Laminate and electronic device

Abstract

The purpose of the present invention is to provide a laminate that exhibits an excellent shock resistance and an excellent resistance to surface scratching, and to provide an electronic device that uses this laminate. The present invention has: a thin glass sheet having a thickness of not more than 200 µm; a first resin layer that has a thickness of at least 5 µm and that is disposed on one side of the thin glass sheet; and a second resin layer that has a thickness of at least 5 µm and that is disposed on the opposite side from the side of the first resin layer on the thin glass sheet. The first resin layer has a storage modulus at 25°C larger than 2,500 MPa, and the second resin layer has a breaking energy of at least 1 mJ / mm3 and a storage modulus at 25°C of not more than 2,500 MPa.

Description

Laminate and electronic device

[0001] The present invention relates to a laminate having excellent impact resistance and surface scratch resistance, and also to an electronic device using the laminate.

[0002] In recent years, development has been underway to make the display screens of electronic devices such as smartphones, e-books, tablet PCs, etc. foldable. The use of flexible thin glass on the outermost surface side of such foldable display screens has been considered.

[0003] Since thin glass is easily broken by impact, it has been considered to dispose a protective resin layer on one side of the thin glass. For example, Patent Document 1 discloses a protective substrate for a display device that includes glass and a resin layer on one side of the glass, in which the thickness of the glass is 20 μm to 200 μm and the specific gravity of the resin layer is 0.9 g / cm ３ ~1.5g / cm ３ and the resin layer has a flexural modulus of elasticity of 1000 MPa to 8000 MPa at 25° C. Furthermore, Patent Document 2 discloses a protective substrate for a display device, which comprises a thin glass having a thickness of 120 μm or less and an impact absorbing layer having a thickness of 5 μm or more arranged on one side of the thin glass, and the impact absorbing layer has a flexural modulus of elasticity of 1000 MPa to 8000 MPa at 25° C. １ ~10 １５ An optical laminate having a maximum value of tan δ in the range of 100 Hz has been described. However, when a conventional resin composition is used to form a protective resin layer, the impact resistance is insufficient, and therefore, further improvement in impact resistance has been desired.

[0004] Furthermore, there is a demand for preventing scratches on the surface of thin glass sheets that are placed on the outermost surface of the display screen of electronic devices.

[0005] JP 2013-37207 A International Publication No. 2018 / 190208

[0006] An object of the present invention is to provide a laminate having excellent impact resistance and surface scratch resistance, and an electronic device using the laminate.

[0007] Disclosure 1 provides a thin glass sheet having a thickness of 200 μm or less, a first resin layer having a thickness of 5 μm or more and disposed on one side of the thin glass sheet, and a second resin layer having a thickness of 5 μm or more and disposed on the side of the thin glass sheet opposite to the first resin layer side, wherein the first resin layer has a storage modulus at 25° C. of greater than 2500 MPa, and the second resin layer has a fracture energy of 1 mJ / mm ３ The laminate (first laminate of the present invention) is a laminate in which the second resin layer has a Young's modulus of 50 MPa or more and a storage modulus of 2500 MPa or less at 25° C. The present disclosure 2 is the laminate of the present disclosure 1, in which the second resin layer has a Young's modulus of 50 MPa or more and 1500 MPa or less.

[0008] Disclosure 3 is a laminate (second laminate of the present invention) comprising a thin glass sheet having a thickness of 200 μm or less, a first resin layer having a thickness of 5 μm or more arranged on one side of the thin glass sheet, and a second resin layer having a thickness of 5 μm or more arranged on the side of the thin glass sheet opposite the first resin layer side, wherein the first resin layer has a storage modulus of greater than 2500 MPa at 25° C., and the second resin layer has a Young's modulus of 50 MPa or more and 1500 MPa or less. Disclosure 4 is the laminate of Disclosure 3, wherein the second resin layer has a storage modulus of 3000 MPa or less at 25° C. Disclosure 5 is the laminate of Disclosure 1, 2, 3, or 4, wherein at least one of the first resin layer and the second resin layer has a thickness of 25 μm or less. Disclosure 6 is the laminate of Disclosure 1, 2, 3, 4, or 5, wherein the second resin layer has a glass transition temperature of 100° C. or less. Disclosure 7 is the laminate of Disclosures 1, 2, 3, 4, 5, or 6, wherein the second resin layer comprises a polymer of a cationically curable resin. Disclosure 8 is the laminate of Disclosure 7, wherein the cationically curable resin comprises an epoxy group-containing compound and an oxetanyl group-containing compound. Disclosure 9 is the laminate of Disclosure 8, wherein the epoxy group-containing compound comprises a hydrogenated bisphenol epoxy resin. Disclosure 10 is the laminate of Disclosure 9, wherein the hydrogenated bisphenol epoxy resin comprises a hydrogenated bisphenol A skeleton. Disclosure 11 is the laminate of Disclosures 9 or 10, wherein the hydrogenated bisphenol epoxy resin has an epoxy equivalent of 100 or more and 2000 or less. Disclosure 12 is the laminate of Disclosure 7, wherein the epoxy group-containing compound comprises an epoxy resin having a polyether skeleton. Disclosure 13 is the laminate of Disclosure 12, wherein the epoxy resin having a polyether skeleton is liquid at 23°C. Disclosure 14 is the laminate of Disclosure 8, wherein the oxetanyl group-containing compound is monofunctional. Disclosure 15 is the laminate of Disclosure 7, wherein the cationically curable resin contains a hydrogenated bisphenol epoxy resin, an epoxy resin having a polyether skeleton, and an oxetanyl group-containing compound.

[0033] Disclosure 16 is the laminate of Disclosure 15, wherein the content of the hydrogenated bisphenol epoxy resin in the second resin layer is 20% by weight or more and 60% by weight or less, the content of the epoxy resin having a polyether skeleton is 10% by weight or more and 20% by weight or less, and the content of the oxetanyl group-containing compound is 20% by weight or more and 60% by weight or less. Disclosure 17 is an electronic device including the laminate of Disclosures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16. The present invention is described in detail below.

