Laminated materials and display devices

Abstract

The present invention provides a laminate comprising a glass substrate, a bonding layer, and a hard coating film in sequence. The hard coating film comprises a substrate layer and a hard coating layer from the bonding layer side. The bonding layer is a layer that bonds the glass substrate to the substrate layer. The thickness of the glass substrate is 10 μm or more and 100 μm or less. When the thickness of the hard coating layer is set as A, the thickness of the substrate layer is set as B, and the thickness of the bonding layer is set as C, the ratio of (A+B) to C is 3.0 or more and 500 or less.

Description

Technical Field

[0001] The present invention relates to a laminate having a glass substrate and a display device using the laminate. Background Technology

[0002] Thin flat glass boasts excellent hardness and heat resistance, but it also presents challenges such as difficulty in bending and susceptibility to breakage upon drop. Therefore, in recent years, the development of ultra-thin glass (UTG)—glass that can be bent by thinning the glass—has been ongoing. Among glass types, those with particularly high bending resistance are known as chemically strengthened glass. By incorporating expansion stress into the glass surface, tiny scratches on the surface are prevented from amplifying during bending, thus reducing the glass's susceptibility to breakage.

[0003] For example, flexibility is required in the display field. In recent years, the development of flexible displays, such as foldable displays, rollable displays, and bendable displays, has been actively underway. Among these, the development of foldable displays, i.e., bendable display devices, is progressing. The use of ultra-thin glass in such flexible displays is being researched (e.g., Patent Documents 1-5).

[0004] For example, Patent Document 1 proposes a laminated body having a glass plate with a thickness of less than 150 μm and a resin film laminated by an adhesive layer, and a bending durability of 10 or more based on the following test.

[0005] Bending durability test: The action of bending the laminate 180° with a bending radius of 3mm in the direction of concavity of the glass plate from the stretched state is regarded as 1 group. The above action is performed at a rate of 43 groups per minute. The number of groups until cracks appear in the laminate is used as the index of bending durability.

[0006] In addition, for example, Patent Document 2 proposes a laminate having a structure in which a glass plate with a thickness of less than 150 μm and a resin film are laminated together by an adhesive layer. The storage modulus of the adhesive layer at 20°C, as measured by a dynamic viscoelasticity measuring device, is 10 MPa or more, and the flexural durability based on the following test is 10 or more.

[0007] Bending durability test: The action of bending the laminate 180° with a bending radius of 3mm in the direction of concavity of the glass plate from the stretched state is regarded as 1 group. The above action is performed at a rate of 43 groups per minute. The number of groups until cracks appear in the laminate is used as the index of bending durability.

[0008] Additionally, for example, Patent Document 3 discloses a glass article which is a chemically strengthened ultrathin glass article with a thickness of less than 0.4 mm, having a fracture height (in mm) greater than the value obtained by multiplying the thickness (t) (t(mm)) of the glass article by 50, and further having a fracture bending radius (in mm) less than the value obtained by multiplying the thickness (t(mm)) of the article by 100000 and dividing by the value of the surface compressive pressure (MPa) measured on the first surface, and also includes a laminated polymer layer.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2019-25899

[0012] Patent Document 2: Japanese Patent Application Publication No. 2019-25900

[0013] Patent Document 3: Japanese Patent Publication No. 2020-521699

[0014] Patent Document 4: Japanese Patent Publication No. 2019-504812

[0015] Patent Document 5: Japanese Patent No. 6544134 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] Glass can be bent by thinning, improving its bending resistance, but it also becomes more prone to breakage, drastically reducing its impact resistance. If glass breaks due to external impact, using glass as a cover component of a display device will not only reduce the device's functionality but may also injure the user's fingertips due to the resulting shards and sharp edges.

[0018] The present invention was made in view of the above-mentioned actual situation, and its main purpose is to provide a laminate with good bending resistance and impact resistance, and improved safety.

[0019] Methods for solving problems

[0020] One embodiment of the present invention provides a laminate comprising a glass substrate, a bonding layer, and a hard coating film in sequence. The hard coating film has a substrate layer and a hard coating layer from the bonding layer side. The bonding layer is a layer that bonds the glass substrate to the substrate layer. The thickness of the glass substrate is 10 μm or more and 100 μm or less. When the thickness of the hard coating layer is set as A, the thickness of the substrate layer is set as B, and the thickness of the bonding layer is set as C, the ratio of (A+B) to C is 3.0 or more and 500 or less.

[0021] Furthermore, in this invention, the composite elastic modulus of the above-mentioned bonding layer is preferably 1 MPa or more and 6000 MPa or less.

[0022] Furthermore, in this invention, the glass transition temperature of the aforementioned bonding layer is preferably between -40°C and 150°C.

[0023] Furthermore, in this invention, the composite elastic modulus of the substrate layer is preferably 5.7 GPa or higher.

[0024] Furthermore, in this invention, the glass substrate is preferably chemically strengthened glass.

[0025] In addition, in this invention, the bonding layer is preferably a pressure-sensitive adhesive layer, or a heat-sensitive adhesive layer, or a cured product containing a curable adhesive composition.

[0026] In addition, in this invention, the bonding layer preferably contains at least one selected from the group consisting of polyester resin, polyolefin resin and urethane resin.

[0027] Furthermore, the laminate in this invention can have an anti-reflective layer on the side of the hard coating opposite to the substrate layer.

[0028] Furthermore, in the laminate of the present invention, preferably, no cracks, breaks or peeling occur when the laminate is repeatedly bent 180° 200,000 times with the glass substrate side of the laminate as the outer side, the hard coating side of the laminate as the inner side, and the opposing edges of the laminate spaced 10 mm apart.

[0029] Another embodiment of the present invention provides a laminate having, in sequence, a hard coating layer, a substrate layer, a bonding layer, a glass substrate and a second bonding layer, wherein the bonding layer is a layer that bonds the glass substrate to the substrate layer, the second bonding layer is a layer that bonds the laminate to other components, the thickness of the glass substrate is 10 μm or more and 100 μm or less, and the laminate satisfies the following formula (1).

[0030] 0.001≤{(E1×D1 2 +E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (1)

[0031] (In the above formula (1), E1 represents the composite elastic modulus (GPa) of the hard coating, D1 represents the thickness (mm) of the hard coating, E2 represents the composite elastic modulus (GPa) of the substrate layer, D2 represents the thickness (mm) of the substrate layer, E3 represents the composite elastic modulus (GPa) of the bonding layer, D3 represents the thickness (mm) of the bonding layer, E4 represents the composite elastic modulus (GPa) of the glass substrate, D4 ​​represents the thickness (mm) of the glass substrate, E5 represents the storage modulus (GPa) of the second bonding layer, D5 represents the thickness (mm) of the second bonding layer.)

[0032] Another embodiment of the present invention is a laminate having a substrate layer, a bonding layer, a glass substrate and a second bonding layer in sequence, wherein the bonding layer is a layer that bonds the glass substrate to the substrate layer, the second bonding layer is a layer that bonds the laminate to other components, the thickness of the glass substrate is 10 μm or more and 100 μm or less, and the laminate satisfies the following formula (2).

[0033] 0.001≤{(E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (2)

[0034] (In the above formula (2), E2 represents the composite elastic modulus of the substrate layer (GPa), D2 represents the thickness of the substrate layer (mm), E3 represents the composite elastic modulus of the bonding layer (GPa), D3 represents the thickness of the bonding layer (mm), E4 represents the composite elastic modulus of the glass substrate (GPa), D4 represents the thickness of the glass substrate (mm), E5 represents the storage modulus of the second bonding layer (GPa), D5 represents the thickness of the second bonding layer (mm).)

[0035] Furthermore, in the laminate of the present invention, the glass transition temperature of the second bonding layer is preferably -50°C or higher and 30°C or lower.

[0036] In addition, the laminate of the present invention may have a protective film on the side of the hard coating opposite to the substrate layer.

[0037] Another embodiment of the present invention provides a display device comprising: a display panel; and the aforementioned laminate disposed on the observer side of the display panel, wherein the laminate is configured such that the surface of the glass substrate side is adjacent to the display panel.

[0038] The display device in this invention is preferably a foldable display.

[0039] The effects of the invention

[0040] This invention provides laminates with good bending and impact resistance, as well as improved safety. Attached Figure Description

[0041] Figure 1 This is a schematic cross-sectional view illustrating the laminate in this invention.

[0042] Figure 2 This is a schematic cross-sectional view illustrating the laminate in this invention.

[0043] Figure 3 This is a schematic cross-sectional view illustrating the laminate in this invention.

[0044] Figure 4 This is a schematic cross-sectional view illustrating the laminate in this invention.

[0045] Figure 5 This is a schematic diagram used to illustrate a dynamic bending test.

[0046] Figure 6 This is a schematic diagram used to illustrate a static bending test.

[0047] Figure 7 This is a schematic cross-sectional view illustrating the laminate in this invention.

[0048] Figure 8 This is a schematic cross-sectional view illustrating the laminate in this invention.

[0049] Figure 9 This is a schematic cross-sectional view illustrating the display device of the present invention.

[0050] Figure 10 It is a graph showing the relationship between the middle value of equation (1) and the test height of the pen drop test.

[0051] Figure 11 It is a graph showing the relationship between the middle value of equation (2) and the test height of the pen drop test. Detailed Implementation

[0052] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the present invention can be implemented in many different ways and is not to be construed as limited to the embodiments illustrated below. Furthermore, to make the description clearer, the drawings sometimes schematically represent the width, thickness, shape, etc., of various parts compared to the actual situation; however, these are always examples and are not intended to limit the interpretation of the present invention. In addition, in this specification and the accompanying drawings, the same reference numerals are used for elements identical to those described in the previously mentioned drawings, and detailed descriptions are appropriately omitted.

[0053] In this specification, when describing the arrangement of other components above a component, the use of only "above" or "below" includes, unless otherwise specified, both the case where the other component is arranged directly above or below the component in contact with it, and the case where the other component is arranged above or below the component, further separated by another component. Similarly, in this specification, when describing the arrangement of another component on the surface of a component, the use of only "surface side" or "surface" includes, unless otherwise specified, both the case where the other component is arranged directly above or below the component in contact with it, and the case where the other component is arranged above or below the component, further separated by another component.

[0054] The laminate and display device of the present invention will now be described in detail.

[0055] A. Laminar structures

[0056] The laminate in this invention has three embodiments. These embodiments will be described below.

[0057] I. First Implementation

[0058] The inventors of this invention conducted in-depth research on laminates having a glass substrate and discovered that by depositing a resin layer on the surface of a thin glass substrate, thereby increasing the thickness of the resin layer, cracking of the glass substrate can be suppressed and impact resistance improved. However, it has been found that when a thicker resin layer is formed by coating the surface of the glass substrate with a resin composition, the effect of the shrinkage difference between the glass substrate and the resin layer becomes greater during heating or curing after the resin composition is applied, sometimes resulting in curling. Furthermore, the inventors of this invention conducted further repeated research and discovered that by pre-filming the resin layer and then bonding the resin film to the surface of a thin glass substrate via an adhesive layer, impact resistance can be further improved while suppressing curling. However, it was found that in such laminates, the surface hardness of the resin film side of the laminate decreases, and damage resistance sometimes decreases.

[0059] This embodiment is based on the above-mentioned actual situation, and its purpose is to provide a laminate with good bending resistance, impact resistance and damage resistance, and improved safety.

[0060] The first embodiment of the laminate of the present invention sequentially comprises a glass substrate, a bonding layer, and a hard coating film. The hard coating film has a substrate layer and a hard coating layer from the bonding layer side. The thickness of the glass substrate is 10 μm or more and 100 μm or less. When the thickness of the hard coating layer is set as A, the thickness of the substrate layer is set as B, and the thickness of the bonding layer is set as C, the thickness ratio (A+B) / C is 3.0 or more and 500 or less. That is, the laminate of this embodiment sequentially comprises a glass substrate, a bonding layer, and a hard coating film. The hard coating film has a substrate layer and a hard coating layer from the bonding layer side. The bonding layer is a layer that bonds the glass substrate to the substrate layer. The thickness of the glass substrate is 10 μm or more and 100 μm or less. When the thickness of the hard coating layer is set as A, the thickness of the substrate layer is set as B, and the thickness of the bonding layer is set as C, the ratio of (A+B) to C is 3.0 or more and 500 or less.

[0061] Figure 1 This is a schematic cross-sectional view illustrating an example of a laminated body in this embodiment. (See diagram below.) Figure 1 As shown, the laminate 1 sequentially comprises a glass substrate 2 having a specified thickness, a bonding layer 3, and a hard coating film 4. The hard coating film 4 has a substrate layer 5 and a hard coating layer 6 from the side of the bonding layer 3. Furthermore, when the thickness of the hard coating layer 6 is set as A, the thickness of the substrate layer 5 is set as B, and the thickness of the bonding layer 3 is set as C, the thickness ratio (A+B) / C is within a specified range.

[0062] In this embodiment, the thickness of the glass substrate is less than a specified value and relatively thin, thus improving flexural strength. On the other hand, a glass substrate that is less than a specified value and relatively thin may be prone to breakage and have low impact resistance. In contrast, in this embodiment, by applying a hard coating to one side of the glass substrate via an adhesive layer, it is possible to improve impact resistance while maintaining good flexural strength.

[0063] Furthermore, in the laminate of this embodiment, when the thickness of the hard coating layer is set to A, the thickness of the substrate layer is set to B, and the thickness of the bonding layer is set to C, by keeping the thickness ratio (A+B) / C within a specified range, the surface hardness of the hard coating side of the laminate can be increased, thereby improving damage resistance. The reason for this is speculated as follows.

[0064] In this embodiment, the thickness ratio (A+B) / C is 3.0 or higher, and the thickness of the bonding layer is relatively thin compared to the combined thickness of the hard coating layer and the substrate layer. While the bonding layer typically has a lower hardness than the glass substrate and the hard coating, by making the bonding layer relatively thin, the influence of the bonding layer's hardness can be reduced, thereby increasing the surface hardness of the hard coating side of the laminate. As a result, damage resistance can be improved.

[0065] It should be noted that the inventors of this invention have conducted in-depth research and found that, as described in the embodiments and comparative examples below, even when the thickness of the bonding layer is relatively thin, the surface hardness of the hard coating side of the laminate is sometimes low. Furthermore, it has been found that, in order to improve the surface hardness of the hard coating side of the laminate, it is important to make the thickness of the bonding layer relatively thin, that is, to make the ratio of the aforementioned thicknesses (A+B) / C a predetermined value or higher.

[0066] Thus, in this embodiment, good bending resistance is maintained while also considering impact resistance and damage resistance. Furthermore, even if the glass substrate in the laminate breaks, the risk of injury to the human body is reduced, enabling the creation of a highly safe laminate. Therefore, the laminate of this embodiment is bendable and can be used for a wide variety of applications. For example, the laminate of this embodiment can be used in a variety of display devices; specifically, it can be used as a component for foldable displays.

[0067] The following describes the various components of the laminate in this embodiment.

[0068] 1. Thickness ratio

[0069] In this embodiment, when the thickness of the hard coating layer is set as A, the thickness of the substrate layer is set as B, and the thickness of the bonding layer is set as C, the thickness ratio (A+B) / C is 3.0 or more, preferably 4.0 or more, and more preferably 5 or more. By setting the thickness ratio within the above range, the surface hardness of the hard coating side of the laminate can be improved, thus enhancing damage resistance. On the other hand, the thickness ratio (A+B) / C is 500 or less, preferably 150 or less, more preferably 100 or less, further preferably 70 or less, and particularly preferably 40 or less. If the thickness ratio is too large, the thickness of the bonding layer becomes relatively very thin, which may weaken the adhesion, reduce the bending resistance, especially the dynamic bending resistance, and potentially reduce the impact resistance. The thickness ratio (A+B) / C is 3.0 or more and 500 or less, preferably 4.0 or more and 150 or less, more preferably 5 or more and 100 or less, further preferably 5 or more and 70 or less, and particularly preferably 5 or more and 40 or less.

[0070] The thickness of the hard coating is not particularly limited as long as it meets the above-mentioned thickness ratio, and can be appropriately selected according to the function of the hard coating and the application of the laminate. The thickness of the hard coating is, for example, 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. By making the thickness of the hard coating within the above range, the surface hardness of the hard coating side of the laminate can be improved, thus improving damage resistance. On the other hand, the thickness of the hard coating is, for example, 50 μm or less, preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. By making the thickness of the hard coating within the above range, good bending resistance can be obtained. The thickness of the hard coating is, for example, 1 μm or more and 50 μm or less, preferably 3 μm or more and 30 μm or less, more preferably 5 μm or more and 25 μm or less, and even more preferably 10 μm or more and 20 μm or less.

[0071] The thickness of the substrate layer is not particularly limited as long as it meets the aforementioned thickness ratio, for example, it is 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. By making the substrate layer thickness within the above range, impact resistance can be improved. On the other hand, the thickness of the substrate layer is, for example, 150 μm or less, preferably 125 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. By making the substrate layer thickness within the above range, good bending resistance can be obtained. The thickness of the substrate layer is, for example, 10 μm or more and 150 μm or less, preferably 15 μm or more and 125 μm or less, more preferably 20 μm or more and 100 μm or less, and even more preferably 25 μm or more and 85 μm or less.

[0072] The thickness of the bonding layer is not particularly limited as long as it meets the above-mentioned thickness ratio, for example, it is 25 μm or less, preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. By making the thickness of the bonding layer within the above range, the surface hardness of the hard coating side of the laminate can be improved, thus improving damage resistance. In addition, by making the thickness of the bonding layer relatively thin as described above, the texture and feel of the glass from the glass substrate can be maintained. On the other hand, the thickness of the bonding layer is, for example, 0.2 μm or more, preferably 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 1.5 μm or more, and particularly preferably 2.0 μm or more. If the thickness of the bonding layer is too thin, the adhesion may weaken, the bending resistance, especially the dynamic bending resistance, may decrease, and the impact resistance may decrease. The thickness of the bonding layer is, for example, 0.2 μm or more and 25 μm or less, preferably 0.5 μm or more and 20 μm or less, more preferably 1.0 μm or more and 15 μm or less, further preferably 1.5 μm or more and 10 μm or less, and particularly preferably 2.0 μm or more and 10 μm or less.

[0073] Here, the thickness of each layer can be the arithmetic mean of the thicknesses at any 10 points obtained from cross-section measurements along the thickness direction of the laminate observed using a scanning electron microscope (SEM). The specific method for taking cross-sectional photographs is as follows: First, cut the laminate into 2cm × 2cm pieces to create blocks encapsulated in embedding resin, and prepare the cross-section using a grinder. A TegraPol-35 grinder manufactured by Struers can be used. Then, take cross-sectional photographs of the sample using a scanning electron microscope. A Hitachi High-Tech S-4800 scanning electron microscope can be used. When taking cross-sectional photographs using a scanning electron microscope (Hitachi High-Tech S-4800), set the detector to "Lower," the accelerating voltage to "3kV," and the emission current to "10μA" for cross-sectional observation. Regarding magnification, adjust the focal length and, while observing whether the layers can be distinguished, appropriately adjust the contrast and brightness within a range of 100x to 100,000x, preferably 1,000x to 50,000x, and even more preferably 5,000x to 10,000x. It should be noted that when taking cross-sectional photographs using a scanning electron microscope (Hitachi High-Tech S-4800), the beam monitoring aperture can be further set to "1", the objective aperture to "3", and the WD to "8mm". Additionally, the contrast of the interface is sometimes difficult to determine at high magnification. In this case, observe at low magnification simultaneously. For example, observe at two magnifications: 2000x and 10,000x, and 5000x and 20,000x. Then, calculate the arithmetic mean of the cross-sectional photographs at both magnifications, and use this average as the thickness of each layer. It should be noted that, unless otherwise stated, the method for measuring the thickness of other layers in a laminate can be the same.

[0074] 2. Bonding layer

[0075] In this embodiment, the bonding layer is disposed between the glass substrate and the hard coating film and is used to bond the glass substrate and the hard coating film.

[0076] As for the materials used in the bonding layer, there are no particular limitations as long as they can bond the glass substrate and the hard coating. Examples include pressure-sensitive adhesives such as optically clear adhesives (OCA), heat-sensitive adhesives such as heat sealants, and curing adhesives. They can be used alone or in combination of two or more.

[0077] Pressure-sensitive adhesives such as optically transparent adhesives (OCA) include, for example, acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, vinyl acetate adhesives, and polyvinyl butyral (PVB) adhesives.

[0078] As heat-sensitive adhesives such as heat sealants, thermoplastic resins capable of heat-melting can be used, for example. There are no particular limitations on such thermoplastic resins; examples include acrylic resins, vinyl chloride-vinyl acetate copolymers, polyamide resins, polyester resins, polyester urethane resins, chlorinated polypropylene, chlorinated rubber, urethane resins, epoxy resins, styrene resins, polyolefin resins, silicone resins, polyvinyl butyral (PVB) and other polyvinyl acetal resins, polyether urethane resins, etc. These thermoplastic resins can be used alone or in combination of two or more.

[0079] Furthermore, the heat-sensitive adhesive composition may further contain a curing agent. This improves heat resistance and adhesion. Additionally, by adding a curing agent, the composite elastic modulus of the bonding layer described later can be adjusted. To produce a bonding layer with the desired composite elastic modulus, it is preferable, for example, to appropriately add a curing agent based on the characteristics of the aforementioned thermoplastic resin. Examples of curing agents include isocyanate-based curing agents, epoxy-based curing agents, and melamine-based curing agents. Curing agents can be used alone or in combination of two or more. When the heat-sensitive adhesive composition contains a curing agent, the bonding layer contains a cured product of the heat-sensitive adhesive composition.

[0080] In addition, the heat-sensitive adhesive composition may contain additives as needed. Examples of additives include, for instance, light stabilizers, ultraviolet absorbers, infrared absorbers, antioxidants, plasticizers, coupling agents, defoamers, fillers, inorganic or organic particles for adjusting refractive index, antistatic agents, colorants such as blue or purple pigments, leveling agents, surfactants, slip agents, various sensitizers, flame retardants, tackifiers, polymerization inhibitors, and surface modifiers. These additives can be appropriately selected from commonly used additives. The content of the additives can be appropriately set. To improve adhesion to the glass substrate, the heat-sensitive adhesive composition preferably contains a silane coupling agent.

[0081] Examples of curing adhesives include thermosetting adhesives and UV-curing adhesives.

[0082] Thermosetting adhesives are adhesives that cure by heating. Examples of thermosetting adhesives include epoxy adhesives, acrylic adhesives, urethane adhesives, polyester adhesives, and silicone adhesives.

[0083] UV-curable adhesives are adhesives that cure when exposed to ultraviolet light. Examples of UV-curable adhesives include epoxy adhesives, acrylic adhesives, and urethane acrylate adhesives.

[0084] In addition, curing adhesive compositions may contain additives as needed. Examples of additives include, for instance, light stabilizers, UV absorbers, infrared absorbers, antioxidants, plasticizers, coupling agents, defoamers, fillers, inorganic or organic particles for adjusting refractive index, antistatic agents, colorants such as blue or purple pigments, leveling agents, surfactants, slip agents, various sensitizers, flame retardants, tackifiers, polymerization inhibitors, and surface modifiers. These additives can be appropriately selected from commonly used additives. The content of the additives can be appropriately set.

