JP2022165392A - Laminate for display device and display device - Google Patents

Abstract

To provide a laminate for a display device, capable of improving visibility of an image or a character in a bent part, and improving visibility in a use form of observing an image in a state that the display device is bent.SOLUTION: A laminate for a display device, having a base layer and a functional layer has: a view feeling reflection rate of regular reflection light of 10.0% or less when light is emitted at an incident angle of 60° to a surface at the functional layer side of the laminate for a display device; and a maximum load by which peeling is not generated on the functional layer of 1.0 kg/cm2 or more and 2.0 kg/cm2 or less when surface modification is performed on a surface at the functional layer side of the laminate for a display device followed by performing a steel wool test of scrubbing the surface at the functional layer side of the laminate for a display device 100 times of reciprocation by applying a prescribed load using #0000 steel wool.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present disclosure relates to a laminate for a display device and a display device using the same.

A laminate having functional layers having various properties such as hard coat properties, scratch resistance, antireflection properties, antiglare properties, antistatic properties, and antifouling properties is arranged on the surface of the display device.

Recently, flexible displays such as foldable displays, rollable displays, and bendable displays have attracted attention, and the development of laminates to be arranged on the surfaces of flexible displays is being actively pursued.

A flexible display is required to have no display failure even when it is repeatedly bent, and is required to have flex resistance.

In addition, in the flexible display, for example, a usage pattern in which an image is observed in a folded state is assumed. For example, FIG. 3 is a schematic cross-sectional view illustrating how the foldable display is used. As illustrated in FIG. 3 , in a mode of use in which an image is observed with the foldable display 20 folded, the foldable display 20 has a first display area 22 and a second display area 23 with the bent portion 21 as a boundary. will have In this case, the image or characters displayed in the second display area 23 may be reflected in the first display area 22, or the image or characters displayed in the first display area 22 may be reflected in the second display area 23. , there is a problem that the visibility of images and characters is lowered. This is not limited to foldable displays, and similar problems arise when viewing images in a flexible display in a folded state.

As a means for improving the visibility of a flexible display, for example, Patent Document 1 describes the problem that the visibility is reduced due to the formation of bending marks or whitening in the repeatedly bent portion and the interference fringes caused by the hard coat film. In order to solve the problem that the visibility is reduced due to the The material film is a polyimide film, the absolute value of the difference between the refractive index of the polyimide film and the refractive index of the hard coat layer is 0.04 or less, and the thickness of the polyimide film is 5 μm or more and 50 μm or less. and the thickness of the hard coat layer is 0.5 μm or more and 10 μm or less, and in a bending resistance test by a cylindrical mandrel method in accordance with JIS K5600-5-1, the hard coat layer is separated from the base film. A hard coat film is proposed in which the diameter of the smallest mandrel among the mandrels on which cracks and peeling did not occur in the hard coat layer when the test was performed on the outside is 6 mm or less.

Further, for example, in Patent Document 2, in a display device provided with an antireflection film, in order to solve the problem that the visually recognized color changes depending on the viewing angle, a transparent base film and the transparent base film and an antireflection layer formed on at least one of the antireflection film, wherein the luminosity reflectance for specular reflection at an incident angle of 5 ° of the antireflection film is 0.6% or less, and the incident angle of 5 ° The difference between the maximum and minimum values of the reflectance (%) in the wavelength range of 450 nm to 750 nm for specular reflection is 0.75 or less, and the reflectance (%) in the wavelength range of 400 nm to 700 nm for specular reflection at an incident angle of 45 ° Antireflection films have been proposed in which the difference between the maximum and minimum values of is 1.5 or less.

JP 2018-109773 A JP 2019-70756 A

However, Patent Literatures 1 and 2 do not consider the visibility in a usage pattern in which an image is observed while the display device is folded, and it is possible to improve the visibility in such a usage pattern. The actual situation is that no laminate has been proposed.

In addition, in flexible displays, there is room for improvement in the visibility of images and characters at bent portions.

The present disclosure has been made in view of the above circumstances, and is capable of improving the visibility of images and characters in a bent portion, and the visibility in a usage pattern in which an image is observed while the display device is folded. A main object of the present invention is to provide a laminate for a display device capable of improving the

An embodiment of the present disclosure is a laminate for a display device having a base material layer and a functional layer, wherein light is incident on the surface of the laminate for a display device on the functional layer side at an incident angle of 60°. The luminous reflectance of specularly reflected light is 10.0% or less when the display device laminate is exposed, and after performing surface modification on the surface of the display device laminate on the functional layer side, the display device laminate When a steel wool test is performed by rubbing the functional layer side surface of #0000 steel wool 100 times under a predetermined load, the maximum load at which the functional layer does not peel off is 1.0 kg / Provided is a laminate for a display device having a weight of 2.0 kg/cm ² or more and 2.0 kg/cm ² or less.

In the display device laminate according to the present disclosure, the functional layer is preferably an inorganic film.

In the above case, the inorganic film preferably contains silicon dioxide.

In addition, in the laminate for a display device according to the present disclosure, the functional layer preferably has a thickness of 50 nm or more and 140 nm or less.

Further, in the laminate for a display device according to the present disclosure, the functional layer preferably has a refractive index of 1.40 or more and 1.50 or less.

The laminate for a display device in the present disclosure may have a second functional layer between the base layer and the functional layer, in which case the second functional layer contains a resin and inorganic particles. preferably.

In the above case, the thickness of the second functional layer is preferably 50 nm or more and 10 μm or less.

In the above case, the second functional layer preferably has a refractive index of 1.55 or more and 2.00 or less.

Further, the laminate for a display device in the present disclosure may have a hard coat layer between the base material layer and the functional layer.

Further, the laminate for a display device according to the present disclosure may have a shock absorbing layer on the side of the substrate layer opposite to the functional layer.

Further, the laminate for a display device according to the present disclosure may have an adhesive layer for attachment on the side of the substrate layer opposite to the functional layer.

Another embodiment of the present disclosure provides a display device comprising a display panel and the above-described display device laminate disposed on the viewer side of the display panel.

In the present disclosure, it is possible to improve the visibility of images and characters in the bent portion, and the display device can improve the visibility in a usage pattern in which an image is observed while the display device is folded. It is effective in being able to provide a laminate.

1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a foldable display in the present disclosure; FIG. It is a schematic diagram explaining a dynamic bending test. 1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a laminate for a display device according to the present disclosure; FIG. 1 is a schematic cross-sectional view illustrating a display device according to the present disclosure; FIG.

Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be embodied in many different modes and should not be construed as limited to the description of the embodiments exemplified below. In addition, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part compared to the actual form, but this is only an example and limits the interpretation of the present disclosure. not something to do. In addition, in this specification and each figure, the same reference numerals may be given to the same elements as those described above with respect to the existing figures, and detailed description thereof may be omitted as appropriate.

In this specification, when expressing a mode of arranging another member on top of a certain member, when simply describing “above” or “below”, unless otherwise specified, 2 includes both cases in which another member is arranged directly above or directly below, and cases in which another member is arranged above or below a certain member via another member. In addition, in this specification, when expressing a mode in which another member is arranged on the surface of a certain member, when simply describing “on the surface side” or “on the surface”, unless otherwise specified, It includes both the case of arranging another member directly above or directly below so as to be in contact with it, and the case of arranging another member above or below a certain member via another member.

Hereinafter, the laminate for a display device and the display device according to the present disclosure will be described in detail.

A. Laminate for Display Device A laminate for a display device in the present disclosure is a laminate for a display device having a base material layer and a functional layer, and light is incident on the surface of the laminate for a display device on the functional layer side. The luminous reflectance of specularly reflected light when light is incident at an angle of 60° is 10.0% or less, and after surface modification is performed on the surface of the laminate for a display device on the functional layer side. , When a steel wool test is performed by rubbing the functional layer side surface of the laminate for a display device 100 times with #0000 steel wool under a predetermined load, the functional layer does not peel off. The load is 1.0 kg/cm ² or more and 2.0 kg/cm ² or less.

FIG. 1 is a schematic cross-sectional view showing an example of a laminate for a display device according to the present disclosure. As shown in FIG. 1 , the display device laminate 1 has a base material layer 2 and a functional layer 3 . Further, as illustrated in FIG. 2A, the luminous reflectance of specularly reflected light L1 when light is incident on the surface S1 on the functional layer side of the display device laminate 1 at an incident angle of 60° is predetermined. is less than or equal to Further, although not shown, surface modification is performed on the surface S1 on the functional layer 3 side of the display device laminate 1, and then the surface S1 on the functional layer 3 side of the display device laminate 1 is coated with #0000 steel wool. The maximum load that does not cause peeling of the functional layer 3 is within a predetermined range when a steel wool test is performed by applying a predetermined load and rubbing 100 reciprocations.

In the present disclosure, as an index for evaluating the hardness and adhesion of the functional layer, peeling occurs in the functional layer when a steel wool test is performed after surface modification on the surface of the laminate for a display device on the functional layer side. No maximum load is used. When the hardness of the functional layer is low or the adhesiveness of the functional layer is low, the maximum load tends to decrease. On the other hand, when the hardness of the functional layer is high or the adhesiveness of the functional layer is high, the maximum load tends to increase. If the adhesion of the functional layer is insufficient, there is a possibility that the bent portion may float when the laminate for a display device is repeatedly bent. On the other hand, if the hardness of the functional layer is too high or the adhesiveness of the functional layer is excessive, cracks or breakage may occur at the bent portion when the laminate for a display device is repeatedly bent.

In the present disclosure, the maximum load at which the functional layer does not peel off when a steel wool test is performed on the surface of the laminate for a display device on the functional layer side after surface modification is a predetermined value or more, When the laminated body for display devices is repeatedly bent, it is possible to suppress the occurrence of floating at the bent portion. In addition, when the surface of the laminate for a display device on the functional layer side is subjected to a steel wool test after surface modification, the maximum load at which the functional layer does not peel off is less than or equal to a predetermined value. It is possible to suppress the occurrence of cracks and breaks. Therefore, when the laminate for a display device is used for a flexible display, the visibility of images and characters at the bent portion can be improved.

Here, for example, in a foldable display, a usage pattern in which an image is observed in a folded state is assumed. In such a usage pattern, the foldable display 20 has a first display area 22 and a second display area 23 with the bent portion 21 as a boundary, as shown in FIG. 3, for example. In such a case, the image or characters displayed in the second display area 23 may be reflected in the first display area 22, or the image or characters displayed in the first display area 22 may be reflected in the second display area 23. As a result, there is a problem that the visibility of images and characters is lowered. This is not limited to foldable displays, and similar problems arise when viewing images in a flexible display in a folded state.

On the other hand, in the present disclosure, the luminous reflectance of the specularly reflected light L1 when the light is incident on the surface S1 on the functional layer side of the display device laminate 1 at an incident angle of 60° is a predetermined value or less. Due to this, when the laminate for a display device is used for a flexible display, when an image is observed with the flexible display folded, the image or characters displayed in one display area are displayed in the other display area. It is possible to suppress reflection.

For example, in a foldable display, when an image is observed in a folded state, the angle θ2 formed by the first display area 22 and the second display area 23 as illustrated in FIG. From the viewpoint of , there is a tendency to set the angle larger than 90° and smaller than 180°, and specifically, it can be set to about 120°. When the display device laminate is arranged on the surface of the foldable display 20 on the viewer 25 side, the display device laminate 1 has the bent portion 11 as shown in FIG. 2B, for example. It has the first region 12 and the second region 13 as boundaries, and the angle θ1 formed by the first region 12 and the second region 13 is the same as the angle θ2 described above.

For example, in FIG. 2B, if the luminous reflectance of specularly reflected light L1 when light is incident on the surface S1 on the functional layer side of the display device laminate 1 at an incident angle of 60° is a predetermined value or less, For example, in the foldable display 20 as illustrated in FIG. can be suppressed from being reflected in the first display area 22 corresponding to . Therefore, in the case where the laminate for a display device of the present disclosure is used for a flexible display, when an image is observed with the flexible display folded, the image and characters displayed in one display area are different from those displayed in the other display area. It is possible to suppress reflection in the area. Therefore, it is possible to improve visibility in a usage pattern in which an image is observed while the display device is folded.

In the present disclosure, when an image is observed with the foldable display 20 folded, for example, as shown in FIG. 3, the angle θ2 , from the viewpoint of visibility of displayed images and characters, tends to be set to be larger than 90 ° and smaller than 180 °, specifically, it can be set to about 120 °; When observing an image with the bull display 20 folded, the observer 25 tends to observe the images displayed in the first display area 22 and the second display area 23 by moving only the line of sight without moving the observation position. and that even on the same surface, the higher the incident angle, the higher the reflectance. The luminous reflectance of specularly reflected light at an incident angle of 60° is the visual sensation when light from one display area is reflected by the other display area when an image is observed with the flexible display folded. shall represent the reflectance.

