Transparent sheet, laminated glass, and glass laminate

Abstract

To provide a technique to improve the strength of a xerogel layer.SOLUTION: A transparent sheet has a xerogel layer, and a first bonding layer and a second bonding layer, which are bonded together while sandwiching and compressing the xerogel layer therebetween in the thickness direction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a transparent sheet, laminated glass, and a glass laminate.

Background Art

[0002] The heat insulating sheet described in Patent Document 1 is composed of a laminate of an aerogel layer containing an aerogel and a resin layer containing a thermoplastic resin laminated on at least one surface of the aerogel layer. This heat insulating sheet is used, for example, as an interlayer film for laminated glass. By interposing the interlayer film for laminated glass between a pair of glass plates, laminated glass can be obtained.

[0003] The multilayer glass described in Patent Document 2 includes two plate glasses, a flat transparent porous body sandwiched between the two plate glasses, and a window frame. The transparent porous body uses methylated silica xerogel. The window frame clamps the transparent porous body from both sides by fixing the distance between the two plate glasses.

[0004] The transparent porous body for heat insulation described in Patent Document 3 includes an aerogel and a protective film made of a transparent resin on all or part of the surface of the aerogel. The protective film is a film in which low-density polyethylene is laminated on an ethylene / vinyl acetate copolymer which is a thermoplastic resin.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] The xerogel layer was brittle and could be cracked by handling before being fixed by sandwiching between two plate glasses.

[0007] Patent Documents 1 and 3 describe laminating an aerogel layer and a resin layer, but the strength of the aerogel layer was insufficient.

[0008] In Patent Document 2, a technique for improving the strength of the xerogel layer before fixing by sandwiching between two plate glasses has not been studied.

[0009] One aspect of the present invention provides a technique for improving the strength of the xerogel layer.

Means for Solving the Problems

[0010] 〔1〕The transparent sheet according to one aspect of the present invention includes a xerogel layer, and a first bonding layer and a second bonding layer that are bonded to each other in a compressed state with the xerogel layer sandwiched therebetween in the thickness direction.

[0011] 〔2〕The transparent sheet according to 〔1〕 above, wherein the compression ratio in the thickness direction of the xerogel layer is 0.5% to 20%.

[0012] 〔3〕The transparent sheet according to 〔1〕 or 〔2〕 above, wherein the first bonding layer and the second bonding layer are in contact with the xerogel layer and contain ethylene-vinyl acetate copolymer resin (EVA resin).

[0013] 〔4〕The transparent sheet according to 〔1〕 or 〔2〕 above, wherein the first bonding layer and the second bonding layer contain a plasticizer. The transparent sheet includes a first barrier layer that suppresses the migration of the plasticizer from the first bonding layer to the xerogel layer between the first bonding layer and the xerogel layer. The transparent sheet includes a second barrier layer that suppresses the migration of the plasticizer from the second bonding layer to the xerogel layer between the second bonding layer and the xerogel layer.

[0014] [5] The transparent sheet according to [4] above, wherein the first bonding layer and the second bonding layer contain polyvinyl butyral resin (PVB resin).

[0015] [6] The transparent sheet according to any one of [1] to [5] above, wherein the first bonding layer and the second bonding layer are bonded over the entire periphery.

[0016] [7] The transparent sheet according to any one of [1] to [5] above, wherein the first bonding layer and the second bonding layer are bonded on two opposite sides.

[0017] [8] The laminated glass according to one aspect of the present invention includes a first glass plate, a second glass plate facing the first glass plate, and an intermediate sheet disposed between the first glass plate and the second glass plate. The intermediate sheet is the transparent sheet according to any one of [1] to [7] above.

[0018] [9] The laminated glass according to [8] above, wherein the first glass plate, the second glass plate, and the intermediate sheet have a curved shape.

[0019]

[10] The laminated glass according to [8] or [9] above, wherein at least one of the first glass plate and the second glass plate contains inorganic glass.

[0020]

[11] The laminated glass according to

[10] above, wherein one of the first glass plate and the second glass plate contains organic glass.

[0021]

[12] The glass laminate according to one aspect of the present invention includes a first glass plate and the transparent sheet according to any one of [1] to [7] above laminated on the first glass plate. [Advantages of the Invention]

[0022] According to one aspect of the present invention, by compressing the xerogel layer in the thickness direction, the strength of the xerogel layer can be improved. [Brief Description of the Drawings]

[0023]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0024] First, the terms used in this specification and the claims will be explained. The term "gel" includes both "wet gel" and "xerogel".

[0025] "Wet gel" means a gel in which a three-dimensional network is swollen by a swelling agent. It includes hydrogels in which the swelling agent is water, alcogels in which the swelling agent is alcohol, and organogels in which the swelling agent is an organic solvent.

