KR20200031354A - Ceramic membrane and method for preparing same - Google Patents

Abstract

The present invention relates to a ceramic membrane comprising only a support and a separation layer, and a manufacturing method thereof. According to the present invention, it is possible to increase a membrane filtration treatment amount.

Description

Ceramic membrane and its manufacturing method {CERAMIC MEMBRANE AND METHOD FOR PREPARING SAME}

The present invention relates to a ceramic film and its manufacturing method.

With the development of the industry, the harmful effects of harmful substances such as dust, soot, waste gas, smoke, and volatile organic chemicals (VOC's) generated in each industrial process are increasing. Therefore, in order to prevent the release of these pollutants, some polymer filters are used, but in the case of polymer filters, there are problems in heat resistance, chemical resistance, abrasion resistance and flame retardancy.

Therefore, ceramic filters have been developed to solve these problems. Ceramic filters have much better heat resistance, chemical resistance, and abrasion resistance than polymer filters. There is no need to save the installation cost and maintenance cost.

The existing ceramic membrane is composed of a three-layer structure of a support-intermediate layer-separation layer. The reasons for the presence of the intermediate layer are as follows. When the separation layer is dip-coated without an intermediate layer on the lag, the pore size of the support is larger than the particles forming the separation layer, and the separation layer particles penetrate all into the pores of the support to block the pores of the support and the separation layer is not formed. Because it is not. Therefore, an intermediate layer composed of medium-sized particles is coated on a support having the largest particles, and a separation layer composed of the smallest particles is coated thereon.

Korean Patent Publication No. 10-2010-0001482

An object of the present invention is to provide a ceramic film and a method of manufacturing the same.

An exemplary embodiment of the present invention includes coating a polymer or oligomer dissolved in a solvent in at least a portion of pores of a porous support; Forming a separation layer on the porous support coated with the polymer or oligomer; And removing the polymer or oligomer from the porous support by heat treatment.

Another embodiment of the present invention, a porous support; And a separation layer formed on the porous support, to provide a ceramic film prepared according to the method for manufacturing a ceramic film of the present invention.

The method of manufacturing a ceramic membrane according to an exemplary embodiment of the present invention is to prepare a ceramic membrane composed of only a support and a separation layer without an intermediate layer by infiltrating a polymer or oligomer dissolved in a solvent into the support, reducing process time and process cost, and preparing the above. The ceramic membrane produced by the method has an advantage of increasing the membrane filtration throughput by reducing the total permeation resistance because there is no intermediate layer.

1 illustrates a method of manufacturing a ceramic film according to an exemplary embodiment of the present invention.
Figure 2 illustrates a manufacturing method according to a comparative example of the present invention.
3 is an SEM image of a porous support before forming a separation layer according to an exemplary embodiment of the present invention.
4 is an SEM image of a porous support before forming a separation layer according to Example 1 of the present invention.
5 is an SEM image of a porous support after forming a separation layer according to Example 2 of the present invention.
6 is an SEM image of a porous support after forming a separation layer according to a comparative example of the present invention.

In the present invention, when a part is said to “include” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated.

Hereinafter, preferred embodiments of the present invention will be described. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

An exemplary embodiment of the present invention comprises the steps of coating the pores of at least a portion of the porous support with a polymer or oligomer in a solvent; Forming a separation layer on the porous support coated with the polymer or oligomer; And removing the polymer or oligomer from the porous support by heat treatment. In contrast, the above steps are schematically illustrated in FIG. 1. The coated polymer or oligomer prevents particles of the separation layer smaller than the pores of the porous support from penetrating into the pores of the porous support, so that a separation layer can be formed without forming an intermediate layer on the porous support. When the intermediate layer is formed, a lot of energy and cost are consumed, and the present invention can reduce it, thereby reducing the process time and cost. In particular, since the pores of the porous support are filled in a solution state, the pores of the porous support that can act as a capillary force can be effectively filled, thereby preventing a problem that the separation layer is not formed. The degree of filling of the pores can be confirmed by a scanning electron microscope (Scannig Electoron Microsope, SEM). In the case of a non-conductive material, for SEM imaging, conductivity may be imparted by plasma coating Pt particles for 180 seconds. Looking at the SEM image of Figure 4, it can be seen that by filling the pores of the porous support with an amorphous polymer, the size of the pores can be reduced.