Note that in FIG. 3 , reference L21 denotes light emitted from the second display area 23 and reflected by the first display area 22 .

Therefore, when the laminate for a display device according to the present disclosure is used for a display device, especially a flexible display, it is possible to improve the visibility of images and characters at the bent portion, and the display device is folded. It is possible to improve visibility in a usage pattern in which an image is observed.

Each configuration of the laminate for a display device according to the present disclosure will be described below.

1. Characteristics of Laminate for Display Device In the present disclosure, the luminous reflectance of specularly reflected light when light is incident on the functional layer side surface of the laminate for display device at an incident angle of 60° is 10.0% or less. and is preferably 9.5% or less, more preferably 9.0% or less. When the luminous reflectance of specularly reflected light at the incident angle of 60° is within the above range, when the laminate for a display device of the present disclosure is used for a flexible display, an image can be obtained when the flexible display is folded. , it is possible to prevent images and characters displayed in one display area from being reflected in the other display area. The lower the luminous reflectance of specularly reflected light at the incident angle of 60° is, the better. The luminous reflectance of specularly reflected light at the incident angle of 60° is preferably 0.1% or more and 10.0% or less, more preferably 0.5% or more and 9.5% or less. It is preferably 1.0% or more and 9.0% or less, more preferably.

Further, the luminous reflectance of specularly reflected light when light is incident on the functional layer side surface of the laminate for a display device at an incident angle of 5° is, for example, 0.1% or more and 4.0% or less. more preferably 0.5% or more and 3.5% or less, and even more preferably 1.0% or more and 3.0% or less. When the luminous reflectance of specularly reflected light at the incident angle of 5° is within the above range, the laminate for a display device of the present disclosure is not folded, that is, the angle θ2 is 180° in FIG. When viewing an image in a state, it reduces the color difference between one display area and the other display area while suppressing the viewer's own reflection in the display area. can be suppressed.

Here, the luminous reflectance can be determined according to JIS Z8722:2009. The luminous reflectance is obtained from the reflection spectrum obtained by making light in the wavelength range of 380 nm or more and 780 nm or less incident on the functional side surface of the laminate for a display device. Tristimulus values X, Y, and Z in the color system are obtained, and the value of Y is the luminous reflectance. That is, the luminous reflectance refers to the Y value of the CIE1931 standard color system. In the measurement of luminous reflectance, the following conditions can be used.

(Measurement condition)
・Field of view: 2°
・Illuminant: C
・Light source: tungsten halogen lamp ・Measurement wavelength: 0.5 nm interval in the range of 380 nm to 780 nm ・Scan speed: high speed ・Slit width: 5.0 nm
・S/R switching: Standard ・Auto zero: Performed at 550 nm after baseline scanning

In addition, when measuring the luminous reflectance of the laminate for a display device, a black vinyl tape having a width larger than the measurement spot area (for example, product name "Yamato vinyl tape NO200-19-21 , Yamato Co., Ltd., 19 mm width) is attached to the surface of the laminate for display device on the side of the substrate layer, and then the measurement is performed. As a device for measuring luminous reflectance, for example, a spectrophotometer can be used. Specifically, a spectrophotometer “UV-2600” manufactured by Shimadzu Corporation can be used. The incident angle is the angle of light incident on the functional layer side surface of the display device laminate with respect to the normal to the functional layer side surface of the display device laminate.

In order to reduce the luminous reflectance of specularly reflected light when light is incident on the functional layer side surface of the laminate for display device at an incident angle of 60°, for example, (1-1) refraction of the functional layer (1-2) The functional layer is a multilayer film in which films with different refractive indexes are laminated, (1-3) The refractive index of the functional layer and the surface of the functional layer on the base layer side Means such as adjusting the refractive index of the contacting layer can be mentioned.

(1-1) When the refractive index of the functional layer is relatively low, the difference between the refractive index of the functional layer and the refractive index of air is reduced by making the refractive index of the functional layer relatively low. can suppress the reflection of light on the functional layer side surface of the laminate for a display device, and can reduce the luminous reflectance of specularly reflected light at the incident angle of 60°. As a method for making the refractive index of the functional layer relatively low, for example, the functional layer contains a low refractive index inorganic material having a low refractive index, or the functional layer contains a resin and low refractive index particles having a lower refractive index than the resin. and the like.

In addition, when the above (1-2) functional layer is a multilayer film in which films with different refractive indexes are laminated, the functional layer is a multilayer film in which films with different refractive indexes are laminated. The interference of light can be used to suppress the reflection of light, and the luminous reflectance of specularly reflected light at the incident angle of 60° can be reduced.

In addition, when adjusting the refractive index of the functional layer and the refractive index of the layer in contact with the surface of the functional layer on the substrate layer side in (1-3) above, the refractive index of the functional layer and the substrate layer side of the functional layer By adjusting the refractive index of the layer in contact with the surface of , it is possible to suppress the reflection of light by utilizing the light interference of the thin film, and the luminous reflectance of specularly reflected light at the incident angle of 60 ° can be reduced. In this case, examples of the layer in contact with the base layer side surface of the functional layer include the base layer. Further, for example, when the second functional layer is arranged between the base material layer and the functional layer, the second functional layer can be the layer in contact with the base layer side surface of the functional layer. Further, for example, when the hard coat layer is arranged between the base material layer and the functional layer, the hard coat layer can be the layer in contact with the base layer side surface of the functional layer.

Further, in the present disclosure, after performing surface modification on the functional layer side surface of the laminate for a display device, a predetermined load is applied to the functional layer side surface of the laminate for a display device using #0000 steel wool. 1.0 kg/cm ² or more, preferably 1.1 kg/cm ² or more. More preferably, it is 3 kg/cm ² or more. When the maximum load is within the above range, it is possible to prevent the bent portion from floating when the laminate for a display device is repeatedly bent. The maximum load is 2.0 kg/cm ² or less, preferably 1.9 kg/cm ² or less, and more preferably 1.7 kg/cm ² or less.
When the maximum load is within the above range, it is possible to suppress the occurrence of cracks or breakage in the bent portion when the laminated body for a display device is repeatedly bent. The maximum load is 1.0 kg/cm ² or more and 2.0 kg/cm ² or less, preferably 1.1 kg/cm ² or more and 1.9 kg/cm ² or less, and 1.3 kg/cm ² or more. It is more preferably 0.7 kg/cm ² or less.

In the present disclosure, when performing the steel wool test on the functional layer side surface of the laminate for display device, the surface of the laminate for display device on the functional layer side is subjected to surface modification before the steel wool test. This is for the purpose of aligning the surface condition of the functional layer side surface of the display device laminate regardless of the structure of the display device laminate. By performing surface modification, it is possible to adjust the surface state to an increased surface tension, and it is possible to appropriately evaluate the adhesion of functional layers having different surface states. In addition, depending on the method of surface modification, the effect of surface modification may diminish over time, so a steel wool test should be performed immediately after surface modification of the laminate for a display device. preferable.

Here, as a method of surface modification, for example, corona discharge treatment can be mentioned. Specific conditions for the corona discharge treatment are shown below.
・Output voltage: 14kV
・Distance from the functional layer side surface of the display device laminate to the electrode of the corona discharge treatment device: 2 mm
・Movement speed of stage of corona discharge treatment device: 30 mm/sec
As the corona discharge treatment device, for example, a corona discharge surface modification device “Corona Scanner ASA-4” manufactured by Shinko Electric Instruments Co., Ltd. can be used.

The method of surface modification may be, for example, a surface treatment such that the contact angle with water of the functional layer side surface of the laminate for a display device is 30° or more and 80° or less. Examples of such surface treatment include corona discharge treatment and plasma treatment.

The contact angle of water on the functional layer side surface of the display device laminate can be determined by the θ/2 method. Specifically, at 20° C. and 50% RH, 2 μL of pure water is dropped on the functional layer side surface of the laminate for a display device, and the static contact angle is obtained 5 seconds after the drop is applied. As the contact angle meter, for example, a fully automatic contact angle meter "DropMaster 700" manufactured by Kyowa Interface Science Co., Ltd. can be used.

Moreover, a steel wool test can be performed by the following method. That is, using #0000 steel wool, the steel wool was fixed to a jig of 1 cm × 1 cm, and under the conditions of a load of 100 g/cm ² or more, a moving speed of 100 mm/sec, and a moving distance of 50 mm, the laminate for a display device was obtained. The surface on the functional layer side is rubbed back and forth 100 times. At this time, the load is increased from 100 g/cm ^{2 by 100 g/cm 2 to} obtain the maximum load at which the functional layer does not peel off. As the #0000 steel wool, Bonstar #0000 manufactured by Nippon Steel Wool Co., Ltd. can be used. Further, as a tester, for example, Gakushin type friction fastness tester AB-301 manufactured by Tester Sangyo Co., Ltd. can be used. In the steel wool test, for example, a laminate for a display device having a size of 5 cm×10 cm is fixed on a glass plate with cellophane tape so as not to be bent or wrinkled.

In order to keep the maximum load at which the functional layer does not peel off when a predetermined steel wool test is performed after surface modification is performed on the surface of the laminate for a display device on the functional layer side, For example, means such as adjusting the hardness and adhesion of the functional layer can be mentioned. Methods of adjusting the hardness and adhesion of the functional layer include, for example, a method of disposing the second functional layer between the base material layer and the functional layer, a method of adjusting the thickness of the functional layer, and the like. Further, as a method of adjusting the hardness and adhesion of the functional layer, a method of disposing a second functional layer between the base layer and the functional layer, a method of adjusting the thickness of the functional layer, a method of adjusting the thickness of the functional layer, and a base layer of the functional layer. A method of surface-treating the layer in contact with the side surface, a method of adjusting the material of the functional layer, and the like may be combined.

In the case of the method of disposing the second functional layer between the substrate layer and the functional layer, for example, when the substrate layer is a resin substrate and the functional layer is an inorganic film, the functional layer (inorganic Although the hardness of the base material layer (inorganic film) is high, the adhesion of the functional layer (inorganic film) to the base material layer (resin base material) tends to be low, and the maximum load tends to be small. By arranging the second functional layer between the can be within a predetermined range. Further, for example, when the substrate layer is a glass substrate and the functional layer is an inorganic film, although the functional layer (inorganic film) has a high hardness, the functional layer (inorganic film) with respect to the substrate layer (glass substrate) The adhesion of the film) tends to be too high, and the maximum load tends to be too large. and inorganic particles, the adhesion of the functional layer can be moderately lowered compared to the above, and the maximum load can be moderately decreased to be within a predetermined range.

In addition, in the case of the above method of adjusting the thickness of the functional layer, if the thickness of the functional layer is thin, the hardness of the functional layer becomes low and the adhesion of the functional layer becomes low. When the thickness is large, the hardness of the functional layer tends to increase, and the adhesiveness of the functional layer tends to increase.

Further, when combining the method of surface-treating the layer in contact with the base layer side surface of the functional layer and the method of adjusting the material of the functional layer, for example, by adjusting the material of the functional layer, the By increasing the hardness and then surface-treating the layer in contact with the surface of the functional layer on the substrate layer side, the adhesion of the functional layer can be increased, and the maximum load can be increased within a predetermined range. can be In this case, examples of the layer in contact with the base layer side surface of the functional layer include the base layer. Further, for example, when the second functional layer is arranged between the base material layer and the functional layer, the second functional layer can be the layer in contact with the base layer side surface of the functional layer. Further, for example, when the hard coat layer is arranged between the base material layer and the functional layer, the hard coat layer can be the layer in contact with the base layer side surface of the functional layer.

The total light transmittance of the laminate for a display device in the present disclosure is, for example, preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more. Due to such a high total light transmittance, a laminate for a display device with good transparency can be obtained.

Here, the total light transmittance of the laminate for a display device can be measured according to JIS K7361-1:1999, for example, by a haze meter HM150 manufactured by Murakami Color Research Laboratory.

The haze of the laminate for a display device in the present disclosure is, for example, preferably 5% or less, more preferably 2% or less, and even more preferably 1% or less. Such a low haze makes it possible to obtain a laminate for a display device with good transparency.

Here, the haze of the laminate for a display device can be measured according to JIS K-7136:2000, for example, by a haze meter HM150 manufactured by Murakami Color Research Laboratory.

The laminate for a display device in the present disclosure preferably has bending resistance. Specifically, when the display device laminate is subjected to a dynamic bending test described below, it is preferable that the display device laminate does not crack or break.