[0085] The material used in the bonding layer is preferably a heat-sensitive adhesive or a curing adhesive, more preferably a heat-sealing agent, a UV-curing adhesive, or a thermosetting adhesive. That is, the bonding layer is preferably a heat-sensitive adhesive layer, or a cured product containing a curing adhesive composition, more preferably a heat-sealing layer, or a cured product containing a UV-curing adhesive composition or a thermosetting adhesive composition. By using a heat-sealing agent, a UV-curing adhesive, or a thermosetting adhesive, a bonding layer that satisfies the composite elastic modulus described later can be obtained, and the glass transition temperature of the bonding layer described later can be 0°C or higher. Furthermore, in the case of optically clear adhesives (OCA), an OCA film is used, but the OCA film has a surface with unevenness. When using such an OCA film, the unevenness can cause image wobbling, potentially damaging the texture and feel of the glass substrate. In contrast, by using a heat-sensitive adhesive or a curing adhesive, this adverse condition can be suppressed.

[0086] Furthermore, the bonding layer preferably contains at least one resin selected from the group consisting of polyester resin, polyolefin resin, and urethane resin. More preferably, the bonding layer contains a polyester resin. It should be noted that urethane resin also includes polyester urethane resin and polyether urethane resin. A bonding layer containing this material allows for easy adjustment of the composite elastic modulus (described later) to a preferred range.

[0087] The composite elastic modulus of the bonding layer is preferably 1 MPa or more, more preferably 10 MPa or more, and even more preferably 20 MPa or more. By making the composite elastic modulus of the bonding layer within the above range and having a certain degree of hardness, the surface hardness of the hard coating side of the laminate can be improved, thus improving damage resistance and impact resistance. On the other hand, the composite elastic modulus of the bonding layer is preferably 6000 MPa or less, more preferably 5500 MPa or less, and even more preferably 4500 MPa or less. If the composite elastic modulus of the bonding layer is too large, the adhesion becomes too weak or the hardness becomes too high, making it difficult to bend, and the bending resistance, especially the dynamic bending resistance, may decrease. The composite elastic modulus of the bonding layer is preferably 1 MPa or more and 6000 MPa or less, more preferably 10 MPa or more and 5500 MPa or less, even more preferably 20 MPa or more and 4500 MPa or less, and particularly preferably 25 MPa or more and 4000 MPa or less.

[0088] Here, the composite elastic modulus of the bonding layer is used to determine the indentation hardness (H) of the bonding layer. IT The contact projected area A is calculated at time ) p The "indentation hardness" is calculated from the load-displacement curve of the indenter obtained by hardness measurement using nanoindentation. The composite elastic modulus of the bonding layer is the elastic modulus that includes the elastic deformation of the bonding layer and the elastic deformation of the indenter.

[0089] Indentation hardness (H) ITIn the measurement, the "TI950 TriboIndenter" manufactured by BRUKER Corporation was used to measure the sample. Specifically, firstly, a block was prepared by embedding a 1mm × 10mm laminate with embedding resin. Then, a uniform slice with a thickness of 50nm to 100nm and no pores was cut from this block using a general slicing method. The slices can be prepared using an "Ultramicrotome EM UC7" (manufactured by Leica Microsystems). Then, the block remaining after the uniform slice without pores was cut was used as the measurement sample. Next, in the cross-section obtained by cutting the above-mentioned slice from this measurement sample, under the following measurement conditions, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by BRUKER Corporation) was vertically pressed into the center of the cross-section of the bonding layer with a maximum indentation load of 25μN for 10 seconds. Here, to avoid the influence of the glass substrate and hard coating film, and to avoid the influence of the side edges of the bonding layer, the Burkevich indenter is pressed into a portion of the bonding layer that is 500 nm from the interface between the glass substrate and the bonding layer towards the center of the bonding layer, and 500 nm from the interface between the hard coating film and the bonding layer towards the center of the bonding layer, and 500 nm from each side of the bonding layer towards the center of the bonding layer. Afterwards, it is held in place to alleviate residual stress, and then unloaded after 10 seconds. The maximum load after relief is measured, and this maximum load P is used. max (μN) and contact projected area A p (nm 2 ), through P max / A p Calculate the indentation hardness (H) IT The contact projected area mentioned above is the contact projected area corrected for the indenter tip curvature using fused silica (BRUKER 5-0098) of a standard specimen corrected for the indenter tip curvature using the Oliver-Pharr method. Indentation hardness (H...) IT The result is the arithmetic mean of the values ​​obtained from measuring 10 sites. It should be noted that if any measured value deviates from the arithmetic mean by more than ±20%, that value should be removed and the measurement repeated. To determine whether a value deviates from the arithmetic mean by more than ±20%, when the measured value is designated as A and the arithmetic mean as B, the result is determined by whether the percentage calculated from (AB) / B × 100 is greater than ±20%.

[0090] (Measurement Condition 1)

[0091] • Loading speed: 2.5 μN / s

[0092] • Duration: 5 seconds

[0093] • Unloading speed: 2.5 μN / sec

[0094] • Measurement temperature: 25℃

[0095] It should be noted that when measuring indentation hardness under the above-described measurement condition 1, if the indentation depth under the maximum load is 500 nm or more, the measurement should be changed to the following measurement condition 2. As mentioned above, in the measurement of indentation hardness, the bonding layer is indented for 10 seconds. Therefore, the maximum load is 25 μN under measurement condition 1 and 5 μN under measurement condition 2.

[0096] (Measurement Condition 2)

[0097] • Loading speed: 0.5 μN / s

[0098] • Duration: 5 seconds

[0099] • Unloading speed: 0.5 μN / sec

[0100] • Measurement temperature: 25℃

[0101] Composite elastic modulus E of the bonding layer r The contact projected area A, calculated using the following formula (3) during the determination of indentation hardness, is... p The composite elastic modulus is then calculated. For the composite elastic modulus, the indentation hardness is measured at 10 locations, and the composite elastic modulus is calculated for each location. The result is the arithmetic mean of the composite elastic moduli obtained at the 10 locations.

[0102] [Number 1]

[0103]

[0104] (In the above equation (3), A p E is the contact projection area. r (where S is the composite elastic modulus of the bonding layer and S is the contact stiffness.)

[0105] The composite elastic modulus of the bonding layer can be adjusted, for example, according to the type or composition of the materials contained in the bonding layer.

[0106] Furthermore, the glass transition temperature of the bonding layer is preferably -40°C or higher, more preferably -30°C or higher, even more preferably -10°C or higher, even more preferably 0°C or higher, and particularly preferably 20°C or higher. If the glass transition temperature of the bonding layer is within the above range, it is easy to obtain a bonding layer that satisfies the aforementioned composite elastic modulus. Additionally, when the glass transition temperature of the bonding layer is 0°C or higher, damage resistance and impact resistance can be further improved. On the other hand, the glass transition temperature of the bonding layer is preferably 150°C or lower, more preferably 140°C or lower, even more preferably 130°C or lower, and even more preferably 120°C or lower. If the glass transition temperature of the bonding layer is too high, adhesion may not be guaranteed. The glass transition temperature of the bonding layer is preferably -40°C or higher to 150°C or lower, more preferably -30°C or higher to 150°C or lower, even more preferably -10°C or higher to 140°C or lower, particularly preferably 0°C or higher to 130°C or lower, and most preferably 0°C or higher to 120°C or lower. Furthermore, the glass transition temperature of the bonding layer is preferably between -40°C and 25°C, and between 50°C and 150°C. This allows for the production of laminates that can withstand use in high-temperature, high-humidity, and low-temperature environments.

[0107] Here, the glass transition temperature of the bonding layer refers to the value determined by the method based on the peak value of the loss tangent (tanδ) (DMA method). When determining the storage modulus E', loss modulus E”, and loss tangent tanδ of the bonding layer using a dynamic viscoelasticity measuring apparatus (DMA), the bonding layer is first punched into a 15mm × 200mm piece. Alternatively, a solution can be prepared by dissolving or melting the bonding layer material. After coating the solution onto a substrate and drying it, the film is peeled off from the substrate, thereby obtaining a test piece of the bonding layer. The solvent is appropriately selected depending on the bonding layer material; examples include ethyl acetate. Furthermore, when preparing the above solution, the bonding layer material can be appropriately heated to dissolve it. For example, a NAFLON (registered trademark) sheet (300mm × 300mm × 1mm thick) manufactured by NICHIAS can be used as the substrate. Then, according to becoming... The bonding layer is sampled in a cylindrical shape with a height of approximately 5 mm. This can be achieved by winding the bonding layer into a cylindrical shape. The compression clamp (parallel plate) of the dynamic viscoelasticity measuring device is used. The cylindrical test sample described above is installed between the points ( ). Then, a compressive load is applied, and longitudinal vibration at a frequency of 1 Hz is applied. Dynamic viscoelasticity is measured within a range of -50°C to 200°C. The storage modulus E', loss modulus E”, and loss tangent tanδ of the bonding layer are measured at each temperature. The glass transition temperature of the bonding layer is the temperature at which the loss tangent tanδ reaches its peak value within a range of -50°C to 200°C. For example, an RSAIII manufactured by TA Instruments can be used as the dynamic viscoelasticity measuring device. It should be noted that the specific measurement conditions in the above method are as follows.

[0108] (Conditions for determining glass transition temperature)

[0109] • Sample to be measured: × Cylindrical shape with a height of 5mm

[0110] • Measuring fixture: Compression (parallel plate)

[0111] • Measurement mode: Temperature dependent (Temperature range: -50℃~200℃, Heating rate: 5℃ / min)

[0112] • Frequency: 1Hz

[0113] When the laminate of this embodiment is used, for example, in a display device, the bonding layer preferably has transparency. Specifically, the total light transmittance of the bonding layer is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more.

[0114] Here, the total light transmittance of the bonding layer can be measured according to JIS K7361-1, for example, using a haze meter HM150 manufactured by the Murakami Color Technology Laboratory. The method for measuring the total light transmittance of other layers can be the same.

[0115] In addition, the haze of the bonding layer is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less.

[0116] Here, the haze of the bonding layer can be measured according to JIS K-7136, for example, using a haze meter HM150 manufactured by Murakami Color Technology Laboratory. The method for measuring the haze of other layers can be the same.

[0117] The method of bonding the glass substrate and the hard coating film using an adhesive layer is appropriately selected depending on the materials used in the adhesive layer. For example, in the case of pressure-sensitive adhesives such as optically transparent adhesives (OCA), a film-like pressure-sensitive adhesive layer can be used to bond the hard coating film and the glass substrate. Alternatively, in the case of heat-sensitive adhesives such as heat sealants, a heat-sensitive adhesive composition can be applied to the substrate side of the hard coating film or one side of the glass substrate, dried to form a heat-sensitive adhesive layer, and then the hard coating film and the glass substrate are overlapped through the heat-sensitive adhesive layer. Heating is then performed to heat-melt the adhesive layer, thereby achieving bonding. In this case, the heating temperature is preferably above the glass transition temperature of the heat-sensitive adhesive layer. Alternatively, in the case of thermosetting adhesives, a thermosetting adhesive composition can be applied to the substrate side of the hard coating film or one surface of the glass substrate, dried to form a thermosetting adhesive layer, and then the hard coating film and the glass substrate are overlapped through the thermosetting adhesive layer. Heating is then applied to cure the thermosetting adhesive layer, thereby achieving bonding. Alternatively, in the case of UV-curable adhesives, a UV-curable adhesive composition can be applied to the substrate side of the hard coating film or one surface of the glass substrate, dried to form a UV-curable adhesive layer, and then the hard coating film and the glass substrate are overlapped through the UV-curable adhesive layer. UV light is then irradiated to cure the UV-curable adhesive layer, thereby achieving bonding.

[0118] When preparing adhesive compositions, solid resins, such as granules or flakes, are sometimes used as the resin. In this case, the resin and solvent can be preheated to dissolve the resin in the solvent, preparing a resin solution, which is then used in the preparation of the adhesive composition.

[0119] 3. Hard coating

[0120] In this embodiment, the hard coating film has a substrate layer and a hard coating layer from the bonding layer side.

[0121] The following describes the components of the hard coating film.

[0122] (1) Hard coating

[0123] In this embodiment, the hard coating layer is used to increase surface hardness. By configuring the hard coating layer, damage resistance can be improved.

[0124] (a) Characteristics of hard coating

[0125] Here, "hard coating" refers to a component used to improve surface hardness. Specifically, it means that in the case of a laminate having a hard coating in this embodiment, when subjected to the pencil hardness test specified in JIS K 5600-5-4 (1999), it exhibits a hardness of "H" or higher.

[0126] In this embodiment, the pencil hardness of the surface of the hard coating side of the laminate is preferably H or higher, more preferably 2H or higher, even more preferably 3H or higher, particularly preferably 4H or higher, and most preferably 5H or higher.

[0127] Here, pencil hardness is determined by the pencil hardness test specified in JIS K5600-5-4 (1999). Specifically, the highest pencil hardness without damage is evaluated by performing the pencil hardness test as specified in JIS K5600-5-4 (1999) on the surface of the hard coating side of the laminate using a test pencil specified in JIS-S-6006. The test conditions can be set as follows: angle 45°, load 1 kg, speed 0.5 mm / s to 1 mm / s, and temperature 23 ± 2 °C. For example, a pencil scratch coating hardness tester manufactured by Toyo Seiki Co., Ltd. can be used as the pencil hardness testing machine.

[0128] (b) Composition of the hard coating

[0129] The hard coating can be a single layer or a multilayer structure with two or more layers. In the case of a multilayer hard coating, in order to improve surface hardness and improve the balance between bending resistance and elastic modulus, the hard coating can have a layer for meeting pencil hardness and a layer for meeting dynamic bending test (a layer for meeting scratch resistance).

[0130] (c) Materials for hard coatings

[0131] Examples of materials for hard coatings include, for instance, cured resins. Specifically, the hard coating preferably comprises a cured resin composition containing a polymerizable compound. The cured resin composition containing the polymerizable compound can be obtained by using a polymerization initiator as needed, employing known methods to polymerize the polymerizable compound.

[0132] (i) Polymer compounds

[0133] The polymerizable compound has at least one polymerizable functional group within its molecule. For example, at least one of free radical polymerizable compounds and cationic polymerizable compounds can be used as the polymerizable compound.

[0134] A free radical polymerizable compound is a compound that possesses free radical polymerizable groups. The free radical polymerizable groups in a free radical polymerizable compound can be any functional group capable of undergoing a free radical polymerization reaction; there are no particular limitations. Examples include groups containing carbon-carbon unsaturated double bonds, such as vinyl groups and (meth)acryloyl groups. It should be noted that when a free radical polymerizable compound has two or more free radical polymerizable groups, these groups can be identical or different.

[0135] From the perspective of improving the hardness of the hard coating, the number of free radical polymerizable groups in one molecule of the free radical polymerizable compound is preferably two or more, and more preferably three or more.

[0136] As a free radical polymerizable compound, compounds having (meth)acrylyl groups are preferred from the perspective of high reactivity. For example, polyfunctional (meth)acrylate monomers and oligomers with molecular weights of several hundred to several thousand, such as urethane (meth)acrylates, polyester (meth)acrylates, epoxy (meth)acrylates, melamine (meth)acrylates, polyfluoroalkyl (meth)acrylates, and organosilicon (meth)acrylates, are preferred. Additionally, polyfunctional (meth)acrylate polymers having two or more (meth)acrylyl groups in the side chains of the acrylate polymer are also preferred. Polyfunctional (meth)acrylate monomers having two or more (meth)acrylyl groups per molecule are particularly preferred. By incorporating a cured product containing polyfunctional (meth)acrylate monomers into the hard coating, the hardness of the hard coating can be increased, thereby improving adhesion. Furthermore, polyfunctional (meth)acrylate oligomers or polymers having two or more (meth)acrylyl groups per molecule are also preferred. By incorporating cured polyfunctional (meth)acrylate oligomers or polymers into the hard coating, the hardness and flexural strength of the hard coating can be improved, thereby enhancing adhesion.

[0137] It should be noted that in this specification, (meth)acryloyl group refers to acryloyl group and methacryloyl group respectively, and (meth)acrylate refers to acrylate and methacrylate respectively.

[0138] Specific examples of polyfunctional (meth)acrylate monomers include, for instance, the substances described in Japanese Patent Application Publication No. 2019-132930. Among these, substances having 3 or more but 6 or fewer (meth)acryloyl groups per molecule are preferred from the perspectives of high reactivity, improved hardness of the coating, and good adhesion. Examples of preferred materials include pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri(meth)acrylate, tripentaerythritol octa(meth)acrylate, and tetrapentaerythritol deca(meth)acrylate. Particularly preferred are at least one selected from pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexaacrylate, as well as substances obtained by modifying them with PO, EO, or caprolactone.

[0139] To adjust hardness or viscosity, improve adhesion, etc., the resin composition may contain a monofunctional (meth)acrylate monomer as a free radical polymerizable compound. Specific examples of monofunctional (meth)acrylate monomers include, for instance, the substance described in Japanese Patent Application Publication No. 2019-132930.

[0140] Cationic polymerizable compounds are compounds that possess cationic polymerizable groups. The cationic polymerizable groups in a cationic polymerizable compound can be any functional group capable of undergoing a cationic polymerization reaction; there are no particular limitations. Examples include epoxy groups, oxetyl groups, and vinyl ether groups. It should be noted that when a cationic polymerizable compound has two or more cationic polymerizable groups, these cationic polymerizable groups can be the same or different.

[0141] From the perspective of improving the hardness of the hard coating, the number of cationic polymeric groups in one molecule of the cationic polymeric compound is preferably two or more, and more preferably three or more.

[0142] Furthermore, as a cationic polymerizable compound, a compound having at least one of an epoxy group and an oxetyl group as a cationic polymerizable group is preferred, and a compound having two or more epoxy groups and at least one of an oxetyl group in one molecule is more preferred. From the perspective of minimizing shrinkage associated with the polymerization reaction, cyclic ether groups such as epoxy groups and oxetyl groups are preferred. In addition, compounds having an epoxy group in the cyclic ether group have the following advantages: it is easy to obtain compounds with diverse structures, it does not adversely affect the durability of the obtained hard coating, and its compatibility with free radical polymerizable compounds is easy to control. Furthermore, oxetyl groups in the cyclic ether group have the following advantages: compared to epoxy groups, they have a higher degree of polymerization and lower toxicity; when the obtained hard coating is combined with a compound having an epoxy group, the formation rate of the network structure obtained from the cationic polymerizable compound in the coating film can be accelerated; even in areas mixed with free radical polymerizable compounds, no unreacted monomers remain in the film, and an independent network structure can be formed.

[0143] Examples of cationic polymerizable compounds with epoxy groups include, for instance, polyglycidyl ethers of polyols having alicyclic rings, or alicyclic epoxy resins obtained by epoxidizing compounds containing cyclohexene or cyclopentene rings using suitable oxidants such as hydrogen peroxide or peroxyacids; alicyclic epoxy resins such as polyglycidyl ethers of aliphatic polyols or their epoxy alkyl adducts, polyglycidyl esters of aliphatic long-chain polyacids, and homopolymers and copolymers of (meth)acrylate glycidyl esters; glycidyl ethers manufactured by reacting bisphenols such as bisphenol A, bisphenol F, and hydrogenated bisphenol A, or their epoxy alkyl adducts, caprolactone adducts, and other derivatives with epichlorohydrin; and glycidyl ether-type epoxy resins derived from bisphenols, such as phenolic varnish epoxy resins.

[0144] Specific examples of alicyclic epoxy resins, glycidyl ether type epoxy resins, and cationic polymerizable compounds having oxocyclic butyl groups can be cited, for example, as the substances described in Japanese Patent Application Publication No. 2018-104682.

[0145] It should be noted that the cured resin composition containing polymeric compounds in the hard coating can be analyzed using a Fourier transform infrared spectrophotometer (FTIR), a thermal decomposition gas chromatography-mass spectrometer (GC-MS), or a combination of high performance liquid chromatography, gas chromatography-mass spectrometry, NMR, elemental analysis, XPS / ESCA, and TOF-SIMS.

[0146] (ii) Polymerization initiator

[0147] The resin composition may also contain a polymerization initiator as needed. As a polymerization initiator, appropriate choices include free radical polymerization initiators, cationic polymerization initiators, and a combination of free radical and cationic polymerization initiators. These polymerization initiators are decomposed by at least one of light irradiation and heating, generating free radicals or cations to initiate free radical polymerization and cationic polymerization. It should be noted that in hard coatings, sometimes the polymerization initiator is completely decomposed without residue.

[0148] Specific examples of free radical polymerization initiators and cationic polymerization initiators can be cited, for example, the substances described in Japanese Patent Application Publication No. 2018-104682.

[0149] (iii) Particles

[0150] The hard coating preferably contains inorganic or organic particles, and more preferably inorganic microparticles. By including particles in the hard coating, the hardness can be increased.

[0151] Examples of inorganic particles include, for instance, metal oxide particles such as silicon dioxide (SiO2), aluminum oxide, zirconium oxide, titanium dioxide, 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, more preferably selected from at least one of silicon dioxide particles and aluminum oxide particles, and even more preferably silicon dioxide particles. This is because excellent hardness can be obtained.

[0152] Furthermore, the inorganic particles are preferably reactive inorganic particles whose surfaces undergo cross-linking reactions with each other or with at least one type of polymerizable compound, and which have photoreactive functional groups capable of forming covalent bonds on at least a portion of the particle surface. By allowing the reactive inorganic particles to undergo cross-linking reactions with each other or with at least one type of free radical polymerizable compound and cationic polymerizable compound, the hardness of the hard coating can be further improved.

[0153] The reactive inorganic particles have at least a portion of their surface coated with an organic component, and the surface has reactive functional groups introduced through the organic component. As reactive functional groups, polymerizable unsaturated groups are suitable, and photocurable unsaturated groups are more preferred. Examples of reactive functional groups include olefinic unsaturated bonds such as (meth)acryloyl, vinyl, and allyl, as well as epoxy groups.

[0154] There are no particular limitations on the active silica particles used; any existing, known active silica particles can be used, such as those described in Japanese Patent Application Publication No. 2008-165040. Furthermore, commercially available active silica particles include, for example, those manufactured by Nissan Chemical Industries, Ltd.: MIBK-SD, MIBK-SDMS, MIBK-SDL, MIBK-SDZL; and those manufactured by Nichibukai Chemicals, Ltd.: V8802, V8803.

[0155] Furthermore, the silica particles can be spherical, but irregularly shaped silica particles are preferred. A mixture of spherical and irregularly shaped silica particles can also be used. It should be noted that, in this specification, irregularly shaped silica particles refer to silica particles with a potato-like, irregularly uneven surface. Because irregularly shaped silica particles have a larger surface area compared to spherical silica particles, the contact area with the aforementioned resin components is increased, resulting in a more superior hardness of the hard coating.

[0156] It should be noted that whether the particles are irregularly shaped silica can be confirmed by observing the cross-section of the hard coating using an electron microscope.

