JP5330966B2 - Transparent substrate, display element using the transparent substrate, solar cell, and lighting element - Google Patents

Description

  The present invention relates to a transparent substrate, a display element using the transparent substrate, a solar cell, and a lighting element. More specifically, the present invention can be thinned, has excellent adhesion, flexibility, impact resistance and flexibility between the inorganic glass and the resin layer in a high temperature and high humidity environment, and The present invention relates to a transparent substrate that remarkably prevents the development of cracks in glass.

  In recent years, flat panel displays (for example, liquid crystal display devices and organic EL display elements) are becoming lighter and thinner due to the development of video communication technology. Conventionally, a glass substrate is often used as a substrate of a display element. The glass substrate is excellent in transparency, solvent resistance, gas barrier properties, and heat resistance. However, when the glass material constituting the glass substrate is made thinner, the weight is reduced and the flexibility is excellent, but the impact resistance becomes insufficient and the handling property is lowered.

  In order to improve the handling property of a thin glass substrate, a flexible substrate having a resin layer formed on the surface of the glass substrate is disclosed (for example, Patent Documents 1 and 2). However, there is a problem that the adhesiveness is insufficient in the manufacturing process of the display element which requires high reliability for the adhesiveness between the glass substrate and the resin layer even in a high temperature and high humidity environment, and these characteristics are sufficiently satisfied. Such a transparent substrate has not been obtained. The above problems also exist for the solar cell substrate.

JP 11-329715 A JP 2008-107510 A

  The object of the present invention is to enable thinning, excellent adhesion, flexibility, impact resistance and flexibility between an inorganic glass and a resin layer in a high-temperature and high-humidity environment, and a glass crack. It is an object of the present invention to provide a transparent substrate that significantly prevents the progress of the above.

The transparent substrate of the present invention is a transparent substrate comprising an inorganic glass and a resin layer formed by applying a thermoplastic resin solution on one or both sides of the inorganic glass, and the resin layer has a hydroxyl group at the end. A first thermoplastic resin layer obtained by applying a first casting solution containing a first thermoplastic resin and an epoxy terminal coupling agent onto the inorganic glass, and a second thermoplastic resin A second thermoplastic resin layer obtained by applying a second casting solution containing a resin onto the first thermoplastic resin layer is included.
In preferable embodiment, content of the said epoxy-type terminal coupling agent is 10 weight part-50 weight part with respect to 100 weight part of said 1st thermoplastic resins.
In a preferred embodiment, the first casting solution further includes a cyclic ether compound and / or a compound in which a cyclic part of the cyclic ether compound is opened, and the cyclic part of the cyclic ether compound and / or the cyclic ether compound is opened. The content of the compound is 5 to 50 parts by weight with respect to 100 parts by weight of the first thermoplastic resin.
In a preferred embodiment, the total thickness of the transparent substrate is 150 μm or less.
In a preferred embodiment, the inorganic glass has a thickness of 100 μm or less.
In a preferred embodiment, the thickness of the first thermoplastic resin layer is 20 μm or less.
In a preferred embodiment, the glass transition temperature of the second thermoplastic resin is 150 ° C to 350 ° C.
In a preferred embodiment, the elastic modulus at 25 ° C. of the second thermoplastic resin layer is 1.5 GPa to 10 GPa.
In a preferred embodiment, the fracture toughness value at 25 ° C. of the second thermoplastic resin layer is ^{1.5MPa · m 1/2 ~10MPa · m 1/2} .
In a preferred embodiment, the fracture diameter when the transparent substrate is cracked and bent is 50 mm or less.
In a preferred embodiment, the transparent substrate of the present invention is used for a solar cell, a display element or a lighting element.
According to another aspect of the present invention, a display element is provided. This display element uses the transparent substrate described above.
According to still another aspect of the present invention, a solar cell is provided. This solar cell uses the transparent substrate described above.
According to still another aspect of the present invention, a lighting element is provided. The illumination element uses the transparent substrate described above.

  The transparent substrate of the present invention comprises, as a resin layer, a first thermoplastic resin layer including a first thermoplastic resin having a hydroxyl group at the terminal and an epoxy-based terminal coupling agent, and a specific second thermoplastic resin layer. By having it, the inorganic glass and the resin layer have excellent adhesion even in a high temperature and high humidity environment. Therefore, the handleability of the obtained transparent substrate is also improved. Furthermore, since a thin glass material can be used, the transparent substrate can be thinned. In the transparent substrate of the present invention, since the second thermoplastic resin layer prevents the progress and breakage of inorganic glass cracks, it is excellent in flexibility, impact resistance and flexibility, and the glass crack progresses. A transparent substrate that can be significantly prevented can be obtained.

It is a schematic sectional drawing of the transparent substrate in preferable embodiment of this invention.

<A. Overview of transparent substrate>
FIG. 1 is a schematic cross-sectional view of a transparent substrate according to a preferred embodiment of the present invention. The transparent substrate 100 includes an inorganic glass 10 and resin layers 20 and 20 ′ disposed on one side or both sides (both sides in the illustrated example) of the inorganic glass 10. The resin layers 20 and 20 ′ include first thermoplastic resin layers 21 and 21 ′ and second thermoplastic resin layers 22 and 22 ′, respectively.

