Display device member, optical laminate and display device

Abstract

The present disclosure provides a display device member comprising: a glass substrate having a thickness of 100 µm or less; and a resin layer that is provided on one surface side of the glass substrate, has a composite elastic modulus of 5.7 GPa or greater, and has a thickness of from 5 µm to 60 µm.

Description

[Technical field]

[0001] The present disclosure relates to a member for a display device, an optical laminate, and a display device. [Background technology]

[0002] Conventionally, a cover member made of glass or resin is used in a display device to protect the display device. This cover member protects the display device from impact and scratches, and is required to have strength, impact resistance, scratch resistance, etc. Glass cover members are characterized by high surface hardness, scratch resistance, high transparency, etc., while resin cover members are characterized by light weight and shatter resistance. In addition, the thicker the cover member is, the better its function of protecting the display device from impact is, and the material and thickness of the cover member are appropriately selected and used based on the weight, cost, size of the display device, etc.

[0003] 2. Description of the Related Art In recent years, flexible displays such as foldable displays, rollable displays, and bendable displays have been actively developed, and in particular, development of foldable displays, that is, display devices that can be bent, has been progressing.

[0004] In a bendable display device, the cover member must also bend in accordance with the movement of the display device, and therefore a bendable cover member is used. In the case of resin cover members, polyimide or polyamideimide films that have been made colorless and transparent by devising a chemical structure have been developed (see, for example, Patent Document 1). In addition, in the case of glass cover members, studies are being conducted on cover members that can be bent by thinning the glass, such as ultra-thin glass (UTG) (see, for example, Patent Document 2). Among glasses, chemically strengthened glass has particularly high bending resistance, and by incorporating an expanding stress in the glass surface, minute scratches on the glass surface are prevented from becoming larger when bent, making the glass less likely to break. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-137864 A [Patent Document 2] JP 2018-188335 A Summary of the Invention [Problem to be solved by the invention]

[0006] Glass has a higher elastic modulus than resin, and therefore has a higher ability to protect a display device than resin when the thickness is the same. Glass also has high optical transparency, making it possible to manufacture a display device with better visibility. On the other hand, as glass becomes thinner, it becomes more fragile, and its impact resistance is dramatically reduced. If the glass of the cover member is broken by an external impact, not only will its function of protecting the display device be reduced, but the resulting fragments and sharp edges may injure the user's fingertips, etc.

[0007] The present disclosure has been made in view of the above circumstances, and has a first object to provide a display device member having excellent impact resistance and flexibility and improved safety, an optical laminate, and a display device including the same. A second object of the present disclosure is to provide a display device member having excellent strength, impact resistance, scratch resistance, and flexibility and improved safety, and a display device including the same. [Means for solving the problem]

[0008] One embodiment of the present disclosure provides a member for a display device, comprising: a glass substrate having a thickness of 100 μm or less; and a resin layer disposed on one surface side of the glass substrate, the resin layer having a composite elastic modulus of 5.7 GPa or more and a thickness of 5 μm or more and 60 μm or less.

[0009] The display device member in the present disclosure may have a primer layer between the glass substrate and the resin layer.

[0010] The display device member according to the present disclosure may further include a functional layer on the side of the resin layer opposite to the glass substrate, in which case the functional layer may be a hard coat layer.

[0011] The member for a display device according to the present disclosure preferably has a total light transmittance of 80% or more, and a haze of 2.0% or less.

[0012] In the display device member of the present disclosure, the resin layer may contain polyimide or polyamideimide. In this case, the weight average molecular weight of the polyimide is preferably 100,000 or more. The weight average molecular weight of the polyamideimide is preferably 50,000 or more.

[0013] Another embodiment of the present disclosure provides an optical laminate having a glass substrate, a first resin layer, a second resin layer, and a third resin layer in this order, wherein the thickness of the glass substrate is 100 μm or less, the composite elastic modulus of the first resin layer is 5.7 GPa or more, the thickness of the first resin layer is 5 μm or more and 60 μm or less, the second resin layer is an adhesive layer, and the third resin layer is a resin film containing a resin selected from the group consisting of polyester-based resins, polycycloolefin-based resins, acetyl cellulose-based resins, polycarbonate-based resins, and polypropylene-based resins.

[0014] In the optical laminate of the present disclosure, it is preferable that the total thickness of the resin layers disposed on the side of the first resin layer of the glass substrate is 143 μm or less.

[0015] The optical laminate according to the present disclosure may have a functional layer on the side of the third resin layer opposite to the second resin layer, in which case the functional layer may be a hard coat layer.

[0016] The optical laminate in the present disclosure preferably has a total light transmittance of 80% or more, and a haze of 2.0% or less.

[0017] In the optical laminate of the present disclosure, the first resin layer may contain polyimide or polyamideimide. In this case, the weight average molecular weight of the polyimide is preferably 100,000 or more. The weight average molecular weight of the polyamideimide is preferably 50,000 or more.

[0018] Another embodiment of the present disclosure provides a display device including a display panel and the above-described member for a display device or the above-described optical laminate arranged on a viewer side of the display panel.

[0019] The display device in the present disclosure is preferably foldable. Effect of the Invention

[0020] The present disclosure has an effect of providing a display device member and an optical laminate having excellent impact resistance and flexibility, and improved safety. The present disclosure also has an effect of providing a display device member having excellent strength, impact resistance, scratch resistance, and flexibility, and improved safety. [Brief description of the drawings]

[0021] [Figure 1] 1 is a schematic cross-sectional view illustrating a display device member according to the present disclosure. [Diagram 2] 1 is a schematic cross-sectional view illustrating a display device member according to the present disclosure. [Diagram 3] 1 is a schematic cross-sectional view illustrating a display device member according to the present disclosure. [Figure 4] 1 is a schematic cross-sectional view illustrating a display device member according to the present disclosure. [Diagram 5] FIG. 1 is a schematic diagram for explaining a dynamic bending test. [Figure 6]FIG. 1 is a schematic diagram for explaining a static bending test. [Figure 7] 1 is a schematic cross-sectional view illustrating an optical laminate according to the present disclosure. [Figure 8] 1 is a schematic cross-sectional view illustrating an optical laminate according to the present disclosure. [Figure 9] 1 is a schematic cross-sectional view illustrating an optical laminate according to the present disclosure. [Figure 10] 1 is a schematic cross-sectional view illustrating a display device according to the present disclosure. [Figure 11] 1 is a schematic cross-sectional view illustrating a display device according to the present disclosure. [Figure 12] 1 is a graph showing the relationship between the thickness of the resin layer and the evaluation of an impact test (pen drop test) in the resin members for a display device of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The following describes the embodiments of the present disclosure with reference to the drawings. However, the present disclosure can be implemented in many different forms, and should not be interpreted as being limited to the description of the embodiments exemplified below. In addition, the drawings may be schematic in terms of the width, thickness, shape, etc. of each part compared to the actual form in order to make the explanation clearer, but these are merely examples and do not limit the interpretation of the present disclosure. In this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0023] In this specification, when describing a mode in which another component is disposed on a certain component, the term "above" or "below" is used, unless otherwise specified, to include both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween. Also, in this specification, when describing a mode in which another component is disposed on the surface of a certain component, the term "on the surface side" or "on the surface" is used, unless otherwise specified, to include both a case in which another component is disposed directly above or below a certain component so as to be in contact with the component, and a case in which another component is disposed above or below a certain component with another component interposed therebetween.

[0024] In this specification, the term "film" also includes a member called a "sheet."

[0025] Hereinafter, the member for a display device, the optical laminate, and the display device according to the present disclosure will be described in detail.

[0026] A. Display device components In order to solve the above problems, the inventors of the present disclosure have conducted intensive research and found that by using a flexible thin glass substrate and disposing a resin layer on one side of the glass substrate, the cracking of the glass substrate can be suppressed and the impact resistance can be increased, and furthermore, by increasing the thickness of the resin layer, the cracking of the glass substrate can be further suppressed and the impact resistance can be further increased. However, when a display device member having a resin layer disposed on one side of the glass substrate is disposed on the observer side of the display panel of a display device, when the display device member is disposed so that the surface of the resin layer side faces the observer side, it has been found that if the thickness of the resin layer is thick, the hardness of the surface of the display device member on the resin layer side is reduced and the scratch resistance is reduced. Then, the inventors of the present disclosure have conducted further research and found that by setting the composite elastic modulus of the resin layer within a predetermined range, the cracking of the glass substrate can be suppressed even when the thickness of the resin layer is relatively thin in order to increase the surface hardness. That is, it has been found that a display device member excellent in all of strength, impact resistance, scratch resistance and flexibility can be obtained. In addition, it has been found that by using a resin layer having a predetermined property, even if the glass substrate is broken, the glass substrate can be used more safely without exposing fragments or sharp edges. The display device member in the present disclosure is based on such a finding.

[0027] The display device member according to the present disclosure includes a glass substrate having a thickness of 100 μm or less, and a resin layer disposed on one surface side of the glass substrate, the resin layer having a composite elastic modulus of 5.7 GPa or more and a thickness of 5 μm or more and 60 μm or less.

[0028] Fig. 1 is a schematic cross-sectional view showing an example of a member for a display device in the present disclosure. As shown in Fig. 1, the member for a display device 1 has a glass substrate 2 and a resin layer 3 arranged on one surface side of the glass substrate 2. The glass substrate 2 has a predetermined thickness, and the resin layer 3 has a predetermined thickness and a predetermined composite elastic modulus.

[0029] In the present disclosure, since the glass substrate is thin, that is, the thickness is equal to or less than a predetermined value, there is a concern that the glass substrate is easily broken and has low impact resistance, but by disposing a resin layer on one side of the glass substrate, when an impact is applied to the display device member, the resin layer can absorb the impact and suppress the breakage of the glass substrate, thereby improving the impact resistance. Furthermore, even if the glass substrate is broken, the resin layer can suppress the glass from scattering.

[0030] Here, by increasing the thickness of the resin layer, the cracking of the glass substrate can be further suppressed, and the impact resistance can be further improved. However, if the thickness of the resin layer is large, the hardness of the surface of the resin layer side of the display device member decreases, and the scratch resistance is reduced. Therefore, in order to increase the hardness of the surface of the resin layer side of the display device member, it is necessary to make the thickness of the resin layer relatively thin. According to the present disclosure, since the composite elastic modulus of the resin layer is within a predetermined range, even if the thickness of the resin layer is made relatively thin to increase the surface hardness, the cracking of the glass substrate can be suppressed. Therefore, both impact resistance and scratch resistance can be improved.

[0031] The composite elastic modulus of the resin layer is measured by a nanoindentation method (indentation test method) as described later. In addition, a pen drop test is one of the evaluations of the impact resistance of a thin glass substrate, and the impact resistance of a display device member can be evaluated by the pen drop test as described in the examples below. There are various types of elastic modulus other than the composite elastic modulus, but the composite elastic modulus of the resin layer is adopted in the present disclosure. This is because, in the measurement of the composite elastic modulus of the resin layer by the nanoindentation method (indentation test method), the indenter is pressed into the measurement sample, which is similar to the tip of the pen colliding with and pressing into the sample in the pen drop test.

[0032] According to the present disclosure, the composite elastic modulus of the resin layer is equal to or greater than a predetermined value, so that the impact resistance in a pen drop test can be improved.

[0033] In addition, according to the present disclosure, since the thickness of the glass substrate is thin, being equal to or less than a predetermined value, and the thickness of the resin layer is relatively thin, being within a predetermined range, flexibility can be increased, and when the display device member is bent, cracking of the resin layer can be suppressed, and bending resistance can be maintained. Therefore, the display device member in the present disclosure can be bent and can be used for a wide variety of display device members, for example, as a foldable display member.

[0034] According to the present disclosure, the composite elastic modulus of the resin layer is equal to or greater than a predetermined value, so that the restoring force when deformation is applied to the resin layer can be increased. The composite elastic modulus is an index that indicates the resistance to deformation, and the larger the composite elastic modulus of the resin layer, the larger the restoring force when deformation is applied to the resin layer, while the smaller the composite elastic modulus of the resin layer, the smaller the restoring force when deformation is applied to the resin layer tends to be. Therefore, by having the composite elastic modulus of the resin layer be equal to or greater than a predetermined value, the restoring property of the display device member after it has been folded for a long time can be improved. In addition, the restoring property of the display device member after repeated folding can also be improved.

[0035] In this manner, the present disclosure provides a display device member having excellent strength, impact resistance, scratch resistance, and flexibility. Furthermore, even if the glass substrate is broken, the risk of injury to the human body can be reduced, and the display device member can be made highly safe.

[0036] In addition, conventionally, optical films having a resin substrate are known as components arranged on the surface of foldable displays, but in foldable displays using the optical films as the components, there is a problem that folding marks are easily left, image quality is reduced, and the appearance is impaired. In contrast, according to the present disclosure, a display device component using a glass substrate and having a glass substrate is less likely to leave folding marks, and can improve image quality and appearance.

[0037] Hereinafter, each configuration of the member for a display device in the present disclosure will be described.

[0038] 1.Resin layer The resin layer in the present disclosure is a member having a composite elastic modulus of 5.7 GPa or more, a thickness of 5 μm or more and 60 μm or less, and disposed on one side of the glass substrate. The resin layer is a member having impact absorption properties, and also functions as a member for suppressing glass from scattering when the glass substrate is broken. The resin layer has optical transparency, and when the member for a display device in the present disclosure is disposed on the viewer side of the display panel of the display device, the resin layer is disposed on the viewer side of the glass substrate.

[0039] (1) Characteristics of the resin layer The composite elastic modulus of the resin layer is 5.7 GPa or more, preferably 6.0 GPa or more, more preferably 6.5 GPa or more. By the composite elastic modulus of the resin layer being within the above range, even if the thickness of the resin layer is relatively thin in order to increase the surface hardness, the cracking of the glass substrate due to impact can be suppressed, and the impact resistance and scratch resistance can be improved.

[0040] According to the method for measuring the composite elastic modulus described below, the composite elastic modulus of the glass substrate is about 40 GPa, and therefore the composite elastic modulus of the resin layer is, for example, preferably 40 GPa or less, and more preferably 20 GPa or less.

[0041] Here, the composite elastic modulus of the resin layer is defined as the indentation hardness (H IT ) is measured using the contact projection area A p The indentation hardness is calculated using the following formula: "Indentation hardness" is a value determined from a load-displacement curve from loading to unloading of the indenter obtained by hardness measurement using the nanoindentation method. The composite elastic modulus of the resin layer is an elastic modulus including the elastic deformation of the resin layer and the elastic deformation of the indenter.

[0042] Indentation hardness (H IT) is measured on the measurement sample using a "TI950 TriboIndenter" manufactured by BRUKER. Specifically, a block is prepared by embedding a display device member cut to 1 mm x 10 mm in an embedding resin, and a uniform slice having a thickness of 50 nm to 100 nm without holes is cut from this block by a general slice preparation method. An "Ultramicrotome EM UC7" (manufactured by Leica Microsystems) or the like can be used to prepare the slice. The remaining block from which the uniform slice without holes is cut is used as the measurement sample. Next, in the cross section obtained by cutting out the slice in such a measurement sample, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by BRUKER) is pressed vertically into the center of the cross section of the resin layer for 10 seconds to a maximum pressing load of 25 μN under the following measurement conditions. Here, in order to avoid the influence of the glass substrate and the side edges of the resin layer, the Berkovich indenter is pressed into a portion of the resin layer that is 500 nm away from the interface between the glass substrate and the resin layer toward the center of the resin layer, and 500 nm away from each of the two ends of the resin layer toward the center of the resin layer. If an optional layer such as a hard coat layer is present on the surface of the resin layer opposite to the surface on the glass substrate side, the Berkovich indenter is pressed into a portion of the resin layer that is 500 nm away from the interface between the optional layer and the resin layer toward the center of the resin layer. After that, the residual stress is relaxed by holding it constant, and then the load is removed over 10 seconds to measure the maximum load after relaxation, and the maximum load P max (μN) and contact projection area A p (nm 2 ) and P max / A p The indentation hardness (H IT The above contact projected area is the contact projected area corrected for the indenter tip curvature by the Oliver-Pharr method using a standard sample of fused quartz (5-0098 manufactured by BRUKER). Indentation hardness (H IT) is the arithmetic average of values ​​obtained by measuring at 10 points. If any of the measured values ​​deviate from the arithmetic average by more than ±20%, those measured values ​​shall be excluded and remeasured. Whether or not any of the measured values ​​deviate from the arithmetic average by more than ±20% shall be judged by whether the value (%) calculated by (AB) / B x 100, where A is the measured value and B is the arithmetic average, is more than ±20%. Indentation hardness (H IT ) can be adjusted by the type of resin contained in the resin layer described later.

[0043] (Measurement conditions) ·Loading speed: 2.5μN / sec ·Holding time: 5 seconds ·Load unloading speed: 2.5μN / sec ·Measurement temperature: 25℃

[0044] Composite elastic modulus of resin layer E r is the contact projection area A obtained during the measurement of indentation hardness according to the following formula (1). p The composite elastic modulus is calculated by measuring the indentation hardness at 10 points, calculating the composite elastic modulus each time, and taking the arithmetic average of the composite elastic moduli obtained at the 10 points.

[0045]

number

[0046] (In the above formula (1), A p is the contact projected area, and E r is the composite elastic modulus of the resin layer, and S is the contact stiffness.)

[0047] (2) Resin layer composition The thickness of the resin layer is 5 μm to 60 μm, preferably 10 μm to 50 μm, more preferably 15 μm to 40 μm. By making the thickness of the resin layer relatively thin within the above range, flexibility can be increased, cracking of the resin layer can be suppressed when the display device member is bent, and bending resistance can be maintained.

[0048] Here, the thickness of the resin layer can be the average value of thicknesses at any 10 points obtained by measuring a cross section in the thickness direction of the member for a display device observed with a transmission electron microscope (TEM), a scanning electron microscope (SEM), or a scanning transmission electron microscope (STEM). The thicknesses of other layers in the member for a display device can be measured in the same manner.