A dynamic bending test is performed as follows. First, a display device laminate having a size of 50 mm×200 mm is prepared. In the dynamic bending test, as shown in FIG. 4A, the short side portion 1C of the display device laminate 1 and the short side portion 1D facing the short side portion 1C are arranged in parallel. are fixed by the fixing portion 51. As shown in FIG. Further, as shown in FIG. 4(a), the fixed portion 51 is horizontally slidable. Next, as shown in FIG. 4(b), the fixed portions 51 are moved closer to each other, thereby deforming the laminate for display device 1 so as to be folded, and furthermore, as shown in FIG. 4(c), Then, after moving the fixing portion 51 to a position where the distance d between the two opposing short side portions 1C and 1D fixed by the fixing portion 51 of the display device laminate 1 becomes a predetermined value, the fixing portion 51 is removed. Deformation of the display device laminate 1 is eliminated by moving in the opposite direction. By moving the fixing portion 51 as shown in FIGS. 4A to 4C, the display device laminate 1 can be folded 180°. In addition, a dynamic bending test was performed so that the bent portion 1E of the laminated body 1 for a display device did not protrude from the lower end of the fixed portion 51, and by controlling the distance when the fixed portion 51 was closest, the display device The distance d between the two opposing short sides 1C and 1D of the laminate 1 can be set to a predetermined value. For example, when the interval d between the short sides 1C and 1D is 30 mm, the outer diameter of the bent portion 1E is considered to be 30 mm. For the dynamic bending test, for example, an endurance tester (product name “DLDMLH-FS”, manufactured by Yuasa System Co., Ltd.) can be used.

In the display device laminate, a dynamic bending test in which the display device laminate 1 is folded 180° so that the distance d between the opposing short side portions 1C and 1D is 30 mm is repeated 200,000 times, and cracking occurs. Alternatively, it is preferable that no breakage occurs, and more preferably, no cracking or breakage occurs when repeated 500,000 times. In particular, when a dynamic bending test was repeated 200,000 times in which the display device laminate 1 was folded 180° so that the distance d between the opposing short sides 1C and 1D was 20 mm, no cracking or breakage occurred. Preferably, in particular, no cracking or breakage occurs when a dynamic bending test is repeated 200,000 times in which the display device laminate 1 is folded 180° so that the distance d between the opposing short sides 1C and 1D is 10 mm. is preferred.

In the dynamic bending test, the display laminate may be folded so that the functional layer is on the outside, or the display laminate may be folded so that the functional layer is on the inside. However, it is preferable that the laminate for a display device is not cracked or broken.

2. Functional Layer The functional layer in the present disclosure is a layer arranged on one surface of the substrate layer.

In the present disclosure, the functional layer can function as a low-reflection film. The functional layer may be a single layer or multiple layers. Hereinafter, description will be made separately for the case where the functional layer is a single layer and the case where the functional layer is a multi-layer.

(1) When the functional layer is a single layer When the functional layer is a single layer, the refractive index of the functional layer is preferably 1.40 or more and 1.50 or less, for example. Here, as will be described later, for example, a resin base material or a glass base material can be used as the base material layer, and the refractive index of general resin is about 1.5, and the refractive index of general glass is It is about 1.5. When the refractive index of the functional layer is within the above range, the difference from the refractive index of air can be reduced, and the reflection of light on the surface of the display device laminate on the functional layer side can be suppressed. . Further, if the refractive index of the functional layer is within the above range, the difference between the refractive index of the functional layer and the refractive index of the substrate layer can be increased, and specularly reflected light from the interface between the functional layer and the substrate layer Reflection of light on the functional layer side surface can be suppressed by thin-film interference between the film and specularly reflected light on the functional layer side surface. Therefore, the luminous reflectance of specularly reflected light at the incident angle of 60° can be reduced.

When the functional layer is a single layer, the refractive index of the functional layer is, for example, preferably 1.40 or higher, more preferably 1.43 or higher, and even more preferably 1.45 or higher. When the refractive index of the functional layer is within the above range, the difference between the refractive index of the functional layer and the refractive index of the substrate layer, or the refractive index of the functional layer and the refractive index of the layer in contact with the surface of the functional layer on the substrate layer side. It is possible to increase the difference between the refractive index and the reflection of light by utilizing the interference of light by the thin film. Further, when the functional layer is a single layer, the refractive index of the functional layer is, for example, preferably 1.50 or less, more preferably 1.49 or less, and further preferably 1.48 or less. preferable. When the refractive index of the functional layer is within the above range, the difference from the refractive index of air can be reduced, and the reflection of light on the surface of the display device laminate on the functional layer side can be suppressed. When the functional layer is a single layer, the refractive index of the functional layer is, for example, preferably 1.40 or more and 1.50 or less, more preferably 1.43 or more and 1.49 or less, and 1.45. It is more preferable to be 1.48 or less.

Here, the refractive index of each layer refers to the refractive index for light with a wavelength of 550 nm. A method of measuring the refractive index can include a method of measuring using an ellipsometer. Examples of the ellipsometer include "UVSEL" manufactured by Jobin-Evon and "DF1030R" manufactured by Techno Synergy.

Moreover, the thickness of the functional layer is appropriately adjusted according to the refractive index of the functional layer. When the functional layer is a single layer, the thickness of the functional layer is, for example, preferably 50 nm or more, more preferably 60 nm or more, and even more preferably 70 nm or more. If the thickness of the functional layer is too thin, the hardness and adhesion of the functional layer will be low, and the maximum load at which the functional layer will not peel off when the steel wool test is performed after the surface modification described above will be too small. When repeatedly bent, there is a possibility that the bent portion may float. Moreover, when the functional layer is a single layer, the thickness of the functional layer is, for example, preferably 140 nm or less, more preferably 130 nm or less, and even more preferably 120 nm or less. If the thickness of the functional layer is too thick, the adhesion of the functional layer becomes excessive, and the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above becomes too large. When bent, there is a risk that cracks or breakage may occur at the bent portion. When the functional layer is a single layer, the thickness of the functional layer is, for example, preferably 50 nm or more and 140 nm or less, more preferably 60 nm or more and 130 nm or less, and even more preferably 70 nm or more and 120 nm or less.

Here, the thickness of the functional layer is measured from a cross section in the thickness direction of the display device laminate observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), or a scanning transmission electron microscope (STEM). It is a measured value and can be taken as the mean value of 10 randomly selected thicknesses. The thickness of other layers included in the display device laminate can be measured in the same manner.

The material of the functional layer is a material that satisfies the maximum load that does not cause peeling of the functional layer when a steel wool test is performed after the surface modification described above, and that can obtain a functional layer that satisfies the above refractive index. It is not particularly limited as long as it is. The functional layer may be, for example, an inorganic film or an organic-inorganic mixed film. When the functional layer is an inorganic film, the functional layer can contain, for example, a low refractive index inorganic material having the above refractive index. Moreover, when the functional layer is an organic-inorganic mixed film, the functional layer can contain, for example, a resin and low refractive index particles having a lower refractive index than the resin.

Among them, the functional layer is preferably an inorganic film. Inorganic films tend to have higher hardness than organic-inorganic mixed films and organic films, and the functional layer satisfies the maximum load that does not cause peeling when the steel wool test is performed after the surface modification described above. is easy to obtain.

When the functional layer contains a low-refractive-index inorganic material, the low-refractive-index inorganic material is a functional layer composed of the low-refractive-index inorganic material, which is subjected to the steel wool test after the surface modification described above. It is not particularly limited as long as it satisfies the maximum load that does not cause peeling and is an inorganic material that can satisfy the above-mentioned refractive index, for example, silicon dioxide (silica), magnesium fluoride, lithium fluoride , calcium fluoride, barium fluoride, and the like. Among them, silicon dioxide (silica) is preferred.

Further, when the functional layer contains a resin and low refractive index particles, the low refractive index particles have a lower refractive index than the resin, and it is possible to obtain a functional layer that satisfies the above refractive index. It is not particularly limited as long as it is a material.

The low refractive index particles may be either inorganic particles or organic particles. Examples of inorganic particles include inorganic particles such as silicon dioxide (silica), magnesium fluoride, lithium fluoride, calcium fluoride, and barium fluoride. Among them, silica particles are preferred.

The low refractive index particles may be, for example, solid particles, hollow particles, or porous particles. Among them, hollow particles and porous particles are preferable because of their low refractive index. Examples of hollow particles and porous particles include porous silica particles, hollow silica particles, porous polymer particles, hollow polymer particles and the like.

Also, the low refractive index particles may be surface-treated. By surface-treating the low-refractive-index particles, the affinity with resins and solvents is improved, the low-refractive-index particles are uniformly dispersed, and aggregation of the low-refractive-index particles is less likely to occur. It is possible to suppress the deterioration of the properties, the coatability of the resin composition for the functional layer, and the deterioration of the film strength.

Examples of the surface treatment method include surface treatment using a silane coupling agent. A specific silane coupling agent may be the same as the silane coupling agent disclosed in JP-A-2013-142817, for example.

Also, the low refractive index particles may be reactive particles having a polymerizable functional group on their surface.
Examples of the low refractive index particles that are reactive particles include those used in the low refractive index layer described in JP-A-2013-142817.

The average particle size of the low refractive index particles may be equal to or less than the thickness of the functional layer, for example, 200 nm or less, or may be 100 nm or less. The average particle size of the low refractive index particles is, for example, 5 nm or more, may be 10 nm or more, may be 30 nm or more, or may be 50 nm or more. If the average particle size of the low refractive index particles is within the above range, the low refractive index particles can be dispersed well without impairing the transparency of the functional layer. As long as the average particle size of the low refractive index particles is within the above range, the average particle size may be either the primary particle size or the secondary particle size. good too.

Here, the average particle size of the low refractive index particles refers to the average value of 20 particles observed in a transmission electron microscope (TEM) photograph of the cross section of the functional layer.

The shape of the low refractive index particles is not particularly limited, and may be, for example, spherical, chain-like, needle-like, and the like.

In addition, when the functional layer contains a resin and low refractive index particles, the resin can satisfy the maximum load that does not cause peeling of the functional layer when a steel wool test is performed after the surface modification described above. The resin is not particularly limited as long as it can form a functional layer, but it is preferably a cured resin cured by heat or irradiation with ionizing radiation such as ultraviolet rays or electron beams. Examples of curable resins include thermosetting resins and ionizing radiation curable resins. Further, examples of the ionizing radiation curable resin include ultraviolet curable resin and electron beam curable resin. Among them, an ionizing radiation curable resin is preferable. This is because the surface hardness of the functional layer can be increased.

As used herein, the term "ionizing radiation-cured resin" refers to a resin cured by irradiation with ionizing radiation. In addition, "ionizing radiation" refers to electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or cross-linking molecules. Examples include charged particle beams such as α rays and ion beams.

Examples of ionizing radiation curable resins include compounds having one or more unsaturated bonds, such as compounds having acrylate-based functional groups. Examples of compounds having one unsaturated bond include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Compounds having two or more unsaturated bonds include, for example, polymethylolpropane tri(meth)acrylate, hexanediol (meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, pentaerythritol tri Polyfunctional compounds such as (meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentylglycol di(meth)acrylate, and the polyfunctional compound and (meth) Examples thereof include reaction products with acrylates and the like (for example, poly(meth)acrylate esters of polyhydric alcohols). "(Meth)acrylate" refers to methacrylate and acrylate.

As the ionizing radiation curable resin, a relatively low molecular weight polyester resin having an unsaturated double bond, a polyether resin, an acrylic resin, an epoxy resin, a urethane resin, an alkyd resin, a spiroacetal resin, a polybutadiene resin, and a polythiol polyene resin. etc. can also be used. Furthermore, as the resin, a low refractive index resin, which will be described later, may be used.

The content of the resin and low refractive index particles in the functional layer satisfies the maximum load that does not cause peeling of the functional layer when a steel wool test is performed after the surface modification described above, and the refractive index of the functional layer as a whole is is appropriately set so as to satisfy the above refractive index.

The functional layer may contain a photopolymerization initiator when an ultraviolet curable resin is used as the resin. Further, when the functional layer contains resin and low refractive index particles, it may contain various additives according to desired physical properties. Additives include, for example, ultraviolet absorbers, antioxidants, light stabilizers, infrared absorbers, dispersing aids, weather resistance improvers, wear resistance improvers, antistatic agents, polymerization inhibitors, cross-linking agents, adhesion property improvers, leveling agents, thixotropic agents, coupling agents, plasticizers, antifoaming agents, fillers and the like.

A method for forming the functional layer is appropriately selected according to the material of the functional layer. When the functional layer contains a low refractive index inorganic material, the method for forming the functional layer includes, for example, a vacuum deposition method, a sputtering method, and the like. Further, when the functional layer contains a resin and low refractive index particles, examples of the method for forming the functional layer include a method of applying a resin composition for the functional layer onto the substrate layer and curing the resin composition. .

(2) When the functional layer is multi-layered When the functional layer is multi-layered, the functional layer may have, for example, a high refractive index film and a low refractive index film in order from the substrate layer side. It may have a refractive index film, a high refractive index film and a low refractive index film, or may have a high refractive index film, a low refractive index film, a high refractive index film and a low refractive index film.

