JP2799425B2 - Method for producing porous ceramic membrane - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous ceramic thin film having pores with uniform pore diameters on its surface and a method for producing the same.

[0002]

2. Description of the Related Art Heretofore, as a ceramic material having voids and pores, that is, a ceramic porous material,
1) A powder containing internal pores such as zeolite or silica gel, 2) A sintered body such as alumina porcelain or a glass filter produced by sintering powder having pores, 3) A glass is produced by chemical treatment or perforation Porous glass, 4) fiber aggregates such as glass fiber and potassium titanate fiber,
5) Foams such as foam glass and cellular concrete are known (Yanagida Hiroaki, "Science of Ceramics", Gihodo Shuppan, p109 (1981)). However, these are all bulk materials, and the production of porous films of ceramics, especially porous thin films, has conventionally been very difficult, and it has been almost impossible to produce porous thin films having pores with uniform pore sizes. . Also,
There are also methods such as PVD, CVD, and sputtering, and methods of anodizing metal, but these methods are costly, and it is difficult to make a large area,
There have been problems such as difficulty in controlling the pores, limited useable metals, and limited ceramics that can be manufactured.

[0003]

DISCLOSURE OF THE INVENTION In view of the above, the present invention has pores having a uniform pore diameter on the surface, and a catalyst, a catalyst carrier,
It is an object of the present invention to provide a porous ceramic thin film having excellent characteristics as an adsorbing material, a deodorizing / deodorizing material, a sustained-release material, and the like, and a simple and economical production method thereof.

[0004]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, coated a sol solution of ceramics added with polyethylene glycol or polyethylene oxide on a substrate, followed by heating and firing. By doing so, it is possible to produce a porous ceramic thin film having pores with uniform pore sizes on the surface, and to control the size and distribution density of the pores by changing the molecular weight and the amount of polyethylene glycol or polyethylene oxide to be added. Have found the present invention.

[0005] The sol solution of ceramics used in the present invention can be prepared by suspending ultrafine ceramics in water, hydrolyzing alkoxides of metals obtained by the reaction of alcohols with metal salts or metals, or the like. It is prepared by hydrolyzing a metal salt dissolved in an alkoxide. At that time, monoethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, N,
When alcohol amines such as N-dimethyldiaminoethanol and diisopropanolamine and glycols such as diethylene glycol are added, a uniform and transparent ceramic is obtained.
A sol solution of the ceramics is obtained, and by using the same, a ceramic porous thin film having excellent durability can be manufactured.

As the metal alkoxide for preparing the ceramic sol solution used in the present invention, all metal alkoxides are used.
B, Ba, Ca, Cd, Ce, Co, Cr, Cu, F
e, Ge, Hf, In, Li, Mg, Mn, Mo, N
b, Ni, P, Pb, Ru, Si, Sn, Sr, Ta,
Alkoxides of Ti, V, W, Y, Zr and alkoxides of mixtures thereof can be mentioned. Examples of the metal salts include organic acid salts of these metals, such as acetate, oxalate, 2-ethylhexanoate, stearate, lactate, and acetyl acetate.

[0007] The ceramic porous thin film of the present invention is obtained by adding polyethylene glycol or polyethylene oxide to the sol solution of the ceramic thus obtained, and applying a dip coating method, a spin coating method, a coating method, or the like.
It is obtained by coating on a substrate by a spray method or the like, followed by heating and baking. At this time, it is desirable to heat and gradually raise the temperature from room temperature to fire. In order to obtain a strong and durable ceramic porous thin film, a ceramic sol solution to which polyethylene glycol or polyethylene oxide is added is thinly and evenly applied, sprayed or spin-coated, or a dip coating is used to increase the pulling speed. It is desirable to form a thin film of the ceramic film by pulling it up at a slow speed, heat and sinter it, and repeat this operation to produce a multilayer film. As a result, a ceramic porous thin film that is thick, strong, and excellent in durability can be obtained. At this time, by mixing and hydrolyzing two or more metal alkoxides, or by dissolving and hydrolyzing a salt of another metal in the metal alkoxide,
A porous thin film of a composite oxide can be manufactured. Further, by using two or more kinds of sol solutions and coating them alternately or sequentially, a multilayer film of different kinds of ceramics can be easily manufactured.

The polyethylene glycol or polyethylene oxide to be added to the ceramic sol solution used in the present invention preferably has a molecular weight of 1,000 or more.
000, 3000, 6000, 8000, 11000,
13,000, 20,000, 100,000, 300,000, 2,000,000, 250
Thousands are preferred. When the one having a molecular weight of less than 1,000 is used, the resulting ceramic porous thin film is easily peeled off from the substrate, and a clean and strong film cannot be obtained.