  The first thermoplastic resin layers 21 and 21 ′ are respectively formed directly on the inorganic glass 10 (that is, without using an adhesive or a pressure-sensitive adhesive), and are formed on the first thermoplastic resin layers 21 and 21 ′. Furthermore, the second thermoplastic resin layers 22 and 22 'are directly formed (that is, without using an adhesive or a pressure-sensitive adhesive). The first thermoplastic resin layers 21, 21 ′ obtained by applying a first casting solution containing a first thermoplastic resin having a terminal hydroxyl group and an epoxy-based end coupling agent are directly applied to the inorganic glass 10. By forming each of the resin layers 20 and 20 ′ so as to be formed, the inorganic glass and the resin layer can be formed even in a high-temperature and high-humidity environment as compared with the case where the resin layer is formed on the inorganic glass via an adhesive or a pressure-sensitive adhesive. In addition, a transparent substrate is obtained that is excellent in adhesion to the substrate and that is less prone to cracks during cutting.

  The epoxy-based end coupling agent is preferably chemically bonded (typically a covalent bond) to the inorganic glass. As a result, a transparent substrate having excellent adhesion between the inorganic glass and the first thermoplastic resin layer can be obtained.

  The total thickness of the transparent substrate can be set to any appropriate value depending on the configuration. Preferably it is 150 micrometers or less, More preferably, it is 140 micrometers or less, Most preferably, they are 80 micrometers-130 micrometers. According to the present invention, by forming the first thermoplastic resin layer and the second thermoplastic resin layer as described above, the thickness of the inorganic glass can be made much thinner than the conventional glass substrate. . That is, since the resin layer including the first thermoplastic resin layer and the second thermoplastic resin layer can contribute to improvement in impact resistance and toughness even if it is thin, it is lightweight and thin and has excellent impact resistance. A transparent substrate having properties can be obtained. The thickness of each of the inorganic glass, the first thermoplastic resin layer, and the second thermoplastic resin layer will be described later.

  The fracture diameter when the transparent substrate is cracked and bent is preferably 50 mm or less, and more preferably 40 mm or less. When the fracture diameter is within the above range, a transparent substrate having excellent flexibility can be obtained, and the durability of the transparent substrate can be used without any practical problem.

  The haze value of the transparent substrate is preferably 10% or less, more preferably 5% or less. When the transparent substrate has such characteristics, for example, when used for a display element, good visibility can be obtained.

  The transmittance of the transparent substrate at a wavelength of 550 nm is preferably 80% or more, and more preferably 85% or more. The transparent substrate preferably has a light transmittance reduction rate of 5% or less after heat treatment at 180 ° C. for 2 hours. This is because, with such a reduction rate, a practically acceptable light transmittance can be ensured even if a heat treatment necessary for the flat panel display manufacturing process is performed.

  The surface roughness Ra of the transparent substrate (substantially, the surface roughness Ra of the second thermoplastic resin layer) is preferably 50 nm or less, more preferably 30 nm or less, and even more preferably 10 nm or less. The waviness of the transparent substrate is preferably 0.5 μm or less, more preferably 0.1 μm or less. A transparent substrate having such characteristics is excellent in quality. Such characteristics can be realized, for example, by a manufacturing method described later.

The transparent substrate preferably has dimensional stability. For example, the transparent substrate has an average linear expansion coefficient at 170 ° C. of preferably 20 ppm ° C. ⁻¹ or less, more preferably 10 ppm ° C. ⁻¹ or less. Within the above range, for example, when the transparent substrate of the present invention is used for a display element, even if it is subjected to a plurality of heat treatment steps, pixel displacement and wiring breakage / cracking are unlikely to occur.

<B. Inorganic glass>
As the inorganic glass 10 used for the transparent substrate of the present invention, any appropriate one can be adopted as long as it is plate-shaped. Examples of the inorganic glass include soda-lime glass, borate glass, aluminosilicate glass, and quartz glass according to the classification according to the composition. Moreover, according to the classification | category by an alkali component, an alkali free glass and a low alkali glass are mentioned. The content of alkali metal components (for example, Na ₂ O, K ₂ O, Li ₂ O) in the inorganic glass is preferably 15% by weight or less, and more preferably 10% by weight or less.

  The thickness of the inorganic glass is preferably 100 μm or less, more preferably 20 μm to 90 μm, and particularly preferably 30 μm to 80 μm. In this invention, the thickness of inorganic glass can be made thin by having the resin layer containing the 1st thermoplastic resin layer and the 2nd thermoplastic resin layer in the one side or both sides of inorganic glass.

The transmittance of the inorganic glass at a wavelength of 550 nm is preferably 85% or more. The refractive index _ng of the inorganic glass at a wavelength of 550 nm is preferably 1.4 to 1.65.

The density of the inorganic glass is preferably ^{2.3g / cm 3 ~3.0g / cm 3} , more preferably from ^{2.3g / cm 3 ~2.7g / cm 3} . If it is the inorganic glass of the said range, a lightweight transparent substrate will be obtained.

  Arbitrary appropriate methods may be employ | adopted for the shaping | molding method of the said inorganic glass. Typically, the inorganic glass is a mixture of a main raw material such as silica or alumina, an antifoaming agent such as sodium nitrate or antimony oxide, and a reducing agent such as carbon at a temperature of 1400 ° C to 1600 ° C. Then, after forming into a thin plate shape, it is produced by cooling. Examples of the method for forming the inorganic glass sheet include a slot down draw method, a fusion method, and a float method. The inorganic glass formed into a plate shape by these methods may be chemically polished with a solvent such as hydrofluoric acid, if necessary, in order to reduce the thickness or improve the smoothness.

  As the inorganic glass, a commercially available one may be used as it is, or a commercially available inorganic glass may be polished to have a desired thickness. Examples of commercially available inorganic glasses include “7059”, “1737” or “EAGLE 2000” manufactured by Corning, “AN100” manufactured by Asahi Glass, “NA-35” manufactured by NH Techno Glass, and “OA-” manufactured by Nippon Electric Glass. 10 ”,“ D263 ”or“ AF45 ”manufactured by Schott Corporation.