[0009] The present inventors have investigated the possibility of improving the impact resistance of thin glass sheets placed on the display surfaces of electronic devices, etc., by laminating a resin layer on the surface thereof. As a result, they have found that providing resin layers on both sides of thin glass sheets can effectively prevent glass from shattering, that making the first resin layer a hard coat layer with a high storage modulus can enhance the protective performance of the glass surface, and that adjusting the combination of the breaking energy and storage modulus or the Young's modulus of the second resin layer to fall within a specific range can enhance impact resistance, thereby completing the present invention.

[0010] The first laminate and the second laminate each include a thin glass sheet having a thickness of 200 μm or less, a first resin layer having a thickness of 5 μm or more and disposed on one side of the thin glass sheet, and a second resin layer having a thickness of 5 μm or more and disposed on the side of the thin glass sheet opposite the first resin layer. At least one of the first resin layer and the second resin layer may be provided within the first laminate and the second laminate. The first laminate and the second laminate may also include layers other than the thin glass sheet, the first resin layer, and the second resin layer. For example, the first resin layer and the second resin layer may be laminated to the thin glass sheet via an adhesive layer, but are preferably in direct contact with the thin glass sheet without an adhesive layer. When the first resin layer and the second resin layer are provided without an adhesive layer, a method of forming the resin layer by applying a resin composition that is the material for the first resin layer and the second resin layer to the surface of the thin glass and curing it is preferably used.

[0011] The first resin layer and the second resin layer preferably cover 80% or more of the area of ​​the thin glass sheet in a plan view, and more preferably cover the entire surface of the thin glass sheet.

[0012] The configurations of the first laminate and the second laminate are appropriately selected depending on the application, but when they are disposed on the front surface of a display device such as an organic electroluminescence display device, they may have the configuration shown in Fig. 1. Fig. 1 is a schematic cross-sectional view showing an example of the configuration of the laminate of the present invention. In Fig. 1, the laminate 10 comprises a first resin layer 11 on one side (the viewing side) of a thin glass sheet 12, and a second resin layer 13 on the opposite side (the display device side) of the thin glass sheet 12 from the first resin layer 11 side, and may be integrated with a polarizing plate 15 by an optically transparent adhesive (OCA) 14.

[0013] The thin glass sheet is not particularly limited as long as it is plate-shaped and has a thickness of 200 μm or less. Examples of the composition of the thin glass sheet include soda-lime glass, borate glass, aluminosilicate glass, and quartz glass. Furthermore, classification based on the alkali component includes alkali-free glass and low-alkali glass. From the viewpoint of impact resistance, the thin glass sheet is preferably chemically strengthened glass that has been subjected to a chemical strengthening treatment. Chemically strengthened glass preferably has a compressive stress layer formed on its surface by a chemical strengthening treatment (ion exchange treatment). The shape of the thin glass sheet is not limited to a flat plate shape and may be, for example, a curved plate shape.

[0014] The thickness of the thin glass sheet is 200 μm or less. When the thickness of the thin glass sheet is 200 μm or less, the flexibility required for foldable electronic devices can be obtained. Furthermore, the thinner the thickness of the thin glass sheet, the more significantly the improvement in impact resistance due to the resin layer becomes. The thickness of the thin glass sheet is preferably 150 μm or less, more preferably 100 μm or less. Furthermore, the thickness of the thin glass sheet is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, and particularly preferably 30 μm or more. When the thin glass sheet has a certain thickness or more, it is possible to achieve both flexibility and impact resistance.

[0015] The thin glass preferably has a light transmittance of 85% or more at a wavelength of 550 nm, and a refractive index of 1.4 to 1.65 at a wavelength of 550 nm.

[0016] The density of the thin glass is preferably 2.3 g / cm ３ ~3.0 g / cm ３ and more preferably 2.3 g / cm ３ ~2.7g / cm ３ is.

[0017] The method for producing the glass used for the thin glass sheet is not particularly limited, and for example, the thin glass sheet is produced by melting a mixture containing a main raw material such as silica or alumina, an antifoaming agent such as mirabilite or antimony oxide, and a reducing agent such as carbon at a temperature of 1400°C to 1600°C, forming it into a thin plate, and then cooling it. Examples of methods for forming the glass into a thin plate include the slot downdraw method, the fusion method, and the float method. Glass formed into a plate by these methods may be chemically polished with a solvent such as hydrofluoric acid, as necessary, to thin the plate or to improve its smoothness.

[0018] In the case of chemically strengthened glass, a chemical strengthening treatment is performed. In the chemical strengthening treatment, the surface of the glass is ion-exchanged to form a surface layer (compressive stress layer) in which compressive stress remains. Specifically, alkali metal ions (typically Li ions or Na ions) with a small ionic radius present near the surface of the glass sheet are replaced by alkali ions with a larger ionic radius (typically Na ions or K ions for Li ions, and K ions for Na ions) by ion exchange at a temperature below the glass transition point. This causes compressive stress to remain on the surface of the glass, improving the strength of the glass.

[0019] The thin glass may be commercially available as it is, or may be commercially available glass that has been subjected to additional treatment such as polishing or etching to a desired thickness.

[0020] <Characteristics of the first resin layer provided in the first and second laminates> In the first laminate and the second laminate, the first resin layer has a storage modulus at 25°C of greater than 2500 MPa. When the storage modulus is greater than 2500 MPa, scratches on the surface of thin glass can be effectively prevented. The storage modulus is preferably 3000 MPa or more. Furthermore, there is no particular upper limit to the storage modulus, but from the viewpoint of ensuring the flexibility of the laminate, it is preferably 10000 MPa or less, and more preferably 5000 MPa or less.

