Optical laminate

Abstract

The present application provides an optical laminate (1) comprising, in order toward one side in the thickness direction, a first film (2), a first adhesive layer (3), a glass sheet (4), a second adhesive layer (5), and a second film (6). The one side in the thickness direction is the visible side. In the following pen drop breakage test, the drop height H1 of the pen until the glass sheet (4) starts to break is 20 cm or more. In the pen drop breakage test, an adhesive layer (12) having a thickness of 15 μm and a shear storage modulus G' of 0.03 MPa at 25°C, which is obtained by a dynamic viscoelasticity test with a frequency of 1 Hz, a temperature increase rate of 5°C / min, a temperature range of -40°C to 150°C, and a torsion mode, is provided on the other side in the thickness direction of the first film (2), and a 10 g pen is dropped toward the second film (6) at a drop height of 1 cm per time up to 30 cm, and the height at which breakage of the glass sheet (4) is confirmed is obtained as the height H1 in the pen drop breakage test, or, when breakage of the glass sheet (4) cannot be confirmed at a drop height of the pen of 30 cm, it is determined that the laminate has a peeling durability of 30 cm or more.

Description

Technical Field

[0001] This invention relates to an optical laminate comprising a glass plate. Background Technology

[0002] Optical laminates comprising a glass plate, an adhesive layer, and a cellulose triacetate film are known (see, for example, Patent Document 1 below). The glass plate exhibits excellent optical properties, but suffers from low impact resistance. Impact resistance is the property of suppressing damage, including cracks, in the glass plate when subjected to impact.

[0003] The optical laminate described in Patent Document 1 can be fitted into an organic EL display. For the optical laminate described in Patent Document 1, the pencil hardness of a glass plate can be measured. The pencil hardness is measured by directly contacting the lead of a pencil with the surface of the glass plate (exposed surface) and evaluating the presence or absence of surface damage. Therefore, when the optical laminate described in Patent Document 1 is fitted into an organic EL display, the glass plate is positioned on the viewable side, and the cellulose triacetate film is positioned on the organic EL component side.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-25899 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In recent years, there has been a demand for higher levels of impact resistance.

[0009] Problem Solving Methods

[0010] To this end, the inventors of this application conducted in-depth research and discovered a novel optical laminate in which a second film is disposed on the visible side of the glass plate and a first film is disposed on the opposite side of the visible side of the glass plate. They also found that such an optical laminate has excellent impact resistance.

[0011] The present invention (1) includes an optical laminate having a first film, a first adhesive layer, a glass plate, a second adhesive layer and a second film sequentially disposed on one side in the thickness direction, wherein the side in the thickness direction is the visible side, and in the pen drop breakage test described below, the pen drop height H1 until the glass plate begins to break is 20 cm or more.

[0012] <Pen Breaking Experiment>

[0013] An adhesive layer is placed on the other side of the optical laminate in the thickness direction. A 7g ballpoint pen with a ball diameter of 0.7mm is dropped onto the second film. The drop height of the pen is increased by 1cm each time until it reaches 30cm. The height at which the glass plate can be confirmed to break is taken as the height H1 in the pen drop breakage test. Alternatively, if the glass plate cannot be confirmed to break when the pen is dropped from a height of 30cm, it is judged to have a breakage durability of 30cm or more. The thickness of the adhesive layer is 15μm, and the shear storage modulus G' at 25°C is 0.03MPa, which is obtained by dynamic viscoelasticity test in torsion mode with a frequency of 1Hz, a heating rate of 5°C / min, a temperature of -40°C to 150°C.

[0014] The present invention (2) includes the optical laminate described in (1), wherein, in the pen drop test described below, the pen drop height H2 until the first film or the second film begins to peel is 20 cm or more.

[0015] <Pen-Pulling Experiment>

[0016] The adhesive layer is disposed on the other side of the optical laminate in the thickness direction. A 7g ballpoint pen with a ballpoint diameter of 0.7mm is dropped onto the second film, and the drop height is increased by 1cm each time up to 30cm. The height at which peeling can be confirmed on either the first or second film is taken as the height H2 in the pen-drop peel test. Alternatively, if cracking can be confirmed on the glass plate, it is judged to have peel durability of cracking height H1 or higher.

[0017] Alternatively, if no peeling is detected on the first and second films mentioned above when the pen falls from a height of 30 cm, it is judged to have peeling durability of 30 cm or more.

[0018] The present invention (3) includes the optical laminate described in (1) or (2), wherein the average value of the second film at -100°C to -50°C, obtained by dynamic viscoelasticity test at a frequency of 10 Hz, a heating rate of 2°C / min, and a stretching mode, is 0.8 or more and 1.5 or less than the average value of the first film at -100°C to -50°C, obtained by dynamic viscoelasticity test.

[0019] The present invention (4) includes the optical laminate as described in any one of (1) to (3), wherein the average value of the first film obtained by dynamic viscoelasticity test in a tensile mode at a frequency of 10 Hz, a heating rate of 2 °C / min, is 0.04 or more, and the average value of the tensile storage modulus E' of the first film obtained by the dynamic viscoelasticity test at a tensile mode is 3 GPa or more and 6 GPa or less.

[0020] The present invention (5) includes the optical laminate as 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.

[0021] The present invention (6) includes the optical laminate described in any one of (1) to (5), wherein the first film and the second film are cellulose triacetate films.

[0022] The present invention (7) includes the optical laminate described in (6), wherein the second film is thicker than the first film.

[0023] The present invention (8) includes the optical laminate described in (7), which further comprises a hard coating disposed on one side of the second film in the thickness direction described above.

[0024] The effects of the invention

[0025] The optical laminate of the present invention has a second film disposed on the visible side. In the pen drop test, the drop height H1 of the pen until the glass plate begins to break is more than 20 cm, thus exhibiting excellent impact resistance. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of one embodiment of the optical laminate of the present invention.

[0027] Figure 2 A~ Figure 2 C is an explanatory diagram of the method for measuring the contact force. Figure 2 A is the way the blade tip of the device cuts into the first membrane. Figure 2 B is the method of measuring the adhesion between the first film and the first adhesive layer by reaching the interface between the blade tip and the first adhesive layer. Figure 2 C is the method of measuring the adhesion between the glass plate and the first adhesive layer by reaching the interface between the blade tip and the glass plate.

[0028] Figure 3 It has Figure 1 A cross-sectional view of an organic electroluminescent display device with an optical laminate shown.

