WO2023153052A1

WO2023153052A1 - Window base material, multilayer window, multilayer window with adhesive layer, and display device including multilayer window

Info

Publication number: WO2023153052A1
Application number: PCT/JP2022/043981
Authority: WO
Inventors: 孝伸矢野; 拓也森
Original assignee: 日東電工株式会社
Priority date: 2022-02-10
Filing date: 2022-11-29
Publication date: 2023-08-17
Also published as: JP2023117335A

Abstract

This window base material includes a structure in which glass and a resin film 2A are laminated. The maximum value of an impact load change determined in a pen drop test at 25°C is 13 N/ms or less. The product, M2A × T2A, of the mean value M2A of the tensile storage modulus in a 2-20 kHz frequency range and a temperature of 25°C of the resin film 2A and the thickness T2A of the resin film 2A satisfies 50 GPa·μm ≤ M2A × T2A ≤ 250 GPa·μm.

Description

Substrate for window, multi-layer window, multi-layer window with adhesive layer, and display device including multi-layer window

The present disclosure relates to a window substrate containing glass, a multilayer window, a multilayer window with an adhesive layer, and a display device including a multilayer window.

A display device may include a window from the viewpoint of protecting constituent members such as an optical film, a touch sensor, and a display panel. The viewing-side surface of such displays usually corresponds to the surface of the window. The window may also have a multi-layer structure, including, for example, a transparent substrate such as a resin film or glass.

Patent document 1 includes a flexible display panel for displaying images and a window disposed on a display surface of the flexible display panel, the window comprising a first protective layer and a thin film glass disposed on the first protective layer. A display device is proposed that includes a layer and a second protective layer disposed over the thin glass layer. It is taught that the first protective layer may comprise a first impact absorbing layer and the second protective layer may comprise a second impact absorbing layer. FIG. 3b includes a second protective layer (LPF2) comprising a thin glass layer (TG), a hard coat layer (HC) and a second shock absorbing layer (UCF) disposed therebetween, and the thin glass A window (WM2) is described comprising a first protective layer (LPF) arranged below the layer (TG). In the window (WM2), the first protective layer (LPF1) comprises a first shock absorbing layer (LCF1) and an inner adhesive layer disposed between the thin glass layer (TG) and the first shock absorbing layer (LCF1) (IAM).

Korean Patent Publication No. 10-2020-0072643 (claims 1, 4 and 6, FIG. 3b, [0072]-[0085])

The surface on the viewing side of the display device is sometimes required to have high scratch resistance. Therefore, it is preferable that the hardness of the surface of the window corresponding to the viewing side surface of the display device is high. A window containing glass is sometimes used from the viewpoint of easily obtaining a relatively high surface hardness. In addition, the window is required not to transmit impacts to members arranged under the window (on the side opposite to the viewing side). However, glass is brittle and has low flexibility. Therefore, when an impact (particularly a fast impact) is applied to the window, it is difficult to sufficiently absorb or disperse the impact force.

A first aspect of the present disclosure is a window substrate including a structure in which glass and a resin film (resin film 2A) are laminated,
The maximum value of the impact load change required by the pen drop test at 25 ° C. is 13 N / ms or less,
The product of the average value M2A of the tensile storage modulus of the resin film 2A at 25° C. and the frequency range of 2 kHz or more and 20 kHz or less and the thickness T2A of the resin film 2A: M2A×T2A is 50 GPa μm≦M2A×T2A≦ The present invention relates to a base material for windows that satisfies 250 GPa·μm.

A second aspect of the present disclosure comprises at least a first base material, the window base material as a second base material, and a first adhesive layer interposed between the first base material and the second base material. A multi-layer window comprising:
The first substrate relates to a multi-layer window, including the viewing side surface Sv of the multi-layer window.

A third aspect of the present disclosure provides a multi-layer window as described above;
a release liner laminated to the side opposite the viewing side of the multilayer window;
and a third adhesive layer interposed between the multilayer window and the release liner.

A fourth aspect of the present disclosure is a multi-layer window as described above;
a display panel or laminate comprising a display panel laminated on the side opposite to the viewing side of the multilayer window;
and a third adhesive layer interposed between the multilayer window and the display panel or the laminate.

A base material for a window that can ensure a hard pencil hardness on the surface of the multilayer window on the viewing side and can suppress the propagation of a rapid impact load to a member arranged on the side opposite to the viewing side of the base material for a window, a multilayer window, A multilayer window with an adhesive layer and a display device can be provided.

1 is a schematic cross-sectional view of a display device including a window substrate (or multilayer window) according to an embodiment of the present disclosure; FIG.

While the novel features of the present invention are set forth in the appended claims, the present invention, both as to construction and content, together with other objects and features of the present invention, will be further developed by the following detailed description in conjunction with the drawings. will be well understood.

(1) The window base material of the present disclosure includes a structure in which glass and resin film 2A are laminated. The window substrate has a maximum impact load change of 13 N/ms or less in a pen drop test at 25°C. The product of the average value M2A of the tensile storage modulus of the resin film 2A and the thickness T2A of the resin film 2A in the frequency range of 2 kHz to 20 kHz at 25 ° C. and 2 kHz to 20 kHz: M2A × T2A is 50 GPa · μm ≤ M2A × T2A ≤ 250 GPa · satisfies μm.

(2) In (1) above, the window substrate may include the resin film 2A arranged on the viewing side, glass, and the adhesive layer 2A interposed between the resin film 2A and the glass. The product M2A×T2A may satisfy 50 GPa·μm≦M2A×T2A≦200 GPa·μm.

(3) In (2) above, the indentation elastic modulus of the adhesive layer 2A at 25°C may be 0.01 MPa or more and 1 MPa or less.

(4) In (2) or (3) above, the window substrate further includes a resin film 2B disposed on the opposite side of the glass to the viewing side, and an adhesive interposed between the glass and the resin film 2B. Layer 2B or adhesive layer 2B may also be included.

(5) In (4) above, the thickness T2B of the resin film 2B may be 40 μm or more and 100 μm or less.

(6) In (4) or (5) above, the resin film 2B may be a polyester film having an indentation elastic modulus of 0.2 GPa or more and 1.5 GPa or less at 25°C.

(7) In any one of (1) to (6) above, the thickness T2A of the resin film 2A may be 40 μm or more and 100 μm or less.

(8) In any one of the above (1) to (7), the average value M2A of the tensile storage modulus of the resin film 2A at 25° C. and in the frequency range of 2 kHz or more and 20 kHz or less is 0.1 GPa or more and 10 GPa or less. There may be.

(9) In any one of (1) to (8) above, the resin film 2A may be a polyester film having an indentation elastic modulus at 25°C of 0.2 GPa or more and 1.5 GPa or less.

(10) A multilayer window of the present disclosure comprises: a first substrate; the window substrate according to any one of (1) to (9) above as a second substrate; and a first adhesive layer interposed between the two substrates. The first substrate includes a viewing side surface Sv of the multilayer window.

(11) In (10) above, the indentation elastic modulus of the first adhesive layer at 25°C may be 0.01 MPa or more and 1 MPa or less.

(12) In (10) or (11) above, the surface Sv of the multilayer window may have a pencil hardness higher than 7B.

(13) In any one of (10) to (12) above, the first base material may include a first resin film. The average value M1 of the tensile storage modulus of the first resin film at 25° C. and in the frequency range of 2 kHz or more and 20 kHz or less may be 3 GPa or more and 10 GPa or less. The thickness T1 of the first resin film may be 30 μm or more and 100 μm or less.

(14) In (13) above, the first resin film may contain a polyimide resin.

(15) The multi-layer window with an adhesive layer of the present disclosure comprises the multi-layer window according to any one of (10) to (14) above, a release liner laminated on the side opposite to the viewing side of the multi-layer window, a third adhesive layer interposed between the multilayer window and the release liner.

(16) A display device of the present disclosure includes the multilayer window according to any one of (10) to (14) above, and a display panel or a display panel laminated on the side opposite to the viewing side of the multilayer window. a laminate; and a third adhesive layer interposed between the multilayer window and the display panel or laminate.

Below, the window substrate, multilayer window, adhesive layer-attached multilayer window, and display device of the present disclosure, including the above (1) to (16), will be described more specifically. At least one of the above (1) to (16) may be combined with at least one of the elements described below within a technically consistent range.

When referring to the drawings, the shape or dimensions of each component in each drawing are not shown to the same scale as the actual. The relative relationships of these dimensions are shown schematically and exaggerated to clarify the characteristics of each component.

A window base material according to the first aspect of the present disclosure includes a structure in which glass and a resin film are laminated. The maximum value of impact load change required by the pen drop test at 25°C is 13 N/ms or less. The product of the average value M2A of the tensile storage modulus of the resin film and the thickness T2A of the resin film in the frequency range of 25 ° C. and 2 kHz to 20 kHz: M2A × T2A is 50 GPa · μm ≤ M2A × T2A ≤ 250 GPa · μm Sufficient.

