JP4461298B2 - Process for producing inorganic and organic-inorganic hybrid coatings - Google Patents

Description

  The present invention relates to a novel process for producing inorganic and organic-inorganic hybrid coatings.

As inorganic-type and organic-inorganic hybrid-type coating materials used for the above-mentioned applications, those having a composition having a polymetalloxane bond such as polysiloxane have been well known. It is used in the form of coating of the inner surface of the porous material.
For inorganic and organic-inorganic hybrid coatings on planar materials, a relatively simple coating preparation method is known by applying a reaction solution, a dipping method, a spin method, and the like (for example, Patent Documents 1 and 2). .
On the other hand, the coating on the inner surface of the porous material, as represented by the silane coupling reaction, allows a dilute reaction solution in which the low molecular weight substance is dissolved to penetrate into the inside of the member so that the low molecular weight substance, the surface site, In general, a method of causing a molecular level reaction is required, and it takes a long time to increase the thickness of the manufacturing process, particularly the coating layer.

JP-A-6-328037 JP 2002-536630 A

A microscopic region rich in inorganic and organic-inorganic hybrid polymers produced in the reaction solution by phase separation preferentially wets and spreads on the inner surface of a nearby member, thereby forming a uniform coating.
The phenomenon in which a liquid wets and spreads on the surface of a specific material to form a uniform film is generally known as wetting transition, but in the present invention, the reaction solution causes uniform wetting transition on the inner surface of the porous body. After spreading, the gelation occurs to form a stable coating film.
In general, an inorganic porous material such as silica gel and an organic-inorganic hybrid containing a siloxane bond are produced by a sol-gel method which is a liquid phase reaction. As is well known, the sol-gel method is based on an inorganic low molecular weight compound having a hydrolyzable functional group as a starting material, and a sol-gel reaction, that is, hydrolysis and subsequent polymerization (polycondensation) reaction. The general method for finally obtaining an oxide aggregate or polymer from an inorganic low molecular weight compound. Metal alkoxides are the most well-known inorganic low-molecular compounds used as starting materials. In addition, metal salts or coordination with hydrolyzable functional groups such as metal chlorides, carboxyl groups and β-diketones. Examples of the compound include metal amines.

  An object of the present invention is to provide a new production method capable of producing inorganic and organic-inorganic hybrid coatings on the inner surface of a porous member, or in a microfabricated groove-like channel or capillary.

In producing inorganic and organic-inorganic hybrid coatings by the sol-gel method, the present inventor made the sol-gel transition that solidifies the reaction liquid and the wetting transition to the interface based on the phase separation occur simultaneously. By selecting a condition in which the characteristic length of the multiphase structure interface that spontaneously develops by phase separation is larger than the pore diameter of the porous member serving as the coating substrate and the width of the microfabricated groove-shaped flow path, We found that the objective was achieved.
Thus, according to the present invention, there is provided a method for producing inorganic and organic-inorganic hybrid coatings on the surface of the pores of a porous member and the surface of a finely processed groove.
Specifically, the present invention relates to a hollow member or porous material having a size limited in at least one dimension so that wetting transition to the interface based on phase separation and sol-gel transition for solidifying the reaction liquid occur simultaneously. This is a method for producing inorganic and organic-inorganic hybrid coatings formed on the inner wall of a material member.
Here, examples of the hollow member include a thin plate-like space sandwiched between sufficiently wide flat plates, a finely processed groove-like flow path, and a sufficiently long cylinder (in a capillary tube). The porous member is a member having continuous through holes connected in a network, for example.
Note that the size of at least one dimension is limited. The porous member or the hollow member has a pore diameter of 0.1 to 100 microns, preferably 0.5 to 40 microns, and a thickness of 2 to 10000 nanometers, preferably It is in the range of 10 to 5000 nanometers.
In addition, the wetting transition of the present invention means that, for example, when a gel is formed by filling a sol having a composition with a diameter of 10 μm or more into a capillary having a diameter of 10 μm, an entangled structure is not formed and a uniform thickness is formed on the capillary inner surface. This is a phenomenon in which silica gel is coated.