[0029] Symbol Explanation

[0030] 1 Optical laminate

[0031] 2. First membrane

[0032] 3 First adhesive layer

[0033] 4 glass plates

[0034] 5. Second adhesive layer

[0035] 6. Second membrane

[0036] 12 Adhesive Layer

[0037] 29 entries

[0038] 38 Hard coating Detailed Implementation

[0039] <Optical Laminate 1>

[0040] Reference Figures 1-3 An embodiment of the optical laminate of the present invention will be described.

[0041] The optical laminate 1, for example, has a flat plate shape extending along the surface direction. The surface direction is orthogonal to the thickness direction of the optical laminate 1. The optical laminate 1 is mounted on an organic electroluminescent display device 10 (see reference). Figure 3 When the optical laminate 1 is positioned on the side where the user makes visual identification, i.e., the visible side (hereinafter referred to as the visible side), it is provided sequentially with a first film 2, a first adhesive layer 3, a glass plate 4, a second adhesive layer 5 and a second film 6 on one side in the thickness direction.

[0042] One side in the thickness direction is the visible side. The other side in the thickness direction is the opposite side of the visible side (hereinafter referred to as the opposite side).

[0043] <First Membrane 2>

[0044] The first film 2 extends along the surface direction. The first film 2 forms the other side (opposite side) of the optical laminate 1 in the thickness direction.

[0045] The average value of tanδ of the first film 2 at -100℃ to -50℃, determined by a dynamic viscoelastic test at a frequency of 10Hz, a heating rate of 2℃ / min, a data acquisition interval of 0.5min, and a tensile mode, is, for example, 0.02 or more, preferably 0.04 or more, and further, for example, 0.20 or less, preferably less than 0.06, and more preferably 0.05 or less. If the average value of tanδ of the first film 2 at -100℃ to -50℃ is higher than the lower limit mentioned above, the impact resistance of the optical laminate 1 can be improved. The average value of tanδ of the first film 2 at -100℃ to -50℃ is an indicator characterizing the responsiveness of the optical laminate 1 when an object collides with it at high speed. The higher the average value of tanδ, the more effectively the first film 2 can mitigate the impact on the glass plate 4 even when the object collides with it at high speed, thus improving the impact resistance of the optical laminate 1. The dynamic viscoelastic test is described in the embodiments described later.

[0046] The average value of the tensile storage modulus E' of the first film 2 at -100℃ to -50℃, determined by a dynamic viscoelastic test at a frequency of 10Hz, a heating rate of 2℃ / min, and a tensile mode, is, for example, 3GPa or more, preferably 4GPa or more, and further preferably 10GPa or less, preferably 6GPa or less, more preferably 5GPa or less, and even more preferably 4.7GPa or less. If the average value of the tensile storage modulus E' of the first film 2 at -100℃ to -50℃ is above the aforementioned lower limit, the impact resistance of the optical laminate 1 can be improved.

[0047] Examples of first membranes 2 include polyester films and cellulose films. Examples of polyester films include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN). Examples of cellulose films include cellulose acetate films, specifically cellulose triacetate (TAC) films. From the viewpoint of improving the adhesion between the first membrane 2 and the first adhesive layer 3, cellulose films are preferred, and TAC films are more preferred.

[0048] 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 at or above the aforementioned lower limit, 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, further preferably 80 μm or less, particularly preferably 50 μm or less, most preferably 30 μm or less, and 23 μm or less is suitable.

[0049] 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.

[0050] <First adhesive layer 3>

[0051] The first adhesive layer 3 extends along the surface direction. The first adhesive layer 3 is disposed on one side of the first film 2 in the thickness direction. Specifically, the first adhesive layer 3 is in contact with one side of the first film 2 in the thickness direction. The first adhesive layer 3 is not an adhesive layer (pressure-sensitive adhesive layer) formed by an adhesive (pressure-sensitive adhesive), but a cured product of a curable adhesive. Specifically, the first adhesive layer 3 is a cured product of a curable adhesive that undergoes a curing reaction through irradiation or heating by active energy rays.

[0052] The curing adhesive is the curing material for the first adhesive layer 3. Examples of curing adhesives include energy-curing adhesives and thermosetting adhesives, with energy-curing adhesives being the preferred type. Specifically, examples of curing adhesives include acrylic adhesive compositions, epoxy adhesive compositions, and silicone adhesive compositions. From the viewpoint of obtaining excellent impact resistance, epoxy adhesive compositions are an example.

[0053] The epoxy adhesive composition contains an epoxy resin as the main component. Examples of epoxy resins include difunctional epoxy resins containing two epoxy groups and polyfunctional epoxy resins containing three or more epoxy groups. These epoxy resins can be used alone or in combination of two or more.

[0054] The combination of bifunctional epoxy resins and multifunctional epoxy resins is a preferred example.

[0055] Examples of bifunctional epoxy resins include: bisphenol type epoxy resins, phenolic varnish type epoxy resins, naphthalene type epoxy resins, fluorene type epoxy resins, triphenylmethane type epoxy resins, and other aromatic epoxy resins; nitrogen-containing epoxy resins such as triepoxypropyl isocyanurate and hydantoin epoxy resins; and aliphatic epoxy resins, glycidyl ether type epoxy resins, and glycidylamine type epoxy resins. Aliphatic epoxy resins are preferably examples of bifunctional epoxy resins. Aliphatic epoxy resins include aliphatic cycloaliphatic epoxy resins. The epoxy equivalent of the bifunctional 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 bifunctional epoxy resin in the epoxy resin is, for example, 80% by mass or more, preferably 90% by mass or more, and also, for example, 99% by mass or less, preferably 97% by mass or less.

[0056] Examples of multifunctional epoxy resins include: phenolic varnish-type epoxy resins, cresol varnish-type epoxy resins, trihydroxyphenylmethane-type epoxy resins, tetraphenylolethane-type epoxy resins, dicyclopentadiene-type epoxy resins, and trifunctional aliphatic epoxy resins. Trifunctional aliphatic epoxy resins are preferred as multifunctional epoxy resins. The epoxy equivalent of the multifunctional 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 multifunctional epoxy resin in the epoxy resin is, for example, 1% by mass or more, preferably 3% by mass or more, and also, for example, 20% by mass or less, preferably 10% by mass or less.

[0057] The proportion of epoxy resin in the epoxy adhesive composition is, for example, 60% by mass or more, preferably 75% by mass or more, and also, for example, 90% by mass or less, preferably 80% by mass or less.

[0058] Commercially available epoxy resins can be used. For aliphatic cycloaliphatic epoxy resins, CELLOXIDE 2021P (manufactured by Daicel Chemical Co., Ltd.) can be used, and for trifunctional aliphatic epoxy resins, EHPE3150 (manufactured by Daicel Chemical Co., Ltd.) can be used.

