Transparent sheet

Abstract

To provide a transparent sheet which suppresses a decrease in visibility when viewed through the transparent sheet, in particular, when viewed from an oblique direction while increasing a use rate of a recycled raw material or a plant-derived raw material in a transparent resin composite of a glass fiber and a resin.SOLUTION: A transparent sheet comprising a glass fiber fabric and a cured resin layer contained in the glass fiber fabric in an impregnated state, wherein a film layer that is a film containing a regenerated polyester resin or a film containing a biomass polyester resin is laminated on at least one surface side of the cured resin layer, the transparent sheet has a total light transmittance of 80% or more and a haze of 30% or less, and the transparent sheet has a b value of - 2.3 to 2.3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a transparent sheet. [Background technology]

[0002] The Building Standards Act and its Enforcement Order stipulate that smoke exhaust systems must be installed to prevent the flow of smoke, toxic gases, etc. that are generated in the event of a fire in a building, and to facilitate evacuation and firefighting activities. Therefore, office buildings, commercial facilities, and other buildings often have smoke exhaust systems and smoke barriers such as vertical smoke barriers installed.

[0003] Hanging smoke barriers are usually attached to the ceilings of buildings to temporarily block the flow of smoke, toxic gases, etc. into corridors or upper floors in the event of a fire, thereby ensuring the necessary time for evacuation. Therefore, to prevent the hanging smoke barriers from obstructing visibility or spoiling the aesthetics, transparent plate glass, transparent resin composites of glass fiber and resin, etc. are used for the hanging smoke barriers. Transparent resin composites of glass fiber and resin have the advantage of being less likely to break than transparent plate glass. For example, Patent Document 1 discloses a transparent non-combustible sheet containing a glass fiber fabric and a cured resin layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-319746 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, efforts to protect the environment, such as reducing emissions of greenhouse gases (hereinafter sometimes referred to as "GHG") such as carbon dioxide, have been strengthened against the backdrop of social issues such as the depletion of fossil fuel resources and global warming. In light of this background, the present inventors have investigated the use of recycled or biomass raw materials for the transparent noncombustible sheet of Patent Document 1, which is used in hanging smoke barriers, to reduce GHG emissions.

[0006] After conducting research, the present inventors came up with the idea that the transparent non-flammable sheet of Patent Document 1 is made of cured resin and glass fiber, but by laminating a film containing recycled polyester resin or a film containing biomass polyester resin onto the cured resin layer, it would be possible to increase the usage rate of recycled or plant-derived raw materials for the entire sheet while maintaining transparency.

[0007] However, the present inventors have now encountered a new problem. Specifically, the inventors have discovered that films containing recycled polyester resins or biomass polyester resins may have inferior total light transmittance and haze compared to virgin polyester films derived from fossil fuels that do not use recycled materials, and that laminating such films to a cured resin layer may result in insufficient visibility when viewed through the transparent sheet, particularly when viewed from an oblique angle. Specifically, for example, a hanging smoke barrier is attached to the ceiling of a building, and if a transparent noncombustible sheet is used for the hanging smoke barrier, a viewer looking through the hanging smoke barrier to see the other side of the sheet will look from an oblique angle below the hanging direction of the sheet, resulting in particularly insufficient visibility.

[0008] Therefore, the main objective of the present invention is to solve the above problems and provide a transparent sheet that increases the usage rate of recycled or plant-derived raw materials in a transparent resin composite of glass fiber and resin, while suppressing a decrease in visibility when viewed through the transparent sheet, particularly when viewed from an oblique direction. [Means for solving the problem]

[0009] The inventors conducted research to solve the above-mentioned problems and discovered that in addition to total light transmittance and haze, visibility when viewed through a transparent sheet is affected by blue and yellow color bleeding, which is a type of color bleeding that occurs when light that has passed through the sheet is dispersed and becomes visible.

[0010] The inventors have found that the blue and yellow color bleeding can be controlled by adjusting the b value of the transparent sheet, and that by setting the total light transmittance and haze within specific ranges while setting the b value within specific ranges, the blue and yellow color bleeding can be suppressed, and that the use rate of recycled or plant-derived raw materials in a transparent resin composite of glass fiber and resin can be increased while suppressing a decrease in visibility when viewed through the transparent sheet. The present invention was completed based on these findings and through further investigation.

[0011] That is, the present invention provides the following aspects of the invention. Item 1. A transparent sheet comprising a glass fiber fabric and a cured resin layer impregnated in the glass fiber fabric, wherein a film layer that is a film containing a recycled polyester resin or a film containing a biomass polyester resin is laminated on at least one side of the cured resin layer, and the transparent sheet has a total light transmittance of 80% or more, a haze of 30% or less, and a b value of -2.3 to 2.3. Item 2. The transparent sheet according to Item 1, wherein the glass fiber fabric has a cover factor CF represented by the following formula (I) of 800 to 900: CF=(Dw) 1 / 2 ×W+(Df) 1 / 2 ×F (I) In the above formula, the abbreviations represent the following: Dw: Warp count (dtex) Df: Weft count (dtex) W: Warp weave density (threads / 25mm) F: Weft density (threads / 25mm) Item 3. The transparent sheet according to Item 1 or 2, wherein the ratio of the thickness of the cured resin layer to the thickness of the film layer (thickness of the cured resin layer / thickness of the film layer) is 0.9 to 1.5. Item 4. A method for producing a transparent sheet comprising a glass fiber fabric and a cured resin layer impregnated in the glass fiber fabric, wherein a film layer that is a film containing a recycled polyester resin or a film containing a biomass polyester resin is laminated on at least one side of the cured resin layer, and the transparent sheet has a total light transmittance of 80% or more, a haze of 30% or less, and a b value of -2.3 to 2.3, the method comprising the step of preparing the film layer that is the film containing the recycled polyester resin or the film containing the biomass polyester resin. [Effects of the Invention]

[0012] According to the transparent sheet of the present invention, the transparent sheet comprises a glass fiber fabric and a cured resin layer impregnated into the glass fiber fabric, and a film layer is laminated on at least one side of the cured resin layer, the film being a film containing a recycled polyester resin or a film containing a biomass polyester resin.The transparent sheet has a total light transmittance of 80% or more, a haze of 30% or less, and a b-value of -2.3 to 2.3.This makes it possible to increase the usage rate of recycled or plant-derived raw materials in a transparent resin composite of glass fiber and resin while suppressing a decrease in visibility when viewed through the transparent sheet. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view illustrating one embodiment of a transparent sheet of the present invention. [Figure 2] This is a diagram showing an outline of the test equipment used when conducting "4.9.2 Heat generation test" in the "Fire resistance performance test and evaluation procedure manual" (revised version as of July 1, 2021) of the Japan Testing Center for Construction Materials. [Figure 3]This is a schematic diagram of the test holder and clamping frame included in the testing equipment used when conducting "4.9.2 Heat Generation Test" in the "Fire Resistance Testing and Evaluation Procedures Manual" (revised July 1, 2021) of the Japan Testing Center for Construction Materials. The values ​​(dimensions) shown in Figure 4 are in mm. DETAILED DESCRIPTION OF THE INVENTION

[0014] The transparent sheet of the present invention comprises a glass fiber fabric and a cured resin layer impregnated in the glass fiber fabric, and a film layer comprising a recycled polyester resin or a biomass polyester resin is laminated on at least one side of the cured resin layer, and the transparent sheet has a total light transmittance of 80% or more, a haze of 30% or less, and a b-value of -2.3 to 2.3. The transparent sheet of the present invention will be described in detail below.

[0015] For example, as shown in FIG. 1, the transparent sheet 1 of the present invention includes a glass fiber fabric 2, a cured resin layer 3 impregnated in the glass fiber fabric 2, and a film layer 4, which is a film containing a recycled polyester resin or a film containing a biomass polyester resin, laminated on both surfaces of the cured resin layer 3.

