Optical pressure-sensitive adhesive sheet with release liner

Abstract

The invention relates to an optical adhesive sheet with a release liner. The invention provides an adhesive sheet with a release liner, which is capable of detecting electric charges via the release liner in a state that the adhesive sheet is adhered to an adherend provided with an optical member capable of sensing electric charges. An optical adhesive sheet (10) with a release liner is provided with: a release liner (2) having a release treatment surface (2a) and a non-release treatment surface (2b); and an adhesive layer (1) formed on the peeling treatment surface (2a) of the peeling liner (2). The surface resistance value of the non-peeling treatment surface (2b) of the peeling pad (2) is 1012 Omega or less, and the dielectric constant of the non-peeling treatment surface (2b) of the peeling pad (2) at at least one frequency in the frequency range of 100 Hz to 10 kHz is 7.5 or less.

Description

Technical Field

[0001] This invention relates to an optical adhesive sheet with a release liner. Background Technology

[0002] In recent years, image display devices such as liquid crystal displays (LCDs) and organic OLED displays (OLEDs) have been widely used in various fields, along with touch panels incorporating touch sensors. These image display devices and touch panels have a structure in which various optical components, such as polarizing films, phase retardation films, optical compensation films, touch sensor films, and cover films, are laminated on the image display panel. In applications where these optical components are bonded, adhesive sheets with adhesive layers are used. For example, optical adhesive sheets are used in bonding various optical components in image display devices (see, for example, Patent Documents 1 to 3).

[0003] On the other hand, for example, in applications such as smartphones and tablet terminals, the development of repeatedly bendable (foldable) display panels is underway. Specifically, foldable display panels can repeatedly deform between a curved shape and a flat, non-curved shape. In such foldable display panels, the components in the stacked structure are manufactured in a manner that allows for repeated bending, and the bonding between such components uses thin optical adhesive sheets. Optical adhesive sheets for flexible devices such as foldable display panels are described, for example, in Patent Document 4 below.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2003-238915

[0007] Patent Document 2: Japanese Patent Application Publication No. 2003-342542

[0008] Patent Document 3: Japanese Patent Application Publication No. 2004-231723

[0009] Patent Document 4: Japanese Patent Application Publication No. 2018-111754 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] In the manufacturing process of the aforementioned optical components, optical adhesive sheets are sometimes attached to the optical components while still having a release liner attached. When the aforementioned optical components include components that sense electrical charges, such as touch sensors, it is sometimes necessary to detect the charge through the release liner side while the adhesive sheet with the release liner is attached.

[0012] The present invention is an invention for solving such a problem, and its object is to provide an adhesive sheet with a release liner, which can detect charge through the release liner while the adhesive sheet is attached to an object having an optical component that senses charge.

[0013] means for solving problems

[0014] This invention provides an optical adhesive sheet with a release liner, wherein the optical adhesive sheet with a release liner comprises: a release liner having a release-treated surface and a non-release-treated surface; and an adhesive layer formed on the release-treated surface of the release liner, wherein the surface resistivity of the non-release-treated surface of the release liner is 10 Ω. 12 The dielectric constant of the non-peeled surface of the release liner is 7.5 or less at at least one frequency in the frequency range of 100Hz to 10kHz.

[0015] The maximum value of the dielectric constant of the non-peeled surface of the peeling pad in the frequency range of 100Hz to 10kHz is preferably 7.5 or less.

[0016] The dielectric constant of the non-peeled surface of the peeling pad is preferably 1.5 or higher at a frequency of 1000 kHz.

[0017] The ratio of the dielectric constant of the adhesive layer at a frequency of 10 kHz to the dielectric constant of the non-removable surface of the release liner at a frequency of 10 kHz [adhesive layer / release liner] is preferably 1.5 or higher.

[0018] On the adhesive surface of the adhesive layer opposite to the adhesive surface having the release liner, a release liner is preferably provided, which has a smaller peel force on the adhesive surface of the adhesive layer than the release liner.

[0019] The adhesive sheet with release liner for optical applications is preferably used for bonding touch panels to glass.

[0020] Invention Effects

[0021] The optical adhesive sheet with release liner of the present invention can detect charge through the release liner when the adhesive sheet is attached to an object having an optical component that senses charge. Therefore, for example, it is possible to confirm charge sensing through the release liner using a conductor while the release liner is attached to the adhesive sheet. Attached Figure Description

[0022] Figure 1 This is a schematic diagram (cross-sectional view) illustrating one embodiment of the optical adhesive sheet with a release liner according to the present invention.

[0023] Figure 2This indicates the flatness of the test piece during the low-temperature bendability evaluation conducted in the examples.

[0024] Figure 3 This indicates the bending state of the test piece during the low-temperature bending evaluation conducted in the examples.

[0025] Label Explanation

[0026] 10 Optical Adhesive Sheets with Release Pads

[0027] 1 adhesive sheet

[0028] 2, 3 Peeling the gasket Detailed Implementation

[0029] [Optical adhesive sheet with release liner]

[0030] The optical adhesive sheet with a release liner of the present invention comprises at least: a release liner having a release-treated surface and a non-release-treated surface; and an adhesive layer formed on the release-treated surface of the release liner. The release liner serves to protect the adhesive surface that has been in contact until the adhesive sheet is used, and is peeled off when the adhesive surface is adhered.

[0031] An embodiment of the optical adhesive sheet with a release liner of the present invention is shown in [the figure]. Figure 1 . Figure 1 The optical adhesive sheet 10 with a release liner includes an adhesive sheet 1, a release liner 2 (first release liner), and a release liner 3 (second release liner). The release liner 2 has a release-treated surface 2a obtained by treatment with a release agent and a non-release-treated surface 2b located opposite to the release-treated surface 2a and not treated with a release agent. The adhesive sheet 1 is formed on the release-treated surface 2a side of the release liner 2, and the adhesive sheet 1 contacts the release-treated surface 2a of the release liner 2 in a peelable manner. The release liner 3, like the release liner 2, has a release-treated surface and a non-release-treated surface located opposite to the release-treated surface, and the release-treated surface is peelably in contact with the adhesive sheet 1 on the side of the adhesive sheet 1 opposite to the side that contacts the release liner 2. That is, the optical adhesive sheet 10 with a release liner includes the release liner 2, the adhesive sheet 1, and the release liner 3 sequentially in the thickness direction. The optical adhesive sheet 10 with a release liner extends in a direction orthogonal to the thickness direction (surface direction).

[0032] (Peeling off the liner)

[0033] The surface resistivity of at least one non-peeled surface of the release liner (e.g., non-peeled surface 2b of release liner 2) of the optical adhesive sheet with release liner of the present invention is 10. 12 Ω or less, preferably 10 11 Ω or less, more preferably 10 10Below Ω. It should be noted that in this specification, the surface resistivity value is sometimes given as 10 Ω. 12 Release pads with an Ω or less are referred to as "release pads of the present invention".

[0034] The non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention has a dielectric constant of 7.5 or less at at least one frequency in the frequency range of 100 Hz to 10 kHz, preferably 7 or less, and more preferably 6 or less. The dielectric constant at the aforementioned at least one frequency is, for example, 0.5 or more, or may be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, or 3.0 or more.

[0035] Since the surface resistance and dielectric constant of the release liner of the present invention are within the aforementioned ranges, it is inferred that the release liner has a small electrostatic capacitance, allowing charge migration and easy passage of charge in the thickness direction. Furthermore, charging is suppressed, preventing the adsorption of foreign matter such as dust. Even when the adhesive sheet with the release liner of the present invention is attached to an object containing an optical component that senses charge, the charge can be detected through the release liner. Therefore, for example, with the release liner attached to the adhesive sheet, it is possible to use a conductor through the release liner to confirm the sensing of charge and the presence or absence of changes in charge quantity.

