JP7830873B2 - Glass laminates, display devices, electronic devices, and resin layers - Google Patents

Description

This disclosure relates to a glass laminate, a display device and electronic device using the same, and a resin layer used therein.

Traditionally, display devices have been fitted with glass or resin cover components to protect them. These cover components protect the display device from impacts and scratches, requiring strength, impact resistance, and scratch resistance. Glass cover components have high surface hardness, are scratch-resistant, and offer high transparency, while resin cover components are lightweight and less prone to breakage. Generally, thicker cover components provide better protection against impacts. The material and thickness of the cover component are selected appropriately based on factors such as weight, cost, and the size of the display device.

In recent years, there has been a surge in the development of flexible displays, including foldable displays, rollable displays, and bendable displays. Among these, the development of foldable displays, or display devices that can be folded, is particularly advanced.

In bendable display devices, the cover component also needs to bend to follow the movement of the display device; therefore, bendable cover components are used. In the case of resin cover components, polyimide and polyamide-imide films that have been made colorless and transparent through improvements in their chemical structure have been developed (see, for example, Patent Document 1). Furthermore, in the case of glass cover components, research is underway on cover components that can be bent by making the glass thinner, such as ultra-thin glass (UTG) (see, for example, Patent Document 2). Among glass types, chemically strengthened glass has particularly high bending resistance. By imbuing the glass surface with expanding stress, it prevents minute scratches on the glass surface from becoming larger during bending, thus making the glass less prone to breakage.

Glass has a higher elastic modulus than resin, meaning that for the same thickness, it offers superior protection for display devices. Furthermore, glass is highly optically transparent, allowing for the manufacture of display devices with better visibility. However, as glass becomes thinner, it becomes more brittle, dramatically reducing its impact resistance. If the glass cover breaks due to external impact, not only is its protective function for the display device diminished, but the resulting fragments and sharp edges could injure the user's fingertips or other body parts.

Therefore, laminating a resin layer onto a glass substrate has been proposed. For example, Patent Document 3 discloses a front panel for a display device with a shatterproof layer formed on a glass substrate.

Japanese Patent Publication No. 2019-137864 Japanese Patent Publication No. 2018-188335 Japanese Patent Publication No. 2016-70972

In a display device comprising a glass laminate having a glass substrate and a resin layer, positioning the resin layer on the observer side of the glass substrate allows for the suppression of glass breakage due to impact, thereby improving impact resistance. However, as described in the examples and comparative examples below, laminating a resin layer onto a glass substrate tends to result in poorer flexibility compared to the glass substrate alone. Thus, flexibility and impact resistance of a glass laminate are considered to be conflicting properties. Therefore, a glass laminate that can achieve both flexibility and impact resistance is required.

This disclosure is made in view of the above circumstances, and its primary purpose is to provide a glass laminate with good bending resistance and impact resistance, as well as improved safety.

To solve the above problems, the inventors of this disclosure conducted diligent research and found that by placing a resin layer on the main surface side of a thin glass substrate and covering the sides of the glass substrate with a resin layer, it is possible to achieve both good flexibility and impact resistance. This disclosure is based on these findings.

One embodiment of the present disclosure provides a glass laminate comprising a glass substrate, a first resin layer, and a second resin layer, wherein the glass substrate has a first surface, a second surface opposite to the first surface, and a third surface different from the first and second surfaces, the thickness of the glass substrate is 100 μm or less, the first resin layer is located on the side of the first surface and is transparent, and the second resin layer covers the third surface.

In the glass laminate described herein, the first resin layer and the second resin layer may contain the same material and be integrally formed.

Furthermore, in the glass laminate according to this disclosure, it is preferable that the following equation (Formula 1) is satisfied when the thickness of the first resin layer is T1 and the thickness of the second resin layer is T2.
(Formula 1) 0.01≦T1/T2≦5.0

Furthermore, in the glass laminate according to this disclosure, it is preferable that the ratio of the thickness of the second resin layer in the thickness direction of the glass substrate to the thickness of the glass substrate is 0.5 or more.

Furthermore, in the glass laminate according to this disclosure, it is preferable that the first resin layer contains at least one selected from the group consisting of polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin. It is also preferable that the second resin layer contains at least one selected from the group consisting of polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin, or contains a cured product of a resin composition containing a polymerizable compound.

Furthermore, the glass laminate in this disclosure may have a primer layer between the glass substrate and the first resin layer.

Furthermore, the glass laminate in this disclosure may have a functional layer on the side of the first resin layer opposite to the glass substrate. In this case, the second resin layer and the functional layer may contain the same material and be integrated. In this case, it is preferable that the functional layer is a hard coat layer and that the hard coat layer contains a cured product of a resin composition containing a polymerizable compound.

Furthermore, the glass laminate in this disclosure may have a third resin layer on the side of the glass substrate opposite to the first resin layer. In this case, it is preferable that the third resin layer contains at least one selected from the group consisting of polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin. In this case, the second resin layer and the third resin layer may contain the same material and be integrated.

Furthermore, in the glass laminate described herein, it is preferable that the glass substrate is chemically strengthened glass.

Furthermore, in the glass laminate described herein, it is preferable that the total light transmittance of the first resin layer is 82% or higher, and the haze is 1.0% or lower.

Furthermore, the glass laminate in this disclosure preferably has a total light transmittance of 82% or more and a haze of 1.0% or less.

Another embodiment of this disclosure provides a display device comprising a display panel and the aforementioned glass laminate positioned on the observer side of the display panel.

Other embodiments of this disclosure provide electronic equipment comprising the display device described above.

Another embodiment of this disclosure provides a resin layer that is disposed on the main surface side of a glass substrate having a thickness of 100 μm or less, and used to cover the side surface of the glass substrate, and is transparent.

The resin layer in this disclosure preferably contains at least one selected from the group consisting of polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin, or contains a cured product of a resin composition containing a polymerizable compound.

Furthermore, the resin layer in this disclosure preferably has a total light transmittance of 82% or more and a haze of 1.0% or less.

This disclosure offers the advantage of providing a glass laminate with good flexibility and impact resistance, as well as improved safety.

This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic perspective view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic cross-sectional view illustrating a glass laminate in this disclosure. This is a schematic diagram illustrating the dynamic flexion test. This is a schematic diagram illustrating the static flexion test. This is a schematic cross-sectional view illustrating a display device in this disclosure.

The embodiments of this disclosure will be described below with reference to the drawings and other illustrations. However, this disclosure can be implemented in many different ways and should not be interpreted as being limited to the embodiments described below. Furthermore, while the drawings may schematically represent the width, thickness, shape, etc., of parts in order to clarify the explanation, these are merely examples and should not limit the interpretation of this disclosure. In addition, in this specification and the drawings, elements similar to those described above in previously shown drawings will be denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

In this specification, when describing a configuration in which one component is placed on top of another component, unless otherwise specified, the terms "above" or "below" include both cases: the other component being placed directly above or below the component in contact with it, and the other component being placed above or below the component via yet another component. Furthermore, when describing a configuration in this specification in which one component is placed on the surface of another component, unless otherwise specified, the terms "on the surface" or "on the surface" include both cases: the other component being placed directly above or below the component in contact with it, and the other component being placed above or below the component via yet another component.

The following describes in detail the glass laminate, display device, electronic device, and resin layer in this disclosure.

A. Glass Laminate The glass laminate in this disclosure is a glass laminate having a glass substrate, a first resin layer, and a second resin layer, wherein the glass substrate has a first surface, a second surface opposite to the first surface, and a third surface different from the first surface and the second surface, the thickness of the glass substrate is 100 μm or less, the first resin layer is located on the side of the first surface and is transparent, and the second resin layer covers the third surface.
In other words, the glass laminate in this disclosure comprises a glass substrate having a thickness of 100 μm or less, a first resin layer disposed on one main surface side of the glass substrate and having transparency, and a second resin layer covering the side surface of the glass substrate.
Hereinafter, the phrase "the first resin layer is located on the first surface side and is transparent" may be expressed as "a first resin layer that is arranged on one main surface side of the glass substrate and is transparent."

Figure 1 is a schematic cross-sectional view showing an example of a glass laminate in this disclosure. As shown in Figure 1, the glass laminate 1 comprises a glass substrate 2 having a predetermined thickness, a first resin layer 3 disposed on the first surface (hereinafter sometimes referred to as the main surface) 2P side of the glass substrate 2 and having transparency, and a second resin layer 4 covering the third surface (hereinafter sometimes referred to as the side surface) 2S of the glass substrate 2.

In Figure 1, the first resin layer 3 and the second resin layer 4 are shown as a single layer, but this is not limited to that configuration; they may also be composed of separate layers.

In the glass laminate described in this disclosure, the glass substrate is thin, with a thickness below a predetermined value, which enhances its flexibility. However, because the glass substrate is thin, there is a concern that it is prone to cracking and has low impact resistance. In contrast, in this disclosure, by arranging the first resin layer on the main surface side of the glass substrate, when an impact is applied to the glass laminate, the first resin layer absorbs the impact, suppressing cracking of the glass substrate and thus improving impact resistance.

Here, as described in the examples and comparative examples below, placing the first resin layer on the main surface side of the glass substrate can improve impact resistance, but it results in worse bending resistance than the glass substrate alone. In contrast, in this disclosure, since the side surface of the glass substrate is covered with the second resin layer, it is possible to improve impact resistance while maintaining good bending resistance. The reason for this is presumed to be as follows.

Glass substrates are prone to microcracks during processing, particularly at the edges of the glass substrate when it is cut. Microcracks in the glass substrate make it easier for cracks to develop, often starting from these microcracks. Furthermore, even when using tempered glass as the substrate, if a large piece of tempered glass is cut, the cut surface (i.e., the side surface) lacks the compressive stress layer formed on the tempered glass surface, resulting in reduced strength at the side surface.

In contrast, in this disclosure, the strength of the side surface of the glass substrate can be increased by coating it with a second resin layer. Furthermore, when the second resin layer is directly positioned on the side surface of the glass substrate, the second resin layer can fill microcracks in the side surface of the glass substrate, thereby increasing its strength. Therefore, when the glass laminate is bent, cracking from the side surface of the glass substrate can be suppressed, maintaining good flexibility. In addition, impact resistance at the edges of the glass substrate can also be improved.

Therefore, this disclosure makes it possible to achieve both good bending resistance and impact resistance. Furthermore, even if the glass substrate in the glass laminate is damaged, the risk of injury to the human body can be reduced, resulting in a highly safe glass laminate. Thus, the glass laminate in this disclosure is bendable and can be used in a wide variety of display devices, for example, as a component for foldable displays.

The following describes the various components of the glass laminate in this disclosure.

1. First Resin Layer The first resin layer in this disclosure is disposed on the first surface side of the glass substrate and is transparent. The first resin layer can also function as an impact-absorbing layer having impact-absorbing properties, or as a shatterproof layer that suppresses the scattering of glass when the glass substrate breaks. When the glass laminate in this disclosure is disposed on the observer side of the display panel of a display device, the first resin layer is disposed on the observer side of the glass substrate.

(1) Characteristics of the first resin layer The first resin layer is transparent. Specifically, the total light transmittance of the first resin layer is preferably 82% or more, more preferably 85% or more, and even more preferably 88% or more. The upper limit is 100%.

Here, the total light transmittance of the first resin layer can be measured in accordance with JIS K7361-1, for example, using a haze meter HM150 manufactured by Murakami Color Technology Research Institute. The same method can be used for measuring the total light transmittance of the other layers.

Furthermore, the haze of the first resin layer is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.5% or less. The lower limit of the haze is 0%.

Here, the haze of the first resin layer can be measured in accordance with JIS K-7136, for example, using a haze meter HM150 manufactured by Murakami Color Technology Research Institute. The same method can be used for measuring the haze of the other layers.

The first resin layer preferably has impact-absorbing properties. Specifically, the composite elastic modulus of the first resin layer is preferably 4.7 GPa or higher, and more preferably 5.7 GPa or higher. Having the composite elastic modulus of the first resin layer within this range suppresses cracking of the glass substrate due to impact, thereby improving impact resistance and scratch resistance.

