Optical laminate

Abstract

The optical laminate (1) of the present invention comprises a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6) arranged in order toward one side in the thickness direction. One side in the thickness direction is the viewing side. In the following pen drop cracking test, the drop height H1 of the pen until the glass plate (4) begins to crack is 20 cm or more. An adhesive layer (12) 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 with 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 in the thickness direction of the first film (2), wherein the shear storage modulus (G') at 25°C is 0.03 MPa. A 10 g pen is dropped toward the second film (6). The drop height of the pen is increased by 1 cm increments up to 30 cm, and the height at which a crack is confirmed in the glass plate (4) is obtained as the height H1 in the pen drop crack test. Alternatively, if no crack is confirmed in the glass plate (4) at a drop height of 30 cm, it is determined that it has a peeling durability of 30 cm or more.

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. The 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, upon careful examination, discovered a novel optical laminate in which a second film is positioned on the visual side of a glass plate and a first film is positioned on the reverse side of the visual side of the glass plate, and discovered that such an optical laminate has excellent impact resistance.

[0007] The present invention (1) is an optical laminate comprising a first film, a first adhesive layer, a glass plate, a second adhesive layer, and a second film in sequence facing one side in the thickness direction, wherein the one side in the thickness direction is a 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 20 cm or more.

[0008] Pen Drop Crack Test

[0009] An adhesive layer with 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 ballpoint pen with a weight of 7 g and a ball diameter of 0.7 mm is dropped toward the second film. The drop height of the pen is increased in increments of 1 cm up to 30 cm, 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. Alternatively, if no crack is confirmed in the glass plate at a drop height of 30 cm, it is determined that it has a crack resistance of 30 cm or more.

[0010] The present invention (2) includes an optical laminate described in (1) in which the drop height H2 of the pen until the first film or the second film begins to peel off in the following pen drop peeling test is 20 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 ballpoint pen with a weight of 7g and a ball diameter of 0.7mm is dropped toward the second film. The drop height of the pen is increased in increments of 1cm up to 30cm, and the height at which peeling is confirmed on the first film or the second film is obtained as height H2 in the pen drop peeling test. Alternatively, if a crack is confirmed on the glass plate, it is determined that it has peeling durability greater than or equal to crack height H1.

[0013] Alternatively, if no peeling is confirmed between the first film and the second film at a drop height of 30 cm from the pen, it is determined that the film has a peeling durability of 30 cm or more.

[0014] The present invention (3) includes an optical laminate described in (1) or (2), wherein the ratio of the average tanδ of the second film obtained from the dynamic viscoelastic test from -100°C to -50°C to the average tanδ of the first film obtained from the dynamic viscoelastic test from -100°C to -50°C obtained by the dynamic viscoelastic test from -100°C to -50°C obtained by the dynamic viscoelastic test from -100°C to -50°C obtained by the frequency 10 Hz, heating rate 2°C / min, is 0.8 or more and 1.5 or less.

[0015] The present invention (4) includes an optical laminate described in any one of claims (1) to (3), wherein the average tanδ of the first 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 first film from -100°C to -50°C obtained by the dynamic viscoelasticity test is 3 GPa or higher and 6 GPa or lower.

[0016] The present invention (5) includes an optical laminate described in any one of (1) to (4), wherein the adhesion force between the first film and the first adhesive layer is 3.0 kN / m or more, the adhesion force between the first adhesive layer and the glass plate is 3.0 kN / m or more, the adhesion force between the glass plate and the second adhesive layer is 3.0 kN / m or more, and the adhesion force between the second adhesive layer and the second film is 3.0 kN / m or more.

[0017] The present invention (6) comprises an optical laminate described in any one of claims (1) to (5), wherein each of the first film and the second film is a triacetylcellulose film.

[0018] The present invention (7) includes an optical laminate described in (6), wherein the second film is thicker than the first film.

[0019] The present invention (8) includes an optical laminate described in (7) which further comprises a hard coat layer disposed on one side of the thickness direction of the second film. Effects of the invention

[0020] The optical laminate of the present invention has excellent impact resistance because the second 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 20 cm or more. Brief explanation of the drawing

[0021] FIG. 1 is a cross-sectional view of one embodiment of the optical laminate of the present invention. FIGS. 2A to FIG. 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 the first film. FIG. 2B is an embodiment in which the cutting edge reaches the interface between the first film and the first 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 first 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

[0022] <Optical laminate (1)>

[0023] An embodiment of the optical laminate of the present invention will be described with reference to FIGS. 1 to 3.

[0024] 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) has a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6) arranged in order toward one side in the thickness direction.

[0025] One side in the thickness direction is the visible side. The other side in the thickness direction is the reverse side of the visible side (hereinafter simply referred to as the reverse side).