[0157] From the perspective of improving hardness, the average particle size of the inorganic particles is preferably 5 nm or more, more preferably 10 nm or more. If the average particle size of the inorganic particles is too small, the particles are difficult to manufacture, and the particles may easily agglomerate. Furthermore, from the perspective of transparency, 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. If the average particle size of the inorganic particles is too large, large unevenness may form in the hard coating, or the haze may increase.

[0158] Here, the average particle size of the inorganic particles can be determined by cross-sectional observation of the hard coating using an electron microscope. The average particle size is taken as the average of the particle sizes of arbitrarily selected 10 particles. It should be noted that the average particle size of the irregularly shaped silica particles is the average of the maximum (major axis) and minimum (minor axis) distances between two points on the outer periphery of the irregularly shaped silica particles observed in the cross-sectional microscopic observation of the hard coating.

[0159] The hardness of the hard coating can be controlled by adjusting the size and content of the inorganic particles. For example, the content of silica particles relative to 100 parts by mass of the polymeric compound is preferably 25 parts by mass or more, more preferably 30 parts by mass or more, and even more preferably 50 parts by mass or more. If the content of silica particles is within the above range, the hardness of the hard coating can be improved. In addition, relative to 100 parts by mass of the polymeric compound, the content of silica particles is preferably 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less. If the content of silica particles is within the above range, good bending resistance can be obtained. For example, relative to 100 parts by mass of the polymeric compound, the content of silica particles is preferably 25 parts by mass or more and 150 parts by mass or less, more preferably 30 parts by mass or more and 120 parts by mass or less, and even more preferably 50 parts by mass or more and 100 parts by mass or less.

[0160] (iv) Ultraviolet absorbers

[0161] The hard coating may also contain ultraviolet absorbers. This helps suppress the degradation of the substrate layer caused by ultraviolet radiation. Specifically, when the substrate layer contains polyimide, it can suppress color changes of the polyimide-containing substrate layer over time. Furthermore, in display devices equipped with laminates, it can suppress the degradation of components disposed closer to the display panel than the laminate itself, such as polarizing elements, caused by ultraviolet radiation.

[0162] For the ultraviolet absorber included in the hard coating, the peak value of the absorption wavelength in the absorbance measurement is preferably between 300 nm and 390 nm, more preferably between 320 nm and 370 nm, and even more preferably between 330 nm and 370 nm. This ultraviolet absorber can efficiently absorb ultraviolet light in the UVA region. On the other hand, by offsetting the peak wavelength from the absorption wavelength of the initiator used to cure the hard coating (250 nm), the curing of the hard coating is not inhibited, and a hard coating with ultraviolet absorption capability can be formed.

[0163] For ultraviolet absorbers, the peak value of the absorption wavelength is preferably 380 nm or less, from the perspective of suppressing coloration caused by ultraviolet absorbers.

[0164] It should be noted that the absorbance of ultraviolet absorbers can be measured, for example, using an ultraviolet-visible-near-infrared spectrophotometer (e.g., Nippon Spectrophotometer Co., Ltd. V-7100).

[0165] Examples of UV absorbers include triazine-based UV absorbers, benzophenone-based UV absorbers, and benzotriazole-based UV absorbers.

[0166] From the perspective of suppressing the degradation of the substrate layer caused by ultraviolet radiation, it is preferable to select one or more ultraviolet absorbers from the group consisting of hydroxybenzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers, and more preferably to select one or more ultraviolet absorbers from the group consisting of hydroxybenzophenone-based ultraviolet absorbers.

[0167] Specific examples of hydroxybenzophenone-based ultraviolet absorbers include, for instance, the hydroxybenzophenone-based ultraviolet absorber described in Japanese Patent Application Publication No. 2019-132930.

[0168] As a hydroxybenzophenone-based ultraviolet absorber, a 2-hydroxybenzophenone-based ultraviolet absorber is preferred, and one or more absorbers selected from the group consisting of benzophenone-based ultraviolet absorbers having the following general formula (A) are more preferred. This absorber can suppress the degradation of the substrate layer caused by ultraviolet radiation and improve durability.

[0169] [Chemistry 1]

[0170] General formula (A)

[0171]

[0172] (In general formula (A), X) 1 and X 2 Each independently represents a hydroxyl group and -OR. a Or a hydrocarbon group with 1 to 15 carbon atoms, R a (This refers to hydrocarbon groups with 1 to 15 carbon atoms.)

[0173] In general formula (A), X 1 X 2 and R a Examples of hydrocarbon groups with 1 to 15 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, dodecyl, allyl, and benzyl. Aliphatic hydrocarbon groups with 3 or more carbon atoms can be straight-chain or branched. The number of carbon atoms in the hydrocarbon group is preferably 1 to 12, more preferably 1 to 8. From the perspective of easily improving transparency, the hydrocarbon group is preferably an aliphatic hydrocarbon group, among which methyl and allyl are preferred.

[0174] From the perspective of ease of improving durability, X 1 and X 2 Each is preferably hydroxyl or -OR. a .

[0175] It is selected from one or more of the group consisting of benzophenone-based ultraviolet absorbers having general formula (A), wherein it is preferably selected from one or more of the group consisting of 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone and 2,2'-dihydroxy-4,4'-diallyloxybenzophenone, more preferably selected from one or more of the group consisting of 2,2',4,4'-tetrahydroxybenzophenone and 2,2'-dihydroxy-4,4'-dimethoxybenzophenone.

[0176] Specific examples of benzotriazole-based ultraviolet absorbers include, for instance, the benzotriazole-based ultraviolet absorber described in Japanese Patent Application Publication No. 2019-132930.

[0177] As a benzotriazole-based ultraviolet absorber, 2-(2-hydroxyphenyl)benzotriazoles are preferred, and one or more are selected from the group consisting of benzotriazole-based ultraviolet absorbers having the following general formula (B). It can suppress the degradation of the substrate layer caused by ultraviolet radiation and improve durability.

[0178] [Chemistry 2]

[0179] General formula (B)

[0180]

[0181] (In general formula (B), Y) 1 Y 2 and Y 3 Each independently represents a hydrogen atom, hydroxyl group, and -OR. b Or a hydrocarbon group with 1 to 15 carbon atoms, R b Y represents a hydrocarbon group with 1 to 15 carbon atoms. 1 Y 2 and Y 3 At least one of them indicates hydroxyl, -OR b Or a hydrocarbon group with 1 to 15 carbon atoms. 4 This represents a hydrogen atom or a halogen atom.

[0182] In general formula (B), Y 1 Y 2 and Y 3 and R b Examples of hydrocarbon groups with 1 to 15 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and dodecyl. Aliphatic hydrocarbon groups with 3 or more carbon atoms can be straight-chain or branched. The number of carbon atoms in the hydrocarbon group is preferably 1 to 12, more preferably 1 to 8. From the perspective of easily improving transparency, the hydrocarbon group is preferably an aliphatic hydrocarbon group, preferably a straight-chain or branched alkyl group, wherein methyl, tert-butyl, tert-pentyl, n-octyl, or tert-octyl are preferred.

[0183] In general formula (B), Y is used as 4 The halogen atom in the atom can be chlorine, fluorine, bromine, etc., with chlorine being the preferred atom.

[0184] In general formula (B), Y is preferred. 1 and Y 3 For hydrogen atoms, Y 2 Indicates hydroxyl or -OR b More preferably, it is selected from one or more of the group consisting of 2-(2-hydroxy-4-octoxyphenyl)-2H-benzotriazole and 2-(2,4-dihydroxyphenyl)-2H-benzotriazole. It can suppress the degradation of the substrate layer caused by ultraviolet light and improve durability.

[0185] The content of the ultraviolet absorber in the hard coating is preferably 10% by mass or less, more preferably 7% by mass or less, from the perspective of suppressing haze by mixing the ultraviolet absorber. Furthermore, from the perspective of suppressing the degradation of the substrate layer caused by ultraviolet radiation and improving durability, the content of the ultraviolet absorber in the hard coating 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.

[0186] (v) Antifouling agent

[0187] Hard coatings can also contain antifouling agents, which can impart antifouling properties to laminates.

[0188] There are no particular limitations on the type of antifouling agent; examples include silicone-based, fluorinated, and silicone-and-fluorinated antifouling agents. Additionally, acrylic-based antifouling agents can also be used. One type of antifouling agent can be used alone, or two or more can be mixed.

[0189] Hard coatings containing silicone-based and fluorine-based antifouling agents are less prone to fingerprint adhesion (less noticeable) and have good wipeability. In addition, the inclusion of silicone-based and fluorine-based antifouling agents can reduce the surface tension of the curing resin composition used for coating hard coatings, thus resulting in good leveling properties and a better appearance of the obtained hard coating.

[0190] Furthermore, the hard coating containing silicone-based anti-fouling agents exhibits good sliding properties and excellent scratch resistance. Display devices equipped with this type of laminate containing silicone-based anti-fouling agents have a superior tactile experience due to the excellent sliding properties when touched with a finger or pen.

[0191] To improve the durability of antifouling performance, the antifouling agent preferably has reactive functional groups. When the antifouling agent lacks reactive functional groups, regardless of whether the laminate is in roll or sheet form, the following may occur: when the laminates are overlapped, the antifouling agent transfers to the side of the laminate opposite to the hard coating side; when other layers are attached or coated to the side of the laminate opposite to the hard coating side, these other layers may peel off, and consequently, they are prone to peeling off during repeated bending. In contrast, when the antifouling agent has reactive functional groups, the performance durability of the antifouling effect becomes better.

[0192] The antifouling agent only needs to have one or more reactive functional groups, preferably two or more. By using an antifouling agent having two or more reactive functional groups, excellent scratch resistance can be imparted to the hard coating.

[0193] Furthermore, the weight-average molecular weight of the antifouling agent is preferably below 5000. The weight-average molecular weight of the antifouling agent can be determined by gel permeation chromatography (GPC).

[0194] The antifouling agent can be uniformly dispersed in the hard coating. From the perspective of obtaining sufficient antifouling properties with a small amount of addition and suppressing the reduction of the strength of the hard coating, it is preferable to be biased towards the surface side of the hard coating.

[0195] As a method to make the antifouling agent biased on the surface side of the hard coating, for example, the following methods can be used: when forming the hard coating, before the coating film of the hard coating with the curable resin composition is dried and cured, the coating film is heated to reduce the viscosity of the resin component contained in the coating film, thereby increasing the fluidity and causing the antifouling agent to be biased on the surface side of the hard coating; or, using an antifouling agent with low surface tension, no heat is applied when the coating film is dried, so that the antifouling agent floats on the surface of the coating film, and then the coating film is cured, thereby causing the antifouling agent to be biased on the surface side of the hard coating.

[0196] The content of the antifouling agent is preferably 0.01 parts by weight or more and 3.0 parts by weight or less per 100 parts by weight of the above-mentioned resin components. If the content of the antifouling agent is too low, it may not be able to impart sufficient antifouling properties to the hard coating. On the other hand, if the content of the antifouling agent is too high, the hardness of the hard coating may be reduced.

[0197] (vi) Other additives

[0198] The hard coating may contain further additives as needed. These additives are selected appropriately based on the function imparted to the hard coating and are not particularly limited. Examples include inorganic or organic particles for adjusting refractive index, infrared absorbers, anti-glare agents, antifouling agents, antistatic agents, colorants such as blue or purple pigments, leveling agents, surfactants, slip agents, various sensitizers, flame retardants, adhesives, polymerization inhibitors, antioxidants, light stabilizers, and surface modifiers.

[0199] (d) Methods for forming hard coatings

[0200] Examples of methods for forming a hard coating include coating a hard coating curable resin composition containing the aforementioned polymeric compound onto a substrate layer and then curing it.

[0201] The curable resin composition for hard coating contains polymerizable compounds, and may further contain polymerization initiators, particles, ultraviolet absorbers, solvents, additives, etc., as needed.

[0202] As a method for applying a curable resin composition for a hard coating onto a substrate layer, there are no particular limitations as long as the coating can achieve the target thickness. Examples include general coating methods such as gravure coating, reverse gravure coating, gravure offset coating, spin coating, roller coating, reverse roller coating, doctor blade coating, dip coating, spray coating, mold coating, and screen printing. Alternatively, transfer printing can also be used as a method for forming the coating film of the resin composition for a hard coating.

[0203] The coating film of the hard coating curable resin composition is dried as needed, thereby removing the solvent. Examples of drying methods include, for instance, vacuum drying or heat drying, and combinations thereof. For example, drying can be performed by heating at a temperature of 30°C to 120°C for 10 to 180 seconds.

[0204] As a method for curing the coating film of a hard coating resin composition, the appropriate method is selected according to the polymeric groups of the polymeric compound; for example, at least one of light irradiation and heating can be used.

[0205] Light irradiation primarily utilizes ultraviolet light, visible light, electron beams, and ionizing rays. In ultraviolet curing, ultraviolet light emitted from sources such as ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arcs, xenon arcs, and metal halide lamps can be used. The irradiation dose from these energy sources, for example, based on the cumulative exposure at an ultraviolet wavelength of 365 nm, can reach 50 mJ / cm². 2 Above 5000mJ / cm 2 Below, left and right.

[0206] When heating is involved, for example, the process can be carried out at a temperature between 40°C and 120°C. Alternatively, the reaction can be carried out by placing the mixture at room temperature (25°C) for more than 24 hours.

[0207] (2) Substrate layer

[0208] In this embodiment, the substrate layer is a component that supports the hard coating.

[0209] (a) Characteristics of the substrate layer

[0210] In this embodiment, the composite elastic modulus of the substrate layer is preferably 5.7 GPa or higher, more preferably 6.5 GPa or higher, and even more preferably 7.5 GPa or higher. By setting the composite elastic modulus of the substrate layer to the above range, the surface hardness of the hard coating side of the laminate can be increased, thereby improving damage resistance.

[0211] Furthermore, according to the method for measuring the composite elastic modulus described later, the composite elastic modulus of the glass substrate is approximately 40 GPa. Therefore, the composite elastic modulus of the substrate layer is preferably 40 GPa or less, more preferably 30 GPa or less, and even more preferably 20 GPa or less. The composite elastic modulus of the substrate layer is preferably 5.7 GPa or more and 40 GPa or less, more preferably 6.5 GPa or more and 30 GPa or less, and even more preferably 7.5 GPa or more and 20 GPa or less.

[0212] The method for determining the composite elastic modulus of the substrate layer can be the same as the method for determining the composite elastic modulus of the bonding layer described above.

[0213] The composite elastic modulus of the substrate layer can be adjusted, for example, according to the type and composition of the materials contained in the substrate layer.

[0214] When the laminate of this embodiment is used, for example, in a display device, the substrate layer preferably has transparency. Specifically, the total light transmittance of the substrate layer is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more.

[0215] In addition, the haze of the substrate layer is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less.

[0216] (b) Material of the substrate layer

[0217] As the substrate layer, a resin substrate can be used, for example. The resin constituting the resin substrate preferably satisfies the aforementioned composite elastic modulus and is transparent. Examples of such resins include polyimide-based resins, polyamide-based resins, polyester-based resins, cellulose-based resins, acrylic resins, polycarbonate-based resins, and polyethylene naphthalate-based resins. Examples of polyimide-based resins include polyimide, polyamide-imide, polyether-imide, and polyesterimide. Examples of polyester-based resins include polyethylene terephthalate (PET), polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate (PEN). Examples of cellulose-based resins include triacetyl cellulose (TAC). Examples of acrylic-based resins include poly(methyl methacrylate) and poly(ethyl methacrylate). It should be noted that the resin substrate can be a single layer or a multilayer structure such as a co-extruded film. Among them, polyimide resins are preferred due to their bending resistance, excellent hardness, and transparency.

[0218] As for polyimide-based resins, there are no particular limitations as long as they meet the above-mentioned composite elastic modulus and have transparency. Among the above, polyimide and polyamide-imide are preferred.

[0219] (i) Polyimide

[0220] Polyimide is obtained by reacting a tetracarboxylic acid component with a diamine component. As a polyimide, there are no particular limitations as long as it satisfies the above-mentioned composite elastic modulus and has transparency. For example, from the perspective of having excellent transparency and excellent rigidity, it is preferable to have at least one structure selected from the group consisting of the structures shown in the following general formula (1) and the following general formula (3).

[0221] [Chemistry 3]

[0222]

[0223] In the above general formula (1), R 5 R represents a tetravalent group that is a tetracarboxylic acid residue. 6 It means that at least one divalent group is selected from the group consisting of trans-cyclohexanediamine residue, trans-1,4-bis(methylene)cyclohexanediamine residue, 4,4'-diaminodiphenyl sulfone residue, 3,4'-diaminodiphenyl sulfone residue, and the divalent group shown in the following general formula (2). n represents the number of repeating units, which is 1 or more.

[0224] [Chemistry 4]

[0225]

[0226] In the above general formula (2), R 7 and R 8Each can be independently represented by a hydrogen atom, alkyl group, or perfluoroalkyl group.

[0227] [Chemistry 5]

[0228]

[0229] In the above general formula (3), R 9 R represents at least one tetravalent group selected from the group consisting of cyclohexanetetracarboxylic acid residues, cyclopentanetetracarboxylic acid residues, dicyclohexane-3,4,3',4'-tetracarboxylic acid residues, and 4,4'-(hexafluoroisopropylidene)phthalic acid residues. 10 This indicates a divalent group that is a diamine residue. n' indicates the number of repeating units, which is 1 or more.

[0230] It should be noted that "tetracarboxylic acid residue" refers to the residue after removing four carboxyl groups from a tetracarboxylic acid, indicating the same structure as the residue after removing the dianhydride structure from a tetracarboxylic dianhydride. Additionally, "diamine residue" refers to the residue after removing two amino groups from a diamine.

[0231] In the above general formula (1), R 5 The residue is a tetracarboxylic acid residue, which can be a residue obtained by removing the dianhydride structure from a tetracarboxylic dianhydride. Examples of tetracarboxylic dianhydrides include, for instance, the tetracarboxylic dianhydride described in International Publication No. 2018 / 070523. R in the above general formula (1) 5 From the perspective of improving transparency and rigidity, it is preferable to include at least one residue selected from the group consisting of 4,4'-(hexafluoroisopropylene)phthalic acid residue, 3,3',4,4'-biphenyltetracarboxylic acid residue, pyromellitic acid residue, 2,3',3,4'-biphenyltetracarboxylic acid residue, 3,3',4,4'-benzophenone tetracarboxylic acid residue, 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residue, 4,4'-oxophthalic acid residue, cyclohexane tetracarboxylic acid residue, and cyclopentane tetracarboxylic acid residue. It is even more preferable to include at least one residue selected from the group consisting of 4,4'-(hexafluoroisopropylene)phthalic acid residue, 4,4'-oxophthalic acid residue, and 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residue.

[0232] R 5 The preferred residues are preferably contained in a total of 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0233] Additionally, as R 5Preferably, Group A and Group B are used in combination. Group A is a tetracarboxylic acid residue group suitable for improving rigidity, selected from the group consisting of 3,3',4,4'-biphenyltetracarboxylic acid residue, 3,3',4,4'-benzophenone tetracarboxylic acid residue and pyromellitic acid residue. Group B is a tetracarboxylic acid residue group suitable for improving transparency, selected from the group consisting of 4,4'-(hexafluoroisopropyl)diphthalic acid residue, 2,3',3,4'-biphenyltetracarboxylic acid residue, 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residue, 4,4'-oxodiphthalic acid residue, cyclohexanetetracarboxylic acid residue and cyclopentanetetracarboxylic acid residue.

[0234] In this case, regarding the content ratio of the tetracarboxylic acid residue group (Group A) suitable for improving rigidity and the tetracarboxylic acid residue group (Group B) suitable for improving transparency, the tetracarboxylic acid residue group (Group A) suitable for improving rigidity is preferably 0.05 moles or more and 9 moles or less, more preferably 0.1 moles or more and 5 moles or less, and even more preferably 0.3 moles or more and 4 moles or less, relative to 1 mole of the tetracarboxylic acid residue group (Group B) suitable for improving transparency.

[0235] R in the above general formula (1) 6 From the perspective of improving transparency and rigidity, it is preferable to select at least one divalent group selected from the group consisting of 4,4'-diaminodiphenyl sulfone residues, 3,4'-diaminodiphenyl sulfone residues and the divalent group shown in the above general formula (2), and more preferably selected from 4,4'-diaminodiphenyl sulfone residues, 3,4'-diaminodiphenyl sulfone residues, and R 7 and R 8 It is at least one divalent group in the group consisting of divalent groups represented by the above general formula (2) of perfluoroalkyl groups.

[0236] R in the above general formula (3) 9 From the perspective of improving transparency and rigidity, it is preferable to include 4,4'-(hexafluoroisopropylidene) phthalic acid residues, 3,3',4,4'-diphenyl sulfone tetracarboxylic acid residues and oxophthalic acid residues.

[0237] R 9 The preferred residues are preferably 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0238] In the above general formula (3), R 10 The residue is a diamine residue, which can be a residue obtained by removing two amino groups from a diamine. Examples of diamines include those described in International Publication No. 2018 / 070523. R in the above general formula (3) is... 10From the perspective of improving transparency and rigidity, it is preferable to include residues selected from 2,2'-bis(trifluoromethyl)benzidine, bis[4-(4-aminophenoxy)phenyl]sulfone, 4,4'-diaminodiphenyl sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]sulfone, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether, 1,4-bis[4-amino-2-(trifluoromethyl)phenoxy]phenyl, 2,2-bis[4-(4- The divalent group comprises at least one divalent group selected from the group consisting of amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane residue, 4,4'-diamino-2-(trifluoromethyl)diphenyl ether residue, 4,4'-diaminobenzoyl aniline residue, N,N'-bis(4-aminophenyl)terephthalamide residue and 9,9-bis(4-aminophenyl)fluorene residue, and more preferably includes at least one divalent group selected from the group consisting of 2,2'-bis(trifluoromethyl)benzidine residue, bis[4-(4-aminophenoxy)phenyl]sulfone residue and 4,4'-diaminodiphenyl sulfone residue.

[0239] R 10 The preferred residues are preferably contained in a total of 50 mol% or more, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

[0240] Additionally, as R 10 Preferably, group C is used in combination with group D, wherein group C is a diamine residue group suitable for improving rigidity selected from the group consisting of bis[4-(4-aminophenoxy)phenyl]sulfone residue, 4,4'-diaminobenzoyl aniline residue, N,N'-bis(4-aminophenyl)terephthalamide residue, p-phenylenediamine residue, m-phenylenediamine residue and 4,4'-diaminodiphenylmethane residue; and group D is a diamine residue group selected from 2,2'-bis(trifluoromethyl)benzidine residue, 4,4'-diaminodiphenylsulfone residue, 2,2-bis[4-(4-aminophenyl)benzidine residue, 4,4'-diaminodiphenyl sulfone residue, and 4,4'-diaminodiphenylmethane residue. The group consisting of at least one of the following diamine residues suitable for improving transparency: phenoxy[phenyl]hexafluoropropane residue, bis[4-(3-aminophenoxy)phenyl]sulfone residue, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether residue, 1,4-bis[4-amino-2-(trifluoromethyl)phenoxy]benzene residue, 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane residue, 4,4'-diamino-2-(trifluoromethyl)diphenyl ether residue and 9,9-bis(4-aminophenyl)fluorene residue.

