Optical adhesive sheet with release liner

Abstract

The optical adhesive sheet (X) with a release liner of the present invention has: an adhesive sheet (10) (optical adhesive sheet), a release liner (20) (heavy release liner) which is releasably in contact with a first surface (11) of the adhesive sheet (10), and a release liner (30) (light release liner) which is releasably in contact with a second surface (12) of the adhesive sheet (10). The adhesive sheet (10) contains a base polymer, a photopolymerizable multifunctional compound, and a photopolymerization initiator. In a probe tack test performed on the second surface (12) after the release liner (30) is peeled from the adhesive sheet (10) under prescribed conditions, the probe peeling distance at the time when the stress during the probe peeling becomes 0 gf is 200 μm or more and 900 μm or less.

Description

Technical Field

[0001] This invention relates to optical adhesive sheets with release liner. Background Technology

[0002] Display panels, for example, have a laminated structure including elements such as pixel panels, polarizing films, and protective glass. During the manufacturing process of the display panel, optically transparent adhesive sheets (optical adhesive sheets) are used, for example, to join the elements included in the laminated structure together. Optical adhesive sheets are manufactured, for example, in the form of optical adhesive sheets with release liner attached to both sides. In optical adhesive sheets with release liner, a heavy release liner is attached to one side of the optical adhesive sheet, and a light release liner is attached to the other side. Such optical adhesive sheets for display panel applications are described, for example, in Patent Document 1 below.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-122140 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The laminated structure of a display panel includes elements with surface height differences. For example, a printed layer for decoration or light shielding is provided at the edge of the pixel panel side surface of the protective glass, creating a height difference (printing height difference) between the protective glass surface and the printed layer surface. Therefore, for optical adhesive sheets used in display panels, in addition to requiring reliable bonding between the adhered materials, flexibility to follow the degree of printing height difference (height difference following ability) is also required. Insufficient height difference following ability of the optical adhesive sheet can lead to air bubbles forming along the printed layer between the optical adhesive sheet and the protective glass, which is unsatisfactory.

[0008] From the perspective of height difference tracking, a flexible optical adhesive sheet is preferred. However, in optical adhesive sheets with release liner, the more flexible the optical adhesive sheet, the more likely the heavy release liner will be accidentally peeled off when the light release liner is peeled off from the optical adhesive sheet.

[0009] The present invention provides an optical adhesive sheet with a release liner suitable for suppressing the peeling of a heavy release liner during the peeling of a light release liner and taking into account the height difference followability.

[0010] means for solving problems

[0011] The present invention [1] is an optical adhesive sheet with a release liner, the optical adhesive sheet with a release liner comprising: an optical adhesive sheet having a first side and a second side opposite to the first side; a heavy release liner that is peelably in contact with the first side; and a light release liner that is peelably in contact with the second side, wherein the optical adhesive sheet comprises a base polymer, a photopolymerizable multifunctional compound and a photopolymerization initiator, and in a probe adhesion test performed on the second side after the light release liner has been peeled off from the optical adhesive sheet under the following conditions, the probe peeling distance when the stress becomes 0 gf during the probe peeling process is more than 200 μm and less than 900 μm.

[0012] condition

[0013] Temperature: 25℃

[0014] Probe diameter: 2.5mm

[0015] Compressive load: 1000gf

[0016] Pressing time: 30 seconds

[0017] Peeling speed: 0.08 mm / s

[0018] The present invention [2] comprises the optical adhesive sheet with a release liner as described in [1] above, wherein the photopolymerizable multifunctional compound comprises a photopolymerizable multifunctional compound having an aromatic ring.

[0019] The present invention [3] comprises the optical adhesive sheet with release liner described in [1] or [2] above, wherein the weight average molecular weight of the photopolymerizable multifunctional compound is less than 1000.

[0020] The present invention [4] comprises an optical adhesive sheet with a release liner as described in any one of [1] to [3] above, wherein the gel fraction of the optical adhesive sheet with a release liner is 50% by mass or more.

[0021] Invention Effects

[0022] As described above, the optical adhesive sheet with a release liner of the present invention comprises a base polymer, a photopolymerizable multifunctional compound, and a photopolymerization initiator. With such an optical adhesive sheet, when bonding between adherends using the optical adhesive sheet (before photocuring), the flexibility of the adhesive sheet can be ensured, and after bonding, the adhesive sheet can be made highly elastic by photopolymerizing the photopolymerizable multifunctional compound. Such an optical adhesive sheet is suitable for ensuring the conformity of surface differences between adherends during bonding and the reliability of the bonding after bonding. Furthermore, with respect to the optical adhesive sheet with a release liner, in a probe adhesion test performed under specified conditions on the second side after peeling off the light release liner from the optical adhesive sheet, the probe peeling distance when the stress reaches 0 gf during probe peeling is 200 μm or more and 900 μm or less. Such an optical adhesive sheet with a release liner is suitable for suppressing accidental peeling of the heavy release liner when peeling off the light release liner from the optical adhesive sheet. Attached Figure Description

[0023] Figure 1 This is a schematic cross-sectional view of one embodiment of the optical adhesive sheet with a release liner of the present invention.

[0024] Figure 2 This schematically illustrates a probe adhesion test.

[0025] Figure 3 This represents an example of a stress-peel distance curve obtained in a probe adhesion test.

[0026] Figure 4 shows Figure 1 An example of a method for manufacturing an optical adhesive sheet with a release liner is shown. Figure 4A This indicates the process of forming a coating film from an adhesive composition. Figure 4B This indicates the process of forming the adhesive sheet. Figure 4C This indicates the peeling process of the light peeling liner. Figure 4D This indicates the process of adding components after supplying the base adhesive sheet. Figure 4E This indicates the process of attaching another light-peeling liner to the adhesive sheet.

[0027] Figure 5 shows Figure 1 An example of how to use the optical adhesive sheet is shown. Figure 5A and Figure 5B This indicates the process of joining a first substrate and a second substrate using an optical adhesive sheet. Figure 5C This indicates the ripening process.

[0028] Figure 6 The stress-peel distance curve of the optical adhesive sheet with a release liner in Example 1 is shown by a probe adhesion test.

[0029] Figure 7The stress-peel distance curve of the optical adhesive sheet with a release liner in Example 2 is shown by a probe adhesion test.

[0030] Figure 8 The stress-peel distance curve of the optical adhesive sheet with a release liner in Example 3 is shown by a probe adhesion test.

[0031] Figure 9 The stress-peel distance curve of the optical adhesive sheet with a release liner of Comparative Example 1 is shown by a probe adhesion test.

[0032] Figure 10 This indicates the positional relationship between the glass plate and the optical adhesive sheet in the joint used in the evaluation of the height difference tracking of the embodiments and comparative examples. Detailed Implementation

[0033] like Figure 1 As shown, an optical adhesive sheet X with a release liner, as an embodiment of the present invention, includes an adhesive sheet 10, a release liner 20, and a release liner 30. The adhesive sheet 10 has a first surface 11 and a second surface 12 opposite to the first surface 11. The first surface 11 and the second surface 12 are adhesive surfaces. The release liner 20 has a release surface 21. The release liner 20 is in peelable contact with the first surface 11 of the adhesive sheet 10 on the release surface 21 side. The release liner 30 has a release surface 31. The release liner 30 is in peelable contact with the second surface 12 of the adhesive sheet 10 on the release surface 31 side. That is, the optical adhesive sheet X with a release liner has the release liner 20, the adhesive sheet 10, and the release liner 30 sequentially in the thickness direction H. The optical adhesive sheet X with a release liner extends in a direction orthogonal to the thickness direction H (surface direction).

[0034] The adhesive sheet 10 is an optically transparent adhesive sheet (optical adhesive sheet). The adhesive sheet 10 is a sheet-like pressure-sensitive adhesive. The adhesive sheet 10 contains a base polymer, a photopolymerizable multifunctional compound, and a photopolymerization initiator, and has photocurability. The adhesive sheet 10 is, for example, an optical adhesive sheet disposed in a light-transmitting portion of a display panel. Examples of display panels include, for example, liquid crystal display panels and organic EL display panels. The display panel, for example, has a laminated structure including elements such as a pixel panel, a polarizing film, a touch panel, and a protective glass. The adhesive sheet 10 is used, for example, during the manufacturing process of the display panel to bond the elements included in the laminated structure to each other.

[0035] Release liner 20 is a heavy release liner requiring a relatively large force to peel from the adhesive sheet 10, while release liner 30 is a light release liner requiring a relatively small force to peel from the adhesive sheet 10. Specifically, in a peel test conducted at 25°C, a peel angle of 180°, and a pulling speed of 300 mm / min, the release liner 20 exhibits a greater peel force than the release liner 30. More specifically, the method for determining this peel force is as described in the embodiments described later. When using the adhesive sheet 10, the release liner 30 (light release liner) and the release liner 20 (heavy release liner) are peeled from the adhesive sheet 10 in this order.