[0049] The resin layer may be disposed on only one surface of the glass substrate, or may be disposed so as to cover two or more surfaces of the glass substrate. In particular, by disposing the resin layer so as to cover the end surface (side surface) of the glass substrate, it is possible to reduce impact from the side surface of the glass substrate and suppress the occurrence of scratches, thereby suppressing breakage of the glass.

[0050] (3) Resin layer material (a) Resin The resin contained in the resin layer is not particularly limited as long as it satisfies the above-mentioned composite elastic modulus and has optical transparency, and examples thereof include polyimide, polyamideimide, acrylic resin, epoxy resin, urethane resin, triacetyl cellulose (TAC), etc.

[0051] Hereinafter, polyimide and polyamideimide will be taken as examples for explanation.

[0052] (i) Polyimide Polyimide is obtained by reacting a tetracarboxylic acid component with a diamine component. It is preferable to obtain a polyamic acid by polymerization of the tetracarboxylic acid component and the diamine component, and then imidize the polyamic acid. The imidization may be performed by chemical imidization, thermal imidization, or a combination of chemical imidization and thermal imidization.

[0053] The polyimide is not particularly limited as long as it satisfies the above-mentioned composite elastic modulus and has optical transparency, but for example, it is preferable that the polyimide contains 10 mol % or more and 100 mol % or less of a constitutional unit represented by the following general formula (1) and (100-x) mol % (where x is the mol % of the constitutional unit represented by the above general formula (1)) of a constitutional unit represented by the following general formula (2) and has a weight average molecular weight of 100,000 or more. This is because the polyimide has a tetracarboxylic acid residue of a specific structure containing a parabiphenylene group with a twisted dihedral angle via an ester bond in the main chain, and a diamine residue having an aromatic ring or an aliphatic ring, and has a specific weight average molecular weight, which makes it easy to achieve a good balance between the composite elastic modulus and bending resistance.

[0054] [ka]

[0055] (In general formulas (1) and (2), R 1 ~R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms; R 1 and R 2 At least one of, and R 3 and R 4 At least one of A represents an alkyl group having 1 to 6 carbon atoms, A represents a tetravalent group which is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, and B represents a divalent group which is a diamine residue having an aromatic ring or an aliphatic ring.

[0056] Here, the 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 an acid dianhydride structure from a tetracarboxylic dianhydride, and the diamine residue refers to a residue obtained by removing two amino groups from a diamine.

[0057] In the general formula (1), R 1 and R 2 At least one of, and R 3 and R 4 At least one of R represents an alkyl group having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms may be a straight-chain or branched-chain alkyl group, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, and an n-hexyl group. From the viewpoint of solvent solubility, an alkyl group having 1 to 4 carbon atoms is preferable, an alkyl group having 1 to 2 carbon atoms is more preferable, and a methyl group is more preferable. Among them, from the viewpoint of solvent solubility, R 1 and R 2 , and R 3 and R 4 Preferably, represents a methyl group.

[0058] In general formula (1), B represents a divalent group that is a diamine residue having an aromatic ring or an aliphatic ring. The diamine residue having an aromatic ring or an aliphatic ring can be a residue obtained by removing two amino groups from a diamine having an aromatic ring or a diamine having an aliphatic ring.

[0059] Specific examples of diamines having an aromatic ring and diamines having an aliphatic ring include those described in, for example, JP-A-2019-132930 and JP-A-2019-1989. These may be used alone or in combination of two or more.

[0060] In the above general formula (2), A represents a tetravalent group which is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring, and B represents a divalent group which is a diamine residue having an aromatic ring or an aliphatic ring. Since B in the above general formula (2) may be the same as B in the above general formula (1), the explanation here is omitted. B in the above general formula (1) and B in the above general formula (2) may be the same or different.

[0061] The tetracarboxylic acid residue in A of the above general formula (2) can be a residue obtained by removing an acid dianhydride structure from a tetracarboxylic acid dianhydride having an aromatic ring, or a residue obtained by removing an acid dianhydride structure from a tetracarboxylic acid dianhydride having an aliphatic ring.

[0062] Specific examples of tetracarboxylic dianhydrides having an aromatic ring and tetracarboxylic dianhydrides having an aliphatic ring include those described in, for example, JP-A-2019-132930 and JP-A-2019-1989. These may be used alone or in combination of two or more.

[0063] The polyimide preferably contains 10 mol % or more and 100 mol % or less of the constitutional unit represented by the above general formula (1). From the viewpoint of solubility in a solvent, the polyimide more preferably contains 15 mol % or more of the constitutional unit represented by the above general formula (1), further preferably contains 25 mol % or more, and particularly preferably contains 50 mol % or more.

[0064] On the other hand, from the viewpoint of improving surface hardness and light transmittance, a copolymerization component may be contained, and the polyimide may contain 95 mol % or less, 90 mol % or less, or 80 mol % or less of the structural unit represented by the above general formula (1).

[0065] Moreover, the polyimide preferably contains the structural unit represented by the above general formula (2) in an amount of (100-x) mol % (where x is the mol % of the structural unit represented by the above general formula (1)). From the viewpoint of solubility in a solvent, the polyimide more preferably contains 85 mol % or less of the structural unit represented by the above general formula (2), even more preferably contains 75 mol % or less, and particularly preferably contains 50 mol % or less.

[0066] In addition, when the polyimide contains 100 mol % of the constitutional unit represented by the above general formula (1), the constitutional unit represented by the above general formula (2) is 0 mol %, that is, it is not contained. The constitutional unit represented by the above general formula (2) may be 0 mol %, but may be contained as a copolymerization component from the viewpoint of improving surface hardness and light transmittance, and the polyimide may contain 5 mol % or more, 10 mol % or more, or 20 mol % or more of the constitutional unit represented by the above general formula (2).

[0067] From the viewpoint of improving light transmittance and surface hardness, at least one of the tetravalent group of the tetracarboxylic acid residue of A and the divalent group of the diamine residue of B preferably contains an aromatic ring and at least one selected from the group consisting of (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are linked together by an alkylene group that may be substituted with a sulfonyl group or fluorine. When the polyimide contains at least one selected from a tetracarboxylic acid residue having an aromatic ring and a diamine residue having an aromatic ring, the molecular skeleton becomes rigid, the orientation is enhanced, and the surface hardness is improved, but the rigid aromatic ring skeleton tends to have an absorption wavelength that extends to a long wavelength, and the transmittance in the visible light region tends to decrease. On the other hand, when the polyimide contains (i) a fluorine atom, the electronic state in the polyimide skeleton can be made difficult to charge transfer, and therefore the light transmittance is improved. In addition, when the polyimide contains (ii) an aliphatic ring, the conjugation of π electrons in the polyimide skeleton can be broken to inhibit the movement of charges in the skeleton, thereby improving the light transmittance, and in addition, when the polyimide contains (iii) a structure in which aromatic rings are linked together by a sulfonyl group or an alkylene group which may be substituted with fluorine, the conjugation of π electrons in the polyimide skeleton can be broken to inhibit the movement of charges in the skeleton, thereby improving the light transmittance.

[0068] In particular, from the viewpoints of improving light transmittance and surface hardness, it is preferable that at least one of the tetravalent group which is the tetracarboxylic acid residue of A and the divalent group which is the diamine residue of B contains an aromatic ring and a fluorine atom, and it is preferable that the divalent group which is the diamine residue of B contains an aromatic ring and a fluorine atom.

[0069] In terms of light transmittance, bending resistance and surface hardness, the polyimide is preferably selected from the group consisting of a trans-cyclohexanediamine residue, a trans-1,4-bismethylenecyclohexanediamine residue, a 4,4'-diaminodiphenylsulfone residue, a 3,4'-diaminodiphenylsulfone residue, a 2,2-bis(4-aminophenyl)propane residue, a 3,3'-bis(trifluoromethyl)-4,4'-[ (1,1,1,3,3,3-hexafluoropropane-2,2-diyl)bis(4,1-phenyleneoxy)]dianiline residue, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane residue, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane residue, and at least one divalent group selected from the group consisting of divalent groups represented by the following general formula (3) is preferred. In particular, from the viewpoint of compatibility between light transmittance and surface hardness, at least one divalent group selected from the group consisting of 4,4'-diaminodiphenylsulfone residue, 3,4'-diaminodiphenylsulfone residue, 2,2-bis(4-aminophenyl)propane residue, and divalent groups represented by the following general formula (3) is preferred, and at least one divalent group selected from the group consisting of divalent groups represented by the following general formula (3) is more preferred. The divalent group represented by the following general formula (3) is R 5 and R 6 More preferably, R is a perfluoroalkyl group, and among these, a perfluoroalkyl group having 1 to 3 carbon atoms is preferred, and a trifluoromethyl group or a perfluoroethyl group is more preferred. 5 and R 6 The alkyl group in is preferably an alkyl group having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group.

[0070] [ka]

[0071] (In the general formula (3), R5 and R 6 each independently represents a hydrogen atom, an alkyl group, or a perfluoroalkyl group.

[0072] In terms of light transmittance, bending resistance and surface hardness, the polyimide is particularly preferably one in which the tetracarboxylic acid residue having an aromatic ring or an aliphatic ring in A in the above general formula (2) is a cyclohexanetetracarboxylic acid dianhydride residue, a cyclopentanetetracarboxylic acid dianhydride residue, a dicyclohexane-3,4,3',4'-tetracarboxylic acid dianhydride residue, a cyclobutanetetracarboxylic acid dianhydride residue, a pyromellitic acid dianhydride residue, a 3,3',4,4'-biphenyltetracarboxylic acid dianhydride residue, a 2,2',3,3' ... and at least one tetravalent group selected from the group consisting of 2,3,3',4'-biphenyltetracarboxylic dianhydride residue, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride residue, 4,4'-oxydiphthalic anhydride residue, and 3,4'-oxydiphthalic anhydride residue.

[0073] In A in the above general formula (2), the total content of these suitable residues is preferably 50 mol % or more, more preferably 70 mol % or more, and even more preferably 90 mol % or more.

[0074] In terms of improving surface hardness, A in the above general formula (2) preferably contains at least one tetracarboxylic acid residue group (Group A) suitable for improving rigidity, such as a pyromellitic dianhydride residue, a 3,3',4,4'-biphenyltetracarboxylic dianhydride residue, and a 2,2',3,3'-biphenyltetracarboxylic dianhydride residue. In addition, from the viewpoint of improving light transmittance, A in the above general formula (2) preferably includes at least one tetracarboxylic acid residue group (Group B) suitable for improving light transmittance, such as cyclohexanetetracarboxylic dianhydride residue, cyclopentanetetracarboxylic dianhydride residue, dicyclohexane-3,4,3',4'-tetracarboxylic dianhydride residue, cyclobutanetetracarboxylic dianhydride residue, 2,3,3',4'-biphenyltetracarboxylic dianhydride residue, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residue, 3,3'-(hexafluoroisopropylidene)diphthalic anhydride residue, 4,4'-oxydiphthalic anhydride residue, and 3,4'-oxydiphthalic anhydride residue. Group A and Group B may be used in combination.

[0075] When Group A and Group B are mixed, the content ratio of the tetracarboxylic acid residue group suitable for improving the above-mentioned rigidity (Group A) to the tetracarboxylic acid residue group suitable for improving light transmittance (Group B) is preferably 0.05 mol or more and 9 mol or less, more preferably 0.1 mol or more and 5 mol or less, and even more preferably 0.3 mol or more and 4 mol or less, of the tetracarboxylic acid residue group suitable for improving the above-mentioned rigidity (Group A) per 1 mol of the tetracarboxylic acid residue group suitable for improving light transmittance (Group B).

[0076] Among these, from the viewpoint of improving surface hardness and light transmittance, it is preferable to use at least one of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residues and 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residues, each of which contains a fluorine atom, as the group B.

[0077] The content ratio of each repeating unit in the polyimide and the content ratio (mol%) of each tetracarboxylic acid residue and each diamine residue can be determined from the molecular weight of the charged material during the production of the polyimide. The content ratio (mol%) of each tetracarboxylic acid residue and each diamine residue in the polyimide can be determined by using high performance liquid chromatography, gas chromatography mass spectrometry, NMR, elemental analysis, XPS / ESCA and TOF-SIMS for the decomposition products of the polyimide obtained in the same manner as above.

[0078] The polyimide preferably has a weight average molecular weight of 100,000 or more as calculated by polystyrene equivalent in gel permeation chromatography from the viewpoint of good bending resistance. From the viewpoint of bending resistance, the weight average molecular weight may be 120,000 or more, 140,000 or more, or 160,000 or more. On the other hand, from the viewpoint of less occurrence of bubble defects, the weight average molecular weight is preferably 270,000 or less. Furthermore, from the viewpoint of solubility, the weight average molecular weight may be 250,000 or less, 230,000 or less, or 210,000 or less.

[0079] The weight-average molecular weight of polyimide can be measured by gel permeation chromatography (GPC). Specifically, polyimide is dissolved in N-methylpyrrolidone (NMP) at a concentration of 0.1% by mass, and a 30 mmol% LiBr-NMP solution with a water content of 500 ppm or less is used as the developing solvent. Measurements are performed using a Tosoh GPC device (HLC-8120, column used: SHODEX GPC LF-804) with a sample injection volume 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 with the same concentration as the sample.

[0080] (ii) Polyamide-imide The polyamideimide is not particularly limited as long as it satisfies the above-mentioned composite elastic modulus and has optical transparency. For example, it is preferable that the polyamideimide contains a polyimide constituent unit including a constituent unit represented by the following formula (4) and a polyamide constituent unit including a constituent unit represented by the following formula (5).

[0081] [ka]

[0082] (In formula (5), X represents a divalent group which is a dicarboxylic acid residue having an aromatic ring.)

[0083] By containing a polyimide structural unit including a structural unit represented by the above formula (4) and a polyamide structural unit including a structural unit represented by the above formula (5), a resin layer having sufficient transparency and high composite modulus and bending resistance can be obtained. In the above polyamideimide, a polyamide structural unit that contains a dicarboxylic acid residue having an aromatic ring and promotes intermolecular interaction by hydrogen bond is introduced into a polyimide structural unit having a tetracarboxylic acid residue of a specific structure including a parabiphenylene group with a twisted dihedral angle via an ester bond in the main chain, and promotes intermolecular interaction by hydrogen bond. By imparting a twist of the aromatic ring to the main chain structure of the polymer, intermolecular energy transition occurring in a π-conjugated polymer can be suppressed, and sufficient transparency can be achieved, while by introducing an amide bond site and an ester bond site into the polyimide structural unit, the intermolecular force due to hydrogen bond formation can be increased, and it is presumed that a resin layer having high composite modulus and bending resistance can be obtained.

[0084] The polyamideimide also has good flex resistance, particularly in a high-humidity environment, because the amide bond site and the ester bond site in the polyimide structural unit form hydrogen bonds to suppress hydrogen bonding with moisture even in a high-humidity environment. This is presumably why deterioration of flex resistance in a high-humidity environment is suppressed, resulting in good flex resistance.

[0085] Furthermore, since the polyamideimide contains the constitutional unit represented by the formula (4), it has good solubility in a solvent even though it contains the constitutional unit represented by the formula (4).

[0086] (Polyimide building block) The polyimide structural unit is a structural unit obtained by reacting a tetracarboxylic acid component with a diamine component, and examples thereof include the structural unit represented by the above general formula (2) described in the section on polyimides.

[0087] The constitutional unit represented by the above formula (4) can be obtained by reacting a tetracarboxylic dianhydride represented by the following formula (4-1) with 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl.

[0088] [ka]

[0089] The content ratio of the structural unit represented by the above formula (4) to the total polyimide structural units in the polyamideimide may be 100 mol%. In addition, the polyimide structural unit may contain other polyimide structural units different from the structural unit represented by the above formula (4). The content ratio of the structural unit represented by the above formula (4) to the total polyimide structural units in the polyamideimide is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and preferably 100 mol% or less, and may be 90 mol% or less. If the content ratio of the structural unit represented by the above formula (4) is within the above range, it is possible to have a high composite modulus and bending resistance while having sufficient transparency. In order to improve the balance between transparency, composite modulus and bending resistance, or to add further properties, it may contain other polyimide structural units different from the structural unit represented by the above formula (4).

[0090] The content ratio of the tetracarboxylic dianhydride residue represented by the above formula (4-1) relative to the total of the tetracarboxylic acid residues contained in the polyimide structural unit in the polyamideimide is preferably 50 mol% or more, more preferably 60 mol% or more, even more preferably 70 mol% or more, and preferably 100 mol% or less, and may be 90 mol% or less. If the content ratio of the tetracarboxylic dianhydride residue represented by the above formula (4-1) is within the above range, it can have high composite modulus and bending resistance while having sufficient transparency. In order to improve the balance between transparency, composite modulus and bending resistance, or to add further properties, it may contain other tetracarboxylic dianhydride residues different from the tetracarboxylic dianhydride residue represented by the above formula (4-1).

[0091] Examples of other polyimide structural units that may be included in the polyimide structural unit include, among the structural units represented by the above general formula (2), polyimide structural units different from the structural unit represented by the above formula (4). In the structural units represented by the above general formula (2), A and B may be the same or different in each structural unit. That is, in the structural unit represented by the above general formula (2), A and B may each be independently one type or two or more types.

[0092] In the constitutional unit represented by the above general formula (2), A represents a tetravalent group which is a tetracarboxylic acid residue having an aromatic ring or an aliphatic ring. Examples of A include tetravalent groups represented by the following formulae (a1) to (a7) and tetravalent groups in which some or all of the hydrogen atoms in the tetravalent groups represented by these formulae are substituted with one or more substituents selected from the group consisting of a fluoro group, a methyl group, a methoxy group, a trifluoromethyl group, and a trifluoromethoxy group.

