Optical adhesive sheet with release liner

Abstract

The present invention provides an adhesive sheet with a release liner that allows for the detection of electric charge via the release liner when the adhesive sheet is attached to a substrate equipped with an optical element that senses electric charge. [Solution] The optical adhesive sheet 10 with a release liner comprises a release liner 2 having a release surface 2a and a non-release surface 2b, and an adhesive layer 1 formed on the release surface 2a of the release liner 2. The surface resistance of the non-release surface 2b of the release liner 2 is 10 12 The dielectric constant is less than or equal to Ω, and the dielectric constant of the non-peeling surface 2b of the peeling liner 2 at at least one frequency between 100 Hz and 10 kHz is 7.5 or less.

Description

Technical Field

[0001] The present invention relates to an optical adhesive sheet with a release liner.

Background Art

[0002] In recent years, in various fields, image display devices such as liquid crystal displays (LCDs) and organic EL displays (OLEDs), and touch panels incorporating touch sensors in these image display devices have been widely used. Such image display devices and touch panels have a configuration in which various optical members such as a polarizing film, a retardation film, an optical compensation film, a touch sensor film, and a cover film are laminated on an image display panel. An adhesive sheet having an adhesive layer is used for the purpose of bonding these optical members. For example, an optical adhesive sheet is used for bonding various optical members in an image display device (see, for example, Patent Documents 1 to 3).

[0003] On the other hand, for example, for smartphones and tablet terminals, development of a foldable display panel that can be repeatedly bent is in progress. A foldable display panel is specifically capable of being repeatedly deformed between a bent shape and a flat non-bent shape. In such a foldable display panel, each element in the laminated structure is manufactured to be repeatedly foldable, and a thin optical adhesive sheet is used for joining between such elements. An optical adhesive sheet for a flexible device such as a foldable display panel is described in, for example, Patent Document 4 below.

Prior Art Documents

Patent Documents

[0004] [[ID=2】] $$END]]

Patent Document 1

Patent Document 2

Patent Document 3

[0005] In the manufacturing process of the optical components described above, the optical adhesive sheet may be attached to the optical component with a release liner attached. If the optical component includes an electric charge sensing component such as a touch sensor, it may be necessary to detect the electric charge through the release liner side while the adhesive sheet with the release liner is attached.

[0006] The present invention aims to solve these problems, and its objective is to provide an adhesive sheet with a release liner that can detect electric charge through the release liner when the adhesive sheet is attached to a substrate equipped with an optical element that senses electric charge. [Means for solving the problem]

[0007] The present invention comprises a peelable liner having a peelable surface and a non-peelable surface, and an adhesive layer formed on the peelable surface of the peelable liner. The surface resistance of the non-peeling treated surface of the above peeling liner is 10 12 It is less than or equal to Ω, The present invention provides an optical adhesive sheet with a peelable liner, wherein the dielectric constant of the non-peelable surface of the peelable liner is 7.5 or less at at least one frequency between 100 Hz and 10 kHz.

[0008] Preferably, the maximum dielectric constant of the non-peeling treated surface of the peeling liner described above is 7.5 or less at frequencies from 100 Hz to 10 kHz.

[0009] It is preferable that the dielectric constant of the non-peeling treated surface of the peeling liner described above is 1.5 or higher at a frequency of 1000 kHz.

[0010] Preferably, the ratio of the dielectric constant of the adhesive layer at a frequency of 10 kHz to the dielectric constant of the non-peelable surface of the peelable liner at a frequency of 10 kHz [adhesive layer / peelable liner] is 1.5 or more.

[0011] It is preferable to provide the adhesive surface of the adhesive layer opposite to the adhesive surface having the above-mentioned release liner with a release liner that has a smaller peeling force to the adhesive surface in contact with the adhesive layer than the above-mentioned release liner.

[0012] In the above-mentioned optical adhesive sheet with a release liner, the adhesive sheet is preferably used for bonding a touch panel to glass. [Effects of the Invention]

[0013] The adhesive sheet with a release liner of the present invention allows for the detection of electric charge through the release liner when the adhesive sheet is attached to a substrate equipped with an optical element that senses electric charge. For example, the detection of electric charge can be confirmed through the release liner using a conductor while the release liner remains attached to the adhesive sheet. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram (cross-sectional view) showing one embodiment of the optical adhesive sheet with a release liner of the present invention. [Figure 2] In the low-temperature flexibility evaluation performed in the example, the test specimen showed a flat state. [Figure 3] The image shows the curved state of the test specimen during the low-temperature flexibility evaluation performed in the example. [Modes for carrying out the invention]

[0015] [Optical adhesive sheet with release liner] 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 protects the adhesive surface that is in contact until the use of the adhesive sheet, and is peeled off when the adhesive surface is bonded.

[0016] An embodiment of the optical adhesive sheet with a release liner of the present invention is shown in Fig. 1. The optical adhesive sheet 10 with a release liner in Fig. 1 comprises 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 treated with a release agent and a non-release-treated surface 2b on the opposite side of 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 is releasably in contact with the release-treated surface 2a of the release liner 2. The release liner 3 has a release-treated surface and a non-release-treated surface on the opposite side of the release-treated surface, similar to the release liner 2, and the release-treated surface is releasably in contact with the adhesive sheet 1 on the surface of the adhesive sheet 1 opposite to the side in contact with the release liner 2. That is, the optical adhesive sheet 1 with a release liner comprises the release liner 2, the adhesive sheet 1, and the release liner 3 in this order in the thickness direction. The optical adhesive sheet 1 with a release liner extends in a direction (plane direction) orthogonal to the thickness direction.

[0017] (Release liner) The surface resistance value of the non-release-treated surface of at least one release liner comprised by the optical adhesive sheet with a release liner of the present invention (for example, the non-release-treated surface 2b of the release liner 2) is 10 12 Ω or less, preferably 10 11 Ω or less, more preferably 10 10 Ω or less. In this specification, a release liner with a surface resistance value of 10 12 Ω or less may be referred to as "the release liner of the present invention".

[0018] The peelable liner of the present invention has a dielectric constant of 7.5 or less at at least one frequency between 100 Hz and 10 kHz on the non-peeling surface (e.g., non-peeling surface 2b), preferably 7 or less, and more preferably 6 or less. The dielectric constant at the above at least one frequency is, for example, 0.5 or more, and may be 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, or 3.0 or more.