A multilayer window according to a second aspect of the present disclosure includes at least a first substrate, a second substrate, and a first adhesive layer interposed between the first substrate and the second substrate. Here, the first substrate includes the viewing side surface Sv of the multilayer window. The window substrate according to the first aspect is used, for example, as the second substrate of the multilayer window according to the second aspect. In this case, the resin film contained in the window substrate corresponds to the resin film 2A of the multilayer window. Hereinafter, the resin film included in the window base material may be referred to as a resin film 2A.

The glass contained in the base material for windows (second base material) is layered glass such as sheet-like or film-like. Hereinafter, the base material for windows may be referred to as a second base material.

The windows of display devices require relatively high hardness. The higher hardness of the constituent members of the multilayer window results in a relatively hard pencil hardness of the multilayer window, but it is difficult to absorb or dissipate the stress due to impact. In the event of a particularly fast impact, stress absorption or dispersion cannot keep up, and the load applied to the member (such as the display panel or laminate including the display panel) placed on the opposite side of the multi-layer window from the viewing side increases. , may cause damage. On the other hand, increasing the flexibility of the components of the multi-layer window increases the absorption of stress from fast impact, but softens the pencil hardness. In other words, in a multilayer window, there is a trade-off relationship between the pencil hardness of the surface on the viewing side and the reduction of fast impact load propagation (in other words, delay of impact load propagation), and it is difficult to achieve both. In addition, if the flexibility of the constituent members of the multilayer window is too high, deformation stress tends to cause strain in the vicinity of the glass included in the multilayer window, and the glass tends to crack.

In the present disclosure, the second base material includes a laminated structure of glass and resin film 2A, and the maximum value of impact load change obtained in a pen drop test at 25°C is defined as a specific range. In addition, the product of the average value M2A of the tensile storage modulus of the resin film 2A at 25° C. and the frequency range of 2 kHz to 20 kHz and the thickness T2A of the resin film 2A: M2A×T2A is 50 GPa·μm≦M2A×T2A. ≦250 GPa·μm is satisfied. Therefore, even if a fast impact is applied to the surface, the resin film 2A can absorb or disperse the stress due to the impact while ensuring a certain degree of pencil hardness on the viewing side surface Sv of the multilayer window. In particular, for multi-layer windows containing glass, even if the impact force itself is not very large, when a fast impact force such as that applied in a pen drop test is applied to the surface of the multi-layer window, the speed of propagation of the impact force is affected by the impact. A fast impact load is likely to be transmitted to the member arranged on the side opposite to the viewing side of the multi-layer window because the speed of absorbing or dispersing the stress cannot catch up. The use of the second substrate slows down the propagation of the impact load, particularly when such a fast impact force is applied to the multilayer window, so that the member located on the opposite side of the multilayer window from the viewing side experiences a rapid impact. It is possible to suppress the transmission of load. In addition, by using the second base material, it is possible to suppress the occurrence of distortion around the glass, thereby suppressing cracking of the glass.

The second base material includes at least a structure in which glass and resin film 2A are laminated. The second base material may include the resin film 2B in addition to the glass and the resin film 2A. In the second substrate, the glass and the resin film 2A may be laminated via the adhesive layer 2A. In the second base material, the resin film 2A may be arranged on the viewing side of the glass. In this case, the glass may be sandwiched between the resin films 2A and 2B. An adhesive layer 2B or an adhesive layer 2B is usually interposed between the glass and the resin film 2B.

In the multi-layer window, the first adhesive layer is the adhesive layer located on the most visible side. At this time, the part which contacts with the 1st adhesion layer and is located in the visual recognition side rather than the 1st adhesion layer is called a 1st base material. The first base material may include a resin film (hereinafter sometimes referred to as a first resin film). In the multi-layer window, the laminated portion of the glass and the resin film 2A (or the laminated portion of the glass and the resin films 2A and 2B) located on the side opposite to the viewing side with respect to the first adhesive layer is the second substrate. called.

In this specification, in the lamination direction (in other words, the average thickness direction of each member) of each member constituting the window substrate, the multilayer window, the adhesive layer-attached multilayer window, and the display device, each member Alternatively, the relative positional relationship of the layers that make up each member is expressed by the expression "visible side" or "opposite side to the visible side" of the window substrate, multilayer window, adhesive layer-attached multilayer window, or display device. can be expressed as Further, in this specification, the multilayer window with an adhesive layer includes a multilayer window, a release liner laminated on the opposite side of the multilayer window from the viewing side, and an adhesive layer interposed therebetween (third adhesive layer). have The multi-layer window with an adhesive layer can be obtained, for example, by peeling off the release liner and passing through the third adhesive layer a member other than the multi-layer window constituting the display device or a laminate (optical film, touch sensor, display panel, or any of these). (such as a laminate comprising at least two of the members) to form a display device.

Elements such as the position of the glass in the laminated structure of the second base material, the properties of the resin film 2A, the number or position of the adhesive layer, etc. greatly affect the impact load change in the pencil hardness and the pen drop test on the surface Sv on the viewing side. . In particular, the second substrate includes glass and the resin film 2A, and the product of the average value M2A of the tensile storage modulus of the resin film 2A in the frequency range of 2 kHz or more and 20 kHz or less and the thickness T2A of the resin film 2A: M2A × By setting T2A within the above specific range, it is possible to keep the impact load change low while ensuring a certain degree of pencil hardness. In the frequency range described above, it is possible to grasp the change in the viscoelasticity of the resin film 2A when a deformation stress at a relatively high speed is applied. The ability to absorb or disperse deformation stress is also affected by the thickness T2A of the resin film 2A. Therefore, M2A×T2A indicates the stress absorbability or dispersibility of the resin film 2A when deformation stress is applied at a relatively high speed, in other words, it can be said to be an index indicating the easiness of deformation of the resin film 2A. .

The adhesive layer is a layer formed by curing a curable adhesive (in other words, a layer of a cured product) and does not have fluidity. On the other hand, the adhesive layer is a layer formed of a non-hardening adhesive and has fluidity.

In this specification, the shear storage modulus of the adhesive layer at 25°C is usually 10 MPa or less, may be 1 MPa or less, or may be 0.1 MPa or less. When the shear storage modulus of the adhesive layer is within this range, high adhesiveness can be ensured, and unlike the case of a hardened adhesive layer, even when a force such as an impact force is propagated, the adhesive layer is deformed appropriately. , easy to absorb or dissipate stress quickly. The shear storage modulus of each adhesive layer at 25°C may be 0.001 MPa or more.

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

In one embodiment of the present disclosure, the second base material may include, for example, the resin film 2A arranged on the viewing side, glass, and the adhesive layer 2A interposed between the resin film 2A and the glass. In this case, M2A×T2A may satisfy 50 GPa·μm≦M2A×T2A≦200 GPa·μm. When M2A×T2A is 50 GPa·μm or more, excessive flexibility of the resin film 2A is suppressed, and the flexibility and height can be kept within an appropriate range. In addition, since the resin film 2A is arranged on the viewing side of the glass, even if a fast impact is applied from the viewing side surface Sv of the multilayer window, the resin film 2A is appropriately deformed and the stress caused by the impact is applied. can be effectively absorbed or dispersed. Moreover, when M2A×T2A is 200 GPa·μm or less, excessive hardening of the resin film 2A is suppressed. Therefore, the stress due to the impact can be effectively absorbed by the resin film 2A. These can reduce the impact load change when a fast impact is applied from the viewing side surface Sv of the multilayer window, and can reduce the stress transmitted to the glass. Moreover, the resin film 2A and the glass are adhered by the adhesive layer 2A. The adhesive layer 2A has fluidity and is softer than the adhesive layer, which is a cured product. Therefore, in addition to the resin film 2A, the adhesive layer 2A can quickly absorb or disperse the stress due to the impact.

In the above embodiment, the thickness T2A of the resin film 2A may be 40 µm or more and 100 µm or less. In this case, since the resin film 2A has an appropriate thickness T2A, it is easy to adjust M2A×T2A within the above range, and the stress due to the impact is released more quickly by the moderate deformation of the resin film 2A and the deformation of the adhesive layer 2A. Can be absorbed or dispersed.

In the above embodiment, the second substrate further includes the resin film 2B arranged on the side opposite to the viewing side of the glass, and the adhesive layer 2B or adhesive layer 2B interposed between the glass and the resin film 2B. It's okay. The resin film 2B can further enhance the effect of protecting the glass. Moreover, the stress propagating to the member arranged on the side opposite to the viewing side of the multilayer window can be further reduced.

The thickness T2B of the resin film 2B may be 40 µm or more and 100 µm or less. Since the resin film 2B has an appropriate thickness T2B, even when the stress due to the impact is transmitted to the resin film 2B, the resin film 2B is deformed and the stress due to the impact can be quickly absorbed or dispersed. The effect of reducing the stress propagating to the member arranged on the side opposite to the viewing side of the second base material is enhanced.

The resin film 2B may be a polyester film having an indentation modulus at 25°C of 0.2 GPa or more and 1.5 GPa or less. Since the resin film 2B has appropriate flexibility and hardness, even if the stress due to the impact is transmitted to the resin film 2B, the resin film 2B is deformed to absorb or disperse the stress due to the impact. The effect of reducing the stress propagating to the member arranged on the side opposite to the viewing side of the second base material is enhanced.