[0241] In this case, regarding the content ratio of the diamine residue group (group C) suitable for improving rigidity to the diamine residue group (group D) suitable for improving transparency, the diamine residue group (group C) suitable for improving rigidity is preferably 0.05 moles or more and 9 moles or less, more preferably 0.1 moles or more and 5 moles or less, and more preferably 0.3 moles or more and 4 moles or less, relative to 1 mole of the diamine residue group (group D) suitable for improving transparency.

[0242] In the structures shown in general formulas (1) and (3) above, n and n' each independently represent the number of repeating units, which is 1 or more. The number of repeating units n in the polyimide can be appropriately selected according to the structure and is not particularly limited. The average number of repeating units can be, for example, 10 or more and 2000 or less, preferably 15 or more and 1000 or less.

[0243] Furthermore, polyimides may contain a polyamide structure in a portion thereof. Examples of polyamide structures that may be included include, for instance, polyamide-imide structures containing tricarboxylic acid residues such as trimellitic anhydride, or polyamide structures containing dicarboxylic acid residues such as terephthalic acid.

[0244] From the perspective of improving transparency and increasing surface hardness, as R 5 Or R 9 The tetravalent group of the tetracarboxylic acid residue, and as R 6 Or R 10 At least one of the divalent groups of the diamine residues preferably comprises an aromatic ring and includes at least one of the following structures: (i) a fluorine atom, (ii) an aliphatic ring, and (iii) a structure in which aromatic rings are linked together by a sulfonyl group or a fluorinated or unsubstituted alkylene group. By including at least one of the tetracarboxylic acid residues having an aromatic ring and the diamine residues having an aromatic ring in the polyimide, the molecular backbone becomes rigid, thereby increasing orientation and surface hardness. However, the rigid aromatic ring backbone tends to extend the absorption wavelength to longer wavelengths, and the transmittance in the visible light region tends to decrease. On the other hand, if the polyimide includes (i) a fluorine atom, the transparency is improved from the perspective of making it less likely for charge transfer to occur in the electronic states within the polyimide backbone. In addition, if the polyimide includes (ii) an aliphatic ring, the transparency is improved from the perspective of hindering the movement of charge within the backbone by cleaving the conjugation of π electrons within the polyimide backbone. Furthermore, if the polyimide contains (iii) a structure in which aromatic rings are linked together by sulfonyl groups or fluorinated or unsubstituted alkylene groups, then the transparency is improved from the perspective of being able to hinder the movement of charges within the framework by severing the conjugation of π electrons within the polyimide framework.

[0245] Among them, focusing on improving transparency and surface hardness, as R 5 Or R9 The tetravalent group of the tetracarboxylic acid residue, and as R 6 Or R 10 At least one of the divalent groups of the diamine residues preferably comprises an aromatic ring and a fluorine atom, as R 6 Or R 10 The divalent group of the diamine residue preferably includes an aromatic ring and a fluorine atom.

[0246] As a specific example of such polyimide, substances having the specific structure described in International Publication No. 2018 / 070523 can be cited.

[0247] Polyimide can be synthesized using well-known methods. Alternatively, commercially available substances can also be used as polyimide. Examples of commercially available polyimide include Neopulim (a registered trademark) manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0248] The weight-average molecular weight of polyimide is preferably 3,000 to 500,000, more preferably 5,000 to 300,000, and even more preferably 10,000 to 200,000. If the weight-average molecular weight is too small, sufficient strength may not be obtained. If the weight-average molecular weight is too large, the viscosity increases and the solubility decreases, so a substrate layer with a smooth surface and uniform thickness may not be obtained.

[0249] It should be noted that the weight-average molecular weight of polyimide can be determined by gel permeation chromatography (GPC). Specifically, polyimide is prepared into a 0.1% (w / w) N-methylpyrrolidone (NMP) solution, and the developing solvent is a 30 mmol% LiBr-NMP solution with a water content of less than 500 ppm. The determination is performed using a Tosoh-manufactured GPC apparatus (HLC-8120, column: SHODEX GPC LF-804) at a sample injection volume of 50 μL, a solvent flow rate of 0.4 mL / min, and a temperature of 37°C. The weight-average molecular weight is determined using a polystyrene standard sample of the same concentration as the sample.

[0250] (ii) Polyamide imide

[0251] As a polyamide-imide, there are no particular limitations as long as it satisfies the aforementioned composite elastic modulus and has transparency. Examples include substances having the following first and second blocks: the first block comprises structural units from a dianhydride and a diamine, and the second block comprises structural units from an aromatic dicarbonyl compound and an aromatic diamine. In the aforementioned polyamide-imide, the dianhydride may, for example, comprise biphenyltetracarboxylic acid dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA). Additionally, the diamine may comprise bis(trifluoromethyl)benzidine (TFDB). That is, the aforementioned polyamide-imide has a structure formed by imidizing a polyamide-imide precursor having the following first and second blocks, where the first block is copolymerized from a monomer comprising a dianhydride and a diamine, and the second block is copolymerized from a monomer comprising an aromatic dicarbonyl compound and an aromatic diamine. The aforementioned polyamide-imide, by having a first block containing an imide bond and a second block containing an amide bond, exhibits superior not only optical properties but also thermal and mechanical properties. In particular, by using bis(trifluoromethyl)benzidine (TFDB) as the diamine forming the first block, thermal stability and optical properties are improved. Furthermore, by using 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and biphenyltetracarboxylic acid dianhydride (BPDA) as the dianhydrides forming the first block, improved birefringence and ensured heat resistance are achieved.

[0252] The dianhydrides forming the first block contain two types of dianhydrides, namely 6FDA and BPDA. In the first block, polymers bonded with TFDB and 6FDA and polymers bonded with TFDB and BPDA can be distinguished based on different repeating units, or they can be arranged regularly within the same repeating unit, or they can be arranged completely randomly.

[0253] In the monomers forming the first block, BPDA and 6FDA are preferably contained as dianhydrides in a molar ratio of 1:3 to 3:1. This is because it not only ensures optical properties but also suppresses the reduction of mechanical properties and heat resistance, resulting in excellent birefringence.

[0254] The molar ratio of the first block to the second block is preferably 5:1 to 1:1. When the content of the second block is significantly low, the improved thermal stability and mechanical properties provided by the second block may not be fully realized. Furthermore, when the content of the second block is further higher than that of the first block, thermal stability and mechanical properties can be improved, but optical properties may deteriorate, such as reduced yellowness and transmittance, while birefringence may increase. It should be noted that the first block and the second block can be random copolymers or block copolymers. The repeating units of the blocks are not particularly limited.

[0255] Examples of aromatic dicarbonyl compounds forming the second block include, for example, one or more selected from the group consisting of p-Terephthaloyl chloride (TPC), terephthalic acid, isophthaloyl dichloride, and 4,4'-benzoyl dichloride. Preferably, it can be one or more selected from p-Terephthaloyl chloride (TPC) and isophthaloyl dichloride.

[0256] Examples of diamines that form the second block include 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP), bis(4-(4-aminophenoxy)phenyl)sulfone (BAPS), bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4'-diaminodiphenyl sulfone (4DDS), 3,3'-diaminodiphenyl sulfone (3DDS), 2,2-bis(4-(4-aminophenoxy)phenylpropane (BAPP), 4,4'-diaminodiphenylpropane (6HDA), and 1,3-bis(4-aminophenoxy)phenyl (134A). The group consisting of one or more diamines having a soft group, including PB), 1,3-bis(3-aminophenoxy)benzene (133APB), 1,4-bis(4-aminophenoxy)biphenyl (BAPB), 4,4'-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (6FAPBP), 3,3-diamino-4,4-dihydroxydiphenyl sulfone (DABS), 2,2-bis(3-amino-4-hydroxyoxyphenyl)propane (BAP), 4,4'-diaminodiphenylmethane (DDM), 4,4'-oxodiphenylamine (4-ODA), and 3,3'-oxodiphenylamine (3-ODA).

[0257] When using aromatic dicarbonyl compounds, high thermal stability and mechanical properties are easily achieved, but high birefringence is sometimes exhibited due to the benzene ring within the molecular structure. Therefore, to suppress the reduction in birefringence caused by the second block, diamines with a flexible group introduced into the molecular structure are preferred. Specifically, diamines are more preferably selected from one or more of bis(4-(3-aminophenoxy)phenyl)sulfone (BAPSM), 4,4'-diaminodiphenyl sulfone (4DDS), and 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane (HFBAPP). In particular, diamines with longer flexible groups (such as BAPSM) and meta-substituents exhibit superior birefringence.

[0258] The polyamide-imide precursor containing the first and second blocks described below has a weight-average molecular weight, as determined by GPC, preferably between 200,000 and 215,000, and a viscosity, preferably between 2,400 poise and 2,600 poise. The first block is a copolymer of a dianhydride containing biphenyltetracarboxylic acid dianhydride (BPDA) and 2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) with a diamine containing bis(trifluoromethyl)benzidine (TFDB), and the second block is a copolymer of an aromatic dicarbonyl compound with an aromatic diamine.

[0259] Polyamide-imide can be obtained by imidizing a polyamide-imide precursor. Alternatively, polyamide-imide films can be obtained using polyamide-imide. For methods of imidizing the polyamide-imide precursor and methods of manufacturing polyamide-imide films, please refer, for example, to Japanese Patent Publication No. 2018-506611.

[0260] 4. Glass substrate

[0261] In this embodiment, the thickness of the glass substrate is 100 μm or less, preferably 90 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less. By making the glass substrate thinner than the above range, good bending resistance and sufficient hardness can be obtained. In addition, curling of the laminate can also be suppressed. Furthermore, this is preferred from the perspective of lightweighting the laminate. On the other hand, the thickness of the glass substrate is preferably 10 μm or more, more preferably 15 μm or more, even more preferably 20 μm or more, and particularly preferably 30 μm or more. By making the thickness of the glass substrate within the above range, good impact resistance can be obtained. The thickness of the glass substrate is 10 μm or more and 100 μm or less, preferably 15 μm or more and 90 μm or less, more preferably 20 μm or more and 80 μm or less, and even more preferably 25 μm or more and 75 μm or less.

[0262] Furthermore, the ratio of the thickness of the glass substrate to the total thickness of the laminate is preferably 30% or more, more preferably 40% or more, and even more preferably 50% or more. If the ratio falls within this range, the thickness of the glass substrate can be relatively increased, maintaining the texture and feel of the glass. On the other hand, the ratio of the thickness of the glass substrate to the total thickness of the laminate is preferably 90% or less, more preferably 80% or less, and even more preferably 70% or less. If the ratio falls within this range, the thickness of the hard coating film can be relatively increased, improving impact resistance. The ratio of the thickness of the glass substrate to the total thickness of the laminate is preferably 30% or more and 90% or less, more preferably 40% or more and 80% or less, and even more preferably 50% or more and 70% or less.

[0263] The glass constituting the glass substrate is not particularly limited, but chemically strengthened glass is preferred. Chemically strengthened glass has excellent mechanical strength and can be thinned accordingly, making it preferred from this perspective. Chemically strengthened glass is typically a glass in which sodium is replaced with potassium or the like near the surface of the glass, resulting in a partial exchange of ions, thereby enhancing the mechanical properties through a chemical method, and creating a compressive stress layer on the surface.

[0264] Examples of glasses that form the substrate of chemically strengthened glass include aluminosilicate glass, soda-lime glass, borosilicate glass, lead glass, alkaline barium glass, and aluminoborosilicate glass. Additionally, the substrate of chemically strengthened glass can be composed of crystallized glass.

[0265] Commercially available products that serve as substrates for chemically strengthened glass include Corning's Gorilla Glass, AGC's Dragontrail, and Schott's chemically strengthened glass.

[0266] 5. Functional layer

[0267] The laminate in this embodiment may further have a functional layer on the side of the hard coating opposite to the substrate layer, between the hard coating and the substrate layer, between the substrate layer and the bonding layer, between the glass substrate and the bonding layer, or on the side of the glass substrate opposite to the bonding layer.

[0268] Furthermore, a functional layer can be a single layer or multiple layers. Additionally, a functional layer can be a layer with a single function, or it can consist of multiple layers with different functions.

[0269] Examples of functional layers disposed on the side opposite to the substrate layer of the hard coating layer include anti-reflective layers, anti-glare layers, and protective layers. Examples of functional layers disposed between the hard coating layer and the substrate layer include primer layers, anti-scattering layers, and impact-absorbing layers. Examples of functional layers disposed between the substrate layer and the bonding layer include decorative layers, primer layers, color-correcting layers, anti-scattering layers, and impact-absorbing layers. Examples of functional layers disposed between the glass substrate and the bonding layer include ITO electrodes and antenna wiring. Examples of functional layers disposed on the side opposite to the bonding layer of the glass substrate include adhesive layers, decorative layers, and impact-absorbing layers.

[0270] (Anti-reflective layer)

[0271] The laminate in this embodiment is, for example, as shown in the example... Figure 2 As shown, an anti-reflective layer 7 can be provided on the side of the hard coating 6 opposite to the substrate layer 5. Furthermore, the anti-reflective layer 7 can be, for example, as shown in... Figure 2 As shown, it can also be a layer that constitutes the hard coating film 4.

[0272] Anti-reflective layers can be composed of a single layer or multiple layers.

[0273] As an anti-reflective layer, it can be used for general anti-reflective layers, such as single-layer films containing materials with a refractive index lower than that of the hard coating layer, multilayer films having high refractive index layers and low refractive index layers from the hard coating layer side, multilayer films having alternating high refractive index layers and low refractive index layers from the hard coating layer side, and multilayer films having intermediate refractive index layers, high refractive index layers and low refractive index layers sequentially from the hard coating layer side.

[0274] When the antireflective layer is a single-layer film, any material contained in the single-layer film can be a material with a lower refractive index than the hard coating layer, such as magnesium fluoride.

[0275] Furthermore, when the antireflective layer is a multilayer film, the refractive index of the low-refractive-index layer is preferably 1.45 or less, more preferably 1.40 or less. By setting the refractive index of the low-refractive-index layer within the above range, the antireflective properties become good. In addition, the lower limit of the refractive index of the low-refractive-index layer is actually 1.10 or more.

[0276] Examples of low refractive index layers include: low refractive index layers containing hydrolyzed condensates of metal alkoxides, low refractive index layers containing resins with low refractive indexes, low refractive index layers containing low refractive index particles, and low refractive index layers containing binder resins and low refractive index particles.

[0277] Hydrolytic condensation polymers of metal alkoxides can be obtained, for example, by the sol-gel method.

[0278] Examples of resins with low refractive index include fluoropolymers.

[0279] There are no particular limitations on the low refractive index particles; any inorganic or organic material such as silicon dioxide or magnesium fluoride can be used. However, from the perspective of reducing the reflectivity of the antireflective layer, porous particles are preferred. Porous particles have fine internal pores containing air, thus resulting in a low refractive index. Examples of porous particles include porous particles and hollow particles. Hollow particles are preferred.

[0280] Hollow particles are particles that have an outer shell, are surrounded by a shell, and have air inside.

[0281] The outer shell of hollow particles can be inorganic or organic, and examples include layers composed of metals, metal oxides, resins, and silicon dioxide. Hollow silica particles with a silicon dioxide outer shell are preferred. When the outer shell is silicon dioxide, the silicon dioxide can be in any of the following states: crystalline, sol-like, or gel-like.

[0282] The hollow particles can be any of the following shapes: spherical, ellipsoidal, or polyhedral (approximately spherical), chain-like, needle-like, plate-like, sheet-like, rod-like, or fibrous. Preferably, they are spherical or approximately spherical, and more preferably ellipsoidal or spherical.

[0283] In cases where the low-refractive-index layer contains a binder resin and low-refractive-index particles, the low-refractive-index particles are preferably surface-treated. Surface treatment of the low-refractive-index particles is preferably performed using a silane coupling agent. Specifically, surface treatment using a silane coupling agent having (meth)acryloyl groups is preferred. By performing surface treatment on the low-refractive-index particles, the affinity with the binder resin is improved, the particle dispersion becomes more uniform, and particle agglomeration is less likely. Therefore, it is possible to suppress the decrease in transparency of the low-refractive-index layer, the coatability of the composition for the low-refractive-index layer, and the reduction in the film strength of the composition for the low-refractive-index layer caused by large particle formation from agglomeration.

[0284] Examples of silane coupling agents preferred for surface treatment of low-refractive-index particles include 3-methacryloyloxypropylmethyldimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldiethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-epoxypropoxypropylmethyldimethoxysilane, 3-epoxypropoxypropyltrimethoxysilane, 3-epoxypropoxypropylmethyldiethoxysilane, 3-epoxypropoxypropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-amino Propyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanate propyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, 1,6-bis(trimethoxysilyl)hexane, trifluoropropyltrimethoxysilane, vinyltrimethoxysilane, and vinyltriethoxysilane, etc.

[0285] The average particle size of the low-refractive-index particles is preferably 5 nm to 200 nm, more preferably 10 nm to 150 nm. Furthermore, when the low-refractive-index particles are hollow particles, the average particle size is preferably 5 nm to 200 nm, more preferably 30 nm to 150 nm, and even more preferably 50 nm to 110 nm. If the average particle size is within the above range, the thickness of the low-refractive-index layer can be easily made uniform. In addition, by making the average particle size 5 nm or more, particle aggregation can be easily suppressed, and in the case of hollow particles, the refractive index of the low-refractive-index layer can be easily and sufficiently reduced. Furthermore, by making the average particle size 200 nm or less, whitening caused by particle diffusion and resulting reduction in visual recognizability can be easily suppressed.

[0286] The average particle size of low-refractive-index particles and high-refractive-index particles (described later) can be calculated by the following operations (1) to (3).

[0287] (1) The cross-section of the antireflective layer is photographed using TEM or STEM. The accelerating voltage of TEM or STEM is preferably 10kV or more and 30kV or less, and the magnification is preferably 50,000 times or more and 300,000 times or less.

[0288] (2) Extract any 10 particles from the observed image and calculate the particle size of each particle. The particle size is determined by the distance between the two lines that maximize the distance between the two lines when the cross-section of the particle is sandwiched between any two parallel lines.

[0289] (3) Perform the same operation 5 times in the observation images of other images of the same sample, and take the average value obtained by averaging the total number of 50 as the average particle size.

[0290] When the low-refractive-index layer contains binder resin and low-refractive-index particles, the content of low-refractive-index particles is preferably 20 to 250 parts by mass, more preferably 30 to 230 parts by mass, and even more preferably 40 to 200 parts by mass, relative to 100 parts by mass of binder resin in the low-refractive-index layer. If the content of low-refractive-index particles is within the above range, the balance between anti-reflective properties and scratch resistance can be improved.

[0291] Furthermore, the proportion of hollow particles relative to the total amount of low-refractive-index particles contained in the low-refractive-index layer is preferably 40% by mass or more, more preferably 50% by mass or more. By setting the proportion of hollow particles within the above range, the refractive index of the low-refractive-index layer can be sufficiently reduced, resulting in good anti-reflective properties.

[0292] Examples of curable resin compositions that can be used as binder resins in low-refractive-index layers include cured products of such compositions. The same material as the curable resin composition exemplified in hard coatings can be used as the curable resin composition; photocurable resin compositions are preferred.

[0293] Furthermore, the curable resin composition forming the adhesive resin preferably contains fluorinated compounds such as fluorinated oligomers and / or monomers having photocurable functional groups. By including fluorinated compounds, the refractive index of the low-refractive-index layer can be easily reduced, and the low-refractive-index layer can be endowed with antifouling and slip properties.

[0294] In addition, the thickness of the low refractive index layer is preferably about 1 / 4 of the wavelength region of visible light (about 100 nm), so for example, it is preferably 80 nm or more and 120 nm or less, more preferably 85 nm or more and 110 nm or less, and even more preferably 90 nm or more and 105 nm or less.

[0295] Examples of methods for forming low-refractive-index layers include wet and dry methods. Examples of wet methods include methods using metal alkoxides or the like to form the layer via sol-gel, methods using low-refractive-index resins, and methods using compositions containing binder resins and low-refractive-index particles to form the layer. Examples of dry methods include methods using low-refractive-index particles to form the layer via physical vapor deposition or chemical vapor deposition. Wet methods offer superior production efficiency, and methods using compositions containing binder resins and low-refractive-index particles to form the layer are preferred.

[0296] Furthermore, the refractive index of the high refractive index layer is preferably 1.55 or higher and 1.85 or lower, more preferably 1.56 or higher and 1.70 or lower. By making the refractive index of the high refractive index layer above a specified value, the anti-reflective properties become good. In fact, the upper limit of the high refractive index layer is 1.85 or lower.

[0297] Examples of high refractive index layers include those containing binder resin and high refractive index particles.

[0298] Examples of high refractive index particles include antimony pentoxide, zinc oxide, titanium oxide, cerium oxide, tin-doped indium oxide, antimony-doped tin oxide, yttrium oxide, and zirconium oxide.

[0299] The average particle size of the high refractive index particles is preferably 5 nm or more and 200 nm or less, more preferably 5 nm or more and 100 nm or less, and even more preferably 10 nm or more and 80 nm or less. By making the average particle size 5 nm or more, particle aggregation can be easily suppressed, and by making the average particle size 200 nm or less, whitening caused by particle diffusion and resulting reduction in visual recognizability can be easily suppressed.

[0300] From the perspective of balancing the high refractive index of the coating and the strength of the coating, the content of high refractive index particles is preferably 50 parts by mass and less than 500 parts by mass relative to 100 parts by mass of the adhesive resin, more preferably 100 parts by mass and less than 450 parts by mass, and even more preferably 200 parts by mass and less than 430 parts by mass.

[0301] Examples of curable resin compositions that can be used as binder resins in high-refractive-index layers include cured products of such compositions. The same material as the curable resin compositions exemplified in hard coatings can be used as the curable resin composition; photocurable resin compositions are preferred.

[0302] Furthermore, the thickness of the high refractive index layer is preferably 200 nm or less, more preferably 50 nm or more and 180 nm or less, and even more preferably 90 nm or more and 160 nm or less. By making the thickness of the high refractive index layer within the above range, low reflectivity can be exhibited in a wide wavelength region within the visible light region (380 nm to 780 nm).

[0303] As a method for forming a high refractive index layer, one example is a method of forming a high refractive index layer by coating a composition containing a binder resin and high refractive index particles.

[0304] The thickness of the anti-reflective layer can be the same as that of a regular anti-reflective layer, and can be appropriately selected based on the layer composition of the anti-reflective layer.

[0305] Methods for forming anti-reflective layers include coating and vapor deposition, which can be selected appropriately based on the material of the anti-reflective layer.

[0306] 6. Second bonding layer

[0307] In the laminated body of this embodiment, for example, Figure 4 As shown, a second bonding layer 10 can be disposed on the side of the glass substrate 2 opposite to the bonding layer 3. The second bonding layer is a layer used to bond the laminate to other components. Examples of other components include, for instance, a display panel in a display device described later. Furthermore, the second bonding layer is typically disposed on the outermost surface of the laminate.