[0021] <Characteristics of the second resin layer included in the first laminate> In the first laminate, the second resin layer has a breaking energy of 1 mJ / mm ３ The storage modulus at 25°C is 2500 MPa or less. ３ By satisfying the above, it is possible to impart sufficient impact resistance to thin glass that has been thinned to realize foldable electronic devices. The breaking energy is preferably 1.5 mJ / mm ３ More preferably, 2 mJ / mm ３ The upper limit of the breaking energy is not particularly limited, but from the viewpoint of ensuring other properties of the laminate, it is, for example, 50 mJ / mm ３ or less. Furthermore, when the storage modulus is 2500 MPa or less, sufficient impact resistance can be imparted to thin glass. Furthermore, since the flexibility of the resin layer can be ensured, a laminate having the flexibility required to realize a foldable electronic device can be obtained. The storage modulus is preferably 2000 MPa or less, more preferably 1800 MPa or less. Furthermore, the lower limit of the storage modulus is not particularly limited, but from the viewpoint of ensuring the impact resistance of the laminate, it is, for example, 100 MPa or more.

[0022] The breaking energy can be measured in accordance with JIS K7113 "Tensile Test Methods for Plastics" using a test piece prepared according to the following procedure. A release-treated polyethylene terephthalate resin film is placed on a 0.7 mm thick glass plate with the release surface facing up, and a 0.5 mm thick silicone sheet die punched into a dumbbell shape (SDK-400) is then placed on top. The resin composition used to form the resin layer is poured into the dumbbell mold, and the resin liquid is covered with the release surface of the release-treated polyethylene terephthalate resin film so as not to trap air bubbles, and then another glass plate is placed on top. Next, a wavelength of 365 nm and an illuminance of 100 mW / cm are used. ２ The ultraviolet LED was used as a light source through a glass plate for 15 seconds, and the light was exposed to 1500 mJ / cm ２ The specimen is then turned over while still sandwiched between the glass plates, and the reverse side is again irradiated with the same ultraviolet light. The specimen is then heated in an oven at 80°C for 30 minutes to harden the resin, and the hardened resin is removed from the silicone sheet mold to obtain a test specimen. A tensile test is then performed on this specimen using a tensile tester. The tensile test is performed with a chuck distance of 25 mm, a tensile speed of 50 mm / min, and a sampling interval of 20 μm until the specimen breaks. From the measurement results obtained, a stress-strain curve is created with stress (unit: MPa) on the vertical axis and strain (unit: %) on the horizontal axis, and the breaking energy can be calculated by determining the area enclosed by this stress-strain curve and the horizontal axis.

[0023] When the fracture energy of the resin layer is measured directly from the laminate, the resin layer is punched into a dumbbell shape (SDK-400) to be used as the test piece. Alternatively, the resin layer is dissolved in a solvent to make a resin liquid, which is then poured into the dumbbell mold and the solvent is completely dried to obtain the test piece.

[0024] The storage modulus is measured by preparing a measurement sample in the same manner as in the measurement of the breaking energy, except that a 0.5 mm thick silicone sheet mold punched into a rectangular shape with a width of 5 mm and a length of 50 mm is used instead of a 0.5 mm thick silicone sheet mold punched into a dumbbell shape (SDK-400). The dynamic viscoelastic spectrum of the prepared measurement sample is measured from −50° C. to 200° C. using a viscoelasticity spectrometer (e.g., DVA-200 manufactured by IT Measurement & Control Co., Ltd.) under conditions of 5° C. / min and 1 Hz in a slow heating shear deformation mode, and the storage modulus at 25° C. can be obtained.

[0025] The second resin layer preferably has a Young's modulus of 1500 MPa or less. A Young's modulus of 1500 MPa or less allows the second resin layer to have an appropriate degree of flexibility, which is preferable for forming a laminate having the flexibility required to realize a foldable electronic device. Furthermore, when the glass is broken, the resin layer is less likely to break, providing a shatterproof effect. The Young's modulus is more preferably 1400 MPa or less, and even more preferably 1300 MPa or less. While the lower limit of the Young's modulus is not particularly limited, from the viewpoint of ensuring the impact resistance of the laminate, it is preferably 50 MPa or more, and more preferably 80 MPa or more. The Young's modulus can be calculated by creating a stress-strain curve in the same manner as in the case of measuring the fracture energy, and determining the slope of the stress-strain curve at strains of 0 to 10%.

[0026] <Characteristics of the second resin layer provided in the second laminate> In the second laminate, the second resin layer has a Young's modulus of 50 MPa or more and 1500 MPa or less. By having the Young's modulus of 50 MPa or more and 1500 MPa or less, appropriate flexibility for realizing a foldable electronic device can be obtained, and sufficient impact resistance can be imparted to thin glass that is thinned to realize a foldable electronic device. The Young's modulus is preferably 1400 MPa or less, more preferably 1300 MPa or less, and preferably 80 MPa or more.

[0027] The second resin layer has a breaking energy of 1 mJ / mm ３ It is preferable that the breaking energy is 1 mJ / mm or more. ３ When the breaking energy is 1.5 mJ / mm or more, the impact resistance of the laminate can be further improved. ３ More preferably, 2 mJ / mm ３ The upper limit of the breaking energy is not particularly limited, but from the viewpoint of ensuring other properties of the laminate, it is, for example, 50 mJ / mm ３ The following is the result.

[0028] The second resin layer preferably has a storage modulus at 25°C of 3000 MPa or less, more preferably 2500 MPa or less, even more preferably 2000 MPa or less, particularly preferably 1800 MPa or less, and particularly preferably 1500 MPa or less. By setting the storage modulus within the above range, the flexibility of the resin layer can be improved, which is preferable for producing a laminate having the flexibility required to realize a foldable electronic device. In addition, although the lower limit of the storage modulus is not particularly limited, from the viewpoint of ensuring the impact resistance of the laminate, it is preferably 10 MPa or more, more preferably 100 MPa or more, and even more preferably 500 MPa or more.

[0029] <Characteristics of the first and second resin layers common to the first and second laminates> The second resin layer preferably has a breaking elongation of 5% or more. When the breaking elongation is 5% or more, cracks and whitening are less likely to occur in a bending endurance test. The breaking elongation is more preferably 7% or more. There is no particular upper limit to the breaking elongation, but from the viewpoint of ensuring the impact resistance of the laminate, it is preferably 1000% or less. The breaking elongation can be determined by performing a tensile test in the same manner as in the measurement of the breaking energy, and using the value of the strain when the test piece breaks.