<C. Resin layer>
The resin layers 20 and 20 ′ are formed on one side or both sides of the inorganic glass 10. The resin layers 20, 20 ′ include first thermoplastic resin layers 21, 21 ′ and second thermoplastic resin layers 22, 22 ′, respectively, and the first thermoplastic resin layer on the inorganic glass 10. The layers 21 and 21 ′ and the second thermoplastic resin layers 22 and 22 ′ are stacked in this order. The second thermoplastic resin layers 22 and 22 ′ may be a single layer or a plurality of layers. When the transparent substrate of the present invention includes the resin layers 20 and 20 ′ on both sides of the inorganic glass 10, the resin layers 20 and 20 ′ may be the same laminate or different laminates. Further, only the first thermoplastic resin layer may be the same, or only the second thermoplastic resin layer may be the same. Preferably, the resin layers 20 and 20 ′ are the same laminate.

  The thickness of each of the resin layers 20 and 20 'is preferably 50 μm or less.

<C-1. First thermoplastic resin layer>
The first thermoplastic resin layers 21 and 21 ′ are formed by directly applying the first casting solution to one side or both sides of the inorganic glass 10. The said 1st casting solution contains the 1st thermoplastic resin which has a hydroxyl group at the terminal, and an epoxy-type terminal coupling agent. When the first thermoplastic resin layers 21 and 21 ′ are arranged on both sides of the inorganic glass 10, the first thermoplastic resin layers 21 and 21 ′ may be configured with the same composition or different compositions. It may be constituted by. Preferably, each first thermoplastic resin layer 21, 21 ′ is configured with the same composition.

  The thickness of the first thermoplastic resin layers 21, 21 ′ is preferably 20 μm or less. By setting the thickness of the first thermoplastic resin layer in the above range, sufficient adhesion between the inorganic glass and the second thermoplastic resin layer can be obtained even in a high temperature and high humidity environment. The thickness of the first thermoplastic resin layers 21, 21 ′ is more preferably 0.001 μm to 20 μm, still more preferably 0.001 μm to 15 μm, and particularly preferably 0.01 μm to 10 μm. If it is said preferable range, the transparent substrate which satisfies sufficient transparency can be obtained. When the first thermoplastic resin layers 21 and 21 'are arranged on both sides of the inorganic glass 10, the thicknesses of the first thermoplastic resin layers 21 and 21' may be the same or different. Preferably, the first thermoplastic resin layers 21 and 21 'have the same thickness. Therefore, the first thermoplastic resin layers 21 and 21 ′ arranged on both sides of the inorganic glass 10 are particularly preferably configured to have the same composition and the same thickness.

The transmittance of the first thermoplastic resin layer at a wavelength of 550 nm is preferably 80% or more. The refractive index (n _r ) at a wavelength of 550 nm of the first thermoplastic resin layer is preferably 1.3 to 1.7.

  The elastic modulus of the first thermoplastic resin layer is preferably 1 GPa or more, and more preferably 1.5 GPa or more. By setting it as the above range, even when the inorganic glass is thinned, the resin layer relieves local stress in the tearing direction to the defects at the time of deformation, so that the inorganic glass is less likely to be cracked or broken.

The fracture toughness of the first thermoplastic resin layer is preferably ^{1MPa · m 1/2 ~10MPa · m 1/2} , still preferably are ^{2MPa · m 1/2 ~6MPa} · m 1/2 .

<C-1-1. Thermoplastic resin having a hydroxyl group at the terminal>
The said 1st casting solution contains the 1st thermoplastic resin which has a hydroxyl group at the terminal. As the first thermoplastic resin, any appropriate one can be used as long as it is a thermoplastic resin having a hydroxyl group at the terminal. Specific examples of the first thermoplastic resin include thermoplastic resins obtained by modifying the terminal hydroxyl group of polyimide, polyimideamide, polyethersulfone, polyetherimide, polysulfone, polyarylate, polycarbonate or the like. These thermoplastic resins can be used alone or in admixture of two or more. If such a thermoplastic resin is used, a resin layer having excellent adhesion to inorganic glass and excellent toughness can be obtained even in a high temperature and high humidity environment. If a resin layer having excellent toughness is used in this way, it is possible to obtain a transparent substrate in which cracks at the time of cutting hardly progress. In addition, arbitrary appropriate methods may be used for the said terminal hydroxyl group modification | denaturation.

  The polymerization degree of the thermoplastic resin having a hydroxyl group at the terminal is preferably 90 to 6200, more preferably 130 to 4900, and particularly preferably 150 to 3700.

The weight average molecular weight of the thermoplastic resin having a hydroxyl group at the terminal is preferably 2.0 × 10 ^{4 to} 150 × 10 ⁴ and more preferably 3.0 × 10 ^{4 to} 120 × 10 ^{4 in} terms of polyethylene oxide. and particularly preferably from ^{3.5 × 10 4 ~90 × 10 4} . If the weight average molecular weight of the thermoplastic resin having a hydroxyl group at the terminal is less than 2.0 × 10 ⁴ , the thermoplastic resin layer may have insufficient toughness and the effect of reinforcing the inorganic glass may be insufficient. Yes, if it exceeds 150 × 10 ⁴ , the viscosity becomes too high and the handling property may be deteriorated.

  The glass transition temperature of the thermoplastic resin having a hydroxyl group at the terminal is preferably 150 ° C to 350 ° C, more preferably 180 ° C to 320 ° C, and particularly preferably 210 ° C to 290 ° C. If it is such a range, the transparent substrate excellent in heat resistance can be obtained.