In the present disclosure, the average value M2A of the tensile storage modulus of the resin film 2A may be 0.1 GPa or more and 10 GPa or less. In this case, in the resin film 2A, it is easy to obtain a higher effect of absorbing or dispersing the stress due to the impact, and it is easy to further reduce the load change due to the impact.

The resin film 2A may be a polyester film having an indentation elastic modulus of 0.2 GPa or more and 1.5 GPa or less at 25°C. In this case, since the resin film 2A has appropriate flexibility and hardness, the resin film 2A can more easily absorb or disperse the stress due to the impact, and can further easily reduce the load change due to the impact. Also, it is easy to adjust M2A×T2A within the above range.

The indentation elastic modulus at 25°C of the adhesive layer 2A interposed between the resin film 2A and the glass may be 0.01 MPa or more and 1 MPa or less. When the indentation elastic modulus of the adhesive layer 2A is within such a range, the adhesive layer 2A can easily absorb or disperse stress due to impact, and can further reduce load changes due to impact.

The present disclosure also includes a multilayer window containing the above base material for windows (second base material). The multilayer window includes at least a first base material, the window base material (second base material), and a first adhesive layer interposed therebetween. The first substrate includes a viewing side surface Sv of the multilayer window.

The indentation elastic modulus at 25°C of the first adhesive layer interposed between the first base material and the second base material may be 0.01 MPa or more and 1 MPa or less. When the indentation modulus of the first adhesive layer is within such a range, the first adhesive layer can more easily absorb or disperse the stress due to impact, reduce the stress transmitted to the second base material, and reduce the load change due to impact. The effect of reducing is enhanced.

The first base material may contain the first resin film. The average value M1 of the tensile storage modulus of the first resin film at 25° C. and in the frequency range of 2 kHz or more and 20 kHz or less may be 3 GPa or more and 10 GPa or less. The thickness T1 of the first resin film may be 30 μm or more and 100 μm or less. In these cases, the first resin film tends to impart high hardness to the first base material including the surface Sv on the viewer side of the window, which is advantageous in enhancing the scratch resistance of the surface on the viewer side of the multilayer window. Therefore, it is possible to secure a hard pencil hardness of the surface Sv on the viewing side of the multilayer window. The first base material may contain a hard coat layer. The hard coat layer is a thin coating layer formed at least on the surface of the first substrate on the viewing side, and is distinguished from the first resin film.

The first resin film may contain, for example, polyimide resin. In this case, the surface Sv on the viewing side of the multilayer window tends to have a higher pencil hardness and is likely to have high scratch resistance.

The pencil hardness of the viewing side surface Sv of the multilayer window is preferably higher than 7B. In the present disclosure, the second base material includes glass and the resin film 2A, and by setting 2M2A×T2A of the resin film 2A within the above range, while suppressing the impact load change, the pencil hardness of a certain degree of hardness is achieved. can be ensured.

The present disclosure also includes the multi-layer window with an adhesive layer and the display device, including the multi-layer window.

The display device includes a multilayer window, a display panel laminated on the side opposite to the viewing side of the multilayer window or a laminate including the display panel, and a third adhesive layer interposed between the multilayer window and the display panel or laminate. and including. Such a display device may be obtained, for example, by peeling off the release liner from the multi-layer window with the adhesive layer and bonding the multi-layer window and the display panel or laminate via the third adhesive layer.

In this specification, the thickness of the window base material, the multilayer window, the adhesive layer-attached multilayer window, and the display device, and the thickness of the members or layers constituting these are referred to as the window base material, the multilayer window, and the adhesive layer-attached multilayer window. , or the average thickness of a section cut out from the display device and measured based on an image of the section taken by a scanning electron microscope (SEM). The average thickness is obtained by measuring the thickness at arbitrary multiple points (for example, 5 points) in the cross-sectional image and averaging the thicknesses.

In the display device, from the viewpoint of ensuring high visibility of the display panel, in many cases, the member (or layer) located on the viewing side of the display panel or the material thereof includes a transparent member (or layer) or a transparent material. material is used. A transparent member (or layer) means a member (or layer) having a total light transmittance of 80% or more. The total light transmittance can be measured according to JIS K 7136K:2000. A transparent material means a material having a total light transmittance of 80% or more for members (or layers) constituting a display device formed of this transparent material.

[Multilayer window]
(First base material)
(First resin film)
A 1st base material contains a 1st resin film, for example. The first substrate typically does not contain glass. Examples of the first resin film include a transparent resin film.

The average value M1 of the tensile storage modulus of the first resin film at 25°C and the frequency range of 2 kHz to 20 kHz is, for example, 3 GPa to 10 GPa, and may be 3 GPa to 8 GPa. When M1 is in such a range, the first substrate tends to have high hardness, and the pencil hardness of the surface Sv on the viewing side of the multilayer window tends to be high, which is advantageous in ensuring high scratch resistance. .

The average value M1 of the tensile storage modulus of the first resin film is the frequency range of 2 kHz or more and 20 kHz or less when the frequency dispersion data of the tensile storage modulus at 25 ° C. is obtained using the measurement sample of the first resin film. is the average value in

More specifically, first, using a measurement sample, a tensile test is performed under the following conditions using the following apparatus. Measure the tensile storage modulus of the sample at the following multiple frequencies, and obtain temperature distribution data for each frequency.
Apparatus: Multifunctional dynamic viscoelasticity measuring device DMS6100 manufactured by Hitachi High-Tech Science Co., Ltd.
Temperature range: -150°C to +100°C
Heating rate: 2°C/min
Mode: Tensile Sample width: 10 mm
Distance between chucks: 20mm
Frequency: 1Hz, 2Hz, 5Hz, 10Hz, 20Hz, 28Hz
Strain amplitude: 10 μm
Atmosphere: N ₂ (flow rate: 250 mL/min)
A master curve corresponding to the frequency dispersion data at 25° C. is obtained from the obtained temperature dispersion data according to the "master curve analysis" of the analysis software "Muse" installed in the measuring apparatus. From this master curve, the average value in the frequency range of 2 kHz or more and 20 kHz or less is obtained and taken as the average value M1 of the tensile storage modulus.

A sample for measurement is prepared by preparing a first resin film and cutting it into a shape of 50 mm in length and 10 mm in width. If the first resin film to be analyzed is not available separately, a sample is prepared by removing the first resin film from the multilayer window or display panel. For cutting the first resin film, for example, a multi-purpose test piece cutting machine manufactured by Dumbbell Co., Ltd. is used.

The thickness T1 of the first resin film is, for example, 20 μm or more and 200 μm or less, and may be 30 μm or more and 100 μm or less. When M1 is 3 GPa or more and 10 GPa or less and T1 is 30 μm or more and 100 μm or less, high hardness of the first base material can be easily ensured. It is advantageous in improving scratch resistance.

Windows for display devices are required to have high transparency (high total light transmittance and low haze, etc.) and high hardness. A material that satisfies these physical properties is used for the material of the first resin film. Examples of the resin constituting the transparent resin film include at least one selected from the group consisting of polyimide resins, polyester resins (polyethylene terephthalate resin, etc.), acrylic resins, and cyclic polyolefin resins. However, the resin constituting the transparent resin film is not limited to these. The first resin film may contain a polyimide resin from the viewpoint of easily obtaining higher hardness and easily ensuring hard pencil hardness and high scratch resistance on the viewing side surface Sv of the multilayer window.

(Hard coat layer)
The first base material may contain a hard coat layer. From the viewpoint of facilitating the prevention of breakage of the first base material, the hard coat layer may be provided at least on the surface of the first resin film on the viewing side.

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 multilayer window includes a plurality of hard coat layers, the thickness of each hard coat layer may be set within the above range.

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

As the coating agent, for example, a coating agent for optical films can be used. Examples of coating agents include, but are not limited to, acrylic coating agents, melamine coating agents, urethane coating agents, epoxy coating agents, silicone coating agents, and inorganic coating agents. The coating agent may contain known additives used in hard coat layers.

(First adhesive layer)
The indentation elastic modulus at 25° C. of the first adhesive layer interposed between the first base material and the second base material is, for example, 0.01 MPa or more and 2 MPa or less, and 0.02 MPa or more and 1.5 MPa or less. good too. When the indentation modulus is within such a range, the first adhesive layer can easily absorb the stress due to the impact. In addition, since the first adhesive layer has an appropriate hardness, the stress that could not be absorbed is dispersed and transmitted to the second substrate. From the viewpoint of further enhancing the effect of absorbing or dispersing stress due to impact, the indentation modulus may be 0.01 MPa or more (or 0.05 MPa or more) or 1 MPa or less, or 0.05 MPa or more and 0.5 MPa or less. may

The indentation modulus of the first adhesive layer can be measured by a nanoindenter method using a measurement sample. The measurement is performed by pressing the first adhesive layer of the measurement sample from the side with an indenter under the following conditions and analyzing the load-displacement curve obtained.
Apparatus: Triboindenter (manufactured by Hysitron Inc.)
Sample size: length 10mm x width 10mm
Indenter: Concial (spherical indenter: curvature radius 10 μm)
Measurement method: single indentation measurement Measurement temperature: 25°C
Indentation depth of indenter: 5000 nm
Analysis: Oliver Pharr analysis based on load-displacement curves

As a sample for measurement, a sample obtained by subjecting a side surface of a laminate (10 mm long×10 mm wide) of the first substrate and the first adhesive layer to focused ion beam (FIB) processing is used. If the adhesive constituting the first base material and the first adhesive layer cannot be obtained for the laminate to be analyzed, the multilayer window or display device is cut to the above size, and the side surface is manufactured by FIB processing. You may use the sample which carried out. FIB processing is performed under the following conditions.
FIB processing device: Helios G4 UX manufactured by Thermo Fisher Scientific
Accelerating voltage: FIB 30 kV
Processing temperature: -160°C
After the processing, the sample is returned to room temperature and taken out from the apparatus, and then the indentation modulus is measured by pressing an indenter from the side surface of the FIB-processed first adhesive layer.