In one embodiment of the present invention, the porous support is not limited thereto, and may be formed by heat-treating a ceramic precursor including a ceramic and a metal salt.

In another embodiment, the ceramic is a metal oxide; Metal borides; Metal carbides; And one or two or more selected from the group consisting of metal nitrides, but is not limited thereto.

As a specific example of the ceramic, aluminum oxide (Al ₂ O ₃ ); Aluminum oxide precursors; Yittria stabilized zirconia (YSZ); Scandia stabilized zirconia (ScSZ); Gadolinium doped ceria (GDC); Samarium doped ceria (SDC); Lanthanum Strontium Gallate Magnesite (LSGM); Nickel oxide (NiO); Copper oxide (CuO or Cu ₂ O); Titanium dioxide (TiO2); Spinel (MgAl ₂ O ₄ )); Mullite; Pyrophyllite; Silicon oxide (SiO ₂ ); Magnesium oxide (MgO); Iron oxide (Fe3O2, Fe2O3); Silicon carbide (SiC); And it may include one or two or more selected from the group consisting of nitrogen carbide (SiN). An example of the precursor of aluminum oxide is Boehmite (ALO (OH)), but is not limited thereto.

The metal salt includes salts of various metals commonly used in the art, such as nickel, copper, zirconium, yttrium, cerium, gadolinium, and a single metal salt or two or more polymetal salts can be used. Specifically, the multi-metal salts include nickel-nitrate hexahydrate, zirconyl-nitrate hydrate, and yttrium-nitrate hexahydrate. hexahydrate); Nickel-nitrate hexahydrate, gadolinium-nitrate hydrate, and cerium-nitrate hexahydrate; And copper-nitrate hexahydrate, gadolinium-nitrate hydrate, and cerium-nitrate hexahydrate. Combinations of multiple metal salts can be used, but the present invention is not limited to the use of multiple metal salts of these specific groups.

In one embodiment of the present invention, at least a portion of the metal salt may be reduced to metal by heat treatment.

The ceramic is 30% by weight to 80% by weight based on the entire porous support after the heat treatment, and the metal may be included by 20% by weight to 70% by weight.

In one embodiment of the present invention, the porous support has a plurality of pores, 30 to 70% by volume, preferably 30% by volume relative to the total volume of the support to facilitate the movement of materials such as fluids, gases It may have a porosity of 40 to 40% by volume.

The average diameter of the pores of the porous support may be 0.01 μm to 100 μm, preferably 0.1 μm to 50 μm, and more preferably 0.5 μm to 10 μm. Measurement of the size of the pores can be performed in the same manner as the method of measuring the pores of the separation layer, which will be described later.

In another exemplary embodiment, the pores of the porous support may serve as channels. The channel means a passage through which a fluid or gas material moves in the porous support.

In one embodiment of the present invention, the weight average molecular weight of the polymer may be 1,000MW to 10,000,000MW, preferably 10,000MW to 100,000MW. The MW means Molar Weight.

In an exemplary embodiment of the present invention, the weight average molecular weight of the oligomer may be 100MW or more and less than 100,000MW, preferably 500MW or more and 10,000MW or less. In the case of an oligomer, in the case of low molecular weight, it is in the form of a low-viscosity liquid, in the case of a high-molecular weight, in the form of a high-viscosity liquid, or in a solid form that is soluble in a solvent, it is easy to fill the pores of the porous support. In the present specification, the oligomer is regarded as a low molecular weight when the weight average molecular weight is 10,000 MW or less, and is considered as a high molecular weight when it is more than 10,000 MW. The high molecular weight can be measured by Gel Permeation Chromatography (GPC) method.