[0093] [ka]

[0094] (In formulas (a1) to (a7), * represents a bond, and Q a is a single bond, -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CO-, -SO2-, -Ph-, -Ph-Q a2 -Ph-, -Q a2 -Ph-Q a2 -, -Q a2 -Ph-Ph-Q a2 -, -Q a2 -Ph-Q a2 -Ph-Q a2 - or a fluorene group. Ph represents a phenylene group, and Q a2 represents -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CO-, or -SO2-.

[0095] Q aThe bonding position of each ring may be, independently, the ortho or meta position with respect to one of the two carboxy groups bonded to each ring. a2 The bonding positions of the rings of the formula (I) to the phenylene group are preferably meta or para, and more preferably para, relative to the phenylene group.

[0096] In the constitutional unit represented by the above general formula (2), among the tetravalent groups represented by the above formulae (a1) to (a7), in the case of structures containing aromatic rings as in the above formulae (a1) to (a3), the tetravalent groups represented by the above formulae (a1) and (a2) are preferred from the viewpoint of imparting transparency and solubility in solvents. Furthermore, those having a bendable structure between the aromatic rings are preferred, and Q in the above formula (a2) is a Examples include -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -SO2-, -Q a2 -Ph-Q a2 -(Q a2 represents -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CO-, or -SO2-.) is preferable. Furthermore, since the transparency is improved when a fluorine atom is contained, Q a As examples, -C(CF3)2-, -Q a2 -Ph-Q a2 -(Q a2 is preferably -C(CF3)2-, and from the viewpoint of composite elastic modulus, Q a Among them, -C(CF3)2- is more preferable.

[0097] In the constitutional unit represented by the above general formula (2), among the tetravalent groups represented by the above formulae (a1) to (a7), A preferably contains an aliphatic ring as in the above formulae (a4) to (a7) because it has an aliphatic structure and is therefore excellent in transparency and solubility. Among these, tetravalent groups represented by structures (a4), (a5), or (a6) having fewer bending sites are preferred because they provide a good composite elastic modulus, and among these, the tetravalent group represented by (a4) is preferred.

[0098] In the constitutional unit represented by the above general formula (2), B represents a divalent group which is a diamine residue having an aromatic ring or an aliphatic ring. Examples of B include divalent groups represented by the following formulae (b1) to (b6) and divalent groups in which some or all of the hydrogen atoms in the divalent groups represented by these formulae are substituted with one or more substituents selected from the group consisting of a fluoro group, a methyl group, a methoxy group, a trifluoromethyl group, and a trifluoromethoxy group.

[0099] [ka]

[0100] (In formulas (b1) to (b6), * represents a bond, and Q b is a single bond, -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CO-, -SO2-, -Ph-, -Ph-Q b2 -Ph-, -Q b2 -Ph-Q b2 -, -Q b2 -Ph-Ph-Q b2 -, -Q b2 -Ph-Q b2 -Ph-Q b2 - or a fluorene group. Ph represents a phenylene group, and Q b2 represents -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, -CO-, or -SO2-.

[0101] Q b The bonding positions of Q to each ring are preferably meta or para relative to the amino group bonded to each ring, and more preferably para. b2 The bonding positions of the rings of the formula (I) to the phenylene group are preferably meta or para, and more preferably para, relative to the phenylene group.

[0102] In the constitutional unit represented by the above general formula (2), from the viewpoints of maintaining transparency and complex elastic modulus, among the divalent groups represented by the above formulae (b1) to (b6), B preferably has a molecular structure in which the π-conjugation between phenylene groups is broken while having a phenylene skeleton, and more preferably further contains fluorine.

[0103] In the divalent group represented by the above formula (b2), Q b is preferably -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2- or -SO2-, and more preferably -C(CF3)2- or -SO2-.

[0104] In the constitutional unit represented by the above general formula (2), B is preferably at least one divalent group selected from the group consisting of divalent groups represented by the above general formula (3) from the viewpoints of transparency and maintaining the composite elastic modulus. As the divalent group represented by the above general formula (3), R 5 and R 6 is more preferably a methyl group or a trifluoromethyl group, and from the viewpoint of transparency, is even more preferably a trifluoromethyl group.

[0105] Moreover, the polyimide constitutional unit other than the constitutional unit represented by the above formula (4) may be a constitutional unit represented by the following formula (6).

[0106] [ka]

[0107] (In formula (6), B' represents a divalent group which is a diamine residue having an aromatic ring or an aliphatic ring, and is different from a 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl residue.)

[0108] In the above formula (6), B' represents a diamine residue having an aromatic ring or an aliphatic ring, which is different from the 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl residue, and may be the same as B in the above general formula (5).

[0109] When the polyimide structural unit contains other polyimide structural units, it is preferable to contain a structural unit represented by the following formula (7), a structural unit represented by the following formula (8), or a combination thereof. When the polyimide structural unit contains a structural unit represented by the following formula (7), a structural unit represented by the following formula (8), or a combination thereof, it is preferable from the viewpoint of improving transparency and increasing solubility in a solvent. When the polyimide structural unit contains a structural unit represented by the following formula (7), it is more preferable from the viewpoint of improving transparency while maintaining a high composite elastic modulus.

[0110] [ka]

[0111] The structural unit represented by the above formula (7) can be obtained by reacting cyclobutanetetracarboxylic dianhydride with 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl. The structural unit represented by the above formula (8) can be obtained by reacting 4,4'-(hexafluoroisopropylidene)diphthalic anhydride with 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl.

[0112] The total content of other polyimide structural units different from the structural unit represented by the above formula (4) relative to the total polyimide structural units in the polyamideimide may be 0 mol%, but when contained, it is preferably 5 mol% or more, and may be 10 mol% or more, and is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less. If the total content of the other polyimide structural units is within the above range, high transparency can be imparted and the composite elastic modulus becomes good.

[0113] Among them, when the polyamideimide contains the structural unit represented by the formula (7), the structural unit represented by the formula (8), or a combination thereof, the total content ratio of the structural unit represented by the formula (7) and the structural unit represented by the formula (8) relative to the total polyimide structural unit in the polyamideimide is preferably 5 mol% or more, and may be 10 mol% or more, and is preferably 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less. If the total content ratio of the structural unit represented by the formula (7) and the structural unit represented by the formula (8) is within the above range, high transparency can be imparted and the composite elastic modulus becomes good.

[0114] (Polyamide structural unit) The polyamide constituent unit is a constituent unit obtained by reacting a dicarboxylic acid component with a diamine component, and an example of the polyamide constituent unit is a constituent unit represented by the following general formula (9).

[0115] [ka]

[0116] (In general formula (9), X represents a divalent group which is a dicarboxylic acid residue having an aromatic ring, and B represents a divalent group which is a diamine residue having an aromatic ring or an aliphatic ring.)

[0117] Here, the dicarboxylic acid residue refers to a residue obtained by removing two carboxyl groups from a dicarboxylic acid, and has the same structure as a residue obtained by removing two carboxylic acid chloride groups from a dicarboxylic acid chloride, and the diamine residue refers to a residue obtained by removing two amino groups from a diamine.

[0118] The polyamide structural unit in the polyamideimide contains, as an essential component, the structural unit represented by the above formula (5). The polyamide structural unit contains one or more types of structural units represented by the above formula (5).

[0119] The structural unit represented by the above formula (5) can be obtained by reacting a dicarboxylic acid component having an aromatic ring with 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl. The dicarboxylic acid component can be a dicarboxylic acid or a dicarboxylic acid chloride, and it is preferable to use a dicarboxylic acid chloride from the viewpoint of reactivity.

[0120] In the constitutional unit represented by the formula (5), X in the formula (5) is preferably at least one selected from the group consisting of structures represented by the following formulas (x1) to (x3). A resin layer having sufficient transparency and high composite elastic modulus can be obtained. In addition, not only the 1,4-phenylene group represented by the following formula (x1) but also a 1,3-phenylene group may be used.

[0121] [ka]

[0122] (In formula (x3), L represents -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, or -CO-, and * represents a bond.)

[0123] In the structure of X in the above formula (5), among the structures represented by the above formulas (x1) to (x3), the structure represented by the above formula (x1) or formula (x2) is more preferable, and the structure represented by the above formula (x2) is even more preferable, from the viewpoints of improving the high composite elastic modulus and the bending resistance.

[0124] The content ratio of the structural unit represented by the above formula (5) to the total polyamide structural units in the polyamideimide may be 100 mol%. In addition, the polyamide structural units may further contain other polyamide structural units different from the structural unit represented by the above formula (5). The content ratio of the structural unit represented by the above formula (5) to the total polyamide structural units in the polyamideimide is preferably 80 mol% or more, more preferably 85 mol% or more, even more preferably 90 mol% or more, and is preferably 100 mol% or less, and may be 95 mol% or less. If the content ratio of the structural unit represented by the above formula (5) is within the above range, the balance between transparency and composite elastic modulus is good.

[0125] From the viewpoint of the balance between transparency and composite elastic modulus, the total content of X in the above formula (5), which is one or more types selected from the group consisting of structures represented by the above formulas (x1) to (x3), relative to the total content of structural units represented by the above formula (5) in the polyamideimide may be 100 mol%, is preferably 80 mol% or more and 100 mol% or less, further preferably 90 mol% or more and 100 mol% or less, and further preferably 95 mol% or more and 100 mol% or less.

[0126] The polyamide structural unit may contain other polyamide structural units different from the structural unit represented by the above formula (5), for example, among the structural units represented by the above general formula (9), polyamide structural units different from the structural unit represented by the above formula (5) may be mentioned. In the structural unit represented by the above general formula (9), X and B may be the same or different in each structural unit. That is, in the structural unit represented by the above general formula (9), X and B may each be independently one type or two or more types. In the above general formula (9), X may be the same as X in the structural unit represented by the above formula (5), and B may be the same as B in the structural unit represented by the above general formula (5).

[0127] The other polyamide structural unit that may be contained in the polyamide structural unit and is different from the structural unit represented by the above formula (5) is, from the viewpoint of transparency, a structural unit represented by the above general formula (9), in which X is at least one selected from the group consisting of the structures represented by the above formulas (x1) to (x3), and B is a divalent group represented by the above formula (b2), b is -O-, -S-, -CH2-, -CH(CH3)-, -C(CH3)2-, -C(CF3)2-, or -SO2-, or in the divalent group represented by the general formula (3), R 5 and R 6 is preferably a hydrogen atom or a methyl group, and in the divalent group represented by the above formula (b2), Q b is -C(CF3)2- or -SO2-, or in the divalent group represented by the general formula (3), R 5 and R 6 is more preferably a methyl group, and in the divalent group represented by the above formula (b2), Q b is even more preferably -C(CF3)2-.

[0128] (Polyamide-imide) The content of the polyamide structural unit containing the structural unit represented by the above formula (5) is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, even more preferably 50 mol% or more, and preferably 80 mol% or less, even more preferably 70 mol% or less, and even more preferably 60 mol% or less, based on the total of the polyimide structural unit containing the structural unit represented by the above formula (4) and the polyamide structural unit containing the structural unit represented by the above formula (5). If the content of the polyamide structural unit containing the structural unit represented by the above formula (5) is within the above range, the composite elastic modulus and bending resistance at room temperature of the resin layer are easily improved, and the solubility of the polyamideimide in a solvent and the bending resistance under high temperature and high humidity are easily improved.

[0129] The content of the dicarboxylic acid residue X having an aromatic ring in the above formula (5) is preferably 10 mol% or more, more preferably 30 mol% or more, even more preferably 40 mol% or more, even more preferably 50 mol% or more, and preferably 80 mol% or less, even more preferably 70 mol% or less, and even more preferably 60 mol% or less, based on the total of the tetracarboxylic acid residue and the dicarboxylic acid residue in the polyamideimide resin. If the content of the dicarboxylic acid residue X having an aromatic ring in the above formula (5) is within the above range, the composite elastic modulus of the resin layer and the bending resistance at room temperature are likely to be improved, and the solubility of the polyamideimide in a solvent and the bending resistance under high temperature and high humidity are likely to be improved.

[0130] The polyamideimide may have a structure different from the polyimide structural unit and the polyamide structural unit in part. The polyamideimide preferably has a polyimide structural unit containing a structural unit represented by the formula (4) and a polyamide structural unit containing a structural unit represented by the formula (5) in total of 95% or more, more preferably 98% or more, and even more preferably 100% of all structural units of the polyamideimide.

[0131] Examples of structures different from the polyimide constituent unit and the polyamide constituent unit include a constituent unit in which a tetracarboxylic acid component is not completely imidized and has a polyamic acid structure in part, and a polyamideimide constituent unit containing a tricarboxylic acid residue such as trimellitic anhydride.

[0132] The content (mol%) of each structural unit and each residue in the polyamideimide is: 1It can be measured using H-NMR, and can also be determined from the charge ratio of raw materials when producing polyamideimide. The structure of polyamideimide can be determined using NMR, various mass analyses, etc. The structure and content ratio of each residue in polyamideimide can be determined, for example, by decomposing polyamideimide with an alkaline aqueous solution or supercritical methanol, and using high performance liquid chromatography, gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA, and TOF-SIMS for the decomposition product obtained.

[0133] The weight average molecular weight of the polyamideimide is preferably 50,000 or more, more preferably 100,000 or more, even more preferably 150,000 or more, and preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 300,000 or less. If the weight average molecular weight of the polyamideimide resin is within the above range, defects in appearance such as cracks and whitening are unlikely to occur after baking, a resin layer with good transparency is easily obtained, and high viscosity is suppressed during synthesis, varnish preparation, and resin layer formation, making it easy to form a resin layer.

[0134] The method for measuring the weight average molecular weight of the polyamideimide can be the same as the method for measuring the weight average molecular weight of the polyimide described above.

[0135] (b) Ultraviolet absorber The resin layer may contain an ultraviolet absorbing agent. The deterioration of the resin layer due to ultraviolet rays can be suppressed. In particular, when the resin layer contains polyimide, the color change over time of the resin layer containing polyimide can be suppressed. In addition, in a display device including a member for a display device, the deterioration of a member arranged on the display panel side of the member for a display device, such as a polarizer, due to ultraviolet rays can be suppressed.

[0136] Examples of the ultraviolet absorbing agent contained in the resin layer include triazine-based ultraviolet absorbing agents, benzophenone-based ultraviolet absorbing agents such as hydroxybenzophenone-based ultraviolet absorbing agents, and benzotriazole-based ultraviolet absorbing agents.

[0137] Specific examples of triazine-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers such as hydroxybenzophenone-based ultraviolet absorbers, and benzotriazole-based ultraviolet absorbers include those described in JP-A-2019-132930.

[0138] As the ultraviolet absorbing agent, among others, a triazine-based ultraviolet absorbing agent, a hydroxybenzophenone-based ultraviolet absorbing agent, and a benzotriazole-based ultraviolet absorbing agent are preferably used.

[0139] In addition, the ultraviolet absorber is preferably a polymer or oligomer. This is because it is possible to suppress bleeding out of the ultraviolet absorber when the display device member is repeatedly bent. Examples of such ultraviolet absorbers include polymers or oligomers having a triazine skeleton, a benzophenone skeleton, or a benzotriazole skeleton, and specifically, it is preferable that the ultraviolet absorber is a thermal copolymerization of a (meth)acrylate having a benzotriazole skeleton or a benzophenone skeleton and methyl methacrylate (MMA) at any ratio.

[0140] The content of the ultraviolet absorbing agent in the resin layer is not particularly limited, but is preferably 1% by mass or more and 6% by mass or less, and more preferably 2% by mass or more and 5% by mass or less. If the content of the ultraviolet absorbing agent is too small, the effect of the ultraviolet absorbing agent may not be sufficiently obtained. If the content of the ultraviolet absorbing agent is too large, the resin layer may be significantly colored or the strength of the resin layer may be reduced.

[0141] (c) Other additives The resin layer may further contain additives as necessary, such as inorganic particles, silica filler for facilitating winding, surfactants for improving film-forming properties and defoaming properties, and adhesion improvers.

[0142] (4) Method for forming resin layer The resin layer may be formed, for example, by applying a resin composition onto a glass substrate. The application method is not particularly limited as long as it can be applied to a desired thickness, and may be, for example, a general application method such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, or screen printing. A transfer method may also be used as the resin layer.

[0143] Hereinafter, an example will be described in which the resin layer contains polyimide or polyamideimide.

[0144] (i) Method for forming a resin layer containing polyimide Examples of methods for forming a resin layer containing polyimide include a method of applying a polyimide varnish containing polyimide and an organic solvent onto a glass substrate and drying it, and a method of applying a polyimide precursor composition containing a polyimide precursor (polyamic acid) and an organic solvent onto a glass substrate, and then imidizing the polyimide precursor by heat treatment or chemical treatment. The former method can ease the heating conditions of the film formation process. On the other hand, the latter method can increase the options for the chemical structure of polyimide, since there is no restriction on the solubility of polyimide.

[0145] Among these, the following production method is preferred because it is less likely to cause bubble defects and makes it easier to obtain a resin layer with good thickness uniformity.

[0146] The method for forming a polyimide-containing resin layer preferably includes the steps of: preparing a polyimide varnish containing polyimide and an organic solvent, the polyimide content in the polyimide varnish being 6% by mass or more and 15% by mass or less, and having a viscosity at 25°C of 1,000 cps or more and 50,000 cps or less; applying the polyimide varnish onto a glass substrate; a first drying step of drying the applied film at a temperature of 140°C or less; and a second drying step of heating the applied film at a temperature of 200°C or more after drying.

[0147] When polyimide is well dissolved in organic solvent, it is preferable to form a resin layer using a polyimide varnish obtained by dissolving polyimide in an organic solvent, since the heating conditions in the film-forming process can be alleviated. When polyimide has a specific amount or more of a structural unit containing a tetracarboxylic acid residue of a specific structure containing a parabiphenylene group with a twisted dihedral angle in the main chain via an ester bond, it is easily dissolved in an organic solvent. When polyimide has a solvent solubility such that it dissolves in an organic solvent at 25°C in an amount of 6% by mass or more, the above-mentioned method for forming a resin layer can be suitably used.