[0019] Because the surface resistance and dielectric constant of the release liner of the present invention are within the above range, it is presumed that the capacitance of the release liner is small, charge transfer is possible, charge passes easily in the thickness direction, and static charge is suppressed, preventing the adhesion of foreign matter such as dust. Therefore, even when the adhesive sheet with the release liner of the present invention is attached to a substrate equipped with an optical element that senses charge, it is possible to detect the charge through the release liner. For this reason, for example, with the release liner still attached to the adhesive sheet, it is possible to sense the charge and confirm whether or not there is a change in the amount of charge using a conductor through the release liner.

[0020] The peelable liner of the present invention preferably has a maximum dielectric constant of 7.5 or less at a frequency of 100 Hz to 10 kHz at the non-peeling treated surface (e.g., non-peeling treated surface 2b) of the present invention, more preferably 7 or less. That is, it is preferable that the dielectric constant is within the above range over the entire frequency range of 100 Hz to 10 kHz. When the above maximum value is 7.5 or less, it is easier to detect changes in charge quantity over a wide range of frequencies. The above maximum value is, for example, 0.5 or more, and may 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.

[0021] The peelable liner of the present invention preferably has a dielectric constant of 9.0 or less at a frequency of 100 Hz on the non-peeling treated surface (e.g., non-peeling treated surface 2b), more preferably 8.5 or less, and even more preferably 7.5 or less, but 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 the amount of charge at a frequency of 100 Hz. The dielectric constant may be, 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.

[0022] The peelable liner of the present invention preferably has a dielectric constant of 8.0 or less at a frequency of 1 kHz at the non-peeling treated surface (e.g., non-peeling treated surface 2b), 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 the amount of charge at a frequency of 1 kHz. The dielectric constant may be, 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.

[0023] The peelable liner of the present invention preferably has a dielectric constant of 7.5 or less at a frequency of 10 kHz on the non-peeling treated surface (e.g., non-peeling treated surface 2b), more preferably 6.5 or less, and even more preferably 5.5 or less. A dielectric constant of 7.5 or less makes it easier to detect changes in charge quantity at a frequency of 10 kHz. The dielectric constant may be, for example, 0.5 or more, and may also be 1.0 or more, 1.5 or more, or 2.0 or more.

[0024] The peelable liner of the present invention preferably has a dielectric constant of 4.0 or less at a frequency of 100 kHz on the non-peeling treated surface (e.g., non-peeling treated surface 2b), 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 amount at a frequency of 100 kHz. The dielectric constant may be, for example, 0.5 or more, and may be 1.0 or more, 1.5 or more, or 2.0 or more.

[0025] The peelable liner of the present invention preferably has a dielectric constant of 3.0 or less, and more preferably 2.5 or less, at a frequency of 1000 kHz on the non-peeling treated surface (e.g., non-peeling treated surface 2b). When the dielectric constant is 3.0 or less, it is easier to detect changes in the amount of charge at a frequency of 1000 kHz.

[0026] The peelable liner of the present invention preferably has a dielectric constant of 1.5 or higher at a frequency of 1000 kHz on the non-peeling treated surface (e.g., non-peeling treated surface 2b), and more preferably 1.7 or higher. When the dielectric constant is 1.5 or higher, 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 above ranges.

[0027] The peelable liner of the present invention preferably has a ratio [1kHz / 1000kHz] of the dielectric constant at 1kHz to the dielectric constant at 1000kHz of the non-peeling treated surface (e.g., non-peeling treated surface 2b) of 3.0 or less, more preferably 2.5 or less, and even more preferably 2.0 or less. When the above ratio is 3.0 or less, the dielectric constant is stable in the frequency range of 1 to 1000kHz, and the frequency dependence of the detectability of charge quantity changes is low, resulting in excellent detection stability. The above ratio is preferably 1.0 or more.

[0028] If the adhesive sheet is a double-sided adhesive sheet, each adhesive surface may be protected by two release liners. For example, as shown in Figure 1, the optical adhesive sheet with a release liner of the present invention includes the release liner of the present invention as a first release liner provided to be peelable on one adhesive surface of the adhesive sheet, and a second release liner may also be provided to be peelable 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. In particular, from the viewpoint of preventing separation when using the adhesive sheet with a release liner of the present invention, it is preferable that the two release liners have different peeling forces on the adhesive surface. In this case, it is preferable that the first release liner, the release liner of the present invention, is a (relatively) heavy release liner to the second release liner, and the second release liner is a (relatively) light release liner to the first release liner. Since the release liner of the present invention can detect electric charge while it is attached to the substrate, it is preferable that it be attached to the substrate together with an adhesive sheet.

[0029] In other words, the optical adhesive sheet with a release liner of the present invention preferably has a release liner on the adhesive surface of the adhesive sheet opposite to the adhesive surface equipped with the release liner of the present invention, which has a smaller peeling force to the adhesive surface in contact with 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 preferably consists of the adhesive layer of the present invention described later.

[0030] The release surface of the release liner of the present invention (the surface in contact with the adhesive sheet) is subjected to a release treatment. In other words, the release liner may have a release treatment layer.

[0031] The base material for the above-mentioned peel-off liner is not particularly limited, and known or commonly used materials 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 film, ionomer resin film, ethylene-(meth)acrylic acid copolymer film, ethylene-(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, and fluororesin film. Crosslinked films of these materials are also acceptable. Furthermore, laminated films of these materials may also be used.

[0032] Examples of release agents used in the stripping process include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax-based release agents. Among these, silicone-based release agents are preferred.

[0033] Other release liners mentioned above can be substrates having the aforementioned release treatment layer or conventional release paper, and are not particularly limited, but examples include substrates having a release treatment layer, low-adhesion substrates made of fluoropolymers, and low-adhesion substrates made of nonpolar polymers. Examples of fluoropolymers in the low-adhesion substrates made of fluoropolymers include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, and chlorofluoroethylene-vinylidene fluoride copolymer. Examples of nonpolar polymers include olefin resins (e.g., polyethylene, polypropylene, etc.).

[0034] The above-mentioned peel liner may include other layers besides the above-mentioned substrate and the above-mentioned peel treatment layer. Examples of these other layers include an antistatic layer. These other layers may be a single layer or multiple layers.

[0035] The thickness of the release liner mentioned above is not particularly limited, but is, for example, about 20 to 150 μm.

[0036] The release liner of the present invention can be manufactured by appropriately designing the type and composition of the release agent, antistatic layer, and substrate so that the surface resistance and dielectric constant fall within the specified range. Alternatively, the release liner of the present invention can be manufactured by appropriately selecting a commercially available release liner that has the surface resistance and dielectric constant within the specified range.

