Optical laminate

Abstract

The present application provides an optical laminate (1) having a glass sheet (2), an adhesive layer (3), and a film (4) in this order toward one side in the thickness direction, the one side in the thickness direction being a visible side. In the following pen drop breakage test, the drop height H1 of the pen until the glass sheet (2) starts to break is 15 cm or more. In the pen drop breakage test, an adhesive layer (12) having a shear storage modulus G' of 0.03 MPa and a thickness of 15 μm is provided on the other side in the thickness direction of the optical laminate (1). A ballpoint pen (29) having a weight of 7 g and a ball diameter of 0.7 mm is dropped toward the film (4), and the drop height of the pen is gradually increased, and the height at which breakage of the glass sheet (2) is confirmed is obtained as the height H1 in the pen drop breakage test.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical laminate provided with a glass sheet. BACKGROUND

[0002] An optical laminate provided with a glass sheet, an adhesive layer, and a cellulose triacetate film is known (for example, refer to Patent Literature 1). The optical properties of the glass sheet are excellent, while the impact resistance is low. The impact resistance is a property of suppressing the generation of damage including cracks in the glass sheet when the glass sheet is impacted.

[0003] The optical laminate described in Patent Literature 1 can be equipped in an organic EL display. For the optical laminate described in Patent Literature 1, the pencil hardness of the glass sheet can be measured. The pencil hardness is measured by bringing the lead of a pencil into direct contact with the surface (exposed surface) of the glass sheet and evaluating the presence or absence of damage to the surface. Therefore, when the optical laminate described in Patent Literature 1 is equipped in an organic EL display, the glass sheet is disposed on the visible side, and the cellulose triacetate film is disposed on the organic EL member side.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2019-25899 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In recent years, higher levels of impact resistance are required.

[0009] MEANS FOR SOLVING THE PROBLEMS

[0010] As a result of intensive studies by the present inventors and others, a new type of optical laminate provided with a film on the visible side was found, and it was found that such an optical laminate has excellent impact resistance.

[0011] The present application (1) includes an optical laminate provided with a glass sheet, an adhesive layer, and a film in this order toward one side in a thickness direction,

[0012] The one side in the thickness direction is the visible side,

[0013] In the following pen drop breakage test, the drop height H1 of the pen until the glass sheet starts to break is 15 cm or more.

[0014] <Pen Drop Breakage Test>

[0015] An adhesive layer was disposed on the other face in the thickness direction of the optical laminate, a ball-point pen of 7 g and a ball diameter of 0.7 mm was dropped on the film, the dropping height of the pen was increased by 1 cm each time, and the height at which the film could be confirmed to be peeled off was taken as the height H2 in the pen peeling test. The thickness of the adhesive layer was 15 μm, and the shear storage modulus G' of the film at 25°C, which was obtained by a dynamic viscoelasticity test at a frequency of 1 Hz, a temperature increase rate of 5°C / min, a temperature of -40°C to 150°C, and a torsion mode, was 0.03 MPa.

[0016] The present application (2) includes the optical laminate described in (1), wherein

[0017] In the following pen peeling test, the dropping height H2 of the pen until the film started to peel off was 15 cm or more,

[0018] <Pen peeling test>

[0019] An adhesive layer was disposed on the other face in the thickness direction of the optical laminate, a ball-point pen of 7 g and a ball diameter of 0.7 mm was dropped on the film, the dropping height of the pen was increased by 1 cm each time, and the height at which the film could be confirmed to be peeled off was taken as the height H2 in the pen peeling test. The thickness of the adhesive layer was 15 μm, and the shear storage modulus G' of the film at 25°C, which was obtained by a dynamic viscoelasticity test at a frequency of 1 Hz, a temperature increase rate of 5°C / min, a temperature of -40°C to 150°C, and a torsion mode, was 0.03 MPa.

[0020] The present application (3) includes the optical laminate described in (1) or (2), wherein

[0021] The average value of tan δ of the film at -100°C to -50°C, which was obtained by a dynamic viscoelasticity test at a frequency of 10 Hz, a temperature increase rate of 2°C / min, and a stretching mode, was 0.04 or more, and the average value of the tensile storage modulus E' of the film at -100°C to -50°C, which was obtained by the dynamic viscoelasticity test, was 3 GPa or more and 6 GPa or less.

