US20070212534A1 - Article With Silica-Based Film and Process for Producing the Same - Google Patents

Article With Silica-Based Film and Process for Producing the Same Download PDF

Info

Publication number
US20070212534A1
US20070212534A1 US10/594,606 US59460605A US2007212534A1 US 20070212534 A1 US20070212534 A1 US 20070212534A1 US 59460605 A US59460605 A US 59460605A US 2007212534 A1 US2007212534 A1 US 2007212534A1
Authority
US
United States
Prior art keywords
film
silica
substrate
based film
article according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US10/594,606
Inventor
Teruyuki Sasaki
Kazuyuki Inoguchi
Kazutaka Kamitani
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Sheet Glass Co Ltd
Original Assignee
Nippon Sheet Glass Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Sheet Glass Co Ltd filed Critical Nippon Sheet Glass Co Ltd
Assigned to NIPPON SHEET GLASS COMPANY, LIMITED reassignment NIPPON SHEET GLASS COMPANY, LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: INOGUCHI, KAZUYUKI, KAMITANI, KAZUTAKA, SASAKI, TERUYUKI
Publication of US20070212534A1 publication Critical patent/US20070212534A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B32LAYERED PRODUCTS
    • B32BLAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/006Surface treatment of glass, not in the form of fibres or filaments, by coating with materials of composite character
    • C03C17/008Surface treatment of glass, not in the form of fibres or filaments, by coating with materials of composite character comprising a mixture of materials covered by two or more of the groups C03C17/02, C03C17/06, C03C17/22 and C03C17/28
    • C03C17/009Mixtures of organic and inorganic materials, e.g. ormosils and ormocers
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/006Surface treatment of glass, not in the form of fibres or filaments, by coating with materials of composite character
    • C03C17/007Surface treatment of glass, not in the form of fibres or filaments, by coating with materials of composite character containing a dispersed phase, e.g. particles, fibres or flakes, in a continuous phase
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04Coating
    • C08J7/0427Coating with only one layer of a composition containing a polymer binder
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00Chemical treatment or coating of shaped articles made of macromolecular substances
    • C08J7/04Coating
    • C08J7/046Forming abrasion-resistant coatings; Forming surface-hardening coatings
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D1/00Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D4/00Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2217/00Coatings on glass
    • C03C2217/20Materials for coating a single layer on glass
    • C03C2217/21Oxides
    • C03C2217/213SiO2
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2217/00Coatings on glass
    • C03C2217/40Coatings comprising at least one inhomogeneous layer
    • C03C2217/43Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase
    • C03C2217/44Coatings comprising at least one inhomogeneous layer consisting of a dispersed phase in a continuous phase characterized by the composition of the continuous phase
    • CCHEMISTRY; METALLURGY
    • C03GLASS; MINERAL OR SLAG WOOL
    • C03CCHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2218/00Methods for coating glass
    • C03C2218/10Deposition methods
    • C03C2218/11Deposition methods from solutions or suspensions
    • C03C2218/113Deposition methods from solutions or suspensions by sol-gel processes
    • CCHEMISTRY; METALLURGY
    • C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08JWORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2483/00Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen, or carbon only; Derivatives of such polymers
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913Rod, strand, filament or fiber
    • Y10T428/2933Coated or with bond, impregnation or core
    • Y10T428/2962Silane, silicone or siloxane in coating
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982Particulate matter [e.g., sphere, flake, etc.]
    • Y10T428/2991Coated
    • Y10T428/2993Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
    • Y10T428/2995Silane, siloxane or silicone coating
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/31504Composite [nonstructural laminate]
    • Y10T428/31652Of asbestos
    • Y10T428/31663As siloxane, silicone or silane