[0037] (Adhesive sheet) The above adhesive sheet comprises at least an adhesive layer formed on the peel-processed surface of the peel-off liner of the present invention. In this specification, the adhesive layer formed on the peel-processed surface of the peel-off liner of the present invention may be referred to as the "adhesive layer of the present invention."

[0038] The above adhesive sheet is a double-sided adhesive sheet. The above adhesive sheet may be a so-called "substrate-less type" adhesive sheet (hereinafter sometimes referred to as "substrate-less adhesive sheet") that does not have a base material (substrate layer), or it may be an adhesive sheet of the type that has a base material (hereinafter sometimes referred to as "adhesive sheet with base material"). Examples of the above substrate-less adhesive sheet include a double-sided adhesive sheet consisting only of the adhesive layer of the present invention, and a double-sided adhesive sheet consisting of the adhesive layer of the present invention and an adhesive layer other than the adhesive layer of the present invention (sometimes referred to as "other adhesive layer"). On the other hand, examples of an adhesive sheet with a base material include an adhesive sheet having the adhesive layer of the present invention on at least one side of the base material. Among these, the substrate-less adhesive sheet (substrate-less double-sided adhesive sheet) is preferred, and more preferably, the substrate-less double-sided adhesive sheet consisting only of the adhesive layer of the present invention. In the above substrate-attached double-sided adhesive sheet, both adhesive layers may be the adhesive layer of the present invention, or one may be the adhesive layer of the present invention and the other may be another adhesive layer. Furthermore, it is preferable that all adhesive layers provided in the above adhesive sheet are the adhesive layers of the present invention. Note that the above-mentioned "substrate (substrate layer)" does not include the release liner that is peeled off when the adhesive sheet is used (applied).

[0039] The adhesive layer of the present invention preferably has a dielectric constant of 7.0 or less at at least one frequency between 1 and 1000 kHz, 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 a release liner of the present invention is attached to an object, the object can more easily detect changes in charge amount through the release liner. The dielectric constant at at least one frequency is, for example, 0.5 or more, and may 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.

[0040] The adhesive layer of the present invention preferably has a maximum dielectric constant of 7.0 or less at frequencies from 1 to 1000 kHz, more preferably 6.0 or less, and even more preferably 5.0 or less. That is, it is preferable that the dielectric constant is within the above range over the entire frequency range from 1 to 1000 kHz. When the above maximum value is 7.0 or less, it is easier to detect changes in charge quantity over a wide range of frequencies. The above maximum value is, for example, 0.5 or more, and may 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.

[0041] The adhesive layer of the present invention preferably has a dielectric constant of 7.0 or less at a frequency of 1 kHz, 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 the amount of charge at a frequency of 1 kHz. The dielectric constant may be, 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, 4.0 or more, or 4.5 or more.

[0042] The adhesive layer of the present invention preferably has a dielectric constant of 7.0 or less at a frequency of 10 kHz, 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 the amount of charge at a frequency of 10 kHz. The dielectric constant may be, 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, 4.0 or more, or 4.5 or more.

[0043] The adhesive layer of the present invention preferably has a dielectric constant of 7.0 or less at a frequency of 100 kHz, 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 the amount of charge at a frequency of 100 kHz. The dielectric constant may be, 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.

[0044] The adhesive layer of the present invention preferably has a dielectric constant of 6.0 or less at a frequency of 1000 kHz, 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 the amount of charge at a frequency of 1000 kHz. The dielectric constant may be, 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.

[0045] The adhesive layer of the present invention preferably has a ratio [1kHz / 1000kHz] of the dielectric constant at 1kHz to the dielectric constant at 1000kHz of 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. When the above ratio is 3.0 or less, the dielectric constant is stable in the frequency range of 1 to 1000kHz, and the frequency dependence of the detectability of charge quantity changes is low, resulting in excellent detection stability. The above ratio is preferably 1.0 or more.

[0046] 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-peelable surface of the release liner of the present invention at a frequency of 10 kHz [adhesive layer / release liner] is preferably 1.5 or higher. When the above ratio is 1.5 or higher, it is easier to detect changes in the amount of charge.

[0047] From the viewpoint of ensuring high flexibility and deformability of the adhesive sheet in the low-temperature range, the shear storage modulus (G') of the adhesive layer of the present invention is preferably 200 kPa or less, more preferably 150 kPa or less, and even more preferably 130 kPa or less at -20°C. From the viewpoint of ensuring cohesive force of the adhesive sheet in the low-temperature range, 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, it is preferable that the shear storage modulus (G') of the adhesive sheet at -20°C is within the above range. Methods for adjusting the shear storage modulus of the adhesive layer of the present invention include, for example, selecting the type of base polymer in the adhesive layer of the present invention, adjusting the molecular weight and the amount of blending, and selecting the type of crosslinking agent and adjusting the amount of blending.

[0048] From the viewpoint of ensuring a high degree of flexible deformability that can follow the deformation of the adherend, the adhesive layer of the present invention preferably has a shear storage modulus (G') at 25°C of 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, it is preferable that the shear storage modulus (G') at 25°C of the adhesive sheet is within the above range.

[0049] From the viewpoint of ensuring cohesive force of the adhesive sheet in the high-temperature range, the shear storage modulus (G') of the adhesive layer of the present invention is preferably 15 kPa or more, more preferably 20 kPa or more, even more preferably 25 kPa or more, and particularly preferably 28 kPa or more. From the viewpoint of ensuring high flexibility and deformability of the adhesive sheet in the high-temperature range, the shear storage modulus (G') of the adhesive sheet at 60°C is preferably 60 kPa or less, more preferably 50 kPa or less, and even more preferably 40 kPa or less. Furthermore, it is preferable that the shear storage modulus (G') of the adhesive sheet at 60°C is within the above range.

[0050] The adhesive layer of the present invention is preferably a solvent-free adhesive layer containing a photopolymerized polymer as the base polymer. Such an adhesive layer can be manufactured from a solvent-free adhesive composition. When manufacturing the adhesive layer of the present invention from a solvent-free adhesive composition, there is no need to remove the solvent by volatilizing it from the coating film of the composition. Therefore, an adhesive sheet equipped with the adhesive layer of the present invention is suitable for reducing environmental impact.

[0051] 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 of the present invention (solvent-free adhesive composition) preferably contains at least a photopolymerizable polymer as a base polymer. A photopolymerizable polymer is a polymer formed by a polymerization method in which the polymerization reaction of polymerizable components is advanced by irradiation with active energy rays such as ultraviolet light.

