Optical laminate

Abstract

The optical laminate (1) of the present invention comprises a glass plate (2), an adhesive layer (3), and a film (4) in sequence facing one side in the thickness direction. One side in the thickness direction is the viewing side. In the following pen drop crack test, the drop height H1 of the pen until the glass plate (2) begins to crack is 15 cm or more. An adhesive layer (12) having a shear storage modulus (G') of 0.03 MPa and a thickness of 15 μm is placed on the other side in the thickness direction of the optical laminate (1). A pen (29) with a ball of 7 g and a ball diameter of 0.7 mm is dropped toward the film (4). The drop height of the pen is increased stepwise, and the height at which a crack is confirmed in the glass plate (2) is obtained as the height H1 in the pen drop crack test.

Description

Technology Field

[0001] The present invention relates to an optical laminate having a glass plate. Background Technology

[0002] An optical laminate comprising a glass plate, an adhesive layer, and a triacetylcellulose film is known (e.g., see Patent Document 1 below). While the glass plate has excellent optical properties, it has low impact resistance. Impact resistance is a property that suppresses damage, including cracks, in the glass plate when the glass plate is subjected to impact.

[0003] The optical laminate described in Patent Document 1 is provided in an organic EL display. In the optical laminate described in Patent Document 1, the pencil hardness of the glass plate is measured. Pencil hardness is measured by directly contacting the lead of a pencil with the surface (exposed surface) of the glass plate and evaluating the presence or absence of scratches on the surface. Accordingly, when the optical laminate described in Patent Document 1 is provided in an organic EL display, the glass plate is positioned on the viewing side and the triacetylcellulose film is positioned on the organic EL member side. Prior art literature

[0004] Japanese Patent Publication No. 2019-25899 The problem to be solved

[0005] Recently, a higher level of impact resistance is required. means of solving the problem

[0006] Therefore, the inventors of the present invention, after careful examination, discovered a novel optical laminate in which a film is positioned on the viewing side, and found that such an optical laminate has excellent impact resistance.

[0007] The present invention (1) comprises an optical laminate having a glass plate, an adhesive layer, and a film arranged in order toward one side in the thickness direction, wherein the one side in the thickness direction is a visible side, and the drop height H1 of the pen until the glass plate begins to crack in the following pen drop crack test is 15 cm or more.

[0008] Pen Drop Crack Test

[0009] An adhesive layer having a thickness of 15 μm and a shear storage modulus (G') at 25°C obtained by a dynamic viscoelasticity test in torsion mode at a frequency of 1 Hz, a heating rate of 5°C / min, a temperature of -40°C to 150°C, is placed on the other side of the optical laminate in the thickness direction. A pen with a ball of 7 g and a ball diameter of 0.7 mm is dropped toward the film. The drop height of the pen is increased by 1 cm increments, and the height at which a crack is confirmed in the glass plate is obtained as the height H1 in the pen drop crack test.

[0010] The present invention (2) includes an optical laminate described in (1) in which the drop height H2 of the pen until the film begins to peel off in the following pen drop peeling test is 15 cm or more.

[0011] Pen Drop Peel Test

[0012] The adhesive layer is placed on the other side of the optical laminate in the thickness direction. A pen with a ball of 7g and a ball diameter of 0.7mm is dropped toward the film. The drop height of the pen is gradually increased up to 30cm, and the height H2 in the pen drop peel test is obtained when peeling is confirmed on the film. Alternatively, if a crack occurs in the glass plate, it is determined that it has peel resistance of crack height H1 or higher.

[0013] The present invention (3) includes an optical laminate described in (1) or (2), wherein the average tanδ of the film from -100°C to -50°C obtained by a dynamic viscoelasticity test in a tensile mode with a frequency of 10 Hz and a heating rate of 2°C / min is 0.04 or higher, and the average tensile storage modulus (E') of the film from -100°C to -50°C obtained by the dynamic viscoelasticity test is 3 GPa or higher and 6 GPa or lower.

[0014] The present invention (4) includes an optical laminate described in any one of claims (1) to (3), wherein the adhesion force between the glass plate and the adhesive layer is 3.0 kN / m or more, and the adhesion force between the film and the adhesive layer is 3.0 kN / m or more.

[0015] The present invention (5) includes an optical laminate described in any one of claims (1) to (4), wherein the film is a triacetylcellulose film.

[0016] The present invention (6) includes an optical laminate described in (5), wherein the film has a thickness of 10 μm or more and 60 μm or less.

[0017] The present invention (7) includes an optical laminate described in any one of claims (1) to (6), which further comprises a hard coat layer disposed on one side of the thickness direction of the film. Effects of the invention

[0018] The optical laminate of the present invention has excellent impact resistance because the film is positioned on the viewing side and the drop height H1 of the pen until the glass plate begins to crack in the pen drop crack test is 15 cm or more. Brief explanation of the drawing

[0019] FIG. 1 is a cross-sectional view of one embodiment of the optical laminate of the present invention. FIGS. 2A to FIGS. 2C are explanatory diagrams of a method for measuring adhesion force. FIG. 2A is an embodiment in which the cutting edge of the device is cut into a film. FIG. 2B is an embodiment in which the cutting edge reaches the interface between the film and the adhesive layer and measures their adhesion force. FIG. 2C is an embodiment in which the cutting edge reaches the interface between the glass plate and the adhesive layer and measures their adhesion force. FIG. 3 is a cross-sectional view of an organic electroluminescence display device having an optical laminate shown in FIG. 1. Specific details for implementing the invention

[0020] <Optical laminate (1)>

[0021] One embodiment of the optical laminate of the present invention will be described with reference to FIGS. 1 to 3.