When the functional layer is multi-layered, the number of layers can be two or more, but two layers are preferred. As the number of layers increases, the thickness of the functional layer increases, the hardness of the functional layer increases, and the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above increases. It may be too much.

Moreover, when the functional layer is multi-layered, the functional layer usually has a low refractive index film on the outermost surface opposite to the substrate layer. The refractive index of the low refractive index film can be the same as the refractive index of the functional layer when the functional layer is a single layer.

Further, when the functional layer is a multilayer and has a low refractive index film and a high refractive index film, the refractive index of the high refractive index film is higher than the refractive index of the low refractive index film. For example, it is preferably 1.55 or more and 3.00 or less, more preferably 1.60 or more and 2.50 or less, and even more preferably 1.65 or more and 2.00 or less. If the refractive index of the high refractive index film is within the above range, the reflectance can be easily adjusted by adjusting the refractive index and thickness of each layer constituting the functional layer.

When the functional layer is multi-layered, the thickness of the functional layer is, for example, preferably 70 nm or more, more preferably 80 nm or more, and even more preferably 90 nm or more. If the thickness of the functional layer is too thin, the hardness and adhesion of the functional layer will be low, and the maximum load at which the functional layer will not peel off when the steel wool test is performed after the surface modification described above will be too small. When repeatedly bent, there is a possibility that the bent portion may float. Also, the thickness of the functional layer is, for example, preferably 140 nm or less, more preferably 130 nm or less, and even more preferably 120 nm or less. If the thickness of the functional layer is too thick, the adhesion of the functional layer becomes excessive, and the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above becomes too large. When bent, there is a risk that cracks or breakage may occur at the bent portion. When the functional layer is multi-layered, the thickness of the functional layer is, for example, preferably 70 nm or more and 140 nm or less, more preferably 80 nm or more and 130 nm or less, and even more preferably 90 nm or more and 120 nm or less.
When the functional layer is multi-layered, the thickness of the functional layer refers to the thickness of the entire functional layer.

The thickness of each film constituting the functional layer is appropriately adjusted according to the refractive index of each film.

The thickness of the low refractive index film is, for example, preferably 5 nm or more and 140 nm or less, more preferably 20 nm or more and 130 nm or less, and even more preferably 40 nm or more and 120 nm or less. If the low refractive index film is too thin, the hardness and adhesion of the functional layer will be low, and the maximum load at which the functional layer will not peel off when the steel wool test is performed after the surface modification described above will be too small, resulting in repeated When it is bent, there is a possibility that the bent portion may float. Also, if the thickness of the low refractive index film is too thick, the adhesion of the functional layer becomes excessive, and the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above increases. Therefore, there is a risk that cracks or breakage may occur in the bent portion when repeatedly bent.

The thickness of the high refractive index film is, for example, preferably 5 nm or more and 140 nm or less, more preferably 20 nm or more and 130 nm or less, and even more preferably 40 nm or more and 120 nm or less. If the high refractive index film is too thin, the hardness and adhesion of the functional layer will be low, and the maximum load at which the functional layer will not peel off when the steel wool test is performed after the surface modification described above will be too small, resulting in repeated When it is bent, there is a possibility that the bent portion may float. If the high refractive index film is too thick, the adhesion of the functional layer becomes excessive, and the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above becomes too large. , there is a risk that cracks or breakage may occur at the bent portion when repeatedly bent.

As a material for the low refractive index film, it is possible to obtain a functional layer capable of satisfying the maximum load that does not cause peeling of the functional layer when a steel wool test is performed after the surface modification described above, and The material is not particularly limited as long as it can form a low refractive index film satisfying the refractive index. The low refractive index film may be, for example, either an inorganic film or an organic-inorganic mixed film.
When the low refractive index film is an inorganic film, the low refractive index film can contain, for example, a low refractive index inorganic material having the above refractive index. In addition, when the low refractive index film is an organic-inorganic mixture film, the low refractive index film can contain, for example, a resin and low refractive index particles having a lower refractive index than the resin.

Among them, the low refractive index film is preferably an inorganic film. Inorganic films tend to have higher hardness than organic-inorganic mixed films and organic films, and the functional layer satisfies the maximum load that does not cause peeling when the steel wool test is performed after the surface modification described above. is easy to obtain.

When the low refractive index film contains a low refractive index inorganic material, the low refractive index inorganic material should be the same as the low refractive index inorganic material used when the functional layer is a single layer and is an inorganic film. can be done.

Further, when the low refractive index film contains a resin and low refractive index particles, the resin and the low refractive index particles are the resin and the low refractive index particles used when the functional layer is a single layer and an organic-inorganic mixed film, respectively. It can be similar to refractive index particles.

As a material for the high refractive index film, it is possible to obtain a functional layer capable of satisfying the maximum load that does not cause peeling of the functional layer when a steel wool test is performed after the surface modification described above, and The material is not particularly limited as long as it can form a high refractive index film that satisfies the refractive index. The high refractive index film may be, for example, either an inorganic film or an organic-inorganic mixed film.
When the high refractive index film is an inorganic film, the high refractive index film can contain, for example, a high refractive index inorganic material having the above refractive index. Further, when the high refractive index film is an organic-inorganic mixed film, the high refractive index film can contain, for example, a resin and high refractive index particles having a higher refractive index than the resin.

When the high refractive index film contains a high refractive index inorganic material, the high refractive index film composed of the high refractive index inorganic material is an inorganic material capable of satisfying the above refractive index. is not particularly limited, and examples include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, cerium fluoride and the like.

When the high refractive index film contains a resin and high refractive index particles, the high refractive index particles have a higher refractive index than the resin and satisfy the above refractive index. It is not particularly limited as long as it can be obtained. The high refractive index particles may be either inorganic particles or organic particles. Examples of inorganic particles include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride. mentioned.

The average particle size of the high refractive index particles may be equal to or less than the thickness of the high refractive index film, and may be the same as the average particle size of the low refractive index particles.

The shape of the high refractive index particles is not particularly limited, and may be, for example, spherical, chain-like, or needle-like.

When the high refractive index film contains a resin and high refractive index particles, the resin may be the same as the resin used when the functional layer is a single layer and is an organic-inorganic mixed film. .

The content of the resin and high refractive index particles in the high refractive index film satisfies the maximum load that does not cause peeling of the functional layer when the steel wool test is performed after the surface modification described above, and the functional layer as a whole The refractive index is appropriately set so as to satisfy the above refractive index.

The low refractive index film and the high refractive index film may contain a photopolymerization initiator when using an ultraviolet curable resin as the resin. Further, when the low refractive index film contains a resin and low refractive index particles, or when the high refractive index film contains a resin and high refractive index particles, various additives may be added depending on the desired physical properties. good. Additives may be the same as those used when the functional layer is a single layer.

A method for forming the low refractive index film and the high refractive index film is appropriately selected according to the material of the low refractive index film and the material of the high refractive index film. Further, when the low refractive index film contains a low refractive index inorganic material or when the high refractive index film contains a high refractive index inorganic material, examples of methods for forming the low refractive index film and the high refractive index film include: , a vacuum deposition method, a sputtering method, and the like. When the low refractive index film contains a resin and low refractive index particles, or when the high refractive index film contains a resin and high refractive index particles, the method for forming the low refractive index film and the high refractive index film includes: For example, there is a method in which a resin composition for a low refractive index film or a resin composition for a high refractive index film is applied onto a base material layer and cured.

3. Second Functional Layer The laminate for a display device in the present disclosure preferably has a second functional layer 4 between the base material layer 2 and the functional layer 3, as shown in FIG. 5, for example. By arranging the second functional layer between the base material layer and the functional layer, it is possible to adjust the adhesion of the functional layer, and the peeling of the functional layer when the steel wool test is performed after the surface modification described above. can control the maximum load that does not occur.

The refractive index of the second functional layer is, for example, preferably 1.55 or more and 2.00 or less, more preferably 1.60 or more and 1.90 or less, and 1.65 or more and 1.80 or less. It is even more preferable to have If the refractive index of the second functional layer is within the above range, the reflectance can be easily adjusted by adjusting the refractive index and thickness of the functional layer and the second functional layer. Further, if the refractive index of the second functional layer is too small, the difference between the refractive index of the second functional layer and the refractive index of the functional layer becomes small, suppressing reflection of light using light interference by the thin film. A sufficient effect may not be obtained.

The thickness of the second functional layer is, for example, preferably 50 nm or more and 10 μm or less, more preferably 60 nm or more and 7 μm or less, and even more preferably 70 nm or more and 5 μm or less. When the thickness of the second functional layer is within the above range, the adhesion to the functional layer can be adjusted without impairing flexibility and bending resistance. Moreover, if the thickness of the second functional layer is too thick, there is a possibility that flexibility and bending resistance may be impaired.

When the functional layer is an inorganic film, the second functional layer is preferably an organic-inorganic mixed film. For example, when the substrate layer is a resin substrate and the functional layer is an inorganic film, although the functional layer (inorganic film) has a high hardness, the functional layer (inorganic film) with respect to the substrate layer (resin substrate) However, the second functional layer is arranged between the base material layer and the functional layer, and the second functional layer is an organic-inorganic mixed film. By doing so, the adhesion of the functional layer can be increased compared to the above, and the maximum load can be increased to be within a predetermined range. Further, for example, when the substrate layer is a glass substrate and the functional layer is an inorganic film, although the functional layer (inorganic film) has a high hardness, the functional layer (inorganic film) with respect to the substrate layer (glass substrate) film) tends to be too high, and the maximum load tends to be too large. By using the inorganic mixed film, the adhesion of the functional layer can be moderately lowered as compared with the above, and the maximum load can be moderately decreased to be within a predetermined range.

When the second functional layer is an organic-inorganic mixed film, the second functional layer can contain resin and inorganic particles.

When the second functional layer contains a resin and inorganic particles, the inorganic particles are not particularly limited as long as the second functional layer satisfying the above refractive index can be obtained. Examples of inorganic particles include zirconium oxide, silicon monoxide, hafnium oxide, tantalum oxide, niobium oxide, cerium oxide, titanium oxide, zinc oxide, aluminum oxide, magnesium oxide, yttrium oxide, lanthanum fluoride, and cerium fluoride. Examples include high refractive index particles and low refractive index particles such as silicon dioxide (silica), magnesium fluoride, lithium fluoride, calcium fluoride and barium fluoride. Among them, zirconium oxide is preferable as the high refractive index particles, and silicon dioxide (silica) is preferable as the low refractive index particles.

Moreover, the inorganic particles may be surface-treated. By subjecting the inorganic particles to a surface treatment, the affinity with resins and solvents is improved, the inorganic particles are uniformly dispersed, and the aggregation of the inorganic particles is less likely to occur, so the transparency of the second functional layer is reduced. In addition, it is possible to suppress deterioration of coating properties and film strength of the resin composition for the second functional layer. The surface treatment method can be the same as the surface treatment method for the low refractive index particles used in the functional layer.

The inorganic particles may also be reactive particles having polymerizable functional groups on their surfaces.

The average particle size of the inorganic particles may be equal to or less than the thickness of the second functional layer, for example, 300 nm or less, 200 nm or less, 150 nm or less, or 100 nm or less. may The average particle diameter of the inorganic particles may be, for example, 5 nm or more, may be 10 nm or more, may be 30 nm or more, or may be 50 nm or more. If the average particle size of the inorganic particles is within the above range, the inorganic particles can be dispersed well without impairing the transparency of the second functional layer. As long as the average particle size of the inorganic particles is within the above range, the average particle size may be either the primary particle size or the secondary particle size, and the inorganic particles may be chained together. The method for measuring the average particle size of the inorganic particles can be the same as the method for measuring the average particle size of the low refractive index particles used in the functional layer.

The shape of the inorganic particles is not particularly limited, and examples thereof include spherical, chain-like, needle-like, and the like.

Moreover, when the second functional layer contains a resin and inorganic particles, the resin may be the same as the resin used for the functional layer.

The content of the resin and inorganic particles in the second functional layer satisfies the maximum load that does not cause peeling of the functional layer when the steel wool test is performed after the surface modification described above, and the entire second functional layer is appropriately set so as to satisfy the above refractive index.

The second functional layer may contain a photopolymerization initiator when an ultraviolet curable resin is used as the resin. Moreover, when the second functional layer contains a resin and inorganic particles, it may contain various additives according to desired physical properties. As the additive, the same additives as those used in the functional layer can be used.

Moreover, it is preferable that the surface of the second functional layer facing the functional layer is subjected to a surface treatment. It is possible to increase the adhesion between the second functional layer and the functional layer, and to moderately increase the maximum load at which the functional layer does not peel off when a steel wool test is performed after the surface modification described above. can.