  A commercially available product may be used as the first thermoplastic resin having a hydroxyl group at the terminal. Examples of the thermoplastic resin having a phenolic hydroxyl group at a commercially available terminal include “Sumika Excel 5003P” manufactured by Sumitomo Chemical Co., Ltd.

  The hydroxyl group at the end of the first thermoplastic resin is preferably a phenolic hydroxyl group. When the first thermoplastic resin has a phenolic hydroxyl group at the terminal, a strong interaction with the epoxy-based terminal coupling agent contained in the first thermoplastic resin layer can be obtained.

  The content of the hydroxyl group is preferably 0.3 or more, more preferably 0.5 to 2.0, per 100 degree of polymerization of the thermoplastic resin having a hydroxyl group at the terminal. When the content of the hydroxyl group is within such a range, an excellent interaction with the epoxy-based end coupling agent can be obtained.

<C-1-2. Epoxy terminal coupling agent>
The first casting solution includes an epoxy-based end coupling agent. It is speculated that the epoxy group in the epoxy-based end coupling agent can chemically bond or interact with the first thermoplastic resin, and the silyl group in the epoxy-based end coupling agent has the inorganic glass. Since it can be chemically bonded to a substituent (for example, a hydroxyl group), the first thermoplastic resin layer is also excellent in adhesion to the inorganic glass. As a result, the transparent substrate of the present invention has improved adhesion between the inorganic glass and the first thermoplastic resin layer, and has excellent adhesion even in a high temperature and high humidity environment.

  Any appropriate epoxy terminal coupling agent can be used. Specific examples include 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane. Etc.

  A commercially available product may be used as the epoxy-based end coupling agent. Examples of commercially available epoxy-based end coupling agents include trade name “KBM-303” (2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane), trade name “KBM-403” manufactured by Shin-Etsu Chemical Co., Ltd. (3-glycidoxypropyltrimethoxysilane), trade name “KBE-402” (3-glycidoxypropylmethyldiethoxysilane), trade name “KBE-403” (3-glycidoxypropyltriethoxysilane) Etc.

  The content of the epoxy-based end coupling agent is preferably 10 to 50 parts by weight, more preferably 15 to 40 parts by weight with respect to 100 parts by weight of the first thermoplastic resin. More preferably, it is 20 to 35 parts by weight. By making content of an epoxy type terminal coupling agent into said range, the adhesiveness of inorganic glass and a resin layer can fully be improved. Furthermore, even if the total thickness of the transparent substrate is increased, a transparent substrate having a desired haze value can be obtained.

<C-1-3. Cyclic ether compound, compound in which cyclic part of cyclic ether compound is opened>
The first casting solution preferably further includes a cyclic ether compound and / or a compound in which a cyclic portion of the cyclic ether compound is opened. If the cyclic ether compound and / or the compound in which the cyclic portion of the cyclic ether compound is opened, the first thermoplastic resin layer and the inorganic glass can be stably adhered, so that the transparent substrate can be obtained with a high yield. Can be obtained.

  Any appropriate compound can be used as the cyclic ether compound, for example, a 4-membered cyclic ether compound such as oxetanes, a 5-membered cyclic ether compound such as tetrahydrofuran, or a 6-membered ring such as tetrahydropyrans. Examples include cyclic ether compounds and epoxies. As the compound in which the cyclic portion of the cyclic ether compound is opened, those obtained by opening any appropriate cyclic ether compound can be used, and examples thereof include compounds obtained by opening the cyclic ether compound. Any appropriate method can be used for the ring-opening method of the cyclic ether compound.

  Any appropriate epoxy can be used as long as it has an epoxy group in the molecule. Examples of the epoxies include bisphenol types such as bisphenol A type, bisphenol F type, bisphenol S type and water additives thereof; novolak types such as phenol novolak type and cresol novolak type; triglycidyl isocyanurate type and hydantoin type. Nitrogen-containing ring type such as alicyclic type; aliphatic type; aromatic type such as naphthalene type and biphenyl type; glycidyl type such as glycidyl ether type, glycidyl amine type and glycidyl ester type; dicyclo such as dicyclopentadiene type Examples include epoxy resins such as types; ester types; ether ester types; and modified types thereof. These epoxy resins can be used alone or in admixture of two or more. Preferably, the epoxy is a bisphenol A type epoxy resin, an alicyclic type epoxy resin, a nitrogen-containing ring type epoxy resin, or a glycidyl type epoxy resin. Moreover, you may use the epoxy-type prepolymer currently disclosed by Unexamined-Japanese-Patent No. 2008-107510.

  The oxetanes are preferably compounds represented by the following general formula (I), (II), or (III).

In the above formula (I), _{R 1} represents a hydrogen atom, a cycloalkyl group, a phenyl group, a naphthyl group, an alkyl group having 1 to 10 carbon atoms.

In the above formula (III), _{R 2} represents a cycloalkyl group, a phenyl group, a naphthyl group, an alkyl group having 1 to 10 carbon atoms. n is an integer from 1 to 5.

  Examples of the oxetanes include 3-ethyl-3-hydroxymethyloxetane (oxetane alcohol), 2-ethylhexyl oxetane, xylylene bisoxetane, 3-ethyl-3 {[((3-ethyloxetane-3-yl). ) Methoxy] methyl} oxetane.

  A commercially available product may be used as the compound in which the cyclic portion of the cyclic ether compound and / or the cyclic ether compound is opened. Examples of the commercially available cyclic ether compound and / or the compound in which the cyclic portion of the cyclic ether compound is opened include, for example, Aron Oxetane OXT-221 manufactured by Toagosei Co., Ltd. HP4032 etc. are mentioned.