[0308] It should be noted that, for ease of explanation, in this specification, the bonding layer disposed between the glass substrate and the substrate layer is referred to as the "bonding layer", and the bonding layer disposed on the side of the glass substrate opposite to the bonding layer is referred to as the "second bonding layer".

[0309] Here, one type of impact damage to glass substrates is bending damage. Bending damage is the phenomenon where the glass substrate bends due to an impact, and breaks when the bending reaches its limit. When an impact is applied instantaneously and locally to the surface of the glass substrate, the substrate deforms instantaneously and locally, generating tensile stress instantaneously and locally on the back side of the substrate. The back side of the glass substrate cannot withstand the tensile stress, resulting in cracks and fractures.

[0310] The inventors of this invention have conducted in-depth research on the impact resistance and flexural resistance of a laminate comprising a glass substrate, a bonding layer, and a hard coating layer in sequence, wherein the laminate further comprises a second bonding layer on the side of the glass substrate opposite to the bonding layer. The second bonding layer is generally softer than the glass substrate, the substrate layer, and the hard coating layer, and is therefore easily deformed by impact. Therefore, it is believed that if the deformation of the second bonding layer is large when an impact is applied to the laminate, the glass substrate is prone to instantaneous and localized deformation. In this case, the glass substrate is prone to flexural failure, and the impact resistance may decrease. Furthermore, it is known that when the laminate comprises a second bonding layer on the side of the glass substrate opposite to the bonding layer, the impact resistance varies significantly depending on the hardness, thickness, etc., of the second bonding layer. Furthermore, it was found that even when the above-mentioned laminate has a second bonding layer on the side of the glass substrate opposite to the bonding layer, when the ratio of the storage modulus (MPa) of the second bonding layer at 20°C to the thickness (μm) of the second bonding layer is within a specified range, the bending failure of the glass substrate can be suppressed, and good bending resistance can be obtained without compromising impact resistance.

[0311] That is, the ratio of the storage modulus (MPa) of the second bonding layer at 20°C to the thickness (μm) of the second bonding layer is preferably, for example, 0.001 to 0.4, more preferably 0.002 to 0.35, further preferably 0.003 to 0.3, and particularly preferably 0.004 to 0.2. As described above, the second bonding layer is generally softer than the glass substrate and the substrate layer and hard coating layer of the hard coating film, and therefore is easily deformed by impact. The thicker the second bonding layer, the greater the degree of deformation caused by impact. Therefore, if the ratio of the storage modulus to the thickness of the second bonding layer is too small, the thickness of the second bonding layer becomes relatively thicker, and the impact resistance may decrease. In addition, if the ratio of the storage modulus to the thickness of the second bonding layer becomes large, the effect of improving impact resistance saturates. Furthermore, if the ratio of the storage modulus to the thickness of the second bonding layer is too large, the thickness of the second bonding layer becomes relatively thin, the storage modulus of the second bonding layer becomes relatively large, and the bending resistance may decrease.

[0312] As described above, when a heat-sensitive adhesive or a curing adhesive is used in the aforementioned bonding layer, and further when a heat-sealing agent, a UV-curing adhesive, or a thermosetting adhesive is used, especially when a heat-sealing agent is used, it is easy to adjust the glass transition temperature and composite elastic modulus of the bonding layer to a preferred range, thereby improving impact resistance. Therefore, in such a case, when a second bonding layer is further configured, in order not to compromise impact resistance, the ratio of the storage modulus to the thickness of the second bonding layer is preferably within the aforementioned range.

[0313] Regarding the thickness of the second bonding layer, there is no particular limitation as long as the ratio of the storage modulus to the thickness of the second bonding layer is satisfied. For example, it is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less, and even more preferably 15 μm or more and 50 μm or less. When the thickness of the second bonding layer is a predetermined value or more, the adhesion is good. In particular, when the thickness of the second bonding layer is 15 μm or more, the adhesion is good, thus improving the bending resistance, especially the dynamic bending resistance. In addition, as mentioned above, the second bonding layer is generally softer than the glass substrate and the substrate layer and hard coating layer of the hard coating film, and therefore is easily deformed by impact. The thicker the second bonding layer, the greater the degree of deformation caused by impact tends to be. Therefore, when the thickness of the second bonding layer is less than a predetermined value, the reduction in impact resistance caused by the second bonding layer can be suppressed. In particular, when the thickness of the second bonding layer is 50 μm or less, good impact resistance can be obtained.

[0314] Regarding the storage modulus of the second bonding layer at 20°C, there is no particular limitation as long as the ratio of the storage modulus to the thickness of the second bonding layer is satisfied. For example, it is preferably 0.10 MPa to 10 MPa, more preferably 0.10 MPa to 5 MPa, and even more preferably 0.10 MPa to 3 MPa. By ensuring that the storage modulus of the second bonding layer is above a specified value and has a certain degree of hardness, good impact resistance can be maintained. In addition, by ensuring that the storage modulus of the second bonding layer is below a specified value, bending resistance, especially dynamic bending resistance, can be improved.

[0315] Here, the storage modulus E' of the second bonding layer at 20°C is a value measured using a dynamic viscoelasticity measuring device (DMA). When measuring the storage modulus E' of the second bonding layer using the DMA, firstly, a solution is prepared by dissolving or melting the material of the second bonding layer. The solution is then coated onto a substrate, dried, and the film is peeled off from the substrate, thereby obtaining a test piece of the second bonding layer. The solvent is appropriately selected depending on the material of the second bonding layer; examples include ethyl acetate. For example, a NAFLON (registered trademark) sheet (300mm × 300mm × 1mm thick) manufactured by NICHIAS can be used as the substrate. Then, the second bonding layer is wound to form... A cylindrical shape with a height of approximately 5mm. Used in the compression clamp (parallel plate) of a dynamic viscoelasticity measuring device. The cylindrical test sample described above is installed between the two layers. Then, a compressive load is applied, and longitudinal vibration at a frequency of 1 Hz is applied. Dynamic viscoelasticity is measured within a temperature range of -50°C to 200°C, and the storage modulus E' of the second bonding layer is measured at each temperature. For example, the RSAIII manufactured by TA Instruments can be used as the dynamic viscoelasticity measuring device. It should be noted that the specific measurement conditions in the above method are as follows.

[0316] (Determination conditions of storage modulus E')

[0317] • Sample to be measured: × Cylindrical shape with a height of 5mm

[0318] • Measuring fixture: Compression (parallel plate)

[0319] • Measurement mode: Temperature dependent (Temperature range: -50℃~200℃, Heating rate: 5℃ / min)

[0320] • Frequency: 1Hz

[0321] The energy storage modulus of the second bonding layer can be adjusted, for example, according to the type and composition of the materials contained in the second bonding layer.

[0322] Furthermore, as described later, when an optically transparent adhesive is used in the second bonding layer, the method for adjusting the storage modulus of the adhesive can be a known method for adjusting the elastic modulus, for example, adjusting the elastic modulus based on the crosslinking density, the type of monomer containing functional groups, etc. For example, if the crosslinking density increases, there is a tendency for the storage modulus to increase.

[0323] Furthermore, the glass transition temperature of the second bonding layer is preferably -50°C to 30°C, more preferably -50°C to 25°C, even more preferably -50°C to 0°C, particularly preferably -45°C to -5°C, and even more preferably -40°C to -5°C. If the glass transition temperature of the second bonding layer is within the above range, it is easy to obtain a second bonding layer that satisfies the aforementioned energy storage modulus. Additionally, when the glass transition temperature of the second bonding layer is -40°C or higher, low-temperature bending performance can be improved. Furthermore, when the glass transition temperature of the second bonding layer is 25°C or lower, room-temperature bending performance can be improved.

[0324] It should be noted that the method for determining the glass transition temperature of the second bonding layer can be the same as the method for determining the glass transition temperature of the bonding layer described above.

[0325] In addition, when the thickness (μm) of the second bonding layer is set to T1, the energy storage modulus (MPa) of the second bonding layer at 20°C is set to E'1, and the thickness (μm) of the glass substrate is set to T2, it is preferable to satisfy the following formula (4).

[0326] T2×E'1 / T1≥0.1 (4)

[0327] When the above formula (4) is satisfied, for example, even when the thickness of the glass substrate is relatively thin, the impact resistance can be improved if the energy storage modulus of the second bonding layer is large and the second bonding layer has a certain degree of hardness. The left side of the above formula (4) is preferably 0.1 or more and 30 or less.

[0328] When the laminate of this embodiment is used, for example, in a display device, the second bonding layer preferably has transparency. Specifically, the total light transmittance of the second bonding layer is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more.

[0329] In addition, the haze of the second bonding layer is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less.

[0330] The material used in the second bonding layer is preferably a material that satisfies the ratio of the energy storage modulus to the thickness of the second bonding layer, and examples include optically clear adhesives (OCA).

[0331] Examples of optically transparent adhesives include acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, and vinyl acetate adhesives. Among these, acrylic adhesives are preferred in terms of flexural strength, adhesion, and transparency. Commercially available products can also be used as optically transparent adhesives.

[0332] Examples of methods for configuring the second bonding layer include, for instance, coating an adhesive onto a glass substrate; or bonding a second bonding layer onto a glass substrate using a film-like second bonding layer.

[0333] 7. Second substrate layer and third bonding layer

[0334] In the laminated body of this embodiment, for example, Figure 3 As shown, a third bonding layer 8 and a second substrate layer 9 may be disposed on the side of the glass substrate 2 opposite to the bonding layer 3, starting from the glass substrate 2 side.

[0335] It should be noted that, for ease of explanation, in this specification, the bonding layer disposed between the glass substrate and the substrate layer is referred to as the "bonding layer," and the bonding layer disposed between the glass substrate and the second substrate layer is referred to as the "third bonding layer." Furthermore, the third bonding layer is not included in the aforementioned second bonding layer.

[0336] By configuring a third bonding layer and a second substrate layer on the side of the glass substrate opposite to the bonding layer, starting from the glass substrate side, it is possible to improve impact resistance while maintaining good flexural strength. The reasoning is speculated as follows.

[0337] The inventors of this invention have conducted in-depth research on cracks and fractures in glass substrates caused by impacts and have made a new discovery: when an impact is applied instantaneously and locally to the surface of a glass substrate, the glass substrate deforms instantaneously and locally, and tensile stress is generated instantaneously and locally on the back side of the glass substrate. The back side of the glass substrate cannot withstand the above tensile stress and thus cracks and fractures occur.

[0338] When a second substrate layer is disposed on the side (back side) of the glass substrate opposite to the bonding layer by a third bonding layer, instantaneous and localized deformation of the glass substrate caused by impact from the hard coating side of the laminate can be suppressed, and instantaneous and localized tensile stress generated on the back side of the glass substrate can be suppressed. Therefore, impact resistance can be improved.

[0339] (1) Second substrate layer

[0340] In this embodiment, the second substrate layer is disposed on the side of the glass substrate opposite to the bonding layer via the third bonding layer, and is used to suppress instantaneous and localized deformation of the glass substrate caused by impact. When the laminate of this embodiment is disposed on the observer side of the display panel of a display device, for example, the laminate is configured such that the surface of the second substrate layer faces the display panel. Furthermore, when the laminate of this embodiment is disposed on the surface of, for example, a resin molded article, the laminate is configured such that the surface of the second substrate layer faces the resin molded article.

[0341] In this embodiment, the composite elastic modulus of the second substrate layer is preferably 7.0 GPa or more, more preferably 7.3 GPa or more, and even more preferably 7.5 GPa or more. By setting the composite elastic modulus of the second substrate layer to the above range, instantaneous and localized deformation of the glass substrate caused by impact can be suppressed, cracks in the glass substrate caused by impact can be suppressed, and impact resistance can be improved. On the other hand, the composite elastic modulus of the second substrate layer is, for example, 100 GPa or less, 90 GPa or less, or 80 GPa or less. The composite elastic modulus of the second substrate layer is preferably 7.0 GPa or more and 100 GPa or less, more preferably 7.3 GPa or more and 90 GPa or less, and even more preferably 7.5 GPa or more and 80 GPa or less.

[0342] It should be noted that the method for determining the composite elastic modulus of the second substrate layer can be the same as the method for determining the composite elastic modulus of the bonding layer described above.

[0343] The composite elastic modulus of the second substrate layer can be adjusted, for example, by the type and composition of the materials contained in the second substrate layer.

[0344] When the laminate of this embodiment is used, for example, in a display device, the second substrate layer preferably has transparency. Specifically, the total light transmittance of the second substrate layer is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more.

[0345] In addition, the haze of the second substrate layer is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less.

[0346] The thickness of the second substrate layer is not particularly limited as long as it is sufficient to suppress instantaneous and localized deformation of the glass substrate caused by impact. For example, it is preferably 25 μm or more, more preferably 27 μm or more, and even more preferably 29 μm or more. The thicker the second substrate layer, the better the impact resistance. On the other hand, the thickness of the second substrate layer is preferably less than or equal to the thickness of the glass substrate, for example, preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less. If the thickness of the second substrate layer is too thick, the bending resistance may decrease. If the thickness of the second substrate layer is within the above range, the impact resistance can be improved while maintaining the bending resistance. The thickness of the second substrate layer is preferably 25 μm or more and 100 μm or less, more preferably 27 μm or more and 90 μm or less, and even more preferably 29 μm or more and 80 μm or less.

[0347] As the second substrate layer, there are no particular limitations as long as the composite elastic modulus described above is met; examples include glass layers, resin layers containing polyimide resins or aramid resins. Among these, a glass layer is preferred. Glass layers typically have a higher composite elastic modulus than resin layers, thus improving impact resistance.

[0348] When the second substrate layer is a glass layer, the glass constituting the glass layer can be the same as the glass constituting the glass substrate.

[0349] In addition, when the second substrate layer is a resin layer, examples of resins contained in the resin layer include polyimide resins and aromatic polyamide resins.

[0350] As for polyimide-based resins, there are no particular limitations as long as the above-mentioned composite elastic modulus is met; examples include polyimide and polyamide-imide. Regarding polyimide and polyamide-imide, when the above-mentioned substrate layer is a resin substrate, they can be the same as the polyimide and polyamide-imide contained in the resin substrate.

[0351] As an aromatic polyamide resin, there are no special limitations as long as the above-mentioned composite elastic modulus is met.

[0352] The resin layer may further contain additives as needed. Examples of additives include, for instance, UV absorbers, light stabilizers, antioxidants, inorganic particles, silica fillers to facilitate winding, surfactants to improve film-forming properties and defoaming properties, and adhesion enhancers.

[0353] As a method of configuring the second substrate layer, one example is a method in which the second substrate layer is bonded to the side of the glass substrate opposite to the bonding layer by means of a third bonding layer.

[0354] (2) Third bonding layer

[0355] In this embodiment, the third bonding layer is disposed between the glass substrate and the second substrate layer and is used to bond the glass substrate and the second substrate layer.

[0356] The thickness of the third bonding layer is preferably thinner than the thickness of the glass substrate, for example, preferably less than 100 μm, more preferably less than 50 μm, and even more preferably less than 25 μm. If the thickness of the third bonding layer is too thick, the bending resistance may be compromised. Furthermore, the third bonding layer is generally softer than the glass substrate and the second substrate layer, and therefore tends to deform easily upon impact; the thicker the third bonding layer, the greater the degree of deformation caused by impact. Therefore, it is considered that if the thickness of the third bonding layer is too thick, the degree of deformation of the third bonding layer increases when an impact is applied to the laminate, thereby making the glass substrate prone to instantaneous and localized deformation. In this case, the glass substrate is prone to cracking and breakage, and the impact resistance may decrease. On the other hand, the thickness of the third bonding layer is preferably, for example, 0.5 μm or more, more preferably 1 μm or more, and even more preferably 5 μm or more. If the thickness of the third bonding layer is too thin, the adhesion weakens, and peeling may occur. The thickness of the third bonding layer is preferably 0.5 μm or more and less than 100 μm, more preferably 1 μm or more and less than 50 μm, and even more preferably 5 μm or more and less than 25 μm.

[0357] The composite elastic modulus of the third bonding layer is preferably 1.0 MPa or more, more preferably 2.0 MPa or more, and even more preferably 3.0 MPa or more. By setting the composite elastic modulus of the third bonding layer to the above range, it possesses a certain degree of hardness, thereby improving impact resistance. Furthermore, as mentioned above, the third bonding layer is generally softer than the glass substrate and the second substrate layer, and therefore tends to deform easily upon impact; the smaller the composite elastic modulus of the third bonding layer, the greater the degree of deformation caused by impact. Therefore, it is considered that if the composite elastic modulus of the third bonding layer is too small, the degree of deformation of the third bonding layer will be greater when an impact is applied to the laminate, thereby easily causing instantaneous and localized deformation in the glass substrate. In this case, the glass substrate is prone to cracking and fracture, and the impact resistance may decrease. On the other hand, the composite elastic modulus of the third bonding layer is preferably 1.9 GPa or less, more preferably 1.8 GPa or less, and even more preferably 1.5 GPa or less. If the composite elastic modulus of the third bonding layer is within the above-mentioned range, it is softer than the glass substrate and the second substrate layer, thus absorbing impact and improving impact resistance. However, if the composite elastic modulus of the third bonding layer is too high, it may impair flexural resistance. The composite elastic modulus of the third bonding layer is preferably, for example, 1.0 MPa or more and 1.9 GPa or less, more preferably 2.0 MPa or more and 1.8 GPa or less, and even more preferably 3.0 MPa or more and 1.5 GPa or less.

[0358] The method for determining the composite elastic modulus of the third bonding layer can be the same as the method for determining the composite elastic modulus of the bonding layer described above.

[0359] The composite elastic modulus of the third bonding layer can be adjusted, for example, according to the type of material contained in the bonding layer.

[0360] Furthermore, as described later, when an optically transparent adhesive is used in the third bonding layer, the method for adjusting the composite elastic modulus of the adhesive can be a known method for adjusting the elastic modulus, for example, adjusting the elastic modulus based on the crosslinking density, the type of monomer containing functional groups, etc. For example, if the crosslinking density increases, there is a tendency for the composite elastic modulus to increase.

[0361] When the laminate of this embodiment is used, for example, in a display device, the third bonding layer preferably has transparency. Specifically, the total light transmittance of the third bonding layer is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more.

[0362] In addition, the haze of the third bonding layer is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less.

[0363] The material used in the third bonding layer is not particularly limited as long as it can bond the glass substrate and the second substrate layer. It is preferred to use a material that meets the above-mentioned composite elastic modulus and transparency. Examples of such materials include optically clear adhesives (OCA) and curing adhesives.

[0364] Examples of optically transparent adhesives include acrylic adhesives, urethane adhesives, silicone adhesives, epoxy adhesives, and vinyl acetate adhesives. Among these, acrylic adhesives are preferred in terms of flexural strength, adhesion, and transparency.

[0365] In particular, the optically transparent adhesive preferably meets the aforementioned composite elastic modulus. Commercially available products can be used as such optically transparent adhesives. Specifically, examples include 3M's "8146-2", Lintec's "MO-3018C", "F619", and "N632".

[0366] The curing adhesive can be the same as the curing adhesive used in the bonding layer described above.

[0367] 8. Protective film

[0368] In this embodiment, a protective film can be disposed on the side of the hard coating opposite to the bonding layer. This protective film can improve the impact resistance of the laminate while protecting it.

[0369] In this embodiment, as described above, by setting the ratio (A+B) / C of the hard coating thickness A, the substrate layer thickness B, and the bonding layer thickness C to a predetermined value or higher, the surface hardness of the hard coating side of the laminate can be increased, thereby improving damage resistance. Even when a protective film is provided, the protective film itself may suffer damage or dents, but the hard coating film has high surface hardness, thus exhibiting good damage resistance.

[0370] On the other hand, if the ratio of the aforementioned thicknesses (A+B) / C is less than the specified value, damage or dents may occur on the hard coating even when a protective film is provided.

[0371] 9. Properties of laminates

[0372] When the laminate in this embodiment is used in a display device, it is preferably transparent. Specifically, the total light transmittance of the laminate in this embodiment is preferably 80% or more, more preferably 85% or more, and even more preferably 88% or more. In this way, by having high total light transmittance, a laminate with good transparency can be manufactured.

[0373] Here, the total light transmittance of the laminate can be measured according to JIS K7361-1, for example, using the HM150 haze meter manufactured by the Murakami Color Technology Research Institute.

[0374] In this embodiment, the haze of the laminate is preferably 2% or less, more preferably 1.5% or less, and even more preferably 1% or less. By making the haze so low, a laminate with good transparency can be produced.

[0375] Here, the haze of the laminate can be measured according to JIS K-7136, for example, using the HM150 haze meter manufactured by the Murakami Color Technology Laboratory.

[0376] The laminate in this embodiment preferably has bending resistance. Specifically, in the laminate of this embodiment, when subjected to the dynamic bending test described below, it is preferable that the laminate does not crack, break, or peel off.

[0377] In dynamic bending tests, the laminate can be folded with the glass substrate on the outside or with the glass substrate on the inside. In either case, it is preferable that the laminate does not produce cracks, fractures, or peeling.

[0378] The dynamic bending test is conducted as follows. For example... Figure 5 As shown in (a), in the dynamic bending test, firstly, the short side 1C and the short side 1D facing the short side 1C of the 20mm×100mm laminate 1 are fixed respectively by the parallel-arranged fixing parts 21. Furthermore, as... Figure 5 As shown in (a), the fixing part 21 can slide in the horizontal direction. Next, as... Figure 5 As shown in (b), the movable fixing parts 21 are brought closer together, thereby deforming the laminate 1 in a folding manner, and then, as... Figure 5 As shown in (c), after the fixing part 21 is moved to a position where the interval d between the two opposing short sides 1C and 1D fixed by the fixing part 21 of the laminate 1 is a predetermined value, the fixing part 21 is moved in the opposite direction to eliminate the deformation of the laminate 1. This is achieved through... Figure 5 The movable fixing part 21 shown in (a) to (c) allows the laminate 1 to be folded 180°. Furthermore, by conducting a dynamic bending test with the bent portion 1E of the laminate 1 not protruding from the lower end of the fixing part 21, and by controlling the interval d when the fixing parts 21 are closest, the interval d between the two opposing short sides 1C and 1D of the laminate 1 can be set to a predetermined value. For example, when the interval d between the two opposing short sides 1C and 1D is 10 mm, the outer diameter of the bent portion 1E is considered to be 10 mm.

[0379] In the laminate, preferably, no cracks, fractures, or peeling occur when the short sides 1C and 1D of the laminate 1 are repeatedly folded 180° 200,000 times with an interval d of 10 mm between the opposing short sides 1C and 1D. More preferably, no cracks, fractures, or peeling occur when the short sides 1C and 1D of the laminate 1 are repeatedly folded 180° 200,000 times with an interval d of 8 mm between the opposing short sides 1C and 1D.

[0380] Here, in the dynamic bending test, "crack" refers to the phenomenon of cracks forming in the laminate. "Fracture" refers to the phenomenon of the laminate completely breaking into two parts. "Peeling" refers to the phenomenon of any layer of the laminate peeling off or lifting off.