[0026] "Xerogel" means, according to the "Definitions of Terms Relating to the Structure and Processes of Sols, Gels, Networks, and Inorganic-Organic Composite Materials (IUPAC Recommendations 2007)" of the "Subcommittee on Polymer Terminology of the Inorganic Chemistry Division and Polymer Division of the International Union of Pure and Applied Chemistry (IUPAC)", "a gel composed of an open network formed by removing the swelling agent from a gel." There is also a classification method in which those obtained by removing the swelling agent by supercritical drying are aerogels, those obtained by removing the swelling agent by ordinary evaporation drying are xerogels, and those obtained by removing the swelling agent by freeze-drying are cryogels. However, in this specification and the claims, these are collectively referred to as xerogels.

[0027] "~" indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value.

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the description may be omitted.

[0029] First, with reference to FIG. 1, a method for manufacturing a xerogel layer according to the first embodiment will be described. The method for manufacturing a xerogel layer includes, for example, preparation of a raw material liquid (step S1), gelation (step S2), solvent substitution (step S3), and drying (step S4).

[0030] Note that the method for manufacturing a xerogel layer does not necessarily include all the processes shown in FIG. 3. For example, when the solvent of the raw material liquid is suitable for drying (step S4), solvent substitution (step S3) may not be performed. Further, the method for manufacturing a xerogel layer may include processes other than those shown in FIG. 3.

[0031] In step S1, a raw material solution is prepared. The raw material solution is selected according to the type of xerogel. The type of xerogel may be selected, for example, from (1) polysiloxane xerogel, (2) polymer xerogel, and (3) polysaccharide xerogels such as cellulose xerogel.

[0032] The raw material solution contains, for example, a gel raw material (hereinafter also referred to as "gel raw material") and a solvent for dissolving the gel raw material. The gel raw material is appropriately selected according to the type of xerogel finally obtained. The solvent is, for example, water or an organic solvent. Examples of the organic solvent include alcohols (such as methanol, ethanol, isopropyl alcohol, tert-butyl alcohol, benzyl alcohol, etc.), aprotic polar organic solvents (such as N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, etc.), ketones (such as cyclopentanone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, etc.), or hydrocarbons (such as n-hexane, heptane, etc.). A combination of a plurality of organic solvents may be used.

[0033] When the xerogel is (1) polysiloxane xerogel, examples of the gel raw material include those containing (1A) a silane compound and (1B) a catalyst. (1B) The catalyst is for uniformly promoting gelation. The gel raw material may further contain (1C) a surfactant.

[0034] Examples of (1A) the silane compound include alkoxysilane, a 6-membered ring-containing silane compound having a 6-membered ring-containing skeleton and a hydrolyzable silyl group, and a silyl group-containing polymer having an organic polymer skeleton and a hydrolyzable silyl group.

[0035] Examples of the alkoxysilane include tetraalkoxysilanes (tetramethoxysilane, tetraethoxysilane, etc.), monoalkyltrialkoxysilanes (methyltrimethoxysilane, methyltriethoxysilane, etc.), dialkyldialkoxysilanes (dimethyl dimethoxysilane, dimethyldiethoxysilane, etc.), trimethoxyphenylsilane, compounds having alkoxysilyl groups at both ends of an alkylene group (1,6-bis(trimethoxysilyl)hexane, 1,6-bis(methyldimethoxysilyl)hexane, 1,6-bis(methyldiethoxysilyl)hexane, 1,2-bis(trimethoxysilyl)ethane, 1,2-bis(methyldimethoxysilyl)ethane, 1,2-bis(methyldiethoxysilyl)ethane, etc.), alkoxysilanes having a perfluoropolyether group (perfluoropolyethertriethoxysilane, perfluoropolyethermethyldiethoxysilane, etc.), alkoxysilanes having a perfluoroalkyl group (perfluoroethyltriethoxysilane, etc.), pentafluorophenylethoxydimethylsilane, trimethoxy(3,3,3-trifluoropropyl)silane, alkoxysilanes having a vinyl group (vinyltrimethoxysilane, vinyltriethoxysilane, dimethoxymethylvinylsilane, diethoxymethylvinylsilane, etc.), alkoxysilanes having an allyl group (allyltrimethoxysilane, allyldimethoxymethylsilane, allyldiethoxymethylsilane, etc.), alkoxysilanes having an epoxy group (2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.), alkoxysilanes having an acryloyloxy group (3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, etc.), alkoxysilanes having a methacryloyloxy group (3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, etc.), or oligomers of the above alkoxysilanes. A combination of a plurality of the above materials may be used.

[0036] The six-membered ring-containing skeleton in the six-membered ring-containing silane compound is an organic skeleton having a six-membered ring composed of, for example, an isocyanuric ring, a triazine ring, or a benzene ring.

[0037] The organic polymer skeleton in the silyl group-containing polymer is an organic skeleton having a chain composed of, for example, a polyethylene chain, a polyether chain, a polyester chain, or a polycarbonate chain.