  The content of the cyclic ether compound and / or the compound in which the cyclic portion of the cyclic ether compound is opened is preferably 5 to 50 parts by weight, more preferably 5 parts by weight with respect to 100 parts by weight of the first thermoplastic resin. Part to 30 parts by weight, more preferably 5 parts to 20 parts by weight. By setting the content of the cyclic ether compound and / or the compound in which the cyclic portion of the cyclic ether compound is opened in the above range, coloring of the resin layer derived from the cyclic ether compound under heating can be suppressed.

  The first thermoplastic resin layer may further contain any appropriate additive depending on the purpose. Examples of the additives include diluents, anti-aging agents, denaturing agents, surfactants, dyes, pigments, anti-discoloring agents, ultraviolet absorbers, softeners, stabilizers, plasticizers, antifoaming agents, reinforcing agents, and the like. Is mentioned. The kind, number, and amount of additives contained in the resin composition can be appropriately set depending on the purpose.

<C-2. Second thermoplastic resin layer>
The second thermoplastic resin layers 22 and 22 ′ are formed by applying a second casting solution on the first thermoplastic resin layers 21 and 21 ′, respectively. The second casting solution includes a second thermoplastic resin. When the second thermoplastic resin layers 22 and 22 ′ are arranged on both sides of the inorganic glass 10, the respective second thermoplastic resin layers 22 and 22 ′ may be configured with the same composition and different compositions. It may be constituted by. Preferably, each 2nd thermoplastic resin layer is comprised with the same thermoplastic resin. The second thermoplastic resin layers 22 and 22 ′ may be a single layer or a plurality of layers. When the second thermoplastic resin layers 22 and 22 ′ are a plurality of layers, the plurality of layers may be formed of the same resin composition or different resin compositions.

  The thickness of the second thermoplastic resin layer is preferably 5 μm to 60 μm, more preferably 20 μm to 50 μm, and still more preferably 20 μm to 40 μm. When the second thermoplastic resin layers 22 and 22 'are arranged on both sides of the transparent substrate, the thicknesses of the second thermoplastic resin layers 22 and 22' may be the same or different. Preferably, the second thermoplastic resin layers 22 and 22 'have the same thickness. Therefore, the second thermoplastic resin layers 22 and 22 'disposed on both sides of the inorganic glass 10 are particularly preferably configured to have the same composition and the same thickness. With such a configuration, even when heat treatment is performed, thermal stress is evenly applied to both surfaces of the inorganic glass, and thus warpage and undulation are extremely unlikely to occur.

  As the second thermoplastic resin, any appropriate one can be used as long as it is compatible with the first thermoplastic resin. Specifically, polyethersulfone resins, polycarbonate resins, epoxy resins, acrylic resins, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefin resins, cycloolefin resins such as norbornene resins, Examples include polyimide resins, polyamide resins, polyimide amide resins, polyarylate resins, polysulfone resins, and polyetherimide resins.

  The glass transition temperature of the second thermoplastic resin is preferably 150 ° C to 350 ° C, more preferably 170 ° C to 330 ° C, and further preferably 190 ° C to 300 ° C. If it is such a range, the transparent substrate excellent in heat resistance can be obtained.

  The elastic modulus at 25 ° C. of the second thermoplastic resin layer is preferably 1.5 GPa to 10 GPa, more preferably 1.8 GPa to 9 GPa, and further preferably 2 GPa to 8 GPa. In such a range, even when the inorganic glass is thinned, the second thermoplastic resin layer relaxes local stress in the tearing direction to defects at the time of deformation. Is less likely to occur.

The fracture toughness value at 25 ° C. of the second thermoplastic resin layer is preferably 1.5 Mpa · m ^{1/2 to} 10 Mpa · m ^1/2 , more preferably ² Mpa · m ^{1/2 to} 8 Mpa · m. It is ^1/2 , and particularly preferably 2.5 Mpa · m ^{1/2 to} 6 Mpa · m ^1/2 . If it is such a range, since the second thermoplastic resin contained in the second thermoplastic resin layer has a sufficient viscosity, the inorganic glass is prevented from progressing and breaking, and has a good flexibility. A substrate can be obtained. If the fracture toughness value at 25 ° C. of the second thermoplastic resin layer is 1.5 Mpa · m ^1/2 or more, high flexibility can be realized. Usually, the upper limit of the fracture toughness value is 10 Mpa · m m ^1/2 .

The transmittance of the second thermoplastic resin layer at a wavelength of 550 nm is preferably 80% or more. The refractive index (n _r ) at a wavelength of 550 nm of the second thermoplastic resin layer is preferably 1.3 to 1.7.

  The second thermoplastic resin layer preferably has chemical resistance. Specifically, it is preferable to have chemical resistance against a solvent used in a cleaning process or the like when manufacturing a display element. Acetone is mentioned as a solvent used for the washing | cleaning process at the time of display element preparation.

  The second thermoplastic resin layer may further contain any appropriate additive depending on the purpose. Examples of the additive include the same additives as those that can be used for the first thermoplastic resin layer. The kind, number, and amount of additives contained in the resin composition can be appropriately set depending on the purpose.

<D. Other layers>
The transparent substrate 100 of the present invention may be further provided with any appropriate layer on the opposite side of the resin layers 20 and 20 ′ from the inorganic glass 10 (on the second resin layers 22 and 22 ′). And a transparent conductive layer and a hard coat layer.

  The transparent conductive layer is used for functioning as an electrode or an electromagnetic wave shield when the transparent substrate of the present invention is used as a substrate for a display element or a solar cell. Any appropriate material can be used as the material used for the transparent conductive layer. Specific examples include metals such as copper and silver, metal oxides such as ITO (indium tin oxide) and IZO (indium zinc oxide), conductive polymers such as polythiophene and polyaniline, and materials such as carbon nanotubes. It is done.