[0026] <First Film (2)>

[0027] The first film (2) extends in the plane direction. The first film (2) forms the other side (reverse side) in the thickness direction of the optical laminate (1).

[0028] The average tanδ of the first film (2) from -100°C to -50°C, obtained by a dynamic viscoelasticity test 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 first film (2) 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 first film (2) 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 first film (2) can sufficiently mitigate the impact received by the glass plate (4) even when an object collides with the glass plate (4) at high speed, and the impact resistance of the optical laminate (1) can be improved. The dynamic viscoelasticity test is described in a later example.

[0029] The average tensile storage modulus (E') of the first film (2) at -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 first film (2) at -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.

[0030] As the first film (2), examples include a polyester film and a cellulose film. Examples of polyester films include polyethylene terephthalate (PET), polybutylene terephthalate (PBT) film and polyethylene naphthalate (PEN) film. Examples of cellulose films include an acetylcellulose film, and specifically, a triacetylcellulose (TAC) film. As the first film (2), from the perspective of increasing the adhesion strength to the first adhesive layer (3) of the first film (2), a cellulose film is preferably used, and more preferably, a TAC film is used.

[0031] The thickness of the first film (2) is not limited. The thickness of the first film (2) is, for example, 10 μm or more, preferably 20 μm or more. If the thickness of the first film (2) is greater than or equal to the lower limit mentioned above, the impact resistance of the optical laminate (1) can be improved. In addition, the thickness of the first film (2) is, for example, 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less, even more preferably 80 μm or less, particularly preferably 50 μm or less, most preferably 30 μm or less, and 23 μm or less is suitable.

[0032] The total light transmittance of the first film (2) is, for example, 40% or more, preferably 50% or more, and also, for example, 99% or less.

[0033] <First adhesive layer (3)>

[0034] The first adhesive layer (3) extends in the plane direction. The first adhesive layer (3) is disposed on one side in the thickness direction of the first film (2). Specifically, the first adhesive layer (3) contacts one side in the thickness direction of the first film (2). The first 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 first adhesive layer (3) is a cured body of a curable adhesive that undergoes a curing reaction by irradiation with active energy rays or heating.

[0035] As a curing material for the first 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.

[0036] 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, a polyfunctional epoxy resin containing three or more epoxy groups, etc. These may be used alone or in combination of two or more types.

[0037] Preferably, the combined use of a difunctional epoxy resin and a polyfunctional epoxy resin may be used.

[0038] 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 a 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.

[0039] 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, a trifunctional aliphatic epoxy resin is used as a 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.

[0040] 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.

[0041] 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.

[0042] In addition, if the epoxy adhesive composition is an active energy curing type, it includes a photogenerator. 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.

[0043] In addition, the epoxy adhesive composition may include additives such as oxetane-based resins and silane coupling agents in appropriate proportions.

[0044] 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 may be used, such as Aron-oxetane (manufactured by Doagosei Co., Ltd.).

[0045] 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.).

[0046] The thickness of the first adhesive layer (3) is not limited. The thickness of the first 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.

[0047] The total light transmittance of the first adhesive layer (3) is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less.

[0048] The tensile storage modulus (E') of the first 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 first 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 first 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.

[0049] Device: Triboindenter (Manufactured by Hysitron Inc.)

[0050] Sample size: 10×10mm

[0051] Indenter: Concial (Spherical indenter: radius of curvature 10㎛),

[0052] Measurement method: Single indentation measurement

[0053] Measured temperature: 25℃

[0054] Indenter indentation depth: 100nm

[0055] Temperature: 25℃

[0056] Analysis: Oliver Pharr analysis based on load-displacement curves

[0057] The adhesion force between the first film (2) and the first 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. The adhesion force between the first film (2) and the first adhesive layer (3) can be determined as the peel strength when the first film (2) is peeled from the first adhesive layer (3) by inserting the tip (43) of the blade (42) provided by the device (41) into the interface between the first film (2) and the first adhesive layer (3), as shown in FIG. 2B, and moving the blade (42) along the plane direction. Details of the method for measuring the adhesion force will be described in a later example. If the adhesion force between the first film (2) and the first adhesive layer (3) is greater than or equal to the lower limit mentioned above, peeling of the first film (2) from the first adhesive layer (3) can be suppressed.

[0058] Glass plate (4)

[0059] The glass plate (4) extends in the plane direction. The glass plate (4) is located on the opposite side of the first film (2) to the first adhesive layer (3). The glass plate (4) is placed on one side in the thickness direction of the first adhesive layer (3).

[0060] Specifically, the glass plate (4) comes into contact with one side in the thickness direction of the first adhesive layer (3). As a result, the first adhesive layer (3) comes into contact with the other side in the thickness direction of the glass plate (4) and one side in the thickness direction of the first film (2), and the first film (2) and the glass plate (4) are bonded (bonded).

