JP5435541B2 - Manufacturing method of inorganic film - Google Patents

Description

  The present invention relates to an efficient method for producing an inorganic film using an electrophoretic electrodeposition method.

The electrophoretic electrodeposition method is considered to be effective as a method for providing a film of particles such as inorganic substances on a substrate. (Non-Patent Document 1)
According to electrophoretic electrodeposition, the composition of the film can be determined in advance at the stage of the particles to which the film composition is applied, the film forming speed is high, and a thick film can be produced. This is because it can be easily controlled and the apparatus is simple.
In this electrophoretic deposition method, 1) particles are charged in a solvent. 2) Electrophoresis of charged particles by an electric field. 3) It consists of three elements: electrophoretic particles are electrodeposited (deposited) on the substrate.

  Among these, the selection of the solvent is an important matter in the charging of the particles of 1). That is, since a voltage is applied to the solvent used in the electrodeposition bath, in the case of an aqueous solution system, water is electrolyzed unless hydrogen electrolysis voltage (1.23 V) or lower, and hydrogen gas or oxygen gas is formed on the electrode. May occur and destroy the deposited particle layer (electrodeposited film). In the case of an aqueous solution, the conductivity of the bath is increased by the electrolyte and the like, so that the power consumption tends to increase, and the voltage cannot be increased so much that the film forming speed cannot be increased.

  For this reason, a method using a non-aqueous solvent as a solvent for the electrodeposition bath has been proposed. However, the condition is that it is liquid at room temperature and has a high dielectric constant.

  Until now, polar organic solvents such as ketones such as acetone and acetylacetone, alcohols such as methanol, ethanol and propanol, and propylene carbonate have been used as such solvents. In addition, a surfactant or the like was added to toluene, hexane or the like having a low dielectric constant. When these organic solvents are used, the voltage can be increased to 100 V, 1000 V, etc., so that there is an advantage that the film forming speed can be greatly increased.

  For example, Patent Document 1 discloses that “zeolite powder is dispersed in an organic solvent such as acetone, alcohols, acetonitrile, and the like and electrophoretic electrodeposition of the zeolite powder on the surface of a substrate by applying a voltage of 10 to 1000 V. Is disclosed.

  Patent Document 2 states that “by adding a powder of antibacterial and antifungal properties to a solvent obtained by adding a small amount of water and iodine to acetone, an organic solvent such as ethanol, and applying a voltage of 30 to 1000V. Presents a method of electrophoretic deposition of the zeolite powder on the surface of the substrate.

  However, the solvents used in these conventional electrodeposition baths are all flammable liquids that are designated as dangerous materials under the Fire Service Law, and therefore, it is necessary to take a strict management system for handling them. There was a limit to commercialization on an industrial scale. In addition, when an organic solvent known so far is used, the applied voltage can be increased as compared with the aqueous solvent, but the current density is high and the average power consumption per unit area is extremely high. There was also a problem.

JP 2001-89134 A JP-A-8-134597

Nobuyuki Koura et al., Surface, “Preparation of highly functional material film using electrophoretic electrodeposition method”, 42 (1), 20 (2004)

  The present invention overcomes the above-mentioned problems of the prior art and is an industrially extremely advantageous inorganic film that can form an inorganic film on a substrate safely, in a low time, and with an ultra-low power without using a flammable solvent. It aims at providing the film forming method.

As a result of intensive studies on a method for safely and efficiently producing an inorganic film such as a silica film on a substrate by electrophoretic electrodeposition, the present inventors have found that hydrofluoroether is used as a solvent for the electrodeposition bath. It has been found that the electrophoretic electrodeposition bath can be prepared in a short period of time without danger of ignition and the like, and the silica film can be produced safely and with low power, and the present invention has been completed.
That is, this application provides the following invention.
<1> In the method of forming an inorganic film on the substrate surface by electrophoretic electrodeposition, hydrofluoroether in which a part of hydrogen of saturated aliphatic ether is substituted with fluorine is used as a solvent for the electrodeposition bath. manufacturing method of the inorganic film, characterized.
<2> The method for producing an inorganic film according to <1>, wherein the hydrofluoroether is a fluoroether represented by the following general formula (I).
R ¹ -O-R ² (I)
(R ¹ and R ² are an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms, and at least one of R ¹ and R ² is a fluoroalkyl group having 1 to 6 carbon atoms. .)
<3> The substrate is at least one substrate selected from metals, alloys, stainless steel, carbon materials, ceramics imparted with conductivity, and plastic substrates imparted with conductivity <1> or The manufacturing method of the inorganic film as described in <2>.
<4> the inorganic film, any silica, MFI-type zeolite, characterized in that it is a film of mesoporous silica, zeolites, and metal oxides or we selected at least one inorganic substance of (1) to (3) A method for producing an inorganic film according to claim 1.