[0148] According to the above-mentioned method for forming a resin layer, the polyimide content in the varnish can be increased to a sufficient concentration, and the varnish can be adjusted to a desired viscosity range, so that a resin layer with good thickness uniformity and with less air bubble defects can be obtained.

[0149] The organic solvent is not particularly limited as long as it can dissolve polyimide, and for example, aprotic polar solvents or water-soluble alcohol solvents can be used. Among them, it is preferable to use organic solvents containing nitrogen atoms such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, and γ-butyrolactone. The organic solvents can be used alone or as a mixed solvent of two or more kinds.

[0150] For the method of forming the resin layer containing the above polyimide, for example, the methods described in JP-A-2019-1989 and JP-A-2019-182974 can be referenced.

[0151] (ii) Method for forming a resin layer containing polyamideimide The method for forming the resin layer containing polyamideimide is not particularly limited, and for example, a method of applying a polyamideimide varnish containing polyamideimide and an organic solvent onto a glass substrate and drying it can be mentioned.

[0152] The method for producing polyamideimide is not particularly limited. For example, polyamideimide can be produced through a process including a step of reacting one or more tetracarboxylic dianhydrides including the tetracarboxylic dianhydride represented by the above formula (4-1) and a tetracarboxylic dianhydride having an aromatic ring or an aliphatic ring as required with one or more diamines including 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl and a diamine having an aromatic ring or an aliphatic ring as required to obtain a polyimide precursor (polyamic acid), a step of reacting the obtained polyimide precursor (polyamic acid) with a dicarboxylic acid component having an aromatic ring to obtain a polyamide-polyimide precursor (polyamic acid) copolymer, and a step of imidizing the obtained polyamide-polyimide precursor (polyamic acid) copolymer.

[0153] The organic solvent contained in the polyamideimide varnish may be the same as the organic solvent contained in the polyimide varnish described above.

[0154] The method for applying the polyamideimide varnish is not particularly limited as long as it is a method capable of applying the varnish to a desired thickness, and examples of the method include general application methods such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, screen printing, etc. A transfer method can also be used as a method for forming a coating film of the polyamideimide varnish.

[0155] After the polyamideimide varnish is applied, the solvent in the coating film is dried, for example, at a temperature of 150° C. or less, preferably at a temperature of 30° C. or more and 120° C. or less, until the coating film becomes tack-free.

[0156] The drying time may be appropriately adjusted depending on the thickness of the coating film, the type of solvent, the drying temperature, etc., and is preferably set to, for example, 5 minutes or more and 60 minutes or less, preferably 10 minutes or more and 40 minutes or less. If the drying time is too long, the efficiency of forming the resin layer may decrease. On the other hand, if the drying time is too short, the appearance of the obtained resin layer may be affected by the rapid drying of the solvent.

[0157] The method for drying the solvent is not particularly limited as long as it is possible to dry the solvent at the above-mentioned temperature. For example, an oven, a drying furnace, a hot plate, infrared heating, or the like can be used.

[0158] The drying step may include a first drying step for drying the coating film and a second drying step for heating the coating film at a high temperature after the drying. The heating temperature in the second drying step is preferably, for example, 150° C. or higher. From the viewpoint of flex resistance, it is preferable to remove as much residual solvent as possible from the resin layer.

[0159] 2. Glass substrate The glass substrate in the present disclosure has a thickness of 100 μm or less, and is a member that supports the resin layer.

[0160] The glass constituting the glass substrate is not particularly limited, but is preferably chemically strengthened glass. Chemically strengthened glass is preferable because it has excellent mechanical strength and can be made thinner accordingly. Chemically strengthened glass is typically glass whose mechanical properties are strengthened by a chemical method by partially exchanging ion species, such as replacing sodium with potassium, near the surface of the glass, and has a compressive stress layer on the surface.

[0161] Examples of glasses constituting the chemically strengthened glass substrate include aluminosilicate glass, soda lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborosilicate glass.

[0162] Commercially available chemically strengthened glass substrates include, for example, Gorilla Glass from Corning and Dragontrail from AGC. In addition, as the chemically strengthened glass substrate, for example, those described in JP 2019-194143 A can also be used.

[0163] The thickness of the glass substrate is 100 μm or less, preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 90 μm or less, and even more preferably 25 μm or more and 80 μm or less. By making the thickness of the glass substrate thin in the above range, good flexibility can be obtained and sufficient hardness can be obtained. In addition, curling of the display device member can be suppressed. Furthermore, it is preferable in terms of reducing the weight of the display device member.

[0164] 3. Functional layer The display device member according to the present disclosure may further include a functional layer on the side of the resin layer opposite to the glass substrate. Examples of the functional layer include a hard coat layer, a protective layer, an anti-reflection layer, and an anti-glare layer.

[0165] In addition, the functional layer may be a single layer or may have multiple layers. In addition, the functional layer may be a layer having a single function or may have multiple layers having different functions. For example, the display device member in the present disclosure may have a hard coat layer and a protective layer as the functional layer, in order from the resin layer side.

[0166] (1) Hard coat layer As shown in Fig. 2, the display device member according to the present disclosure preferably further includes a hard coat layer 4 on the surface of the resin layer 3 opposite to the glass substrate 2. The hard coat layer is a member for increasing the surface hardness. The provision of the hard coat layer can improve scratch resistance.

[0167] (a) Characteristics of the hard coat layer Here, the "hard coat layer" refers to a member for increasing surface hardness, and specifically refers to a member for a display device in the present disclosure that has a hard coat layer and exhibits a hardness of "H" or more when subjected to a pencil hardness test specified in JIS K 5600-5-4 (1999).

[0168] In the case where the display device member in the present disclosure has a hard coat layer on the side of the resin layer opposite the glass substrate, the pencil hardness of the surface of the display device member on the hard coat layer side is preferably H or more, more preferably 2H or more, and even more preferably 3H or more.

[0169] Here, the pencil hardness is measured by a pencil hardness test specified in JIS K5600-5-4 (1999). Specifically, a pencil hardness test specified in JIS K5600-5-4 (1999) is performed on the surface of the hard coat layer side of the display device member using a test pencil specified in JIS-S-6006, and the highest pencil hardness that does not cause scratches is evaluated. The measurement conditions can be an angle of 45°, a load of 750 g, a speed of 0.5 mm / sec or more and 1 mm / sec or less, and a temperature of 23±2°C. As a pencil hardness tester, for example, a pencil scratch coating hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

[0170] (b) Structure of the hard coat layer The hard coat layer may be a single layer or may have a multi-layer structure of two or more layers. When the hard coat layer has a multi-layer structure, in order to improve the surface hardness and to obtain a good balance between the flex resistance and the elastic modulus, the hard coat layer preferably has a layer for satisfying the pencil hardness and a layer for satisfying the dynamic flex test (a layer for satisfying the scratch resistance).

[0171] (c) Material for hard coat layer As the material for the hard coat layer, for example, an organic material, an inorganic material, or an organic-inorganic composite material can be used.

[0172] Among them, the material of the hard coat layer is preferably an organic material. Specifically, the hard coat layer preferably contains a cured product of a resin composition containing a polymerizable compound. The cured product of the resin composition containing a polymerizable compound can be obtained by polymerizing the polymerizable compound by a known method using a polymerization initiator as necessary.

[0173] (i) Polymerizable compound The polymerizable compound has at least one polymerizable functional group in the molecule. As the polymerizable compound, for example, at least one of a radical polymerizable compound and a cationic polymerizable compound can be used.

[0174] The radical polymerizable compound is a compound having a radical polymerizable group. The radical polymerizable group of the radical polymerizable compound is not particularly limited as long as it is a functional group capable of generating a radical polymerization reaction, and includes, for example, a group containing a carbon-carbon unsaturated double bond, and specifically includes a vinyl group, a (meth)acryloyl group, and the like. In addition, when the radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be the same or different from each other.

[0175] The number of radically polymerizable groups that the radically polymerizable compound has in one molecule is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.

[0176] As the radical polymerizable compound, from the viewpoint of high reactivity, a compound having a (meth)acryloyl group is preferable. For example, polyfunctional (meth)acrylate monomers and oligomers having several (meth)acryloyl groups in the molecule and a molecular weight of several hundred to several thousand, such as urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, melamine (meth)acrylate, polyfluoroalkyl (meth)acrylate, silicone (meth)acrylate, etc., can be preferably used, and polyfunctional (meth)acrylate polymers having two or more (meth)acryloyl groups in the side chain of an acrylate polymer can also be preferably used. Among them, polyfunctional (meth)acrylate monomers having two or more (meth)acryloyl groups in one molecule can be preferably used. By including a cured product of a polyfunctional (meth)acrylate monomer in the hard coat layer, the hardness of the hard coat layer can be improved, and the adhesion can be further improved. Also preferably used is a polyfunctional (meth)acrylate oligomer or polymer having two or more (meth)acryloyl groups in one molecule. By including a cured product of a polyfunctional (meth)acrylate oligomer or polymer in the hard coat layer, the hardness and bending resistance of the hard coat layer can be improved, and further, the adhesion can be improved.

[0177] In this specification, (meth)acryloyl refers to each of acryloyl and methacryloyl, and (meth)acrylate refers to each of acrylate and methacrylate.

[0178] Specific examples of polyfunctional (meth)acrylate monomers include those described in JP-A-2019-132930. Among these, from the viewpoints of high reactivity, improved hardness of the hard coat layer, and adhesion, those having 3 to 6 (meth)acryloyl groups in one molecule are preferred. For example, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, etc. can be preferably used, and in particular, at least one selected from pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexaacrylate, and those modified with PO, EO, or caprolactone are preferred.

[0179] The resin composition may contain a monofunctional (meth)acrylate monomer as a radical polymerizable compound for adjusting hardness and viscosity, improving adhesion, etc. Specific examples of monofunctional (meth)acrylate monomers include those described in JP-A-2019-132930.

[0180] The cationic polymerizable compound is a compound having a cationic polymerizable group. The cationic polymerizable group of the cationic polymerizable compound is not particularly limited as long as it is a functional group capable of generating cationic polymerization reaction, and examples thereof include an epoxy group, an oxetanyl group, and a vinyl ether group. Note that, when the cationic polymerizable compound has two or more cationic polymerizable groups, these cationic polymerizable groups may be the same or different from each other.

[0181] The number of cationically polymerizable groups that the cationically polymerizable compound has in one molecule is preferably 2 or more, and more preferably 3 or more, from the viewpoint of improving the hardness of the hard coat layer.

[0182] In addition, as the cationic polymerizable compound, a compound having at least one of an epoxy group and an oxetanyl group as a cationic polymerizable group is preferable, and a compound having at least two of an epoxy group and an oxetanyl group in one molecule is more preferable. Cyclic ether groups such as an epoxy group and an oxetanyl group are preferable because they cause little shrinkage during polymerization. In addition, compounds having an epoxy group among cyclic ether groups have the advantage that compounds with various structures are easily available, they do not adversely affect the durability of the obtained hard coat layer, and the compatibility with the radical polymerizable compound is easily controlled. In addition, among cyclic ether groups, an oxetanyl group has a higher degree of polymerization and is less toxic than an epoxy group, and when the obtained hard coat layer is combined with a compound having an epoxy group, it has the advantage of accelerating the network formation rate obtained from the cationic polymerizable compound in the coating film, and forming an independent network without leaving unreacted monomers in the film even in the region where it is mixed with the radical polymerizable compound.

[0183] Examples of the cationically polymerizable compound having an epoxy group include alicyclic epoxy resins obtained by epoxidizing a polyglycidyl ether of a polyhydric alcohol having an alicyclic ring or a compound containing a cyclohexene ring or a cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or a peracid; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polybasic acids, and homopolymers and copolymers of glycidyl (meth)acrylate; glycidyl ethers produced by reacting bisphenols such as bisphenol A, bisphenol F, and hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts or caprolactone adducts, with epichlorohydrin, and novolak epoxy resins, and the like, which are derived from bisphenols.

[0184] Specific examples of the alicyclic epoxy resin, the glycidyl ether type epoxy resin, and the cationic polymerizable compound having an oxetanyl group include those described in JP 2018-104682 A.

[0185] The cured product of the resin composition containing the polymerizable compound contained in the hard coat layer can be analyzed using a Fourier transform infrared spectrophotometer (FTIR) or a pyrolysis gas chromatograph (GC-MS), and the decomposition products of the polymer can be analyzed using a combination of high performance liquid chromatography, a gas chromatograph mass spectrometer, NMR, elemental analysis, XPS / ESCA, TOF-SIMS, etc.

[0186] (ii) Polymerization initiator The resin composition may contain a polymerization initiator as necessary. As the polymerization initiator, a radical polymerization initiator, a cationic polymerization initiator, a radical and cationic polymerization initiator, etc. may be appropriately selected and used. These polymerization initiators are decomposed by at least one of light irradiation and heating to generate radicals or cations, and cause radical polymerization and cationic polymerization to proceed. In addition, there are cases where the polymerization initiator is completely decomposed and does not remain in the hard coat layer.

[0187] Specific examples of radical polymerization initiators and cationic polymerization initiators include those described in JP-A-2018-104682.

[0188] (iii) particles The hard coat layer preferably contains inorganic or organic particles, and more preferably contains inorganic fine particles. When the hard coat layer contains particles, the hardness can be improved.

[0189] Examples of inorganic particles include metal oxide particles such as silica (SiO2), aluminum oxide, zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, and cerium oxide, metal fluoride particles such as magnesium fluoride and sodium fluoride, metal particles, metal sulfide particles, and metal nitride particles. Among these, metal oxide particles are preferred, and at least one selected from silica particles and aluminum oxide particles is more preferred, with silica particles being even more preferred. This is because excellent hardness can be obtained.

[0190] In addition, the inorganic particles are preferably reactive inorganic particles having photoreactive reactive functional groups on at least a part of the particle surface that can form covalent bonds by crosslinking between the inorganic particles themselves or between at least one polymerizable compound. The hardness of the hard coat layer can be further improved by crosslinking between the reactive inorganic particles themselves or between the reactive inorganic particles and at least one of the radical polymerizable compound and the cationic polymerizable compound.

[0191] The reactive inorganic particles have at least a part of the surface covered with an organic component, and have reactive functional groups introduced by the organic component on the surface. For example, a polymerizable unsaturated group is preferably used as the reactive functional group, and more preferably a photocurable unsaturated group. For example, the reactive functional group includes ethylenically unsaturated bonds such as (meth)acryloyl group, vinyl group, and allyl group, and epoxy group.

[0192] The reactive silica particles are not particularly limited, and conventionally known ones can be used, for example, reactive silica particles described in JP-A-2008-165040, etc. In addition, commercially available reactive silica particles include, for example, MIBK-SD, MIBK-SDMS, MIBK-SDL, MIBK-SDZL manufactured by Nissan Chemical Industries, Ltd., and V8802, V8803, etc. manufactured by JGC Catalysts and Chemicals Co., Ltd.

[0193] In addition, silica particles may be spherical silica particles, but preferably are irregular silica particles. Spherical silica particles and irregular silica particles may be mixed. In this specification, irregular silica particles refer to silica particles with random potato-shaped irregularities on the surface. Since irregular silica particles have a larger surface area than spherical silica particles, by including such irregular silica particles, the contact area with the resin component etc. is larger, and the hardness of the hard coat layer can be improved.

[0194] Whether or not the particles are amorphous silica particles can be confirmed by observing a cross section of the hard coat layer with an electron microscope.

[0195] The average particle size of the inorganic particles is preferably 5 nm or more, more preferably 10 nm or more, from the viewpoint of improving hardness. If the average particle size of the inorganic particles is too small, it is difficult to manufacture the particles, and the particles may easily aggregate with each other. In addition, the average particle size of the inorganic particles is preferably 200 nm or less, more preferably 100 nm or less, and even more preferably 50 nm or less, from the viewpoint of transparency. If the average particle size of the inorganic particles is too large, there is a risk that large irregularities are formed in the hard coat layer or that the haze is high.

[0196] Here, the average particle size of the inorganic particles can be measured by observing the cross section of the hard coat layer with an electron microscope, and the average particle size is the average of the particle sizes of 10 arbitrarily selected particles. The average particle size of the irregular silica particles is the average value of the maximum (long axis) and minimum (short axis) of the distance between two points on the periphery of the irregular silica particles that appear in the cross section of the hard coat layer observed with a microscope.

[0197] The hardness of the hard coat layer can be controlled by adjusting the size and content of the inorganic particles. For example, the content of the silica particles is preferably 25 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the polymerizable compound.

[0198] (iv) Ultraviolet absorber The hard coat layer may contain an ultraviolet absorbing agent. The deterioration of the resin layer due to ultraviolet rays can be suppressed. In particular, when the resin layer contains polyimide, the color change over time of the resin layer containing polyimide can be suppressed. In addition, in a display device including a display device member, the deterioration of a member arranged on the display panel side of the display device member, such as a polarizer, due to ultraviolet rays can be suppressed.

[0199] The ultraviolet absorber contained in the hard coat layer preferably has an absorption wavelength peak of 300nm or more and 390nm or less in absorbance measurement, more preferably 320nm or more and 370nm or less, and even more preferably 330nm or more and 370nm or less.This is because such an ultraviolet absorber can efficiently absorb ultraviolet rays in the UVA region, and can form a hard coat layer having ultraviolet absorbing ability without causing the hard coat layer to be cured by shifting the peak wavelength from the absorption wavelength of 250nm of the initiator for hardening the hard coat layer.

[0200] Among them, the ultraviolet absorbent preferably has an absorption wavelength peak of 380 nm or less, since coloring due to the ultraviolet absorbent can be suppressed.

[0201] The absorbance of the ultraviolet absorbent can be measured, for example, by using an ultraviolet-visible-near infrared spectrophotometer (for example, V-7100 manufactured by JASCO Corporation).

[0202] The ultraviolet absorbing agent may be the same as the ultraviolet absorbing agent used in the resin layer.