Furthermore, according to the composite elastic modulus measurement method described later, the composite elastic modulus of the glass substrate is approximately 40 GPa. Therefore, the composite elastic modulus of the first resin layer is preferably 40 GPa or less, and more preferably 20 GPa or less.
Specifically, it is preferable that the pressure be between 4.7 GPa and 40 GPa, and more preferably between 5.7 GPa and 20 GPa.

Here, the composite modulus of the first resin layer is calculated using the contact projected area A _p obtained when measuring the indentation hardness ( _HIT ) of the first resin layer. "Indentation hardness" is a value obtained from the load-displacement curve from loading to unloading of the indenter, which is obtained by hardness measurement using the nanoindentation method. The composite modulus of the first resin layer is the modulus of elasticity that includes the elastic deformation of the first resin layer and the elastic deformation of the indenter.

The indentation hardness ( _HIT ) will be measured using a BRUKER TI950 TriboIndenter on the sample. Specifically, a block will be prepared by embedding a 1 mm x 10 mm glass laminate in embedding resin. From this block, uniform sections with a thickness of 50 nm to 100 nm, free from holes, will be cut using a general sectioning method. An ultramicrotome EM UC7 (Leica Microsystems) or similar can be used to prepare the sections. The remaining block from which these uniform, hole-free sections have been cut will be used as the measurement sample. Next, in the cross-section obtained by cutting out the above section from the measurement sample, a Berkovich indenter (triangular pyramid, TI-0039 manufactured by BRUKER) is pressed vertically into the center of the cross-section of the first resin layer over 10 seconds to a maximum indentation load of 25 μN, under the following measurement conditions. Here, in order to avoid the influence of the glass substrate and the side edges of the first resin layer, the Berkovich indenter is pressed into a portion of the first resin layer 500 nm away from the interface between the glass substrate and the first resin layer towards the center of the first resin layer, and 500 nm away from both ends of the first resin layer towards the center of the resin layer. If there is any layer such as a functional layer on the side of the first resin layer opposite to the side facing the glass substrate, the indenter is also pressed into a portion of the first resin layer 500 nm away from the interface between the arbitrary layer and the first resin layer towards the center of the first resin layer. After holding the load for a certain period to allow residual stress to relax, the load is removed over 10 seconds, and the maximum load after relaxation is measured. The indentation hardness ( _HIT ) is calculated using the formula P _max (μN) and the contact projection area A _p ( ^nm² ) as P _max / A _p . The above contact projection area is the contact projection area corrected for the indenter tip curvature using the Oliver-Pharr method with a standard sample of fused silica (BRUKER 5-0098). The indentation hardness ( _HIT ) is the arithmetic mean of the values obtained from 10 measurements. If any of the measured values deviate by more than ±20% from the arithmetic mean, those measurements are excluded and remeasured. Whether or not there are any measurements that deviate from the arithmetic mean by ±20% or more is determined by whether the value (%) obtained by (A-B)/B × 100, where A is the measured value and B is the arithmetic mean, is ±20% or more. The indentation hardness ( _HIT ) can be adjusted by the type of resin contained in the first resin layer, as described later.

(Measurement conditions)
・Loading speed: 2.5 μN/sec ・Holding time: 5 seconds ・Load unloading speed: 2.5 μN/sec ・Measurement temperature: 25°C

The composite modulus _Er of the first resin layer is determined using the contact projected area _Ap obtained during the measurement of indentation hardness, according to the following formula (1). The composite modulus is calculated by measuring the indentation hardness at 10 locations, determining the composite modulus each time, and taking the arithmetic mean of the 10 obtained composite moduli.

(In the above formula (1), A _p is the contact projected area, _Er is the composite modulus of the first resin layer, and S is the contact stiffness.)

(2) Thickness of the first resin layer The thickness of the first resin layer is not particularly limited as long as flexibility and shock absorption can be obtained. For example, it is preferably 5 μm or more and 60 μm or less, more preferably 10 μm or more and 50 μm or less, and even more preferably 15 μm or more and 40 μm or less. By making the thickness of the first resin layer relatively thin, as within the above range, flexibility can be increased, cracking of the first resin layer can be suppressed when the glass laminate is bent, and bending resistance can be maintained.

Here, the thickness of the first resin layer can be the average value of any 10 thicknesses obtained by measuring the cross-section in the thickness direction of the glass laminate as observed by a transmission electron microscope (TEM), scanning electron microscope (SEM), or scanning transmission electron microscope (STEM). Unless otherwise specified, the same method can be used to measure the thickness of other layers in the glass laminate.

(3) Material of the first resin layer (a) Resin The resin included in the first resin layer is not particularly limited as long as it satisfies the above-mentioned composite elastic modulus and is transparent, for example, polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin. These resins may be used individually or in combination of two or more.

In this specification, polyimide resins refer to polymers having imide bonds in their main chain. Examples of polyimide resins include polyimide, polyamideimide, polyesterimide, and polyetherimide.

The following explanation will use polyimide as an example.

(Polyimide)
Polyimides are obtained by reacting a tetracarboxylic acid component with a diamine component. It is preferable to obtain polyamic acid by polymerization of the tetracarboxylic acid component and the diamine component and then imidate it. Imidation may be carried out by chemical imidation, thermal imidation, or a combination of chemical and thermal imidation.

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

(In general formulas (1) and (2), ^R1 to ^R4 each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and at least one of ^R1 and ^R2 , and at least one of ^R3 and ^R4 , represent an alkyl group having 1 to 6 carbon atoms. A represents a tetravalent group which is a tetracarboxylic acid residue having an aromatic or aliphatic ring, and B represents a divalent group which is a diamine residue having an aromatic or aliphatic ring.)

Here, a tetracarboxylic acid residue refers to a residue obtained by removing four carboxyl groups from a tetracarboxylic acid, and represents the same structure as a residue obtained by removing the acidic dianhydride structure from a tetracarboxylic dianhydride. Furthermore, a diamine residue refers to a residue obtained by removing two amino groups from a diamine.

In general formula (1), at least one of ^R1 and ^R2 , and at least one of ^R3 and ^R4 , represent an alkyl group having 1 to 6 carbon atoms. The alkyl group having 1 to 6 carbon atoms may be linear or branched alkyl group, and examples include a methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, n-pentyl group, and n-hexyl group. From the viewpoint of solvent solubility, an alkyl group having 1 to 4 carbon atoms is preferred, more preferably an alkyl group having 1 to 2 carbon atoms, and more preferably a methyl group. Among these, from the viewpoint of solvent solubility, it is preferable that ^R1 and ^R2 , and ^R3 and ^R4 represent a methyl group.

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

Specific examples of diamines having aromatic rings and diamines having aliphatic rings can be found in, for example, Japanese Patent Publication No. 2019-132930 and Japanese Patent Publication No. 2019-1989. These can be used individually or in combination of two or more types.

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

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

Specific examples of tetracarboxylic dianhydrides having aromatic rings and tetracarboxylic dianhydrides having aliphatic rings can be found in, for example, Japanese Patent Publication No. 2019-132930 and Japanese Patent Publication No. 2019-1989. These can be used individually or in combination of two or more types.

The polyimide preferably contains 10 mol% to 100 mol% of the constituent units represented by the general formula (1) above. From the viewpoint of solubility in solvents, the polyimide more preferably contains 15 mol% or more of the constituent units represented by the general formula (1), even more preferably 25 mol% or more, and particularly preferably 50 mol% or more.

On the other hand, since surface hardness and transparency are improved, copolymer components may be included. The polyimide may contain 95 mol% or less of the constituent units represented by the general formula (1) above, 90 mol% or less, or 80 mol% or less.

Furthermore, it is preferable that the polyimide contains (100-x) mol% of the constituent units represented by the general formula (2) above (where x is the mol% of the constituent units represented by the general formula (1) above). From the viewpoint of solubility in solvents, it is more preferable that the polyimide contains 85 mol% or less of the constituent units represented by the general formula (2), even more preferable that it contains 75 mol% or less, and particularly preferable that it contains 50 mol% or less.

Furthermore, if the polyimide contains 100 mol% of the constituent units represented by the general formula (1) above, then the constituent units represented by the general formula (2) above will be 0 mol%, i.e., not present. While the constituent units represented by the general formula (2) above may be 0 mol%, they may also be included as copolymer components to improve surface hardness and transparency. The polyimide may contain 5 mol% or more, 10 mol% or more, or 20 mol% or more of the constituent units represented by the general formula (2) above.

From the viewpoint of improving transparency and surface hardness, it is preferable that at least one of the tetravalent group, which is a tetracarboxylic acid residue of A, and the divalent group, which is a diamine residue of B, contains an aromatic ring and includes at least one selected from the group consisting of (i) a fluorine atom, (ii) an aliphatic ring, and (iii) an alkylene group which may be substituted with a sulfonyl group or fluorine. When polyimide contains at least one selected from a tetracarboxylic acid residue having an aromatic ring and a diamine residue having an aromatic ring, the molecular skeleton becomes rigid, the orientation is increased, and the surface hardness is improved. However, a rigid aromatic ring skeleton tends to have an absorption wavelength that extends to longer wavelengths, and the transmittance in the visible light region tends to decrease. On the other hand, when polyimide contains (i) a fluorine atom, the electronic state within the polyimide skeleton can be made less susceptible to charge transfer, thus improving transparency. Furthermore, when polyimide contains (ii) aliphatic rings, transparency is improved because it can disrupt the conjugation of π electrons within the polyimide framework, thereby inhibiting charge movement within the framework. Additionally, when polyimide contains (iii) a structure in which aromatic rings are linked by sulfonyl groups or alkylene groups that may be substituted with fluorine, transparency is improved because it can disrupt the conjugation of π electrons within the polyimide framework, thereby inhibiting charge movement within the framework.

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

Polyimide is selected from the viewpoints of transparency, flexibility, and surface hardness, and the diamine residue having an aromatic ring or aliphatic ring in B of the above general formulas (1) and (2) is trans-cyclohexanediamine residue, trans-1,4-bismethylenecyclohexanediamine residue, 4,4'-diaminodiphenylsulfone residue, 3,4'-diaminodiphenylsulfone residue, 2,2-bis(4-aminophenyl)propane residue, 3,3'-bis(trifluoromethyl)-4,4'-[ Preferably, the group is at least one divalent group selected from the group consisting of (1,1,1,3,3,3-hexafluoropropane-2,2-diyl)bis(4,1-phenyleneoxy)]dianiline residue, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane residue, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane residue, and a divalent group represented by the following general formula (3). In particular, from the viewpoint of achieving both transparency and surface hardness, it is preferable that the group consists of at least one divalent group selected from the group comprising a 4,4'-diaminodiphenylsulfone residue, a 3,4'-diaminodiphenylsulfone residue, a 2,2-bis(4-aminophenyl)propane residue, and a divalent group represented by the following general formula (3), and more preferably a divalent group represented by the following general formula (3). As the divalent group represented by the following general formula (3), it is more preferable that ^R5 and ^R6 are perfluoroalkyl groups, and among these, perfluoroalkyl groups having 1 to 3 carbon atoms are preferred, and more preferably a trifluoromethyl group or a perfluoroethyl group. Furthermore, as the alkyl groups in ^R5 and ^R6 in the following general formula (3), it is preferable that they are alkyl groups having 1 to 3 carbon atoms, and more preferably a methyl group or an ethyl group.

(In general formula (3), ^R5 and ^R6 each independently represent a hydrogen atom, an alkyl group, or a perfluoroalkyl group.)

Polyimides, in particular, are selected from the viewpoints of transparency, flexibility, and surface hardness, such as the tetracarboxylic acid residue having an aromatic or aliphatic ring in A of the above general formula (2), which includes cyclohexanetetracarboxylic acid dianhydride residues, cyclopentanetetracarboxylic acid dianhydride residues, dicyclohexane-3,4,3',4'-tetracarboxylic acid dianhydride residues, cyclobutanetetracarboxylic acid dianhydride residues, pyromellitic acid dianhydride residues, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride residues, and 2,2',3,3' Preferably, it is at least one tetravalent group selected from the group consisting of -biphenyltetracarboxylic acid dianhydride residue, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride residue, 4,4'-(hexafluoroisopropylidene)diphthalic acid anhydride residue, 3,4'-(hexafluoroisopropylidene)diphthalic acid anhydride residue, 3,3'-(hexafluoroisopropylidene)diphthalic acid anhydride residue, 4,4'-oxydiphthalic acid anhydride residue, and 3,4'-oxydiphthalic acid anhydride residue.