[0061] The total light transmittance of the glass plate (4) is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less. The glass plate (4) can be a commercially available product, for example, the G-leaf series (registered trademark, manufactured by Nippon Electric Glass Co., Ltd.).

[0062] The adhesion force between the glass plate (4) and the first 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. The adhesion force between the glass plate (4) and the first adhesive layer (3) can be determined as the peel strength when the first adhesive layer (3) is peeled from the glass plate (4) by inserting the tip (43) of the blade (42) provided by the device (41) into the interface between the glass plate (4) and the first adhesive layer (3), as shown in Fig. 2C, and moving the blade (42) along the plane direction. Details of the method for measuring the adhesion force will be described in a later example.

[0063] The thickness of the glass plate (4) is not limited. The thickness of the glass plate (4) is, for example, 5 μm or more, preferably 10 μm or more, more preferably 20 μm. The thickness of the glass plate (4) is 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less.

[0064] <Second adhesive layer (5)>

[0065] The second adhesive layer (5) extends in the plane direction. The second adhesive layer (5) is disposed on one side in the thickness direction of the glass plate (4). Specifically, the second adhesive layer (5) contacts one side in the thickness direction of the glass plate (4). The second adhesive layer (5) is a cured body of a curable adhesive that is not an adhesive layer (pressure-sensitive adhesive layer) containing an adhesive (pressure-sensitive adhesive). In detail, the second adhesive layer (5) is a cured body of a curable adhesive that undergoes a curing reaction by irradiation with active energy rays or heating. The curing raw material, thickness, total light transmittance, tensile storage modulus (E'), and elastic modulus measured by the nano-indenter method of the second adhesive layer (5) are the same as those of the first adhesive layer (3).

[0066] The adhesion force between the glass plate (4) and the second adhesive layer (5) 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. The adhesion force between the glass plate (4) and the second adhesive layer (5) can be obtained by the same method as the method for measuring the adhesion force between the glass plate (4) and the first adhesive layer (3) described above.

[0067] <Film 2 (6)>

[0068] The second film (6) forms one side (visible side) in the thickness direction of the optical laminate (1). The second film (6) is located on the opposite side of the glass plate (4) to the second adhesive layer (5). The second film (6) extends in the plane direction. The second film (6) is placed on one side in the thickness direction of the second adhesive layer (5). The second film (6) is in contact with one side in the thickness direction of the second adhesive layer (5). As a result, the second adhesive layer (5) is in contact with one side in the thickness direction of the glass plate (4) and the other side in the thickness direction of the second film (6), thereby bonding (bonding) the glass plate (4) and the second film (6).

[0069] The average tanδ of the second film (6) from -100°C to -50°C, obtained by a dynamic viscoelasticity test 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 set so that the ratio with the average tanδ of the first film (2), which will be described later, is within a specific range. The average tanδ of the second film (6) from -100°C to -50°C 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 second film (6) 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 second film (6) 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 of tanδ is high, the second film (6) can sufficiently mitigate the impact received by the glass plate (4) even when an object collides with the glass plate (4) at high speed, thereby improving the impact resistance of the optical laminate (1). The dynamic viscoelasticity test is described in a later example.

[0070] The ratio of the average tanδ of the second film at -100°C to -50°C to the average tanδ of the first film at -100°C to -50°C is, for example, 0.5 or more, preferably 0.8 or more, more preferably 0.9 or more, and also, for example, 2.0 or less, preferably 1.5 or less, more preferably 1.1 or less. If the above ratio is above the lower limit and below the upper limit, the impact resistance of the optical laminate (1) can be improved.

[0071] The average tensile storage modulus (E') of the second film (6) at -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 second film (6) at -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.

[0072] The adhesion force between the second film (6) and the second adhesive layer (5) 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 second film (6) and the second adhesive layer (5) is greater than or equal to the lower limit mentioned above, delamination at the interface between the second film (6) and the second adhesive layer (5) can be suppressed when an object collides with the second film (6) of the optical laminate (1). The adhesion force between the second film (6) and the second adhesive layer (5) can be obtained by the same method as the method for measuring the adhesion force between the first film (2) and the first adhesive layer (3) mentioned above.

[0073] As for the second film (6), for example, the film exemplified in the first film (2) may be used. As for the second film (6), a cellulose film may be used, and more preferably a TAC film, in order to increase the adhesion of the second film (6) to the second adhesive layer (5) and suppress the peeling of the second film (6) when an object collides with the optical laminate (1).

[0074] As a combination of the first film (2) and the second film (6), preferably, the first film (2) is a PET film and the second film (6) is a TAC film, or the first film (2) is a TAC film and the second film (6) is a TAC film.