  According to the present invention, inorganic and organic-inorganic hybrid coatings can be produced on the inner surface of a porous member, or in a microfabricated groove-like channel or capillary.

The principle of the present invention is applied to various inorganic and organic-inorganic hybrid compounds known to be able to produce inorganic or organic-inorganic hybrid polymers from low-molecular compounds by the sol-gel method as described above. However, the method of the present invention is particularly preferably applied when the inorganic and organic-inorganic hybrid polymers constituting the porous body are silica and / or organic functional group-containing siloxane polymers. is there.
In order to produce a uniform coating consisting of a silica or siloxane polymer according to the present invention, on the surface of a porous member or a finely processed groove-like flow path, the sol-gel reaction step is performed at least in the initial stage of the reaction in the acidic region, In addition, the reaction conditions are adjusted so that the amount of water containing the catalyst component in the sol-gel reaction is in the range of 2.0 to 40.0 g with respect to 1.0 g of silica in the reaction system (as an anhydrous silica equivalent weight). As a result, sol-gel transition and phase separation occur simultaneously, and a gel composed of a solvent-rich phase and a skeletal phase is produced.
Thus, in order to produce a uniform coating on the surface of a porous member or a microfabricated groove-like channel according to the method of the present invention, first, a component that induces phase separation in an aqueous solution containing a sol-gel reaction catalyst component is added. Dissolve to prepare a homogeneous solution. When an inorganic low molecular weight compound having a hydrolyzable functional group is added to this homogeneous solution and a sol-gel reaction is performed, a gel that separates into a solvent-rich phase and a skeleton phase is generated as described above.
In the present invention, the porous member to be coated, the micro-processed groove-like flow path, or the contents of the capillary does not need to have double pores. The process is not essential.

  In the method of the present invention, a substance used as a component for inducing phase separation is preferably a cationic interface including a hydrophilic part such as a quaternary ammonium salt and a hydrophobic part mainly composed of an alkyl group in an amphiphilic substance. A surfactant comprising an activator or a nonionic surfactant, or a block copolymer having a hydrophilic part and a hydrophobic part. Specific examples thereof include alkyl ammonium halides, polyoxyethylene alkyl ethers, ethylene oxides A propylene oxide-ethylene oxide block copolymer may be mentioned, but is not limited thereto. Water-soluble polymers such as polyethylene oxide, polyacrylic acid, polyvinyl alcohol, polyacrylamide, polyvinyl pyrrolidone, polyoxazoline, polyethyleneimine, polyallylamine, and the like can also be preferably used. In addition, relatively low molecular weight compounds such as formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, ethylene glycol, diethylene glycol, triethylene glycol In addition, polymers with higher degree of polymerization, monocarboxylic acids such as glycerin, formic acid and acetic acid, dicarboxylic acids such as phthalic acid, maleic acid and oxalic acid, tricarboxylic acids such as citric acid, ethylene carbonate, propylene carbonate, etc. It can be suitably used for the purpose of separation induction. The substance that induces phase separation used in the present invention is preferably a substance that uniformly dissolves in the reaction solution, such as a surfactant, the above-mentioned block copolymer, and a water-soluble polymer.

  In addition, as the inorganic low molecular weight compound having a hydrolyzable functional group used in the present invention, various metal compounds including the metal alkoxide as described above can be applied, but a particularly preferable embodiment of the present invention. Accordingly, in the case of producing a porous body composed of silica, a silicon alkoxide monomer and a low molecular weight polymer (oligomer) are preferably used as the silica source.

