KR102433159B1 - Novel camphene/photopolymer solution as pore-forming agent for photocuring-assisted additive manufacturing of porous ceramics - Google Patents

Abstract

The present invention relates to a novel campin/photopolymer solution-based photocurable ceramic slurry composition for manufacturing a porous ceramic support and a 3D printing technology using the same.
The present invention uses a campin/photopolymer solution, optimizes the components and content of the photocurable ceramic slurry composition, and prepares the slurry composition at room temperature without a separate heating process. have an advantage

Description

Novel camphene/photopolymer solution as pore-forming agent for photocuring-assisted additive manufacturing of porous ceramics

The present invention relates to a novel campin/photopolymer solution-based photocurable 3D printing technology for manufacturing porous ceramics.

Starting with polymers that have good chemical reactivity and low melting points, which are easy to process, 3D printing technology using metal or ceramic materials has been developed. The 3D printing technology using the ceramic material not only simplifies the manufacturing process because the existing mold manufacturing is unnecessary, but also brings a new manufacturing process paradigm that can be manufactured for each individual.

Ceramic materials, unlike other materials, have high chemical stability and high melting point, so expensive processes and equipment are required to directly apply them to 3D printing technology, so various methods have been developed to solve this problem. This method is mainly in the form of ceramic powder, which is dispersed in a material that is easy to make a shape, has a shape, and then removes the components except for the ceramic by the same method as heat treatment, and then undergoes a sintering process at high temperature to obtain a final product.

Through the implementation of pores connected to each other in the ceramic structure, physical properties that can be applied to various fields such as ion batteries, filters, catalyst supports, drug delivery systems and biomaterials are provided. For this purpose, easy-to-remove freezing media are mainly used. These include water, tert-butyl alcohol, and campin, and when these substances are cooled from a liquid state, they form solid crystals and push out substances other than the main substance, and are removed after the molding process to form pores. In particular, the campin can form dendrites to realize three-dimensionally connected pores, and can be easily removed even at room temperature and pressure due to its high vapor pressure.

3D printing of ceramics using photocuring is a method of laminating a ceramic slurry layer by layer and curing it by irradiating light according to the design. Typically, there are stereolithography (SLA) and digital light processing (DLP) methods. The DLP method cures one layer at a time to have high resolution and high printing speed.

In the past, the University of Michigan abroad made campin into a liquid by applying heat, and for a composition based on a freezing medium containing monomers and a photocuring initiator, the campin was solidified at room temperature and sublimated to form porous polymers and ceramics. was prepared (Non-Patent Document 1).

However, since campin has a melting point of about 50°C, a temperature above the melting point is essential when using campin as a solvent or applying it to a freezing medium.

Specifically, the existing methods for manufacturing porous ceramics using a cam pin are different materials using a ball-milling equipment, etc. that can continuously apply heat to a solid cam pin at room temperature to maintain it as a liquid for shape manufacturing. After preparing a slurry in which they were evenly dispersed, and fixing the shape of the slurry using a mold, etc., the campin had to be solidified.

Even in the latest porous ceramic 3D printing technology in which a photocurable slurry containing campin is applied as a pore agent, heat must be applied to the slurry containing campin until just before the tape casting method is used to form a thin film shape. If the temperature of the printing bed is low, the campin may solidify before casting is completed, and the layer may not be formed properly. Therefore, the temperature of the printing bed also needs to be controlled.

In addition, since the campinne has a relatively high vapor pressure even at room temperature, there may be component loss when maintained at a high temperature.

1. Journal of Materials Science, 47(16), 6166-6178, Journal of the American Ceramic Society, 95(12), 3763-3768.

The present invention optimizes the components and content of the photocurable ceramic slurry composition, and prepares the slurry composition at room temperature without a separate heating process. aims to provide

The present invention comprises the steps of preparing a campene / photo-curable monomer solution by mixing a campene (Camphene) and a photo-curable monomer at 20 to 30 °C;

It provides a method for preparing a photo-curable ceramic slurry composition, comprising the step of preparing a photo-curable ceramic slurry composition by mixing the campin / photo-curable monomer solution, ceramic powder, dispersant, and photo-curing initiator.

In addition, the present invention is prepared by the above-described manufacturing method,

Camphene, a photocurable monomer, a ceramic powder, a dispersant and a photocurable initiator,

At 20 to 30°C, Campin provides a photocurable ceramic slurry composition that is present in the liquid phase in the composition.

In addition, the present invention comprises the steps of forming a ceramic slurry layer for 3D printing by applying the above-described photocurable ceramic slurry composition to a 3D printing bed;

forming a ceramic structure by photo-curing into a pre-designed shape after inducing solidification of the campin;

forming a porous ceramic structure in which micropores are formed by freeze-drying the ceramic structure; and

It provides a method of manufacturing a three-dimensional porous support having a three-dimensionally connected micro-pore structure, comprising the step of heat-treating the porous ceramic structure at a high temperature.

In addition, the present invention provides a three-dimensional porous support having a three-dimensionally connected micro-pore structure prepared by the above-described manufacturing method.

The photo-curable ceramic slurry composition according to the present invention enables the production of personalized products of porous ceramics having a complex shape with a computer-based three-dimensional drawing without a separate mold manufacturing process.

In addition, in the present invention, the entire process from filling the syringe with the slurry to the production of a green body (structure) having a shape is automated, and since the solidified slurry acts as a supporter, there is no need for a separate supporter. It is possible.

