JP2022083451A - Optical laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel optical laminate excellent in impact resistance.

SOLUTION: There is provided an optical laminate 1 which comprises a glass plate 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 is a visible side. In the pen-drop cracking test described below, a pen drop height H1 at which the glass plate 2 begins to crack is 15 cm or more. <Pen-Drop Cracking Test> An adhesive layer 12 having a shear storage modulus G' of 0.03 MPa and a thickness of 15 μm is disposed on the other surface in the thickness direction of the optical laminate 1. A pen 29 with a ball having a weight of 7 g and a ball diameter of 0.7 mm is dropped toward the film 4. The pen drop height is gradually increased and a height at which a crack is confirmed in the glass plate 2 is acquired as a height H1 in the pen-drop cracking test.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an optical laminate including a glass plate.

An optical laminate including a glass plate, an adhesive layer, and a triacetyl cellulose film is known (see, for example, Patent Document 1 below). The glass plate has excellent optical characteristics but low impact resistance. Impact resistance is a property of suppressing damage including cracks in the glass plate when the glass plate is impacted.

The optical laminate described in Patent Document 1 is provided in an organic EL display. In the optical laminate described in Patent Document 1, the pencil hardness of the glass plate is measured. The pencil hardness is measured by bringing the pencil lead into direct contact with the surface (exposed surface) of the glass plate and evaluating the presence or absence of scratches on the surface. Therefore, when the optical laminate described in Patent Document 1 is provided in the organic EL display, the glass plate is arranged on the visual recognition side and the triacetyl cell roll film is arranged on the organic EL member side.

Japanese Unexamined Patent Publication No. 2019-25899

In recent years, a higher level of impact resistance has been required.

Therefore, as a result of diligent studies, the inventors of the present application have found a novel optical laminate in which the film is arranged on the visual recognition side, and have found that the optical laminate is excellent in impact resistance.

In the present invention (1), a glass plate, an adhesive layer, and a film are provided in order toward one side in the thickness direction, the one side in the thickness direction is the visual recognition side, and the glass is described in the pen drop cracking test below. Includes an optical laminate in which the drop height H1 of the pen until the plate begins to crack is 15 cm or more.

<Pen drop crack test>
The shear storage elastic modulus G'at a frequency of 1 Hz, a heating rate of 5 ° C./min, a temperature of −40 ° C. to 150 ° C., and a shear storage elastic modulus of 25 ° C. obtained by a dynamic viscoelasticity test in a torsion mode is 0.03 MPa, and the thickness is 15 μm. The pressure-sensitive adhesive layer is arranged on the other surface of the optical laminate in the thickness direction. A 7 g ball pen having a ball diameter of 0.7 mm is dropped toward the film. The drop height of the pen is raised by 1 cm, and the height when cracks are confirmed in the glass plate is obtained as the height H1 in the pen drop crack test.

The present invention (2) includes the optical laminate according to (1), wherein the drop height H2 of the pen until the film starts to peel in the following pen drop peeling test is 15 cm or more.
<Pen drop peeling test>
The pressure-sensitive adhesive layer is arranged on the other surface of the optical laminate in the thickness direction. A 7 g ball pen having a ball diameter of 0.7 mm is dropped toward the film. The drop height of the pen is gradually increased to 30 cm, and the height when peeling is confirmed on the film is obtained as the height H2 in the pen drop peeling test. Alternatively, when the glass plate is cracked, it is determined that the glass plate has peeling durability having a crack height of H1 or more.

In the present invention (3), the average tan δ of the film at a frequency of 10 Hz, a heating rate of 2 ° C./min, and a dynamic viscoelasticity test in a tensile mode from -100 ° C to -50 ° C is 0.04 or more. The average of the tensile storage elastic modulus E'of the film at −100 ° C. to −50 ° C. determined by the dynamic viscoelasticity test is 3 GPa or more and 6 GPa or less, according to (1) or (2). Includes an optical laminate.

In the present invention (4), the adhesive force between the glass plate and the adhesive layer is 3.0 kN / m or more, and the adhesive force between the film and the adhesive layer is 3.0 kN / m or more. The optical laminate according to any one of (1) to (3) is included.

The present invention (5) includes the optical laminate according to any one of claims (1) to (4), wherein the film is a triacetyl cell roll film.

The present invention (6) includes the optical laminate according to (5), wherein the film has a thickness of 10 μm or more and 60 μm or less.

The present invention (7) includes the optical laminate according to any one of claims (1) to (6), further comprising a hard coat layer arranged on one side of the film in the thickness direction.

The optical laminate of the present invention is excellent in impact resistance because the film is arranged on the visual side and the drop height H1 of the pen until the glass plate starts to crack in the pen drop cracking test is 15 cm or more.

FIG. 1 is a cross-sectional view of an embodiment of the optical laminate of the present invention. 2A to 2C are explanatory views of a method for measuring the adhesion force. FIG. 2A is an embodiment in which the cutting edge of the device is cut into the film. FIG. 2B is an embodiment in which the cutting edge reaches the interface between the film and the adhesive layer, and the adhesion thereof is measured. FIG. 2C shows an embodiment in which the cutting edge reaches the interface between the glass plate and the adhesive layer, and the adhesion thereof is measured. FIG. 3 is a cross-sectional view of an organic electroluminescence display device including the optical laminate shown in FIG.

<Optical laminate 1>
An embodiment of the optical laminate of the present invention will be described with reference to FIGS. 1 to 3.

