JPS6236016A - Clay derivative film having porous structure and its production - Google Patents

Abstract

PURPOSE:To provide an extremely stable clay deriv. film which has porous structure, is strong and tough and is flexible by incorporating silica.oxide polyvalent metallic hydrate between layers of smectite. CONSTITUTION:A) Silica sol such as polysilicic acid, silica hydrosol or org. silica sol obtd. by hydrolyzing silicon alkoxide Si(OR)4 (R is a straight chain or branched chain alkyl group of 1-6 C). B) A group consisting of water or acid soluble polyvalent metallic salt and Ti(OR)4 (R is the same as above) or TiO2 hydrosol obtd. by peptization with an acid. The silica oxide polyvalent metallic hydrosol formed by acting >=1 kinds of the above-mentioned components A and B is brought into reaction with smectite. The desired clay deriv. incorporated with the silica oxide polyvalent metallic hydrosol between the clay layers is thus obtd. and the clay deriv. film is obtd. when such deriv. is coated and dried.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a clay derivative film having a porous structure and a method for producing the same. A film of a composite of clay mineral and silica/polyvalent metal oxide fine particles having a distance determined by measurement, which is the sum of the thickness of the clay silicon salt layer (approximately 9.8 A and the interlayer void distance), and its Relating to a method of manufacturing. The purpose is to provide a new inorganic membrane with a stable porous structure, and by using the clay derivative of the present invention, a flexible and strong sheet-like self-retaining membrane or coating can be easily changed. It is useful as an adsorption/separation membrane, a sensor coating, a catalyst, a catalyst carrier, an encapsulating agent, a heat insulating or heat retaining sheet, and a breathable membrane.The membrane can also be multilayered and used as a non-LA or 'A substrate.

It has a porous structure and can be used in a wide variety of applications, such as inorganic adhesives and coating agents, and is industrially useful.

[Prior art] Smectite, represented by montmorillonite and beidellite, is a group of minerals that make up clay, and has a layered structure, with exchangeable cations such as sodium, potassium, calcium, and magnesium existing between the layers. In order to
It is well known that various organic or inorganic ions and polar molecules are introduced between the layers. Normally, water molecules in the atmosphere are adsorbed between the layers of smectite.
．． There is a gap (interlayer void) of approximately 0 to 5.8 A, but water is easily desorbed from such interlayer voids due to water molecule adsorption not only by heating but also by vacuum degassing, so it is not stable. It cannot exist.

It has been known for a long time that these smectite films can be easily created reflecting the two-dimensional nature of clay. However, these membranes cannot maintain a stable shape because they reswell with water.
Furthermore, the interlayers easily contract, making it impossible to form a porous membrane.

On the other hand, attempts have been made to insert bulky polynuclear metal ions between the layers as pillars to support the interlayers and obtain a stable porous body. That is, in this method, water-soluble polynuclear total ions or polynuclear hydroxide metal ions produced by hydrolyzing metal ions with alkali are introduced between the layers of smectite, and then thermally decomposed to build oxide pillars between the layers. A method comprising: aluminum (Clay Miner, 12.229
~238 (1977), ), chromium (Amer, M
iner,, 84°830-835 (1979),)
, Zirconium (Clays Clay Mine
r,, 27.119-124 (1979), ), using polynuclear metal ions such as iron [JP-A-58-55,332], the interlayer void is 5-8λ, and the specific surface repair is 200-400.
A method of obtaining a porous body of m2/g is known.

In this type of porous material, the swelling property is reduced by the introduction of oxide supports, and at the same time pores are formed, but the film forming function is completely lost, and large pores cannot be formed.

[Problems to be Solved by the Invention] When the porous body is actually used as an adsorbent, a catalyst, a catalyst carrier encapsulating agent, a heat insulating agent, etc., the interlayer voids are too small at 5 to 8 A, and the effective diameter is too large. It was insufficient for molecular applications. In addition, the conventional method has limitations on the types of metals that can be used, and for example, it has not been possible to introduce silica or titanium oxide, which is prized as a pigment because of its high refractive index of 41, between the layers.

In addition, the functionality of adsorbents, catalysts, catalyst carriers, encapsulating agents, etc. is influenced not only by the inherent properties of the material, but also by its shape. As the surface area increases, adsorption performance and catalyst activity are expected to increase. Furthermore, by making the film thinner, the amount of material used can be reduced and costs can be reduced, and new properties such as transparency can be imparted. Although such functional thin films are required to have flexibility, density, and toughness, no inorganic thin film that has all of these required properties has been obtained. The present invention aims to solve the problems at once and provide a strong and flexible clay derivative film having a porous structure and a method for producing the same.

