JP6903804B1 - Flexible image display device and optical laminate used for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure high adhesiveness between constituent members when a flexible image display device is repeatedly bent in a high temperature environment. A display device 1 includes a window member 11, a first member, a first laminated body L, a panel member with a touch sensor, and a plurality of layers of adhesive members 21, 22, and 23. The first laminated body is a laminated body of the second member and the third A member. When the first laminated body is provided, one of the first member and the second member is an optical film, the other is an optical film or a touch sensor 13, and the plurality of layers of the adhesive member includes at least three layers. When the panel member with a touch sensor is provided, the plurality of layers of the adhesive member includes two layers arranged between the members. E0 × T0> 0.32 (E0: elastic modulus of the window member (GPa), T0: thickness of the window member (mm)). The thickness of at least one layer of the adhesive member is 20 μm or more, and the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side is 10 μm or more. [Selection diagram] Fig. 1

Description

The present invention relates to a flexible image display device and an optical laminate including a plurality of layers of adhesive members.

The flexible image display device includes, for example, a panel member including a display panel and an optical laminate arranged on the front surface of the panel member. The optical laminate includes, for example, a window member and an optical film, and may further include a touch sensor. An adhesive layer or an adhesive layer is arranged between each member included in the optical laminate or the flexible image display device.

For example, in Patent Document 1, a display panel, a polarizing member provided on the display panel, a window provided on the polarizing member, a first adhesive member provided between the display panel and the polarizing member, and polarization are provided. A foldable display device including a member and a second adhesive member provided between windows has been proposed. Patent Document 1 describes that a foldable display device can include a touch sensing unit. Further, Patent Document 1 describes a foldable display device including a window WD, a touch sensing unit TSU, a polarizing member POL, and a display panel DP. The first adhesive member AD1 is arranged between the window WD and the touch sensing unit TSU, and the fourth adhesive member AD4 is arranged between the touch sensing unit TSU and the polarizing member POL, and the polarizing member POL and the display panel. A second adhesive member AD2 is arranged between the DP and the DP.

JP-A-2017-126061 (Claim 1, [0132], [0138] and FIG. 7B)

The flexible image display device has a laminated structure in which members (window members, optical films, touch sensors, panel members, etc.) constituting the device are bonded together with an adhesive layer or an adhesive layer. The flexible image display device is required to have high adhesiveness that does not cause peeling between the bonded members when repeatedly bent. The peeling between the members becomes particularly remarkable when the flexible image display device is repeatedly bent in a high temperature environment. Further, when the hardness of the window member is high (or the stiffness is strong), peeling between the members is likely to become apparent.

One aspect of the present invention is a window member and
The first member laminated on the window member and
A first laminated body or a panel member with a first touch sensor laminated on the window member via the first member.
A flexible image display device including a plurality of layers of adhesive members.
The first laminated body is a laminated body of a second member laminated via the first member and a third A member laminated via the first member and the second member on the window member. Yes,
When the flexible image display device includes the first laminated body,
One of the first member and the second member is an optical film, and the other is an optical film or a touch sensor.
The third A member includes at least a panel member.
The plurality of layers of the adhesive member are arranged at least between the window member and the first member, between the first member and the second member, and between the second member and the third A member. Including 3 layers to be
When the flexible image display device includes the panel member with the first touch sensor,
The first member is an optical film and
The plurality of layers of the adhesive member includes at least two layers arranged between the window member and the first member and between the first member and the panel member with the first touch sensor.
When the elastic modulus (GPa) of the window member is E0 and the thickness (mm) of the window member is T0, E0 × T0 (kN / mm) satisfies the condition of E0 × T0> 0.32.
The thickness of at least one layer of the plurality of adhesive members satisfies the condition of 20 μm or more.
The present invention relates to a flexible image display device in which the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side among the plurality of layers of the adhesive member satisfies a condition of 10 μm or more.

Another aspect of the present invention is used in the flexible image display device described above.
Window members and
The first member laminated on the window member and
A second laminated body or a first separator laminated on the window member via the first member,
An optical laminate comprising a plurality of layers of adhesive members.
The second laminated body is a laminated body of a second member laminated via the first member and a third B member laminated via the first member and the second member on the window member. Yes,
When the optical laminate includes the second laminate,
One of the first member and the second member is an optical film, and the other is an optical film or a touch sensor.
The third B member includes at least a second separator.
The plurality of layers of the adhesive member are arranged at least between the window member and the first member, between the first member and the second member, and between the second member and the third B member. Including 3 layers to be
When the optical laminate includes the first separator
The first member is an optical film and
The plurality of layers of the adhesive member includes at least two layers arranged between the window member and the first member and between the first member and the first separator.
When the elastic modulus (GPa) of the window member is E0 and the thickness (mm) of the window member is T0, E0 × T0 (kN / mm) satisfies the condition of E0 × T0> 0.32.
The thickness of at least one layer of the plurality of adhesive members satisfies the condition of 20 μm or more.
The present invention relates to an optical laminate in which the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side among the plurality of layers of the adhesive member satisfies the condition of 10 μm or more.

When a flexible image display device provided with a window member having high hardness is repeatedly bent in a high temperature environment, high adhesiveness between the laminated members can be ensured.

It is a schematic cross-sectional view of the flexible image display device which concerns on 1st Embodiment of this invention. It is the schematic sectional drawing of the flexible image display apparatus which concerns on 2nd Embodiment of this invention. It is the schematic sectional drawing of the flexible image display apparatus which concerns on 3rd Embodiment of this invention.

The flexible image display device according to the present invention includes a window member, a first member laminated on the window member, and a first laminated body or a panel member with a first touch sensor laminated on the window member via the first member. , With a plurality of layers of adhesive members. The first laminated body is a laminated body of a second member laminated via the first member and a third A member laminated via the first member and the second member on the window member.

When the flexible image display device includes the first laminated body, one of the first member and the second member is an optical film, and the other is an optical film or a touch sensor. The third A member includes at least a panel member. In this case, the plurality of layers of the adhesive member are at least three layers arranged between the window member and the first member, between the first member and the second member, and between the second member and the third A member. including.

When the flexible image display device includes a panel member with a first touch sensor, the first member is an optical film. In this case, the plurality of layers of the adhesive member includes at least two layers arranged between the window member and the first member and between the first member and the panel member with the first touch sensor.

The present invention also includes an optical laminate used in the above-mentioned flexible image display device. The optical laminate includes a window member, a first member laminated on the window member, a second laminate or a first separator laminated on the window member via the first member, and a plurality of layers of adhesive members. Equipped. The second laminated body is a laminated body of a second member laminated via the first member and a third B member laminated via the first member and the second member on the window member.

When the optical laminated body includes the second laminated body, one of the first member and the second member is an optical film, and the other is an optical film or a touch sensor. The third B member includes at least a second separator. The multi-layer adhesive member includes at least three layers arranged between the window member and the first member, between the first member and the second member, and between the second member and the third B member.

When the optical laminate includes a first separator, the first member is an optical film. In this case, the plurality of layers of the adhesive member includes at least two layers arranged between the window member and the first member and between the first member and the first separator.

The optical laminate is used in a flexible image display device in a state where the separator (specifically, the first separator or the second separator included in the third B member) is peeled off. The flexible image display device includes an optical laminate with the separator peeled off, with the window member arranged on the viewing side.

In the above flexible image display device and optical laminate, when the elastic modulus (GPa) of the window member is E0 and the thickness (mm) of the window member is T0, E0 × T0 (kN / mm) is E0 × T0. The condition of> 0.32 is satisfied. The product (= E0 × T0) of the elastic modulus and the thickness indicates the degree of stiffness (or hardness) of the window member.

The flexible image display device is required to have high adhesiveness that does not peel off between the laminated constituent members when repeatedly bent. By arranging the adhesive member between the constituent members, the stress when the flexible image display device is bent can be relaxed to some extent by the adhesive member. This is because the adhesive member has a high viscosity even when the members are bonded to each other, unlike the adhesive member that adheres the members to each other by curing.

The adhesive member is a cured adhesive and has no fluidity. On the other hand, the adhesive member is a non-curable adhesive and has fluidity.

Adhesion when the hardness (or weakness) of the window member arranged on the visual side of the flexible image display device is low (specifically, when E0 × T0 ≦ 0.32 (kN / mm)) By arranging the members in a plurality of layers in the flexible image display device, the stress due to bending can be relaxed. However, when the hardness of the window member is high (or the stiffness is strong) (specifically, when E0 × T0> 0.32 (kN / mm)), even if a plurality of layers of the adhesive member are arranged, it is bent. It became clear that the stress may not be sufficiently relieved. Further, when the flexible image display device is repeatedly bent at room temperature (20 ° C. to 35 ° C.), even if peeling does not occur between the laminated members, the flexible image display device is repeatedly bent in a high temperature environment (for example, 60 ° C.). Peeling may occur, making it impossible to ensure high adhesiveness.

A layer of an adhesive member having a thickness of less than 10 μm (especially, 8 μm or less, 7 μm or less, or 6 μm or less) has a low effect of relieving stress due to bending. In particular, in the case of E0 × T0> 0.32 (kN / mm), if the thickness of the nth and (n + 1) th adhesive member layers from the window member side is continuously less than 10 μm, the thickness is 20 μm or more. It is difficult to relieve the stress due to bending even if the layer of the adhesive member having In the flexible image display device and the optical laminate according to the present invention, at least three layers or at least two layers of adhesive members are provided, and the thickness of at least one layer of the adhesive members is controlled to 20 μm or more. In addition, the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side among the plurality of layers of the adhesive member is controlled to be 10 μm or more. By providing at least three layers or at least two layers of adhesive members, the flexibility of the laminated structure as a whole is increased. Further, by controlling the thickness of the layer of the adhesive member as described above, the stress due to bending can be effectively relaxed by the entire laminated structure even when E0 × T0> 0.32 (kN / mm). Therefore, even if the flexible image display device is repeatedly bent in a high temperature environment, peeling between the laminated members is effectively suppressed, and high adhesiveness can be ensured.

The hardness of each member in the flexible image display device or the optical laminate including the window member can be adjusted by, for example, adjusting the material, layer structure, and / or thickness of each member.