The amount of polyethylene glycol or polyethylene oxide added to the ceramic sol solution used in the present invention is preferably not more than its solubility. When added in excess of the solubility, the pores do not become uniform in size and a clean film cannot be formed.

The size of the pore diameter and the density of the pore distribution on the surface of the ceramic porous thin film of the present invention can be controlled by changing the amount of addition or molecular weight of polyethylene glycol or polyethylene oxide. A ceramic porous thin film with small pores aligned when the addition amount is small or a small molecular weight is used, and large pores when a large addition amount or a large molecular weight is used. A uniform ceramic porous thin film can be obtained. When the addition amount is small, a ceramic porous thin film having a sparse distribution of pores is obtained, and when the addition amount is large, a ceramic porous thin film having a fine pore distribution is obtained. Further, when polyethylene glycol or polyethylene oxide having a wide molecular weight distribution is added, a ceramic porous thin film in which pores having various pore sizes are mixed can be obtained.

The substrate used for producing the porous ceramic thin film of the present invention may be any material such as glass, ceramics, concrete, and metal, as long as it can withstand the firing temperature. The shape may be any shape such as a plate, a cylinder, a prism, a cone, a sphere, a gourd, and a rugby ball. Also. Even if the substrate is closed, it may or may not have a lid,
It may be a circular tube, a square tube, a fiber, or a hollow sphere such as a microballoon.

The thus obtained porous ceramic thin film according to the present invention has excellent durability and is porous, so that it can be used as an adsorbent, a deodorant / deodorant material capable of treating a catalyst, a catalyst carrier, or a specific molecule, and a sustained release. It is suitable as a material or the like.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Among the embodiments of the present invention, particularly representative ones will be described below.

Example 1 0.1 mol of titanium tetraisopropoxide was added to 200 m
After diluting with 1 l of absolute ethanol and stirring, 0.1 mol of diethanolamine and 0.1 mol of water were added, and 2 g of polyethylene glycol having a molecular weight of 2,000 was further added to prepare a transparent sol solution. The surface of a 1 mm thick quartz glass plate was coated with a titanium oxide film. That is, a quartz glass plate was immersed in this sol solution, pulled up, dried, and fired. This operation was repeated 10 times, and 4
A 00 nm titania film was made. When the surface of the obtained titania film was observed with an electron microscope, it was found to be covered with pores having a size of about 20 nm.

Example 2 0.12 mol of aluminum triisopropoxide was added to 2
Dilute with 00 ml isopropanol and, with stirring,
0.12 mol of triethanolamine and 1 mol of water were added, and 2.5 g of polyethylene glycol having a molecular weight of 1,000 was further added to prepare a transparent sol solution. And
In the same manner as in Example 1, dip coating was performed to obtain 2
The surface of a quartz glass plate having a size of 1 cm square and a thickness of 1 mm was coated, and the coating was repeated 12 times to form a porous thin film of alumina having a thickness of 500 nm. Observation of the surface of the obtained film with an electron microscope revealed that the film was covered with pores having a size of about 10 nm.

Example 3 0.2 mol of zirconium tetra n-butoxide was added to 50
The mixture was diluted with 0 ml of absolute ethanol, and while stirring, 0.4 mol of diethylene glycol and 0.4 mol of water were added.
g was added to prepare a transparent sol solution. Then, in the same manner as in Example 1, 2 cm was obtained by dip coating.
The surface of a 1 mm-thick quartz glass plate was coated at each corner, and the coating was repeated seven times to form a 300-nm-thick porous zirconia thin film. Observation of the surface of the obtained film with an electron microscope revealed that the film was covered with pores having a size of about 350 nm.

Example 4 0.1 mol of titanium tetraisopropoxide and 0.1 mol of zirconium tetra-n-butoxide were added to 500 ml of isopropanol, and while stirring, 0.4 mol of diisopropanolamine and 0.4 mol of water were added.
Further, 4 g of polyethylene glycol having a molecular weight of 3000 was added to prepare a transparent sol solution. Then, in the same manner as in Example 1, the surface of a 2 cm square quartz glass plate having a thickness of 1 mm was coated by a dip coating method, and the coating was repeated ten times to form a porous thin film of zirconium titanate having a thickness of 400 nm. . Observation of the surface of the obtained film with an electron microscope revealed that the film was covered with pores having a size of about 30 nm.