[0036] The maximum value of the dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention in the frequency range of 100Hz to 10kHz is preferably 7.5 or less, more preferably 7 or less. That is, the dielectric constant is preferably within the above range throughout the entire frequency range of 100Hz to 10kHz. When the maximum value is 7.5 or less, it is easier to detect changes in charge over a wide frequency range. The maximum value is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, or 4.0 or more.

[0037] The dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention at a frequency of 100 Hz is preferably 9.0 or less, more preferably 8.5 or less, even more preferably 7.5 or less, and may also be 7.0 or less, 6.5 or less, or 5.5 or less. When the dielectric constant is 9.0 or less, it is easier to detect changes in charge at a frequency of 100 Hz. The dielectric constant is, for example, 0.5 or more, and may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, or 4.0 or more.

[0038] The dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention at a frequency of 1 kHz is preferably 8.0 or less, more preferably 7.5 or less, even more preferably 7.0 or less, and may also be 6.5 or less, 6.0 or less, or 5.0 or less. When the dielectric constant is 8.0 or less, it is easier to detect changes in charge at a frequency of 1 kHz. The dielectric constant is, for example, 0.5 or more, and may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, or 3.0 or more.

[0039] The dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention is preferably 7.5 or less at a frequency of 10 kHz, more preferably 6.5 or less, and even more preferably 5.5 or less. When the dielectric constant is 7.5 or less, it is easier to detect changes in charge at a frequency of 10 kHz. The dielectric constant may be 0.5 or more, or it may be 1.0 or more, 1.5 or more, or 2.0 or more.

[0040] The dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention is preferably 4.0 or less at a frequency of 100 kHz, more preferably 3.5 or less, and even more preferably 3.0 or less. When the dielectric constant is 4.0 or less, it is easier to detect changes in charge at a frequency of 100 kHz. The dielectric constant is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, or 2.0 or more.

[0041] The dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention is preferably 3.0 or less, more preferably 2.5 or less, at a frequency of 1000 kHz. When the dielectric constant is 3.0 or less, it is easier to detect changes in charge at a frequency of 1000 kHz.

[0042] The dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention is preferably 1.5 or more, more preferably 1.7 or more, at a frequency of 1000 kHz. When the dielectric constant is 1.5 or more, it tends to have a good balance with the surface resistance value. Furthermore, it is preferable that the dielectric constants at frequencies of 100 Hz, 1 kHz, 10 kHz, and 100 kHz are within the aforementioned ranges.

[0043] The ratio of the dielectric constant of the non-peeled surface (e.g., non-peeled surface 2b) of the release liner of the present invention at 1 kHz to the dielectric constant at 1000 kHz [1 kHz / 1000 kHz] is preferably 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. When the ratio is 3.0 or less, the dielectric constant is stable in the frequency range of 1 to 1000 kHz, and the detection capability of charge change has low frequency dependence, resulting in excellent detection stability. The ratio is preferably 1.0 or more.

[0044] When the adhesive sheet described above is a double-sided adhesive sheet, each adhesive surface can be protected by two separate release liner sheets. For example, as Figure 1 As shown, the optical adhesive sheet with a release liner of the present invention comprises a first release liner provided in a peelable manner on one adhesive surface of the adhesive sheet, and a second release liner may also be provided in a peelable manner on the other adhesive surface of the adhesive sheet until use. The second release liner may be the release liner of the present invention, or it may be any other release liner besides the release liner of the present invention. From the viewpoint of preventing accidental separation when using the adhesive sheet with the release liner of the present invention, it is preferable that the two release liners have different peeling forces on the adhesive surface. Furthermore, in this case, it is preferable that the release liner of the present invention, as the first release liner, is a heavier release liner than the second release liner, and the second release liner is a lighter release liner than the first release liner. This is because, since the charge can be detected while the release liner of the present invention is adhered to the substrate, it is preferable to adhere it to the substrate together with the adhesive sheet.

[0045] That is, the optical adhesive sheet with release liner of the present invention preferably has a release liner on the adhesive surface opposite to the adhesive surface having the release liner of the present invention, wherein the release liner has a smaller peel force on the adhesive surface of the adhesive sheet than the release liner of the present invention. In this case, the release liner of the present invention functions as a heavy release liner, and the other release liner functions as a light release liner. The adhesive sheet is preferably composed of the adhesive layer of the present invention described later.

[0046] The release liner of the present invention has a release treatment surface (the surface in contact with the adhesive sheet) subjected to a release treatment. That is, the release liner may have a release treatment layer.

[0047] There are no particular limitations on the substrate for the aforementioned release liner; any known or commonly used substrate can be selected. Examples include: polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate copolymer film, ionomer resin film, ethylene-(meth)acrylate copolymer film, ethylene-(meth)acrylate copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorinated resin film, etc. Crosslinked films of these films can also be listed. Furthermore, laminated films of these films can also be used.

[0048] Examples of release agents used for stripping processes include: alkyd, polysiloxane, fluorinated, unsaturated polyester, polyolefin, and wax-based release agents. Among these, polysiloxane release agents are preferred.

[0049] As other release liner options, substrates with the aforementioned release treatment layer or conventional release paper can be used, without particular limitation. Examples include substrates with a release treatment layer, low-adhesion substrates containing fluorinated polymers, and low-adhesion substrates containing non-polar polymers. Examples of fluorinated polymers in the aforementioned low-adhesion substrates containing fluorinated polymers include: polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PTFE), polyvinylidene fluoride (PVC), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer. Additionally, examples of non-polar polymers include olefin resins (e.g., polyethylene, polypropylene).

[0050] The release liner described above may also have other layers besides the substrate and the release treatment layer described above. Examples of these other layers include an antistatic layer. These other layers may be single-layered or multi-layered.

[0051] There is no particular limitation on the thickness of the aforementioned release liner, for example, it is about 20 μm to about 150 μm.

[0052] The release liner of the present invention can be manufactured by appropriately designing the type or composition of the release agent, antistatic layer, and substrate so that the surface resistivity and dielectric constant are within a specific range. Alternatively, the release liner of the present invention can be selected from commercially available release liners, using release liners with surface resistivity and dielectric constant within the aforementioned range.

[0053] (Adhesive sheet)

[0054] The aforementioned adhesive sheet includes at least an adhesive layer formed on the release-treated surface of the release liner of the present invention. It should be noted that, in this specification, the adhesive layer formed on the release-treated surface of the release liner of the present invention is sometimes referred to as "the adhesive layer of the present invention".

[0055] The aforementioned adhesive sheet is a double-sided adhesive sheet. The adhesive sheet can also be a so-called "substrate-free" adhesive sheet (hereinafter sometimes referred to as a "substrate-free adhesive sheet") that does not have a substrate (substrate layer), or it can be an adhesive sheet with a substrate (hereinafter sometimes referred to as a "substrate-supported adhesive sheet"). Examples of the aforementioned substrate-free adhesive sheets include, for example, double-sided adhesive sheets containing only the adhesive layer of the present invention, and double-sided adhesive sheets containing the adhesive layer of the present invention and adhesive layers other than the adhesive layer of the present invention (sometimes referred to as "other adhesive layers"). On the other hand, examples of substrate-supported adhesive sheets include adhesive sheets having the adhesive layer of the present invention on at least one side of the substrate. Among these, substrate-free adhesive sheets (substrate-free double-sided adhesive sheets) are preferred, and substrate-free double-sided adhesive sheets containing only the adhesive layer of the present invention are more preferred. The adhesive layers on both sides of the aforementioned substrate-supported double-sided adhesive sheet can both be the adhesive layer of the present invention, or one can be the adhesive layer of the present invention and the other can be another adhesive layer. Furthermore, it is preferable that all adhesive layers in the aforementioned adhesive sheet are adhesive layers of the present invention. It should be noted that the "substrate (substrate layer)" mentioned above does not include the release liner that is peeled off when using (adhering) adhesive sheets.