In the above general formula (2), it is preferable that A contains a total of 50 mol% or more of these preferred residues, more preferably 70 mol% or more, and even more preferably 90 mol% or more.

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

When mixing Group A and Group B, the preferred ratio of the tetracarboxylic acid residue group suitable for improving rigidity (Group A) to the tetracarboxylic acid residue group suitable for improving transparency (Group B) is 0.05 moles to 9 moles, more preferably 0.1 moles to 5 moles, and even more preferably 0.3 moles to 4 moles, of the tetracarboxylic acid residue group suitable for improving rigidity (Group A) per mole of the tetracarboxylic acid residue group suitable for improving transparency (Group B).

In particular, from the viewpoint of improving surface hardness and transparency, it is preferable to use at least one of the following residues in Group B: a 4,4'-(hexafluoroisopropylidene)diphthalic anhydride residue containing a fluorine atom, and a 3,4'-(hexafluoroisopropylidene)diphthalic anhydride residue.

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

From the viewpoint of good flexural resistance, the polyimide preferably has a weight-average molecular weight of 100,000 or more in terms of polystyrene equivalent in gel permeation chromatography. From the viewpoint of flexural resistance, the weight-average molecular weight may be 120,000 or more, 140,000 or more, or 160,000 or more. On the other hand, from the viewpoint of less likelihood of bubble defects, the weight-average molecular weight is preferably 270,000 or less. Furthermore, from the viewpoint of solubility, the weight-average molecular weight may be 250,000 or less, 230,000 or less, or 210,000 or less.

The weight-average molecular weight of polyimide can be measured by gel permeation chromatography (GPC). Specifically, the polyimide is used as a 0.1% by mass N-methylpyrrolidone (NMP) solution, and the developing solvent is a 30 mmol LiBr-NMP solution with a water content of 500 ppm or less. Measurement is performed using a Tosoh GPC instrument (HLC-8120, column: SHODEX GPC LF-804) with a sample input 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 based on a polystyrene standard sample of the same concentration as the sample.

(b) UV absorber The first resin layer may contain a UV absorber. This can suppress the degradation of the first resin layer due to ultraviolet light. In particular, if the first resin layer contains polyimide, it can suppress the color change of the first resin layer containing polyimide over time. Furthermore, in a display device equipped with a glass laminate, it can suppress the degradation of components located on the display panel side of the glass laminate, such as polarizers, due to ultraviolet light.

Examples of UV absorbers included in the first resin layer include triazine-based UV absorbers, benzophenone-based UV absorbers such as hydroxybenzophenone-based UV absorbers, and benzotriazole-based UV absorbers.

Specific examples of triazine-based UV absorbers, benzophenone-based UV absorbers such as hydroxybenzophenone-based UV absorbers, and benzotriazole-based UV absorbers can be found, for example, in Japanese Patent Publication No. 2019-132930.

Among the UV absorbers, triazine-based UV absorbers, hydroxybenzophenone-based UV absorbers, and benzotriazole-based UV absorbers are particularly preferred.

Furthermore, the UV absorber is preferably a polymer or oligomer. This is because it can suppress the bleed-out of the UV absorber when the glass laminate is repeatedly bent. Examples of such UV absorbers include polymers or oligomers having a triazine skeleton, a benzophenone skeleton, or a benzotriazole skeleton. Specifically, it is preferable that the UV absorber is obtained by thermal copolymerizing a (meth)acrylate having a benzotriazole or benzophenone skeleton with methyl methacrylate (MMA) in any ratio.

The content of the UV absorber in the first resin layer is not particularly limited, but is preferably 1% to 6% by mass, and more preferably 2% to 5% by mass. If the UV absorber content is too low, the effect of the UV absorber may not be fully obtained. Conversely, if the UV absorber content is too high, the first resin layer may become significantly discolored or its strength may decrease.

(c) Other additives The first resin layer may further contain additives as needed. Examples of additives include inorganic particles, silica fillers to facilitate winding, surfactants to improve film-forming and defoaming properties, and adhesion enhancers.

(4) Method for forming the first resin layer As a method for forming the first resin layer, for example, a method of applying a resin composition onto a glass substrate is used. The application method is not particularly limited as long as it can be applied to the desired thickness, and examples of general application methods include gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, spray coating, die coating, and screen printing. In addition, as a method for forming the first resin layer, a transfer method in which the first resin layer is transferred to the main surface of the glass substrate, or a method of laminating a film-like first resin layer to the main surface of the glass substrate via an adhesive layer can also be used.

The adhesive layer is transparent. Specifically, the total light transmittance of the adhesive layer is preferably 85% or higher, more preferably 88% or higher, and even more preferably 90% or higher. The upper limit is 100%.

Examples of adhesives used in the bonding layer include OCA (Optical Clear Adhesive) and photosensitive adhesives.

The thickness of the adhesive layer is preferably, for example, 1 μm to 100 μm. If the adhesive layer is too thick, the flexibility may be compromised. On the other hand, if the adhesive layer is too thin, the adhesion may not be guaranteed, and the adhesive may peel off.

The following explanation will use the case where the first resin layer contains polyimide as an example.

(Method for forming a first resin layer containing polyimide)
Methods for forming a first resin layer containing polyimide include, for example, applying a polyimide varnish containing polyimide and an organic solvent to a glass substrate and drying it, and applying a polyimide precursor composition containing a polyimide precursor (polyamic acid) and an organic solvent to a glass substrate, and then imidizing the polyimide precursor by heat treatment or chemical treatment. In the former method, the heating conditions of the film formation process can be relaxed. On the other hand, in the latter method, the constraints on the solubility of polyimide are removed, thus increasing the options for the chemical structure of the polyimide.

In particular, the following manufacturing method is preferred because it is less prone to the occurrence of air bubble defects and makes it easier to obtain a first resin layer with good thickness uniformity.

A method for forming a first resin layer containing polyimide preferably comprises the following steps: a preparation step of preparing a polyimide varnish containing polyimide and an organic solvent, wherein the polyimide content is 6% by mass or more and 15% by mass or less in the polyimide varnish, and the viscosity at 25°C is 1,000 cps or more and 50,000 cps or less; a coating step of applying the polyimide varnish onto a glass substrate; a first drying step of drying the coating film at a temperature of 140°C or lower; and a second drying step of heating the dried coating film at a temperature of 200°C or higher.

When polyimide dissolves well in organic solvents, the heating conditions of the film formation process can be relaxed. Therefore, it is preferable to form the first resin layer using a polyimide varnish obtained by dissolving polyimide in an organic solvent. Polyimide is easily soluble in organic solvents when it contains a specific amount or more of a constituent unit containing a tetracarboxylic acid residue with a specific structure, including a parabiphenylene group with a dihedral angle twisted via an ester bond in the main chain. When polyimide has solvent solubility such that it dissolves in an organic solvent at 25°C at a concentration of 6% by mass or more, the above method for forming the first resin layer can be suitably used.

According to the above method for forming the first resin layer, the polyimide content in the varnish can be increased to a sufficient concentration, and the varnish can be adjusted to a desired viscosity range. Therefore, a first resin layer with good thickness uniformity and less susceptibility to air bubble defects can be obtained.

The above organic solvent is not particularly limited as long as it can dissolve polyimide; for example, aprotic polar solvents or water-soluble alcohol-based solvents can be used. Among these, it is preferable to use organic solvents containing nitrogen atoms, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphoramide, 1,3-dimethyl-2-imidazolidinone, or γ-butyrolactone. Furthermore, the above organic solvents can be used as one or a mixture of two or more solvents.

For a method of forming the first resin layer containing the above-mentioned polyimide, refer to, for example, the methods described in Japanese Patent Publication No. 2019-1989 and Japanese Patent Publication No. 2019-182974.

2. Second resin layer The second resin layer in this disclosure is a layer that covers the side surface of the glass substrate.

In this specification, "side surface" of the glass substrate refers to all surfaces of the glass substrate other than the opposing first and second surfaces. Furthermore, for example, if the glass substrate has been chamfered, the side surface of the glass substrate may have a chamfered portion.

The second resin layer is preferably transparent. Specifically, the total light transmittance and haze of the second resin layer can be the same as those of the first resin layer.

The second resin layer preferably has shock-absorbing properties. Specifically, the composite elastic modulus of the second resin layer can be the same as that of the first resin layer.

Furthermore, the method for measuring the composite elastic modulus of the second resin layer can be the same as that for the composite elastic modulus of the first resin layer.

The thickness of the second resin layer in the direction parallel to the main surface of the glass substrate is not particularly limited as long as flexibility and shock absorption are obtained. For example, it is preferably 4 μm or more and 2000 μm or less, more preferably 5 μm or more and 1000 μm or less, and even more preferably 10 μm or more and 100 μm or less. By having the thickness of the second resin layer in the direction parallel to the main surface of the glass substrate within the above range, cracking of the glass substrate can be suppressed when the glass laminate is bent, and the bending resistance can be improved. Furthermore, the impact resistance at the edges of the glass substrate can be improved.

Furthermore, the thickness of the second resin layer is preferably such that 0.01 ≤ T1/T2 ≤ 5.0 is satisfied when the thickness of the first resin layer is T1 and the thickness of the second resin layer is T2, more preferably 0.1 ≤ T1/T2 ≤ 4.0 is satisfied, and in particular preferably 0.5 ≤ T1/T2 ≤ 3.5 is satisfied.
By keeping the above thickness ratio within the specified range, cracking of the glass substrate can be suppressed when the glass laminate is bent, thereby improving its flexibility. Furthermore, impact resistance at the edges of the glass substrate can be improved.

Here, "thickness of the second resin layer" refers to the thickness of the second resin layer from the leading edge of the glass substrate's side surface, in a direction opposite to the glass substrate itself and parallel to the first surface, when the laminate of this disclosure is cut perpendicular to the third surface. Furthermore, if the thickness of the second resin layer from the leading edge of the glass substrate's side surface is non-uniform, the minimum thickness of the second resin layer from the leading edge of the glass substrate's side surface shall be used.

The thickness of the second resin layer on the glass substrate is determined appropriately according to the shape of the edges of the glass substrate. For example, as shown in Figure 2(a), if the cross-sectional shape of the edge of the glass substrate 2 is trapezoidal, the thickness T2 of the second resin layer 4 is the minimum thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2.

Furthermore, as shown in Figure 2(b), for example, when the cross-sectional shape of the end of the glass substrate 2 is rectangular, the thickness T2 of the second resin layer 4 is the minimum thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2. Also, as shown in Figure 2(c), for example, when the cross-sectional shape of the end of the glass substrate 2 is triangular, the thickness T2 of the second resin layer 4 is the thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2.

Furthermore, for example, as shown in Figure 2(d), if the cross-sectional shape of the end of the glass substrate 2 is semi-elliptical, the thickness T2 of the second resin layer 4 is the thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2. Also, for example, as shown in Figure 3(a), if the cross-sectional shape of the end of the glass substrate 2 is substantially rectangular, the thickness T2 of the second resin layer 4 is the minimum thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2.

Furthermore, as shown in Figure 3(b), for example, if the cross-sectional shape of the end of the glass substrate 2 is chamfered, the thickness T2 of the second resin layer 4 is the minimum thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2. Also, as shown in Figure 3(c), for example, if the cross-sectional shape of the end of the glass substrate 2 is a quadrant, the thickness T2 of the second resin layer 4 is the thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2. Also, as shown in Figure 3(d), for example, if the cross-sectional shape of the end of the glass substrate 2 is a semicircular shape, the thickness T2 of the second resin layer 4 is the thickness of the second resin layer 4 from the tip portion 2E on the side surface of the glass substrate 2.

Furthermore, the degree to which the second resin layer covers the sides of the glass substrate is not particularly limited, as long as it is possible to increase the strength of the sides of the glass substrate by covering them with the second resin layer. For example, the entire surface of the side of the glass substrate may be covered with the second resin layer, or only a portion of the side may be covered with the second resin layer. More specifically, the entire surface present on the edge of the glass substrate may be covered with the second resin layer, or only a portion of the surface present on the edge of the glass substrate may be covered with the second resin layer. Also, the entire thickness of the glass substrate on the side may be covered with the second resin layer, or only a portion of the thickness of the glass substrate on the side may be covered with the second resin layer.