[0036] In a probe adhesion test conducted on the second surface 12 after the release liner 30 has been peeled off from the adhesive sheet 10, the probe peeling distance d when the stress becomes 0gf during the probe peeling process is more than 200μm and less than 900μm.

[0037] [condition]

[0038] Temperature: 25℃

[0039] Probe diameter: 2.5mm

[0040] Compressive load: 1000gf

[0041] Pressing time: 30 seconds

[0042] Peeling speed: 0.08 mm / s

[0043] Before the probe adhesion test, such as Figure 2 As shown, the adhesive sheet 10 with release liner 20 is mounted as test piece Z on the measuring stage W of the adhesiveness testing machine. Specifically, firstly, the release liner 20 side of the optical adhesive sheet X with release liner is fixed to the measuring stage W using adhesive (not shown). Then, the release liner 30 is peeled off from the adhesive sheet 10 of the optical adhesive sheet X with release liner on the measuring stage W.

[0044] The probe adhesion test under the above conditions is described in detail below. A cylindrical stainless steel probe with a tip diameter (probe diameter) of 2.5 mm was used as probe P. The area of ​​the tip Pa of probe P is 19.63 mm². 2Then, the ambient temperature and the temperature of probe P were adjusted to 25°C. The tip Pa of probe P (2.5 mm in diameter) was then pressed vertically onto the adhesive sheet 10 from above at a pressing speed of 0.08 mm / s until the pressing load reached 1000 gf. Next, the pressing load of 1000 gf was maintained on probe P for 30 seconds. Then, probe P was peeled upwards from the second surface 12 of the adhesive sheet 10 at a peeling speed of 0.08 mm / s (peeling process). During this process, the load acting on probe P was measured as the stress on the adhesive sheet 10. The method for the probe adhesion test is specifically described in the embodiments described later.

[0045] An example of a stress-peel distance curve representing the stress (load acting downwards on probe P) after the start of peeling of probe P is shown in [the figure]. Figure 3 In. Figure 3 In the graph, the horizontal axis represents the peeling distance (μm) of probe P, and the vertical axis represents the stress (gf). The peeling distance of probe P refers to the rising distance of the tip Pa of probe P during the peeling process (the distance moved in the height direction from the position of the second surface 12 at the start of peeling). During the probe peeling process, firstly, the adhesive sheet 10 undergoes elastic deformation, and the stress increases. Then, after the stress reaches the maximum stress Smax, the adhesive sheet 10 undergoes plastic deformation, and the stress decreases. The stress of the adhesive sheet 10 decreases to 0gf. The probe peeling distance when the stress is 0gf is shown as distance d. Figure 3 In the process of adjusting the peel distance d at a stress of 0 gf, methods for adjusting the peel distance d include, for example, the selection of the type of base polymer in the adhesive sheet 10, the adjustment of its molecular weight, and the adjustment of its compounding amount. The selection of the type of base polymer includes adjusting the composition of the monomers forming the base polymer. Methods for adjusting the peel distance d also include the selection of the type of components other than the base polymer in the adhesive sheet 10, the adjustment of their molecular weight, and the adjustment of their compounding amount. Examples of such components include photopolymerizable multifunctional compounds and silane coupling agents.

[0046] As described above, the adhesive sheet 10 of the optical adhesive sheet X with a release liner comprises a base polymer, a photopolymerizable multifunctional compound, and a photopolymerization initiator. With such an adhesive sheet 10, when bonding between adherends using the adhesive sheet 10 (before photocuring), the flexibility of the adhesive sheet 10 can be ensured, and after bonding, the adhesive sheet 10 can be made highly elastic by photopolymerizing the photopolymerizable multifunctional compound. Such an adhesive sheet 10 is suitable for ensuring conformity to the surface differences of the adherends during bonding and for ensuring the reliability of the bond after bonding.

[0047] Furthermore, in the optical adhesive sheet X with a release liner, during the probe adhesion test conducted on the second surface 12 under the aforementioned conditions after the release liner 30 (light release liner) has been peeled off from the adhesive sheet 10, the peeling distance d of the probe when the stress reaches 0gf during the probe peeling process is 200 μm or more and 900 μm or less. The optical adhesive sheet with a release liner having a peeling distance d of 900 μm or less is suitable for suppressing accidental peeling of the release liner 20 (heavy release liner) when peeling the release liner 30 (light release liner) from the adhesive sheet 10. Furthermore, the optical adhesive sheet with a release liner having a peeling distance d of 200 μm or more is suitable for ensuring the adhesion of the surface of the adhesive sheet 10 and ensuring the reliability of the bonding after joining the adhered objects using the adhesive sheet 10.

[0048] As described above, the optical adhesive sheet X with release liner is suitable for suppressing the peeling of release liner 20 (heavy release liner) when release liner 30 (light release liner) peels off, while also taking into account height difference followability.

[0049] From the viewpoint of suppressing the above-mentioned peeling, the peeling distance d (stress of 0gf) is preferably 250μm or more, more preferably 300μm or more, even more preferably 400μm or more, and preferably 850μm or less, more preferably 750μm or less, and even more preferably 650μm or less.

[0050] From the viewpoint of improving the shelf life of the optical adhesive sheet X or adhesive sheet 10 with release liner, the gel fraction of adhesive sheet 10 (before photocuring) is preferably 50% by mass or more, more preferably 53% by mass or more. If the shelf life of adhesive sheet 10 is low, the shape of the product may easily change due to the flow of adhesive sheet 10 during storage of the optical adhesive sheet X with release liner; furthermore, indentations may easily form on adhesive sheet 10 when stored in a stacked state. From the viewpoint of ensuring the aforementioned height difference tracking, the gel fraction of adhesive sheet 10 (before photocuring) is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 55% by mass or less. Methods for adjusting the gel fraction of adhesive sheet 10 include, for example, the selection of the type of base polymer in adhesive sheet 10, adjustment of molecular weight, and adjustment of the amount of compounding. The method for determining the gel fraction is described in the examples described later.

[0051] From the viewpoint of preventing accidental peeling of the release liner 20 from the adhesive sheet 10, the peel force F1 used to peel the release liner 20 (re-release liner) from the adhesive sheet 10 (before light curing) is preferably 0.1 N / 25 mm or more, more preferably 0.3 N / 25 mm or more, and even more preferably 0.5 N / 25 mm or more. From the viewpoint of ensuring the ease of peeling the release liner 20 from the adhesive sheet 10, the peel force F1 is preferably 3.0 N / 25 mm or less, more preferably 2.0 N / 25 mm or less, and even more preferably 1.0 N / 25 mm or less. The peel force F1 is a value measured by performing a peel test to peel the release liner 20 from the adhesive sheet 10 under the conditions of a measurement temperature of 25°C, a peel angle of 180°, and a pulling speed of 300 mm / min. The method for measuring the peel force F1 is specifically described in the examples described later. As methods for adjusting the peel force F1, examples include: the selection of the type of base polymer in the adhesive sheet 10, the adjustment of the molecular weight, and the adjustment of the compounding amount. Methods for adjusting the peel force F1 may include: selecting the types of components other than the base polymer in the adhesive sheet 10, and adjusting the amount of these components. Examples of these components include photopolymerizable multifunctional compounds and silane coupling agents. These adjustment methods also apply to the peel force F2, which will be described later. Furthermore, methods for adjusting the peel force F1 may include selecting the types of materials used to form the peel surface 21 of the peel liner 20.

[0052] From the viewpoint of preventing the release liner 30 from accidentally peeling off from the adhesive sheet 10, the peel force F2 used to peel the release liner 30 (light release liner) from the adhesive sheet 10 is preferably 0.001 N / 25 mm or more, more preferably 0.01 N / 25 mm or more, and even more preferably 0.015 N / 25 mm or more. From the viewpoint of ensuring the light peelability of the release liner 30 as a light release liner, the peel force F2 is preferably 1.0 N / 25 mm or less, more preferably 0.1 N / 25 mm or less, and even more preferably 0.05 N / 25 mm or less. The peel force F2 is a value measured by performing a peel test to peel the release liner 30 off from the adhesive sheet 10 under the conditions of a measurement temperature of 25°C, a peel angle of 180°, and a pulling speed of 300 mm / min. The method for measuring the peel force F2 is specifically described in the embodiments described later. As a method for adjusting the peel force F2, the selection of the type of material forming the peel surface 31 of the release liner 30 can be listed.