The shear storage modulus of the first adhesive layer at 25°C is, for example, within the range described above. The shear storage modulus of the first adhesive layer at 25° C. may be, for example, 0.005 MPa or more and 0.2 MPa or less, or 0.01 MPa or more and 0.1 MPa or less.

In this specification, the shear storage modulus of the adhesive layer can be measured according to JIS K 7244-1:1998. Specifically, first, a molded article having a thickness of about 1.5 mm is produced using an adhesive layer or an adhesive that constitutes the adhesive layer. A disc having a diameter of 7.9 mm is punched out of this molding 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) at 25°C. Determine the shear storage modulus at Note that the storage elastic modulus of the adhesive layer is also determined in the same manner as in the case of the adhesive layer.

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

The first adhesive layer is composed of an adhesive. The type of adhesive is not particularly limited, and examples include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinylpyrrolidone adhesives, and polyacrylamide adhesives. , and cellulosic adhesives. Adhesives include, for example, base polymers, cross-linking agents, additives (e.g., tackifiers, coupling agents, polymerization inhibitors, cross-linking retarders, catalysts, plasticizers, softeners, fillers, colorants, metal powders, UV absorbers, light stabilizers, antioxidants, antidegradants, surfactants, antistatic agents, surface lubricants, leveling agents, corrosion inhibitors, particles of inorganic or organic materials (metal compound particles (metal oxide particles, etc.), resin particles, etc.)). The constituent components of the adhesive are not limited to these.

The thickness of the first adhesive layer may be 5 μm or more (or 10 μm or more) and 50 μm or less, or may be 10 μm or more and 40 μm or less (or 30 μm or less). When the thickness of the first adhesive layer is within such a range, when a fast impact is applied to the first substrate, the first adhesive layer can also absorb or disperse the stress accompanying the impact, and the impact load It is more advantageous in keeping the variation low.

For the first adhesive layer, for example, the adhesive constituting the first adhesive layer is applied so as to cover one main surface of the underlying layer (first resin film or second base material), or in a sheet form. It can be formed by transferring a molded adhesive.

(Second base material)
The second base material corresponding to the window base material of the present disclosure includes a laminated structure of glass and resin film 2A. A member or layer constituting the second substrate is required to have high transparency (high total light transmittance, low haze, etc.), and moderate flexibility and hardness. A member (or layer) that satisfies these physical properties is used for each member (or layer).

The second base material has a laminated structure of the resin film 2A and the glass arranged on the viewing side, or a laminated structure of the resin film 2A and the resin film 2B arranged on the viewing side and the glass interposed therebetween. may contain.

When the second base material includes the resin film 2A arranged on the viewing side and the glass, the resin film 2A and the glass are adhered by the adhesive layer 2A. In this case, the second base material may further include a resin film 2B. The glass and the resin film 2B are adhered by the adhesive layer 2B or the adhesive layer 2B.

(glass)
Examples of the glass contained in the second base include a thin glass substrate.

The thickness of the glass is, for example, 5 μm or more and 60 μm or less, may be 10 μm or more and 50 μm or less, or may be 10 μm or more and 40 μm or less.

The composition of the glass is not particularly limited. Examples of glasses are soda lime glass, borate glass, aluminosilicate glass, and quartz glass. The glass may be alkali-free glass or low-alkali glass. From the viewpoint of easily obtaining high transparency, the total content of alkali metal components (e.g., Na ₂ O, K ₂ O, Li ₂ O) in the glass is, for example, 15% by mass or less, and 10% by mass or less. There may be.

(Adhesive layer 2A)
The indentation elastic modulus of the adhesive layer 2A at 25° C. is, for example, 0.01 MPa or more and 2 MPa or less, and may be 0.02 MPa or more and 1.5 MPa or less. When the indentation elastic modulus is within such a range, even if the stress associated with a fast impact is transmitted to the adhesive layer 2A, the adhesive layer 2A deforms appropriately, and the effect of absorbing or dispersing the stress by the second base material increases. . Therefore, the effect of reducing impact load change is enhanced, and fast impact is less likely to propagate to members arranged on the side opposite to the viewing side. From the viewpoint of further enhancing the effect of absorbing or dispersing stress, the indentation modulus may be 0.01 MPa or more (or 0.05 MPa or more) or 1 MPa or less, or 0.05 MPa or more and 0.5 MPa or less. good.

The indentation modulus of the adhesive layer 2A can be measured according to the indentation modulus of the first adhesive layer. As a sample for measurement, a sample obtained by cutting a laminated body in which an adhesive layer 2A is attached to glass into a size of 10 mm long×10 mm wide and performing FIB processing on the side surface is used. If the adhesive layer 2A to be analyzed is not available, a sample made from a multi-layer window or display device may be used.

The shear storage modulus of the adhesive layer 2A at 25°C is, for example, within the range described above, and may be selected from the range described for the first adhesive layer.

The adhesive layer 2A is composed of an adhesive. The adhesive includes those described for the first adhesive layer. The description of the first adhesive layer can also be referred to for the components of the adhesive.

The thickness of the adhesive layer 2A may be 5 μm or more (or 10 μm or more) and 50 μm or less, or may be 10 μm or more and 40 μm or less (or 30 μm or less). When the thickness of the adhesive layer 2A is within such a range, the effect of absorbing or dispersing the stress due to impact by the adhesive layer 2A increases.

For the adhesive layer 2A, for example, an adhesive constituting the adhesive layer 2A is applied so as to cover one main surface of the underlying layer (glass or resin film 2A), or a sheet-shaped adhesive is applied. It can be formed by transferring.

(Resin film 2A)
The average value M2A of the tensile storage modulus of the resin film 2A at 25° C. and the frequency range of 2 kHz or more and 20 kHz or less is, for example, 0.1 GPa or more and 10 GPa or less, and 0.2 GPa or more (or 0.5 GPa or more) and 6 GPa or less. 0.8 GPa or more and 3 GPa or less (or 2 GPa or less), or 0.9 GPa or more and 1.5 GPa or less. When M2A is within such a range, the resin film 2A is likely to be more effective in absorbing or dispersing stress due to impact.

The average value M2A of the tensile storage modulus of the resin film 2A is obtained in the same procedure as in the case of the first resin film, except that the measurement sample of the resin film 2A is used. A sample for measurement is produced by preparing the resin film 2A and cutting it into a shape of 100 mm in length×10 mm in width. For cutting the resin film 2A, for example, a multi-purpose test piece cutting machine manufactured by Dumbbell Co. is used. If the resin film 2A to be analyzed cannot be obtained separately, a sample is prepared from the resin film 2A taken from the second substrate, multilayer window or display panel.

The thickness T2A of the resin film 2A may be 30 μm or more and 150 μm or less, 40 μm or more and 100 μm or less, or 40 μm or more and 90 μm or less.

When the product of M2A and T2A is within a specific range, it is easy to obtain a hard pencil hardness on the viewing side surface Sv of the multilayer window and excellent stress absorption or stress dispersion due to the second base material.

More specifically, when the resin film 2A arranged on the viewing side, the glass, and the adhesive layer 2A interposed between the resin film 2A and the glass are included, M2A×T2A is 25 GPa·μm or less and 50 GPa·μm or less. μm≦M2A×T2A≦200 GPa·μm, 55 GPa·μm≦M2A×T2A≦200 GPa·μm, or 60 GPa·μm≦M2A×T2A≦200 GPa·μm. When M2A×T2A is within such a range, a higher effect of absorbing or dispersing stress due to rapid impact can be obtained, and the change in impact load can be suppressed. In addition, since the second base material has appropriate hardness, it is easy to ensure a high pencil hardness on the surface Sv on the viewing side of the multilayer window. Within the above range, M2A×T2A may be 250 GPa·μm or less, 150 GPa·μm or less, or 100 GPa·μm or less.

By setting the thickness T2A of the resin film 2A within a specific range, the flexibility (or hardness) suitable for the layer structure of the second base material can be imparted to the resin film 2A. Also, it is easy to adjust M2A×T2A within the above range.

When M2A×T2A is within the above range, the thickness T2A of the resin film 2A may be 40 μm or more and 100 μm or less, 50 μm or more and 100 μm or less, or 50 μm or more and 90 μm or less. When the thickness T2A of the resin film 2A is within such a range, the resin film 2A can more easily absorb or disperse the stress due to the impact. In addition, it is easy to obtain a relatively hard pencil hardness.