[0203] Among these, from the viewpoint of suppressing deterioration of the resin layer due to ultraviolet rays, one or more ultraviolet absorbers selected from the group consisting of hydroxybenzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred, and one or more ultraviolet absorbers selected from the group consisting of hydroxybenzophenone-based ultraviolet absorbers are more preferred.

[0204] Specific examples of hydroxybenzophenone-based ultraviolet absorbers include those described in JP-A-2019-132930.

[0205] Among them, the hydroxybenzophenone-based ultraviolet absorber is preferably a 2-hydroxybenzophenone-based ultraviolet absorber, and more preferably at least one selected from the group consisting of benzophenone-based ultraviolet absorbers having the following general formula (A). This can suppress deterioration of the resin layer caused by ultraviolet rays and improve durability.

[0206] [ka]

[0207] (In the general formula (A), X 1 and X 2 are each independently a hydroxyl group, -OR a or a hydrocarbon group having 1 to 15 carbon atoms, R a represents a hydrocarbon group having 1 to 15 carbon atoms.

[0208] In the general formula (A), X 1 , X 2 and R a In the above formula, examples of the hydrocarbon group having 1 to 15 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a dodecyl group, an allyl group, and a benzyl group. The aliphatic hydrocarbon groups having 3 or more carbon atoms may each be linear or branched. The hydrocarbon group preferably has 1 to 12 carbon atoms, and more preferably has 1 to 8 carbon atoms. In terms of facilitating improvement in light transmittance, the hydrocarbon group is preferably an aliphatic hydrocarbon group, and among these, a methyl group and an allyl group are preferred.

[0209] X is a material that is easy to improve durability. 1 and X 2 each independently represents a hydroxyl group or -OR a It is preferable that:

[0210] The one or more types selected from the group consisting of benzophenone-based ultraviolet absorbers having general formula (A) are preferably one or more types selected from the group consisting of 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2'-dihydroxy-4,4'-diallyloxybenzophenone, and more preferably one or more types selected from the group consisting of 2,2',4,4'-tetrahydroxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0211] Specific examples of benzotriazole-based ultraviolet absorbers include those described in JP-A-2019-132930.

[0212] Among them, the benzotriazole-based ultraviolet absorber is preferably 2-(2-hydroxyphenyl)benzotriazoles, and more preferably one or more selected from the group consisting of benzotriazole-based ultraviolet absorbers having the following general formula (B). This can suppress deterioration of the resin layer due to ultraviolet rays and improve durability.

[0213] [ka]

[0214] (In the general formula (B), Y 1 , Y 2 , and Y 3 are each independently a hydrogen atom, a hydroxyl group, -OR b or a hydrocarbon group having 1 to 15 carbon atoms, R b represents a hydrocarbon group having 1 to 15 carbon atoms; Y 1 , Y 2 , and Y 3 At least one of the groups is a hydroxyl group, -OR b or a hydrocarbon group having 1 to 15 carbon atoms. 4 represents a hydrogen atom or a halogen atom.

[0215] In the general formula (B), Y 1 , Y 2 , and Y 3 , and R b In the above formula, examples of the hydrocarbon group having 1 to 15 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a dodecyl group. The aliphatic hydrocarbon group having 3 or more carbon atoms may be linear or branched. The hydrocarbon group preferably has 1 to 12 carbon atoms, and more preferably has 1 to 8 carbon atoms. In terms of facilitating improvement in light transmittance, the hydrocarbon group is preferably an aliphatic hydrocarbon group, and is preferably a linear or branched alkyl group, and among these, a methyl group, a t-butyl group, a t-pentyl group, a n-octyl group, or a t-octyl group is preferable.

[0216] In the general formula (B), Y 4 Examples of the halogen atom in include a chlorine atom, a fluorine atom, and a bromine atom, and among these, a chlorine atom is preferred.

[0217] In the general formula (B), Y 1 , and Y 3 is a hydrogen atom, and Y 2 is a hydroxyl group or -OR b It is preferable that the compound is one or more selected from the group consisting of 2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole and 2-(2,4-dihydroxyphenyl)-2H-benzotriazole. It is possible to suppress deterioration of the resin layer due to ultraviolet rays and improve durability.

[0218] The content of the ultraviolet absorber in the hard coat layer is, for example, preferably 10% by mass or less, more preferably 7% by mass or less, from the viewpoint of suppressing haze caused by mixing the ultraviolet absorber. Also, from the viewpoint of suppressing deterioration of the resin layer due to ultraviolet rays and improving durability, the content of the ultraviolet absorber in the hard coat layer is preferably 1% by mass or more and 6% by mass or less, more preferably 2% by mass or more and 5% by mass or less.

[0219] (v) Antifouling agents The hard coat layer may contain an antifouling agent, which can impart antifouling properties to the member for a display device.

[0220] The antifouling agent is not particularly limited, and examples thereof include silicone-based antifouling agents, fluorine-based antifouling agents, and silicone-based and fluorine-based antifouling agents. The antifouling agent may also be an acrylic-based antifouling agent. The antifouling agent may be used alone or in combination of two or more.

[0221] The hard coat layer containing the silicone-based antifouling agent or the fluorine-based antifouling agent is less susceptible to fingerprints (less noticeable) and has good wiping properties. In addition, when the silicone-based antifouling agent or the fluorine-based antifouling agent is contained, the surface tension during application of the hard coat layer curable resin composition can be reduced, resulting in good leveling properties and a good appearance of the obtained hard coat layer.

[0222] In addition, the hard coat layer containing the silicone-based antifouling agent has good slipperiness and good scratch resistance. In a display device including a display device member having such a hard coat layer containing a silicone-based antifouling agent, the slipperiness when touched with a finger, a pen, or the like is improved, resulting in a good tactile sensation.

[0223] The antifouling agent preferably has a reactive functional group in order to enhance the durability of the antifouling performance. If the antifouling agent does not have a reactive functional group, regardless of whether the display device member is in the form of a roll or a sheet, when the display device member is stacked, the antifouling agent is transferred to the surface opposite to the surface of the hard coat layer side of the display device member, and when another layer is attached or applied to the surface opposite to the surface of the hard coat layer side of the display device member, the other layer may peel off, and further, when repeatedly bent, the other layer may easily peel off. On the other hand, when the antifouling agent has a reactive functional group, the performance durability of the antifouling performance is good.

[0224] The number of reactive functional groups in the antifouling agent may be at least 1, and is preferably at least 2. By using an antifouling agent having two or more reactive functional groups, excellent scratch resistance can be imparted to the hard coat layer.

[0225] The antifouling agent preferably has a weight average molecular weight of not more than 5000. The weight average molecular weight of the antifouling agent can be measured by gel permeation chromatography (GPC).

[0226] The antifouling agent may be uniformly dispersed in the hard coat layer. However, from the viewpoint of obtaining sufficient antifouling properties with a small amount of addition and suppressing a decrease in strength of the hard coat layer, it is preferable that the antifouling agent is unevenly distributed on the surface side of the hard coat layer.

[0227] Examples of the method for unevenly distributing the antifouling agent on the surface side of the hard coat layer include a method in which, when forming the hard coat layer, a coating film of a curable resin composition for a hard coat layer is dried and before being cured, the coating film is heated to reduce the viscosity of the resin component contained in the coating film, thereby increasing the fluidity, thereby unevenly distributing the antifouling agent on the surface side of the hard coat layer; and a method in which an antifouling agent with low surface tension is used, the antifouling agent is floated on the surface of the coating film without applying heat when the coating film is dried, and then the coating film is cured, thereby unevenly distributing the antifouling agent on the surface side of the hard coat layer.

[0228] The content of the antifouling agent is preferably, for example, 0.01 parts by mass or more and 3.0 parts by mass or less relative to 100 parts by mass of the resin component. If the content of the antifouling agent is too small, sufficient antifouling properties may not be imparted to the hard coat layer, and if the content of the antifouling agent is too large, the hardness of the hard coat layer may decrease.

[0229] (vi) Other additives The hard coat layer may further contain additives as necessary.The additives are appropriately selected according to the function to be imparted to the hard coat layer, and are not particularly limited, and may include, for example, inorganic or organic particles for adjusting the refractive index, infrared absorbing agents, antiglare agents, antifouling agents, antistatic agents, colorants such as blue dyes and purple dyes, leveling agents, surfactants, lubricants, various sensitizers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, light stabilizers, surface modifiers, etc.

[0230] (d) Thickness of the hard coat layer The thickness of the hard coat layer may be appropriately selected depending on the material of the hard coat layer, the function of the hard coat layer, and the use of the display device member. For example, when the material of the hard coat layer is an organic material, the thickness of the hard coat layer is preferably 2 μm or more and 50 μm or less, more preferably 3 μm or more and 30 μm or less, even more preferably 5 μm or more and 20 μm or less, and particularly preferably 6 μm or more and 10 μm or less. In addition, for example, when the material of the hard coat layer is an inorganic material, the thickness of the hard coat layer can be about several tens of nm. If the thickness of the hard coat layer is within the above range, a display device member having sufficient hardness as a hard coat layer and good bending resistance can be obtained.

[0231] (e) Method for forming hard coat layer The method for forming the hard coat layer is appropriately selected depending on the material of the hard coat layer, and examples thereof include a method of applying a curable resin composition for hard coat layer containing the polymerizable compound on the resin layer and curing the composition, a vapor deposition method, a sputtering method, and the like.

[0232] The curable resin composition for a hard coat layer contains a polymerizable compound, and may further contain a polymerization initiator, particles, an ultraviolet absorber, a solvent, an additive, and the like, as necessary.

[0233] The method for applying the curable resin composition for hard coat layer onto the resin layer is not particularly limited as long as it is a method that allows application to a desired thickness, and examples of the method include general application methods such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, screen printing, etc. In addition, a transfer method can also be used as a method for forming a coating film of the resin composition for hard coat layer.

[0234] The coating film of the curable resin composition for hard coat layer is dried as necessary to remove the solvent. Examples of the drying method include vacuum drying, heat drying, and a combination of these drying methods. For example, the coating film can be dried by heating at a temperature of 30° C. or higher and 120° C. or lower for 10 seconds to 180 seconds.

[0235] The method for curing the coating of the curable resin composition for the hard coat layer is appropriately selected depending on the polymerizable group of the polymerizable compound, and for example, at least one of light irradiation and heating can be used.

[0236] For light irradiation, ultraviolet light, visible light, electron beams, ionizing radiation, etc. are mainly used. In the case of ultraviolet curing, for example, ultraviolet light emitted from the light beam of an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. can be used. The irradiation amount of the energy ray source is, for example, 50 mJ / cm as the cumulative exposure amount at an ultraviolet wavelength of 365 nm. 2 More than 5000mJ / cm 2 It can be as follows:

[0237] When heating is performed, the treatment can be performed at a temperature of, for example, 40° C. or higher and 120° C. or lower. The reaction may also be performed by leaving the mixture at room temperature (25° C.) for 24 hours or more.

[0238] (2) Protective layer The member for a display device in the present disclosure may further include a protective layer on the side of the resin layer opposite to the glass substrate.

[0239] The protective layer has transparency. Specifically, the total light transmittance of the protective layer is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

[0240] The total light transmittance of the protective layer can be measured in accordance with JIS K7361-1, for example, by a haze meter HM150 manufactured by Murakami Color Research Laboratory. The same method for measuring the total light transmittance of other layers can be used below.

[0241] The protective layer is not particularly limited as long as it has transparency, and may contain, for example, a resin. The resin used for the protective layer is not particularly limited as long as it can provide a transparent protective layer, and a general resin may be used.

[0242] Examples of a method for disposing a protective layer on one surface of a glass substrate include a method in which a protective film is used as the protective layer and a resin layer and the protective film are bonded together via an adhesive layer, and a method in which a protective layer is formed on a resin layer.

[0243] The pressure-sensitive adhesive layer has transparency. Specifically, the total light transmittance of the pressure-sensitive adhesive layer is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

[0244] Examples of the adhesive used in the adhesive layer include an adhesive such as OCA and a photosensitive adhesive.

[0245] The thickness of the adhesive layer is preferably, for example, 1 μm or more and 100 μm or less. If the adhesive layer is too thick, the flexibility may be impaired. On the other hand, if the adhesive layer is too thin, the adhesiveness may not be ensured and the adhesive layer may peel off.

[0246] 4.Other configurations In addition to the above-mentioned layers, the display device member according to the present disclosure may have other layers as necessary, such as a primer layer, a second resin layer, and a decorative layer.

[0247] (1) Primer layer The member for a display device according to the present disclosure may have a primer layer 5 between the glass substrate 2 and the resin layer 3, as shown in Fig. 3, for example. In addition, when the member for a display device according to the present disclosure has a second resin layer 6 on the surface of the glass substrate 2 opposite to the resin layer 3, as shown in Fig. 4, for example, a primer layer 7 may be provided between the glass substrate 2 and the second resin layer 6. The primer layer can improve the adhesion between the glass substrate and the resin layer and the second resin layer.

[0248] The material of the primer layer is not particularly limited as long as it is a material that can increase the adhesion between the glass substrate and the resin layer or the second resin layer, and examples thereof include resins. Examples of resins include (meth)acrylic resins, urethane resins, (meth)acrylic urethane copolymers, vinyl chloride-vinyl acetate copolymer resins, polyesters, butyral resins, chlorinated polypropylene, chlorinated polyethylene, epoxy resins, silicone resins, etc. These resins may be used alone or in combination of two or more.

[0249] The thickness of the primer layer may be any thickness that is capable of increasing the adhesion between the glass substrate and the resin layer or the second resin layer, and may be, for example, 0.1 μm or more and 10 μm or less, and preferably 0.2 μm or more and 5 μm or less.

[0250] The method for forming the primer layer may be, for example, a method for applying a primer layer composition onto a glass substrate.The application method may be, for example, a general application method such as gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, screen printing, etc.The primer layer may also be formed by a transfer method.

[0251] (2) Second resin layer 4, the display device member according to the present disclosure may have a second resin layer 6 on the surface of the glass substrate 2 opposite to the resin layer 3. When an impact is applied to the display device member, not only the resin layer but also the second resin layer absorbs the impact, and cracking of the glass substrate can be suppressed, thereby improving impact resistance.

[0252] The resin contained in the second resin layer is not particularly limited as long as it is a resin capable of absorbing impact, and examples thereof include urethane resin, epoxy resin, polyimide, polyamideimide, acrylic resin, triacetyl cellulose (TAC), etc. These resins may be used alone or in combination of two or more.

[0253] The second resin layer may further contain an additive as necessary. Examples of the additive include an ultraviolet absorbing agent. The ultraviolet absorbing agent may be the same as the ultraviolet absorbing agent used in the resin layer.

[0254] The thickness of the second resin layer may be any thickness capable of absorbing impact, and may be, for example, preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 50 μm or less, and even more preferably 15 μm or more and 40 μm or less.

[0255] The method for forming the second resin layer can be the same as the method for forming the above-mentioned resin layer.

[0256] (3) Decorative layer The display device member according to the present disclosure may have a decorative layer between the glass substrate and the resin layer, or on the surface of the glass substrate opposite to the resin layer.

[0257] The decorative layer includes a colorant and a binder resin. The binder resin included in the decorative layer is not particularly limited, and a resin used in a general decorative layer can be used. The colorant included in the decorative layer is not particularly limited, and a known colorant used in a general decorative layer can be used.

[0258] The decorative layer is usually disposed on a part of the glass substrate, and may have a pattern shape.

[0259] The thickness of the decorative layer is not particularly limited, but can be, for example, 5 μm or more and 40 μm or less.

[0260] 5. Characteristics of display device components The display device member in the present disclosure preferably has a total light transmittance of, for example, 80% or more, more preferably 85% or more, and even more preferably 88% or more. Such a high total light transmittance allows the display device member to have good transparency.

[0261] Here, the total light transmittance of the member for a display device can be measured in accordance with JIS K7361-1, for example, by using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0262] The haze of the display device member in the present disclosure is, for example, preferably 2.0% or less, more preferably 1.5% or less, and even more preferably 1.0% or less. Such a low haze allows the display device member to have good transparency.

[0263] Here, the haze of the display member can be measured in accordance with JIS K-7136, for example, by using a haze meter HM150 manufactured by Murakami Color Research Laboratory.

[0264] The member for a display device in the present disclosure preferably has bending resistance. Specifically, when the dynamic bending test described below is repeated 200,000 times, the member for a display device preferably does not crack or break, and more preferably when the dynamic bending test is repeated 1,000,000 times, the member for a display device preferably does not crack or break.

[0265] In the dynamic bending test, the display device component may be folded so that the glass substrate is on the outside, or the display device component may be folded so that the glass substrate is on the inside, but in either case, it is preferable that the display device component does not crack or break.

[0266] The dynamic bending test is carried out as follows. As shown in FIG. 5(a), in the dynamic bending test, first, the short side 1C of the display device member 1 having a size of 20 mm×100 mm and the short side 1D opposite to the short side 1C are fixed by the fixing parts 21 arranged in parallel. Also, as shown in FIG. 5(a), the fixing parts 21 are slidable in the horizontal direction. Next, as shown in FIG. 5(b), the fixing parts 21 are moved so as to approach each other, so that the display device member 1 is deformed so as to be folded, and further, as shown in FIG. 5(c), the fixing parts 21 are moved to a position where the distance d between the two opposing short side parts 1C and 1D fixed by the fixing parts 21 of the display device member 1 becomes a predetermined value, and then the fixing parts 21 are moved in the opposite direction to eliminate the deformation of the display device member 1. As shown in FIG. 5(a) to (c), the fixing parts 21 are moved to fold the display device member 1 by 180°. Furthermore, by performing a dynamic bending test so that the bent portion 1E of the display device member 1 does not protrude from the lower end of the fixing portion 21 and controlling the distance d when the fixing portion 21 is closest, the distance d between the two opposing short side portions 1C, 1D of the display device member 1 can be set to a predetermined value. For example, when the distance d between the two opposing short side portions 1C, 1D is 10 mm, the outer diameter of the bent portion 1E is regarded as 10 mm.