[0053] From the viewpoint of suppressing the peeling of the release liner 20 during the peeling of the release liner 30, the difference between the peeling force F1 and the peeling force F2, F1-F2, is preferably 0.1 N / 25 mm or more, more preferably 0.3 N / 25 mm or more, and even more preferably 0.5 N / 25 mm or more. From the viewpoint of ensuring the uniform peelability of the release liner 20 and the release liner 30 from the adhesive sheet 10, the difference F1-F2 is preferably 2.0 N / 25 mm or less, more preferably 1.0 N / 25 mm or less, and even more preferably 0.6 N / 25 mm or less.

[0054] From the viewpoint of suppressing the peeling of the release liner 20 during the peeling of the release liner 30, the ratio of the peeling force F1 to the peeling force F2 (F1 / F2) is preferably 1.1 or more, more preferably 1.2 or more, and even more preferably 1.3 or more. From the viewpoint of ensuring the peelability of the release liner 20 and the release liner 30 from the adhesive sheet 10 in a balanced manner, the ratio (F1 / F2) is preferably 100 or less, more preferably 60 or less, and even more preferably 40 or less.

[0055] In this embodiment, the base polymer in the adhesive sheet 10 is a polymer obtained by photopolymerization, comprising a polymerizable component containing a monofunctional monomer and a crosslinking agent. Photopolymerization refers to a polymerization method in which the polymerizable component undergoes a polymerization reaction by irradiation with active energy rays such as ultraviolet light. The base polymer is, for example, a polymer obtained by photopolymerization of a monofunctional monomer (a mixture of a polymer of monofunctional monomers and unreacted monofunctional monomers) and a polymer obtained by photopolymerization of a crosslinking agent.

[0056] Such a base polymer includes a photopolymer having a photocrosslinked structure (first photopolymer). The photocrosslinked structure is a structure in which linear structures formed from units derived from monofunctional monomers are crosslinked through units derived from a crosslinking agent. The base polymer may also include a photopolymer without such a photocrosslinked structure (second photopolymer). The second photopolymer is a polymer of monofunctional monomers. Furthermore, the base polymer is preferably an acrylic polymer. The acrylic polymer is a copolymer containing a polymerizable component of alkyl (meth)acrylate in a proportion of 50% by mass or more. "(Meth)acrylate" refers to acrylic acid and / or methacrylic acid.

[0057] The monofunctional monomer is preferably a monofunctional alkyl (meth)acrylate, more preferably an alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms. The alkyl (meth)acrylate may have a straight-chain alkyl group or a branched alkyl group, or it may have a cyclic alkyl group (alicyclic alkyl group).

[0058] Examples of linear or branched alkyl methacrylates include: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, amyl methacrylate, isoamyl methacrylate, neopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, isooctyl methacrylate, and propyl methacrylate. Nonyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, undecyl acrylate, dodecyl acrylate, isotridecyl acrylate, tetradecyl acrylate, isotetradecyl acrylate, pentadecyl acrylate, hexadecyl acrylate, heptadecanyl acrylate, octadecyl acrylate, isooctadecyl acrylate, and nonadecanyl acrylate.

[0059] 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.

[0060] Monofunctional monomers can be used alone or in combination of two or more. The monofunctional monomer is preferably an alkyl acrylate having an alkyl group having 3 to 12 carbon atoms, and more preferably at least one selected from the group consisting of n-butyl acrylate, 2-ethylhexyl acrylate and dodecyl acrylate.

[0061] From the viewpoint of appropriately exhibiting basic properties such as adhesion in the adhesive sheet 10, the proportion of monofunctional monomers in the polymerizable component forming the base polymer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and more preferably 75% by mass or more. This proportion is, for example, 99% by mass or less.

[0062] Polymerizable components may include copolymerizable monomers capable of copolymerizing with monofunctional alkyl (meth)acrylates as monofunctional monomers. Examples of copolymerizable monomers include, for example, monomers containing polar groups. Examples of monomers containing polar groups include hydroxyl-containing monomers, carboxyl-containing monomers, and monomers with nitrogen-containing rings. Monomers containing polar groups help ensure the cohesiveness and other properties of acrylic polymers during modification.

[0063] 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 and 4-hydroxybutyl acrylate.

[0064] From the viewpoint of ensuring cohesiveness in the adhesive sheet 10, the proportion of hydroxyl-containing monomers in the polymerizable component is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. From the viewpoint of adjusting the polarity of the acrylic polymer (which relates to the compatibility of various additive components in the adhesive sheet 10 with the acrylic polymer), this proportion is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0065] 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.

[0066] From the viewpoint of ensuring cohesion in the adhesive sheet 10 and adhesion of the adhesive sheet 10 to the adherend, the proportion of carboxyl-containing monomers in the polymerizable component is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. From the viewpoint of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of acid corrosion to the adherend, this proportion is preferably 20% by mass or less, more preferably 10% by mass or less.

[0067] Examples of monomers having a nitrogen-containing ring include: N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrazine, N-vinylpyrrole, N-vinylimidazolium, N-vinylpyrazole, 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-pyrazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisopyrazole, N-vinylthiazole, N-vinylisothiazole, and acryloylmorpholine. The monomer having a nitrogen-containing ring is preferably at least one selected from the group consisting of N-vinyl-2-pyrrolidone and acryloylmorpholine.

[0068] From the viewpoint of ensuring cohesion in the adhesive sheet and adhesion of the adhesive sheet to the adhered object, the proportion of monomers having nitrogen-containing rings in the polymerizable component is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more. 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 sheet with the acrylic polymer), this proportion is preferably 30% by mass or less, more preferably 20% by mass or less.

[0069] Examples of crosslinking agents include: multifunctional oligomers and multifunctional monomers.

[0070] Examples of multifunctional oligomers include: urethane acrylate oligomers (oligomers having a urethane backbone and two or more acryloyl groups), epoxy acrylate oligomers (oligomers having an epoxy backbone and two or more acryloyl groups), and polysiloxane acrylate oligomers (oligomers having a siloxane backbone and two or more acryloyl groups). Commercially available urethane acrylate oligomers include, for example, Art Resin UN-333, UN-350, UN-353, UN-5500, and UN-5590 manufactured by Nekami Industries.

[0071] From the viewpoint of appropriately adjusting the gel fraction of the adhesive sheet 10, the weight-average molecular weight (Mw) of the multifunctional oligomer is preferably 5000 or more, and more preferably 20000 or less, and even more preferably 15000 or less. The weight-average molecular weight is determined by gel permeation chromatography (GPC) and calculated by conversion to polystyrene.

[0072] Examples of multifunctional monomers include polyfunctional (meth)acrylates containing two or more olefinic unsaturated double bonds in one molecule. From the viewpoint of easily introducing cross-linked structures via photopolymerization (active energy beam polymerization), polyfunctional (meth)acrylates are preferred as multifunctional monomers. Examples of polyfunctional (meth)acrylates, specifically those relating to photopolymerizable multifunctional compounds, will be discussed later.

[0073] The crosslinking agent can be used alone or in combination of two or more. The crosslinking agent is preferably a multifunctional oligomer, more preferably a urethane acrylate oligomer.

[0074] The proportion of the crosslinking agent in the polymerizable component is preferably 0.1% by mass or more, more preferably 0.3% by mass or more, even more preferably 0.5% by mass or more, and even more preferably 0.7% by mass or more. This configuration is preferred for maintaining the sheet shape of the adhesive sheet 10 before photocuring, and therefore is preferred for ensuring the operability of the adhesive sheet 10. The proportion of the crosslinking agent in the polymerizable component is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less, and even more preferably 1% by mass or less. This configuration is preferred for ensuring high flexibility in the adhesive sheet 10 before photocuring, thereby achieving good height difference tracking. In addition, this configuration is preferred for suppressing accidental peeling of the heavy peeling liner during the peeling of the light peeling liner.

[0075] Examples of photopolymerizable multifunctional compounds include, for example, multifunctional monomers and multifunctional oligomers.

[0076] Examples of multifunctional monomers include: multifunctional (meth)acrylates. Examples of multifunctional (meth)acrylates include: difunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional or higher multifunctional (meth)acrylates.

[0077] Examples of difunctional (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, neopentyl glycol dimethacrylate, stearic acid-modified pentaerythritol dimethacrylate, dihydrodicyclopentadienyl diacrylate, di(meth)acryloyl isocyanurate, and ethoxylated bisphenol A diacrylate (BPAEODE).

[0078] Examples of trifunctional (meth)acrylates include: trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tri(acryloyloxyethyl) isocyanurate.

[0079] 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 pentaacrylate, and dipentaerythritol hexa(meth)acrylate.

[0080] As a multifunctional oligomer, examples of multifunctional oligomers with crosslinking agents mentioned above can be cited.

[0081] Photopolymerizable polyfunctional compounds can be used alone or in combination of two or more.