The optical laminate 1 has, for example, a flat plate shape extending in the plane direction. The plane direction is orthogonal to the thickness direction of the optical laminate 1. When the optical laminate 1 is provided in the organic electroluminescence display device 10 (see FIG. 3), the optical laminate 1 is arranged on the visual recognition side (hereinafter, simply referred to as the visual recognition side) which is the side to be visually recognized by the user. The optical laminate 1 includes a glass plate 2, an adhesive layer 3, and a film 4 in order toward one side in the thickness direction. One side in the thickness direction is the visual recognition side. The other side in the thickness direction is the opposite side of the visual recognition side (hereinafter, simply referred to as the opposite side).

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

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, still more preferably 50 μm or less.

<Adhesive layer 3>
The adhesive layer 3 extends in the plane direction. The adhesive layer 3 is arranged on one side of the glass plate 2 in the thickness direction. Specifically, the adhesive layer 3 comes into contact with one side of the glass plate 2 in the thickness direction. The adhesive layer 3 is not a pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) made of a pressure-sensitive adhesive (pressure-sensitive adhesive), but a cured product of a curable adhesive. Specifically, the adhesive layer 3 is a cured product of a curable adhesive that undergoes a curing reaction by irradiation with active energy rays or heating.

The curable adhesive is a curing raw material for the adhesive layer 3, and examples thereof include an active energy curing type and a thermosetting type, and an active energy curing type is preferable. Specific examples of the curable adhesive include an acrylic adhesive composition, an epoxy adhesive composition, and a silicone adhesive composition. From the viewpoint of obtaining excellent impact resistance, an epoxy adhesive is used. The composition may be mentioned.

The epoxy adhesive composition contains an epoxy resin as a main component. Examples of the epoxy resin include a bifunctional epoxy resin containing two epoxy groups and a polyfunctional epoxy resin containing three or more epoxy groups. These can be used alone or in combination of two or more.
A combination of the bifunctional epoxy resin and the polyfunctional epoxy resin is preferable.

Examples of the bifunctional epoxy resin include aromatic epoxy resins such as bisphenol type epoxy resin, novolak type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, and triphenylmethane type epoxy resin, for example, triepoxypropyl isocyanurate. , Hydant-in epoxy resin and other nitrogen-containing ring epoxy resins, and examples thereof include aliphatic type epoxy resins, glycidyl ether type epoxy resins, and glycidylamine type epoxy resins. As the bifunctional epoxy resin, an aliphatic type epoxy resin is preferable. The aliphatic epoxy resin includes an aliphatic alicyclic epoxy resin. The epoxy equivalent of the bifunctional epoxy resin is, for example, 100 g / eq. As mentioned above, preferably 120 g / eq. The above, and for example, 250 g / eq. Hereinafter, preferably, 150 g / eq. It is as follows. The ratio of the bifunctional epoxy resin in the epoxy resin is, for example, 80% by mass or more, preferably 90% by mass or more, and for example, 99% by mass or less, preferably 97% by mass or less.

Examples of the polyfunctional epoxy resin include phenol novolac type epoxy resin, cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetraphenylol ethane type epoxy resin, dicyclopentadiene type epoxy resin, and trifunctional aliphatic epoxy resin. Examples thereof include polyfunctional epoxy resins having three or more functionalities such as. The polyfunctional epoxy resin is preferably a trifunctional aliphatic epoxy resin. The epoxy equivalent of the polyfunctional epoxy resin is, for example, 130 g / eq. As mentioned above, preferably 150 g / eq. The above, and for example, 220 g / eq. Hereinafter, preferably, 200 g / eq. It is as follows. The proportion of the polyfunctional epoxy resin in the epoxy resin is, for example, 1% by mass or more, preferably 3% by mass or more, and for example, 20% by mass or less, preferably 10% by mass or less.

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

As the epoxy resin, a commercially available product can be used, and as the aliphatic alicyclic epoxy resin, seroxide 2021P (manufactured by Daicel Chemical Co., Ltd.) and EHPE3150 (manufactured by Daicel Chemical Co., Ltd.) are used as the trifunctional aliphatic epoxy resin.

Further, the epoxy adhesive composition contains a photoacid generator if it is an active energy curable type. Examples of the photoacid generator include triarylsulfonium salts and the like. As the photoacid generator, a commercially available product can be used, and CPI101A (manufactured by San Afro) or the like is used as the triarylsulfonium 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 for example, 30% by mass or less, preferably 20% by mass or less.

Further, the epoxy adhesive composition can contain additives such as an oxetane-based resin and a silane coupling agent in an appropriate ratio.

Examples of the oxetane-based resin include monofunctional oxetane such as 3-ethyl-3-oxetanemethanol and 2-ethylhexyloxetane, for example, xylylenebis oxetane, 3-ethyl-3 {[(3-ethyloxetane-3-yl). ) Bifunctional oxetane such as methoxy] methyl} oxetane. As the oxetane-based resin, a commercially available product can be used, and Aron oxetane (manufactured by Toagosei Co., Ltd.) or the like is used.

Examples of the silane coupling agent include an epoxy group-containing silane coupling agent such as 3-glycidoxypropyltrimethoxysilane. As the silane coupling agent, a commercially available product can be used, and examples thereof include KBM series (manufactured by Shin-Etsu Silicone Co., Ltd.).

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 is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less.