(Adhesive member)
The optical laminate or the flexible image display device includes a plurality of layers of adhesive members. More specifically, when the flexible image display device (or optical laminate) includes the first laminate (or the second laminate), the flexible image display device (or the optical laminate) is at least the window member and the first. A three-layer adhesive member is provided between the first member, between the first member and the second member, and between the second member and the third A member (or the third B member). When the flexible image display device (or optical laminate) includes the panel member with the first touch sensor (or the first separator), the multi-layer adhesive member is at least between the window member and the first member, and the first. It includes a two-layer adhesive member arranged between the member and the panel member with the first touch sensor (or the first separator). The multi-layer adhesive member may include an adhesive member other than the three-layer or two-layer adhesive member arranged between such adjacent members. The adhesive member other than the three-layer or two-layer adhesive member is inside each member other than the window member (specifically, the first member, the second member, the third A member (or the third B member), and the first touch. It is arranged in at least one member selected from the group consisting of panel members with sensors). Each adhesive member is usually layered. The number of adhesive members in each member is not particularly limited, and may be 0 layer, 1 layer, or 2 or more layers. As described above, the adhesive member (that is, the adhesive member having a plurality of layers) included in the flexible image display device or the optical laminate includes both the adhesive member included between the adjacent members and the adhesive member contained in each member. Is included.

The adhesive member included in the flexible image display device or the optical laminate may be, for example, 8 layers or less, 7 layers or 6 layers or less, or 5 layers or 4 layers or less.

Among the plurality of layers of the adhesive member, the layer having a thickness of 20 μm or more is at least one layer, and may be two or more layers. By providing a layer of adhesive members with a thickness of 20 μm or more, even when E0 × T0> 0.32 (kN / mm), between the laminated members when the flexible image display device is repeatedly bent in a high temperature environment. High adhesiveness can be ensured.

The maximum thickness of the plurality of layers of the adhesive member is, for example, 50 μm or less, and may be 40 μm or less. The flexible image display device is used in a state where the surface of the window member is exposed on the visual side. Therefore, it is preferable that the surface of the flexible image display device on the visual side has high scratch resistance. When the flexible image display device includes a plurality of layers of adhesive members or when the layers of the adhesive members are thick, it is relatively easy to relieve stress due to bending. However, since the pressure marks are hard to return to the original due to the deformation of the adhesive member, the scratch resistance is lowered. In the case of a hardened adhesive member, it is difficult for stress to be relaxed as in the case of an adhesive member, and there is almost no decrease in scratch resistance. In a flexible image display device, since the constituent members are required to have high flexibility, it is considered that the influence of the highly viscous adhesive member on the scratch resistance is likely to become apparent. In the present invention, since E0 × T0> 0.32 (kN / mm), a certain degree of scratch resistance can be ensured. From the viewpoint of easily ensuring higher scratch resistance, the maximum thickness of the plurality of layers of the adhesive member is preferably 30 μm or less, and may be 27 μm or less. The scratch resistance of the surface can be evaluated by, for example, a pencil hardness test.

The scratch resistance of the flexible image display device is measured with respect to the surface on the viewing side (more specifically, the surface on the viewing side of the window member). Therefore, the stress relaxation property of the layer of the adhesive member adjacent to the window member (that is, the first layer from the window member side) is more likely to affect the scratch resistance than the layer of the adhesive member located at a position away from the window member. Further, when E0 × T0> 0.32 (kN / mm), the stress when the surface on the visual side of the flexible image display device is pressed is compared with the case of E0 × T0 ≦ 0.32 (kN / mm). Tends to be relaxed throughout the laminated structure of the flexible image display device. Therefore, from the viewpoint of ensuring higher scratch resistance, it is preferable to control the average value of the layer thickness of the first adhesive member from the window member side and the thickness of the plurality of adhesive members.

More specifically, the average value of the thicknesses of the plurality of layers of adhesive members contained in the flexible image display device or the optical laminate is, for example, 23 μm or less, and from the viewpoint of ensuring higher scratch resistance, 20 μm or less is used. Preferably, it may be less than 20 μm or 19 μm or less, or 18 μm or less.

The thickness of the layer of the first adhesive member from the window member side is preferably 20 μm or less, may be less than 20 μm or 17 μm or less, and may be 16 μm or less or 15 μm or less.

In other words, from the viewpoint of ensuring higher pencil hardness, it is preferable that the layer of the adhesive member having a thickness of more than 20 μm is provided at the second and subsequent positions from the window member side.

From the viewpoint of ensuring higher adhesiveness, the thickness of the layer of the adhesive member located on the outer side of the layer of the adhesive member located on the inner side in the bent state of the flexible image display device may be 20 μm or more. It is advantageous. Therefore, from such a viewpoint, it is preferable that the thickness of the second and subsequent layers of the adhesive member from the window member side is 20 μm or more.

The thickness of each layer of the adhesive member is, for example, 3 μm or more, and may be 5 μm or more or 6 μm or more. When the thickness of the layer of the adhesive member is within such a range, it is easy to secure high flexibility in the flexible image display device.

Of the plurality of layers of the adhesive member, at least one of the nth layer and the (n + 1) th layer from the window member side may have a thickness of 10 μm or more, 11 μm or more, 12 μm or more, and 14 μm or more. Alternatively, it may be 15 μm or more. When the thickness of one of the nth layer and the (n + 1) th layer is less than 10 μm (preferably 8 μm or less, more preferably 7 μm or less or 6 μm or less), the thickness of the other layer is ensured from the viewpoint of ensuring higher adhesiveness. Is preferably 14 μm or more or 15 μm or more.

In the flexible image display device, at least 1 is provided between the surface of the window member on the first member side and the touch sensor or the panel member with the touch sensor (specifically, the panel member with the first or second touch sensor). A decorative layer may be provided so as to come into contact with the adhesive member of the layer. If the thickness of the adhesive member at the portion where the decorative layer is provided is small, it becomes difficult for the adhesive member to absorb the step formed by the decorative layer. Therefore, from the viewpoint of easily absorbing the step caused by the decorative layer, the thickness of the adhesive member with which the decorative layer comes into contact may be 10 μm or more.

From the viewpoint of easily absorbing the step caused by the decorative layer, the thickness of the adhesive member with which the decorative layer comes into contact may be 1.5 times or more the thickness of the decorative layer, or 2 times or more or 2.5 times or more, and further. May be tripled or more.

The upper limit value and the lower limit value of the layer thickness of the adhesive member described above can be arbitrarily combined.

The thickness of each layer of the adhesive member is measured based on a cross section of a flexible image display device or an optical laminate cut out and an image of the cross section taken by a scanning electron microscope (SEM). The thickness of each layer of the adhesive member is obtained by measuring and averaging the thicknesses of the portions where the decorative layer is not formed at an arbitrary plurality of locations (for example, 5 locations) in the SEM image of the cross section.

The storage elastic modulus of each layer of the adhesive member at 25 ° C. is usually 10 MPa or less, may be 3 MPa or less, 2 MPa or less, or 1.5 MPa or less . The storage elastic modulus of each adhesive member at 25 ° C. is preferably 1 MPa or less, 0.3 MPa or less or 0.2 MPa or less, and 0.15 MPa or less or 0.1 MPa or less. When the storage elastic modulus of each layer of the adhesive member is in such a range, high adhesiveness can be ensured. On the other hand, when the storage elastic modulus of the layer of the adhesive member is in the above range, unlike the case of the cured adhesive member, the stress due to pressing is easily relieved and the pencil hardness is easily lowered. Even when the flexible image display device includes a plurality of layers of adhesive members that can easily relieve stress due to pressing, a certain high pencil hardness can be ensured by setting E0 × T0> 0.32 (kN / mm). Can be done. Further, by controlling the thickness of the layer of the first adhesive member from the window member side and the average thickness of the plurality of adhesive members as described above, it is possible to secure a higher pencil hardness.

The storage elastic modulus of each layer of the adhesive member at 25 ° C. may be 0.001 MPa or more, or 0.005 MPa or more.

The upper limit value and the lower limit value of the storage elastic modulus of each layer of the adhesive member described above can be arbitrarily combined.

On the other hand, the storage elastic modulus of the adhesive member at 25 ° C. is larger than 10 MPa, may be 100 MPa or more, and is usually about 1 GPa. In the present specification, the adhesive member means a member having such a storage elastic modulus.
In this way, the adhesive member is distinguished from the adhesive member by the storage elastic modulus.

The storage elastic modulus of the adhesive member can be measured according to JIS K 7244-1: 1998. Specifically, first, a molded product having a thickness of about 1.5 mm is produced using an adhesive member. This molded product is punched into a disk shape having a diameter of 7.9 mm to prepare a test piece. This test piece is sandwiched between parallel plates, and the viscoelasticity is measured under the following conditions using a dynamic viscoelasticity measuring device (for example, "Advanced Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific), and the viscoelasticity is measured at 25 ° C. The storage elastic modulus in. The storage elastic modulus of the adhesive member is also obtained in the same manner as in the case of the adhesive member.

(Measurement condition)
Deformation mode: Torsion measurement frequency: 1Hz
Measurement temperature: -40 ° C to + 150 ° C
Heating speed: 5 ° C. / min

In the flexible image display device according to the present invention, it is possible to secure a high pencil hardness such that the pencil hardness of the surface on the viewing side (more specifically, the surface on the viewing side of the window member) is H or more. Further, in the flexible image display device according to the present invention, it is possible to secure a high pencil hardness of 3H or more or 4H or more on the window member side.

In this specification, the pencil hardness means the scratch hardness (pencil method) defined in JIS K 5600-5-4: 1999. Pencil hardness can be measured under the conditions of a load of 750 g and a weight of 25 ° C. in accordance with JIS K 5600-5-4: 1999.

From the viewpoint of ensuring high visibility of the panel members, the total light transmittance of each adhesive member is preferably 85% or more, more preferably 90% or more.

The total light transmittance of the adhesive member can be measured according to JIS K 7136K: 2000. For the measurement, a test piece in which an adhesive member is arranged on non-alkali glass (thickness 0.8 to 1.0 mm, total light transmittance 92%) until the thickness becomes about 1.5 mm is used.