The surface treatment method is not particularly limited as long as it can increase the adhesion between the second functional layer and the functional layer. Examples include corona discharge treatment, plasma treatment, and ozone treatment. treatment, glow discharge treatment, oxidation treatment, and the like.

The surface treatment conditions are appropriately set so as to satisfy the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above. For example, if the output is too small, the adhesion between the second functional layer and the functional layer will be insufficient, and the maximum load that does not cause peeling of the functional layer when performing the steel wool test after the surface modification described above. becomes too small, and when it is repeatedly bent, the bent portion may float. In addition, if the output is too large, the adhesion between the second functional layer and the functional layer becomes excessive, and the maximum load at which the functional layer does not peel off when the steel wool test is performed after the surface modification described above is reached. If it becomes too large, there is a risk that cracks or breakage will occur at the bent portion when it is repeatedly bent. Further, for example, if the surface treatment time is too short, the adhesion between the second functional layer and the functional layer becomes insufficient, and the functional layer is peeled off when the steel wool test is performed after the surface modification described above. The maximum load that does not occur becomes too small, and there is a risk that the bent portion will float when repeatedly bent. Also, if the surface treatment time is too long, the adhesion between the second functional layer and the functional layer becomes excessive, and the functional layer does not peel off when the steel wool test is performed after the surface modification. When the load becomes too large and the sheet is repeatedly bent, there is a risk of cracks or breakage occurring in the bent portion.

A method for forming the second functional layer is appropriately selected according to the material of the functional layer. When the second functional layer contains a resin and inorganic particles, the method for forming the second functional layer includes, for example, coating the resin composition for the second functional layer on the substrate layer, and curing the resin composition. There is a method to make

4. Base Material Layer The base material layer in the present disclosure is a member that supports the functional layer and has transparency.

The substrate layer is not particularly limited as long as it has transparency, and examples thereof include resin substrates and glass substrates.

(1) Resin substrate The resin constituting the resin substrate is not particularly limited as long as it can obtain a transparent resin substrate. Examples include polyimide resins, polyamide resins, Examples include polyester-based resins. Examples of polyimide-based resins include polyimide, polyamideimide, polyetherimide, and polyesterimide. Examples of polyester resins include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate. Among them, polyimide-based resins, polyamide-based resins, or mixtures thereof are preferable, and polyimide-based resins are more preferable, because they have bending resistance and excellent hardness and transparency.

The polyimide-based resin is not particularly limited as long as it can obtain a resin substrate having transparency, but among the above, polyimide and polyamideimide are preferably used. Flexibility and bending resistance can be enhanced, and since the refractive index is relatively high, the reflectance can be easily adjusted.

(a) Polyimide Polyimide is obtained by reacting a tetracarboxylic acid component and a diamine component. The polyimide is not particularly limited as long as it has transparency and rigidity. ) preferably has at least one structure selected from the group consisting of structures represented by

In the above general formula (1), R ¹ is a tetravalent group that is a tetracarboxylic acid residue, R ² is a trans-cyclohexanediamine residue, a trans-1,4-bismethylenecyclohexanediamine residue, 4,4 '-diaminodiphenylsulfone residue, 3,4'-diaminodiphenylsulfone residue, and at least one divalent group selected from the group consisting of a divalent group represented by the following general formula (2) . n represents the number of repeating units and is 1 or more.

In general formula (2) above, R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.

In the above general formula (3), R ⁵ is a cyclohexanetetracarboxylic acid residue, a cyclopentanetetracarboxylic acid residue, a dicyclohexane-3,4,3′,4′-tetracarboxylic acid residue, and 4,4′ At least one tetravalent group selected from the group consisting of -(hexafluoroisopropylidene) ^diphthalic acid residues, and R6 represents a divalent group that is a diamine residue.
n' represents the number of repeating units and is 1 or more.

The term "tetracarboxylic acid residue" refers to a residue obtained by removing four carboxyl groups from a tetracarboxylic acid, and has the same structure as a residue obtained by removing the acid dianhydride structure from a tetracarboxylic dianhydride. show. Moreover, the term "diamine residue" refers to a residue obtained by removing two amino groups from a diamine.

In the above general formula (1), R ¹ is a tetracarboxylic acid residue, which can be a residue obtained by removing the acid dianhydride structure from a tetracarboxylic dianhydride. Examples of tetracarboxylic dianhydrides include those described in International Publication No. 2018/070523. As R ¹ in the above general formula (1), 4,4′-(hexafluoroisopropylidene)diphthalic acid residue, 3,3′,4 ,4′-biphenyltetracarboxylic acid residue, pyromellitic acid residue, 2,3′,3,4′-biphenyltetracarboxylic acid residue, 3,3′,4,4′-benzophenonetetracarboxylic acid residue , 3,3′,4,4′-diphenylsulfonetetracarboxylic acid residue, 4,4′-oxydiphthalic acid residue, cyclohexanetetracarboxylic acid residue, and cyclopentanetetracarboxylic acid residue. Further, 4,4'-(hexafluoroisopropylidene) diphthalic acid residue, 4,4'-oxydiphthalic acid residue, and 3,3',4,4'-diphenyl It preferably contains at least one selected from the group consisting of sulfonetetracarboxylic acid residues.

R ¹ preferably contains 50 mol % or more of these suitable residues in total, more preferably 70 mol % or more, and even more preferably 90 mol % or more.

Further, R ¹ is selected from the group consisting of 3,3′,4,4′-biphenyltetracarboxylic acid residue, 3,3′,4,4′-benzophenonetetracarboxylic acid residue, and pyromellitic acid residue. A tetracarboxylic acid residue group (group A) suitable for improving rigidity such as at least one selected and a 4,4′-(hexafluoroisopropylidene)diphthalic acid residue, 2,3′ , 3,4′-biphenyltetracarboxylic acid residue, 3,3′,4,4′-diphenylsulfonetetracarboxylic acid residue, 4,4′-oxydiphthalic acid residue, cyclohexanetetracarboxylic acid residue, and cyclo It is also preferable to use a mixture of a tetracarboxylic acid residue group (group B) suitable for improving transparency, such as at least one selected from the group consisting of pentanetetracarboxylic acid residues.

In this case, the content ratio of the tetracarboxylic acid residue group (group A) suitable for improving rigidity and the tetracarboxylic acid residue group (group B) suitable for improving transparency is , 0.05 mol of tetracarboxylic acid residue group (group A) suitable for improving rigidity per 1 mol of tetracarboxylic acid residue group (group B) suitable for improving transparency It is preferably 9 mol or less, more preferably 0.1 mol or more and 5 mol or less, and still more preferably 0.3 mol or more and 4 mol or less.

R ² in the above general formula (1) includes, among others, a 4,4′-diaminodiphenylsulfone residue, a 3,4′-diaminodiphenylsulfone residue, a 3,4′-diaminodiphenylsulfone residue, and a and at least one divalent group selected from the group consisting of the divalent groups represented by the general formula (2), and further a 4,4′-diaminodiphenylsulfone residue, 3, 4′-Diaminodiphenylsulfone residue, and at least one divalent group selected from the group consisting of the divalent group represented by the general formula (2), wherein R ³ and R ⁴ are perfluoroalkyl groups. It is preferably a group.

As R ⁵ in the above general formula (3), 4,4′-(hexafluoroisopropylidene)diphthalic acid residue, 3,3′,4 , 4′-diphenylsulfonetetracarboxylic acid residues, and oxydiphthalic acid residues.

R ⁵ preferably contains 50 mol % or more of these suitable residues, more preferably 70 mol % or more, and even more preferably 90 mol % or more.

R6 in the above general formula ( ³ ) is a diamine residue, and can be a residue obtained by removing two amino groups from a diamine. Examples of diamines include those described in International Publication No. 2018/070523. As R ⁶ in the general formula (3), 2,2′-bis(trifluoromethyl)benzidine residue, bis[4-(4- aminophenoxy)phenyl]sulfone residue, 4,4′-diaminodiphenylsulfone residue, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane residue, bis[4-(3-amino phenoxy)phenyl]sulfone residue, 4,4′-diamino-2,2′-bis(trifluoromethyl)diphenyl ether residue, 1,4-bis[4-amino-2-(trifluoromethyl)phenoxy]benzene residue, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane residue, 4,4′-diamino-2-(trifluoromethyl)diphenyl ether residue, 4 ,4'-diaminobenzanilide residue, N,N'-bis(4-aminophenyl)terephthalamide residue, and at least one selected from the group consisting of 9,9-bis(4-aminophenyl)fluorene residue It preferably contains a divalent group of 2,2'-bis(trifluoromethyl)benzidine residue, bis[4-(4-aminophenoxy)phenyl]sulfone residue, and 4,4' -It preferably contains at least one divalent group selected from the group consisting of diaminodiphenylsulfone residues.

R ⁶ preferably contains 50 mol % or more of these suitable residues in total, more preferably 70 mol % or more, and even more preferably 90 mol % or more.

Further, as R ⁶ , bis[4-(4-aminophenoxy)phenyl]sulfone residue, 4,4′-diaminobenzanilide residue, N,N′-bis(4-aminophenyl)terephthalamide residue, A diamine residue group (group C) and 2,2′-bis(trifluoromethyl)benzidine residue, 4,4′-diaminodiphenylsulfone residue, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane residue group, bis[4-(3-aminophenoxy)phenyl]sulfone residue, 4,4′-diamino-2,2′-bis(trifluoromethyl)diphenyl ether residue, 1,4-bis[4-amino- 2-(trifluoromethyl)phenoxy]benzene residue, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane residue, 4,4′-diamino-2- A group of diamine residues suitable for improving transparency, such as at least one selected from the group consisting of (trifluoromethyl)diphenyl ether residues and 9,9-bis(4-aminophenyl)fluorene residues. (Group D) is also preferably used in combination.

In this case, the content ratio of the diamine residue group (group C) suitable for improving rigidity and the diamine residue group (group D) suitable for improving transparency is The diamine residue group (group C) suitable for improving rigidity is 0.05 mol or more and 9 mol or less per 1 mol of the diamine residue group (group D) suitable for improving rigidity. It is preferably 0.1 mol or more and 5 mol or less, and more preferably 0.3 mol or more and 4 mol or less.

In the structures represented by the general formulas (1) and (3), n and n' each independently represent the number of repeating units and are 1 or more. The number n of repeating units in the polyimide may be appropriately selected depending on the structure, and is not particularly limited. The average number of repeating units can be, for example, 10 or more and 2000 or less, preferably 15 or more and 1000 or less.

Also, the polyimide may partially contain a polyamide structure. Polyamide structures that may be included include, for example, polyamideimide structures containing tricarboxylic acid residues such as trimellitic anhydride, and polyamide structures containing dicarboxylic acid residues such as terephthalic acid.

From the viewpoint of improving transparency and improving surface hardness, a tetravalent group that is a tetracarboxylic acid residue of R ¹ or R ⁵ and a divalent group that is a diamine residue of R ² or R ⁶ At least one of the groups is an alkylene group containing an aromatic ring, and (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a sulfonyl group or a fluorine-substituted aromatic ring. It is preferable to include at least one selected from the group consisting of a structure linked with Polyimide contains at least one selected from a tetracarboxylic acid residue having an aromatic ring and a diamine residue having an aromatic ring, so that the molecular skeleton becomes rigid, the orientation increases, and the surface hardness improves. Such an aromatic ring skeleton tends to extend the absorption wavelength to longer wavelengths, and tends to lower the transmittance in the visible light region. On the other hand, if the polyimide contains (i) a fluorine atom, the electron state in the polyimide skeleton can be made difficult to transfer, resulting in improved transparency.
In addition, when the polyimide contains (ii) an alicyclic ring, the transparence of charges in the polyimide skeleton can be inhibited by severing the conjugation of π electrons in the polyimide skeleton, thereby improving the transparency. Further, when the polyimide (iii) contains a structure in which the aromatic rings are linked by a sulfonyl group or an alkylene group optionally substituted with fluorine, the charge in the skeleton is removed by breaking the conjugation of the π electrons in the polyimide skeleton. Transparency improves from the point that movement can be inhibited.

Among them, from the viewpoint of improving transparency and improving surface hardness, R ¹ or R ⁵ is a tetravalent group that is a tetracarboxylic acid residue, and R ² or R ⁶ is a diamine residue 2 At least one of the valent groups preferably contains an aromatic ring and a fluorine atom, and the divalent group which is a diamine residue of R ² or R ⁶ may contain an aromatic ring and a fluorine atom. preferable.

Specific examples of such polyimide include those having a specific structure described in WO2018/070523.

Polyimide can be synthesized by a known method. A commercially available polyimide may also be used. Commercially available polyimides include, for example, Neoprim (registered trademark) manufactured by Mitsubishi Gas Chemical Company, Inc., and the like.