[0056] The dielectric constant of the adhesive layer of the present invention at at least one frequency in the frequency range of 1 kHz to 1000 kHz is preferably 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less. When the dielectric constant is 7.0 or less, even when the adhesive sheet with release liner of the present invention is bonded to the adhered object, the adhered object can more easily detect changes in charge through the release liner. The dielectric constant at the at least one frequency is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, or 3.5 or more.

[0057] The dielectric constant of the adhesive layer of the present invention preferably has a maximum value of 7.0 or less in the frequency range of 1 kHz to 1000 kHz, more preferably 6.0 or less, and even more preferably 5.0 or less. That is, the dielectric constant is preferably within the above range throughout the entire frequency range of 1 kHz to 1000 kHz. When the maximum value is 7.0 or less, it is easier to detect changes in charge over a wide frequency range. The maximum value is, for example, 0.5 or more, but can also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, or 4.5 or more.

[0058] The dielectric constant of the adhesive layer of the present invention at a frequency of 1 kHz is preferably 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less. When the dielectric constant is 7.0 or less, it is easier to detect changes in charge at a frequency of 1 kHz. The dielectric constant is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, or 4.5 or more.

[0059] The dielectric constant of the adhesive layer of the present invention at a frequency of 10 kHz is preferably 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less. When the dielectric constant is 7.0 or less, it is easier to detect changes in charge at a frequency of 10 kHz. The dielectric constant is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, or 4.5 or more.

[0060] The dielectric constant of the adhesive layer of the present invention at a frequency of 100 kHz is preferably 7.0 or less, more preferably 6.0 or less, and even more preferably 5.0 or less. When the dielectric constant is 7.0 or less, it is easier to detect changes in charge at a frequency of 100 kHz. The dielectric constant is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, or 4.0 or more.

[0061] The dielectric constant of the adhesive layer of the present invention at a frequency of 1000 kHz is preferably 6.0 or less, more preferably 5.0 or less, and even more preferably 4.0 or less. When the dielectric constant is 6.0 or less, it is easier to detect changes in charge at a frequency of 1000 kHz. The dielectric constant is, for example, 0.5 or more, but may also be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, or 3.5 or more.

[0062] The dielectric constant of the adhesive layer of the present invention at 1 kHz relative to its dielectric constant at 1000 kHz [1 kHz / 1000 kHz] is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. When the ratio is 3.0 or less, the dielectric constant is stable in the frequency range of 1 kHz to 1000 kHz, and the detection capability of charge change has low frequency dependence, resulting in excellent detection stability. The ratio is preferably 1.0 or more.

[0063] The ratio of the dielectric constant of the adhesive layer of the present invention at a frequency of 10 kHz to the dielectric constant of the non-release treated surface of the release liner of the present invention at a frequency of 10 kHz [adhesive layer / release liner] is preferably 1.5 or more. When the ratio is 1.5 or more, it is easier to detect changes in charge.

[0064] From the viewpoint of ensuring a high degree of flexibility and deformability of the adhesive sheet in low-temperature regions, the shear storage modulus (G') of the adhesive layer of the present invention at -20°C is preferably 200 kPa or less, more preferably 150 kPa or less, and even more preferably 130 kPa or less. From the viewpoint of ensuring the cohesiveness of the adhesive sheet in low-temperature regions, the shear storage modulus (G') at -20°C is preferably 40 kPa or more, more preferably 60 kPa or more, even more preferably 80 kPa or more, and particularly preferably 90 kPa or more. Furthermore, the shear storage modulus (G') of the adhesive sheet at -20°C is preferably within the above-mentioned range. Methods for adjusting the shear storage modulus of the adhesive layer of the present invention include, for example, the selection of the type of base polymer in the adhesive layer of the present invention, the adjustment of its molecular weight, the adjustment of its compounding amount, and the selection of the type of crosslinking agent and the adjustment of its compounding amount.

[0065] From the viewpoint of ensuring flexible deformability that can follow the height of the adhered object when it deforms, the shear storage modulus (G') of the adhesive layer of the present invention at 25°C is preferably 80 kPa or less, more preferably 60 kPa or less, and even more preferably 45 kPa or less. The shear storage modulus (G') at 25°C is preferably 20 kPa or more, more preferably 35 kPa or more, even more preferably 38 kPa or more, and particularly preferably 40 kPa or more. Furthermore, the shear storage modulus (G') of the adhesive sheet at 25°C is preferably within the above range.

[0066] From the viewpoint of ensuring the cohesiveness of the adhesive sheet in high-temperature regions, the shear storage modulus (G') of the adhesive layer of the present invention at 60°C is preferably 15 kPa or more, more preferably 20 kPa or more, further preferably 25 kPa or more, and particularly preferably 28 kPa or more. From the viewpoint of ensuring the high flexibility and deformability of the adhesive sheet in high-temperature regions, the shear storage modulus (G') at 60°C is preferably 60 kPa or less, more preferably 50 kPa or less, and further preferably 40 kPa or less. Furthermore, the shear storage modulus (G') of the adhesive sheet at 60°C is preferably within the above-mentioned range.

[0067] The adhesive layer of the present invention is preferably a solvent-free adhesive layer comprising a photopolymerizable polymer as the base polymer. Such an adhesive layer can be manufactured from a solvent-free adhesive composition. With a solvent-free adhesive composition, the process of manufacturing the adhesive layer of the present invention from this composition does not require a step of removing the solvent by evaporation from the coating film of the composition. Therefore, adhesive sheets having the adhesive layer of the present invention are suitable for reducing environmental impact.

[0068] The adhesive layer of the present invention is preferably a sheet-like pressure-sensitive adhesive (solvent-free adhesive sheet) formed from a solvent-free adhesive composition. Therefore, the adhesive layer (solvent-free adhesive composition) of the present invention preferably contains at least a photopolymer as a base polymer. A photopolymer is a polymer formed by a polymerization method in which polymerizable components are polymerized by irradiation with active energy rays such as ultraviolet light.

[0069] The base polymer (photopolymer) is the adhesive component that exhibits adhesive properties in the adhesive layer of the present invention. The base polymer is preferably an acrylic polymer. The acrylic polymer is a (co)polymer containing a polymerizable component of (meth)acrylate in a proportion of 50% by mass or more. "(meth)acrylate" refers to acrylic acid and / or methacrylic acid.

[0070] The aforementioned alkyl methacrylates are preferably alkyl methacrylates in which the alkyl group has 1 to 20 carbon atoms. Alkyl methacrylates may have straight-chain or branched alkyl groups, or cyclic alkyl groups such as alicyclic alkyl groups. The aforementioned alkyl methacrylates may be used alone or in combination with two or more types.

[0071] Examples of alkyl (meth)acrylates having straight or branched alkyl groups include: methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecanyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate (i.e., lauryl (meth)acrylate), isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, isotetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecanyl (meth)acrylate, octadecyl (meth)acrylate, isostearyl (meth)acrylate, and nonadecanyl (meth)acrylate.