In addition, the present invention uses campin as a pore agent and optimizes the components and content of the photocurable ceramic slurry composition, so that the slurry composition can be manufactured at room temperature without a separate heating process, so the manufacturing process of the slurry composition is simple and the process process It has the advantage of low component loss. In addition, since the temperature at which the campin of the slurry is phase-separated to form a solid crystal can be controlled by various factors, the process temperature can be adjusted as desired, unlike the conventional method in which the freezing point of water or campin is fixed.

In addition, since it is possible to utilize much more various variables and alternative materials than before, it is possible to arbitrarily control the composition and content, the viscosity of the slurry, the temperature at which the campin is phase separated, the temperature of the printing bed, and many other parameters. possibility can be presented.

1 shows the result of mixing a photocurable monomer and campin in certain ratios at room temperature.
2 shows a scene in which dendrites are formed as the campin/HDDA solution is cooled, observed through an optical microscope.
3 shows the DSC measurement results according to the mass ratio of campin and HDDA.
4 shows the dispersing agent candidate group solubility evaluation results for HDDA.
5 shows the DSC measurement results of the photocurable ceramic slurry composition and the campin/HDDA solution prepared in Example 1.(6).
6 shows a schematic diagram of 3D printing of a porous ceramic structure of a DLP method using a photocurable ceramic slurry composition.
7 shows a schematic diagram of the phase change of the slurry composition during the manufacturing process of the porous structure.
8 shows an SEM image of a porous polymer structure (pHDDA) fabricated by 3D printing using a solution excluding ceramic powder and a dispersant in the photocurable ceramic slurry composition established in Example 1.(6).
9 shows an SEM image of a porous polymer/ceramic structure fabricated by 3D printing using the photocurable ceramic slurry composition prepared in Example 1.(6).
10 shows an SEM image of a fracture surface of a porous ceramic support prepared according to heat treatment conditions.

The present invention comprises the steps of preparing a campene / photo-curable monomer solution by mixing a campene (Camphene) and a photo-curable monomer at 20 to 30 °C;

It relates to a method for preparing a photo-curable ceramic slurry composition, comprising the step of preparing a photo-curable ceramic slurry composition by mixing the campin / photo-curable monomer solution, ceramic powder, dispersant, and photo-curing initiator.

In an embodiment of the present invention, an optimal condition for manufacturing a porous support was selected by providing a process of selecting a photocurable ceramic slurry composition and setting 3D printing conditions using the photocurable ceramic slurry composition.

Specifically, first, in order to search for a photocurable monomer (photopolymer) in which campin is dissolved at room temperature, the solubility of campin in a commercial photocurable monomer was checked, and as the temperature of the campin/photopolymer solution prepared at room temperature decreased, It was confirmed with an optical microscope whether the campins well form dendrites, and the temperature at which the campins/photopolymer solution was cooled at a constant rate using DSC equipment was measured at which the campins were phase-separated and solidified. In addition, a dispersant capable of dispersing ceramic powder by being evenly mixed with the campin/photopolymer solution was explored, and the stability of slurries made from commercial alumina powders with different particle sizes to maintain an even state, ease of sintering, viscosity of the slurry, and campin crystals A ceramic powder was selected in consideration of the ease of formation, and a photocuring initiator capable of absorbing 405 nm light from a 3D printer to initiate curing of the photocurable monomer through radical formation was selected. The composition of the photocurable ceramic composition was selected through the above process. In addition, the ratio of the campin/photopolymer solution is determined in consideration of the solubility (DSC measurement result) of the campin/photopolymer, the porosity, and the strength of the 3D printed structure (green body), and in the solution except for the campin The content of the alumina powder was selected in consideration of the volume ratio of the alumina powder and the final porosity of the structure, and the content of the dispersant in which campin crystals were well formed when the temperature of the slurry was lowered was searched and selected.

Through this, in the embodiment of the present invention, a certain amount of a dispersant is evenly mixed in the campin/photopolymer solution, alumina powder and zirconia balls are added and mixed to evenly disperse the powder, and then a certain amount of A photocurable ceramic slurry composition was prepared by adding a photocuring initiator and uniformly dispersing it.

In addition, the photo-curable ceramic slurry composition optimized for the above components and ratios is cooled at a constant rate using DSC equipment, and the temperature at which the campin is phase-separated and solidified is measured. The printing bed temperature was searched and selected, and the photocuring time suitable for applying the slurry composition to 3D printing equipment was searched and selected. In addition, after printing the slurry composition with 3D printing equipment, an appropriate cleaning method and a method for removing the campin are searched and selected, and the structure that has undergone the above process is removed through an appropriate heat treatment process to remove components other than alumina, and for densification to a desired degree. Appropriate temperature, temperature rise rate and retention time for each section were searched and selected. Through this, a ceramic support was prepared.

Hereinafter, the manufacturing method of the photocurable ceramic slurry composition of this invention is demonstrated in more detail.

A slurry generally refers to a low fluidity liquid state containing a high concentration of suspended material. In the present invention, a composition including campin, a photocurable monomer, ceramic powder, a dispersant, and a photocuring initiator, which will be described below, may be expressed as a slurry.

A method for preparing a photocurable ceramic slurry composition (hereinafter, referred to as a slurry composition) according to the present invention comprises the steps of (S1) mixing a camphene and a photocurable monomer at 20 to 30° C. to prepare a campene/photocurable monomer solution; and

(S2) mixing the campin / photo-curable monomer solution, ceramic powder, dispersant and photo-curing initiator.

First, step (S1) is a step of preparing a campin / photo-curable monomer solution.