[0059] Furthermore, if the epoxy adhesive composition is an active energy curing type, it contains a photoacid generator. Examples of photoacid generators include triaryl sulfonium salts. Commercially available photoacid generators can be used; for example, CPI101A (manufactured by San-Apro) can be used as a triaryl sulfonium salt. The proportion of the photoacid generator in the epoxy adhesive composition is, for example, 1% by mass or more, preferably 10% by mass or more, and also, for example, 30% by mass or less, preferably 20% by mass or less.

[0060] In addition, epoxy adhesive compositions may contain additives such as oxetane resins and silane coupling agents in appropriate proportions.

[0061] Examples of oxetane resins include monofunctional oxetanes such as 3-ethyl-3-oxetane-methanol and 2-ethylhexyloxetane, and difunctional oxetanes such as dimethyldioxetane and 3-ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane. Commercially available oxetane resins can be used, such as those manufactured by ARON OXETANE (Toa Synthetic Co., Ltd.).

[0062] Examples of silane coupling agents include epoxy-containing silane coupling agents such as 3-epoxypropoxypropyltrimethoxysilane. Commercially available silane coupling agents are also available, such as the KBM series (manufactured by Shin-Etsu Silicone Co., Ltd.).

[0063] 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, and more preferably 3 μm or less.

[0064] 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.

[0065] 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, and even more preferably 4 GPa or more, and is, for example, 100 GPa or less. The tensile storage modulus E' of the first adhesive layer 3 at 25°C can be determined by measuring the dynamic viscoelasticity in a temperature dispersion mode at a frequency of 1 Hz and a heating rate of 5°C / min. Furthermore, the elastic modulus of the first adhesive layer 3 at 25°C, measured by nanoindentation, is, for example, 1 GPa or more, preferably 2 GPa or more, more preferably 3 GPa or more, and even more preferably 4 GPa or more, and is, for example, 100 GPa or less. The measurement conditions for nanoindentation are as follows.

[0066] Device: Triboindenter (manufactured by Hysitron Inc.)

[0067] Sample size: 10×10mm

[0068] Indenter: Concial (spherical indenter: radius of curvature 10μm)

[0069] Measurement method: Single indentation measurement

[0070] Measurement temperature: 25℃

[0071] Indentation depth of the indenter: 100nm

[0072] Temperature: 25℃

[0073] Analysis: Oliver Pharr analysis based on load-displacement curves

[0074] The adhesion force between the first membrane 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, further preferably 3.5 kN / m or more, particularly preferably 4.0 kN / m or more, most preferably 5.0 kN / m or more, and, for example, 10 kN / m or less. Figure 2 As shown in Figure B, the tip 43 of the blade 42 of the device 41 is inserted into the interface between the first film 2 and the first adhesive layer 3, and the blade 42 is moved along the surface direction. The adhesion force between the first film 2 and the first adhesive layer 3 is determined by measuring the peel strength when the first film 2 is peeled from the first adhesive layer 3. Details of the method for measuring the adhesion force are described in the embodiments described later. If the adhesion force between the first film 2 and the first adhesive layer 3 is above the aforementioned lower limit, peeling of the first film 2 from the first adhesive layer 3 can be suppressed.

[0075] <Glass Plate 4>

[0076] The glass plate 4 extends along the surface direction. The glass plate 4 is located on the side of the first adhesive layer 3 opposite to the first film 2. The glass plate 4 is disposed on one side of the first adhesive layer 3 in the thickness direction.

[0077] Specifically, the glass plate 4 contacts one side of the first adhesive layer 3 in the thickness direction. Thus, the first adhesive layer 3 contacts the other side of the glass plate 4 in the thickness direction and one side of the first film 2 in the thickness direction, bonding (joining) the first film 2 and the glass plate 4 together.

[0078] 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. Commercially available glass plates 4 can be used, such as the G-leaf series (registered trademark, manufactured by Nippon Electric Glass Co., Ltd.).

[0079] 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, for example, 10 kN / m or less. Figure 2 As shown in Figure C, the tip 43 of the blade 42 of the device 41 is inserted into the interface between the glass plate 4 and the first adhesive layer 3, and the blade 42 is moved along the surface direction. The adhesion force between the glass plate 4 and the first adhesive layer 3 is determined by measuring the peel strength when the glass plate 4 is peeled from the first adhesive layer 3. Details of the method for measuring the adhesion force are described in the embodiments described later.

[0080] 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, and 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.

[0081] <Second adhesive layer 5>

[0082] The second adhesive layer 5 extends along the surface direction. The second adhesive layer 5 is disposed on one side of the glass plate 4 in the thickness direction. Specifically, the second adhesive layer 5 is in contact with one side of the glass plate 4 in the thickness direction. The second adhesive layer 5 is not an adhesive layer (pressure-sensitive adhesive layer) formed by an adhesive (pressure-sensitive adhesive), but a cured product of a curable adhesive. Specifically, the second adhesive layer 5 is a cured product of a curable adhesive that undergoes a curing reaction through irradiation or heating by active energy rays. The curing raw materials, thickness, total light transmittance, tensile storage modulus E', and elastic modulus measured by nanoindentation method of the second adhesive layer 5 are the same as those of the first adhesive layer 3.

[0083] 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, for example, 10 kN / m or less. The adhesion force between the glass plate 4 and the second adhesive layer 5 can be determined by the same method as the method for determining the adhesion force between the glass plate 4 and the first adhesive layer 3 described above.

[0084] <Second Membrane 6>

[0085] The second film 6 forms one side (visible side) of the optical laminate 1 in the thickness direction. The second film 6 is located on the side of the second adhesive layer 5 opposite to the glass plate 4. The second film 6 extends along the surface direction. The second film 6 is disposed on one side of the second adhesive layer 5 in the thickness direction. The second film 6 is in contact with one side of the second adhesive layer 5 in the thickness direction. Thus, the second adhesive layer 5 contacts one side of the glass plate 4 in the thickness direction and the other side of the second film 6 in the thickness direction, bonding (joining) the glass plate 4 and the second film 6 together.

[0086] The average tanδ of the second film 6, determined through a dynamic viscoelastic test in tensile mode at a frequency of 10 Hz, a heating rate of 2 °C / min, a data acquisition interval of 0.5 min, is set such that its ratio to the average tanδ of the first film 2 (described later) reaches a specific range. The average tanδ of the second film 6 at -100 °C to -50 °C is, for example, 0.02 or more, preferably 0.04 or more, and also, for example, 0.20 or less, preferably less than 0.06, more preferably 0.05 or less. If the average tanδ of the second film 6 at -100 °C to -50 °C is higher than the aforementioned lower limit, the impact resistance of the optical laminate 1 can be improved. The average tanδ of the second film 6 at -100 °C to -50 °C is an indicator characterizing the responsiveness of the optical laminate 1 when an object collides with it at high speed. The higher the average value of tanδ, the more effectively the second film 6 can mitigate the impact on the glass plate 4 even when the object collides with it at high speed, thus improving the impact resistance of the optical laminate 1. Dynamic viscoelasticity tests are described in the embodiments described later.