In one embodiment of the present invention, the solvent may use a solvent for conventional coating, specifically, water, tetrahydrofuran (THF), isopropyl alcohol, normal propyl alcohol, ethanol, methanol, normal Ketone-based solvents such as butyl acetate, toluene, hexane, ethyl acetate, and acetone, α-terpineol, or a mixture thereof may be used, preferably water, tetrahydrofuran (THF) You can. However, the use of the solvent is not limited to those specified above, and a suitable solvent may be used in accordance with solubility and compatibility with the polymer or oligomer used.

The solubility and compatibility with the polymer or oligomer is determined by a method of visual observation or a method using a solubility parameter. First, as a method of observing with the naked eye, a mixture of a solvent and a polymer or an oligomer is stirred, and then, the turbidity (or transparency) and viscosity of the solution are observed with the naked eye. At this time, the transparency of the solution increases and the viscosity increases as the compatibility of the polymer or oligomer with a good solvent increases. As a method using the solubility parameter, a Hildebrand solubility parameter or a Hansen solubility parameter can be used. Ideally, the difference between the Hildebrand solubility parameter of the polymer and the solvent is 0.5 or less.

In addition, the Hansen solubility parameter divides the term of the cohesive energy of the Hilderbrand solubility parameter by the type of interaction energy that works between molecules of each substance, so that the dissipation force term (δ _d ), the dipole force term (δ _p ), and hydrogen It is represented as a binding force term (δ _h ). For example, the compatibility of the polymer (1) and the solvent (2) can be defined using R _a (solubility sphere or interaction sphere). The R _a can be defined as in Equation 1 below.

[Equation 1]

R _a ² = 4 (δ _d2 -δ _d1 ) ² + (δ _p2 -δ _p1 ) ² + (δ _h2 -δ _h1 ) ²

In Equation 1, δ _d1, δ _d2 , δ _p1 , δ _p2, δ _h1, and δ _h2 are the dispersion force terms (δ _d ), the dipole spacing term (δ _p ), and the hydrogen bonding force, respectively, of the polymer (1) and the solvent (2). Term (δ _h ). By substituting R _a value obtained from Equation 1 into Equation 2 below, the relative energy difference between the polymer (1) and the solvent (2) system can be obtained.

[Equation 2]

RED = R _a / R ₀

The RED represents a relative energy difference (Relative Energy Difference), R _a is a value calculated in the formula 1, R ₀ corresponds to an eigenvalue of each polymer. At this time, the RED value should be less than 1, and the smaller the difference, the higher the solubility and compatibility.

The concentration of the polymer or oligomer dissolved in the solvent is 0.01 wt% to 100 wt%, preferably 1 wt% to 10 wt%. The concentration is calculated as (mass of polymer or oligomer / mass of solvent). When partially filling the pores of the porous support, a high concentration solution close to 100 wt% is used to fill almost all of the low concentration. When the pores are partially filled, it is easy to remove, and when almost all of them are filled, pores of the support can be made small to prevent the separation of particles of a size much smaller than the support from penetrating into the support. Depending on the type of polymer, it is possible to determine what concentration of solution to use.

In one embodiment of the present invention, the polymer or oligomer may be a thermoplastic resin. The thermoplastic resin means a resin having deformable properties, that is, plasticity, when heated and heated again after molding.

In one embodiment of the present invention, but not limited to, the thermoplastic resin is polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), polystyrene (PS) polyvinylidene fluoride (PVDF), polyethylene ( PE), polypropylene (PP), polyethylene phthalate (PET), polyimide (PI), polyamide (PA), and polyethylene oxide (PEO). Since the thermoplastic resin is dissolved in a solvent, the pores of the porous support can be coated without changing the state of the thermoplastic resin from liquid to solid or solid to liquid.

