JP2015074588A - Method for producing hydrophilized glass substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a hydrophilized glass substrate capable of exhibiting high antifogging properties or an effect of suppressing deterioration in visibility due to water droplets over a long period of time by maintaining a hydrophilic property of a surface for a long time.SOLUTION: There is provided a method for producing a hydrophilized glass substrate which comprises: a pre-treatment step S1 of bringing a surface of a glass substrate into contact with flame or plasma; and a hydrophilization step S3 of applying a hydrophilized process liquid containing a titanium compound or a silicon compound onto a surface of the glass substrate, followed by heat-treating the surface of the glass substrate.

Description

  The present invention relates to a method for producing a hydrophilic glass substrate.

  Glass products such as mirrors placed in humid places such as washrooms and bathrooms often become cloudy, especially in cold weather. This phenomenon occurs when the surface temperature of the glass substrate constituting the glass product falls below the dew point, so that moisture in the air becomes fine water droplets and adheres to the surface of the glass substrate, where light is diffusely reflected. . Moreover, it is often experienced that water drops adhere to the surface of a windshield or a rearview mirror (door mirror) of an automobile when it rains and the like, resulting in a significant decrease in visibility. This is also a phenomenon caused by water droplets adhering to the surface of the glass substrate, similar to the above fogging.

  One means for reducing such a phenomenon is adjusting the wettability of the glass substrate surface. By adjusting the wettability of the glass substrate surface to be high, the contact angle between the glass substrate and the water droplet is reduced, and the water droplet cannot maintain its form. As a result, the water droplets become a thin water film on the glass substrate, so that cloudiness and a decrease in visibility due to adhesion of the water droplets are suppressed. Antifogging sprays containing a surfactant as a component aiming at such an effect are also commercially available, but since the sustainability of the effect by the surfactant is generally short, it is used to prevent fogging of the glass substrate. If it is going to suppress the fall of visibility accompanying adhesion of a water droplet, spray processing must be frequently performed to a glass substrate, and it is inconvenient.

  In order to solve such a problem, for example, Patent Document 1 discloses that a film having hydrophilicity and water absorption, insoluble in water and having surface friction resistance is formed on the surface of a glass substrate to cause fogging of a lens or the like. It has been proposed to suppress. In recent years, titanium oxide particles that are photocatalysts are attached to the surface of a glass substrate, and the surface of the glass substrate is made superhydrophilic by the photocatalytic action of titanium oxide (for example, (See Patent Document 2).

Japanese Patent Laid-Open No. 2005-234066 Japanese Patent No. 2756474

  According to the method of superhydrophilicizing the surface of the glass substrate by the photocatalytic action of titanium oxide, the effect of suppressing fogging and water droplets is considerably high. Further, as treatment methods for obtaining such an effect, most of the treatment methods can be completed by applying a treatment agent containing titanium oxide particles to the surface of the glass substrate, which is very simple. However, in general, the period in which the effect lasts is not so long and depends on the type of treatment agent used. For example, when the antifogging treatment is performed on the mirror by the above method, the antifogging effect is about several weeks. Will be lost.

  The present invention has been made in view of the above situation, and by maintaining the hydrophilicity of the surface for a long period of time, it is possible to exhibit a high anti-fogging property and an effect of suppressing the deterioration of visibility due to water droplets over a long period of time. It aims at providing the manufacturing method of a hydrophilic glass substrate.

  As a result of intensive studies in order to solve the above problems, the present inventor made a hydrophilic treatment liquid containing a titanium compound such as titanium oxide or an alkoxide of titanium, or a silicon compound such as silica or a silica precursor into glass. In order to complete the present invention, it is found that by providing a pretreatment step in which a flame or plasma is brought into contact with the surface of the glass substrate before application to the substrate, a glass substrate that maintains hydrophilicity over a long period of time can be obtained. It came.

  In the present invention, a pretreatment step of bringing a flame or plasma into contact with the surface of a glass substrate, and a hydrophilic treatment liquid containing a titanium compound or a silicon compound is applied to the surface of the glass substrate that has undergone the pretreatment step, and then the glass And a hydrophilic treatment step of heat-treating the surface of the substrate.

  It is preferable that the pretreatment step is to bring a flame into contact with the surface of the glass substrate.

  It is preferable that the heat treatment in the hydrophilic treatment step is to bring a flame into contact with the surface of the glass substrate.

  In the hydrophilic treatment step, it is preferable to apply the hydrophilic treatment liquid after preheating so that the glass substrate has a temperature of 100 ° C. or higher.

  A primer treatment step of applying a primer treatment liquid containing a silane coupling agent to the surface of the glass substrate and then heat treating the surface of the glass substrate between the pretreatment step and the hydrophilization treatment step; But you can.

  ADVANTAGE OF THE INVENTION According to this invention, the hydrophilic property of the surface is maintained for a long period of time, and the manufacturing method of the hydrophilization glass substrate which can show the high anti-fogging property over a long period of time and the visibility fall suppression effect by a water droplet is provided The

FIG. 1 is a flow diagram showing one embodiment of a method for producing a hydrophilic glass substrate of the present invention. FIG. 2 is a cross-sectional view schematically showing a mirror manufactured in one embodiment of the method for manufacturing a hydrophilic glass substrate of the present invention.

  Hereinafter, one embodiment of the present invention will be described, but the present invention is not limited to the following embodiment, and can be implemented with appropriate modifications without departing from the spirit of the present invention. FIG. 1 is a flow diagram showing an embodiment of a method for producing a hydrophilic glass substrate of the present invention. FIG. 2 is a cross-sectional view schematically showing a mirror manufactured in one embodiment of the method for manufacturing a hydrophilic glass substrate of the present invention.

  The hydrophilized glass substrate produced by the method for producing a hydrophilized glass substrate of the present invention has a reduced water contact angle due to the surface being hydrophilized, and water attached to the surface does not become water droplets. Features water film. For this reason, this hydrophilic glass substrate has anti-fogging property that suppresses “fogging” caused by the attachment of fine water droplets, and suppresses a decrease in visibility due to adhesion of large water droplets to the surface. It has the performance to do. The glass substrate to be hydrophilized only needs to have the glass surface exposed on one surface, and the glass surface does not necessarily have to be exposed on the other surface, such as a mirror. Examples of such glass substrates include windshields and rearview mirrors for automobiles, lenses such as glasses, mirrors installed in bathrooms and washstands, window glass for buildings, and the like.

  In this embodiment, as an example of the present invention, a method for producing a hydrophilic glass substrate when the mirror 1 shown in FIG. 2 is selected as the glass substrate will be described. In this case, the glass substrate to be hydrophilized is the mirror 1 composed of the glass layer 2, the silver plating layer 3 and the paint film 4, and the glass surface of the glass layer 2 is exposed on the surface exposed to the hydrophilic treatment. The primer layer 5 and the hydrophilic layer 6 are formed to form a hydrophilic mirror (that is, a hydrophilic glass substrate) 1A. The silver plating layer 3 is a silver layer formed on one surface of the glass layer 2 (this is called the back surface, and the side where the glass on the opposite side is exposed is called the surface) in contact with the glass layer 2. The deposited film or the plated film. On the surface of the silver plating layer 3, a paint film 4 as a protective film is formed in contact with the silver plating layer 3. The paint film 4 is made of an organic material such as urethane resin. In the future, the mirror 1 will also be referred to as “glass substrate 1”, and the hydrophilized mirror 1A will also be referred to as “hydrophilic glass substrate 1A”.

  The manufacturing method of the hydrophilized glass substrate 1A of this embodiment includes a pretreatment step S1, a primer treatment step S2, a hydrophilization treatment step S3, and a cooling step S4. Hereinafter, each step will be described.

[Pretreatment step S1]
The pretreatment step S1 is a step of bringing a flame or plasma into contact with the surface of the glass substrate 1. In this embodiment, a mirror composed of the glass layer 2, the silver plating layer 3 and the paint film 4 is used as the glass substrate 1, and a flame is brought into contact with the surface thereof. In the pretreatment step S1, various impurities such as moisture and organic substances adhering to the surface of the glass substrate 1 are removed by a flame or plasma. By removing such impurities from the glass substrate 1, the primer layer 5 and the hydrophilic layer 6 to be formed can be firmly bonded to the surface of the glass substrate 1.

  In general, when various impurities are removed from the surface of the glass substrate with high accuracy, a method of polishing the surface of the glass substrate using cerium oxide particles is employed. By performing such treatment, polishing is performed while cerium oxide reacts with glass, and it is said that precise polishing that cannot be realized by simple mechanical polishing can be performed. However, since such a polishing process is performed in a wet manner, a large amount of moisture is adsorbed on the surface of the glass substrate after polishing, and this moisture causes the primer layer and the hydrophilic layer to adhere to the glass substrate. It can be an obstacle. However, when the process of contacting the flame or plasma used in the present invention is performed, impurities can be removed from the surface of the glass substrate 1 without causing such a problem.

  Preferred examples of the flame used for such treatment include those produced by burning flammable gases such as propane, butane, and natural gas. Among these, a mixed gas of propane and butane can be preferably exemplified, but is not particularly limited. The flame preferably has a purple color (flame temperature of about 700 to 800 ° C.) due to complete combustion of the gas. The flame thus obtained is brought into direct contact with the surface of the glass substrate 1. At this time, it is preferable to perform the flame contact until the surface temperature of the glass substrate 1 observed with the surface thermometer reaches about 90 to 300 ° C., and more preferably to perform the flame contact until about 90 to 150 ° C. preferable. By heating the surface temperature of the glass substrate 1 within this temperature range, impurities attached to the surface of the glass substrate 1 are effectively removed, while the coating film 4 on the glass substrate 1 that is a mirror is decomposed by heat. It is preferable because it can be suppressed.

  In addition, even if it does not depend on the process which makes a flame contact, it is also possible to raise the surface temperature of the glass substrate 1 to said range, for example by means, such as IR (infrared rays) irradiation. However, in this case, since the heating time tends to be long, the entire glass substrate 1 is heated, and there is a risk that the coating film 4 is decomposed by heat. Above all, according to the study of the present inventors, simply increasing the temperature of the glass substrate 1 by IR irradiation results in poor adhesion between the primer layer 5 and the hydrophilic layer 6, and the hydrophilic layer 6 is sufficiently bonded. Durability cannot be obtained. In this regard, in the case of flame treatment, by impregnating the surface of the glass substrate 1 with a high-temperature flame, impurities existing on the surface of the glass substrate 1 are instantaneously decomposed or evaporated by contact with the flame, while existing on the back surface. It can suppress that the glass substrate 1 becomes high temperature until the coating film 4 decomposes | disassembles, Furthermore, sufficient adhesiveness of the hydrophilic layer 6 can be obtained as mentioned above.

  The plasma used in the plasma treatment may be either low-temperature plasma or thermal plasma, and one generated by a conventionally known plasma generator can be used. The plasma contains many highly reactive charged particles, and these charged particles come into contact with impurities existing on the surface of the glass substrate 1, so that the impurities are decomposed and removed from the surface of the glass substrate 1. In addition, although the surface temperature of the glass substrate 1 may rise depending on the kind of plasma to be used, the upper limit of the surface temperature of the glass substrate 1 is preferably about 90 to 300 ° C., and about 90 to 150 ° C. More preferably.

  The glass substrate 1 that has been subjected to the process of bringing the flame or plasma into contact is cooled to about room temperature by air cooling, and then subjected to the primer processing step S2.

[Primer treatment step S2]
The primer treatment step S2 is a step performed between the pretreatment step S1 and a hydrophilization treatment step S3 described later, and a primer treatment liquid containing a silane coupling agent is applied to the surface of the glass substrate 1, and then In this step, the surface of the glass substrate 1 is subjected to heat or plasma treatment. Through this step, the primer layer 5 is formed on the surface of the glass substrate 1. The primer layer 5 is formed in order to improve the adhesion of the hydrophilic layer 6 formed in the hydrophilic treatment step S3 described later to the glass substrate 1. In addition, since the adhesiveness with respect to the glass substrate 1 of the hydrophilic layer 6 can be significantly improved by passing through the said pretreatment process S1, depending on selection of the hydrophilic treatment liquid used by the hydrophilic treatment process S3 mentioned later. Even if the primer layer 5 is not provided, sufficient adhesion of the hydrophilic layer 6 can be obtained. In this case, the primer processing step S2 may be omitted.

  The silane coupling agent is polymerized by hydrolysis and polycondensation reaction to form a siloxane bond, thereby forming the primer layer 5 serving as a base for the hydrophilic layer 6. Various types of such silane coupling agents are commercially available. For example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, Ethyltripropoxysilane, ethyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane, phenyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldipropoxysilane, dimethyldibutoxysilane, diethyl Dimethoxysilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyldibutoxysilane, phenylmethyldimethoxysilane, phenylmethyldiethoxy Lan, phenylmethyldipropoxysilane, phenylmethyldibutoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltripropoxysilane, n-propyltributoxysilane, γ-glycidoxypropyltrimethoxy Silane, γ-methacryloxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, octadecyltriethoxysilane, vinyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxy Silane, (gamma) -mercaptopropyl trimethoxysilane, (beta)-(3,4 epoxy cyclohexyl) ethyltrimethoxysilane etc. are mentioned. Of these, aminosilane-based silane coupling agents are preferably used. These silane coupling agents can be used alone or in combination of two or more.

  A solution obtained by diluting the silane coupling agent with a solvent is a primer treatment solution. The solvent that can be used for the preparation of the primer treatment solution is not particularly limited as long as it can be mixed with the silane coupling agent. Examples thereof include toluene, xylene, ethyl acetate, acetone, methyl ethyl ketone, and 2-methoxymethyl acetate. (Also called methyl cellosolve acetate), 2-ethoxyethyl acetate (also called cellosolve acetate), ethylene glycol mono-tert-butyl ether acetate, and the like. These solvents can be used alone or in combination of two or more.

  As a density | concentration of the silane coupling agent in a primer processing liquid, about 0.1-5 mass% is preferable, about 0.1-3 mass% is more preferable, About 0.2-1 mass% is further more preferable. The concentration of the silane coupling agent shown in these is considerably dilute as compared with a normal primer application. The reason why the concentration is so thin is that when the pretreatment step S1 is performed, the adhesiveness of the hydrophilic layer 6 described later is improved by reducing the thickness of the formed primer layer 5 as much as possible. This is because the person has found out.

  The silane coupling agent contained in the primer treatment liquid is hydrolyzed by reacting with moisture in the air when applied to the surface of the glass substrate 1 or reacting with moisture contained in the solvent. It is considered that the polymer is condensed and cured by heat treatment described later. Further, hydrolysis may be promoted in advance by adding a small amount of water to the primer treatment solution.

  In applying the primer treatment liquid to the surface of the glass substrate 1, a known application method can be used without any particular limitation. Examples of such a coating method include a spray method, a roll coater method, a flow coater method, a brush coating method, a dipping method, a gravure coating method, a spin coating method, and the like. From the viewpoint of improving the adhesion of the layer 6, a spray method is preferably used. What is necessary is just to adjust suitably about the application quantity of a primer process liquid so that the thickness of the primer layer 5 formed may be set to about 10 nm-1000 nm.

  After applying the primer treatment liquid to the surface of the glass substrate 1, heat treatment is performed on the surface. By this heat treatment, the solvent contained in the primer treatment liquid is removed from the surface of the glass substrate 1 and the condensation polymerization reaction of the silane coupling agent present on the surface of the glass substrate 1 is promoted.

  Examples of the heat treatment include a hot air treatment method, an IR (infrared) heating method, and a method of contacting with a flame. Among these, since the adhesiveness of the hydrophilic layer 6 can be improved more by using the method of making it contact with a flame, it is preferable. When using the method of making it contact with a flame, it can carry out in the procedure similar to the flame treatment in pre-processing process S1 already described as heating conditions. In addition, as temperature of heat processing, about 90-150 degreeC can be illustrated as surface temperature of the glass substrate 1. FIG.

  The glass substrate 1 on which the primer layer 5 is formed through the primer treatment step S2 is subjected to a hydrophilic treatment step S3.

[Hydrophilic treatment step S3]
The hydrophilic treatment step S3 is a step of applying a hydrophilic treatment liquid containing a titanium compound or a silicon compound to the surface of the glass substrate 1 on which the primer layer 5 is formed, and then heat-treating the surface of the glass substrate 1. By passing through this process, the hydrophilic layer 6 containing the titanium oxide which is a photocatalyst or the silica which is hydrophilic is formed, and what was the glass substrate 1 turns into the glass substrate 1A hydrophilized. As already described, when the primer treatment step S2 is omitted, the hydrophilic layer 6 is formed immediately above the glass substrate 1. Therefore, when primer treatment process S2 is abbreviate | omitted, "primer layer 5" shall be read as "glass substrate 1" in the following description.

  As already known, when a layer containing titanium oxide having a photocatalytic action is irradiated with ultraviolet light, the contact angle between the layer and water is 10 ° or less, more specifically 5 ° or less, particularly about 0 °. It becomes highly hydrophilic. In the present invention, the performance of exhibiting antifogging properties or suppressing the visibility from being lowered due to the presence of large surface water droplets is brought about by such an action. In addition, such an effect | action is fully exhibited even by the weak ultraviolet light irradiation contained in a fluorescent lamp. In addition, such photocatalytic action not only improves antifogging and visibility, but also exhibits antifouling properties. For example, if the present invention is applied to a bathroom mirror, it can be used for insolubilized soap scum and tap water. It is also suppressed that the contained components adhere to the surface of the mirror in a scale shape.

  The titanium compound may be a titanium oxide particle that exhibits a photocatalytic action, or may be a titanium oxide precursor that is converted into titanium oxide by heat treatment.

  When titanium oxide particles are used as the titanium compound, examples of the titanium oxide include anatase type titanium oxide, rutile type titanium oxide, and brookite type titanium oxide. In this case, the titanium oxide particles are in a state of being dispersed or suspended in the hydrophilization treatment liquid, and the particle diameter thereof may be about 5 nm to 1000 nm, but is not particularly limited. Since the treatment liquid in which such titanium oxide particles are dispersed or suspended is commercially available from various companies including Toko Co., Ltd., it can be easily obtained.

When a titanium oxide precursor is used as the titanium compound, the titanium oxide precursor may be a titanium alkoxide such as tetraethoxy titanium, tetraisopropoxy titanium, tetra-n-propoxy titanium, tetrabutoxy titanium, tetramethoxy titanium, or the like. Examples thereof include compounds obtained by partially or completely hydrolyzing organic titanium compounds, and inorganic titanium compounds such as titanium tetrachloride and Ti (SO ₄ ) ₂ . These compounds are used in the state of being dissolved, dispersed or suspended in the hydrophilization solution.

  When using a compound obtained by partially or completely hydrolyzing an organotitanium compound, these compounds are completely hydrolyzed and subjected to polycondensation by being subjected to the heat treatment described later after being applied to the surface of the primer layer 5. Reaction occurs to form amorphous titanium oxide. In the case of using an inorganic titanium compound, these compounds are hydrolyzed and subjected to a polycondensation reaction by being applied to the surface of the primer layer 5 and then subjected to a heat treatment described later to become amorphous titanium oxide.

  Since the silica itself has hydrophilicity, the hydrophilic layer 6 can express not only the antifogging property and visibility but also the antifouling property in the same manner as when the titanium oxide is contained. . The silicon compound serving as the silica supply source may be silica particles, or may be a silica precursor that is converted into silica by heat treatment.

  When silica particles are used as the silicon compound, the silica particles are dispersed or suspended in the hydrophilization treatment liquid, and the particle diameter can be about 5 nm to 1000 nm, but is not particularly limited. Since the treatment liquid in which such silica particles are dispersed or suspended is commercially available from various companies including KRI Co., Ltd., it can be easily obtained.

  When a silica precursor is used as the silicon compound, examples of the silica precursor include the silane coupling agent described above, or a compound obtained by partially or completely hydrolyzing the silane coupling agent. These compounds are used in a state of being dissolved, dispersed or suspended in the hydrophilization solution. When such a silane coupling agent itself or a compound obtained by partially or completely hydrolyzing the silane coupling agent is used, the compound is completely hydrolyzed by applying a heat treatment described later after being applied to the surface of the primer layer 5. While being decomposed, it undergoes a condensation polymerization reaction and is finally converted to silica.

  The hydrophilization treatment liquid is obtained by mixing the titanium compound or silicon compound with a solvent. Solvents include toluene, xylene, ethyl acetate, acetone, methyl ethyl ketone, butyl cellosolve, cyclohexanone, ethylene glycol mono tert-butyl ether, ethylene glycol mono ethyl ether, ethylene glycol mono n-butyl ether, 2-methoxymethyl acetate, 2-ethoxyethyl acetate And various organic solvents such as ethylene glycol mono tert-butyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono n-butyl ether acetate, and the like. Among these, ethylene glycol mono tert-butyl ether, ethylene glycol mono tert- Preferred examples include butyl ether acetate and the like. These solvents can be used alone or in combination of two or more.

  The concentration of the titanium compound or silicon compound in the hydrophilization treatment liquid is exemplified by about 0.1 to 50% by mass, and may be appropriately adjusted so that the thickness of the hydrophilic layer 6 falls within a preferable range described later. .

  When applying the hydrophilic treatment liquid to the surface of the primer layer 5, it is preferable to heat (ie preheat) the glass substrate 1 in advance so that the glass substrate 1 becomes 100 ° C. or higher. When such preheating is performed, when the hydrophilization treatment liquid is brought into contact with the primer layer 5, the solvent contained in the hydrophilization treatment liquid quickly evaporates to form a uniform titanium compound or silicon compound layer ( This will later become the hydrophilic layer 6). On the other hand, when the hydrophilization treatment liquid is applied to the surface of the primer layer 5 without performing such preheating, as the solvent gradually volatilizes, portions having a high concentration of the titanium compound or silicon compound are formed in some places, resulting in spots. The hydrophilic layer 6 is formed in a state where an opaque portion is formed. In such a state, it cannot be used for applications such as mirrors that require transparency, and the adhesiveness between the hydrophilic layer 6 and the primer layer 5 is not ensured, resulting in a product with poor durability. It is not preferable.

  The thickness of the formed hydrophilic layer 6 is preferably 10 nm to 10 μm, more preferably 10 nm to 1000 nm, and further preferably 10 nm to 300 nm. In addition, the titanium compound or silicon compound layer formed by applying the hydrophilization treatment liquid is converted into the hydrophilic layer 6 through a heat treatment described later, but the thickness is slightly reduced at that time. It is desirable to determine the coating amount of the hydrophilization treatment liquid in consideration of the minute.

  When applying the hydrophilic treatment liquid to the surface of the primer layer 5, a spray method is preferably used. If the hydrophilic treatment liquid is applied to the preheated glass substrate 1 using the spray method as described above, the solvent volatilizes almost simultaneously with the contact of the hydrophilization treatment liquid in the form of a mist with the primer layer 5. Therefore, the layer of titanium compound or silicon compound can be formed as a uniform thin film, leading to desirable results.

  The titanium compound or silicon compound layer formed on the surface of the primer layer 5 is subjected to heat treatment. Through this heat treatment, the titanium compound or silicon compound layer is converted into the hydrophilic layer 6. This heat treatment is preferably performed by bringing a flame into contact with the surface of the titanium compound or silicon compound layer. Examples of the flame used at this time include the same flames as described in the above-described pretreatment step S1. By performing such a flame treatment, the titanium compound and the silicon compound are baked on the surface of the primer layer 5 to form the hydrophilic layer 6 having adhesion and durability.

  When performing the heat treatment, the surface temperature of the glass substrate 1 is preferably 150 to 250 ° C., more preferably 170 to 200 ° C., and the temperature is preferably maintained for 30 seconds or more. Even if the surface temperature of the glass substrate 1 is in the above range, the temperature of the flame itself used for the treatment is about 700 to 800 ° C., so that the titanium compound or silicon compound in contact with the flame is sufficiently baked. In addition, when amorphous titanium oxide is formed by using a titanium oxide precursor as a titanium compound, crystallization proceeds by the temperature of the flame and is converted to anatase type or rutile type titanium oxide. The Further, when a silica precursor is used as the silicon compound, the silica precursor is converted to silica by the flame temperature. In addition, when heat-treating the glass substrate 1, in addition to the above flame treatment, heating by IR (infrared rays) may be used in combination.

  The hydrophilized glass substrate 1A on which the hydrophilic layer 6 has been formed through the hydrophilization treatment step S3 is subjected to the cooling step S4.

[Cooling step S4]
The cooling step S4 is a step of performing slow cooling so that the hydrophilized glass substrate 1A heated by the heat treatment of the hydrophilization treatment step S3 does not crack due to rapid cooling. In this step, hot air or hot air of 100 ° C. or lower is blown onto the hydrophilic glass substrate 1A while gradually lowering the temperature, and the temperature of the hydrophilic glass substrate 1A is lowered to room temperature. Since such a technique is known in the field of the glass industry, description thereof is omitted here.

  The hydrophilic glass substrate 1A is manufactured through the above steps. The above-described embodiment is an example of the present invention, and the present invention is not limited to the above-described embodiment, and can be implemented with appropriate modifications without departing from the spirit of the present invention.

  For example, although the primer layer 5 is formed in the above embodiment and FIG. 1, the hydrophilic layer 6 may be formed directly on the surface of the glass substrate 1 without forming the primer layer 5. In this case, the primer treatment step S2 is omitted. As described above, the present invention is characterized in that the heat-treating step S1 is performed to form the hydrophilic layer 6 having high adhesion, and if the sufficient adhesion of the hydrophilic layer 6 can be obtained thereby, the primer layer 5 may be omitted. Depending on the type of the hydrophilization solution used, it may even be possible to improve the adhesion of the hydrophilic layer 6 by omitting the primer layer 5.

  Hereinafter, the method for producing a hydrophilic glass substrate of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

[Example 1]
(Pretreatment) A flame obtained by burning a mixed gas of propane and butane with a torch type gas burner on the surface of the glass surface side of a commercially available glass mirror (hereinafter referred to as “the surface of the glass mirror”). A pretreatment for contact was performed. The flame used was obtained by adjusting the air so that the appearance of the flame was completely purple, and when the flame was brought into contact, the surface temperature of the glass mirror observed with a surface thermometer was 90-100. The treatment was performed while moving the flame so that the entire surface of the glass mirror was in contact with the flame almost uniformly so that the temperature would be about ° C.

  (Primer treatment) Thereafter, a primer (trade name: KBP-43) containing an amino-based silane coupling agent manufactured by Shin-Etsu Chemical Co., Ltd. was diluted with 2-methoxymethyl acetate to a concentration of 0.5% by mass. A primer treatment solution was prepared and spray-coated on the surface of the glass mirror subjected to the pretreatment. After spray coating, the entire surface of the glass mirror was brought into contact with a flame and heat-treated in the same procedure as the pretreatment.

  (Hydrophilic treatment) Next, the surface of the glass mirror subjected to the primer treatment is heated to 110 ± 10 ° C., and the titanium oxide particle dispersion manufactured by Toko Co., Ltd. The hydrophilic treatment liquid diluted so as to be about 7 times diluted with tert-butyl ether was spray-coated on the surface of a glass mirror. At this time, the dry film thickness of the coating film was adjusted to 100 to 200 nm. After that, heat treatment was performed by heating with infrared rays while bringing the flame into contact with the front surface in the same procedure as the pretreatment so that the surface temperature of the glass mirror was maintained at 180 ± 10 ° C. for 30 seconds. After the heat treatment, hot air to warm air of 100 ° C. or lower was blown onto the glass mirror while gradually lowering the temperature, and the temperature of the glass mirror was lowered to room temperature to obtain a hydrophilic treatment mirror of Example 1.

[Example 2]
A hydrophilic treatment mirror of Example 2 was obtained in the same procedure as Example 1 except that the primer treatment was omitted.

[Example 3]
A hydrophilization treatment mirror of Example 3 was obtained in the same procedure as in Example 1 except that the heat treatment in the hydrophilization treatment was only infrared heating and the flame contact was not performed.

[Example 4]
The hydrophilization of Example 4 was carried out in the same manner as in Example 1 except that a commercially available silica dispersion was diluted with ethylene glycol mono-tert-butyl ether so as to be diluted about 7 times to obtain a hydrophilization treatment liquid. A processing mirror was obtained.

[Comparative Example 1]
A hydrophilic treatment mirror of Comparative Example 1 was obtained in the same procedure as Example 1 except that the pretreatment was omitted.

[Comparative Example 2]
A hydrophilic treatment mirror of Comparative Example 2 was obtained in the same procedure as Example 1 except that the pretreatment and the primer treatment were omitted.

[Durability evaluation of hydrophilic layer]
Whether or not the formed hydrophilic layer is maintained by immersing the hydrophilized mirrors of Examples 1 to 3 and Comparative Examples 1 and 2 in water and spraying water onto the surface with spraying every week. evaluated. When water is sprayed 10 times in a continuous manner with a spray bottle, water droplets are conspicuously observed, and the hydrophilic layer is not maintained. Evaluation was made according to the following criteria. The results are shown in Table 1.
○: The hydrophilic layer is maintained continuously after 4 weeks. Δ: The hydrophilic layer is maintained from 1 week to less than 4 weeks, but the hydrophilic layer is not maintained after that. ×: The hydrophilic layer is maintained. Was less than a week

  As shown in Table 1, it is understood that when the flame treatment is performed on the surface of the glass substrate prior to the hydrophilic treatment, the durability of the formed hydrophilic layer is improved, and the usefulness of the present invention is shown. ing. In addition, in the hydrophilization treatment, it is understood that the durability of the hydrophilic layer is further improved by performing the flame treatment after applying the hydrophilization treatment liquid.

DESCRIPTION OF SYMBOLS 1 Mirror 1A Hydrophilized mirror 2 Glass layer 3 Silver plating layer 4 Paint film 5 Primer layer 6 Hydrophilic layer

Claims (5)

A pretreatment step of bringing a flame or plasma into contact with the surface of the glass substrate;
Applying a hydrophilic treatment liquid containing a titanium compound or a silicon compound to the surface of the glass substrate that has undergone the pretreatment step, and then heat-treating the surface of the glass substrate; and
The manufacturing method of the hydrophilic glass substrate characterized by including.   The method for producing a hydrophilic glass substrate according to claim 1, wherein the pretreatment step is to bring a flame into contact with the surface of the glass substrate.   The method for producing a hydrophilic glass substrate according to claim 1 or 2, wherein the heat treatment in the hydrophilic treatment step is to bring a flame into contact with the surface of the glass substrate.   The hydrophilized glass substrate according to any one of claims 1 to 3, wherein in the hydrophilization treatment step, the hydrophilization treatment liquid is applied after preheating so that the glass substrate becomes 100 ° C or higher. Manufacturing method.   Between the pretreatment step and the hydrophilization treatment step, a primer treatment step of applying a primer treatment liquid containing a silane coupling agent to the surface of the glass substrate and then heat-treating the surface of the glass substrate is included. The manufacturing method of the hydrophilic glass substrate of any one of Claims 1-4.

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