The hybrid column also includes an organometallic compound having a hydrolyzable functional group, a non-hydrolyzable organic functional group and a hydrolyzable functional group bonded via at least one metal / carbon bond. It can be prepared by hydrolyzing and polymerizing an organometallic compound to gel the reaction solution system, then removing unnecessary substances in the gel and heating.
Here, the capacity of the organometallic compound containing a non-hydrolyzable organic functional group and a hydrolyzable functional group bonded via at least one metal / carbon bond is an organic compound having a hydrolyzable functional group. It is preferably 1/10 or more of the capacity of the metal compound.
In addition, as an organometallic compound containing a non-hydrolyzable organic functional group and a hydrolyzable functional group bonded through at least one metal / carbon bond, for example, methyltrimethoxysilane, ethyltrimethoxysilane, vinyl Trimethoxysilane, γ-glyoxydoxypropyltrimethoxysilane, γ-glyxidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltri Methoxysilane, N-β (aminoethyl) γ-aminopropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxy Silane can be used.
In the case of producing a porous body composed of an organic functional group-containing siloxane polymer (organic / inorganic hybrid), a single silicon alkoxide containing at least one silicon-carbon bond is used as such an organic / inorganic hybrid source. Polymers having a structure in which one or more carbons are bridged between two or more silicon atoms (bistrialkoxysilylalkanes) can be used.
The inorganic porous material of the present invention can also be produced by combining silica and an organic functional group-containing siloxane polymer.

  Examples are given below to further clarify the features of the present invention, but the present invention is not limited to these Examples.

Example 1
<Coating on the inside of porous member>
(1) Production of porous member with continuous through-holes connected in a network shape 1Molar aqueous nitric acid solution 3.370g and formamide (FA) 6.916g are mixed, and 10mL of methyltrimethoxysilane (MTMS) is MTMS under ice cooling. The mixture was mixed so that: FA: H2O = 1: 2.2: 2.5, stirred for 5 minutes, and gelled in a constant temperature bath at 40 ° C. Aging was performed for at least 24 hours after gelation, followed by drying for about 45 hours. Thereafter, it was washed with ethanol and dried at 40 ° C.
(2) Preparation of coating Obtained by mixing tetramethoxysilane (TMOS), formamide (FA) and 1 molar aqueous nitric acid solution so that the molar ratio of TMOS: FA: H2O = 1: 2.3 to 2.5: 1.5 The porous member was immersed in the reaction solution, introduced into the macropores, gelled at 40 ° C. and dried.
FIG. 1 (a), FIG. 2 (a) and FIG. 3 (a) are silica gels having a phase-separated structure having the above composition formed without being included in a porous member. FIG. 1 (b), FIG. 2 (b) and FIG. 3 (b) show the gel formed on the inner surface of a porous member having continuous through holes connected in a network. As shown in the figure, a coating layer was formed on the inner wall surface of the porous body.

(Example 2)
<Coating on the inner wall of the capillary>
A composition giving a domain size larger than the capillary diameter was selected, and a gel was prepared in a capillary having an inner diameter of 10 microns.
Methyltrimethoxysilane (MTMS), formamide (FA), and 1 molar nitric acid aqueous solution are mixed at a molar ratio of MTMS: FA: H2O = 1: 2.2 to 2.4: 2.5, and the resulting reaction solution has an inner diameter of 10 A micron capillary was immersed to introduce the solution into the capillary, gelled at 40 ° C. and dried. As shown in the figure, a coating layer was formed on the inner wall surface of the capillary.
FIGS. 4 (a), 5 (a) and 6 (a) are organic-inorganic hybrid gels having a phase separation structure formed with the above composition without being placed in a capillary. FIGS. 4 (b), 5 (b) and 6 (b) are organic-inorganic hybrid coatings in which this gel is formed on the inner wall of a capillary having an inner diameter of 10 microns. The dotted line shown in the figure is the original inner wall of the capillary, and it can be seen that it is coated with the thickness shown in the figure.