Example 5 0.1 mol of titanium tetraisopropoxide and lead acetate
0.1 mol of trihydrate is added to 250 ml of isopropanol, and while stirring, 0.2 mol of diethanolamine is added.
And 0.6 mol of water, and 1.6 g of polyethylene glycol having a molecular weight of 2,000 were further added to prepare a transparent sol solution. Then, in the same manner as in Example 1, the surface of a 2 cm square quartz glass plate having a thickness of 1 mm was coated by a dip coating method, and the coating was repeated ten times to form a porous thin film of lead titanate having a thickness of 600 nm. . When the surface of the obtained film was observed with an electron microscope, it was
It was covered with pores of nm size.

Example 6 0.2 mol of niobium pentaethoxide was diluted with 500 ml of absolute ethanol, 0.4 mol of N-ethyldiethanolamine and 0.4 mol of water were added thereto with stirring, and polyethylene oxide having a molecular weight of 100,000 was added. .
2 g was added to prepare a transparent sol solution. Then, in the same manner as in Example 1, 2c was formed by dip coating.
The surface of a 1 mm-thick quartz glass plate with m squares was coated and repeated 9 times to form a porous thin film of niobium oxide having a thickness of 400 nm. Observation of the surface of the obtained film with an electron microscope revealed that the film was covered with pores having a size of about 500 nm.

EXAMPLE 7 0.1 mol of zirconium tetra-n-butoxide and 0.1 mol of lead acetate trihydrate were added to 500 ml of isopropanol, and 0.2 ml of diethanolamine was added with stirring.
ol and 0.6 mol of water were added, and 0.1 g of polyethylene oxide having a molecular weight of 2,000,000 was further added to prepare a transparent sol solution. Then, in the same manner as in Example 1, the surface of a 2 cm square quartz glass plate having a thickness of 1 mm was coated by a dip coating method, and the coating was repeated 20 times to form a porous thin film of lead zirconate having a thickness of 800 nm. . When the surface of the obtained film was observed with an electron microscope,
It was covered with pores having a size of about 1100 nm.

Example 8 0.1 mol of titanium tetraisopropoxide, 0.1 mol of zirconium tetra-n-butoxide and 0.2 mol of lead acetate trihydrate were added to 500 ml of isopropanol, and while stirring, 0.4 mol of diethanolamine and water were added. 1.2 mol was added, and 0.2 g of polyethylene oxide having a molecular weight of 200,000 was further added to prepare a transparent sol solution. Then, in the same manner as in Example 1, a 2 cm square quartz glass plate having a thickness of 1 mm is coated by a dip coating method, and the coating is repeated 15 times to form a porous thin film of lead zirconate titanate having a thickness of 600 nm. Had made. When the surface of the obtained film was observed with an electron microscope,
It was covered with pores having a size of about 800 nm.

[0022]

As described above, an object of the present invention is to provide a ceramic porous thin film having pores with uniform pore sizes on the surface and a simple and economical method for producing the same. A simple method of coating a substrate with a sol solution of ceramics to which polyethylene glycol or polyethylene oxide has been added, followed by heating and firing, can produce a ceramic porous thin film having pores with uniform pores on the surface, and the polyethylene to be added. The pore size and distribution density can be easily controlled by changing the molecular weight or the amount of glycol or polyethylene oxide added. According to this method, it is possible to produce an extremely thin ceramic porous film of nano order, which was impossible with the conventional method, and to obtain a ceramic porous film having a desired pore size and distribution density. Can be made. It is also possible to produce a ceramic porous thin film with a three-dimensional structure by stacking them, mixing two or more types of metal alkoxides and hydrolyzing them, or dissolving salts of other metals in metal alkoxides. By using the sol solution or by using two or more kinds of sol solutions, it is possible to easily produce a porous thin film of a composite oxide or a multilayer film of different kinds of ceramics. Furthermore, this method requires a lower sintering temperature than conventional methods, and is therefore energy saving and economical. The resulting ceramic porous thin film has excellent heat resistance and durability, and is suitable for catalysts, catalyst carriers, adsorbents capable of treating specific molecules, deodorant / deodorant materials, sustained-release materials, etc. Can have a large ripple effect on the industry.

Claims (4)

(57) [Claims] 1. A method for producing a ceramic porous thin film, comprising coating a substrate with a sol solution of ceramics to which polyethylene glycol or polyethylene oxide is added, followed by heating and firing. 2. The method for producing a porous ceramic thin film according to claim 1 , wherein a polyethylene glycol or polyethylene oxide having a molecular weight of 1,000 or more is used. 3. A process according to claim 1 Symbol the addition amount of the polyethylene glycol or polyethylene oxide for the sol solution of the ceramic is equal to or less than its solubility
Method of manufacturing a ceramic porous membrane of the mounting. 4. The method of claim, wherein the sol solution ceramics are those prepared from alkoxide and alcohol amines or glycols ceramics 1
The method for producing a titanium oxide porous thin film photocatalyst according to the above.