[0267] It is preferable that no cracks or breaks occur in a display device member when a test in which the display device member 1 is folded 180° so that the distance d between the opposing short sides 1C, 1D of the display device member 1 is 10 mm is repeated 200,000 times, and it is even more preferable that no cracks or breaks occur in a dynamic bending test in which the display device member is folded 180° so that the distance d between the opposing short sides of the display device member is 10 mm, 8 mm, 6 mm, 5 mm, 4 mm, 3 mm, 2.5 mm, or 2 mm is repeated 200,000 times.

[0268] Furthermore, when a static bending test described below is carried out on a member for a display device, the member for a display device preferably has an opening angle θ of 100° or more after the static bending test.

[0269] The static bending test is performed as follows. First, as shown in FIG. 6(a), the short side 1C of the display device member 1 and the short side 1D facing the short side 1C are fixed by the fixing parts 22 arranged in parallel so that the distance d between the short side 1C and the short side 1D is a predetermined value. Then, the display device member 1 is folded and left to stand at 23° C. for 240 hours to perform a static bending test. After that, as shown in FIG. 6(b), the fixing parts 22 are removed from the short side 1D after the static bending test to open the folded state, and the opening angle θ, which is the angle at which the display device member 1 naturally opens after 30 minutes at room temperature, is measured. The larger the opening angle θ, the better the restorability, and the maximum opening angle is 180°.

[0270] In the member for a display device, when a static bending test is performed so that the distance d between the opposing short sides 1C, 1D of the member for a display device 1 is 10 mm, the opening angle θ after the static bending test is preferably 100° or more.

[0271] In the static bending test, the display device component may be folded so that the glass substrate is on the inside, or the display device component may be folded so that the glass substrate is on the outside, but in either case, it is preferable that the opening angle θ is 100° or more.

[0272] 6. Uses of display device components The display device member in the present disclosure can be used as a member arranged on the viewer side of the display panel in a display device. The display device member in the present disclosure can be used as a display device member for, for example, a smartphone, a tablet terminal, a wearable terminal, a personal computer, a television, a digital signage, a public information display (PID), an in-vehicle display, etc. In particular, the display device member in the present disclosure can be preferably used for flexible displays such as foldable displays, rollable displays, and bendable displays, and can be preferably used as a foldable display member.

[0273] In the display device member according to the present disclosure, the surface that becomes the outermost surface after the display device member is placed on the surface of a display device is preferably the surface on the resin layer side.

[0274] The method for disposing the display device member of the present disclosure on the surface of the display device is not particularly limited, and examples thereof include a method via an adhesive layer, etc. As the adhesive layer, a known adhesive layer used for adhering display device members can be used.

[0275] B. Optical laminate In order to solve the above problems, the inventors of the present disclosure have conducted intensive research and found that by using a thin glass substrate having flexibility and disposing a resin layer on one side of the glass substrate, the cracking of the glass substrate can be suppressed and the impact resistance can be increased, and further, by setting the composite modulus of the resin layer within a predetermined range, even if the thickness of the resin layer is relatively thin for flexibility, the cracking of the glass substrate can be suppressed and the impact resistance can be increased. The inventors of the present disclosure have further conducted research and found that by laminating a first resin layer having a predetermined composite modulus, a second resin layer which is an adhesive layer, and a third resin layer which is a predetermined resin film, the cracking of the glass substrate can be further suppressed and the impact resistance can be further increased compared to the case of only a resin layer having a predetermined composite modulus. In addition, by laminating a specific first resin layer, a second resin layer, and a third resin layer, even if the glass substrate is broken, the fragments or sharp end faces are not exposed, and it is possible to use it more safely. The optical laminate in the present disclosure is based on such findings.

[0276] The optical laminate in the present disclosure is an optical laminate having, in this order, a glass substrate, a first resin layer, a second resin layer, and a third resin layer, wherein the thickness of the glass substrate is 100 μm or less, the composite elastic modulus of the first resin layer is 5.7 GPa or more, the thickness of the first resin layer is 5 μm or more and 60 μm or less, the second resin layer is an adhesive layer, and the third resin layer is a resin film containing a resin selected from the group consisting of polyester-based resins, polycycloolefin-based resins, acetyl cellulose-based resins, polycarbonate-based resins, and polypropylene-based resins.

[0277] Fig. 7 is a schematic cross-sectional view showing an example of an optical laminate in the present disclosure. As shown in Fig. 7, the optical laminate 11 has a glass substrate 12, a first resin layer 13, a second resin layer 14, and a third resin layer 15, in this order. The glass substrate 12 has a predetermined thickness, the first resin layer 13 has a predetermined thickness and a predetermined composite elastic modulus, the second resin layer 14 is an adhesive layer, and the third resin layer 15 is a resin film containing a predetermined resin.

[0278] In the present disclosure, the glass substrate is thin, being less than a predetermined value, and therefore is likely to be easily broken and has low impact resistance, but by laminating a first resin layer having a predetermined composite elastic modulus, a second resin layer being an adhesive layer, and a third resin layer being a predetermined resin film in this order on one side of the glass substrate, when an impact is applied to the optical laminate, the first resin layer, the second resin layer, and the third resin layer absorb the impact, suppressing the breakage of the glass substrate and improving the impact resistance. The reason for this is not clear, but is presumed to be as follows.

[0279] That is, since the first resin layer has a predetermined composite elastic modulus, the second resin layer is an adhesive layer, and the third resin layer is a predetermined resin film, the second resin layer is a layer softer than the first resin layer and the third resin layer, and the third resin layer is a layer softer than the first resin layer. For example, the tensile elastic modulus of the resin contained in the resin film constituting the third resin layer is 2.8 to 4 GPa for polyethylene terephthalate (PET), 2.1 GPa for polycycloolefin (COP), 1.4 GPa for triacetyl cellulose (TAC), 2.4 GPa for polycarbonate (PC), and 2 GPa for polypropylene (PP), and it can be said that the third resin layer is a layer softer than the first resin layer. Therefore, compared to a case where only the first resin layer is arranged on one side of the glass substrate, when the first resin layer, the second resin layer, and the third resin layer are stacked in this order on one side of the glass substrate, when an impact is applied to the optical laminate, the second resin layer and the third resin layer are more likely to deform than the first resin layer, and it is therefore thought that the impact is more easily dispersed.

[0280] In addition, since the second resin layer and the third resin layer, which are softer than the first resin layer, are arranged on the side of the first resin layer opposite to the glass substrate, it is considered that when an impact is applied to the optical laminate, the impact is not easily transmitted to the glass substrate. Therefore, when the first resin layer, the second resin layer, and the third resin layer are laminated, it is presumed that the impact absorption is higher than when only the first resin layer is laminated. Furthermore, when only the second resin layer and the third resin layer are laminated in this order on one side of the glass substrate, when an impact is applied to the optical laminate, the second resin layer and the third resin layer are relatively soft and easily deformed, so there is a risk that the glass substrate will be damaged before the impact is fully absorbed. Therefore, when the first resin layer, the second resin layer, and the third resin layer are laminated, it is presumed that the impact resistance is higher than when only the second resin layer and the third resin layer are laminated.

[0281] As described above in the section on display device components, the reason why the composite elastic modulus of the first resin layer is adopted in the present disclosure is that in measuring the composite elastic modulus of the first resin layer by the nanoindentation method (indentation test method), an indenter is pressed into a measurement sample, which is similar to the tip of a pen colliding with and pressing into a sample in a pen drop test.

[0282] According to the present disclosure, the composite elastic modulus of the first resin layer is equal to or greater than a predetermined value, so that the impact resistance in a pen drop test can be improved.

[0283] Furthermore, in the present disclosure, even if the glass substrate is broken, the first resin layer, the second resin layer, and the third resin layer can prevent the glass from scattering.

[0284] In addition, according to the present disclosure, the thickness of the glass substrate is thin, being equal to or less than a predetermined value, the thickness of the first resin layer having a composite elastic modulus equal to or greater than a predetermined value is relatively thin within a predetermined range, the second resin layer is an adhesive layer that is a relatively soft layer, and the third resin layer is a predetermined resin film, so that flexibility can be increased. Therefore, when the optical laminate is bent, cracks in the first resin layer, the second resin layer, and the third resin layer can be suppressed, and bending resistance can be maintained. Therefore, the optical laminate in the present disclosure can be folded and can be used for a wide variety of optical laminates, for example, as a member for a foldable display.

[0285] In addition, according to the present disclosure, the composite elastic modulus of the first resin layer is equal to or greater than a predetermined value, so that the force of recovery when deformation is applied to the first resin layer can be increased. Therefore, the composite elastic modulus of the first resin layer is equal to or greater than a predetermined value, so that the recovery property of the optical laminate after it has been folded for a long time can be improved. In addition, the recovery property of the optical laminate after repeatedly folding the optical laminate can be improved.

[0286] In this manner, the present disclosure provides an optical laminate having excellent impact resistance and flexibility. Furthermore, even if the glass substrate is broken, the risk of injury to the human body can be reduced, and the optical laminate has high safety.

[0287] Hereinafter, each component of the optical laminate according to the present disclosure will be described.

[0288] 1.First resin layer The first resin layer in the present disclosure is a member having a composite elastic modulus of 5.7 GPa or more, a thickness of 5 μm or more and 60 μm or less, and disposed on one surface side of a glass substrate. The first resin layer is a member having impact absorption properties, and also functions as a member for suppressing scattering of glass when the glass substrate is broken. The first resin layer is transparent, and when the optical laminate in the present disclosure is disposed on the viewer side of a display panel of a display device, it is disposed on the viewer side of the glass substrate.

[0289] (1) Characteristics of the first resin layer The composite elastic modulus of the first resin layer can be the same as the composite elastic modulus of the resin layer in the above-mentioned member for a display device.

[0290] Here, the method for measuring the composite elastic modulus of the first resin layer can be the same as the method for measuring the composite elastic modulus of the resin layer in the member for a display device described above.

[0291] In order to avoid the influence of the glass substrate and the side edges of the first resin layer, the Berkovich indenter is pressed into a portion of the first resin layer that is 500 nm away from the interface between the glass substrate and the first resin layer toward the center of the first resin layer and 500 nm away from each of the two ends of the first resin layer toward the center of the first resin layer, and is also pressed into a portion of the first resin layer that is 500 nm away from the interface between the second resin layer and the first resin layer toward the center of the first resin layer.

[0292] (2) Configuration of the first resin layer The thickness of the first resin layer can be the same as that of the resin layer in the above-mentioned member for a display device.

[0293] The first resin layer may be disposed on the glass substrate in the same manner as the resin layer in the member for a display device described above is disposed on the glass substrate.

[0294] (3) Material of the first resin layer (a) Resin The resin contained in the first resin layer can be the same as the resin contained in the resin layer in the above-mentioned member for a display device.

[0295] (b) Ultraviolet absorber The first resin layer may contain an ultraviolet absorbing agent, which may be the same as the ultraviolet absorbing agent contained in the resin layer in the member for a display device described above.

[0296] (c) Other additives The first resin layer may further contain additives as necessary. The additives may be the same as those contained in the resin layer in the above-mentioned display device member.

[0297] (4) Method for forming the first resin layer The first resin layer can be formed by the same method as the resin layer in the member for a display device described above.

[0298] 2.Second resin layer The second resin layer in the present disclosure is an adhesive layer. The first resin layer and the third resin layer, which is a predetermined resin film, can be bonded together via the second resin layer, which is an adhesive layer. The second resin layer is a member having impact absorption properties. The second resin layer has transparency, and when the optical laminate in the present disclosure is disposed on the viewer side of the display panel of a display device, it is disposed on the viewer side of the glass substrate.

[0299] The second resin layer has transparency, and specifically, the total light transmittance of the second resin layer is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

[0300] The total light transmittance of the second resin layer can be measured in accordance with JIS K7361-1, for example, by a haze meter HM150 manufactured by Murakami Color Research Laboratory. The same method for measuring the total light transmittance of the other layers can be used below.

[0301] The adhesive used in the second resin layer is not particularly limited as long as it is an adhesive capable of obtaining an adhesive layer having transparency, and for example, OCA (Optical Clear Adhesive) can be used. Specific examples include acrylic adhesives, silicone adhesives, urethane adhesives, rubber adhesives, polyvinyl ether adhesives, polyvinyl acetate adhesives, etc.

[0302] The thickness of the second resin layer is preferably, for example, 1 μm or more and 100 μm or less. If the thickness of the second resin layer is too thick, the flexibility may be impaired. On the other hand, if the thickness of the second resin layer is too thin, the adhesiveness may not be ensured and the layer may peel off.

[0303] The second resin layer may be, for example, an adhesive film. Alternatively, the second resin layer may be formed by applying an adhesive composition onto the first resin layer or the third resin layer.

[0304] 3.Third resin layer The third resin layer in the present disclosure is a resin film containing a resin selected from the group consisting of polyester-based resins, polycycloolefin-based resins, acetyl cellulose-based resins, polycarbonate-based resins, and polypropylene-based resins. The third resin layer is a member having impact absorption properties, and also functions as a member for suppressing glass from scattering when the glass substrate is broken. The third resin layer is transparent, and when the optical laminate in the present disclosure is disposed on the viewer side of the display panel of the display device, it is disposed on the viewer side of the glass substrate.

[0305] The third resin layer has transparency, and specifically, the total light transmittance of the third resin layer is preferably 85% or more, more preferably 88% or more, and even more preferably 90% or more.

[0306] The resin contained in the resin film constituting the third resin layer is a resin selected from the group consisting of polyester-based resins, polycycloolefin-based resins, acetylcellulose-based resins, polycarbonate-based resins, and polypropylene-based resins. The polyester-based resin is not particularly limited as long as it can provide a resin film having transparency, and examples thereof include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and the like. The polycycloolefin-based resin is not particularly limited as long as it can provide a resin film having transparency, and examples thereof include norbornene-based resins, monocyclic olefin-based resins, cyclic conjugated diene-based resins, vinyl alicyclic hydrocarbon-based resins, and hydrogenated versions thereof. The acetylcellulose-based resin is not particularly limited as long as it can provide a resin film having transparency, and examples thereof include triacetylcellulose (TAC), and the like. The polycarbonate-based resin is not particularly limited as long as it can provide a resin film having transparency, and examples thereof include polycarbonate (PC), and the like. The polypropylene-based resin is not particularly limited as long as it can provide a resin film having transparency, and examples thereof include polypropylene (PP), and the like.

[0307] The third resin layer may contain additives such as a filler, an ultraviolet absorber, a stabilizer, an antioxidant, an antistatic agent, a flame retardant, and a lubricant, if necessary.

[0308] The thickness of the third resin layer is, for example, preferably 0.5 μm to 30 μm, more preferably 1.0 μm to 25 μm, and even more preferably 1.5 μm to 20 μm. If the third resin layer is too thick, flexibility and bendability may be impaired. On the other hand, if the third resin layer is too thin, sufficient impact resistance may not be obtained.

[0309] The third resin layer, which is a resin film, can be attached to the first resin layer via the second resin layer, which is an adhesive layer.

[0310] 4. Glass substrate The glass substrate in the present disclosure has a thickness of 100 μm or less and is a member that supports the first resin layer. The glass substrate may be the same as the glass substrate in the above-mentioned member for a display device.

[0311] 5. Functional Layer The optical laminate of the present disclosure may further include a functional layer on the side of the third resin layer opposite to the second resin layer. Examples of the functional layer include a hard coat layer, an anti-reflection layer, and an anti-glare layer.

[0312] The functional layer may be a single layer or may have multiple layers. The functional layer may be a layer having a single function or may have multiple layers having different functions.

[0313] (1) Hard coat layer The optical laminate according to the present disclosure preferably further includes a hard coat layer 16 on the side of the third resin layer 15 opposite to the second resin layer 14, as shown in Fig. 8 for example. The hard coat layer is a member for increasing the surface hardness. By providing the hard coat layer, scratch resistance can be improved.

[0314] The hard coat layer may be the same as the hard coat layer in the member for a display device described above.

[0315] 6.Other configurations The optical laminate of the present disclosure may have other layers, if necessary, in addition to the layers described above.

[0316] (1) Second Hard Coat Layer The optical laminate in the present disclosure may further include a second hard coat layer 17 between the first resin layer 13 and the second resin layer 14, as shown in FIG. 9. The second hard coat layer is a member for increasing the surface hardness. By providing the second hard coat layer, the impact resistance can be improved.

[0317] The second hard coat layer can be the same as the above-mentioned hard coat layer, and therefore the description thereof will be omitted here.

[0318] (2) Fourth resin layer The optical laminate in the present disclosure may have a fourth resin layer on the surface of the glass substrate opposite to the first resin layer. When an impact is applied to the optical laminate, not only the first resin layer, the second resin layer, and the third resin layer but also the fourth resin layer can absorb the impact, suppressing cracking of the glass substrate and improving impact resistance.

[0319] The resin contained in the fourth resin layer is not particularly limited as long as it is a resin capable of absorbing impact, and examples thereof include urethane resin, epoxy resin, polyimide, polyamideimide, acrylic resin, triacetyl cellulose (TAC), etc. These resins may be used alone or in combination of two or more.

[0320] The fourth resin layer may further contain additives as necessary, such as fillers, ultraviolet absorbers, stabilizers, antioxidants, antistatic agents, flame retardants, and lubricants.

[0321] The thickness of the fourth resin layer may be any thickness capable of absorbing impact, and may be, for example, preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 50 μm or less, and even more preferably 15 μm or more and 40 μm or less.

[0322] The fourth resin layer may be formed by the same method as that for forming the first resin layer.

[0323] (3) Primer layer The optical laminate in the present disclosure may have a primer layer between the glass substrate and the first resin layer. In addition, when the optical laminate in the present disclosure has a fourth resin layer on the surface side of the glass substrate opposite to the first resin layer, the primer layer may be between the glass substrate and the fourth resin layer. The primer layer can improve the adhesion between the glass substrate and the first resin layer and the adhesion between the glass substrate and the fourth resin layer.

[0324] The primer layer may be the same as the primer layer in the member for a display device described above.