[0052] The base polymer (photopolymer) is an adhesive component that exhibits tackiness in the adhesive layer of the present invention. The base polymer is preferably an acrylic polymer. The acrylic polymer is a (co)polymer of polymerizable components containing 50% by mass or more of alkyl (meth)acrylate. "(meth)acrylic" means acrylic and / or methacrylic.

[0053] The above alkyl (meth)acrylate is preferably an alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group. The alkyl (meth)acrylate may have a linear or branched alkyl group, or a cyclic alkyl group such as an alicyclic alkyl group. The above alkyl (meth)acrylate may be used alone or in combination of two or more types.

[0054] Examples of alkyl (meth)acrylate esters having linear or branched alkyl groups include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, and (meth Examples include isononyl acrylate, decyl (meth)acrylate, isodecyl (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, cetyl (meth)acrylate, heptadecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and nonadecyl (meth)acrylate.

[0055] 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. An example of an alkyl (meth)acrylate having a bicyclic aliphatic hydrocarbon ring is isobornyl (meth)acrylate. Examples of alkyl (meth)acrylates having three or more aliphatic hydrocarbon rings include dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

[0056] The (meth)acrylate alkyl ester is preferably an alkyl acrylate having an alkyl group having 3 to 15 carbon atoms, and 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). Even more preferably, BA and NOAA are used in combination, or 2EHA and LA are used in combination.

[0057] The proportion of alkyl (meth)acrylate 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 polymerizable components constituting the base polymer, from the viewpoint of appropriately exhibiting basic properties such as tackiness in the adhesive sheet. The above proportion is, for example, 99% by mass or less or 96% by mass or less.

[0058] The polymerizable component may include copolymerizable monomers that can copolymerize with alkyl (meth)acrylate esters. Examples of copolymerizable monomers include monomers having polar groups. Examples of polar group-containing monomers include monomers containing hydroxyl groups, monomers containing carboxyl groups, and monomers having nitrogen atom-containing rings. Polar group-containing monomers are useful for modifying acrylic polymers, such as introducing crosslinking sites into acrylic polymers and ensuring the cohesive strength of acrylic polymers. The copolymerizable monomers may be used alone or in combination of two or more types.

[0059] Examples of hydroxyl group-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-hydroxylauryl (meth)acrylate. The hydroxyl group-containing monomer is preferably at least one selected from the group consisting of 2-hydroxyethyl acrylate (HEA) and 4-hydroxybutyl acrylate (4HBA).

[0060] The proportion of hydroxyl group-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 polymerizable components constituting the base polymer, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesive force in the adhesive layer of the present invention. From the viewpoint of adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the adhesive layer of the present invention and the acrylic polymer), the above proportion is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less.

[0061] Examples of monomers containing a carboxyl group include acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

[0062] The proportion of carboxyl group-containing 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 polymerizable components constituting the base polymer, from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer of the present invention, and ensuring adhesion force to the adherend in the adhesive layer of the present invention. The above 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, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of corrosion of the adherend by acid.

[0063] Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, 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-oxazin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, and N-vinylisothiazole. The monomer having a nitrogen atom-containing ring is preferably N-vinyl-2-pyrrolidone (NVP).

[0064] The proportion of monomers having nitrogen atom-containing 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 polymerizable components constituting the base polymer, from the viewpoint of ensuring cohesive force in the adhesive layer of the present invention and ensuring adhesion force to the adherend in the adhesive layer of the present invention. The above proportion is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less, from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to the compatibility between various additive components in the adhesive layer of the present invention and the acrylic polymer).

[0065] The polymerizable component described above may also contain other copolymerizable monomers. Examples of these other copolymerizable monomers include acid anhydride monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. These other copolymerizable monomers may be used alone or in combination of two or more types.

[0066] The above-mentioned base polymer can be formed, for example, by photopolymerizing the polymerizable component described above. Examples of such photopolymerization include photopolymerization by ultraviolet irradiation. A photopolymerization initiator is used as the polymerization initiator. This photopolymerization initiator may be used alone or in combination of two or more types.

[0067] Examples of the above-mentioned photopolymerization initiators include radical photopolymerization initiators, cationic photopolymerization initiators, and anionic photopolymerization initiators.

[0068] Examples of the radical photopolymerization initiators mentioned above include acylphosphine oxide photopolymerization initiators, benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, and thioxanthone photopolymerization initiators.

[0069] 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-trimethylbenzoyldiphenylphosphine 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-(t-butyl)dichloroacetophenone. Examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-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 benzyl photopolymerization initiators include benzyl. Examples of benzophenone photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, and polyvinylbenzophenone. Examples of ketal photopolymerization initiators include benzyldimethylketal. Examples of thioxanthone photopolymerization initiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

[0070] The above 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.

[0071] The amount of the above-mentioned photopolymerization initiator used (the total amount of multiple photopolymerization initiators if 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 also, 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, per 100 parts by mass of the total amount of polymerizable components.

[0072] The above-mentioned base polymer preferably has a crosslinked structure. Examples of methods for introducing a crosslinked structure to the base polymer include the following first and second methods. In the first method, a base polymer having a functional group that can react with a crosslinking agent and a crosslinking agent are blended into an adhesive composition, and the base polymer and crosslinking agent are reacted in the adhesive layer. In the second method, a polyfunctional compound (crosslinking agent), such as a polyfunctional monomer, is included in the polymerizable component that forms the base polymer, and a base polymer in which a branched structure (crosslinked structure) is introduced into the polymer chain is formed by polymerization of the polymerizable component. These methods may be used in combination.

[0073] Examples of crosslinking agents used in the first method described above include compounds that react with functional groups (such as hydroxyl groups and carboxyl groups) contained in the base polymer. Examples of such crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, carbodiimide crosslinking agents, and metal chelate crosslinking agents. The crosslinking agents may be used alone or in combination of two or more types.

[0074] 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, 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, with respect to the viewpoint of ensuring the cohesive force of the adhesive layer of the present invention, per 100 parts by mass of the base polymer.

[0075] In the second method described above, the monofunctional monomer and the polyfunctional compound, such as a polyfunctional monomer for introducing a crosslinking structure, may be polymerized in a single step or in multiple steps. In the multi-step polymerization method, first, the monofunctional monomer is polymerized (prepolymerization), thereby preparing a prepolymer composition containing a partially polymerized product (a mixture of a low-degree polymerized product and an unreacted monomer). Next, the polyfunctional compound as a crosslinking agent is added to the prepolymer composition, and then the partially polymerized product and the polyfunctional compound are polymerized (main polymerization).

[0076] Examples of polyfunctional compounds include polyfunctional monomers and polyfunctional oligomers that contain two or more ethylenically unsaturated double bonds in a single molecule. Examples of polyfunctional monomers include polyfunctional (meth)acrylates.