The weight average molecular weight of the polyimide is, for example, preferably 3,000 or more and 500,000 or less, more preferably 5,000 or more and 300,000 or less, and even more preferably 10,000 or more and 200,000 or less. If the weight-average molecular weight is too small, sufficient strength may not be obtained. If the weight-average molecular weight is too large, the viscosity increases and the solubility decreases. may not be obtained.

The weight average molecular weight of polyimide can be measured by gel permeation chromatography (GPC). Specifically, the polyimide is used as an N-methylpyrrolidone (NMP) solution with a concentration of 0.1% by mass, and the developing solvent is a 30 mmol% LiBr-NMP solution with a water content of 500 ppm or less. 8120, column used: GPC LF-804 (manufactured by SHODEX), measurement is performed under the conditions of a sample injection amount of 50 μL, a solvent flow rate of 0.4 mL/min, and 37°C. The weight average molecular weight is determined based on a polystyrene standard sample having the same concentration as the sample.

(b) Polyamideimide The polyamideimide is not particularly limited as long as it can obtain a transparent resin base material, and includes, for example, structural units derived from dianhydrides and structural units derived from diamines. Examples include those having a first block and a second block containing a structural unit derived from an aromatic dicarbonyl compound and a structural unit derived from an aromatic diamine. In the polyamideimide, the dianhydride can include, for example, biphenyltetracarboxylic dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). Also, the diamine can include bistrifluoromethylbenzidine (TFDB). That is, the polyamideimide has a first block copolymerized with a monomer containing a dianhydride and a diamine, and a second block copolymerized with a monomer containing an aromatic dicarbonyl compound and an aromatic diamine. It has a structure obtained by imidizing the polyamideimide precursor.
By having the first block containing an imide bond and the second block containing an amide bond, the above polyamideimide is excellent not only in optical properties but also in thermal and mechanical properties.
In particular, by using bistrifluoromethylbenzidine (TFDB) as the diamine forming the first block, thermal stability and optical properties can be improved. Further, by using 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic dianhydride (BPDA) as dianhydrides forming the first block, It is possible to improve birefringence and ensure heat resistance.

The dianhydrides forming the first block include two types of dianhydrides, namely 6FDA and BPDA. The first block may include a polymer to which TFDB and 6FDA are bonded and a polymer to which TFDB and BPDA are bonded, which are separated based on separate repeating units, and may be included in the same repeating unit. may be regularly arranged, or may be contained in a completely random arrangement.

Among the monomers forming the first block, BPDA and 6FDA are preferably contained in a molar ratio of 1:3 to 3:1 as dianhydrides. This is because not only optical properties can be ensured, but also deterioration of mechanical properties and heat resistance can be suppressed, and excellent birefringence can be obtained.

Preferably, the molar ratio of the first block and the second block is between 5:1 and 1:1.
If the content of the second block is extremely low, the effect of improving the thermal stability and mechanical properties of the second block may not be sufficiently obtained. Further, when the content of the second block is higher than the content of the first block, although the thermal stability and mechanical properties can be improved, the yellowness, transmittance, etc. are lowered, and the optical properties are deteriorated. , the birefringence properties may also be enhanced. The first block and the second block may be random copolymers or block copolymers. The repeating unit of the block is not particularly limited.

Examples of the aromatic dicarbonyl compound forming the second block include terephthaloyl chloride (p-Terephthaloyl chloride, TPC), terephthalic acid, isophthaloyl dichloride (Iso-phthaloyl dichloride) and 4,4 One or more selected from the group consisting of '-benzoyl chloride (4,4'-benzoyl chloride) can be mentioned. Preferably, one or more selected from terephthaloyl chloride (p-Terephthaloyl chloride, TPC) and isophthaloyl dichloride (Iso-phthaloyl dichloride) can be used.

Diamines forming the second block include, for example, 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS) ), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4′-diaminodiphenylsulfone (4DDS), 3,3′-diaminodiphenylsulfone (3DDS), 2,2-bis(4 -(4-aminophenoxy)phenylpropane (BAPP), 4,4'-diaminodiphenylpropane (6HDA), 1,3-bis(4-aminophenoxy)benzene (134APB), 1,3-bis(3-amino phenoxy)benzene (133APB), 1,4-bis(4-aminophenoxy)biphenyl (BAPB), 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (6FAPBP), 3,3- Diamino-4,4-dihydroxydiphenylsulfone (DABS), 2,2-bis(3-amino-4-hydroxyloxyphenyl)propane (BAP), 4,4'-diaminodiphenylmethane (DDM), 4,4'- Mention may be made of diamines having one or more flexible groups selected from the group consisting of oxydianiline (4-ODA) and 3,3'-oxydianiline (3-ODA).

When using an aromatic dicarbonyl compound, it is easy to achieve high thermal stability and mechanical properties, but it may exhibit high birefringence due to the benzene ring in the molecular structure. Therefore, in order to suppress the decrease in birefringence due to the second block, it is preferable to use a diamine having a flexible group introduced into its molecular structure. Specifically, diamines include bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4′-diaminodiphenylsulfone (4DDS) and 2,2-bis(4-(4-aminophenoxy ) phenyl) hexafluoropropane (HFBAPP). In particular, a diamine such as BAPSM having a long flexible group and having a substituent at the meta position can exhibit a superior birefringence.

dianhydrides, including biphenyltetracarboxylic dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA); and diamines, including bistrifluoromethylbenzidine (TFDB). A polyamideimide precursor containing a copolymerized first block and a second block obtained by copolymerizing an aromatic dicarbonyl compound and an aromatic diamine in its molecular structure has a weight-average molecular weight measured by GPC of, for example, 200. ,000 or more and 215,000 or less, and the viscosity is preferably, for example, 2400 poise or more and 2600 poise or less.

Polyamideimide can be obtained by imidating a polyamideimide precursor. Moreover, a polyamide-imide film can be obtained using a polyamide-imide.
For the method for imidizing the polyamideimide precursor and the method for producing the polyamideimide film, for example, Japanese Patent Publication No. 2018-506611 can be referred to.

(2) Glass Substrate The glass constituting the glass substrate is not particularly limited as long as it has transparency, and examples thereof include silicate glass and silica glass. Among them, borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass are preferable, and alkali-free glass is more preferable. Commercially available glass substrates include, for example, ultra-thin sheet glass G-Leaf manufactured by Nippon Electric Glass Co., Ltd., ultra-thin glass manufactured by Matsunami Glass Industry Co., Ltd., and the like.

Moreover, it is also preferable that the glass constituting the glass substrate is chemically strengthened glass. Chemically strengthened glass is excellent in mechanical strength and is preferable in that it can be made thinner accordingly. Chemically strengthened glass is glass whose mechanical properties are strengthened by a chemical method, typically by partially exchanging ion species, such as replacing sodium with potassium, in the vicinity of the surface of the glass. It has a compressive stress layer.

Examples of glass constituting the chemically strengthened glass substrate include aluminosilicate glass, soda lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.

Commercially available chemically strengthened glass substrates include, for example, Corning's Gorilla Glass, AGC's Dragontrail, and Schott's chemically strengthened glass.

(3) Structure of base layer The thickness of the base layer is not particularly limited as long as it is a thickness that allows flexibility, and is appropriately selected according to the type of base layer. be.

The thickness of the resin base material is, for example, preferably 10 μm or more and 100 μm or less, and more preferably 25 μm or more and 80 μm or less. When the thickness of the resin base material is within the above range, good flexibility and sufficient hardness can be obtained. Moreover, the curling of the laminate for a display device can also be suppressed. Furthermore, it is preferable in terms of weight reduction of the laminate for a display device.

The thickness of the glass substrate is, for example, preferably 200 μm or less, more preferably 15 μm or more and 100 μm or less, further preferably 20 μm or more and 90 μm or less, and 25 μm or more and 80 μm or less. is particularly preferred. When the thickness of the glass substrate is within the above range, good flexibility and sufficient hardness can be obtained. Moreover, the curling of the laminate for a display device can also be suppressed. Furthermore, it is preferable in terms of weight reduction of the laminate for a display device.

5. Other Layers The laminate for a display device in the present disclosure can have other layers in addition to the base layer and functional layer described above.

(1) Hard coat layer The laminate for a display device in the present disclosure can have a hard coat layer between the base material layer and the functional layer. As described above, when the second functional layer is arranged between the base layer and the functional layer, for example, as shown in FIG. 6, between the base layer 2 and the second functional layer 4 It can have a hard coat layer 5 . The hard coat layer is a member for increasing surface hardness. The scratch resistance can be improved by arranging the hard coat layer. In particular, when the base material layer is a resin base material, the scratch resistance can be effectively improved by disposing the hard coat layer.

The refractive index of the hard coat layer is, for example, preferably 1.70 or less, more preferably 1.45 or more and 1.67 or less, and further preferably 1.48 or more and 1.65 or less. It is preferably 1.50 or more and 1.60 or less, particularly preferably. When the refractive index of the hard coat layer is within the above range, surface hardness can be increased without impairing flexibility and bending resistance.

As a material for the hard coat layer, for example, an organic material, an inorganic material, an organic-inorganic composite material, or the like can be used.

Among them, the material of the hard coat layer is preferably an organic material. As the organic material, for example, it is preferable to use a cured resin cured by irradiation with heat or ionizing radiation such as ultraviolet rays or electron beams. The cured resin may be the same as the cured resin used for the functional layer.

The hard coat layer may contain a polymerization initiator as needed. As the polymerization initiator, radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, and the like can be appropriately selected and used. These polymerization initiators are decomposed by at least one of light irradiation and heating to generate radicals or cations to promote radical polymerization and cationic polymerization. In some cases, the polymerization initiator is completely decomposed and does not remain in the hard coat layer.

The hard coat layer may contain a photopolymerization initiator when an ultraviolet curable resin is used as the resin. Further, the hard coat layer may contain various additives according to desired physical properties. Additives may be the same as those used in the functional layer.

The thickness of the hard coat layer may be appropriately selected depending on the function of the hard coat layer and the application of the laminate for display device. The thickness of the hard coat layer is, for example, preferably 0.5 μm or more and 50 μm or less, more preferably 1.0 μm or more and 40 μm or less, further preferably 1.5 μm or more and 30 μm or less. It is particularly preferable to be 0 μm or more and 20 μm or less. If the thickness of the hard coat layer is within the above range, it is possible to obtain sufficient hardness as the hard coat layer.

As a method for forming the hard coat layer, for example, a method of applying a hard coat layer resin composition onto the substrate layer and curing the resin composition can be used.

(2) Impact Absorbing Layer The laminate for a display device according to the present disclosure can have an impact absorbing layer 6 on the surface of the base material layer 2 opposite to the functional layer 3, for example, as shown in FIG. By arranging the shock absorbing layer, when a shock is applied to the laminate for a display device, the shock can be absorbed and the shock resistance can be improved. Moreover, when the base material layer is a glass base material, cracking of the glass base material can be suppressed.

The material for the impact absorbing layer is not particularly limited as long as it has impact absorbing properties and can provide a transparent impact absorbing layer. Examples include polyethylene terephthalate (PET) and polyethylene naphthalate. (PEN), urethane resin, epoxy resin, polyimide, polyamideimide, acrylic resin, triacetyl cellulose (TAC), silicone resin, and the like. These materials may be used singly or in combination of two or more.

The impact-absorbing layer can further contain additives as needed. Examples of additives include inorganic particles, organic particles, ultraviolet absorbers, antioxidants, light stabilizers, surfactants, and adhesion improvers.

The thickness of the impact absorption layer may be any thickness that can absorb impact, and for example, it is preferably 5 μm or more and 150 μm or less, more preferably 10 μm or more and 120 μm or less, further preferably 15 μm or more and 100 μm. can be:

As the impact absorbing layer, for example, a resin film may be used. Further, for example, a shock absorbing layer may be formed by applying a composition for a shock absorbing layer onto the base material layer.

(3) Adhesive layer for attachment The laminate for a display device in the present disclosure can have an adhesive layer 7 for attachment on the surface of the base material layer 2 opposite to the functional layer 3, for example, as shown in FIG. . The laminate for a display device can be attached to, for example, a display panel or the like via the adhesive layer for attachment.

The adhesive used for the sticking adhesive layer is not particularly limited as long as it has transparency and is capable of adhering the laminate for a display device to a display panel or the like. Curable adhesives, ultraviolet curable adhesives, two-liquid curable adhesives, hot-melt adhesives, pressure-sensitive adhesives (so-called adhesives), and the like can be mentioned.

The thickness of the adhesive layer for attachment is, for example, preferably 10 μm or more and 100 μm or less, more preferably 25 μm or more and 80 μm or less, and even more preferably 40 μm or more and 60 μm or less. If the thickness of the sticking adhesive layer is too thin, there is a possibility that the display device laminate and the display panel or the like cannot be sufficiently adhered. Moreover, when the thickness of the adhesive layer for sticking is too thick, flexibility may be impaired.