[Means for Solving the Problems] The present inventors have determined that the struts to be introduced between the clay layers in order to provide a clay derivative film having a porous structure are heated at 500°C.
In view of the above, it was considered that silica which is stable, has various polymerization forms, and can be converted into an oxide having a large degree of polymerization, that is, a high molecular weight, is suitable. However, when comparing the pH of various hydroxides and oxides that do not have one surface type position, that is, the zero charge point, Al(OH) 35.1, Zr0210.5,
〒+02'6.7. Therefore, since silica is negatively charged at a pH of 1.8 or higher, it was not introduced between the clay layers, which are originally negatively charged, due to electrostatic repulsion. Therefore, we conducted various studies in order to maintain positive charges on the silica surface.

Reaction■ Silicon alkoxide Si(OR)a (R
represents a straight-chain or branched alkyl group having 1 to 5 carbon atoms. The resulting polymer of silicic acid is called polysilicic acid), silica hydrosol,
Silica sol such as organic silica sol, a water- or acid-soluble polyvalent metal salt, and Ti(OR)e (R is as described above), or titanium oxide obtained by hydrolyzing this and then peptizing it with an acid. A reaction in which smectite is reacted with silica/polyvalent metal oxide hydrosyl produced by reacting one or more selected from the group consisting of hydrosols (hereinafter referred to as polyvalent metal oxide sources) with smectite. 1 selected from valent metal sources
Reaction ■ Adding silica sols to smectite and then reacting with an oxidized polyvalent metal source, Reaction ■ to Reaction ■ can be carried out to achieve the desired result. If the obtained clay derivative is further cast or coated on, for example, a Teflon mold or aluminum foil and then dried, it will have a large interlayer distance and a large specific surface area as the object of the present invention. The present invention was completed by discovering that it is possible to produce a clay derivative membrane with a porous structure.

Specifically, the present invention provides a clay derivative film having a porous structure characterized by containing silica/polyvalent metal oxide hydrate between smectite layers, and a method for producing the same.

In any of the reactions from reaction (1) to reaction (2) of the present invention, a polyvalent metal oxide oxide is introduced between the clay layers. Swellable smectite is suitable for this purpose, but it is not limited to natural clay minerals, and synthetic ones may also be used.Also, various artificial fluorine layered silicates that are wettable with water and have ion exchange ability are also suitable. Available. The crystal structure of these natural and synthetic clay minerals is composed of two-dimensional silicates with a thickness of about 8.8 A stacked on top of each other, but the shape of the crystallites reflects the two-dimensionality of the bonds. In reflection, it is plate-shaped, and similar two-dimensional gaps are formed between layers inside the crystal at grain boundaries where crystal grains overlap. Note that the term "interlayer" as used in the present invention includes not only the silicate layers inside the crystallites but also the grain boundaries between such crystallites.

Among the silica sols used in the present invention, Si(OR)
As s, silicon tetraethoxide in which R is an ethyl group is preferred because it is inexpensive and easily available.

Hydrolysis of silicon tetraethoxide is carried out by adding a mixture of ethanol as a solvent, water as a decomposition agent, and acid as a catalyst and heating the mixture from room temperature to 80°C. The conditions for hydrolysis are arbitrarily selected depending on the polymerization form and degree of polymerization, i.e., molecular weight, of the polysilicic acid to be prepared (Journal of Ceramics Association, Cod, 242-247 (1984)).
, that is, the circular is H2O/Si(OC2Hs)n
= 2 or less, a chain polymer is generated and H2O/Si(
In OC2H5)*-5, a chain polymer is produced in the early stage of polymerization, but a three-dimensional network polymer is produced in the latter stage. Furthermore, it has been reported that in H70/Si(OC2Hs)a-20, a three-dimensional network polymer is formed from the initial stage. 20/Si (OC2Hs) Although it can be carried out under conditions outside the range of i-2 to 20, H2O/Si can be carried out in a suitable polymerization time without causing rapid viscosity increase and gelation. (OG2Hs)n-2~20
is desirable, and for the same reason, Si(OC2Hs)a
The concentration of is preferably 30 to 70%, and as the catalytic acid, inexpensive mineral acids such as hydrochloric acid, nitric acid, and sulfuric acid are used.

Furthermore, silica sols include not only polysilicic acid obtained by hydrolyzing silicon tetraethoxide as described above, but also colloidal particle diameters using water as a dispersion medium.
It is possible to use a commercially available 100 silica hydrosol or an organic silica sol using an organic solvent such as methanol, ethanol or isopropyl alcohol as a dispersion medium. Furthermore, it goes without saying that the object of the present invention can also be achieved by using several types of polysilicic acid, silica hydrosol and organic silica sol in combination.