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

The tensile storage elastic 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, still more preferably 4 GPa or more, and for example, 100 GPa or less. be. The tensile storage elastic modulus E'of the adhesive layer 3 at 25 ° C. is determined by measuring the dynamic viscoelasticity in a temperature dispersion mode under the conditions of a frequency of 1 Hz and a heating rate of 5 ° C./min. The elastic modulus of the adhesive layer 3 at 25 ° C. measured by the nanoindenter method is, for example, 1 GPa or more, preferably 2 GPa or more, more preferably 3 GPa or more, still more preferably 4 GPa or more, and also. For example, it is 100 GPa or less. The measurement conditions of the nanoindenter method are as follows.

Equipment: Triboinder (manufactured by Hybrid Inc.)
Sample size: 10 x 10 mm
Indenter: Concial (spherical indenter: radius of curvature 10 μm),
Measurement method: Single push measurement Measurement temperature: 25 ° C
Indenter indentation depth: 100 nm
Temperature: 25 ° C
Analysis: Oliver Pharr analysis based on load-displacement curve

The adhesive 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 for example. It is 10 kN / m or less, preferably 8 kN / m or less. When the adhesion between the glass plate 2 and the adhesive layer 3 is equal to or greater than the above-mentioned 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 is excellent in reliability.
As shown in FIG. 2A, the adhesive force between the glass plate 2 and the adhesive layer 3 is as shown in FIG. 2B by inserting the cutting edge 43 of the blade 42 included in the device 41 into the interface between the glass plate 2 and the adhesive layer 3. In addition, the blade 42 is moved along the surface direction to obtain a peeling strength when the glass plate 2 is peeled from the adhesive layer 3. Details of the method for measuring the adhesion force will be described in a later example.

<Film 4>
The film 4 forms one side (visual recognition side surface) of the optical laminate 1 in the thickness direction. The film 4 is located on the opposite side of the glass plate 2 with respect to the adhesive layer 3. The film 4 extends in the plane direction.
The film 4 is arranged on one side of the adhesive layer 3 in the thickness direction. The film 4 is in contact with one side of the adhesive layer 3 in the thickness direction. As a result, the adhesive layer 3 is in contact with one surface of the glass plate 2 in the thickness direction and the other surface of the film 4 in the thickness direction, and the glass plate 2 and the film 4 are bonded (bonded) to each other.

The average tan δ of the film 4 at -100 ° C to -50 ° C determined by a dynamic viscoelasticity test in a frequency of 10 Hz, a heating rate of 2 ° C / min, a data acquisition interval of 0.5 min, and a tensile mode is, for example, 0.02. The above is preferably 0.04 or more, and is, for example, 0.20 or less, preferably less than 0.06, and more preferably 0.05 or less. If the average of tan δ of the film 4 from −100 ° C. to −50 ° C. exceeds the above-mentioned lower limit, the impact resistance of the optical laminate 1 can be improved. The average of the tan δ of the film 4 at −100 ° C. to −50 ° C. is an index showing the responsiveness when the object collides with the optical laminate 1 at high speed. If the average of tan δ is high, even if an object collides with the glass plate 2 at high speed, the film 4 can sufficiently alleviate the impact received by the glass plate 2, and the impact resistance of the optical laminate 1 can be improved. The dynamic viscoelasticity test will be described in later examples.

The average tensile storage elastic modulus E'of the film 4 at a frequency of 10 Hz, a heating rate of 2 ° C./min, and a dynamic viscoelasticity test in a tensile mode from -100 ° C to -50 ° C is, for example, 3 GPa or more, preferably 3 GPa or more. It is 4 GPa or more, and for example, 10 GPa or less, preferably 6 GPa or less, more preferably 5 GPa or less, still more preferably 4.7 GPa or less. When the average tensile storage elastic modulus E'of the film 4 from −100 ° C. to −50 ° C. is equal to or higher than the above-mentioned lower limit, the impact resistance of the optical laminate 1 can be improved.

The adhesion between the film 4 and the adhesive layer 3 is, for example, 0.5 kN / m or more, preferably 1.5 kN / m or more, more preferably 3.0 kN / m or more, still more preferably 3.5 kN. / M or more, particularly preferably 4.0 kN / m or more, most preferably 5.0 kN / m or more, and for example, 10 kN / m or less. When the adhesion between the film 4 and the adhesive layer 3 is equal to or greater than the above lower limit, peeling at the interface between the film 4 and the adhesive layer 3 can be suppressed when an object collides with the film 4 of the optical laminate 1. .. As shown in FIG. 2A, the adhesive force between the film 4 and the adhesive layer 3 is as shown in FIG. 2C by inserting the cutting edge 43 of the blade 42 included in the measuring device 41 into the interface between the film 4 and the adhesive layer 3. , The blade 42 is moved along the surface direction to obtain the peel strength when the film 4 is peeled from the adhesive layer 3. Details of the method for measuring the adhesion force will be described in a later example.

Examples of the film 4 include a polyester film and a cell roll film. Examples of the polyester film include polyethylene terephthalate film (PET), polybutylene terephthalate (PBT) film, and polyethylene naphthalate (PEN) film. Examples of the cell roll film include acetyl cell roll fill, and specific examples thereof include a triacetyl cell roll (TAC) film. As the film 4, a cell roll film is preferable from the viewpoint of increasing the adhesive force of the film 4 to the adhesive layer 3 and suppressing the peeling of the film 4 when an object collides with the optical laminate 1. More preferably, a TAC film can be mentioned.