Each adhesive member is composed of an adhesive. The type of adhesive is not particularly limited, and for example, acrylic adhesive, rubber adhesive, silicone adhesive, urethane adhesive, vinyl alkyl ether adhesive, polyvinylpyrrolidone adhesive, polyacrylamide adhesive. , And a cellulose-based pressure-sensitive adhesive. Adhesives include, for example, base polymers, cross-linking agents, additives (eg, tackifiers, coupling agents, polymerization inhibitors, cross-linking retarders, catalysts, plasticizers, softeners, fillers, colorants, metal powders. , Ultraviolet absorbers, light stabilizers, antioxidants, deterioration inhibitors, surfactants, antistatic agents, surface lubricants, leveling agents, corrosion inhibitors, particles of inorganic or organic materials (metal compound particles (metal oxidation) (Object particles, etc.), resin particles, etc.))) are included, but are not limited thereto.

It is advantageous to use a pressure-sensitive adhesive having the above-mentioned storage elastic modulus as the pressure-sensitive adhesive because the effect of controlling the thickness of the pressure-sensitive adhesive member tends to be remarkable. Of the plurality of layers of the pressure-sensitive adhesive member, the pressure-sensitive adhesives constituting at least two layers of the pressure-sensitive adhesive members may be the same, and the pressure-sensitive adhesives constituting each pressure-sensitive adhesive member may be different.

The pressure-sensitive adhesive member can be formed, for example, by applying a pressure-sensitive adhesive constituting each pressure-sensitive adhesive member to one of the members that sandwich each pressure-sensitive adhesive member, or by transferring a pressure-sensitive adhesive molded into a sheet shape. Then, by laminating the other of the members that sandwich each adhesive member on the adhesive member, each adhesive member is arranged between the members. Even when the adhesive member is included in each member, the adhesive member is arranged in each member in the same manner as when the adhesive member is arranged between the members. For example, the adhesive member is arranged on one of the layers (or laminates) constituting each member and sandwiching the adhesive member by utilizing the application or transfer of the adhesive as described above, and the other layer (or laminate) is arranged. The adhesive member is arranged in each member by attaching the body) to the adhesive member.

(Window member)
The window member is arranged on the outermost surface of the flexible image display device or the optical laminate on the visual side in order to prevent damage to the optical film, the touch sensor, the panel member with the touch sensor, and the panel member.

When the product of the elastic modulus E0 of the window member and the thickness T0 is E0 × T0> 0.32 (kN / mm), the space between the laminated members when the flexible image display device is repeatedly bent in a high temperature environment ( Alternatively, the adhesiveness between the layers constituting each member) tends to decrease. In the present invention, by controlling the thickness of the plurality of layers of the adhesive member as described above, high adhesiveness is ensured even in a high temperature environment even when E0 × T0> 0.32 (kN / mm). be able to.

The window member usually includes a window film. Flexible image display devices or optical laminates applied thereto are required to have high flexibility (high commutativity, etc.), high transparency (high total light transmittance, low haze, etc.), and high hardness. The material of the window film is not particularly limited as long as it satisfies these physical characteristics.

Examples of the window film include a transparent resin film. Examples of the resin constituting the transparent resin film include polyimide resin, polyamide resin, polyester resin, cellulose resin, acetate resin, styrene resin, sulfone resin, epoxy resin, polyolefin resin, and polyether. At least one selected from ether ketone resin, sulfide resin, vinyl alcohol resin, urethane resin, acrylic resin, and polycarbonate resin can be mentioned. However, the resin constituting the transparent resin film is not limited to these.

The thickness of the window film is, for example, 20 μm or more and 500 μm or less, and may be 30 μm or more and 200 μm or less. When the window film has such a thickness, it is easy to achieve both high strength and high flexibility.

In the present specification, with respect to a member (molded body) other than the adhesive member or a material other than the adhesive, the transparent material means that the total light transmittance of the test piece is 80% or more. A test piece having a thickness of about 1.5 mm and made of a transparent material or member is used for measuring the total light transmittance. The total light transmittance can be measured according to the case of the adhesive member.

The window member may include a hard coat layer. From the viewpoint that a high damage prevention effect of the window film can be easily obtained, it is preferable that the hard coat layer is provided at least on the side opposite to the first member side of the window member. More specifically, it is preferable that the hard coat layer is provided on the surface at least on the side opposite to the first member side of the window film (that is, the visible side of the window film).

The thickness of the hard coat layer is, for example, 1 μm or more and 100 μm or less, and may be 1 μm or more and 50 μm or less. When the window member includes a plurality of hard coat layers, the thickness of each hard coat layer may be within such a range.

The hard coat layer is formed, for example, by applying a curable coating agent to the surface of a underlying layer (for example, a window film) and curing it.

As the coating agent, for example, those used for optical films can be used. Examples of the coating agent include, but are not limited to, an acrylic coating agent, a melamine coating agent, a urethane coating agent, an epoxy coating agent, a silicone coating agent, and an inorganic coating agent.

The coating agent may contain additives. Additives include, for example, silane coupling agents, colorants, dyes, powders or particles (pigments, inorganic or organic fillers, particles of inorganic or organic materials, etc.), surfactants, plasticizers, antistatic agents. Examples thereof include, but are not limited to, agents, surface lubricants, leveling agents, antioxidants, light stabilizers, ultraviolet absorbers, polymerization inhibitors, antifouling materials, and the like.

The window member may include another layer (hereinafter, referred to as layer A), if necessary. The layer A includes an antireflection layer, an antiglare layer, an antifouling layer, a sticking prevention layer, a hue adjustment layer, an antistatic layer, an easy-adhesion layer, a precipitation prevention layer such as ions or oligomers, a shock absorption layer, and a shatterproof layer. Can be mentioned. The window member may include one layer A or a plurality of layers. The layer A is provided, for example, on the surface side or the first member side of another layer or laminate (for example, a window film) constituting the window member. The layer A may be directly formed by a coating or the like on another layer or a laminated body constituting the window film, or may be laminated via an adhesive member. The window member does not include an adhesive member. Here, the adhesive member refers to an adhesive member having a storage elastic modulus at 25 ° C. as described above.

The thickness T0 of the window member is, for example, 0.02 mm or more and 0.3 mm or less, and may be 0.04 mm or more and 0.2 mm or less.

The thickness T0 of the window member is measured based on a cross section of the flexible image display device or the optical laminate and an SEM image of the cross section. The thickness T0 is obtained by measuring the thickness at an arbitrary plurality of points (for example, 5 points) and averaging the thickness in the SEM image of the cross section.

In the present specification, the thickness of the member constituting the optical laminate or the flexible image display device is obtained according to the case of the thickness T0 of the window member.

The elastic modulus E0 of the window member may be, for example, 0.53 GPa or more and 16 GPa or less, greater than 0.6 GPa and less than 16 GPa, 1 GPa or more and 15 GPa or less, 1 GPa or more and 10 GPa or less, or 3 GPa or more and 8 GPa or less.

The elastic modulus E0 (GPa) of the window member is an average value (arithmetic mean value) obtained by preparing three samples for measuring the window member, measuring the elastic modulus of each sample by a tensile test, and averaging them. is there. The tensile test can be performed under the following conditions using the following device.
Tensile tester: Shimadzu Corporation, Autograph AG-1S
Control: Stroke Station distance: 100 mm
Tensile rate: 50 mm / min
Elastic modulus calculation range: 10N / mm ^{2 to} 20N / mm ²

The sample for measuring the elastic modulus is prepared as follows. First, the elastic modulus of the window member in the vertical and horizontal directions is measured. Next, a sample is prepared by cutting the window member into strips with a length in the direction of high elastic modulus of 150 mm and a length of 10 mm in the direction of low elastic modulus. For cutting the window member, for example, a multipurpose test piece cutting machine manufactured by Dumbbell Co., Ltd. is used.

E0 × T0 may be larger than 0.32 kN / mm, may be 0.33 kN / mm or more, and may be 0.34 kN / mm or more or 0.35 kN / mm or more. From the viewpoint of easily ensuring higher flexibility, E0 × T0 is, for example, 1.5 kN / mm or less, and may be 1.0 kN / mm or less. These lower limit values and upper limit values can be arbitrarily combined.

(1st member and 2nd member)
In the flexible image display device and the optical laminate, the first member is laminated on the window member. When the flexible image display device (or optical laminated body) includes the first laminated body (or the second laminated body), the second member is laminated on the window member via the first member. An adhesive member is interposed between the window member and the first member, and between the first member and the second member, respectively. When the flexible image display device (or optical laminate) includes the first laminate (or the second laminate), one of the first member and the second member is an optical film, and the other is an optical film or a touch sensor. .. The flexible image display device (or optical laminate) includes a third A member (or a third B member), one of the first member and the second member may be an optical film, and the other may be a touch sensor. When the flexible image display device includes the panel member with the first touch sensor and the optical laminate includes the first separator, the first member may be an optical film. When the third A member includes a panel member with a second touch sensor, each of the first member and the second member may be an optical film.

Since the first member and the second member are members included in the flexible image display device, they have appropriate strength and flexibility. The elastic moduli (GPa) of the first member and the second member are E1 and E2, respectively, and the thicknesses (mm) of the first member and the second member are T1 and T2, respectively. At this time, it is preferable that the first member and the second member each satisfy the following. When the product of the elastic modulus and the thickness of each member is in such a range, the effect of controlling the thickness of each layer of the adhesive member as described above can be further easily obtained.
0.01 (kN / mm) ≤ E1 x T1 ≤ 0.35 (kN / mm) (first member)
0.01 (kN / mm) ≤ E2 x T2 ≤ 0.35 (kN / mm) (second member)

(Optical film)
The optical film is a film that imparts an optical function. An optical film is usually a laminate containing at least one layer having an optical function. Examples of the optical film include those used in the field of image display devices and the like. Each of the first member and the second member may be an optical film, or may be one layer or a laminate of two or more layers constituting the optical film.

Examples of the layer having an optical function include a layer having an optically anisotropic substance (for example, an optically anisotropic film). As the layer having optical anisotropy, for example, a polarizer, a retardation layer, viewing angle film, viewing angle limitations (peep prevention) film, a brightness enhancement film, although the optical compensation film and the like, limited to It is not something that is done. The laminate of two or more layers may have two or more selected from these layers having optical anisotropy. In a laminate of two or more layers, all of the layers having optical anisotropy may have different functions, or at least two layers may have the same function. For example, the laminate may include a polarizer and a retardation layer, or may include two retardation layers having different compositions.