Definitions

  • the present invention relates to an article with a silica-based film, and a process for producing the same. Particularly, the present invention relates to an article on which a silica-based film, which has excellent mechanical strength even when thick, is formed by an improved sol-gel process, and to an article obtained by the production process.
  • silica-based films are hard and also can be used in the form of films that coat substrates.
  • a melting method a high temperature treatment is necessary for obtaining a silica-based film. This limits the materials of which the substrates and films can be made.
  • the sol-gel process is a process of obtaining an oxide in a solid state by: using a solution of an organic or inorganic compound of metal as a starting material; rendering the solution into a sol in which fine particles of metal oxides or hydroxides have dissolved, through the hydrolysis reaction and polycondensation reaction of the compound contained in the solution; further gelling and solidifying the sol; and heating this gel if necessary.
  • the sol-gel process allows silica-based films to be produced at lower temperatures.
  • Processes of forming silica-based films by the sol-gel process are disclosed in JP55(1980)-034258A, JP63(1988)-241076A, JP8(1996)-27422A, JP63(1988)-268772A, JP2002-088304A, JP5(1993)-85714A, JP6(1994)-52796A, JP63(1988)-168470A, and JP11(1999)-269657A, for example.
  • the silica-based films formed by the sol-gel process have lower mechanical strength than that of silica-based films obtained by the melting method.
  • JP11(1999)-269657A discloses a process for producing a silica-based film by applying an alcohol solution that is used as a coating solution to a substrate.
  • the alcohol solution contains 0.010 to 3 wt %, in terms of silica, of at least one selected from silicon alkoxide and hydrolysate thereof (including partial hydrolysate), 0.0010 to 1.ON of acid, and 0 to 10 wt % of water.
  • the silica-based film obtained by this process has strength to an extent that allows the film to withstand the dry abrasion test. It probably cannot be said that the silica-based film has sufficiently high strength, but it has high mechanical strength for a film obtained by the sol-gel process.
  • the thickness thereof is limited to 250 nm maximum when consideration is given to obtaining an appearance that is good enough for practical use.
  • the thickness of the silica-based film that is formed by the sol-gel process is generally around 100 to 200 nm.
  • a coating solution containing colloidal silica added thereto allows a film with a thickness exceeding 1 ⁇ m to be formed through a single application.
  • the film obtained using this coating solution has a pencil hardness of merely around 8H and does not have sufficiently high mechanical strength.
  • the film obtained thereby has increased thickness.
  • the silica-based film thus obtained does not have high characteristics in mechanical strength, particularly abrasion resistance. This is mainly because the coating solution is applied twice, which induces cracks in the film.
  • the present invention provides a novel sol-gel process for producing a silica-based film having excellent mechanical strength. According to the present invention, a silica-based film having excellent mechanical strength can be obtained even when the thickness thereof exceeds 300 nm.
  • the present invention provides an article with a silica-based film, which includes a substrate and a silica-based film that is formed on the surface of the substrate by a sol-gel process.
  • the thickness of the silica-based film is more than 300 nm and the silica-based film does not separate from the substrate after the Taber abrasion test prescribed in Japanese Industrial Standards (JIS) R 3212 that is carried out with respect to the surface of the silica-based film.
  • JIS Japanese Industrial Standards
  • the term “silica-based film” denotes a film in which silica is a component with the highest content.
  • the Taber abrasion test according to JIS R 3212 can be carried out using a commercially available Taber abrasion tester. This test is an abrasion test that is carried out at a rotation number of 1000, with a load of 500 g being applied, as prescribed in the JIS.
  • the present invention provides a process for producing an article with a silica-based film, which includes a substrate and a silica-based film that is formed on the surface of the substrate.
  • the process includes: applying a film-forming solution for forming the silica-based film to the surface of the substrate; and heating the substrate to which the film-forming solution has been applied.
  • the film-forming solution contains silicon alkoxide, strong acid, water, and alcohol.
  • the silicon alkoxide has a concentration of more than 3 mass % and less than 9 mass % in terms of a SiO 2 concentration when silicon atoms contained in the silicon alkoxide are expressed as SiO 2 .
  • the strong acid has a concentration in the range of 0.001 to 0.2 mol/kg in terms of the molality of protons that is obtained, assuming that the protons have dissociated completely from the strong acid.
  • the number of moles of the water is at least four times and at most ten times the total number of moles of the silicon atoms contained in the silicon alkoxide.
  • the substrate is heated at a temperature above 100° C.
  • a silica-based film that has excellent mechanical strength, even though its thickness exceeds 300 nm, can be formed by the sol-gel process.
  • the silicon alkoxide in the film-forming solution forms an oligomer having siloxane bonds through the hydrolysis reaction and polycondensation (dehydration condensation) reaction in the presence of water and a catalyst in the coating solution, and thereby the coating solution is changed into a sol state.
  • the coating solution in the sol state is applied to the substrate and then an organic solvent such as alcohol and water volatilize from the coating solution that has been applied.
  • an organic solvent such as alcohol and water volatilize from the coating solution that has been applied.
  • the oligomer is concentrated to have a higher molecular weight and eventually loses flowability.
  • a film of a semisolid gel is formed on the substrate.
  • gaps that are present in the network of the siloxane bonds are filled with the organic solvent and water.
  • the siloxane polymer contracts and thereby the film is cured.
  • the size of the gaps of the network that remain after gelation depends on the form of polymerization of silicon alkoxide in the solution.
  • the form of polymerization varies depending on pH of the solution.
  • the oligomer of silicon alkoxide tends to grow linearly.
  • the linear oligomer is folded and thereby forms a network structure.
  • the film obtained thereby is a dense film having relatively smaller gaps.
  • the microstructure is not strong. Therefore, the film tends to crack when the solvent and water volatilize from the gaps.
  • the present invention has been completed based on the following knowledge. That is, even when thick, a crack-free dense film can be formed under certain conditions when the concentration of strong acid, water content, etc. are adjusted appropriately in the acidic region that allows a relatively dense film to be formed.
  • Silanol has an isoelectric point of 2. This denotes that silanol can exist most stably in the coating solution when the solution has a pH of 2. That is, even if a large amount of hydrolyzed silicon alkoxide exists in the solution, the probability that oligomers are formed through the dehydration condensation reaction is very low when the solution has a pH of about 2. Consequently, hydrolyzed silicon alkoxide can exist in the form of monomers or in a lower degree of polymerization in the coating solution.
  • one alkoxyl group per molecule is hydrolyzed in silicon alkoxide and thereby the silicon alkoxide becomes silanol and is stabilized in this state.
  • silicon alkoxide becomes silanol and is stabilized in this state.
  • one of the alkoxyl groups is hydrolyzed and thereby it becomes silanol and is stabilized in this state.
  • the solution will have a pH of around 3 to 1 when a strong acid is added to the sol-gel solution so that the molality (mass molality) of protons (hereinafter also referred to simply as “proton concentration”) that is obtained, assuming that the protons have dissociated completely from the strong acid, is 0.001 to 0.1 mol/kg.
  • proton concentration molality of protons
  • silicon alkoxide can exist in the coating solution stably as monomeric or lower polymerized silanol.
  • a pH of around 2 denotes a relatively highly acidic state. In order to obtain such a pH, it is necessary to use a strong acid.
  • the coating solution of the present invention contains a mixed solvent of water and alcohol, but another solvent can be added thereto if necessary.
  • a solution having a pH of around 2 can be obtained by using a strong acid and adding it so that the molality of protons that is obtained, assuming that the protons have dissociated completely from the strong acid, is 0.001 to 0.2 mol/kg.
  • protons of the acid to be used whose acid dissociation constant in water is 4 or higher need not be taken into account.
  • the acid dissociation constant of acetic acid which is a weak acid, in water is 4.8
  • the protons of the acetic acid are not included in the proton concentration even when acetic acid is contained in the coating solution.
  • the strong acid denotes, specifically, an acid having protons whose acid dissociation constant in water is lower than 4.
  • the proton concentration is defined as a concentration that is determined when the protons have dissociated completely from the strong acid, as described above, is as follows. That is because in a mixed solution of water and an organic solvent such as alcohol, it is difficult to determine the degree of dissociation of a strong acid accurately.
  • the coating solution When the coating solution is applied to the substrate surface while being maintained at a pH of around 1 to 3 and then is dried, the hydrolysis is not completed and the film is filled densely with silicon alkoxide that is in a lower polymerized state. Accordingly, a considerably dense film with finer pores can be obtained.
  • this film is dense, the hardness thereof does not become higher than a certain degree due to insufficient hydrolysis, even when it is heated at 200 to 300° C.
  • excess water is added to silicon alkoxide so that the hydrolysis of silicon alkoxide is facilitated not only before the application of the coating solution but also after the application.
  • the film is cured even if it is not heated to a high temperature.
  • water having a maximum number of moles that is required for hydrolysis i.e. a number of moles that is at least four times the total number of moles of silicon atoms in silicon alkoxide, is added.
  • the drying step water evaporates in parallel with the volatilization of the solvent.
  • the number of moles of water be more than four times, for example, 5 to 10 times the total number of moles of the silicon atoms.
  • silicon alkoxide a maximum of four alkoxyl groups can bind to one silicon atom. Alkoxide that has a small number of alkoxyl groups requires a smaller number of moles of water for hydrolysis. Furthermore, even in the case of tetraalkoxysilane, in which four alkoxyl groups are bound to a silicon atom, the total number of moles of water required for hydrolysis of a polymerized material thereof (that is commercially available as, for instance, “Ethyl silicate 40” manufactured by COLCOAT Co., Ltd.) is less than four times that of the silicon atoms (the number of moles of water required for hydrolysis stoichiometrically is (2n+2) moles where n denotes the number of moles of Si contained in the polymerized material (n ⁇ 2)).