[0038] (1B) Examples of the catalyst include a base catalyst or an acid catalyst, and their aqueous solutions may also be used. Examples of the base catalyst include amines (triethylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, etc.), urea, ammonia, sodium hydroxide, or potassium hydroxide. Examples of the acid catalyst include inorganic acids (nitric acid, sulfuric acid, hydrochloric acid, etc.) or organic acids (formic acid, oxalic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monofluoroacetic acid, trifluoroacetic acid, etc.).

[0039] (1C) Examples of the surfactant include hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, Pluronic (registered trademark) F127 and PE10500 (trade name of BASF), or EH-208 (trade name of NOF Corporation).

[0040] When the xerogel is a (2) polymer xerogel, examples of the gel raw material include a thermoplastic resin or a curable resin.

[0041] Examples of the thermoplastic resin include those that can be dissolved in a solvent when heated and form a monolith (porous body) when cooled. Specifically, for example, polymethyl methacrylate or polystyrene can be mentioned.

[0042] Examples of the curable resin include a photocurable resin or a thermosetting resin. Examples of the photocurable resin include those containing either or both of acrylate and methacrylate and a photoinitiator. Examples of the thermosetting resin include those containing either or both of acrylate and methacrylate and a thermal polymerization initiator, as well as addition condensates of resorcinol and formaldehyde, or addition condensates of melamine and formaldehyde.

[0043] When the xerogel is a (3) polysaccharide xerogel, examples of the gel raw material include those containing (3A) polysaccharide nanofibers and (3B) an acid. Examples of the polysaccharide include cellulose, chitin, chitosan, or gellan gum in addition to others.

[0044] Examples of the (3A) polysaccharide nanofibers include 2,2,6,6 - tetramethylpiperidine - 1 - oxyl (TEMPO) - oxidized cellulose nanofibers. Examples of the (3A) polysaccharide nanofibers include chitin nanofibers or chitosan nanofibers in addition to cellulose nanofibers.

[0045] Examples of the (3B) acid include the inorganic acid or the organic acid. Instead of the acid, a base can also be used.

[0046] In step S2, the raw material liquid is injected into the interior of the container to form a raw material liquid layer containing the raw material liquid, and the formed raw material liquid layer is gelled inside the container. By gelation, cross - linking proceeds throughout the raw material liquid, and a three - dimensional backbone structure of the polymer is formed. Gelation includes aging. By gelation, a wet gel layer is obtained.

[0047] When the gel raw material contains (1A) a silane compound and (1B) a catalyst, gelation is carried out by heating. The silane compound is hydrolyzed with an acid catalyst or the like to become a sol having silanol groups (Si - OH). When the sol is heated, the silanol groups undergo an intermolecular dehydration condensation reaction to form Si - O - Si bonds, and the raw material liquid is gelled.

[0048] Note that the means for gelling the raw material liquid layer is not limited to a heater and is appropriately selected according to the type of gelling raw material.

[0049] For example, when the gelling raw material is a thermoplastic resin, the means for gelling the raw material liquid layer is a cooler.

[0050] When the gelling raw material is a photocurable resin, the means for gelling the raw material liquid layer is a light source. The light source irradiates the raw material liquid layer with light such as ultraviolet rays, cures the photocurable monomer, and gels the raw material liquid layer.

[0051] When the gelling raw material is a thermosetting resin, the means for gelling the raw material liquid layer is a heater.

[0052] When the gelling raw material is a polysaccharide nanofiber, the polysaccharide nanofiber gels in a short time when it comes into contact with an acid catalyst or a base catalyst. Therefore, the raw material liquid may contain the polysaccharide nanofiber and does not need to contain an acid catalyst or a base catalyst. The acid catalyst or the base catalyst may be supplied in a shower form from above to the raw material liquid layer. In this case, the means for gelling the raw material liquid layer is a feeder that supplies an acid catalyst or a base catalyst from above to the raw material liquid layer.

[0053] In the final stage of gelling, since curing shrinkage occurs, the outer periphery of the wet gel layer may be peeled off from the side wall of the container due to the curing shrinkage.

[0054] In step S3, the solvent contained inside the wet gel layer is replaced with another solvent. The wet gel layer is a fine porous body and contains a solvent inside. The solvent replacement (step S3) is carried out before drying (step S4) for the purpose of suppressing the shrinkage of the wet gel layer due to the surface tension of the solvent during drying and suppressing the damage of the fine structure of the wet gel layer.

[0055] In solvent replacement, the solvent contained inside the wet gel layer is replaced from the solvent suitable for gelation (i.e., the solvent of the raw material solution) to a solvent suitable for drying. The solvent after replacement is appropriately selected according to the drying method. As the drying method, supercritical drying, freeze drying, or atmospheric pressure drying is used.

[0056] In supercritical drying, the solvent contained inside the wet gel layer is replaced with a supercritical fluid. As a solvent suitable for supercritical drying, for example, methanol, ethanol, or isopropyl alcohol, etc. are used. As the supercritical fluid, generally, supercritical carbon dioxide gas is used. Supercritical drying is carried out inside a closed high-pressure vessel.