The optical film may include at least one layer having an optical function and a base material layer (or a protective layer that protects the layer). For example, the polarizing plate includes at least a film-shaped polarizing element, and may be composed of a polarizing element and a protective film that protects the polarizing element.

It is preferable that the flexible image display device and the optical laminate each include, as an optical film, a film provided with at least a polarizer or a polarizing plate.

The polarizer is not particularly limited, and those used in the field of image display devices and the like can be used. Examples of the polarizer include a film in which a dichroic substance is adsorbed on a hydrophilic polymer film and uniaxially stretched, and a polyene-based oriented film. Examples of the hydrophilic polymer constituting the hydrophilic polymer film include polyvinyl alcohol-based resins (including partially formalized polyvinyl alcohol-based resins) and partially saponified ethylene-vinyl acetate copolymers. Examples of the dichroic substance include iodine and a dichroic dye. Examples of the material constituting the polyene-based alignment film include a dehydrated product of a polyvinyl alcohol-based resin and a dehydrochlorinated product of a polyvinyl chloride-based resin.

As the polarizer, a thin polarizer having a thickness of 10 μm or less may be used. Examples of the thin polarizing element are described in JP-A-51-069644, JP-A-2000-338329, International Publication No. 2010/100917 Pamphlet, Patent No. 46910205, and Patent No. 4751481. Polarizers can be mentioned. The thin polarizer can be obtained, for example, by a production method including a step of stretching a polyvinyl alcohol-based resin layer and a resin base material layer in a laminated state, and a step of dyeing with a dichroic material.

As the protective film, for example, a polymer film having excellent transparency, mechanical strength, thermal stability, moisture blocking property, and optical isotropic property is used. As the polymer material having such properties, the protective film includes, for example, cellulose-based resin, polyolefin-based resin (including cyclic polyolefin-based resin), acrylic-based resin, imide-based resin (including phenylmaleimide-based resin), and polyamide. Based resin, polycarbonate resin, polyester resin (including polyarylate resin), acetate resin, polyether sulfone resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin , At least one selected from the group consisting of sulfide-based resins (for example, polyphenylene sulfide-based resins), polyether ether ketone-based resins, epoxy-based resins, and urethane-based resins. However, the resin constituting the protective film is not limited to these polymer materials.

The optical film may include one layer of protective film and may contain two or more layers of protective film. The protective film may be arranged on one surface of a layer having an optical function (for example, a polarizer), or may be arranged on both surfaces. Further, the optical film may include two or more layers having an optical function in which a protective film is arranged on one surface. If the optical film contains more than one layer of protective film (eg, if the protective film is placed on both surfaces of the polarizer), the composition of all protective films may be different, with at least two layers. The composition of the protective film may be the same.

In addition to the polarizer or the polarizing plate, the optical film may further include another film (hereinafter, referred to as layer B) that imparts an optical function other than the polarizer or the polarizing plate. Examples of the layer B include those used in the field of image display devices. The layer B may be, for example, an optically anisotropic film. Examples of the layer B include layers other than the polarizer or the polarizing plate among the above-mentioned layers having optical anisotropy. Specifically, as the layer B, for example, a phase difference layer, the viewing angle film, viewing angle limitations (peep prevention) film, a brightness enhancement film, an optical compensation film. The optical film may contain one such layer B, or may contain two or more such layers B. However, layer B is not limited to these.

The layer B may be laminated on the polarizing plate via the protective film, or may be laminated on the polarizer without the protective film. When the polarizing plate does not have a protective film, the layer B also functions as a protective film.

The thickness of the optical film is, for example, 5 μm or more and 500 μm or less, and may be 10 μm or more and 100 μm or less.

The thickness of the polarizing plate is, for example, 200 μm or less. From the viewpoint of easily ensuring higher flexibility, the thickness of the polarizing plate is preferably 100 μm or less, more preferably 80 μm or less or 70 μm or less. The thickness of the polarizing plate is, for example, 10 μm or more.

The thickness of the layer B is, for example, 0.1 μm or more and 100 μm or less. When the polarizing plate does not have a protective film (that is, when the layer B also functions as a protective film), the thickness of the laminate of the layer B and the polarizing plate is within the range described for the thickness of the polarizing plate. It is preferable to adjust the thickness of the layer B so as to be.

The layers constituting the optical film may be directly laminated on the adjacent layers by using a coating or the like. Further, the layers constituting the optical film may be laminated on adjacent layers via an adhesive member or an adhesive member. For example, the layer B may be laminated on the polarizing plate via an adhesive member, or may be laminated via an adhesive member. When two or more adjacent layers B are provided, the adjacent layers B may be laminated via either an adhesive member or an adhesive member.

(Touch sensor)
As the touch sensor, for example, a touch sensor used in the field of an image display device or the like is used. Examples of the touch sensor include, but are not limited to, a resistive film type, a capacitance type, an optical type, and an ultrasonic type. In the flexible image display device and the optical laminate, when an optical film is present between the touch sensor and the window member, it is easy to obtain high sensitivity by using the capacitive touch sensor.

Capacitive touch sensors usually include a transparent conductive layer. Examples of such a touch sensor include a laminate of a transparent conductive layer and a transparent base material. Examples of the transparent base material include a transparent film.

The transparent conductive layer is not particularly limited, but a conductive metal oxide, metal nanowires, or the like is used. Examples of the metal oxide include indium oxide (ITO: Indium Tin Oxide) containing tin oxide and tin oxide containing antimony. The transparent conductive layer may be a conductive pattern composed of a metal oxide or a metal. Examples of the shape of the conductive pattern include, but are not limited to, a striped shape, a square shape, and a grid shape.

The surface resistance value of the transparent conductive layer may be, for example, 0.1 Ω / □ or more and 1000 Ω / □ or less, and may be 0.5 Ω / □ or more and 500 Ω / □ or less.

The thickness of the transparent conductive layer is, for example, 0.005 μm or more and 10 μm or less, and may be 0.01 μm or more and 3 μm or less.

As the transparent film, for example, a transparent resin film is used. The resins constituting the transparent resin film include polyester resins (including polyarylate resins), acetate resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and acrylics. Based resin, polyvinyl chloride resin, vinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, sulfide resin (for example, polyphenylene sulfide resin), polyether ether ketone resin, cellulose resin, epoxy resin , Urethane-based resin and the like. The transparent resin film may contain one kind of these resins, or may contain two or more kinds of these resins. Of these resins, polyester-based resins, polyimide-based resins and polyether sulfone-based resins are preferable. However, the resin constituting the transparent resin film is not limited to these resins.

From the viewpoint of enhancing the adhesion between the transparent conductive layer and the transparent base material, a surface-treated transparent base material may be used. As the surface treatment, a known one can be adopted. Further, if necessary, the transparent base material may be subjected to, for example, a dust removal or cleaning treatment (cleaning treatment using a solvent, ultrasonic waves, or the like) prior to laminating the transparent conductive layer.

If necessary, the touch sensor may be provided with a layer other than the transparent conductive layer and the transparent base material (hereinafter, referred to as layer C). For example, an undercoat layer or an oligomer precipitation prevention layer may be provided as the layer C between the transparent conductive layer and the transparent base material. Further, the layer C may be laminated on at least one surface of the transparent conductive layer and the transparent base material. The layer C includes a functional layer having a desired function (for example, a film imparting the above optical function (optically anisotropic film or the like), a layer having the above optical function), a decorative base film, or the like. Can be mentioned. The decorative base film is laminated on the surface of the transparent conductive layer, for example. However, layer C is not limited to these layers. The layer C may be laminated on the transparent conductive layer or the transparent base material via the adhesive member or the adhesive member, if necessary.

The thickness of the entire touch sensor is, for example, 5 μm or more and 250 μm or less, and may be 10 μm or more and 200 μm or less.

(Third member)
In the flexible image display device and the optical laminate, the third member is laminated on the window member via the first member and the second member. An adhesive member is interposed between the second member and the third member. The third member of the flexible image display device is referred to as a third A member. The third A member includes at least a panel member. The third member of the optical laminate is referred to as a third B member. The third B member includes at least a separator (second separator). The optical laminate is included in the flexible image display device with the separator peeled off. The third B member does not include either a panel member or a panel member with a touch sensor. Each of the third A member and the third B member may be a laminated body. Each of the third A member and the third B member may include an adhesive member or an adhesive member.

The third A member may include at least a panel member. The third A member may be, for example, a laminated body of a panel member and a protective member that protects the panel member. When the third A member includes a protective member, the protective member is usually laminated on the side opposite to the second member side of the panel member. That is, the protective member is provided on the side opposite to the visible side of the panel member. However, these are merely examples, and the third A member is not limited thereto. When the third A member is a laminated body, adjacent layers (or members, for example, a panel member and a protective member) constituting the laminated body may be laminated via an adhesive member or an adhesive member.

The elastic modulus (GPa) of the third A member is E3, and the thickness (mm) of the third A member is T3. The third A member preferably satisfies the following equation.
0.01 (kN / mm) ≤ E3 x T3 ≤ 0.35 (kN / mm)
In the third A member, when the product of the elastic modulus and the thickness is in such a range, the effect of controlling the thickness of the adhesive member as described above can be further easily obtained.

The third B member in the optical laminate may include at least a separator. The third B member may be composed of only a separator. The third B member is laminated with the second member so that the separator comes into contact with the adhesive member arranged on the side opposite to the first member side of the second member. Then, the separator is peeled off from the optical laminate, and the exposed adhesive member is attached to the third A member (specifically, the panel member or the laminate including the panel member) to form a flexible image display device. ..

(Panel member)
The panel member includes, for example, at least an image display panel. A sealing member (thin film sealing layer or the like) may be arranged on the visual side of the image display panel. The sealing member is usually arranged directly on the visible surface of the image display panel.

As the image display panel, a known one is used. Examples of the image display panel include an organic electroluminescence (EL) panel.

(Protective member)
Examples of the protective member include a sheet or film (or substrate) that holds or protects the panel member. The protective member may be one that holds the panel member, has an appropriate strength for protecting the panel member, and has an appropriate flexibility that does not hinder the flexibility of the flexible image display device. As the protective member, a resin sheet or the like is used. The material of the resin sheet is not particularly limited, and can be appropriately selected depending on the type of the image display panel, for example.