In the present invention, a camphene can be used as a pore agent in a freezing medium to realize pores connected to each other in a ceramic support. Although the campinne is in a solid state at room temperature, it has a characteristic of being in a liquid state at a specific temperature. Specifically, when the campin is cooled in a liquid state, it forms solid crystals and pushes out materials other than the present material, and may be removed after the forming process to form pores.

As described above, since campin is in a solid state at room temperature, in the prior art, a slurry composition was prepared by applying heat, and there is a problem in that heat must be applied to the slurry composition even during 3D printing.

The present invention can solve this problem, and the campin may exist in a liquid state in the photo-curable ceramic slurry composition at room temperature.

In the present invention, the photocurable monomer (monomer) is a photopolymer, and can dissolve campin at room temperature. In addition, the photocurable monomer may perform a role of uniformly complexing the ceramic powder and controlling the viscosity of the slurry composition and the strength of the molded body.

In the present invention, the photocurable monomer may be used to include not only the dictionary meaning of 'unit molecules forming a polymer', but also oligomers which are oligomers produced by polymerization of the unit molecules to a low degree.

The type of the photocurable monomer is not particularly limited as long as it can dissolve campin at room temperature, and an acrylate-based monomer may be used, and specifically 1,6-hexanediol diacrylate (HDDA) , and at least one selected from the group consisting of triethylene glycol dimethacrylate (TEGDMA) and acrylated epoxidized soybean oil (AESO) may be used.

In one embodiment, the content of the campin may be 20 to 60 parts by weight, or 30 to 45 parts by weight based on 100 parts by weight of the slurry composition, and the content of the photocurable monomer is 5 to 40 parts by weight based on 100 parts by weight of the slurry composition. , or 10 to 20 parts by weight.

In addition, the mass ratio of campin and the photocurable monomer may be 2:8 to 8.5:1.5. In the above range, the phase separation of the campin and the photocurable monomer does not occur, and the campin can be dissolved in the photocurable monomer as much as possible at room temperature. If the content of the photocurable monomer acting as a binder is used too little or if the campin is used too much, the porosity increases and the strength of the support is weak, which may cause it to be easily broken. Since there is a fear that it may be difficult to implement pores, it is recommended to adjust it within the above range.

In one embodiment, when the photocurable monomer is 1,6-hexanediol diacrylate (HDDA), the mass ratio of campin and the photocurable monomer is 5:5 to 8.5:1.5 or 6:4 to 8:2, and in the case of triethylene glycol dimethacrylate (TEGDMA), the mass ratio of campin and the photocurable monomer may be 4:6 to 8.5:1.5 or 5:5 to 8:2, and , In the case of acrylated epoxidized soybean oil (AESO), the mass ratio of campin and the photocurable monomer may be 3:7 to 4:6. In addition, when the photocurable monomer is a mixture of TEGDMA and AESO, the mass ratio of campin and the photocurable monomer may be 4:6 to 8.5:1.5 or 5:5 to 7:3.

In one embodiment, in step (S1), camphene and a photocurable monomer are mixed to prepare a campene/photocurable monomer solution, and the step may be performed at 20 to 30°C or at room temperature.

In the present invention, step (S2) is a step of mixing the campin/photocurable monomer solution, ceramic powder, dispersant and photocuring initiator prepared in step (S1). Through the above steps, a photocurable ceramic slurry composition may be prepared.

In the present invention, the slurry composition may include ceramic powder to improve physical properties of the ceramic structure and the support. Such ceramic powder may be included in the slurry composition in a volume of 5 to 30 vol%. In the case of a slurry composition having a low content of less than 5 vol%, it is easy to manufacture, but there is a risk of quality deterioration.

In one embodiment, the type of ceramic powder is not particularly limited, and for example, hydroxyapatite (HA), fluoridated hydroxyapatite (FHA), tricalciumphosphate (TCP), BCP ( At least one selected from the group consisting of biphasic calcium phosphate), alumina, zirconia, silica and bioglass may be used.

In one embodiment, the average particle size of the ceramic powder is not particularly limited, and may be 0.05 to 10 μm, specifically 0.1 to 5 μm, and more specifically 0.2 to 1 μm. Dispersion is easy in the above range.

In addition, the content of the ceramic powder may be 10 to 70 parts by weight based on 100 parts by weight of the slurry composition. In the above content range, it is possible to prepare a ceramic structure and a support having excellent physical properties.

In the present invention, the dispersant may be used to uniformly mix the photocurable monomer, campin, and ceramic powder.

In one embodiment, the type of the dispersant is not particularly limited, and for example, xylene, an organic material having acetate, an alkylammonium salt copolymer compound, a polyester/polyether-based compound , at least one selected from the group consisting of a copolymer containing a phosphoric acid group and a copolymer having an amine group may be used.

In one embodiment, the content of the dispersant may be 1 to 5 parts by weight, or 1 to 3 parts by weight based on 100 parts by weight of the slurry composition. A uniform slurry composition can be prepared in the above range. If the content is less than 1 part by weight, it is difficult to prepare a slurry having a uniform composition due to the agglomeration of ceramic powder particles with each other.

In addition, in the present invention, the photocurable initiator may polymerize the photocurable monomer by forming free radicals by electromagnetic waves in a specific wavelength band selectively controlled.