According to the method of the present invention, the following remarkable effects can be obtained.
(1) A high voltage can be applied to the electrophoretic electrodeposition bath without using a flammable solvent, and there is no danger of ignition or the like.
(2) Power consumption for manufacturing can be greatly reduced.
(3) The electrophoretic electrodeposition bath can be prepared in a short time.
(4) An inorganic film can be manufactured with high accuracy and good reproducibility over a long period of time without depending on the environment and time.
(5) The film thickness to be formed can be precisely controlled by controlling the voltage and voltage application time.
(6) Effective for mass productivity and cost reduction.

The figure which shows the typical electrophoretic electrodeposition apparatus used with this invention method Film-forming photograph of mesoporous silica (MPS) film obtained in Example 1 The graph which measured the electrodeposition time of the electrophoretic electrodeposition method of Example 1, and the current density Film-forming photograph of the high pre-silica film obtained in Example 2 The graph which measured the relationship between the electrodeposition time of the electrophoretic electrodeposition method of Example 2, and current density Film formation photograph of titanium oxide film obtained in Example 3 Film-forming photograph of the magnesium oxide film obtained in Example 4 Film-forming photograph of silicalite R-6 film obtained in Example 5 Film-forming photograph of YSZ film obtained in Example 6 Film-forming photograph of silicalite R-6 film obtained in Example 7 Film-forming photograph of silicalite R-6 film obtained in Example 8 Film formation photograph of titanium oxide film obtained in Example 9 Film formation photograph of titanium oxide film obtained in Example 10 The graph which measured the relationship between the electrodeposition time of the electrophoretic electrodeposition method of the comparative example 1, and current density

1. Electrodeposition substrate 2. Electrodeposition bath 3. Counter electrode 4. DC power supply (apparatus for voltage application)

  The method for producing an inorganic film by the electrophoretic electrodeposition method of the present invention is characterized in that hydrofluoroether in which a part of hydrogen of saturated aliphatic ether is substituted with fluorine is used as the organic solvent for the electrodeposition bath.

This hydrofluoroether is environmentally friendly with zero ozone depletion potential, low global warming potential, virtually non-toxic, high tolerable concentration, high safety such as no incombustibility and no flash point, and low surface tension and viscosity. From low latent heat of vaporization, solvent for cleaning semiconductors, etc., electrical insulation, no incombustibility, no flash point, thermal and chemical stability, waste heat utilization system solvent, cooling, thermostatic bath solvent, It is used as a medium for withstand voltage testing of electronic components.
However, a method for applying the property of the dielectric constant of hydrofluoroether as a solvent for the electrodeposition bath of electrophoretic electrodeposition has not been known at all so far, and a novel finding discovered by the present inventors for the first time. It is.

The hydrofluoroether preferably used in the present invention is represented by the following general formula (1).
R ¹ -O-R ² (I)
(R ¹ and R ² are an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms, and at least one of R ¹ and R ² is a fluoroalkyl group having 1 to 6 carbon atoms. .)

Examples of the hydrofluoroether represented by the general formula (I) include methyl nonafluorobutyl ether (C ₄ F ₉ OCH ₃ ), ethyl nonafluorobutyl ether (C ₄ F ₉ OC ₂ H ₅ ), methyl trideca Examples include fluorohexyl ether (C ₆ F ₁₃ OCH ₃ ) and C ₃ HF ₆ —CH (CH ₃ ) OC ₃ HF ₆ . Among these, from the viewpoint of relative dielectric constant, it is preferable to use methyl nonafluorobutyl ether (C ₄ F ₉ OCH ₃ ) or ethyl nonafluorobutyl ether (C ₄ F ₉ OC ₂ H ₅ ).

Examples of such commercially available hydrofluoroethers include Novec series [HFE7100 (C ₄ F ₉ OCH ₃ ), HFE 7200 (C ₄ F ₉ OC ₂ H ₅ ), HFE 7300 (C ₆ F _{13 OCH 3), HFE7600 (C 3} HF 6 -CH (CH 3) OC 3 HF 6)] can be mentioned.