Regarding the degree of coverage of the side surfaces of the glass substrate by the second resin layer in the thickness direction of the glass substrate, specifically, the ratio of the thickness T4 of the second resin layer in the thickness direction of the glass substrate to the thickness T3 of the glass substrate (T4/T3) is preferably 0.5 or more, but may also be 1.0 or more, or 1.5 or more. By having the above ratio (T4/T3) within this range, cracking of the glass substrate can be suppressed when the glass laminate is bent, thereby improving its bending resistance. Furthermore, impact resistance at the edges of the glass substrate can be improved. Note that the upper limit of the above ratio (T4/T3) is not particularly limited and may be, for example, 3.0 or less. For example, in Figure 4(a), the above ratio (T4/T3) is greater than 1, and in Figure 4(b), the above ratio (T4/T3) is less than 1.

The thickness direction of the glass substrate refers to the direction perpendicular to the main surface (first surface) of the glass substrate. Furthermore, the thickness of the second resin layer in the thickness direction of the glass substrate refers to the thickness of the second resin layer in the direction from the main surface (first surface) to the surface opposite the main surface (second surface), along the thickness direction of the glass substrate. For example, in Figures 2(a)-(d), 3(a)-(d), and 4(a)-(c), the thickness T4 of the second resin layer in the thickness direction of the glass substrate is the thickness of the second resin layer 4 from the main surface 2P of the glass substrate 2, along the thickness direction of the glass substrate 2.

Here, the shape of the glass substrate is typically a rectangular parallelepiped, or a hexahedron. Even when the glass substrate has been chamfered, for example, its shape can still be considered typically a rectangular parallelepiped, or roughly a hexahedron. In this case, the glass substrate has opposing first and second faces and four third faces (sides). In such a case, the degree of coverage of the third faces of the glass substrate by the second resin layer is sufficient if at least one of the four third faces of the glass substrate is covered by the second resin layer. That is, in this case, one of the four third faces of the glass substrate may be covered by the second resin layer, two may be covered, three may be covered, or all four may be covered.

In particular, it is preferable that two opposing third surfaces of the four third surfaces of the glass substrate are covered with the second resin layer, and that two sides of the four third surfaces of the glass substrate that are substantially parallel to the bending direction of the glass laminate are covered with the second resin layer. For example, as shown in Figures 5(a) and (b), when the glass laminate 1 is bent, cracks are likely to occur in the glass substrate at the bent portion 1F of the glass laminate 1. Therefore, if two of the four third surfaces of the glass substrate that are substantially parallel to the bending direction D1 of the glass laminate 1 are covered with the second resin layer, it is possible to suppress cracking at the bent portion when the glass laminate is bent and improve its bending resistance.

In particular, it is preferable that all four third surfaces of the glass substrate are covered with the second resin layer. This suppresses cracking of the glass substrate when the glass laminate is bent, improving its flexibility. Furthermore, it improves the impact resistance at the edges of the glass substrate.

Therefore, as described above, when the ratio of the thickness T1 of the first resin layer to the thickness T2 of the second resin layer (T1/T2) is within a predetermined range, and the glass substrate is in the shape of a rectangular parallelepiped, it is preferable that the above ratio (T1/T2) is within the above range on at least one of the four third surfaces of the glass substrate. In particular, it is preferable that the above ratio (T1/T2) is within the above range on two opposing third surfaces of the four third surfaces of the glass substrate, and more preferably that the above ratio (T1/T2) is within the above range on all four third surfaces of the glass substrate.

Furthermore, as described above, when the ratio of the thickness T4 of the second resin layer in the thickness direction of the glass substrate to the thickness T3 of the glass substrate (T4/T3) is within a predetermined range, and the glass substrate is in the shape of a rectangular parallelepiped, it is preferable that the above ratio (T4/T3) is within the above range on at least one of the four third surfaces of the glass substrate. In particular, it is preferable that the above ratio (T4/T3) is within the above range on two opposing third surfaces of the four third surfaces of the glass substrate, and it is preferable that the above ratio (T4/T3) is within the above range on all four third surfaces of the glass substrate.

Furthermore, regarding the degree of coverage of the glass substrate's sides by the second resin layer, specifically, when the glass substrate is rectangular, and the sum of the lengths of the four sides when viewed from above is taken as 100%, the percentage of the four sides of the glass substrate where the above ratio (T1/T2) falls within the above range is preferably 2% or more, more preferably 50% or more, and even more preferably 90% or more. As described above, for example, as shown in Figures 5(a) and (b), when the glass laminate 1 is bent, cracks are likely to occur in the glass substrate at the bent portion 1F of the glass laminate 1. Therefore, if the above ratio (T1/T2) is within the above range at the bent portion 1F on two of the four sides of the glass substrate that are substantially parallel to the bending direction D1 of the glass laminate 1, cracks in the glass substrate can be suppressed when the glass laminate is bent. Thus, even if the above percentage is 2%, an improvement in bending resistance can be expected.

Furthermore, regarding the degree of coverage of the glass substrate's sides by the second resin layer, specifically, when the glass substrate is rectangular, and the sum of the lengths of the four sides when viewed from above is taken as 100%, the percentage of the four sides of the glass substrate where the above ratio (T4/T3) falls within the above range is preferably 2% or more, more preferably 50% or more, and even more preferably 90% or more. For the reasons stated above, even if the above percentage is 2%, an improvement in bending resistance can be expected.

Furthermore, the thickness of the second resin layer in the direction parallel to the first surface, and the thickness of the second resin layer in the thickness direction of the glass substrate, can be measured from a cross-section of the glass laminate in the thickness direction observed using a transmission electron microscope (TEM), scanning electron microscope (SEM), or scanning transmission electron microscope (STEM).

The second resin layer is not particularly limited as long as it covers the side surface of the glass substrate, but it is preferable that it contains the same material as the other layers located on the main surface (first surface) side of the glass substrate and is integrated with them. When the second resin layer contains the same material as the other layers located on the main surface side of the glass substrate and is integrated with them, there is no interface between the second resin layer and the other layers, thus increasing the strength at the edges of the glass substrate. Furthermore, since the second resin layer and the other layers can be formed simultaneously, the number of processes can be reduced, and manufacturing efficiency can be increased.

In this disclosure, when two layers are described as "containing the same material," it means that when the two layers are analyzed using an analytical instrument, the results are identical, taking into account the errors of the analytical instrument.

Furthermore, the statement that the second resin layer is integrated with the other layers means that the second resin layer and the other layers contain the same material and are formed continuously as a single layer.

When the second resin layer contains the same material as the other layers and is integrated, the other layers can be any layer located on the main surface side of the glass substrate, such as the first resin layer, the functional layer described later, or the third resin layer described later. For example, as shown in Figure 1, the second resin layer 4 may contain the same material as the first resin layer 3 and be integrated. Also, as shown in Figure 6, for example, when a functional layer such as a hard coat layer 5 is located on the side of the first resin layer 3 opposite to the glass substrate 2, the second resin layer 4 may contain the same material as the functional layer such as the hard coat layer 5 and be integrated. Furthermore, as shown in Figure 7, for example, when the third resin layer 6 is located on the side of the glass substrate 2 opposite to the first resin layer 3, the second resin layer 4 may contain the same material as the third resin layer 6 and be integrated.

Furthermore, as shown in Figure 7, when the first resin layer and the second resin layer are formed from different materials, and there is a boundary between the first and second resin layers, the first resin layer extends to the boundary with the second resin layer.

The material for the second resin layer can be the same as the material used for the first resin layer. Alternatively, the material used for the functional layer described later can also be used for the second resin layer.

If the second resin layer is integrated with the first resin layer, it contains the same material as the first resin layer. Similarly, if the second resin layer is integrated with the third resin layer, it contains the same material as the third resin layer. Furthermore, if the second resin layer is integrated with the functional layer, it contains the same material as the functional layer.

The method for forming the second resin layer is appropriately selected depending on the morphology of the second resin layer, etc.

For example, if the second resin layer contains the same material as the first resin layer and is integrated with it, the second resin layer is formed simultaneously with the first resin layer. A method for forming the first and second resin layers is, for example, to apply the resin composition to the main surface and side surfaces of the glass substrate. The application method can be the same as the method for forming the first resin layer described above. Furthermore, if the second resin layer contains the same material as the first resin layer and is integrated with it, a transfer method for transferring the first resin layer to the main surface and side surfaces of the glass substrate, or a method for bonding a film-like resin layer to the main surface and side surfaces of the glass substrate via an adhesive layer, can also be used as a method for forming the first and second resin layers. Also, if the second resin layer contains the same material as the third resin layer described later and is integrated with it, the method can be the same as the case where the second resin layer contains the same material as the first resin layer and is integrated with it. Furthermore, if the second resin layer contains the same material as the functional layer described later and is integrated with it, the second resin layer is formed simultaneously with the functional layer. The method for forming the functional layer and the second resin layer can be the same as the method for forming the functional layer described later.

3. Glass Substrate The glass substrate in this disclosure has a thickness of 100 μm or less and is a member that supports the first resin layer.

The glass constituting the glass substrate is not particularly limited, but chemically strengthened glass is preferred. Chemically strengthened glass is preferable because it has excellent mechanical strength and can be made thinner. Chemically strengthened glass is typically glass whose mechanical properties have been strengthened by a chemical method, such as by partially exchanging ionic species near the surface of the glass, such as replacing sodium with potassium, and has a compressive stress layer on its surface. Chemically strengthened glass with a surface compressive stress value (CS) of 450 MPa or more is particularly preferred.
Typically, the upper limit for the surface compressive stress (CS) of chemically strengthened glass is 850 MPa or less.

Here, the surface compressive stress (CS) of chemically strengthened glass can be measured, for example, by the refractometer method. Specifically, it can be measured using the Lukeo FSM-6000LE refractometer-type glass surface stress meter.

Examples of glass materials that make up chemically strengthened glass substrates include aluminosilicate glass, soda-lime glass, borosilicate glass, lead glass, alkali barium glass, and aluminoborsilicate glass.

Examples of commercially available chemically strengthened glass substrates include Corning's Gorilla Glass and AGC's Dragontrail. Alternatively, the chemically strengthened glass substrate described in Japanese Patent Publication No. 2019-194143 can also be used.

The thickness of the glass substrate is 100 μm or less, preferably 15 μm or more and 100 μm or less, more preferably 20 μm or more and 90 μm or less, and even more preferably 25 μm or more and 80 μm or less. By making the glass substrate thin within the above range, good flexibility and sufficient hardness can be obtained. Furthermore, curling of the glass laminate can be suppressed. Moreover, it is preferable in terms of reducing the weight of the glass laminate.

The shape of the end of the glass substrate is not particularly limited. The cross-sectional shape of the end of the glass substrate can be any shape, such as a trapezoid as shown in Figure 2(a), a rectangle as shown in Figure 2(b), a triangle as shown in Figure 2(c), a semi-ellipse as shown in Figure 2(d), a roughly rectangular shape as shown in Figure 3(a), a chamfered shape as shown in Figure 3(b), a quarter-circle shape as shown in Figure 3(c), a semi-circular shape as shown in Figure 3(d), etc.

In particular, the cross-sectional shape of the edge of the glass substrate is preferably such that the corners of the edge of the glass substrate are chamfered. Examples of chamfered corners include, for example, a square face, a rounded face, a semi-circular face, etc. Specifically, shapes like those shown in Figures 2(a), (c), (d) and Figures 3(a) to (d) are examples. When the cross-sectional shape of the edge of the glass substrate has chamfered corners, the resin composition can be easily applied to the side surface of the glass substrate, and the second resin layer can be easily formed. Furthermore, in this case, the flexibility of the glass substrate can be improved.

In particular, the cross-sectional shape of the edge of the glass substrate is preferably such that the corners of the edge of the glass substrate are rounded, that is, the corners have an R-shape. Examples of shapes with R-shaped corners include those shown in Figures 2(d), 3(a), (c), and (d). When the cross-sectional shape of the edge of the glass substrate has R-shaped corners, the resin composition can be more easily applied to the side surface of the glass substrate, and the second resin layer can be easily formed. Furthermore, in this case, the flexibility of the glass substrate can be further improved.