[0087] 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, 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.

[0088] The average value of the tensile storage modulus E' of the second film 6 at -100°C to -50°C, determined by a dynamic viscoelastic test at a frequency of 10 Hz, a heating rate of 2°C / min, and a tensile mode, is, for example, 3 GPa or more, preferably 4 GPa or more, and further preferably 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 value of the tensile storage modulus E' of the second film 6 at -100°C to -50°C is above the lower limit mentioned above, the impact resistance of the optical laminate 1 can be improved.

[0089] 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, further preferably 3.5 kN / m or more, particularly preferably 4.0 kN / m or more, and most preferably 5.0 kN / m or more. However, it is, for example, 10 kN / m or less. If the adhesion force between the second film 6 and the second adhesive layer 5 is at or above the aforementioned lower limit, then when an object collides with the second film 6 of the optical laminate 1, peeling at the interface between the second film 6 and the second adhesive layer 5 can be suppressed. The adhesion force between the second film 6 and the second adhesive layer 5 can be determined using the same method as the method described above for measuring the adhesion force between the first film 2 and the first adhesive layer 3.

[0090] As the second membrane 6, the membrane exemplified in the first membrane 2 can be cited as an example. From the viewpoint of improving the adhesion of the second membrane 6 to the second adhesive layer 5 and suppressing the peeling of the second membrane 6 when an object collides with the optical laminate 1, a cellulose membrane is preferred, and a TAC membrane is more preferred.

[0091] As a combination of the first film 2 and the second film 6, the preferred examples are a combination in which the first film 2 is a PET film and the second film 6 is a TAC film, and a combination in which the first film 2 is a TAC film and the second film 6 is a TAC film.

[0092] More preferably, a combination in which the first membrane 2 is a TAC membrane and the second membrane 6 is a TAC membrane is provided, that is, a combination in which the first membrane 2 and the second membrane 6 are both TAC membranes.

[0093] The thickness of the second film 6 is not limited. Preferably, the second film 6 is thicker than the first film 2. Especially when the first film 2 and the second film 6 are both 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, and the peeling of the second film 6 can be suppressed.

[0094] 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 at or above the aforementioned lower limit, the impact resistance of the optical laminate 1 can be improved. Furthermore, 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 at or below the aforementioned upper limit, peeling of the second film 6 when an object collides with the optical laminate 1 can be suppressed.

[0095] 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.

[0096] <Adhesive layer 12>

[0097] The optical laminate 1 may further include an adhesive layer 12, indicated by imaginary lines. The adhesive layer 12 is disposed on the other side of the first film 2 in the thickness direction. Specifically, the adhesive layer 12 is in contact with the other side of the first film 2 in the thickness direction. That is, the optical laminate 1 sequentially comprises 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 on one side in the thickness direction. The adhesive layer 12 is a pressure-sensitive adhesive bonded without a curing reaction.

[0098] The material of the adhesive layer 12 is not limited. Examples of materials for the adhesive layer 12 include: acrylic adhesives, rubber adhesives, vinyl alkyl ether adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluoropolymer adhesives, epoxy adhesives, and polyether adhesives. Acrylic adhesives are preferred. The formulation and properties of the adhesive layer 12 are detailed, for example, in Japanese Patent Application Publication No. 2018-28573.

[0099] The shear storage modulus G' of the adhesive layer 12 at 25°C is, for example, 0.01 MPa or more, and also, for example, 0.20 MPa or less. The shear storage modulus G' can be determined by dynamic viscoelasticity testing in shear (torsion) mode at a frequency of 1 Hz and a heating rate of 5°C / min.

[0100] 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, and more preferably 20 μm or less.

[0101] The thickness of the optical laminate 1 is, for example, 50 μm or more, and also, for example, 300 μm or less.

[0102] <Pen Breaking Experiment>

[0103] In the pen-dropping breakage test, the pen drop height H1 of the optical laminate 1 until the glass plate 4 begins to break is more than 20cm.

[0104] First, the optical laminate 1 is placed on the surface of a horizontal platform (not shown) with respect to a resin film 34 (indicated by imaginary lines). The optical laminate 1 with a thickness of 15 μm is placed on one side of the glass plate 4 in the thickness direction.

[0105] It should be noted that the adhesive layer 12 also serves as a fixing component for securing the optical laminate 1 to the horizontal platform during the pen breakage test. The shear storage modulus G' at 25°C, determined by dynamic viscoelasticity tests in torsion mode at a frequency of 1 Hz, a heating rate of 5°C / min, a temperature range of -40°C to 150°C, is 0.03 MPa.

[0106] like Figure 1 As shown, pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7mm) is dropped towards the second film 6. The mass of pen 29 is 7g. The height from the second film 6 to the tip 32 of pen 29 is 5cm. The tip 32 is pointed downwards. If glass plate 4 does not break due to the drop of pen 29, the height is increased by 1cm each time. The height at which breakage can be confirmed on glass plate 4 is taken as the height H1 in the pen drop breakage test. Alternatively, if breakage cannot be confirmed on glass plate 4 at a drop height of 30cm, it is judged to have peel durability of 30cm or more.

[0107] On the other hand, if the drop height H1 in the pen breakage test is less than 20cm, the optical laminate 1 has low impact resistance.

[0108] On the other hand, the drop height H1 in the pen breakage test is preferably 25cm or more, and more preferably 30cm or more.

[0109] <Pen-Pulling Experiment>

[0110] In the pen-dropping test, the pen 29 dropped from the optical laminate 1 at a height H2 of more than 20 cm until the second film 6 began to peel off.

[0111] The pen-drop peel test was performed in parallel with the pen-drop breakage test described above. First, the optical laminate 1 was placed on the surface of a horizontal platform (not shown) with the resin film 34 (indicated by imaginary lines) in between. Without placing the adhesive layer 12 on the optical laminate 1, the same adhesive layer 12 used in the pen-drop breakage test was placed on one side of the optical laminate 1 in the thickness direction.

[0112] like Figure 1As shown, a pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7mm) is dropped towards the second film 6. The mass of the pen 29 is 7g. The height from the glass plate 4 to the tip 32 of the pen 29 is 5cm. The tip 32 is pointed downwards. If no peeling occurs between the first film 2 and the first adhesive layer 3, between the glass plate 4 and the first adhesive layer 3, between the glass plate 4 and the second adhesive layer 5, or between the second film 6 and the second adhesive layer 5 due to the drop of the pen 29, the height is increased by 1cm each time. The height at which any peeling can be confirmed is taken as the height H2 in the pen drop peel test. Alternatively, if a breakage can be confirmed on the glass plate 4, it is judged to have peel durability at a breakage height H1 or higher. Alternatively, if no peeling is confirmed at a drop height of 30cm, it is judged to have peel durability at 30cm or higher.

[0113] The optical laminate 1, which satisfies the above requirements, exhibits high adhesion between the first film 2 and the first adhesive layer 3, high adhesion between the glass plate 4 and the first adhesive layer 3, high adhesion between the second adhesive layer 5 and the glass plate 4, and high adhesion between the second film 6 and the second adhesive layer 5. Therefore, the optical laminate 1 has excellent reliability.

[0114] <Method for manufacturing optical laminate 1>

[0115] The manufacturing method of the optical laminate 1 will be described. In the manufacturing method of the optical laminate 1, for example, a curable adhesive is applied (coated) to the other side of the glass plate 4 in the thickness direction and / or to one side of the first film 2 in the thickness direction, and the curable adhesive is sandwiched between the glass plate 4 and the first film 2. A curable adhesive is applied (coated) to one side of the glass plate 4 in the thickness direction and / or to the other side of the second film 6 in the thickness direction, and the curable adhesive is sandwiched between the glass plate 4 and the second film 6.

[0116] Then, the two curing adhesives are cured. If the curing adhesive is an energy-curing type, it is irradiated with energy including ultraviolet light. If the curing adhesive is a thermosetting type, it is heated. This forms a first adhesive layer 3 and a second adhesive layer 5. The first adhesive layer 3 firmly bonds the first film 2 and the glass plate 4. The second adhesive layer 5 firmly bonds the glass plate 4 and the second film 6.

[0117] Thus, an optical laminate 1 comprising 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.

[0118] Then, to further include an adhesive layer 12 in the optical laminate 1, an adhesive layer 12 is disposed on the other side in the thickness direction of the first film 2. For example, a varnish containing adhesive is applied to the other side in the thickness direction of the first film 2 and dried. Alternatively, the adhesive layer 12 formed on a release liner (not shown) can be transferred to the other side in the thickness direction of the first film 2. Thus, 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. It should be noted that a release liner (not shown) may also be included in the optical laminate 1. In this case, the optical laminate 1 has a release liner (not shown), 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.

[0119] <Applications of Optical Laminate 1>

[0120] The optical laminate 1 can be used for various optical applications, for example, it can be configured in an image display device. Examples of image display devices include organic electroluminescent display devices (hereinafter referred to as "organic EL display devices").

[0121] Next, refer to Figure 3 An organic EL display device 10 having an optical laminate 1 will be described.

[0122] <Organic EL Display Device 10>

[0123] The organic EL display device 10 has a flat plate shape extending along the surface direction. Because it includes the conductive film 13, which will be described below, the organic EL display device 10 functions as a touch panel type input display device. The organic EL display device 10 includes, in sequence towards the surface: an optical laminate 1, a conductive film 13, a second adhesive layer 14, and an image display member 15. It should be noted that in this organic EL display device 10, the upper side of the paper surface is the user's viewing side, i.e., the surface side (equivalent to...). Figure 1 The other side in the thickness direction), the bottom side of the paper is the back side (equivalent to the ...). Figure 1 (One side in the thickness direction).

[0124] <Optical Laminate 1>

[0125] The optical laminate 1 comprises, in sequence, 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 on the surface side (visible side).

[0126] <Conductive film 13>

[0127] The conductive film 13 has a conductive layer 16 and a substrate layer 17 sequentially on the back side.

[0128] <Conductive layer 16>

[0129] The conductive layer 16 has a given pattern. The surface and sides 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, and metals. Examples of metal oxides include composite oxides. Examples of composite oxides include indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium gallium oxide (IGO), indium tin oxide (ITO), and antimony tin 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 at the center in the planar direction and lead-out wiring portions 19 located around the sensor electrode portion 18. Details of the conductive layer 16 are described, for example, in Japanese Patent Application Publication No. 2017-102443, Japanese Patent Application Publication No. 2014-113705, and Japanese Patent Application Publication No. 2014-219667.

[0130] <Substrate Layer 17>

[0131] A substrate layer 17 is disposed on the back side of the conductive layer 16 and the back side of the adhesive layer 12. The substrate layer 17 extends along the surface direction. The substrate layer 17 is, for example, a resin layer. Examples of materials for the substrate layer 17 include: olefin resins, polyester resins, (meth)acrylic resins, polycarbonate resins, polyethersulfone resins, polyaryl ester resins, melamine resins, polyamide resins, polyimide resins, cellulose resins, and polystyrene resins. Examples of olefin resins include: polyethylene, polypropylene, and cyclic olefin polymers (COP). Examples of polyester resins include: PET, PBT, and PEN. Examples of (meth)acrylic resins include: poly(meth)acrylic ester resins. Detailed information about the substrate layer 17 is described, for example, in Japanese Patent Application Publication No. 2018-181722.

[0132] <Second Adhesive Layer 14>

[0133] 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 that of the adhesive layer 12.

[0134] <Image display component 15>

[0135] The image display component 15 forms the back side of the organic EL display device 10. The image display component 15 is disposed on the back side of the conductive film 13 via a second adhesive layer 14. The image display component 15 extends along the surface direction. Specifically, the image display component 15 is an organic EL element. Although not illustrated, for example, the image display component 15 includes a display substrate, two electrodes, an organic EL layer sandwiched between the two electrodes, and a sealing layer. It should be noted that the structure and properties of the image display component 15 are described in detail, for example, in Japanese Patent Application Publication No. 2018-28573.

[0136] <Effects of one implementation method>

[0137] One embodiment of the optical laminate 1 has a novel configuration in which the second film 6 is disposed on the visible side of the glass plate 4 and the first film 2 is disposed on the opposite side of the glass plate 4. Furthermore, in a pen-dropping breakage test, the optical laminate 1 exhibits a pen drop height H1 of 20 cm or more until the glass plate 4 begins to break. Therefore, the optical laminate 1 demonstrates excellent impact resistance.

[0138] Furthermore, it is preferable that, in a pen-dropping test, the pen drop height H2 of the optical laminate 1 is 20 cm or more until the first film 2 or the second film 6 begins to peel off. Therefore, the optical laminate 1 exhibits excellent reliability.

[0139] Furthermore, for the optical laminate 1, when 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 impact absorption behavior between the first film 2 and the second film 6 can be reduced. Therefore, peeling of either the first film 2 or the second film 6 can be suppressed. As a result, the optical laminate 1 exhibits excellent reliability.

[0140] Furthermore, for this optical laminate 1, when the average tanδ value of the first film 2 at -100℃ to -50℃ is 0.04 or higher, and the average tensile storage modulus E' of the first film 2 at -100℃ to -50℃, determined by dynamic viscoelasticity testing, is 3 GPa or higher and 6 GPa or lower, it can suppress the breakage of the glass plate 4 in the pen-drop breakage test. Therefore, the optical laminate 1 exhibits excellent impact resistance.

[0141] Furthermore, for this optical laminate 1, when 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, the adhesion force of the first film 2 relative to the glass plate 4 and the adhesion force of the second film 6 relative to the glass plate 4 are excellent. Therefore, the optical laminate 1 has excellent reliability.

[0142] Furthermore, if the first film 2 and the second film 6 in the optical laminate 1 are both TAC films, then the adhesion of the first film 2 to the first adhesive layer 3 and the adhesion of the second film 6 to the second adhesive layer 5 are excellent. Therefore, the optical laminate 1 has excellent reliability.

[0143] Furthermore, if the second film 6 is thicker than the first film 2, the resistance of the first film 2 can be reduced relative to the impact absorption behavior of the second film 6. As a result, peeling of either the first film 2 or the second film 6 can be suppressed. Therefore, the optical laminate 1 has excellent reliability.

[0144] <Variation Example>

[0145] In the following variations, the same reference numerals are used for the same components and processes as in the first embodiment described above, and detailed descriptions are omitted. Furthermore, unless otherwise specified, the variations can achieve the same effects as the first embodiment.

[0146] In one embodiment, the first membrane 2 is a single layer, but the number of layers in the first membrane 2 is not limited. The first membrane 2 may also be multilayered.

[0147] In one embodiment, the second membrane 6 is a single layer, but the number of layers in the second membrane 6 is not limited. The second membrane 6 may also be multilayered.

[0148] like Figure 1 As shown by the dashed line, the optical laminate 1 may further include a hard coating layer 38. The hard coating layer 38 is disposed on one side of the second film 6 in the thickness direction. The hard coating layer 38 is in contact with the thickness direction side of the second film 6. The optical laminate 1, facing the visible side, sequentially includes a first film 2, a first adhesive layer 3, a glass plate 4, a second adhesive layer 5, a second film 6, and a hard coating layer 38. The formulation, properties, and dimensions of the hard coating layer 38 are not particularly limited. In this modified example, because the optical laminate 1 includes the hard coating layer 38, the impact resistance and scratch resistance of the optical laminate 1 can be improved.

[0149] It can also replace the hard coating 38 to have other functional layers, or even further to have other functional layers. Examples of other functional layers include anti-scattering layers, anti-fouling layers, and anti-reflective layers. These layers can be single layers or multiple layers stacked together.

[0150] The optical laminate of the present invention exhibits excellent impact resistance, thus providing sufficient impact resistance even for glass plates with a thickness of less than 40 μm. Furthermore, due to the excellent flexibility of glass plates with a thickness of less than 40 μm, the optical laminate of the present invention is also suitable for use in flexible displays such as foldable and rollable displays.

[0151] Example

[0152] The specific numerical values ​​of proportions (including proportions), physical properties, parameters, etc., used in the following description can be replaced by the corresponding upper limit values ​​(defined in the form of "less than" or "less than") or lower limit values ​​(defined in the form of "more than" or "exceeding") of the proportions (including proportions), physical properties, parameters, etc., described in the "Specific Embodiments" above. Furthermore, unless otherwise specified, "parts" and "%" in the following description refer to mass measurements.

[0153] In the following examples and comparative examples, an optical laminate 1 was manufactured, and then an adhesive layer 12 was disposed on the optical laminate 1. The impact resistance and peel resistance of the optical laminate 1 were evaluated.

[0154] Example 1

[0155] A glass plate 4 (G-leaf) with a thickness of 30 μm, a first membrane 2 (DIAFOIL S100, manufactured by Mitsubishi Chemical Corporation) with a thickness of 25 μm made of polyethylene terephthalate membrane, and a second membrane 6 (KC4UYW, manufactured by Konica Minolta) with a thickness of 40 μm made of cellulose triacetate membrane (KC4UYW, manufactured by Konica Minolta) were prepared. In addition, an epoxy adhesive composition (curing type adhesive) was prepared by combining 70 parts by weight of aliphatic cycloaliphatic epoxy resin (CELLOXIDE2021P, epoxy equivalent 128-133 g / eq., manufactured by Daicel Chemical Co., Ltd.), 5 parts by weight of trifunctional aliphatic epoxy resin (EHPE3150, epoxy equivalent 170-190 g / eq., manufactured by Daicel Chemical Co., Ltd.), 19 parts by weight of oxetane resin (ARON OXETANE, manufactured by Toa Synthetic Co., Ltd.), 4 parts by weight of silane coupling agent (KBM-403, 3-epoxypropoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd.), and 2 parts by weight of photoacid generator (CPI101A, triarylsulfonium salt, manufactured by San-Apro Co., Ltd.). This epoxy adhesive composition was sandwiched between a glass plate 4 and a first membrane 2. Additionally, the epoxy adhesive composition is sandwiched between the glass plate 4 and the second film 6. An acrylic adhesive composition coated on one side of the glass plate 4 is sandwiched between the glass plate 4 and the second film 6. An acrylic adhesive composition coated on the other side of the glass plate 4 is sandwiched between the glass plate 4 and the second film 2.

[0156] Then, the two curable adhesives were irradiated with ultraviolet light. This resulted in the formation of a first adhesive layer 3 with a thickness of 1 μm and a second adhesive layer 5 with a thickness of 1 μm. The first adhesive layer 3 was formed from a cured material that strongly bonded the first film 2 and the glass plate 4. The elastic modulus of the first adhesive layer 3 at 25°C, measured by nanoindentation, was 4.9 GPa. The second adhesive layer 5 was formed from a cured material that strongly bonded the second film 6 and the glass plate 4. The elastic modulus of the second adhesive layer 5 at 25°C, measured by nanoindentation, was also 4.9 GPa.

[0157] Thus, an optical laminate 1 is manufactured having a first film 2, a first adhesive layer 3, a glass plate 4, a second adhesive layer 5 and a second film 6 sequentially on one side in the thickness direction.