[0381] Furthermore, in the laminated body of this embodiment, when the laminated body is subjected to the static bending test described below, the angle θ after the static bending test is preferably 100° or more, and more preferably 130° or more.

[0382] The static bending test is conducted as follows. First, as... Figure 6 As shown in (a), a 20mm × 100mm laminate 1 has its short side 1C and short side 1D facing the short side 1C fixed with parallel fixing parts 22, such that the distance d between the short side 1C and the short side 1D is 10mm. Next, with the laminate 1 folded, a static bending test is performed at 23°C for 240 hours. Afterwards, as... Figure 6As shown in (b), after the static bending test, the fixing part 22 was removed from the short side 1D, thereby opening the folded state. The angle at which the laminate 1 naturally opened after 30 minutes at room temperature was measured, i.e., the opening angle θ. It should be noted that the larger the opening angle θ, the better the recovery, with a maximum of 180°.

[0383] In the static bending test, the laminate can be folded with the glass substrate as the inside or with the glass substrate as the outside. In either case, the angle θ is preferably 100° or more, and more preferably 130° or more.

[0384] In the laminated body of this embodiment, when the laminated body is subjected to the puncture test described below, the puncture breaking force is preferably 16N or more, more preferably 19N or more, and even more preferably 25N or more. If the puncture breaking force is within the above range, the impact resistance becomes good.

[0385] The puncture test was conducted as follows. First, a test laminate was prepared by bonding a 50 μm thick optically clear adhesive film (OCA) (manufactured by 3M, "8146-2", composite elastic modulus 9.6 MPa) to the glass substrate side of the laminate, along with a 100 μm thick PET film (manufactured by Toyobo, "A4160 (current model)" ("A4100 (old model)"), composite elastic modulus 6.9 GPa). Next, for the test laminate, a Tensilon universal testing machine (RTC-1310A) manufactured by A&D was used to perform a puncture test from the hard coating side of the test laminate toward the PET film side, under conditions of a needle tip curvature radius of 0.5 mm and a puncture speed of 50 mm / min. At this time, the stroke and load on the surface of the test laminate were set to zero for measurement. Then, the maximum stress at which the glass substrate broke was taken as the puncture fracture force.

[0386] 10. Applications of laminates

[0387] The application of the laminate in this embodiment is not particularly limited. For example, in a display device, it can be used as a component disposed on the observer side of the display panel. The laminate in this embodiment can be used in display devices such as smartphones, tablet terminals, wearable terminals, personal computers, televisions, digital signage, public information displays (PIDs), and vehicle displays.

[0388] The laminate in this embodiment exhibits good bending and impact resistance, making it suitable for use as a component capable of handling curved surfaces. The laminate of this invention is preferably used, for example, in flexible displays such as foldable displays, rollable displays, bendable displays, and slidable displays, and is more preferably used in foldable displays. Furthermore, the laminate in this embodiment can also be used, for example, as a surface material for resin molded articles with curved surfaces, imparting design and aesthetic appeal.

[0389] In this embodiment, when the laminate is disposed on the surface of a display device, a resin molded article, etc., the glass substrate side is the inner side and the hard coating side is the outer side.

[0390] There are no particular limitations on the method for disposing the laminate of this embodiment on the surface of a display device, resin molded article, etc., and methods such as using an adhesive layer can be cited as examples. As the adhesive layer, a known adhesive layer used in the bonding of laminates can be used.

[0391] II. Second Implementation

[0392] The inventors of this invention conducted in-depth research on laminates having a glass substrate and discovered that by depositing a resin layer on the surface of a thin glass substrate, thereby increasing the thickness of the resin layer, cracking of the glass substrate can be suppressed and impact resistance improved. However, it is known that when a thicker resin layer is formed by coating the surface of the glass substrate with a resin composition, the effect of the shrinkage difference between the glass substrate and the resin layer becomes greater during heating or curing after the resin composition is applied, sometimes resulting in curling. Furthermore, the inventors of this invention conducted further repeated research and discovered that by pre-filming the resin layer and then bonding the resin film to the surface of a thin glass substrate via an adhesive layer, it is possible to further improve impact resistance while suppressing curling.

[0393] However, in order to bond the above-mentioned laminate to other components, a second bonding layer can be disposed on the side of the glass substrate opposite to the bonding layer in the above-mentioned laminate. The inventors of the present invention further studied a laminate having a second bonding layer, a glass substrate, a bonding layer and a resin film in sequence. And found that in such a laminate, the impact resistance is sometimes reduced depending on the type of the second bonding layer.

[0394] This embodiment is based on the above-mentioned actual situation, and its purpose is to provide a laminate that can take into account both bending resistance and impact resistance.

[0395] The second embodiment of the laminate in this invention is a laminate having a hard coating layer, a substrate layer, a bonding layer, a glass substrate and a second bonding layer in sequence, wherein the bonding layer is a layer that bonds the glass substrate to the substrate layer, the second bonding layer is a layer that bonds the laminate to other components, the thickness of the glass substrate is 10 μm or more and 100 μm or less, and the laminate satisfies the following formula (1).

[0396] 0.001≤{(E1×D1 2 +E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (1)

[0397] (In the above formula (1), E1 represents the composite elastic modulus (GPa) of the hard coating, D1 represents the thickness (mm) of the hard coating, E2 represents the composite elastic modulus (GPa) of the substrate layer, D2 represents the thickness (mm) of the substrate layer, E3 represents the composite elastic modulus (GPa) of the bonding layer, D3 represents the thickness (mm) of the bonding layer, E4 represents the composite elastic modulus (GPa) of the glass substrate, D4 ​​represents the thickness (mm) of the glass substrate, E5 represents the storage modulus (GPa) of the second bonding layer, D5 represents the thickness (mm) of the second bonding layer.)

[0398] Figure 7 This is a schematic cross-sectional view illustrating an example of a laminated body in this embodiment. (See diagram below.) Figure 7 As shown, the laminate 1 sequentially comprises a hard coating layer 6, a substrate layer 5, a bonding layer 3, a glass substrate 2, and a second bonding layer 10. The glass substrate 2 has a specified thickness. Furthermore, the composite elastic modulus E1 and thickness D1 of the hard coating layer 6, the composite elastic modulus E2 and thickness D2 of the substrate layer 5, the composite elastic modulus E3 and thickness D3 of the bonding layer 3, the composite elastic modulus E4 and thickness D4 of the glass substrate 2, and the energy storage modulus E5 and thickness D5 of the second bonding layer 10 satisfy the above equation (1).

[0399] In the laminate of this embodiment, the thickness of the glass substrate is less than a specified value and relatively thin, thus improving the bending resistance. On the other hand, the thickness of the glass substrate is less than a specified value and relatively thin, so it may be prone to breakage and have low impact resistance. In contrast, in this embodiment, by sequentially configuring a hard coating layer, a substrate layer, a bonding layer, a glass substrate, and a second bonding layer, the elastic modulus and thickness of each layer satisfy the above formula (1), which can improve the impact resistance while maintaining good bending resistance. The reason for this is speculated as follows.

[0400] Here, impact damage to glass can be broadly categorized into two types. The first is bending damage. The second is Hertzian damage, also known as stress concentration damage. Bending damage occurs on the side of the glass opposite to the impact surface. On the other hand, Hertzian damage occurs on the impact surface of the glass.

[0401] The inventors of this invention have conducted in-depth research on the impact resistance and bending resistance of a laminate comprising a hard coating layer, a substrate layer, a bonding layer, a glass substrate, and a second bonding layer in sequence. The second bonding layer is generally softer than the glass substrate, the substrate layer, and the hard coating layer, and is therefore easily deformed by impact. Therefore, it is believed that if the second bonding layer deforms significantly when an impact is applied to the laminate, the glass substrate is prone to instantaneous and localized deformation. In this case, there is concern that the glass substrate is susceptible to bending failure. On the other hand, it is believed that bending failure of the glass substrate can be suppressed when the thickness of the second bonding layer is relatively thin. Furthermore, it is believed that bending failure of the glass substrate can also be suppressed when the hardness of the second bonding layer is relatively hard. However, even if bending failure of the glass substrate can be suppressed by making the thickness of the second bonding layer relatively thin or the hardness of the second bonding layer relatively hard, Hertzian failure of the glass substrate cannot be suppressed. To suppress Hertzian failure of the glass substrate, it is preferable to make the thickness of the hard coating layer, the substrate layer, and the bonding layer relatively thick, or to make the hardness of the hard coating layer, the substrate layer, and the bonding layer relatively hard. Furthermore, among the layers, the thickness of the glass substrate has the greatest impact on impact failure of the glass substrate. However, by making the thickness of the hard coating, substrate layer, and bonding layer relatively thick, or by making the hard coating, substrate layer, and bonding layer relatively hard, even if Hertzian failure of the glass substrate can be suppressed, the bending resistance may be reduced. Furthermore, by increasing the thickness of the glass substrate, even if impact failure of the glass substrate can be suppressed, the bending resistance may be reduced. Based on the influence of the thickness and hardness of each layer on impact resistance and bending resistance, and the experimental results described in the examples and comparative examples below, the above-mentioned equation (1) representing the correlation between the thickness and elastic modulus of each layer and impact resistance and bending resistance is derived.

[0402] If the intermediate value of equation (1) is too small, the thickness of the second bonding layer will be relatively thicker, or the storage modulus of the second bonding layer will be relatively lower. Therefore, the glass substrate is prone to bending failure, and the impact resistance may be reduced. On the other hand, if the intermediate value of equation (1) is too large, the thickness of the glass substrate, hard coating, substrate layer and bonding layer will be relatively thicker, or the composite elastic modulus of the hard coating, substrate layer and bonding layer will be relatively higher. Therefore, the bending resistance may be reduced. Therefore, in this embodiment, by making the elastic modulus and thickness of each layer satisfy equation (1) above, it is possible to improve the impact resistance while maintaining good bending resistance.

[0403] Thus, in this embodiment, good bending resistance is maintained while impact resistance is improved. Furthermore, even if the glass substrate in the laminate breaks, the risk of injury to the human body is reduced, enabling the creation of a highly safe laminate. Therefore, the laminate of this embodiment is bendable and can be used for a wide variety of applications. For example, the laminate of this embodiment can be used in a variety of display devices; specifically, it can be used as a component for foldable displays.

[0404] The laminate in this embodiment satisfies the following equation (1).

[0405] 0.001≤{(E1×D1 2 +E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (1)

[0406] (In the above formula (1), E1 represents the composite elastic modulus (GPa) of the hard coating, D1 represents the thickness (mm) of the hard coating, E2 represents the composite elastic modulus (GPa) of the substrate layer, D2 represents the thickness (mm) of the substrate layer, E3 represents the composite elastic modulus (GPa) of the bonding layer, D3 represents the thickness (mm) of the bonding layer, E4 represents the composite elastic modulus (GPa) of the glass substrate, D4 ​​represents the thickness (mm) of the glass substrate, E5 represents the storage modulus (GPa) of the second bonding layer, D5 represents the thickness (mm) of the second bonding layer.)

[0407] The intermediate value of the above formula (1) is 0.001 to 3, preferably 0.0015 to 1.5, more preferably 0.003 to 1, further preferably 0.005 to 0.7, and particularly preferably 0.01 to 0.4. As described above, if the intermediate value of the above formula (1) is too small, the thickness of the second bonding layer becomes relatively thicker, or the storage modulus of the second bonding layer becomes relatively lower. Therefore, the glass substrate is prone to bending failure, and the impact resistance may decrease. In addition, if the intermediate value of the above formula (1) is too large, the thickness of the glass substrate, hard coating, substrate layer and bonding layer becomes relatively thicker, or the composite elastic modulus of the hard coating, substrate layer and bonding layer becomes relatively higher. Therefore, the bending resistance may decrease.

[0408] Furthermore, as described above, by making the thickness of the second bonding layer relatively thin or the hardness of the second bonding layer relatively hard, even if bending failure of the glass substrate can be suppressed, Hertzian failure of the glass substrate cannot be suppressed. Therefore, if the value of the middle part of the above formula (1) is above a predetermined value, the effect of suppressing bending failure of the glass substrate is saturated. Therefore, the value of the middle part of the above formula (1) is preferably 0.4 or less.

[0409] The thickness of the hard coating, the thickness of the substrate layer, the thickness of the bonding layer, the thickness of the glass substrate, and the thickness of the second bonding layer are the same as the thickness of each layer in the laminate of the first embodiment described above.

[0410] The composite elastic modulus of the hard coating is preferably 4 GPa to 10 GPa, more preferably 5 GPa to 9 GPa, and even more preferably 6 GPa to 8 GPa. If the composite elastic modulus of the hard coating is too small, sufficient damage resistance may not be obtained. On the other hand, if the composite elastic modulus of the hard coating is too large, the hardness becomes too high and it is difficult to bend, and the bending resistance, especially the dynamic bending resistance, may be reduced.

[0411] The method for determining the composite elastic modulus of the hard coating is the same as the method for determining the composite elastic modulus of the bonding layer in the first embodiment described above.

[0412] The composite elastic modulus of a hard coating can be adjusted, for example, by the type and composition of the materials contained in the hard coating.

[0413] The composite elastic modulus of the substrate layer is the same as that of the substrate layer in the first embodiment described above.

[0414] The composite elastic modulus of the bonding layer is the same as that of the bonding layer in the first embodiment described above.

[0415] The composite elastic modulus of the glass substrate is preferably 40 GPa or more and 100 GPa or less, more preferably 50 GPa or more and 90 GPa or less, and even more preferably 60 GPa or more and 80 GPa or less.

[0416] The energy storage modulus of the second bonding layer is the energy storage modulus at 20°C. The energy storage modulus of the second bonding layer is the same as that of the second bonding layer in the first embodiment described above.

[0417] The hard coating layer, substrate layer, bonding layer, glass substrate, and second bonding layer in this embodiment are the same as those in the first embodiment described above.

[0418] The laminate of this embodiment may further have a functional layer on the side of the hard coating opposite to the substrate layer, between the hard coating and the substrate layer, between the substrate layer and the bonding layer, between the glass substrate and the bonding layer, or between the glass substrate and the second bonding layer. The functional layer is the same as the functional layer in the first embodiment described above.

[0419] In this embodiment of the laminate, a protective film may be disposed on the side of the hard coating layer opposite to the substrate layer. The protective film is the same as the protective film in the first embodiment described above.

[0420] The characteristics and uses of the laminate in this embodiment are the same as those of the laminate in the first embodiment described above.

[0421] III. Third Implementation

[0422] Similar to the second embodiment described above, the purpose of this embodiment is to provide a laminate that can balance bending resistance and impact resistance.

[0423] The third embodiment of the laminate in the present invention is a laminate having a substrate layer, a bonding layer, a glass substrate and a second bonding layer in sequence, wherein the bonding layer is a layer that bonds the glass substrate to the substrate layer, the second bonding layer is a layer that bonds the laminate to other components, the thickness of the glass substrate is 10 μm or more and 100 μm or less, and the laminate satisfies the following formula (2).

[0424] 0.001≤{(E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (2)

[0425] (In the above formula (2), E2 represents the composite elastic modulus of the substrate layer (GPa), D2 represents the thickness of the substrate layer (mm), E3 represents the composite elastic modulus of the bonding layer (GPa), D3 represents the thickness of the bonding layer (mm), E4 represents the composite elastic modulus of the glass substrate (GPa), D4 represents the thickness of the glass substrate (mm), E5 represents the storage modulus of the second bonding layer (GPa), D5 represents the thickness of the second bonding layer (mm).)

[0426] Figure 8 This is a schematic cross-sectional view illustrating an example of a laminated body in this embodiment. (See diagram below.) Figure 7 As shown, the laminate 1 sequentially comprises a substrate layer 5, a bonding layer 3, a glass substrate 2, and a second bonding layer 10. The glass substrate 2 has a specified thickness. Furthermore, the composite elastic modulus E2 and thickness D2 of the substrate layer 5, the composite elastic modulus E3 and thickness D3 of the bonding layer 3, the composite elastic modulus E4 and thickness D4 of the glass substrate 2, and the energy storage modulus E5 and thickness D5 of the second bonding layer 10 satisfy the above equation (2).

[0427] In the laminate of this embodiment, the thickness of the glass substrate is less than a specified value and relatively thin, thus improving the bending resistance. On the other hand, the thickness of the glass substrate is less than a specified value and relatively thin, so it may be prone to breakage and have low impact resistance. In contrast, in this embodiment, by sequentially arranging a substrate layer, a bonding layer, a glass substrate, and a second bonding layer, the elastic modulus and thickness of each layer satisfy the above formula (2), which can improve the impact resistance while maintaining good bending resistance. The reason for this is speculated as follows.

[0428] The inventors of this invention have conducted in-depth research on the impact resistance and bending resistance of a laminate having a substrate layer, a bonding layer, a glass substrate, and a second bonding layer in sequence. The second bonding layer is generally softer than the glass substrate and the substrate layer, and therefore easily deformed upon impact. Therefore, it is believed that if the second bonding layer deforms significantly when an impact is applied to the laminate, the glass substrate is prone to instantaneous and localized deformation. In this case, there is concern that the glass substrate is susceptible to bending failure. On the other hand, it is believed that a relatively thin second bonding layer can suppress bending failure of the glass substrate. Furthermore, it is believed that a relatively hard second bonding layer can also suppress bending failure of the glass substrate. However, even if bending failure of the glass substrate can be suppressed by making the second bonding layer relatively thin or relatively hard, Hertzian failure of the glass substrate cannot be suppressed. To suppress Hertzian failure of the glass substrate, it is preferable to make the substrate layer and the bonding layer relatively thick, or to make the substrate layer and the bonding layer relatively hard. Furthermore, among the layers, the thickness of the glass substrate has the greatest impact on impact failure of the glass substrate. However, by making the thickness of the substrate layer and the bonding layer relatively thick, or by making the hardness of the substrate layer and the bonding layer relatively high, even if Hertzian failure of the glass substrate can be suppressed, the bending resistance may be reduced. Furthermore, by increasing the thickness of the glass substrate, even if impact failure of the glass substrate can be suppressed, the bending resistance may be reduced. Based on the influence of the thickness and hardness of each layer on impact resistance and bending resistance, and the experimental results described in the examples and comparative examples below, the above-mentioned equation (2) representing the correlation between the thickness and elastic modulus of each layer and impact resistance and bending resistance is derived.

[0429] If the intermediate value of equation (2) is too small, the thickness of the second bonding layer will be relatively thicker, or the storage modulus of the second bonding layer will be relatively lower. Therefore, the glass substrate is prone to bending failure, and the impact resistance may be reduced. On the other hand, if the intermediate value of equation (2) is too large, the thickness of the glass substrate, the substrate layer and the bonding layer will be relatively thicker, or the composite elastic modulus of the substrate layer and the bonding layer will be relatively higher. Therefore, the bending resistance may be reduced. Therefore, in this embodiment, by making the elastic modulus and thickness of each layer satisfy equation (2) above, it is possible to improve the impact resistance while maintaining good bending resistance.

[0430] Thus, in this embodiment, impact resistance is improved while maintaining good bending resistance. Furthermore, even if the glass substrate in the laminate breaks, the risk of injury to the human body is reduced, enabling the creation of a highly safe laminate. Therefore, the laminate of this embodiment is bendable and can be used for a wide variety of applications. For example, the laminate of this embodiment can be used in a variety of display devices; specifically, it can be used as a component for foldable displays.

[0431] The laminate in this embodiment satisfies the following equation (2).

[0432] 0.001≤{(E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (2)

[0433] (In the above formula (2), E2 represents the composite elastic modulus of the substrate layer (GPa), D2 represents the thickness of the substrate layer (mm), E3 represents the composite elastic modulus of the bonding layer (GPa), D3 represents the thickness of the bonding layer (mm), E4 represents the composite elastic modulus of the glass substrate (GPa), D4 represents the thickness of the glass substrate (mm), E5 represents the storage modulus of the second bonding layer (GPa), D5 represents the thickness of the second bonding layer (mm).)

[0434] The intermediate value of the above formula (2) is 0.001 to 3, preferably 0.0015 to 1.5, more preferably 0.003 to 1, further preferably 0.005 to 0.7, and particularly preferably 0.01 to 0.4. As described above, if the intermediate value of the above formula (2) is too small, the thickness of the second bonding layer becomes relatively thicker, or the storage modulus of the second bonding layer becomes relatively lower. Therefore, the glass substrate is prone to bending failure, and the impact resistance may decrease. In addition, if the intermediate value of the above formula (2) is too large, the thickness of the glass substrate, the substrate layer and the bonding layer becomes relatively thicker, or the composite elastic modulus of the substrate layer and the bonding layer becomes relatively higher. Therefore, the bending resistance may decrease.

[0435] Furthermore, as described above, by making the thickness of the second bonding layer relatively thin or the hardness of the second bonding layer relatively hard, even if bending failure of the glass substrate can be suppressed, Hertzian failure of the glass substrate cannot be suppressed. Therefore, if the value of the middle part of the above formula (2) is above a predetermined value, the effect of suppressing bending failure of the glass substrate is saturated. Thus, the value of the middle part of the above formula (2) is preferably 0.4 or less.

[0436] The thickness of the substrate layer, the thickness of the bonding layer, the thickness of the glass substrate, and the thickness of the second bonding layer are the same as the thickness of each layer in the laminate of the first embodiment described above.

[0437] The composite elastic modulus of the substrate layer is the same as that of the substrate layer in the first embodiment described above.

[0438] The composite elastic modulus of the bonding layer is the same as that of the bonding layer in the first embodiment described above.

[0439] The composite elastic modulus of the glass substrate is the same as that of the glass substrate in the second embodiment described above.

[0440] The energy storage modulus of the second bonding layer is the energy storage modulus at 20°C. The energy storage modulus of the second bonding layer is the same as that of the second bonding layer in the first embodiment described above.

[0441] The substrate layer, bonding layer, glass substrate, and second bonding layer in this embodiment are the same as those in the first embodiment described above.

[0442] The laminate of this embodiment may further have a functional layer on the side of the substrate layer opposite to the bonding layer, between the substrate layer and the bonding layer, between the glass substrate and the bonding layer, or between the glass substrate and the second bonding layer. The functional layer is the same as the functional layer in the first embodiment described above.

[0443] In this embodiment of the laminate, a protective film may be disposed on the side of the substrate layer opposite to the bonding layer. The protective film is the same as the protective film in the first embodiment described above.

[0444] The characteristics and uses of the laminate in this embodiment are the same as those of the laminate in the first embodiment described above.

[0445] B. Display device

[0446] The display device of the present invention includes a display panel and a laminate disposed on the observer side of the display panel, wherein the laminate is configured such that the surface of the glass substrate faces the display panel. That is, the display device of the present invention includes a display panel and a laminate disposed on the observer side of the display panel, wherein the surface of the laminate is configured such that the surface of the glass substrate is adjacent to the display panel.