4. Functional Layer The glass laminate in this disclosure may further have a functional layer on the side of the first resin layer opposite to the glass substrate, i.e., on the second side. Examples of functional layers include a hard coat layer, a protective layer, an anti-reflective layer, an anti-glare layer, and the like.

Furthermore, the functional layer may be a single layer or may consist of multiple layers. Also, the functional layer may be a layer having a single function or may consist of multiple layers having different functions. For example, the glass laminate in this disclosure may have a hard coat layer and a protective layer as functional layers, in that order from the first resin layer side.

(1) Hard Coat Layer The glass laminate in this disclosure may further have a hard coat layer 5 on the side of the first resin layer 3 opposite to the glass substrate 2, as shown in Figure 8, for example. The hard coat layer is a component for increasing surface hardness. The presence of the hard coat layer improves scratch resistance.

(a) Characteristics of the hard coat layer Here, the "hard coat layer" is a component for increasing surface hardness, and specifically refers to a hard coat layer that exhibits a hardness of "H" or higher when a pencil hardness test is performed according to JIS K 5600-5-4 (1999) in a configuration in which the glass laminate in this disclosure has a hard coat layer.

In the case where the glass laminate in this disclosure has a hard coat layer on the side of the first resin layer opposite to the glass substrate, the pencil hardness of the hard coat layer side of the glass laminate is preferably H or higher, more preferably 2H or higher, and even more preferably 3H or higher.

Here, pencil hardness is measured using the pencil hardness test specified in JIS K5600-5-4 (1999). Specifically, using a test pencil specified in JIS-S-6006, the pencil hardness test specified in JIS K5600-5-4 (1999) is performed on the hard coat layer side of the glass laminate, and the highest pencil hardness without scratching is evaluated. Measurement conditions can be set to an angle of 45°, a load of 750g, a speed of 0.5 mm/sec to 1 mm/sec, and a temperature of 23±2°C. As a pencil hardness tester, for example, a pencil scratch coating hardness tester manufactured by Toyo Seiki Co., Ltd. can be used.

(b) Structure of the hard coat layer The hard coat layer may be a single layer or may have a multilayer structure of two or more layers. When the hard coat layer has a multilayer structure, in order to improve surface hardness and to have a good balance between flexural resistance and elastic modulus, it is preferable that the hard coat layer has a layer to satisfy the pencil hardness and a layer to satisfy the dynamic flexural test (a layer to satisfy the scratch resistance).

(c) Material of the hard coat layer For example, organic materials, inorganic materials, organic-inorganic composite materials, etc. can be used as the material for the hard coat layer.

In particular, the hard coat layer is preferably made of an organic material. Specifically, the hard coat layer is preferably made of a cured resin composition containing a polymerizable compound. A cured resin composition containing a polymerizable compound can be obtained by polymerizing the polymerizable compound using a known method, with a polymerization initiator used as needed.

(i) Polymerizable compounds A polymerizable compound has at least one polymerizable functional group in its molecule. Examples of polymerizable compounds include at least one radical polymerizable compound and a cationic polymerizable compound.

A radical polymerizable compound is a compound that possesses a radical polymerizable group. The radical polymerizable group in a radical polymerizable compound can be any functional group capable of undergoing a radical polymerization reaction; it is not particularly limited, but examples include groups containing a carbon-carbon unsaturated double bond, specifically vinyl groups and (meth)acryloyl groups. Furthermore, if a radical polymerizable compound has two or more radical polymerizable groups, these radical polymerizable groups may be identical or different.

The number of radical polymerizable groups in a single molecule of a radical polymerizable compound is preferably two or more, and more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.

As radical polymerizable compounds, compounds having (meth)acryloyl groups are preferred due to their high reactivity. For example, polyfunctional (meth)acrylate monomers and oligomers with molecular weights of several hundred to several thousand, having several (meth)acryloyl groups in the molecule, such as urethane (meth)acrylate, polyester (meth)acrylate, epoxy (meth)acrylate, melamine (meth)acrylate, polyfluoroalkyl (meth)acrylate, and silicone (meth)acrylate, can be preferably used. Polyfunctional (meth)acrylate polymers having two or more (meth)acryloyl groups in the side chain of the acrylate polymer can also be preferably used. In particular, polyfunctional (meth)acrylate monomers having two or more (meth)acryloyl groups in one molecule can be preferably used. By including cured products of polyfunctional (meth)acrylate monomers in the hard coat layer, the hardness of the hard coat layer can be improved, and the adhesion can be further improved. Furthermore, polyfunctional (meth)acrylate oligomers or polymers having two or more (meth)acryloyl groups in a single molecule can also be preferably used. By including a cured product of the polyfunctional (meth)acrylate oligomer or polymer in the hard coat layer, the hardness and flexibility of the hard coat layer can be improved, and its adhesion can be further enhanced.

In this specification, (meth)acryloyl refers to acryloyl and methacryloyl respectively, and (meth)acrylate refers to acrylate and methacrylate respectively.

Specific examples of polyfunctional (meth)acrylate monomers can be found, for example, in Japanese Patent Publication No. 2019-132930. In particular, those having 3 to 6 (meth)acryloyl groups per molecule are preferred due to their high reactivity, improved hardness of the hard coat layer, and adhesion. For example, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, etc., can be preferably used. Especially preferred are pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexaacrylate, as well as at least one selected from those modified with PO, EO, or caprolactone.

The resin composition may contain monofunctional (meth)acrylate monomers as radical polymerizable compounds for purposes such as adjusting hardness and viscosity, and improving adhesion. Specific examples of monofunctional (meth)acrylate monomers can be found in, for example, Japanese Patent Application Publication No. 2019-132930.

A cationic polymerizable compound is a compound that possesses a cationic polymerizable group. The cationic polymerizable group in a cationic polymerizable compound can be any functional group capable of undergoing a cationic polymerization reaction; it is not particularly limited, but examples include epoxy groups, oxetanyl groups, and vinyl ether groups. Furthermore, if a cationic polymerizable compound has two or more cationic polymerizable groups, these groups may be identical or different.

The number of cationic polymerizable groups in a single molecule of a cationic polymerizable compound is preferably two or more, and more preferably three or more, from the viewpoint of improving the hardness of the hard coat layer.

Furthermore, among cationic polymerizable compounds, compounds having at least one of an epoxy group and an oxetanyl group as cationic polymerizable groups are preferred, and compounds having two or more of at least one of the epoxy group and oxetanyl group in one molecule are more preferred. Cyclic ether groups such as epoxy groups and oxetanyl groups are preferred because they exhibit less shrinkage during polymerization. Additionally, compounds containing epoxy groups among cyclic ether groups are readily available in a variety of structures, do not adversely affect the durability of the resulting hard coat layer, and have the advantage of easily controlling compatibility with radical polymerizable compounds. Moreover, among cyclic ether groups, oxetanyl groups have a higher degree of polymerization and lower toxicity compared to epoxy groups. When the resulting hard coat layer is combined with a compound containing epoxy groups, it accelerates the network formation rate from the cationic polymerizable compound in the coating film, and has advantages such as forming an independent network without leaving unreacted monomers in the film even in regions where it is mixed with radical polymerizable compounds.

Examples of cationic polymerizable compounds containing epoxy groups include, for example, alicyclic epoxy resins obtained by epoxidizing polyglycidyl ethers of polyhydric alcohols having alicyclic rings, or compounds containing cyclohexene rings or cyclopentene rings, with a suitable oxidizing agent such as hydrogen peroxide or peracid; aliphatic epoxy resins such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polybasic acids, and homopolymers and copolymers of glycidyl (meth)acrylates; glycidyl ethers produced by the reaction of bisphenols such as bisphenol A, bisphenol F, and hydrogenated bisphenol A, or derivatives thereof such as alkylene oxide adducts and caprolactone adducts, with epichlorohydrin, and novolac epoxy resins, as well as glycidyl ether-type epoxy resins derived from bisphenols.

Specific examples of alicyclic epoxy resins, glycidyl ether-type epoxy resins, and cationic polymerizable compounds having an oxetanyl group can be found, for example, those described in Japanese Patent Publication No. 2018-104682.

Furthermore, the cured product of the resin composition containing polymerizable compounds in the hard coat layer can be analyzed using a Fourier transform infrared spectrophotometer (FTIR), a gas chromatography-mass chromatograph (GC-MS), and, for the decomposition products of the polymer, a combination of high-performance liquid chromatography, gas chromatography-mass spectrometry, NMR, elemental analysis, XPS/ESCA, and TOF-SIMS.

(ii) Polymerization initiator The resin composition may contain a polymerization initiator as needed. Radical polymerization initiators, cationic polymerization initiators, radical and cationic polymerization initiators, etc., can be appropriately selected and used as polymerization initiators. These polymerization initiators are decomposed by at least one of light irradiation and heating, generating radicals or cations to promote radical polymerization and cationic polymerization. Note that in some cases, the polymerization initiator may not remain in the hard coat layer after all of it has been decomposed.

Specific examples of radical polymerization initiators and cationic polymerization initiators can be found, for example, in Japanese Patent Publication No. 2018-104682.

(iii) Particles The hard coat layer preferably contains inorganic or organic particles, and more preferably inorganic fine particles. The hardness can be improved by including particles in the hard coat layer.

Examples of inorganic particles include silica ( _SiO₂ ), aluminum oxide, zirconia, titania, zinc oxide, germanium oxide, indium oxide, tin oxide, indium tin oxide (ITO), antimony oxide, metal oxide particles such as 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, at least one selected from silica particles and aluminum oxide particles is more preferred, and silica particles are even more preferred because they provide excellent hardness.

Furthermore, it is preferable that the inorganic particles are reactive inorganic particles having photoreactive reactive functional groups on at least a portion of their surface that can crosslink with other inorganic particles or with at least one polymerizable compound to form covalent bonds. By crosslinking reactive inorganic particles with each other or with at least one radical polymerizable compound and at least one cationic polymerizable compound, the hardness of the hard coat layer can be further improved.

Reactive inorganic particles have at least a portion of their surface coated with an organic component, and possess reactive functional groups introduced by this organic component on their surface. For example, polymerizable unsaturated groups are preferably used as reactive functional groups, and more preferably, photocurable unsaturated groups. Examples of reactive functional groups include (meth)acryloyl groups, vinyl groups, allyl groups, and other ethylenically unsaturated bonds, as well as epoxy groups.

The reactive silica particles are not particularly limited and conventionally known particles can be used, such as the reactive silica particles described in Japanese Patent Application Publication No. 2008-165040. Commercially available reactive silica particles include, for example, MIBK-SD, MIBK-SDMS, MIBK-SDL, MIBK-SDZL from Nissan Chemical Industries, Ltd., and V8802, V8803 from JGC Catalysts & Chemicals Ltd.

Furthermore, while the silica particles may be spherical, irregularly shaped silica particles are preferred. Spherical and irregularly shaped silica particles may be mixed. In this specification, irregularly shaped silica particles refer to silica particles with a potato-like, randomly uneven surface. Because irregularly shaped silica particles have a larger surface area compared to spherical silica particles, including such irregularly shaped silica particles increases the contact area with the resin components, thereby improving the hardness of the hard coat layer.

Furthermore, whether or not the particles are irregularly shaped silica can be confirmed by cross-sectional observation of the hard coat layer using an electron microscope.

The average particle size of inorganic particles is preferably 5 nm or larger, and more preferably 10 nm or larger, from the viewpoint of improving hardness. If the average particle size of inorganic particles is too small, particle manufacturing becomes difficult, and there is a risk that the particles will aggregate easily. Furthermore, from the viewpoint of transparency, the average particle size of inorganic particles is preferably 200 nm or smaller, more preferably 100 nm or smaller, and even more preferably 50 nm or smaller. If the average particle size of inorganic particles is too large, there is a risk of large irregularities forming in the hard coat layer and a high haze.

Here, the average particle size of inorganic particles can be measured by cross-sectional observation of the hard coat layer using an electron microscope, and the average particle size is defined as the average of the particle sizes of 10 arbitrarily selected particles. The average particle size of irregularly shaped silica particles is the average of the maximum (major axis) and minimum (minor axis) distances between two points on the outer circumference of the irregularly shaped silica particle observed using a cross-sectional microscope of the hard coat layer.