[0075] More preferably, a combination in which the first film (2) is a TAC film and the second film (6) is a TAC film, that is, a combination in which each of the first film (2) and the second film (6) is a TAC film, may be used.

[0076] The thickness of the second film (6) is not limited. Preferably, the second film (6) is thicker than the first film (2). In particular, if the first film (2) and the second film (6) are each TAC films, the second film (6) is thicker than the first film (2). If the second film (6) is thicker than the first film (2), the impact resistance of the optical laminate (1) can be improved while preventing peeling of the second film (6).

[0077] Specifically, the thickness of the second film (6) is, for example, 10 μm or more, preferably 20 μm or more, and more preferably 30 μm or more. If the thickness of the second film (6) is greater than or equal to the lower limit mentioned above, the impact resistance of the optical laminate (1) can be improved. In addition, the thickness of the second film (6) is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 60 μm or less. If the thickness of the second film (6) is less than or equal to the upper limit mentioned above, peeling of the second film (6) can be suppressed when an object collides with the optical laminate (1).

[0078] The total light transmittance of the second film (6) is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less.

[0079] <Adhesive layer (12)>

[0080] 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 in the thickness direction of the first film (2). Specifically, the adhesive layer (12) is in contact with the other side in the thickness direction of the first film (2). That is, the optical laminate (1) is provided with the adhesive layer (12), the first film (2), the first adhesive layer (3), the glass plate (4), the second adhesive layer (5), and the second film (6) in order toward one side in the thickness direction. The adhesive layer (12) is an adhesive that performs pressure bonding without involving a curing reaction.

[0081] The material of the adhesive layer (12) is not limited. Examples of materials for the adhesive layer (12) include acrylic adhesives, rubber adhesives, vinylalkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, epoxy adhesives, and polyether adhesives. Preferably, acrylic adhesives are 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.

[0082] 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.

[0083] The thickness of the adhesive layer (12) is, for example, 5 μm or more, preferably 5 μm or more, and also, for example, 50 μm or less, preferably 30 μm or less, more preferably 20 μm or less.

[0084] The thickness of the optical laminate (1) is, for example, 50 μm or more, and also, for example, 300 μm or less.

[0085] Pen Drop Crack Test

[0086] In the optical laminate (1), the drop height H1 of the pen until the glass plate (4) begins to crack in the pen drop crack test is 20 cm or more.

[0087] First, an optical laminate (1) is placed on the surface of a horizontal bar (not shown) by interposing a resin film (34) that represents the optical laminate (1) as a virtual line. An optical laminate (1) with a thickness of 15 μm is placed on one side of the glass plate (4) in the thickness direction.

[0088] In addition, this adhesive layer (12) also serves as a fixing member for fixing the optical laminate (1) to a 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, a temperature of -40°C to 150°C, is 0.03 MPa.

[0089] As shown in FIG. 1, a pen (29) (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped toward the second film (6). The mass of the pen (29) is 7 g. The height from the second film (6) to the tip (32) of the pen (29) is 5 cm. The tip (32) is pointed downwards. When the pen (29) is dropped as described above, if no crack occurs in the glass plate (4), the height is increased by 1 cm. The height at which a crack is confirmed in the glass plate (4) is obtained as the height H1 in the pen drop crack test. Alternatively, if no crack is confirmed in the glass plate (4) at a drop height of 30 cm, it is determined that it has a peel durability of 30 cm or more.

[0090] Meanwhile, if the drop height H1 in the pen drop crack test is less than 20 cm, the impact resistance of the optical laminate (1) is low.

[0091] On the other hand, the drop height H1 in the pen drop crack test is preferably 25 cm or more, and more preferably 30 cm or more.

[0092] Pen Drop Peel Test

[0093] In the optical laminate (1), the drop height H2 of the pen (29) until the second film (6) begins to peel off in the pen drop peeling test is 20 cm or more.

[0094] The pen drop peel test is performed in parallel with the pen drop crack test described above. First, the optical laminate (1) is placed on the surface of a horizontal bar (not shown) with a resin film (34) representing the optical laminate (1) as a virtual line interposed therein. If the adhesive layer (12) is not placed on the optical laminate (1), 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.

[0095] As shown in FIG. 1, a pen (29) (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped toward the second film (6). The mass of the pen (29) is 7 g. The height from the glass plate (4) to the tip (32) of the pen (29) is 5 cm. The tip (32) is pointed downward. During the above drop of the pen (29), if no peeling occurs from the first adhesive layer (3) of the first film (2), from the first adhesive layer (3) of the glass plate (4), from the second adhesive layer (5) of the glass plate (4), or from the second adhesive layer (5) of the second film (6), the height is increased by 1 cm. The height at which any one of the above peeling is confirmed is obtained as the height H2 in the pen drop peeling test. Alternatively, when a crack is detected in the glass plate (4), it is determined that it has peeling durability of crack height H1 or higher. Alternatively, when the above peeling is not detected at a drop height of 30 cm from the pen, it is determined that it has peeling durability of 30 cm or higher.