  • the number of moles of water required for the hydrolysis of silicon alkoxide may be less than four times the total number of moles of silicon atoms in the silicon alkoxide.
  • water is added in a number of moles that is at least four times the total number of moles of silicon atoms.
  • a thick film can be obtained by preparing the coating solution so that the concentration of silicon alkoxide is relatively high.
  • the silicon atoms contained in the silicon alkoxide exceeds 3 mass % in terms of the SiO 2 concentration when the silicon atoms are expressed as SiO 2 .
  • the concentration of the silicon alkoxide should be adjusted so as to be 9 mass % or less in terms of the above-mentioned SiO 2 concentration. This is because when the concentration of the silicon alkoxide becomes excessively high, shrinkage of the film in the drying step becomes large and thereby a crack may occur in the film, resulting in deterioration of mechanical strength of the film.
  • the mole number of water should be at most 10 times the total mole number of silicon atoms. This is because when too much water is present, shrinkage of the film in the drying step becomes high and thereby a crack may occur in the film, resulting in deterioration of mechanical strength of the film.
  • the present invention provides an article with a silica-based film formed on a substrate.
  • the silica-based film does not separate from the substrate even after having been subjected to the Taber abrasion test prescribed in JIS R 3212 even when thick.
  • the thickness of the silica-based film can exceed 300 nm. Moreover, it is possible that the film thickness be 350 nm or more, furthermore, 400 nm or more, and still furthermore, 450 or more, if necessary. According to the present invention, a considerably thick film can be formed. In order not to cause the separation of the film after the Taber abrasion test, however, it is recommended that the upper limit of the film thickness be less than lm, preferably less than 800 nm, and more preferably less than 700 nm.
  • the present invention also allows a portion that has been subjected to the Taber abrasion test to have a haze ratio of 4% or lower, further 3% or lower after the Taber abrasion test. This mechanical strength is comparable to that of a vitreous film obtained by the melting method.
  • the thick silica-based film having excellent mechanical strength can be formed even on a substrate that does not have particularly good heat resistance.
  • the substrate may be a glass plate or a resin plate.
  • the silica-based film of the present invention which is formed by the sol-gel process, may be free from the alkali component.
  • a glass plate for the melting method for example, a glass plate containing the alkali component typified by a soda-lime-silica glass plate is used as a substrate
  • the article according to the present invention has the glass plate containing the alkali component and the silica-based film that is formed on the surface of the plate and substantially free from the alkali component.
  • the term “substantially free from” is used with the meaning that a trace amount of the alkali such as an amount of the component diffused from the glass plate into the film may be contained.
  • the silica-based film in accordance with the present invention might contain a component other than silica and a remaining component that is derived from the film raw material and remains in the film, such as an acid and a remaining component derived from an alkoxyl group.
  • the silica-based film in accordance with the present invention can be formed with a large thickness and therefore, has an advantage in the addition of a functional material for imparting a variety of functions to the film.
  • Examples of the functional material that may be added to the silica-based film include various fine particles.
  • As the fine particles at least one selected from fine particles of conductive oxide and fine particles of an organic material is preferable.
  • the fine particles of conductive oxide are typically ITO (indium thin oxide) fine particles.
  • As the fine particles of an organic material fine latex particles, etc. are exemplified.
  • Heating of the fine ITO particles to 250° C. or higher deteriorates their heat shielding property.
  • the heating temperature of the substrate may be adjusted appropriately depending on the heat resistance of the functional material.
  • the silica-based film in accordance with the present invention may contain an organic material and on the other hand, may be substantially free from an organic material.
  • the term “substantially free from” is used with the meaning that a trace amount of an organic component that is derived from the organic raw material such as silicon alkoxide and an organic acid in the film-forming solution may be contained.
  • the silica-based film in accordance with the present invention may be a film that is substantially free from an organic material and may be a film that is free from a hydrophilic organic polymer.
  • the silicon alkoxide is preferably at least one selected from tetraalkoxysilane and a material made by polymerization of tetraalkoxysilane.
  • the silicon alkoxide and the polymerized material thereof may contain a hydrolyzed alkoxyl group.
  • the acid used in the production process of the present invention is preferably a strong acid.
  • the strong acid include hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, sulfuric acid, methanesulfonic acid, paratoluenesulfonic acid, and oxalic acid.
  • volatile acids can be used advantageously since they volatilize during heating and thus do not remain in the film that has been cured. The acid remaining in the film that has been cured may hinder binding of inorganic components and thereby may deteriorate the film hardness.
  • the process of the present invention includes a step of applying a film-forming solution and a step of heating the substrate to which the film-forming solution has been applied.
  • Liquid components contained in the film-forming solution for example, at least one part of and preferably substantially all of the water or alcohol, are removed in the heating step or in both of the heating step and a drying step that can be preformed prior to the heating step.
  • the substrate is heated to the temperature above 100° C., preferably above 150° C., and this heating allows the silica-based film to cure and thereby enhances mechanical strength of the film.
  • the heating temperature in this step is, for example, 400° C. or less, and preferably 300° C. or less, since an excessively high temperature causes cracks.
  • the silica-based film of the present invention has a comparable film hardness to that of molten glass although it is heat-treated at a relatively lower temperature. Hence, this silica-based film is suitable for practical use even when it is used for window glasses for automobiles or buildings.
  • the content (indicated in terms of silica) of silicon alkoxide (tetraethoxysilane), the proton concentration, and the content of water are indicated in Table 1.
  • the content of water was calculated to include water (0.35 mass %) contained in the ethyl alcohol.
  • the proton concentration was calculated, assuming that all the protons contained in the hydrochloric acid had dissociated.
  • the same methods of calculating the water content and proton concentration as those described above are employed in all the examples and comparative examples described below.
  • the film-forming solution was applied to a soda-lime-silicate glass substrate (100 ⁇ 100 mm) that had been washed, at a humidity (relative humidity) of 30% and at room temperature by a flow coating method. In this state, it was dried at room temperature for about 30 minutes. Thereafter, it was placed in an oven whose temperature had been raised to 200° C. beforehand and then was heated for 40 minutes. After that, it was cooled.
  • the film thus obtained was a 400-nm thick film that had high transparency and was free from cracks.
  • the hardness of the film was evaluated by the abrasion test according to JIS R 3212. That is, using a commercially available Taber abrasion tester (6150 ABRASER, manufactured by TABER INDUSTRIES), the film was subjected to abrasion 1000 times with a load of 500 g. The haze ratio was measured before and after the abrasion test. Table 1 indicates the film thickness, presence or absence of cracks, and presence or absence of film separation after the Taber test.
  • the haze ratio before the Taber abrasion test was 0.1%, and that after the test was 3.3%. It should be noted that the haze ratios of a molten glass sheet were measured before and after the Taber test of a molten glass sheet, as a blank. The haze ratio before the test was 0.0% and that after the test was 1.5%. The haze ratios were measured using HGM-2DP manufactured by SUGA TEST INSTRUMENTS Co., Ltd.
  • the glass sheet with a silica film produced in Example 1 is highly useful even when it is used for window glasses for automobiles or buildings.
  • a haze ratio is required to be 4% or lower after the Taber test.
  • Films were formed in a manner similar to Example 1, except that the mixing ratios of raw materials were changed.
  • the mixing ratios of raw materials are shown in Table 1 together with the film thicknesses and the results of Taber abrasion test.
  • Films were formed in a manner similar to Example 1, except that the mixing ratios of raw materials were changed.
  • the mixing ratios of raw materials are shown in Table 1 together with the film thicknesses and the results of Taber abrasion test.
  • Example 8 and 9 and Comparative Examples 3 and 4 only the addition amounts of water were changed.
  • Comparative Example 3 fine cracks accompanied by separation appeared and the film was separated by the Taber abrasion test.
  • Example 9 and Comparative Example 4 cracks appeared in a part of the film. However, after the film was subjected to the Taber abrasion test that was performed on the region where no crack appeared, the separation of the film was not observed in Example 9 but was observed in Comparative Example 4.
  • Films were formed in a manner similar to Example 1, except that the mixing ratios of raw materials were changed.
  • the mixing ratios of raw materials are shown in Table 1 together with the film thicknesses and the results of Taber abrasion test.
  • tetramethoxysilane methyl silicate, etc. can be used as silicon alkoxide.
  • an organically modified alkoxide may be used as silicon alkoxide.
  • the amount of organically modified silicon alkoxide be 10% or less of the number of moles of silicon atoms contained in silicon alkoxide that are not organically modified.
  • Strong acid to be used herein can be sulfuric acid, p-sulfonic acid, methanesulfonic acid, etc.
  • Alcohol to be used herein can be methyl alcohol, 1-propyl alcohol, isopropyl alcohol, t-butyl alcohol, etc.
  • metal oxides other than silica may be added to the silica-based film of the present invention.
  • chlorides, oxides, or nitrates of metals such as lithium, sodium, potassium, cesium, magnesium, calcium, cobalt, iron, nickel, copper, aluminum, gallium, indium, scandium, yttrium, lanthanum, cerium, zinc, etc. may be added to the coating solution.
  • boric acid or alkoxide of boron that has been chelated with beta-diketone such as acetylacetone.
  • oxychloride, oxynitrate, or alkoxide that has been chelated with beta-diketone can be added.
  • the article with the silica-based film according to the present invention is useful as an underlayer film, a protection film, a low reflection film, an ultraviolet ray shielding film, an infrared ray shielding film, a colored film and the like.