  The hard coat layer can impart scratch resistance and surface smoothness to the transparent substrate. Arbitrary appropriate things can be used as a material used for a hard-coat layer, and its formation method. Examples of the material include an epoxy resin, an acrylic resin, a silicone resin, and a mixture thereof. As a formation method of a hard-coat layer, the method of hardening said resin with a heat | fever or an active energy ray is mentioned, for example.

<E. Manufacturing method of transparent substrate>
The transparent substrate 100 of the present invention can be manufactured by any appropriate method. For example, the step of directly applying the first casting solution on one side of the inorganic glass 10 to form the first thermoplastic resin layer 21, and the above on the first thermoplastic resin layer 21, A step of directly applying the second casting solution to form the second thermoplastic resin layer 22 is included. When the transparent substrate 100 has the resin layers 20 and 20 ′ on both sides of the inorganic glass, the first casting solution is directly applied to the other surface of the inorganic glass, and the first thermoplastic resin layer 21 is applied. And a step of directly applying the second casting solution on the first thermoplastic resin layer 21 ′ to form a second thermoplastic resin layer 22 ′.

  The first thermoplastic resin layers 21 and 21 ′ are formed by using a first casting solution containing a first thermoplastic resin having a hydroxyl group at the terminal and an epoxy terminal coupling agent on one or both sides of the inorganic glass 10. The coating step comprises coating a coating layer to form a coating layer, a drying step for drying the coating layer, and a heat treatment step for heat-treating the coating layer after drying. The first casting solution preferably further contains a cyclic ether compound and / or a compound in which the cyclic portion of the cyclic ether compound is opened. In the first casting solution, the content of the first thermoplastic resin having a hydroxyl group at the terminal, the epoxy-based terminal coupling agent, and the cyclic ether compound and / or the compound in which the cyclic portion of the cyclic ether compound is opened is as described above. It is as follows.

  Examples of the coating solvent used in the coating step include ketone solvents, halogen solvents, aromatic solvents, highly polar solvents, and mixtures thereof. Examples of the ketone solvent include methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone. Examples of the halogen solvent include methylene chloride, ethylene chloride, chloroform, carbon tetrachloride, trichloroethane, and the like. Examples of the aromatic solvent include toluene, xylene, benzene, phenol and the like. Examples of the highly polar solvent include dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, ethyl acetoacetate and the like.

  Any appropriate method can be used as the first casting solution coating method, such as air doctor coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, Coating methods such as cast coating, spray coating, slot orifice coating, calendar coating, electrodeposition coating, dip coating, and die coating; relief printing methods such as flexographic printing; intaglio printing methods such as direct gravure printing methods and offset gravure printing methods; Examples of the printing method include a lithographic printing method such as an offset printing method and a stencil printing method such as a screen printing method.

  The first thermoplastic resin layer is preferably obtained by applying the first casting solution and then drying the application layer. Any appropriate drying method (for example, natural drying, air drying, heat drying) may be employed as the drying method. For example, in the case of heat drying, the drying temperature is typically 100 ° C. to 200 ° C., and the drying time is typically 1 to 30 minutes. While being dried, the epoxy-based end coupling agent and the first thermoplastic resin having a hydroxyl group at the terminal can be reacted.

  Any appropriate heat treatment method can be adopted as the heat treatment method for the first thermoplastic resin layer. Typically, the heat treatment temperature is 50 ° C. to 180 ° C., and the heat treatment time is 1 to 20 minutes. By the heat treatment, the epoxy group terminal coupling agent and the inorganic glass surface can be bonded by chemical bonding.

  Next, the second casting solution is directly applied onto the first thermoplastic resin layers 21 and 21 ′ formed by the above-described method, thereby forming the second thermoplastic resin layers 22 and 22 ′. . The second thermoplastic resin layers 22 and 22 'can be formed using a method similar to the method for forming the first thermoplastic resin layers 21 and 21'. Specifically, the second thermoplastic resin layers 22 and 22 ′ are formed by applying a second casting solution containing the second thermoplastic resin on the first thermoplastic resin layers 21 and 21 ′. It comprises a coating step for forming a coating layer by coating and a drying step for drying the coating layer. Since the coating process is the same as described above, detailed description thereof is omitted.

  As a method for drying the second thermoplastic resin layer, any appropriate drying method (for example, natural drying, air drying, heat drying) may be employed. For example, in the case of heat drying, the drying temperature is typically 80 ° C. to 150 ° C., and the drying time is typically 1 to 30 minutes.

  In the method for producing a transparent substrate of the present invention, preferably, the formed first thermoplastic resin layers 21, 21 ′ and the second thermoplastic resin layers 22, 22 ′, that is, the resin layers 20 and 20 ′ are further added. A drying step of drying and a heat treatment step of heat treating the resin layers 20 and 20 ′ after drying are included. By including these steps, the chemical bond or interaction between the inorganic glass, the first thermoplastic resin layer, and the second thermoplastic resin layer can be further strengthened. As the drying method, any appropriate method described above can be adopted. In the case of the heat drying method, the drying temperature is typically 100 ° C. to 200 ° C., and the drying time is typically 1 to 30 minutes. It is. Any appropriate heat treatment method can be adopted as the heat treatment method. Typically, the heat treatment temperature is 50 ° C. to 180 ° C., and the heat treatment time is 1 to 20 minutes.

  The method for producing a transparent substrate of the present invention further includes a step of forming any appropriate other layer on the second thermoplastic resin layers 22 and 22 'according to the use. Examples of other layers include the transparent conductive layer and the hard coat layer exemplified in the above section D. Any appropriate method can be used as a method of forming other layers.