The thickness of the film 4 is not limited. The thickness of the film 4 is, for example, 10 μm or more, preferably 30 μm or more. When the thickness of the film 4 is at least the above-mentioned lower limit, the impact resistance of the optical laminate 1 can be improved. The thickness of the film 4 is, for example, 200 μm or less, preferably 100 μm or less, and more preferably 60 μm or less. When the thickness of the film 4 is equal to or less than the above-mentioned upper limit, peeling of the film 4 when an object collides with the optical laminate 1 can be suppressed.

The total light transmittance of the film 4 is, for example, 80% or more, preferably 85% or more, and for example, 99% or less.

<Adhesive layer 12>
The optical laminate 1 may further include an adhesive layer 12 represented by a virtual line. The pressure-sensitive adhesive layer 12 is arranged on the other side of the glass plate 2 in the thickness direction. Specifically, the pressure-sensitive adhesive layer 12 is in contact with the other side of the film 4 in the thickness direction. That is, the optical laminate 1 includes the pressure-sensitive adhesive layer 12, the glass plate 2, the adhesive layer 3, and the film 4 in order toward one side in the thickness direction. The pressure-sensitive adhesive layer 12 is an adhesive body that is pressure-sensitively adhered without a curing reaction.

The material of the pressure-sensitive adhesive layer 12 is not limited. Examples of the material of the pressure-sensitive adhesive layer 12 include an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, a polyamide-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, and a fluorine-based pressure-sensitive adhesive. Examples thereof include adhesives, epoxy adhesives, and polyether adhesives. As the material, an acrylic pressure-sensitive adhesive is preferable. The formulation and physical properties of the pressure-sensitive adhesive layer 12 are described in detail in, for example, Japanese Patent Application Laid-Open No. 2018-28873.

The shear storage elastic modulus G'at 25 ° C. of the pressure-sensitive adhesive layer 12 is, for example, 0.01 MPa or more and, for example, 0.20 MPa or less. The shear storage elastic modulus G'is determined by a dynamic viscoelasticity test at a frequency of 1 Hz, a heating rate of 5 ° C./min, and a shear (twist) mode.

The thickness of the pressure-sensitive adhesive layer 12 is, for example, 5 μm or more, preferably 10 μm or more, and for example, 50 μm or less, preferably 30 μm or less, and more preferably 20 μm or less.

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

<Pen drop crack test>
In the optical laminate 1, the drop height H1 of the pen until the glass plate 2 starts to crack in the pen drop cracking test is, for example, 15 cm or more.

First, the optical laminate 1 is arranged on the surface of a horizontal table (not shown) via a resin film 34 shown by a virtual line. The pressure-sensitive adhesive layer 12 having a thickness of 15 μm is arranged on one side of the optical laminate 1 in the thickness direction. The pressure-sensitive adhesive layer 12 also serves as a fixing member for fixing the optical laminate 1 to the horizontal table in the pen drop cracking test. The shear storage elastic modulus G'at a frequency of 1 Hz, a heating rate of 5 ° C./min, a temperature of −40 ° C. to 150 ° C., and a shear storage elastic modulus of 25 ° C. obtained by a dynamic viscoelasticity test in a torsion mode is 0.03 MPa.

As shown in FIG. 1, a pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped toward the film 4. The mass of the pen 29 is 7 g. The height from the glass plate 2 to the tip 32 of the pen 29 is 5 cm. The tip portion 32 faces downward and is sharp. If the glass plate 2 is not cracked due to the above-mentioned drop of the pen 29, the height is gradually increased by 1 cm. The height when the crack is confirmed in the glass plate 2 is acquired as the height H1 in the pen drop crack test.

When the drop height H1 in the pen drop cracking test is 15 cm or more, the impact resistance of the optical laminate 1 is excellent.

The drop height H1 in the pen drop cracking test is preferably 20 cm or more.

<Pen drop peeling test>
In the optical laminate 1, the drop height H2 of the pen 29 until the film 4 starts to peel in the pen drop peeling test is, for example, 15 cm or more.

First, the optical laminate 1 is arranged on the surface of a horizontal table (not shown) via a resin film 34 shown by a virtual line. The same adhesive layer 12 as the adhesive layer 12 used in the pen drop cracking test is arranged on one side of the optical laminate 1 in the thickness direction.

As shown in FIG. 1, a pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped toward the film 4. The mass of the pen 29 is 7 g. The height from the glass plate 2 to the tip 32 of the pen 29 is 5 cm. The tip portion 32 faces downward and is sharp. If the pen 29 does not peel off from the adhesive layer 3 due to the above-mentioned drop, the height is gradually increased by 1 cm. The height when the peeling from the adhesive layer 3 of the film 4 is confirmed is obtained as the height H2 in the pen drop peeling test. Alternatively, when the glass plate 2 is cracked, it is determined that the glass plate 2 has peeling durability having a crack height of H1 or more.

Preferably, the drop height H2 in the pen drop peeling test is 20 cm or more.

The optical laminate 1 that satisfies the above requirements has a high adhesive force to the adhesive layer 3 of the film 4. Therefore, the optical laminate 1 is excellent in reliability.

<Manufacturing method of optical laminate 1>
A method for manufacturing the optical laminate 1 will be described. In the method for manufacturing the optical laminate 1, for example, first, a curable adhesive is placed (applied) on one side of the glass plate 2 in the thickness direction and / or on the other side of the film 4 in the thickness direction, and then the curable adhesive is applied. Then, the curable adhesive is sandwiched between the glass plate 2 and the film 4.