[0030] The first resin layer and the second resin layer each preferably have a breaking strength of 5 MPa or more and 50 MPa or less. When the breaking strength is in the range of 5 MPa or more and 50 MPa or less, sufficient impact resistance is easily imparted to the thin glass. The breaking strength is more preferably 10 MPa or more and 40 MPa or less. The breaking strength can be measured by performing a tensile test in the same manner as in the measurement of the breaking energy, and using the value of the stress at which the test piece breaks.

[0031] The second resin layer preferably has a glass transition temperature of 100°C or lower. When the glass transition temperature of the resin layer is 100°C or lower, the flexibility of the resin layer can be ensured, which is preferable in terms of obtaining a laminate having the flexibility required to realize a foldable electronic device. The glass transition temperature is more preferably 80°C or lower, and even more preferably 60°C or lower. The lower limit of the glass transition temperature is not particularly limited, but is, for example, 0°C or higher from the viewpoint of ensuring other properties of the laminate. Note that the glass transition temperature can be determined by creating a dynamic viscoelasticity spectrum in the same manner as in the case of measuring the storage modulus, and using the temperature at the maximum value of the loss tangent.

[0032] The first resin layer and the second resin layer each preferably have a total light transmittance of 80% or more. When the total light transmittance of the resin layer is 80% or more, the transparency of the resin layer can be ensured, which is preferable in terms of forming a laminate having the transparency required to realize a foldable display device (foldable display). The total light transmittance is more preferably 90% or more. The total light transmittance can be measured, for example, using a HazeMeter NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The total light transmittance is measured by a method conforming to JIS K 7361-1.

[0033] The thickness of the first resin layer and the second resin layer is each 5 μm or more. A thickness of 5 μm or more of the first resin layer can effectively enhance the protection performance of the glass surface, and a thickness of 5 μm or more of the second resin layer can provide a flexible resin layer with an impact-absorbing function, thereby imparting sufficient impact resistance to thin glass that has been thinned to realize a foldable electronic device. The thickness of the first resin layer and the second resin layer is preferably 10 μm or more. Furthermore, the upper limit of the thickness of the first resin layer and the second resin layer is not particularly limited, but from the viewpoint of ensuring the bendability of the laminate, it is preferably thinner than thin glass. Specifically, it is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 25 μm or less. From the viewpoint of improving the bendability of the laminate, it is preferable that at least one of the first resin layer and the second resin layer has a thickness of 25 μm or less.

[0034] Hereinafter, each material that can be used for the first resin layer and the second resin layer will be described. The resin composition used to form the first resin layer and the second resin layer is not particularly limited as long as it can adjust the properties of the resin layer obtained after curing within the desired range. For example, a material containing a cationically curable resin is preferably used because it has excellent adhesion to glass. That is, it is preferable that the first resin layer and the second resin layer each contain a polymer of a cationically curable resin, and in particular, it is preferable that the second resin layer contains a polymer of a cationically curable resin.

[0035] The cationically curable resin is not particularly limited as long as it has at least one cationically polymerizable functional group in the molecule and is a highly cationically polymerizable compound. Examples of the cationically polymerizable functional group include an epoxy group, an oxetanyl group, a vinyl ether group, an episulfide group, and an ethyleneimine group. Among these, the cationically curable resin preferably contains at least one resin selected from the group consisting of an epoxy resin (an epoxy group-containing compound), an oxetane resin (an oxetanyl group-containing compound), and a vinyl ether resin (a vinyl ether group-containing compound), and more preferably contains an epoxy resin (an epoxy group-containing compound) and an oxetane resin (an oxetanyl group-containing compound). Epoxy resins and oxetane resins have excellent adhesion to the thin glass, and therefore can prevent the first resin layer and the second resin layer from peeling off when the first laminate or the second laminate is repeatedly bent.

[0036] The epoxy resin (epoxy group-containing compound) is not particularly limited, and examples thereof include bisphenol-type epoxy resins such as bisphenol A, bisphenol F, bisphenol AD, and bisphenol S; novolac-type epoxy resins such as phenol novolac and cresol novolac; aromatic epoxy resins such as resorcinol-type epoxy resins and trisphenolmethane triglycidyl ether; alicyclic epoxy resins; naphthalene-type epoxy resins; fluorene-type epoxy resins; dicyclopentadiene-type epoxy resins; polyether-modified epoxy resins such as epoxy resins having a polyether skeleton; NBR-modified epoxy resins; CTBN-modified epoxy resins; and hydrogenated versions thereof. Among these, hydrogenated bisphenol-type epoxy resins and epoxy resins having a polyether skeleton are preferably used as the cationically curable resin contained in the resin composition used to form the second resin layer. These epoxy resins may be used alone or in combination of two or more.

[0037] The hydrogenated bisphenol epoxy resin is preferably a hydrogenated bisphenol A epoxy resin containing a hydrogenated bisphenol A skeleton. The hydrogenated bisphenol epoxy resin may be a multimer such as a dimer. The hydrogenated bisphenol epoxy resin preferably has an epoxy equivalent of 100 or more and 2000 or less. By having the epoxy equivalent of 100 or more and 2000 or less, the crosslinking density of the epoxy resin can be controlled within a preferred range, thereby further improving impact resistance. The epoxy equivalent is defined as "the mass of the resin containing one equivalent of epoxy groups" and is measured according to a method in accordance with JIS K7236.

[0038] Examples of the alicyclic epoxy resin include 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexyl)adipate, 1,2-epoxy-4-vinylcyclohexane, 1,4-cyclohexanedimethanol diglycidyl ether, epoxyethyldivinylcyclohexane, diepoxyvinylcyclohexane, 1,2,4-triepoxyethylcyclohexane, limonene dioxide, and alicyclic epoxy group-containing silicone oligomers. These alicyclic epoxy resins may be used alone or in combination of two or more.