[0072] Examples of alkyl (meth)acrylates having an alicyclic alkyl group include cycloalkyl (meth)acrylates, alkyl (meth)acrylates having a bicyclic aliphatic hydrocarbon ring, and alkyl (meth)acrylates having three or more aliphatic hydrocarbon rings. Examples of cycloalkyl (meth)acrylates include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. Examples of alkyl (meth)acrylates having a bicyclic aliphatic hydrocarbon ring include isobornyl (meth)acrylate. Examples of alkyl (meth)acrylates having three or more aliphatic hydrocarbon rings include tetrahydrodicyclopentadienyl (meth)acrylate, tetrahydrodicyclopentadienyloxyethyl (meth)acrylate, tetrahydrotricyclopentadienyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0073] Alkyl methacrylates are preferably alkyl acrylates having an alkyl group having 3 to 15 carbon atoms, more preferably at least one selected from the group consisting of n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), n-octyl acrylate (NOAA), and lauryl acrylate (LA). Further preferably, BA and NOAA are used together, or 2EHA and LA are used together.

[0074] From the viewpoint of appropriately exhibiting basic properties such as adhesion in the adhesive sheet, the proportion of (meth)acrylate alkyl ester is preferably 55% by mass or more, more preferably 60% by mass or more, and even more preferably 80% by mass or more, relative to the total amount (100% by mass) of the polymerizable components constituting the above-mentioned base polymer. The above proportion is, for example, 99% by mass or less or 96% by mass or less.

[0075] The polymerizable component described above may include copolymerizable monomers capable of copolymerizing with alkyl (meth)acrylates. Examples of such copolymerizable monomers include monomers having polar groups. Examples of such polar monomers include hydroxyl-containing monomers, carboxyl-containing monomers, and monomers having nitrogen-containing rings. These polar monomers facilitate the modification of acrylic polymers, such as introducing crosslinking points and ensuring the cohesiveness of the acrylic polymers. The aforementioned copolymerizable monomers may be used alone or in combination of two or more.

[0076] Examples of hydroxyl-containing monomers include: 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylaurate (meth)acrylate. The hydroxyl-containing monomer is preferably at least one selected from the group consisting of 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA).

[0077] From the viewpoint of introducing a crosslinking structure into the acrylic polymer and ensuring the cohesiveness of the adhesive layer of the present invention, the proportion of hydroxyl-containing monomers is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to the total amount (100% by mass) of the polymerizable components constituting the above-mentioned base polymer. From the viewpoint of adjusting the polarity of the acrylic polymer (which relates to the compatibility of various additive components in the adhesive layer of the present invention with the acrylic polymer), the above-mentioned proportion is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less.

[0078] Examples of carboxyl-containing monomers include: acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0079] From the viewpoint of introducing a cross-linking structure into the acrylic polymer, ensuring the cohesiveness of the adhesive layer of the present invention, and ensuring the adhesion of the adhesive layer of the present invention to the adherend, the proportion of carboxyl monomers is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, relative to the total amount (100% by mass) of the polymerizable components constituting the above-mentioned base polymer. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend due to acid, the above-mentioned proportion is preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.5% by mass or less.

[0080] Examples of monomers having a nitrogen-containing ring include: N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazolium, and N-vinylpyrrolidone. Zyrazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3- Azine-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisothione Zyrazoles, N-vinylthiazoles, and N-vinylisothiazoles. Monomers having a nitrogen-containing ring are preferably N-vinyl-2-pyrrolidone (NVP).

[0081] From the viewpoint of ensuring the cohesiveness of the adhesive layer of the present invention and the adhesion of the adhesive layer of the present invention to the adherend, the proportion of monomers having nitrogen-containing atomic rings is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more, relative to the total amount (100% by mass) of the polymerizable components constituting the above-mentioned base polymer. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (which relates to the compatibility of various additive components in the adhesive layer of the present invention with the acrylic polymer), the above-mentioned proportion is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0082] The polymerizable components described above may contain other copolymerizable monomers. Examples of such other copolymerizable monomers include: acid anhydride monomers, sulfonic acid monomers, phosphate monomers, epoxy monomers, cyano monomers, alkoxy monomers, and aromatic vinyl compounds. These other copolymerizable monomers may be used alone or in combination of two or more.

[0083] The aforementioned basic polymer can be formed, for example, by photopolymerization of the polymerizable components. Examples of photopolymerization include photopolymerization performed by ultraviolet irradiation. A photopolymerization initiator is used as the polymerization initiator. The aforementioned photopolymerization initiator can be used alone or in combination of two or more.

[0084] Examples of photopolymerization initiators include: free radical photopolymerization initiators, cationic photopolymerization initiators, and anionic photopolymerization initiators.

[0085] Examples of free radical photopolymerization initiators include: acylphosphine oxide photopolymerization initiators, benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-keto alcohol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzoyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, and thioxanone photopolymerization initiators.

[0086] Examples of acylphosphine oxide photopolymerization initiators include: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Examples of benzoin ether photopolymerization initiators include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-dimethoxy-1,2-diphenylethane-1-one. Examples of acetophenone photopolymerization initiators include: 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenyl ketone, 4-phenoxydichloroacetophenone, and 4-(tert-butyl)dichloroacetophenone. Examples of α-keto alcohol polymerization initiators include 2-methyl-2-hydroxyphenylacetone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropane-1-one. Examples of aromatic sulfonyl chloride photopolymerization initiators include 2-naphthalenesulfonyl chloride. Examples of photoactive oxime photopolymerization initiators include 1-phenyl-1,1-propanedione-2-(O-ethoxycarbonyl)-oxime. Examples of benzoin photopolymerization initiators include benzoin. Examples of benzoyl photopolymerization initiators include benzoyl. Examples of benzophenone photopolymerization initiators include benzoyl. Examples of benzophenone photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, and poly(vinylbenzophenone). Examples of ketal photopolymerization initiators include benzoyl dimethyl ketal. Examples of photopolymerization initiators for thioxanthone include: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0087] The aforementioned photopolymerization initiator is preferably at least one selected from the group consisting of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 1-hydroxycyclohexylphenyl ketone.

[0088] Relative to the total amount of polymerizable components (100 parts by mass), the amount of the aforementioned photopolymerization initiator (the total amount of multiple photopolymerization initiators when multiple photopolymerization initiators are used) is, for example, 0.01 parts by mass or more, preferably 0.03 parts by mass or more, more preferably 0.05 parts by mass or more, and for example, 1 part by mass or less, preferably 0.5 parts by mass or less, more preferably 0.3 parts by mass or less, and even more preferably 0.2 parts by mass or less.

[0089] The aforementioned base polymer preferably has a crosslinked structure. Examples of methods for introducing a crosslinked structure into the base polymer include the following first and second methods. In the first method, a base polymer having functional groups capable of reacting with a crosslinking agent and a crosslinking agent are incorporated into an adhesive composition, and the base polymer and the crosslinking agent react in the adhesive layer. In the second method, a multifunctional compound (crosslinking agent) such as a multifunctional monomer is included in the polymerizable component forming the base polymer, and a base polymer with a branched structure (crosslinked structure) introduced into the polymer chain is formed by polymerization of this polymerizable component. These methods can be used in combination.

[0090] Examples of crosslinking agents used in the first method described above include compounds that react with functional groups (hydroxyl and carboxyl groups, etc.) contained in the base polymer. Examples of such crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, and epoxy crosslinking agents. Crosslinking agents include aziridine, carbodiimide, and metal chelate crosslinking agents. Crosslinking agents can be used alone or in combination of two or more.