[0022] This optical laminate (1) has a flat shape that extends, for example, in a plane direction. The plane direction is orthogonal to the thickness direction of the optical laminate (1). When the optical laminate (1) is provided in an organic electroluminescence display device (10) (see FIG. 3), it is positioned on the viewing side (hereinafter simply referred to as the viewing side), which is the side that the user sees. The optical laminate (1) is provided with a glass plate (2), an adhesive layer (3), and a film (4) in sequence facing one side in the thickness direction. One side in the thickness direction is the viewing side. The other side in the thickness direction is the opposite side of the viewing side (hereinafter simply referred to as the opposite side).

[0023] Glass plate (2)

[0024] The glass plate (2) extends in the plane direction. The glass plate (2) forms the other side (reverse side) in the thickness direction of the optical laminate (1). The total light transmittance of the glass plate (2) is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less. The glass plate (2) may be a commercially available product, for example, the G-leaf series (registered trademark, manufactured by Nippon Electric Glass Co., Ltd.).

[0025] The thickness of the glass plate (2) is not limited. The thickness of the glass plate (2) is, for example, 1 μm or more, preferably 10 μm or more, more preferably 20 μm. The thickness of the glass plate (2) is 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less.

[0026] <Adhesive layer (3)>

[0027] The adhesive layer (3) extends in the plane direction. The adhesive layer (3) is placed on one side in the thickness direction of the glass plate (2). Specifically, the adhesive layer (3) is in contact with one side in the thickness direction of the glass plate (2). The adhesive layer (3) is not an adhesive layer (pressure-sensitive adhesive layer) containing an adhesive (pressure-sensitive adhesive), but is a cured body of a curable adhesive. In detail, the adhesive layer (3) is a cured body of a curable adhesive that undergoes a curing reaction by irradiation with active energy rays or heating.

[0028] As a curing material for the adhesive layer (3), the curing adhesive may be an active energy curing type and a thermal curing type, and preferably, an active energy curing type. Specifically, as a curing adhesive, examples include an acrylic adhesive composition, an epoxy adhesive composition, and a silicone adhesive composition, and an epoxy adhesive composition may be used in terms of obtaining excellent impact resistance.

[0029] The epoxy adhesive composition comprises an epoxy resin as the main component. Examples of epoxy resins include a difunctional epoxy resin containing two epoxy groups and a polyfunctional epoxy resin containing three or more epoxy groups. These may be used alone or in combination of two or more types.

[0030] Preferably, the combined use of a difunctional epoxy resin and a polyfunctional epoxy resin can be used.

[0031] Examples of difunctional epoxy resins include aromatic epoxy resins such as bisphenol-type epoxy resin, novolak-type epoxy resin, naphthalene-type epoxy resin, fluorene-type epoxy resin, and triphenylmethane-type epoxy resin; nitrogen-containing cyclic epoxy resins such as triepoxypropyl isocyanurate and hydantoin epoxy resin; furthermore, aliphatic epoxy resin, glycidyl ether-type epoxy resin, and glycidylamine-type epoxy resin. Preferably, an aliphatic epoxy resin is used as the difunctional epoxy resin. Aliphatic epoxy resins include aliphatic alicyclic epoxy resins. The epoxy equivalent of the difunctional epoxy resin is, for example, 100 g / eq. or more, preferably 120 g / eq. or more, and also, for example, 250 g / eq. or less, preferably 150 g / eq. or less. The proportion of difunctional epoxy resin in the epoxy resin is, for example, 80 mass% or more, preferably 90 mass% or more, and also, for example, 99 mass% or less, preferably 97 mass% or less.

[0032] Examples of polyfunctional epoxy resins include polyfunctional epoxy resins with three or more functions, such as phenol novolak-type epoxy resin, cresol novolak-type epoxy resin, trihydroxyphenylmethane-type epoxy resin, tetraphenylolethane-type epoxy resin, dicyclopentadiene-type epoxy resin, and trifunctional aliphatic epoxy resin. Preferably, trifunctional aliphatic epoxy resin is used as the polyfunctional epoxy resin. The epoxy equivalent of the polyfunctional epoxy resin is, for example, 130 g / eq. or more, preferably 150 g / eq. or more, and also, for example, 220 g / eq. or less, preferably 200 g / eq. or less. The proportion of the polyfunctional epoxy resin in the epoxy resin is, for example, 1 mass% or more, preferably 3 mass% or more, and also, for example, 20 mass% or less, preferably 10 mass% or less.

[0033] The proportion of epoxy resin in the epoxy adhesive composition is, for example, 60 mass% or more, preferably 75 mass% or more, and also, for example, 90 mass% or less, preferably 80 mass% or less.

[0034] Commercially available epoxy resins can be used, and as an aliphatic alicyclic epoxy resin, Celoxide 2021P (manufactured by Daicel Chemical Co., Ltd.) and as a trifunctional aliphatic epoxy resin, EHPE3150 (manufactured by Daicel Chemical Co., Ltd.) are used.

[0035] In addition, the epoxy adhesive composition includes a photogenerator if it is an active energy curing type. Examples of photogenerators include triarylsulfonium salts. Commercially available photogenerators may be used, and CPI101A (manufactured by San Aprosa) is used as a triarylsulfonium salt. The proportion of the photogenerator in the epoxy adhesive composition is, for example, 1 mass% or more, preferably 10 mass% or more, and also, for example, 30 mass% or less, preferably 20 mass% or less.

[0036] In addition, the epoxy adhesive composition may include additives such as oxetane-based resins and silane coupling agents in appropriate proportions.

[0037] Examples of oxetane-based resins include monofunctional oxetanes such as 3-ethyl-3-oxetane methanol and 2-ethylhexyl oxetane, and difunctional oxetanes such as xylylenebis-oxetane and 3-ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane. Commercially available oxetane-based resins can be used, such as Aron-oxetane (manufactured by Doagosei Co., Ltd.).

