JP2023000852A - Transparent sheet, laminated glass, and glass laminate - Google Patents

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

The present invention relates to transparent sheets, laminated glass, and glass laminates.

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

The multi-layer glass described in Patent Document 2 includes two sheet glasses, a flat transparent porous body sandwiched between the two sheet glasses, and a window frame. The transparent porous material uses methylated silica xerogel. The window frame clamps the transparent porous body from both sides by fixing the gap between the two sheets of glass.

The heat-insulating transparent porous body described in Patent Literature 3 includes an airgel and a protective coating made of a transparent resin on all or part of the surface of the airgel. The protective film is a film in which low-density polyethylene is laminated on an ethylene/vinyl acetate copolymer, which is a thermosoftening resin.

WO2018/155551 JP 2009-286685 A JP-A-10-324585

The xerogel layer was fragile and sometimes cracked due to handling before it was sandwiched between two sheets of glass and fixed.

Patent Documents 1 and 3 describe stacking an airgel layer and a resin layer, but the strength of the airgel layer is insufficient.

Patent Document 2 does not discuss a technique for improving the strength of the xerogel layer before fixing it by sandwiching it between two sheets of plate glass.

One aspect of the present invention provides techniques for improving the strength of xerogel layers.

[1] A transparent sheet according to an aspect of the present invention comprises a xerogel layer, a first bonding layer and a second bonding layer which are bonded to each other in a state in which the xerogel layer is sandwiched in the thickness direction and compressed, Prepare.

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

[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 the ethylene-vinyl acetate copolymer Contains resin (EVA resin).

[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 between the first bonding layer and the xerogel layer that suppresses migration of the plasticizer from the first bonding layer to the xerogel layer. The transparent sheet includes a second barrier layer between the second bonding layer and the xerogel layer that suppresses migration of the plasticizer from the second bonding layer to the xerogel layer.

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

[6] The transparent sheet according to any one of [1] to [5] above, wherein the first lamination layer and the second lamination layer are laminated along the entire periphery.

[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 at two sides facing each other. there is

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

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

[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.

[11] In the laminated glass according to [10] above, one of the first glass plate and the second glass plate contains an organic glass.

[12] A glass laminated plate according to an aspect of the present invention includes a first glass plate, the transparent sheet according to any one of [1] to [7] laminated on the first glass plate, Prepare.

According to one aspect of the present invention, the strength of the xerogel layer can be improved by compressing the xerogel layer in the thickness direction.

FIG. 1 is a flow chart showing a method for manufacturing a xerogel layer according to the first embodiment. FIG. 2 is a cross-sectional view showing a laminate and a vacuum bag according to the first embodiment. FIG. 3 is a cross-sectional view showing an example of a state in which the inside of the vacuum bag shown in FIG. 2 is evacuated. FIG. 4 is a cross-sectional view showing the transparent sheet according to the first embodiment. FIG. 5 is a cross-sectional view showing a laminate and a pair of nip rollers according to the first embodiment. FIG. 6 is a cross-sectional view showing the laminated glass according to the first embodiment. FIG. 7 is a cross-sectional view showing a modified example of laminated glass. FIG. 8 is a cross-sectional view showing a laminate and a vacuum bag according to the second embodiment. FIG. 9 is a cross-sectional view showing an example of a state in which the inside of the vacuum bag shown in FIG. 8 is vacuumed. FIG. 10 is a cross-sectional view showing a transparent sheet according to the second embodiment. FIG. 11 is a cross-sectional view showing a laminate and a pair of nip rollers according to the second embodiment. FIG. 12 is a cross-sectional view showing an example of a transparent sheet breaking test method.

First, terms used in the present specification and claims will be explained. "Gel" includes both "wet gel" and "xerogel".

A "wet gel" means a gel in which the three-dimensional network is swollen with 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.

The term "xerogel" is defined in the "Sols, Gels, Networks, and Structures and Processes of Inorganic-Organic Composites" of the "International Union of Pure and Applied Chemistry (IUPAC) Inorganic Chemistry Committee and Polymer Terminology Subcommittee". Definition (IUPAC Recommendation 2007)” means “a gel consisting of an open network formed by removing the swelling agent from the gel”. There are also classification methods such as aerogels that have had the swelling agent removed by supercritical drying, xerogels that have had the swelling agent removed by normal evaporative drying, and cryogel that have had the swelling agent removed by freeze drying. In the claims, these are collectively referred to as xerogels.