[0022] The present application (4) includes the optical laminate described in any one of (1) to (3), wherein

[0023] The adhesion of the glass plate to the adhesive layer was 3.0 kN / m or more,

[0024] The adhesion of the film to the adhesive layer was 3.0 kN / m or more.

[0025] The present application (5) includes the optical laminate described in any one of claims (1) to (4), wherein

[0026] The film was a cellulose triacetate film.

[0027] The present application (6) includes the optical laminate described in (5), wherein

[0028] The film has a thickness of 10 μm or more and 60 μm or less.

[0029] The present application (7) includes the optical laminate described in any one of claims (1) to (6), further provided with a hard coat layer disposed on one face of the film in the thickness direction thereof.

[0030] Effects of the Invention

[0031] The optical laminate of the present application is provided with a film on the visual side, and in a pen drop break test, the drop height Hl of the pen until the glass plate starts to break is 15 cm or more, and thus the impact resistance is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a cross-sectional view of one embodiment of the optical laminate of the present application.

[0033] Figure 2 A ~ Figure 2 C is an explanatory view of a method for measuring the adhesion. Figure 2 A is a method in which the blade tip of the device is cut into the film. Figure 2 B is a method in which the blade tip reaches the interface between the film and the adhesive layer and the adhesion thereof is measured. Figure 2 C is a method in which the blade tip reaches the interface between the glass plate and the adhesive layer and the adhesion thereof is measured.

[0034] Figure 3 is a cross-sectional view of an organic electroluminescent display device provided with Figure 1 is a cross-sectional view of an organic electroluminescent display device provided with

[0035] SYMBOL EXPLANATION

[0036] 1 Optical laminate

[0037] 2 Glass plate

[0038] 3 Adhesive layer

[0039] 4 Film

[0040] 29 Pen

[0041] 38 Hard coat layer DETAILED DESCRIPTION

[0042] <Optical Laminate 1>

[0043] REFERENCE Figures 1 to 3 One embodiment of the optical laminate of the present application will be described.

[0044] 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 in use, it is positioned on the side where the user makes visual identification, i.e., the visible side (hereinafter referred to as the visible side). The optical laminate 1 comprises, in sequence, a glass plate 2, an adhesive layer 3, and a film 4 on one side in the thickness direction. The 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).

[0045] <Glass Plate 2>

[0046] Glass plate 2 extends along the surface direction. Glass plate 2 forms the other side (opposite side) of optical laminate 1 in the thickness direction. The total light transmittance of glass plate 2 is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less. Commercially available glass plate 2 can be used, for example, the G-leaf series (registered trademark, manufactured by Nippon Electric Glass Co., Ltd.).

[0047] The thickness of the glass plate 2 is not limited. The thickness of the glass plate 2 is, for example, 1 μm or more, preferably 10 μm or more, and more preferably 20 μm. The thickness of the glass plate 2 is 100 μm or less, preferably 80 μm or less, more preferably 60 μm or less, and even more preferably 50 μm or less.

[0048] <Adhesive Layer 3>

[0049] The adhesive layer 3 extends along the surface direction. The adhesive layer 3 is disposed on one side of the glass plate 2 in the thickness direction. Specifically, the adhesive layer 3 is in contact with one side of the glass plate 2 in the thickness direction. The 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. More specifically, the adhesive layer 3 is a cured product of a curable adhesive that undergoes a curing reaction through irradiation or heating by active energy rays.

[0050] The curing adhesive is the curing material for 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.

[0051] 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.

[0052] The combination of bifunctional epoxy resins and multifunctional epoxy resins is a preferred example.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] In addition, epoxy adhesive compositions may contain additives such as oxetane resins and silane coupling agents in appropriate proportions.

[0059] 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.).

[0060] 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.).

[0061] The thickness of the adhesive layer 3 is not limited. The thickness of the adhesive layer 3 is, for example, 0.1 μm or more, and also, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less.

[0062] The total light transmittance of the adhesive layer 3 is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less.

[0063] The tensile storage modulus E' of the adhesive layer 3 at 25°C is, for example, 1 GPa or more, preferably 2 GPa or more, more preferably 3 GPa or more, and even more preferably 4 GPa or more, and is, for example, 100 GPa or less. The tensile storage modulus E' of the 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 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.

[0064] Device: Triboindenter (manufactured by Hysitron Inc.)