In one embodiment, the type of the photocuring initiator is not particularly limited, for example, phenylbis (2,4,6-trimethyl benzoylphosphine oxide) (Phenylbis (2, 4, 6-trimethyl benzoylphosphine oxide), PPO ), phenylbis (2,4,6-trimethyl benzoylphosphine oxide) (Phenylbis (2, 4, 6-trimethyl benzoylphosphine oxide), PPO), 1-hydroxy-cyclohexyl-phennyl-ketone (1-Hydroxy- cyclohexyl-phenyl-ketone), 2-hydroxy-2-methyl-1-phenyl-1-propanone (2-Hydroxy-2-methyl-1-phenyl-1-propanone), 2-hydroxy-1-[ 4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (2-Hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone), methylbenzoyl Formate (Methylbenzoylformate), oxy-phenyl-acetic acid-2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester (oxy-phenyl-acetic acid -2-[2 oxo-2phenyl-acetoxy- ethoxy]-ethyl ester), oxy-phenyl-acetic acid-2-[2-hydroxy-ethoxy]-ethyl ester (oxy-phenyl-acetic acid-2-[2-hydroxy-ethoxy]-ethyl ester), alpha -Dimethoxy-alpha-phenylacetophenone (alpha-dimethoxy-alpha-phenylacetophenone), 2-benzyl-2-(dimethylamino)1-[4-(4-morpholinyl)phenyl]-1-butanone (2 -Benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone), 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinone) nyl)-1-propanone (2-Methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone) and diphenyl (2,4,6-trimethylbenzoyl)-phospho fin oxide (Diphen) At least one selected from the group consisting of yl (2,4,6-trimethylbenzoyl)-phosphine oxide, TPO) may be used.

In one embodiment, the content of the photocuring initiator may be 0.1 to 1 parts by weight based on 100 parts by weight of the slurry composition. In addition, the content of the photocuring initiator may be 1 to 5 parts by weight or 1 to 3 parts by weight based on 100 parts by weight of the photocurable monomer. In the above range, photocuring of the photocurable monomer may be easily performed.

In one embodiment, mixing of the above-mentioned components in step (S2), that is, campin/photocurable monomer solution, ceramic powder, dispersant and photocuring initiator may be performed through a general method in the art.

In one embodiment, first, the campin/photocurable monomer solution, ceramic powder, and dispersant may be mixed, and then a photocuring initiator may be mixed. In addition, when mixing the ceramic powder, it is possible to evenly disperse the powder by adding zirconia balls.

In one embodiment, the step (S2) may be performed under the temperature conditions of step (S1), that is, 20 to 30°C.

A photocurable ceramic slurry composition may be prepared through the above-described steps (S1) and (S2). The temperature of the prepared photo-curable ceramic slurry composition may be 20 to 30 ℃.

In addition, the present invention relates to a photocurable ceramic slurry composition prepared by the method for preparing the photocurable ceramic slurry composition described above.

The photocurable ceramic slurry composition according to the present invention may include the aforementioned campin, photocurable monomer, ceramic powder, dispersant, and photocurable initiator.

In one embodiment, the temperature of the photo-curable ceramic slurry composition may be 20 to 30 ℃. Since the campin used in the present invention exists as a liquid in the slurry composition of the present invention, 3D printing can be performed without being affected by temperature conditions during 3D printing.

In addition, the present invention relates to a method for manufacturing a ceramic structure using the above-described photocurable ceramic slurry composition.

The method of manufacturing a ceramic structure of the present invention comprises the steps of: (A) applying a photocurable ceramic slurry composition to a 3D printing bed to form a ceramic slurry layer for 3D printing;

(B) after inducing the solidification of the campin, photocuring to a pre-designed shape to form a ceramic structure;

(C) forming a porous ceramic structure in which micropores are formed by freeze-drying the ceramic structure; and

(D) heat-treating the porous ceramic structure at a high temperature.

In the present invention, the shape of the ceramic structure and the ceramic support can be maintained by using the above-described photocurable ceramic slurry composition, and physical properties of the ceramic support can be adjusted.

In the present invention, it is possible to provide a photo-curable ceramic-based 3D printing technology applicable to a vapor-ized 3D printer through the fusion of computer-controlled 3D printing technology and photo-curing molding technology.

In one embodiment, the photo-curable ceramic slurry composition of the present invention applies the tape casting technique to the top-down printing method, stacking a thin slurry layer on a printing bed that can be set at a low temperature using a thermoelectric element, It can be printed on equipment that can be photocured with a DLP projector in the wavelength band.

In the present invention, step (A) is a step of applying a photocurable ceramic slurry composition, to form a ceramic slurry layer for 3D printing.

In the present invention, 3D printing can print 3D drawing data using a printer according to a program designed in advance by a computer.

Specifically, the photocurable ceramic slurry composition may be applied to a printing bed, and a ceramic slurry layer having a constant thickness may be formed using a doctor blade at a temperature of 20 to 30°C.

At this time, the temperature of the printing bed may be -10 to 20 ℃.

In the above temperature range, the campin may be phase separated (solidified) into a solid at an appropriate rate in the photocurable ceramic slurry composition. That is, not only the slurry coating occurs well at the above temperature, but also the formation of crystals of the campin can occur sufficiently.

In particular, since the campin contained in the ceramic slurry for implementing the micropores in the structure is in a liquid state in the slurry composition at room temperature, in the present invention, printing is possible at room temperature without setting a separate temperature condition. Through this, it is possible to prevent the phenomenon of having a non-uniform thickness when forming a slurry layer using a doctor blade because the freezing medium solidifies very quickly when a separate printing bed is not heated during conventional 3D printing.

In one embodiment, the thickness of the ceramic slurry layer is controllable using a doctor blade, and may be between 25 and 200 μm.