[0082] From the viewpoint of adjusting the peel distance d to 200 μm to 900 μm, the photopolymerizable polyfunctional compound preferably includes a photopolymerizable polyfunctional compound having an aromatic ring (first photopolymerizable polyfunctional compound), and more preferably includes a first photopolymerizable polyfunctional compound and a photopolymerizable polyfunctional compound without an aromatic ring (second photopolymerizable polyfunctional compound). The first photopolymerizable polyfunctional compound has an aromatic ring within its molecular structure, thus restricting the molecular motion of the compound itself. Furthermore, the compound may π-conjugate with each other. It is speculated that such a first photopolymerizable polyfunctional compound tends to have high viscosity, thus imparting less plasticity to the adhesive sheet 10, thereby helping to prevent the peel distance d from becoming excessively large.

[0083] The first photopolymerizable polyfunctional compound is preferably a polyfunctional monomer having an aromatic ring, more preferably BPAEODE. From the viewpoint of adjusting the above-mentioned exfoliation distance d to 200 μm to 900 μm, the molecular weight of the first photopolymerizable polyfunctional compound is preferably 1000 or less, more preferably 700 or less, even more preferably 500 or less, and preferably 300 or more, more preferably 400 or more, and even more preferably 450 or more.

[0084] The second photopolymerizable polyfunctional compound is preferably a polyfunctional monomer without an aromatic ring, more preferably trimethylolpropane triacrylate (TMPTA). From the viewpoint of adjusting the above-mentioned peeling distance d to 200 μm to 900 μm, the molecular weight of the second photopolymerizable polyfunctional compound is preferably 1000 or less, more preferably 700 or less, even more preferably 500 or less, and preferably 200 or more, more preferably 250 or more, and even more preferably 280 or more.

[0085] From the viewpoint of ensuring good bonding reliability after photocuring in the adhesive sheet 10, the content of the photopolymerizable polyfunctional compound in the adhesive sheet 10 (the total content when the adhesive sheet 10 contains multiple photopolymerizable polyfunctional compounds) is preferably 1.2 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 2.5 parts by mass or more, relative to 100 parts by mass of the base polymer. From the viewpoint of adjusting the peel distance d to 200 μm to 900 μm, the content of the photopolymerizable polyfunctional compound in the adhesive sheet 10 is preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3.5 parts by mass or less, relative to 100 parts by mass of the base polymer. From the viewpoint of ensuring good bonding reliability after photocuring in the adhesive sheet 10, the content of the first photopolymerizable polyfunctional compound in the adhesive sheet 10 is preferably 0.2 parts by mass or more, more preferably 0.4 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the base polymer. From the viewpoint of adjusting the peel distance d to 200 μm to 900 μm, the content of the first photopolymerizable polyfunctional compound in the adhesive sheet 10 is preferably 2 parts by mass or less, more preferably 1.5 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of the base polymer. From the viewpoint of ensuring good bonding reliability after photocuring in the adhesive sheet 10, the content of the second photopolymerizable polyfunctional compound in the adhesive sheet 10 is preferably 1 part by mass or more, more preferably 1.6 parts by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the base polymer. From the viewpoint of adjusting the peel distance d to 200 μm to 900 μm, the content of the second photopolymerizable polyfunctional compound in the adhesive sheet 10 is preferably 5 parts by mass or less, more preferably 3.5 parts by mass or less, and even more preferably 2 parts by mass or less, relative to 100 parts by mass of the base polymer.

[0086] Examples of photopolymerization initiators used in the adhesive sheet 10 include: free radical photopolymerization initiators, cationic photopolymerization initiators, and anionic photopolymerization initiators.

[0087] 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, ketal photopolymerization initiators, and thioxanone photopolymerization initiators.

[0088] 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 polymerization 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 benzoyldimethyl ketal. Examples of photopolymerization initiators for thioxanthone include: thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone. The photopolymerization initiator can be used alone or in combination of two or more. Preferably, the photopolymerization initiator is an acylphosphine oxide photopolymerization initiator, more 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.

[0089] The content of photopolymerization initiator in the adhesive sheet 10 is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, even more preferably 0.25 parts by mass or more, even more preferably 0.3 parts by mass or more, and even more preferably 0.4 parts by mass or more, relative to 100 parts by mass of the base polymer. This configuration is preferred for forming a crosslinked network with sufficient crosslinking density within the adhesive sheet 10 through photopolymerization reaction when the adhesive sheet 10 is irradiated with light, thereby significantly changing the viscoelasticity of the adhesive sheet 10. The content of photopolymerization initiator in the adhesive sheet 10 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 base polymer. This configuration is preferred for suppressing the excessive generation of polymerization initiator when the adhesive sheet 10 is irradiated with light and forming a long-distance and continuous crosslinked network through photopolymerization reaction.

[0090] The adhesive sheet 10 may contain other components. Examples of such other components include: ultraviolet absorbers, antioxidants, silane coupling agents, and rust inhibitors.

[0091] Examples of UV absorbers include triazine UV absorbers, benzotriazole UV absorbers, benzophenone UV absorbers, salicylate UV absorbers, and cyanoacrylate UV absorbers. Considering their high absorption of UV light in the 320nm–370nm wavelength range and excellent compatibility with acrylic polymers, triazine UV absorbers are preferred. UV absorbers can be used alone or in combination of two or more.

[0092] Commercially available triazine-based UV absorbers include, for example: bis(ethylhexyloxyphenol)methoxyphenyltriazine (product name "Tinosorb S", manufactured by BASF), the reaction product of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(alkoxy)methyl]ethylene oxide (product name "TINUVIN 400", manufactured by BASF), the reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine with (2-ethylhexyl)-glycidyl ester (product name "TINUVIN 405", manufactured by BASF), and (2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine) (product name "TINUVIN"). 460, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol (product name "TINUVIN 577", manufactured by BASF), 2-(2-hydroxy-4-[1-octoxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (product name "TINUVIN 479", manufactured by BASF) and 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol ("ADK STAB LA-46", manufactured by ADEKA).

[0093] Relative to 100 parts by weight of the base polymer, the content of the ultraviolet absorber in the adhesive sheet 10 is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 3 parts by weight or less, more preferably 2 parts by weight or less. This configuration is preferred from the viewpoint of balancing the ultraviolet blocking function of the adhesive sheet 10 for protecting devices with its photocurability.

[0094] Examples of antioxidants include phenolic antioxidants, phosphorus-containing antioxidants, sulfur-containing antioxidants, and amine antioxidants. Antioxidants can be used alone or in combination of two or more.

[0095] Phenolic antioxidants are preferred as antioxidants, and hindered phenolic antioxidants are more preferred. Examples of hindered phenolic antioxidants include pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (product name "Irganox 1010", manufactured by BASF) and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (product name "Irganox 1076", manufactured by BASF).

[0096] Relative to 100 parts by weight of the base polymer, the content of antioxidant in the adhesive sheet 10 is preferably 0.05 parts by weight or more, more preferably 0.1 parts by weight or more, and preferably 3 parts by weight or less, more preferably 2 parts by weight or less. This configuration is preferred from the viewpoint of balancing the inhibition of oxidative degradation of the adhesive sheet 10 and its photocurability.

[0097] Examples of silane coupling agents include, for example, silane coupling agents containing epoxy groups. Examples of silane coupling agents containing epoxy groups include, for example, 3-epoxypropoxydialkyldialkoxysilane and 3-epoxypropoxyalkyltrialkoxysilane. Examples of 3-epoxypropoxydialkyldialkoxysilanes include, for example, 3-epoxypropoxypropylmethyldimethoxysilane and 3-epoxypropoxypropylmethyldiethoxysilane. Examples of 3-epoxypropoxyalkyltrialkoxysilanes include, for example, 3-epoxypropoxypropyltrimethoxysilane and 3-epoxypropoxypropyltriethoxysilane. 3-epoxypropoxyalkyltrialkoxysilane is preferred as a silane coupling agent, and more preferably, 3-epoxypropoxypropyltrimethoxysilane. Silane coupling agents can be used alone or in combination of two or more. The content of silane coupling agent in the adhesive sheet 10 is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and preferably 5 parts by mass or less, more preferably 3 parts by mass or less, relative to 100 parts by mass of the base polymer.

[0098] From the viewpoint of ensuring sufficient adhesion to the adhered objects, the thickness of the adhesive sheet 10 is preferably 10 μm or more, more preferably 20 μm or more. From the viewpoint of the operability and ease of cutting of the adhesive sheet 10, the thickness of the adhesive sheet 10 is preferably 500 μm or less, more preferably 400 μm or less, further preferably 300 μm or less, even more preferably 200 μm or less, and even more preferably 150 μm or less.