[0057] In freeze drying, the solvent contained inside the wet gel layer is frozen and then evaporated in a vacuum. Usually, this is called sublimation. As a solvent suitable for freeze drying, water, tert-butyl alcohol, cyclohexane, 1,4-dioxane, or fluorinated solvents, etc. are used. Freeze drying is carried out inside a closed vacuum vessel.

[0058] In atmospheric pressure drying, the solvent contained inside the wet gel layer is evaporated under atmospheric pressure. Since it is important to reduce the contraction force of the fine skeleton of the wet gel layer due to the capillary force accompanying solvent evaporation, as a solvent suitable for atmospheric pressure drying, a solvent with a low surface tension, for example, a low molecular weight aliphatic hydrocarbon-based solvent such as hexane or heptane, or a fluorinated solvent is used. Since atmospheric pressure drying is carried out at atmospheric pressure, a closed container is not required.

[0059] Solvent replacement is carried out at a temperature below the boiling point of the solvent to suppress damage to the fine structure of the wet gel layer due to boiling of the solvent. However, in order to increase the replacement efficiency of the solvent, the solvent may be heated at a temperature below the boiling point. The heating temperature is, for example, 40°C to 100°C.

[0060] The number of solvent replacements is once in this embodiment, but it may be multiple times. That is, the solvent contained inside the wet gel layer is replaced from the solvent of the raw material liquid with a first solvent having a composition different from that of the solvent of the raw material liquid, and may further be replaced with a second solvent having a composition different from that of the solvent of the raw material liquid and the first solvent.

[0061] When the compatibility between the solvent of the raw material liquid and the second solvent is low, the replacement efficiency deteriorates. Therefore, by introducing replacement with the first solvent once in between, the time required for replacement from the solvent of the raw material liquid to the second solvent can be shortened. As the first solvent, one having high compatibility with both the solvent of the raw material liquid and the second solvent is used.

[0062] In addition, when the solvent of the raw material liquid is suitable for drying, solvent replacement is not necessary.

[0063] In step S4, the solvent contained inside the wet gel layer is removed. As the drying method of the wet gel layer, as described above, supercritical drying, freeze drying, or normal pressure drying is used. Among these, normal pressure drying is excellent in that a closed container is not required.

[0064] Normal pressure drying is carried out at a temperature below the boiling point of the solvent in order to suppress damage to the fine structure of the wet gel layer due to the boiling of the solvent. However, in order to increase the solvent removal efficiency, the wet gel layer may be heated at a temperature below the boiling point. The drying temperature of the wet gel layer is, for example, room temperature to 100°C.

[0065] In normal pressure drying, by blowing air against the wet gel layer, the evaporation of the solvent contained inside the wet gel layer can be promoted. The solvent evaporated by normal pressure drying is recovered and discarded or recycled as necessary.

[0066] By drying (step S4), a xerogel layer is obtained. The thickness of the xerogel layer is, for example, 0.1 mm to 20 mm, preferably 0.5 mm to 10 mm. The xerogel layer contains xerogel. The xerogel may be a porous monolith having transparency and heat insulation properties. The xerogel layer having transparency and heat insulation properties is used, for example, as a transparent heat insulating material for automotive window glass or building window glass.

[0067] When the application of the xerogel layer is a transparent heat insulating material, the transmittance of the xerogel layer at a wavelength of 500 nm is preferably 70% or more, preferably 80% or more, and preferably 90% or more in terms of a thickness of 1 mm. The transmittance is measured in accordance with Japanese Industrial Standard (JIS R 3106:1998). As an apparatus for measuring the transmittance, for example, a spectrophotometer (Solid Spec-3700DUV) manufactured by Shimadzu Corporation is used.

[0068] Examples of the applications of the xerogel layer include filters, adsorbents, sound absorbers, moisture absorbers, oil absorbers, or separation membranes in addition to heat insulating materials.

[0069] Next, with reference to FIGS. 2 to 4, a method for manufacturing the transparent sheet 20 according to the first embodiment will be described. First, as shown in FIG. 2, a first release film 41, a first bonding layer 25, a xerogel layer 21, a second bonding layer 26, and a second release film 42 are laminated in this order to produce a laminate 40. The laminate 40 is inserted, for example, inside a vacuum bag 50.

[0070] The first release film 41 prevents the vacuum back 50 from being bonded to the first bonding layer 25 and is peeled off from the first bonding layer 25 after being taken out of the vacuum back 50. The second release film 42 prevents the vacuum back 50 from being bonded to the second bonding layer 26 and is peeled off from the second bonding layer 26 after being taken out of the vacuum back 50. Note that the laminate 40 may not include the first release film 41 and the second release film 42, and a release agent may be applied to the inner surface of the vacuum back 50. A first glass plate may be used instead of the first release film 41, and a second glass plate may be used instead of the second release film 42. In this case, it is possible to produce laminated glass by the process shown in FIG. 3.

