon-containing compound with an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "Tospearl 1100", average particle size: 11 μm, refractive index: 1.43)

[0165] 3. Production of Pressure-Sensitive Adhesive Sheet The obtained coating solution of the pressure-sensitive adhesive composition was applied using a knife coater to the release-treated surface of a heavy-release type release sheet R1, which was prepared by treating one side of a polyethylene terephthalate film with a silicone-based release agent, and then the sheet was heated at 90°C for 1 minute to form a coating layer.

[0166] Next, the coating layer on the release sheet R1 obtained above was bonded to a light-release type release sheet R2, which was a polyethylene terephthalate film with one side treated with a silicone-based release agent, so that the release-treated surface of the release sheet R2 was in contact with the coating layer, thereby producing an adhesive sheet consisting of release sheet R2 / coating layer of adhesive layer (thickness: 50 μm) / release sheet R1.

[0167] The thickness of the pressure-sensitive adhesive layer was measured in accordance with JIS K7130 using a constant pressure thickness measuring device (manufactured by Teclock Corporation, product name "PG-02") (the same applies hereinafter). Furthermore, it was confirmed that the release strength of release sheet R1 was greater than that of release sheet R2 in the obtained pressure-sensitive adhesive sheet.

[0168] [Examples 2 to 3, Comparative Examples 1 to 5] Pressure-sensitive adhesive sheets were produced in the same manner as in Example 1, except that the type and amount of light-diffusing fine particles (C) and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. In Comparative Example 2, C2 and C3 were mixed and blended as the light-diffusing fine particles (C). In Comparative Example 3, two 50 μm-thick pressure-sensitive adhesive layers were laminated to form a 100 μm-thick pressure-sensitive adhesive layer.

[0169] The weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> GPC measurement device: HLC-8020, manufactured by Tosoh Corporation GPC columns (passed in the following order): TSK guard column HXL-H, TSK gel GMHXL (x2), TSK gel G2000HXL, manufactured by Tosoh Corporation Measurement solvent: tetrahydrofuran Measurement temperature: 40°C

[0170] [Test Example 1] (Measurement of gel fraction) The pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples were cut to a size of 80 mm x 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass was weighed using a precision balance. The mass of the mesh alone was subtracted to calculate the mass of the pressure-sensitive adhesive alone. This mass was designated M1.

[0171] Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23°C) for 24 hours. The adhesive was then removed and air-dried for 24 hours in an environment with a temperature of 23°C and a relative humidity of 50%, and then dried in an oven at 80°C for 12 hours. After drying, the mass was weighed using a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. This mass was designated M2. The gel fraction (%) was expressed as (M2 / M1) x 100. The results are shown in Table 2.

[0172] [Test Example 2] (Haze Value Measurement) The adhesive layer of the pressure-sensitive adhesive sheet produced in Examples and Comparative Examples was attached to glass, and this was used as a measurement sample.After background measurement was performed on glass, the measurement sample was measured according to JIS K7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SH7000") to measure the haze value (%; H(450)) by light with a wavelength of 450 nm, the haze value (%; H(550)) by light with a wavelength of 550 nm, the haze value (%; H(650)) by light with a wavelength of 650 nm, and the haze value (total light haze value) (%).The results are shown in Table 2.

[0173] Also, the slope S1 expressed by the following formula (1), the slope S2 expressed by the following formula (2), and the slope S3 expressed by the following formula (3) were calculated. Furthermore, the ratio (H(450) / H(550)) of the haze value (H(450)) to the haze value (H(550)), and the ratio (H(650) / H(550)) of the haze value (H(450)) to the haze value (H(550)) were calculated. The results are also shown in Table 2. S1=(H(650)-H(450)) / 200 (1) S2=(H(550)-H(450)) / 100 (2) S3=(H(650)-H(550)) / 100 (3)

[0174] [Test Example 3] (Measurement of total light transmittance) The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in the Examples and Comparative Examples was attached to glass, and this was used as a measurement sample. After background measurement was performed on the glass, the total light transmittance (%) of the measurement sample was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH5000") in accordance with JIS K7136:2000. The results are shown in Table 2.

[0175] [Test Example 4] (Measurement of adhesive strength) The release sheet R2 was peeled off from the pressure-sensitive adhesive sheets produced in the Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was attached to an easy-adhesion layer of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "Cosmoshine PET A4360", thickness: 100 μm) having an easy-adhesion layer, to obtain a release sheet R1 / adhesive layer / PET film laminate. The obtained laminate was cut into a width of 25 mm and a length of 100 mm.

[0176] The release sheet R1 was peeled from the laminate under an environment of 23°C and 50% RH, and the exposed adhesive layer was attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). It was then pressurized for 20 minutes at 0.5 MPa and 50°C in an autoclave manufactured by Kurihara Manufacturing Co., Ltd. The sample was then left for 24 hours under conditions of 23°C and 50% RH, and the adhesive strength (before UV; N / 25 mm) was measured using a tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon") at a peel speed of 300 mm / min and a peel angle of 180°. Measurements were conducted under conditions other than those described here in accordance with JIS Z0237:2022. The results are shown in Table 2.

[0177] [Test Example 5] (Evaluation of Color) The adhesive layer of the pressure-sensitive adhesive sheet produced in the Examples and Comparative Examples was attached to a soda-lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., 70 mm long x 70 mm wide x 1.1 mm thick) to prepare a sample (the two release sheets had already been peeled off). The sample was placed 3 cm away from a white light source (LED; manufactured by Panasonic Corporation, product name "LDL40SN2225", total luminous flux 2500 lm, color temperature 5000 K) with the glass plate facing the white light source. The color of the white light source viewed through the sample was then visually confirmed. The results are shown in Table 2.