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

(iv) UV absorber The hard coat layer may contain a UV absorber. This can suppress the degradation of the first resin layer by ultraviolet light. In particular, if the first resin layer contains polyimide, it can suppress the color change of the first resin layer containing polyimide over time. Furthermore, in a display device equipped with a glass laminate, it can suppress the degradation of components located on the display panel side of the glass laminate, such as polarizers, by ultraviolet light.

The UV absorber contained in the hard coat layer preferably has an absorption wavelength peak of 300 nm to 390 nm in absorbance measurements, more preferably 320 nm to 370 nm, and even more preferably 330 nm to 370 nm. Such a UV absorber can efficiently absorb UV light in the UVA region, and by shifting its peak wavelength from the 250 nm absorption wavelength of the initiator used to cure the hard coat layer, it is possible to form a hard coat layer with UV absorption capabilities without inhibiting the hard coat layer's curing.

Among UV absorbers, those with an absorption wavelength peak of 380 nm or less are preferable because they can suppress discoloration caused by the UV absorber.

The absorbance of the UV absorber can be measured using, for example, a UV-Vis-Near-Infrared spectrophotometer (e.g., JASCO Corporation V-7100).

The UV absorber can be the same as the UV absorber used in the first resin layer described above.

In particular, from the viewpoint of suppressing degradation of the first resin layer due to ultraviolet light, one or more ultraviolet absorbers selected from the group consisting of hydroxybenzophenone-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred, and one or more ultraviolet absorbers selected from the group consisting of hydroxybenzophenone-based ultraviolet absorbers are more preferred.

Specific examples of hydroxybenzophenone-based ultraviolet absorbers can be found, for example, in Japanese Patent Publication No. 2019-132930.

Among the hydroxybenzophenone-based UV absorbers, 2-hydroxybenzophenone-based UV absorbers are preferred, and more preferably one or more selected from the group consisting of benzophenone-based UV absorbers having the following general formula (A). This can suppress UV degradation of the first resin layer and improve its durability.

(In general formula (A), ^X1 and ^X2 each independently represent a hydroxyl group, -OR ^a , or a hydrocarbon group having 1 to 15 carbon atoms, and ^Ra represents a hydrocarbon group having 1 to 15 carbon atoms.)

In general formula (A), the hydrocarbon groups having 1 to 15 carbon atoms in ^X1 , ^X2 , and ^Ra include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, dodecyl, allyl, and benzyl groups. Aliphatic hydrocarbon groups having 3 or more carbon atoms may be linear or branched. The hydrocarbon groups preferably have 1 to 12 carbon atoms, and more preferably 1 to 8. From the viewpoint of improving transparency, the hydrocarbon groups are preferably aliphatic hydrocarbon groups, and among them, methyl and allyl groups are preferred.

From the standpoint of improving durability, it is preferable that ^X1 and ^X2 are each independently a hydroxyl group or ^-ORa .

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

Specific examples of benzotriazole-based ultraviolet absorbers can be found, for example, in Japanese Patent Publication No. 2019-132930.

Among the benzotriazole-based UV absorbers, 2-(2-hydroxyphenyl)benzotriazoles are preferred, and more preferably, one or more selected from the group consisting of benzotriazole-based UV absorbers having the following general formula (B). This can suppress UV degradation of the first resin layer and improve its durability.

(In general formula (B), ^Y1 , ^Y2 , and ^Y3 each independently represent a hydrogen atom, a hydroxyl group, -OR ^b , or a hydrocarbon group having 1 to 15 carbon atoms; R ^b represents a hydrocarbon group having 1 to 15 carbon atoms; and at least one of ^Y1 , ^Y2 , and ^Y3 represents a hydroxyl group, -OR ^b , or a hydrocarbon group having 1 to 15 carbon atoms. ^Y4 represents a hydrogen atom or a halogen atom.)

In general formula (B), the hydrocarbon groups having 1 to 15 carbon atoms in ^Y1 , ^Y2 , ^Y3 , and ^Rb include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and dodecyl groups. Aliphatic hydrocarbon groups having 3 or more carbon atoms may be linear or branched. The hydrocarbon groups preferably have 1 to 12 carbon atoms, and more preferably 1 to 8. From the viewpoint of improving transparency, the hydrocarbon groups are preferably aliphatic hydrocarbon groups, preferably linear or branched alkyl groups, and among these, methyl, t-butyl, t-pentyl, n-octyl, or t-octyl groups are preferred.

In general formula (B), examples of halogen atoms in Y ⁴ include chlorine atoms, fluorine atoms, bromine atoms, etc., with chlorine atoms being preferred.

In general formula (B), it is preferable that ^Y1 and ^Y3 are hydrogen atoms, and ^Y2 represents a hydroxyl group or -OR ^b , and more preferably one or more selected from the group consisting of 2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole and 2-(2,4-dihydroxyphenyl)-2H-benzotriazole. This suppresses degradation of the first resin layer due to ultraviolet light and improves durability.

The amount of UV absorber in the hard coat layer is preferably 10% by mass or less, and more preferably 7% by mass or less, from the viewpoint of suppressing haze caused by the mixing of UV absorbers. Furthermore, from the viewpoint of suppressing UV degradation of the first resin layer and improving its durability, the amount of UV absorber in the hard coat layer is preferably 1% by mass or more and 6% by mass or less, and more preferably 2% by mass or more and 5% by mass or less.

(v) Antifouling agent The hard coat layer may contain an antifouling agent. This can impart antifouling properties to the glass laminate.

The antifouling agent is not particularly limited; examples include silicone-based antifouling agents, fluorine-based antifouling agents, and silicone-based and fluorine-based antifouling agents. The antifouling agent may also be an acrylic-based antifouling agent. The antifouling agent may be used individually or in mixtures of two or more types.

Hard coat layers containing silicone-based or fluorine-based antifouling agents are less prone to fingerprints (less noticeable) and have good wipeability. Furthermore, the inclusion of silicone-based or fluorine-based antifouling agents can lower the surface tension of the curable resin composition for the hard coat layer during application, resulting in good leveling properties and a superior appearance for the resulting hard coat layer.

Furthermore, the hard coat layer containing a silicone-based antifouling agent exhibits good slipperiness and scratch resistance. In a display device equipped with a glass laminate having such a hard coat layer containing a silicone-based antifouling agent, the tactile feel is improved because it becomes smoother when touched with fingers or pens.

To enhance the durability of its antifouling performance, the antifouling agent preferably has reactive functional groups. If the antifouling agent does not have reactive functional groups, regardless of whether the glass laminate is in roll or sheet form, when the glass laminates are stacked, the antifouling agent may transfer to the side of the glass laminate opposite the hard coat layer. This could cause other layers to peel off when other layers are applied or coated to the side opposite the hard coat layer, and furthermore, repeated bending may make other layers more prone to peeling. In contrast, if the antifouling agent has reactive functional groups, the durability of its antifouling performance is improved.

The number of reactive functional groups in the antifouling agent may be one or more, 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 coat layer.

Furthermore, the antifouling agent preferably has a weight-average molecular weight of 5000 or less. The weight-average molecular weight of the antifouling agent can be measured by gel permeation chromatography (GPC).

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

Methods for unevenly distributing the antifouling agent to the surface side of the hard coat layer include, for example, a method in which, during the formation of the hard coat layer, the coating film of the curable resin composition for the hard coat layer is heated before drying and curing to lower the viscosity of the resin components contained in the coating film, thereby increasing its fluidity and unevenly distributing the antifouling agent to the surface side of the hard coat layer; or a method in which an antifouling agent with low surface tension is used, and the antifouling agent is allowed to float on the surface of the coating film without applying heat during drying, and then the coating film is cured, thereby unevenly distributing the antifouling agent to the surface side of the hard coat layer.

The amount of the antifouling agent is preferably 0.01 parts by mass or more and 3.0 parts by mass or less per 100 parts by mass of the resin component. If the amount of antifouling agent is too low, sufficient antifouling properties may not be imparted to the hard coat layer, and if the amount is too high, the hardness of the hard coat layer may decrease.

(vi) Other additives The hard coat layer may further contain additives as needed. Additives are selected appropriately according to the function to be imparted to the hard coat layer and are not particularly limited, but examples include inorganic or organic particles for adjusting the refractive index, infrared absorbers, anti-glare agents, anti-fouling agents, antistatic agents, colorants such as blue or purple dyes, leveling agents, surfactants, lubricants, various sensitizers, flame retardants, adhesion promoters, polymerization inhibitors, antioxidants, light stabilizers, surface modifiers, etc.

(d) Thickness of the hard coat layer The thickness of the hard coat layer can be appropriately selected depending on the material of the hard coat layer, the function of the hard coat layer, and the application of the glass laminate. For example, if the material of the hard coat layer is an organic material, the thickness of the hard coat layer is preferably 2 μm or more and 50 μm or less, more preferably 3 μm or more and 30 μm or less, even more preferably 5 μm or more and 20 μm or less, and particularly preferably 6 μm or more and 10 μm or less. Also, if the material of the hard coat layer is an inorganic material, for example, the thickness of the hard coat layer can be about several tens of nanometers. If the thickness of the hard coat layer is within the above range, sufficient hardness can be obtained as a hard coat layer, and a glass laminate with good flexibility can be obtained.

(e) Method for forming the hard coat layer The method for forming the hard coat layer may be appropriately applied depending on the material of the hard coat layer, etc. For example, a method may be applied to the first resin layer and cured by coating it with a curable resin composition for a hard coat layer containing the polymerizable compound, etc., or by vapor deposition, sputtering, etc.

The hard coat layer curable resin composition contains a polymerizable compound and may further contain polymerization initiators, particles, UV absorbers, solvents, additives, etc., as needed.

The method for applying the curable resin composition for the hard coat layer onto the first resin layer is not particularly limited as long as it can be applied to the desired thickness. Examples of common application methods include gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, spray coating, die coating, and screen printing. Furthermore, a transfer method can also be used to form the coating film of the hard coat layer resin composition.

The coating film of the curable resin composition for the hard coat layer is dried as needed to remove the solvent. Drying methods include, for example, vacuum drying, heat drying, or a combination of these methods. For example, drying can be achieved by heating at a temperature of 30°C to 120°C for 10 to 180 seconds.

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

For light irradiation, ultraviolet light, visible light, electron beams, and ionizing radiation are mainly used. In the case of ultraviolet curing, for example, ultraviolet light emitted from light 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 of the energy source can be, for example, an integrated exposure dose at an ultraviolet wavelength of 365 nm of approximately 50 mJ/ ^cm² to 5000 mJ/ ^cm² .

When heating is required, the reaction can be carried out at a temperature of, for example, 40°C to 120°C. Alternatively, the reaction can be carried out by leaving the mixture at room temperature (25°C) for 24 hours or more.

Furthermore, as a method for forming the hard coat layer, a hard coat film in which the hard coat layer is arranged on one side of the base layer can be used, and the hard coat film can be bonded to the first resin layer via an adhesive layer. In this case, for example, as shown in Figure 9, the adhesive layer 7 and the hard coat film 15 having the base layer 11 and the hard coat layer 5 can be arranged in this order on the side of the first resin layer 3 opposite to the glass base material 2.

The adhesive layer is transparent. Specifically, the total light transmittance of the adhesive layer is preferably 85% or higher, more preferably 88% or higher, and even more preferably 90% or higher. The upper limit is 100%.

Examples of adhesives used in the bonding layer include OCA (Optical Clear Adhesive) and photosensitive adhesives.

The thickness of the adhesive layer is preferably, for example, 1 μm to 100 μm. If the adhesive layer is too thick, the flexibility may be compromised. On the other hand, if the adhesive layer is too thin, the adhesion may not be guaranteed, and the adhesive may peel off.

(2) Protective layer The glass laminate in this disclosure may further have a protective layer on the side of the first resin layer opposite to the glass substrate.

The protective layer is transparent. Specifically, the total light transmittance of the protective layer is preferably 85% or higher, more preferably 88% or higher, and even more preferably 90% or higher. The upper limit is 100%.

The protective layer is not particularly limited as long as it is transparent, and may include, for example, a resin. The resin used for the protective layer is not particularly limited as long as it can produce a transparent protective layer; general-purpose resins can be used.

Methods for applying a protective layer to the main surface of a glass substrate include, for example, using a protective film as the protective layer and bonding the first resin layer and the protective film via an adhesive layer, or forming the protective layer on the first resin layer.