"~" indicating a numerical range means that the numerical values before and after it are included as lower and upper limits.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each drawing, the same reference numerals are given to the same or corresponding configurations, and explanations thereof may be omitted.

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

Note that the method for producing a xerogel layer may not include all the processes shown in FIG. may Also, the method of manufacturing the xerogel layer may include a process different from the process shown in FIG.

In step S1, a raw material liquid is prepared. The raw material liquid is selected according to the type of xerogel. Types of xerogels are, for example, (1) polysiloxane xerogels, but may also be selected from (2) polymeric xerogels, and (3) polysaccharide xerogels such as cellulose xerogels.

The raw material liquid includes, for example, a gel raw material (hereinafter also referred to as "gel raw material") and a solvent that dissolves the gel raw material. The gel raw material is appropriately selected according to the type of xerogel to be finally obtained. Solvents are, for example, water or organic solvents. Examples of organic solvents include alcohols (methanol, ethanol, isopropyl alcohol, tert-butyl alcohol, benzyl alcohol, etc.), aprotic polar organic solvents (N,N-dimethylformamide, dimethylsulfoxide, N,N-dimethylacetamide, etc. ), ketones (cyclopentanone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, acetone, etc.), or hydrocarbons (n-hexane, heptane, etc.). A plurality of organic solvents may be used in combination.

When the xerogel is (1) a polysiloxane xerogel, the gel raw material includes, for example, (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.

(1A) Silane compounds include alkoxysilanes, 6-membered ring-containing silane compounds having a 6-membered ring-containing skeleton and a hydrolyzable silyl group, silyl group-containing polymers having an organic polymer skeleton and a hydrolyzable silyl group, and the like. mentioned.

Examples of alkoxysilanes include tetraalkoxysilanes (tetramethoxysilane, tetraethoxysilane, etc.), monoalkyltrialkoxysilanes (methyltrimethoxysilane, methyltriethoxysilane, etc.), dialkyldialkoxysilanes (dimethyldimethoxysilane, dimethyldimethoxysilane, etc.). ethoxysilane, etc.), trimethoxyphenylsilane, compounds having alkoxysilyl groups at both ends of the 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.), perfluoro Alkoxysilanes having a polyether 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, etc.) silane, allyldimethoxymethylsilane, allyldiethoxymethylsilane, etc.), alkoxysilanes having an epoxy group (2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, cydoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.), alkoxysilanes having an acryloyloxy group (3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropylmethyldimethoxysilane, etc.), methacryloyloxy group-containing alkoxysilanes (3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, etc.) and oligomers of the above alkoxysilanes. A plurality of the above materials may be used in combination.

The 6-membered ring-containing skeleton in the 6-membered ring-containing silane compound is, for example, an organic skeleton having a 6-membered ring composed of an isocyanurate ring, a triazine ring, a benzene ring, or the like.

The organic polymer backbone in the silyl group-containing polymer is, for example, an organic backbone having chains consisting of polyethylene chains, polyether chains, polyester chains, polycarbonate chains, or the like.

(1B) Catalysts include base catalysts and acid catalysts, and aqueous solutions thereof may be used. Examples of basic catalysts include amines (triethylamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, etc.), urea, ammonia, sodium hydroxide, potassium hydroxide, and the like. Examples of acid catalysts 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.). .

(1C) Surfactants include, for example, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, Pluronic (registered trademark) F127 and PE10500 (BASF trade name), or EH-208 (NOF Corporation trade name). is mentioned.

When the xerogel is (2) a polymer xerogel, examples of gel raw materials include thermoplastic resins and curable resins.

Examples of thermoplastic resins include those that can be dissolved in a solvent when heated and can form a monolith (porous body) when cooled. Specific examples include polymethyl methacrylate, polystyrene, and the like.

Examples of curable resins include photocurable resins and thermosetting resins. Examples of photocurable resins include those containing either one or both of acrylate and methacrylate and a photopolymerization initiator. Thermosetting resins include those containing either or both of acrylate and methacrylate and a thermal polymerization initiator, as well as addition condensates of resorcinol and formaldehyde, addition condensates of melamine and formaldehyde, and the like. mentioned.