[0016] The transparent sheet 1 of the present invention may contain at least one glass fiber fabric 2, or may contain multiple glass fiber fabrics. As shown in FIG. 1 , the cured resin layer 3 fills the gaps between the glass fibers constituting the glass fiber fabric 2, and one surface side of the cured resin layer 3 communicates with the other surface side through the gaps. To further enhance visibility, the transparent sheet 1 of the present invention preferably has the cured resin layer 3 formed on both surfaces of the glass fiber fabric 2, as shown in FIG. 1 . The transparent sheet 1 of the present invention preferably has the film layer 4 laminated on at least one surface of the cured resin layer 3, and more preferably has the film layer 4 laminated on both surfaces of the cured resin layer 3. The transparent sheet 1 of the present invention may also contain layers other than the glass fiber fabric 2, the cured resin layer 3, and the film layer 4.

[0017] (glass fiber fabric 2) In the transparent sheet 1 of the present invention, the glass fiber fabric 2 is included in a state in which it is impregnated with a cured resin layer 3, which will be described later. In the transparent sheet 1 of the present invention, the glass fiber fabric 2 contributes to increasing the mechanical strength and non-flammability of the sheet. The refractive index of the glass fiber fabric 2 can be set to be similar to the refractive index of the cured resin layer 3, which will be described later. This allows the transparent sheet 1 of the present invention to have a total light transmittance of 80% or more and a haze of 30% or less, which are indicators of transparency. In other words, the total light transmittance of 80% or more and a haze of 30% or less, which are indicators of transparency possessed by the transparent sheet 1 of the present invention, indicates that at least the refractive index of the glass fiber fabric 2 and the refractive index of the cured resin layer 3, which will be described later, are sufficiently similar (for example, the difference between the refractive index of the glass fiber fabric 2 and the refractive index of the cured resin layer 3 is 0.02 or less).

[0018] In the transparent sheet 1 of the present invention, the glass fiber fabric 2 is composed of a plurality of glass fibers. The weave of the glass fiber fabric is not particularly limited, and examples thereof include plain weave, satin weave, twill weave, basket weave, and rib weave. The weave density of the glass fiber fabric is not particularly limited, but from the viewpoint of more easily achieving both a specific b-value range for the transparent sheet 1 (described later) and enhanced flame retardancy, it is preferably 50 to 90 fibers / 25 mm, more preferably 60 to 85 fibers / 25 mm, and even more preferably 60 to 80 fibers / 25 mm.

[0019] The glass material of the glass fibers constituting the glass fiber fabric 2 is not particularly limited, and for example, known glass materials can be used. Examples of glass materials include alkali-free glass (E glass), acid-resistant alkali-containing glass (C glass), high-strength, high-elasticity glass (S glass, T glass, etc.), and alkali-resistant glass (AR glass), with the versatile alkali-free glass (E glass) being preferred. The glass fibers constituting the glass fiber fabric 2 may be made of one type of glass material or a combination of two or more types of glass fibers made of different glass materials. In addition, from the viewpoint of improving transparency, it is preferable to select a glass material whose refractive index is close to that of the cured resin layer 3 described below.

[0020] The count of the glass fibers constituting the glass fiber fabric 2 is not particularly limited as long as it can form the glass fiber fabric 2. From the viewpoint of more easily achieving both a specific b-value range for the transparent sheet 1 described below and enhanced flame retardancy, the count of the glass fibers is preferably 20 tex or less, more preferably 2 to 6 tex, more preferably 2 to 5 tex, and even more preferably 2.0 to 3.8 tex. The count of the glass fibers may be one type alone or two or more types may be combined. The tex count of the glass fibers corresponds to the number of grams per 1000 m.

[0021] The glass fibers constituting the glass fiber fabric 2 are preferably glass yarns in which a plurality of single filaments, which are long glass fibers, are twisted together. The number of single filaments in the glass yarn is preferably about 30 to 150, more preferably about 80 to 120, from the viewpoint of more easily achieving both the b-value of the transparent sheet 1 described below in a specific range and enhanced non-combustibility. The diameter of the single filaments in the glass yarn is preferably about 3.0 to 4.6 μm, more preferably about 3.0 to 4.2 μm, from the viewpoint of more easily achieving both the b-value of the transparent sheet 1 described below in a specific range and enhanced non-combustibility.

[0022] In the transparent sheet 1, the proportion (mass %) of the glass fiber fabric 2 relative to the total mass of the glass fiber fabric 2 and the cured resin layer 3 is preferably 5 to 50 mass %, more preferably 10 to 30 mass %, and particularly preferably 10 to 20 mass %, from the viewpoint of more easily achieving both the b value of the transparent sheet 1 to be described later within a specific range and increasing non-combustibility. 2 ) is 10 to 30 (g / m 2 ) is preferred, and 10 to 25 (g / m 2 ) is more preferable, and 15 to 25 (g / m 2 ) is more preferable. From the viewpoint of more easily achieving both the b value of the transparent sheet 1 described later within a specific range and increased non-combustibility, the thickness of the glass fiber fabric 2 is preferably 10 to 35 μm, more preferably 10 to 30 μm, and even more preferably 16 to 25 μm.

[0023] In the transparent sheet 1, from the viewpoint of more easily achieving both the b value of the transparent sheet 1 described below within a specific range and enhanced flame retardancy, the glass fiber fabric 2 preferably has a cover factor CF represented by the following formula (I) of 800 to 900. In other words, by setting the cover factor within the above range, it is possible to easily ensure flame retardancy while allowing a large amount of light to pass through the openings in the glass fiber fabric formed by the warp and weft yarns. CF=(Dw) 1 / 2 ×W+(Df)1 / 2 ×F (I) In the above formula, the abbreviations represent the following: Dw: Warp count (dtex) Df: Weft count (dtex) W: Warp weave density (threads / 25mm) F: Weft density (threads / 25mm)

[0024] The difference in refractive index between the glass fiber fabric 2 and the cured resin layer 3 described below is preferably 0.05 or less, more preferably 0.02 or less, and even more preferably 0.01 or less. The refractive index of the glass fiber fabric 2 is preferably about 1.45 to 1.65, and more preferably about 1.50 to 1.60.

[0025] The refractive index of the glass fiber fabric 2 is measured in accordance with the B method of JIS K 7142:2008. Specifically, the glass fibers constituting the glass fiber fabric 2 are immersed in methylene iodide (nD 23 1.747), butyl phthalate (nD 23 1.491) and dimethyl carbonate (nD 23 The refractive index of the cured resin layer 3 is measured at a temperature of 23°C using an Abbe refractometer (NAR-2T manufactured by Atago Co., Ltd.) with a wavelength of 589 nm and a sodium D line as a light source, and the average value of five tests is used as the refractive index. The refractive index of the cured resin layer 3 is measured in accordance with Method B of JIS K 7142:2008. Specifically, the cured or solidified cured resin layer 3 is powdered and immersed in methylene iodide (nD 23 1.747), butyl phthalate (nD 23 1.491) and dimethyl carbonate (nD 23 1.366), and a small measuring microscope STM5-311 (Olympus, observation magnification 400x) was used as the microscope, and measurements were taken at a temperature of 23°C using sodium D line with a wavelength of 589 nm as the light source, and the average value of 5 tests was taken as the refractive index value.

[0026] (cured resin layer 3) In the transparent sheet 1 of the present invention, the cured resin layer 3 is impregnated into the glass fiber fabric 2 and is formed by curing or solidifying a curable resin composition containing a curable resin. When a cured resin layer is formed, the resin composition containing the curable resin can be cured by applying energy such as light or heat to the resin composition to form a cured product (a photocured resin composition or a heat-cured resin composition).