[0091] From the viewpoint of ensuring the cohesiveness of the adhesive layer of the present invention, the amount of crosslinking agent in the first method is preferably 0.01 parts by mass or more, more preferably 0.02 parts by mass or more, and even more preferably 0.05 parts by mass or more, and preferably 3 parts by mass or less, more preferably 1 part by mass or less, and even more preferably 0.5 parts by mass or less, relative to 100 parts by mass of the base polymer.

[0092] In the second method described above, monofunctional monomers and polyfunctional compounds, such as polyfunctional monomers used to introduce crosslinking structures, can be polymerized in a single step or in multiple steps. In the multi-step polymerization method, the monofunctional monomer is first polymerized (prepolymerization), thereby preparing a prepolymer composition containing a portion of the polymer (a mixture of low-degree polymers and unreacted monomers). Next, a polyfunctional compound is added to the prepolymer composition as a crosslinking agent, and then the portion of the polymer is polymerized with the polyfunctional compound (main polymerization).

[0093] Examples of multifunctional compounds include multifunctional monomers and multifunctional oligomers containing two or more olefinic unsaturated double bonds in one moiety. Examples of multifunctional monomers include multifunctional (meth)acrylates.

[0094] Examples of polyfunctional (meth)acrylates include: difunctional (meth)acrylates, trifunctional (meth)acrylates, and polyfunctional (meth)acrylates with more than four functions.

[0095] Examples of bifunctional (meth)acrylates include: ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, glycerol dimethacrylate, ethoxylated bisphenol A dimethacrylate (BPAEODE), and neopentyl glycol dimethacrylate.

[0096] Examples of trifunctional (meth)acrylates include: trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tri(acryloyloxyethyl)isocyanurate.

[0097] Examples of polyfunctional (meth)acrylates with more than four functions include: di(trimethylolpropane)tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0098] Examples of multifunctional oligomers include: urethane (meth)acrylate oligomers, polyester (meth)acrylate oligomers, polyether (meth)acrylate oligomers, polyol (meth)acrylate oligomers, epoxy (meth)acrylate oligomers, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate.

[0099] The multifunctional compound used as the crosslinking agent in the second method can be used alone or in combination with two or more. Preferably, at least one compound selected from the group consisting of 1,6-hexanediol diacrylate (HDDA) and dipentaerythritol hexaacrylate (DPHA) is used.

[0100] When using a multifunctional monomer as the multifunctional compound, from the viewpoint of ensuring the cohesiveness of the adhesive layer of the present invention, the amount of the multifunctional monomer is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, relative to 100 parts by mass of the monofunctional monomer. From the viewpoint of ensuring the flexibility and deformability of the adhesive layer of the present invention, the amount of the multifunctional monomer is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of the monofunctional monomer.

[0101] When using a multifunctional oligomer as the multifunctional compound, from the viewpoint of ensuring the cohesiveness of the adhesive layer of the present invention, the amount of the multifunctional oligomer in the monomer component is preferably 0.2 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 0.7 parts by mass or more, relative to 100 parts by mass of the monofunctional monomer. From the viewpoint of ensuring the flexibility and deformability of the adhesive layer of the present invention, the amount of the multifunctional oligomer is preferably 8 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3 parts by mass or less, relative to 100 parts by mass of the monofunctional monomer.

[0102] In polymerization, chain transfer agents can be used for purposes such as adjusting molecular weight. Examples of chain transfer agents include α-thioglycerol, dodecyl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolic acid, 2,3-dimercapto-1-propanol, and α-methylstyrene dimers. Chain transfer agents can be used alone or in combination of two or more.

[0103] From the viewpoint of ensuring the cohesiveness of the adhesive layer of the present invention, the weight-average molecular weight of the base polymer is preferably 100,000 or more, more preferably 300,000 or more, and even more preferably 500,000 or more. The weight-average molecular weight of the base polymer is determined by gel permeation chromatography (GPC) and calculated by conversion to polystyrene.

[0104] The glass transition temperature (Tg) of the base polymer is preferably below 0°C, more preferably below -10°C, and even more preferably below -20°C. For example, the glass transition temperature is above -80°C.

[0105] The glass transition temperature (Tg) of a basic polymer can be calculated using the theoretical value based on the Fox formula below. The Fox formula is the relationship between the glass transition temperature (Tg) of the polymer and the glass transition temperature (Tgi) of the homopolymer of the monomers constituting the polymer. In the Fox formula below, Tg represents the glass transition temperature (°C) of the polymer, Wi represents the weight fraction of monomer i constituting the polymer, and Tgi represents the glass transition temperature (°C) of the homopolymer formed from monomer i. The glass transition temperature of the homopolymer can be obtained from literature. For example, the glass transition temperatures of various homopolymers listed in *Polymer Handbook* (4th edition, John Wiley & Sons, Inc., 1999) can be used. Alternatively, the glass transition temperature of the homopolymer of the monomers can also be calculated using the method specifically described in Japanese Patent Application Publication No. 2007-51271.

[0106] Fox formula 1 / (273+Tg)=Σ[Wi / (273+Tgi)]

[0107] The adhesive layer of the present invention may contain a silane coupling agent. The content of the silane coupling agent relative to 100 parts by weight of the base polymer is preferably 0.1 parts by weight or more, more preferably 0.2 parts by weight or more. The content is preferably 5 parts by weight or less, more preferably 3 parts by weight or less.

[0108] The adhesive layer of the present invention may contain other components besides those described above, without impairing the effects of the present invention. Examples of these other components include: curing agents, curing catalysts, crosslinking accelerators, tackifying resins (rosin derivatives, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc.), anti-aging agents, fillers (metal powders, organic fillers, inorganic fillers, etc.), colorants (pigments or dyes, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, rust inhibitors, granules, foils, flame retardants, ion traps, etc. Only one of the above-mentioned components may be used, or two or more may be used.

[0109] From the viewpoint of ensuring sufficient adhesion to the adhered objects, the thickness of the adhesive layer of the present invention is preferably 5 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. From the viewpoint of making the device using the optical adhesive sheet with release liner of the present invention thinner, the thickness of the adhesive layer of the present invention is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less, even more preferably 70 μm or less, and particularly preferably 50 μm or less.

[0110] The total light transmittance of the adhesive layer of the present invention is preferably 60% or more, more preferably 80% or more, and even more preferably 85% or more. The aforementioned total light transmittance is, for example, 100% or less. The aforementioned total light transmittance can be measured according to JIS K7375 (2008).

[0111] The optical adhesive sheet with release liner of the present invention can be manufactured, for example, as follows.

[0112] First, prepare two release liner pads comprising the release liner pad of the present invention. The release liner pad can be manufactured, for example, by forming a release treatment layer on one side of a substrate. The release treatment layer can be formed by peeling the surface of the substrate with a release treatment agent. Alternatively, commercially available release liner pads can also be used.

[0113] Next, the adhesive composition is applied to a release liner to form a coating film, which is then cured. Examples of methods for applying the adhesive composition include roller coating, licking coating, gravure coating, reverse coating, brush coating, spraying, dip roller coating, doctor blade coating, knife coating, air knife coating, curtain coating, die lip coating, and die-cutting.

[0114] The adhesive composition described above is preferably solvent-free. That is, the adhesive composition preferably does not contain or substantially does not contain organic solvents. There are no particular limitations on the organic solvents used as solvents, such as hydrocarbon solvents like cyclohexane, hexane, and heptane; aromatic solvents like toluene and xylene; ester solvents like ethyl acetate and methyl acetate; ketone solvents like acetone and methyl ethyl ketone; and alcohol solvents like methanol, ethanol, butanol, and isopropanol. It should be noted that the organic solvents described above can be mixtures containing two or more organic solvents.