As the sticking adhesive layer, for example, an adhesive film may be used. Also, for example, an adhesive composition may be applied onto a support or a substrate layer to form an adhesive layer for attachment.

(4) Antifouling layer In the laminate for a display device according to the present disclosure, for example, as shown in FIG. good. By disposing the antifouling layer, antifouling properties can be imparted to the laminate for a display device. In the present disclosure, the thickness of the antifouling layer is relatively thin as described later, so it is presumed that it does not affect thin film interference.

As the material for the antifouling layer, a general antifouling layer material such as a fluorine compound or a silicone compound can be applied.
In the present embodiment, in a mode of use in which the images of the first display area and the second display area are observed in a folded state, the antifouling can be repeatedly wiped off fingerprints, stains, etc. attached to the first display area or the second display area. A fluorine compound is preferable from the viewpoint of imparting properties and transparency and maintaining the visibility of the image.

Examples of the fluorine compound include fluorine compounds having reactive functional groups such as (meth)acryloyl groups, vinyl groups, epoxy groups, oxetanyl groups, and ethylenically unsaturated bond groups, fluorine compounds having the above reactive functional groups and silicon, and the like. For example, a fluorine compound having a fluoroalkylene group in the main chain, a fluorine compound having a fluoroalkylene group in the main chain and side chains, a fluorine compound having a fluoroalkyl group, a fluorine compound having a siloxane bond, a reactive functional group Fluorine compounds having a silicone containing, fluorine compounds having a reactive functional group and a perfluoropolyether group, fluorine compounds having a silane unit containing a perfluoropolyether group, etc. can be mentioned,
In this embodiment, it is preferable to use a fluorine compound having a silane unit containing a perfluoropolyether group.

The thickness of the antifouling layer is, for example, preferably 1 nm or more and 30 nm or less, more preferably 2 nm or more and 20 nm or less, and even more preferably 3 nm or more and 10 nm or less. If the thickness of the antifouling layer is within the above range, antifouling properties and durability can be improved.

Examples of the method for forming the antifouling layer include a method of applying a resin composition for an antifouling layer onto the functional layer and curing the composition, a vacuum deposition method, a sputtering method, and the like.

(5) Interlayer adhesive layer In the laminate for a display device according to the present disclosure, an interlayer adhesive layer may be arranged between each layer.

As the adhesive used for the interlayer adhesive layer, the same adhesive as used for the adhesive layer for attachment can be used.

The thickness, formation method, etc. of the interlayer adhesive layer can be the same as the thickness, formation method, etc. of the adhesive layer for attachment.

6. Use of Laminate for Display Device The laminate for a display device according to the present disclosure can be used as a front plate arranged closer to the viewer than the display panel in a display device. Among others, the laminate for a display device according to the present disclosure can be suitably used for a front plate in a flexible display device such as a foldable display, a rollable display, and a bendable display. In particular, the laminate for a display device according to the present disclosure can improve the visibility at the bent portion and the visibility in a usage pattern in which an image is observed while the display device is folded. It can be used preferably.

Further, the display device laminate in the present disclosure can be used, for example, as a front plate in a display device such as a smartphone, a tablet terminal, a wearable terminal, a personal computer, a television, a digital signage, a public information display (PID), or an in-vehicle display. can be done.

B. Display Device A display device according to the present disclosure includes a display panel and the above-described display device laminate disposed on the viewer side of the display panel.

FIG. 10 is a schematic cross-sectional view showing an example of a display device according to the present disclosure. As shown in FIG. 10 , the display device 30 includes a display panel 31 and the display device laminate 1 arranged on the viewer side of the display panel 31 . In the display device 30 , the display device laminate 1 and the display panel 31 can be bonded together, for example, via the bonding adhesive layer 7 of the display device laminate 1 .

When the laminate for a display device according to the present disclosure is arranged on the surface of the display device, the functional layer is arranged on the outside and the substrate layer is arranged on the inside.

The method for disposing the laminate for a display device according to the present disclosure on the surface of the display device is not particularly limited, but includes, for example, a method via an adhesive layer.

Examples of the display panel in the present disclosure include display panels used in display devices such as organic EL display devices and liquid crystal display devices.

The display device according to the present disclosure can have a touch panel member between the display panel and the laminate for display device.

The display device according to the present disclosure is preferably a flexible display device such as a foldable display, a rollable display, or a bendable display.

Also, the display device according to the present disclosure is preferably foldable. That is, the display device in the present disclosure is preferably a foldable display. The display device according to the present disclosure has excellent visibility at the bent portion and visibility in a usage pattern in which an image is observed with the display device folded, and is suitable as a foldable display.

Note that the present disclosure is not limited to the above embodiments. The above embodiment is an example, and any device that has substantially the same configuration as the technical idea described in the claims of the present disclosure and achieves the same effect is the present invention. It is included in the technical scope of the disclosure.

Examples and comparative examples are given below to further illustrate the present disclosure.

[Example 1]
(1) Formation of hard coat layer First, each component was blended so as to have the composition shown below to obtain a resin composition 1 for functional layer.

<Composition of Resin Composition 1 for Functional Layer>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “UV-7000B”, manufactured by Mitsubishi Chemical Corporation): 100 Parts by mass Silica particles (average primary particle size 12 nm, manufactured by Nissan Chemical Industries, Ltd.): 35 parts by mass (converted to 100% solid content)
・Methyl isobutyl ketone: 220 parts by mass

Next, a 50 μm-thick polyimide film (Mitsubishi Gas Chemical Co., Ltd. “Neoprim”) is used as the base layer, and the functional layer resin composition 1 is applied on the base layer with a bar coater to form a coating film. formed. Then, this coating film is heated at 70 ° C. for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (Fusion UV Systems Japan Co., Ltd., light source H bulb) is used to irradiate ultraviolet rays with oxygen concentration. was 200 ppm or less, the coating film was cured by irradiating so that the integrated light quantity was 40 mJ/cm ² , and a hard coat layer having a thickness of 3 μm was formed.

(2) Formation of second functional layer Each component was blended so as to have the composition shown below to obtain a resin composition 2 for functional layer.

<Composition of Resin Composition 2 for Functional Layer>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 70 mass Part ・ Pentaerythritol acrylate (product name “A-TMM-3”, manufactured by Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass ・ High refractive index particles (zirconium oxide, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 100 mass Part (value converted to 100% solid content)
・Methyl isobutyl ketone: 230 parts by mass

Next, the functional layer resin composition 2 was applied on the hard coat layer with a bar coater to form a coating film. Then, this coating film is heated at 70 ° C. for 1 minute to evaporate the solvent in the coating film, and an ultraviolet irradiation device (Fusion UV Systems Japan Co., Ltd., light source H bulb) is used to irradiate ultraviolet rays with oxygen concentration. was 200 ppm or less and the integrated light amount was 400 mJ/cm ² to cure the coating film to form a second functional layer having a thickness of 3 μm.

(3) Formation of functional layer The surface of the second functional layer was modified by plasma treatment at an output of 200 W for 180 seconds. After that, on the surface-modified second functional layer, a film of a low refractive index inorganic material (silicon dioxide (silica)) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.) to a thickness of 90 nm. A functional layer was formed.

(4) Formation of Antifouling Layer The surface of the functional layer was modified by plasma treatment at an output of 200 W for 60 seconds. After that, on the surface-modified functional layer, a film of a fluorine compound (product name "Optool UD120", manufactured by Daikin Industries, Ltd.) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.) to a thickness of 7 nm. An antifouling layer was formed.

[Example 2]
A laminate was produced in the same manner as in Example 1, except that the second functional layer was formed using the functional layer resin composition 3 described below.

<Composition of Resin Composition 3 for Functional Layer>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 83 mass Part ・ Pentaerythritol acrylate (product name “A-TMM-3”, manufactured by Shin-Nakamura Chemical Co., Ltd.): 17 parts by mass ・ High refractive index particles (zirconium oxide, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 180 mass Part (value converted to 100% solid content)
・Methyl isobutyl ketone: 250 parts by mass

[Example 3]
A laminate was produced in the same manner as in Example 1, except that a second functional layer was formed using a functional layer resin composition 4 described below.

<Composition of the functional layer resin composition 4>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 70 mass Part ・ Pentaerythritol acrylate (product name “A-TMM-3”, manufactured by Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass ・ High refractive index particles (zirconium oxide, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 70 mass Part (value converted to 100% solid content)
・Methyl isobutyl ketone: 230 parts by mass

[Example 4]
A laminate was produced in the same manner as in Example 1, except that a second functional layer having a thickness of 70 nm was formed using a functional layer resin composition 5 described below.

<Composition of the functional layer resin composition 5>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 70 mass Part ・ Pentaerythritol acrylate (product name “A-TMM-3”, manufactured by Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass ・ High refractive index particles (zirconium oxide, average primary particle size 11 nm, manufactured by Nippon Shokubai Co., Ltd.): 100 mass Part (value converted to 100% solid content)
・Methyl isobutyl ketone: 320 parts by mass

[Example 5]
A laminate was produced in the same manner as in Example 1, except that the thickness of the second functional layer was 1 μm.

[Example 6]
A laminate was produced in the same manner as in Example 1, except that the thickness of the second functional layer was 10 μm.

[Example 7]
A laminate was produced in the same manner as in Example 1, except that the thickness of the functional layer was 120 nm.

[Example 8]
A laminate was produced in the same manner as in Example 1, except that the thickness of the functional layer was 60 nm.

[Example 9]
A laminate was produced in the same manner as in Example 1, except that a functional layer having a high refractive index film and a low refractive index film was formed as follows.

First, the surface of the second functional layer was modified by plasma treatment with an output of 200 W for 180 seconds. After that, on the surface-modified second functional layer, a film of a high refractive index inorganic material (zirconium oxide) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.) to form a film with a high refractive index of 10 nm thick. A film was formed.

Next, the surface of the high refractive index film was modified by plasma treatment with an output of 200 W for 120 seconds. After that, on the surface-modified high refractive index film, a film of a low refractive index inorganic material (silicon dioxide (silica)) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.) to a thickness of 110 nm. A refractive index film was formed.

[Example 10]
A laminate was produced in the same manner as in Example 4, except that the thickness of the second functional layer was 140 nm.

[Comparative Example 1]
A laminate was produced in the same manner as in Example 1, except that the second functional layer was formed using the functional layer resin composition 6 described below.

<Composition of the functional layer resin composition 6>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 40 mass Part ・ Pentaerythritol acrylate (product name “A-TMM-3”, manufactured by Shin-Nakamura Chemical Co., Ltd.): 60 parts by mass ・ Low refractive index particles (hollow silica, average primary particle diameter 50 nm, manufactured by JGC Catalysts and Chemicals Co., Ltd.): 35 Parts by mass (value converted to 100% solid content)
・Methyl isobutyl ketone: 220 parts by mass

[Comparative Example 2]
A laminate was produced in the same manner as in Example 1, except that the output of 100 W was used as the surface treatment condition in the formation of the second functional layer.

[Comparative Example 3]
A laminate was produced in the same manner as in Example 1, except that the output of 400 W was used as the surface treatment condition in the formation of the second functional layer.

[Comparative Example 4]
A laminate was produced in the same manner as in Example 1, except that a functional layer having a high refractive index film and a low refractive index film was formed as follows.

First, the surface of the second functional layer was modified by plasma treatment with an output of 200 W for 180 seconds. After that, on the surface-modified second functional layer, a film of a high refractive index inorganic material (zirconium oxide) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.), and a high refractive index film having a thickness of 80 nm is formed. A film was formed.

Next, the surface of the high refractive index film was modified by plasma treatment at an output of 200 W for 120 seconds. After that, on the surface-modified high refractive index film, a film of a low refractive index inorganic material (silicon dioxide (silica)) was formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.) to a thickness of 90 nm. A refractive index film was formed.

[Comparative Example 5]
A laminate was produced in the same manner as in Example 1, except that the thickness of the functional layer was 150 nm.

[Comparative Example 6]
A laminate was produced in the same manner as in Example 1, except that the thickness of the functional layer was 40 nm.

[Comparative Example 7]
A laminate was produced in the same manner as in Example 1, except that the second functional layer and the functional layer were formed as follows.

(1) Formation of Second Functional Layer A second functional layer was formed in the same manner as in Example 1, except that the following resin composition 7 for functional layer was used.

<Composition of Resin Composition 7 for Functional Layer>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 70 mass Parts ・ Pentaerythritol acrylate (product name “A-TMM-3”, manufactured by Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass ・ High refractive index particles (titanium oxide, average primary particle size 5 nm, manufactured by Resinocolor Industry Co., Ltd.): 270 mass Part (value converted to 100% solid content)
・Methyl isobutyl ketone: 250 parts by mass

(2) Formation of functional layer The surface of the second functional layer was modified by plasma treatment at an output of 400 W for 180 seconds. After that, on the surface-modified second functional layer, a film of a low refractive index inorganic material (silicon dioxide (silica)) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.) to a thickness of 90 nm. A functional layer was formed.