[0039] The epoxy resin may be an epoxy resin that is liquid at room temperature (23° C.) or an epoxy resin that is solid at room temperature, or an appropriate combination of these may be used. The epoxy resin preferably contains at least one epoxy resin that is liquid at room temperature, and for example, a hydrogenated bisphenol epoxy resin that is liquid at room temperature or an epoxy resin having a polyether skeleton that is liquid at room temperature is preferably used. Examples of the epoxy resins that are liquid at room temperature include polyether skeleton epoxy resins such as "jER YX7400" and "jER YX7400N" (both manufactured by Mitsubishi Chemical Corporation); bisphenol A type epoxy resins such as "EPICLON 840", "EPICLON 840-S", "EPICLON 850", "EPICLON 850-S", and "EPICLON EXA-850CRP" (all manufactured by DIC Corporation); bisphenol F type epoxy resins such as "EPICLON 830", "EPICLON 830-S", "EPICLON EXA-830CRP", and "EPICLON EXA-830LVP" (all manufactured by DIC Corporation) and "jER 806H" (manufactured by Mitsubishi Chemical Corporation); Naphthalene-type epoxy resins such as "JER YX8000", "jER YX8034", "jER YX8040" (all manufactured by Mitsubishi Chemical Corporation), "EPICLON EXA-7015" (manufactured by DIC Corporation), and "EX-252" (manufactured by Nagase ChemteX Corporation); resorcinol-type epoxy resins such as "EX-201" (manufactured by Nagase ChemteX Corporation); "Celloxide 2081", "Celloxide 2021P", "Celloxide 2000", "Celloxide 3000", "Celloxide 8000", "Celloxide 8010", "EHPE3150" (all manufactured by Daicel Corporation), and "TTA21" (manufactured by Jiangsu Alicyclic epoxy resins such as "X-40-2670", "X-22-169AS", and "X-22-169B" (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like are commercially available.

[0040] Examples of the epoxy resins that are solid at room temperature include bisphenol A type epoxy resins such as "EPICLON 860", "EPICLON 10550", and "EPICLON 1055" (all manufactured by DIC Corporation); bisphenol F type epoxy resins such as "jER 4005P" (manufactured by Mitsubishi Chemical Corporation); bisphenol S type epoxy resins such as "EPICLON EXA-1514" (manufactured by DIC Corporation); naphthalene type epoxy resins such as "EPICLON HP-4700", "EPICLON HP-4710", and "EPICLON HP-4770" (all manufactured by DIC Corporation); dicyclopentadiene type epoxy resins such as "EPICLON HP-7200 series" (manufactured by DIC Corporation); EXA-9900" (manufactured by DIC Corporation) and other cresol novolac epoxy resins are commercially available.

[0041] The oxetane resin (oxetanyl group-containing compound) which is the cationically curable resin is not particularly limited, and examples thereof include 3-ethyl-3-[(2-ethylhexyloxy)methyl]oxetane, 3-ethyl-3-hydroxymethyloxetane, 1,4-bis([(3-ethyl-3-oxetanyl)methoxy]methyl)benzene, 3-ethyl-3-(phenoxymethyl)oxetane, bis[(3-ethyloxetan-3-yl)methyl]ether, 3-ethyl-3-([3-(triethoxysilyl)propoxy]methyl)oxetane, and oxetanylsilsesquioxane. Monofunctional oxetane resins are preferably used. Examples of the oxetane resin include "ETRENACOLL EHO" (manufactured by Ube Industries, Ltd.), "ARONOXETANE OXT-101," "ARONOXETANE OXT-121," "ARONOXETANE OXT-211," "ARONOXETANE OXT-221," and "ARONOXETANE OXT-610" (all manufactured by Toagosei Co., Ltd.). These may be used alone or in combination of two or more.

[0042] The vinyl ether resin (vinyl ether group-containing compound) that is the cationically curable resin is not particularly limited, and examples thereof include methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, allyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-pentyl vinyl ether, isopentyl vinyl ether, tert-pentyl vinyl ether, n-hexyl vinyl ether, isohexyl vinyl ether, 2-ethylhexyl vinyl ether, n-heptyl vinyl ether, n-octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether, hexadecyl vinyl ether, octadecyl vinyl ether, ethoxymethyl vinyl ether, 2-methoxyethyl vinyl ether, 2-ethoxyethyl vinyl ether, 2-butoxyethyl vinyl ether, acetoxymethyl vinyl ether, 2-acetoxyethyl vinyl ether, 3-acetoxypropyl vinyl ether, 4-acetoxybutyl vinyl ether, and 4-ethoxybutyl vinyl ether. , 2-(2-methoxyethoxy)ethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, diethylene glycol monovinyl ether, diethylene glycol methyl vinyl ether, diethylene glycol ethyl vinyl ether, triethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether, polyethylene glycol monovinyl ether, propylene glycol monovinyl ether, dipropylene glycol monovinyl ether, tripropylene glycol monovinyl ether, polypropylene glycol monovinyl ether, 4-hydroxycyclohexyl vinyl ether, cyclohexyldimethanol monovinyl ether, trimethylolpropane monovinyl ether, ethylene oxide-added trimethylolpropane monovinyl ether, pentaerythritol monovinyl ether, ethylene oxide-added pentaerythritol monovinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether,Cyclohexyl ethyl vinyl ether, menthyl vinyl ether, tetrahydrofurfuryl vinyl ether, norbornenyl vinyl ether, 1-adamantyl vinyl ether, 2-adamantyl vinyl ether, phenyl vinyl ether, benzyl vinyl ether, 1-naphthyl vinyl ether, 2-naphthyl vinyl ether, glycidyl vinyl ether, diethylene glycol ethyl vinyl ether, triethylene glycol methyl vinyl ether, divinyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, polypropylene glycol divinyl ether, butanediol divinyl ether, neopentyl glycol divinyl Examples of the vinyl vinyl compounds include vinyl ether, hexanediol divinyl ether, nonanediol divinyl ether, hydroquinone divinyl ether, 1,4-cyclohexanediol divinyl ether, 1,4-cyclohexanedimethanol divinyl ether, trimethylolpropane divinyl ether, ethylene oxide-added trimethylolpropane divinyl ether, pentaerythritol divinyl ether, ethylene oxide-added pentaerythritol divinyl ether, trimethylolpropane trivinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, pentaerythritol trivinyl ether, ethylene oxide-added pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, ditrimethylolpropane tetravinyl ether, and dipentaerythritol hexavinyl ether. These may be used alone or in combination of two or more.

