KR102353525B1 - Photocuring-assisted 3D plotting to produce hollow tubular ceramic scaffolds - Google Patents

Abstract

The present invention relates to a manufacturing technique of a hollow tubular porous ceramic structure using a photocurable 3D plating technique.
The hollow tubular porous structure manufactured using the photocurable 3D plating according to the present invention can have a high porosity that cannot be achieved with conventional techniques, and when used as a bone scaffold, it further improves the internal growth and regeneration rate of bone can do it

Description

Photocuring-assisted 3D plotting to produce hollow tubular ceramic scaffolds

The present invention relates to a technology for manufacturing a tubular ceramic scaffold using a photocurable 3D plating technology.

When a fatal defect occurs in the bone, it is treated using a scaffold using a bone substitute material. Among these bone substitute materials, ceramics such as hydroxyapatite, bioglass, zirconia, and alumina are used. Among them, hydroxyapatite has a ratio of calcium (Ca) to phosphorus (P) of 1.47, which is the most similar to bone. Due to this, it has strong mechanical strength and high osteoconductivity compared to other ceramics, suggesting the ability to directly bond to bone. Therefore, hydroxyapatite is the most promising material for use as a scaffold. The interconnected pore structure in bone scaffolds has been widely applied because of its several advantages. The presence of pores provides a high surface area to the scaffold and causes significant fluid penetration inside the body, which in turn increases the anchoring force of the bone and scaffold. The method of inserting such pores is a method of manufacturing a scaffold having pores through a three-dimensional plating method of ceramics, manufacturing by putting an auxiliary agent that creates pores inside the ceramic, or a method of increasing the porosity through a tubular structure by putting a core material inside A method of increasing the porosity of ceramics through various manufacturing methods such as, etc. is being implemented.

Recently, a photo-curing technology-based 3D plating technology has emerged, and this technology has shown the effect of increasing the complex shape manufacturing and shape retention of ceramic plating that were not previously achieved. However, so far, this technology only uses ceramic plating with a dense structure, and a ceramic scaffold having a high porosity has not been produced.

1. Registered Patent Publication No. 10-1873223 2. Laid-open Patent Publication No. 10-2020-0027584

An object of the present invention is to manufacture a ceramic structure having a hollow tubular porous structure using a photo-curable three-dimensional plotting technique.

The present invention comprises the steps of preparing a shell feed rod by injecting a porous ceramic slurry composition into a mold equipped with a shell supporter;

removing the shell supporter from the mold; and

and injecting a carbon black slurry composition into the space from which the shell supporter is removed to prepare a core feed rod,

The porous ceramic slurry composition includes a ceramic powder, a photocurable monomer, a freezing medium, a dispersant and a photoinitiator,

The carbon black slurry composition provides a method for producing a core-shell feed rod comprising carbon black, a viscosity modifier and a dispersant.

In addition, the present invention provides a core-shell feed rod manufactured by the above-described method for manufacturing the core-shell feed rod.

In addition, the present invention comprises the steps of manufacturing a scaffold by extruding and laminating the core-shell feed rod prepared by the above-described manufacturing method using 3D plating;

lyophilizing the scaffold; and

Comprising the step of heat-treating the lyophilized scaffold,

The core-shell feed rod provides a method of manufacturing a hollow tubular porous structure that is photocured by ultraviolet irradiation after extrusion.

In addition, the present invention provides a hollow tubular porous structure prepared by the above-described method for manufacturing the hollow tubular porous structure.

In the present invention, by using the photo-curable three-dimensional plating technology, it is possible to manufacture a structure having a more complex shape by enabling ceramic plating having a high shape-retaining force that could not be obtained in the conventional plating technology. In the present invention, it is possible to manufacture a spiral or free-form structure using the above technique, and by combining a given code, it is possible to enable plating of more various shapes.

In particular, the hollow tubular porous structure manufactured using the photocurable 3D plating according to the present invention can have a high porosity that cannot be achieved with conventional techniques, and when used as a bone scaffold, the internal growth and regeneration rates of bone are reduced. It is expected that further improvement can be made.