[0096] An optical laminate (1) satisfying the above requirements has high adhesion to the first adhesive layer (3) of the first film (2), high adhesion to the first adhesive layer (3) of the glass plate (4), high adhesion to the glass plate (4) of the second adhesive layer (5), and high adhesion to the second adhesive layer (5) of the second film (6). Therefore, the optical laminate (1) has excellent reliability.

[0097] <Method for manufacturing an optical laminate (1)>

[0098] A method for manufacturing an optical laminate (1) is described. In the method for manufacturing an optical laminate (1), a curable adhesive is placed (applied) on, for example, the other side in the thickness direction of a glass plate (4) and / or one side in the thickness direction of a first film (2), and the said curable adhesive is inserted between the glass plate (4) and the first film (2). A curable adhesive is placed (applied) on one side in the thickness direction of a glass plate (4) and / or the other side in the thickness direction of a second film (6), and the said curable adhesive is inserted between the glass plate (4) and the second film (6).

[0099] After that, two curable adhesives are cured. If the curable adhesive is an active energy curable type, active energy including ultraviolet rays is irradiated onto the curable adhesive. If the curable adhesive is a heat curable type, the curable adhesive is heated. As a result, a first adhesive layer (3) and a second adhesive layer (5) are formed. The first adhesive layer (3) firmly adheres the first film (2) and the glass plate (4). The second adhesive layer (5) firmly adheres the glass plate (4) and the second film (6).

[0100] As a result, an optical laminate (1) is obtained having a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6).

[0101] After that, in order to further provide an adhesive layer (12) in the optical laminate (1), the adhesive layer (12) is placed on the other side in the thickness direction of the first film (2). For example, a varnish containing an adhesive is applied and dried on the other side in the thickness direction of the first film (2). Alternatively, the adhesive layer (12) formed on a release sheet not shown may be transferred to the other side in the thickness direction of the first film (2). As a result, an optical laminate (1) having an adhesive layer (12), a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6) is obtained. Additionally, a release sheet not shown may be provided in the optical laminate (1). In that case, the optical laminate (1) comprises an unillustrated peeling sheet, an adhesive layer (12), a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6).

[0102] <Uses of optical laminate (1)>

[0103] 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').

[0104] Next, an organic EL display device (10) equipped with an optical laminate (1) will be described with reference to FIG. 3.

[0105] <Organic EL display device (10)>

[0106] 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 facing the surface. 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).

[0107] <Optical laminate (1)>

[0108] The optical laminate (1) is configured with an adhesive layer (12), a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6) in order facing the surface (visibility side).

[0109] <Challenging Film (13)>

[0110] The conductive film (13) is provided with a conductive layer (16) and a substrate layer (17) in sequence facing this side.

[0111] <Challenge Layer (16)>

[0112] 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.

[0113] <Layer (17)>

[0114] 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.

[0115] <Second adhesive layer (14)>

[0116] 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).

[0117] <Image display component (15)>

[0118] 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 fitted 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.

[0119] <Effect of operation of one embodiment>

[0120] An optical laminate (1) of one embodiment is a novel configuration in which a second film (6) is placed on the viewing side of a glass plate (4) and a first film (2) is placed on the reverse side of a glass plate (4). In this optical laminate (1), the drop height H1 of the pen until the glass plate (4) begins to crack in a pen drop crack test is 20 cm or more. Therefore, the optical laminate (1) has excellent impact resistance.

[0121] In addition, in this optical laminate (1), preferably, the drop height H2 of the pen until the first film (2) or the second film (6) begins to peel off in the pen drop peeling test is 20 cm or more. Therefore, the optical laminate (1) has excellent reliability.

[0122] In addition, in this optical laminate (1), if the ratio of the average tanδ of the first film (2) at -100°C to -50°C to the average tanδ of the second film (6) at -100°C to -50°C is 0.8 or more and 1.5 or less, the difference in shock absorption behavior between the first film (2) and the second film (6) can be reduced. Therefore, delamination of the first film (2) or the second film (6) can be suppressed. As a result, the optical laminate (1) has excellent reliability.

[0123] In addition, in this optical laminate (1), if the average tanδ of the first film (2) from -100°C to -50°C is 0.04 or higher, and the average tensile storage modulus (E') of the first film (2) from -100°C to -50°C obtained by dynamic viscoelasticity test is 3 GPa or higher and 6 GPa or lower, then cracking of the glass plate (4) in the pen drop crack test can be suppressed. Therefore, the optical laminate (1) has excellent impact resistance.