[0043] The cationically curable resin is preferably a hydrogenated bisphenol epoxy resin, an epoxy resin having a polyether skeleton, or an oxetanyl group-containing compound, which can provide particularly excellent impact resistance and therefore also provide good results in the evaluation of shatterproofness by a pen drop test.

[0044] The content of the hydrogenated bisphenol epoxy resin is not particularly limited, but is preferably 20% by weight or more, more preferably 40% by weight or more, and preferably 70% by weight or less, and more preferably 50% by weight or less, relative to the total amount of the resin layer containing the cationic curable resin polymer. The content of the epoxy resin having a polyether skeleton is not particularly limited, but is preferably 10% by weight or more, more preferably 12% by weight or more, and preferably 40% by weight or less, more preferably 30% by weight or less, and even more preferably 20% by weight or less, relative to the total amount of the resin layer containing the cationic curable resin polymer. The content of the oxetanyl group-containing compound is not particularly limited, but is preferably 10% by weight or more, more preferably 20% by weight or more, and preferably 70% by weight or less, more preferably 60% by weight or less, and even more preferably 50% by weight or less, relative to the total amount of the resin layer containing the cationic curable resin polymer. It is preferred that the content of the hydrogenated bisphenol epoxy resin in the second resin layer containing a polymer of the cationically curable resin is 20% by weight or more and 60% by weight or less, the content of the epoxy resin having a polyether skeleton is 10% by weight or more and 20% by weight or less, and the content of the oxetanyl group-containing compound is 20% by weight or more and 60% by weight or less.

[0045] Furthermore, the resin composition used to form the first resin layer is preferably one containing an epoxy resin (an epoxy group-containing compound) as a main component. Specifically, the content of the epoxy resin in the first resin layer is preferably 60% by weight or more, more preferably 80% by weight or more, and even more preferably 85% by weight or more. Suitable examples of the epoxy resin used in the first resin layer include bifunctional alicyclic epoxy resins such as "Celloxide 2021P" and "Celloxide 8010" (both manufactured by Daicel Corporation); multifunctional (trifunctional or higher) epoxy resins such as "TEPIC-VL" (manufactured by Nissan Chemical Industries, Ltd.), "EPICLON HP-4710" (manufactured by DIC Corporation), and "GTR-1800" (manufactured by Nippon Kayaku Co., Ltd.); and rigid-skeleton epoxy resins such as "EPICLON HP-7200" (manufactured by DIC Corporation), "OGSOL PG-100," and "OGSOL CG-500" (both manufactured by Osaka Gas Chemicals Co., Ltd.). Examples of rigid-skeleton epoxy resins include epoxy resins having an aromatic ring, such as epoxy resins having a biphenyl skeleton, epoxy resins having a naphthalene skeleton, and epoxy resins having a bisphenol skeleton. An example of an epoxy resin having a bisphenol skeleton is a bisphenol F type epoxy resin.

[0046] The resin composition preferably contains a polymerization initiator. The polymerization initiator may be a photopolymerization initiator or a thermal polymerization initiator. Examples of photopolymerization initiators include compounds formed by combining a cation such as diphenyliodonium, 4-methoxydiphenyliodonium, bis(4-methylphenyl)iodonium, bis(4-tert-butylphenyl)iodonium, bis(dodecylphenyl)iodonium, diphenyl-4-thiophenoxyphenylsulfonium, bis[4-(diphenylsulfonio)-phenyl]sulfide, bis[4-(di(4-(2-hydroxyethyl)phenyl)sulfonio)-phenyl]sulfide, and η5-2,4-(cyclopentadienyl)[1,2,3,4,5,6-η-(methylethyl)benzene]-iron(1+) with an anion such as tetrafluoroborate, hexafluorophosphate, triphenylhexafluorophosphate, or hexafluoroarsenate. Examples of the thermal polymerization initiator include imidazoles, quaternary ammonium salts, phosphorus compounds, amines, phosphines, phosphonium salts, bicyclic amidines and their salts, acid anhydrides, novolac phenolic resins obtained by condensation reaction of phenol, cresol, xylenol, resorcinol, or the like with formaldehyde, polymercapto resins such as liquid polymercaptan and polysulfide, amides, etc. These polymerization initiators may be used alone or in combination of two or more.

[0047] The content of the polymerization initiator is preferably 0.1 parts by weight at the lower limit and 10 parts by weight at the upper limit relative to 100 parts by weight of the cationic curable resin. If the content of the polymerization initiator is less than 0.1 parts by weight, the cationic polymerization may not proceed sufficiently, or the curing reaction may be too slow. If the content of the polymerization initiator exceeds 10 parts by weight, the curing reaction of the resin composition may be too fast, resulting in reduced workability and an uneven composition of the resulting resin layer. A more preferred lower limit of the content of the polymerization initiator is 0.5 parts by weight, and a more preferred upper limit is 5 parts by weight.

[0048] The resin composition may further contain various known additives such as a solvent, a viscosity adjuster, a surface modifier (surfactant, leveling agent), a plasticizer, a silane coupling agent, a tackifier, a sensitizer, a thermosetting agent, a crosslinking agent, a cure retarder, an antioxidant, a storage stabilizer, a dispersant, and a filler, as long as the additives do not impair the object of the present invention.

[0049] The method for preparing the resin composition is not particularly limited, and examples thereof include a method of using a mixer to mix a curable resin, a polymerization initiator, and additives to be added as needed, etc. Examples of the mixer include a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roll mill.