(Panel member with touch sensor)
The panel member with a touch sensor (specifically, each of the panel member with a first touch sensor and the panel member with a second touch sensor included in the third A member) is an integral body of the touch sensor and the panel member. .. Such a panel member with a touch sensor includes, for example, a structure in which an antistatic capacity type touch sensor of a metal mesh electrode is formed on a thin film sealing layer of an organic light emitting diode (OLED). LED. As the touch sensor, the above description may be referred to.

The panel member includes, for example, at least an image display panel. A sealing member (thin film sealing layer or the like) may be arranged on the visual side of the image display panel. The sealing member is usually arranged directly on the visible surface of the image display panel.

As the image display panel, a known one is used. Examples of the image display panel include an organic electroluminescence (EL) panel.

The panel member with a touch sensor may include a protective member. Examples of the protective member include a sheet or film (or substrate) that holds or protects the panel member. The protective member may be one that holds the panel member, has an appropriate strength for protecting the panel member, and has an appropriate flexibility that does not hinder the flexibility of the flexible image display device. As the protective member, a resin sheet or the like is used. The material of the resin sheet is not particularly limited, and can be appropriately selected depending on the type of the image display panel, for example.

The elastic modulus (GPa) of the panel member with a touch sensor is Ep, and the thickness (mm) of the panel member with a touch sensor is Tp. At this time, the panel member with the touch sensor preferably satisfies the following formula.
0.01 ≤ Ep x Tp ≤ 0.35
In the panel member with a touch sensor, when the product of the elastic modulus and the thickness is in such a range, the effect of controlling the thickness of each adhesive member as described above can be further easily obtained. The unit of Ep × Tp is kN / mm.

(Separator)
The separator (specifically, each of the first separator and the second separator included in the third B member) includes, for example, a base sheet and a release agent arranged on at least one surface of the base sheet. Sheets are used. The separator is arranged with the release agent in contact with the adhesive member. More specifically, the first separator is arranged in contact with the adhesive member arranged on the side opposite to the window member of the first member. The second separator is arranged in contact with the adhesive member arranged on the side opposite to the first member side of the second member.

The base sheet may have a structure other than the first separator or the third B member of the optical laminate, have appropriate strength and flexibility, and can easily form a release agent layer. As the base sheet, a resin film, paper, a laminate thereof, or the like is used. The material of the base sheet is determined according to the type of release agent, the composition of the optical laminate, and the like. As the resin film, for example, a polyester film (polyethylene terephthalate film or the like) or a polyolefin film (polypropylene film or the like) may be used. The thickness of the base sheet is not particularly limited, and can be selected in consideration of desired peelability. As the release agent, a known one can be used, and it is preferable to select one having a small residual amount of the adhesive member on the separator. For example, a silicone-based release agent or a fluorine-based release agent may be used.

(Decorative layer)
The decorative layer is, for example, at least one layer between the window member and the touch sensor or the panel member with the touch sensor (more specifically, the panel member with the first touch sensor or the panel member with the second touch sensor). Arranged so as to come into contact with the adhesive member. Further, when the adhesive member is included in the first member, it may be arranged so as to come into contact with the adhesive member. For example, a decorative layer may be formed on at least one of the surface of the window member on the first member side and the surface of the first member on the window member side. When the first member is an optical film, the surface of the first member on the first laminated body side or the panel member side with the first touch sensor (or the first separator side), and when the second member is an optical film, A decorative layer may be formed on at least one of the surfaces of the second member on the third A member side (or the third B member side). When the first member is an optical film and the first member includes a layer of the adhesive member, it is added to the surface of at least one of the layers sandwiching the layer of the adhesive member in contact with the adhesive member. A decorative layer may be formed. When the second member is an optical film and the second member includes a layer of the adhesive member, it is added to the surface of at least one of the layers sandwiching the layer of the adhesive member in contact with the adhesive member. A decorative layer may be formed. The decorative layer may be formed on at least one surface of the surfaces of these members and layers, and may be formed on two or more surfaces. The decorative layer is usually provided in a frame-like pattern on the outer periphery of the display unit on which the image is displayed so that the lead wiring of the drive element or the touch sensor is not visible from the outside. However, the shape of the decorative layer is not limited to the frame shape, and may be any shape that can hide the lead-out wiring and the like.

In addition to not reflecting the light from the viewing side, the decorative layer is required to shield the light from the side opposite to the viewing side. Such a decorative layer is composed of, for example, an ink layer, a metal thin film, and a thin film containing metal fine particles. The thin film containing the metal fine particles includes, for example, the metal fine particles and the binder resin. The decorative layer may have a single-layer structure or a laminated structure. The decorative layer of the laminated structure may be, for example, at least two laminated bodies selected from an ink layer, a metal thin film, and a thin film containing metal fine particles. The laminate also includes a laminate of two or more ink layers having different compositions, two or more metal thin films having different compositions, or a thin film containing two or more metal fine particles having different compositions.

The thickness of the decorative layer is, for example, 20 μm or less, and may be 15 μm or less. From the viewpoint that the step due to the decorative layer can be easily eliminated by the adhesive member, the thickness of the decorative layer is preferably 10 μm or less, and may be 8 μm or less or 5 μm or less. Further, when the thickness of the decorative layer is in such a range, it is easy to secure high bending resistance of the flexible image display device and the optical laminate. From the viewpoint of ensuring a higher concealing effect of the lead wiring, the thickness of the decorative layer is preferably 10 nm or more, more preferably 30 nm or more or 50 nm or more. These lower limit values and upper limit values can be arbitrarily combined.

The decorative layer may be formed, for example, by applying a coating agent containing a component of the decorative layer to the surface of the member or layer on which the decorative layer is formed. Further, the decorative layer may be formed by depositing constituent components on the surface of the member or layer on which the decorative layer is formed by a vapor phase method. In the case of a metal thin film, in particular, a decorative layer having a small thickness can be easily formed by using the vapor phase method. Examples of the gas phase method include a sputtering method, a vacuum deposition method, a chemical vapor deposition (CVD) method, and an electron beam deposition method.

A primer layer may be arranged on the surface of the member or layer on which the decorative layer is formed prior to application of the coating agent. For example, when the decorative layer is provided on the surface of the window member on the first member side, even if the primer layer is arranged between the decorative layer and the surface of the window member on the first member side. Good. When the decorative layer is provided on the surface of the first laminated body side of the first member or the panel member side with the first touch sensor (or the first separator side), the decorative layer and the first laminated body side of the first member Alternatively, a primer layer may be arranged between the surface of the panel member with the first touch sensor (or the side of the first separator). The primer layer contains, for example, at least one selected from the group consisting of metal compounds (metal oxides, metal nitrides, metal carbides, metal sulfides, etc.) and resin materials. The primer layer is preferably transparent.

The thickness of the primer layer is preferably small from the viewpoint that the adhesive member easily absorbs the step difference of the decorative layer and the optical influence of the primer layer can be easily suppressed. The thickness of the primer layer is, for example, 500 nm or less, preferably 100 nm or less or 30 nm or less.

The flexible image display device and the optical laminate are manufactured, for example, by laminating the constituent members while arranging the adhesive members between the respective members (and, if necessary, between the layers constituting the respective members). The stacking order is not particularly limited.

For example, the window member and the first member are laminated with the adhesive member interposed therebetween, and then the first member and the second member are laminated with the adhesive member interposed between the members. It may be laminated. Further, after laminating the first member and the second member with the adhesive member interposed between the members, the first member and the window member are laminated with the adhesive member interposed between the members. You may. It is preferable that each adhesive member is previously attached to one of the members that sandwich each adhesive member.

In the optical laminated body, the adhesive member may be arranged on the surface of the second member opposite to the first member side before laminating the second member with the first member. Further, the adhesive member may be arranged on the surface of the second member opposite to the first member side at an appropriate stage after the second member is laminated with the first member. In the optical laminated body, the separator is laminated on the adhesive member arranged on the surface of the second member opposite to the first member side before or after the adhesive member is arranged on the surface of the second member.

The flexible image display device is manufactured by preparing an optical laminate in advance, peeling the third B member (more specifically, a separator) from the optical laminate, and attaching the exposed adhesive member to the third A member. You may. Further, the third A member and the second member are laminated so that the adhesive member is interposed between them, and then the first member is laminated on the second member so that the adhesive member is interposed between them, and then. A flexible image display device may be produced by laminating a window member on a first member so that an adhesive member is interposed between them. Further, a laminated body of the third A member and the second member and a laminated body of the window member and the first member are prepared in advance, and these laminated bodies are placed between the first member and the second member. May be laminated in a state of interposing.

These manufacturing methods are merely examples, and are not limited thereto. Even when the flexible image display device or the optical laminate includes a panel member with a touch sensor, it can be manufactured by laminating each member according to these manufacturing methods.

FIG. 1 is a schematic cross-sectional view of the flexible image display device of the first embodiment according to the above aspect of the present invention. The flexible image display device 1 includes a laminated body of a window member 11, an optical film 12 as a first member, a touch sensor 13 as a second member, and a panel member 14 as a third A member. The laminated body of the touch sensor 13 which is the second member and the panel member 14 which is the third A member corresponds to the first laminated body L. The optical film 12 and the window member 11 are laminated with the adhesive member 21 interposed between the optical film 12 and the window member 11. The touch sensor 13 is laminated on the window member 11 via the optical film 12. An adhesive member 22 is interposed between the optical film 12 and the touch sensor 13. The panel member 14 is laminated on the window member 11 via the optical film 12 and the touch sensor 13. An adhesive member 23 is interposed between the touch sensor 13 and the panel member 14. The laminated body of the structure excluding the panel member 14 and the separator (not shown) in FIG. 1 corresponds to an optical laminated body.

The window member 11 includes, for example, a window film 111 and a hard coat layer 112 laminated on the window film 111. The hard coat layer 112 is provided on the side of the window member 11 opposite to the first member (optical film 12) side (more specifically, the surface of the window film 111 opposite to the first member side). .. The product of the elastic modulus E0 of the window member 11 and the thickness T0 satisfies E0 × T0> 0.32 (kN / mm).