[0071] As shown in FIG. 3, the vacuum back 50 is heated from the outside while reducing the pressure inside the vacuum back 50. The atmospheric pressure inside the vacuum back 50 is, for example, -100 kPa to -65 kPa based on the atmospheric pressure. The heating temperature of the vacuum back 50 is, for example, 70°C to 110°C. Thereafter, the laminate 40 taken out from the vacuum back 50 is thermocompression bonded at a pressure of 0.3 MPa to 1.3 MPa while being heated at 100°C to 150°C. For thermocompression bonding, for example, an autoclave is used.

[0072] As shown in FIG. 4, a transparent sheet 20 is obtained. The transparent sheet 20 includes a first bonding layer 25, a xerogel layer 21, and a second bonding layer 26 in this order. The first bonding layer 25 and the second bonding layer 26 are bonded to each other in a state where the xerogel layer 21 is compressed while being sandwiched in the thickness direction. Note that the number of xerogel layers 21 disposed between the first bonding layer 25 and the second bonding layer 26 may be plural. A plurality of xerogel layers may be arranged in a planar manner like tiles.

[0073] The first bonding layer 25 and the second bonding layer 26 may be bonded over the entire periphery, or may be bonded only on two sides facing each other. It is only necessary to maintain the xerogel layer 21 in a compressed state in the thickness direction. The xerogel layer 21 has higher resistance to compressive stress than to tensile stress. If a compressive stress is applied to the xerogel layer 21 in advance, the generation of tensile stress during handling can be suppressed. Therefore, the strength of the xerogel layer 21 can be improved and the handleability can be improved.

[0074] The compression ratio CR in the thickness direction of the xerogel layer 21 is, for example, 0.5% to 20%. The compression ratio CR is obtained by the formula CR = (TB - TA) / TB × 100. TB is the thickness before compression, and TA is the thickness after compression.

[0075] If the compression ratio CR is 0.5% or more, the compressive stress is large and the strength is high. If the compression ratio CR is 20% or less, the fine structure of the xerogel layer 21 can be maintained, and whitening or cracking of the xerogel layer 21 can be suppressed. The compression ratio CR is preferably 1% or more, and more preferably 5% or more.

[0076] The first bonding layer 25 and the second bonding layer 26 are not particularly limited, but include, for example, ethylene-vinyl acetate copolymer resin (EVA resin) or polyvinyl butyral resin (PVB resin). The PVB resin is superior in penetration resistance to the EVA resin and is suitable for the front glass of an automobile, etc. However, unlike the EVA resin, the PVB resin contains a plasticizer. The plasticizer is an additive for enhancing flexibility, but when it migrates to the xerogel layer 21, it destroys the fine structure of the xerogel layer 21 and causes whitening or cracking of the xerogel layer 21. When the first bonding layer 25 and the second bonding layer 26 are in contact with the xerogel layer 21, it is preferable that they do not contain a plasticizer. Specific examples of thermoplastic resins that do not contain a plasticizer include, for example, EVA resin.

[0077] The transparent sheet 20 shown in FIG. 4 may be produced using a pair of nip rollers 51 as shown in FIG. 5. Each of the pair of nip rollers 51 has a roller 52, a first flange 53 provided at one axial end of the roller 52, and a second flange 54 provided at the other axial end of the roller 52.

[0078] A pair of rollers 52 compress the xerogel layer 21. A pair of first flanges 53 bond the side ends of the first bonding layer 25 and the second bonding layer 26 together. A pair of second flanges 54 bond the other side ends of the first bonding layer 25 and the second bonding layer 26 together. The first bonding layer 25 and the second bonding layer 26 sandwich the xerogel layer 21 in the thickness direction and maintain it in a compressed state, improving the strength of the xerogel layer 21.

[0079] The nip roller 51 may have a heater (not shown) inside to heat the first bonding layer 25 and the second bonding layer 26.

[0080] Note that the laminate 40 shown in FIG. 5 includes the first release film 41 and the second release film 42, but it may not include them, and a release agent may be applied to the outer peripheral surface of the nip roller 51. Also, although details will be described later, the roller 52 has an embossed pattern on its outer peripheral surface, and the embossed pattern may be transferred to at least one of the first bonding layer 25 and the second bonding layer 26.

[0081] Next, referring to FIG. 6, the laminated glass 30 according to the first embodiment will be described. The laminated glass 30 includes a first glass plate 31, a second glass plate 32 facing the first glass plate 31, and an intermediate sheet 33 disposed between the first glass plate 31 and the second glass plate 32. The intermediate sheet 33 is, for example, the transparent sheet 20 shown in FIG. 4. Note that the portions of the transparent sheet 20 protruding from the end faces of the first glass plate 31 and the second glass plate 32 may be cut off.