In one embodiment of the present invention, the polymer or oligomer may be a thermosetting resin. The thermosetting resin refers to a resin that has deformable properties when the reaction proceeds during heating and molding, that is, plasticity, but does not cause plasticity even after curing by heating in an insoluble or insoluble state after molding.

In one embodiment of the present invention, but not limited to, the thermosetting resin is silicone resin, amino resin, epoxy resin and polyurethane, acrylic resin, phenol resin, urea resin, melamine resin, polyester resin, alkyd resin It may include one or more selected. When a thermosetting resin is used, it is thermally decomposed directly from a solid to a gas without a phase change from a solid to a liquid, and because it is a crosslinked polymer, it does not dissolve in an organic solvent or an aqueous solvent, but only swelling occurs. It is not damaged. As a result, there is an advantage that the solvent can be used universally regardless of the type.

In one embodiment of the present invention, the step of coating the oligomer dissolved in the solvent in at least a portion of the pores of the porous support may further include curing the coated oligomer.

More specifically, in one embodiment of the present invention, the step of coating the oligomer dissolved in the solvent of at least a portion of the pores of the porous support is coated with an oligomer of a thermosetting polymer dissolved in a solvent, and then the coated thermosetting oligomer is Curing may further include a step.

Specifically, in one embodiment of the present invention, the polymer or oligomer coating is preferably 1 time or more and 10 times or less, preferably 1 time or more and 2 times or less, and more preferably 1 time. When the number of coatings increases as described above, the penetration depth in the pores of the porous support of the polymer or oligomer and the thickness of the polymer or oligomer layer on the surface of the porous support increase within a range in which the step of removing the separate polymer or oligomer layer is not required. There is an advantageous effect in forming a separation layer without an intermediate layer.

In one embodiment of the present invention, the thickness of the polymer or oligomer layer on the surface of the porous support may be less than 10 μm and less than 1 μm. When the polymer or oligomer layer in the above range is formed, it is not necessary to remove the polymer or oligomer layer to form a separation layer. To this end, the concentration of the solution and the number of coatings can be adjusted. The preferred concentration range of the solution is 1 wt% to 10 wt%, and the number of coating times may be most preferably one or less.

In one embodiment of the present invention, the step of coating the pores of the porous support may use methods such as spin coating, dip coating, inkjet printing, gravure printing, spray coating, doctor blade, bar coating, gravure coating, brush painting, etc. Can be used, preferably dip coating. The deep coating step may be repeated once or multiple times to perform deep coating.

When manufactured by dip coating as described above, due to the relatively simple process, there is an economical advantage in time, cost and / or process.

In one embodiment of the present invention, the coating time may vary depending on the type of the polymer or oligomer, solvent, concentration, viscosity and thickness of the porous support, for example, 600 seconds / times or less, preferably 60 seconds / time Times.

In one embodiment of the present invention, the step of drying the porous support coated with the polymer or oligomer may be included before the step of forming the separation layer. The drying step may be performed by appropriately selecting a known drying method selected from spray drying, tray drying, freeze drying, solvent drying, and flash drying.

In an exemplary embodiment of the present invention, a step of removing a portion of the polymer or oligomer layer on the surface of the porous support may be included before forming the separation layer. This is because if the polymer or oligomer layer on the surface of the porous support is formed too thick, the separation layer particles may peel off from the porous support during heat treatment. However, the polymer or oligomer layer is described above As 10㎛ If less, the removal step may not be necessary.

In an exemplary embodiment of the present invention, the separation layer may include, but is not limited to, a silica material, an organic-containing amorphous silica material, or a carbonaceous material as the outermost layer. Specifically, it is preferable that the separation layer includes at least one of Si, Ti, Zr, and Al. This makes it possible to make the separation layer a ceramic member such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZrO ₂ , zeolite, mullite, and mixtures thereof, and all membranes made of these materials have separation performance. At the same time, it can have high acid resistance.