[0038] Examples of silane coupling agents include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane. Commercially available silane coupling agents may be used, such as the KBM series (manufactured by Shin-Etsu Silicon Co., Ltd.).

[0039] The thickness of the adhesive layer (3) is not limited. The thickness of the adhesive layer (3) is, for example, 0.1 μm or more, and also, for example, 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less.

[0040] The total light transmittance of the adhesive layer (3) is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less.

[0041] The tensile storage modulus (E') of the adhesive layer (3) at 25°C is, for example, 1 GPa or more, preferably 2 GPa or more, more preferably 3 GPa or more, even more preferably 4 GPa or more, and also, for example, 100 GPa or less. The tensile storage modulus (E') of the adhesive layer (3) at 25°C can be obtained by measuring dynamic viscoelasticity in a temperature dispersion mode under conditions of a frequency of 1 Hz and a heating rate of 5°C / min. In addition, the elastic modulus of the adhesive layer (3) at 25°C measured by the nano-indenter method is, for example, 1 GPa or more, preferably 2 GPa or more, more preferably 3 GPa or more, even more preferably 4 GPa or more, and also, for example, 100 GPa or less. The measurement conditions of the nano-indenter method are as follows.

[0042] Device: Triboindenter (Manufactured by Hysitron Inc.)

[0043] Sample size: 10×10mm

[0044] Indenter: Concial (Spherical indenter: radius of curvature 10㎛),

[0045] Measurement method: Single indentation measurement

[0046] Measured temperature: 25℃

[0047] Indenter indentation depth: 100nm

[0048] Temperature: 25℃

[0049] Analysis: Oliver Pharr analysis based on load-displacement curves

[0050] The adhesion force between the glass plate (2) and the adhesive layer (3) is, for example, 3.0 kN / m or more, preferably 3.5 kN / m or more, more preferably 4.0 kN / m or more, and also, for example, 10 kN / m or less, preferably 8 kN / m or less. If the adhesion force between the glass plate (2) and the adhesive layer (3) is greater than or equal to the lower limit mentioned above, delamination at the interface between the glass plate (2) and the adhesive layer (3) can be suppressed when an object collides with the optical laminate (1). Therefore, the optical laminate (1) has excellent reliability.

[0051] The adhesion force between the glass plate (2) and the adhesive layer (3) can be determined as the peel strength when the blade tip (43) of the blade (42) provided by the device (41) is inserted into the interface between the glass plate (2) and the adhesive layer (3) as shown in Fig. 2C, and the blade (42) is moved along the plane direction to peel the glass plate (2) from the adhesive layer (3). Details of the method for measuring the adhesion force will be described in a later example.

[0052] <Film (4)>

[0053] The film (4) forms one side (visibility side) in the thickness direction of the optical laminate (1). The film (4) is located on the side opposite the glass plate (2) to the adhesive layer (3). The film (4) extends in the plane direction.

[0054] The film (4) is placed on one side of the adhesive layer (3) in the thickness direction. The film (4) is in contact with one side of the adhesive layer (3) in the thickness direction. As a result, the adhesive layer (3) is in contact with one side of the glass plate (2) in the thickness direction and the other side of the film (4) in the thickness direction, thereby bonding (bonding) the glass plate (2) and the film (4).

[0055] The average tanδ of the film (4) from -100°C to -50°C, obtained by dynamic viscoelasticity testing in tensile mode with a frequency of 10 Hz, a heating rate of 2°C / min, and a data acquisition interval of 0.5 min, is, for example, 0.02 or higher, preferably 0.04 or higher, and also, for example, 0.20 or lower, preferably less than 0.06, more preferably 0.05 or lower. If the average tanδ of the film (4) from -100°C to -50°C exceeds the lower limit mentioned above, the impact resistance of the optical laminate (1) can be improved. The average tanδ of the film (4) from -100°C to -50°C is an indicator of responsiveness when an object collides with the optical laminate (1) at high speed. If the average tanδ is high, the film (4) can sufficiently mitigate the impact received by the glass plate (2) even when an object collides with the glass plate (2) at high speed, and the impact resistance of the optical laminate (1) can be improved. Dynamic viscoelasticity testing is described in a later example.

[0056] The average tensile storage modulus (E') of the film (4) from -100°C to -50°C, obtained by a dynamic viscoelasticity test in a tensile mode with a frequency of 10 Hz and a heating rate of 2°C / min, is, for example, 3 GPa or more, preferably 4 GPa or more, and also, for example, 10 GPa or less, preferably 6 GPa or less, more preferably 5 GPa or less, and even more preferably 4.7 GPa or less. If the average tensile storage modulus (E') of the film (4) from -100°C to -50°C is greater than or equal to the lower limit mentioned above, the impact resistance of the optical laminate (1) can be improved.

[0057] The adhesion force between the film (4) and the adhesive layer (3) is, for example, 0.5 kN / m or more, preferably 1.5 kN / m or more, more preferably 3.0 kN / m or more, even more preferably 3.5 kN / m or more, particularly preferably 4.0 kN / m or more, most preferably 5.0 kN / m or more, and also, for example, 10 kN / m or less. If the adhesion force between the film (4) and the adhesive layer (3) is greater than or equal to the lower limit mentioned above, delamination at the interface between the film (4) and the adhesive layer (3) can be suppressed when an object collides with the film (4) of the optical laminate (1). The adhesion force between the film (4) and the adhesive layer (3) can be determined as the peel strength when the tip (43) of the blade (42) provided by the measuring device (41) is inserted into the interface between the film (4) and the adhesive layer (3) as shown in Fig. 2B, and the blade (42) is moved along the plane direction to peel the film (4) from the adhesive layer (3). Details of the method for measuring the adhesion force will be described in a later example.