[0099] The total light transmittance of the adhesive sheet 10 is preferably 90% or more, more preferably 92% or more. This configuration is preferred for ensuring the transparency required for the adhesive sheet 10 used in display panels. The total light transmittance of the adhesive sheet 10 is, for example, 100% or less. The total light transmittance can be measured according to JIS K 7375 (2008).

[0100] From the viewpoint of ensuring the flexibility of the adhesive sheet 10, the shear storage modulus of the adhesive sheet 10 (before photocuring) at 25°C is preferably 1 MPa or less, more preferably 500 kPa or less, even more preferably 300 kPa or less, even more preferably 200 kPa or less, even more preferably 180 kPa or less, and particularly preferably 150 kPa or less. From the viewpoint of ensuring the cohesiveness of the adhesive sheet 10, the shear storage modulus of the adhesive sheet 10 at 25°C is preferably 5 kPa or more, more preferably 10 kPa or more, even more preferably 15 kPa or more, and particularly preferably 20 kPa or more. The shear storage modulus of the adhesive sheet can be measured using a dynamic viscoelasticity measuring device. For example, an "Advanced Rheological Extension System (ARES)" manufactured by Rheometric Scientific can be used as a dynamic viscoelasticity measuring device. In the measurement, the measurement mode is set to shear mode, the measurement temperature range is set to -50°C to 150°C, the heating rate is set to 5°C / min, and the frequency is set to 1 Hz. The method for determining the shear storage modulus is as described in the embodiments below.

[0101] The release liner 20 is, for example, a flexible, transparent resin film. Examples of materials that can be used for the release liner 20 include: polyester resin, polyolefin resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, cellulose resin, and polystyrene resin. Examples of polyester resins include: polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include: polyethylene, polypropylene, and cyclic olefin polymers (COP). From the viewpoint of transparency and strength, polyester resin is preferred as the material for the release liner 20, and PET is more preferred.

[0102] The release surface 21 of the release liner 20 can be treated with a release agent. Examples of release agents include polysiloxane release treatment, long-chain alkyl acrylate release treatment, and fluorinated release treatment. From the viewpoint of ease of adjusting the release force of the self-adhesive sheet 10, polysiloxane release treatment is preferred.

[0103] From the viewpoint of ensuring the protective function of the adhesive sheet 10, the thickness of the release liner 20 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. From the viewpoint of operability, the thickness of the release liner 20 is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less.

[0104] The release liner 30 is a flexible, transparent resin film. Examples of materials that can be used as the release liner 30 include those described above as the material for the release liner 20. From the viewpoint of transparency and strength, polyester resin is preferred as the material for the release liner 30, and PET is more preferred.

[0105] In this embodiment, the release surface 31 of the release liner 30 is treated with a release agent. Examples of release treatments include polysiloxane release treatment, long-chain alkyl acrylate release treatment, and fluorinated release treatment. From the viewpoint of ease of adjusting the release force of the self-adhesive sheet 10, polysiloxane release treatment is preferred. The release treatment of the release liner 30 is performed in such a way that the release force F2 of the release liner 30 is smaller than the release force F1 of the release liner 20.

[0106] From the viewpoint of ensuring the protective function of the adhesive sheet 10, the thickness of the release liner 30 is preferably 5 μm or more, more preferably 10 μm or more, and even more preferably 20 μm or more. From the viewpoint of operability, the thickness of the release liner 30 is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less.

[0107] Optical adhesive sheet X with release liner can be manufactured, for example, by the following operation.

[0108] First, a prepolymer composition is prepared (prepolymer composition preparation step). Specifically, first, a mixture (liquid state) comprising the aforementioned monofunctional monomer for forming the basic polymer and a photopolymerization initiator is prepared. Next, the mixture is irradiated with ultraviolet light, causing a portion of the monofunctional monomer in the mixture to undergo photopolymerization to obtain the prepolymer composition. Examples of light sources for ultraviolet irradiation include: ultraviolet LED lamps, black light lamps, high-pressure mercury lamps, and metal halide lamps. Furthermore, during ultraviolet irradiation, a wavelength cutoff filter can be used as needed to cut off a portion of the wavelength range of light emitted from the light source. During ultraviolet irradiation, the illuminance is, for example, 5 mW / cm². 2 ~200mW / cm 2 The cumulative irradiation intensity is, for example, 100 mW / cm². 2 ~5000mJ / cm 2 Ultraviolet irradiation is preferably continued until the viscosity of the composition reaches about 15 Pa·s to about 25 Pa·s. This viscosity is measured using a Type B viscometer under the conditions of rotor No. 5, rotor speed 10 rpm, and temperature 30°C. The prepolymer composition contains a photopolymer of a monofunctional monomer (the aforementioned second photopolymer) and a monofunctional monomer that has not undergone polymerization (residual monomer). Furthermore, the prepolymer composition does not contain solvents.

[0109] Next, a crosslinking agent, a photopolymerization initiator, and other components as needed are added to the prepolymer composition, thereby preparing an adhesive composition (adhesive composition preparation step). Other components may include, for example, additional monofunctional monomers (additional monomers), antioxidants, silane coupling agents, and rust inhibitors. The adhesive composition is solvent-free and therefore a solvent-free adhesive composition.

[0110] Next, as Figure 4A As shown, a coating film 10A is formed between the release liner 20 and the release liner 30 (coating film formation process). Specifically, firstly, an adhesive composition is applied to the release surface 21 of the release liner 20 to form the coating film 10A. Next, the release surface 31 side of the release liner 30 is adhered to the coating film 10A on the release liner 20. Examples of coating methods for the adhesive composition include: roller coating, licker coating, gravure coating, reverse coating, roller brush coating, spray coating, dip roller coating, doctor blade coating, doctor knife coating, air knife coating, curtain coating, die lip coating, and die-cutting coating.

[0111] Next, as Figure 4B As shown, the coating 10A between the release liner 20 and the release liner 30 ( Figure 4A The substrate is formed by irradiating it with ultraviolet light (substrate adhesive sheet formation process). During ultraviolet irradiation, a photopolymerization reaction occurs in the coating film in a reaction system containing monofunctional monomers (residual monomers, additional monomers) and a crosslinking agent, thereby forming a base polymer.

[0112] Next, as Figure 4C As shown, the release liner 30 is peeled off from the base adhesive sheet 10B (peeling process).

[0113] Next, as Figure 4DAs shown, an additive component is supplied to the base adhesive sheet 10B (additional component supply process). For example, an additive component solution (not shown) containing the additive component and a solvent is applied to the exposed surface of the base adhesive sheet 10B. The additive component contains the aforementioned photopolymerizable multifunctional compound and the aforementioned photopolymerization initiator, and may include additives such as ultraviolet absorbers and antioxidants. Next, the additive component is allowed to penetrate from the surface of the base adhesive sheet 10B into the base adhesive sheet 10B, while the solvent is vaporized by heating as needed. Prior to this process, the base polymer has already formed a cross-linked structure to create the base adhesive sheet 10B. Therefore, due to the vaporization of the solvent in this process, it is difficult (actually not formed) to create an orange peel-like (yuzuhashi) surface on the base adhesive sheet 10B. Furthermore, a photocurable adhesive sheet 10 is formed by the base adhesive sheet 10B and the additive component. Relative to 100 parts by mass of the base polymer, the amount of the photopolymerizable polyfunctional compound added in this process is preferably 1.2 parts by mass or more, more preferably 2 parts by mass or more, even more preferably 2.5 parts by mass or more, and preferably 7 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 3.5 parts by mass or less.

[0114] Next, as Figure 4E As shown, another release liner 30 is attached to the adhesive sheet 10 (attaching process).

[0115] The above operations can be used to manufacture an adhesive sheet 10 whose adhesive surface is covered and protected by release liner 20 and release liner 30. The adhesive sheet 10 formed from a solvent-free adhesive composition is suitable for reducing environmental impact.

[0116] Figures 5A to 5C This illustrates an example of the use of adhesive sheet 10 of optical adhesive sheet X with release liner.

[0117] In this method, firstly, as Figure 5A and Figure 5B As shown, the component 51 is bonded to the protective glass 52 by the adhesive sheet 10. The component 51 is, for example, a pixel panel, polarizing film, or touch panel for a display panel. The protective glass 52 has a first surface 52a on the side of the component 51 and a second surface 52b opposite to the first surface 52a. A printed layer 53 for decoration or light shielding is formed at the end edge of the first surface 52a. The printed layer 53 is provided, for example, along the entire circumference of the end edge of the protective glass 52. There is a height difference (printing height difference) between the surface of the first surface 52a and the surface of the printed layer 53 on the component 51 side of the protective glass 52. These components 51 are bonded to the protective glass 52 by the adhesive sheet 10. Specifically, as described in the first or second method below.