(Example 3)
<Evaluation in the normal phase of the column coated inside the porous member>
First, a porous member having continuous through holes was prepared in a capillary having an inner diameter of 200 μm by the method shown in Example 1 (TMOS: FA: H2O = 1: 2.3: 1.5), and normal phase evaluation was performed (FIG. 7). ). Next, a coating was prepared by the method shown in Example 1, and normal phase evaluation was performed (FIG. 8).
The mobile phase used for the evaluation was hexane / 2-propanol = 98/2 (v / v), and the samples used were ruene, dinitrotoluene and dinitrobenzene from the first peak. The retention ratio of dinitrotoluene is reduced from 0.29 to 0.16 by the coating. This indicates that the first prepared host gel has a methyl group-rich surface, and the decrease in this value indicates that the influence of the methyl group has disappeared due to the coating. The retention ratio of dinitrobenzene increased from 0.81 to 3.29. The retention ratio value after coating shows the same value as when evaluating an ordinary porous silica column, and this value and the large increase in retention ratio before and after coating increased the surface area by coating. This shows that a new porous silica surface was formed on the host gel.
Furthermore, an increase in column back pressure from 1.6 kgf per 100 mm to 2.2 kgf indicates that the through-pore diameter is decreasing, indicating that the coating is achieved with a thickness of several micrometers.
As a result of SEM observation, in spite of the porous gel formed in the space of 200 μm, the gel did not shrink at all, and very good performance as a column was obtained.

  The porous member having a coating produced by the production method of the present invention comprises a chromatography filler, a porous body for blood separation, a porous body for a hygroscopic agent, a porous body for low molecular weight adsorption such as deodorant, an enzyme carrier and a catalyst. It is suitably used for producing a porous body for a carrier. In addition, the microfabricated groove-like flow path in which the coating is produced by the production method of the present invention is suitably used for a fine space chemical reaction device.

The figure which shows the scanning electron micrograph of the coating obtained by evaporating and removing a solvent after a sol-gel reaction process in Example 1 (TMOS: FA: H2O = 1: 2.3: 1.5). The figure which shows the scanning electron micrograph of the coating obtained by evaporating and removing a solvent after the sol-gel reaction process in Example 1 (TMOS: FA: H2O = 1: 2.4: 1.5). The figure which shows the scanning electron micrograph of the coating obtained by evaporating and removing a solvent after a sol-gel reaction process in Example 1 (TMOS: FA: H2O = 1: 2.5: 1.5). The figure which shows the scanning electron micrograph of the coating obtained by evaporating and removing a solvent after the sol-gel reaction process in Example 2 (MTMS: FA: H2O = 1: 2.2: 2.5). The figure which shows the scanning electron micrograph of the coating obtained by evaporating and removing a solvent after a sol-gel reaction process in Example 2 (MTMS: FA: H2O = 1: 2.3: 2.5). FIG. 3 is a scanning electron micrograph of the coating obtained by evaporating and removing the solvent after the sol-gel reaction step in Example 2 (MTMS: FA: H 2 O = 1: 2.5: 2.5). Liquid chromatogram using the porous member before coating obtained in Example 1 Liquid chromatogram using the coated porous member obtained in Example 1

Claims (1)

A reaction process in which a sol having a composition with a diameter equal to or larger than the inner diameter of a hollow member or porous member is filled in the member, and wetting transition to the interface based on phase separation and sol-gel transition for solidifying the reaction liquid occur simultaneously. A method of producing an inorganic and organic-inorganic hybrid coating formed on the inner wall of a hollow member or porous member having a size limited in at least one dimension , wherein the reaction step is performed at least at the initial stage of the reaction. In the sol-gel reaction, the amount of water containing the catalyst component is 2.0 to 40.0 g with respect to 1.0 g of silica in the reaction system (as an anhydrous silica equivalent weight). A method for producing inorganic and organic-inorganic hybrid coatings characterized by adjusting the conditions .

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