[0050] The method for forming the first resin layer and the second resin layer is not particularly limited, and for example, they can be formed by applying a resin composition to the surface of the thin glass plate and then curing it by light irradiation, heating, etc. The method for applying the resin composition is not particularly limited, and for example, screen printing, die coating printing, offset printing, gravure printing, inkjet printing, etc. may be used.

[0051] The resin composition may contain a solvent from the viewpoint of coatability and the like. As the solvent, from the viewpoint of coatability, storage stability, and the like, a nonpolar solvent having a boiling point of 200°C or less or an aprotic polar solvent having a boiling point of 200°C or less is preferred. Examples of the nonpolar solvent having a boiling point of 200°C or less or an aprotic polar solvent having a boiling point of 200°C or less include ketone solvents, ester solvents, hydrocarbon solvents, halogenated solvents, ether solvents, and nitrogen-containing solvents. From the viewpoint of the stability of the coating liquid, the uniformity of the coating film, drying efficiency, and the like, the boiling point of the nonpolar solvent or aprotic polar solvent is more preferably in the range of 80°C to 180°C.

[0052] The resin composition preferably has a viscosity of 1 to 1,000 mPa·s at 25°C as measured using an E-type viscometer. A more preferred viscosity range is adjusted depending on the coating method. For example, a range of 5 to 50 mPa·s is preferred for application by inkjet coating, a range of 10 to 100 mPa·s is preferred for application by slit coating, and a range of 100 to 1,000 mPa·s is preferred for application by roll coating or offset printing. On the other hand, if the viscosity exceeds 1,000 mPa·s, the leveling properties of the coating liquid tend to decrease, and the uniformity of the thickness of the coating film tends to decrease. The viscosity can be measured, for example, using a VISCOMETER TV-22 (manufactured by Toki Sangyo Co., Ltd.) as an E-type viscometer with a CP1 cone plate, by appropriately selecting a rotation speed of 1 to 100 rpm from the optimal torque number for each viscosity range.

[0053] Further, an electronic device comprising the first laminate or the second laminate also constitutes one aspect of the present invention. As the electronic device of the present invention, a foldable electronic device (foldable electronic device) is preferred, and in particular, a foldable display device (foldable display) is preferred. Specific examples include mobile display terminals such as smartphones, e-books, and tablet PCs. From the viewpoint of exhibiting surface scratch resistance, a display device comprising the first laminate or the second laminate preferably has a configuration in which the first resin layer is disposed on the viewing side and the second resin layer is disposed on the display device side. According to this configuration, the first resin layer functioning as a hard coat layer is located on the surface side of the display device.

[0054] According to the present invention, it is possible to provide a laminate having excellent impact resistance and surface scratch resistance, and an electronic device using the laminate.

[0055] 1 is a schematic cross-sectional view showing an example of the configuration of a laminate of the present invention.

[0056] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0057] (Examples 1 to 11, Comparative Examples 2 to 5) A curable resin shown in (1) below, an initiator shown in (2) below, and a surface modifier shown in (3) below were mixed and stirred according to the compounding ratios shown in Table 1 below to obtain a resin composition. The obtained resin composition was diluted with a solvent, propylene glycol monomethyl ether acetate, to adjust the viscosity, and then coated onto a thin glass plate having a thickness of 50 μm so as to have a thickness after drying shown in Table 1 below. The obtained coating film was dried at a temperature of 100° C. for 15 minutes, and then irradiated with ultraviolet light having a wavelength of 365 nm at a dose of 1500 mJ / cm. ２ The resin was cured by irradiating the thin glass with light at 1000 W at 4000 W and then heating at 80° C. for 30 minutes. As a result, a laminate was obtained which had a first resin layer made of a cured resin on one side (the viewing side) of the thin glass and a second resin layer made of a cured resin on the other side (the display element side).

[0058] (1) Curable Resins EPICLON EXA-830LVP (mixture of bisphenol F liquid epoxy resin and bisphenol A liquid epoxy resin, manufactured by DIC Corporation) jER YX7400N (polyether skeleton liquid epoxy resin, manufactured by Mitsubishi Chemical Corporation) jER 4005P (bisphenol F solid epoxy resin, manufactured by Mitsubishi Chemical Corporation) jER YX8000 (hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 192 to 220) jER YX8034 (hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 250 to 360) jER YX8040 (hydrogenated bisphenol A epoxy resin, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 900 to 1500) Celloxide 2021P (3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, manufactured by Daicel Corporation) ETRENACOLL EHO (3-ethyl-3-hydroxymethyloxetane, manufactured by Ube Industries, Ltd.)

[0059] (2) Initiator CPI-210S (a triarylsulfonium salt-type photocationic polymerization initiator, manufactured by San-Apro Co., Ltd.) DTS-200 (aromatic sulfonium salt-type photocationic polymerization initiator, manufactured by Midori Chemical Co., Ltd.) (3) Surface modifier BYK-340 (manufactured by BYK-Chemie Co., Ltd.) JAR-33 (organically modified polysiloxane, manufactured by Jujo Chemical Co., Ltd.)

[0060] Comparative Example 1 A thin glass sheet of Comparative Example 1 was prepared using the same 50 μm thick thin glass sheet as in Examples 1 to 11 and Comparative Examples 2 to 5, on the surface of which no resin layer was formed.

[0061] <Measurement of Physical Properties> The physical properties of the cured resin products prepared in Examples 1 to 11 and Comparative Examples 2 to 5 were measured by the following methods. The results are shown in Table 1 below.

[0062] (Storage Modulus and Glass Transition Temperature) Test pieces of the cured resin measuring 0.5 mm thick, 5 mm wide, and 50 mm long were prepared, and the dynamic viscoelasticity spectrum was measured from -50°C to 150°C using a viscoelasticity spectrometer (DVA-200, manufactured by IT Measurement & Control Co., Ltd.) under conditions of 10°C / min and 10 Hz in tensile mode. The storage modulus at 25°C was determined from the obtained dynamic viscoelasticity spectrum. The temperature at which the loss tangent was maximized was taken as the glass transition temperature Tg (°C).