[0115] In the above-mentioned adhesive composition, "substantially free of organic solvents" means that, except in cases where organic solvents are unavoidably mixed in, no organic solvents are actively incorporated. Specifically, the proportion of organic solvents in the adhesive composition relative to the total amount of the adhesive composition (total mass, 100% by mass) is said to be substantially free of organic solvents (1.0% by mass or less, preferably 0.5% by mass or less, more preferably 0.2% by mass or less).

[0116] The above-described adhesive composition can be prepared by known or conventional methods. As an active energy ray curable type, the above-described adhesive composition can be prepared, for example, by adding additives as needed to a mixture of polymerizable components or a portion thereof.

[0117] Next, another release liner is attached to the coating on one release liner. Then, the coating is cured as needed. The curing temperature is, for example, 20°C to 160°C. The curing time is, for example, 1 minute to 21 days. Alternatively, to cure the coating, it can be irradiated with light, such as active energy rays. Examples of light sources for irradiation include ultraviolet LED lamps, high-pressure mercury lamps, and metal halide lamps.

[0118] Through the above operations, the optical adhesive sheet with release liner of the present invention can be manufactured.

[0119] (use)

[0120] The optical adhesive sheet with release liner of the present invention is used for optical applications, namely, for bonding to optical components. More specifically, it is used, for example, for bonding optical components (optical component bonding) and for manufacturing articles using the aforementioned optical components (optical articles). By using the optical adhesive sheet with release liner of the present invention for optical applications, excellent reliability is achieved.

[0121] The optical adhesive sheet with a release liner of the present invention is used, for example, in optical components such as electrical and electronic equipment, to mount (set) various components or parts to designated locations (e.g., housing, front panel, window portion, etc.). Furthermore, "electrical and electronic equipment" refers to equipment that belongs to at least one of electrical equipment or electronic equipment. Examples of such electrical and electronic equipment include, for example, image display devices such as liquid crystal displays, organic / inorganic electroluminescent displays, and plasma displays, as well as portable electronic devices. Examples of such image display devices include, for example, image display devices among the aforementioned portable electronic devices, vehicle-mounted displays, and digital signage (electronic billboards / electronic bulletin boards). It should be noted that the aforementioned image display devices can be of a so-called "rigid" or "flexible" form (structure), and can also be of a form (structure) capable of being bent or folded, such as a so-called "foldable" or "rollable" form.

[0122] Examples of portable electronic devices mentioned above include: mobile phones, smartphones, tablet PCs, laptop PCs, various wearable devices (e.g., wrist-worn devices like watches, modular devices worn on the body with clips or straps, eyewear (including monocular, binocular, and headband types), clothing devices worn as accessories on shirts, socks, hats, etc., and ear-worn devices like headphones), digital cameras, digital camcorders, audio equipment (portable music players, voice recorders, etc.), computers (desktop calculators, etc.), portable gaming devices, electronic dictionaries, electronic notebooks, e-books, in-vehicle information devices, portable radios, portable televisions, portable printers, portable scanners, portable modems, etc. It should be noted that in this specification, "portable" means not merely that it can be carried, but rather that it possesses a level of portability that an individual (a standard adult) can relatively easily handle.

[0123] The optical adhesive sheet with release liner of the present invention (i.e., the adhesive sheet described above) is preferably used for bonding to an optical component having a component capable of detecting changes in charge. Examples of components capable of detecting such changes in charge include a panel equipped with a touch sensor (touch panel). Specifically, the application of the optical adhesive sheet with release liner of the present invention is preferably for bonding a touch panel and an image display device between the touch panel and the image display device. The optical adhesive sheet with release liner of the present invention is particularly preferably used for bonding a touch panel to glass (e.g., a glass plate, chemically strengthened glass, a glass lens, etc.).

[0124] The adhesive layer of the present invention is particularly preferably directly laminated with the aforementioned touch sensor. Alternatively, the adhesive layer of the present invention can be directly laminated to the image display device, or it can be laminated through other layers such as a polarizing film. The adhesive layer of the present invention is less likely to amplify noise, thus making it difficult for noise emitted from the image display device to be transmitted to the touch sensor.

[0125] [Optical components with adhesive layer]

[0126] By attaching the aforementioned adhesive sheet to an optical component, an optical component with an adhesive layer, comprising an optical component and an optical adhesive sheet with a release liner attached to at least one side of the optical component, can be obtained. On the adhesive sheet of the aforementioned optical component with an adhesive layer, a release liner of the present invention is provided on the adhesive surface until use, and this release liner is peeled off when attached to other adhered objects.

[0127] The adhesive layer of the above-mentioned optical component can be attached to an optical component (touch sensor film) having metal wiring such as a metal mesh film or a silver nanowire film. In this case, it is preferable to attach the adhesive layer of the present invention to the side of the touch sensor film having the aforementioned metal wiring.

[0128] [Optical laminate]

[0129] By placing the adhesive sheet between the touch sensor and the image display device, an optical laminate (the optical laminate of the present invention) can be obtained, which sequentially includes a touch sensor, the adhesive sheet, and the image display device. The optical laminate may include the touch sensor and the adhesive sheet as a single layer, or it may include multiple layers of the touch sensor and the adhesive sheet. When multiple touch sensors are included, it is preferable to stack each touch sensor with the adhesive sheet in between.

[0130] Examples of the aforementioned image display devices include the display devices described above. The aforementioned touch sensor is a capacitive touch sensor, such as a transparent conductive film on a glass plate or a transparent plastic film (particularly PET film, polycarbonate film, or cyclic olefin polymer film) with a transparent conductive layer. The aforementioned adhesive sheet is preferably bonded in contact with the aforementioned transparent conductive layer.

[0131] Examples of transparent conductive layers include thin films of ITO (indium tin oxide), ZnO, SnO, and CTO (cadmium tin oxide). Furthermore, transparent conductive layers can be formed from silver, copper, CNTs (carbon nanotubes), etc. Additionally, the transparent conductive layer can also be formed from Ag nanowires, Ag / Cu, or other metal mesh sensors. Furthermore, the touch sensor may also have lead-wound wiring formed from thin copper or silver paste at its ends.

[0132] The aforementioned optical laminate may include a cover member. This cover member is disposed on the surface of the touch sensor opposite to the side with the image display device, protecting the touch sensor and image display device within the optical laminate. Examples of the cover member include cover glass and plastic cover plates. The cover member may also be attached to layers of the optical laminate, such as the touch sensor, via the aforementioned adhesive sheet. Furthermore, the optical laminate may include a polarizing film on the surface of the image display device (the surface with the touch sensor).

[0133] The aforementioned optical laminate may include a noise reduction layer (such as a noise reduction film). From the viewpoint of suppressing the amplification of noise emitted by the image display device, the noise reduction layer is preferably disposed between the touch sensor and the image display device. The noise reduction layer is bonded to the touch sensor and to the image display device respectively via an adhesive layer. The noise reduction layer may be a single layer or multiple layers. In the case of multiple noise reduction layers, the composition and thickness of the multiple noise reduction layers may be the same or different layers.

[0134] The embodiments described above are for the purpose of making the present invention easier to understand, and are not intended to limit the present invention.

[0135] Example

[0136] The following examples illustrate the present invention in more detail, but the present invention is not limited to these examples. It should be noted that the proportions (parts by mass) refer entirely to the proportions of each of the stated ingredients.