The polyvalent metal oxide sources used in the present invention include titanium tetraisopropoxide or titanium oxide hydrosol obtained by hydrolyzing it and peptizing it with acid, titanium tetrachloride, oxysulfuric acid, etc. Cheap and readily available water-soluble titanium salts such as titanium can also be used. Furthermore, it goes without saying that several of the above titanium sources may be used in combination.

Titanium oxide hydrosol is prepared by using titanium alkoxide Ti(OR)n (R is as mentioned above), generally cheap and easily available isopropoxide in which R is an isopropyl group. The white precipitate generated by adding the titanium alkoxide to a 4 times molar acid solution is gradually dissolved in the acid to obtain a transparent solution.As described above, titanium alkoxide is added to the acid solution and hydrolyzed. In addition to a method in which the titanium alkoxide and peptizing reaction proceed simultaneously, a method is also adopted in which titanium alkoxide is hydrolyzed in advance and then a predetermined amount of acid is added to peptize the titanium alkoxide.Furthermore,
The desired titanium oxide hydrosol can also be obtained when hetitanium alkoxide is added to a polysilicic acid solution that previously contains the acid required for peptization.

The acid used for peptization may be an organic acid or an inorganic acid, but mineral acids such as hydrochloric acid, nitric acid and sulfuric acid are preferred;
Room temperature is sufficient for the reaction temperature at that time.

Examples of the water- or acid-soluble metal salts include hatinium, zirconium, hafnium, germanium, tin, lead, aluminum, gallium, indium, thallium, scandium, yttrium, lanthanum, actinium,
Magnesium, calcium, strontium, barium, zinc, cadmium, mercury, copper, nickel, cobalt, iron, manganese, chromium and molybdenum chloride, nitrate, sulfate, oxychloride, oxysulfate, oxynitrate and organic Mention may be made of acid salts.

When the present invention is carried out by any of the methods from reaction (1) to reaction (2) above, the reaction temperature is preferably room temperature to 80°C;
A pure clay derivative can be obtained by washing and dehydrating the obtained reaction product according to a conventional method, if necessary.
Then, if necessary, it may be washed, and after dehydration if necessary, a water-fi7-soluble organic solvent such as methanol,
Any of ethanol, isopropyl alcohol, acetone, tetrahydrofuran, etc. can be used as a dispersion medium, and in this case, rapid drying is expected when formed into a film.

When forming a film, the reaction product is centrifuged, dehydrated, and then cast or coated on a Teflon mold or aluminum foil, or continuously spread using a doctor blade method or reverse roll method. By first drying with warm air, a flexible and dense film can be produced. Depending on the purpose of use, the obtained film may be heated to 300 to 800°C.

The clay derivative of the present invention can be obtained, for example, by reacting polyvalent metal oxide hydrosyl oxide with smectite in reaction (1), in which the concentration of the smectite suspension is 0.1 to 5 w.
/ma% (hereinafter simply expressed as %) is preferable, and the amount of silica-competitively oxidized polyvalent gold hydrosil added is (S i + Gold J!) as 5-40
In the case of 0 reaction (1) and reaction (2), where it is desirable to add the compound in millimole, it can be carried out in exactly the same manner.

It is clear from Example 1 that the clay derivative film obtained by the method of the present invention has a porous structure.

That is, the resulting clay derivative film had a large interlayer distance of 35λ and a large surface area of 420 m2/g.

[Effects of the Invention] The clay derivative membrane having a porous structure of the present invention obtained in this manner is extremely stable, and has high water resistance and heat resistance. Since it provides a sheet-like self-retaining film or coating, it is useful as an adsorption/separation film, a sensor coating, a catalyst support, an encapsulating agent, a heat insulating or heat-retaining sheet, and a breathable film.The film can also be multilayered to form an inorganic substrate. It can be used in a wide range of industrial applications, such as as an inorganic binder with a porous structure, and as a coating agent.

[Examples] The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples unless the gist thereof is exceeded.

Example 1 A mixed solution of 31 parts of ethanol and 2.5 parts of 2N hydrochloric acid was added to 10.4 g of silicone tetraethoxide and stirred at room temperature for 2 hours to obtain a solution of polysilicic acid. Separately, titanium tetraisopropoxide 1.4. was added to IN hydrochloric acid 201 and stirred for 30 minutes until the resulting white precipitate was dissolved to obtain a transparent sol. This sol was added to the previously prepared polysilicic acid solution and stirred at room temperature for 10 minutes to obtain a transparent silica/titanium oxide hydrosol. This sol was mixed with montmorillonite from Yamagata Prefecture (manufactured by Kunimine Industries, product name: Kunipia F).
Cation exchange capacity 100 milliequivalent 7100g) 5.0
The mixture was injected over 10 minutes with stirring into a solution of 6001 in water, and stirring was continued for 1 hour at 50°C.The reaction product was centrifuged, washed with water, and the resulting cake was stirred to obtain a clay derivative. A slurry was prepared. This slurry was coated on a glass plate and analyzed by X-ray diffraction after drying at room temperature. As a result, the interlayer distance of the clay derivative was 35A, and the specific surface area by nitrogen gas adsorption method was 420 layers and 27gΦ The clay derivative slurry was poured into a Teflon mold and then dried with warm air to obtain a film with a thickness of 60 Bm.