[0063] (Young's Modulus, Breaking Elongation, Breaking Strength, Breaking Energy) In accordance with JIS K7113 "Tensile Testing Methods for Plastics," 0.5 mm thick dumbbell-shaped (SDK-400) test specimens of the cured resin were prepared and subjected to tensile testing using a tensile testing machine. The tensile test was performed until the specimen broke, with a chuck distance of 20 mm, a tensile speed of 50 mm / min, and a sampling interval of 20 μm. From the obtained measurement results, a stress-strain curve was created, with stress (unit: MPa) on the vertical axis and strain (unit: %) on the horizontal axis. The strain value at which the specimen broke was taken as the breaking elongation, and the maximum stress value at which the specimen broke was taken as the breaking strength. Young's modulus was calculated by determining the slope of the stress-strain curve at strains of 0 to 10%. Breaking energy was calculated by determining the area enclosed by the stress-strain curve and the horizontal axis.

[0064] <Evaluation> The laminates obtained in Examples 1 to 11 and Comparative Examples 2 to 5 and the thin glass plate of Comparative Example 1 were evaluated as follows. The results are shown in Table 1 below.

[0065] (Pen Drop Test) The first resin layer side of the laminate was placed on a 10 mm thick artificial marble slab ("Corian" manufactured by DuPont), with the first resin layer side facing up, and a ballpoint pen (Orange EG 0.7 manufactured by BIC Japan, with a 0.7 mm diameter nib and a weight of 5.75 g) was dropped vertically from a predetermined height onto the first resin layer side of the laminate with the nib facing downward. The maximum height at which no cracks occurred in the thin glass sheet was recorded as the test result.

[0066] (Shatterproof test) For laminates in which cracks occurred in the thin glass sheet in the pen drop test, shatterproofness was evaluated based on the following evaluation criteria. ∘: Cracks occurred in the glass, but the glass fragments caused by the cracks were held together by the resin layer, and there was no peeling between the resin layer and the thin glass sheet, so no shattering of the glass was observed. ×: Cracks occurred in the thin glass sheet and at the same time, cracks also occurred in the resin layer, causing fragmentation, or the resin layer and the thin glass sheet were peeled off, causing fragmentation of the glass.

[0067] (Bending durability test) Using a U-bending tester (manufactured by Yuasa System Co., Ltd., DLDMLH-FS), the laminate was positioned so that the first resin layer was on the inside when bent, and repeatedly bent at a test speed of 1 second / cycle, a bending radius R of 2.0 mm, and a number of flexing times of 100,000. After the test, the bent portion of the laminate was visually inspected. A case in which there was no change in appearance before and after the test was evaluated as "○", and a case in which cracks or whitening occurred and the appearance changed after the test was evaluated as "×".

[0068] (Surface Scratch Test) The laminate was placed on a 10 mm thick artificial marble plate ("Corian" manufactured by DuPont) with the first resin layer side facing up, and the pencil hardness of the laminate was measured in accordance with JIS K5600-5-4 "Scratch Hardness (Pencil Method)".

[0069]

[0070] According to the present invention, it is possible to provide a laminate having excellent impact resistance and surface scratch resistance, and an electronic device using the laminate.

[0071] REFERENCE SIGNS LIST 10 Laminate 11 First resin layer 12 Thin glass sheet 13 Second resin layer 14 Optical transparent adhesive 15 Polarizing plate

Claims

1. A thin glass sheet having a thickness of 200 μm or less; A first resin layer having a thickness of 5 μm or more and disposed on one side of the thin glass; A second resin layer having a thickness of 5 μm or more is disposed on the opposite side of the thin glass to the first resin layer side, The first resin layer has a storage modulus at 25° C. of more than 2500 MPa, The second resin layer has a breaking energy of 1 mJ / mm ３ or more, and the storage modulus at 25° C. is 2500 MPa or less. A laminate comprising:

2. The laminate according to claim 1 , wherein the second resin layer has a Young's modulus of 50 MPa or more and 1500 MPa or less.

3. A thin glass sheet having a thickness of 200 μm or less; A first resin layer having a thickness of 5 μm or more and disposed on one side of the thin glass; A second resin layer having a thickness of 5 μm or more is disposed on the opposite side of the thin glass to the first resin layer side, The first resin layer has a storage modulus at 25° C. of more than 2500 MPa, The second resin layer has a Young's modulus of 50 MPa or more and 1500 MPa or less. A laminate comprising:

4. The laminate according to claim 3 , wherein the second resin layer has a storage modulus at 25° C. of 3000 MPa or less.

5. 5. The laminate according to claim 1, wherein at least one of the first resin layer and the second resin layer has a thickness of 25 [mu]m or less.

6. 5. The laminate according to claim 1, wherein the second resin layer has a glass transition temperature of 100[deg.] C. or lower.

7. 5. The laminate according to claim 1, wherein the second resin layer contains a polymer of a cationic curable resin.

8. The laminate according to claim 7, wherein the cationically curable resin comprises an epoxy group-containing compound and an oxetanyl group-containing compound.

9. 9. The laminate according to claim 8, wherein the epoxy group-containing compound comprises a hydrogenated bisphenol type epoxy resin.

10. The laminate according to claim 9 , wherein the hydrogenated bisphenol type epoxy resin contains a hydrogenated bisphenol A skeleton.

11. 10. The laminate according to claim 9, wherein the hydrogenated bisphenol type epoxy resin has an epoxy equivalent of 100 or more and 2,000 or less.

12. 9. The laminate according to claim 8, wherein the epoxy group-containing compound comprises an epoxy resin having a polyether skeleton.

13. The laminate according to claim 12, wherein the epoxy resin having a polyether skeleton is liquid at 23°C.

14. The laminate according to claim 8, wherein the oxetanyl group-containing compound is monofunctional.

15. 5. An electronic device comprising the laminate according to claim 1.