[0082] The transparent sheet 20 includes a first bonding layer 25 on one side of the xerogel layer 21 and a second bonding layer 26 on the opposite side of the xerogel layer 21. The first bonding layer 25 exhibits adhesiveness, for example, by heating, and bonds the xerogel layer 21 and the first glass plate 31. The second bonding layer 26 exhibits adhesiveness, for example, by heating, and bonds the xerogel layer 21 and the second glass plate 32. By bonding the first glass plate 31 and the second glass plate 32 via the transparent sheet 20, the laminated glass 30 is obtained.

[0083] The transparent sheet 20 has a uniform thickness, but may have a non-uniform thickness. For example, when an image of a head-up display is projected onto the laminated glass 30, the thickness of the transparent sheet 20 may increase from the lower side to the upper side in order to suppress the image from being seen double. In this case, the transparent sheet 20 is formed in a wedge shape, and the wedge angle is, for example, 1.0 mrad or less.

[0084] The first glass plate 31 and the second glass plate 32 may be of the same material or different materials. The materials of the first glass plate 31 and the second glass plate 32 may be inorganic glass or organic glass. It is preferable that at least one of the first glass plate 31 and the second glass plate 32 contains inorganic glass. The remaining one may be either inorganic glass or organic glass.

[0085] Examples of the organic glass include an acrylic resin or a polycarbonate resin. Examples of the inorganic glass include soda-lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, or borosilicate glass. The method of forming the inorganic glass into a plate shape is not particularly limited, but is, for example, the float method.

[0086] The first glass plate 31 and the second glass plate 32 may be unstrengthened glass (raw glass). The unstrengthened glass is glass obtained by shaping molten glass into a plate shape and slowly cooling it, and has not been subjected to strengthening treatments such as air-cooling strengthening treatment or chemical strengthening treatment. When the unstrengthened glass is cracked by impact, it is less likely to produce crack patterns such as reticular or spider-web-like cracks, and can ensure visibility.

[0087] The first glass plate 31 and the second glass plate 32 may have the same thickness or different thicknesses. When the first glass plate 31 is provided on the outside of the vehicle of the second glass plate 32, the thickness of the first glass plate 31 may be thicker than the thickness of the second glass plate 32. The thickness of the first glass plate 31 is, for example, 1.1 mm or more and 3.5 mm or less. The thickness of the second glass plate 32 is 0.5 mm or more and 2.3 mm or less. The thickness of the laminated glass 30 as a whole is 2.3 mm or more and 8.0 mm or less.

[0088] The laminated glass 30 is manufactured in the same manner as the transparent sheet 20. For example, first, a laminate having the first glass plate 31, the transparent sheet 20, and the second glass plate 32 in this order is produced. Next, the laminate is inserted into the inside of a vacuum bag, and the vacuum bag is heated from the outside while reducing the pressure inside the vacuum bag. Then, the laminate taken out from the vacuum bag is thermocompression bonded, for example, with an autoclave or the like. Thereby, the laminated glass 30 is obtained.

[0089] The transparent sheet 20 may have an embossed pattern on at least one of the surface in contact with the first glass plate 31 and the surface in contact with the second glass plate 32 before thermocompression bonding. For example, the roller 52 has an embossed pattern on its outer peripheral surface, and the embossed pattern may be transferred to the transparent sheet 20. The embossed pattern of the transparent sheet 20 improves the exhaust efficiency when the pressure inside the vacuum bag is reduced, and suppresses air bubbles from being caught in the laminated glass 30.

[0090] The laminated glass 30 is used, for example, as a window glass of an automobile. As shown in FIG. 7, the laminated glass 30 may be curved convexly outward of the vehicle as a whole or partially. The laminated glass 30 is a complex curve curved in the longitudinal and vertical directions of the vehicle, but may be a single curve curved only in the longitudinal direction or the vertical direction.

[0091] When manufacturing the laminated glass 30 having a curved shape, the first glass plate 31 and the second glass plate are pre-bent. Before thermocompression bonding, the laminate includes, in this order, the first glass plate 31 having a curved shape, the flat transparent sheet 20, and the second glass plate 32 having a curved shape. As a result, during thermocompression bonding, the transparent sheet 20 is bent and the xerogel layer 21 is bent.

[0092] According to the present embodiment, since a compressive stress is applied to the xerogel layer 21 before bending, it is possible to suppress the generation of tensile stress in the xerogel layer 21 during bending. Therefore, it is possible to suppress the cracking of the xerogel layer 21 during bending.

[0093] In FIG. 7, the laminated glass 30 is composed of the first glass plate 31, the intermediate sheet 33, and the second glass plate 32, but a glass laminate may be composed of the first glass plate 31 and the intermediate sheet 33. That is, the glass laminate may have a glass plate only on one side of the intermediate sheet 33. The same applies to the following second embodiment.

[0094] Next, with reference to FIGS. 8 to 10, the transparent sheet 20 according to the second embodiment will be described. The transparent sheet 20 of the present embodiment can also be used as an intermediate sheet of the laminated glass 30. Hereinafter, the differences between the first embodiment and the second embodiment will be mainly described.