The resulting membrane was a translucent and flexible membrane.

Example 2 In Example 1, 18ml of ethanol, 0.8ml of water
A mixed solution of 1.01 g of silicone tetraethoxide and 0.5N nitric acid was added to 10.4 g of silicone tetraethoxide, and the mixture was stirred at 80° C. for 4 hours to obtain a solution of polysilicic acid. In addition, 10 ml of 0.5N nitric acid was used in place of 20 ml of 0.5N hydrochloric acid to obtain a transparent titanium oxide hydrosol. The following procedure was carried out in the same manner as in Example 1 to obtain a clay derivative reaction product liquid. Using a clay derivative slurry obtained by centrifuging and stirring this reaction product solution, a membrane prepared in the same manner as in Example 1 was heated at 500° C. for 1 hour. The resulting membrane was flexible.

Example 3 In Example 1, 1.51% of ethanol and 1.51% of 2N hydrochloric acid were added.
4NIj; if! A silica/titanium oxide hydrosol was prepared by adding 1.9 g of a 25 w/w % titanium tetrachloride solution diluted with No. 11.

This sol was mixed with sodium fluorine hectorite (Na+z
3Mga/3Li+z3Si40+oF2) 2.5g
The following procedure was carried out in the same manner as in Example 1 to obtain a flexible membrane.

Example 4 Organic silica sol (catalyst chemical industry type, trade name 09GAL-
1232, SiO2 content 31.4w/w%) 9.8g
zirconium oxychloride solution (ZrC1a as 2
0% content) was added and stirred at 40°C for 20 minutes to obtain silica-zirconia hydrosil. Using this sol, the same procedure as in Example 1 was carried out to obtain a flexible film. This membrane was immersed in water for one week, but it hardly swelled and maintained its original shape.

Example 5 In Example 1, a mixed solution of 31 ml of ethanol, 3.5 ml of water, and 11 ml of 0.5N hydrochloric acid was added to 10.4 g of silicon tetraethoxide, and the resulting polysilicic acid solution was stirred at 80°C for 90 minutes. 0 added to the suspension
Next, 4.1 g of 20 w/w% ferric chloride solution was added, and
Stir at 0°C for 1 hour, and proceed in the same manner as in Example 1.
A flexible, translucent brown film was obtained.

Claims (1)

[Scope of Claims] 1. A clay derivative film having a porous structure characterized by containing silica/polyvalent metal oxide hydrate between layers of smectite. 2. Silica consists of polysilicic acid, silica hydrosol, and organic silica sol obtained by hydrolyzing Si(OR)_4 [R represents a linear or branched alkyl group having 1 to 5 carbon atoms] A clay derivative membrane having a porous structure according to claim 1 selected from the group. 3. The polyvalent metal oxide is Ti(OR)_4 [R represents a linear or branched alkyl group having 1 to 5 carbon atoms] or by hydrolyzing it and then peptizing it with acid. A clay derivative membrane having a porous structure according to claim 1, which is selected from titanium oxide hydrosols. 4. The clay derivative membrane having a porous structure according to claim 1, wherein the polyvalent metal oxide is selected from water- or acid-soluble metal salts. 5. A method for producing a clay derivative film having a porous structure, characterized by using a clay derivative containing silica/polyvalent metal oxide hydrate between smectite layers. 6. A method for producing a clay derivative film having a porous structure according to claim 5, wherein the clay derivative is obtained by reacting a silica sol, a polyvalent metal oxide source, and smectite. 7. Silica sols are obtained from polysilicic acid, silica hydrosol and organic silica sol obtained by hydrolyzing Si(OR)_4 [R represents a linear or branched alkyl group having 1 to 5 carbon atoms] 7. A method for producing a clay derivative membrane having a porous structure according to claim 6, which is selected from the group consisting of: 8. The method for producing a clay derivative film having a porous structure according to claim 6, wherein the oxidized polyvalent metal source is selected from the group consisting of water- or acid-soluble polyvalent metal salts and titanium oxide hydrosol. 9. Titanium oxide hydrosol is obtained by hydrolyzing Ti(OR)_4 [R represents a linear or branched alkyl group having 1 to 5 carbon atoms] or by peptizing it with an acid. A method for producing a clay derivative membrane having a porous structure according to claim 8.