Abstract

The present invention provides an article with a silica-based film, wherein the film does not separate from a substrate after the Taber abrasion test prescribed in Japanese Industrial Standards (JIS) R 3212 although the thickness of the film formed by a sol-gel process exceeds 300 nm. This film can be formed by an improved sol-gel process, that is, a sol-gel process by using a coating solution wherein silicon alkoxide has a concentration of more than 3 mass % and less than 9 mass % in terms of a SiO2 concentration, the molality of protons is 0.001 to 0.2 mol/kg, and the number of moles of the water is at least four times and at most ten times the total number of moles of the silicon atoms, and by heating a substrate at the temperature above 100° C.

Description

    TECHNICAL FIELD
  • The present invention relates to an article with a silica-based film, and a process for producing the same. Particularly, the present invention relates to an article on which a silica-based film, which has excellent mechanical strength even when thick, is formed by an improved sol-gel process, and to an article obtained by the production process.
  • BACKGROUND ART
  • Generally, silica-based films are hard and also can be used in the form of films that coat substrates. However, when employing a melting method, a high temperature treatment is necessary for obtaining a silica-based film. This limits the materials of which the substrates and films can be made.
  • The sol-gel process is a process of obtaining an oxide in a solid state by: using a solution of an organic or inorganic compound of metal as a starting material; rendering the solution into a sol in which fine particles of metal oxides or hydroxides have dissolved, through the hydrolysis reaction and polycondensation reaction of the compound contained in the solution; further gelling and solidifying the sol; and heating this gel if necessary.
  • The sol-gel process allows silica-based films to be produced at lower temperatures. Processes of forming silica-based films by the sol-gel process are disclosed in JP55(1980)-034258A, JP63(1988)-241076A, JP8(1996)-27422A, JP63(1988)-268772A, JP2002-088304A, JP5(1993)-85714A, JP6(1994)-52796A, JP63(1988)-168470A, and JP11(1999)-269657A, for example.
  • Generally, the silica-based films formed by the sol-gel process have lower mechanical strength than that of silica-based films obtained by the melting method.
  • JP11(1999)-269657A discloses a process for producing a silica-based film by applying an alcohol solution that is used as a coating solution to a substrate. The alcohol solution contains 0.010 to 3 wt %, in terms of silica, of at least one selected from silicon alkoxide and hydrolysate thereof (including partial hydrolysate), 0.0010 to 1.ON of acid, and 0 to 10 wt % of water.
  • The silica-based film obtained by this process has strength to an extent that allows the film to withstand the dry abrasion test. It probably cannot be said that the silica-based film has sufficiently high strength, but it has high mechanical strength for a film obtained by the sol-gel process. However, in the case of the silica-based film that can be formed by the process disclosed in JP11(1999)-269657A, the thickness thereof is limited to 250 nm maximum when consideration is given to obtaining an appearance that is good enough for practical use. The thickness of the silica-based film that is formed by the sol-gel process is generally around 100 to 200 nm.
  • As is disclosed in JP63(1988)-168470A, a coating solution containing colloidal silica added thereto allows a film with a thickness exceeding 1 μm to be formed through a single application. However, the film obtained using this coating solution has a pencil hardness of merely around 8H and does not have sufficiently high mechanical strength.
  • When the coating solution is applied twice, the film obtained thereby has increased thickness. However, the silica-based film thus obtained does not have high characteristics in mechanical strength, particularly abrasion resistance. This is mainly because the coating solution is applied twice, which induces cracks in the film.
  • Consequently, it is difficult to obtain a silica-based film that has a thickness exceeding 250 nm and has excellent mechanical strength, by the sol-gel process.
  • DISCLOSURE OF INVENTION
  • The present invention provides a novel sol-gel process for producing a silica-based film having excellent mechanical strength. According to the present invention, a silica-based film having excellent mechanical strength can be obtained even when the thickness thereof exceeds 300 nm.
  • The present invention provides an article with a silica-based film, which includes a substrate and a silica-based film that is formed on the surface of the substrate by a sol-gel process. The thickness of the silica-based film is more than 300 nm and the silica-based film does not separate from the substrate after the Taber abrasion test prescribed in Japanese Industrial Standards (JIS) R 3212 that is carried out with respect to the surface of the silica-based film.
  • In this description, the term “silica-based film” denotes a film in which silica is a component with the highest content. The Taber abrasion test according to JIS R 3212 can be carried out using a commercially available Taber abrasion tester. This test is an abrasion test that is carried out at a rotation number of 1000, with a load of 500 g being applied, as prescribed in the JIS.
  • From another aspect, the present invention provides a process for producing an article with a silica-based film, which includes a substrate and a silica-based film that is formed on the surface of the substrate. The process includes: applying a film-forming solution for forming the silica-based film to the surface of the substrate; and heating the substrate to which the film-forming solution has been applied.
  • In the production process of the present invention, the film-forming solution contains silicon alkoxide, strong acid, water, and alcohol. The silicon alkoxide has a concentration of more than 3 mass % and less than 9 mass % in terms of a SiO2 concentration when silicon atoms contained in the silicon alkoxide are expressed as SiO2. The strong acid has a concentration in the range of 0.001 to 0.2 mol/kg in terms of the molality of protons that is obtained, assuming that the protons have dissociated completely from the strong acid. The number of moles of the water is at least four times and at most ten times the total number of moles of the silicon atoms contained in the silicon alkoxide.
  • In the production process of the present invention, the substrate is heated at a temperature above 100° C.
  • According to the present invention, a silica-based film that has excellent mechanical strength, even though its thickness exceeds 300 nm, can be formed by the sol-gel process.
  • DESCRIPTION OF THE INVENTION
  • First, the reason why the mechanical strength of the film is improved by the present invention is described below.
  • In the case of the sol-gel process using silicon alkoxide as a starting material, the silicon alkoxide in the film-forming solution (coating solution) forms an oligomer having siloxane bonds through the hydrolysis reaction and polycondensation (dehydration condensation) reaction in the presence of water and a catalyst in the coating solution, and thereby the coating solution is changed into a sol state.
  • The coating solution in the sol state is applied to the substrate and then an organic solvent such as alcohol and water volatilize from the coating solution that has been applied. In this drying step, the oligomer is concentrated to have a higher molecular weight and eventually loses flowability. Thus a film of a semisolid gel is formed on the substrate. Immediately after gelation, gaps that are present in the network of the siloxane bonds are filled with the organic solvent and water. When the solvent and water volatilize from the gel, the siloxane polymer contracts and thereby the film is cured.
  • In the case of a gel obtained by the conventional sol-gel process, gaps that have remained after the organic solvent and water are removed are not filled completely and remain as pores even after a heat treatment is carried out at a maximum temperature of around 400° C. When the pores remain, the film cannot have sufficiently high mechanical strength. Hence, conventionally, it has been considered that in order to obtain a sufficiently hard film, a heat treatment has to be carried out at a high temperature that exceeds 400° C., for example, at least 450° C. and preferably at least 500° C.
  • The relationship between the reaction and the temperature in the heat treatment of a silica-based film that is formed by the sol-gel process is described further in detail. When the heat treatment is carried out at around 100 to 150° C., the solvent and water in the coating solution evaporate. In the case where the heat treatment is carried out at around 250 to 400° C., when an organic material is contained in the raw material, the organic material decomposes and evaporates. Furthermore, when the heat treatment is carried out at a temperature of approximately 500° C. or higher, the gel skeleton contracts and thereby the film becomes dense.
  • The size of the gaps of the network that remain after gelation depends on the form of polymerization of silicon alkoxide in the solution.
  • The form of polymerization varies depending on pH of the solution. In an acidic solution, the oligomer of silicon alkoxide tends to grow linearly. When such a solution is applied to the substrate, the linear oligomer is folded and thereby forms a network structure. The film obtained thereby is a dense film having relatively smaller gaps. However, since the film is solidified, with the linear polymer being folded, the microstructure is not strong. Therefore, the film tends to crack when the solvent and water volatilize from the gaps.
  • On the other hand, in an alkaline solution, spherical oligomers tend to grow. When such a solution is applied to the substrate, a structure in which spherical oligomers are joined to each other is formed. Accordingly, the film obtained thereby has relatively large gaps. Since these gaps are formed through bonding and growth of the spherical oligomers, the film tends not to crack when the solvent and water volatilize from the gaps.
  • The present invention has been completed based on the following knowledge. That is, even when thick, a crack-free dense film can be formed under certain conditions when the concentration of strong acid, water content, etc. are adjusted appropriately in the acidic region that allows a relatively dense film to be formed.