[0137] [Example 1]

[0138] (Preparation of the prepolymer composition)

[0139] In a flask, 0.05 parts by weight of a first photopolymerization initiator (trade name "Omnirad 184", 1-hydroxycyclohexylphenyl ketone, manufactured by IGM Resins) and 0.05 parts by weight of a second photopolymerization initiator (trade name "Omnirad 819", bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM Resins) and 0.05 parts by weight of a second photopolymerization initiator (trade name "Omnirad 819", bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM Resins) were added to a monomer mixture comprising 70 parts by weight of n-octyl acrylate (NOAA), 20 parts by weight of n-butyl acrylate (BA), 8 parts by weight of 4-hydroxybutyl acrylate (4HBA), and 2 parts by weight of N-vinyl-2-pyrrolidone (NVP). The mixture was then irradiated with ultraviolet light under a nitrogen atmosphere, thereby polymerizing a portion of the monomer components in the mixture to obtain a first prepolymer composition. A black light lamp was used for ultraviolet irradiation. The irradiation continued until the viscosity of the composition reached approximately 20 Pa·s. The viscosity was measured using a Type B viscometer under the conditions of rotor No. 5, rotor speed of 10 rpm, and temperature of 30°C (the viscosity described below is also the same). The resulting prepolymer composition is a partial polymer containing photopolymer and unpolymerized monomer components (residual monomers).

[0140] (Preparation of the adhesive composition)

[0141] An adhesive composition was prepared by mixing 100 parts by weight of the first prepolymer composition, 1.5 parts by weight of the oligomer described below, and 0.5 parts by weight of the silane coupling agent (brand name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.).

[0142] (Preparation of oligomers)

[0143] First, in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet, a mixture containing 60 parts by mass of tetrahydrodicyclopentadienyl methacrylate (DCPMA), 40 parts by mass of methyl methacrylate (MMA), 3.5 parts by mass of α-thioglycerol as a chain transfer agent, and 100 parts by mass of toluene as a solvent was stirred at 70°C for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) as a thermal polymerization initiator was added to the mixture to prepare a reaction solution. The reaction was carried out at 70°C for 1 hour under a nitrogen atmosphere, followed by a reaction at 80°C for 2 hours (polymerization reaction). Then, the reaction solution was heated to 130°C to volatilize and remove the toluene, chain transfer agent, and unreacted monomers. This yielded an acrylic oligomer (solid) as a hydrophobic oligomer without polar groups. The weight-average molecular weight of this acrylic oligomer was 5100.

[0144] (Formation of the adhesive layer)

[0145] A coating film was formed by applying the aforementioned adhesive composition to the release-treated surface of a first release liner (trade name "RF12ASD", manufactured by SK Chemicals) having a release-treated surface on one side, which was treated with a polysiloxane-based release agent. Next, the release-treated surface of a second release liner (trade name "Diafoil MRE#75", 75 μm thick, manufactured by Mitsubishi Chemical Corporation) having a release-treated surface on one side was bonded to the coating film on the first release liner. Then, the coating film between the release liners was irradiated with ultraviolet light to photocur the coating film, thereby forming an adhesive layer (50 μm thick). During ultraviolet irradiation, a black light lamp was used as the irradiation source, and the irradiation intensity was set to 5 mW / cm². 2 In comparison, the first release liner is a heavy release liner, and the second release liner is a light release liner.

[0146] Through the above operations, an optical adhesive sheet with a double-sided release liner as described in Example 1 was produced.

[0147] [Example 2]

[0148] As a heavy-duty release liner, a release liner (trade name "RF17ASD", manufactured by SK Chemicals) with a release-treated surface on one side obtained by treating with a polysiloxane-based release agent was used instead of the first release liner. Otherwise, the same procedure as in Example 1 was followed to produce an optical adhesive sheet of Example 2 with release liners on both sides.

[0149] [Example 3]

[0150] As a heavy-duty release liner, a release liner (trade name "RF32ASD", manufactured by SK Chemicals) with a release-treated surface on one side obtained by treating with a polysiloxane-based release agent was used instead of the first release liner. Otherwise, the same procedure as in Example 1 was followed to produce an optical adhesive sheet of Example 3 with release liners on both sides.

[0151] [Comparative Example 1]

[0152] As a heavy-duty release liner, a release liner with a release-treated surface obtained by treating one side with a polysiloxane-based release agent (the surface resistance value and dielectric constant of the release liner are shown in Table 1) was used instead of the first release liner. Otherwise, the same procedure as in Example 1 was followed to produce an optical adhesive sheet of Comparative Example 1 with release liners on both sides.

[0153] [Comparative Example 2]

[0154] As a heavy-duty release liner, a release liner (trade name "Diafoil MRV#6", manufactured by Mitsubishi Chemical Corporation) with a release-treated surface on one side obtained by treating with a polysiloxane-based release agent was used instead of the first release liner. Otherwise, the same procedure as in Example 1 was followed to produce an optical adhesive sheet with release liners on both sides of Comparative Example 2.

[0155] <Evaluation>

[0156] The optical adhesive sheets of the embodiments and comparative examples were evaluated as follows. The evaluation results are shown in the table.

[0157] (1) Dielectric constant (relative permittivity)

[0158] The dielectric constants of the release liner and adhesive layer used in the examples and comparative examples were measured as follows. The dielectric constant of the release liner was measured using the non-release treated surface before the adhesive layer was formed. For the dielectric constant of the adhesive layer, the adhesive surface exposed after peeling off the second release liner from the obtained optical adhesive sheet was measured.

[0159] A test sample was prepared by sandwiching the copper foil between the copper foil and the electrode. Next, using the "E4980A" manufactured by KEYSIGHT Corporation, according to JIS K6911, the dielectric constant of the release liner was measured in the range of 100Hz to 1000kHz, and the dielectric constant of the adhesive layer was measured in the range of 1kHz to 1000kHz under the following conditions.

[0160] [Conditions for determining dielectric constant]

[0161] Electrode composition: Aluminum plate with a diameter of 12.1 mm and a thickness of 0.5 mm.

[0162] Counter electrode: 3oz copper plate

[0163] Measurement environment: Temperature 25℃, relative humidity 50%

[0164] (2) Surface resistivity

[0165] For the heavy-duty peeling pads used in the examples and comparative examples, the surface resistance was measured using a resistivity meter (TREK "Model 152-1") with a probe (TREK "Model 152P-2P") in contact with the non-peeled surface of the heavy-duty peeling pad under conditions of 23°C and 50% relative humidity, with an applied voltage of 100V and a voltage application time of 3 seconds.

[0166] (3) Shear storage modulus

[0167] A necessary number of test samples were prepared for each optical adhesive sheet. Specifically, firstly, multiple small pieces of adhesive sheet cut from the optical adhesive sheet were glued together to create a sample sheet with a thickness of approximately 1.0 mm. Next, this sample sheet was punched to obtain cylindrical particles (7.9 mm in diameter) that would serve as the test samples. Then, dynamic viscoelasticity measurements were performed on the test samples using a dynamic viscoelasticity measuring device (product name "Discovery Hybrid Reometeter-2 (DHR-2)", manufactured by TA Instruments, after being fixed to a clamp with a parallel plate of 7.9 mm in diameter. In this measurement, the measurement mode was set to shear mode, the measurement temperature range was set to -50°C to 150°C, the heating rate was set to 5°C / min, and the frequency was set to 1 Hz. The shear storage modulus at specified temperatures (-20°C, 25°C, and 60°C) was read from the measurement results.

[0168] (4) Antistatic properties

[0169] The case where a measured value is obtained in the above surface resistance measurement is evaluated as "○", and the case where the value is greater than the measurement limit but no measured value is obtained is evaluated as "×", thereby evaluating the antistatic property.