[0118] In the first method, firstly, from the optical adhesive sheet X with a release liner... Figure 1The release liner 30 is peeled off from the adhesive sheet 10. Then, the adhesive sheet 10 exposed through this peeling is attached to the component 51. Figure 5A Next, the release liner 20 is peeled off from the adhesive sheet 10 on component 51. Then, the adhesive sheet 10 exposed through this peeling is adhered to the first surface 52a of the protective glass 52. In the second method, firstly, the optical adhesive sheet X with the release liner is... Figure 1 The release liner 30 is peeled off from the adhesive sheet 10. Then, the adhesive sheet 10 exposed by the peeling is adhered to the first surface 52a of the protective glass 52. Next, the release liner 20 is peeled off from the adhesive sheet 10 on the protective glass 52. Then, the adhesive sheet 10 exposed by the peeling is adhered to the member 51.

[0119] According to the optical adhesive sheet X with a release liner, in either the first or second method, when the release liner 30 (light release liner) is peeled off from the adhesive sheet 10, accidental peeling of the release liner 20 (heavy release liner) from the adhesive sheet 10 can be suppressed. Furthermore, according to the optical adhesive sheet X with a release liner, in either the first or second method, the adhesive sheet 10 is adhered to the surface of the adhered object with a height difference (the first surface 52a of the protective glass 52) in a soft state before photocuring. Therefore, the adhesive sheet 10 of the optical adhesive sheet X with a release liner is suitable for achieving good height difference tracking.

[0120] Next, as Figure 5C As shown, the adhesive sheet 10 between component 51 and protective glass 52 is photocured (photocuring process) by ultraviolet irradiation. Under ultraviolet irradiation, a photopolymerization reaction of a photopolymerizable multifunctional compound occurs in the adhesive sheet 10, thereby forming a photopolymer of the photopolymerizable multifunctional compound. This photopolymerization reaction occurs around the base polymer (a first photopolymerizable polymer and a second photopolymerizable polymer having a photocrosslinking structure), thus the photopolymer of the photopolymerizable multifunctional compound is formed simultaneously with the formation of an interpenetrating polymer network (IPN) structure with the base polymer. This results in highly elastic adhesive sheet 10 and improved bonding strength between component 51 and protective glass 52. Examples of light sources for ultraviolet irradiation include ultraviolet LED lamps, black light lamps, high-pressure mercury lamps, and metal halide lamps. Additionally, a wavelength cutoff filter for blocking a portion of the wavelength range of light emitted from the light source can be used during ultraviolet irradiation. The cumulative irradiation intensity during ultraviolet irradiation is, for example, 50 mJ / cm². 2 ~10000mJ / cm 2 .

[0121] Example

[0122] The present invention will be specifically described below with reference to the embodiments shown. However, the present invention is not limited to the embodiments. In addition, the specific values ​​of the amount (content), physical property value, parameters, etc. described below can be replaced with the upper limit (defined as "less" or "less than") or lower limit (defined as "more than" or "greater than") of the amount (content), physical property value, parameters, etc. corresponding to them described in the above "Specific Embodiments".

[0123] [Example 1]

[0124] <Preparation of Prepolymer Compositions>

[0125] In a flask, 0.07 parts by weight of two first photopolymerization initiators were added to a monomer mixture comprising 78 parts by weight of n-butyl acrylate (BA), 16 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 6 parts by weight of 4-hydroxybutyl acrylate (4HBA). 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 prepolymer composition. As the first photopolymerization initiators, 0.035 parts by weight of "Omnirad 184" (1-hydroxycyclohexylphenyl ketone) manufactured by IGM Resins and 0.035 parts by weight of "Omnirad 651" (2,2-dimethoxy-1,2-diphenylethane-1-one) manufactured by IGM Resins were used. Ultraviolet irradiation continued until the viscosity of the composition reached approximately 20 Pa·s. This 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 a photopolymer (photopolymer P1a) and monomer components that have not undergone polymerization (residual monomers).

[0126] <Preparation of Adhesive Compositions>

[0127] Next, 100 parts by weight of the prepolymer composition, 2 parts by weight of acryloylmorpholine (ACMO) as an additional monomer, 8 parts by weight of 4-hydroxybutyl acrylate (4HBA) as another additional monomer, 0.8 parts by weight of urethane acrylate oligomer (UAO) (product name "Art Resin UN-350 NDTN 001 BA", weight average molecular weight 12500, manufactured by Negami Kogyo Co., Ltd.) as a crosslinking agent, 0.4 parts by weight of the second photopolymerization initiator, 0.5 parts by weight of the antioxidant (product name "Irganox 1010", manufactured by BASF), 0.15 parts by weight of the rust inhibitor (product name "BT-120", benzotriazole, manufactured by Jōhoku Chemical Co., Ltd.), and 0.35 parts by weight of the silane coupling agent (product name "KBM-403", 3-epoxypropoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to obtain the adhesive composition. As the second photopolymerization initiator, "Omnirad 819" (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide) manufactured by IGM Resins was used.

[0128] <Making Basic Adhesive Sheets>

[0129] Next, an adhesive composition was applied to the release-treated surface of a first release liner (product name "DIAFOIL MRV", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation), which serves as a heavy release liner with a release-treated surface on one side, to form a coating film. Then, the release-treated surface of a second release liner (product name "DIAFOIL MRE", thickness 75 μm, manufactured by Mitsubishi Chemical Corporation), which serves as a light release liner with a release-treated surface on one side, was adhered to the coating film on the first release liner. Next, ultraviolet light was irradiated onto the coating film between the release liners from the second release liner side, causing the coating film to photocur and form an adhesive layer with a thickness of 100 μm (UV irradiation process). During UV irradiation, a black light lamp (manufactured by Toshiba) was used as the light source, and the illuminance was set to 6.5 mW / cm². 2 The cumulative irradiation intensity was set to 1500 mJ / cm. 2 In the ultraviolet irradiation process, a photopolymerization reaction is carried out in the coating film in a reaction system containing the aforementioned residual monomer, additional monomer, and crosslinking agent, thereby forming a photopolymer P1b with a photocrosslinked structure. Furthermore, this photopolymerization reaction occurs around the aforementioned photopolymer P1a, thus photopolymer P1b is formed around photopolymer P1a. The adhesive layer formed in this process contains photopolymer P1a and photopolymer P1b as base polymers. Through the above operations, a base adhesive sheet with a release liner (first release liner / base adhesive sheet (100 μm thick) / second release liner) is produced.

[0130] <Preparation of the solution with added components>

[0131] A post-addition component solution was prepared by mixing 1.8 parts by mass of ethoxylated bisphenol A diacrylate (BPAEODE) (product name "ABE-300", molecular weight: 468.0, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) as the first photopolymerizable polyfunctional compound, 5.7 parts by mass of trimethylolpropane triacrylate (TMPTA) (product name "Viscoat#295", molecular weight: 296.3, manufactured by Osaka Organic Chemical Industry Co., Ltd.) as the second photopolymerizable polyfunctional compound, 1.4 parts by mass of the third photopolymerization initiator, 3.5 parts by mass of the ultraviolet absorber (product name "Tinosorb S", manufactured by BASF), and 49.1 parts by mass of ethyl acetate as the solvent. All components in the solution except the solvent were post-addition components. "Omnirad 819" manufactured by IGM Resins was used as the third photopolymerization initiator. The composition of the post-addition component solution is shown in Table 1. In Table 1, the proportions of each component are expressed in parts by mass.

[0132] <Fabrication of Optical Adhesive Sheets>

[0133] The second release liner was peeled off from the aforementioned base adhesive sheet with the release liner, and then a post-addition component solution was coated to a thickness of 20 μm onto the exposed surface of the base adhesive sheet (coating treatment). Coating was performed using an RDS No.10 bar coater manufactured by RDSPECIALTIES. Following this, a drying process was carried out in a desiccator at 110°C for 60 seconds. Through the coating and drying processes, the post-addition components (photopolymerizable multifunctional compound, third photopolymerization initiator, and UV absorber) penetrated into the base adhesive sheet, and the solvent was vaporized. The penetration of the post-addition components into the base adhesive sheet resulted in a photocurable optical adhesive sheet. Relative to 100 parts by mass of the base polymer (the total of 100 parts by mass of the prepolymer composition, additional monomers, and crosslinking agent described above), the amount of BPAEODE added is 0.6 parts by mass, the amount of TMPTA added is 2.0 parts by mass, and the amount of the third photopolymerization initiator (Omnirad 819) added is 0.5 parts by mass (in Table 2, the relative amounts of the photopolymerizable multifunctional compound and the third photopolymerization initiator relative to 100 parts by mass of the base polymer are shown in parentheses attached to the ingredients). Next, on the optical adhesive sheet on the first release liner, the release-treated surface of the third release liner (product name "DIAFOIL MRQ", thickness 50 μm, manufactured by Mitsubishi Chemical Corporation) which serves as a light release liner with a release-treated surface on one side is attached.