The adhesive layer can be the same as the adhesive layer described in the section on the hard coat layer above.

5. Other Compositions The glass laminate in this disclosure may have other layers in addition to the above-described layers, as necessary. Examples of other layers include a primer layer, a third resin layer, a decorative layer, and so on.

(1) Primer layer The glass laminate in this disclosure may have a primer layer 8 between the glass substrate 2 and the first resin layer 3, for example, as shown in Figures 9 to 11. Also, if the glass laminate in this disclosure has a third resin layer on the side of the glass substrate opposite to the first resin layer, as will be described later, a primer layer may be provided between the glass substrate and the third resin layer. The primer layer can improve the adhesion between the glass substrate and the first resin layer and the third resin layer.

The material for the primer layer is not particularly limited as long as it can improve the adhesion between the glass substrate and the first or third resin layer. Examples of resins include (meth)acrylic resin, urethane resin, (meth)acrylic urethane copolymer, vinyl chloride-vinyl acetate copolymer, polyester, butyral resin, chlorinated polypropylene, chlorinated polyethylene, epoxy resin, and silicone resin. These resins may be used individually or in combination of two or more.

Furthermore, the primer layer composition used for forming the primer layer may contain, for example, a silane coupling agent such as an alkoxysilane compound.

The thickness of the primer layer should be sufficient to enhance the adhesion between the glass substrate and the first or third resin layer. For example, it can be 0.1 μm or more and 10 μm or less, preferably 0.2 μm or more and 5 μm or less.

One method for forming the primer layer is to apply a primer layer composition onto a glass substrate. Examples of application methods include gravure coating, gravure reverse coating, gravure offset coating, spin coating, roll coating, reverse roll coating, blade coating, dip coating, and screen printing. Transfer methods can also be used to form the primer layer.

(2) Third resin layer The glass laminate in this disclosure may have a third resin layer 6 on the side of the glass substrate 2 opposite to the first resin layer 3, i.e., on the second side, as shown in Figure 12, for example. When an impact is applied to the glass laminate, the impact is absorbed not only by the first resin layer but also by the third resin layer, which can suppress cracking of the glass substrate and improve impact resistance.

The properties and materials of the third resin layer can be the same as those of the first resin layer described above, so a detailed explanation is omitted here.

The thickness of the third resin layer should be sufficient to absorb impact. For example, it is preferably 5 μm to 100 μm, more preferably 10 μm to 75 μm, and even more preferably 15 μm to 50 μm.

The method for forming the third resin layer can be the same as the method for forming the first resin layer described above.

(3) Decorative layer The glass laminate in this disclosure may have a decorative layer between the glass substrate and the first resin layer, or on the side of the glass substrate opposite to the first resin layer.

The decorative layer contains a coloring agent and a binder resin. The binder resin included in the decorative layer is not particularly limited; any resin commonly used in decorative layers can be used. Furthermore, the coloring agent included in the decorative layer is not particularly limited; any known coloring agent commonly used in decorative layers can be used.

The decorative layer is typically placed on a portion of the glass substrate. The decorative layer may also have a patterned shape.

The thickness of the decorative layer is not particularly limited, but for example, it can be between 5 μm and 40 μm.

6. Characteristics of the Glass Laminate The glass laminate in this disclosure preferably has a total light transmittance of, for example, 82% or more, more preferably 85% or more, and even more preferably 88% or more. The upper limit is 100%. By having such a high total light transmittance, a glass laminate with good transparency can be obtained.

Here, the total light transmittance of the glass laminate can be measured in accordance with JIS K7361-1, for example, using a haze meter HM150 manufactured by Murakami Color Technology Laboratory.

The haze of the glass laminate in this disclosure is preferably 1.0% or less, more preferably 0.8% or less, and even more preferably 0.5% or less. Such low haze allows for a glass laminate with good transparency. The lower limit of the haze is 0%.

Here, the haze of the glass laminate can be measured in accordance with JIS K-7136, for example, using a haze meter HM150 manufactured by Murakami Color Technology Laboratory.

The glass laminate in this disclosure preferably has flexibility. Specifically, in a bending test using the cylindrical mandrel method, the minimum diameter of the mandrel at which a crack occurs in the glass laminate is preferably 10 mm or less, and more preferably 5 mm or less. If the minimum diameter of the mandrel is within this range, the flexibility can be further improved. The bending test using the cylindrical mandrel method will be described in detail in the examples below, so a detailed explanation is omitted here.

Furthermore, in the glass laminate described in this disclosure, it is preferable that no cracks or fractures occur in the glass laminate when the dynamic bending test described below is repeated 200,000 times.

In dynamic bending tests, the glass laminate may be folded so that the glass substrate faces outward, or so that the glass substrate faces inward. In either case, it is preferable that no cracks or fractures occur in the glass laminate.

The dynamic bending test is performed as follows. As shown in Figure 13(a), in the dynamic bending test, first, the short side portion 1C and the short side portion 1D opposite to the short side portion 1C of the 20 mm x 100 mm glass laminate 1 are fixed together with parallel fixing portions 21.

Furthermore, as shown in Figure 13(a), the fixing part 21 is slidable horizontally. Next, as shown in Figure 13(b), the fixing parts 21 are moved closer to each other to deform the glass laminate 1 into a folding shape. Then, as shown in Figure 13(c), the fixing parts 21 are moved to a position where the distance d between the two opposing short sides 1C and 1D fixed by the fixing parts 21 of the glass laminate 1 is a predetermined value. After that, the fixing parts 21 are moved in the opposite direction to release the deformation of the glass laminate 1. As shown in Figures 13(a) to (c), the glass laminate 1 can be folded 180° by moving the fixing parts 21. In addition, by performing a dynamic bending test so that the bent part 1E of the glass laminate 1 does not protrude from the lower end of the fixing part 21, and by controlling the distance d when the fixing parts 21 are closest together, the distance d between the two opposing short sides 1C and 1D of the glass laminate 1 can be set to a predetermined value. For example, if the distance d between two opposing short sides 1C and 1D is 10 mm, then the outer diameter of the bent section 1E is considered to be 10 mm.

In a glass laminate, it is preferable that no cracks or fractures occur when a test is repeatedly performed 200,000 times in which the glass laminate 1 is folded 180° so that the distance d between opposing short sides 1C and 1D is 8 mm.

Furthermore, in the glass laminate described in this disclosure, when the static bending test described below is performed on the glass laminate, it is preferable that the opening angle θ after the static bending test is 100° or more, and more preferably 130° or more.

The static bending test is performed as follows. First, as shown in Figure 14(a), the short side portion 1C of the glass laminate 1 and the short side portion 1D opposite to short side portion 1C are fixed with fixing portions 22 that are arranged parallel to each other so that the distance d between short side portions 1C and 1D is 10 mm. Then, a static bending test is performed by leaving the glass laminate 1 in a folded state at 23°C for 240 hours. After that, as shown in Figure 14(b), the folding state is released by removing the fixing portion 22 from the short side portion 1D after the static bending test, and the opening angle θ, which is the angle at which the glass laminate 1 naturally opens after 30 minutes at room temperature, is measured. Note that a larger opening angle θ indicates better resilience, with a maximum of 180°.

In static bending tests, the glass laminate may be folded so that the glass substrate faces inward, or so that the glass substrate faces outward. In either case, the opening angle θ is preferably 100° or greater, and more preferably 130° or greater.

7. Applications of the Glass Laminate The glass laminate in this disclosure can be used in a display device as a component positioned on the observer side of the display panel. The glass laminate in this disclosure can be used in display devices used in electronic devices such as smartphones, tablet terminals, wearable devices, personal computers, televisions, digital signage, public information displays (PIDs), and in-vehicle displays. In particular, the glass laminate in this disclosure can be preferably used in flexible displays such as foldable displays, rollable displays, and bendable displays, and is more preferably used in foldable displays.

When the glass laminate in this disclosure is placed on the surface of a display device, the side facing the glass substrate faces the display panel, and the side facing the first resin layer faces outwards.

The method for arranging the glass laminate on the surface of a display device in this disclosure is not particularly limited and includes, for example, a method using an adhesive layer. As the adhesive layer, a known adhesive layer used for bonding glass laminates can be used.

B. Display Device The display device in this disclosure comprises a display panel and the aforementioned glass laminate disposed on the observer side of the display panel.

Figure 15 is a schematic cross-sectional view showing an example of a display device in this disclosure. As shown in Figure 15, the display device 30 comprises a display panel 31 and a glass laminate 1 positioned on the observer side of the display panel 31. In the display device 30, the glass laminate 1 is used as a component positioned on the surface of the display device 30, and an adhesive layer 32 is positioned between the glass laminate 1 and the display panel 31.

The glass laminate in this disclosure may be the same as the glass laminate described above.

Examples of display panels used in display devices such as liquid crystal displays, organic EL displays, and LED displays can be cited in this disclosure.

The display device in this disclosure may have a touch panel member between the display panel and the glass laminate.

The display device in this disclosure is preferably a flexible display. In particular, the display device in this disclosure is preferably foldable. That is, the display device in this disclosure is more preferably a foldable display. Because the display device in this disclosure has the aforementioned glass laminate, it has excellent impact resistance and bending resistance, making it suitable as a flexible display, and even more so as a foldable display.

C. Electronic Devices The electronic devices in this disclosure include the display devices described above.

The electronic devices described in this disclosure are not particularly limited as long as they are equipped with the display devices described above, and include, for example, smartphones, tablet devices, wearable devices, personal computers, televisions, digital signage, public information displays (PIDs), in-vehicle displays, and the like.

D. Resin layer The resin layer in this disclosure is a resin layer that is disposed on the main surface side of a glass substrate having a thickness of 100 μm or less and is used to cover the side surface of the glass substrate, and is transparent.

When the resin layer in this disclosure is placed on the main surface side of a glass substrate having a predetermined thickness and used to cover the side surface of the glass substrate, good flexibility and impact resistance can be obtained, as described in section A. Glass Laminate above.

The resin layers in this disclosure can be configured in the same way as in the above-described glass laminate, where the first and second resin layers contain the same material and are integrated, where the second and third resin layers contain the same material and are integrated, and where the second resin layer and the functional layer contain the same material and are integrated. Among these, it is preferable that the resin layers in the above-described glass laminate consist of the first and second resin layers containing the same material and being integrated.

One method for arranging the resin layer so as to be placed on the main surface of the glass substrate and covering the sides of the glass substrate is to bond a film-like resin layer to the main surface and sides of the glass substrate via an adhesive layer.

This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure.

The following examples and comparative examples further illustrate this disclosure.

[Comparative Example 1]
(Glass substrate)
A chemically strengthened glass substrate with a thickness of 70 μm was used. The edges of this glass substrate were processed, and the shape of the edges of the glass substrate was as shown in Figure 2(a).

[Comparative Example 2]
(Formation of the resin layer)
Using the same glass substrate as in Comparative Example 1, a resin composition containing a urethane-modified copolymer polyester resin (Byron UR-4800, manufactured by Toyobo Co., Ltd.) was deposited on the main surface of the glass substrate to a predetermined thickness to form a resin layer. The drying conditions during resin layer formation were 100°C for 3 minutes. In addition, when forming the resin layer, a film slightly larger than the glass substrate was laminated to the second surface of the glass substrate, opposite to the main surface (first surface) on which the resin layer was to be formed. Then, with the glass substrate side facing upwards, it was attached to a carrier glass with a thickness of 0.7 mm, and the resin composition was applied by die coating. At that time, a nozzle with a nozzle width smaller than the width of the glass substrate was used in the die coater to prevent the resin composition from being applied to the sides of the glass substrate.

[Example 1]
(Formation of resin layer)
In Comparative Example 2, a resin layer was formed on the main surface and side surfaces of the glass substrate in the same manner as in Comparative Example 2, except that when forming the resin layer, a nozzle with a nozzle width greater than the width of the glass substrate was used in the die coater to apply the resin composition to the main surface and side surfaces of the glass substrate.

[Comparative Example 3]
(Glass substrate)
A chemically strengthened glass substrate with a thickness of 70 μm was used. The edges of this glass substrate were unprocessed, and the shape of the edges of the glass substrate was as shown in Figure 2(b).