[0027] From the viewpoint of increasing the total light transmittance of the transparent sheet 1 and reducing haze, the cured resin is preferably one that can approximate the refractive index of the cured resin layer 3 to that of the glass fiber fabric 2 described above. Preferred cured resins are those that result in photocurable cured resin compositions, such as vinyl ester resins (bisphenol A vinyl ester resins), brominated vinyl ester resins (brominated bisphenol A vinyl ester resins), urethane (meth)acrylate resins, fluorine-containing (meth)acrylate resins, fluorene (meth)acrylate resins, unsaturated polyester resins, curable acrylic resins, and epoxy resins. Among these, the cured resin layer is preferably one that satisfies the requirements for total heat release and heat release rate (radiant intensity of 50 kW / m in a cone calorimeter test) in the heat release test of the certification standard for non-combustible materials in the Building Standards Act. 2 In a 20-minute heating and combustion test, (1) the total calorific value was 8MJ / m 2 (2) 200 kW / m 2 From the viewpoint of making it easier to lower the heat generation time exceeding 10 seconds (the heat generation time exceeding 10 seconds is less), it is preferable that the resin contains a brominated vinyl ester resin.

[0028] The resin composition forming the cured resin layer 3 may further contain additives such as a curing accelerator, a flame retardant, an ultraviolet absorber, a filler, and a photopolymerization initiator. Examples of flame retardants include aluminum hydroxide, magnesium hydroxide, trichloroethyl phosphate, triallyl phosphate, ammonium polyphosphate, and phosphoric acid ester. Examples of ultraviolet absorbers include benzotriazole. Examples of fillers include calcium carbonate, silica, and talc. Photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, 2-methyl Examples of suitable methylbenzoyl compounds include 2-benzyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0029] In the present invention, in order to enhance the transparency of the transparent sheet, it is desirable to set the refractive indexes of the glass fiber fabric 2 and the cured resin layer 3 to be similar to each other. From this viewpoint, the refractive index of the cured resin layer 3 is preferably about 1.45 to 1.65, and more preferably about 1.50 to 1.60.

[0030] In the transparent sheet 1 of the present invention, the mass of the cured resin layer 3 is, for example, 20 to 400 (g / m 2) is preferably 50 to 150 g / m from the viewpoint of increasing the usage rate of recycled or plant-derived raw materials in the transparent sheet 1, increasing the total light transmittance and reducing haze, and improving non-flammability. 2 , more preferably 80 to 120 g / m 2 The thickness of the cured resin layer 3 is, for example, 20 to 500 μm, and from the viewpoint of more easily achieving a balance between increasing the usage rate of recycled or plant-derived raw materials in the transparent sheet 1, increasing the total light transmittance and reducing haze, and increasing non-flammability, the thickness is preferably 30 to 150 μm, and more preferably 70 to 110 μm.

[0031] (Film layer 4 is a film containing recycled polyester resin or a film containing biomass polyester resin) The transparent sheet 1 of the present invention includes a film layer 4 that is a film containing recycled polyester resin or a film containing biomass polyester resin, thereby reducing the amount of cured resin used to form the cured resin layer 3, while ensuring strength and ease of handling when used, for example, in a hanging smoke barrier or partition, and increasing the rate of recycled or plant-derived raw materials used in the transparent sheet 1.

[0032] In the present invention, the film containing recycled polyester resin contains a polyester resin obtained by recycling. Recycled raw materials include pre-consumer materials, which are waste plastics generated during the film manufacturing process, and post-consumer materials, which are used waste plastics. Both pre-consumer and post-consumer materials can be used. While a combination of pre-consumer and post-consumer materials is also possible, pre-consumer materials are preferred. Recycling methods include mechanical recycling and chemical recycling. Either method is acceptable, but a film containing mechanically recycled recycled polyester resin, which has poor total light transmittance and haze, is preferred because it more easily exhibits the effects of the present invention. A preferred example of a film containing recycled polyester resin is a film containing recycled polyethylene terephthalate. The recycled raw material usage rate (mass %) in a film containing recycled polyester resin is 50 mass % or more, preferably 80 mass % or more, and more preferably 90 mass % or more. Furthermore, a film containing recycled polyester resin may contain fossil-derived virgin polyester resin as part of its raw materials, rather than using recycled raw materials. Furthermore, the mass ratio of the recycled polyester raw material to the mass of the transparent sheet 1 of the present invention is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, from the viewpoint of more easily achieving the effects of the present invention.

[0033] In the present invention, the film containing biomass polyester resin contains biomass polyester as a raw material. The biomass polyester resin is composed of diol units and dicarboxylic acid units, and the diol units are ethylene glycol derived from biomass. The dicarboxylic acid units may be dicarboxylic acid derived from fossil fuel. The biomass polyester can be obtained by a polycondensation reaction using such biomass-derived ethylene glycol and fossil fuel-derived dicarboxylic acid.

[0034] Biomass-derived ethylene glycol is produced from ethanol (biomass ethanol) produced from biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene oxide by a conventionally known method to produce ethylene glycol. Alternatively, commercially available biomass ethylene glycol may be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used.

[0035] The dicarboxylic acid units of the biomass polyester may be dicarboxylic acids derived from fossil fuels. As the dicarboxylic acid, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof can be used without limitation. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Among these, terephthalic acid is preferred, and dimethyl terephthalate is preferred as a derivative of aromatic dicarboxylic acid.

[0036] The biomass raw material usage rate (mass %) in the film containing biomass polyester resin is 10 mass % or more, preferably 20 mass % or more. In addition, the mass ratio of the biomass raw material to the mass of the transparent sheet 1 of the present invention is preferably 10 mass % or more, from the viewpoint of more easily achieving the effects of the present invention.

[0037] In the transparent sheet 1 of the present invention, from the viewpoint of further enhancing the GHG emission reduction effect and making it easier to achieve the effects of the present invention, a film containing recycled polyester resin is preferably laminated to at least one side of the cured resin layer 3, and more preferably laminated to both sides of the cured resin layer 3.

[0038] In the transparent sheet 1 of the present invention, the total light transmittance of the film layer 4, which is a film containing a recycled polyester resin or a film containing a biomass polyester resin, is 85 to 92%, preferably 85 to 89%, from the viewpoint of further enhancing the GHG emission reduction effect and facilitating the realization of the effects of the present invention. In the transparent sheet 1 of the present invention, the haze of the film layer 4, which is a film containing a recycled polyester resin or a film containing a biomass polyester resin, is 0.5 to 5%, preferably 2.5 to 4%, from the viewpoint of further enhancing the GHG emission reduction effect and facilitating the realization of the effects of the present invention. In the transparent sheet 1 of the present invention, the total light transmittance of the film layer 4 is a value measured in accordance with Japanese Industrial Standard JIS K 7361-1:1997, "Testing Method for Total Light Transmittance of Plastic-Transparent Materials - Part 1: Single Beam Method." In the transparent sheet 1 of the present invention, the haze of the film layer 4 is a value measured in accordance with Japanese Industrial Standard JIS K 7136 2000, "Determination of Haze of Plastic-Transparent Materials."

[0039] In the transparent sheet 1 of the present invention, the film layer 4, which is a film containing a recycled polyester resin or a film containing a biomass polyester resin, preferably has a b value of -2.3 to 2.3, and the absolute value of the b value may be 0.5 to 2.0 or 1.0 to 2.0. In the present invention, the b values ​​of the film layer 4 and the transparent sheet 1 are measured using a spectrophotometer under the conditions of transmission, light source C, viewing angle 2°, geometric conditions (0° / 0), and measurement temperature 25°C. * is the b value.

[0040] In the transparent sheet 1 of the present invention, the film layer 4, which is a film containing a recycled polyester resin or a film containing a biomass polyester resin, may have an L value of 90 or more, and from the viewpoint of further enhancing the GHG emission reduction effect and making the effects of the present invention more easily obtainable, preferably 92 to 97, more preferably 93 to 96. In the transparent sheet 1 of the present invention, the film layer 4, which is a film containing a recycled polyester resin or a film containing a biomass polyester resin, may have an a value of -0.5 to 0.5, and from the viewpoint of further enhancing the GHG emission reduction effect and making the effects of the present invention more easily obtainable, preferably the absolute value of the a value is 0.05 to 0.3, more preferably 0.1 to 0.2. In the present invention, the a value and L value of the film layer 4 and the transparent sheet 1 are measured using a spectrophotometer under the transmission method, the light source is a C light source, the viewing angle is 2°, the geometric conditions are (0° / 0), and the measurement temperature is 25°C. * is the a value, L * is the L value.