[0065] Sample size: 10×10mm

[0066] Indenter: Concial (spherical indenter: radius of curvature 10μm)

[0067] Measurement method: Single indentation measurement

[0068] Measurement temperature: 25℃

[0069] Indentation depth of the indenter: 100nm

[0070] Temperature: 25℃

[0071] Analysis: Oliver Pharr analysis based on load-displacement curves

[0072] The adhesion force between the glass plate 2 and the adhesive layer 3 is, for example, 3.0 kN / m or more, preferably 3.5 kN / m or more, more preferably 4.0 kN / m or more, and also, for example, 10 kN / m or less, preferably 8 kN / m or less. If the adhesion force between the glass plate 2 and the adhesive layer 3 is above the aforementioned lower limit, peeling at the interface between the glass plate 2 and the adhesive layer 3 can be suppressed when an object collides with the optical laminate 1. Therefore, the optical laminate 1 has excellent reliability.

[0073] like 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 2 and the adhesive layer 3, and the blade 42 is moved along the surface direction. The adhesion force between the glass plate 2 and the adhesive layer 3 is determined by measuring the peel strength when the glass plate 2 is peeled from the adhesive layer 3. Details of the method for measuring the adhesion force are described in the following embodiments.

[0074] <Membrane 4>

[0075] Film 4 forms one side (visible side) of the optical laminate 1 in the thickness direction. Film 4 is located on the side of the adhesive layer 3 opposite to the glass plate 2. Film 4 extends along the surface direction.

[0076] The membrane 4 is disposed on one side of the adhesive layer 3 in the thickness direction. The membrane 4 is in contact with one side of the adhesive layer 3 in the thickness direction. Thus, the adhesive layer 3 is in contact with one side of the glass plate 2 in the thickness direction and the other side of the membrane 4 in the thickness direction, bonding (joining) the glass plate 2 and the membrane 4 together.

[0077] The average value of tanδ of film 4 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 film 4 at -100℃ to -50℃ is higher than the lower limit mentioned above, the impact resistance of optical laminate 1 can be improved. The average value of tanδ of film 4 at -100℃ to -50℃ is an indicator characterizing the responsiveness of optical laminate 1 when an object collides with it at high speed. The higher the average value of tanδ, the more effectively film 4 can mitigate the impact on glass plate 2 even when an object collides with it at high speed, thus improving the impact resistance of optical laminate 1. The dynamic viscoelastic test is described in the following embodiments.

[0078] The average value of the tensile storage modulus E' of the film 4 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 film 4 at -100℃ to -50℃ is above the lower limit mentioned above, the impact resistance of the optical laminate 1 can be improved.

[0079] The adhesion force between the membrane 4 and the adhesive layer 3 is, for example, 0.5 kN / m or more, preferably 1.5 kN / m or more, more preferably 3.0 kN / m or more, 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 membrane 4 and the adhesive layer 3 is at or above the aforementioned lower limit, then when an object collides with the membrane 4 of the optical laminate 1, peeling at the interface between the membrane 4 and the adhesive layer 3 can be suppressed. Figure 2 As shown in Figure B, the tip 43 of the blade 42 of the measuring device 41 is inserted into the interface between the film 4 and the adhesive layer 3, and the blade 42 is moved along the surface direction. The adhesion force between the film 4 and the adhesive layer 3 is determined by measuring the peel strength when the film 4 is peeled from the adhesive layer 3. Details of the method for measuring the adhesion force are described in the following embodiments.

[0080] Examples of membranes 4 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 of membrane 4 to the adhesive layer 3 and suppressing the peeling of membrane 4 when an object collides with the optical laminate 1, cellulose films are preferred, and TAC films are more preferred.

[0081] The thickness of film 4 is not limited. The thickness of film 4 is, for example, 10 μm or more, preferably 30 μm or more. If the thickness of film 4 is at or above the aforementioned lower limit, the impact resistance of the optical laminate 1 can be improved. Alternatively, the thickness of film 4 is, for example, 200 μm or less, preferably 100 μm or less, more preferably 60 μm or less. If the thickness of film 4 is at or below the aforementioned upper limit, peeling of film 4 when an object collides with the optical laminate 1 can be suppressed.

[0082] The total light transmittance of the membrane 4 is, for example, 80% or more, preferably 85% or more, and also, for example, 99% or less.