[Comparative Example 4]
(Formation of resin layer)
A resin layer was formed on the main surface of the glass substrate in the same manner as in Comparative Example 2, except that the thickness of the resin layer was changed, using the same glass substrate as in Comparative Example 3.

[Comparative Example 5]
(Formation of the primer layer)
Using the same glass substrate as in Comparative Example 1, the following primer layer composition was coated onto the glass substrate and dried at 80°C for 3 minutes and at 150°C for 60 minutes to form a primer layer with a thickness of 1 μm.

<Composition for primer layer>
- Bisphenol A type solid epoxy resin (jER1256B40, manufactured by Mitsubishi Chemical Corporation) 28 parts by mass - Bisphenol A novolac type solid epoxy resin (jER157S65B80, manufactured by Mitsubishi Chemical Corporation) 5 parts by mass - 2-ethyl-4-methylimidazole (manufactured by Tokyo Chemical Industry Co., Ltd.) 1 part by mass - Solvent (MEK) 11 parts by mass

(Formation of resin layer)
Referring to Synthesis Example 1 in International Publication No. 2014/046180, a tetracarboxylic dianhydride represented by the following chemical formula was synthesized.

In a 5 L separable flask, a solution containing dehydrated N,N-dimethylacetamide (DMAc) (1833.2 g) and 2,2'-bis(trifluoromethyl)benzidine (TFMB) (138.48 g) was added. The solution temperature was controlled to 30°C. Then, tetracarboxylic dianhydride (TMPBPTME) (176.70 g), represented by the above chemical formula, was gradually added, ensuring the temperature rise was 2°C or less. The mixture was stirred with a mechanical stirrer for 30 minutes. Pyromellitic dianhydride (PMDA) (64.20 g) was then gradually added in several batches, ensuring the temperature rise was 2°C or less, to synthesize a polyimide precursor solution (18% solids by mass) in which the polyimide precursor was dissolved. The molar ratio (TMBPPTME:PMDA) of the tetracarboxylic dianhydrides used in the polyimide precursor was 90:10. The weight-average molecular weight of the polyimide precursor was 75,000.

Under a nitrogen atmosphere, 2162 g of the polyimide precursor solution (at room temperature) was added to a 5 L separable flask. Then, 432 g of dehydrated N,N-dimethylacetamide was added and the mixture was stirred until homogeneous. Next, pyridine (6.622 g) and acetic anhydride (213.67 g), which serve as catalysts, were added, and the mixture was stirred at room temperature for 24 hours to synthesize the polyimide solution.

To the obtained polyimide solution, N,N-dimethylacetamide (DMAc) (2000 g) was added and stirred until homogeneous. Next, the polyimide solution was divided into three equal parts and transferred to 5 L beakers. Isopropyl alcohol (3500 g) was gradually added to each beaker to obtain a white slurry. The slurry was transferred to a Buchner funnel and filtered. This was followed by washing with isopropyl alcohol (total 9000 g), and filtration. This process was repeated three times. The mixture was then dried at 110°C using a vacuum dryer to obtain polyimide (polyimide powder). The weight-average molecular weight of the polyimide, measured by GPC, was 100,000.

A polyimide varnish (resin composition) containing 12% polyimide by mass was prepared by adding N,N-dimethylacetamide (DMAc) to polyimide so that the solid content concentration of polyimide was 12% by mass. The viscosity of the polyimide varnish (resin composition) (solid content concentration 12% by mass) at 25°C was 15,000 cps.

The polyimide varnish (resin composition) was applied to the primer layer to a predetermined thickness and dried at 80°C for 5 minutes, 150°C for 10 minutes, and 230°C for 30 minutes to form a resin layer of the predetermined thickness. For the formation of the resin layer, a film slightly larger than the glass substrate was bonded to the second surface of the glass substrate, opposite to the main surface (first surface) where the resin layer would be formed. Then, with the glass substrate side facing upwards, it was attached to a 0.7 mm thick carrier glass, and the resin composition was applied by die coating. During this process, a nozzle with a width smaller than the width of the glass substrate was used in the die coater to prevent the resin composition from being applied to the sides of the glass substrate.

[Example 2]
(Formation of resin layer)
In Comparative Example 5, a resin layer was formed on the main surface and side surfaces of the glass substrate in the same manner as in Comparative Example 5, except that when forming the resin layer, a nozzle with a nozzle width greater than the width of the glass substrate was used in the die coater to apply the resin composition to the main surface and side surfaces of the glass substrate.

[Example 3]
(Formation of resin layer)
In Example 2, a resin layer was formed on the main surface and side surfaces of a glass substrate in the same manner as in Example 2, except that the resin composition was applied by a spin coating method and the thickness of the resin layer was changed.

[Example 4]
(Formation of resin layer)
In Example 3, a resin layer was formed on the main surface and side surface of the glass substrate in the same manner as in Example 3, except that the thickness of the resin layer was changed.

[Example 5]
A resin layer was formed on the main surface and side surfaces of a glass substrate in the same manner as in Example 4, except that a chemically strengthened glass substrate having the surface compressive stress (CS) values shown in Table 1 below was used.

[Example 6]
In Example 5, a resin layer was formed on the main surface and side surface of the glass substrate in the same manner as in Example 5, except that the thickness of the second resin layer was changed.

[Example 7]
In Example 5, a resin layer was formed on the main surface and side surface of the glass substrate in the same manner as in Example 5, except that the thickness of the second resin layer was changed.

[evaluation]
(1) Flexion test (mandrel test)
Flexural tests were performed on the glass laminates of Examples 1-5 and Comparative Examples 2, 4, and 5, as well as the glass substrates of Comparative Examples 1 and 3. Following the cylindrical mandrel method described in JIS-K5600-5-1, sample pieces (100 mm x 50 mm) were wrapped around mandrels with diameters ranging from 2 mm to 32 mm to evaluate the flexural resistance of the glass laminates or glass substrates.
In this test, the glass laminate was wrapped around a mandrel with the first resin layer on the inside and the glass substrate on the outside. Table 1 shows the smallest diameter of the mandrel in which cracks occurred in the glass laminate or glass substrate. A smaller value indicates higher bending resistance. The results of the bending test were evaluated according to the following criteria.
A: The minimum diameter of the mandrel in which a crack has occurred in the glass laminate or glass substrate is 5 mm or less.
B: The minimum diameter of the mandrel in which a crack has occurred in the glass laminate or glass substrate is 6 mm or more and 10 mm or less.
C: The minimum diameter of the mandrel in which a crack has occurred in the glass laminate or glass substrate is 12 mm or larger.

(2) Impact test (pen drop test)
Impact tests were performed on the glass laminates of Examples 1-5 and Comparative Examples 2, 4, and 5, as well as the glass substrates of Comparative Examples 1 and 3. First, a test laminate was prepared by bonding a 50 μm thick optical adhesive film (OCA) and a 100 μm thick PET film in that order to the surface of the glass substrate of the glass laminate or to the glass substrate. The test laminate was placed on a metal plate so that the PET film side of the test laminate was in contact with the metal plate, which was 30 mm thick. Next, a pen was dropped onto the test laminate from a test height, tip-down, at the center and at the edges of the test laminate. Here, the edges of the test laminate refer to the area within 5 mm from the edge of the glass substrate. The center of the test laminate refers to the area other than the edges of the test laminate.
The pen used was a Zebra Blenn 0.5 BAS88-BK (weight 12g, pen tip 0.5mmφ). Table 1 shows the maximum test height at which no crack occurred in the glass substrate. A higher value indicates higher impact resistance. The impact test results were evaluated according to the following criteria.
A: The maximum test height at which no cracks occurred in the glass substrate was 12 cm or more.
B: The maximum test height at which no cracks occurred in the glass substrate was between 8 cm and 12 cm.
C: The maximum test height at which no cracks occurred in the glass substrate was less than 8 cm.

(3) Total light transmittance and haze The total light transmittance and haze were measured for the glass laminates of Examples 1 to 5. The total light transmittance was measured using a haze meter (HM150, manufactured by Murakami Color Technology Laboratory) in accordance with JIS K7361-1. The haze was measured using a haze meter (HM150, manufactured by Murakami Color Technology Laboratory) in accordance with JIS K-7136.

(4) Surface compressive stress (CS) of chemically strengthened glass
For the glass substrates in Examples 1 to 5 and Comparative Examples 1 to 5, the surface compressive stress values were measured using a refractometer-type glass surface stress meter FSM-6000LE manufactured by Lukeo.

In Table 1, the resin layer formed on the main surface of the glass substrate is referred to as the first resin layer, and the resin layer formed on the side surface of the glass substrate is referred to as the second resin layer. Furthermore, the thickness T2 of the second resin layer is the thickness of the second resin layer in the direction parallel to the main surface of the glass substrate, and the thickness T4 of the second resin layer is the thickness of the second resin layer in the thickness direction of the glass substrate. The coverage ratio is defined as the ratio of T1/T2 on the four sides of the glass substrate, where the sum of the lengths of the four sides when viewed from above is considered 100%, and the ratio is between 0.01 and 5.0.

Comparative Examples 1 and 2 showed that when the first resin layer was positioned on the main surface of the glass substrate, but the sides of the glass substrate were not covered with the second resin layer (Comparative Example 2), impact resistance was good, but flexural resistance was worse than that of the glass substrate alone (Comparative Example 1). Similarly, Comparative Examples 3 and 4 showed that when the first resin layer was positioned on the main surface of the glass substrate, but the sides of the glass substrate were not covered with the second resin layer (Comparative Example 4), impact resistance was good, but flexural resistance was worse than that of the glass substrate alone (Comparative Example 3). Furthermore, in Comparative Example 5, although the first resin layer was positioned on the main surface of the glass substrate, the sides of the glass substrate were not covered with the second resin layer, resulting in good impact resistance but poor flexural resistance.

In contrast, in Examples 1 to 4, the first resin layer was arranged on the main surface side of the glass substrate, and the side surfaces of the glass substrate were covered with the second resin layer, resulting in excellent bending resistance and impact resistance.

1… Glass laminate 2… Glass substrate 2P… Main surface of glass substrate 2S… Side surface of glass substrate 3… First resin layer 4… Second resin layer 5… Hard coat layer 6… Third resin layer 8… Primer layer 30… Display device 31… Display panel

Claims (12)

A glass laminate comprising a glass substrate, a first resin layer, and a second resin layer,
The glass substrate has one main surface, another main surface opposite to the first main surface, and a side surface.
The thickness of the glass substrate is 100 μm or less.
The first resin layer is present on one of the main surfaces and is transparent.
The second resin layer covers the side surface,
The composite modulus of the first resin layer is 5.7 GPa or more and 40 GPa or less .
The first resin layer has a functional layer on the side opposite to the glass substrate,
The second resin layer and the functional layer contain the same material and are integrally formed.
A glass laminate in which the functional layer is a hard coat layer, and the hard coat layer contains a cured product of a resin composition containing a polymerizable compound . The glass laminate according to claim 1 , wherein the thickness of the first resin layer is T1 and the thickness of the second resin layer is T2, and the equation (formula 1) is satisfied.
(Formula 1) 0.01≦T1/T2≦5.0 The glass laminate according to claim 1 or claim 2 , wherein the ratio of the thickness of the second resin layer in the thickness direction of the glass substrate to the thickness of the glass substrate is 0.5 or more. The glass laminate according to any one of claims 1 to 3 , wherein the first resin layer contains at least one selected from the group consisting of polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin. The glass laminate according to any one of claims 1 to 4 , wherein a primer layer is provided between the glass substrate and the first resin layer. The glass laminate according to any one of claims 1 to 5 , wherein the glass substrate has a third resin layer on the side opposite to the first resin layer. The glass laminate according to claim 6 , wherein the third resin layer contains at least one selected from the group consisting of polyurethane, polyester, polyimide resin, epoxy resin, and acrylic resin. The glass laminate according to any one of claims 1 to 7 , wherein the glass substrate is chemically strengthened glass. The glass laminate according to any one of claims 1 to 8 , wherein the total light transmittance of the first resin layer is 82% or more and the haze is 1.0% or less. A glass laminate according to any one of claims 1 to 9 , wherein the total light transmittance is 82% or more and the haze is 1.0% or less. Display panel and,
The glass laminate according to any one of claims 1 to 10 is positioned on the observer side of the display panel,
A display device equipped with the following features. An electronic device comprising the display device described in claim 11 .