[0041] The film layer 4 may contain a material that is absorbing blue to yellow light (light with a wavelength of 430-590 nm) from the visible light spectrum. Examples of such a material include metals (Ag, Ni, Cu, Sn, Sb, Al, In, Ti, etc.) or metal oxides (antimony pentoxide, tin oxide, zinc oxide, indium oxide, antimony-doped indium oxide, tin-doped indium oxide, silver oxide, etc.), and π-conjugated conductive polymers such as polyacetylene, polyparaphenylene, polythiophene, polypyrrole, and polyaniline. The film layer 4 may further contain a layer containing a material that is absorbing the above-mentioned light with a wavelength of 430-590 nm on the surface side of the film layer 4. The mass of each layer containing a material that is absorbing the above-mentioned light with a wavelength of 430-590 nm is 0.1 to 10 g / m. 2 and 0.1 to 5 g / m 2 is preferably 0.1 to 3 g / m 2 More preferably, the range is 0.1 to 1 g / m 2 are particularly preferred.

[0042] The thickness of each film layer 4 is preferably 30 to 150 μm, more preferably 65 to 90 μm, from the viewpoint of more easily achieving both the b value of the transparent sheet 1 in a specific range and enhanced non-combustibility. The mass of each film layer 4 is preferably 45 to 180 g / m², from the viewpoint of more easily achieving both the b value of the transparent sheet 1 in a specific range and enhanced non-combustibility. 2 is preferable, and from the viewpoint of achieving both non-combustibility and folding resistance, 90 to 120 g / m 2 is more preferred.

[0043] In the transparent sheet 1 of the present invention, the ratio of the thickness of the cured resin layer 3 to the thickness of the film layer 4 (thickness of cured resin layer / thickness of film layer) is preferably 0.9 to 2.0, and more preferably 0.9 to 1.5, from the viewpoint of more easily achieving both the b-value of the transparent sheet 1 in a specific range and enhanced flame retardancy. Furthermore, in the transparent sheet 1 of the present invention, the ratio of the thickness of the film layer 4 to the mass of the glass fiber fabric 2 (thickness of film layer 4 / mass of glass fiber fabric 2) is preferably 2 to 4.5, and more preferably 3.5 to 4.2, from the viewpoint of more easily achieving both the b-value of the transparent sheet 1 in a specific range and enhanced flame retardancy.

[0044] (Properties of transparent sheet 1, etc.) The transparent sheet 1 of the present invention has a total light transmittance of 80% or more and a haze of 30% or less. In this specification, the total light transmittance of the transparent sheet 1 is a value measured in accordance with Japanese Industrial Standard JIS K 7361-1:1997, "Test method for total light transmittance of plastic transparent materials - Part 1: Single beam method." The haze of the transparent sheet 1 is a value measured in accordance with Japanese Industrial Standard JIS K7136 2000, "Determination of haze of plastic transparent materials." The transparent sheet of the present invention preferably has a total light transmittance of 85% or more, and can be 85 to 89.5%. The haze of the transparent sheet 1 of the present invention is preferably 20% or less, more preferably 10% or less, and can be 3 to 8%.

[0045] The transparent sheet 1 of the present invention has a b-value of -2.3 to 2.3. By setting the b-value of the transparent sheet 1 within this range, blue and yellow color bleeding can be suppressed, and the percentage of recycled or plant-derived raw materials used in the transparent resin composite of glass fiber and resin can be increased, while suppressing a decrease in visibility when viewed through the transparent sheet 1. The absolute value of the b-value is preferably 0.8 to 2.3, more preferably 1.2 to 1.9, and even more preferably 1.2 to 1.55. The b-value can be 0 to 2.3, 0 to 1.9, or 0 to 1.5. When the b-value is positive (a positive number), blue light is dispersed, resulting in a positive b-value. When the b-value is negative (a negative number), yellow light is dispersed, resulting in a negative b-value. The present inventors have conducted research and found that by setting the b-value within the above specific range, blue and yellow color bleeding can be suppressed, and a decrease in visibility when viewed through the transparent sheet 1 can be suppressed.

[0046] The transparent sheet 1 of the present invention preferably has an a value of -1.0 to 1.0. The absolute value of the a value of the transparent sheet 1 of the present invention is more preferably 0.6 to 1.0, and more preferably 0.7 to 1.0. The transparent sheet 1 of the present invention preferably has an L value of 92 or more, and more preferably 95 or more.

[0047] The transparent sheet 1 of the present invention has the property of being difficult to burn (to generate heat) in the event of a fire, since it contains the glass fiber fabric 2. A preferable index of the property that the transparent sheet 1 of the present invention has is a value of 50 kW / m 2 In a heat generation test in which radiant heat is irradiated, the total heat generation amount for 20 minutes after the start of heating is, for example, 8MJ / m 2 Other preferable indexes of the properties of the sheet 1 of the present invention include a thermal conductivity of 50 kW / m 2 In a heat generation test in which radiant heat is irradiated, the heat generation rate is 200 kW / m for 10 seconds or more continuously for 20 minutes after heating starts. 2 The main points are that it does not exceed 50kW / m 2The total heat generation amount and heat generation rate per unit area in the heat generation test in which radiant heat of 50 kW / m is applied from a radiant electric heater to the surface of the membrane ceiling sheet, as measured in accordance with "4.9.2 Heat Generation Test" in the "Fire Prevention and Evaluation Service Manual" (revised July 1, 2021) of the Japan Testing Center for Building Materials. To make it easier for the sheet of the present invention to have the above properties, the content ratio of the glass fiber fabric 2 or the mass of the cured resin layer 3 can be adjusted, or the cured resin layer 3 can be made to contain a brominated vinyl ester resin. Furthermore, the transparent sheet of the present invention has a heat generation rate of 50 kW / m from a radiant electric heater to the surface of the membrane ceiling sheet, as measured in accordance with "4.9.2 Heat Generation Test" in the "Fire Prevention and Evaluation Service Manual" (revised July 1, 2021) of the Japan Testing Center for Building Materials. 2 In a heat generation test in which radiant heat is irradiated, it is preferable that no through holes of 0.5 mm square or larger are present for 20 minutes after the start of heating.

[0048] The mass of the transparent sheet 1 of the present invention is not particularly limited, but is, for example, 200 to 500 g / m 2 , preferably 300 to 400 g / m 2 The thickness of the transparent sheet 1 of the present invention is, for example, 150 to 400 μm, and preferably 220 to 300 μm.

[0049] (Use of transparent sheet 1) The transparent sheet 1 of the present invention can be suitably used as a material for constituting smoke-proof hanging walls, smoke-proof sheets, partition walls, smoke-proof curtains, touch panels, solar panels (back sheets, etc.), or as a membrane material used for roofing materials, lighting tents, etc.