  • Silanol has an isoelectric point of 2. This denotes that silanol can exist most stably in the coating solution when the solution has a pH of 2. That is, even if a large amount of hydrolyzed silicon alkoxide exists in the solution, the probability that oligomers are formed through the dehydration condensation reaction is very low when the solution has a pH of about 2. Consequently, hydrolyzed silicon alkoxide can exist in the form of monomers or in a lower degree of polymerization in the coating solution.
  • In the range where the pH is around 2, one alkoxyl group per molecule is hydrolyzed in silicon alkoxide and thereby the silicon alkoxide becomes silanol and is stabilized in this state. For example, in the case of tetraalkoxysilane that has four alkoxyl groups, one of the alkoxyl groups is hydrolyzed and thereby it becomes silanol and is stabilized in this state.
  • The solution will have a pH of around 3 to 1 when a strong acid is added to the sol-gel solution so that the molality (mass molality) of protons (hereinafter also referred to simply as “proton concentration”) that is obtained, assuming that the protons have dissociated completely from the strong acid, is 0.001 to 0.1 mol/kg. When the pH is adjusted in this range, silicon alkoxide can exist in the coating solution stably as monomeric or lower polymerized silanol. A pH of around 2 denotes a relatively highly acidic state. In order to obtain such a pH, it is necessary to use a strong acid.
  • The coating solution of the present invention contains a mixed solvent of water and alcohol, but another solvent can be added thereto if necessary. Similarly to the case of using such a mixed solvent, a solution having a pH of around 2 can be obtained by using a strong acid and adding it so that the molality of protons that is obtained, assuming that the protons have dissociated completely from the strong acid, is 0.001 to 0.2 mol/kg.
  • For the calculation of the molality of protons, protons of the acid to be used whose acid dissociation constant in water is 4 or higher need not be taken into account. For instance, since the acid dissociation constant of acetic acid, which is a weak acid, in water is 4.8, the protons of the acetic acid are not included in the proton concentration even when acetic acid is contained in the coating solution. In this description, the strong acid denotes, specifically, an acid having protons whose acid dissociation constant in water is lower than 4.
  • The reason why the proton concentration is defined as a concentration that is determined when the protons have dissociated completely from the strong acid, as described above, is as follows. That is because in a mixed solution of water and an organic solvent such as alcohol, it is difficult to determine the degree of dissociation of a strong acid accurately.
  • When the coating solution is applied to the substrate surface while being maintained at a pH of around 1 to 3 and then is dried, the hydrolysis is not completed and the film is filled densely with silicon alkoxide that is in a lower polymerized state. Accordingly, a considerably dense film with finer pores can be obtained.
  • Although this film is dense, the hardness thereof does not become higher than a certain degree due to insufficient hydrolysis, even when it is heated at 200 to 300° C. Hence, excess water is added to silicon alkoxide so that the hydrolysis of silicon alkoxide is facilitated not only before the application of the coating solution but also after the application. In the state where hydrolysis progresses readily, the film is cured even if it is not heated to a high temperature. Specifically, water having a maximum number of moles that is required for hydrolysis, i.e. a number of moles that is at least four times the total number of moles of silicon atoms in silicon alkoxide, is added.
  • In the drying step, water evaporates in parallel with the volatilization of the solvent. When this is taken into consideration, it is further preferable that the number of moles of water be more than four times, for example, 5 to 10 times the total number of moles of the silicon atoms.
  • In silicon alkoxide, a maximum of four alkoxyl groups can bind to one silicon atom. Alkoxide that has a small number of alkoxyl groups requires a smaller number of moles of water for hydrolysis. Furthermore, even in the case of tetraalkoxysilane, in which four alkoxyl groups are bound to a silicon atom, the total number of moles of water required for hydrolysis of a polymerized material thereof (that is commercially available as, for instance, “Ethyl silicate 40” manufactured by COLCOAT Co., Ltd.) is less than four times that of the silicon atoms (the number of moles of water required for hydrolysis stoichiometrically is (2n+2) moles where n denotes the number of moles of Si contained in the polymerized material (n≧2)). The higher the polymerization degree of the alkoxysilane material to be used, the smaller the number of moles of water required for hydrolysis. Hence, practically, the number of moles of water required for the hydrolysis of silicon alkoxide may be less than four times the total number of moles of silicon atoms in the silicon alkoxide. In the present invention, however, in view of the fact that addition of excess water is preferred, water is added in a number of moles that is at least four times the total number of moles of silicon atoms.
  • Addition of water in a number of moles exceeding that required for hydrolysis stoichiometrically accelerates the hydrolysis reaction of silicon alkoxide in the drying step. The variation of pH of the applied solution from the above-mentioned range due to volatilization of the solvent and vaporization of water also is one of the factors that accelerate hydrolysis. By forming a dense film and allowing the hydrolysis and polycondensation reaction to progress sufficiently as described above, a hard film is formed. As a result, a film with excellent mechanical strength can be obtained through a heat treatment that is carried out at a lower temperature than that employed conventionally.
  • The use of this method makes it possible to obtain a silica-based film that has excellent mechanical strength although being thick. A thick film can be obtained by preparing the coating solution so that the concentration of silicon alkoxide is relatively high. For example, the silicon atoms contained in the silicon alkoxide exceeds 3 mass % in terms of the SiO2 concentration when the silicon atoms are expressed as SiO2.
  • The concentration of the silicon alkoxide, however, should be adjusted so as to be 9 mass % or less in terms of the above-mentioned SiO2 concentration. This is because when the concentration of the silicon alkoxide becomes excessively high, shrinkage of the film in the drying step becomes large and thereby a crack may occur in the film, resulting in deterioration of mechanical strength of the film.
  • Further, the mole number of water should be at most 10 times the total mole number of silicon atoms. This is because when too much water is present, shrinkage of the film in the drying step becomes high and thereby a crack may occur in the film, resulting in deterioration of mechanical strength of the film.
  • With the improvement of the sol-gel process described above, the present invention provides an article with a silica-based film formed on a substrate. The silica-based film does not separate from the substrate even after having been subjected to the Taber abrasion test prescribed in JIS R 3212 even when thick.
  • The thickness of the silica-based film can exceed 300 nm. Moreover, it is possible that the film thickness be 350 nm or more, furthermore, 400 nm or more, and still furthermore, 450 or more, if necessary. According to the present invention, a considerably thick film can be formed. In order not to cause the separation of the film after the Taber abrasion test, however, it is recommended that the upper limit of the film thickness be less than lm, preferably less than 800 nm, and more preferably less than 700 nm.
  • The present invention also allows a portion that has been subjected to the Taber abrasion test to have a haze ratio of 4% or lower, further 3% or lower after the Taber abrasion test. This mechanical strength is comparable to that of a vitreous film obtained by the melting method.
  • According to the present invention, the thick silica-based film having excellent mechanical strength can be formed even on a substrate that does not have particularly good heat resistance. In the present invention, the substrate may be a glass plate or a resin plate.
  • In order to lower melting temperature, an alkali component such as Na and K often is contained in the glass raw material for the melting method. Contrary to this, the silica-based film of the present invention, which is formed by the sol-gel process, may be free from the alkali component. When a glass plate for the melting method, for example, a glass plate containing the alkali component typified by a soda-lime-silica glass plate is used as a substrate, the article according to the present invention has the glass plate containing the alkali component and the silica-based film that is formed on the surface of the plate and substantially free from the alkali component. Here, the term “substantially free from” is used with the meaning that a trace amount of the alkali such as an amount of the component diffused from the glass plate into the film may be contained.
  • The silica-based film in accordance with the present invention might contain a component other than silica and a remaining component that is derived from the film raw material and remains in the film, such as an acid and a remaining component derived from an alkoxyl group.
  • The silica-based film in accordance with the present invention can be formed with a large thickness and therefore, has an advantage in the addition of a functional material for imparting a variety of functions to the film.
  • Examples of the functional material that may be added to the silica-based film include various fine particles. As the fine particles, at least one selected from fine particles of conductive oxide and fine particles of an organic material is preferable. The fine particles of conductive oxide are typically ITO (indium thin oxide) fine particles. As the fine particles of an organic material, fine latex particles, etc. are exemplified.
  • Heating of the fine ITO particles to 250° C. or higher deteriorates their heat shielding property. In the present invention, the heating temperature of the substrate may be adjusted appropriately depending on the heat resistance of the functional material.