[0058] Examples of film (4) include polyester film and cellulose film. Examples of polyester film include polyethylene terephthalate film (PET), polybutylene terephthalate (PBT) film and polyethylene naphthalate (PEN) film. Examples of cellulose film include acetylcellulose film, and specifically, triacetylcellulose (TAC) film. As for the film (4), from the perspective of increasing the adhesion of the film (4) to the adhesive layer (3) and suppressing the peeling of the film (4) when an object collides with the optical laminate (1), a cellulose film is preferably used, and more preferably a TAC film is used.

[0059] The thickness of the film (4) is not limited. The thickness of the film (4) is, for example, 10 μm or more, preferably 30 μm or more. If the thickness of the film (4) is greater than the lower limit mentioned above, the impact resistance of the optical laminate (1) can be improved. In addition, the thickness of the film (4) is, for example, 200 μm or less, preferably 100 μm or less, more preferably 60 μm or less. If the thickness of the film (4) is less than the upper limit mentioned above, peeling of the film (4) can be suppressed when an object collides with the optical laminate (1).

[0060] The total light transmittance of the film (4) is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less.

[0061] <Adhesive layer (12)>

[0062] The optical laminate (1) may additionally be provided with an adhesive layer (12) indicated by a virtual line. The adhesive layer (12) is disposed on the other side of the thickness direction of the glass plate (2). Specifically, the adhesive layer (12) is in contact with the other side of the thickness direction of the film (4). That is, the optical laminate (1) is provided with the adhesive layer (12), the glass plate (2), the adhesive layer (3), and the film (4) in sequence facing one side of the thickness direction. The adhesive layer (12) is an adhesive that bonds by pressure without involving a curing reaction.

[0063] The material of the adhesive layer (12) is not limited. Examples of materials for the adhesive layer (12) include acrylic adhesive, rubber adhesive, vinylalkyl ether adhesive, silicone adhesive, polyester adhesive, polyamide adhesive, urethane adhesive, fluorine adhesive, epoxy adhesive, and polyether adhesive. Preferably, acrylic adhesive is used as the material. The formulation and physical properties of the adhesive layer (12) are described in detail, for example, in Japanese Patent Publication No. 2018-28573.

[0064] The shear storage modulus (G') of the adhesive layer (12) at 25°C is, for example, 0.01 MPa or higher, and also, for example, 0.20 MPa or lower. The shear storage modulus (G') can be obtained by a dynamic viscoelasticity test in a shear (torsion) mode with a frequency of 1 Hz, a heating rate of 5°C / min.

[0065] The thickness of the adhesive layer (12) is, for example, 5 μm or more, preferably 10 μm or more, and also, for example, 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less.

[0066] The thickness of the optical laminate (1) is, for example, 25 μm or more, and also, for example, 200 μm or less.

[0067] Pen Drop Crack Test

[0068] In the optical laminate (1), the drop height H1 of the pen until the glass plate (2) begins to crack in the pen drop crack test is, for example, 15 cm or more.

[0069] First, a resin film (34) representing the optical laminate (1) as a virtual line is placed on the surface of a horizontal bar (not shown). An adhesive layer (12) with a thickness of 15 μm is placed on one side of the optical laminate (1) in the thickness direction. Additionally, this adhesive layer (12) serves as a fixing member for fixing the optical laminate (1) to the horizontal bar in a pen drop crack test. The shear storage modulus (G') at 25°C, obtained by a dynamic viscoelasticity test in a torsional mode with a frequency of 1 Hz, a heating rate of 5°C / min, and a temperature of -40°C to 150°C, is 0.03 MPa.

[0070] As shown in FIG. 1, a pen (29) (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped toward the film (4). The mass of the pen (29) is 7 g. The height from the glass plate (2) to the tip (32) of the pen (29) is 5 cm. The tip (32) is pointed downward. If no crack occurs in the glass plate (2) during the above-mentioned drop of the pen (29), the height is increased step by step by 1 cm. The height at which a crack is confirmed in the glass plate (2) is obtained as the height H1 in the pen drop crack test.

[0071] If the drop height H1 in the pen drop crack test is 15 cm or more, the impact resistance of the optical laminate (1) is excellent.

[0072] The drop height H1 in the pen drop crack test is preferably 20 cm or more.

[0073] Pen Drop Peel Test

[0074] In the optical laminate (1), the drop height H2 of the pen (29) until the film (4) begins to peel off in the pen drop peeling test is, for example, 15 cm or more.

[0075] First, a resin film (34) representing the optical laminate (1) as a virtual line is placed on the surface of a horizontal bar (not shown). An adhesive layer (12) identical to the adhesive layer (12) used in the pen drop crack test is placed on one side of the optical laminate (1) in the thickness direction.

[0076] As shown in FIG. 1, a pen (29) (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped toward the film (4). The mass of the pen (29) is 7 g. The height from the glass plate (2) to the tip (32) of the pen (29) is 5 cm. The tip (32) is pointed downwards. During the above-mentioned drop of the pen (29), if no peeling occurs from the adhesive layer (3) of the film (4), the height is increased step by step by 1 cm. The height at which peeling from the adhesive layer (3) of the film (4) is confirmed is obtained as the height H2 in the pen drop peeling test. Alternatively, if a crack occurs in the glass plate (2), it is determined that it has peeling durability greater than or equal to the crack height H1.

[0077] Preferably, the drop height H2 in the pen drop peel test is 20 cm or more.

[0078] The optical laminate (1) satisfying the above requirements has high adhesion to the adhesive layer (3) of the film (4). Therefore, the optical laminate (1) has excellent reliability.

[0079] <Method for manufacturing an optical laminate (1)>

[0080] A method for manufacturing an optical laminate (1) is described. In the method for manufacturing an optical laminate (1), for example, first, a curable adhesive is placed (applied) on one side in the thickness direction of a glass plate (2) and / or on the other side in the thickness direction of a film (4), and then the curable adhesive is inserted between the glass plate (2) and the film (4).