[0124] In addition, in this optical laminate (1), if the adhesion force between the first film (2) and the first adhesive layer (3) is 3.0 kN / m or more, the adhesion force between the first adhesive layer (3) and the glass plate (4) is 3.0 kN / m or more, the adhesion force between the glass plate (4) and the second adhesive layer (5) is 3.0 kN / m or more, and the adhesion force between the second adhesive layer (5) and the second film (6) is 3.0 kN / m or more, then the adhesion force of the first film (2) to the glass plate (4) and the adhesion force of the second film (6) to the glass plate (4) are excellent. Therefore, the optical laminate (1) has excellent reliability.

[0125] In addition, in this optical laminate (1), if the first film (2) and the second film (6) are each TAC films, the adhesion to the first adhesive layer (3) of the first film (2) and the adhesion to the second adhesive layer (5) of the second film (6) are excellent. Therefore, the optical laminate (1) has excellent reliability.

[0126] In addition, if the second film (6) is thicker than the first film (2), the resistance of the first film (2) to the shock absorption behavior of the second film (6) can be reduced, and as a result, delamination of the first film (2) or the second film (6) can be suppressed. Therefore, the optical laminate (1) has excellent reliability.

[0127] <Variation Example>

[0128] 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.

[0129] In one embodiment, the first film (2) is a single layer, but the number of layers of the first film (2) is not limited. The first film (2) may be a multilayer.

[0130] In one embodiment, the second film (6) is a single layer, but the number of layers of the second film (6) is not limited. The second film (6) may be a multilayer.

[0131] 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 second film (6). The hard coat layer (38) is in contact with one side in the thickness direction of the second film (6). The optical laminate (1) is provided with the first film (2), the first adhesive layer (3), the glass plate (4), the second adhesive layer (5), the second film (6), and the 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.

[0132] 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.

[0133] 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.

[0134] [Example]

[0135] 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 or equal to") 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.

[0136] 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 and peel resistance of the optical laminate (1).

[0137] Example 1

[0138] A glass plate (4) (G-leaf) with a thickness of 30 μm, a first film (2) (diafoil S100, manufactured by Mitsubishi Chemical Co.) with a thickness of 25 μm, and a second film (6) with a thickness of 40 μm, a triacetylcellulose film (KC4UYW, manufactured by Konica Minolta) were prepared. In addition, an epoxy adhesive composition (curing adhesive) 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 Doagosei 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 inserted between a glass plate (4) and a first film (2). Additionally, an epoxy adhesive composition was inserted between the glass plate (4) and the second film (6). An acrylic adhesive composition applied to one side of the glass plate (4) was inserted between the glass plate (4) and the second film (6). An acrylic adhesive composition applied to the other side of the glass plate (4) was inserted between the glass plate (4) and the second film (2).

[0139] Afterward, ultraviolet rays were irradiated onto two curable adhesives. As a result, a first adhesive layer (3) with a thickness of 1 μm and a second adhesive layer (5) with a thickness of 1 μm were formed. The first adhesive layer (3) includes a cured body that firmly bonds the first film (2) and the glass plate (4). The elastic modulus of the first adhesive layer (3) at 25°C, measured by the nano-indenter method, was 4.9 GPa. The second adhesive layer (5) includes a cured body that firmly bonds the second film (6) and the glass plate (4). The elastic modulus of the second adhesive layer (5) at 25°C, measured by the nano-indenter method, was 4.9 GPa.

[0140] As a result, an optical laminate (1) was manufactured by sequentially providing a first film (2), a first adhesive layer (3), a glass plate (4), a second adhesive layer (5), and a second film (6) in one direction in the thickness direction.

[0141] Next, an adhesive layer (12) with a thickness of 15 μm was placed on the other side of the first film (2) in the thickness direction by transfer. The adhesive layer (12) was prepared as follows.

[0142] 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%).

[0143] 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 to obtain a solid acrylic oligomer. The weight-average molecular weight of the acrylic oligomer was 5100. The glass transition temperature (Tg) was 130°C.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] [condition]

[0148] Mode: Twist

[0149] Temperature: -40℃ to 150℃

[0150] Heating rate: 5℃ / min

[0151] Frequency: 1Hz

[0152] Example 2

[0153] An optical laminate (1) was manufactured in the same manner as in Example 1. However, the thickness of the first film (2) was changed to 50 μm.