  • The silica-based film in accordance with the present invention may contain an organic material and on the other hand, may be substantially free from an organic material. Here, the term “substantially free from” is used with the meaning that a trace amount of an organic component that is derived from the organic raw material such as silicon alkoxide and an organic acid in the film-forming solution may be contained. The silica-based film in accordance with the present invention may be a film that is substantially free from an organic material and may be a film that is free from a hydrophilic organic polymer.
  • In the process of the present invention, the silicon alkoxide is preferably at least one selected from tetraalkoxysilane and a material made by polymerization of tetraalkoxysilane. The silicon alkoxide and the polymerized material thereof may contain a hydrolyzed alkoxyl group.
  • The acid used in the production process of the present invention, is preferably a strong acid. Examples of the strong acid include hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, sulfuric acid, methanesulfonic acid, paratoluenesulfonic acid, and oxalic acid. Among strong acids, volatile acids can be used advantageously since they volatilize during heating and thus do not remain in the film that has been cured. The acid remaining in the film that has been cured may hinder binding of inorganic components and thereby may deteriorate the film hardness.
  • The process of the present invention includes a step of applying a film-forming solution and a step of heating the substrate to which the film-forming solution has been applied. Liquid components contained in the film-forming solution, for example, at least one part of and preferably substantially all of the water or alcohol, are removed in the heating step or in both of the heating step and a drying step that can be preformed prior to the heating step.
  • In the heating step, the substrate is heated to the temperature above 100° C., preferably above 150° C., and this heating allows the silica-based film to cure and thereby enhances mechanical strength of the film. The heating temperature in this step is, for example, 400° C. or less, and preferably 300° C. or less, since an excessively high temperature causes cracks.
  • The silica-based film of the present invention has a comparable film hardness to that of molten glass although it is heat-treated at a relatively lower temperature. Hence, this silica-based film is suitable for practical use even when it is used for window glasses for automobiles or buildings.
  • Hereinafter, the present invention is described further in detail using examples.
  • EXAMPLE 1
  • First, 10.6 g of tetraethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.), 7.0 g of pure water, and 0.05 g of concentrated hydrochloric acid (35 mass %, manufactured by KANTO CHEMICAL CO., INC.) were added to 89.8 g of ethyl alcohol (manufactured by KATAYAMA CHEMICAL, Inc.). This was stirred and thus a film-forming solution was obtained.
  • With respect to this solution, the content (indicated in terms of silica) of silicon alkoxide (tetraethoxysilane), the proton concentration, and the content of water are indicated in Table 1. The content of water was calculated to include water (0.35 mass %) contained in the ethyl alcohol. The proton concentration was calculated, assuming that all the protons contained in the hydrochloric acid had dissociated. The same methods of calculating the water content and proton concentration as those described above are employed in all the examples and comparative examples described below.
  • Subsequently, the film-forming solution was applied to a soda-lime-silicate glass substrate (100×100 mm) that had been washed, at a humidity (relative humidity) of 30% and at room temperature by a flow coating method. In this state, it was dried at room temperature for about 30 minutes. Thereafter, it was placed in an oven whose temperature had been raised to 200° C. beforehand and then was heated for 40 minutes. After that, it was cooled. The film thus obtained was a 400-nm thick film that had high transparency and was free from cracks.
  • The hardness of the film was evaluated by the abrasion test according to JIS R 3212. That is, using a commercially available Taber abrasion tester (6150 ABRASER, manufactured by TABER INDUSTRIES), the film was subjected to abrasion 1000 times with a load of 500 g. The haze ratio was measured before and after the abrasion test. Table 1 indicates the film thickness, presence or absence of cracks, and presence or absence of film separation after the Taber test.
  • The haze ratio before the Taber abrasion test was 0.1%, and that after the test was 3.3%. It should be noted that the haze ratios of a molten glass sheet were measured before and after the Taber test of a molten glass sheet, as a blank. The haze ratio before the test was 0.0% and that after the test was 1.5%. The haze ratios were measured using HGM-2DP manufactured by SUGA TEST INSTRUMENTS Co., Ltd.
  • The glass sheet with a silica film produced in Example 1 is highly useful even when it is used for window glasses for automobiles or buildings. For the window glass for automobiles, a haze ratio is required to be 4% or lower after the Taber test.
  • EXAMPLES 2 TO 7 AND COMPARATIVE EXAMPLES 1 AND 2
  • Films were formed in a manner similar to Example 1, except that the mixing ratios of raw materials were changed. The mixing ratios of raw materials are shown in Table 1 together with the film thicknesses and the results of Taber abrasion test.
  • With respect to Examples 2 to 7 and Comparative Examples 1 and 2, only proton concentrations were changed. In Comparative Example 1 in which the proton concentration was decreased, application of the film-forming solution could not be performed since the glass plate repelled the film-forming solution. The reason is believed to be that hydrolysis of silicon alkoxide was extremely insufficient. In Example 7 in which the proton concentration was increased, cracks appeared in a part of the film. However, after the film was subjected to the Taber abrasion test that was performed on the region where no crack appeared, the separation of the film was not observed. In Comparative Example 2 in which the proton concentration was increased more, cracks appeared in the wider area than that of Example 7, and the film thickness could not be measured. After the film was subjected to the Taber abrasion test that was performed on the region where no crack appeared, the separation of the film was observed.
  • EXAMPLES 8 AND 9 AND COMPARATIVE EXAMPLES 3 AND 4
  • Films were formed in a manner similar to Example 1, except that the mixing ratios of raw materials were changed. The mixing ratios of raw materials are shown in Table 1 together with the film thicknesses and the results of Taber abrasion test.
  • With respect to Examples 8 and 9 and Comparative Examples 3 and 4, only the addition amounts of water were changed. In Comparative Example 3, fine cracks accompanied by separation appeared and the film was separated by the Taber abrasion test. In Example 9 and Comparative Example 4, cracks appeared in a part of the film. However, after the film was subjected to the Taber abrasion test that was performed on the region where no crack appeared, the separation of the film was not observed in Example 9 but was observed in Comparative Example 4.
  • EXAMPLES 10 TO 12 AND COMPARATIVE EXAMPLE 5
  • Films were formed in a manner similar to Example 1, except that the mixing ratios of raw materials were changed. The mixing ratios of raw materials are shown in Table 1 together with the film thicknesses and the results of Taber abrasion test.
  • With respect to Examples 10 to 12 and Comparative Example 5, only the addition amounts of silicon alkoxide were changed. In all examples, cracks appeared in a part of the film. However, after the film was subjected to the Taber abrasion test that was performed on the region where no crack appeared, the separation of the film was not observed in Examples 10 to 12 but was observed in Comparative Example 5. It should be noted that in Comparative Example 5, many cracks appeared so that the thickness of the film could not be measured.
    TABLE 1
    Silicon
    Alkoxide Water
    (in (to Si Film
    terms of Proton Content; Film Presence Separation
    SiO2; Concentration mole Thickness of after
    mass %) (mol/kg) ratio) (nm) Cracks Taber Test
    Example 1 3.1 0.004 8 400 No No
    Comparative 5.0 0.0001 7
    Example 1
    Example 2 5.0 0.001 7 480 No No
    Example 3 5.0 0.01 7 510 No No
    Example 4 5.0 0.02 7 480 No No
    Example 5 5.0 0.03 7 450 No No
    Example 6 5.0 0.05 7 480 No No
    Example 7 5.0 0.1 7 460 Yes No
    Comparative 5.0 0.3 7 Yes Yes
    Example 2
    Comparative 5.0 0.01 2 Yes Yes
    Example 3
    Example 8 5.0 0.01 4 430 No No
    Example 9 5.0 0.01 10 490 Yes No
    Comparative 5.0 0.01 15 460 Yes Yes
    Example 4
    Example 10 6.0 0.01 7 520 Yes No
    Example 11 7.0 0.01 7 630 Yes No
    Example 12 8.0 0.01 7 740 Yes No
    Comparative 9.0 0.01 7 Yes Yes
    Example 5
  • The examples and comparative examples described above are only examples for explaining the present invention. The present invention is not limited to these examples.
  • For instance, tetramethoxysilane, methyl silicate, etc. can be used as silicon alkoxide.
  • Furthermore, an organically modified alkoxide may be used as silicon alkoxide. In this case, however, it is preferable that the amount of organically modified silicon alkoxide be 10% or less of the number of moles of silicon atoms contained in silicon alkoxide that are not organically modified.
  • Strong acid to be used herein can be sulfuric acid, p-sulfonic acid, methanesulfonic acid, etc.
  • Alcohol to be used herein can be methyl alcohol, 1-propyl alcohol, isopropyl alcohol, t-butyl alcohol, etc.
  • Furthermore, metal oxides other than silica may be added to the silica-based film of the present invention.
  • For instance, chlorides, oxides, or nitrates of metals such as lithium, sodium, potassium, cesium, magnesium, calcium, cobalt, iron, nickel, copper, aluminum, gallium, indium, scandium, yttrium, lanthanum, cerium, zinc, etc. may be added to the coating solution.
  • With respect to boron, it is possible to add boric acid or alkoxide of boron that has been chelated with beta-diketone such as acetylacetone.
  • With respect to titanium and zirconium, oxychloride, oxynitrate, or alkoxide that has been chelated with beta-diketone can be added.
  • With respect to aluminum, it is possible to add alkoxide that has been chelated with beta-diketone.
  • INDUSTRIAL APPLICABILITY
  • The article with the silica-based film according to the present invention is useful as an underlayer film, a protection film, a low reflection film, an ultraviolet ray shielding film, an infrared ray shielding film, a colored film and the like.