In the present invention, step (B) is a step of photocuring after inducing the solidification of campin in the ceramic slurry layer formed in step (A). In the present invention, the ceramic slurry layer can be photocured in a pre-designed shape.

In the present invention, a ceramic structure having micropores can be formed by continuously and repeatedly performing the ceramic slurry layer formation/photocuring process.

In one embodiment, the solidification induction time may be adjusted according to the content of the freezing medium in the slurry.

In one embodiment, photocuring may be performed by visible light or ultraviolet light irradiated from a DLP projector in a 405 nm wavelength band. The ultraviolet irradiation may be performed by a UV beam, etc. In this case, the intensity of the irradiated ultraviolet rays may be 50 to 300 W/m ² .

In one embodiment, the photo-curing time may be determined to completely photo-cure the ceramic slurry layer. In this case, if the time is short, a phenomenon in which the bonding between the ceramic molding layers is very weak may occur.

In addition, the photocuring time is appropriately adjusted so that the ceramic slurry layer is completely cured and the bonding site of the layer is cured a little deeper than the previously programmed thickness of the layer during photocuring for bonding with the previously cured upper layer. can This allows the cured layer to overlap the upper layer.

Step (C) is a freeze-drying step, which is a step of forming a porous ceramic structure in which three-dimensionally connected micropores are formed by freeze-drying to remove a freezing medium, that is, campin.

In one embodiment, when the three-dimensionally connected cam pin present in the ceramic structure is removed, the position remains as a micropore.

In one embodiment, in freeze-drying, the campin can be easily removed without damage to the ceramic structure at a temperature of -70°C to 0°C and a pressure of 0.1 to 20 mTorr.

The term "three-dimensionally connected micropores" refers to micropores connected in multiple directions, for example, not as closed pores, such as air bubbles, but above, below, and on either side of the specimen. It means an open pore structure connected in multiple directions.

In the present invention, step (D) is a step of heat-treating the porous ceramic structure at a high temperature. Through this step, the residual polymer can be removed and the ceramic wall can be densified.

In the present invention, heat treatment may be performed at 200 to 600° C. for 1 to 40 hours, followed by secondary heat treatment (sintering) at 1300 to 1700° C. for 1 to 10 hours.

In one embodiment, the primary heat treatment may effectively remove the polymer present in the porous ceramic structure manufactured by the photocuring method.

The first heat treatment may be performed at 200 to 600° C. for 1 to 40 hours. If the heat treatment temperature is too low or the time is too short, the mechanical strength may be lowered and the polymer and/or the dispersant may not be easily removed. In addition, by performing heat treatment while increasing the temperature step by step, it is possible to more easily remove impurities.

In the secondary heat treatment (sintering), the ceramic walls can be densified and adhesion between the ceramic walls can be enhanced.

The secondary heat treatment may be performed at 1300 to 1700° C. for 1 to 10 hours. If the secondary heat treatment temperature is too high or the time is long, there is a risk that the chemical composition of the pore structure and the ceramic structure may be different.

In addition, the present invention relates to a porous support prepared by the above-described manufacturing method.

In the porous support having a micropore structure prepared by the present invention, a ceramic structure having a micropore structure having an average diameter (diameter) of 0.5 to 50 μm is formed in various directions for each layer and is three-dimensionally connected, and the porosity is 20 to 70%, and even though the pores are aligned, there is no significant difference in strength depending on the direction due to the characteristics of the dendritic pores.

The present invention also relates to an article comprising the porous support.

Since the porous support according to the present invention has a regular pore structure and excellent mechanical properties, it can be used as an ion battery, a filter, a catalyst support, a drug delivery system, or a biomaterial.

Advantages and features of the present invention, and methods of achieving them, will become apparent with reference to the embodiments described below in detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the technical field to which the present invention belongs It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims.

Example

1. Preparation of photocurable ceramic slurry composition

(1) Selection of a photocurable monomer (photopolymer) in which campin is soluble at room temperature

1,6-hexanediol diacrylate (HDDA, Sartomer, USA) was selected as a photocurable monomer (photopolymer) capable of dissolving campene (Camphene-95%, Sigma Aldrich, USA) at room temperature. HDDA is a bifunctional monomer and has a low viscosity at room temperature and has an advantage of high strength after curing.

By varying the mixing ratio of the campin and HDDA, the mixing pattern according to the content of the HDDA was confirmed. At this time, the mixing ratio (weight ratio) of the campin and HDDA was adjusted to 6:4, 7:3, 8:2, 9:1.

1a shows the result of dissolving campin in certain ratios in HDDA, which is a photocurable monomer, at room temperature.

As a result, it can be confirmed that, in the case of Camphene, phase separation of the layers occurred at a weight ratio of 9:1 when mixed with HDDA. In the case of 6:4, 7:3, and 8:2, it can be seen that the cam pin is well dissolved in HDDA.

Therefore, it is possible to prepare a photocurable ceramic slurry composition having good flowability, low viscosity, and capable of 3D printing at room temperature using HDDA.

On the other hand, other photocurable polymers other than HDDA were also evaluated for solubility in campin, which is shown in FIGS. 1B to 1D.

1b to 1d, in the case of TEGDMA, at a mass ratio of 5:5 to 7:3, campin is well soluble in TEGDMA, and in the case of AESO, at a mass ratio of 3:7 to 4:6, campin is dissolved in AESO. It is well dissolved, and in the case of a mixed solution of TEGDMA and AESO, it can be seen that campin is well dissolved at a mass ratio of 5:5 to 7:3.