<F. Application>
The transparent substrate of the present invention can be suitably used for display elements such as liquid crystal display devices, organic EL displays and plasma displays, and lighting elements such as solar cells and organic EL elements. Further, since the transparent substrate of the present invention is excellent in flexibility, flexibility and impact resistance, it can be suitably used for a film-shaped display element, a solar cell, and a lighting element.

  The present invention will be further described using the following examples and comparative examples. The present invention is not limited only to these examples. The thickness was measured using an Anritsu digital micrometer “KC-351C type”.

[Example 1]
Polyethersulfone having a hydroxyl group at the terminal (Sumika Excel 5003P, manufactured by Sumitomo Chemical Co., Ltd.) 36.2 g was dissolved in a mixed solvent of 172 g of cyclopentanone and 10.8 g of N, N-dimethylformamide. A solution containing 16.5% by weight of ether sulfone was obtained. To the resulting solution, 0.027 g of a leveling agent (BYK307, manufactured by Big Chemie), 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate (Celoxide 2021P, manufactured by Daicel Chemical Industries) 81 g, 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane (Aron oxetane OXT-221, manufactured by Toagosei Co., Ltd.) 1.45 g, 1.09 g of 2-methylimidazole, epoxy type 9.05 g of end coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added to obtain a first casting solution.
One surface of an inorganic glass (thickness: 50 μm, length 10 cm × width 4 cm) is washed with methyl ethyl ketone, then treated with corona, coated with the first casting solution, dried at 100 ° C. for 10 minutes, and further at 170 ° C. A heat treatment was performed for 20 minutes to form a first thermoplastic resin layer having a thickness of 1 μm. The same treatment was performed on the other surface to form a first thermoplastic resin layer.
90 g of polyarylate (M-4000, manufactured by Unitika) was dissolved in 600 g of cyclopentanone to obtain a second casting solution. The obtained second casting solution was applied onto the first thermoplastic resin layer and dried at 90 ° C. for 15 minutes. Furthermore, the second casting solution was also applied onto the first thermoplastic resin layer on the other side and dried at 85 ° C. for 10 minutes. Subsequently, both surfaces were dried at 130 ° C. for 10 minutes, and further heat-treated at 170 ° C. for 20 minutes to form a second thermoplastic resin layer having a thickness of 36.5 μm on one side. The total thickness of the obtained transparent substrate was 125 μm.

[Example 2]
A transparent substrate having a total thickness of 125 μm was obtained in the same manner as in Example 1 except that polyarylate 2 (U-100, manufactured by Unitika) was used instead of polyarylate 1 (M-4000, manufactured by Unitika). Obtained.

[Example 3]
A transparent substrate having a total thickness of 143 μm was obtained in the same manner as in Example 1 except that the thickness of the first thermoplastic resin layer was 10 μm.

[Comparative Example 1]
Except for using polyethersulfone having a hydroxyl group at the end (Sumika Excel 5003P, manufactured by Sumitomo Chemical Co., Ltd.), using polyethersulfone having no hydroxyl group at the end (Sumika Excel 5200P, manufactured by Sumitomo Chemical Co., Ltd.) In the same manner as in Example 1, a laminate having a total thickness of 125 μm was obtained.

[Comparative Example 2]
The total thickness was the same as in Example 1 except that an amino group-containing coupling agent (KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was used instead of the epoxy-based end coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.). Obtained a laminate having a thickness of 125 μm.

[Reference Example 1]
90 g of polyarylate 1 (M-4000, manufactured by Unitika Co., Ltd.) was dissolved in 600 g of methylene chloride, and a casting solution added with 0.0675 g of a leveling agent (BYK307, manufactured by Big Chemie) was obtained.
One surface of an inorganic glass (thickness: 50 μm, length 10 cm × width 4 cm) is washed with methyl ethyl ketone, then subjected to corona treatment, and an amino group-containing coupling agent (KBM-603, manufactured by Shin-Etsu Chemical Co., Ltd.) is applied at 110 ° C. And dried for 10 minutes. The above-mentioned casting solution was applied on the inorganic glass subjected to the coupling treatment, and dried at 40 ° C. for 15 minutes. Similarly, the other surface was subjected to a coupling treatment, and the casting solution was applied and dried at 40 ° C. for 10 minutes. Next, both surfaces were dried at 60 ° C. for 10 minutes and at 110 ° C. for 20 minutes, and then heat-treated at 200 ° C. for 20 minutes to obtain a laminate having a total thickness of 125 μm.