The optical film 12 includes a polarizing plate composed of a polarizing element 121 and a protective film 122, and a retardation layer 123. The retardation layer 123 is arranged on the touch sensor 13 side, which is the second member, and is laminated on the polarizer 121 side of the polarizing plate.

The touch sensor 13 includes a transparent conductive layer 131 and a transparent film (touch sensor film) 132 as a transparent base material. The touch sensor 13 is arranged so that the transparent conductive layer 131 comes into contact with the adhesive member 22 arranged between the optical film 12 and the touch sensor 13.

The panel member 14 includes an organic EL panel (organic EL display) 141 and a thin film sealing layer 142. The panel member 14 is arranged so that the thin film sealing layer 142 comes into contact with the adhesive member 23 arranged between the touch sensor 13 and the panel member 14.

In the flexible image display device 1 and the optical laminate, E0 × T0> 0.32 (kN / mm), and the thickness of at least one of the adhesive members 21 to 23 is controlled so as to satisfy the condition of 20 μm or more. ing. Further, among the adhesive members 21 to 23, the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side is controlled so as to satisfy the condition of 10 μm or more. Therefore, even if the flexible image display device is repeatedly bent in a high temperature environment, high adhesiveness between the laminated members can be ensured. Further, it is possible to secure a relatively high pencil hardness on the surface of the flexible image display device 1 and the optical laminate on the window member 11 side.

In FIG. 1, a frame-shaped decorative layer 30 is provided on the surface of the first member (optical film 12) on the second member (touch sensor 13) side. In this case, by setting the thickness of the adhesive member (specifically, the adhesive member 22) to which the decorative layer 30 comes into contact to be 10 μm or more, the step caused by the decorative layer 30 can be effectively absorbed.

Note that FIG. 1 shows a case where the decorative layer 30 is formed on the surface of the optical film 12 on the touch sensor 13 side, but the case is not limited to this case. The decorative layer 30 may be provided on the surface of the window member 11 on the first member (optical film 12) side.

FIG. 1 shows a case where the first member is an optical film 12, the second member is a touch sensor 13, and the third A member is a panel member. However, not limited to this case, the touch sensor may be laminated on the window member 11 as the first member, and the optical film as the second member may be laminated on the window member 11 via the touch sensor. Further, as the third A member, a laminated body including the panel member as described above may be used.

FIG. 2 is a schematic cross-sectional view of the flexible image display device of the second embodiment. The flexible image display device 101 includes a window member 11, an optical film 12A as the first member, and a laminate of the first laminate L. The first laminated body L has a structure in which an optical film 12B, which is a second member, and a panel member 15B with a second touch sensor, which is a third A member, are laminated. An adhesive member 21 is interposed between the window member 11 and the optical film 12A. An adhesive member 22 is interposed between the optical film 12A and the first laminated body L, and an adhesive member 23 is interposed between the optical film 12B and the panel member 15B with a second touch sensor. Except for the configuration of the optical film 12A and the first laminated body L, which are the first members, the same as the first embodiment, and the description of the first embodiment can be referred to.

The optical film 12A is a polarizing plate composed of a polarizing element 121 and a protective film 122. In the optical film 12A, the polarizer 121 is arranged on the adhesive member 22 side (in other words, the side opposite to the window member 11). The optical film 12B is a laminate of two retardation layers 123 and 124.

In the second embodiment, for example, a laminate of a configuration excluding the panel member 15B with a second touch sensor and a separator (second separator) (not shown) corresponds to an optical laminate.

Also in the second embodiment, as in the first embodiment, E0 × T0> 0.32 (kN / mm), and the thickness of at least one layer of the adhesive members 21 to 23 satisfies the condition of 20 μm or more. Is controlled. Further, among the adhesive members 21 to 23, the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side is controlled so as to satisfy the condition of 10 μm or more. Therefore, even if the flexible image display device is repeatedly bent in a high temperature environment, high adhesiveness between the laminated members can be ensured. Further, it is possible to secure a relatively high pencil hardness on the surface of the flexible image display device 1 and the optical laminate on the window member 11 side.

FIG. 3 is a schematic cross-sectional view of the flexible image display device according to the third embodiment. The flexible image display device 201 includes a laminated body of a window member 11, an optical film 12 as a first member, and a panel member 15A with a first touch sensor. An adhesive member 21 is interposed between the window member 11 and the optical film 12. An adhesive member 22 is interposed between the optical film 12 and the panel member 15A with the first touch sensor. It is the same as the first embodiment except that the panel member 15A with the first touch sensor is arranged in place of the first laminated body L. For the configurations other than the panel member 15A with the first touch sensor, the description of the first embodiment can be referred to.

In the third embodiment, the laminated body of the configuration excluding the panel member 15A with the first touch sensor and the separator (first separator) (not shown) corresponds to the optical laminated body.

Also in the third embodiment, E0 × T0> 0.32 (kN / mm), and the thickness of at least one layer of the adhesive members 21 and 22 is controlled so as to satisfy the condition of 20 μm or more. Further, among the adhesive members 21 and 22, the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side is controlled so as to satisfy the condition of 10 μm or more. Therefore, as in the case of the first and second embodiments, high adhesiveness between the laminated members can be ensured, and on the surface of the flexible image display device 1 and the optical laminate on the window member 11 side. A relatively high pencil hardness can be secured.

[Example]
Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to the following Examples.

<< Examples 1 to 6, Comparative Examples 1 to 5, and Reference Examples 1 to 2 >>
(1) Preparation of Evaluation Sample An evaluation sample of the flexible image display device 1 as shown in FIG. 1 was prepared by the following procedure.
(A) Preparation of Window Member 11 As the window member 11, a transparent polyimide film as the window film 111 provided with an acrylic hard coat layer 112 (thickness 10 μm) on one side was used. The hard coat layer 112 was formed by using a coating agent for the hard coat layer. More specifically, first, a coating agent was applied to one side of the transparent polyimide film to form a coating layer, and the coating layer was heated together with the transparent polyimide film at 90 ° C. for 2 minutes. Next, the hard coat layer 112 was formed by irradiating the coating layer with ultraviolet rays using a high-pressure mercury lamp at an integrated light intensity of 300 mJ / cm ^2. The window member 11 was manufactured in this way.

The coating agent for the hard coat layer is 100 parts by mass of a polyfunctional acrylate (manufactured by Aika Kogyo Co., Ltd., product name "Z-850-16") as a base resin, and a leveling agent (manufactured by DIC Co., Ltd., trade name: GRANDIC PC-4100). ) 5 parts by mass and 3 parts by mass of a photopolymerization initiator (manufactured by Ciba Japan, trade name: Irgacure 907) are mixed and diluted with methylisobutylketone so that the dry solid content concentration becomes 50% by mass. Prepared by.

In Examples and Comparative Examples, a transparent polyimide film manufactured by KOLON, product name "A_50_O", and a thickness of 80 μm was used. The elastic modulus E0 of the window members of the examples and comparative examples obtained by the above-mentioned procedure was 4.0 GPa. In Examples and Comparative Examples, E0 × T0 (= 0.09 mm) = 0.36 kN / mm.

In the reference example, as the transparent polyimide film, a product name "A_50_O" manufactured by KOLON and a thickness of 50 μm were used. The elastic modulus E0 of the window member of the reference example obtained by the above-mentioned procedure was 4.7 GPa. In the reference example, it was E0 × T0 (= 0.06 mm) = 0.28 kN / mm.

(B) Preparation of Optical Film 12 An optical film 12 was prepared by the following procedure.

(Preparation of Polarizer 121)
An amorphous polyethylene terephthalate film (thickness 100 μm) containing 7 mol% of isophthalic acid unit was prepared as a base material made of a thermoplastic resin, and the surface was subjected to corona discharge treatment at an output discharge amount of ^{58 W / m 2 min.} ..

1% by mass of acetoacetyl-modified polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefima Z200 (average degree of polymerization 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%)) The added polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2%) was prepared, and an aqueous coating liquid containing 5.5% by mass of a polyvinyl alcohol (PVA) -based resin was prepared.

A coating liquid is applied to the surface of the base material so that the film thickness after drying is 12 μm, and the PVA-based resin layer is formed on the base material by drying in an atmosphere of 60 ° C. for 10 minutes by hot air drying. The provided laminate was produced.

The obtained laminate was first stretched 1.8 times at a free end (auxiliary stretching in the air) at 130 ° C. in the air to produce a stretched laminate. Next, a step of insolubilizing the PVA layer in which the PVA molecules contained in the stretched laminate were oriented was performed by immersing the stretched laminate in a boric acid insoluble aqueous solution having a liquid temperature of 30 ° C. for 30 seconds. The boric acid insoluble aqueous solution in this step is a boric acid aqueous solution having a boric acid content of 3 parts by mass with respect to 100 parts by mass of water. A colored laminate was produced by dyeing the obtained stretched laminate. In the colored laminate, the stretched laminate is mixed with a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ° C., and the single transmittance of the PVA layer constituting the polarizer finally produced is 40 to 44%. The PVA layer contained in the stretched laminate was stained with iodine by immersing it in the stretched laminate for a predetermined time. In this step, the staining solution is an aqueous solution containing iodine and potassium iodide (iodine concentration: 0.1-0.4% by mass, potassium iodide concentration: 0.7 to 2.8% by mass, iodine and potassium iodide). Concentration ratio: 1: 7). Next, a step of cross-linking the PVA molecules of the PVA layer on which iodine was adsorbed was performed by immersing the colored laminate in a boric acid cross-linked aqueous solution at 30 ° C. for 60 seconds. The boric acid cross-linked aqueous solution in this step is an aqueous solution containing boric acid and potassium iodide (boric acid content: 3 parts by mass with respect to 100 parts by mass of water, potassium iodide content: 3 parts by mass with respect to 100 parts by mass of water). Department).

The obtained colored laminate is finally stretched 3.05 times in the boric acid aqueous solution at a stretching temperature of 70 ° C. in the same direction as the above stretching in air (stretching in boric acid water). A laminate having a draw ratio of 5.50 times was obtained. The obtained laminate was taken out from the boric acid aqueous solution, and the boric acid adhering to the surface of the PVA layer was washed with a potassium iodide aqueous solution (potassium iodide content: 4 parts by mass with respect to 100 parts by mass of water). The washed laminate was dried by a drying step with warm air at 60 ° C. The thickness of the polarizer 121 contained in the dried laminate was 5 μm.