[0081] Afterward, the curable adhesive is cured. If the curable adhesive is an active energy curable type, active energy including ultraviolet rays is irradiated onto the curable adhesive. Specifically, ultraviolet rays are irradiated onto the curable adhesive from the side of the glass plate (2). If the curable adhesive is a heat-curable type, the curable adhesive is heated. This forms an adhesive layer (3) that firmly bonds the glass plate (2) and the film (4).

[0082] As a result, an optical laminate (1) having a glass plate (2), an adhesive layer (3), and a film (4) is obtained.

[0083] After that, in order to additionally provide an adhesive layer (12) in the optical laminate (1), the adhesive layer (12) is placed on the other side of the glass plate (2) in the thickness direction. For example, a varnish containing an adhesive is applied and dried on the other side of the glass plate (2) in the thickness direction. Alternatively, an adhesive layer (12) formed on a release sheet not shown may be transferred to the other side of the glass plate (2) in the thickness direction. As a result, an optical laminate (1) having an adhesive layer (12), a glass plate (2), an adhesive layer (3), and a film (4) is obtained. Additionally, a release sheet not shown may be provided in the optical laminate (1). In that case, the optical laminate (1) has a release sheet not shown, an adhesive layer (12), a glass plate (2), an adhesive layer (3), and a film (4).

[0084] <Uses of optical laminate (1)>

[0085] The optical laminate (1) is used for various optical purposes and is provided in, for example, an image display device. An example of an image display device is an organic electroluminescence display device (hereinafter simply abbreviated as 'organic EL display device').

[0086] Next, an organic EL display device (10) equipped with an optical laminate (1) will be described with reference to FIG. 3.

[0087] <Organic EL display device (10)>

[0088] The organic EL display device (10) has a flat plate shape extending in the plane direction. The organic EL display device (10) functions as a touch panel type input display device in that it is equipped with a conductive film (13) to be described next. The organic EL display device (10) is equipped with an optical laminate (1), a conductive film (13), a second adhesive layer (14), and an image display member (15) in order toward the back side. In addition, in this organic EL display device (10), the upper side of the paper surface is the user's viewing side and is the front side (corresponding to the other side in the thickness direction of FIG. 1), and the lower side of the paper surface is the back side (corresponding to one side in the thickness direction of FIG. 1).

[0089] <Optical laminate (1)>

[0090] The optical laminate (1) comprises an adhesive layer (12), a glass plate (2), an adhesive layer (3), and a film (4) in order facing outward.

[0091] <Challenging Film (13)>

[0092] The conductive film (13) is provided with a conductive layer (16) and a substrate layer (17) in order facing this side.

[0093] <Challenge Layer (16)>

[0094] The conductive layer (16) has a predetermined pattern. The surface and side of the conductive layer (16) are in contact with the adhesive layer (12). Examples of materials for the conductive layer (16) include metal oxides, conductive fibers (fibers), and metals. Examples of metal oxides include composite oxides. Examples of composite oxides include indium zinc composite oxide (IZO), indium gallium zinc composite oxide (IGZO), indium gallium composite oxide (IGO), indium tin composite oxide (ITO), and antimony tin composite oxide (ATO). Examples of conductive fibers include metal nanowires and carbon nanotubes. Examples of metals include gold, platinum, silver, and copper. The conductive layer (16) integrally includes a sensor electrode portion (18) located in the center of the plane direction and an lead wiring portion (19) located around the sensor electrode portion (18). Details of the conductive layer (16) are described, for example, in Japanese Published Patent Application No. 2017-102443, Japanese Published Patent Application No. 2014-113705 and Japanese Published Patent Application No. 2014-219667.

[0095] <Layer (17)>

[0096] The substrate layer (17) is disposed on the back side of the conductive layer (16) and on the back side of the adhesive layer (12). The substrate layer (17) extends in the plane direction. The substrate layer (17) is, for example, a resin layer. Examples of materials for the substrate layer (17) include olefin resin, polyester resin, (meth)acrylic resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Examples of olefin resins include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of polyester resins include PET, PBT, and PEN. Examples of (meth)acrylic resins include poly(meth)acrylate resin. Details of the substrate layer (17) are described, for example, in Japanese Patent Publication No. 2018-181722.

[0097] <Second adhesive layer (14)>

[0098] The second adhesive layer (14) is disposed on the back side of the conductive film (13). Specifically, the second adhesive layer (14) is in contact with the back side of the conductive film (13). The material of the second adhesive layer (14) is the same as the material of the adhesive layer (12).

[0099] <Image display component (15)>

[0100] The image display member (15) forms the back surface of the organic EL display device (10). The image display member (15) is disposed on the back side of the conductive film (13) with a second adhesive layer (14) interposed therebetween. The image display member (15) extends in the plane direction. Specifically, the image display member (15) is an organic EL element. For example, although not illustrated, the image display member (15) includes a display substrate, two electrodes, an organic EL layer sandwiched between the two electrodes, and an encapsulation layer. Furthermore, the composition and physical properties of the image display member (15) are described in detail, for example, in Japanese Patent Publication No. 2018-28573.

[0101] <Effect of operation of one embodiment>

[0102] An optical laminate (1) of one embodiment is a novel configuration in which a film (4) is positioned on the viewing side and a glass plate (2) is positioned on the reverse side. In this optical laminate (1), the drop height H1 of the pen until the glass plate begins to crack in a pen drop crack test is 15 cm or more. Therefore, the optical laminate (1) has excellent impact resistance.

[0103] In addition, in this optical laminate (1), the drop height H2 of the pen until the film (4) begins to peel off in the pen drop peeling test is 15 cm or more. Therefore, the adhesion of the film (4) is excellent. Therefore, the optical laminate (1) has excellent reliability.