[0134] Through the above operations, the optical adhesive sheet with a release liner of Example 1 (first release liner / optical adhesive sheet (100 μm thick) / third release liner) was produced. The optical adhesive sheet is a photocurable optical adhesive sheet containing a base polymer, a photopolymerizable multifunctional compound, and a third photopolymerization initiator.

[0135] [Example 2]

[0136] Except for the following, the optical adhesive sheet with a release liner of Example 2 was made in the same manner as the optical adhesive sheet with a release liner of Example 1.

[0137] In the preparation of the post-addition component solution, the amount of BPAEODE was set to 3.0 parts by mass, and the amount of ethyl acetate was set to 47.9 parts by mass. In the optical adhesive sheet of Example 2, relative to 100 parts by mass of the base polymer, the amount of BPAEODE as the first photopolymerizable polyfunctional compound added was 1.0 parts by mass, the amount of TMPTA as the second photopolymerizable polyfunctional compound added was 2.0 parts by mass, and the amount of the third photopolymerization initiator (Omnirad 819) added was 0.5 parts by mass (shown in Table 2).

[0138] [Example 3]

[0139] Except for the following, the optical adhesive sheet with a release liner of Example 3 was made in the same manner as the optical adhesive sheet with a release liner of Example 1.

[0140] In the preparation of the post-addition component solution, the amount of the third photopolymerization initiator (Omnirad 819) added was set to 1.8 parts by mass, and the amount of ethyl acetate added was set to 49.1 parts by mass. In the optical adhesive sheet of Example 3, relative to 100 parts by mass of the base polymer, the amount of BPAEODE, as the first photopolymerizable polyfunctional compound, added was 0.6 parts by mass, the amount of TMPTA, as the second photopolymerizable polyfunctional compound, added was 2.0 parts by mass, and the amount of the third photopolymerization initiator (Omnirad 819) added was 1.0 parts by mass (shown in Table 2).

[0141] [Comparative Example 1]

[0142] Except for the following, the optical adhesive sheet with release liner of Comparative Example 1 was made in the same manner as the optical adhesive sheet with release liner of Example 1.

[0143] In the preparation of the adhesive composition, the amount of crosslinking agent (UAO) was set to 1.2 parts by mass. In the preparation of the post-addition component solution, BPAEODE was not added, the amount of TMPTA (photopolymerizable polyfunctional compound) was set to 16.1 parts by mass, the amount of the third photopolymerization initiator (Omnirad 819) was set to 0.68 parts by mass, and the amount of ethyl acetate was set to 39.7 parts by mass. In the optical adhesive sheet of Comparative Example 1, the amount of photopolymerizable polyfunctional compound (TMPTA) added was 5.6 parts by mass relative to 100 parts by mass of the base polymer, and the amount of the third photopolymerization initiator (Omnirad 819) added was 0.24 parts by mass (shown in Table 2).

[0144] [Comparative Example 2]

[0145] Except for the following, the optical adhesive sheet with release liner of Comparative Example 2 was made in the same manner as the optical adhesive sheet with release liner of Example 1.

[0146] In the preparation of the adhesive composition, the amount of crosslinking agent (UAO) was set to 1.2 parts by mass. In the preparation of the post-addition component solution, BPAEODE was not added, the amount of TMPTA (photopolymerizable polyfunctional compound) was set to 16.1 parts by mass, and the amount of ethyl acetate was set to 39.0 parts by mass. In the optical adhesive sheet of Comparative Example 2, the amount of photopolymerizable polyfunctional compound (TMPTA) added was 5.6 parts by mass relative to 100 parts by mass of the base polymer, and the amount of the third photopolymerization initiator (Omnirad 819) added was 0.5 parts by mass (shown in Table 2).

[0147] Total transmittance

[0148] For each optical adhesive sheet in Examples 1 to 3 and Comparative Examples 1 and 2, the total transmittance was measured by the following operation.

[0149] First, a sample for measurement was prepared. Specifically, the third release liner was peeled off from the optical adhesive sheet, and then the exposed surface of the optical adhesive sheet was adhered to alkali-free glass (manufactured by Matsunami Glass Co., Ltd.). The first release liner was then peeled off from the optical adhesive sheet on the glass. This yielded the sample for measurement. Next, the total transmittance of this sample was measured according to JIS K7136 (2000) using a haze meter "HM-150N" manufactured by Murakami Color Technology Research Institute Co., Ltd. Furthermore, in this measurement, the results obtained by measuring only the alkali-free glass under the same conditions were used as a baseline. The total transmittance (%) of each optical adhesive sheet is shown in Table 2.

[0150] <Gel fraction>

[0151] The gel fraction of each optical adhesive sheet in Examples 1 to 3 and Comparative Examples 1 and 2 was measured. Specifically, it is described below.

[0152] First, approximately 1 g of adhesive sample was collected from the optical adhesive sheet. Next, the mass of the adhesive sample (W1) was measured. Then, the adhesive sample was immersed in 40 g of ethyl acetate in a container for 7 days. Next, all components insoluble in ethyl acetate (the undissolved portion) were recovered. Next, the undissolved portion was dried at 130°C for 2 hours (to remove ethyl acetate). Next, the mass of the undissolved portion (W2) was measured. Then, the gel fraction G (mass %) of the photocured optical adhesive sheet was calculated based on the following formula. Its value is shown in Table 2. For each optical adhesive sheet (with photocurability) in Examples 1 to 3 and Comparative Examples 1 and 2, the gel fraction G shown in Table 2 is the gel fraction of the optical adhesive sheet before photocuring.

[0153] Gel fraction (mass%) = (W2 / W1) × 100

[0154] <Shear storage modulus>

[0155] Dynamic viscoelasticity was measured for each optical adhesive sheet in Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, it is described below.

[0156] First, a necessary number of test samples were prepared for each optical adhesive sheet. Specifically, 20 optical adhesive sheets cut from the original sheet were first glued together to create a sample sheet approximately 2 mm thick. Next, this sheet was punched to obtain cylindrical particles (7.9 mm in diameter) that would serve as the test samples.

[0157] Then, regarding the samples used for testing, a dynamic viscoelasticity measuring apparatus (product name "Advanced Rheological Expansion System (ARES)", manufactured by Rheometric Scientific) was used, fixed to a clamp on a parallel plate with a diameter of 7.9 mm, and dynamic viscoelasticity measurements were performed. 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 1Hz. The shear storage modulus (MPa) at 25°C was read from the measurement results. The values ​​are shown in Table 2. For each optical adhesive sheet (with photocurability) in Examples 1 to 3 and Comparative Examples 1 and 2, the shear storage modulus shown in Table 2 is the shear storage modulus of the optical adhesive sheet before photocuring.

[0158] <Peeling force of the peeling liner>

[0159] For each optical adhesive sheet with a release liner in Examples 1 to 3 and Comparative Examples 1 and 2, the peeling force for peeling the release liner from the optical adhesive sheet was measured (first measurement).

[0160] In the preparation of the test piece for the first determination, firstly, a sample piece (100 mm in length × 25 mm in width) is cut from the optical adhesive sheet with a release liner. Next, a third release liner (light release liner) is peeled off from the sample piece, and the exposed surface of the optical adhesive sheet is then attached to a glass plate to obtain the test piece.

[0161] Next, the test piece was left to stand at 25°C for 60 minutes, and then a peel test was performed to peel the first peel pad (heavy peel pad) from the adhesive sheet. The force required for peeling was measured as the peel force. In this test, a tensile testing machine (product name "Autograph AG-50NX plus"), manufactured by Shimadzu Corporation, was used. The test temperature was set to 25°C, the peel angle was set to 180°, and the pulling speed was set to 300 mm / min (the same was true in the second test described later). The measured peel force F1 (N / 25mm) is shown in Table 2.

[0162] On the other hand, for each optical adhesive sheet with a release liner in Examples 1 to 3 and Comparative Examples 1 and 2, the peeling force for peeling the light release liner from the optical adhesive sheet was measured (second measurement).

[0163] In the preparation of the test piece for the second determination, firstly, a sample piece (100 mm in length × 25 mm in width) is cut from an optical adhesive sheet with a release liner. Then, the first release liner (re-release liner) side of the sample piece is bonded to the glass plate using double-sided strong adhesive tape, thus obtaining the test piece.

[0164] Next, the test piece was left to stand at 25°C for 60 minutes, and then a peel test was performed to peel the third release liner (light release liner) from the adhesive sheet. The force required for peeling was measured as the peel force. The measured peel force F2 (N / 25mm) is shown in Table 2. The difference between peel force F1 and peel force F2, F1-F2 (N / 25mm), and the ratio of peel force F1 to peel force F2 (F1 / F2) are also shown in Table 2.