Claims (12)

1. An article with a silica-based film, the article comprising a substrate and a silica-based film that is formed on a surface of the substrate by a sol-gel process,
wherein the thickness of the silica-based film is more than 300 nm, and
the silica-based film does not separate from the substrate after the Taber abrasion test prescribed in Japanese Industrial Standards R 3212 that is carried out with respect to a surface of the silica-based film.
2. The article according to claim 1, wherein the thickness of the silica-based film is not less than 350 nm and less than 1 μm.
3. The article according to claim 2, wherein the thickness of the silica-based film is not less than 400 nm and less than 1 μm.
4. The article according to claim 1, wherein the substrate is a glass plate or a resin plate.
5. The article according to claim 1, wherein the substrate is a glass plate containing an alkali component and the silica-based film is substantially free from an alkali component.
6. A process for producing an article with a silica-based film by a sol-gel process, the article including a substrate and a silica-based film that is formed on a surface of the substrate,
the process comprising:
applying a film-forming solution for forming the silica-based film to the surface of the substrate, and
heating the substrate to which the film-forming solution has been applied,
wherein the film-forming solution contains silicon alkoxide, strong acid, water, and alcohol;
the silicon alkoxide has a concentration of more than 3 mass % and less than 9 mass % in terms of a SiO2 concentration when silicon atoms contained in the silicon alkoxide are expressed as SiO2;
the number of moles of the water is at least four times and at most ten times the total number of moles of the silicon atoms contained in the silicon alkoxide;
the strong acid has a concentration in the range of 0.001 to 0.2 mol/kg in terms of the molality of protons that is obtained assuming that the protons have dissociated completely from the strong acid; and
the substrate is heated at a temperature above 100° C.
7. The process for producing an article according to claim 6, wherein the film-forming solution is applied so that the thickness of the silica-based film exceeds more than 300 nm.
8. The process for producing an article according to claim 7, wherein the film-forming solution is applied so that the thickness of the silica-based film is not less than 350 nm and less than 1 μm.
9. The process for producing an article according to claim 6, wherein the substrate is heated at a temperature above 150° C.
10. The process for producing an article according to claim 9, wherein the substrate is heated at a temperature above 150° C. and not more than 400° C.
11. The process for producing an article according to claim 6, wherein the silicon alkoxide contains at least one selected from tetraalkoxysilane and a material made by polymerization of tetraalkoxysilane.
12. The process for producing an article according to claim 6, wherein the substrate is a glass plate or a resin plate.
US10/594,606 2004-03-31 2005-03-31 Article With Silica-Based Film and Process for Producing the Same Abandoned US20070212534A1 (en)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
JP2004-104503 2004-03-31
JP2004104503 2004-03-31
JP2004-271618 2004-09-17
JP2004-271624 2004-09-17
JP2004271618 2004-09-17
JP2004271624 2004-09-17
PCT/JP2005/006338 WO2005095102A1 (en) 2004-03-31 2005-03-31 Article with silica coating formed and process for producing the same

Publications (1)

Publication Number Publication Date
US20070212534A1 true US20070212534A1 (en) 2007-09-13

Family

ID=35063609

Family Applications (2)

Application Number Title Priority Date Filing Date
US10/594,606 Abandoned US20070212534A1 (en) 2004-03-31 2005-03-31 Article With Silica-Based Film and Process for Producing the Same
US10/594,936 Expired - Fee Related US7749606B2 (en) 2004-03-31 2005-03-31 Article with organic-inorganic composite film and process for producing the same

Family Applications After (1)

Application Number Title Priority Date Filing Date
US10/594,936 Expired - Fee Related US7749606B2 (en) 2004-03-31 2005-03-31 Article with organic-inorganic composite film and process for producing the same

Country Status (6)

Country Link
US (2) US20070212534A1 (en)
EP (2) EP1731301A4 (en)
JP (2) JPWO2005095102A1 (en)
KR (2) KR20070007834A (en)
DE (1) DE602005024940D1 (en)
WO (2) WO2005095101A1 (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090246512A1 (en) * 2005-10-05 2009-10-01 Nippon Sheet Glass Company, Limited Article With Organic-Inorganic Composite Film
US20100143600A1 (en) * 2007-05-08 2010-06-10 Central Glass Company, Limited Coating Fluid Applicable by Hand for Sol-Gel Film Formation

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4989219B2 (en) * 2004-03-31 2012-08-01 日本板硝子株式会社 Infrared cut glass and manufacturing method thereof
JP5038893B2 (en) * 2005-06-21 2012-10-03 日本板硝子株式会社 Transparent article and method for producing the same
JP2007320780A (en) * 2006-05-30 2007-12-13 Nippon Sheet Glass Co Ltd Transparent article with infrared-cutting film formed thereon
DE102006046308A1 (en) * 2006-09-29 2008-04-03 Siemens Ag Transparent coating used for optical instruments, spectacles, headlamp housings, windscreens and cockpit glazing is based on silicon dioxide and has a specified porosity
JP5249047B2 (en) * 2006-12-20 2013-07-31 日本板硝子株式会社 Articles with organic-inorganic composite film formed
JP5221066B2 (en) * 2007-06-26 2013-06-26 リコー光学株式会社 Film laminated substrate, counter substrate for liquid crystal panel and liquid crystal panel
WO2009103024A2 (en) * 2008-02-14 2009-08-20 Dave Bakul C Methods and compositions for improving the surface properties of fabrics, garments, textiles and other substrates
CN103347833B (en) 2011-02-07 2018-01-02 日本板硝子株式会社 Glass article and ultraviolet screener film formation particulate dispersive composition with ultraviolet screening ability
US9176259B2 (en) 2011-03-04 2015-11-03 Intermolecular, Inc. Sol-gel based antireflective (AR) coatings with controllable pore size using organic nanocrystals and dendrimers
US9441119B2 (en) * 2011-03-28 2016-09-13 Intermolecular, Inc. Sol-gel transition control of coatings by addition of solidifiers for conformal coatings on textured glass
CN111684030B (en) * 2018-02-23 2022-11-01 旭化成株式会社 High-durability antifogging coating film and coating composition
CN115386254B (en) * 2022-07-12 2023-05-26 山西银光华盛镁业股份有限公司 Hydrophobic transparent protective liquid for protecting magnesium alloy material process, and preparation method and use method thereof

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4277525A (en) * 1978-09-01 1981-07-07 Tokyo Ohka Kogyo Kabushiki Kaisha Liquid compositions for forming silica coating films
US4865649A (en) * 1986-11-18 1989-09-12 Tokyo Ohka Kogyo Co., Ltd. Coating solution for forming a silica-based coating film
US5424130A (en) * 1991-05-13 1995-06-13 Toyota Jidosha Kabushiki Kaisha Water repellent glass and process for producing the same
US5518810A (en) * 1993-06-30 1996-05-21 Mitsubishi Materials Corporation Infrared ray cutoff material and infrared cutoff powder use for same
US6465108B1 (en) * 1997-12-04 2002-10-15 Nippon Sheet Glass Co., Ltd. Process for the production of articles covered with silica-base coats
US20030027967A1 (en) * 2000-12-22 2003-02-06 Masahiro Hori Article having predetermined surface shape and method for preparing the same
US6589457B1 (en) * 2000-07-31 2003-07-08 The Regents Of The University Of California Polymer-assisted aqueous deposition of metal oxide films
US20030129421A1 (en) * 2001-10-09 2003-07-10 Mitsubishi Chemical Corporation Active energy ray-curable antistatic coating composition
US20030146415A1 (en) * 2001-02-28 2003-08-07 Tsutomu Minami Article having a predetermined surface shape and method for preparation thereof
US6855396B1 (en) * 1999-10-28 2005-02-15 Institut Fuer Neue Materialien Gemeinnuetzige Gmbh Substrate comprising an abrasion-resistant diffusion barrier layer system