[0095] As shown in FIG. 8, the first release film 41, the first bonding layer 25, the first barrier layer 22, the xerogel layer 21, the second barrier layer 23, the second bonding layer 26, and the second release film 42 are stacked in this order to produce a laminate 40. The laminate 40 is inserted, for example, inside a vacuum bag 50.

[0096] As shown in FIG. 9, while evacuating the inside of the vacuum bag 50, the vacuum bag 50 is heated from the outside. Then, the laminate 40 taken out from the vacuum bag 50 is thermocompression bonded, for example, in an autoclave. As a result, as shown in FIG. 10, the transparent sheet 20 is obtained.

[0097] The transparent sheet 20 includes a first bonding layer 25, a first barrier layer 22, a xerogel layer 21, a second barrier layer 23, and a second bonding layer 26 in this order. The first bonding layer 25 and the second bonding layer 26 are bonded to each other in a state where the xerogel layer 21 is compressed with the xerogel layer 21 sandwiched in the thickness direction. Note that the number of xerogel layers 21 disposed between the first bonding layer 25 and the second bonding layer 26 may be plural. A plurality of xerogel layers may be arranged side by side in a planar shape like tiles.

[0098] The first bonding layer 25 and the second bonding layer 26 may be bonded over the entire periphery, or may be bonded only at two sides facing each other. It is only necessary to maintain the xerogel layer 21 in a compressed state in the thickness direction. The xerogel layer 21 has higher resistance to compressive stress than to tensile stress. If a compressive stress is applied to the xerogel layer 21 in advance, the generation of tensile stress during handling can be suppressed. Therefore, the strength of the xerogel layer 21 can be improved and the handleability can be improved.

[0099] The first barrier layer 22 is used when the first bonding layer 25 contains a plasticizer. The first barrier layer 22 is disposed between the first bonding layer 25 and the xerogel layer 21, and suppresses the migration of the plasticizer from the first bonding layer 25 to the xerogel layer 21. While the first barrier layer 22 suppresses the plasticizer from destroying the fine structure of the xerogel layer 21, by including the plasticizer in the first bonding layer 25, the penetration resistance of the laminated glass 30 can be improved. Specific examples of the thermoplastic resin containing a plasticizer include, for example, PVB resin.

[0100] The second barrier layer 23 is used when the second bonding layer 26 contains a plasticizer. The second barrier layer 23 is disposed between the second bonding layer 26 and the xerogel layer 21, and suppresses the migration of the plasticizer from the second bonding layer 26 to the xerogel layer 21. While the second barrier layer 23 suppresses the plasticizer from destroying the fine structure of the xerogel layer 21, by including the plasticizer in the second bonding layer 26, the penetration resistance of the laminated glass 30 can be improved.

[0101] The transparent sheet 20 shown in FIG. 10 may be produced using a pair of nip rollers 51 as shown in FIG. 11. The laminate 40 shown in FIG. 11 includes a first release film 41 and a second release film 42, but may not include them, and a release agent may be applied to the outer peripheral surface of the nip roller 51. Further, the roller 52 has an embossed pattern on its outer peripheral surface, and the embossed pattern may be transferred to at least one of the first bonding layer 25 and the second bonding layer 26.

Example

[0102] Hereinafter, the experimental data will be described. Example 1 described later is a comparative example, and Examples 2 and 3 described later are examples.

[0103] (Xerogel layer) First, a sol solution as a raw material solution was prepared. Specifically, 40 g of methyltrimethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), 10 g of tetramethoxysilane (manufactured by Tokyo Chemical Industry Co., Ltd.), 100 g of a 5 mmol / L acetic acid aqueous solution, 30 g of urea, 10 g of hexadecyltrimethylammonium bromide (manufactured by Tokyo Chemical Industry Co., Ltd.) were placed in a plastic container containing a magnetic stirrer, and stirred at 25 ° C at a rotation speed of 800 rpm for 60 minutes to hydrolyze the alkoxysilane to form a sol, and a sol solution was prepared.

[0104] Next, the sol solution was poured into a 12 cm square polystyrene container so that the thickness was about 10 mm, and the container was heated in an oven at 60 ° C for 4 days with the container covered to obtain a wet gel layer.

[0105] Next, the solvent contained in the wet gel layer was replaced. Specifically, a first replacement of water with methanol, a second replacement of methanol with isopropanol, and a third replacement of isopropanol with heptane were performed. In the first replacement, the wet gel layer was immersed in methanol for 8 hours three times, and the methanol was replaced between the first and second times and between the second and third times. The second replacement and the third replacement were also performed in the same manner as the first replacement.