In the present disclosure, the resin film 2A includes, for example, a transparent resin film having moderate flexibility (and hardness). At least one resin selected from the group consisting of polyester resins, acrylic resins, and cyclic polyolefin resins can be used as the resin constituting the resin film 2A. However, the resin constituting the transparent resin film is not limited to these. The resin film 2A preferably contains a polyester resin from the viewpoint of easily obtaining appropriate flexibility (and hardness). In particular, the resin film 2A is preferably a polyester film having an indentation modulus at 25° C. of 0.2 GPa or more and 1.5 GPa or less (preferably 0.3 GPa or more and 1.5 GPa or less (or 1 GPa or less)). A polyester film exhibiting such an indentation modulus or a polyester constituting this film may be referred to herein as a soft polyester film or a soft polyester, respectively.

The indentation modulus of the soft polyester film can be measured according to the case of the first adhesive layer. However, as an indenter, a Berkovich (triangular pyramid) is used. As a sample for measurement, an adhesive is applied to the glass, a soft polyester film is adhered, the adhesive is completely cured, the resulting laminate is cut into a size of 10 mm in length × 10 mm in width, and the side surface is FIB. A sample obtained by processing is used. If the flexible polyester film to be analyzed is not available, samples made from multi-layer windows or displays may be used.

The soft polyester may contain, for example, aliphatic or chain-like monomer units (monomer units having no ring structure, etc.). Also, the soft polyester may contain a plasticizer as needed. A flexible polyester film having a thickness of 100 μm may have a tensile elastic modulus according to ISO527-3 of 100 MPa or more, 200 MPa or more or 250 MPa or more, or 400 MPa or more or 500 MPa or more. The soft polyester film that constitutes the resin film 2A may be an unstretched film, an extruded film, or an injection-molded film.

In the present disclosure, the indentation elastic modulus of the resin film 2A included in the second base material at 25° C. may be 0.1 GPa or more and 5 GPa or less (or 4.5 GPa or less), or 0.2 GPa or more and 2 GPa or less. 0.2 GPa or more and 1.5 GPa or less, or 0.3 GPa or more and 1.5 GPa or less (or 1 GPa or less). When the indentation modulus is within such a range, the effect of absorbing or dispersing stress can be further enhanced by the resin film 2A while ensuring pencil hardness to some extent.

The indentation elastic modulus of the resin film 2A can be measured according to the indentation elastic modulus of the first adhesive layer. However, as an indenter, a Berkovich (triangular pyramid) is used. As a sample for measurement, an adhesive is applied to glass, the resin film 2A is adhered, the adhesive is completely cured, and the obtained laminate is cut into a size of 10 mm long x 10 mm wide, and the side surface is FIB processed. A sample obtained by If the resin film 2A to be analyzed cannot be obtained, a sample made from a multilayer window or a display device may be used.

The tensile storage modulus of the resin film 2A at a frequency of 10 Hz and 25° C. may be 0.1 GPa or more and 10 GPa or less, may be 0.2 GPa or more and 5 GPa or less, or may be 0.2 GPa or more and 2 GPa or less (or 1 GPa or less). ). When the tensile storage elastic modulus of the resin film 2A at a frequency of 10 Hz is within such a range, the resin film 2A is appropriately deformed, and the effect of absorbing or dispersing stress is likely to be obtained, and strain due to stress is accumulated. hard. The tensile storage modulus of the resin film 2A at a frequency of 10 Hz and 25° C. is obtained according to the average value M2A of the tensile storage modulus of the resin film 2A. However, the measurement frequency shall be 10 Hz.

(Resin film 2B)
In the second substrate, when the glass is arranged on the side opposite to the viewing side with respect to the resin film 2A, the resin film 2B may be laminated on the glass. In other words, the second substrate may further include a resin film 2B arranged on the opposite side of the glass to the viewing side. An adhesive layer 2B or an adhesive layer 2B is interposed between the glass and the resin film 2B. The resin film 2B can enhance the effect of protecting the glass. In addition, since the resin film 2B can also absorb or disperse stress, it is possible to further reduce the stress transmitted to members arranged on the side opposite to the viewing side of the multilayer window.

The resin film 2B may be, for example, a transparent resin film having moderate flexibility (and hardness). At least one resin selected from the group consisting of polyester resins, acrylic resins, and cyclic polyolefin resins can be used as the resin constituting the resin film 2B. However, the resin constituting the transparent resin film is not limited to these. The resin film 2B is preferably a soft polyester film from the viewpoint of easily obtaining appropriate flexibility (and hardness). Soft polyesters may include, for example, aliphatic or chain-like monomer units (such as monomer units that do not have a ring structure). As the soft polyester and soft polyester film, for example, the soft polyester and soft polyester film described for resin film 2A may be used, respectively.

The thickness T2B of the resin film 2B may be 30 µm or more and 150 µm or less. The thickness T2B of the resin film 2B containing soft polyester may be 40 μm or more and 100 μm or less, or may be 50 μm or more and 100 μm or less (or 90 μm or less). In this case, even if the stress due to the impact is transmitted to the resin film 2B, the stress can be absorbed or dispersed, and the stress transmitted to the members arranged on the opposite side of the multilayer window from the viewing side can be further reduced. can.

(Adhesive layer 2B)
For the adhesive layer 2B, the description of the first adhesive layer or the adhesive layer 2A can be referred to. The indentation modulus at 25° C., the shear storage modulus at 25° C., and the thickness of the adhesive layer 2B may be selected from the range described for the adhesive layer 2A or the range described for the first adhesive layer. The indentation modulus can be measured according to the case of the adhesive layer 2A. As the adhesive constituting the adhesive layer 2B, the adhesive described for the first adhesive layer can be mentioned, and the description of the first adhesive layer can be referred to for the constituent components of the adhesive. For the adhesive layer 2B, for example, an adhesive constituting the adhesive layer 2B is applied so as to cover one main surface of the underlying layer (glass or resin film 2B), or a sheet-shaped adhesive is applied. It can be formed by transferring. At least two of the first adhesive layer, the adhesive layer 2A, and the adhesive layer 2B may be composed of the same adhesive, or may be composed of different adhesives.

(Adhesion layer 2B)
The indentation modulus of the adhesive layer at 25° C. may be 0.1 GPa or more and 10 GPa or less, 1 GPa or more and 10 GPa or less, or 2.5 GPa or more and 7 GPa or less. When the indentation elastic modulus of the adhesive layer 2B is within the above range, the stress transmitted to the glass is easily propagated to the resin film 2B quickly, and the stress is absorbed or dispersed by the resin film 2B, so that the viewing side of the multilayer window The stress transmitted to the member arranged on the opposite side can be further reduced.

The indentation elasticity modulus of the adhesive layer 2B can be measured according to the indentation elasticity modulus of the first adhesive layer. However, as an indenter, a Berkovich (triangular pyramid) is used, and the indentation depth of the indenter is set to 50 nm. As a sample for measurement, a sample (length 10 mm×width 10 mm) in which only the adhesive layer 2B is formed on glass is used. The adhesive layer 2B is formed by applying an adhesive that constitutes the adhesive layer 2B to glass and curing it completely, and then cutting the resulting laminate and performing FIB processing. If the adhesive that constitutes the adhesive layer 2B to be analyzed cannot be obtained, a sample made from a multi-layer window or a display device may be used.

The shear storage modulus of the adhesive layer 2B at 25°C is, for example, within the range described above. The shear storage modulus of the adhesive layer 2B at 25° C. may be 100 MPa or more and 15 GPa or less, or may be 500 MPa or more and 10 GPa or less.

The adhesive layer 2B can be formed, for example, by applying a curable adhesive to the main surface of the underlying layer (one of the glass and the resin film 2B), laminating the other, and curing.

Examples of adhesives used for the adhesive layer 2B include active energy ray-curable adhesives (ultraviolet-curable adhesives, electron beam-curable adhesives, etc.) and heat-curable adhesives. Such adhesives include acrylic adhesives, epoxy adhesives, urethane adhesives, and the like. However, the adhesive is not limited to these only.

The thickness of the adhesive layer 2B is, for example, 0.5 μm or more and 10 μm or less, may be 0.8 μm or more and 5 μm or less, or may be 0.8 μm or more (or 1 μm or more) and 2 μm or less.

(Pencil hardness)
The viewing side surface Sv of the multilayer window preferably has a pencil hardness greater than 7B, and may be 6B or even harder.

In this specification, the pencil hardness means the hardness (scratch hardness by the pencil method) of the surface Sv on the viewing side of the multilayer window according to the pencil hardness test specified in JIS K 5600-5-4:1999. Pencil hardness can be measured under conditions of 750 g load and 25° C. in accordance with JIS K 5600-5-4:1999.

(Impact load change)
The maximum value of the impact load change determined by the pen drop test at 25° C. is 13 N/ms or less, may be 12 N/ms or less, or may be 11 N/ms or less. In this specification, the maximum impact load change means the impact load change (0 0.01 ms interval (positive slope of impact load). The measured impact load usually takes a maximum value at a very early stage (for example, within 0.2 ms), and the impact load change also takes a maximum value. This very early impact load change is an indication of the rate of stress absorption or dissipation upon application of a fast impact. It means that the smaller the maximum value of impact load change, the more quickly the stress due to impact is absorbed or dispersed.