[0104] In addition, the average tanδ of the film (4) from -100℃ to -50℃ is 0.04 or higher, and the average tensile storage modulus (E') of the film (4) from -100℃ to -50℃ is 3GPa or higher and 6GPa or lower, so cracking of the glass plate (2) in the pen drop crack test can be suppressed. Therefore, the optical laminate (1) has excellent impact resistance.

[0105] In addition, in this optical laminate (1), the adhesion force between the glass plate (2) and the adhesive layer (3) is 3.0 kN / m or more, and the adhesion force between the film (4) and the adhesive layer (3) is 3.0 kN / m or more, so the adhesion force to the respective adhesive layer (3) of the film (4) and the glass plate (2) is excellent. Therefore, the optical laminate (1) has excellent reliability.

[0106] In addition, if the film (4) is a TAC film, the adhesion to the adhesive layer (3) is excellent.

[0107] Therefore, the optical laminate (1) has excellent reliability.

[0108] In addition, if the thickness of the film (4) is 60 μm or less, peeling from the adhesive layer (3) of the film (4) can be suppressed when an object collides with the optical laminate (1).

[0109] In addition, the optical laminate of the present invention has excellent impact resistance, so it has sufficient impact resistance even in glass plates with a thickness of less than 40㎛.

[0110] <Variation Example>

[0111] In the following variations, the same reference numerals are used for components and processes similar to those in the above-described embodiment, and their detailed descriptions are omitted. Additionally, the variations may exhibit the same functional effects as the embodiment, except as not specified otherwise.

[0112] In one embodiment, the film (4) is a single layer, but the number of layers of the film (4) is not limited.

[0113] The film (4) may be multilayered.

[0114] As indicated by the dashed line in FIG. 1, the optical laminate (1) may additionally be provided with a hard coat layer (38). The hard coat layer (38) is disposed on one side in the thickness direction of the film (4). The hard coat layer (38) is in contact with one side in the thickness direction of the film (4). The optical laminate (1) is provided with a glass plate (2), an adhesive layer (3), a film (4), and a hard coat layer (38) in order toward the viewing side. The formulation, physical properties, and dimensions of the hard coat layer (38) are not particularly limited. In this modified example, since the optical laminate (1) is provided with a hard coat layer (38), the impact resistance and scratch resistance of the optical laminate (1) can be improved.

[0115] Instead of the hard coat layer (38), or additionally, other functional layers may be provided. Examples of other functional layers include a scattering prevention layer, an anti-fouling layer, and an anti-reflection layer. These may be single layers or multiple layers stacked.

[0116] The optical laminate of the present invention has excellent impact resistance, so it has sufficient impact resistance even in glass plates with a thickness of less than 40 μm. Since glass plates with a thickness of less than 40 μm have excellent flexibility, the optical laminate of the present invention can be suitably used in flexible displays such as foldable displays and rollable displays.

[0117] [Example]

[0118] Specific numerical values ​​such as mixing ratios (content ratios), physical properties, and parameters used in the following description may be replaced with the corresponding upper limit values ​​(numerical values ​​defined as "less than or equal to" or "less than") or lower limit values ​​(numerical values ​​defined as "greater than or equal to" or "greater than") of the mixing ratios (content ratios), physical properties, and parameters described in the "forms for carrying out the invention" above. Furthermore, unless specifically stated otherwise in the following description, "parts" and "%" are based on mass.

[0119] In subsequent examples and comparative examples, an optical laminate (1) was manufactured, and then an adhesive layer (12) was placed on the optical laminate (1) to evaluate the impact resistance of the optical laminate (1).

[0120] Example 1

[0121] A glass plate (2) (G-leaf) with a thickness of 30 μm and a film (4) (diafoil S100, manufactured by Mitsubishi Chemical Co., Ltd.) including a polyethylene terephthalate film with a thickness of 50 μm were prepared. In addition, an epoxy adhesive composition was prepared by mixing 70 parts by mass of an aliphatic alicyclic epoxy resin (Celoxide 2021P, epoxy equivalent 128~133 g / eq., manufactured by Daicel Chemical Co., Ltd.), 5 parts by mass of a trifunctional aliphatic epoxy resin (EHPE3150, epoxy equivalent 170~190 g / eq., manufactured by Daicel Chemical Co., Ltd.), 19 parts by mass of an oxetane-based resin (Aron Oxetane, manufactured by Toa Kosei Co., Ltd.), 4 parts by mass of a silane coupling agent (KBM-403, 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), and 2 parts by mass of a photocatalytic agent (CPI101A, triarylsulfonium salt, manufactured by San Apro Co., Ltd.). This epoxy adhesive composition was applied to a glass plate (2), and then the epoxy adhesive composition was sandwiched between the glass plate (2) and a film (4).

[0122] After that, ultraviolet rays were irradiated onto the curable adhesive from the side of the glass plate (2). As a result, an adhesive layer (3) with a thickness of 1 μm was formed, which includes a cured body that firmly bonds the glass plate (2) and the film (4). The elastic modulus of the adhesive layer (3) at 25°C, measured by the nano-indenter method, was 4.9 GPa. As a result, an optical laminate (1) having the glass plate (2), the adhesive layer (3), and the film (4) was manufactured.

[0123] Next, an adhesive layer (12) with a thickness of 15 μm was placed on the other side of the glass plate (2) in the thickness direction by transfer. The adhesive layer (12) was prepared as follows.

[0124] 43 parts by mass of lauryl acrylate (LA), 44 parts by mass of 2-ethylhexyl acrylate (2EHA), 6 parts by mass of 4-hydroxybutyl acrylate (4HBA), 7 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 0.015 parts by mass of BASF’s ‘Yirgacure 184’ were mixed and polymerized by irradiating with ultraviolet light to obtain a base polymer composition (polymerization rate: about 10%).