(2) Observation of the cooling process of campin/HDDA solution

After spraying a small amount of campin/HDDA solution on the slide glass, covering the cover glass to make a thin layer, the bottom part was cooled to about 0°C, and the solidification (phase separation) process of the campin was observed under an optical microscope. At this time, the weight ratio of campin and HDDA in the solution was 7:3, and the portion where crystals grew with directionality was photographed.

2 shows a scene in which dendrites are formed as the campin/HDDA solution observed through an optical microscope is cooled.

As shown in FIG. 2, it can be confirmed that when the campin/HDDA solution is cooled, the campin is phase-separated to form dendrites and solidify. By directly observing the above process, it can be confirmed that the campin can be used as a pore agent in the campin/photopolymer solution through temperature control.

(3) DSC measurement result according to the weight ratio of cam pin and HDDA

Differential scanning calorimetry (DSC) was measured according to the weight ratio of campin and HDDA in the campin/HDDA solution.

The DSC was measured through a DSC Q20 (TA Instrument, USA) instrument, and the solution was cooled at a rate of 5° C. per minute.

3 shows the DSC measurement results according to the weight ratio of campin and HDDA.

As shown in FIG. 3 , when the weight ratio of the cam pin and HDDA is 9:1, it can be confirmed that the cam pin does not completely melt at room temperature. In the case of 6:4, 7:3, and 8:2, campin was well dissolved in HDDA at room temperature.

(4) Setting a dispersant for the preparation of a photocurable ceramic slurry composition

For some of the hydrophobic dispersants shown in Table 1 below, solubility in HDDA and solubility in a solution to which campin was added were confirmed.

Specifically, solubility was confirmed by adding 1 g of a dispersing agent to 2 g of HDDA.

dispersant candidates manufacturing company product name Evonik Variquat ^® CC 9 Croda Inc. Hypermer™ KD4 BYK DISPERBYK-163 BYK DISPERBYK-180 BYK DISPERBYK-2001

4 is a photograph showing the dispersing agent candidate group solubility evaluation results for HDDA.

As shown in FIG. 4 , it can be confirmed that KD4, BYK-2001 and BYK-163 among the dispersants are well soluble in HDDA solution.

In the present invention, colorless BYK-163 was selected among the dispersants stably dispersed in the HDDA solution.

(5) Selection of alumina powder and photocuring initiator

Alumina powder was selected as the ceramic powder.

Specifically, the photocurable ceramic slurry composition contains a large amount of campin in a liquid state with low viscosity and has low viscosity because the content of ceramic powder is not high. 0.3 μm 99.99% purity α-alumina powder from Kojundo Chemical Laboratory, Japan, which has a small size, was used.

In addition, TPO was selected as the photocuring initiator.

Specifically, in order to prepare a photocurable ceramic slurry composition applicable to DLP in the 405 nm wavelength band with visible and high energy, information related to a photocuring initiator capable of absorbing 405 nm light was searched, and through this, TPO (2, 4,6-Trimethylbenzoyldiphenylphosphine oxide, Sigma Aldrich, USA) was selected.

(6) Establishment of composition of photocurable ceramic slurry composition

Specifically, in order to establish the composition of the photocurable ceramic slurry composition,

(a) As a result of DSC measurement, taking into account the expected porosity (final volume ratio of campin) and the strength of the structure (raw material), campin crystals are formed at -10℃ or higher, which is the temperature range of the thermoelectric element at room temperature, and the strength of the printable structure is determined The ratio of cam pin and HDDA that can be provided is selected as 7:3,

(b) The content of alumina powder with a size of 0.3 μm was tentatively selected in consideration of the porosity and volume ratio in components excluding campin,

(c) Based on the content of alumina powder, the structure prepared by adding a dispersant in a certain proportion was removed from the campin and photographed with a field emission scanning electron microscope (FE-SEM), JSM-6701F, JEOL Techniques, Japan equipment. Therefore, based on the experimental results in which the ceramic powder was sufficiently dispersed by the dispersant and the pores formed by the campin crystal were formed in a dendritic form, the structure of the sample prepared by arbitrarily selecting the dispersant content was confirmed.

(d) In addition, based on the amount of the photocurable monomer, the amount of the photocuring initiator capable of being printable to a thickness of 100 μm and having a sufficient photocuring depth and appropriate time is set arbitrarily, and a slurry is prepared to make 3D printing light After confirming the degree of curing under the conditions, a photocuring initiator was selected to establish the final composition of the photocurable ceramic slurry composition.

Through the above process, the composition and content (g) of the photocurable ceramic slurry composition were established as shown in Table 2 below.

role pore-forming agent photocurable monomer ceramic powder dispersant photocuring initiator Ingredient name Camphene HDDA Al ₂ O ₃ BYK-163 TPO Density [g/cc] 0.85 1.02 3.97 0.99 1.12 mass [g] 14.00 6.00 15.97 0.96 0.12 Volume ratio [%] 60.00 21.43 14.66 3.53 0.38

- Camphene: Camphene 95%, Sigma Aldrich

- HDDA (1, 6-HexaediolDiacrylate): Sartomer

- Al ₂ O ₃ (α-Alumina): 0.3 μm, Kojundo Chemical Laboratory

- BYK-163 (DISPERBYK-163): BYK-Chemie GmbH

- TPO (Diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide): Sigma Aldrich

The photo-curable ceramic slurry composition is prepared by mixing campin and photo-curable monomer to prepare a campin/photo-curable monomer solution, and after evenly mixing the dispersant in the camp-in/photo-curable monomer solution, alumina powder and zirconia balls are added and mixed to make the powder even. After dispersion, a photocuring initiator was added and uniformly dispersed.