Then, the curable adhesive is cured. If the curable adhesive is an active energy curable type, the curable adhesive is irradiated with active energy including ultraviolet rays. Specifically, the curable adhesive is irradiated with ultraviolet rays from the glass plate 2 side. If the curable adhesive is thermosetting, heat the curable adhesive. As a result, the adhesive layer 3 that firmly adheres the glass plate 2 and the film 4 is formed.

As a result, an optical laminate 1 including a glass plate 2, an adhesive layer 3, and a film 4 is obtained.

After that, in order to further provide the pressure-sensitive adhesive layer 12 on the optical laminate 1, the pressure-sensitive adhesive layer 12 is arranged on the other surface of the glass plate 2 in the thickness direction. For example, a varnish containing an adhesive is applied and dried on the other surface of the glass plate 2 in the thickness direction. Alternatively, the pressure-sensitive adhesive layer 12 formed on the release sheet (not shown) can be transferred to the other surface of the glass plate 2 in the thickness direction. As a result, an optical laminate 1 including the pressure-sensitive adhesive layer 12, the glass plate 2, the adhesive layer 3, and the film 4 is obtained. The optical laminate 1 may be provided with a release sheet (not shown). In that case, the optical laminate 1 includes a release sheet (not shown), an adhesive layer 12, a glass plate 2, an adhesive layer 3, and a film 4.

<Use of optical laminate 1>
The optical laminate 1 is used for various optical applications, and is provided in, for example, an image display device. Examples of the image display device include an organic electroluminescence display device (hereinafter, simply abbreviated as “organic EL display device”).

Next, the organic EL display device 10 including the optical laminate 1 will be described with reference to FIG.

<Organic EL display device 10>
The organic EL display device 10 has a flat plate shape extending in the plane direction. Since the organic EL display device 10 includes the conductive film 13 described below, it functions as a touch panel type input display device. The organic EL display device 10 includes an optical laminate 1, a conductive film 13, a second pressure-sensitive adhesive layer 14, and an image display member 15 in order toward the front side. In the organic EL display device 10, the upper side of the paper surface is the user's visual recognition side, which is the front side (corresponding to the other side in the thickness direction of FIG. 1), and the lower side of the paper surface is the back side (one side in the thickness direction of FIG. 1). Equivalent to).

<Optical laminate 1>
The optical laminate 1 includes an adhesive layer 12, a glass plate 2, an adhesive layer 3, and a film 4 in this order toward the front side.

<Conductive film 13>
The conductive film 13 includes a conductive layer 16 and a base material layer 17 in order toward the back side.

<Conductive layer 16>
The conductive layer 16 has a predetermined pattern. The surface and sides of the conductive layer 16 come into contact with the pressure-sensitive adhesive layer 12. Examples of the material of the conductive layer 16 include metal oxides, conductive fibers (fibers), and metals. Examples of the metal oxide include composite oxides. Examples of the composite oxide include indium zinc composite oxide (IZO), indium gallium zinc composite oxide (IGZO), indium gallium composite oxide (IGO), indium tin composite oxide (ITO), and antimonthine composite. Oxides (ATO) can be mentioned. Examples of conductive fibers include metal nanowires and carbon nanotubes. Metals include, for example, gold, platinum, silver, and copper. The conductive layer 16 integrally has a sensor electrode portion 18 located in the central portion in the plane direction and a drawer wiring portion 19 located in the periphery of the sensor electrode portion 18. Details of the conductive layer 16 are described in, for example, JP-A-2017-102443, JP-A-2014-113705, and JP-A-2014-219667.

<Base material layer 17>
The base material layer 17 is arranged on the back surface of the conductive layer 16 and the back surface of the pressure-sensitive adhesive layer 12. The base material layer 17 extends in the plane direction. The base material layer 17 is, for example, a resin layer. Examples of the material of the base material layer 17 include olefin resin, polyester resin, (meth) acrylic resin, polycarbonate resin, polyether sulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Can be mentioned. Examples of the olefin resin include polyethylene, polypropylene, and cycloolefin polymer (COP). Examples of the polyester resin include PET, PBT, and PEN. Examples of the (meth) acrylic resin include poly (meth) acrylate resins. Details of the base material layer 17 are described in, for example, Japanese Patent Application Laid-Open No. 2018-181722.

<Second adhesive layer 14>
The second pressure-sensitive adhesive layer 14 is arranged on the back surface of the conductive film 13. Specifically, the second pressure-sensitive adhesive layer 14 is in contact with the back surface of the conductive film 13. The material of the second pressure-sensitive adhesive layer 14 is the same as the material of the pressure-sensitive adhesive layer 12.

<Image display member 15>
The image display member 15 forms the back surface of the organic EL display device 10. The image display member 15 is arranged on the back side of the conductive film 13 via the second pressure-sensitive adhesive layer 14. The image display member 15 extends in the plane direction. Specifically, the image display member 15 is an organic EL element. For example, although not shown, the image display member 15 includes a display board, two electrodes, an organic EL layer sandwiched between the two electrodes, and a sealing layer. The configuration and physical properties of the image display member 15 are described in detail in, for example, Japanese Patent Application Laid-Open No. 2018-28873.

<Action and effect of one embodiment>
The optical laminate 1 of one embodiment has a novel configuration in which the film 4 is arranged on the viewing side and the glass plate 2 is arranged on the opposite side. In this optical laminate 1, the drop height H1 of the pen until the glass plate starts to crack in the pen drop cracking test is 15 cm or more. Therefore, the optical laminate 1 is excellent in impact resistance.