The pen drop test is performed at 25° C. by vertically dropping a ball point pen onto the surface of the sample for measurement. The sample is placed so that the surface opposite to the viewing side is in contact with the surface of the acceleration sensor. The ballpoint pen is dropped onto the surface of the sample on the viewing side. A time-dependent change in the impact load of the sample in the pen drop test is measured using an acceleration sensor placed on a stainless steel plate. A recorder connected to the sensor records the time-dependent change in the impact load at this time. The change (slope) of the impact load is calculated at intervals of 0.01 ms, and the maximum value of the slope (maximum value of the positive slope) is obtained. The measurement conditions for the pen drop test and the acceleration sensor are as follows.
Ballpoint pen: weight 7g, ball diameter 0.7mm (Oil-based ballpoint pen “BK407 Black” manufactured by Pentel Co., Ltd.)
Drop height: 20cm
Acceleration sensor: PCB ICP (registered trademark) (Integrated Circuit Piezoelectric) sensor (model: 480C02)
Recorder: Memory HiCorder manufactured by Hioki Electric Co., Ltd. (Model: MR8870)
Impact load measurement (storage) interval: 0.001 ms
Measurement time: 0.000ms to 1.0ms

A sample for measurement was prepared by applying a laminate B1 corresponding to the first base material to the surface of the window base material (second base material) to be analyzed on the viewing side, and applying a 25 μm thick acrylic adhesive layer (indentation elastic modulus ( 25 ° C.): 0.11 MPa, shear storage modulus (25 ° C.): 0.03 MPa), and the resulting laminate (laminate A1) is cut into a size of 25 mm long × 25 mm wide. be done. If the window base material (second base material) to be analyzed or the materials or members constituting it cannot be obtained, the laminated body corresponding to the window base material (second base material) from the multilayer window or display device Samples may be prepared by exfoliating portions.

The above laminate B1 is formed by forming an acrylic hard coat layer having a thickness of 10 μm on one surface of a 50 μm-thick transparent polyimide film (average tensile storage modulus M1: 6.5 GPa), and It is obtained by forming the acrylic adhesive layer having a thickness of 25 μm. More specifically, in the laminate B1, the first base material produced by the procedure of "(a) Production of the first base material" in Example 1 described later is used as a protective base material, and the first base material is An acrylic adhesive layer having a thickness of 25 μm is formed on the surface opposite to the viewing side (the surface opposite to the hard coat layer), and is formed by cutting into a size of 25 mm long×25 mm wide. For the acrylic adhesive layer, a layer of an acrylic adhesive composition prepared by the procedure of "(b) Preparation of adhesive" in Example 1 below is applied to the surface opposite to the viewing side of the first substrate. Formed by transcription.

It should be noted that cracking of the glass is confirmed using an optical microscope from the surface of the measurement sample on the viewing side after the pen drop test of the measurement sample.

(others)
If necessary, the multilayer window includes the first resin film, the resin films 2A and 2B, the hard coat layer, the glass, the first adhesive layer, the adhesive layers 2A and 2B, and other layers other than the adhesive layer 2B (hereinafter referred to as layer A ) may be included. Layer A includes an antireflection layer, an antiglare layer, an antifouling layer, an antisticking layer, a hue adjusting layer, an antistatic layer, an easy adhesion layer, a layer for preventing deposition of ions or oligomers, an antiscattering layer, a decorative layer, and the like. is mentioned. The multi-layer window may contain one layer of layer A or may contain multiple layers. Layer A may be included in the first substrate, depending on the function of layer A, and may be laminated to the surface of the second substrate opposite to the viewing side. When the first base material includes the layer A, the layer A is arranged, for example, on the viewing side of the first resin film. Layer A may be formed directly on a layer in contact with Layer A by coating or the like, or may be laminated via an adhesive layer or adhesive layer.

The thickness of the multilayer window is, for example, 50 μm or more and 600 μm or less, and may be 100 μm or more and 300 μm or less.

[Multilayer window with adhesive layer]
(Third adhesive layer)
In the multi-layer window with an adhesive layer of the present disclosure, a third adhesive layer is disposed on the surface of the multi-layer window of the present disclosure opposite to the viewing side.

For the third adhesive layer, the description of the first adhesive layer or adhesive layer 2A can be referred to. The indentation modulus at 25° C., the shear storage modulus at 25° C., and the thickness of the third adhesive layer may be selected from the range described for the adhesive layer 2A or the range described for the first adhesive layer.

The indentation modulus of the third adhesive layer can be measured in the same manner as the indentation modulus of the first adhesive layer. As a sample for measurement, a sample obtained by attaching a third adhesive layer to glass, cutting the resulting laminate into a size of 10 mm long×10 mm wide, and subjecting the side surface to FIB processing is used. If the third adhesive layer to be analyzed is not available, samples made from multi-layer windows or display devices may be used.

As the adhesive constituting the third adhesive layer, the adhesive described for the first adhesive layer can be mentioned, and the description of the first adhesive layer can be referred to for the constituent components of the adhesive. For the third adhesive layer, for example, the adhesive constituting the third adhesive layer is applied so as to cover the underlying layer (the surface of the multilayer window opposite to the viewing side or one main surface of the release liner). Alternatively, it can be formed by transferring a sheet-shaped adhesive.

When the third adhesive layer is formed on the surface of the multilayer window opposite to the viewing side, the release liner is applied to the third adhesive such that the surface of the third adhesive layer opposite to the viewing side is covered with the release liner. By attaching the layers, a multi-layer window with an adhesive layer is formed. When the third adhesive layer is formed on one main surface of the release liner, the third adhesive layer held by the release liner is adhered to the surface of the multilayer window opposite to the viewing side to form the multilayer window with the adhesive layer. A window is formed.

The adhesive that constitutes the third adhesive layer may be the same as the adhesive that constitutes at least one of the first adhesive layer, the adhesive layer 2A, and the adhesive layer 2B, and is different from all the adhesives that constitute each layer. may be

(Release liner)
A release liner is laminated via a third adhesive layer to the surface of the multilayer window opposite to the viewing side.

As the release liner, for example, a release sheet comprising a base sheet and a release agent provided on at least one main surface of the base sheet is used. For the base sheet, for example, the same material as the resin film exemplified as the first base film can be arbitrarily selected and used. As the release agent, known release agents (eg, silicone-based release agents, fluorine-based release agents) can be used.

[Display device]
A display device of the present disclosure includes the multilayer window described above, a display panel or a laminate including the display panel, and a third adhesive layer interposed therebetween. For the third adhesive layer, the description of the third adhesive layer of the multi-layer window with the adhesive layer can be referred to. The display device may be formed, for example, by laminating members or layers constituting the display device, and a third adhesive layer is formed on one surface of the multilayer window and the display panel or the laminate including the display panel. , may be formed by pasting the other. Alternatively, the release liner of the multi-layer window with the adhesive layer is peeled off from the third adhesive layer, and the display panel or the laminate including the display panel is attached to the exposed surface of the third adhesive layer to form the multi-layer window. good too.

(display panel)
Examples of the display panel include an image display panel. A known image display panel is used as the image display panel. Image display panels include, for example, organic electroluminescence (EL) panels. However, the display panel is not limited to these.

(Laminate including display panel)
The laminate may be, for example, a laminate (first laminate) of a display panel and a sealing member (such as a thin film sealing layer). The sealing member is normally arranged directly on the main surface of the image display panel on the viewing side.

The laminate may be a laminate (second laminate) of the display panel and the protective member. Protective members include, for example, sheets or films (or substrates) that hold or protect panel members. Examples of the protective member include a protective member that holds the panel member and has an appropriate strength for protecting the panel member. When the display device is a flexible image display device, a protective member having moderate flexibility that does not interfere with flexibility is used. A resin sheet or the like is used as the protective member. The material of the resin sheet is not particularly limited, and can be appropriately selected according to, for example, the type of display panel.

The laminate may be a panel member with a touch sensor. The touch sensor-equipped panel member is, for example, a laminate (third laminate) having a structure in which a touch sensor and a display panel (such as the display panel described above) are integrated. The touch sensor-equipped panel member may include the protective member described above. The panel member with a touch sensor includes, for example, a member having a configuration in which an antistatic capacitive touch sensor of a metal mesh electrode is formed on a thin film sealing layer of an organic light emitting diode (OLED). A touch sensor, which will be described later, may be used as the touch sensor.

Each of the first laminate and the second laminate may further include a touch sensor. Touch sensors include, for example, touch sensors used in the field of display devices. Examples of touch sensors include resistive type, capacitive type, optical type, and ultrasonic type touch sensors. However, touch sensors are not limited to these.

For example, capacitive touch sensors usually have a transparent conductive layer. Such touch sensors include, for example, a laminate of a transparent conductive layer and a transparent substrate. Examples of transparent substrates include transparent resin films containing the resins exemplified for the first resin film.