[0325] (4) Decorative layer The optical laminate according to the present disclosure may have a decorative layer between the glass substrate and the first resin layer, or on the surface of the glass substrate opposite to the first resin layer.

[0326] The decorative layer may be the same as the decorative layer in the member for a display device described above.

[0327] 7.Optical laminate In the optical laminate of the present disclosure, the total thickness of the resin layers arranged on the surface side of the first resin layer of the glass substrate is not particularly limited as long as it is a thickness that provides impact resistance and flexibility, but for example, it is preferably 143 μm or less, more preferably 135 μm or less. By having the total thickness of the resin layers in the above range, the flexibility of the optical laminate can be improved.

[0328] The resin layer disposed on the surface side of the first resin layer of the glass substrate refers to all layers including resin among the layers disposed on the surface side of the first resin layer of the glass substrate. The resin layer includes at least the first resin layer, the second resin layer, and the third resin layer, and may further include the functional layer, the second hard coat layer, the primer layer, and the decorative layer.

[0329] The total light transmittance and haze of the optical laminate according to the present disclosure can be similar to those of the above-mentioned member for a display device.

[0330] The optical laminate of the present disclosure preferably has bending resistance. Specifically, it is preferable that the optical laminate does not crack or break when the dynamic bending test described below is repeated 200,000 times.

[0331] In the dynamic bending test, the optical laminate may be folded so that the glass substrate is on the outside, or the optical laminate may be folded so that the glass substrate is on the inside, but in either case, it is preferable that the optical laminate does not crack or break.

[0332] The dynamic bending test can be performed in the same manner as the dynamic bending test described above in the section on members for display devices.

[0333] It is preferable that the optical laminate does not crack or break when a test of folding the optical laminate 1 by 180° so that the distance d between the opposing short side portions 1C and 1D of the optical laminate 1 is 10 mm is repeated 200,000 times. In particular, it is more preferable that no crack or break occurs when a test of folding the optical laminate 1 by 180° so that the distance d between the opposing short side portions 1C and 1D of the optical laminate 1 is 8 mm is repeated 70,000 times, even more preferable that no crack or break occurs when repeated 100,000 times, and particularly preferable that no crack or break occurs when repeated 200,000 times.

[0334] Furthermore, when the static bending test described below is carried out on the optical laminate, it is preferable that the opening angle θ of the optical laminate after the static bending test is 100° or more.

[0335] The static bending test may be the same as that described in the section on members for display devices above.

[0336] In the optical laminate, when a static bending test is performed so that the distance d between opposing short sides 1C, 1D of the optical laminate 1 is 10 mm, the opening angle θ after the static bending test is preferably 100° or more.

[0337] In the static bending test, the optical laminate may be folded so that the glass substrate is on the inside, or the optical laminate may be folded so that the glass substrate is on the outside. In either case, the opening angle θ is preferably 100° or more, and more preferably 130° or more.

[0338] The applications of the optical laminate in the present disclosure can be similar to the applications of the above-mentioned members for display devices.

[0339] When the optical laminate of the present disclosure is disposed on the surface of a display device, the surface on the glass substrate side faces the display panel, and the surface on the third resin layer side faces outward.

[0340] The method for disposing the optical laminate of the present disclosure on the surface of a display device can be the same as that for the above-mentioned member for a display device.

[0341] B.Display device A display device according to the present disclosure includes a display panel, and the above-described member for a display device or the above-described optical laminate, which is disposed on the viewer's side of the display panel.

[0342] Fig. 10 is a schematic cross-sectional view showing an example of a display device in the present disclosure. As shown in Fig. 10, a display device 30 includes a display panel 31, a touch panel member 32, and a display device member 1 arranged on the viewer side of the display panel 31 and the touch panel member 32. In the display device 30, the display device member 1 is used as a member arranged on the surface of the display device 30, and an adhesive layer 34 is arranged between the display device member 1 and the touch panel member 32. In addition, an adhesive layer 33 is also arranged between the display panel 31 and the touch panel member 32.

[0343] Fig. 11 is a schematic cross-sectional view showing another example of a display device according to the present disclosure. As shown in Fig. 11, a display device 30 includes a display panel 31 and an optical laminate 11 arranged on the viewer side of the display panel 31. In the display device 30, the optical laminate 11 is used as a member arranged on the surface of the display device 30, and an adhesive layer 35 is arranged between the optical laminate 11 and the display panel 31.

[0344] The member for a display device in the present disclosure may be similar to the member for a display device described above.

[0345] The optical laminate in the present disclosure may be similar to the optical laminate described above.

[0346] Examples of the display panel in the present disclosure include display panels used in display devices such as liquid crystal display devices, organic EL display devices, and LED display devices.

[0347] The display device according to the present disclosure may have a touch panel member between the display panel and a member for a display device or an optical laminate.

[0348] The display device in the present disclosure is preferably a flexible display. In particular, the display device in the present disclosure is preferably foldable. That is, the display device in the present disclosure is more preferably a foldable display. The display device in the present disclosure has excellent bending resistance because it has the above-mentioned member for a display device, or has excellent impact resistance and flexibility because it has the above-mentioned optical laminate, and is suitable as a flexible display or even a foldable display.

[0349] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present disclosure and exhibits similar effects is included in the technical scope of the present disclosure. EXAMPLES

[0350] The present disclosure will be further described below with reference to examples and comparative examples.

[0351] [Example 1-1] (1) Formation of primer layer The components were mixed together to obtain the composition shown below to prepare a primer layer composition. Bisphenol A type solid epoxy resin (jER1256B40, manufactured by Mitsubishi Chemical) 28 parts by weight Bisphenol A novolac type solid epoxy resin (jER157S65B80, manufactured by Mitsubishi Chemical) 5 parts by weight 2-Ethyl-4-methylimidazole (Tokyo Chemical Industry Co., Ltd.) 1 part by weight Solvent (MEK) 11 parts by weight

[0352] A chemically strengthened glass substrate having a thickness of 70 μm was prepared, and the above-mentioned primer layer composition was applied to the glass substrate to a predetermined thickness, and dried at 80°C for 3 minutes and at 150°C for 60 minutes to form a primer layer having a thickness of 1 μm.

[0353] (2) Formation of resin layer With reference to Synthesis Example 1 of WO 2014 / 046180, a tetracarboxylic dianhydride represented by the following chemical formula was synthesized.

[0354] [ka]

[0355] A solution of dehydrated N,N-dimethylacetamide (DMAc) (1833.2 g) and 2,2'-bis(trifluoromethyl)benzidine (TFMB) (138.48 g) was placed in a 5L separable flask, and the liquid temperature was controlled at 30°C. Tetracarboxylic dianhydride (TMPBPTME) (176.70 g) represented by the above chemical formula was gradually added so that the temperature rise was 2°C or less, and the mixture was stirred with a mechanical stirrer for 30 minutes. Pyromellitic dianhydride (PMDA) (64.20 g) was gradually added in several portions so that the temperature rise was 2°C or less, synthesizing a polyimide precursor solution (solid content 18% by mass) in which the polyimide precursor was dissolved. The molar ratio (TMPBPTME:PMDA) of the tetracarboxylic dianhydride TMPBPTME and PMDA used in the polyimide precursor was 90:10. The weight average molecular weight of the polyimide precursor was 75,000.

[0356] Under a nitrogen atmosphere, the above polyimide precursor solution (2162 g) was added to a 5 L separable flask, cooled to room temperature. Dehydrated N,N-dimethylacetamide (432 g) was added and stirred until homogenous. Next, catalysts pyridine (6.622 g) and acetic anhydride (213.67 g) were added and stirred at room temperature for 24 hours to synthesize a polyimide solution.

[0357] N,N-dimethylacetamide (DMAc) (2000 g) was added to the obtained polyimide solution and stirred until it became uniform. Next, the polyimide solution was divided into three equal parts and transferred to a 5 L beaker, and isopropyl alcohol (3500 g) was gradually added to each beaker to obtain a white slurry. The above slurry was transferred onto a Buchner funnel and filtered, and then washed with isopropyl alcohol (total 9000 g), and the process of filtering was repeated three times, and the mixture was dried at 110 ° C using a vacuum dryer to obtain polyimide (polyimide powder). The weight average molecular weight of the polyimide measured by GPC was 100,000.

[0358] A polyimide varnish (resin composition) containing 12% by mass of polyimide was prepared by adding N,N-dimethylacetamide (DMAc) to the polyimide so that the solid content of the polyimide was 12% by mass. The viscosity of the polyimide varnish (resin composition) (solid content concentration 12% by mass) at 25°C was 15000cps.

[0359] The polyimide varnish (resin composition) was applied to a predetermined thickness on the primer layer and dried at 100°C for 10 minutes, at 150°C for 10 minutes, and at 230°C for 30 minutes to form a resin layer with a thickness of 5 μm to 60 μm.

[0360] (3) Formation of hard coat layer The components were mixed so as to obtain the composition shown below, thereby preparing a curable resin composition for a hard coat layer. Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (M403, manufactured by Toagosei Co., Ltd.) 25 parts by weight Dipentaerythritol EO modified hexaacrylate (A-DPH-6E, manufactured by Shin-Nakamura Chemical Co., Ltd.) 25 parts by weight -50 parts by weight (solid equivalent) of non-standard silica particles (average particle size 25 nm, manufactured by JGC Catalysts and Chemicals) Photopolymerization initiator (Irg184) 4 parts by weight Fluorine-based leveling agent (F568, DIC Corporation) 0.2 parts by weight (solid equivalent) Ultraviolet absorber 1 (DAINSORB P6, manufactured by Daiwa Kasei) 3 parts by weight Solvent (MIBK) 150 parts by weight

[0361] The above-mentioned curable resin composition for hard coat layer was applied onto the above-mentioned resin layer to a predetermined thickness, dried at 80° C. for 3 minutes, and then cured by irradiation with ultraviolet light to form a hard coat layer having a thickness of 10 μm.

[0362] [Example 1-2] A member for a display device was produced in the same manner as in Example 1-1, except that a resin layer was formed as follows.

[0363] A 500 mL separable flask was purged with N2, and a solution containing 293.29 g of dehydrated dimethylacetamide (DMAc) and 14.3 g (44.7 mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was dissolved therein. The solution was controlled to have a liquid temperature of 30°C. 24.8 g (40.1 mmol) of tetracarboxylic dianhydride (TMPBPTME) used in Example 1 was gradually added so that the temperature rise was 2°C or less, and the mixture was stirred with a mechanical stirrer for 3 hours. Then, 0.91 g (4.5 mmol) of terephthalic acid dichloride (TPC) was added to the solution and stirred for another 3 hours to obtain a polyamic acid solution. Next, 6.66 g (84.2 mmol) of pyridine and 8.60 g (84.2 mmol) of acetic anhydride, which are catalysts, were added, and the mixture was stirred at 25°C for 30 minutes to confirm that the solution was homogeneous, and the mixture was heated to 70°C and stirred for 1 hour. After that, 174.26 g of 2-propyl alcohol (IPA) was gradually added to the solution cooled to room temperature, resulting in a slightly turbid solution. 435.64 g of IPA was added to the turbid solution all at once to obtain a white slurry. The slurry was filtered and washed five times with IPA, and then dried for six hours under reduced pressure in an oven heated to 100°C to obtain a polyamideimide powder (37.1 g). The weight average molecular weight of the polyamideimide measured by GPC was 62,000.

[0364] A polyamideimide varnish containing 19% by mass of polyamideimide was prepared by adding DMAc to the polyamideimide so that the solid content of the polyamideimide became 19% by mass. The viscosity of the polyamideimide varnish (solid content of 19% by mass) at 25°C was 4000 mPa s.

[0365] The above polyamideimide varnish (resin composition) was applied onto the primer layer to a predetermined thickness, and dried at 100°C for 10 minutes, at 150°C for 10 minutes, and at 230°C for 30 minutes to form a resin layer with a thickness of 5 μm to 60 μm.

[0366] [Examples 1-3] A member for a display device was produced in the same manner as in Example 1-1, except that a resin layer was formed as follows.

[0367] A solution of dehydrated N,N-dimethylacetamide (DMAc) (1833.2 g) and 2,2'-bis(trifluoromethyl)benzidine (TFMB) (138.48 g) was placed in a 5 L separable flask, and the liquid temperature was controlled at 30 ° C. Tetracarboxylic acid dianhydride (TMPBPTME) (256.026 g) represented by the above chemical formula was gradually added so that the temperature rise was 2 ° C or less, and the mixture was stirred with a mechanical stirrer for 30 minutes. Pyromellitic dianhydride (PMDA) (4.7 g) was gradually added in several portions so that the temperature rise was 2 ° C or less, synthesizing a polyimide precursor solution (solid content 18 mass %) in which the polyimide precursor was dissolved. The molar ratio (TMPBPTME:PMDA) of the tetracarboxylic acid dianhydride used in the polyimide precursor was 95:5. The weight average molecular weight of the polyimide precursor was 75,000.

[0368] Under a nitrogen atmosphere, the above polyimide precursor solution (2162 g) was added to a 5 L separable flask, cooled to room temperature. Dehydrated N,N-dimethylacetamide (432 g) was added and stirred until homogenous. Next, catalysts pyridine (6.622 g) and acetic anhydride (213.67 g) were added and stirred at room temperature for 24 hours to synthesize a polyimide solution.

[0369] N,N-dimethylacetamide (DMAc) (2000 g) was added to the obtained polyimide solution and stirred until it became uniform. Next, the polyimide solution was divided into three equal parts and transferred to a 5 L beaker, and isopropyl alcohol (3500 g) was gradually added to each beaker to obtain a white slurry. The above slurry was transferred onto a Buchner funnel and filtered, and then washed with isopropyl alcohol (total 9000 g), and the process of filtering was repeated three times, and the mixture was dried at 110 ° C using a vacuum dryer to obtain polyimide (polyimide powder). The weight average molecular weight of the polyimide measured by GPC was 100,000.

[0370] A polyimide varnish (resin composition) containing 12% by mass of polyimide was prepared by adding N,N-dimethylacetamide (DMAc) to the polyimide so that the solid content of the polyimide was 12% by mass. The viscosity of the polyimide varnish (resin composition) (solid content concentration 12% by mass) at 25°C was 15000cps.

[0371] The above polyimide varnish (resin composition) was applied onto the primer layer to a predetermined thickness, and dried at 100°C for 10 minutes, at 150°C for 10 minutes, and at 230°C for 30 minutes to form a resin layer with a thickness of 5 μm to 60 μm.

[0372] [Comparative Example 1-1] A member for a display device was produced in the same manner as in Example 1-1, except that a resin layer was formed as follows.

[0373] A composition containing a urethane modified copolymer polyester resin (Vylon UR4800, manufactured by Toyobo) was applied to a predetermined thickness and dried at 100° C. for 5 minutes to form a resin layer having a thickness of 5 μm to 60 μm.

[0374] [Comparative Example 1-2] A member for a display device was produced in the same manner as in Example 1-1, except that a resin layer was formed as follows.

[0375] A composition containing an epoxy resin (1256B40, manufactured by Mitsubishi Chemical) was applied to a predetermined thickness and dried at 80° C. for 5 minutes and at 150° C. for 60 minutes to form a resin layer with a thickness of 5 μm to 60 μm.

[0376] [Comparative Example 1-3] A member for a display device was produced in the same manner as in Example 1-1, except that a resin layer was formed as follows.

[0377] 500 g of dehydrated N,N-dimethylacetamide (boiling point: 165°C) was added to the vessel, and while flowing N2 inside the vessel, the N,N-dimethylacetamide was heated to about 80°C while stirring. The amount of dissolved oxygen in the N,N-dimethylacetamide was monitored one by one, and when the amount of dissolved oxygen in the N,N-dimethylacetamide became below the detection limit of the dissolved oxygen meter (less than 0.005 mg / L), heating was stopped, and the N,N-dimethylacetamide was cooled to room temperature and then subjected to the next process.

[0378] The following steps were carried out under a nitrogen atmosphere. 466.1 g of the above N,N-dimethylacetamide and 2.46 g (10 mmol) of 1,3-bis(3-aminopropyl)tetramethyldisiloxane (AprTMOS) were placed in a 500 mL separable flask, and the temperature of the solution in which AprTMOS was dissolved was controlled at 30° C., and 1.23 g (3 mmol) of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) was gradually added so that the temperature rise was 2° C. or less, and the mixture was stirred with a mechanical stirrer for 30 minutes. 60.8g (190mmol) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) was added thereto, and after confirming that it was completely dissolved, 91.6g (206mmol) of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) was gradually added in several portions so that the temperature rise was 2°C or less, and a polyimide precursor solution (solid content 25% by weight) in which the polyimide precursor was dissolved was synthesized. The molar ratio of TFMB and AprTMOS used in the polyimide precursor was 95:5. The viscosity of the polyimide precursor solution (solid content 25% by weight) at 25°C was 48900cps, and the weight average molecular weight of the polyimide precursor measured by GPC was 156400.

[0379] Under a nitrogen atmosphere, the above polyimide precursor solution, cooled to room temperature, was added to a 5L separable flask. Dehydrated N,N-dimethylacetamide was added and stirred until homogenous. Next, pyridine and acetic anhydride, which act as catalysts, were added and stirred at room temperature for 24 hours to synthesize a polyimide solution.

[0380] N,N-dimethylacetamide (DMAc) was added to the obtained polyimide solution and stirred until it became uniform. Next, the polyimide solution was divided into three equal parts and transferred to 5 L beakers, and isopropyl alcohol was gradually added to each beaker to obtain a white slurry. The above slurry was transferred onto a Buchner funnel and filtered, then washed with isopropyl alcohol, and then filtered. This process was repeated three times, and the mixture was dried at 110°C using a vacuum dryer to obtain polyimide (polyimide powder).

[0381] A polyimide varnish (resin composition) containing 12% by mass of polyimide was prepared by adding N,N-dimethylacetamide (DMAc) to the polyimide so that the solid content of the polyimide was 12% by mass. The viscosity of the polyimide varnish (resin composition) (solid content concentration 12% by mass) at 25°C was 3000 cps.