Further, in this optical laminate 1, the drop height H2 of the pen until the film 4 starts to peel in the pen drop peeling test is 15 cm or more. Therefore, the adhesion of the film 4 is excellent. Therefore, the optical laminate 1 is excellent in reliability.

Further, the average tan δ of the film 4 from -100 ° C to -50 ° C is 0.04 or more, and the average tensile storage elastic modulus E'of the film 4 from -100 ° C to -50 ° C is 3 GPa or more and 6 GPa. Since it is as follows, the cracking of the glass plate 2 in the pen drop cracking test can be suppressed. Therefore, the optical laminate 1 is excellent in impact resistance.

Further, in this optical laminate 1, the adhesive force between the glass plate 2 and the adhesive layer 3 is 3.0 kN / m or more, and the adhesive force between the film 4 and the adhesive layer 3 is 3.0 kN / m or more. Therefore, each of the film 4 and the glass plate 2 has excellent adhesion to the adhesive layer 3. Therefore, the optical laminate 1 is excellent in reliability.

Further, if the film 4 is a TAC film, it has excellent adhesion to the adhesive layer 3.
Therefore, the optical laminate 1 is excellent in reliability.

Further, when the thickness of the film 4 is 60 μm or less, 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.

Further, since the optical laminate of the present invention has excellent impact resistance, even a glass plate having a thickness of less than 40 μm has sufficient impact resistance.

<Modification example>
In the following modification, the same members and processes as those in the above-described embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. Further, the modified example can exhibit the same action and effect as that of one embodiment, except for special mention.

In one embodiment, the film 4 is a single layer, but the number of layers of the film 4 is not limited.
The film 4 may have a plurality of layers.

As shown by the alternate long and short dash line in FIG. 1, the optical laminate 1 may further include a hard coat layer 38. The hard coat layer 38 is arranged on one side of the film 4 in the thickness direction. The hard coat layer 38 is in contact with one 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 coat layer 38 in this order toward the visual recognition side. The formulation, physical properties and dimensions of the hardcourt layer 38 are not particularly limited. In this modification, since the optical laminate 1 includes the hard coat layer 38, the impact resistance and scratch resistance of the optical laminate 1 can be improved.

The hard coat layer 38 may be replaced with, or may be further provided with another functional layer. Examples of other functional layers include an anti-scattering layer, an anti-fouling layer, and an anti-reflection layer. These may be a single layer or a plurality of these may be laminated.

Since the optical laminate of the present invention has excellent impact resistance, even a glass plate having a thickness of less than 40 μm has sufficient impact resistance. Since a glass plate having a thickness of less than 40 μm is excellent in flexibility, the optical laminate of the present invention can be suitably used for flexible displays such as foldable displays and rollable displays.

Specific numerical values such as the compounding ratio (content ratio), physical property values, parameters, etc. used in the following description are the compounding ratios (content ratios) corresponding to those described in the above-mentioned "mode for carrying out the invention". ), Physical property values, parameters, etc. can be replaced with the upper limit value (value defined as "less than or equal to" or "less than") or the lower limit value (value defined as "greater than or equal to" or "excess"). can. In addition, unless otherwise specified in the following description, "part" and "%" are based on mass.

In the following Examples and Comparative Examples, the optical laminate 1 was manufactured, and then the pressure-sensitive adhesive layer 12 was arranged on the optical laminate 1 to evaluate the impact resistance of the optical laminate 1.

Example 1
A glass plate 2 (G-leaf) having a thickness of 30 μm and a film 4 (Diafoil S100, manufactured by Mitsubishi Chemical Corporation) made of a polyethylene terephthalate film having a thickness of 50 μm were prepared. In addition, 70 parts by mass of an aliphatic alicyclic epoxy resin (seroxetane 2021P, epoxy equivalent 128 to 133 g / eq., Manufactured by Daicel Chemical Co., Ltd.), trifunctional aliphatic epoxy resin (EHPE3150, epoxy equivalent 170 to 190 g / eq., Daicel). Chemical Co., Ltd.) 5 parts by mass, oxetane resin (Aron Oxetane, manufactured by Toa Synthetic Co., Ltd.) 19 parts by mass, silane coupling agent (KBM-403, 3-glycidoxypropyltrimethoxysilane, manufactured by Shinetsu Chemical Industry Co., Ltd.) 4 An epoxy adhesive composition was prepared by blending 2 parts by mass and 2 parts by mass of a photoacid generator (CPI101A, triarylsulfonium salt, manufactured by San Afro). This epoxy adhesive composition was applied to the glass plate 2, and then the acrylic adhesive composition was sandwiched between the glass plate 2 and the film 4.

Then, ultraviolet rays were applied to the curable adhesive from the glass plate 2 side. As a result, an adhesive layer 3 having a thickness of 1 μm made of a cured body that firmly adheres the glass plate 2 and the film 4 was formed. The elastic modulus of the adhesive layer 3 at 25 ° C. measured by the nanoindenter method was 4.9 GPa. As a result, the optical laminate 1 including the glass plate 2, the adhesive layer 3, and the film 4 was manufactured.

Next, the pressure-sensitive adhesive layer 12 having a thickness of 15 μm was placed on the other surface of the glass plate 2 in the thickness direction by transfer. The pressure-sensitive adhesive layer 12 was prepared as follows.