(7) DSC measurement

By measuring the DSC of the photocurable ceramic slurry composition prepared in (6), the phase separation temperature of the campin was measured.

It was measured through a DSC Q20 (TA Instrument, USA) instrument, and the solution was cooled at a rate of 5° C. per minute.

And, it was compared with DSC in the campin/HDDA solution (campin:HDDA=7:3).

5 shows the DSC measurement results of the photocurable ceramic slurry composition and the campin/HDDA solution having the composition shown in Table 2.

As shown in FIG. 5, when cooled to 5°C per minute, the campin/HDDA (7:3) solution showed a solidification point at about 5°C, and as the dispersant and ceramic powder were added, the solidification point moved to about -2°C. that can be checked At this time, if the cooling rate is reduced during the measurement, the freezing point is measured at a higher temperature, which is closer to reality. Therefore, it is possible to solidify the campin at the printing bed temperature in the embodiment.

2. Fabrication of porous ceramic structures and ceramic supports using 3D printer equipment

6 is a photo-curable slurry in which campin is dissolved, that is, a DLP-type porous ceramic 3D printing schematic diagram using the photo-curable ceramic slurry composition according to the present invention.

6, in the present invention, using the photocurable ceramic slurry composition of the composition and content established in 1. (6), a slurry layer is formed on the printing bed using the 3D printing equipment of the present invention, Phase separation (solidification) of the campin in the formed slurry layer was induced, and then photocuring was performed to prepare a ceramic structure.

In addition, the porous ceramic structure was prepared by removing the campin from the ceramic structure by freeze-drying, and then heat treatment was performed to finally prepare a porous ceramic support.

Hereinafter, a process of selecting conditions for manufacturing the porous ceramic structure and the support is shown.

(1) Production of structures (raw bodies)

By applying a thermoelectric element capable of Z-axis movement, the photocurable ceramic slurry composition prepared in 1.(6) was extruded on a printing bed set at a low temperature, and a layer of a certain thickness (100 μm) was formed by a tape casting method. Phase separation of campin from the slurry occurs by the low temperature printing bed.

After that, the two-dimensional shapes cut in the stacking direction and the stacking thickness of the three-dimensional design were cured using light for a set time for each slurry layer. By repeating this process, a three-dimensional structure (raw material) was manufactured, and the cam pin was removed to form a porous ceramic structure.

In the photocurable ceramic slurry composition, a porous polymer was also manufactured by applying a campin/photocurable monomer/photocuring initiator solution excluding the ceramic powder and dispersant.

7 shows a schematic diagram of the phase change of the slurry during the manufacturing process of the porous structure. As the slurry in which the powder is uniformly dispersed in the campin/HDDA solution is cooled, the campin crystals are formed, and phase separation occurs by pushing out the remaining slurry components. The extruded slurry is exposed to light and photocured to form a skeleton in the molded body, and the campene crystals are removed to form dendritic pores.

8 shows an SEM image of a porous polymer structure (pHDDA) fabricated by the 3D printing method using a solution excluding ceramic powder and a dispersant in the photocurable ceramic slurry composition established in 1.(6).

As shown in FIG. 8 , it can be confirmed that the photocurable monomer pushed out by the campin solidification (phase separation) is photocured and the campin is removed to form three-dimensionally connected dendritic pores.

Also, FIG. 9 shows an SEM image of the porous polymer/ceramic structure fabricated by the 3D printing method using the photocurable slurry established in 1.(6).

As shown in FIG. 9 , it can be confirmed that the photocurable slurry pushed out according to the solidification of the cam pin is photo-cured, and the cam pin is removed to form three-dimensionally connected dendritic pores.

(2) Measurement of photocuring depth according to photocuring time

The curing time for sufficient interlayer bonding to fit the Z-axis resolution of 100 μm setting was investigated.

Specifically, the slurry layer of sufficient thickness was cooled under photocuring conditions to phase-separate, and after exposure to light for a certain period of time, the cured thickness was measured.

The results are shown in Table 3 below.

Photocuring time (sec) 70 80 90 Photocurable thickness (μm) 140 170 190~200

Table 3 shows the curing thickness of the slurry layer according to the photocuring time.

As shown in Table 3, it can be seen that as the photocuring time increases, the cured thickness also increases.

(3) Setting the printing temperature condition

The temperature at which campin is phase-separated into a solid at an appropriate rate in the photo-curable ceramic slurry composition was investigated. Through this, the printing bed temperature at which crystal formation occurs sufficiently and slurry coating can occur well was searched and selected based on the DSC results of the slurry.

It was set around -2℃, which is near the peak temperature. At a higher temperature, the phase separation of the campin may not occur well. At a lower temperature, the phase separation of the campin occurs after the slurry is extruded onto the printing bed at a low temperature before coating, so that the slurry layer is formed properly. There is a risk that it will not happen. In addition, there is a risk that atmospheric water vapor is condensed on the low-temperature slurry layer and adsorbed between the layers.

(4) Post-processing process for removing the cam pin after manufacturing the hexahedral structure

After fabricating the structure, wash the uncured surrounding slurry with ethanol and remove the campin from the structure. ① Leave at room temperature and pressure for one day, ② Use a freeze dryer, FD5508, ilShinBioBase, Republic of Korea for one day, or , ③ was dried through heat treatment. No problem was found in the final result using any of the three methods.