[0154] Example 3

[0155] An optical laminate (1) was manufactured in the same manner as in Example 2. However, the second film (6) was changed to a triacetylcellulose film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0156] Example 4

[0157] An optical laminate (1) was manufactured in the same manner as in Example 1. However, the second film (6) was changed to a triacetylcellulose film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0158] Example 5

[0159] An optical laminate (1) was manufactured in the same manner as in Example 3. However, the first film (2) was changed to a triacetylcellulose film (KC4UYW, manufactured by Konica Minolta) with a thickness of 40 μm.

[0160] Example 6

[0161] An optical laminate (1) was manufactured in the same manner as in Example 1. However, the first film (2) was changed to a triacetylcellulose film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0162] Example 7

[0163] An optical laminate (1) was manufactured in the same manner as in Example 5. However, the first film (2) was changed to a triacetylcellulose film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0164] Comparative Example 1

[0165] An optical laminate (1) was manufactured in the same manner as in Example 3. However, the first film (2) and the first adhesive layer (3) were not provided in the optical laminate (1). This optical laminate (1) comprises a glass plate (4), a second adhesive layer (5), and a second film (6).

[0166] Comparative Example 2

[0167] An optical laminate (1) was manufactured in the same manner as in Example 5. However, the second adhesive layer (5) and the second film (6) were not provided in the optical laminate (1). This optical laminate (1) comprises a first film (2), a first adhesive layer (3), and a glass plate (4).

[0168] Table 1 lists the types and thicknesses of the first film (2) and the second film (6) in each example and comparative example.

[0169] <Evaluation>

[0170] For each example and comparative example, the following items were measured and evaluated. Their results are listed in Table 1.

[0171] <tanδ and tensile storage modulus (E') of the first film (2) and the second film (6)>

[0172] The first film (2) and the second film (6) prepared in each example and comparative example were subjected to a dynamic viscoelasticity test. The apparatus and conditions are described below.

[0173] Device: Multifunctional dynamic viscoelasticity measuring device DMS6100 manufactured by Hitachi High-Tech Science Co., Ltd.

[0174] Temperature range: -100~200℃

[0175] Heating rate: 2℃ / min

[0176] Mode: Seal

[0177] Sample width: 10mm

[0178] Interval: 20mm

[0179] Frequency: 10Hz

[0180] Strain amplitude: 10㎛

[0181] Atmosphere: Waiting (250ml / min)

[0182] Data acquisition interval: 0.5 min (every 1℃)

[0183] Each average of the tensile storage modulus (E') of the first film (2) 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 first film (2) from -100℃ to -50℃ was calculated by dividing the total sum of all data acquired from -100℃ to -50℃ by the number of data. The average of the tanδ of the second film (6) was calculated in the same manner as above.

[0184] <Adhesion force between the first film (2) and the first adhesive layer (3) and adhesion force between the second film (6) and the second adhesive layer (5)>

[0185] Using a surface and interface property analysis device, the adhesion strength of the first film (2) and the first adhesive layer (3) was measured using the following device, conditions, and method.

[0186] Device: Manufactured by Dipra Wintes, Surface and interface property analysis device (SAICAS DN-20 type)

[0187] Material of blade (42): single crystal diamond

[0188] Width of the blade tip (43): 1mm

[0189] Angle of inclination of the blade tip (43): 10°

[0190] 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 tip.

[0191] As shown in Fig. 2A, the optical laminate (1) was set in the measuring device (41).

[0192] The blade tip (43) was moved to one side in the horizontal direction (corresponding to the plane direction of the optical laminate (1)) in the inclined thickness direction. The horizontal speed is 10 μm / sec and the vertical speed is 0.5 μm / sec.

[0193] As a result, the blade tip (43) was inserted into the first film (2).

[0194] As shown in Fig. 2B, when the blade tip (43) reaches the interface between the first film (2) and the first adhesive layer (3), the blade tip (43) is moved only in the horizontal direction. The horizontal speed is maintained at 10 μm / sec. The first film (2) is peeled off from the first 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 first film (2) and (3).

[0195] The adhesion force between the second film (6) and the second adhesive layer (5) was determined in the same way as above.

[0196] <Adhesion force between the first adhesive layer (3) and the glass plate (4) and adhesion force between the glass plate (4) and the second adhesive layer (5)>

[0197] The adhesion force between the first adhesive layer (3) and the glass plate (4) was measured using the same apparatus, conditions, and method as described above. However, as shown in Fig. 2C, the blade tip (43) was inserted into the first film (2) and then into the first adhesive layer (3), and the blade tip (43) was moved horizontally when it reached the interface between the first adhesive layer (3) and the glass plate (4). As a result, the first adhesive layer (3) was peeled off from the glass plate (4). The peeling strength at this time was measured as the adhesion force between the first adhesive layer (3) and the glass plate (4). The adhesion force between the first adhesive layer (3) and the glass plate (4) was 4.5 kN / m.