43 parts by mass of lauryl acrylate (LA), 44 parts by mass of 2-ethylhexyl acrylate (2EHA), 6 parts by mass of 4-hydroxybutyl acrylate (4HBA), 7 parts by mass of N-vinyl-2-pyrrolidone (NVP), and BASF. 0.015 parts by mass of "Irgacure 184" was blended and polymerized by irradiating with ultraviolet rays to obtain a base polymer composition (polymerization rate: about 10%).

Separately, 60 parts by mass of dicyclopentanyl methacrylate (DCPMA), 40 parts by mass of methyl methacrylate (MMA), 3.5 parts by mass of α-thioglycerol, and 100 parts by mass of toluene are mixed and subjected to a nitrogen atmosphere. The mixture was stirred at 70 ° C. for 1 hour. Next, 0.2 parts by mass of 2,2'-azobisisobutyronitrile (AIBN) was added and reacted at 70 ° C. for 2 hours, then heated to 80 ° C. and reacted for 2 hours. Then, the reaction solution was heated to 130 ° C., and toluene, the chain transfer agent and the unreacted monomer were dried and removed to obtain a solid acrylic oligomer. The weight average molecular weight of the acrylic oligomer was 5100. The glass transition temperature (Tg) was 130 ° C.

0.07 parts by mass of 1,6-hexanediol diacrylate (HDDA), 1 part by mass of acrylic oligomer, silane coupling agent ("KBM403" manufactured by Shin-Etsu Chemical Co., Ltd.) with respect to 100 parts by mass of the solid content of the base polymer composition. After adding 0.3 parts by mass, these were uniformly mixed to prepare a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition is applied to the surface of a release sheet made of PET film (Mitsubishi Chemical "Diafoil MRF75"), and then a release sheet made of another PET film (Mitsubishi Chemical "Diafoil MRF75") is applied. It was attached to the film. Then, the coating film was irradiated with ultraviolet rays to prepare an adhesive layer 12 having a thickness of 15 μm. The shear storage elastic modulus G'at 25 ° C. of the pressure-sensitive adhesive layer 12 was 0.03 MPa. The measurement method is as follows.
The pressure-sensitive adhesive layer 12 is externally processed into a disk shape, sandwiched between parallel plates, and the pressure-sensitive adhesive layer 12 is measured by dynamic viscoelasticity measurement under the following conditions using "Advanced Shearometric Exhibition System (ARES)" manufactured by Shearetic Scientific. The shear storage elastic modulus G'at 25 ° C. was determined.

[conditions]
Mode: Torsion temperature: -40 ° C to 150 ° C
Temperature rise rate: 5 ° C / min Frequency: 1Hz

Example 2
The optical laminate 1 was manufactured in the same manner as in Example 1. However, the film 4 was changed to a triacetyl cellulose film (KC4UYW, manufactured by Konica Minolta) having a thickness of 40 μm.
Was used.

Example 3
The optical laminate 1 was manufactured in the same manner as in Example 1. However, the film 4 was changed to a triacetyl cellulose film (KC2CT, manufactured by Konica Minolta) having a thickness of 20 μm.

Example 4
The optical laminate 1 was manufactured in the same manner as in Example 2. However, the film 4 was changed to a triacetyl cellulose film (KC8UAW, manufactured by Konica Minolta) having a thickness of 80 μm.

Comparative Example 1
The optical laminate 1 was manufactured in the same manner as in Example 1. However, as the film 4, a methacrylic resin pellet having a glutarimide ring unit was formed into a film by extrusion molding, and then a stretched acrylic film was used. The thickness of the acrylic film was 40 μm.

Table 1 shows the types and thicknesses of the films 4 in each Example and Comparative Example.

<Evaluation>
The following items were measured and evaluated for each Example and Comparative Example. The results are shown in Table 1.

<Tan δ of film 4 and tensile storage elastic modulus E'>
The films 4 prepared in each Example and Comparative Example were subjected to a dynamic viscoelasticity test. The equipment and conditions are described below.

Equipment: Hitachi High-Tech Science Multifunctional Dynamic Viscoelasticity Measuring Equipment DMS6100
Temperature range: -100 to 200 ° C
Temperature rise rate: 2 ° C / min
Mode: Tensile sample width: 10 mm
Distance between chucks: 20 mm
Frequency: 10Hz
Strain amplitude: 10 μm
Atmosphere: Atmosphere (250 ml / min)
Data acquisition interval: 0.5 min (every 1 ° C)

Each of the average tensile storage elastic moduli E'of the film 4 from -100 ° C to -50 ° C was calculated by dividing the sum of all the above acquired data from -100 ° C to -50 ° C by the number of data. .. Each of the averages of tan δ of film 4 from −100 ° C. to −50 ° C. was calculated by dividing the sum of all the above-mentioned acquired data from −100 ° C. to −50 ° C. by the number of data.

<Adhesive force between film 4 and adhesive layer 3>
The adhesion between the film 4 and the adhesive layer 3 was measured using the surface / interface physical characteristic analysis device with the following devices, conditions and methods.

Equipment: Surface / interface physical characteristic analysis equipment (SAICAS DN-20 type) manufactured by Daipra Wintes.

Material of blade 42: Single crystal diamond Width of blade edge 43: 1 mm
Scoop angle of cutting edge 43: 10 °

As shown in FIG. 2A, the surface / interface physical characteristic analysis device 41 includes a blade 42, a moving device (not shown), and a pressure measuring unit. The blade 42 is movable. The blade 42 includes a blade edge 43 formed at the lower end portion.

As shown in FIG. 2A, the optical laminate 1 was set in the measuring device 41. At this time, the film 4 was arranged on the upper side and the glass plate 2 was arranged on the lower side.