In one embodiment of the present invention, the separation layer may be formed by a sol-gel method, a CVD method, a sputtering method, or the like.

In one embodiment of the present invention, the formation of the separation layer may be achieved by the coating method. More specifically, the separation layer particles in the dispersion medium It can be achieved by dip coating the dispersed dispersion. At this time, the dispersion medium is preferable as the compatibility with the polymer or oligomer is poor, and the above-described method may be used for judgment.

In an exemplary embodiment of the present invention, the thickness of the separation layer may be 1 nm to 500 μm, preferably 100 nm to 100 μm, more preferably 1 μm to 40 μm. The thickness of the separation layer was confirmed through a SEM cross-sectional photograph.

In one embodiment of the present invention, the separation layer may be porous having pores, and the average diameter of the separation layer pores may be 0.01 nm to 10 μm, preferably 0.1 nm to 100 nm. The pore size can be measured using a method of mercury intrusion porosimetry, liquid liquid displacement or capillary flow porometer. That is, while sequentially changing the pressure of the unreacted inert gas, a wetting medium that wets the porous ceramic membrane corresponding to the sample is penetrated into the porous ceramic membrane pores or extruded. In this process, the pressure at a specific point, the weight of the medium, and the gas flow rate are recorded. Thereafter, the size of the pores can be calculated using the Laplace equation (ASTM, F316-03, Standard test methods for pore size characteristics of membrane filters by bubble point and mean flow pore test). In the embodiment of the present invention, the pore size measured by the mercury impregnation method was used. In addition, the pore size of the surface of the ceramic film can be confirmed by SEM, and the pore size can be reversely calculated in the Hogen-Poisseuille equation by calculating the permeability through which the fluid (liquid or gas) penetrates the ceramic film at a constant pressure.

Removal in the present invention means that the coated polymer or oligomer is burned and disappeared by heat treatment.

The heat treatment means treating at a temperature higher than room temperature.

In one embodiment of the present invention, the heat treatment temperature is 400 ° C to 2500 ° C, 800 ° C to 1500 ° C, and the heat treatment time may be 30 minutes or more and 10 hours or less, preferably 1 hour or more and 5 hours or less. The heat treatment is heat-treated at a temperature of 400 ° C. or higher, and as the components of the coated thermosetting resin are removed, sintering of the separation layer starts, and heat treatment at a temperature of 2500 ° C. or lower causes excessive sintering, resulting in the porous support and separation layer. Can prevent the internal pores from disappearing.

In the present invention, sintering means a phenomenon in which when the heat treatment is performed at a constant temperature, particles of the porous support or particles of the separation layer are brought into close contact with each other and harden.

In order to form the intermediate layer, an energy costly firing process is required, but the manufacturing method according to an exemplary embodiment of the present invention has an effect of reducing process time and process cost since there is no step of forming the intermediate layer.

As an exemplary embodiment of the present invention, a ceramic film manufactured according to the above manufacturing method is provided.

As a specific embodiment of the present invention, the ceramic membrane may be composed of only a support and a separation layer without an intermediate layer. Through this, the total permeation resistance is reduced, and the membrane filtration throughput of the ceramic membrane can be increased.

Hereinafter, examples will be described in detail to specifically describe the present invention. However, the embodiments according to the present invention may be modified in various other forms, and the scope of the present invention is not interpreted to be limited to the embodiments described below. The embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art.

<Preparation of porous support>

A porous support made of 100 wt% of alumina of 5 μm size having a pore size of 2 μm was prepared. Subsequently, the porous support was subjected to plasma coating of Pt particles for 180 seconds, and the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 3.

<Example 1>

An oligomer and a curing agent are mixed with the porous support (Devon, two-part 5min epoxy dissolved in acetone at 1 wt%), dissolved in a solvent, dip coated and cured. Thereafter, the porous support was subjected to plasma coating of Pt particles for 180 seconds, and the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 4. As a result of the observation, it was confirmed that the voids between the particles of the porous support were filled.