[0106] Next, the wet gel layer that had undergone the tertiary substitution was placed in an oven at 50 °C and dried under normal pressure for 24 hours to obtain a xerogel layer, a transparent polysiloxane gel. The thickness of the polysiloxane gel was 9.4 mm. Thereafter, the polysiloxane gel was cut to prepare three rectangular test pieces with a length of 110 mm, a width of 30 mm, and a thickness of 9.4 mm. No difference in appearance was observed among the three test pieces. The thickness and transmittance of each test piece are shown in Table 1.

[0107] (Example 1) In Example 1, a laminate was prepared by sandwiching one test piece between two EVA films and further sandwiching it with two release films from the outside. As each EVA film, Mersene G (thickness 0.38 mm) manufactured by Tosoh Corporation was used. As each release film, an ETFE film manufactured by AGC Inc. was used.

[0108] Next, the prepared laminate was placed in a vacuum packaging bag (heat-resistant barrier laminated standard bag 400×500 mm R-4050 H manufactured by Meiwa Sangyo Co., Ltd.), subjected to decompression suction to degas the air remaining at the interface of each layer, and sealed. This was heated at 110 °C for 30 minutes under atmospheric pressure to obtain a transparent sheet.

[0109] (Example 2) In Example 2, a laminate was prepared using another test piece. After sealing the prepared laminate in a vacuum packaging bag, it was heated at 110 °C for 15 minutes under a pressure of 0.3 MPa using an autoclave. In the same manner as in Example 1, a transparent sheet was obtained.

[0110] (Example 3) In Example 3, a laminate was prepared using the remaining test piece. After sealing the prepared laminate in a vacuum packaging bag, it was heated at 110 °C for 15 minutes under a pressure of 1.0 MPa using an autoclave. In the same manner as in Example 1, a transparent sheet was obtained.

[0111] (Evaluation) The thickness of the xerogel layer after lamination was determined as the difference between the thickness T1 (see Fig. 12) at the center in the longitudinal direction of the transparent sheet and the thickness T2 (see Fig. 12) at one end in the longitudinal direction of the transparent sheet.

[0112] The compression ratio CR of the xerogel layer after lamination was determined using the formula CR = (TB - TA) / TB × 100. TB is the thickness of the xerogel layer before lamination, and TA is the thickness of the xerogel layer after lamination.

[0113] The transmittance of the transparent sheet after lamination was measured in the same manner as the transmittance of the xerogel layer before lamination.

[0114] The strength of the transparent sheet after lamination was evaluated by the method shown in Fig. 12. Specifically, both ends in the longitudinal direction of the transparent sheet 101 were grasped with a pair of U-shaped jigs 100, the transparent sheet 101 was bent, and the radius of curvature r was calculated by the Newton-Raphson method from the chord length d and the sagitta h when the xerogel layer broke.

[0115] The evaluation results are shown in Table 1.

[0116]

Table 1

[0117] As described above, the transparent sheet, laminated glass, and glass laminate according to the present invention have been described, but the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope described in the claims. Naturally, they also belong to the technical scope of the present invention.

Explanation of Reference Numerals

[0118] 20 Transparent sheet 21 Xerogel layer 25 First lamination layer 26 The second bonding layer

Claims

1. A xerogel layer, A first bonding layer and a second bonding layer that are bonded to each other in a state of being compressed while sandwiching the xerogel layer in the thickness direction, and comprising The compression rate in the thickness direction of the xerogel layer is 0.5% to 20%, A transparent sheet.

2. The first bonding layer and the second bonding layer are in contact with the xerogel layer and contain ethylene-vinyl acetate copolymer resin (EVA resin). The transparent sheet according to Claim 1.

3. The first bonding layer and the second bonding layer contain a plasticizer, A first barrier layer for suppressing the migration of the plasticizer from the first bonding layer to the xerogel layer is provided between the first bonding layer and the xerogel layer, A second barrier layer for suppressing the migration of the plasticizer from the second bonding layer to the xerogel layer is provided between the second bonding layer and the xerogel layer. The transparent sheet according to Claim 1.

4. The first bonding layer and the second bonding layer contain polyvinyl butyral resin (PVB resin). The transparent sheet according to Claim 3.

5. The first bonding layer and the second bonding layer are bonded together over the entire periphery. The transparent sheet according to any one of Claims 1 to 4.

6. The first bonding layer and the second bonding layer are bonded together on two opposite sides. The transparent sheet according to any one of Claims 1 to 4.

7. A first glass plate, A second glass plate facing the first glass plate, An intermediate sheet disposed between the first glass plate and the second glass plate, and comprising The intermediate sheet is the transparent sheet according to any one of Claims 1 to 6. A laminated glass.

8. The laminated glass according to claim 7, wherein the first glass plate, the second glass plate, and the intermediate sheet have a curved shape.

9. The laminated glass according to claim 7 or 8, wherein at least one of the first glass plate and the second glass plate contains inorganic glass.

10. The laminated glass according to claim 9, wherein one of the first glass plate and the second glass plate contains organic glass.

11. A first glass plate, The transparent sheet according to any one of claims 1 to 6 laminated on the first glass plate, A glass laminate comprising.

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