When the xerogel is (3) polysaccharide xerogel, the gel raw material includes (3A) polysaccharide nanofibers and (3B) acid. Examples of polysaccharides include chitin, chitosan, gellan gum, etc., in addition to cellulose.

(3A) Polysaccharide nanofibers include, for example, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofibers. (3A) Examples of polysaccharide nanofibers include cellulose nanofibers as well as chitin nanofibers and chitosan nanofibers.

(3B) Acids include the above inorganic acids and the above organic acids. Bases can also be used instead of acids.

In step S2, the raw material liquid is injected into the container to prepare a raw material liquid layer containing the raw material liquid, and the prepared raw material liquid layer is gelled inside the container. Due to gelation, cross-linking proceeds throughout the raw material liquid to form a three-dimensional skeleton structure of the polymer. Gelation includes aging. Gelation results in a wet gel layer.

When the gel raw material contains (1A) a silane compound and (1B) a catalyst, gelation is performed by heating. A silane compound is hydrolyzed with an acid catalyst or the like to form a sol having a silanol group (Si—OH). When the sol is heated, the silanol groups undergo a dehydration condensation reaction between molecules to form Si--O--Si bonds, and the raw material solution is gelled.

The means for gelling the raw material liquid layer is not limited to the heater, and may be appropriately selected according to the type of gel raw material.

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

When the gel raw material is a photocurable resin, the means for gelling the raw material liquid layer is a light source. The light source irradiates the material liquid layer with light such as ultraviolet rays to cure the photocurable monomer and gel the material liquid layer.

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

When the gel raw material is polysaccharide nanofibers, the polysaccharide nanofibers gel in a short time upon contact with an acid catalyst or a base catalyst. Therefore, the raw material liquid may contain polysaccharide nanofibers and not contain an acid catalyst or a base catalyst. The acid catalyst or base catalyst may be supplied in the form of a shower from above to the raw material liquid layer. In this case, the means for gelling the raw material liquid layer is a feeder for supplying the acid catalyst or basic catalyst from above to the raw material liquid layer.

In the final stage of gelation, curing shrinkage occurs, and the outer circumference of the wet gel layer may be peeled off from the side wall of the container by the curing shrinkage.

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 containing a solvent inside. Solvent replacement (step S3) is performed before drying (step S4) to suppress shrinkage of the wet gel layer due to the surface tension of the solvent during drying and to suppress damage to the microstructure of the wet gel layer. carried out for the purpose.

In the solvent replacement, the solvent contained inside the wet gel layer is replaced from the solvent suitable for gelation (that is, the solvent of the raw material liquid) with the solvent suitable for drying. The solvent after substitution is appropriately selected according to the drying method. As a drying method, supercritical drying, freeze drying, or normal pressure drying is used.

Supercritical drying replaces the solvent contained inside the wet gel layer with a supercritical fluid. Solvents suitable for supercritical drying include, for example, methanol, ethanol, or isopropyl alcohol. Carbon dioxide gas in a supercritical state is generally used as the supercritical fluid. Supercritical drying is carried out inside a closed high-pressure vessel.

Freeze-drying freezes the solvent contained inside the wet gel layer and then evaporates it in a vacuum. This is commonly called sublimation. Solvents suitable for freeze-drying include water, tert-butyl alcohol, cyclohexane, 1,4-dioxane, fluorine-based solvents, and the like. Freeze-drying is performed inside a closed vacuum vessel.

Normal pressure drying evaporates the solvent contained inside the wet gel layer under normal pressure. Since it is important to reduce the contraction force of the microskeleton of the wet gel layer due to the capillary force that accompanies solvent evaporation, solvents suitable for normal pressure drying include solvents with low surface tension, such as low molecular weight fats such as hexane and heptane. Group hydrocarbon-based solvents or fluorine-based solvents are used. Since normal pressure drying is performed at normal pressure, a sealed container is not required.