(5) Heat treatment process for sintering ceramic and removing components other than ceramic from the porous structure from which the cam pin has been removed

The temperature information at which impurities are removed from the porous structure manufactured by (4) was searched for, and based on this, heat treatment conditions were searched and selected in which the pore shape did not collapse or cracks did not occur in the result. In addition, the pore shape and the degree of densification of the ceramic wall were checked according to the sintering conditions.

Specifically, heat treatment was sequentially performed as shown in Table 4 below to remove impurities.

Rising temperature per minute (°C) / Target temperature (°C) hold time (min) 5 of 270 60 1/300 60 0.5 / 400 60 1 / 500 60

Table 4 shows a heat treatment process for removing components other than ceramic.

In addition, as a sintering process, it was heated at a rate of 5° C. per minute immediately after heat treatment to remove components other than ceramic. The pore structure is maintained when the mooring is carried out at 1400°C for 2 hours and 30 minutes, and there are fine pores between the particles on the ceramic wall. It can be seen that there is no densification.

10 shows SEM images of fracture surfaces for each sintering temperature after heat treatment (degreasing process) under the conditions of Table 4 is performed on the structure manufactured by the 3D printing method.

As shown in FIG. 10, in the prepared porous support, materials other than ceramic were well removed without cracks in the structure through the degreasing process, and it can be confirmed that the structure was maintained and the bonding between the ceramic powder was achieved according to the sintering conditions. . Specifically, it can be seen that the structure is maintained and micropores are formed in the skeleton under the condition of 1400°C, and the maintenance and densification of the structure are well maintained at the condition of 1550°C.

Claims (14)

Preparing a campene / photo-curable monomer solution by mixing a campene (Camphene) and a photo-curable monomer at 20 to 30 ℃;
Mixing the campin / photo-curable monomer solution, ceramic powder, dispersant and photo-curing initiator to prepare a photo-curable ceramic slurry composition,
The photocurable monomer is a group consisting of 1,6-hexanediol diacrylate (HDDA), triethylene glycol dimethacrylate (TEGDMA), and acrylated epoxidized soybean oil (AESO). A method for producing a photocurable ceramic slurry composition comprising at least one selected from
delete The method of claim 1,
A method for producing a photocurable ceramic slurry composition, wherein campin and the photocurable monomer are mixed in a mass ratio of from 2:8 to 8.5:1.5.
The method of claim 1,
Ceramic powder is hydroxyapatite (HA), fluorine-containing hydroxyapatite (FHA), tricalciumphosphate (TCP), BCP (biphasic calcium phosphate), alumina, zirconia, silica (silica) and a method for producing a photocurable ceramic slurry composition comprising at least one selected from the group consisting of bioglass.
The method of claim 1,
A method for producing a photocurable ceramic slurry composition, wherein the ceramic powder is 5 to 30 vol% of the total volume of the photocurable ceramic slurry composition.
The method of claim 1,
The dispersant is an organic material containing xylene and acetate, an alkylammonium salt copolymer compound, a polyester/polyether-based compound, a copolymer containing a phosphoric acid group, and an amine group. A method for producing a photocurable ceramic slurry composition comprising at least one selected from the group consisting of copolymers.
The method of claim 1,
The photocuring initiator is phenylbis(2,4,6-trimethyl benzoylphosphine oxide) (PPO), 1-hydroxy-cyclohexyl-pennyl-ketone, 2-hydroxy-methyl-1-phenyl-1-propanone , 2-Hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, methylbenzoylformate, oxy-phenyl-acetic acid-2-[2-oxo-2 -Phenyl-acetoxy-ethoxy]-ethyl ester, oxy-phenyl-acetic acid-2-[2-hydroxy-ethoxy]-ethyl ester, alpha-dimethoxy-alpha-phenylacetophenone, 2-benzyl-2 -(dimethylamino)1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl) -1-propanone and diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (TPO) method for producing a photocurable ceramic slurry composition comprising at least one selected from the group consisting of.
The method of claim 1,
The temperature of the photo-curable ceramic slurry composition is 20 to 30 ℃ method for producing a photo-curable ceramic slurry composition.
It is prepared by the manufacturing method according to claim 1,
Campphene, a photocurable monomer, a ceramic powder, a dispersant and a photocuring initiator,
A photocurable ceramic slurry composition in which campin is present in a liquid phase in the composition at 20 to 30°C.
forming a ceramic slurry layer for 3D printing by applying the photocurable ceramic slurry composition according to claim 9 to a 3D printing bed;
forming a ceramic structure by photocuring to a pre-designed shape after inducing solidification of the campin;
forming a porous ceramic structure in which micropores are formed by freeze-drying the ceramic structure; and
A method of manufacturing a three-dimensional porous support having a three-dimensionally connected micro-pore structure, comprising the step of heat-treating the porous ceramic structure.
11. The method of claim 10,
The method for producing a three-dimensional porous support, wherein the thickness of the ceramic slurry layer is controlled to 25 to 200 ㎛ using a doctor blade.
11. The method of claim 10,
Freeze-drying is a method for producing a three-dimensional porous support that is carried out under the conditions of a temperature of -70 ℃ to 0 ℃ and a pressure of 0.1 to 20 mTorr.
11. The method of claim 10,
Heat treatment is a method of manufacturing a three-dimensional porous support to perform a primary heat treatment for 1 to 40 hours at 200 to 600 ° C., and then performing a secondary heat treatment (sintering) at 1300 to 1700 ° C. for 1 to 10 hours.
A three-dimensional porous support having a three-dimensionally connected micropore structure prepared by the method according to claim 10.

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