[0125] Separately, 60 parts by mass of dicyclofentanyl methacrylate (DCPMA), 40 parts by mass of methyl methacrylate (MMA), 3.5 parts by mass of α-thioglycerol, and 100 parts by mass of toluene were mixed and stirred at 70°C for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) were added and reacted at 70°C for 2 hours, after which the temperature was raised to 80°C and reacted for 2 hours. Subsequently, the reaction mixture was heated to 130°C to dry and remove toluene, chain transfer agents, and unreacted monomers, thereby obtaining a solid acrylic oligomer. The weight-average molecular weight of the acrylic oligomer was 5100. The glass transition temperature (Tg) was 130°C.

[0126] A pressure-sensitive adhesive composition was prepared by adding 0.07 parts by mass of 1,6-hexanediol diacrylate (HDDA), 1 part by mass of an acrylic oligomer, and 0.3 parts by mass of a silane coupling agent (Shin-Etsu Chemical 'KBM403') to 100 parts by mass of the solid content of a base polymer composition, and then uniformly mixing the ingredients.

[0127] An adhesive composition was applied to the surface of a release sheet containing a PET film ('Diafoil MRF75' manufactured by Mitsubishi Chemical), and then another release sheet containing a PET film ('Diafoil MRF75' manufactured by Mitsubishi Chemical) was laminated to a coating film. After that, ultraviolet rays were irradiated onto the coating film to prepare an adhesive layer (12) with a thickness of 15 μm. The shear storage modulus (G') of this adhesive layer (12) at 25°C was 0.03 MPa. The measurement method is as follows.

[0128] The adhesive layer (12) was shaped into a disc and inserted into a parallel plate, and the shear storage modulus (G') of the adhesive layer (12) at 25°C was determined by dynamic viscoelasticity measurement under the following conditions using the ‘Advanced Rheometric Expansion System (ARES)’ manufactured by Rheometric Scientific.

[0129] [condition]

[0130] Mode: Twist

[0131] Temperature: -40℃ to 150℃

[0132] Heating rate: 5℃ / min

[0133] Frequency: 1Hz

[0134] Example 2

[0135] An optical laminate (1) was manufactured in the same manner as in Example 1. However, the film (4) was changed to a triacetylcellulose film (KC4UYW, manufactured by Konica Minolta) with a thickness of 40 μm.

[0136] Example 3

[0137] An optical laminate (1) was manufactured in the same manner as in Example 1. However, the film (4) was changed to a triacetylcellulose film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0138] Example 4

[0139] An optical laminate (1) was manufactured in the same manner as in Example 2. However, the film (4) was changed to a triacetylcellulose film (KC8UAW, manufactured by Konica Minolta) with a thickness of 80 μm.

[0140] Comparative Example 1

[0141] An optical laminate (1) was manufactured in the same manner as in Example 1. However, as the film (4), an acrylic film was used in which a methacrylic resin pellet having glutarimide ring units was formed into a film by extrusion molding and then stretched. The thickness of the acrylic film was 40 μm.

[0142] Table 1 lists the type and thickness of the film (4) in each example and comparative example.

[0143] <Evaluation>

[0144] For each example and comparative example, the following items were measured and evaluated. Their results are listed in Table 1.

[0145] <tanδ and tensile storage modulus (E') of film (4)>

[0146] The film (4) prepared in each example and comparative example was subjected to a dynamic viscoelasticity test. The apparatus and conditions are described below.

[0147] Device: Multifunctional Dynamic Viscoelasticity Measuring Device DMS6100 manufactured by Hitachi High-Tech Science Co., Ltd.

[0148] Temperature range: -100~200℃

[0149] Heating rate: 2℃ / min

[0150] Mode: Seal

[0151] Sample width: 10mm

[0152] Interval: 20mm

[0153] Frequency: 10Hz

[0154] Strain amplitude: 10㎛

[0155] Atmosphere: Waiting (250ml / min)

[0156] Data acquisition interval: 0.5 min (every 1℃)

[0157] Each average of the tensile storage modulus (E') of the film (4) from -100℃ to -50℃ was calculated by dividing the total sum of all data acquired from -100℃ to -50℃ by the number of data. Each average of the tanδ of the film (4) from -100℃ to -50℃ was calculated by dividing the total sum of all data acquired from -100℃ to -50℃ by the number of data.

[0158] <Adhesion between film (4) and adhesive layer (3)>

[0159] Using a surface and interface property analysis device, the adhesion strength between the film (4) and the adhesive layer (3) was measured using the following device, conditions, and method.

[0160] Device: Manufactured by Dipra Wintes, Surface and interface property analysis device (SAICAS DN-20 type)

[0161] Material of blade (42): single crystal diamond

[0162] Width of the blade tip (43): 1mm

[0163] Angle of inclination of the blade tip (43): 10°

[0164] As shown in A of FIG. 2, the surface and interface material property analysis device (41) is equipped with a blade (42), a moving device not shown, and a pressure measuring part. The blade (42) is movable. The blade (42) is equipped with a blade tip (43) formed at the lower end.

[0165] As shown in Fig. 2A, the optical laminate (1) was set in the measuring device (41). At this time, the film (4) was placed on the upper side and the glass plate (2) was placed on the lower side.

[0166] The blade tip (43) was moved downward in a horizontal direction (corresponding to the plane direction of the optical laminate (1)). The horizontal speed was 10 μm / sec and the vertical speed was 0.5 μm / sec. As a result, the blade tip (43) was cut into the film (4).

[0167] As shown in Fig. 2B, when the blade tip (43) reaches the interface between the film (4) and the adhesive layer (3), the blade tip (43) is moved only in the horizontal direction. The horizontal speed is maintained at 10 μm / sec. The film (4) is peeled off from the adhesive layer (3) by the horizontal movement of the blade tip (43). The peeling strength at this time is measured as the adhesion strength between the film (4) and the adhesive layer (3).