[0198] The adhesion force between the glass plate (4) and the second adhesive layer (5) was determined in the same manner as above. The adhesion force between the glass plate (4) and the second adhesive layer (5) was 4.5 kN / m.

[0199] Pen Drop Crack Test

[0200] 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 second film (6) faced 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 ballpoint pen (29) with a weight of 7g and a ball diameter of 0.7 mm from a height of 5 cm from the second film (6). The height of 5 cm is the distance between one side of the second film (6) 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 (4) during the above-mentioned 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 (4), the height is increased by 1 cm. In this way, the height H1 when a crack occurs in the glass plate (4) is obtained.

[0201] Pen Drop Peel Test

[0202] In the same manner as the pen drop crack test described above, a pen (29) was dropped onto the second film (6). The initial drop height was set to 5 cm. Subsequently, if no peeling occurred from the second adhesive layer (5) of the second film (6), from the second adhesive layer (5) of the glass plate (4), from the first adhesive layer (3) of the glass plate (4), or from the first adhesive layer (3) of the first film (2), the height was increased by 1 cm. The height at which the above peeling was confirmed was obtained as the height H2 in the pen drop peeling test. Alternatively, if a crack was confirmed in the glass plate (4), it was determined that it had peeling durability greater than or equal to the crack height H1. Alternatively, if the above peeling was not confirmed even at a drop height of 30 cm of the pen (29), it was determined that it had peeling durability greater than or equal to 30 cm.

[0203] [Table 1]

[0204]

[0205] 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.

[0206] [Industrial Applicability]

[0207] An optical laminate is provided in an image display device. Explanation of the symbols

[0208] 1: Optical laminate 2: First Film 3: First adhesive layer 4: Glass plate 5: Second adhesive layer 6: Second Film 12: Adhesive layer 29: Pen 38: Hard coat layer

Claims

Claim 1 An optical laminate comprising a first film, a first adhesive layer, a glass plate, a second adhesive layer, and a second film arranged in sequence facing one side in the thickness direction, wherein the thickness of the first adhesive layer is 5 μm or less, 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 20 cm or more: <Pen Drop Crack Test> Frequency 1 Hz, heating rate 5 ℃ / min, temperature -40 ℃ to 150 ℃, and an adhesive layer having a thickness of 15 μm and a shear storage modulus (G') at 25 ℃ obtained by a dynamic viscoelasticity test in torsion mode is 0.03 MPa, is placed on the other side in the thickness direction of the optical laminate. A ballpoint pen with a ball diameter of 0.7 mm and a weight of 7 g is dropped toward the second film. The drop height of the pen is increased in increments of 1 cm up to 30 cm, and the height at which a crack is confirmed in the glass plate is obtained as height H1 in the pen drop crack test. Alternatively, if no crack is confirmed in the glass plate at a drop height of 30 cm, it is determined that it has crack durability of 30 cm or more. Claim 2 An optical laminate according to claim 1, wherein the drop height H2 of the pen until the first film or the second film begins to peel off in the following pen drop peel test is 20 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 second film. The drop height of the pen is increased in increments of 1 cm up to 30 cm, and the height at which peeling is confirmed on the first film or the second film is obtained as the height H2 in the pen drop peel test. Alternatively, if a crack is confirmed on the glass plate, it is determined that it has peel durability of crack height H1 or more. Alternatively, if no peeling is confirmed on the first film and the second film at a drop height of 30 cm, it is determined that it has peel durability of 30 cm or more. Claim 3 An optical laminate according to claim 1 or 2, wherein the ratio of the average tanδ of the second film obtained from the dynamic viscoelastic test from -100°C to -50°C to the average tanδ of the first film obtained from the dynamic viscoelastic test in the tensile mode is 0.8 or more and 1.5 or less. Claim 4 An optical laminate according to claim 1 or 2, wherein the average tanδ of the first 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 first film from -100°C to -50°C obtained by the dynamic viscoelasticity test is 3 GPa or higher and 6 GPa or lower. Claim 5 An optical laminate according to claim 1 or 2, wherein the adhesion force between the first film and the first adhesive layer is 3.0 kN / m or more, the adhesion force between the first adhesive layer and the glass plate is 3.0 kN / m or more, the adhesion force between the glass plate and the second adhesive layer is 3.0 kN / m or more, and the adhesion force between the second adhesive layer and the second film is 3.0 kN / m or more. Claim 6 An optical laminate according to claim 1 or 2, wherein each of the first film and the second film is a triacetylcellulose film. Claim 7 In paragraph 6, the second film is an optical laminate that is thicker than the first film. Claim 8 An optical laminate according to claim 1 or 2, further comprising a hard coat layer disposed on one side in the thickness direction of the second film.

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