The cutting edge 43 was moved diagonally downward 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. As a result, the cutting edge 43 cuts into the film 4.

As shown in FIG. 2B, when the cutting edge 43 reached the interface between the film 4 and the adhesive layer 3, the cutting edge 43 was moved only in the horizontal direction. The horizontal velocity remains at 10 μm / sec. The film 4 was peeled from the adhesive layer 3 by the horizontal movement of the cutting edge 43. The peel strength at this time was measured as the adhesion between the film 4 and the adhesive layer 3.

<Adhesive force between the glass plate 2 and the adhesive layer 3>
The adhesive force between the glass plate 2 and the adhesive layer 3 was measured by the same apparatus, conditions and method as described above. However, as shown in FIG. 2C, after cutting into the film 4 of the cutting edge 43, the cutting edge 43 is also cut into the adhesive layer 3, and when the cutting edge 43 reaches the interface between the adhesive layer 3 and the glass plate 2, the cutting edge 43 is cut. Moved horizontally. As a result, the adhesive layer 3 was peeled off from the glass plate 2. The peel strength at this time was measured as the adhesion between the glass plate 2 and the adhesive layer 3.

<Pen drop crack test>
The following pen drop cracking test was carried out for the optical laminate 1 of each Example and Comparative Example. First, as shown in FIG. 1, the optical laminate 1 was placed on the surface of the resin film 34 (virtual line) so that the film 4 faces upward. Specifically, the pressure-sensitive adhesive layer 12 was attached to the surface of the resin film 34. The resin film 34 is a prescale (a monosheet type for prescale MS medium pressure manufactured by Fujifilm, thickness 95 μm). The resin film 34 is arranged on the surface of a horizontal table (not shown). Next, a pen drop cracking test is carried out in which a 7 g pen 29 (Pentel ballpoint pen BK407 black, ball diameter 0.7 mm) is dropped from a height of 5 cm from the film 4. The height of 5 cm described above is the distance between one side of the film 4 in the thickness direction and the tip portion 32 of the pen 29. The tip portion 32 faces downward and is sharp. In this optical laminate 1, if the glass plate 2 is cracked by the above-mentioned drop of the pen 29, the height H1 of the pen drop cracking test becomes 5 cm. If the glass plate 2 does not crack, the height is gradually increased by 1 cm. As a result, the height H1 when the glass plate 2 is cracked is obtained.

<Pen drop peeling test>
The pen 29 was dropped onto the film 4 in the same manner as in the pen drop cracking test described above. The initial drop height was set to 5 cm. After that, when the film 4 was not peeled off from the adhesive layer 3, the height was gradually increased by 1 cm. The height when the peeling from the adhesive layer 3 of the film 4 was confirmed was obtained as the height H2 in the pen drop peeling test. Alternatively, when the glass plate 2 is cracked, it is determined that the glass plate 2 has peeling durability having a cracked height of H1 or more.

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

Claims (7)

A glass plate, an adhesive layer, and a film are provided in order toward one side in the thickness direction.
One side in the thickness direction is the visual recognition side.
An optical laminate having a pen drop height H1 of 15 cm or more until the glass plate begins to crack in the pen drop cracking test below.
<Pen drop crack test>
The shear storage elastic modulus G'at a frequency of 1 Hz, a heating rate of 5 ° C./min, a temperature of -40 ° C to 150 ° C., and a shear storage modulus G'at 25 ° C. obtained by a dynamic viscoelasticity test in a torsion mode is 0.03 MPa.
The pressure-sensitive adhesive layer having a thickness of 15 μm is arranged on the other surface of the optical laminate in the thickness direction. A 7 g ballpoint pen with a ball diameter of 0.7 mm is dropped toward the film. The drop height of the pen is raised by 1 cm, and the height when cracks are confirmed in the glass plate is obtained as the height H1 in the pen drop crack test. The optical laminate according to claim 1, wherein the drop height H2 of the pen until the film starts to peel in the following pen drop peeling test is 15 cm or more.
<Pen drop peeling test>
The pressure-sensitive adhesive layer is arranged on the other surface of the optical laminate in the thickness direction. A 7 g ballpoint pen with a ball diameter of 0.7 mm is dropped toward the film. The drop height of the pen is gradually increased to 30 cm, and the height when peeling is confirmed on the film is obtained as the height H2 in the pen drop peeling test. Alternatively, when the glass plate is cracked, it is determined that the glass plate has peeling durability having a crack height of H1 or more. The average tan δ of the film at a frequency of 10 Hz, a heating rate of 2 ° C./min, and a dynamic viscoelasticity test in a tensile mode from -100 ° C to -50 ° C is 0.04 or more, and the dynamic viscoelasticity. The optical laminate according to claim 1 or 2, wherein the average tensile storage elastic modulus E'of the film at −100 ° C. to −50 ° C. determined by a test is 3 GPa or more and 6 GPa or less. The adhesion between the glass plate and the adhesive layer is 3.0 kN / m or more.
The optical laminate according to any one of claims 1 to 3, wherein the adhesive force between the film and the adhesive layer is 3.0 kN / m or more. The optical laminate according to any one of claims 1 to 4, wherein the film is a triacetyl cell roll film. The optical laminate according to claim 5, wherein the film has a thickness of 10 μm or more and 60 μm or less. The optical laminate according to any one of claims 1 to 6, further comprising a hard coat layer arranged on one side of the film in the thickness direction.

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