  In the method of the present invention, an inorganic substance to be formed into a film is dispersed and dissolved in the hydrofluoroether to prepare an electrodeposition bath, which is electrophoretically deposited to form an inorganic film on the substrate.

As the inorganic substance, all conventionally known various inorganic substances used in this type of electrophoretic electrodeposition method can be used.
Examples of such an inorganic material, silica (anhydrous silicic acid, quartz, cristobalite, Aerosil), MFI-type zeolite (silicalite, ZSM-5), mesoporous silica mosquitoes, zeolite preparative represented by aluminosilicate, magnesium oxide, Examples of the metal oxide include aluminum, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, copper oxide, zinc oxide, niobium oxide, tungsten oxide, zirconia oxide, and yttria-stabilized zirconia (YSZ). Among these, it is desirable to use silicalite, mesoporous silica, and zeolite when viewed from the viewpoint of an adsorption membrane, a separation membrane, etc. using the porosity of an inorganic substance. Further, from the viewpoint of a separation film that uses the gap of the deposited film that utilizes the stability of the inorganic substance for separation, it is desirable to use silica, aluminum oxide, titanium oxide, and zirconium oxide.

  The inorganic substance is preferably in the form of particles or powder so that it is uniformly dispersed in the hydrofluoroether. For example, in the case of mesoporous silica, it is desirable to have a fine powder shape (particle size of 40 μm or less). In this case, it is necessary to keep the amount of water contained in it as small as possible by the humidity control method or the drying method, and preferably to keep it substantially free of moisture in terms of thick film production at the actual manufacturing site. It is preferable from the viewpoint. The method for synthesizing silica is not limited.

  Although there is no restriction | limiting in the stirring time at the time of disperse | distributing the said inorganic powder in a hydrofluoroether solvent, You may apply a ultrasonic wave using a stirrer.

In the method of the present invention, an electrodeposition substrate (anode electrode) is placed while inorganic powder is dispersed in this solvent, and a voltage of finite value exceeding 0V to 1000V is applied.
In the solvent, the inorganic powder such as silica is negatively charged, moves toward the anode electrode, and can be deposited on the electrode surface as an ordered arrangement.

The substrate (anode electrode) used in the method of the present invention is preferably formed of a conductive material, and any substrate that can be used as an electrode can be used as appropriate.
Such substrates are provided with metals such as Al, Cu, Fe, Ni, Ti, Ag, Au, Pt, W, and their alloys, stainless steel, ordinary steel, low alloy steel, carbon material, and conductivity. Examples thereof include non-metallic materials such as ceramics, glass, ceramics, and plastics, and porous ceramic substrates having electrodes on the back side.
When using a non-metallic material that is not conductive as a substrate, it is possible to impart conductivity by electroless plating of Ni, Cu or the like or coating with conductive ceramics such as ITO prior to electrophoretic electrodeposition. it can.
The substrate may have various shapes such as a plate shape, a tubular shape, a prism shape, and the like. Since the thick film is formed on the surface of the substrate, a member constituting the device can be used as the substrate when incorporated in the device. When the tube or prismatic shape is deformed, a thick film can be formed along the shape.

Generally, the amount of electrodeposition increases with the passage of time within a specific time. When this time period elapses, the electrodeposition amount becomes constant. The relationship between the amount of electrodeposition and the electrodeposition time per unit follows the same process. Also, the electrodeposition time and electrodeposition thick film follow the same process.
Based on the results measured in advance, the electrodeposition film having a desired thickness of up to about 1 mm can be manufactured by controlling the voltage and the electrodeposition time.

In the method of the present invention, since hydrofluoroether is used as the solvent for the electrodeposition solution, the silica particle film can be reproduced with high accuracy and over a long period of time at an ultra-low voltage without depending on the environment or time. It can be manufactured with good performance.
That is, by using hydrofluoroether in the electrodeposition bath, the current value can be greatly reduced as compared with the conventional acetone-iodine electrodeposition bath, acetone bath, and 1-propanol bath. Since electrodeposition is performed, the power (current × voltage) applied to the film formation can be greatly reduced.