Solvent replacement is performed at a temperature below the boiling point of the solvent in order to prevent the microstructure of the wet gel layer from being damaged by the boiling of the solvent. However, the solvent may be heated at a temperature below the boiling point in order to increase the replacement efficiency of the solvent. The heating temperature is, for example, 40.degree. C. to 100.degree.

The number of solvent substitutions is one in the present embodiment, but may be multiple times. That is, the solvent contained in the wet gel layer is replaced from the solvent of the raw material liquid by the first solvent having a composition different from the solvent of the raw material liquid, and further, the solvent of the raw material liquid and the first solvent having a composition different from the first solvent. 2 solvents may be substituted.

When the compatibility between the solvent of the raw material liquid and the second solvent is low, the substitution efficiency becomes poor. can reduce the time required to replace As the first solvent, one having high compatibility with both the solvent of the raw material liquid and the second solvent is used.

In addition, when the solvent of the raw material liquid is suitable for drying, solvent replacement is unnecessary.

In step S4, the solvent contained inside the wet gel layer is removed. As a method for drying the wet gel layer, supercritical drying, freeze drying, or normal pressure drying is used as described above. Among these, normal pressure drying is superior in that it does not require a closed container.

Atmospheric drying is performed at a temperature below the boiling point of the solvent in order to prevent the microstructure of the wet gel layer from being damaged by the boiling of the solvent. However, the wet gel layer may be heated at a temperature below the boiling point in order to increase the removal efficiency of the solvent. The drying temperature of the wet gel layer is, for example, room temperature to 100°C.

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

A xerogel layer is obtained by drying (step S4). 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 includes xerogel. Xerogels may be porous monoliths that are transparent and thermally insulating. A xerogel layer having transparency and thermal insulation properties is used, for example, as a transparent thermal insulator in automotive glazings and building glazings.

When the xerogel layer is used as 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 thickness of 1 mm. The transmittance is measured according to Japanese Industrial Standards (JIS R 3106:1998). As a device for measuring transmittance, for example, a spectrophotometer (Solid Spec-3700DUV) manufactured by Shimadzu Corporation is used.

Applications of xerogel layers include, for example, filters, adsorbents, sound absorbers, moisture absorbers, oil absorbers, and separation membranes, in addition to heat insulators.

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

The first release film 41 prevents the bonding of the vacuum bag 50 and the first bonding layer 25 and is peeled off from the first bonding layer 25 after being removed from the vacuum bag 50 . The second release film 42 prevents lamination of the vacuum bag 50 and the second lamination layer 26 and is peeled off from the second lamination layer 26 after being removed from the vacuum bag 50 . Note that the laminate 40 may not include the first release film 41 and the second release film 42, and the inner surface of the vacuum bag 50 may be coated with a release agent. 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, the laminated glass can be produced by the steps shown in FIG.

As shown in FIG. 3, the vacuum bag 50 is heated from the outside while the pressure inside the vacuum bag 50 is reduced. The internal pressure of the vacuum bag 50 is, for example, -100 kPa to -65 kPa with reference to the atmospheric pressure. The heating temperature of the vacuum bag 50 is, for example, 70.degree. C. to 110.degree. After that, the laminated body 40 taken out from the vacuum bag 50 is thermocompressed under a pressure of 0.3 MPa to 1.3 MPa while being heated at 100.degree. C. to 150.degree. For example, an autoclave is used for thermocompression bonding.

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 in which the xerogel layer 21 is sandwiched in the thickness direction and compressed. In addition, the number of xerogel layers 21 arranged 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 like a tile.

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 suffices if the xerogel layer 21 can be maintained in a compressed state in the thickness direction. The xerogel layer 21 has a higher resistance to compressive stress than to tensile stress. If compressive stress is applied to the xerogel layer 21 in advance, it is possible to suppress the generation of tensile stress during handling. Therefore, the strength of the xerogel layer 21 can be improved, and the handleability can be improved.

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

If the compressibility CR is 0.5% or more, the compressive stress is large and the strength is high. If the compressibility 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 compressibility CR is preferably 1% or more, more preferably 5% or more.