[0165] <Probe Adhesion Test>

[0166] For each optical adhesive sheet with a release liner in Examples 1 to 3 and Comparative Examples 1 and 2, a probe adhesion test was performed by the following procedure.

[0167] First, a 20mm × 40mm optical adhesive sheet with a release liner was cut from the adhesive sheet to serve as a test piece. Next, the test piece was placed on the measuring table of an adhesiveness testing machine (product name "TAC-1000", manufactured by Rhesca). Specifically, the first release liner side of the test piece was adhered to the measuring table using a specified strong adhesive. Then, the third release liner was peeled from the optical adhesive sheet in the test piece, exposing one side (the second side) of the optical adhesive sheet. A probe adhesion test was then performed using this testing machine.

[0168] In the probe adhesion test, a cylindrical stainless steel probe with a tip diameter (probe diameter) of 2.5 mm was used as the probe for pressing onto the optical adhesive sheet. The tip area of ​​this probe was 19.63 mm². 2 In this experiment, the ambient temperature and probe temperature were set to 25°C, the pressing speed was set to 0.08 mm / s, the pressing load was set to 1000 gf, the pressing time was set to 30 seconds, and the peeling speed was set to 0.08 mm / s. Specifically, in this experiment, firstly, the tip of the probe (2.5 mm in diameter) was pressed vertically onto the optical adhesive sheet from above at a pressing speed of 0.08 mm / s until the pressing load reached 1000 gf. Then, the pressing load of 1000 gf was maintained for 30 seconds. Next, the probe was peeled upwards from the optical adhesive sheet at a peeling speed of 0.08 mm / s (peeling process). During this period, the load acting on the probe was measured as the stress on the optical adhesive sheet.

[0169] The measurement results of Examples 1 to 3 and Comparative Example 1 are shown below. Figures 6 to 9 middle. Figure 6 The stress-peel distance curve is shown by a probe adhesion test obtained for the optical adhesive sheet with a release liner in Example 1. Figure 6 In the curve graph, the horizontal axis represents the probe peeling distance (μm), and the vertical axis represents the stress (gf). Figures 7-9 The same applies to the curve graph. The probe peeling distance refers to the rising distance of the probe tip surface during the probe peeling process (the distance moved in the height direction from the position of the second surface of the optical adhesive sheet at the start of peeling). Figure 7 The stress-peel distance curve of the optical adhesive sheet with a release liner in Example 2 is shown by a probe adhesion test. Figure 8 The stress-peel distance curve of the optical adhesive sheet with a release liner in Example 3 is shown by a probe adhesion test. Figure 9The stress-peel distance curves obtained by probe adhesion tests for the optical adhesive sheet with release liner of Comparative Example 1 are shown. Table 2 shows the probe peel distance d (μm) when the stress becomes 0gf during the probe peeling process for each optical adhesive sheet with release liner of Examples 1 to 3 and Comparative Examples 1 and 2.

[0170] <Peeling inhibition of heavy peeling liner during light peeling>

[0171] For the optical adhesive sheets of each release liner in Examples 1 to 3 and Comparative Examples 1 and 2, the ease of peeling off the heavy release liner during the peeling off of the light release liner was investigated.

[0172] Specifically, firstly, 10 evaluation samples were prepared for each optical adhesive sheet with a release liner. Next, the evaluation samples were fixed on a designated stage. Specifically, the first release liner (heavy release liner) side of the evaluation sample was fixed to the stage using double-sided adhesive tape (product name "TESA 68547", manufactured by TESA). Then, the end of the third release liner (light release liner) of the evaluation sample on the stage was pinched with fingertips and the third release liner was peeled off. During peeling, the peeling angle was set to approximately 45°, and the pulling speed was set to approximately 300 mm / min. Then, regarding the peeling suppression of the first release liner (heavy release liner) during the peeling of the third release liner (light release liner), the case where 10 evaluation samples did not peel off the first release liner but only the third release liner was properly peeled off was evaluated as "A", the case where 7 to 9 samples were evaluated as "B", and the case where 0 to 6 samples were evaluated as "C". The evaluation results are shown in Table 2.

[0173] <Elevation Difference Following Test>

[0174] The height difference tracking of each optical adhesive sheet in Examples 1 to 3 and Comparative Examples 1 and 2 was investigated as follows.

[0175] First, a second sample sheet (75mm × 45mm) is cut from the optical adhesive sheet with a release liner. Next, a third release liner (light release liner) is peeled from the optical adhesive sheet in the second sample sheet, and the exposed surface of the optical adhesive sheet is bonded to the center of a PET film (125μm thick, 100mm × 50mm). During bonding, a roller press is used, with the roller pressure set to 0.2MPa and the feed speed set to 100mm / min (the same applies to the bonding process described later). Next, a first release liner (heavy release liner) is peeled from the optical adhesive sheet on the PET film, and the exposed surface of the optical adhesive sheet is bonded to a glass plate with a printed layer (500μm thick, 100mm long × 50mm wide), thus obtaining a bond. Figure 11 shows the positional relationship between the glass plate 71 and the optical adhesive sheet 72 from the second sample sheet in the bond. A printed layer 73 (45 μm thick, black ink) is formed on one side of the glass plate 71 along its thickness direction, covering the entire circumference of the end edge of the glass plate 71. The printed layer 73 is formed in the length direction D1 within a range of 15 mm inward from each end of the glass plate 71, and in the width direction D2 within a range of 5 mm inward from each end of the glass plate 71. An optical adhesive sheet 72 is attached to the center of one side of the glass plate 71 along its thickness direction, contacting the printed layer 73 along the entire circumference of its end edge. That is, the printed layer 73 on the glass plate 71 is sandwiched between the glass plate 71 and the optical adhesive sheet 72 within a range of 2.5 mm outward from the inner end of the layer.

[0176] Next, the bond was subjected to autoclaving at 50°C and 0.5 MPa for 30 minutes. Then, the area near the inner edge of the printed layer in the bond was observed. Specifically, the inner side of the inner edge of the printed layer (the area where the optical adhesive sheet should adhere to the glass plate) was observed from the PET film side of the bond using a digital microscope at 20x magnification. Furthermore, regarding the height difference tracking of the optical adhesive sheet, cases where no bubbles were observed within the observation range were rated as "A", and cases where bubbles were observed were rated as "B". The results are shown in Table 2.

[0177] Table 1

[0178] Table 2

[0179] It should be noted that the above-described invention is provided as an illustrative embodiment of the present invention, but this is merely illustrative and should not be interpreted as limiting. Modifications of the invention that are obvious to those skilled in the art are included within the scope of the claims.

[0180] Industrial practicality

[0181] The adhesive sheet 10 (optical adhesive sheet) of the present invention is suitable for use in light-transmitting portions of a display panel. Examples of display panels include liquid crystal display panels and organic EL display panels.

[0182] Label Explanation

[0183] X Optical adhesive sheet with release liner

[0184] H Thickness direction

[0185] 10. Adhesive sheet (optical adhesive sheet)

[0186] 11 First page

[0187] 12 Second page

[0188] 20. Peel-off gasket (heavy-duty peel-off gasket)

[0189] 21, 31 Peeling surfaces

[0190] 30. Peel-off gasket (light peel-off gasket)

Claims

1. An optical adhesive sheet with a release liner, said optical adhesive sheet having: An optical adhesive sheet having a first side and a second side opposite to the first side; A re-peeling liner, wherein the re-peeling liner is in peelable contact with the first surface; and A light-release liner, wherein the light-release liner is releasably in contact with the second surface, wherein... The optical adhesive sheet comprises a base polymer, a photopolymerizable multifunctional compound, and a photopolymerization initiator. In a probe adhesion test conducted on the second surface after the light release liner has been peeled off from the optical adhesive sheet, under the following conditions, the probe peeling distance when the stress reaches 0 gf during the probe peeling process is 200 μm or more and 900 μm or less. [condition] Temperature: 25℃ Probe diameter: 2.5mm Compressive load: 1000gf Pressing time: 30 seconds Peeling speed: 0.08 mm / second.

2. The optical adhesive sheet with a release liner according to claim 1, wherein, The photopolymerizable polyfunctional compounds include photopolymerizable polyfunctional compounds having aromatic rings.

3. The optical adhesive sheet with a release liner according to claim 1, wherein, The weight-average molecular weight of the photopolymerizable multifunctional compound is below 1000.

4. The optical adhesive sheet with a release liner according to any one of claims 1 to 3, wherein, The optical adhesive sheet with a release liner has a gel fraction of 50% by mass or more.

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