[0178] [Test Example 6] (Evaluation of Concealing Properties) The adhesive layer of the adhesive sheet produced in the Examples and Comparative Examples was attached to a soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd., 70 mm long x 70 mm wide x 1.1 mm thick) to prepare a sample (the two release sheets had already been peeled off). Meanwhile, white paper with the following two sizes of letters printed in black was used as the evaluation standard. 1... Font size: 16 pt, Font: MS Gothic, Character string: aiueo 2... Font size: 8 pt, Font: MS Gothic, Character string: aiueo

[0179] The sample was placed at a position 3 cm away from the evaluation standard object, with the glass plate facing the evaluation standard object. Then, at a position 50 cm away from the sample, the characters on the evaluation standard object were visually observed through the sample, and the degree of visibility of the characters was confirmed according to the following criteria to evaluate the hiding power. The results are shown in Table 2. A: 1 is visible, but 2 is difficult to see. F: Both 1 and 2 are easily visible.

[0180]

[0181]

[0182] As can be seen from Table 2, the PSA sheets produced in the examples were able to adjust the color of emitted light to a color other than white. Furthermore, the PSA sheets were also excellent in hiding power and adhesive strength.

[0183] The pressure-sensitive adhesive sheet according to the present invention is suitable for use in a display having an RGB light source, particularly a blue LED, a green LED and a red LED, in the backlight.

[0184] DESCRIPTION OF SYMBOLS 1... Adhesive sheet 11... Adhesive layer 12a, 12b... Release sheets 2A, 2B... Display body 21... First display body constituent member 22... Second display body constituent member 23... Printed layer 30... Backlight 31... Substrate 32... Light emitter 40... Display section

Claims

1. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein, when the haze value (%) of the pressure-sensitive adhesive layer measured with a light beam having a wavelength of 450 nm is H(450) and the haze value (%) of the pressure-sensitive adhesive layer measured with a light beam having a wavelength of 650 nm is H(650), the absolute value of the slope S1 expressed by the following formula (1) is greater than 0.026, the haze value of the pressure-sensitive adhesive layer is 10% or more and 100% or less, and the adhesive strength of the pressure-sensitive adhesive sheet to soda-lime glass is 1 N / 25 mm or more. S1 = (H(650) - H(450)) / 200 ... (1) 2. A pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer, wherein, when the haze value (%) of the pressure-sensitive adhesive layer measured with a light beam having a wavelength of 450 nm is H(450), the haze value (%) of the pressure-sensitive adhesive layer measured with a light beam having a wavelength of 550 nm is H(550), and the haze value (%) of the pressure-sensitive adhesive layer measured with a light beam having a wavelength of 650 nm is H(650), at least one of the absolute value of the slope S2 expressed by the following formula (2) and the absolute value of the slope S3 expressed by the following formula (3) is 0.032 or more, the haze value of the pressure-sensitive adhesive layer is 10% or more and 100% or less, and the adhesive strength of the pressure-sensitive adhesive sheet to soda-lime glass is 1 N / 25 mm or more. S2=(H(550)-H(450)) / 100 ... (2) S3=(H(650)-H(550)) / 100 ... (3) 3. The adhesive sheet according to claim 1, characterized in that the slope S1 exhibits a negative value.

4. The adhesive sheet according to claim 2, wherein the slopes S2 and S3 exhibit negative values.

5. The pressure-sensitive adhesive sheet according to claim 1 or 2, characterized in that when the haze value (%) of the pressure-sensitive adhesive layer by light having a wavelength of 550 nm is H(550), the slope S3 expressed by the following formula (3) is 0 or more and 0.015 or less: S3 = (H(650) - H(550)) / 100 ... (3) 6. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the slope S3 expressed by the following formula (3) is greater than 0.015 when the haze value (%) of the pressure-sensitive adhesive layer measured by light with a wavelength of 550 nm is H(550): S3 = (H(650) - H(550)) / 100 ... (3) 7. The adhesive sheet according to claim 1 or 2, characterized in that the gel fraction of the adhesive constituting the adhesive layer is 20% or more and 100% or less.

8. The adhesive sheet according to claim 1 or 2, characterized in that the adhesive constituting the adhesive layer contains light-diffusing fine particles.

9. The pressure-sensitive adhesive sheet according to claim 8, characterized in that the average particle size of the light-diffusing fine particles is 0.1 μm or more and 20 μm or less.

10. The pressure-sensitive adhesive sheet according to claim 8, wherein the refractive index of said light-diffusing fine particles is 1.30 or more and 2.00 or less.

11. The adhesive sheet according to claim 8, wherein the content of the light diffusing microparticles in the adhesive is 1% by mass or more and 70% by mass or less.

12. The pressure-sensitive adhesive sheet according to claim 8, wherein the light-diffusing particles are made of silicone resin.

13. The adhesive sheet according to claim 1 or 2, wherein the adhesive constituting the adhesive layer is an acrylic adhesive.

14. The adhesive sheet according to claim 1 or 2, characterized in that the thickness of the adhesive layer is 10 μm or more and 2000 μm or less.

15. The adhesive sheet according to claim 1 or 2, characterized in that the adhesive sheet comprises two release sheets, and the adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets.

16. The adhesive sheet according to claim 1 or 2, which is used to bond two display component members in a display having blue, green and red light sources.

17. A display equipped with a backlight having blue, green and red light sources, wherein a display component located closer to the display surface than the backlight is bonded to another display component via an adhesive layer of the adhesive sheet according to claim 1 or 2.

18. The display according to claim 17, wherein the blue light source, the green light source and the red light source are each a light-emitting diode.

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