The first bonding layer 25 and the second bonding layer 26 include, but are not limited to, ethylene-vinyl acetate copolymer resin (EVA resin) or polyvinyl butyral resin (PVB resin), for example. PVB resin is superior in penetration resistance to EVA resin, and is suitable for automobile windshields and the like. However, unlike EVA resin, PVB resin contains a plasticizer. A plasticizer is an additive for enhancing flexibility, but when it migrates to the xerogel layer 21, it destroys the microstructure 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. A specific example of a thermoplastic resin that does not contain a plasticizer is EVA resin.

The transparent sheet 20 shown in FIG. 4 may be produced using a pair of nip rollers 51 as shown in FIG. 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 .

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 different side edges of the first bonding layer 25 and the second bonding layer 26 . The first bonding layer 25 and the second bonding layer 26 sandwich the xerogel layer 21 in the thickness direction and maintain the compressed state, thereby improving the strength of the xerogel layer 21 .

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

Although the laminate 40 shown in FIG. 5 includes the first release film 41 and the second release film 42, it may not include the first release film 41 and the second release film 42, and the outer peripheral surface of the nip roller 51 may be coated with a release agent. Further, although the details will be described later, the roller 52 may have 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 .

Next, the laminated glass 30 according to the first embodiment will be described with reference to FIG. 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. Prepare. The intermediate sheet 33 is, for example, the transparent sheet 20 shown in FIG. In addition, the transparent sheet 20 may have portions protruding from the end faces of the first glass plate 31 and the end faces of the second glass plate 32 cut off.

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

The transparent sheet 20 has a uniform thickness, but may have a non-uniform thickness. For example, when the image of the head-up display is projected onto the laminated glass 30, the thickness of the transparent sheet 20 may increase from the bottom to the top in order to prevent the image from appearing double. In this case, the transparent sheet 20 is formed in a wedge shape with a wedge angle of, for example, 1.0 mrad or less.

The first glass plate 31 and the second glass plate 32 may be made of the same material or different materials. The material of the first glass plate 31 and the second glass plate 32 may be inorganic glass or organic glass. At least one of the first glass plate 31 and the second glass plate 32 preferably contains inorganic glass. The remaining one may be an inorganic glass or an organic glass.

Examples of organic glass include acrylic resins and polycarbonate resins. Examples of inorganic glass include soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, borosilicate glass, and the like. A method for forming the inorganic glass into a plate is not particularly limited, and for example, a float method.

The first glass plate 31 and the second glass plate 32 may be untempered glass (raw glass). Untempered glass is glass obtained by molding molten glass into a plate shape and then slowly cooling it, and is glass that has not undergone tempering treatment such as air-cooling tempering treatment or chemical tempering treatment. Untempered glass is less likely to cause mesh-like or spider-web-like cracks when it is shattered by impact, and can ensure visibility.

The thickness of the first glass plate 31 and the thickness of the second glass plate 32 may be the same or different. When the first glass plate 31 is provided on the vehicle outer side 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 entire laminated glass 30 is 2.3 mm or more and 8.0 mm or less.

The laminated glass 30 is manufactured similarly to 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 the vacuum bag, and the vacuum bag is heated from the outside while reducing the pressure inside the vacuum bag. After that, the laminated body taken out from the vacuum bag is thermocompression bonded, for example, in an autoclave. Thereby, the laminated glass 30 is obtained.

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 may have 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 depressurizing the inside of the vacuum bag, and suppresses entrapment of air bubbles in the laminated glass 30 .

The laminated glass 30 is used, for example, as an automobile window glass. As shown in FIG. 7, the laminated glass 30 may be wholly or partially curved convexly toward the outside of the vehicle. The laminated glass 30 has a compound curve that curves in the front-rear direction and the up-down direction of the vehicle, but may be a single curve that curves only in the front-rear direction or the up-down direction.

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

According to this embodiment, compressive stress is applied to the xerogel layer 21 before bending, so it is possible to suppress the generation of tensile stress in the xerogel layer 21 during bending. Therefore, cracking of the xerogel layer 21 can be suppressed during bending.

7, the first glass plate 31, the intermediate sheet 33, and the second glass plate 32 constitute the laminated glass 30, but the first glass plate 31 and the intermediate sheet 33 may constitute a glass laminate. . That is, the glass laminate may have a glass plate only on one side of the intermediate sheet 33 . The same applies to the second embodiment described below.