[0083] <Adhesive layer 12>

[0084] 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 glass plate 2 in the thickness direction. Specifically, the adhesive layer 12 is in contact with the other side of the film 4 in the thickness direction. That is, the optical laminate 1 sequentially comprises the adhesive layer 12, the glass plate 2, the adhesive layer 3, and the film 4 on one side in the thickness direction. The adhesive layer 12 is a pressure-sensitive adhesive bonded without a curing reaction.

[0085] 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.

[0086] 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.

[0087] The thickness of the adhesive layer 12 is, for example, 5 μm or more, preferably 10 μm or more, and also, for example, 50 μm or less, preferably 30 μm or less, and more preferably 20 μm or less.

[0088] The thickness of the optical laminate 1 is, for example, 25 μm or more, and also, for example, 200 μm or less.

[0089] <Pen Breaking Experiment>

[0090] In the pen-dropping breakage test, the pen drop height H1 of the optical laminate 1 until the glass plate 2 begins to break is, for example, 15 cm or more.

[0091] First, the optical laminate 1 is placed on the surface of a horizontal platform (not shown) through a resin film 34 (indicated by imaginary lines). An adhesive layer 12 with a thickness of 15 μm is placed on one side of the optical laminate 1 in the thickness direction. It should be noted that this adhesive layer 12 also serves as a fixing member for securing the optical laminate 1 to the horizontal platform during the pen-drop fracture test. The shear storage modulus G' at 25 °C, determined through a dynamic viscoelastic test at a frequency of 1 Hz, a heating rate of 5 °C / min, a temperature range of -40 °C to 150 °C, and a torsional mode, is 0.03 MPa.

[0092] like Figure 1 As shown, pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7mm) is dropped towards membrane 4. The mass of pen 29 is 7g. The height from glass plate 2 to the tip 32 of pen 29 is 5cm. The tip 32 is pointed downwards. If glass plate 2 does not break due to the drop of pen 29, the height is gradually increased by 1cm each time. The height at which breakage can be observed in glass plate 2 is taken as the height H1 in the pen breakage test.

[0093] If the drop height H1 in the pen breakage test is 15cm or more, the optical laminate 1 has excellent impact resistance.

[0094] The drop height H1 in the pen breakage test is preferably 20cm or more.

[0095] <Pen-Pulling Experiment>

[0096] In the pen-dropping test, the pen 29 falls at a height H2 of, for example, 15 cm or more until the film 4 begins to peel off.

[0097] First, the optical laminate 1 is placed on the surface of a horizontal platform (not shown) with the resin film 34 (indicated by imaginary lines) in between. An adhesive layer 12, identical to the adhesive layer 12 used in the pen-drop breakage test, is placed on one side of the optical laminate 1 in the thickness direction.

[0098] likeFigure 1 As shown, a pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7mm) is dropped towards the film 4. The mass of the pen 29 is 7g. The height from the glass plate 2 to the tip 32 of the pen 29 is 5cm. The tip 32 is pointed downwards. If the film 4 does not peel off from the adhesive layer 3 due to the dropping of the pen 29, the height is gradually increased by 1cm each time. The height at which peeling of the film 4 from the adhesive layer 3 can be confirmed is taken as the height H2 in the pen drop peel test. Alternatively, if the glass plate 2 breaks, it is judged to have peel durability of breaking height H1 or higher.

[0099] The preferred drop height H2 in the pen-peeling test is 20cm or more.

[0100] In the optical laminate 1 that meets the above requirements, the film 4 has a high adhesion to the adhesive layer 3. Therefore, the optical laminate 1 has excellent reliability.

[0101] <Method for manufacturing optical laminate 1>

[0102] 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 first applied (coated) on one side of the glass plate 2 in the thickness direction and / or the other side of the film 4 in the thickness direction, and then the curable adhesive is sandwiched between the glass plate 2 and the film 4.

[0103] Then, the curing adhesive is cured. If the curing adhesive is an energy-curing type, it is irradiated with energy including ultraviolet light. Specifically, ultraviolet light is irradiated onto the curing adhesive from the glass plate 2 side. If the curing adhesive is a thermosetting type, it is heated. Thus, an adhesive layer 3 is formed that strongly bonds the glass plate 2 and the film 4.

[0104] Thus, an optical laminate 1 having a glass plate 2, an adhesive layer 3, and a film 4 is obtained.