[0050] (Method of manufacturing transparent sheet 1) The method for producing the sheet 1 of the present invention is not particularly limited, and examples thereof include the following production method. First, a film containing the recycled polyester resin or a film containing a biomass polyester resin described above is prepared. Then, the glass fiber fabric 2 described above and the uncured cured resin solution that will form the cured resin layer 3 described above are prepared. The cured resin solution is applied to the film that will form the film layer 4, and the glass fiber fabric 2 is placed on top of the cured resin solution to impregnate the glass fiber fabric 2 with the cured resin solution. Then, another film that will form the film layer 4 is placed on the glass fiber fabric 2, and pressure is applied to the surfaces of the two films to further impregnate the glass fiber fabric 2 with the cured resin solution. The cured resin solution is cured by heating or light irradiation, resulting in a transparent sheet 1 in which the glass fiber fabric 2 is impregnated with the cured resin layer 3 and the film layer 4 is laminated on the cured resin layer 3 (transparent sheet 1 laminated in the order of film layer 4 / cured resin layer 3 impregnated in the glass fiber fabric 2 / film layer 4). [Example]

[0051] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0052] 1. Measurement and evaluation methods 1-1. Single fiber diameter (μm) and number of single fibers of glass yarn (pieces) Two pieces of glass fiber fabric were cut into 30 cm squares, one for observing the warp yarns and the other for observing the weft yarns, and each was embedded in epoxy resin (product name "3091", manufactured by Marumoto Struers K.K.) and cured. Next, the glass cloth embedded in the epoxy resin was polished to an extent that the cross section of the single fibers constituting the warp or weft yarns could be observed, and the average single fiber diameter (μm) and the number of single fibers (number of fibers) of the glass yarn were measured by observing them at a magnification of 500 times using a scanning electron microscope (SEM) (product name "JSM-6390A", manufactured by JEOL Ltd.). (1) Single fiber diameter of long glass fiber (μm) Twenty warp and weft yarns were randomly selected, and the cross sections of all the single fibers contained in each of the 20 glass yarns were observed, the diameters were measured, and the average values ​​were calculated to determine the single fiber diameters of the warp and weft yarns. (2) Number of single fibers (pieces) Twenty warp and weft yarns were randomly selected, and the total number of single fibers contained in each of the 20 glass yarns was measured and the average value was calculated to determine the number of single fibers in the warp and weft yarns.

[0053] 1-2.Glass yarn count The count of the glass yarn was measured according to the method specified in "7.1 Count" of the Japanese Industrial Standard JIS R 3420 2013 "General Test Methods for Glass Fibers." Specifically, 500 m of glass yarn was first taken from the winding machine and used as a test piece. The test piece was placed flat in a muffle furnace and baked at 625°C for 25 minutes, then allowed to cool in a desiccator, and the mass of the test piece was measured. The count was calculated according to the following formula: (formula) t=(m / 500)×1000 t: count m: mass of test piece (g)

[0054] 1-3.Glass fiber fabric 2 weave density (threads / 25mm) The weave density of the glass fiber fabric 2 was measured for the warp and weft threads in accordance with the method specified in "7.9 Density (Weave Density)" of the Japanese Industrial Standard JIS R 3420:2013 "General Test Methods for Glass Fibers." Specifically, the measurement targets were positions 50 mm or more away from the edges and selvages of the glass fiber fabric 2, with the measurement interval set to 10 mm or more and 200 mm or less, and the total number of threads within the set measurement interval was counted. This was counted as one measurement, and the measurement was then moved to another position that did not include the previously measured thread, and the total number of threads within the measurement interval was counted two more times in the same manner. For each of the three measurements, the number of threads per 25 mm was calculated using the following formula, and the average of the three measurements was calculated. (formula) Mi=(ni / ai)×25 Mi: Number of threads per 25mm ni: Number of measured yarns ai: the exact distance at which the measurement was taken (mm)

[0055] 1-4. Thickness of glass fiber fabric 2 (μm) The thickness of the glass fiber fabric 2 was measured in accordance with Method A specified in "7.10.1 Cloth Thickness" of the Japanese Industrial Standard JIS R3420:2013 "General Test Methods for Glass Fibers." Specifically, using a micrometer, the spindle was gently rotated to lightly contact the measurement surface parallel to it, and the thickness of the glass fiber fabric 2 was measured by reading the scale after the ratchet made three clicks. The thickness of the glass fiber fabric 2 was measured at the intersection of the warp and weft yarns.

[0056] 1-5. Refractive index of the glass fiber fabric 2 and the cured resin layer 3 The refractive indices of the glass fiber fabric 2 and the cured resin layer 3 were measured in accordance with "Method B" specified in Japanese Industrial Standard JIS K 7142:2008, "Plastics - Determination of Refractive Index." Specifically, the glass fibers constituting the glass fiber fabric 2 and the cured resin layer 3 were first crushed to an extent that Becke lines could be observed when observed under an optical microscope at 400x magnification, and used as measurement samples. Separately, multiple immersion solutions with refractive indices differing by 0.002 were prepared. A small amount of the immersion solution was placed on a glass slide, and several particles of the measurement sample were placed in the immersion solution on the glass slide, followed by a cover glass. A halogen lamp equipped with a D-line interference filter was used as the light source, and the measurement sample was focused on using an optical microscope at 400x magnification. The microscope stage and objective lens were then moved slightly apart to defocus the image. By this procedure, if the refractive index of the measurement sample does not match that of the immersion liquid, the Becke lines (i.e., the bright halo visible around or inside the powder) will shift to the higher refractive index, and if the refractive index of the measurement sample matches that of the immersion liquid, the Becke lines will not appear. The refractive index was measured by repeating the measurement until the refractive index of the measurement sample matches that of the immersion liquid or falls between two adjacent refractive indices in the series of immersion liquids. The refractive index was measured three times at a temperature of 23°C, and the average of the three measurements was taken as the refractive index.

[0057] 1-6. Mass of glass fiber fabric 2 (g / m 2 ) The mass of the glass fiber fabric 2 was measured in accordance with the method specified in "7.2 Mass (mass) of cloths and mats" of the Japanese Industrial Standard JIS R 3420:2013 "General test methods for glass fibers." Specifically, a 100 cm2 area was measured from a point 50 mm or more away from the edge of the glass fiber fabric 2. 2 A square test piece was taken, dried at 105°C for 1 hour, and then the mass of the test piece was measured and calculated as 1m according to the following formula: 2 The mass per unit was calculated. (formula) ρA=(ms / 100)×10 4 ρA:1m 2 Mass per unit (g / m 2 ) ms: mass of test piece (g)

[0058] 1-7. Total light transmittance (%) and haze (%) The total light transmittance of the transparent sheet 1 was measured in accordance with Japanese Industrial Standard JIS K 7361-1:1997 "Test method for total light transmittance of plastic transparent materials - Part 1: Single beam method." The haze of the transparent sheet 1 was measured in accordance with Japanese Industrial Standard JIS K 7136:2000 "Determination of haze of plastic transparent materials."

[0059] 1-8. Non-flammability test (total heat generation in heat generation test (MJ / m 2 ), heat generation rate per unit area 200kW / m 2 (Excessive duration (seconds), 20 minutes after heating begins, no cracks or holes penetrating to the back surface that are harmful to fire prevention) Transparent sheet 1: 50kW / m 2 The total heat generation amount in the heat generation test in which radiant heat is irradiated is 200kW / m and the heat generation rate per unit area is 200kW / m 2 The excess duration and the absence of cracks or holes penetrating to the backside that would be harmful to fire safety for 20 minutes after heating began were measured in accordance with "4.9.2 Heat Generation Test" in the "Fire Prevention and Evaluation Procedures Manual" (revised July 1, 2021) of the Japan Testing Center for Construction Materials. The specific method is as follows:

[0060] [Test specimen] (1) The number of test specimens (sheet 1) shall be three. (2) The shape and dimensions of the test specimen shall be a square with each side measuring 99 mm ± 1 mm. (3) Before the test, the test specimen is cured at a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5% until it reaches a constant mass. [Test equipment] (1) A schematic diagram of the test equipment used is shown in Figure 3. The test equipment consists of a conical radiant electric heater, a spark plug, a radiant heat shield, a test specimen holder, a gas sampling device, an exhaust system capable of measuring gas flow rate, and a heat flow meter. (2) Radiant electric heater: 50 kW / m 2 The radiant heat must be able to be irradiated uniformly and stably onto the surface of the test piece. (3) The radiant heat shield must be capable of protecting the test specimen from radiant heat before the test begins. (4) A schematic diagram of the test holder and clamping frame included in the test equipment is shown in Figure 4. The specimen holder shall be made of stainless steel and be a square with outer dimensions of 106 mm ± 1 mm on each side, 25 mm ± 1 mm in depth, and 2.4 mm ± 0.15 mm in thickness. The clamping frame shall be made of stainless steel and be a square with inner dimensions of 111 mm ± 1 mm on each side, 54 mm ± 1 mm in height, and 1.9 mm ± 0.1 mm in thickness, with a square opening at the top measuring 94.0 mm ± 0.5 mm on each side. (5) The exhaust system shall be equipped with a centrifugal exhaust fan, hood, fan intake and exhaust ducts, an orifice plate flow meter, etc. that function effectively at the test temperature. The distance between the bottom end of the hood and the surface of the test specimen shall be 210 mm ± 50 mm, and the exhaust device of the exhaust system in this state shall have a flow rate of 0.024 m / s when converted to standard temperature and standard pressure. 3The exhaust gas flow rate shall be at least 1 / s. To measure the exhaust gas flow rate, an orifice plate with an inner diameter of 57 mm ± 3 mm and a thickness of 1.6 mm ± 0.3 mm shall be installed in the exhaust duct at a distance of at least 350 mm ± 15 mm downstream from the fan. For exhaust gas sampling, a ring sampler with 12 holes, each 2.2 mm ± 0.1 mm in diameter, shall be installed 685 mm ± 15 mm from the hood, with the holes facing in the opposite direction of the flow. The exhaust gas temperature shall be measured at the center of the exhaust duct, 100 mm ± 5 mm upstream from the orifice plate. (6) The gas sampling device shall be capable of continuously and accurately measuring the concentrations of oxygen, carbon monoxide, and carbon dioxide in the exhaust gas. (7) The spark plug shall be capable of receiving power from a 10kV transformer or induction coil system, etc. The distance between the electrodes of the spark plug shall be 3mm ± 0.5mm, and the electrodes shall be positioned 13mm ± 2mm above the central axis of the test specimen, in principle. (8) The heat flow meter is 100kW / m 2 ±10kW / m 2 The heat flow meter is a Schmidt-Boelter type that can measure up to 12.5 mm in diameter. The heat sensing part of the heat flow meter is circular and has a surface emissivity of 0.95±0.05.

[0061] [Test conditions] (1) The test time shall be 20 minutes from the time when radiant heat is irradiated onto the surface of the test specimen and an electric spark is simultaneously generated. (2) The test specimen is wrapped on the sides and back with aluminum foil of 0.025 mm or more and 0.04 mm or less in thickness, placed in a press frame, and then coated with inorganic fiber (nominal density 64 to 128 kg / m) on the back side. 3 ) and then pressed into the specimen holder. (3) During the test, a radiant electric heater was applied to the surface of the test specimen at 50 kW / m 2 It emits radiant heat. (4) Exhaust gas flow rate: 0.024 m 3 Adjust to / s. (5) Until the test begins, the test specimen is protected from radiant heat by a radiant heat shield. (6) Before moving the radiation heat shield, set the spark plug in place.

[0062] [measurement] (1) Measure the oxygen concentration at intervals of no more than 5 seconds. (2) The heat generation rate per unit area (kW / m 2 ) and the heat generation rate per unit area is calculated as 200 kW / m 2 The duration of the superheat state is calculated as "heat generation rate per unit area 200 kW / m 2 Furthermore, the total heat generation rate per unit area (MJ / m) was calculated by trapezoidal integration of the heat generation rate per unit area with respect to time. 2 Here, trapezoidal integration is performed by dividing the integration interval equally over the measurement interval, with the test time being used as the integration interval, and negative heat release rates being set to 0, and only positive heat release rates being integrated.

number

number

number

number

[0063] In the above non-combustibility test, if all of the following (1) to (3) were satisfied, the product was deemed to have excellent non-combustibility and rated A, and if at least one of the following (1) to (3) was not satisfied, the product was deemed to have poor non-combustibility and rated B. (1) Total calorific value (MJ / m 2 ) is 8MJ / m 2 below (2) The maximum heat generation rate after heating starts is 200 kW / m for 10 seconds or more. 2 not exceed (3) After heating begins, there are no holes of 0.5mm square or larger for 20 minutes.

[0064] 1-9. L value, a value and b value The L value, a value, and b value of the film and transparent sheet used as the film layer 4 were measured using a spectrophotometer (product name SE7700, manufactured by Nippon Denshoku Industries Co., Ltd.) under the following conditions: transmission method, light source C, viewing angle 2°, geometric conditions (0° / 0), and measurement temperature 25°C. * , a * , b * were measured and taken as the L value, a value and b value, respectively.

[0065] 1-10. Visibility when viewed through a transparent sheet A desk stand for a straight-tube fluorescent lamp was prepared, with the longitudinal direction of the straight-tube fluorescent lamp horizontal and the fluorescent lamp surface facing the observer. A 1,000-yen bill was then placed above the fluorescent lamp with its face facing the observer. A transparent sheet was placed 2 m away from the fluorescent lamp and the 1,000-yen bill and tilted at 45 degrees. An observer was positioned 1 m away on the opposite side of the transparent sheet from the side where the fluorescent lamp and the 1,000-yen bill were placed, and observed the 1,000-yen bill through the transparent sheet. Evaluation was based on whether the characters "1,000 Yen," "Bank of Japan Note," and the serial number (the number printed above the "Bank of Japan Note") were clearly legible. The evaluation criteria were as follows: In the present invention, a score of 3 or higher was considered acceptable. 5: The words "1,000 yen," "Bank of Japan note," and the serial number were all clearly readable. 4: Only the words "1,000 yen" and "Bank of Japan note" were clearly readable. 3: Only the word "1,000 yen" was clearly readable. 2: Only the characters "1,000 yen" were legible, but not clearly. 1: None of the text was legible or clearly readable.

[0066] 2. Transparent sheet manufacturing [Example 1] (Preparation of glass fiber fabric 2) Glass yarns (product name "ECBC1500 1 / 0 0.5Z", manufactured by Unitika Glass Fiber Co., Ltd.; average single fiber diameter 4 μm, single fiber count 100, twist count 0.5Z, count 3.4 tex) were used as warp and weft yarns. These were woven on an air jet loom to obtain a plain weave glass fiber fabric with a warp density of 75 / 25 mm and a weft density of 75 / 25 mm. The spinning and weaving sizing agents adhering to the resulting glass fiber fabric were then removed by heating at 400°C for 30 hours. The glass fiber fabric was then treated with a surface treatment agent containing a silane coupling agent (S-350: N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride), manufactured by Chisso Corporation) adjusted to a concentration of 15 g / L, squeezed with a padder roll, and then dried at 120°C for 1 minute for curing. The glass fiber fabric was then subjected to a water jet processing at a pressure of 1.5 MPa while applying a tension of 100 N / m in the warp direction to the glass fiber fabric, and a width-widening treatment was carried out once to obtain a glass fiber fabric 2. The obtained glass fiber fabric 2 had a warp density of 75 threads / 25 mm, a weft density of 75 threads / 25 mm, a thickness of 20 μm, and a mass of 19 g / m 2 The refractive index was 1.561. The single fiber diameter and the number of single fibers of the glass yarn were measured using the glass fiber fabric 2.

[0067] (Preparation of curable resin solution used to form cured resin layer 3) As the curable resin solution used to form the cured resin layer 3, brominated vinyl ester resin (product name "Neopol 8197", manufactured by Japan U-Pica Co., Ltd.), bisphenol A type vinyl ester resin (product name "Neopol 8114", manufactured by Japan U-Pica Co., Ltd.), neopentyl glycol diacrylate (product name "NK Ester A-NPG", manufactured by Shin-Nakamura Chemical Co., Ltd.), and photopolymerization initiators (product name "Omnirad 184", manufactured by IGM, and product name "Omnirad TPO-H", manufactured by IGM) were prepared and mixed to the mass ratio shown in Table 1 to prepare a curable resin solution.