The touch sensor may include other layers (hereinafter referred to as layer B) other than the transparent conductive layer and the transparent substrate, if necessary. For example, an undercoat layer or an oligomer precipitation prevention layer may be provided as layer B between the transparent conductive layer and the transparent substrate. Also, a layer B may be laminated on the surface of at least one of the transparent conductive layer and the transparent substrate. However, layer B is not limited to only these layers. Layer B may be laminated on the transparent conductive layer or the transparent substrate via an adhesive layer or adhesive layer, if necessary.

Each of the first laminate, second laminate and third laminate may further include an optical film. Each of the first laminate and the second laminate may include a touch sensor and an optical film (specifically, a film having an optical function).

An optical film is usually a laminate containing at least one layer having an optical function. Examples of optical films include those used in the field of display devices and the like. Layers having optical functions include, for example, layers having optical anisotropy (eg, optically anisotropic films). Examples of the layer having optical anisotropy include polarizers, retardation layers, viewing angle widening films, viewing angle limiting (peep prevention) films, brightness enhancement films, and optical compensation films, but are limited to these. not. A laminate of two or more layers may be a laminate having two or more selected from these optically anisotropic layers. 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 with different compositions.

The optical film may include a layer having at least one optical function and a substrate layer (or a protective layer for protection) that holds this layer. For example, a laminate of a layered polarizer and a substrate layer holding the polarizer is called a polarizer. The optical film may contain at least a polarizer or a polarizing plate.

Among the layers having optical anisotropy described above, the optical film comprises a polarizer, at least one layer having optical anisotropy other than the polarizer (hereinafter referred to as layer C), and optionally at least one group. A material layer may be provided. The optical film may have a laminate of a polarizer and a substrate layer as a polarizing plate.

The layer C may be laminated on the polarizing plate via the substrate layer, or may be laminated on the polarizer without the substrate layer.

The polarizer is not particularly limited, and polarizers used in the field of image display devices can be used. Examples of the polarizer include a film obtained by adsorbing a dichroic substance to a hydrophilic polymer film and uniaxially stretching the film, and an oriented polyene film. Hydrophilic polymers constituting the hydrophilic polymer film include, for example, polyvinyl alcohol-based resins (including partially formalized polyvinyl alcohol-based resins) and partially saponified ethylene-vinyl acetate copolymers. Dichroic substances include, for example, iodine and dichroic dyes. Materials constituting the oriented polyene film include, for example, dehydrated polyvinyl alcohol resins and dehydrochlorinated polyvinyl chloride resins.

A thin polarizer having a thickness of 10 μm or less may be used as the polarizer. Thin polarizers are described in, for example, JP-A-51-069644, JP-A-2000-338329, WO 2010/100917, JP 4691205, and JP 4751481. A polarizer is mentioned. A thin polarizer is obtained, for example, by a manufacturing method including a step of stretching a laminated state of a polyvinyl alcohol-based resin layer and a resin substrate layer, and a step of dyeing with a dichroic material.

A thin glass substrate, a transparent resin film, etc. are used as the base material layer. Examples of the resin constituting the transparent resin film include the resins exemplified for the first resin film. However, the resin constituting the base material layer is not limited to these.

FIG. 1 shows a display device including a multi-layer window according to one embodiment. The layer structure of each display device will be described below. However, the display device of the present disclosure is not limited to only this embodiment.

FIG. 1 is a schematic cross-sectional view of a display device including a window substrate or multilayer window according to one embodiment. The display device 100 includes a multilayer window W, a display panel (or a laminate including the display panel) 40, and a third adhesive layer 33 interposed therebetween. The multilayer window W includes a first substrate 1 arranged on the viewing side, a second substrate 2 laminated on the side opposite to the viewing side of the first substrate 1, and a first adhesive interposed therebetween. layer 13; The first base material 1 includes a first resin film 11 and a hard coat layer 12 formed on the surface of the first resin film 11 on the viewing side. The viewer-side surface of the first substrate (more specifically, the surface of the hard coat layer 12 ) corresponds to the multilayer window W and the viewer-side surface Sv of the display device 100 . The second base material 2 includes a glass 22 arranged on the viewing side, a resin film 21 (resin film 2A), and an adhesive layer 24 (adhesive layer 2A) interposed therebetween. The third adhesive layer 33 is formed on the surface of the glass 22 of the multilayer window W opposite to the viewing side. A laminate of the multilayer window W and the third adhesive layer 33, in which a release liner is attached so as to cover the surface of the third adhesive layer 33 opposite to the viewing side, corresponds to the multilayer window with the adhesive layer. . For example, in such a multi-layer window with an adhesive layer, the release liner is separated from the third adhesive layer 33, and the third adhesive layer 33 is adhered to the viewing side surface of the display panel (or laminate including the display panel) 40. The display device 100 can be formed by stacking the multilayer windows W such that

[Example]
EXAMPLES The present invention will be specifically described below based on examples and comparative examples, but the present invention is not limited only to the following examples.

<<Examples 1 and 2 and Comparative Examples 1 and 2>>
(1) Production of Evaluation Sample An evaluation sample of the multilayer window W as shown in FIG. 1 was produced by the following procedure.

(a) Preparation of first base material As the first base material 1, a transparent polyimide film (manufactured by KOLON, product name “C_50”, thickness (T1) 50 μm) as the first resin film 11 is used. was provided with a hard coat layer 12 (thickness: 10 μm).

The hard coat layer 12 was formed using a coating agent for hard coat layers. More specifically, first, a coating agent was applied to one side of a 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, a hard coat layer 12 was formed by irradiating the coating layer with ultraviolet rays using a high-pressure mercury lamp at an integrated light amount of 300 mJ/cm ² . Thus, the first base material 1 was produced.

The coating agent for the hard coat layer includes 100 parts by mass of polyfunctional acrylate (manufactured by Aica Kogyo Co., Ltd., product name "Z-850-16") as a base resin, and a leveling agent (manufactured by DIC, trade name: GRANDIC PC -4100) and 3 parts by mass of a photopolymerization initiator (manufactured by IGM Resins B.V., trade name: Omnirad 907). Prepared by diluting with isobutyl ketone.

The average value M1 of the tensile storage modulus of the first resin film at 25°C and the frequency range of 2 kHz to 20 kHz, which is obtained by the procedure described above, was 7.5 GPa.

(b) Preparation of Adhesive An acrylic pressure-sensitive adhesive composition was prepared in the following procedure.
(Preparation of acrylic oligomer)
60 parts by mass of dicyclopentanyl methacrylate and 40 parts by mass of methyl methacrylate as monomer components, 3.5 parts by mass of α-thioglycerol as a chain transfer agent, and 100 parts by mass of toluene as a polymerization solvent were mixed and placed 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. . After that, the reaction solution was heated to 130° C. to remove the toluene, the chain transfer agent and the unreacted monomer by drying to obtain a solid acrylic oligomer. The acrylic oligomer had a weight average molecular weight of 5100 and a glass transition temperature (Tg) of 130°C.

(Preparation of base polymer composition)
43 parts by weight of lauryl acrylate, 44 parts by weight of 2-ethylhexyl acrylate, 6 parts by weight of 4-hydroxybutyl acrylate, and 7 parts by weight of N-vinyl-2-pyrrolidone, and IGM Resins B.I. V. 0.015 parts by mass of "Omnirad 184" manufactured by Co., Ltd. was mixed and polymerized by irradiating ultraviolet rays to obtain a base polymer composition (polymerization rate: about 10%).

(Preparation of acrylic adhesive)
To 100 parts by mass of the above base polymer 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 (manufactured by Shin-Etsu Chemical Co., Ltd. "KBM403J" ) was added and uniformly mixed to prepare an acrylic pressure-sensitive adhesive.

(c) Fabrication of Second Substrate As the glass 22, a thin glass plate (G-leaf (registered trademark) manufactured by Nippon Electronic Glass Co., Ltd., thickness 30 μm) was prepared. As the resin film 21 (resin film 2A), a film made of the material shown in Table 1 and having a thickness T2A shown in Table 1 was prepared. The resin film 21 formed of the material shown in Table 1 used in each example is as follows. The resin film 21 containing soft polyester is formed only of soft polyester, and the indentation elastic modulus of the soft polyester at 25° C. is the same value as the indentation elastic modulus of the resin film 2A shown in Table 1.
PES1: Film made of transparent soft polyester (OKY200, manufactured by Bell Polyester Products Co., Ltd.) (injection molding, unstretched, tensile modulus of 100 μm thick sheet conforming to ISO527-3: 271 MPa)
PES2: Film made of transparent soft polyester (OKY300, manufactured by Bell Polyester Products Co., Ltd.) (injection molding, unstretched, tensile modulus of 100 μm thick sheet conforming to ISO527-3: 561 MPa)
TPU: Polyurethane elastomer sheet (manufactured by Seedam Co., Ltd., DUS605)
PET: polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, biaxially stretched film, Diafoil (registered trademark) S100)

In Comparative Example 1, only the thin glass plate (G-leaf (registered trademark) manufactured by Nippon Electronic Glass Co., Ltd., thickness 30 μm) was used as the second base material.