（６）ガラス転移温度
各実施例、比較例、および参考例で用いた第２の熱可塑性樹脂を用いて、セイコーインスツールメンツ社製ＤＳＣ「Ｅｘｓｔａｒ６０００ ＤＳＣ６２２０」を用いて、ピーク値からガラス転移温度を求めた。 <Evaluation>
The following methods evaluated the 2nd thermoplastic resin layer used by the said Example, the comparative example, and the reference example, the transparent substrate obtained above, and a laminated body. The results are shown in Table 1.
(1) Adhesion test It evaluated by the cross-cut peel test of JISK5400. That is, after cutting with a cutter at 1 mm intervals in a 10 mm square on the surface of the resin layer side (the surface of the second thermoplastic resin), making 100 grids, and sticking an adhesive tape thereon, The adhesion was evaluated by the number of grids of the resin layer that was peeled off and peeled from the inorganic glass.
The transparent substrates obtained in the examples and the laminates obtained in the comparative examples and the reference examples are placed in an environment of a temperature of 60 ° C. and a humidity of 90% for 500 hours. Adhesion was evaluated by an eye peel test.
In the case where the number of grids of the peeled resin layer is 0, the mark is “◯”, and in the case where the number is 1 or more, the mark is “X”.
(2) Breaking diameter (a) The transparent substrates obtained in Examples and the laminates obtained in Comparative Examples and Reference Examples were prepared as evaluation samples.
(B) A crack of 5 mm or less was made in the center of the edge of the vertical side of the exposed portion of the inorganic glass.
(C) Bending the vertical side of the sample for evaluation and breaking the diameter of the circle whose circumference is the vertical side when the crack progresses through the exposed portion of the inorganic glass and further progresses 1 cm in the laminated region of the resin or the like. The diameter.
(3) Haze Using a haze meter “HM-150” manufactured by Murakami Color Research Laboratory Co., Ltd., based on JIS K7136, transparent substrates obtained in Examples, and laminates obtained in Comparative Examples and Reference Examples The haze value was measured.
(4) Elastic modulus Using a product name “Tribo Indenter” manufactured by Hystron, Inc., a single indentation measurement of the second thermoplastic resin layer at a temperature of 25 ° C. (indentation factor: Berkovich (triangular pyramid), indentation depth: 230-280 nm).
(5) Fracture toughness value Using the second thermoplastic resin used in each example, comparative example, and reference example, a strip-shaped resin sample having a thickness of 50 μm, a width of 2 cm, and a length of 15 cm was prepared, and the longitudinal direction of the strip Cracks (5 mm) were made at the end (center portion) of the. A tensile stress was applied in the longitudinal direction of the strip by an autograph (manufactured by Shimadzu Corporation, AG-I), and the stress at the time of resin rupture from a crack at a temperature of 25 ° C. was measured. Test conditions were such that the distance between chucks was 10 cm and the pulling speed was 10 mm / min. The obtained tensile stress σ at break, crack length a, and sample width b were substituted into the following formula to determine the fracture toughness value K _IC at break.

(6) Glass transition temperature Using the second thermoplastic resin used in each example, comparative example, and reference example, using DSC “Exstar6000 DSC6220” manufactured by Seiko Instruments Inc., the glass transition temperature from the peak value. Asked.

[Evaluation]
The transparent substrates of Examples 1 to 3 have excellent adhesion between the inorganic glass and the resin layer even after being placed in an environment of high temperature and high humidity (temperature: 60 ° C., humidity: 90%) for 500 hours. It was. Furthermore, these transparent substrates are less prone to cracking and breaking, and the haze value is also suppressed.

  In the laminates of Comparative Examples 1 and 2, the inorganic glass and the resin layer were peeled off before being placed in a high temperature and high humidity environment. Furthermore, since the inorganic glass is broken, the fracture diameter and haze could not be measured. The laminate of Reference Example 1 had excellent adhesion before being placed in a high-temperature and high-humidity environment, but after being placed in a high-temperature and high-humidity environment for 500 hours, the inorganic glass and the resin layer were separated. It peeled. Furthermore, since the inorganic glass is broken, the fracture diameter and haze could not be measured.

  The transparent substrate of the present invention can be suitably used for display elements such as liquid crystal display devices, organic EL displays and plasma displays, and lighting elements such as solar cells and organic EL elements.

DESCRIPTION OF SYMBOLS 10 Inorganic glass 20,20 'Resin layer 21,21' 1st thermoplastic resin layer 22,22 '2nd thermoplastic resin layer 100 Transparent substrate

Claims (12)

An inorganic glass having a thickness of 100 μm or less ;
A transparent substrate comprising a resin layer formed by applying a thermoplastic resin solution on one or both sides of the inorganic glass,
The resin layer is first thermoplastic resin layer obtained by applying a first casting solution onto the inorganic glass, and a second casting solution comprising a second thermoplastic resin the the second thermoplastic resin layer obtained by coating on the first thermoplastic resin layer seen including,
The first casting solution includes a first thermoplastic resin having a hydroxyl group at a terminal, an epoxy-based terminal coupling agent, and a cyclic ether compound and / or a compound in which a cyclic portion of the cyclic ether compound is opened,
The content of the cyclic ether compound and / or the compound in which the cyclic portion of the cyclic ether compound is opened is 5 to 50 parts by weight with respect to 100 parts by weight of the first thermoplastic resin.
Transparent substrate.   The transparent substrate according to claim 1, wherein the content of the epoxy-based end coupling agent is 10 to 50 parts by weight with respect to 100 parts by weight of the first thermoplastic resin. Total thickness is 150μm or less, the transparent substrate according to claim 1 or 2. The transparent substrate in any one of Claim 1 to 3 whose thickness of a said 1st thermoplastic resin layer is 20 micrometers or less. The transparent substrate in any one of Claim 1 to 4 whose glass transition temperature of a said 2nd thermoplastic resin is 150 to 350 degreeC. The transparent substrate in any one of Claim 1 to 5 whose elasticity modulus in 25 degreeC of a said 2nd thermoplastic resin layer is 1.5GPa-10GPa. The fracture toughness value at 25 ° C. of the second thermoplastic resin layer is ^{1.5MPa · m 1/2 ~10MPa · m 1/2} , the transparent substrate according to any one of claims 1 to 6. The transparent substrate according to any one of claims 1 to 7 , wherein a fracture diameter when the transparent substrate is cracked and bent is 50 mm or less. The transparent substrate in any one of Claim 1 to 8 used for a solar cell, a display element, or a lighting element. Using a transparent substrate according to any one of claims 1 to 9, the display element. A transparent substrate using a solar battery according to any one of claims 1-9. To any one of claims 1 to 9 using a transparent substrate, wherein the illumination device.

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