[0068] (Preparation of film layer 4) A film containing recycled polyester resin made from mechanically recycled polyethylene terephthalate (manufactured by Toray Industries, Inc., product name Ecouse (registered trademark) Lumirror (registered trademark), containing pre-consumer recycled materials as raw materials) was prepared. The mass of the film was 105 g / m. 2 The film had a total light transmittance of 87.54%, a haze of 2.84%, an L value of 93.33, an a value of -0.03, and a b value of 1.92. Two sheets of the film were prepared.

[0069] (Lamination of a layer containing a material that is absorbing light with wavelengths of 430-590 nm onto film layer 4) A resin solution containing tin oxide microparticles (average particle diameter 20 nm) mixed and dispersed in a polyester resin (adhesive resin) at a mass ratio of 75:25 (adhesive resin:tin oxide microparticles) was applied to one side of the prepared film and dried to form a layer containing tin oxide microparticles, a metal oxide. The laminated film obtained by laminating this layer with film layer 4 had a total light transmittance of 88.38%, a haze of 3.03%, an L value of 94.46, an a value of -0.14, and a b value of 1.52. The thickness of the laminated film was 76 μm and the mass was 106 g. Two laminated films were prepared.

[0070] (Manufacturing transparent sheet 1) A prepared curable resin solution for forming the cured resin layer 3 was applied to the surface of the laminated film opposite the layer containing tin oxide microparticles. Next, the prepared glass fiber fabric 2 was placed on top of the curable resin solution and left to stand for 1 minute to impregnate the gaps in the glass fiber fabric 2 with the curable resin solution. Next, the laminated film was placed so that the surface opposite the layer containing tin oxide microparticles faced the curable resin solution side, and a roller was used to roll the laminated film over the cured resin layer 3 until the mass of the cured resin layer 3 reached 96 g / m. 2 Thereafter, the curable resin solution that would become the cured resin layer 3 through the laminated film was irradiated with light using a black light fluorescent lamp (product name FL15BLB, manufactured by Toshiba Corporation) (light irradiation conditions: cumulative light amount 200 mJ / cm 2) and curing the curable resin solution to form a cured resin layer 3, thereby obtaining a transparent sheet 1 of the present invention having a laminated structure of layer containing tin oxide microparticles / film layer 4 / cured resin layer 3 contained in a state impregnated in glass fiber fabric 2 / film layer 4 / layer containing tin oxide microparticles. In the obtained transparent sheet, the gaps between the glass fibers of the glass fiber fabric were impregnated with the cured resin layer 3 (a cured product of the cured resin), and the cured resin layer 3 was formed on both sides of the glass fiber fabric layer.

[0071] [Example 2] (Preparation of glass fiber fabric 2) The same glass fiber fabric 2 as in Example 1 was prepared.

[0072] (Preparation of curable resin solution used to form cured resin layer 3) The same curable resin solution as in Example 1 was prepared.

[0073] (Preparation of film layer 4) Two sheets of the same film as in Example 1 (manufactured by Toray Industries, Inc., product name Ecouse (registered trademark) Lumirror (registered trademark), containing pre-consumer recycled materials as raw materials) were prepared.

[0074] (Manufacturing transparent sheet 1) The curable resin solution prepared for the cured resin layer 3 was applied to the film that would become the film layer 4. Next, the prepared glass fiber fabric 2 was placed on the curable resin solution and left to stand for 1 minute to impregnate the gaps in the glass fiber fabric 2 with the curable resin solution. Next, the film that would become the film layer 4 was placed on the curable resin solution, and a roller was used to roll the film from above until the mass of the cured resin layer 3 became 96 g / m. 2 Thereafter, the curable resin solution that would become the cured resin layer 3 through the laminated film was irradiated with light using a black light fluorescent lamp (product name FL15BLB, manufactured by Toshiba Corporation) (light irradiation conditions: cumulative light amount 200 mJ / cm 2) and cured the curable resin solution to form a cured resin layer 3, thereby obtaining a transparent sheet 1 of the present invention having a laminated structure of cured resin layer 3 / film layer 4 contained in a state of being impregnated in film layer 4 / glass fiber fabric 2. In the obtained transparent sheet, the cured resin layer 3 (a cured product of the cured resin) was impregnated into the gaps between the glass fibers of the glass fiber fabric, and the cured resin layer 3 was formed on both sides of the glass fiber fabric layer.

[0075] [Example 3] (Preparation of glass fiber fabric 2) The same glass fiber fabric 2 as in Example 1 was prepared.

[0076] (Preparation of curable resin solution used to form cured resin layer 3) The same curable resin solution as in Example 1 was prepared.

[0077] (Preparation of film layer 4) A film containing recycled polyester resin (manufactured by Toyobo Co., Ltd., trade name Reshine (registered trademark)) was prepared using recycled polyethylene terephthalate raw materials that had been subjected to mechanical recycling. The mass of the film was 70 g / m. 2 , and the thickness was 50 μm.

[0078] (Manufacturing transparent sheet 1) The curable resin solution prepared for the cured resin layer 3 was applied to the film that would become the film layer 4. Next, the prepared glass fiber fabric 2 was placed on the curable resin solution and left to stand for 1 minute to impregnate the gaps in the glass fiber fabric 2 with the curable resin solution. Next, the film that would become the film layer 4 was placed on the curable resin solution, and a roller was used to roll the film from above until the mass of the cured resin layer 3 became 96 g / m. 2 Thereafter, the curable resin solution that would become the cured resin layer 3 through the laminated film was irradiated with light using a black light fluorescent lamp (product name FL15BLB, manufactured by Toshiba Corporation) (light irradiation conditions: cumulative light amount 200 mJ / cm 2) and cured the curable resin solution to form a cured resin layer 3, thereby obtaining a transparent sheet 1 of the present invention having a laminated structure of cured resin layer 3 / film layer 4 contained in a state of being impregnated in film layer 4 / glass fiber fabric 2. In the obtained transparent sheet, the cured resin layer 3 (a cured product of the cured resin) was impregnated into the gaps between the glass fibers of the glass fiber fabric, and the cured resin layer 3 was formed on both sides of the glass fiber fabric layer.

[0079] [Comparative Example 1] (Preparation of glass fiber fabric 2) Glass yarns (trade name "ECD900 1 / 0 0.8Z", manufactured by Unitika Glass Fiber Co., Ltd.; average single fiber diameter 5 μm, single fiber count 100, twist count 0.8Z, count 5.6 tex) were used as warp and weft yarns. These were woven on an air jet loom to obtain a plain weave glass fiber fabric with a warp density of 69 / 25 mm and a weft density of 69 / 25 mm. The spinning and weaving sizing agents adhering to the resulting glass fiber fabric were then removed by heating at 400°C for 30 hours. The glass fiber fabric was then treated with a surface treatment agent containing a silane coupling agent (S-350: N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride), manufactured by Chisso Corporation) adjusted to a concentration of 15 g / L, squeezed with a padder roll, and then dried at 120°C for 1 minute for curing. The glass fiber fabric was then subjected to a water jet processing at a pressure of 1.5 MPa while applying a tension of 100 N / m in the warp direction to the glass fiber fabric, and a width-widening treatment was carried out once to obtain a glass fiber fabric 2. The obtained glass fiber fabric 2 had a warp density of 69 threads / 25 mm, a weft density of 69 threads / 25 mm, a thickness of 30 μm, and a mass of 30 g / m 2 The refractive index was 1.561. The single fiber diameter and the number of single fibers of the glass yarn were measured using the glass fiber fabric 2.

[0080] (Preparation of curable resin solution used to form cured resin layer 3) The same curable resin solution as in Example 1 was prepared.