[0447] Figure 9 This is a schematic cross-sectional view illustrating an example of a display device according to the present invention. Figure 9As shown, the display device 30 includes a display panel 31 and a laminate 1 disposed on the observer side of the display panel 31. The laminate 1 is configured such that the surface on the glass substrate 2 side is adjacent to the display panel 31. In the display device 30, the laminate 1 serves as a component disposed on the surface of the display device 30, and an adhesive layer 32 is disposed between the laminate 1 and the display panel 31.

[0448] The laminate in this invention can be the same as the laminate described above.

[0449] Examples of display panels used in display devices such as liquid crystal display devices, organic EL display devices, and LED display devices can be cited as display panels in this invention.

[0450] The display device of the present invention may have a touch panel component between the display panel and the laminate.

[0451] The display device of the present invention is preferably a flexible display. More preferably, the display device of the present invention is foldable. That is, the display device of the present invention is more preferably a foldable display. Because the display device of the present invention has the above-described laminate, it exhibits excellent impact resistance and bending resistance, making it suitable as a flexible display, and further as a foldable display.

[0452] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are illustrative examples; any embodiment that has a substantially similar structure to the technical concept described in the claims of the present invention and can achieve the same effect is included within the technical scope of the present invention.

[0453] Example

[0454] The following examples and comparative examples are shown to further illustrate the present invention.

[0455] [Comparative Example 1]

[0456] A chemically strengthened glass substrate with a thickness of 70 μm is used.

[0457] [Example 1]

[0458] (1) Preparation of hard coating

[0459] (1-1) Fabrication of the substrate layer

[0460] Referring to Synthesis Example 1 of International Publication No. 2014 / 046180, the tetracarboxylic acid dianhydride shown in the following chemical formula was synthesized.

[0461] [Chemistry 6]

[0462]

[0463] A 500 mL detachable flask was purged with nitrogen. 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 added. The solution temperature was maintained at 30 °C. 24.8 g (40.1 mmol) of tetracarboxylic acid dianhydride (TMPBPTME) was slowly added to the solution, with the temperature rising by less than 2 °C. The mixture was stirred for 3 hours using a mechanical stirrer. Then, 0.91 g (4.5 mmol) of terephthaloyl chloride (TPC) was added to the solution, and the mixture was 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 were added as catalysts. The mixture was stirred at 25 °C for 30 minutes to ensure homogeneity, then heated to 70 °C and stirred for 1 hour. Subsequently, 174.26 g of 2-propanol (IPA) was slowly added to the solution cooled to room temperature, resulting in a slightly turbid solution. Then, 435.64 g of IPA was added to the turbid solution in one go, yielding a white slurry. The slurry was filtered, washed five times with IPA, and then dried under reduced pressure in an oven at 100°C for 6 hours to obtain 37.1 g of polyamide-imide powder. The weight-average molecular weight of the polyamide-imide, determined by GPC, was 62,000.

[0464] DMAc was added to polyamide-imide to prepare a polyamide-imide varnish with a polyamide-imide content of 19% by mass. The polyamide-imide varnish (19% by mass solids) had a viscosity of 4000 mPa·s at 25°C.

[0465] Following the method described later in the circulating oven, the film thickness after drying was as shown in Table 1. A polyamide-imide varnish (19% by mass solids) was applied to a glass plate. Then, after drying in a circulating oven at 120°C for 10 minutes, the plate was cooled to 25°C, and the polyimide resin coating was peeled off.

[0466] The peeled polyimide resin coating was cut into 150mm × 200mm pieces. Two metal frames (external dimensions 150mm × 200mm, internal dimensions 130mm × 180mm) were used to clamp the cut polyimide resin coating, and the metal frames were fixed to the polyimide resin coating using a fixing clamp. The fixed polyimide resin coating was heated to 300℃ in a circulating oven under a nitrogen flow (oxygen concentration below 100ppm) at a heating rate of 10℃ / min. After holding at 300℃ for 1 hour, it was cooled to 25℃ to produce a single-layer polyimide resin film.

[0467] (1-2) Formation of hard coating

[0468] Prepare a curable resin composition for hard coating by mixing the components as shown below.

[0469] <Composition of Curable Resin Composition for Hard Coating>

[0470] • A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (M403, manufactured by Toa Synthetic Co., Ltd.) 25 kg

[0471] • Dipentaerythritol EO-modified hexaacrylate (A-DPH-6E, manufactured by Shin-Nakamura Chemical Co., Ltd.) 25 parts by weight

[0472] • 50 parts by weight of irregularly shaped silica microparticles (average particle size 25nm, manufactured by Nichibukai Chemical Co., Ltd.) (converted from solid content)

[0473] • Photopolymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV) 4 parts by weight

[0474] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0475] • 3 parts by weight of UV absorber 1 (DAINSORB P6, manufactured by Yamato Kasei)

[0476] Solvent (MIBK) 150 parts by weight

[0477] Next, the above-mentioned hard coating material was applied to the substrate layer with a cured film thickness of 10 μm. After drying at 70°C for 1 minute, it was then subjected to an irradiation dose of 200 mJ / cm². 2 Irradiate with ultraviolet light to cure it, forming a hard coating. This results in a hard coating film.

[0478] (2) Fabrication of laminates

[0479] On the substrate side of the aforementioned hard coating film, a 25 μm thick bonding layer (acrylic adhesive sheet, OCA) (manufactured by 3M "8146-1") is bonded using a hand roller to obtain a hard coating film with a bonding layer. Next, the bonding layer side of the hard coating film with a bonding layer is bonded to a 70 μm thick chemically strengthened glass substrate using a hand roller to obtain a laminate.

[0480] [Examples 2-9 and Comparative Examples 2-4]

[0481] The thickness of the substrate layer of the hard coating film was varied as shown in Table 1 below, and the "PANACLEAN PD-S1" manufactured by PANAC Corporation (acrylic adhesive sheet, OCA) was used as the bonding layer when the thickness of the bonding layer was 15 μm, 10 μm or 5 μm. Otherwise, the laminate was obtained in the same manner as in Example 1.

[0482] [Example 10]

[0483] (1) Preparation of hard coating

[0484] The hard coating was prepared in the same manner as in Example 7.

[0485] (2) Formation of the heat-sensitive adhesive layer

[0486] A heat-sealing resin composition is prepared by mixing the components in the manner shown below.

[0487] <Composition of the heat-sealing resin composition>

[0488] • 100 parts by weight of amorphous polyester resin (Vylon 560, manufactured by Toyobo Co., Ltd.)

[0489] · 5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)

[0490] · 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0491] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0492] Solvent (MEK) 310 parts by weight

[0493] Solvent (toluene) 310 parts by weight

[0494] Next, the heat-sealing resin composition is applied to the substrate layer side of the hard coating film with a dried film thickness of 5 μm, and dried at 70°C for 1 minute to form a heat-sensitive adhesive layer, thereby obtaining a hard coating film with a heat-sensitive adhesive layer.

[0495] (3) Fabrication of laminates

[0496] The aforementioned hard coating film with a heat-sensitive adhesive layer was configured such that the side with the heat-sensitive adhesive layer was bonded to a 70 μm thick chemically strengthened glass substrate. A 2 mm thick glass support substrate was placed on the opposite side of the glass substrate from the hard coating film with the heat-sensitive adhesive layer. The hard coating film with the heat-sensitive adhesive layer and the glass substrate were bonded together using a roller laminator (manufactured by ACCO BRANDS JAPAN, trade name: Benchtop Roller Laminator B35A3) while heated, to obtain a laminate. At this time, the roller temperature was set to 140℃~149℃, and the feed speed was set to 0.3 m / min. The laminate was then aged at 70℃ for 2 days.

[0497] [Examples 11-14 and Comparative Example 5]

[0498] The thickness of the bonding layer is varied as shown in Table 1 below, otherwise the laminate is obtained in the same manner as in Example 10.

[0499] [Example 15]

[0500] A pressure-sensitive adhesive layer is formed instead of a heat-sensitive adhesive layer, and the roller temperature is set to 20°C to 30°C during the fabrication of the laminate. Otherwise, the laminate is obtained in the same manner as in Example 10.

[0501] (Formation of pressure-sensitive adhesive layer)

[0502] A pressure-sensitive adhesive composition is prepared by mixing the components in the manner shown below.

[0503] Composition of the pressure-sensitive adhesive composition

[0504] · 100 parts by weight of polyether urethane resin

[0505] · 5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)

[0506] · 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0507] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0508] Solvent (MEK) 310 parts by weight

[0509] Solvent (toluene) 310 parts by weight

[0510] The pressure-sensitive adhesive composition was applied to the substrate side of the hard coating film with a dried film thickness of 5 μm, and dried at 70°C for 1 minute to form a pressure-sensitive adhesive layer.

[0511] [Example 16]

[0512] As the bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (manufactured by Lintec Corporation, “D692”) was used, otherwise the laminate was obtained in the same manner as in Example 7.

[0513] [Example 17]

[0514] Laminates were obtained using the heat-sealing resin composition shown below, except otherwise described in Example 10.

[0515] <Composition of the heat-sealing resin composition>

[0516] · 100 parts by weight of modified polyolefin resin

[0517] · 5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)

[0518] · 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0519] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0520] Solvent (MEK) 310 parts by weight

[0521] Solvent (toluene) 310 parts by weight

[0522] [Example 18]

[0523] Laminates were obtained using the heat-sealing resin composition shown below, except otherwise described in Example 10.

[0524] <Composition of the heat-sealing resin composition>

[0525] • 100 parts by weight of polyester urethane resin (UR-8300, 30% solids, manufactured by Toyobo Co., Ltd.) • 1.5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.) • 1.5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0526] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0527] Solvent (MEK) 58 parts by weight

[0528] Solvent (toluene) 58 parts by weight

[0529] [Example 19]

[0530] Laminates were obtained using the heat-sealing resin composition shown below, except otherwise described in Example 10.

[0531] <Composition of the heat-sealing resin composition>

[0532] • 100 parts by weight of polyester urethane resin (UR-5537, 30% solids, manufactured by Toyobo Co., Ltd.) • 1.5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.) • 1.5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0533] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0534] Solvent (MEK) 58 parts by weight

[0535] Solvent (toluene) 58 parts by weight

[0536] [Example 20]

[0537] Laminates were obtained using the heat-sealing resin composition shown below, except otherwise described in Example 10.

[0538] <Composition of the heat-sealing resin composition>

[0539] • 100 parts by weight of amorphous polyester resin (Vylon 240, manufactured by Toyobo Co., Ltd.)

[0540] • 5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.) • 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0541] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0542] Solvent (MEK) 310 parts by weight

[0543] Solvent (toluene) 310 parts by weight

[0544] [Example 21]

[0545] Laminates were obtained using the heat-sealing resin composition shown below, except otherwise described in Example 10.

[0546] <Composition of the heat-sealing resin composition>

[0547] • 100 parts by weight of amorphous polyester resin (Vylon 600, manufactured by Toyobo Co., Ltd.)

[0548] · 5 parts by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)

[0549] · 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0550] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0551] Solvent (MEK) 310 parts by weight

[0552] Solvent (toluene) 310 parts by weight

[0553] [Example 22]

[0554] (1) Preparation of hard coating

[0555] The hard coating was prepared in the same manner as in Example 7.

[0556] (2) Formation of adhesive layer

[0557] A UV-curable resin composition is prepared by mixing the components as shown below.

[0558] <Composition of UV-curable resin composition>

[0559] • Carbamate acrylate (product name "UV-3310B", manufactured by Mitsubishi Chemical Corporation): 35 parts by weight

[0560] • Ethoxylated pentaerythritol tetraacrylate (product name "ATM-35E", manufactured by Shin-Nakamura Chemical Industry Co., Ltd.): 10 parts by weight

[0561] • Phenoxyethyl acrylate (product name "Viscoat#192", manufactured by Osaka Organic Chemical Industry Co., Ltd.): 5 parts by weight

[0562] • A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (product name "KAYARAD PET-30", manufactured by Nippon Kayaku Co., Ltd.): 50 parts by weight

[0563] • Photopolymerization initiator (1-hydroxycyclohexylphenyl ketone, product name "Omnirad 184", manufactured by IGM Resins BV): 5 parts by weight

[0564] Methyl isobutyl ketone: 10 parts by weight

[0565] Next, the UV-curable resin composition is applied to the substrate layer side of the hard coating film with a cured film thickness of 5 μm, and dried at 70°C for 1 minute to form an adhesive layer, thereby obtaining a hard coating film with an adhesive layer.

[0566] (3) Fabrication of laminates

[0567] Using a hand roller, the adhesive layer side of the aforementioned hard coating film with an adhesive layer is bonded to a chemically strengthened glass substrate with a thickness of 70 μm. Then, irradiation at a dose of 400 mJ / cm² is applied from the hard coating side. 2 Irradiation with ultraviolet light causes the adhesive layer to cure, resulting in a laminate.

[0568] [Example 23]

[0569] (1) Preparation of hard coating

[0570] The hard coating was prepared in the same manner as in Example 7.

[0571] (2) Formation of adhesive layer

[0572] A thermosetting resin composition is prepared by mixing the components in the manner shown below.

[0573] <Composition of thermosetting resin composition>

[0574] ·Special phenolic varnish type epoxy resin (JER157S65, manufactured by Mitsubishi Chemical) 25 parts by weight

[0575] • 75 parts by weight of bis(A) / bis(F) blended epoxy resin (JER4250, manufactured by Mitsubishi Chemical)

[0576] ·6.5 parts by weight of 2-ethyl-4-methylimidazolium (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0577] · 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0578] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0579] Solvent (MEK) 600 parts by weight

[0580] Next, the above-mentioned thermosetting resin composition is applied to the substrate layer side of the above-mentioned hard coating film with a cured film thickness of 5 μm, and dried at 70°C for 1 minute to form an adhesive layer, thereby obtaining a hard coating film with an adhesive layer.

[0581] (3) Fabrication of laminates

[0582] Using a hand roller, the adhesive layer side of the hard coating film with the adhesive layer is bonded to a chemically strengthened glass substrate with a thickness of 70 μm. Then, the adhesive layer is cured by heating at 130°C for 60 minutes to obtain a laminate.

[0583] [Example 24]

[0584] Laminates were obtained using the thermosetting resin composition shown below, except otherwise described in Example 23.

[0585] <Composition of thermosetting resin composition>

[0586] · 50 parts by weight of special phenolic varnish-type epoxy resin (JER157S65, manufactured by Mitsubishi Chemical)

[0587] • 50 parts by weight of type A epoxy resin (JER1256, manufactured by Mitsubishi Chemical)

[0588] ·6.5 parts by weight of 2-ethyl-4-methylimidazolium (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0589] · 5 parts by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0590] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0591] Solvent (MEK) 600 parts by weight

[0592] [Example 25]

[0593] (1) Preparation of hard coating

[0594] As the substrate layer, a 60 μm thick TAC film (manufactured by Fujifilm, “TG60UL”) was used. The thickness of the hard coating was varied as shown in Table 1 below. Otherwise, the hard coating was prepared in the same manner as in Example 10.

[0595] (2) Formation of the heat-sensitive adhesive layer

[0596] A hard coating with a heat-sensitive adhesive layer was obtained in the same manner as in Example 10.

[0597] (3) Fabrication of laminates

[0598] The laminate was obtained in the same manner as in Example 10.

[0599] [Example 26]

[0600] (1) Preparation of hard coating

[0601] As the substrate layer, a PET film with a thickness of 50 μm (manufactured by Toyobo Co., Ltd., “A4360 (current model)” (“A4300 (old model)”)) was used. The thickness of the hard coating was changed as shown in Table 1 below. Otherwise, the hard coating film was made in the same way as in Example 10.

[0602] (2) Formation of the heat-sensitive adhesive layer

[0603] A hard coating with a heat-sensitive adhesive layer was obtained in the same manner as in Example 10.

[0604] (3) Fabrication of laminates

[0605] The laminate was obtained in the same manner as in Example 10.

[0606] [Example 27]

[0607] As the substrate layer, a 50 μm thick PEN film (manufactured by Teijin Corporation) was used, and the laminate was fabricated in the same manner as in Example 26.

[0608] [Examples 28-30 and Comparative Example 6]

[0609] The thickness of the glass substrate was varied as shown in Table 3 below, otherwise the laminate was obtained in the same manner as in Example 10.

[0610] [Rating 1]

[0611] (1) Pencil hardness

[0612] First, for the glass substrate side of the laminates in Examples 1-30 and Comparative Examples 2-6, and for Comparative Example 1 on the glass substrate, a test laminate was prepared by bonding a 100 μm thick PET film (Toyobo Co., Ltd., "A4160 (current model)" ("A4100 (old model)") with a 50 μm thick optically transparent adhesive film (OCA) (manufactured by 3M Co., Ltd., with a composite elastic modulus of 9.6 MPa) to the glass substrate. For the laminates in Examples 1-30 and Comparative Examples 2-6, the pencil hardness of the surface of the hard coating side of the test laminate was measured. Additionally, for the glass substrate of Comparative Example 1, the pencil hardness of the surface of the test laminate on the glass substrate side was measured. In this case, the pencil hardness was measured according to JIS K5600-5-4 (1999). In addition, a pencil hardness tester (product name "Pencil Scratch Coating Hardness Tester (Electric)", manufactured by Toyo Seiki Co., Ltd.) was used, with the test conditions set as follows: angle 45°, load 1kg, speed 0.5mm / second to 1mm / second and temperature 23±2℃.

[0613] For Examples 1-9 and Comparative Examples 1-4, the pencil hardness was evaluated according to the following criteria.

[0614] 2A: The pencil hardness is 5H or higher.

[0615] A: The pencil's hardness is 4H.

[0616] B: The pencil's hardness is 3H.

[0617] C: The pencil's hardness is H.

[0618] D: The pencil's hardness is less than H.

[0619] For Examples 10-30 and Comparative Examples 5-6, the pencil hardness was evaluated according to the following criteria.

[0620] 2A: The pencil hardness is 5H or higher.

[0621] A: The pencil's hardness is 4H.

[0622] B: The pencil's hardness is 3H.

[0623] C: The pencil hardness is less than 3H.

[0624] (2) Impact test (pen drop test)

[0625] For the laminates of Examples 1-30 and Comparative Examples 2-6, and the glass substrate of Comparative Example 1, a pen drop test was conducted as an impact test. First, for the glass substrate side of the laminates of Examples 1-30 and Comparative Examples 2-6, and for the glass substrate of Comparative Example 1, a test laminate was prepared by bonding a 50 μm thick optically clear adhesive film (OCA) (manufactured by 3M Co., Ltd. "8146-2", composite elastic modulus 9.6 MPa) with a 100 μm thick PET film (manufactured by Toyobo Co., Ltd. "A4160 (current model)" ("A4100 (old model)"), composite elastic modulus 6.9 GPa). The test laminate was placed on a metal plate with the PET film side of the test laminate in contact with a 30 mm thick metal plate. Then, a pen was dropped onto the test laminate from the test height with its tip pointing downwards. The pen used is a Zebra Blen 0.5BAS88-BK (weight 12g, nib) Tables 1-3 show the maximum test heights at which no cracks appeared in the glass substrate. It should be noted that the higher the value, the higher the impact resistance.

[0626] (3) Puncture test

[0627] The above-described puncture test was performed on the laminate of Example 10 and the glass substrate of Comparative Example 1 to determine the puncture breaking force. It should be noted that a higher value indicates higher impact resistance.

[0628] (4) Dynamic bending test

[0629] The dynamic bending test described above was performed on the laminates of Examples 1-30 and Comparative Examples 2-6, as well as the glass substrate of Comparative Example 1, to evaluate their bending resistance. In this test, the distance d between the two opposing short sides of the laminate or glass substrate was 3 mm, 4 mm, 6 mm, 8 mm, or 10 mm. Furthermore, the laminate was bent 200,000 times with the glass substrate side as the outer side and the hard coating side as the inner side. The results of the dynamic bending test were evaluated according to the following criteria.

[0630] 4A: Even with a spacing d of 3 mm, the laminate or glass substrate does not exhibit cracks, breaks, or peeling.

[0631] 3A: Even with a spacing d of 4 mm, the laminate or glass substrate does not exhibit cracks, breaks, or peeling.

[0632] 2A: Even with a spacing d of 6 mm, the laminate or glass substrate does not exhibit cracks, breaks, or peeling.

[0633] A: Even with a spacing d of 8mm, the laminate or glass substrate did not show any cracks, breaks, or peeling.

[0634] B: When the interval d is 10mm, the laminate or glass substrate has no cracks, breaks, or peeling.

[0635] C: When the interval d is 10 mm, cracks, fractures and peeling occur in the laminate or glass substrate.

[0636] (5) Composite elastic modulus

[0637] For the laminates of Examples 1-30 and Comparative Examples 2-6, the composite elastic modulus of the substrate layer and the bonding layer was measured by the above-described method for measuring composite elastic modulus.

[0638] (6) Glass transition temperature (Tg)

[0639] For the laminates of Examples 1 to 30 and Comparative Examples 2 to 6, the glass transition temperature of the bonding layer was determined by the glass transition temperature determination method described above.

[0640] [Table 1]

[0641]

[0642] [Table 2]

[0643]

[0644] [Table 3]

[0645]

[0646] Tables 1-3 confirm that when the thickness ratio (A+B) / C is within the specified range, the impact resistance and bending resistance are good, resulting in high surface hardness and good damage resistance.

[0647] [Example 31]

[0648] On the glass substrate side of the laminate of Example 10, a second bonding layer (optically transparent adhesive film (OCA), energy storage modulus 0.10 MPa) with a thickness of 100 μm is bonded using a hand roller to obtain the laminate.

[0649] [Example 32]

[0650] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M "8146-4", energy storage modulus 0.23 MPa) was used, and the laminate was fabricated in the same manner as in Example 31.

[0651] [Example 33]

[0652] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M Corporation "8146-2", energy storage modulus 0.23 MPa) was used, and the laminate was fabricated in the same manner as in Example 31.

[0653] [Example 34]

[0654] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 50 μm (storage modulus of 0.10 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0655] [Example 35]

[0656] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 55 μm (storage modulus of 0.12 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0657] [Example 36]

[0658] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 30 μm (storage modulus of 0.12 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0659] [Example 37]

[0660] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (storage modulus of 0.32 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0661] [Example 38]

[0662] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (storage modulus of 0.15 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0663] [Example 39]

[0664] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (Lintec "F619", energy storage modulus 0.19 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0665] [Example 40]

[0666] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (Lintec "N632", energy storage modulus 0.20 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0667] [Example 41]

[0668] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (storage modulus of 0.57 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0669] [Example 42]

[0670] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (storage modulus of 1.17 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0671] [Example 43]

[0672] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (Lintec "D692, storage modulus 2.33 MPa") was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0673] [Example 44]

[0674] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (storage modulus 2.22 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0675] [Example 45]

[0676] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 15 μm (Lintec "D692, storage modulus 2.14 MPa") was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0677] [Example 46]

[0678] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 15 μm (storage modulus of 0.12 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0679] [Example 47]

[0680] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (storage modulus of 0.91 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0681] [Example 48]

[0682] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 10 μm (storage modulus 2.22 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0683] [Example 49]

[0684] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (storage modulus of 1.95 MPa) was used to fabricate the laminate in the same manner as in Example 31.