Next, a transparent sheet 20 according to a second embodiment will be described with reference to FIGS. 8 to 10. FIG. The transparent sheet 20 of the present embodiment can also be used as an intermediate sheet of the laminated glass 30. Differences between the first embodiment and the second embodiment will be mainly described below.

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

As shown in FIG. 9, the vacuum bag 50 is heated from the outside while the pressure inside the vacuum bag 50 is reduced. After that, the laminate 40 taken out from the vacuum bag 50 is thermocompression bonded, for example, in an autoclave. As a result, a transparent sheet 20 is obtained as shown in FIG.

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 in which the xerogel layer 21 is sandwiched in the thickness direction and compressed. In addition, the number of xerogel layers 21 arranged 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 like a tile.

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 suffices if the xerogel layer 21 can be maintained in a compressed state in the thickness direction. The xerogel layer 21 has a higher resistance to compressive stress than to tensile stress. If compressive stress is applied to the xerogel layer 21 in advance, it is possible to suppress the generation of tensile stress during handling. Therefore, the strength of the xerogel layer 21 can be improved, and the handleability can be improved.

The first barrier layer 22 is used when the first bonding layer 25 contains a plasticizer. The first barrier layer 22 is arranged between the first bonding layer 25 and the xerogel layer 21 to suppress migration of the plasticizer from the first bonding layer 25 to the xerogel layer 21 . By including the plasticizer in the first bonding layer 25 while suppressing the destruction of the microstructure of the xerogel layer 21 by the plasticizer by the first barrier layer 22 , the penetration resistance of the laminated glass 30 can be improved. Specific examples of thermoplastic resins containing plasticizers include, for example, PVB resins.

The second barrier layer 23 is used when the second bonding layer 26 contains a plasticizer. The second barrier layer 23 is arranged between the second bonding layer 26 and the xerogel layer 21 to suppress migration of the plasticizer from the second bonding layer 26 to the xerogel layer 21 . By including the plasticizer in the second bonding layer 26 while suppressing the destruction of the microstructure of the xerogel layer 21 by the plasticizer by the second barrier layer 23, the penetration resistance of the laminated glass 30 can be improved.

The transparent sheet 20 shown in FIG. 10 may be produced using a pair of nip rollers 51 as shown in FIG. Although the laminate 40 shown in FIG. 11 includes the first release film 41 and the second release film 42, it may not include the first release film 41 and the second release film 42, and the outer peripheral surface of the nip roller 51 may be coated with a release agent. Moreover, the roller 52 may have 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 .

Experimental data will be described below. Example 1, which will be described later, is a comparative example, and Examples 2 and 3, which will be described later, are examples.

(xerogel layer)
First, a sol liquid, which is a raw material liquid, 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 5 mmol / L acetic acid aqueous solution, 30 g of urea, hexadecyltrimethylammonium 10 g of bromide (manufactured by Tokyo Kasei Kogyo Co., Ltd.) is placed in a plastic container containing a magnetic stirrer and stirred at 800 rpm for 60 minutes at 25° C. to hydrolyze the alkoxysilane to form a sol to prepare a sol solution. did.

Next, the sol liquid 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 lid attached to obtain a wet gel layer. rice field.

Next, the solvent contained in the wet gel layer was replaced. Specifically, primary replacement of water with methanol, secondary replacement of methanol with isopropanol, and tertiary replacement of isopropanol with heptane were performed. In the primary replacement, immersion of the wet gel layer in methanol for 8 hours was repeated three times, and methanol was replaced between the first and second times and between the second and third times. Secondary substitution and tertiary substitution were also carried out in the same manner as the primary substitution.

Next, the wet gel layer after tertiary substitution was placed in an oven at 50° C. and dried under normal pressure for 24 hours to obtain a transparent polysiloxane gel as a xerogel layer. The thickness of the polysiloxane gel was 9.4 mm. After that, the polysiloxane gel was cut into three rectangular test pieces each having a length of 110 mm, a width of 30 mm and a thickness of 9.4 mm. No difference in appearance was observed for the three specimens. Table 1 shows the thickness and transmittance of each test piece.

(Example 1)
In Example 1, a laminate was produced by sandwiching one test piece between two EVA films and then sandwiching it between two release films from the outside. As each EVA film, Tosoh's product name Mersen G (thickness: 0.38 mm) was used. As each release film, an ETFE film manufactured by AGC was used.