<Example 2>

The porous support of Example 1 of the Al ₂ O ₃ particles having a size of 100 ㎚ The porous support was immersed for 2 minutes using a dispersion (Al ₂ O ₃ solid content of 18 wt%) as an aqueous dip coating solution, and then lifted at a constant rate of 1 mm / sec to perform dip coating. Thereafter, after drying in an oven, a separation layer was formed by heat treatment at 1000 ° C. for 1 hour or more. The manufacturing process from Example 1 to Example 2 is schematically illustrated in FIG. 1. Thereafter, the porous support was subjected to plasma coating of Pt particles for 180 seconds, and the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 5. As a result of the observation, it was confirmed that there were no cracks or the like on the surface of the porous support, and the particles of the separation layer did not penetrate into the pores of the porous support. That is, it was confirmed that the separation layer was well formed.

<Comparative Example 1>

A separation layer was formed in the same manner as in Example 2 without the porous support. This manufacturing process is schematically shown in FIG. 2. Subsequently, the porous support was subjected to plasma coating of Pt particles for 180 seconds, and the cross-section and surface of the porous support were observed using SEM, and the corresponding SEM image is shown in FIG. 6.

As a result of the observation of Comparative Example 1, cracks were generated on the surface of the porous support, and it was confirmed that the separation layer particles penetrated into the pores of the porous support and decreased the porosity of the porous support. In addition, that the separation layer particles penetrated into the pores of the porous support means that the separation layer was not evenly formed.

Through the SEM image of Example 1, it was confirmed that the pores of the porous support can be filled with a polymer or oligomer, and the separation layer without filling the pores of the porous support with a polymer through the SEM image of Example 2 and Comparative Example 1 It was found that the particles penetrated into the pores of the porous support and were difficult to form.

In addition, through the SEM image of Example 2, it was confirmed that the polymer or oligomer filling the pores of the porous support can be removed by heat treatment, which means that it does not adversely affect the permeability.

Claims (10)

Coating at least a portion of the pores of the porous support with a polymer or oligomer dissolved in a solvent;
Forming a separation layer on the porous support coated with the polymer or oligomer; And
Method of manufacturing a ceramic membrane comprising the step of removing the polymer or oligomer from the porous support by heat treatment. According to claim 1,
The polymer or oligomer is a method for producing a ceramic film that is a thermoplastic resin. According to claim 2,
The thermoplastic resin is polyvinyl chloride (PVC), polyvinylpyrrolidone (PVP), polystyrene (PS) polyvinylidene fluoride (PVDF), polyethylene (PE), polypropylene (PP), polyethylene phthalate (PET), A method of manufacturing a ceramic membrane comprising at least one selected from polyimide (PI), polyamide (PA) and polyethylene oxide (PEO). According to claim 1,
The polymer or oligomer is a method for producing a ceramic film that is a thermosetting resin. The method of claim 4,
The thermosetting resin is a silicone resin, amino resin, epoxy resin and polyurethane, acrylic resin, phenol resin, urea resin, melamine resin, polyester resin, and a method of manufacturing a ceramic film comprising at least one selected from alkyd resin. According to claim 1,
The method of coating the oligomer in which at least a portion of the pores of the porous support are dissolved in a solvent further comprises curing the coated oligomer. According to claim 1,
The polymer has a weight average molecular weight of 1,000MW to 10,000,000MW and a weight average molecular weight of the oligomer is 100MW or more and less than 100,000MW. According to claim 1,
The concentration of the polymer or oligomer dissolved in the solvent is 0.01 wt% to 100 wt%. According to claim 1,
A method of manufacturing a ceramic film, wherein the coating of the polymer or oligomer is performed once or more and 10 times or less. Porous support; And a separation layer provided on one surface of the porous support, wherein the ceramic membrane produced by the manufacturing method according to any one of claims 1 to 9.

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