Next, the electrophoretic electrodeposition process of the present invention will be described more specifically.
FIG. 1 is a diagram showing a representative apparatus for electrophoretic electrodeposition used in the present invention. In FIG. 1, 1 is an electrodeposition substrate, 2 is an electrodeposition bath, 3 is a counter electrode, and 4 is a DC power source. The electrodeposition bath 2 can be prepared by dispersing the inorganic powder in the hydrofluoroether solvent in a container such as a beaker or a graduated cylinder and preparing the electrodeposition bath, and transferring it to a square cell as shown in FIG. Alternatively, the electrodeposition bath may be prepared by dispersing the inorganic powder in the hydrofluoroether solvent in a square cell as shown in FIG.
During the preparation, stirring by a stirrer or the like or ultrasonic vibration may be used. The reason is that it is considered that there is an effect of preventing the stacking of the inorganic powders and improving the orientation of the inorganic powders. In the solvent, when the inorganic powder is negatively charged, the substrate is used as an anode and a counter electrode is provided. In the solvent, when the inorganic powder is positively charged, the substrate is used as a cathode and a counter electrode is provided. As the counter electrode, a known electrode such as stainless steel, titanium, Ag, Pt, or Au can be appropriately used.

By applying a voltage for a certain period of time, the inorganic powder can be electrophoresed to form a film made of inorganic particles on the substrate surface. The voltage varies depending on the capability of the electrophoretic electrodeposition apparatus. As the voltage by the DC power supply (4 in FIG. 1), a voltage ranging from a finite value exceeding 0V to 1000V is adopted.
“A range from a finite value exceeding 0 V to 1000 V” means that in the present invention, it is essential to apply a voltage in electrophoretic deposition. Specifically, since the electrophoretic electrodeposition cannot be performed when the voltage value at that time is 0, the voltage does not include 0, and even if the value exceeds 0, for example, 0.01, It means that it may be 0.1, 1 or 100V. As a conclusion, it means that a voltage with a lower limit value exceeding 0 and a voltage with an upper limit value of up to 1000 V may be applied.

In electrophoretic deposition, the speed of movement of the inorganic powder depends on the electric field. When electrophoretic electrodeposition is performed at a constant voltage, the amount of electrodeposition increases with the passage of time within a specific time. When this specific time zone elapses, the amount of electrodeposition does not increase and eventually becomes a constant value. The relationship between the amount of electrodeposition per unit and the electrodeposition time follows a similar process. Also, the electrodeposition time and electrodeposition thick film follow the same process. At this time, the current value also changes depending on the amount of electrodeposition. When electrophoretic electrodeposition is performed at a constant current, the increase in the amount of electrodeposition is constant. However, in either case, if the concentration of the inorganic powder in the electrodeposition bath is reduced by electrodeposition, the rate of increase in the amount of electrodeposition decreases.
Thus, the change of the electrodeposition amount can be predicted. Therefore, electrodeposition may be performed until a desired electrodeposition thick film and electrodeposition amount are obtained based on what can be measured in advance.

  The present invention will be described below with reference to examples.

Example 1
The electrophoretic apparatus shown in FIG. 1 in which the electrodeposition substrate 1 (anode substrate: aluminum) has a surface area of 3.5 cm ² and the counter electrode 3 has two stainless plates (surface area of 3.5 cm ² ) is used. A mesoporous silica film was prepared. Specifically, a solution obtained by dispersing 0.03 g of mesoporous silica powder in 10 cc of a hydrofluoroether solvent (Novec HFE-7200) is used as an electrodeposition bath 2, and this is subjected to an electrodeposition experiment for 2 minutes at an applied voltage of 100 V. went. A film-forming photograph of the obtained mesoporous silica film is shown in FIG. Moreover, the graph which measured the relationship between electrodeposition time and current density is shown in FIG.
FIG. 3 shows that the current density is about 0.000004 mA / cm ^{2 to} 0.0000015 mA / cm ² , and the average power value is 0.000275 mW / cm ² (275 nW / cm ² ). This average power value is an extremely small value such as about 1/5000 of Comparative Example 1 described later. In the present invention, it is shown that mesoporous silica film can be formed with power saving of about 1/5000 of the conventional method. ing. Further, this average power value is an extremely small value such as about 1/60000 of Comparative Example 2 to be described later. In the present invention, it is shown that film formation is possible with power saving of about 1/60000 of the conventional method. Yes.

Example 2
In Example 1, except for changing the mesoporous silica powder Haipure deer (TM) (silica fine particles) was carried out by following the procedure of electrodeposition experiment as in Example 1. The film photograph of the resulting Haipure deer film shown in FIG. Moreover, the graph of the relationship between electrodeposition time and current density is shown in FIG.
FIG. 5 shows that the current density is about 0.000004 mA / cm ^{2 to} 0.000007 mA / cm ² and the average power is 0.0005 mW / cm ² (500 nW / cm ² ). This average power value is an extremely small value such as about 1/33000 of Comparative Example 2 to be described later. In the present invention, it is shown that film formation is possible with power saving of about 1/33000 of the conventional method.