[0685] [Comparative Example 7]

[0686] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (storage modulus 2.22 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0687] [Comparative Example 8]

[0688] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 15 μm (storage modulus of 12.74 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 31.

[0689] [Example 50]

[0690] On the glass substrate side of the laminate of Example 18, an optically transparent adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M Company "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0691] [Example 51]

[0692] On the glass substrate side of the laminate of Example 19, an optically transparent adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0693] [Example 52]

[0694] On the glass substrate side of the laminate of Example 20, an optically transparent adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M Company "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0695] [Example 53]

[0696] On the glass substrate side of the laminate of Example 21, an optically clear adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M Company "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0697] [Example 54]

[0698] On the glass substrate side of the laminate of Example 22, an optically transparent adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0699] [Example 55]

[0700] On the glass substrate side of the laminate of Example 23, an optically clear adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M Company "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0701] [Example 56]

[0702] On the glass substrate side of the laminate of Example 28, an optically clear adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0703] [Example 57]

[0704] The thickness of the hard coating was 10 μm, and the laminate was fabricated in the same manner as in Example 26. On the glass substrate side of the laminate, an optically clear adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M "8146-2", storage modulus 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0705] [Example 58]

[0706] On the glass substrate side of the laminate of Example 26, an optically clear adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M Company "8146-2", storage modulus of 0.23 MPa) was bonded using a hand roller to obtain the laminate.

[0707] [Example 59]

[0708] The thickness of the glass substrate is 50 μm, and the laminate is fabricated in the same manner as in Example 57.

[0709] [Example 60]

[0710] As the bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (composite elastic modulus 0.0096 GPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 33.

[0711] [Example 61]

[0712] As the bonding layer, an optically transparent adhesive film (OCA) with a thickness of 50 μm (composite elastic modulus of 0.0096 GPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 59.

[0713] [Example 62]

[0714] The thickness of the glass substrate is 50 μm, and an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M Corporation "8146-4", storage modulus 0.23 MPa) is used as the second bonding layer. Otherwise, the laminate is made in the same manner as in Example 33.

[0715] [Example 63]

[0716] As the substrate layer, a 50 μm thick PEN film (manufactured by Teijin Corporation) was used, and the laminate was fabricated in the same manner as in Example 62.

[0717] [Example 64]

[0718] As the substrate layer, a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., “A4360”) was used, and the laminate was otherwise made in the same manner as in Example 62.

[0719] [Example 65]

[0720] The thickness of the glass substrate is 30 μm, and an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M Corporation "8146-4", storage modulus 0.23 MPa) is used as the second bonding layer. Otherwise, the laminate is fabricated in the same manner as in Example 33.

[0721] [Example 66]

[0722] As the substrate layer, a 50 μm thick PEN film (manufactured by Teijin Corporation) was used, and the laminate was otherwise fabricated in the same manner as in Example 65.

[0723] [Example 67]

[0724] As the substrate layer, a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., “A4360”) was used, and the laminate was otherwise made in the same manner as in Example 65.

[0725] [Example 68]

[0726] As the bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (composite elastic modulus 0.0096 GPa) is used, and as the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 25 μm (composite elastic modulus 0.23 MPa) is used. Otherwise, the laminate is fabricated in the same manner as in Example 67.

[0727] [Example 69]

[0728] The thickness of the substrate layer is 80 μm, and the thickness of the glass substrate is 50 μm. Otherwise, the laminate is fabricated in the same manner as in Example 33.

[0729] [Example 70]

[0730] As the substrate layer, a PET film (Toresha "U403") with a thickness of 23 μm was used, and the thickness of the glass substrate was 30 μm. Otherwise, the laminate was fabricated in the same manner as in Example 59.

[0731] [Comparative Example 9]

[0732] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M "8146-4", energy storage modulus 0.23 MPa) was used, and the laminate was otherwise fabricated in the same manner as in Example 68.

[0733] [Comparative Example 10]

[0734] A 100μm thick optically clear adhesive film (OCA) (manufactured by 3M "8146-4", storage modulus 0.23MPa) is laminated onto one side of a chemically strengthened glass substrate with a thickness of 70μm using a hand roller to obtain a laminate.

[0735] [Comparative Example 11]

[0736] The thickness of the glass substrate was 50 μm, and the laminate was fabricated in the same manner as in Comparative Example 10.

[0737] [Comparative Example 12]

[0738] The thickness of the glass substrate was 30 μm, and the laminate was fabricated in the same manner as in Comparative Example 10.

[0739] [Example 71]

[0740] Similar to Example 1, a substrate layer composed of a polyimide resin film with a thickness of 80 μm was prepared. A heat-sensitive adhesive layer was formed on one side of the substrate layer, similar to Example 10, resulting in a substrate layer with a heat-sensitive adhesive layer. The substrate layer with the heat-sensitive adhesive layer was positioned such that the side with the heat-sensitive adhesive layer was bonded to a chemically strengthened glass substrate with a thickness of 70 μm. A 2 mm thick glass support substrate was placed on the opposite side of the glass substrate from the substrate layer with the heat-sensitive adhesive layer. The substrate layer with the heat-sensitive adhesive layer and the glass substrate were bonded together using a roller laminator (manufactured by ACCO BRANDS JAPAN, trade name: Benchtop Roller Laminator B35A3) while heated, resulting in a laminate. The roller temperature was set to 140°C–149°C, and the feed speed was set to 0.3 m / min. The laminate was then aged at 70°C for 2 days. Next, an optically clear adhesive film (OCA) with a thickness of 50 μm (manufactured by 3M, "8146-2", storage modulus 0.23 MPa) is bonded to the glass substrate side of the laminate using a hand roller to obtain the laminate.

[0741] [Example 72]

[0742] The thickness of the substrate layer is 50 μm, and the laminate is fabricated in the same manner as in Example 71.

[0743] [Example 73]

[0744] The thickness of the substrate layer is 50 μm, and the thickness of the glass substrate is 50 μm. Otherwise, the laminate is fabricated in the same manner as in Example 71.

[0745] [Example 74]

[0746] The thickness of the substrate layer is 50 μm, and the thickness of the glass substrate is 30 μm. Otherwise, the laminate is fabricated in the same manner as in Example 71.

[0747] [Example 75]

[0748] The thickness of the substrate layer is 30 μm, and the laminate is fabricated in the same manner as in Example 71.

[0749] [Example 76]

[0750] As the substrate layer, a 75 μm thick PET film (manufactured by Toyobo Co., Ltd., “A4360”) was used, and the laminate was otherwise made in the same manner as in Example 71.

[0751] [Example 77]

[0752] As the substrate layer, a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., “A4360”) was used, and the laminate was otherwise made in the same manner as in Example 71.

[0753] [Example 78]

[0754] The thickness of the glass substrate is 50 μm, and the laminate is fabricated in the same manner as in Example 77.

[0755] [Example 79]

[0756] The thickness of the glass substrate is 30 μm, and the laminate is fabricated in the same manner as in Example 77.

[0757] [Example 80]

[0758] As the substrate layer, a 23 μm thick PET film (manufactured by Toray Industries, Inc., “U403”) was used, and the laminate was otherwise fabricated in the same manner as in Example 71.

[0759] [Example 81]

[0760] As the substrate layer, a 60 μm thick TAC film (manufactured by Fujifilm "TG60UL") was used, and the laminate was otherwise fabricated in the same manner as in Example 71.

[0761] [Example 82]

[0762] As the substrate layer, a 50 μm thick PEN film (manufactured by Teijin Corporation) was used, and the laminate was fabricated in the same manner as in Example 71.

[0763] [Example 83]

[0764] The thickness of the glass substrate is 50 μm, and an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M Corporation "8146-4", storage modulus 0.23 MPa) is used as the second bonding layer. Otherwise, the laminate is made in the same manner as in Example 71.

[0765] [Example 84]

[0766] As the substrate layer, a 50 μm thick PEN film (manufactured by Teijin Corporation) was used, and the laminate was fabricated in the same manner as in Example 83.

[0767] [Example 85]

[0768] As the substrate layer, a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., “A4360”) was used, and the laminate was otherwise made in the same manner as in Example 83.

[0769] [Example 86]

[0770] The thickness of the glass substrate is 30 μm, and an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M Corporation "8146-4", storage modulus 0.23 MPa) is used as the second bonding layer. Otherwise, the laminate is made in the same manner as in Example 71.

[0771] [Example 87]

[0772] As the substrate layer, a 50 μm thick PEN film (manufactured by Teijin Corporation) was used, and the laminate was fabricated in the same manner as in Example 86.

[0773] [Example 88]

[0774] As the substrate layer, a 50 μm thick PET film (manufactured by Toyobo Co., Ltd., “A4360”) was used, and the laminate was otherwise made in the same manner as in Example 86.

[0775] [Example 89]

[0776] An optically transparent adhesive film (OCA) with a thickness of 25 μm (composite elastic modulus 0.0096 GPa) was used as the bonding layer, and an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M Corporation "8146-4", storage modulus 0.23 MPa) was used as the second bonding layer. Otherwise, the laminate was obtained in the same manner as in Example 88.

[0777] [Example 90]

[0778] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 15 μm (storage modulus 2.14 MPa) was used, otherwise the laminate was obtained in the same manner as in Example 72.

[0779] [Example 91]

[0780] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (storage modulus of 0.91 MPa) was used, otherwise the laminate was obtained in the same manner as in Example 72.

[0781] [Example 92]

[0782] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 10 μm (storage modulus 2.22 MPa) was used, otherwise the laminate was obtained in the same manner as in Example 72.

[0783] [Example 93]

[0784] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (storage modulus of 1.95 MPa) was used, otherwise the laminate was obtained in the same manner as in Example 72.

[0785] [Example 94]

[0786] As the substrate layer, a 23 μm thick PET film (manufactured by Toray Industries, Inc., “U403”) was used, and the thickness of the glass substrate was 30 μm. Otherwise, the laminate was fabricated in the same manner as in Example 71.

[0787] [Comparative Example 13]

[0788] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (storage modulus 2.22 MPa) was used, otherwise the laminate was obtained in the same manner as in Example 72.

[0789] [Comparative Example 14]

[0790] As the second bonding layer, an optically transparent adhesive film (OCA) with a thickness of 100 μm (manufactured by 3M "8146-4", energy storage modulus 0.23 MPa) was used, and otherwise the laminate was obtained in the same manner as in Example 94.

[0791] [Rating 2]

[0792] (1) Impact test (pen drop test)

[0793] For the laminate, a pen drop test was conducted as an impact test. First, a 100μm thick PET film (Toyobo Corporation "A4160" composite elastic modulus 6.9GPa) was bonded to the second bonding layer side of the laminate to create a test laminate. The test laminate was then placed on a 30mm thick metal plate with the PET film side facing it. Next, a pen was dropped onto the test laminate from the test height, tip down, with the center of the laminate. The pen used was a Zebra Blen0.5BAS88-BK (weight 12g, nib...). Tables 4-6 show the maximum test heights at which no cracks appeared in the glass substrate. It should be noted that higher values ​​indicate higher impact resistance.

[0794] (2) Dynamic bending test

[0795] First, a test laminate was prepared by bonding a 38μm thick PET film (Toyobo Co., Ltd. "A4360") to the second bonding layer side of the laminate using a hand roller. A dynamic bending test was then performed, similar to Evaluation 1 above, to evaluate its bending resistance. In this test, the test laminate was bent 200,000 times with the second bonding layer side facing outwards and the hard coating or substrate layer side facing inwards.

[0796] (3) Composite elastic modulus of glass substrate, bonding layer, substrate layer and hard coating

[0797] The composite elastic modulus of the glass substrate, bonding layer, substrate layer and hard coating was determined using the above-mentioned method for determining composite elastic modulus.

[0798] (4) Storage modulus of the second bonding layer at 20°C

[0799] The energy storage modulus of the second bonding layer at 20°C was determined using the aforementioned method for determining the energy storage modulus of the second bonding layer.

[0800] Figure 10 The graph shown above illustrates the relationship between the intermediate value of equation (1) and the test height of the pen-dropping experiment. Additionally, Figure 11 The graph shown in the figure represents the relationship between the intermediate value of the above equation (2) and the test height of the pen drop test.

[0801] (5) Glass transition temperatures (Tg) of the bonding layer and the second bonding layer

[0802] The glass transition temperatures of the bonding layer and the second bonding layer were determined using the method described above.

[0803] [Table 4]

[0804]

[0805] [Table 5]

[0806]

[0807] [Table 6]

[0808]

[0809] From Tables 4-5 and Figure 10 It can be confirmed that, under the condition of satisfying the above equation (1), good flexural resistance can be obtained without compromising impact resistance. Furthermore, from Table 6 and... Figure 11 It can be confirmed that, under the condition of satisfying the above formula (2), good bending resistance can be obtained without compromising impact resistance.

[0810] [Example 95]

[0811] A 50 μm thick PET film (manufactured by Toyobo Co., Ltd., "A4160") was prepared. The hard coating curable resin composition used in Example 1 was applied to the PET film using a bar coater to complete the coating. The coating was then dried at 100°C for 3 minutes and cured by irradiation with 200 mJ ultraviolet light to form a 10 μm thick hard coating. Next, a pressure-sensitive adhesive layer was formed on the side of the PET film opposite to the hard coating, in the same manner as in Example 15. This yielded a laminated film. Then, the bonding layer side of the laminated film was bonded to a 30 μm thick chemically strengthened glass substrate to obtain a laminate.

[0812] [Example 96]

[0813] As the bonding layer, an optically transparent adhesive film (OCA) with a thickness of 5 μm (Lintec "D692", composite elastic modulus 19 MPa) was used to fabricate the laminate in the same manner as in Example 95.

[0814] [Example 97]

[0815] As the bonding layer, an optically transparent adhesive film (acrylic adhesive sheet, OCA) with a thickness of 5 μm (PANACLEAN PD-S1 manufactured by PANAC Corporation, with a composite elastic modulus of 13.7 MPa) was used to fabricate the laminate in the same manner as in Example 95.

[0816] [Example 98]

[0817] A hard coating is formed on the PET film in the same manner as in Example 95.

[0818] Next, the heat-sealing resin composition used in Example 17 was applied to the side of the PET film opposite to the hard coating layer, with a dried film thickness of 5 μm, and dried at 70°C for 1 minute to form a heat-sensitive adhesive layer, thus obtaining a laminated film.

[0819] Next, the laminated film was configured such that the heat-sensitive adhesive layer side was bonded to a 30μm thick chemically strengthened glass substrate. A 2mm thick glass support substrate was placed on the opposite side of the glass substrate. Using a roller laminator (manufactured by ACCO BRANDS JAPAN, trade name: Benchtop Roller Laminator B35A3), the laminated film and glass substrate were bonded while heated to obtain the laminate. At this time, the roller temperature was set to 140℃~149℃, and the feed speed was set to 0.3m / min. The laminate was then aged at 70℃ for 2 days.

[0820] [Example 99]

[0821] The laminate was prepared in the same manner as in Example 98, except that the heat-sealing resin composition used in Example 10 was used.

[0822] [Example 100]

[0823] The laminate was prepared in the same manner as in Example 98, except that the heat-sealing resin composition used in Example 18 was used.

[0824] [Example 101]

[0825] The laminate was prepared in the same manner as in Example 98, except that the heat-sealing resin composition used in Example 19 was used.

[0826] [Example 102]

[0827] The laminate was prepared in the same manner as in Example 98, except that the heat-sealing resin composition used in Example 21 was used.

[0828] [Example 103]

[0829] The laminate was prepared in the same manner as in Example 98, except that the heat-sealing resin composition used in Example 20 was used.

[0830] [Example 104]

[0831] Similar to Example 95, a hard coating is formed on the PET film.

[0832] Next, the UV-curable resin composition used in Example 22 was applied to the side of the PET film opposite to the hard coating, with a cured film thickness of 5 μm, and dried at 70°C for 1 minute to form an adhesive layer, thus obtaining a laminated film.

[0833] Using a hand roller, the adhesive layer side of the laminated film is bonded to a 30 μm thick chemically strengthened glass substrate. Then, from the hard coating side, an irradiation dose of 400 mJ / cm² is applied. 2 Irradiation with ultraviolet light causes the adhesive layer to cure, resulting in a laminate.

[0834] [Example 105]

[0835] Laminates were prepared in the same manner as in Example 98, except that the following heat-sealing resin composition was used.

[0836] <Composition of the heat-sealing resin composition>

[0837] • 100 parts by weight of amorphous polyester resin (TP-235S20TM, 20% solids, manufactured by Mitsubishi Chemical Corporation)

[0838] • 1 part by weight of hexamethylene diisocyanate (CORONATE 2203, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)

[0839] • 1 part by weight of silane coupling agent (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)

[0840] Fluorine-based leveling agent (F568, manufactured by DIC) 0.2 parts by weight (conversion based on solid content)

[0841] Solvent (MEK) 34 parts by weight

[0842] Solvent (toluene) 10 parts by weight

[0843] [Example 106]

[0844] Similar to Example 95, a hard coating is formed on the PET film.

[0845] Next, the thermosetting resin composition used in Example 23 was applied to the side of the PET film opposite to the hard coating layer, with a cured film thickness of 5 μm. The film was dried at 70°C for 1 minute to form an adhesive layer, thus obtaining a hard coating film with an adhesive layer.

[0846] Using a hand roller, the adhesive layer side of the hard coating film with the adhesive layer is bonded to a chemically strengthened glass substrate with a thickness of 30 μm. Then, the adhesive layer is cured by heating at 130°C for 60 minutes to obtain a laminate.

[0847] [Rating 3]

[0848] (1) Pencil hardness

[0849] The pencil hardness of the hard-coated side of the laminate was measured in the same manner as in Evaluation 1 above. The pencil hardness was evaluated according to the following criteria.

[0850] 2A: The pencil hardness is 2H or higher.

[0851] A: The pencil's hardness is H.

[0852] B: The pencil's hardness is F.

[0853] C: The pencil hardness is below HB.

[0854] (2) Impact test (pen drop test)

[0855] Similar to Evaluation 1 above, a pen drop test was conducted on the laminate as an impact test. Table 7 shows the maximum test height at which the glass substrate did not crack. It should be noted that a higher value indicates higher impact resistance.

[0856] (3) Dynamic bending test

[0857] The dynamic bending test was conducted in the same manner as evaluation 1 above to evaluate the bending resistance. The dynamic bending test was conducted under three conditions: (a) temperature 23°C, (b) temperature 60°C and humidity 90%RH, and (c) temperature -20°C.

[0858] [Table 7]

[0859]

[0860] The preferred range of the glass transition temperature of the bonding layer is -40°C to 150°C. From the perspective of dynamic bending performance under high temperature and high humidity and low temperature environments, it is suggested that the glass transition temperature of the bonding layer is more preferably -40°C to 25°C and 50°C to 150°C.

[0861] Symbol Explanation

[0862] 1…laminated body

[0863] 2…glass substrate

[0864] 3… Bonding layer

[0865] 4… Hard coating

[0866] 5…Substrate layer

[0867] 6… Hard coating

[0868] 7…Anti-reflective layer

[0869] 10…Second bonding layer

[0870] 11…protective film

[0871] 12…Resin substrate

[0872] 13… Adhesive layer

[0873] 14…Second hard coating

[0874] 30… Display device

[0875] 31… Display Panel

Claims

1. A laminate comprising, sequentially having a hard coating layer, a substrate layer, a bonding layer, a glass substrate, and a second bonding layer, wherein, The bonding layer is a layer that bonds the glass substrate to the substrate layer. The second bonding layer is a layer that bonds the laminate to other components. The thickness of the glass substrate is between 10 μm and 100 μm. The laminate satisfies the following equation (1), 0.001≤{(E1×D1 2 +E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (1) In the above formula (1), E1 represents the composite elastic modulus of the hard coating layer in GPa, D1 represents the thickness of the hard coating layer in mm, E2 represents the composite elastic modulus of the substrate layer in GPa, D2 represents the thickness of the substrate layer in mm, E3 represents the composite elastic modulus of the bonding layer in GPa, D3 represents the thickness of the bonding layer in mm, E4 represents the composite elastic modulus of the glass substrate in GPa, D4 represents the thickness of the glass substrate in mm, E5 represents the energy storage modulus of the second bonding layer in GPa, and D5 represents the thickness of the second bonding layer in mm.

2. A laminate, comprising sequentially having a substrate layer, a bonding layer, a glass substrate, and a second bonding layer, wherein, The bonding layer is a layer that bonds the glass substrate to the substrate layer. The second bonding layer is a layer that bonds the laminate to other components. The thickness of the glass substrate is between 10 μm and 100 μm. The laminate satisfies the following equation (2), 0.001≤{(E2×D2 2 +E3×D3 2 )×E4×D4 2 ×E5×1000} / D5≤3.0 (2) In the above formula (2), E2 represents the composite elastic modulus of the substrate layer in GPa, D2 represents the thickness of the substrate layer in mm, E3 represents the composite elastic modulus of the bonding layer in GPa, D3 represents the thickness of the bonding layer in mm, E4 represents the composite elastic modulus of the glass substrate in GPa, D4 represents the thickness of the glass substrate in mm, E5 represents the energy storage modulus of the second bonding layer in GPa, and D5 represents the thickness of the second bonding layer in mm.

3. The laminate as claimed in claim 1 or claim 2, wherein, The glass transition temperature of the second bonding layer is above -50°C and below 30°C.

4. The laminate as claimed in claim 1 or claim 2, wherein, The second bonding layer contains an optically transparent adhesive.

5. The laminate as claimed in claim 1 or claim 2, wherein, The composite elastic modulus of the bonding layer is above 1 MPa and below 6000 MPa.

6. The laminate as claimed in claim 1 or claim 2, wherein, The glass transition temperature of the bonding layer is above -40°C and below 150°C.

7. The laminate as claimed in claim 1 or claim 2, wherein, The composite elastic modulus of the substrate layer is above 5.7 GPa.

8. The laminate as claimed in claim 1 or claim 2, wherein, The glass substrate is chemically strengthened glass.

9. The laminate as claimed in claim 1 or claim 2, wherein, The bonding layer is a pressure-sensitive adhesive layer, a heat-sensitive adhesive layer, or a cured product containing a curable adhesive composition.

10. The laminate as claimed in claim 1 or claim 2, wherein, The bonding layer contains at least one selected from the group consisting of polyester resin, polyolefin resin and urethane resin.

11. The laminate as claimed in claim 1, wherein, An anti-reflective layer is provided on the side of the hard coating opposite to the substrate layer.

12. The laminate as claimed in claim 1, wherein, When the laminate is repeatedly bent 180° 200,000 times with the glass substrate side of the laminate as the outer side, the hard coating side of the laminate as the inner side, and the opposing edges of the laminate spaced 10 mm apart, no cracks, breaks or peeling occur.

13. The laminate as claimed in claim 1, wherein, A protective film is provided on the side of the hard coating opposite to the substrate layer.

14. A display device comprising: Display panel; and The laminate of any one of claims 1 to 13 disposed on the observer side of the display panel. The laminate is configured such that the surface of the glass substrate is adjacent to the display panel.

15. The display device as claimed in claim 14, wherein it is a foldable display.

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