Family Cites Families (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3725079A (en) * 1967-05-26 1973-04-03 Gaf Corp Coating formulations containing phosphate esters of glycidol polyethers
JPS5639672B2 (en) 1974-03-29 1981-09-14
JPH0832854B2 (en) 1987-01-06 1996-03-29 日本合成ゴム株式会社 Coating composition
JPS63268722A (en) 1987-04-28 1988-11-07 Dainippon Ink & Chem Inc Unsaturated polyester resin composition
DE3828098A1 (en) 1988-08-18 1990-03-08 Fraunhofer Ges Forschung METHOD AND COMPOSITION FOR THE PRODUCTION OF SCRATCH-RESISTANT MATERIALS
JP2680434B2 (en) 1989-07-25 1997-11-19 武夫 三枝 Method for producing oxazoline polymer / silica composite molded article
JP2574049B2 (en) 1990-01-17 1997-01-22 武夫 三枝 Organic / inorganic composite transparent homogeneous material and its manufacturing method
JP2555797B2 (en) * 1991-05-13 1996-11-20 トヨタ自動車株式会社 Water repellent glass and method for manufacturing the same
JPH0652796A (en) 1991-09-30 1994-02-25 Colcoat Eng Kk Method for forming silica coat film by low temperature baking
JPH0585714A (en) 1991-09-30 1993-04-06 Korukooto Eng Kk Production of alcohol-base silica sol which silica coating film can be formed by low temperature baking
JPH0827422A (en) 1994-07-15 1996-01-30 Mitsubishi Chem Corp Composition for forming silica-based film
JPH08295844A (en) 1995-04-25 1996-11-12 Sekisui Chem Co Ltd Coating composition and production of laminate
JP3427755B2 (en) 1997-12-04 2003-07-22 日本板硝子株式会社 Method for producing silica-based membrane coated article
DE19811790A1 (en) * 1998-03-18 1999-09-23 Bayer Ag Transparent paint binders containing nanoparticles with improved scratch resistance, a process for their preparation and their use
DE19816136A1 (en) * 1998-04-09 1999-10-14 Inst Neue Mat Gemein Gmbh Nanostructured moldings and layers and their production via stable water-soluble precursors
JP3723891B2 (en) * 1999-09-17 2005-12-07 グンゼ株式会社 Surface hard transparent sheet and manufacturing method thereof
JP4745490B2 (en) 2000-09-13 2011-08-10 宇部日東化成株式会社 Silica-based coating agent, method for producing silica thin film, and silica thin film
JP4565438B2 (en) 2000-12-01 2010-10-20 グンゼ株式会社 Surface hard transparent sheet and manufacturing method thereof
JP2002338304A (en) 2001-02-28 2002-11-27 Nippon Sheet Glass Co Ltd Producing method of article having prescribed surface shape
JP2002348542A (en) 2001-03-21 2002-12-04 Nippon Sheet Glass Co Ltd Coated article, coating liquid composition, and method for producing the coated article
US7160626B2 (en) 2001-03-21 2007-01-09 Nippon Sheet Glass Company, Ltd. Coated article, coating liquid composition, and method for producing coated article
JP3951264B2 (en) * 2002-03-27 2007-08-01 グンゼ株式会社 Transparent moisture-resistant gas barrier film
JP4470736B2 (en) 2002-07-29 2010-06-02 旭硝子株式会社 Infrared shielding glass

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4277525A (en) * 1978-09-01 1981-07-07 Tokyo Ohka Kogyo Kabushiki Kaisha Liquid compositions for forming silica coating films
US4865649A (en) * 1986-11-18 1989-09-12 Tokyo Ohka Kogyo Co., Ltd. Coating solution for forming a silica-based coating film
US5424130A (en) * 1991-05-13 1995-06-13 Toyota Jidosha Kabushiki Kaisha Water repellent glass and process for producing the same
US5518810A (en) * 1993-06-30 1996-05-21 Mitsubishi Materials Corporation Infrared ray cutoff material and infrared cutoff powder use for same
US6465108B1 (en) * 1997-12-04 2002-10-15 Nippon Sheet Glass Co., Ltd. Process for the production of articles covered with silica-base coats
US6855396B1 (en) * 1999-10-28 2005-02-15 Institut Fuer Neue Materialien Gemeinnuetzige Gmbh Substrate comprising an abrasion-resistant diffusion barrier layer system
US6589457B1 (en) * 2000-07-31 2003-07-08 The Regents Of The University Of California Polymer-assisted aqueous deposition of metal oxide films
US20030027967A1 (en) * 2000-12-22 2003-02-06 Masahiro Hori Article having predetermined surface shape and method for preparing the same
US20030146415A1 (en) * 2001-02-28 2003-08-07 Tsutomu Minami Article having a predetermined surface shape and method for preparation thereof
US20030129421A1 (en) * 2001-10-09 2003-07-10 Mitsubishi Chemical Corporation Active energy ray-curable antistatic coating composition

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090246512A1 (en) * 2005-10-05 2009-10-01 Nippon Sheet Glass Company, Limited Article With Organic-Inorganic Composite Film
US8039111B2 (en) 2005-10-05 2011-10-18 Nippon Sheet Glass Company, Limited Article with organic-inorganic composite film
US20100143600A1 (en) * 2007-05-08 2010-06-10 Central Glass Company, Limited Coating Fluid Applicable by Hand for Sol-Gel Film Formation
US8299169B2 (en) 2007-05-08 2012-10-30 Central Glass Company, Limited Coating fluid applicable by hand for sol-gel film formation

Also Published As

Publication number Publication date
US20070212571A1 (en) 2007-09-13
JP4451440B2 (en) 2010-04-14
EP1731300B1 (en) 2010-11-24
WO2005095102A1 (en) 2005-10-13
EP1731300A1 (en) 2006-12-13
EP1731300A4 (en) 2008-09-03
KR20060134173A (en) 2006-12-27
DE602005024940D1 (en) 2011-01-05
EP1731301A4 (en) 2008-08-20
WO2005095101A1 (en) 2005-10-13
JPWO2005095102A1 (en) 2008-02-21
JPWO2005095101A1 (en) 2008-02-21
US7749606B2 (en) 2010-07-06
KR20070007834A (en) 2007-01-16
EP1731301A1 (en) 2006-12-13

Similar Documents

Publication Publication Date Title
US20070212534A1 (en) Article With Silica-Based Film and Process for Producing the Same
US6635735B1 (en) Coating composition
US5413865A (en) Water-repellent metal oxide film and method of forming same on glass substrate
US6210750B1 (en) Water-repellent glass and process for preparing same
JPWO2007040257A1 (en) Article formed with organic-inorganic composite film and method for producing the same
EP3004011A1 (en) Anti-corrosion anti-reflection glass and related methods
WO2002074447A2 (en) Coated article, coating liquid composition, and method for producing coated article
JP2007125537A (en) Method for manufacturing article having organic-inorganic composite film
JP5249047B2 (en) Articles with organic-inorganic composite film formed
US20070289493A1 (en) Transparent article with infrared shielding film
JP2006111851A (en) Solution for forming silica-based film
TW202200520A (en) Improvement of glass strength and fracture toughness by a non-brittle abrasion resistant coating
US8039111B2 (en) Article with organic-inorganic composite film
JP2007099571A (en) Transparent article formed with infrared ray cutting film and its producing method
JP2002348542A (en) Coated article, coating liquid composition, and method for producing the coated article
JP3598529B2 (en) Method for producing water-repellent article
JP2006111850A (en) Solution for forming silica-based film
JP2000017227A (en) Coating composition
CN1938152A (en) Article with silica-based film and process for producing the same
JPWO2007040256A1 (en) Resin article and manufacturing method thereof
JP2002188054A (en) Coating liquid for forming colored film
TW202328020A (en) Improvement of glass strength and fracture toughness by a non-brittle coating

Legal Events

Date Code Title Description
AS Assignment

Owner name: NIPPON SHEET GLASS COMPANY, LIMITED, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SASAKI, TERUYUKI;INOGUCHI, KAZUYUKI;KAMITANI, KAZUTAKA;REEL/FRAME:018395/0109

Effective date: 20060901

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION