JP5100077B2 - Method for producing silica film - Google Patents

Description

  The present invention relates to a method for producing a silica film through a step of converting polysilazane into silica.

In the following Patent Document 1, for the purpose of improving the antifouling property of dentures, simply by applying a coating liquid containing polysilazane on the surface of dentures, the polysilazane reacts with moisture in the air and is converted to silica. A method by which silica can be coated is described.
Japanese Patent No. 3674856

  However, the method described in Patent Document 1 has a problem that since the polysilazane is converted to silica by leaving it in the air after applying the coating liquid, the reaction rate is slow and it takes time to form the silica film.

  This invention is made | formed in view of the said situation, and it aims at providing the method of forming the silica film | membrane produced | generated from a polysilazane on a base material in a short time.

In order to solve the above problems, a method for producing a silica film of the present invention comprises forming a polysilazane film containing polysilazane on a substrate , and an aqueous layer containing water and hydrogen peroxide water on the polysilazane film. And forming a polysilazane into silica by irradiation with laser light or microwaves.
In the method for producing a silica film of the present invention, the water layer preferably contains a heat generating agent that generates heat upon irradiation with laser light or microwaves.
The polysilazane layer preferably contains a heat generating agent that generates heat upon irradiation with laser light or microwaves.

According to the present invention, a polysilazane film containing polysilazane is formed on a substrate, and an aqueous layer containing hydrogen peroxide is formed on the polysilazane film, and then irradiated with laser light or microwaves. Since the polysilazane is converted to silica, a silica film produced from the polysilazane can be formed in a short time.

<Base material>
The material of the base material in the present invention is not particularly limited. Examples thereof include metals such as stainless steel and titanium, resins such as polycarbonate and acrylic resin, ceramics such as alumina and zirconia, minerals such as jewels, corals, and fossils, bones, teeth, wood, paper, leather, silicon wafers, and the like.

<Polysilazane>
The polysilazane used in the present invention is a polymer having “— (SiH ₂ —NH) —” (wherein all or part of H may be substituted with a substituent) as a repeating unit, and is a chain Examples include polysilazane and cyclic polysilazane. Examples of the chain polysilazane include perhydropolysilazane, polymethylhydrosilazane, polyN-methylsilazane, polyN- (triethylsilyl) allylsilazane, polyN- (dimethylamino) cyclohexylsilazane, and phenylpolysilazane. Any of these can be used and is not limited thereto. One kind of polysilazane may be used, or a mixture of two or more kinds may be used.
Among these, perhydroxypolysilazane is particularly preferable in that the effect of improving the adhesive strength according to the present invention is good.

<Silica membrane>
In the present invention, polysilazane reacts with water (H ₂ O) and is converted to silica, for example, as represented by the following reaction formula.
(—SiH ₂ NH —) + 2H ₂ O → (—SiO ₂ —) + NH ₃ + 2H ₂
The silica film in the present invention means a film containing silica converted from a polysilazane film, and not all of the polysilazane is necessarily converted to silica.

<First Embodiment>
A first embodiment of the method for producing a silica film of the present invention will be described.
First, a polysilazane film containing polysilazane is formed on a substrate. Specifically, after applying a coating liquid containing polysilazane and a solvent on a substrate, the solvent is removed.

The solvent used in the coating solution may be any solvent that does not react with polysilazane and can form a uniform polysilazane solution. Specific examples include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; aliphatic hydrocarbons such as pentane, hexane, isohexane, methylpentane, heptane, isoheptane, octane, and isooctane; cyclopentane, methylcyclopentane, and cyclohexane. Alicyclic hydrocarbons such as methylcyclohexane; halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride, bromoform, ethylene chloride, ethylidene chloride, trichloroethane; ethyl ether, isopropyl ether, ethyl butyl ether, butyl ether, 1, 2 -Ethers such as dioxyethane, thiochitasan, dimethyldioxane, tetrahydrofuran, tetrahydropyran and the like. These solvents may be one kind or a mixture of two or more kinds.
The concentration of polysilazane in the coating solution is preferably 0.01 to 50% by mass, and more preferably 1 to 20% by mass.
A catalyst may be added to the coating solution. Examples of the catalyst include triethylamine, diethylamine, monoethanolamine, diethanolamine, n-butylamine, di-n-butylamine, tri-n-butylamine and other amines, sodium hydroxide, potassium hydroxide and other metal hydroxides, ammonia Water, bases such as pyridine, acetic acid, acetic anhydride, succinic acid, fumaric acid, maleic acid, maleic anhydride, carboxylic acids such as succinic acid and their anhydrides, organic acids such as trichloroacetic acid, hydrochloric acid, nitric acid, sulfuric acid, etc. Inorganic acids, and Lewis acids such as iron trichloride and aluminum trichloride.
The coating liquid can contain appropriate additives as long as the effects of the present invention are not impaired. For example, ultraviolet absorbers, fillers made of ceramics or resins, fluorine compounds, drug components, photocatalysts, photosensitive components, brighteners and the like can be mentioned.

As a method for applying the coating liquid, a brush coating method, a spray method, a dipping method, a flow coating method, or the like can be used.
Prior to application of the coating liquid, the coated surface may be polished or washed as necessary.
After applying the coating solution, it is preferable to perform a drying step in order to remove the solvent.

Next, laser light or microwave is irradiated toward the polysilazane film formed on the substrate. As a result, polysilazane is converted to silica to form a silica film. In this embodiment, it is considered that the irradiated laser light or microwave is absorbed by the base material and heat is generated, whereby the polysilazane film is heated, and the polysilazane and moisture in the atmosphere react to convert to silica.
The type of laser light is not particularly limited, and for example, a carbon dioxide laser (hereinafter sometimes referred to as a CO ₂ laser), an Er (erbium) -YAG (yttrium, aluminum, garnet) laser, an Nd (neodymium) -YAG laser, or the like. Can be used.
The wavelength of the microwave is not particularly limited, and it is preferable to select a wavelength that efficiently generates heat due to the microwave irradiation according to the material of the irradiation object.
The thickness of the silica film formed on the substrate in this manner is not particularly limited, but is preferably about 0.01 to 4 μm, and more preferably about 0.1 to 2 μm.

According to the present embodiment, after the polysilazane film is formed on the substrate, the reaction of the polysilazane reacting with moisture to convert to silica is promoted by irradiating with laser light or microwave, thereby forming the silica film. The time required is reduced.
Moreover, since the method of this embodiment does not require a heat treatment process, it can be applied even when heat treatment cannot be performed depending on the type and use of the substrate.

<Second Embodiment>
A second embodiment of the method for producing a silica film of the present invention will be described. This embodiment is greatly different from the first embodiment in that an aqueous layer containing water is formed on the polysilazane film after the formation of the polysilazane film and before irradiation with laser light or microwaves. is there.

First, a polysilazane film is formed on a substrate in the same manner as in the first embodiment.
Next, an aqueous layer is formed on the polysilazane film. Specifically, an aqueous layer solution is applied or dropped onto a polysilazane film, and laser light or microwaves are irradiated in a state where the surface of the polysilazane film is covered with an aqueous layer. The aqueous layer solution only needs to contain water (H ₂ O), and specific examples thereof include water and an aqueous solution having a pH of 4.5 to 9.5.
In addition, when a surfactant or hydrogen peroxide solution is contained in the aqueous layer solution, a more homogeneous aqueous layer can be formed, which is preferable for forming a silica film with good film quality.
The coating amount (or dropping amount) of the aqueous layer solution may be at least the amount that can cover the entire polysilazane film with the aqueous layer.

  Next, laser light or microwaves are irradiated toward the polysilazane film and the water layer formed on the substrate. The type of laser light is the same as in the first embodiment. In addition, when the laser beam or microwave irradiated in this way is easily absorbed by the water layer, the laser beam or microwave hardly travels in the water layer. ) Is preferably within a range in which the entire polysilazane film can be covered with an aqueous layer.

In the present embodiment, polysilazane is converted to silica by irradiation with laser light or microwave, and a silica film is formed. In the present embodiment, it is considered that the irradiated laser light or microwave is absorbed by the base material to generate heat, which causes the polysilazane to be heated and react with moisture in the water layer to be converted to silica.
Also, depending on the combination of the type of laser light or the wavelength of the microwave and the type of water layer, such as when using a CO ₂ laser, the laser light or microwave is absorbed by the water layer, and the water layer generates heat. It is considered that water vapor is generated, and the polysilazane reacts with the water vapor and is converted to silica.

Therefore, according to this embodiment, the time required for forming the silica film is shortened by laser light or microwave irradiation as in the first embodiment, and in particular, the polysilazane film is covered with the water layer. Since the laser beam or microwave is irradiated, water (H ₂ O) necessary for the silica conversion reaction of polysilazane is sufficiently supplied, and the conversion reaction to the silica proceeds better.
Also, depending on the combination of the type of laser beam or microwave wavelength and the type of water layer, if a phenomenon occurs in which the laser beam or microwave is absorbed into the water layer and heat is generated, this causes a conversion reaction to silica. It is considered to be promoted more.

<Third Embodiment>
A third embodiment of the method for producing a silica film of the present invention will be described. The present embodiment is greatly different from the second embodiment in that a heat generating agent that generates heat by laser light or microwave irradiation is contained in the water layer formed on the polysilazane film.

First, a polysilazane film is formed on a substrate in the same manner as in the first embodiment.
Next, an aqueous layer containing a heat generating agent is formed on the polysilazane film. Specifically, the dispersion liquid in which the heat generating agent is dispersed in the aqueous layer liquid in the second embodiment is applied or dropped onto the polysilazane film, and the surface of the polysilazane film is covered with the aqueous layer. To do.

Any heat generating agent may be used as long as it generates heat when irradiated with laser light or microwave, and an appropriate one is selected according to the type of laser light irradiated in the subsequent process or the wavelength of the microwave. For example, the carbon dioxide, nanodiameter, activated carbon, or other carbon is preferable as the exothermic agent when using a CO ₂ laser, and the carbon dioxide, nanodiameter, activated carbon, or other carbon is used as the exothermic agent when using a YAG laser. preferable. The exothermic agent is preferably fine particles.
The coating amount (or dripping amount) of the dispersion containing the exothermic agent is the same as in the second embodiment.

Subsequently, a laser beam or a microwave is irradiated toward the water layer containing the polysilazane film and the heat generating agent formed on the substrate. The type of laser light is the same as in the second embodiment.
As a result, polysilazane is converted to silica to form a silica film. In this embodiment, the irradiated laser light or microwave is absorbed by the heat generating agent to generate heat, water around the heat generating agent is heated to generate water vapor, and polysilazane reacts with the water vapor and is converted to silica. It is thought that.
Also, depending on the type of laser light or the wavelength of the microwave, such as when using a CO ₂ laser, the irradiated laser light or microwave is absorbed by the water in the water layer, and the water generates heat to produce water vapor. It is considered that a phenomenon occurs in which polysilazane reacts with the water vapor and is converted to silica.

According to this embodiment, by irradiating a laser beam or microwave while the polysilazane film is covered with a water layer containing an exothermic agent, the reaction of polysilazane reacting with moisture and converted to silica is promoted, The time required for forming the silica film is shortened. Similarly to the second embodiment, water (H ₂ O) necessary for the silica conversion reaction of polysilazane is sufficiently supplied from the aqueous layer, so that the silica conversion reaction proceeds well.
Furthermore, since the laser beam or microwave is absorbed by the heat generating agent before reaching the base material, the temperature rise of the base material itself can be suppressed as compared with the case where the heat generating agent is not present.

<Fourth Embodiment>
A fourth embodiment of the method for producing a silica film of the present invention will be described. This embodiment is greatly different from the first embodiment in that a polysilazane film contains a heat generating agent that generates heat when irradiated with laser light or microwaves.
Specifically, a heating agent is included in the coating liquid used for forming the polysilazane film in the first embodiment. The same exothermic agent as in the third embodiment can be used.

A polysilazane film is formed on the substrate in the same manner as in the first embodiment except that the heating agent is contained in the coating liquid.
Then, laser light or microwave is irradiated toward the polysilazane film formed on the substrate. The type of laser is the same as in the first embodiment.
As a result, polysilazane is converted to silica to form a silica film. In the present embodiment, the irradiated laser light or microwave is absorbed by the heat generating agent in the polysilazane film to generate heat, whereby the polysilazane film is heated, and the polysilazane reacts with moisture in the atmosphere and is converted to silica. Conceivable.
Therefore, according to the present embodiment, the reaction of polysilazane reacting with moisture to convert to silica is promoted, and the time required for forming the silica film is shortened.
Furthermore, since the laser beam or microwave is absorbed by the heat generating agent before reaching the base material, the temperature rise of the base material itself can be suppressed as compared with the case where the heat generating agent is not present.

  In this embodiment, after forming a polysilazane film containing a heat generating agent, and before irradiating with laser light or microwaves, an aqueous layer containing water is formed on the polysilazane film as in the second embodiment. Alternatively, an aqueous layer containing a heat generating agent and water may be formed on the polysilazane film as in the third embodiment. The same effects as those of the second embodiment and the same effects as those of the third embodiment can be obtained.

<Modification>
In the first to fourth embodiments, laser light or microwave irradiation may be performed in a state where the polysilazane film is in contact with a hydrophilizing agent, whereby a hydrophilic silica film can be generated. Specifically, a hydrophilizing agent may be applied or dropped onto the polysilazane film, and the surface of the polysilazane film may be irradiated with laser light or microwaves while being covered with the hydrophilizing agent. Examples of the hydrophilizing agent include hydrogen peroxide solution, ozone water, acetic acid aqueous solution, pH 4.5 to 9.5 aqueous solution, and alcohols such as ethanol.

In the first and fourth embodiments, when a water layer is not formed on the polysilazane film, alcohols such as ethanol are preferably used as the hydrophilizing agent.
In the second embodiment, the third embodiment, and the fourth embodiment, when an aqueous layer is formed on the polysilazane film, an aqueous solution that acts as a hydrophilizing agent as the aqueous layer solution, for example, hydrogen peroxide It is preferable to use water, ozone water, an acetic acid aqueous solution, an aqueous solution having a pH of 4.5 to 9.5, or the like.
Alternatively, the hydrophilic silica film can also be generated by a method of performing ozone injection during laser light or microwave irradiation.

According to the present invention, since a silica film produced from polysilazane can be formed in a short time, the time required for silica coating can be greatly shortened. Therefore, silica coating for preventing tooth coloring and discoloration for the purpose of aesthetics, ornaments such as accessories, biomaterials such as catheters and stents, dental members such as implants, microchemical chips, DNA chips, Silica coating in a micropipette or the like can be performed quickly, and the production efficiency can be improved. Further, the silica film can contain an ultraviolet absorber, and coloring and deterioration due to ultraviolet rays can be prevented.
In addition, the method of the present invention can be applied to a substrate that is difficult to heat-treat at high temperatures because it can form a silica film produced from polysilazane without requiring heat-treatment. It is particularly suitable for tooth silica coating, and can prevent the adhesion of coloring substances and the like by closing irregularities on the tooth surface. Further, since the formed silica film is glossy, it is excellent in cosmetic aesthetics.
In the method of the present invention, hydrophilic silica can be produced by irradiating a laser beam or microwave while the polysilazane film is in contact with a hydrophilizing agent. Thereby, the hydrophilic silica coating which is excellent in antifouling property and can easily remove attached dirt can be performed in a time without requiring heat treatment. It is particularly suitable for imparting antifouling properties to teeth and dentures.

  Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

(Example 1: Example of containing exothermic agent in polysilazane film)
Bovine crown enamel was used as the base material. That is, the surface of the bovine crown was polished with # 600 water-resistant abrasive paper to expose and polish the enamel on the tooth surface, and then cut into 6 mm × 6 mm. This was etched for 5 seconds using a phosphoric acid aqueous solution (manufactured by 3M ESPE, product name: Scotchbond etchant) as an etching material, and then washed with water and dried as a base material.
On the other hand, a product name: NP-110 (perhydropolysilazane xylene solution) manufactured by Clariant Japan, diluted with xylene to a perhydropolysilazane concentration of 10% by mass (hereinafter referred to as a PHPS solution). To 50 μl, 0.001 g of HCA-100X (product name, manufactured by Mitsui Chemicals), which is a fine powder of HAP (hydroxyapatite), was added as a heat generating agent to prepare a dispersion, which was used as a coating liquid.
A coating solution was applied on the surface (enamel surface) of the base material, and air-dried in air at 22 ° C. for 10 minutes.
Thereafter, CO ₂ laser (trade name: OPELASER, 03SII, Yoshida Seisakusho Co., Ltd.) was irradiated to the surface coated with the coating solution of the base. Irradiation conditions were an output of 1.0 W and a just focus (distance between tip of irradiation tube and substrate irradiation surface: 10 mm) for 1 minute. Thereby, a silica film having a film thickness of 0.85 μm was formed.

For the silica film thus formed on the surface of the base material and the coating film on the base material before laser irradiation (immediately after coating and before drying) for comparison, a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation, product name) : FT-IR8000), and the FT-IR spectrum was measured in the wave number range of 4600 to 650 cm ^{−1 by} the ATR method. An absorption peak attributable to Si-O in the vicinity of 1060 cm ^-1 and near 800 cm ^-1 indicative of conversion into silica, the intensity of the absorption peak attributable to Si-N in the vicinity of 830 cm ^-1 indicating the remaining PHPS unreacted Examined.
The result is shown in FIG. The spectrum indicated by (reference) in FIG. 1 is the measurement result for the coating film before laser irradiation, and the spectrum indicated by (1) is the measurement result for the silica film obtained in this example.
Compared to (reference) in FIG. 1, in the spectrum of (1), the peak near 1060 cm ⁻¹ increases and the peak near 830 cm ⁻¹ decreases. From this, it was confirmed that the conversion from polysilazane to silica occurred through the laser irradiation step.

(Example 2: Example of forming an aqueous layer made of purified water on a polysilazane film)
In Example 1, the coating solution was changed to only a PHPS solution containing no HAP.
And 50 microliters of this coating liquid was apply | coated on the surface of the base material on the same conditions as Example 1, and after drying similarly to Example 1, 40 microliters of purified water was dripped on it.
Thereafter, a CO ₂ laser was irradiated in the same manner as in Example 1. However, laser irradiation was performed on the entire surface while moving the substrate back and forth and left and right within a plane parallel to the surface. Purified water was evaporated by this laser irradiation, and a silica film was obtained. The thickness of the silica film was 0.85 μm.

The FT-IR spectrum was measured in the same manner as in Example 1 for the silica film thus formed on the surface of the substrate. The result is shown in FIG.
Compared with (reference) in FIG. 1, in the spectrum of (2), the peak near 1060 cm ⁻¹ is increased and the peak near 830 cm ⁻¹ is decreased. From this, it was confirmed that the conversion from polysilazane to silica occurred through the laser irradiation step.

(Example 3: Example in which an aqueous layer made of hydrogen peroxide solution was formed on a polysilazane film)
In Example 1, the coating solution was changed to only a PHPS solution containing no HAP.
And 50 microliters of this coating liquid was apply | coated on the surface of the base material on the same conditions as Example 1, and after drying similarly to Example 1, 40 microliters of hydrogen peroxide (concentration 3%) was dripped on it. .
Thereafter, the CO ₂ laser was irradiated while moving the base material in the same manner as in Example 2. By this laser irradiation, the hydrogen peroxide solution evaporated and a silica film was obtained. The thickness of the silica film was 0.85 μm.

The FT-IR spectrum was measured in the same manner as in Example 1 for the silica film thus formed on the surface of the substrate. The result is shown in FIG.
Compared to (reference) in FIG. 1, in the spectrum of (3), the peak near 1060 cm ⁻¹ significantly increased and the peak near 830 cm ⁻¹ greatly decreased. In addition, an absorption peak attributed to Si—O in the vicinity of 800 cm ⁻¹ was also observed. From this, it was confirmed that the conversion from polysilazane to silica occurred through the laser irradiation step. It can also be seen from the size of the peak that the film quality is particularly good.

(Example 4: Example of forming water layer containing exothermic agent on polysilazane film)
A silicon wafer (1 cm × 1 cm) was used as the substrate. As a coating liquid, a PHPS solution prepared by Clariant, Aquamica NP-110 (product name, xylene solution of perhydropolysilazane) diluted with xylene to a concentration of 10% by mass of perhydropolysilazane was used.
First, 50 μl of the coating solution was applied on the surface of the substrate by a flow coating method, and then naturally dried in the atmosphere at 22 ° C. for 10 minutes.
Next, 40 μl of flaky nanodiamond (carbon content: 0.001 g / ml) manufactured by Nanocarbon Laboratory is added as a heat generating agent to 40 μl of hydrogen peroxide (concentration 3%), and 40 μl of the mixed solution is added dropwise. did.
Thereafter, an Nd-YAG laser (YOSHIDA, product name: Opelser-Nd2) was irradiated toward the surface of the base material coated with the coating liquid. At this time, laser irradiation was performed on the entire surface of the substrate while moving the substrate back and forth and left and right within a plane parallel to the surface. Irradiation conditions were an output of 1.5 W, a distance between the irradiation tube tip and the substrate irradiation surface: 20 mm, and irradiation for 1 minute. Thereby, a silica film having a film thickness of 0.85 μm was formed.

The FT-IR spectrum was measured in the same manner as in Example 1 for the silica film thus formed on the surface of the substrate. The result is shown in FIG.
As shown in FIG. 2, an absorption peak attributed to Si—O was clearly seen in the vicinity of 1049 cm ⁻¹ , confirming the formation of silica.

(Example 5: An example in which a water layer made of hydrogen peroxide water was formed on a polysilazane film and irradiated with microwaves)
In Example 1, the coating solution was changed to only a PHPS solution containing no HAP.
And 50 microliters of this coating liquid was apply | coated on the surface of the base material on the same conditions as Example 1, and after drying similarly to Example 1, 40 microliters of hydrogen peroxide (concentration 3%) was dripped on it. .
Thereafter, the substrate was placed in a microwave oven (product name: HITACHI MR-M220, manufactured by Hitachi) so that the surface coated with the coating solution was on the upper side, and was irradiated with microwaves. Irradiation conditions were a frequency of 2450 MHz and an output of 500 W for 1 minute. By this microwave irradiation, the hydrogen peroxide solution was evaporated and a silica film was obtained. The thickness of the silica film was 0.85 μm.
The FT-IR spectrum was measured in the same manner as in Example 1 for the silica film thus formed on the surface of the substrate. The result is shown in FIG. The spectrum shown by (reference) of FIG. 3 is a measurement result about the coating film before microwave irradiation, and the spectrum shown by (5) is a measurement result about the silica film obtained in the present Example.
Compared with (reference) in FIG. 3, in the spectrum of (5), the peak in the vicinity of 1060 cm ⁻¹ , which is an index of silica conversion, remarkably increases, and the peak in the vicinity of 830 cm ⁻¹ indicating Si—N before conversion is large. Diminished. From this, it was confirmed that the conversion from polysilazane to silica occurred through the microwave irradiation process.

It is a figure which shows the FT-IR spectrum of the silica film obtained in Examples 1-3 and the coating film as a reference. 6 is a diagram showing an FT-IR spectrum of the silica film obtained in Example 4. FIG. It is a figure which shows the FT-IR spectrum of the silica film obtained in Example 5, and the coating film as a reference.

Claims (3)

A polysilazane film containing polysilazane is formed on a substrate, an aqueous layer containing hydrogen peroxide water is formed on the polysilazane film, and then the polysilazane is converted to silica by irradiation with laser light or microwaves. A method for producing a silica film, comprising the step of: The method for producing a silica film according to claim 1 , wherein the water layer contains a heat generating agent that generates heat upon irradiation with laser light or microwaves. The method for producing a silica film according to claim 1 or 2 , wherein the polysilazane film contains a heat generating agent that generates heat upon irradiation with laser light or microwaves.

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