[0170] (5) Low-temperature bending properties

[0171] A light release liner was peeled off from the optical adhesive sheet, and the exposed surface was subjected to plasma treatment. Simultaneously, both sides (first and second sides) of a 51 μm thick polarizing film were also plasma treated. Additionally, the surfaces of an 80 μm thick transparent polyimide film and a 125 μm thick polyethylene terephthalate (PET) film were plasma treated. In each plasma treatment, a plasma irradiation device (trade name "AP-TO5," manufactured by Sekisui Chemicals Co., Ltd.) was used, with the voltage set to 160V, the frequency set to 10kHz, and the processing speed set to 5000 mm / min. Then, the exposed adhesive surface of the adhesive sheet was bonded to the first side of the polarizing film. During this bonding process, at 23°C, the adhesive sheet with the heavy release liner was pressed against the polarizing film by a 2 kg roller making one reciprocating motion. Next, a release liner is peeled off from the adhesive sheet with the polarizing film, and then the aforementioned transparent polyimide film is bonded to the exposed surface of the adhesive sheet. Next, the aforementioned PET film is bonded to the second side of the polarizing film using a thin, strong adhesive sheet with a thickness of 15 μm. During this bonding process, the polarizing film and the PET film are pressed together at 23°C by pressing a 2 kg roller back and forth once. This results in a laminated film with a stacked structure consisting of a PET film (125 μm thick), a thin, strong adhesive sheet (15 μm thick), a polarizing film (51 μm thick), an adhesive sheet (50 μm thick), and a transparent polyimide film (80 μm thick).

[0172] Next, evaluation test pieces were cut from the laminated film prepared by the above operation. Specifically, rectangular test pieces of 35 mm × 100 mm were cut from the laminated film such that the absorption axis direction of the polarizing film in the cut test pieces is parallel to the long side direction. Then, the test pieces were subjected to autoclaving treatment at 35 °C and 0.50 MPa for 15 minutes.

[0173] Next, a bending test was performed on the test piece using a planar unloaded U-shaped expansion and contraction testing machine (manufactured by Yuasa Systems Machinery Co., Ltd.). In this test, as... Figure 2 As shown, bending clamps 201 and 202 of the testing machine are respectively installed at both ends of the long side of the test piece 100, thereby fixing the test piece 100 to the testing machine. The bending clamps 201 and 202 are each maintained within a 20mm range from the end edge of the test piece 100. The central 60mm region of the test piece 100 along its long side is not fixed by the bending clamps 201 and 202. Furthermore, in this experiment, the test piece 100 is bent in an inward-facing configuration on the PET film side within a constant temperature bath at -20°C. Figure 3 ) and non-curved morphology ( Figure 2The test piece 100 was repeatedly deformed (bent) at a bending speed of 60 rpm for 200,000 cycles. Specifically, the bending pattern in this experiment was one where the axial direction of the bending torque acting on the test piece 100 was orthogonal to the absorption axis of the polarizing film. In this bending pattern, the bending radius of the test piece 100 was set to 1.3 mm, and the bending angle was set to 180°. Then, the bent portion 100a of the test piece 100 was observed. Regarding the adhesion of the adhesive sheet to the adhered object in the bending test, cases where no peeling occurred between the adhesive sheet and its adhered object (transparent polyimide film, polarizing film) were evaluated as "○", and cases where peeling occurred were evaluated as "×". The evaluation results are shown in Table 1.

[0174] (6) Charge detection capability

[0175] A light release liner was peeled off from the optical adhesive sheet, and the exposed surface was then bonded to a display bearing the trade name "Galaxy Fold 5" (manufactured by Samsung Electronics) to create an evaluation laminate. The sensitivity was then confirmed by moving the laminate back and forth at a certain speed while pressing the heavy release liner on the surface of the optical adhesive sheet with a finger. Cases where the sensor responded were rated as "○", and cases where the sensor did not respond were rated as "×". The evaluation results are shown in Table 1.

[0176]

[0177] As shown in Table 1, the optical adhesive sheet with release liner in the embodiment exhibits excellent charge detection capability and excellent low-temperature flexibility, and is evaluated as having excellent bending stability. In contrast, the case where the dielectric constant of the non-released surface is greater than 7.5 is evaluated as having poor charge detection capability through the release liner.

[0178] The following describes variations of the invention disclosed herein.

[0179] [Appendix 1] An optical adhesive sheet with a release liner, wherein the optical adhesive sheet with a release liner comprises: a release liner having a release-treated surface and a non-release-treated surface; and an adhesive layer formed on the release-treated surface of the release liner, wherein the surface resistivity of the non-release-treated surface of the release liner is 10 Ω. 12 The dielectric constant of the non-peeled surface of the release liner is 7.5 or less at at least one frequency in the frequency range of 100Hz to 10kHz.

[0180] [Note 2] In the optical adhesive sheet with release liner according to Note 1, the non-release treated surface of the release liner has a maximum dielectric constant of 7.5 or less in the frequency range of 100 Hz to 10 kHz.

[0181] [Note 3] An optical adhesive sheet with a release liner according to Note 1 or 2, wherein the non-release treated surface of the release liner has a dielectric constant of 1.5 or higher at a frequency of 1000 kHz.

[0182] [Note 4] An optical adhesive sheet with a release liner according to any one of Notes 1 to 3, wherein the ratio of the dielectric constant of the adhesive layer at a frequency of 10 kHz to the dielectric constant of the non-release treated surface of the release liner at a frequency of 10 kHz [adhesive layer / release liner] is 1.5 or more.

[0183] [Appendix 5] An optical adhesive sheet with a release liner according to any one of Appendices 1 to 4, wherein on the adhesive surface of the adhesive layer opposite to the adhesive surface having the release liner, there is a release liner with a smaller peel force on the adhesive surface of the adhesive layer than the release liner.

[0184] [Appendix 6] An optical adhesive sheet with a release liner according to any one of Appendices 1 to 5, wherein the adhesive sheet of the optical adhesive sheet with a release liner is used for bonding a touch panel to glass.

Claims

1. An optical adhesive sheet with a release liner, wherein, The optical adhesive sheet with a release liner comprises: a release liner having a release-treated surface and a non-release-treated surface; and an adhesive layer formed on the release-treated surface of the release liner. The surface resistivity of the non-peeled surface of the peeling liner is 10. 12 Below Ω, The non-peeled surface of the peeling pad has a dielectric constant of 7.5 or less at at least one frequency in the frequency range of 100 Hz to 10 kHz.

2. The optical adhesive sheet with a release liner according to claim 1, wherein, The non-peeled surface of the release liner has a maximum dielectric constant of 7.5 or less in the frequency range of 100 Hz to 10 kHz.

3. The optical adhesive sheet with a release liner according to claim 1 or 2, wherein, The non-stripped surface of the stripping liner has a dielectric constant of 1.5 or higher at a frequency of 1000 kHz.

4. The optical adhesive sheet with a release liner according to claim 1 or 2, wherein, The ratio of the dielectric constant of the adhesive layer at 10 kHz to the dielectric constant of the non-removable surface of the release liner at 10 kHz [adhesive layer / release liner] is 1.5 or higher.

5. The optical adhesive sheet with a release liner according to claim 1 or 2, wherein, On the adhesive surface of the adhesive layer opposite to the adhesive surface having the release liner, there is a release liner with a smaller peel force on the adhesive surface of the adhesive layer than the release liner.

6. The optical adhesive sheet with a release liner according to claim 1 or 2, wherein, The adhesive sheet with release liner is used for bonding touch panels to glass.

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