[Comparative Example 8]
A laminate was produced in the same manner as in Example 1, except that a second functional layer was formed and a functional layer having a high refractive index film and a low refractive index film was formed as follows. did.

(1) Formation of Second Functional Layer A second functional layer was formed in the same manner as in Example 1, except that the following resin composition 8 for functional layer was used.

<Composition of the functional layer resin composition 8>
・Polymerization initiator (1-hydroxycyclohexylphenyl ketone, product name “Omnirad184”, manufactured by IGM Resins B.V.): 3 parts by mass ・Urethane acrylate (product name “EBECRYL8209”, manufactured by Daicel Ornex): 100 mass Part Low refractive index particles (hollow silica, average primary particle size 50 nm, manufactured by Nikki Shokubai Kasei Co., Ltd.): 40 parts by mass (converted to 100% solid content)
・Methyl isobutyl ketone: 220 parts by mass

(2) Formation of functional layer The surface of the second functional layer was modified by plasma treatment at an output of 200 W for 180 seconds. After that, on the surface-modified second functional layer, a film of a high refractive index inorganic material (zirconium oxide) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.), and a first film having a thickness of 30 nm is formed. A high refractive index film was formed.

Next, plasma treatment was performed at an output of 200 W for 150 seconds to modify the surface of the first high refractive index film. After that, on the surface-modified first high refractive index film, a film of a low refractive index inorganic material (silicon dioxide (silica)) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.). A first low refractive index film of 20 nm was formed.

Next, plasma treatment was performed at an output of 200 W for 120 seconds to modify the surface of the first low refractive index film. After that, on the surface-modified first low refractive index film, a film of a high refractive index inorganic material (zirconium oxide) was formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.). No. 2 high refractive index film was formed.

Next, the surface of the second high refractive index film was modified by plasma treatment with an output of 200 W for 90 seconds. After that, on the surface-modified second high refractive index film, a film of a low refractive index inorganic material (silicon dioxide (silica)) is formed by a vacuum deposition method using a vacuum deposition device (manufactured by ULVAC, Inc.). A second low refractive index film of 90 nm was formed.

[evaluation]
(1) Luminous reflectance The luminous reflectance was determined according to JIS Z8722:2009. From the reflection spectrum obtained by making light in the wavelength range of 380 nm or more and 780 nm or less incident on the functional layer side surface of the laminate, in the 2 degree field of view with standard light C, the tristimulus value X in the XYZ color system, Y and Z were determined, and the value of Y was taken as the luminous reflectance. In the measurement of luminous reflectance, a spectrophotometer "UV-2600" manufactured by Shimadzu Corporation was used under the following conditions. In addition, in order to prevent back reflection, the luminous reflectance of the laminate was measured using a black vinyl tape (product name "Yamato vinyl tape NO200-19-21" manufactured by Yamato Co., Ltd., 19 mm wide) with a width larger than the measurement spot area. ) was attached to the back surface of the laminate, and then measured.

(Measurement condition)
・Field of view: 2°
・Illuminant: C
・Light source: tungsten halogen lamp ・Measurement wavelength: 0.5 nm interval in the range of 380 nm to 780 nm ・Scan speed: high speed ・Slit width: 5.0 nm
・S/R switching: Standard ・Auto zero: Performed at 550 nm after baseline scanning

(2) The maximum load at which the functional layer does not peel off when the steel wool test is performed after surface modification. The laminate was mounted on the stage of No. 2 so that the antifouling layer side surface faced upward, and the entire surface of the antifouling layer side surface of the laminate was subjected to corona discharge treatment under the following conditions.
・Output voltage: 14kV
・Distance from the antifouling layer side surface of the display device laminate to the electrode of the corona discharge treatment device: 2 mm
・Movement speed of corona scanner stage: 30mm/sec

Next, using Gakushin type rubbing fastness tester AB-301 manufactured by Tester Sangyo Co., Ltd., the laminate having a size of 5 cm × 10 cm was fixed on a glass plate with cellophane tape so as not to break or wrinkle. Next, using #0000 steel wool (Bonstar #0000 manufactured by Nippon Steel Wool Co., Ltd.), the steel wool is fixed to a jig of 1 cm × 1 cm, a load of 100 g / cm ² or more, a moving speed of 100 mm / sec, and a moving distance Under the condition of 50 mm, the surface of the laminate for a display device on the antifouling layer side was rubbed back and forth 100 times. Then, the load was increased from 100 g/cm ^{2 by 100 g/cm 2 to} obtain the maximum load at which the functional layer did not peel off.

(3) Dynamic bending resistance The following dynamic bending test was performed on the laminate to evaluate bending resistance. First, a laminate with a size of 50 mm × 200 mm was prepared, and as shown in FIG. A short side portion 1C of the body 1 and a short side portion 1D facing the short side portion 1C were fixed by fixing portions 51 arranged in parallel. Next, as shown in FIG. 4(b), the fixed portions 51 are moved closer to each other, thereby deforming the laminate for display device 1 so as to be folded, and further, as shown in FIG. 4(c). Then, after moving the fixing portion 51 to a position where the distance d between the two opposing short side portions 1C and 1D fixed by the fixing portion 51 of the display device laminate 1 becomes a predetermined value, the fixing portion 51 is removed. Deformation of the display device laminate 1 was eliminated by moving in the opposite direction. By moving the fixing portion 51 as shown in FIGS. 4A to 4C, the stack 1 for a display device was repeatedly folded by 180°. At this time, the distance d between the two opposing short sides 1C and 1D of the display device laminate 1 was set to 10 mm. In addition, when the laminated body was bent so that the functional layer was on the inside, it was called inward bending, and when it was bent so that the functional layer was on the outside, it was called outward bending. The results of the dynamic bending test were evaluated according to the following criteria.
A: The laminate did not crack or break even after 300,000 cycles.
B: Cracking or breakage occurred in the laminate by 300,000 cycles.

(4) Visibility After the above dynamic bending test was performed on the laminate, the position and bending direction of the bending portion of the laminate were aligned with the position and bending direction of the bendable display, and the lamination was performed. The layered product was adhered to the surface of a foldable display ("ThinkPad X1 Fold" manufactured by Lenovo) so that the surface on the body's functional layer side was the surface, and the visibility was confirmed. At this time, for example, the angle θ2 of the foldable display 20 as shown in FIG. 3 was set to 120°.

For example, with regard to the visibility of the first display area 22 of the foldable display 20 as shown in FIG. 3, characters were displayed to confirm whether the characters could be visually recognized.

Also, regarding the visibility of the bent portion 21 of the foldable display 20 shown in FIG. 3, for example, an image was displayed to check whether the bent portion 21 and other regions looked strange.

The visibility was evaluated according to the following criteria.
A: 10 out of 10 people could visually recognize without any problem.
B: 7 or more and 9 or less out of 10 people could visually recognize without any problem.
C: 4 or more and 6 or less out of 10 persons could visually recognize without any problem.
D: Less than 4 out of 10 people could visually recognize without any problem.

In the laminates of Examples 1 to 10, the luminous reflectance of specularly reflected light at an incident angle of 60° was a predetermined value or less, and the steel wool test was performed after the surface modification described above. Since the maximum load at which peeling does not occur is within a predetermined range, the visibility of the above-mentioned first display area is good, and the visibility is good in the usage pattern in which an image is observed while the foldable display is folded. In addition, the dynamic bendability was excellent, and the visibility of the bent portion was good.

On the other hand, in the laminate of Comparative Example 1, the luminous reflectance of specularly reflected light at an incident angle of 60° was high, and the visibility of the above-described first display area was poor. This is because the difference in refractive index between the functional layer and the second functional layer is small and the antireflection effect is low.

In the functional layer of Comparative Example 2, since the output of the surface treatment (plasma treatment) to the second functional layer is small, the adhesion between the second functional layer and the functional layer is insufficient. The maximum load at which the functional layer did not peel off was small when a steel wool test was performed after quality, the dynamic flexibility was poor, and the visibility of the bent portion was poor.

In the laminate of Comparative Example 3, since the output of the surface treatment (plasma treatment) to the second functional layer is large, the adhesion between the second functional layer and the functional layer is excessive. When the steel wool test was performed later, the maximum load at which the functional layer did not peel off was large, the dynamic flexibility was poor, and the visibility of the bent portion was poor.

In the laminate of Comparative Example 4, when the steel wool test was performed after the surface modification described above, the maximum load at which the functional layer did not peel off was large, the dynamic flexibility was poor, and the visibility of the bent portion was poor.
This is because although the number of layers constituting the functional layer is two, the overall thickness of the functional layer is large, so the adhesion of the functional layer is excessive and the flexibility is poor.

In the laminate of Comparative Example 5, when the steel wool test was performed after the surface modification described above, the maximum load at which the functional layer did not peel off was large, the dynamic flexibility was poor, and the visibility of the bent portion was poor.
This is because the thickness of the functional layer is large, so the adhesion of the functional layer is excessive and the flexibility is poor.

In the laminate of Comparative Example 6, the luminous reflectance of specularly reflected light at an incident angle of 60° was high, and the visibility of the above-described first display area was poor. This is because the thickness of the functional layer is thin and the antireflection effect is low. In addition, in the laminate of Comparative Example 6, when the steel wool test was performed after the surface modification described above, the maximum load at which the functional layer did not peel off was small, the dynamic flexibility was poor, and the visibility of the bent portion was poor. rice field. This is because the thickness of the functional layer is small, the hardness of the functional layer is low, and the adhesiveness of the functional layer is insufficient.

In the laminate of Comparative Example 7, although the output of the surface treatment (plasma treatment) to the second functional layer is large, the content of inorganic particles in the second functional layer is large, so the adhesion of the functional layer is poor. Therefore, when the steel wool test was performed after the surface modification described above, the maximum load at which the functional layer did not peel off was small, the dynamic flexibility was poor, and the visibility of the bent portion was poor.

In the laminate of Comparative Example 8, when the steel wool test was performed after the surface modification described above, the maximum load at which the functional layer did not peel off was large, the dynamic flexibility was poor, and the visibility of the bent portion was poor.
This is because the number of layers constituting the functional layer is large and the overall thickness of the functional layer is large, so the adhesion of the functional layer is excessive and the flexibility is poor.

DESCRIPTION OF SYMBOLS 1... Laminate for a display device 2... Base material layer 3... Functional layer 4... Second functional layer 5... Hard coat layer 6... Shock absorbing layer 7... Adhesive layer for attachment 8... Antifouling layer 30... Display device 31... display panel

Claims (13)

A laminate for a display device having a substrate layer and a functional layer,
The luminous reflectance of specularly reflected light when light is incident on the functional layer side surface of the display device laminate at an incident angle of 60° is 10.0% or less,
After performing surface modification on the functional layer side surface of the display device laminate, a predetermined load is applied to the functional layer side surface of the display device laminate using #0000 steel wool. A laminate for a display device, wherein the maximum load at which the functional layer is not peeled off is 1.0 kg/cm ² or more and 2.0 kg/cm ² or less when a steel wool test of 100 reciprocating rubbings is performed. The laminate for a display device according to claim 1, wherein the functional layer is an inorganic film. 3. The laminate for a display device according to claim 2, wherein said inorganic film contains silicon dioxide. 4. The laminate for a display device according to claim 1, wherein the functional layer has a thickness of 50 nm or more and 140 nm or less. 5. The laminate for a display device according to claim 1, wherein the functional layer has a refractive index of 1.40 or more and 1.50 or less. 6. The method according to any one of claims 1 to 5, wherein a second functional layer is provided between the base layer and the functional layer, and the second functional layer contains a resin and inorganic particles. The laminate for a display device described above. 7. The laminate for a display device according to claim 6, wherein the second functional layer has a thickness of 50 nm or more and 10 [mu]m or less. The laminate for a display device according to claim 6 or 7, wherein the second functional layer has a refractive index of 1.55 or more and 2.00 or less. The laminate for a display device according to any one of claims 1 to 8, comprising a hard coat layer between the base material layer and the functional layer. 10. The laminate for a display device according to any one of claims 1 to 9, which has an impact absorbing layer on the side opposite to the functional layer of the base material layer. 11. The laminate for a display device according to any one of claims 1 to 10, which has an adhesive layer for attachment on the side opposite to the functional layer of the base material layer. 12. The laminate for a display device according to any one of claims 1 to 11, which has an antifouling layer on a surface of the functional layer opposite to the base layer. a display panel;
a laminate for a display device according to any one of claims 1 to 12, arranged on the viewer side of the display panel;
A display device.

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