[0077] Examples of polyfunctional (meth)acrylates include difunctional (meth)acrylates, trifunctional (meth)acrylates, and polyfunctional (meth)acrylates with four or more functions.

[0078] Examples of difunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, ethoxylated bisphenol A diacrylate (BPAEODE), and neopentyl glycol di(meth)acrylate.

[0079] Examples of trifunctional (meth)acrylates include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(acryloyloxyethyl) isocyanurate.

[0080] Examples of polyfunctional (meth)acrylates with four or more functions include ditrimethylolpropanetetra(meth)acrylate, pentaerythritoltetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, alkyl-modified dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0081] Examples of polyfunctional 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.

[0082] In the second method, the polyfunctional compound used as a crosslinking agent may be used alone or in combination of two or more types. Preferably, the polyfunctional compound is at least one selected from the group consisting of 1,6-hexanediol diacrylate (HDDA) and dipentaerythritol hexaacrylate (DPHA).

[0083] When a polyfunctional monomer is used as the polyfunctional compound, the amount of polyfunctional monomer blended 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, per 100 parts by mass of monofunctional monomer, from the viewpoint of ensuring the cohesive force of the adhesive layer of the present invention. The amount of polyfunctional monomer blended 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, per 100 parts by mass of monofunctional monomer, from the viewpoint of ensuring the flexible deformability of the adhesive layer of the present invention.

[0084] When a polyfunctional oligomer is used as the polyfunctional compound, the amount of polyfunctional oligomer blended 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, per 100 parts by mass of monofunctional monomer, from the viewpoint of ensuring the cohesive force of the adhesive layer of the present invention. The amount of polyfunctional oligomer blended 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, per 100 parts by mass of monofunctional monomer, from the viewpoint of ensuring the flexible deformability of the adhesive layer of the present invention.

[0085] In polymerization, chain transfer agents may be used for purposes such as molecular weight adjustment. Examples of chain transfer agents include α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and α-methylstyrene dimers. Chain transfer agents may be used alone or in combination of two or more types.

[0086] 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, from the viewpoint of ensuring cohesive force in the adhesive layer of the present invention. The weight-average molecular weight of the base polymer is measured by gel permeation chromatography (GPC) and calculated on a polystyrene basis.

[0087] The glass transition temperature (Tg) of the base polymer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower. The above glass transition temperature is, for example, -80°C or higher.

[0088] For the glass transition temperature (Tg) of the base polymer, the theoretical glass transition temperature (Tg) can be obtained based on Fox's equation shown below. Fox's equation is a relationship between the glass transition temperature Tg of a polymer and the glass transition temperature Tgi of the homopolymer of the monomers constituting the polymer. In Fox's equation 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. For the glass transition temperature of the homopolymer, literature values ​​can be used. For example, "Polymer Handbook" (4th edition, John Wiley & Sons, Inc., 1999) lists the glass transition temperatures of various homopolymers. On the other hand, the glass transition temperature of the monomer homopolymer can also be determined by the method specifically described in Japanese Patent Publication No. 2007-51271.

[0089] Fox's formula 1 / (273+Tg)=Σ[Wi / (273+Tgi)]

[0090] The adhesive layer of the present invention may contain a silane coupling agent. The content of the silane coupling agent is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, per 100 parts by mass of the base polymer. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

[0091] The adhesive layer of the present invention may contain other components besides those described above, as long as they do not impair 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 phenols, etc.), anti-aging agents, fillers (metal powders, organic fillers, inorganic fillers, etc.), colorants (pigments, dyes, etc.), antioxidants, plasticizers, softeners, surfactants, antistatic agents, surface lubricants, leveling agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, rust inhibitors, granular materials, foil-like materials, flame retardants, and ion trapping agents. Each of these other components may be used individually or in combination of two or more.

[0092] From the viewpoint of ensuring sufficient adhesion to the adherend, 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 thinning the optical adhesive sheet with release liner of the present invention, 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.

[0093] 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 above total light transmittance is, for example, 100% or less. The above total light transmittance can be measured in accordance with JIS K 7375 (2008).

[0094] The optical adhesive sheet with a release liner of the present invention can be manufactured, for example, as follows.

[0095] First, two release liners, each containing a release liner of the present invention, are prepared. The above release liners 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 a release treatment treatment on the surface of the substrate with a release treatment agent. Alternatively, commercially available release liners can also be used.

[0096] Next, the adhesive composition described above is applied to one of the release liners to form a coating film, and then the coating film is solidified. Examples of methods for applying the adhesive composition include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coating.

[0097] The above adhesive composition is preferably solvent-free. That is, it is preferable that the above adhesive composition does not contain or substantially contains organic solvents. The above organic solvent is not particularly limited as long as it is an organic compound used as a solvent, but examples include hydrocarbon solvents such as cyclohexane, hexane, and heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, butanol, and isopropyl alcohol. The above organic solvent may be a mixed solvent containing two or more organic solvents.

[0098] In the above-mentioned adhesive composition, "substantially free of organic solvents" means that organic solvents are not actively incorporated except in cases where they are inevitably mixed in. Specifically, an adhesive composition in which the content ratio of organic solvents is 1.0% by mass or less (preferably 0.5% by mass or less, and more preferably 0.2% by mass or less) relative to the total amount (total mass, 100% by mass) of the adhesive composition can be said to be substantially free of organic solvents.

[0099] The above adhesive compositions can be prepared by known or conventional methods. The above adhesive compositions that are curable by active energy rays can be prepared, for example, by mixing a mixture of polymerizable components or a partial polymer thereof with additives as needed.

[0100] Next, one release liner is bonded onto the coating film on the other release liner. After that, the coating film is aged as needed. The aging temperature is, for example, 20°C to 160°C. The aging time is, for example, 1 minute to 21 days. In addition, light irradiation, such as activated energy ray irradiation, may be performed to solidify the coating film. Examples of light sources for light irradiation include ultraviolet LED lights, high-pressure mercury lamps, and metal halide lamps.

[0101] As described above, the optical adhesive sheet with a release liner of the present invention can be manufactured.

[0102] (Application) The optical adhesive sheet with a release liner of the present invention is used in optical applications, specifically for bonding to optical components. More specifically, it is used, for example, for bonding optical components (for bonding optical components) or in the manufacture of products using the optical components (optical products). Using the optical adhesive sheet with a release liner of the present invention in optical applications provides superior reliability.

[0103] The optical adhesive sheet with a release liner of the present invention is used, for example, in optical components of electrical and electronic equipment to attach (mount) various members or parts to predetermined locations (e.g., housing, front panel, window portion, etc.). "Electrical and electronic equipment" refers to equipment that falls under at least one of either electrical equipment or electronic equipment. Examples of such electrical and electronic equipment include 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 image display devices in portable electronic devices, in-vehicle displays, and digital signage (electronic billboards). The image display devices may be in the form (structure) of a so-called "rigid type" or a so-called "flexible type," or they may be in the form (structure) of a so-called "foldable type" or "rollable type," which can be bent or folded.

[0104] Examples of the above-mentioned portable electronic devices include mobile phones, smartphones, tablet computers, notebook computers, various wearable devices (for example, wristwear-type devices worn on the wrist like watches, modular devices attached to a part of the body with clips or straps, eyewear-type devices including glasses (monocular and binocular types, including head-mounted types), clothing-type devices attached to shirts, socks, hats, etc. as accessories, earwear-type devices attached to the ears like earphones, etc.), digital cameras, digital video cameras, audio equipment (portable music players, IC recorders, etc.), calculators (calculators, etc.), portable game consoles, electronic dictionaries, electronic organizers, e-books, in-car information systems, portable radios, portable televisions, portable printers, portable scanners, and portable modems. In this specification, "portable" means not merely being able to carry something, but having a level of portability that allows an individual (a typical adult) to carry it relatively easily.

[0105] The optical adhesive sheet with a release liner of the present invention (i.e., the adhesive sheet described above) is preferably used for bonding to an optical member equipped with a component capable of detecting changes in charge quantity. An example of a component capable of detecting changes in charge quantity is a panel equipped with a touch sensor (touch panel). Specifically, the optical adhesive sheet with a release liner of the present invention is preferably used for bonding a touch panel and an image display device, where it is placed between the touch panel and the image display device. The optical adhesive sheet with a 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.).

[0106] It is particularly preferable that the adhesive layer of the present invention is directly laminated with the touch sensor. Alternatively, the adhesive layer of the present invention may be directly laminated to the image display device, or it may be laminated via another layer such as a polarizing film. Since the adhesive layer of the present invention is less prone to noise amplification, it can reduce the transmission of noise emitted from the image display device to the touch sensor.

[0107] [Optical components with adhesive layer] By attaching the above adhesive sheet to an optical member, an optical member with an adhesive layer can be obtained, comprising an optical member and an optical adhesive sheet with a release liner of the present invention attached to at least one surface of the optical member. The adhesive sheet of the optical member with an adhesive layer has the release liner of the present invention on its adhesive surface until use, and is peeled off when it is attached to another substrate.

[0108] The above-mentioned optical component with adhesive layer may be an optical component (touch sensor film) having metal wiring such as a metal mesh film or silver nanowire film, to which the adhesive layer of the present invention is attached. In that case, it is preferable that the adhesive layer of the present invention is attached to the side of the touch sensor film that has the metal wiring.

[0109] [Optical laminate] By providing the above-mentioned adhesive sheet between the touch sensor and the image display device, an optical laminate (the optical laminate of the present invention) is obtained, comprising the touch sensor, the adhesive sheet, and the image display device in this order. The optical laminate may comprise the touch sensor and the adhesive sheet in single layers or in multiple layers. When multiple touch sensors are provided, it is preferable that the touch sensors are laminated with the above-mentioned adhesive sheet in between.

[0110] Examples of the image display device mentioned above include those described above. The touch sensor is a capacitive touch sensor, and is, for example, a transparent conductive film in which a transparent conductive layer is provided on a glass plate or a transparent plastic film (particularly PET film, polycarbonate film, or cyclic olefin polymer film). It is preferable that the adhesive sheet is bonded so as to be in contact with the transparent conductive layer.

[0111] Examples of the transparent conductive layer include thin films of ITO (indium tin oxide), ZnO, SnO, and CTO (cadmium tin oxide). Other materials that can be used to form the transparent conductive layer include silver, copper, and CNT (carbon nanotubes). Furthermore, metal mesh sensors such as Ag nanowires and Ag / Cu can also be used in the transparent conductive layer. The touch sensor may also have wiring formed from thin films of copper or silver paste at its ends.

[0112] The optical laminate may include a cover member. The cover member is provided on the surface opposite to the side equipped with the touch sensor image display device and protects the touch sensor and image display device in the optical laminate. Examples of the cover member include a cover glass and a plastic cover. The cover member may be bonded to the layers constituting the optical laminate, such as the touch sensor, via the adhesive sheet. The optical laminate may also have a polarizing film on the surface of the image display device (the surface equipped with the touch sensor).

[0113] The optical laminate described above may include a noise reduction layer (such as a noise reduction film). From the viewpoint of needing to suppress the amplification of noise emitted by the image display device, it is preferable that the noise reduction layer be provided between the touch sensor and the image display device. The noise reduction layer and the touch sensor, and the noise reduction layer and the image display device, are each bonded together via an adhesive layer. The noise reduction layer may be a single layer or a multi-layer layer. When multiple noise reduction layers are provided, the multiple noise reduction layers may be the same layer in terms of composition, thickness, etc., or they may be different layers.

[0114] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit it. [Examples]

[0115] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. Note that all amounts (parts by mass) refer to the amount of each component described.

[0116] [Example 1] (Preparation of prepolymer composition) In a flask, a monomer mixture containing 70 parts by mass of n-octyl acrylate (NOAA), 20 parts by mass of n-butyl acrylate (BA), 8 parts by mass of 4-hydroxybutyl acrylate (4HBA), and 2 parts by mass of N-vinyl-2-pyrrolidone (NVP) was mixed with 0.05 parts by mass of a first photopolymerization initiator (product name "Omnirad184," 1-hydroxycyclohexyl phenyl ketone, manufactured by IGM Resins) and 0.05 parts by mass of a second photopolymerization initiator (product name "Omnirad819," bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, manufactured by IGM Resins). The mixture was then irradiated with ultraviolet light under a nitrogen atmosphere to polymerize a portion of the monomer components in the mixture and obtain a first prepolymer composition. A black light was used for ultraviolet irradiation. The ultraviolet irradiation was continued until the viscosity of the composition reached approximately 20 Pa·s. This viscosity was measured using a B-type viscometer under the conditions of rotor No. 5, rotor speed of 10 rpm, and temperature of 30°C (the same conditions apply to the viscosity described later). The resulting prepolymer composition is a partially polymerized product containing a photopolymer and monomer components that have not undergone polymerization (residual monomers).

[0117] (Preparation of adhesive composition) A sizing agent composition was prepared by mixing 100 parts by mass of the first prepolymer composition, 1.5 parts by mass of the following oligomer, and 0.5 parts by mass of a silane coupling agent (product name "KBM-403", manufactured by Shin-Etsu Chemical Co., Ltd.).

[0118] (Preparation of oligomers) First, in a reaction vessel equipped with a stirrer, thermometer, reflux condenser, and nitrogen gas inlet tube, a mixture containing 60 parts by mass of dicyclopentanyl 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, which was reacted under a nitrogen atmosphere at 70°C for 1 hour, and then at 80°C for 2 hours (polymerization reaction). Next, the reaction solution was heated to 130°C to volatilize and remove toluene, chain transfer agent, and unreacted monomers. This yielded an acrylic oligomer (solid form) as a hydrophobic oligomer without polar groups. The weight-average molecular weight of this acrylic oligomer was 5100.

[0119] (Formation of the adhesive layer) A coating film was formed by applying the above adhesive composition to the release surface of a first release liner (product name "RF12ASD", manufactured by SK Chemicals Co., Ltd.), which has a release surface treated with a silicone-based release agent on one side. Next, the release surface of a second release liner (product name "Diafoil MRE#75", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation), which has a release surface on one side, was bonded onto the coating film on the first release liner. Then, ultraviolet light was irradiated onto the coating film between the release liners to photocur the coating film and form an adhesive layer (thickness 50 μm). For ultraviolet irradiation, a black light was used as the light source, and the irradiation intensity was set to 5 mW / cm². 2 Relatively speaking, the first delamination liner is a heavily delaminating liner, and the second delamination liner is a lightly delaminating liner.

[0120] As described above, an optical adhesive sheet with a double-sided release liner was prepared according to Example 1.

[0121] [Example 2] An optical adhesive sheet with double-sided peel-off liners was prepared in the same manner as in Example 1, except that a peel-off liner (product name "RF17ASD", manufactured by SK Chemicals Co., Ltd.) having a peel-off surface treated with a silicone-based release agent on one side was used as the heavy peel-off liner, instead of the first peel-off liner.

[0122] [Example 3] An optical adhesive sheet with double-sided peel-off liners was prepared in the same manner as in Example 1, except that a peel-off liner (product name "RF32ASD", manufactured by SK Chemicals Co., Ltd.) having a peel-off surface treated with a silicone-based release agent on one side was used as the heavy peel-off liner, instead of the first peel-off liner.

[0123] [Comparative Example 1] A comparative optical adhesive sheet with double-sided peel-off liners was prepared in the same manner as in Example 1, except that a peel-off liner having a peel-treated surface on one side treated with a silicone-based release agent (surface resistance and dielectric constant are as shown in Table 1) was used as the heavy peel-off liner, instead of the first peel-off liner.

[0124] [Comparative Example 2] A comparative example 2 optical adhesive sheet with double-sided peel-off liners was prepared in the same manner as in Example 1, except that a peel-off liner having a peel-treated surface on one side treated with a silicone-based release agent (product name "Diafoil MRV#6", manufactured by Mitsubishi Chemical Corporation) was used as the heavy peel-off liner, instead of the first peel-off liner.

[0125] <Rating> The optical adhesive sheets of the examples and comparative examples were evaluated as follows. The evaluation results are shown in the table.

[0126] (1) Permittivity (relative permittivity) The dielectric constants of the heavy-peel liner and adhesive layer used in the examples and comparative examples were measured as follows. The dielectric constant of the heavy-peel liner was measured on the non-peelable surface before the adhesive layer was formed. The dielectric constant of the adhesive layer was measured on the adhesive surface exposed after peeling the second peel liner off the obtained optical adhesive sheet. A measurement sample was prepared by sandwiching a copper foil between the electrodes. Next, the dielectric constant of the measurement sample was measured using a KEYSIGHT E4980A in accordance with JIS K6911, under the following conditions: a frequency range of 100 Hz to 1000 kHz for the release liner and a frequency range of 1 to 1000 kHz for the adhesive layer.

[0127] [Measurement conditions for dielectric constant] Electrode configuration: Aluminum plate with a diameter of 12.1 mm and a thickness of 0.5 mm. Counter electrode: 3oz copper plate Measurement environment: Temperature 25°C, relative humidity 50%

[0128] (2) Surface resistance For the heavy peeling liners used in the examples and comparative examples, the surface resistance was measured using a resistivity meter (TREK Model 152-1) in an environment of 23°C and 50% relative humidity. The probe (TREK Model 152P-2P) was brought into contact with the non-peeling treated surface of the heavy peeling liner, and the applied voltage was 100V for a voltage application time of 3 seconds.

[0129] (3) Shear storage modulus For each optical adhesive sheet, the required number of measurement samples were prepared. Specifically, first, multiple adhesive sheet pieces cut from the optical adhesive sheet were bonded together to create a sample sheet with a thickness of approximately 1.0 mm. Next, this sheet was punched out to obtain cylindrical pellets (7.9 mm in diameter) which were to be used as measurement samples. Then, dynamic viscoelasticity measurements were performed on the measurement samples using a dynamic viscoelasticity measuring device (product name "Discovery Hybrid Reometeter-2 (DHR-2)", manufactured by TA Instruments) after fixing them to a parallel plate jig with a diameter of 7.9 mm. In this measurement, the measurement mode was set to shear mode, the measurement temperature range to -50°C to 150°C, the heating rate to 5°C / min, and the frequency to 1 Hz. From the measurement results, the shear storage modulus at predetermined temperatures (-20°C, 25°C, 60°C) was read.

[0130] (4) Antistatic properties In the measurement of surface resistance described above, "○" was used to indicate when an actual value was obtained, and "×" was used to indicate when the measurement limit was exceeded and an actual value could not be obtained, thereby evaluating the antistatic properties.