In Examples 1 and 2 and Comparative Examples 2 and 3, the second base material was produced by the following procedure. First, the acrylic adhesive composition prepared in (b) above is transferred to one surface of the glass 22 to form the adhesive layer 2A, and the adhesive layer 2A is formed of the glass 22 and the resin film 21 (resin film 2A). The resin film 21 was laminated and adhered so as to be sandwiched between the two. Thus, the second base material 2 was produced. The indentation elastic modulus of the adhesive layer 2A at 25° C. measured by the procedure described above was 0.11 MPa, the shear storage elastic modulus at 25° C. was 0.03 MPa, and the thickness was 25 μm.

(d) Preparation of multilayer window The surface of the first resin film 11 of the first substrate 1 obtained in (a) above (the surface opposite to the viewing side) is coated with the acrylic adhesive prepared in (b) above. A first adhesive layer 13 was formed by transferring the agent layer. A multilayer window W was produced by stacking the second substrate 2 so that the resin film 21 produced in (c) above was in contact with the first substrate 1 so as to sandwich the first adhesive layer 13 . The thickness of the first adhesive layer 13 was 25 μm. The indentation elastic modulus at 25° C. of the first adhesive layer determined by the procedure described above was 0.11 MPa, and the shear storage elastic modulus at 25° C. was 0.03 MPa. In Comparative Example 1, a multi-layer window was produced by stacking thin glass plates in place of the second substrate 2 .

(2) Evaluation Using the obtained multilayer window (corresponding to the laminate A1 described above), the second substrate or the resin film 2A, the following evaluations were performed.

(a) Indentation Elasticity Modulus, Tensile Storage Elasticity Modulus The indentation elastic modulus (GPa) at 25° C. of the resin film 2A, the tensile storage elastic modulus (GPa) at 10 Hz, and the average value of the tensile storage elastic modulus in the procedure described above. M2A (GPa) was determined. Also, the product M2A×T2A (GPa·μm) was calculated from M2A and thickness T2A.

(b) Pencil hardness test The pencil hardness of the viewing side surface Sv of the multilayer window was measured at 25°C according to the procedure described above.

(c) Impact load change In the procedure described above, a pen drop test was performed using a sample cut from the laminate A1 at 25 ° C., the impact load change was measured, and the maximum positive value (N / ms) was obtained. Ta.

(d) Cracking of glass In the pen drop test of (c) above, the state of cracking of the glass after the test was observed with an optical microscope from the viewing side surface Sv and evaluated according to the following criteria. Evaluation was performed on three samples for each case.
A: No glass breakage is observed in all three samples.
B: Glass cracks are not observed in two of the three samples.
C: Glass cracks are observed in two or more of the three samples.

《Reference examples 1 to 4》
Evaluation samples of multilayer windows were prepared according to Examples 1 and 2 and Comparative Examples 2 and 3. The second base material was produced by the following procedure. First, an epoxy-based adhesive composition was applied to one surface of the glass 22, and the resin film 21 was stacked so that the resulting coating film was sandwiched between the glass 22 and the resin film 21 (resin film 2A). In this state, the coating film was cured by irradiating it with ultraviolet rays from the glass 22 side to form an adhesive layer 2A sandwiched between the glass 22 and the resin film 2A21. The thickness of the adhesive layer 2A measured by the procedure described above was 1 μm. Thus, a second base material was produced. Other than these, samples were prepared and evaluated in the same manner as in Examples 1 and 2 and Comparative Examples 2 and 3. The indentation elastic modulus of the adhesive layer 2A at 25° C. measured by the procedure described above was 4.9 GPa.

An epoxy-based adhesive composition was prepared by the following procedure.
Alicyclic alicyclic epoxy resin (Celoxide 2021P, epoxy equivalent 128-133 g/eq., manufactured by Daicel Corporation) 70 parts by mass, trifunctional aliphatic epoxy resin (EHPE3150, epoxy equivalent 170-190 g/eq., Daicel Corporation) ) 5 parts by mass, oxetane resin (Aron oxetane (registered trademark), manufactured by Toagosei Co., Ltd.) 19 parts by mass, silane coupling agent (KBM-403, 3-glycidoxypropyltrimethoxysilane, Shin-Etsu Chemical Co., Ltd. company) and 2 parts by mass of a photoacid generator (CPI101A, triarylsulfonium salt, manufactured by San-Apro Co., Ltd.) were blended to prepare an epoxy adhesive composition.

Table 1 shows the results of Examples, Comparative Examples, and Reference Examples. In Table 1, Examples 1-2 are E1-E2, Comparative Examples 1-3 are C1-C3, and Reference Examples 1-4 are R1-R4.

As shown in Table 1, in Examples, the pencil hardness was relatively high, and the maximum value of impact load change in the pen drop test was kept small. In contrast, Comparative Examples and Reference Examples had a pencil hardness of 7B or softer, or had a larger maximum impact load change. In this way, even if a fast impact is applied to the viewing side surface of the multi-layer window, the stress due to the impact can be quickly absorbed or dispersed, and the impact load change can be suppressed to a low level in the example, despite the inclusion of glass. can. In addition, it is possible to secure a relatively high pencil hardness on the surface of the multilayer window on the viewing side while having excellent stress absorbability or dispersibility. In Comparative Example 1, cracking of the glass was observed in the pen drop test, but cracking of the glass could be suppressed in Examples.

Although the present invention has been described in terms of its presently preferred embodiments, such disclosure should not be construed as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art to which the invention pertains after reading the above disclosure. Therefore, the appended claims are to be interpreted as covering all variations and modifications without departing from the true spirit and scope of the invention.

The window base material of the present disclosure is suitable for use as a base material for window members of display devices. A multilayer window comprising a window substrate is suitable for use as a window member in a display device. However, the uses of window substrates and multilayer windows are not necessarily limited to these.

100: Display device W: Multilayer window 1: First substrate 11: First resin film 12: Hard coat layer 13: First adhesive layer 2: Second substrate (window substrate)
21: Resin film 2A
22: Glass 24: Adhesive layer 2A
33: Third adhesive layer 40: Display panel or laminate containing display panel

Claims

A base material for a window including a structure in which glass and a resin film 2A are laminated,
The maximum value of the impact load change required by the pen drop test at 25 ° C. is 13 N / ms or less,
The product of the average value M2A of the tensile storage modulus of the resin film 2A at 25° C. and the frequency range of 2 kHz or more and 20 kHz or less and the thickness T2A of the resin film 2A: M2A×T2A is 50 GPa μm≦M2A×T2A≦ A base material for windows that satisfies 250 GPa·μm.
including the resin film 2A arranged on the viewing side, the glass, and an adhesive layer 2A interposed between the resin film 2A and the glass,
2. The base material for a window according to claim 1, wherein the product M2A*T2A satisfies 50 GPa.[mu]m<M2A*T2A<200 GPa.[mu]m.
The window base material according to claim 2, wherein the indentation elastic modulus of the adhesive layer 2A at 25°C is 0.01 MPa or more and 1 MPa or less.
Furthermore, the resin film 2B arranged on the side opposite to the viewing side of the glass, and the adhesive layer 2B or the adhesive layer 2B interposed between the glass and the resin film 2B. A window substrate as described.
The window substrate according to claim 4, wherein the thickness T2B of the resin film 2B is 40 µm or more and 100 µm or less.
The window substrate according to claim 4 or 5, wherein the resin film 2B is a polyester film having an indentation elastic modulus at 25°C of 0.2 GPa or more and 1.5 GPa or less.
The window base material according to any one of claims 1 to 6, wherein the thickness T2A of the resin film 2A is 40 µm or more and 100 µm or less.
The window-use according to any one of claims 1 to 7, wherein the resin film 2A has an average tensile storage modulus M2A at 25°C and a frequency range of 2 kHz or more and 20 kHz or less, which is 0.1 GPa or more and 10 GPa or less. Base material.
The window base material according to any one of claims 1 to 8, wherein the resin film 2A is a polyester film having an indentation modulus at 25°C of 0.2 GPa or more and 1.5 GPa or less.
A first base material, a window base material according to any one of claims 1 to 9 as a second base material, and a first adhesive interposed between the first base material and the second base material A multi-layer window comprising at least a layer and
The first substrate comprises a multi-layer window including a viewing side surface Sv of the multi-layer window.
The multilayer window according to claim 10, wherein the indentation elastic modulus at 25°C of the first adhesive layer is 0.01 MPa or more and 1 MPa or less.
The multilayer window according to claim 10 or 11, wherein said surface Sv of said multilayer window has a pencil hardness higher than 7B.
The first base material includes a first resin film,
The average value M1 of the tensile storage elastic modulus of the first resin film at 25° C. and in the frequency range of 2 kHz or more and 20 kHz or less is 3 GPa or more and 10 GPa or less,
The multilayer window according to any one of claims 10 to 12, wherein the thickness T1 of the first resin film is 30 µm or more and 100 µm or less.
The multilayer window according to claim 13, wherein the first resin film includes polyimide resin.
a multilayer window according to any one of claims 10 to 14;
a release liner laminated to the side opposite the viewing side of the multilayer window;
a third adhesive layer interposed between the multilayer window and the release liner.
a multilayer window according to any one of claims 10 to 14;
a display panel or laminate comprising a display panel laminated on the side opposite to the viewing side of the multilayer window;
A display device comprising: a third adhesive layer interposed between the multilayer window and the display panel or the laminate.