[0081] (Preparation of film layer 4) Two sheets of the same film as in Example 1 (manufactured by Toray Industries, Inc., product name Ecouse (registered trademark) Lumirror (registered trademark), containing pre-consumer recycled materials as raw materials) were prepared.

[0082] (Lamination of a layer containing a material that is absorbing light with wavelengths of 430-590 nm onto film layer 4) The same laminated film as in Example 1 was prepared in the same manner as in Example 1. Two sheets of the laminated film were prepared.

[0083] (Manufacturing transparent sheet 1) A prepared curable resin solution for forming the cured resin layer 3 was applied to the surface of the laminated film opposite the layer containing tin oxide microparticles. Next, the prepared glass fiber fabric 2 was placed on top of the curable resin solution and left to stand for 1 minute, allowing the curable resin solution to penetrate into the gaps in the glass fiber fabric 2. Next, the laminated film was placed so that the surface opposite the layer containing tin oxide microparticles faced the curable resin solution, and a roller was used to roll the laminated film from above until the mass of the cured resin layer 3 reached 95 g / m. 2 Thereafter, the curable resin solution that would become the cured resin layer 3 through the laminated film was irradiated with light using a black light fluorescent lamp (product name FL15BLB, manufactured by Toshiba Corporation) (light irradiation conditions: cumulative light amount 200 mJ / cm 2 ) and curing the curable resin solution to form a cured resin layer 3, thereby obtaining a transparent sheet 1 of the present invention having a laminated structure of layer containing tin oxide microparticles / film layer 4 / cured resin layer 3 contained in a state impregnated in glass fiber fabric 2 / film layer 4 / layer containing tin oxide microparticles. In the obtained transparent sheet, the gaps between the glass fibers of the glass fiber fabric were impregnated with the cured resin layer 3 (a cured product of the cured resin), and the cured resin layer 3 was formed on both sides of the glass fiber fabric layer.

[0084] Comparative Example 2 (Preparation of glass fiber fabric 2) Glass yarns (trade name "ECD450 1 / 0 0.8Z", manufactured by Unitika Glass Fiber Co., Ltd.; average single fiber diameter 5 μm, single fiber count 200, twist count 0.8Z, count 11.2 tex) were used as warp and weft yarns. These were woven on an air jet loom to obtain a plain weave glass fiber fabric with a warp density of 53 / 25 mm and a weft density of 53 / 25 mm. The spinning and weaving sizing agents adhering to the resulting glass fiber fabric were then removed by heating at 400°C for 30 hours. The glass fiber fabric was then treated with a surface treatment agent containing a silane coupling agent (S-350: N-vinylbenzyl-aminoethyl-γ-aminopropyltrimethoxysilane (hydrochloride), manufactured by Chisso Corporation) adjusted to a concentration of 15 g / L, squeezed with a padder roll, and then dried at 120°C for 1 minute for curing. The glass fiber fabric was then subjected to a water jet processing at a pressure of 1.5 MPa while applying a tension of 100 N / m in the warp direction to the glass fiber fabric, and a width-widening treatment was carried out once to obtain a glass fiber fabric 2. The obtained glass fiber fabric 2 had a warp density of 53 threads / 25 mm, a weft density of 53 threads / 25 mm, a thickness of 43 μm, and a mass of 48 g / m 2 The refractive index was 1.561. The single fiber diameter and the number of single fibers of the glass yarn were measured using the glass fiber fabric 2.

[0085] (Preparation of curable resin solution used to form cured resin layer 3) The same curable resin solution as in Example 1 was prepared.

[0086] (Preparation of film layer 4) Two sheets of the same film as in Example 1 (manufactured by Toray Industries, Inc., product name Ecouse (registered trademark) Lumirror (registered trademark), containing pre-consumer recycled materials as raw materials) were prepared.

[0087] (Lamination of a layer containing a material that is absorbing light with wavelengths of 430-590 nm onto film layer 4) The same laminated film as in Example 1 was prepared in the same manner as in Example 1. Two sheets of the laminated film were prepared.

[0088] (Manufacturing transparent sheet 1) A prepared curable resin solution for forming the cured resin layer 3 was applied to the surface of the laminated film opposite the layer containing tin oxide microparticles. Next, the prepared glass fiber fabric 2 was placed on top of the curable resin solution and left to stand for 1 minute, allowing the curable resin solution to be impregnated into the gaps in the glass fiber fabric 2. Next, the laminated film was placed so that the surface opposite the layer containing tin oxide microparticles faced the curable resin solution side, and a roller was used to roll the laminated film from above until the mass of the cured resin layer 3 reached 97 g / m. 2 Thereafter, the curable resin solution that would become the cured resin layer 3 through the laminated film was irradiated with light using a black light fluorescent lamp (product name FL15BLB, manufactured by Toshiba Corporation) (light irradiation conditions: cumulative light amount 200 mJ / cm 2 ) and curing the curable resin solution to form a cured resin layer 3, thereby obtaining a transparent sheet 1 of the present invention having a laminated structure of layer containing tin oxide microparticles / film layer 4 / cured resin layer 3 contained in a state impregnated in glass fiber fabric 2 / film layer 4 / layer containing tin oxide microparticles. In the obtained transparent sheet, the gaps between the glass fibers of the glass fiber fabric were impregnated with the cured resin layer 3 (a cured product of the cured resin), and the cured resin layer 3 was formed on both sides of the glass fiber fabric layer.

[0089] 3.Results The results are shown in Table 1.

[0090] [Table 1]

[0091] The transparent sheets of Examples 1 to 3 were transparent sheets comprising a glass fiber fabric and a cured resin layer impregnated into the glass fiber fabric, and a film layer comprising a film containing recycled polyester resin or a film containing biomass polyester resin was laminated on at least one side of the cured resin layer.The transparent sheets had a total light transmittance of 80% or more, a haze of 30% or less, and a b-value of -2.3 to 2.3.As a result, it was possible to increase the usage rate of recycled or plant-derived raw materials in the transparent resin composite of glass fiber and resin, while suppressing blue or yellow color bleeding and suppressing a decrease in visibility when viewed through the transparent sheet.

[0092] On the other hand, the transparent sheets of Comparative Examples 1 and 2 had b values ​​outside the range of -2.3 to 2.3, and therefore were unable to suppress blue or yellow color bleeding and were unable to suppress a decrease in visibility when viewed through the transparent sheets.

Claims

1. A transparent sheet comprising a glass fiber fabric and a cured resin layer impregnated in the glass fiber fabric, a film layer that is a film containing a recycled polyester resin or a film containing a biomass polyester resin is laminated on at least one surface of the cured resin layer; the transparent sheet has a total light transmittance of 80% or more and a haze of 30% or less; The transparent sheet has a b value of −2.3 to 2.

3.

2. 2. The transparent sheet according to claim 1, wherein the glass fiber fabric has a cover factor CF represented by the following formula (I) of 800 to 900: CF=(Dw) １／２ ×W+(Df) １／２ ×F ・・・(I) In the above formula, the abbreviations represent the following: Dw: Warp count (dtex) Df: Weft count (dtex) W: Warp weave density (threads / 25mm) F: Weft density (count / 25mm)

3. 3. The transparent sheet according to claim 1, wherein the ratio of the thickness of the cured resin layer to the thickness of the film layer (thickness of the cured resin layer / thickness of the film layer) is 0.9 to 1.

5.

4. The present invention comprises a glass fiber fabric and a cured resin layer impregnated in the glass fiber fabric, and a film layer which is a film containing a recycled polyester resin or a film containing a biomass polyester resin is laminated on at least one surface side of the cured resin layer, the transparent sheet has a total light transmittance of 80% or more and a haze of 30% or less; A method for producing a transparent sheet, wherein the b value of the transparent sheet is −2.3 to 2.3, A method for producing a transparent sheet, comprising the step of preparing a film layer that is a film containing the recycled polyester resin or a film containing a biomass polyester resin.

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