Next, the produced laminate is placed in a vacuum packaging bag (heat-resistant barrier laminate standard bag 400 x 500 mm R-4050 H manufactured by Meiwa Sansho Co., Ltd.) and vacuum suction is performed to deaerate air remaining at the interface of each layer and seal. did. This was heated at 110° C. for 30 minutes under atmospheric pressure to obtain a transparent sheet.

(Example 2)
In Example 2, a laminate was produced using another test piece, and after sealing the produced laminate in a vacuum packaging bag, a pressure of 0.3 MPa was applied using an autoclave, and 15 at 110 ° C. A transparent sheet was obtained in the same manner as in Example 1, except for heating for 1 minute.

(Example 3)
In Example 3, a laminate was produced using the remaining test pieces, and after sealing the produced laminate in a vacuum packaging bag, a pressure of 1.0 MPa was applied using an autoclave, and 15 at 110 ° C. A transparent sheet was obtained in the same manner as in Example 1, except for heating for 1 minute.

(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.

The compressibility 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.

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

The strength of the transparent sheet after lamination was evaluated by the method shown in FIG. Specifically, a pair of U-shaped jigs 100 hold both ends of the transparent sheet 101 in the longitudinal direction to bend the transparent sheet 101, and from the chord length d and the arrow height h when the xerogel layer breaks, the radius of curvature r was calculated by the Newton-Raphson method.

Table 1 shows the evaluation results.

表１から明らかなように、キセロゲル層を圧縮しなかった例１に比べて、キセロゲル層を圧縮した例２及び例３では、キセロゲル層が曲げ破断した時の曲率半径ｒが小さく、キセロゲル層の強度の大幅な向上が認められた。

As is clear from Table 1, in Examples 2 and 3 in which the xerogel layer was compressed, the radius of curvature r when the xerogel layer was bent and broken was smaller than in Example 1 in which the xerogel layer was not compressed. A significant improvement in strength was observed.

Although the transparent sheet, laminated glass, and glass laminate according to the present invention have been described above, the present invention is not limited to the above embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These also naturally belong to the technical scope of the present invention.

20 transparent sheet 21 xerogel layer 25 first bonding layer 26 second bonding layer

Claims (12)

a xerogel layer;
a first bonding layer and a second bonding layer that are bonded to each other in a state in which the xerogel layer is sandwiched in the thickness direction and compressed;
A transparent sheet. 2. The transparent sheet according to claim 1, wherein the xerogel layer has a compressibility of 0.5% to 20% in the thickness direction. 3. The transparent sheet according to claim 1, wherein the first bonding layer and the second bonding layer are in contact with the xerogel layer and contain an ethylene-vinyl acetate copolymer resin (EVA resin). The first bonding layer and the second bonding layer contain a plasticizer,
A first barrier layer is provided between the first bonding layer and the xerogel layer to suppress migration of the plasticizer from the first bonding layer to the xerogel layer,
3. The transparent sheet according to claim 1, further comprising a second barrier layer between the second bonding layer and the xerogel layer for suppressing migration of the plasticizer from the second bonding layer to the xerogel layer. 5. The transparent sheet according to claim 4, wherein the first bonding layer and the second bonding layer contain polyvinyl butyral resin (PVB resin). 6. The transparent sheet according to any one of claims 1 to 5, wherein the first lamination layer and the second lamination layer are laminated along the entire periphery. 6. The transparent sheet according to any one of claims 1 to 5, wherein the first bonding layer and the second bonding layer are bonded on two sides facing each other. 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;
with
A laminated glass, wherein the intermediate sheet is the transparent sheet according to any one of claims 1 to 7. The laminated glass according to claim 8, wherein the first glass plate, the second glass plate, and the intermediate sheet have curved shapes. 10. The laminated glass according to claim 8 or 9, wherein at least one of said first glass plate and said second glass plate comprises inorganic glass. 11. The laminated glass of Claim 10, wherein one of said first glass sheet and said second glass sheet comprises an organic glass. a first glass plate;
The transparent sheet according to any one of claims 1 to 7, which is laminated on the first glass plate;
A glass laminate.

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