[0168] <Adhesion between glass plate (2) and adhesive layer (3)>

[0169] The adhesion strength between the glass plate (2) and the adhesive layer (3) was measured using the same apparatus, conditions, and method as described above. However, as shown in Fig. 2C, the cutting edge (43) was cut into the film (4) and then into the adhesive layer (3), and when the cutting edge (43) reached the interface between the adhesive layer (3) and the glass plate (2), the cutting edge (43) was moved horizontally. As a result, the adhesive layer (3) was peeled off from the glass plate (2). The peeling strength at this time was measured as the adhesion strength between the glass plate (2) and the adhesive layer (3).

[0170] Pen Drop Crack Test

[0171] The following pen drop crack test was performed on the optical laminate (1) of each example and comparative example. First, as shown in FIG. 1, the optical laminate (1) was placed on the surface of a resin film (34) (virtual line) so that the film (4) faces upward. Specifically, an adhesive layer (12) was attached to the surface of the resin film (34). The resin film (34) is a press scale (Fuji Film manufactured press scale MS medium pressure mono sheet type, thickness 95 μm). The resin film (34) is placed on the surface of a horizontal bar not shown. Next, a pen drop crack test is performed by dropping a 7g pen (29) (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) from a height of 5 cm from the film (4). The aforementioned height of 5 cm is the distance between one side of the film (4) in the thickness direction and the tip (32) of the pen (29). The tip (32) is pointed downward. In this optical laminate (1), if a crack occurs in the glass plate (2) during the aforementioned drop of the pen (29), the height H1 of the pen drop crack test becomes 5 cm. If no crack occurs in the glass plate (2), the height is increased stepwise by 1 cm. As a result, the height H1 when a crack occurs in the glass plate (2) is obtained.

[0172] Pen Drop Peel Test

[0173] In the same manner as the pen drop crack test described above, a pen (29) was dropped onto the film (4). The initial drop height was set to 5 cm. After that, if no peeling occurred from the adhesive layer (3) of the film (4), the height was increased step by step by 1 cm. The height at which peeling from the adhesive layer (3) of the film (4) was confirmed was obtained as the height H2 in the pen drop peeling test. Alternatively, when a crack occurred in the glass plate (2), it was determined that it had peeling durability greater than or equal to the cracked height H1.

[0174] [Table 1]

[0175]

[0176] Furthermore, although the above invention has been provided as an exemplary embodiment of the present invention, it is merely an example and should not be interpreted restrictively. Variations of the present invention that are obvious to those skilled in the art are included in the latter claims.

[0177] [Industrial Applicability]

[0178] An optical laminate is provided in an image display device. Explanation of the symbols

[0179] 1: Optical laminate 2: Glass plate 3: Adhesive layer 4: Film 29: Pen 38: Hard coat layer

Claims

Claim 1 An optical laminate comprising a glass plate, an adhesive layer, and a film arranged in order toward one side in the thickness direction, wherein the adhesive layer is a cured body of a curable adhesive, the curable adhesive is an epoxy adhesive composition containing an epoxy resin, the epoxy resin includes a difunctional epoxy resin containing two epoxy groups and a polyfunctional epoxy resin containing three or more epoxy groups, the ratio of the epoxy resin in the epoxy adhesive composition is 60 mass% or more, the one side in the thickness direction is the viewing side, and the drop height H1 of the pen until the glass plate begins to crack in the following pen drop crack test is 15 cm or more: <Pen Drop Crack Test> A pressure-sensitive adhesive layer having a thickness of 15 μm and a shear storage modulus (G') at 25°C obtained by a dynamic viscoelasticity test in a torsion mode at a frequency of 1 Hz, a heating rate of 5°C / min, a temperature of -40°C to 150°C, is disposed on the other side in the thickness direction of the optical laminate. A ballpoint pen with a weight of 7g and a ball diameter of 0.7mm is dropped toward the film. The drop height of the pen is increased by 1cm increments, and the height at which a crack is confirmed in the glass plate is obtained as the height H1 in the pen drop crack test. Claim 2 An optical laminate according to claim 1, wherein the drop height H2 of the pen until the film begins to peel off in the following pen drop peel test is 15 cm or more: <Pen Drop Peel Test> The adhesive layer is placed on the other side of the optical laminate in the thickness direction. A ballpoint pen with a weight of 7 g and a ball diameter of 0.7 mm is dropped toward the film. The drop height of the pen is gradually increased up to 30 cm, and the height at which peeling is confirmed on the film is obtained as the height H2 in the pen drop peel test. Alternatively, if a crack occurs in the glass plate, it is determined that it has peel resistance with a crack height H1 or greater. Claim 3 An optical laminate according to claim 1 or 2, wherein the average tanδ of the film from -100°C to -50°C obtained by a dynamic viscoelasticity test in a tensile mode at a frequency of 10 Hz and a heating rate of 2°C / min is 0.04 or higher, and the average tensile storage modulus (E') of the film from -100°C to -50°C obtained by the dynamic viscoelasticity test is 3 GPa or higher and 6 GPa or lower. Claim 4 An optical laminate according to claim 1 or 2, wherein the adhesion force between the glass plate and the adhesive layer is 3.0 kN / m or more, and the adhesion force between the film and the adhesive layer is 3.0 kN / m or more. Claim 5 An optical laminate according to claim 1 or 2, wherein the film is a triacetylcellulose film. Claim 6 In claim 5, the film is an optical laminate having a thickness of 10㎛ or more and 60㎛ or less. Claim 7 An optical laminate according to claim 1 or 2, further comprising a hard coat layer disposed on one side of the thickness direction of the film.

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