(Formation of protective film 122)
As the protective film 122, an acrylic film obtained by molding a methacrylic resin pellet having a glutarimide ring unit into a film by extrusion molding and then stretching the film was used. The thickness of the protective film was 40 μm. A polarizing plate was produced by bonding the protective film 122 and the polarizer 121 together using an adhesive (active energy ray-curable adhesive) and irradiating the adhesive with ultraviolet rays under the following conditions to cure the adhesive.
Gallium-filled metal halide lamp: Fusion UV Systems. Product name "Light HAMMER10" manufactured by Inc.
Bulb: V bulb Peak illuminance: 1600 mW / cm ²
Integrated irradiation dose: ^{1000 mJ / cm 2} (wavelength 380 to 440 nm)

The adhesive was prepared by mixing the following components at a ratio such that the content in 100% by mass of the adhesive had the following value, and stirring at 50 ° C. for 1 hour.
Hydroxyethyl acrylamide ... 11.4% by mass
Tripropylene glycol diacrylate ... 57.1% by mass
Acryloyl morpholine ... 11.4% by mass
2-Acetacetoxyethyl methacrylate ... 4.6% by mass
Acrylic polymer (ARUFON UP-1190, manufactured by Toagosei Co., Ltd.) ... 11.4% by mass
2-Methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one ... 2.8% by mass
Diethyl thioxanthone ... 1.3% by mass

(Preparation of retardation layer 123)
As the retardation layer 123, a retardation film including two layers, a retardation layer for a 1/4 wave plate in which a liquid crystal material is oriented and immobilized, and a retardation layer for a 1/2 wavelength plate was used. As a material for forming the retardation layer for the 1/2 wave plate and the retardation layer for the 1/4 wave plate, a polymerizable liquid crystal material (manufactured by BASF, trade name Pariocolor LC242) showing a nematic liquid crystal phase was used. The retardation layer 123 was prepared with reference to the description in paragraphs [0118] to [0120] of JP-A-2018-288573.

(Preparation of Optical Film 12)
The polarizing plate obtained above and the retardation layer 123 were continuously bonded by a roll-to-roll method using the above adhesive (active energy ray-curable adhesive). At this time, the layers were laminated so that the axis angle between the slow phase axis and the absorption axis was 45 °. The optical film 12 was produced in this way. The elastic modulus E1 of the optical film obtained by the procedure described above was 4.8 GPa, and E1 × T1 (= 0.05 mm) = 0.24 kN / mm.

(C) Formation of Decorative Layer A frame-shaped black ink layer (width 15 mm, thickness 5 μm) was provided as a decorative layer 30 on the surface of the optical film 12 on the touch sensor 13 side by screen printing. As the black ink, INQ-HF979 manufactured by Teikoku Printing Co., Ltd. was used.

(D) Preparation of Adhesives Adhesives (a1) to (a3) for producing the adhesive members 21 to 23 were prepared by the following procedure.

(A1) Acrylic Adhesive 1: An acrylic adhesive composition obtained by the following procedure (preparation of an acrylic polymer solution)
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler was charged with a monomer mixture containing 99 parts by mass of butyl acrylate and 1 part by mass of 4-hydroxybutyl acrylate. To 100 parts by mass of this monomer mixture, 2,2'-azobisisobutyronitrile was added as a polymerization initiator, and 0.1 part by mass was added together with ethyl acetate. Nitrogen gas was introduced while gently stirring the obtained mixture to carry out nitrogen substitution. Then, the liquid temperature in the flask was maintained at around 55 ° C., and the polymerization reaction was carried out for 7 hours. Ethyl acetate was added to the obtained reaction solution to prepare a solution of an acrylic polymer A1 having a weight average molecular weight of 1.6 million, which was adjusted to a concentration of a polymer component of 30% by mass.

(Preparation of acrylic adhesive 1)
0.1 part by mass of isocyanate-based cross-linking agent (trade name: Takenate D110N, trimethylolpropanexylylene diisocyanate, manufactured by Mitsui Kagaku Co., Ltd.), peroxide with respect to 100 parts by mass of the polymer component of the solution of acrylic polymer A1. 0.3 parts by mass of a cross-linking agent (benzoyl peroxide (trade name: Niper BMT, manufactured by Nippon Yushi Co., Ltd.)) and a silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) 0.08 The acrylic pressure-sensitive adhesive 1 was prepared by mixing with parts by mass.

(A2) Acrylic adhesive 2: Acrylic adhesive composition obtained by the following procedure (preparation of an acrylic polymer solution)
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler contains 94.9 parts by mass of butyl acrylate, 5 parts by mass of acrylic acid, and 0.1 parts by mass of 2-hydroxyethyl acrylate. A mixture of monomers was charged. To 100 parts by mass of the dry solid content of this monomer mixture, 0.1 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with ethyl acetate. Nitrogen gas was introduced while gently stirring the obtained mixture to carry out nitrogen substitution. Then, the liquid temperature in the flask was maintained at around 55 ° C., and the polymerization reaction was carried out for 7 hours. Ethyl acetate was added to the obtained reaction solution to prepare a solution of an acrylic polymer A2 having a weight average molecular weight of 2 million, wherein the concentration of the polymer component was adjusted to 30% by mass.

(Preparation of acrylic adhesive 2)
With respect to 100 parts by mass of the polymer component of the solution of the acrylic polymer A2, 0.6 parts by mass of an isocyanate-based cross-linking agent (trade name: Coronate L, trimethylolpropane tolylene diisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.) and silane coupling An acrylic pressure-sensitive adhesive 2 was prepared by mixing with 0.08 parts by mass of an agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Industry Co., Ltd.).

(A3) Acrylic adhesive 3: Acrylic adhesive composition obtained by the following procedure (preparation of acrylic oligomer)
60 parts by mass of dicyclopentanyl methacrylate and 40 parts by mass of methyl methacrylate as a monomer component, 3.5 parts by mass of α-thioglycerol as a chain transfer agent, and 100 parts by mass of toluene as a polymerization solvent are mixed under a nitrogen atmosphere. The mixture was stirred at 70 ° C. for 1 hour. Next, 0.2 parts by mass of 2,2'-azobisisobutyronitrile was added as a thermal polymerization initiator, and the mixture was 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, and the glass transition temperature (Tg) was 130 ° C.

(Preparation of prepolymer composition)
43 parts by mass of lauryl acrylate, 44 parts by mass of 2-ethylhexyl acrylate, 6 parts by mass of 4-hydroxybutyl acrylate, and 7 parts by mass of N-vinyl-2-pyrrolidone, and BASF's "Irgacure 184" as a photopolymerization initiator. A prepolymer composition (polymerization rate: about 10%) was obtained by mixing 015 parts by mass and irradiating with ultraviolet rays to carry out polymerization.

(Preparation of acrylic adhesive 3)
In addition to 100 parts by mass of the above prepolymer composition, 0.07 parts by mass of 1,6-hexanediol diacrylate, 1 part by mass of the above acrylic oligomer, and a silane coupling agent (“KBM403J” manufactured by Shin-Etsu Chemical Industry Co., Ltd.” ) 0.3 parts by mass was added and mixed uniformly to prepare an acrylic pressure-sensitive adhesive 3.

(E) Formation of Adhesive Layer Using the adhesive (adhesive shown in Table 1) prepared in (d) above, an adhesive layer for forming each layer of the adhesive members 21 to 23 was formed. More specifically, the adhesive shown in Table 1 was uniformly applied to the release film with a fountain coater and dried in an air circulation type constant temperature oven at 155 ° C. for 2 minutes to form an adhesive layer on the surface of the release film. .. As the release film, a polyethylene terephthalate film (transparent substrate, separator) having a thickness of 38 μm treated with a silicone-based release agent was used. The thickness of the pressure-sensitive adhesive layer was adjusted by the amount of the pressure-sensitive adhesive applied so that the thickness of each pressure-sensitive adhesive member in the sample had the values shown in Table 1.

(F) Preparation of Laminated Body Each member produced above was cut into a predetermined size as needed. The pressure-sensitive adhesive layer was transferred from the release film to one of the members holding each pressure-sensitive adhesive member, and each member was laminated so as to sandwich the pressure-sensitive adhesive layer and pressure-bonded by a hand roller. In this way, an evaluation sample in which each member was laminated by the adhesive member was prepared. As the touch sensor 13 and the panel member 14, a transparent polyimide film (manufactured by KOLON, product name "A_50_O", thickness 50 μm) was used as a dummy. The elastic modulus E2 (or E3) of the transparent polyimide film obtained by the procedure described above was 6 GPa, and E2 (or E3) × T2 (or T3) = 0.3 kN / mm.

(2) Evaluation (a) Storage elastic modulus of the adhesive member The storage elastic modulus of each adhesive member was determined by the procedure described above. The storage elastic modulus of the pressure-sensitive adhesive member using each acrylic pressure-sensitive adhesive is as follows.
Adhesive member using acrylic adhesive 1 (a1): 0.08 MPa
Adhesive member using acrylic adhesive 2 (a2): 0.12 MPa
Adhesive member using acrylic adhesive 3 (a3): 0.03 MPa

(B) Pencil hardness test An evaluation sample was placed on a glass plate, and the pencil hardness on the surface of the window member 11 side (the surface of the hard coat layer 112) was measured.

(C) Adhesiveness The evaluation sample obtained above was cut into strips of 100 mm × 20 mm with the direction of the absorption axis of the polarizing plate as the long side. Set the cut out sample in a no-load U-shaped expansion / contraction tester (“Small desktop durability tester DLMD111LHA” and “U-shape expansion / contraction test jig” manufactured by Yuasa System Equipment Co., Ltd.) so that the window member side is inside the bend. Then, a bending test was conducted under the following conditions.
Environmental conditions: 60 ° C, 55% RH
Test speed: 60 rpm
Bending radius: R3
Number of bends: 100,000 times

The state of peeling at the bent portion of the sample after the test was visually observed and evaluated according to the following criteria.
A: No peeling has occurred between the laminated members.
B: Peeling is observed between the laminated members.