[0382] The polyimide varnish (resin composition) was applied to a predetermined thickness on the primer layer and dried at 100°C for 10 minutes, at 150°C for 10 minutes, and at 230°C for 30 minutes to form a resin layer with a thickness of 5 μm to 60 μm.

[0383] [Rating 1] (1) Composite elastic modulus The composite elastic modulus of the resin layer of each of the display device members of the examples and comparative examples was determined.

[0384] First, the indentation hardness of the resin layer was measured. IT) was measured on the measurement sample using a "TI950 TriboIndenter" manufactured by BRUKER. Specifically, a block was prepared by embedding a display device member cut to 1 mm x 10 mm in embedding resin, and a uniform slice having a thickness of 50 nm to 100 nm without holes was cut from this block by a general slice preparation method. An "Ultramicrotome EM UC7" (manufactured by Leica Microsystems) was used to prepare the slices. The remaining block from which the uniform slice without holes was cut was used as the measurement sample. Next, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by BRUKER) was pressed vertically into the center of the cross section of the resin layer for 10 seconds under the following measurement conditions until the maximum pressing load reached 25 μN. At this time, in order to avoid the influence of the glass substrate and the side edges of the resin layer, the Berkovich indenter was pressed into a portion of the resin layer 500 nm away from the interface between the glass substrate and the resin layer toward the center of the resin layer, 500 nm away from each of the two ends of the resin layer toward the center of the resin layer, and 500 nm away from the interface between the hard coat layer and the resin layer toward the center of the resin layer. After that, the residual stress was relaxed by holding it constant, and then the load was removed over 10 seconds to measure the maximum load after relaxation, and the maximum load P max (μN) and contact projection area A p (nm 2 ) and P max / A p The indentation hardness (H IT ) was calculated. The above contact projected area was determined by correcting the indenter tip curvature by the Oliver-Pharr method using a standard sample of fused quartz (5-0098 manufactured by BRUKER). If any of the measured values ​​deviated from the arithmetic mean value by ±20% or more, the measured value was excluded and remeasured.

[0385] (Measurement conditions) ·Loading speed: 2.5μN / sec ·Holding time: 5 seconds ·Load unloading speed: 2.5μN / sec ·Measurement temperature: 25℃

[0386] Next, the indentation hardness (H IT ) is measured using the above contact projection area A p The composite elastic modulus was calculated from the above formula (1) using the above formula. The indentation hardness was measured at 10 points, the composite elastic modulus was calculated each time, and the arithmetic average value of the composite elastic moduli obtained at the 10 points was used.

[0387] (2) Impact test (pen drop test) Impact tests were carried out on the display device members of the examples and comparative examples. First, an optical adhesive (OCA) and PET were attached in this order to the surface of the glass substrate of the display device member, and the display device member was placed on a metal plate with the PET side in contact with the metal plate having a thickness of 30 mm. Next, a pen was dropped from the test height onto the display device member with its tip facing down, and the highest test height at which the glass substrate did not crack was evaluated. The results of the display device members of Examples 1-1 to 1-2 and Comparative Examples 1-1 to 1-3 are shown in FIG. 12. The results when the resin layer had a thickness of 40 μm are shown in Table 1.

[0388] (3) Pencil hardness In the display member of the examples and comparative examples, when the thickness of the resin layer was 20 μm, the pencil hardness of the surface of the hard coat layer side of the display member was measured in accordance with JIS K5600-5-4 (1999). When measuring the pencil hardness, a pencil hardness tester (product name "Pencil scratch coating hardness tester (electric type)", manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used, and the measurement conditions were an angle of 45°, a load of 750 g, a speed of 0.5 mm / sec or more and 1 mm / sec or less, and a temperature of 23±2°C.

[0389] (4) Total light transmittance and haze In the display member of the examples and comparative examples, when the thickness of the resin layer was 20 μm, the total light transmittance and haze of the display member were measured. The total light transmittance of the display member was measured using a haze meter (HM150 manufactured by Murakami Color Research Laboratory) in accordance with JIS K7361-1. The haze of the display member was measured using a haze meter (HM150 manufactured by Murakami Color Research Laboratory) in accordance with JIS K-7136.

[0390] (5) Bending resistance In the members for a display device of the Examples and Comparative Examples, when the thickness of the resin layer was 20 μm, a dynamic bending test and a static bending test were carried out on the members for a display device to evaluate bending resistance.

[0391] (5-1) Dynamic bending test A dynamic bending test was performed on the display device members of the examples and comparative examples to evaluate the bending resistance. Specifically, first, a display device member having a size of 20 mm x 100 mm was fixed to a durability tester (product name "DLDMLH-FS", manufactured by Yuasa System Devices Co., Ltd.) with the short side (20 mm) of the display device member fixed at the fixing part, and the minimum distance d between the two opposing short side parts was adjusted to 10 mm as shown in FIG. 5(c), and a dynamic bending test was performed 200,000 times in which the surface of the display device member was folded by 180°. At this time, the display device member was folded so that the surface of the hard coat layer side of the display device member was inside and the surface of the glass substrate side of the display device member was outside. In addition, a dynamic bending test was performed in the same manner as above using another display device member, in which the surface of the hard coat layer side of the display device member was folded outside and the surface of the glass substrate side of the display device member was folded inside. After the dynamic bending test, the fixed part was removed from one of the short sides to release the folded state, and the opening angle (see FIG. 6(b)), which is the angle at which the display device member naturally opens, was measured. The smaller opening angle was used between folding the display device member so that the surface on the hard coat layer side was on the inside and folding the display device member so that the surface on the hard coat layer side was on the outside.

[0392] (5-2) Static bending test A static bending test was performed on the display device members of the examples and comparative examples, and the opening angle after the static bending test was measured. Specifically, first, the short sides (20 mm) of the display device member having a size of 20 mm x 100 mm were fixed to fixing parts arranged in parallel so that the distance d between the opposing short sides of the display device member was 10 mm, and the display device member was folded and left to stand at 23 ° C. for 240 hours in a static bending test. Then, by removing the fixing part from one of the short sides after the static bending test, the folded state was opened, and the opening angle (see FIG. 6 (b)), which is the angle at which the display device member naturally opens after 30 minutes at room temperature, was measured. As the opening angle, a static bending test was performed in both cases where the display device member was folded so that the surface on the hard coat layer side was inside and where the display device member was folded so that the surface on the hard coat layer side was outside, and the smaller angle was adopted.

[0393] [Table 1]

[0394] From Table 1 and FIG. 12, in Comparative Examples 1-1 to 1-3, the composite elastic modulus of the resin layer was less than a predetermined value, so that the surface hardness of the display device member decreased when the thickness of the resin layer was increased. In contrast, in Examples 1-1 to 1-3, the composite elastic modulus of the resin layer was equal to or greater than a predetermined value, so that, for example, even when the thickness of the resin layer was 40 μm, the surface hardness was high, and it was found that both impact resistance and surface hardness could be achieved. Also, from Table 1 and FIG. 12, it was confirmed that when the composite elastic modulus of the resin layer was equal to or greater than a predetermined value, the rate of increase in impact resistance with an increase in the thickness of the resin layer was large. Also, from the comparison of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 in Table 1, it was found that when the composite elastic modulus of the resin layer was equal to or greater than a predetermined value, the bending resistance tended to improve. This is because the greater the composite elastic modulus of the resin layer, the greater the restoring force when deformation is applied to the resin layer.

[0395] Hereinafter, in Comparative Examples 2-1 to 2-2 and Examples 2-1 to 2-9, the hard coat layer formed on the third resin layer is referred to as the first hard coat layer, and the hard coat layer formed on the first resin layer is referred to as the second hard coat layer.

[0396] [Comparative Example 2-1] (1) Formation of primer layer A primer layer having a thickness of 1 μm was formed on a glass substrate in the same manner as in the formation of the primer layer in Example 1-1.

[0397] (2) Formation of the first resin layer A first resin layer having a thickness of 20 μm was formed on the primer layer in the same manner as in the formation of the resin layer in Example 1-1.

[0398] (3) Formation of the second hard coat layer A second hard coat layer having a thickness of 10 μm was formed on the first resin layer in the same manner as in the formation of the hard coat layer in Example 1-1, thereby obtaining an optical laminate.

[0399] [Comparative Example 2-2] (1) Preparation of hard coat film As the third resin layer, a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., product name A4100) was prepared, and the same hard coat layer curable resin composition as in Example 1-1 was applied onto the PET film with a bar coater to complete a coating film. The formed coating film was then dried at 100° C. for 3 minutes, and then cured by irradiating with 200 mJ of ultraviolet light to form a first hard coat layer with a thickness of 10 μm. This resulted in a hard coat film.

[0400] (2) Preparation of optical laminate A chemically strengthened glass substrate having a thickness of 70 μm was prepared, and the glass substrate and the PET film side of the hard coat film were bonded together using an acrylic adhesive film having a thickness of 50 μm (manufactured by 3M, product name 8146-2). This resulted in an optical laminate.

[0401] [Examples 2-1 to 2-8] (1) Preparation of glass-resin laminate A primer layer and a first resin layer were formed on a glass substrate in the same manner as in Comparative Example 2-1, except that the thickness of the first resin layer was set to 10 μm to 40 μm, thereby obtaining a glass resin laminate.

[0402] (2) Preparation of hard coat film A hard coat film was prepared in the same manner as in Comparative Example 2-2.

[0403] (3) Preparation of optical laminate The surface of the glass resin laminate on the first resin layer side and the surface of the hard coat film on the PET film side were bonded together using an acrylic adhesive film (manufactured by 3M, product name 8146-2) having a thickness of 10 μm to 50 μm, thereby producing an optical laminate.

[0404] [Example 2-9] (1) Preparation of glass-resin laminate A primer layer, a first resin layer, and a second hard coat layer were formed on a glass substrate in the same manner as in Comparative Example 2-1, except that the thickness of the first resin layer was 23 μm, thereby obtaining a glass resin laminate.

[0405] (2) Preparation of hard coat film A hard coat film was prepared in the same manner as in Comparative Example 2-2.

[0406] (3) Preparation of optical laminate The surface of the glass resin laminate on the second hard coat layer side and the surface of the hard coat film on the PET film side were bonded together using a 50 μm thick acrylic adhesive film (manufactured by 3M, product name 8146-2), thereby producing an optical laminate.

[0407] [Rating 2] (1) Composite elastic modulus The composite elastic modulus of the first resin layer of the optical laminate of the example and the comparative example was determined.

[0408] First, the indentation hardness of the first resin layer was measured. IT ) was measured on the measurement sample using a "TI950 TriboIndenter" manufactured by BRUKER. Specifically, first, a block was prepared by embedding an optical laminate cut to 1 mm x 10 mm in an embedding resin, and a uniform slice having a thickness of 50 nm to 100 nm without holes was cut from this block by a general slice preparation method. An "Ultramicrotome EM UC7" (manufactured by Leica Microsystems) was used to prepare the slices. The remaining block from which the uniform slice without holes was cut was used as the measurement sample. Next, in the cross section obtained by cutting out the slice in such a measurement sample, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by BRUKER) was pressed vertically into the center of the cross section of the first resin layer for 10 seconds until the maximum pressing load reached 25 μN under the following measurement conditions. At this time, in order to avoid the influence of the glass substrate and the side edges of the first resin layer, the Berkovich indenter was pressed into a portion of the first resin layer that was 500 nm away from the interface between the glass substrate and the first resin layer toward the center of the first resin layer, and 500 nm away from each of the two ends of the first resin layer toward the center of the first resin layer. After that, the pressure was held constant to relax the residual stress, and then the load was removed over 10 seconds to measure the maximum load after relaxation, and the maximum load P max (μN) and contact projection area A p (nm 2 ) and P max / A p The indentation hardness (H IT ) was calculated. The above contact projected area was determined by correcting the indenter tip curvature by the Oliver-Pharr method using a standard sample of fused quartz (5-0098 manufactured by BRUKER). If any of the measured values ​​deviated from the arithmetic mean value by ±20% or more, the measured value was excluded and remeasured.

[0409] (Measurement conditions) ·Loading speed: 2.5μN / sec ·Holding time: 5 seconds ·Load unloading speed: 2.5μN / sec ·Measurement temperature: 25℃

[0410] Next, the indentation hardness (H IT ) is measured using the above contact projection area A p The composite elastic modulus was calculated from the above formula (1) using the above formula. The indentation hardness was measured at 10 points, the composite elastic modulus was calculated each time, and the arithmetic average value of the composite elastic moduli obtained at the 10 points was used.

[0411] (2) Impact test (pen drop test) Impact tests were carried out on the optical laminates of the examples and comparative examples. First, a 50 μm thick optical adhesive film (OCA) and a 100 μm thick PET film were attached in this order to the glass substrate side surface of the optical laminate to prepare a test laminate. The test laminate was placed on a metal plate with a thickness of 30 mm so that the PET film side surface of the test laminate was in contact with the metal plate. Next, a pen was dropped from the test height onto the test laminate with its tip facing down. Zebra's Blen 0.5BAS88-BK (weight 12 g, pen tip 0.5 mmφ) was used as the pen. Table 1 shows the highest test height at which no cracks occurred in the glass substrate and the lowest test height at which cracks occurred in the glass substrate.

[0412] (3) Dynamic bending test A dynamic bending test was performed on the optical laminates of the examples and comparative examples to evaluate the bending resistance. Specifically, first, an optical laminate having a size of 20 mm x 100 mm was fixed to a durability tester (product name "DLDMLH-FS", manufactured by Yuasa System Devices Co., Ltd.) with the short side (20 mm) of the optical laminate fixed by a fixing part, and the minimum distance d between the two opposing short sides was adjusted to 10 mm or 8 mm as shown in FIG. 5(c), and a dynamic bending test was performed 200,000 times or 70,000 times in which the surface of the optical laminate was folded by 180°. At this time, the optical laminate was folded so that the surface on the hard coat layer side was the outside and the surface on the glass substrate side of the optical laminate was the inside. Then, in an environment of 25°C and 50% RH, in a bright room of 2000Lx, it was visually examined whether cracks or breaks had occurred in the bending part. The results of the dynamic bending test were evaluated according to the following criteria. A: No cracks or breaks occurred in the bent portion. B: Cracks or breaks occurred at the bent parts.

[0413] [Table 2]

[0414] In Comparative Example 2-1, the second resin layer and the third resin layer were not arranged, and therefore the impact resistance was poor. In Comparative Example 2-2, the first resin layer was not arranged, and therefore the impact resistance was poor. In contrast, in Examples 2-1 to 2-9, the predetermined first resin layer, second resin layer, and third resin layer were arranged in this order, and therefore the impact resistance was excellent. In addition, when Examples 2-1 to 2-7 are compared with Example 2-8, when the total thickness of the resin layers is equal to or less than a predetermined value, the bending resistance was also excellent. [Explanation of symbols]

[0415] 1. Display device components 2 … Glass substrate 3 ... Resin layer 4 … Hard coat layer 11 … Optical laminate 12 ... Glass substrate 13...First resin layer 14…Second resin layer 15...Third resin layer 16 … Hard coat layer

Claims

1. A glass substrate having a thickness of 15 μm or more and 100 μm or less; A resin layer disposed on one surface side of the glass substrate, the resin layer having a composite elastic modulus of 5.7 GPa or more and a thickness of 5 μm or more and 60 μm or less; The display device member according to claim 1, wherein the glass substrate is a chemically strengthened glass.

2. The member for a display device according to claim 1 , further comprising a primer layer between the glass substrate and the resin layer.

3. The member for a display device according to claim 1 , further comprising a functional layer on a surface of the resin layer opposite to the glass substrate.

4. The display device member according to claim 3 , wherein the functional layer is a hard coat layer.

5. The member for a display device according to any one of claims 1 to 4, which has a total light transmittance of 80% or more.

6. The display member according to any one of claims 1 to 5, having a haze of 2.0% or less.

7. The display device member according to claim 1 , wherein the resin layer contains polyimide or polyamideimide.

8. 8. The display device member according to claim 7, wherein the weight average molecular weight of the polyimide is 100,000 or more and 270,000 or less.

9. 8. The display device member according to claim 7, wherein the weight average molecular weight of the polyamideimide is 50,000 or more and 1,000,000 or less.

10. An optical laminate having a glass substrate, a first resin layer, a second resin layer, and a third resin layer in this order, The thickness of the glass substrate is 15 μm or more and 100 μm or less, The composite elastic modulus of the first resin layer is 5.7 GPa or more, and the thickness of the first resin layer is 5 μm or more and 60 μm or less, The second resin layer is an adhesive layer, The optical laminate, wherein the third resin layer is a resin film containing a resin selected from the group consisting of polyester-based resins, polycycloolefin-based resins, acetyl cellulose-based resins, polycarbonate-based resins, and polypropylene-based resins.

11. The optical laminate according to claim 10 , wherein a total thickness of the resin layers disposed on the side of the glass substrate facing the first resin layer is 143 μm or less.

12. The optical laminate according to claim 10 or 11, further comprising a functional layer on a surface of the third resin layer opposite to the second resin layer.

13. The optical laminate according to claim 12 , wherein the functional layer is a hard coat layer.

14. The optical laminate according to any one of claims 10 to 13, which has a total light transmittance of 80% or more.

15. The optical laminate according to any one of claims 10 to 14, having a haze of 2.0% or less.

16. The optical laminate according to claim 10 , wherein the first resin layer contains polyimide or polyamideimide.

17. The optical laminate according to claim 16, wherein the weight average molecular weight of the polyimide is 100,000 or more and 270,000 or less.

18. The optical laminate according to claim 16, wherein the weight average molecular weight of the polyamideimide is 50,000 or more and 1,000,000 or less.

19. A display panel; A member for a display device according to any one of claims 1 to 9 or an optical laminate according to any one of claims 10 to 18, which is disposed on a viewer side of the display panel; A display device comprising:

20. 20. The display device of claim 19, which is foldable.

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