Examples 3-6
Example 1 is the same as Example 1 except that the mesoporous silica powder is replaced with titanium oxide (Example 3), magnesium oxide (Example 4), silicalite (Example 5), and YSZ (Example 6). Thus, various inorganic films were formed. Film-forming photographs are shown in FIG. 6 (Example 3), FIG. 7 (Example 4), FIG. 8 (Example 5), and FIG. 9 (Example 6).
In Examples 3, 5, and 6, the average current density and the average power were as follows.
Example 3 Average current density 1.2 nA / cm ² Average power 0.12 μW / cm ²
Example 5 Average current density 1.8 nA / cm ² Average power 0.18 μW / cm ²
Example 6 Average current density 1.0 nA / cm ² Average power 0.1 μW / cm ²

Examples 7-8
In Example 5, various changes were made in the same manner as in Example 5 except that the hydrofluoroether solvent (Novec HFE-7200) was changed to Novec HFE-7100 (Example 7) and Novec HFE-7300 (Example 8). An inorganic film was formed. The film-forming photographs are shown in FIG. 10 (Example 7) and FIG. 11 (Example 8).
In these examples, the current density and average power were as follows.
Example 7 Average current density 2.0 nA / cm ² Average power 0.2 μW / cm ²
Example 8 Average current density 3.5 nA / cm ² Average power 0.35 μW / cm ²

Examples 9-10
In Example 2, except that the hydrofluoroether solvent (Novec HFE-7200) was changed to Novec HFE-7100 (Example 9) and Novec HFE-7300 (Example 10), various inorganic materials were used. A membrane was formed. The film-forming photographs are shown in FIG. 12 (Example 9) and FIG. 13 (Example 10).
In these examples, the current density and average power were as follows.
Example 9 Average current density 1.0 nA / cm ² Average power 0.1 μW / cm ²
Example 10 Average current density 2.5 nA / cm ² Average power 0.25 μW / cm ²

Comparative Example 1
In Example 1, a mesoporous silica film was obtained in the same manner as in Example 1 except that the hydrofluoroether solvent (Novec HFE-7200) was replaced with dehydrated acetone. FIG. 14 shows the change over time of the current value when electrodeposited at 100V. The current value is about 0.02 mA / cm ^{2 to} 0.005 mA / cm ² . The average power is 1.25 mW / cm ^2. This power value is about 5000 times that of the first embodiment. Moreover, it is about 2500 times of Example 2.

Comparative Example 2
In Example 6, a YSZ film was obtained in the same manner as in Example 1 except that the hydrofluoroether solvent (Novec HFE-7200) was replaced with 1-propanol. The current density at this time is 0.25mA / cm ² ~0.08mA / cm ² about. The average power is 16.5 mW / cm ^2. This power value is about 60,000 times that of the first embodiment. Moreover, it is 33000 times of Example 2. From this, in the present invention, it is shown that film formation is possible with power saving of about 1/2500 to 1/60000 of the conventional method.

Claims (4)

In the method of depositing an inorganic film on a substrate surface by electrophoretic electrodeposition, hydrofluoroether in which a part of hydrogen of saturated aliphatic ether is substituted with fluorine is used as a solvent for the electrodeposition bath. manufacturing method of inorganic membrane. The method for producing an inorganic film according to claim 1, wherein the hydrofluoroether is a fluoroether represented by the following general formula (I).
R ¹ -O-R ² (I)
(R ¹ and R ² are an alkyl group having 1 to 6 carbon atoms or a fluoroalkyl group having 1 to 6 carbon atoms, and at least one of R ¹ and R ² is a fluoroalkyl group having 1 to 6 carbon atoms. .)   3. The substrate according to claim 1, wherein the substrate is at least one substrate selected from a metal, an alloy, stainless steel, a carbon material, a ceramic provided with conductivity, and a plastic substrate provided with conductivity. Of manufacturing the inorganic film. Inorganic membranes, silica, MFI-type zeolite, mesoporous silica, zeolite, and inorganic as claimed in claim 1, characterized in that a film of the metal oxide or we selected at least one inorganic substance A method for producing a membrane.