[0105] Then, to further include an adhesive layer 12 in the optical laminate 1, the adhesive layer 12 is disposed on the other side of the glass plate 2 in the thickness direction. For example, a varnish containing adhesive is applied to the other side of the glass plate 2 in the thickness direction and dried. Alternatively, the adhesive layer 12 formed on a release liner (not shown) can be transferred to the other side of the glass plate 2 in the thickness direction. Thus, an optical laminate 1 having an adhesive layer 12, a glass plate 2, an adhesive layer 3, and a film 4 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 glass plate 2, an adhesive layer 3, and a film 4.

[0106] <Applications of Optical Laminate 1>

[0107] 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").

[0108] Next, refer to Figure 3 An organic EL display device 10 having an optical laminate 1 will be described.

[0109] <Organic EL Display Device 10>

[0110] 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, facing backwards, comprises, in sequence: 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 surface of the paper 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).

[0111] <Optical Laminate 1>

[0112] The optical laminate 1 has an adhesive layer 12, a glass plate 2, an adhesive layer 3 and a film 4 in sequence on the surface side.

[0113] <Conductive film 13>

[0114] The conductive film 13 has a conductive layer 16 and a substrate layer 17 sequentially on the back side.

[0115] <Conductive layer 16>

[0116] 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.

[0117] <Substrate Layer 17>

[0118] 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.

[0119] <Second Adhesive Layer 14>

[0120] 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.

[0121] <Image Display Component 15>

[0122] 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.

[0123] <Effects of one implementation method>

[0124] One embodiment of the optical laminate 1 has a novel configuration in which the film 4 is disposed on the visible side and the glass plate 2 is disposed on the opposite side. Furthermore, in a pen-dropping breakage test, the optical laminate 1 exhibits a pen drop height H1 of 15 cm or more until the glass plate begins to break. Therefore, the optical laminate 1 demonstrates excellent impact resistance.

[0125] Furthermore, in the pen-dropping test, the pen drop height H2 of the optical laminate 1 before the film 4 begins to peel is more than 15 cm. Therefore, the film 4 exhibits excellent adhesion. Consequently, the optical laminate 1 demonstrates excellent reliability.

[0126] Furthermore, the average tanδ of film 4 at -100℃ to -50℃ is 0.04 or higher, and the average tensile storage modulus E' of film 4 at -100℃ to -50℃ is 3 GPa or higher and 6 GPa or lower. Therefore, it can suppress the breakage of glass plate 2 in pen breakage test. Thus, the optical laminate 1 has excellent impact resistance.

[0127] Furthermore, in this optical laminate 1, the adhesion between the glass plate 2 and the adhesive layer 3 is 3.0 kN / m or more, and the adhesion between the film 4 and the adhesive layer 3 is 3.0 kN / m or more. Therefore, the adhesion between the film 4 and the glass plate 2 and the adhesive layer 3 is excellent. Consequently, the optical laminate 1 exhibits excellent reliability.

[0128] In addition, if membrane 4 is a TAC membrane, it has excellent adhesion to adhesive layer 3.

[0129] Therefore, the optical laminate 1 has excellent reliability.

[0130] In addition, if the thickness of the film 4 is less than 60 μm, it is possible to suppress the peeling of the film 4 from the adhesive layer 3 when the object collides with the optical laminate 1.

[0131] In addition, the optical laminate of the present invention has excellent impact resistance, so even glass plates with a thickness of less than 40 μm have sufficient impact resistance.

[0132] <Variation Example>

[0133] 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.

[0134] In one embodiment, membrane 4 is a single layer, but the number of layers in membrane 4 is not limited.

[0135] Membrane 4 can also be multilayered.

[0136] 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 film 4 in the thickness direction. The hard coating layer 38 is in contact with the side of the film 4 in the thickness direction. The optical laminate 1 includes a glass plate 2, an adhesive layer 3, a film 4, and a hard coating layer 38 in sequence towards the visible side. The formulation, properties, and dimensions of the hard coating layer 38 are not particularly limited. In this modified example, since the optical laminate 1 includes the hard coating layer 38, the impact resistance and scratch resistance of the optical laminate 1 can be improved.

[0137] 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.

[0138] 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.

[0139] Example

[0140] 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.

[0141] 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, and the impact resistance of the optical laminate 1 was evaluated.

[0142] Example 1

[0143] A glass plate 2 (G-leaf) with a thickness of 30 μm and a membrane 4 (DIAFOIL S100, manufactured by Mitsubishi Chemical Corporation) with a thickness of 50 μm made of polyethylene terephthalate film were prepared. In addition, an epoxy adhesive composition was prepared by combining 70 parts by weight of aliphatic cycloaliphatic epoxy resin (CELLOXIDE 2021P, 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 coated onto a glass plate 2, and then the epoxy adhesive composition was sandwiched between the glass plate 2 and the membrane 4.

[0144] Then, ultraviolet light is irradiated onto the curing adhesive from the glass plate 2 side. This forms an adhesive layer 3 with a thickness of 1 μm, formed from the cured material, that strongly bonds the glass plate 2 and the film 4. The elastic modulus of the adhesive layer 3 at 25°C, measured by nanoindentation, is 4.9 GPa. Thus, an optical laminate 1 comprising the glass plate 2, the adhesive layer 3, and the film 4 is manufactured.

[0145] Next, an adhesive layer 12 with a thickness of 15 μm is transferred onto the other side of the glass plate 2 in the thickness direction. The adhesive layer 12 is prepared as described below.

[0146] 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.

[0147] 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. Then, the reaction mixture was 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.

[0148] 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.

[0149] 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.

[0150] 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.

[0151] [condition]

[0152] Pattern: Twist

[0153] Temperature: -40℃~150℃

[0154] Heating rate: 5℃ / min

[0155] Frequency: 1Hz

[0156] Example 2

[0157] The optical laminate 1 was manufactured in the same manner as in Example 1. However, the membrane 4 was replaced with a cellulose triacetate membrane (KC4UYW, manufactured by Konica Minolta) with a thickness of 40 μm.

[0158] Example 3

[0159] The optical laminate 1 was manufactured in the same manner as in Example 1. However, the membrane 4 was replaced with a cellulose triacetate membrane (KC2CT, manufactured by Konica Minolta) with a thickness of 20 μm.

[0160] Example 4

[0161] The optical laminate 1 was manufactured in the same manner as in Example 2. However, the membrane 4 was replaced with a cellulose triacetate membrane (KC8UAW, manufactured by Konica Minolta) with a thickness of 80 μm.

[0162] Comparative Example 1

[0163] The optical laminate 1 was manufactured in the same manner as in Example 1. The film 4 was an acrylic film obtained by extruding methacrylic acid resin granules having glutarimide ring units into a film shape and then stretching it. The acrylic film had a thickness of 40 μm.

[0164] Table 1 lists the types and thicknesses of membrane 4 in each embodiment and comparative example.

[0165] <Evaluation>

[0166] For each embodiment and comparative example, the following aspects were measured and evaluated. The results are recorded in Table 1.

[0167] <tanδ and tensile storage modulus E' of membrane 4>

[0168] The membrane 4 prepared in each embodiment and comparative example was used for dynamic viscoelasticity testing. The apparatus and conditions are described below.

[0169] Apparatus: Hitachi High-Tech Science Co., Ltd., Multifunctional Dynamic Viscoelasticity Measuring Apparatus DMS6100

[0170] Temperature range: -100~200℃

[0171] Heating rate: 2℃ / min

[0172] Mode: Stretch

[0173] Sample width: 10mm

[0174] Chuck spacing: 20mm

[0175] Frequency: 10Hz

[0176] Strain amplitude: 10 μm

[0177] Atmosphere: Atmospheric (250ml / min)

[0178] Data acquisition interval: 0.5 min (per 1℃)

[0179] The average tensile storage modulus E' of membrane 4 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 membrane 4 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.

[0180] <Adhesion strength between membrane 4 and adhesive layer 3>

[0181] The adhesion between membrane 4 and adhesive layer 3 was measured using a surface / interface property analysis apparatus under the following apparatus, conditions, and methods.

[0182] Device: Surface / interface physical property analysis device (SAICAS DN-20 type) manufactured by DAIPLA WINTES Co., Ltd.

[0183] Blade 42 material: Single-crystal diamond

[0184] Width of blade tip 43: 1mm

[0185] The rake angle of the blade tip 43 is 10°.

[0186] Surface / interface property analysis device 41, such as Figure 2 As shown in Figure A, the device includes a blade 42, a moving device (not shown), and a pressure measuring unit. The blade 42 is movable. The blade 42 has a blade tip 43 formed at its lower end.

[0187] like Figure 2 As shown in Figure A, the optical laminate 1 is placed on the measuring device 41. At this time, the film 4 is placed on the upper side and the glass plate 2 is placed on the lower side.

[0188] The blade tip 43 is moved obliquely downwards in 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. Thus, the blade tip 43 cuts into the film 4.

[0189] like Figure 2 As shown in Figure B, when the blade tip 43 reaches the interface between the membrane 4 and the 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 membrane 4 is peeled off from the adhesive layer 3. The peel strength at this point is measured as the adhesion force between the membrane 4 and the adhesive layer 3.

[0190] <Adhesion strength between glass plate 2 and adhesive layer 3>

[0191] The adhesion force between the glass plate 2 and the adhesive layer 3 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 film 4, it also cuts into the adhesive layer 3. When the blade tip 43 reaches the interface between the adhesive layer 3 and the glass plate 2, the blade tip 43 is moved horizontally. Thus, the adhesive layer 3 peels off from the glass plate 2. The peel strength at this point is measured as the adhesion force between the glass plate 2 and the adhesive layer 3.

[0192] <Pen Breaking Experiment>

[0193] 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 film 4 facing upwards. Specifically, the adhesive layer 12 is adhered to the surface of the resin film 34. The resin film 34 is a 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 breakage test is conducted by dropping a 7g pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7mm) from a height of 5cm above the film 4. The aforementioned height of 5cm is the distance between one side of the film 4 in the thickness direction and the tip 32 of the pen 29. The tip 32 faces downwards and is sharp. For this optical laminate 1, if the glass plate 2 breaks due to the aforementioned drop of the pen 29, the height H1 of the pen breakage test is 5cm. If the glass plate 2 does not break, the height is gradually increased by 1cm each time. Thus, the height H1 at which the glass plate 2 breaks is obtained.

[0194] <Pen-Pulling Experiment>

[0195] Similar to the pen-drop test described above, pen 29 is dropped onto film 4. The initial drop height is set to 5 cm. Then, if no peeling of film 4 from adhesive layer 3 occurs, the height is gradually increased by 1 cm each time. The height at which peeling of film 4 from adhesive layer 3 can be confirmed is taken as the height H2 in the pen-drop test. Alternatively, if glass plate 2 breaks, it is determined to have peel durability at a break height H1 or higher.

[0196] Table 1

[0197]

[0198] 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.

[0199] Industrial applicability

[0200] Optical laminates can be fitted into image display devices.

Claims

1. An optical laminate, comprising, sequentially on one side in the thickness direction, a glass plate, an adhesive layer, and a film. The adhesive layer is a cured product of a curable adhesive. The curing adhesive is an epoxy adhesive composition containing epoxy resin. The epoxy resin includes bifunctional epoxy resins containing two epoxy groups and polyfunctional epoxy resins containing three or more epoxy groups. The epoxy resin in the epoxy adhesive composition accounts for more than 60% by mass. 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 15 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 film. The drop height of the pen is increased by 1cm each time. The height at which the glass plate can be confirmed to break is taken as the height H1 in the pen breakage test. The thickness of the adhesive layer is 15μm, and the shear storage modulus G' at 25℃ is 0.03MPa, which is obtained by dynamic viscoelasticity test at a frequency of 1Hz, a heating rate of 5℃ / min, a temperature of -40℃ to 150℃, and a torsional mode.

2. The optical laminate according to claim 1, wherein, In the pen-dropping test described below, the pen drop height H2 until the film begins to peel is 15 cm or more. <Pen-Pulling Experiment> The 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 film. The drop height of the pen is gradually increased to 30cm. The height at which peeling is confirmed on the film is taken as the height H2 in the pen peel test. Alternatively, if the glass plate breaks, it is judged to have peel durability of breaking height H1 or higher.

3. The optical laminate according to claim 1 or 2, wherein, The average tanδ value of the 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 0.

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

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

5. The optical laminate according to claim 1 or 2, wherein, The membrane is a cellulose triacetate membrane.

6. The optical laminate according to claim 5, wherein, The membrane has a thickness of 10 μm or more and 60 μm or less.

7. The optical laminate according to any one of claims 1 to 6, further comprising a hard coating disposed on one side of the film in the thickness direction.

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