[0158] Next, an adhesive layer 12 with a thickness of 15 μm is deposited on the other side of the first film 2 in the thickness direction by transfer printing. The adhesive layer 12 is prepared as described below.

[0159] By combining 43 parts by weight of lauryl acrylate (LA), 44 parts by weight of 2-ethylhexyl acrylate (2EHA), 6 parts by weight of 4-hydroxybutyl acrylate (4HBA), 7 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 0.015 parts by weight of BASF's "IRGACURE 184", and irradiating with ultraviolet light to carry out polymerization, a basic polymer composition (polymerization rate: approximately 10%) was obtained.

[0160] Separately, 60 parts by weight of dicyclopentyl methacrylate (DCPMA), 40 parts by weight of methyl methacrylate (MMA), 3.5 parts by weight of α-thioglycerol, and 100 parts by weight of toluene were mixed and stirred at 70°C for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added, and the mixture was reacted at 70°C for 2 hours, followed by a further reaction at 80°C for 2 hours. The reaction solution was then heated to 130°C, and the toluene, chain transfer agent, and unreacted monomers were dried to remove them, yielding a solid acrylic oligomer. The weight-average molecular weight of the acrylic oligomer was 5100. The glass transition temperature (Tg) was 130°C.

[0161] An adhesive composition was prepared by adding 0.07 parts by weight of 1,6-hexanediol diacrylate (HDDA), 1 part by weight of acrylic oligomer, and 0.3 parts by weight of silane coupling agent (Shin-Etsu Chemical "KBM403") to 100 parts by weight of the solid components of the base polymer composition, and then mixing them uniformly.

[0162] An adhesive composition was coated onto the surface of a release sheet made of PET film (Mitsubishi Chemical "DIAFOIL MRF75"), and then another release sheet made of PET film (Mitsubishi Chemical "DIAFOIL MRF75") was bonded to the coating. The coating was then irradiated with ultraviolet light 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 determination method is described below.

[0163] The adhesive layer 12 was machined into a disc shape and sandwiched between parallel plates. 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.

[0164] [condition]

[0165] Pattern: Twist

[0166] Temperature: -40℃~150℃

[0167] Heating rate: 5℃ / min

[0168] Frequency: 1Hz

[0169] Example 2

[0170] 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.

[0171] Example 3

[0172] The optical laminate 1 was manufactured in the same manner as in Example 2. However, the second film 6 was replaced with a cellulose triacetate film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0173] Example 4

[0174] The optical laminate 1 was manufactured in the same manner as in Example 1. However, the second film 6 was replaced with a cellulose triacetate film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0175] Example 5

[0176] The optical laminate 1 was manufactured in the same manner as in Example 3. However, the first film 2 was replaced with a cellulose triacetate film (KC4UYW, manufactured by Konica Minolta) with a thickness of 40 μm.

[0177] Example 6

[0178] The optical laminate 1 was manufactured in the same manner as in Example 1. However, the first film 2 was replaced with a cellulose triacetate film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0179] Example 7

[0180] The optical laminate 1 was manufactured in the same manner as in Example 5. However, the first film 2 was replaced with a cellulose triacetate film (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0181] Comparative Example 1

[0182] An optical laminate 1 was manufactured in the same manner as in Example 3. However, the optical laminate 1 does not include the first film 2 and the first adhesive layer 3. The optical laminate 1 includes a glass plate 4, a second adhesive layer 5, and a second film 6.

[0183] Comparative Example 2

[0184] An optical laminate 1 was manufactured in the same manner as in Example 5. However, the optical laminate 1 does not include the second adhesive layer 5 and the second film 6. The optical laminate 1 includes a first film 2, a first adhesive layer 3, and a glass plate 4.

[0185] Table 1 describes the types and thicknesses of the first membrane 2 and the second membrane 6 in each embodiment and comparative example.

[0186] <Evaluation>

[0187] For each embodiment and comparative example, the following aspects were measured and evaluated. The results are recorded in Table 1.

[0188] <tanδ and tensile storage modulus E' of membrane 2 and membrane 6>

[0189] The first membrane 2 and the second membrane 6 prepared in each embodiment and comparative example were used for dynamic viscoelasticity testing. The apparatus and conditions are described below.

[0190] Apparatus: Hitachi High-Tech Science Co., Ltd., Multifunctional Dynamic Viscoelasticity Measuring Apparatus DMS6100

[0191] Temperature range: -100~200℃

[0192] Heating rate: 2℃ / min

[0193] Mode: Stretch

[0194] Sample width: 10mm

[0195] Chuck spacing: 20mm

[0196] Frequency: 10Hz

[0197] Strain amplitude: 10 μm

[0198] Atmosphere: Atmospheric (250ml / min)

[0199] Data acquisition interval: 0.5 min (per 1℃)

[0200] The average tensile storage modulus E' of the first membrane 2 at -100℃ to -50℃ was calculated by dividing the sum of all the data obtained above at -100℃ to -50℃ by the number of data points. The average tanδ of the first membrane 2 at -100℃ to -50℃ was calculated by dividing the sum of all the data obtained above at -100℃ to -50℃ by the number of data points. The average tanδ of the second membrane 6 was calculated in the same manner.

[0201] <The adhesion between the first membrane 2 and the first adhesive layer 3, and the adhesion between the second membrane 6 and the second adhesive layer 5>

[0202] The adhesion between the first film 2 and the first adhesive layer 3 was measured using a surface / interface property analysis apparatus under the following apparatus, conditions, and methods.

[0203] Device: Surface / interface physical property analysis device (SAICAS DN-20 type) manufactured by DAIPLA WINTES Co., Ltd.

[0204] Blade 42 material: Single-crystal diamond

[0205] Width of blade tip 43: 1mm

[0206] The rake angle of the blade tip 43 is 10°.

[0207] Surface / interface property analysis device 41, such as Figure 2 As shown in Figure A, the device includes a cutting edge 42, a moving device (not shown), and a pressure measuring unit. The cutting edge 42 is movable. The cutting edge 42 has a blade tip 43 formed at its front end.

[0208] like Figure 2 As shown in Figure A, the optical laminate 1 is placed on the measuring device 41.

[0209] The blade tip 43 is moved obliquely to one side of the thickness direction along the horizontal direction (corresponding to the surface direction of the optical laminate 1). The horizontal velocity is 10 μm / sec, and the vertical velocity is 0.5 μm / sec.

[0210] Therefore, the blade tip 43 cuts into the first membrane 2.

[0211] like Figure 2 As shown in Figure B, 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 velocity is maintained at 10 μm / sec. Through the horizontal movement of the blade tip 43, the first film 2 is peeled off from the first adhesive layer 3. The peel strength at this point is measured as the adhesion force between the first film 2 and 3.