[0131] (5) Low temperature flexibility The light-peel liner was peeled off the optical adhesive sheet, and the exposed surface was plasma-treated. Meanwhile, both sides (first and second surfaces) of a 51 μm thick polarizing film were also plasma-treated. Furthermore, the surface of an 80 μm thick transparent polyimide film and the surface of a 125 μm thick polyethylene terephthalate (PET) film were also plasma-treated. For each plasma treatment, a plasma irradiation device (product name "AP-TO5," manufactured by Sekisui Chemical Co., Ltd.) was used, with a voltage of 160 V, a frequency of 10 kHz, and a processing speed of 5000 mm / min. The exposed adhesive surface of the adhesive sheet and the first surface of the polarizing film were then bonded together. This bonding was performed in a 23°C environment, using a 2 kg roller to press the adhesive sheet with the heavy-peel liner against the polarizing film in one back-and-forth motion. Next, the heavy-peel liner was peeled off the adhesive sheet with the polarizing film, and the exposed surface of the adhesive sheet was then bonded to the transparent polyimide film. Next, the PET film was laminated to the second surface of the polarizing film via a thin, strong adhesive sheet with a thickness of 15 μm. In this lamination process, the polarizing film and the PET film were pressed together by running a 2 kg roller back and forth once in an environment of 23°C. This resulted in a laminated film having a layered structure consisting of a PET film (thickness 125 μm), a thin, strong adhesive sheet (thickness 15 μm), a polarizing film (thickness 51 μm), an adhesive sheet (thickness 50 μm), and a transparent polyimide film (thickness 80 μm).

[0132] Next, test specimens for evaluation were cut from the laminated film prepared in this manner. Specifically, rectangular test specimens measuring 35 mm × 100 mm were cut from the laminated film so that the absorption axis direction of the polarizing film in the cut specimen was parallel to the direction of the longer side. Next, these test specimens were autoclaved for 15 minutes at 35°C and 0.50 MPa.

[0133] Next, the test specimen was subjected to a bending test using a planar unloaded U-shaped stretch tester (manufactured by Yuasa System Equipment Co., Ltd.). In this test, as shown in Figure 2, the bending fixtures 201 and 202 of the test machine were attached to each of the ends of the long side of the test specimen 100, and the test specimen 100 was fixed to the test machine. Each of the bending fixtures 201 and 202 held a range of 20 mm from the edge of the test specimen 100. The central 60 mm area of ​​the long side of the test specimen 100 was not fixed to the bending fixtures 201 and 202. In this test, the test specimen 100 was repeatedly deformed (bent) 200,000 times at a bending speed of 60 rpm in a constant temperature bath at -20°C, between a bent form (Figure 3) with the PET film side facing inward and an unbent form (Figure 2). In this test, the bending configuration specifically refers to a configuration where the axis of the bending moment acting on the test specimen 100 is perpendicular to the absorption axis of the polarizing film. In this bending configuration, the bending radius of the test specimen 100 was set to 1.3 mm and the bending angle to 180°. The repeatedly bent portion 100a of the test specimen 100 was observed, and the adhesion of the adhesive sheet to the substrate in the bending test was evaluated as follows: "○" if no peeling occurred between the adhesive sheet and the substrate (transparent polyimide film, polarizing film), and "×" if peeling occurred. The evaluation results are shown in Table 1.

[0134] (6) Charge detection A light-peel liner was peeled off the optical adhesive sheet, and the exposed surface was attached to the display of a "Galaxy Fold5" (manufactured by Samsung Electronics) to create an evaluation laminate. Then, the heavy-peel liner on the surface of the optical adhesive sheet was pressed down with a finger and moved back and forth at a constant speed, and the sensitivity was checked. A response from the sensor was evaluated as "○", and no response as "×". The evaluation results are shown in Table 1.

[0135] [Table 1]

[0136] As shown in Table 1, the optical adhesive sheets with release liners in the examples were evaluated as having excellent charge detection properties, excellent low-temperature flexibility, and excellent bending stability. On the other hand, when the dielectric constant of the non-peelable surface exceeded 7.5, the charge detection properties via the release liner were evaluated as being poor.

[0137] The following describes variations of the invention relating to this disclosure. [Note 1] The peel liner comprises a peelable surface and a non-peelable surface, and an adhesive layer formed on the peelable surface of the peel liner. The surface resistance of the non-peelable surface of the peelable liner is 10 12 It is less than or equal to Ω, An optical adhesive sheet with a release liner, wherein the dielectric constant of the non-peelable surface of the release liner is 7.5 or less at at least one frequency between 100 Hz and 10 kHz. [Note 2] The maximum dielectric constant of the non-peelable surface of the peelable liner at frequencies of 100 Hz to 10 kHz is 7.5 or less, as described in Note 1. [Note 3] The optical adhesive sheet with a peelable liner according to Note 1 or 2, wherein the dielectric constant of the non-peelable surface of the peelable liner at a frequency of 1000 kHz is 1.5 or more. [Note 4] The ratio of the dielectric constant of the adhesive layer at a frequency of 10 kHz to the dielectric constant of the non-peelable surface of the peel liner at a frequency of 10 kHz [adhesive layer / peel liner] is 1.5 or more, as described in any one of Notes 1 to 3. [Note 5] An optical adhesive sheet with a release liner according to any one of Notes 1 to 4, wherein the adhesive surface of the adhesive layer opposite to the adhesive surface having the release liner has a release liner that has a smaller peeling force to the adhesive surface in contact with the adhesive layer than the release liner. [Note 6] The adhesive sheet in the aforementioned optical adhesive sheet with a release liner is an optical adhesive sheet with a release liner as described in any one of Notes 1 to 5, for the purpose of bonding a touch panel and glass. [Explanation of Symbols]

[0138] 10 Optical adhesive sheets with release liner 1 Adhesive sheet 2,3 Peel-off liner

Claims

1. The invention comprises a peelable liner having a peelable surface and a non-peelable surface, and an adhesive layer formed on the peelable surface of the peelable liner, The surface resistance of the non-peelable surface of the peelable liner is 10 １２ It is less than or equal to Ω, An optical adhesive sheet with a release liner, wherein the dielectric constant of the non-peelable surface of the release liner is 7.5 or less at at least one frequency between 100 Hz and 10 kHz.

2. The optical adhesive sheet with a peelable liner according to claim 1, wherein the maximum dielectric constant of the non-peelable surface of the peelable liner at frequencies of 100 Hz to 10 kHz is 7.5 or less.

3. The optical adhesive sheet with a peelable liner according to claim 1 or 2, wherein the dielectric constant of the non-peelable surface of the peelable liner at a frequency of 1000 kHz is 1.5 or more.

4. The optical adhesive sheet with a peel-off liner according to claim 1 or 2, wherein the ratio of the dielectric constant of the adhesive layer at a frequency of 10 kHz to the dielectric constant of the non-peelable surface of the peel-off liner at a frequency of 10 kHz [adhesive layer / peele-off liner] is 1.5 or more.

5. The optical adhesive sheet with a release liner according to claim 1 or 2, wherein the adhesive surface of the adhesive layer opposite to the adhesive surface having the release liner is provided with a release liner having a smaller peeling force to the adhesive surface in contact with 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 is used to bond a touch panel and glass.

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