The results of Examples 1 to 6, Comparative Examples 1 to 5, and Reference Examples 1 to 2 are shown in Table 1. In these tables, e1 to e6 are Examples 1 to 6, c1 to c5 are Comparative Examples 1 to 5, and r1 to r2 are Reference Examples 1 and 2.

As shown in Table 1, when E0 × T0 ≦ 0.32 (kN / mm), there is no layer of the adhesive member having a thickness of 20 μm or more, and the layer of the adhesive member having a thickness of less than 10 μm is formed. High adhesiveness is obtained even when continuous (r1 and r2). However, even if the thickness of the layer of the adhesive member is the same as that of r1 and r2, when E0 × T0> 0.32 (kN / mm), peeling occurs between the laminated members (c3 and c5). .. Further, as shown in Table 1, even when a plurality of layers of adhesive members having a relatively large thickness (specifically, 15 μm) are provided, peeling between the laminated members cannot be suppressed (c1 and). c4).

On the other hand, in the embodiment, the thickness of at least one layer of the plurality of adhesive members is 20 μm or more, and the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side is 10 μm or more. With such a configuration, even when E0 × T0> 0.32 (kN / mm), no peeling is observed between the laminated members in the bending test in a high temperature environment, and high adhesiveness can be ensured (e1). ~ E6). Further, even when the sample contains a layer of an adhesive member having a small thickness of less than 10 μm, high adhesiveness can be ensured (e1 and e3).

In any of the examples, a high pencil hardness of 3H or more can be secured. From the viewpoint of ensuring higher pencil hardness, the average value of the thicknesses of the plurality of layers of the adhesive member is preferably 20 μm or less or less than 20 μm, and more preferably 19 μm or less or 18 μm or less. From the same viewpoint, the thickness of the first layer (that is, the adhesive member 21) from the window member side is preferably 20 μm or less or less than 20 μm, more preferably 17 μm or less, still more preferably 16 μm or less or 15 μm or less.

<< Examples 7 to 12, Comparative Examples 6 to 9, and Reference Examples 3 to 4 >>
An evaluation sample of the flexible image display device 201 as shown in FIG. 3 was prepared according to Examples 1 to 6. Instead dummy of data Tchisensa 13 and panel member 14 of Example 1, use as a dummy of the first touch sensor with the panel member 15A, a transparent polyimide film (KOLON Co., product name "A_50_O", thickness 50 [mu] m) as a dummy There was.

For the formation of the pressure-sensitive adhesive layer, a pressure-sensitive adhesive (the pressure-sensitive adhesive shown in Table 2) prepared in the same manner as in Examples 1 to 6 was used. The thickness of the pressure-sensitive adhesive layer was adjusted by the amount of the pressure-sensitive adhesive applied so that the thickness of each pressure-sensitive adhesive member in the sample had the values shown in Table 2.

In Examples and Comparative Examples, a transparent polyimide film manufactured by KOLON, product name "A_50_O", and a thickness of 80 μm was used as the window member. The elastic modulus E0 of the window members of the examples and comparative examples obtained by the above-mentioned procedure was 4.0 GPa. In Examples and Comparative Examples, E0 × T0 (= 0.09 mm) = 0.36 kN / mm.

In the reference example, a transparent polyimide film manufactured by KOLON, having a product name of "A_50_O" and a thickness of 50 μm was used as the window member. The elastic modulus E0 of the window member of the reference example obtained by the above-mentioned procedure was 4.7 GPa. In the reference example, it was E0 × T0 (= 0.06 mm) = 0.28 kN / mm.

Using the obtained sample, evaluation was performed in the same manner as in Examples 1 to 6.
The results of Examples 7 to 12, Comparative Examples 6 to 9, and Reference Examples 3 to 4 are shown in Table 2. In Table 2, Examples 7 to 12 are e7 to e12, Comparative Examples 6 to 9 are c6 to c9, and Reference Examples 3 to 4 are r3 to r4.

As shown in Table 2, when E0 × T0 ≦ 0.32 (kN / mm), there is no layer of the adhesive member having a thickness of 20 μm or more and a layer of the adhesive member having a thickness of less than 10 μm. High adhesiveness is obtained even when continuous (r4 and r3). However, even if the thickness of the layer of the adhesive member is the same as that of r3 and r4, when E0 × T0> 0.32 (kN / mm), peeling occurs between the laminated members (c7 and c9). .. Further, as shown in Table 2, even when a plurality of layers of adhesive members having a relatively large thickness (specifically, 15 μm) are provided, peeling between the laminated members cannot be suppressed (c6 and). c8).

On the other hand, in the embodiment, the thickness of at least one layer of the plurality of adhesive members is 20 μm or more, and the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side is 10 μm or more. With such a configuration, even when E0 × T0> 0.32 (kN / mm), no peeling is observed between the laminated members in the bending test in a high temperature environment, and high adhesiveness can be ensured (e7). ~ E12). Further, even when the sample contains a layer of an adhesive member having a small thickness of less than 10 μm, high adhesiveness can be ensured (e7 and e9).

In any of the examples, a high pencil hardness of 3H or more can be secured. From the viewpoint of ensuring higher pencil hardness, the thickness of the first adhesive member layer from the window member side is preferably 20 μm or less, and the average value of the thicknesses of the plurality of adhesive members is preferably 20 μm or less. ..

1, 101, 201: Flexible image display device 11: Window member 111: Window film 112: Hard coat layer 12, 12A, 12B: Optical film 121: Polarizer 122: Protective film 123, 124: Phase difference layer 13: Touch sensor 131: Transparent conductive layer 132: Transparent film 14: Panel member 141: Organic EL panel 142: Thin film sealing layer 15A: Panel member with first touch sensor 15B: Panel member with second touch sensor L: First laminated body 21, 22, 23 : Adhesive member 30: Decorative layer

Claims (14)

A window member with a transparent resin film and
The first member laminated on the window member and
A first laminated body or a panel member with a first touch sensor laminated on the window member via the first member.
A flexible image display device including a plurality of layers of adhesive members.
The first laminated body is a laminated body of a second member laminated via the first member and a third A member laminated via the first member and the second member on the window member. Yes,
When the flexible image display device includes the first laminated body,
One of the first member and the second member is an optical film, and the other is an optical film or a touch sensor.
The third A member includes at least a panel member.
The plurality of layers of the adhesive member are arranged at least between the window member and the first member, between the first member and the second member, and between the second member and the third A member. Including 3 layers to be
When the flexible image display device includes the panel member with the first touch sensor,
The first member is an optical film and
The plurality of layers of the adhesive member includes at least two layers arranged between the window member and the first member and between the first member and the panel member with the first touch sensor.
When the elastic modulus (GPa) of the window member is E0 and the thickness (mm) of the window member is T0, E0 × T0 (kN / mm) satisfies the condition of E0 × T0> 0.32.
The thickness of at least one layer of the plurality of adhesive members satisfies the condition of 20 μm or more.
A flexible image display device in which the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side of the plurality of layers of the adhesive member satisfies a condition of 10 μm or more. The third A member is provided.
The flexible image display device according to claim 1, wherein one of the first member and the second member is the optical film, and the other is the touch sensor. The flexible image display device according to claim 1 or 2, wherein the plurality of layers of the adhesive member further includes at least one layer arranged in the third A member. The third A member includes a panel member with a second touch sensor.
The flexible image display device according to claim 1, wherein each of the first member and the second member is the optical film. The flexible image display device according to any one of claims 1 to 4, wherein the maximum value of the thickness of the plurality of layers of the adhesive member satisfies the condition of 50 μm or less. Among the plurality of layers of the adhesive member, the thickness of the first layer from the window member side satisfies the condition of 20 μm or less.
The flexible image display device according to any one of claims 1 to 5, wherein the average value of the thicknesses of the plurality of layers of the adhesive member satisfies the condition of 20 μm or less. The flexible image display device according to any one of claims 1 to 6, wherein the storage elastic modulus of each layer of the plurality of layers of the adhesive member at 25 ° C. satisfies the condition of 1 MPa or less. The flexible image display device according to any one of claims 1 to 7, wherein the thickness of each layer of the plurality of layers of the adhesive member satisfies the condition of 3 μm or more. The flexible image display device according to any one of claims 1 to 8, wherein E0 × T0 regulates the pencil hardness specified in JIS K 5600-5-4: 1999 on the surface on the window member side. The flexible image display device according to any one of claims 1 to 9 , wherein the hardness according to the pencil hardness test specified in JIS K 5600-5-4: 1999 on the window member side is H or more. The window member includes a hard coat layer and has a hard coat layer.
The flexible image display device according to any one of claims 1 to 10 , wherein the hard coat layer is provided at least on the side of the window member opposite to the first member side. The flexible image display device according to any one of claims 1 to 11, wherein the elastic modulus E0 of the window member is 0.53 GPa or more and 16 GPa or less. Used in the flexible image display device according to any one of claims 1 to 12.
A window member with a transparent resin film and
The first member laminated on the window member and
A second laminated body or a first separator laminated on the window member via the first member,
An optical laminate comprising a plurality of layers of adhesive members.
The second laminated body is a laminated body of a second member laminated via the first member and a third B member laminated via the first member and the second member on the window member. Yes,
When the optical laminate includes the second laminate,
One of the first member and the second member is an optical film, and the other is an optical film or a touch sensor.
The third B member includes at least a second separator.
The plurality of layers of the adhesive member are arranged at least between the window member and the first member, between the first member and the second member, and between the second member and the third B member. Including 3 layers to be
When the optical laminate includes the first separator
The first member is an optical film and
The plurality of layers of the adhesive member includes at least two layers arranged between the window member and the first member and between the first member and the first separator.
When the elastic modulus (GPa) of the window member is E0 and the thickness (mm) of the window member is T0, E0 × T0 (kN / mm) satisfies the condition of E0 × T0> 0.32.
The thickness of at least one layer of the plurality of adhesive members satisfies the condition of 20 μm or more.
An optical laminate in which the thickness of at least one of the nth layer and the (n + 1) th layer from the window member side of the plurality of layers of the adhesive member satisfies the condition of 10 μm or more. The third B member is provided, and the third B member is provided.
The optical laminate according to claim 13 , wherein one of the first member and the second member is the optical film, and the other is the touch sensor.

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