[0212] Similarly, the adhesion force between the second film 6 and the second adhesive layer 5 was determined.

[0213] <The adhesion between the first adhesive layer 3 and the glass plate 4, and the adhesion between the glass plate 4 and the second adhesive layer 5>

[0214] The adhesion force between the first adhesive layer 3 and the glass plate 4 was measured using the same apparatus, conditions, and methods as described above. It should be noted that, as... Figure 2 As shown in Figure C, after the blade tip 43 cuts into the first film 2, it also cuts into the first adhesive layer 3. When the blade tip 43 reaches the interface between the first adhesive layer 3 and the glass plate 4, it is moved horizontally. Thus, the first adhesive layer 3 peels off from the glass plate 4. The peel strength at this point is 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 is 4.5 kN / m.

[0215] Similarly, the adhesion force between the glass plate 4 and the second adhesive layer 5 was calculated. The adhesion force between the glass plate 4 and the second adhesive layer 5 is 4.5 kN / m.

[0216] <Pen Breaking Experiment>

[0217] The following pen-drop breakage test was performed on the optical laminates 1 of each embodiment and comparative example. First, as... Figure 1 As shown, the optical laminate 1 is placed on the surface of the resin film 34 (imaginary line) with the second film 6 facing upwards. Specifically, the adhesive layer 12 is adhered to the surface of the resin film 34. The resin film 34 is Prescale (Fujifilm Prescale MS medium-pressure single-sheet type, 95μm thick). The resin film 34 is disposed on the surface of a horizontal platform (not shown). Next, a pen drop test is conducted by dropping a 7g ballpoint pen 29 with a ball diameter of 0.7mm from a height of 5cm above the second film 6. The aforementioned height of 5cm 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 faces downwards and is sharp. For this optical laminate 1, if the glass plate 4 breaks due to the aforementioned drop of the pen 29, the height H1 of the pen drop test is 5cm. If the glass plate 4 does not break, the height is increased by 1cm each time. Thus, the height H1 at which the glass plate 4 breaks is obtained.

[0218] <Pen-Pulling Experiment>

[0219] Similar to the pen-dropping test described above, the pen 29 is dropped onto the second film 6. The initial drop height is set to 5 cm. Then, if no peeling occurs between the second film 6 and the second adhesive layer 5, between the glass plate 4 and the second adhesive layer 5, between the glass plate 4 and the first adhesive layer 3, or between the first film 2 and the first adhesive layer 3, the height is increased by 1 cm each time. The height at which the aforementioned peeling can be confirmed is taken as the height H2 in the pen-dropping test. Alternatively, if a breakage can be confirmed on the glass plate 4, it is determined to have peel durability at a breakage height H1 or higher. Alternatively, if the aforementioned peeling cannot be confirmed even at a drop height of 30 cm for the pen 29, it is determined to have "peel durability at 30 cm or higher".

[0220]

[0221] It should be noted that the above-described invention is provided as an exemplary embodiment of the present invention, but it is merely an example and not intended to be limiting. Those skilled in the art will understand that variations of the present invention are included in the appended claims.

[0222] Industrial applicability

[0223] Optical laminates can be fitted into image display devices.

Claims

1. An optical laminate, comprising, sequentially on one side in the thickness direction, a first film, a first adhesive layer, a glass plate, a second adhesive layer, and a second film. The thickness of the first adhesive layer is less than 5 μm. One side in the thickness direction is the visible side. In the pen-drop breakage test described below, the pen's drop height H1 until the glass plate begins to break is 20 cm or more. <Pen Breaking Experiment> An adhesive layer is placed on the other side of the optical laminate in the thickness direction. A 7g ballpoint pen with a ball diameter of 0.7mm is dropped onto the second film. The drop height of the pen is increased by 1cm at a time up to 30cm. The height at which the glass plate can be confirmed to break is taken as the height H1 in the pen drop breakage test. Alternatively, if the glass plate cannot be confirmed to break at a drop height of 30cm, it is judged to have a breakage durability of more than 30cm. The thickness of the adhesive layer is 15μm, and the shear storage modulus G' at 25℃, determined by a dynamic viscoelastic test at a frequency of 1Hz, a heating rate of 5℃ / min, a temperature of -40℃ to 150℃, and a torsional mode, is 0.03MPa.

2. The optical laminate according to claim 1, wherein, In the pen-dropping test described below, the pen drop height H2 until the first or second film begins to peel is 20 cm or more. <Pen-Pulling Experiment> The adhesive layer is positioned on the other side of the optical laminate in the thickness direction. A 7g ballpoint pen with a ballpoint diameter of 0.7mm is dropped onto the second film. The drop height is increased by 1cm at a time up to 30cm. The height at which peeling is confirmed on either the first or second film is taken as the height H2 in the pen-drop peel test. Alternatively, if cracking is confirmed on the glass plate, it is determined to have peel durability at a crack height H1 or higher. Alternatively, if no peeling is detected on the first and second films when the pen falls from a height of 30 cm, it is determined that the peeling durability is greater than 30 cm.

3. The optical laminate according to claim 1 or 2, wherein, The ratio of the average tanδ of the second membrane at -100℃ to -50℃, obtained by dynamic viscoelasticity testing at a frequency of 10Hz, a heating rate of 2℃ / min, and a tensile mode, to the average tanδ of the first membrane at -100℃ to -50℃, obtained by the same dynamic viscoelasticity test, is 0.8 or more and 1.5 or less.

4. The optical laminate according to claim 1 or 2, wherein, The average value of tanδ of the first membrane at -100℃ to -50℃, determined by dynamic viscoelasticity test at a frequency of 10Hz, a heating rate of 2℃ / min, and a tensile mode, is greater than or equal to 0.

04. The average value of tensile storage modulus E' of the first membrane at -100℃ to -50℃, determined by the above dynamic viscoelasticity test, is greater than or equal to 3GPa and less than 6GPa.

5. The optical laminate according to claim 1 or 2, wherein, The adhesion force between the first membrane and the first adhesive layer is greater than 3.0 kN / m. The adhesion force between the first adhesive layer and the glass plate is greater than 3.0 kN / m. The adhesion force between the glass plate and the second adhesive layer is greater than 3.0 kN / m. The adhesion force between the second adhesive layer and the second film is greater than 3.0 kN / m.

6. The optical laminate according to claim 1 or 2, wherein, The first membrane and the second membrane are both cellulose triacetate membranes.

7. The optical laminate according to claim 6, wherein, The second membrane is thicker than the first membrane.

8. The optical laminate according to claim 1 or 2, further comprising a hard coating disposed on one side of the second film in the thickness direction.

Images