1 shows the results of extrusion behavior of a carbon black slurry composition having a content different from that of a porous ceramic slurry composition having a fixed composition.
2 shows the manufacturing procedure of a core-shell feedrod for making a hollow tubular structure.
3 is a photograph of a shell supporter and a syringe.
4 shows a process for preparing a sample (scaffold) having a hollow tubular porous structure using a photocurable three-dimensional plating technique.
Figure 5 shows a schematic diagram for the photocuring and freeze-drying process.
6 and 7 show the results of confirming the structure of the filament prepared by the photocurable three-dimensional plating technology through an optical microscope and FE-SEM.
8 shows a schematic diagram (A) of a computer designed scaffold and an actual shape (B) of a scaffold with different filament spacing.
9 and 10 show the internal structure of the scaffold confirmed through an optical microscope (FIG. 8A), FE-SEM (FIG. 8B), and micro-CT (FIG. 9).
11 shows the porosity measurement results of the sintered scaffolds having different filament spacing.
12 shows the compressive strength test results of sintered scaffolds having different filament spacing.

In describing the components of the present invention, terms such as (A), (B), (a), (b) may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms.

The present invention provides a method for manufacturing a hollow tubular porous structure using a photocurable three-dimensional plating technique.

In the present invention, "photocurable three-dimensional plating technology" is a technology that can obtain a structure (ceramic scaffold) by irradiating UV light using a photocurable monomer. This technology enables three-dimensional plating of more complex shapes by enabling ceramic plating with a high shape-retaining force that could not be obtained with conventional plating technology.

In the conventional manufacturing of a porous ceramic structure using three-dimensional plating, a method of manufacturing a porous ceramic structure by stacking filaments using simple plating or using a camphene or the like was used. However, the structure manufactured by the above methods has a limitation in that the shape retaining force is not high. Recently, a photocurable 3D plating equipment that improves shape retention in ceramic plating technology has been used, making it possible to manufacture structures with high shape retention. However, since the inside of the structure manufactured using this technology still has a dense structure, there is a limit in increasing the porosity of the manufactured structure.

Therefore, in the present invention, by using a porous ceramic slurry composition to which a freezing medium is added for realizing a microporous structure and a carbon black slurry composition for making a hollow tubular structure together, which has not been achieved in conventional photocurable plating, It may be possible to manufacture a hollow tubular porous structure having a high porosity and also having a microporous structure.

The present invention provides a method for manufacturing a core-shell feedrod for application to photocurable three-dimensional plating technology.

A method for manufacturing a core-shell feed rod according to the present invention comprises the steps of: (A) preparing a shell feed rod by injecting a porous ceramic slurry composition into a mold equipped with a shell supporter;

(B) removing the shell supporter from the mold; and

(C) preparing a core feed rod by injecting a carbon black slurry composition into the space from which the shell supporter is removed.

In the present invention, the slurry generally refers to a liquid state with low fluidity containing a high concentration of suspended material, and in the present invention, the slurry may be used to include a paste or a dough state.

In the present invention, the porous ceramic slurry composition is used as a shell feed rod in a core-shell feed rod.

The porous ceramic slurry composition includes a ceramic powder, a photocurable monomer, a freezing medium, a dispersant, and a photoinitiator.

The slurry composition of the present invention may include ceramic powder to improve physical properties of ceramic compacts and structures. Such ceramic powder may be included in the slurry composition in a volume of 10 to 50 vol% and 15 to 30 vol%. In the case of a slurry composition of less than 30 vol %, the preparation is easy, but there is a risk of quality deterioration. Meanwhile, since the freezing medium is removed during the preparation of the porous ceramic to be described later, the volume of the ceramic powder in the hollow tubular porous structure may be 30 to 70 vol% or 40 to 60 vol%.

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

In addition, the content of the ceramic powder may be 30 to 70 parts by weight, 35 to 60 parts by weight, or 40 to 50 parts by weight based on 100 parts by weight of the slurry composition. In the above content range, it is possible to manufacture a ceramic molded body and a structure having excellent physical properties. In addition, the content of the ceramic powder in the hollow tubular porous structure may be 60 to 90 parts by weight, 65 to 80 parts by weight.

In the present invention, the photocurable monomer (monomer) may play a role of uniformly complexing the ceramic powder and controlling the viscosity of the slurry composition and the strength of the molded body. The slurry composition used in the conventional 3D printer requires a low viscosity. However, as the content of the ceramic powder increases, the viscosity increases, which causes a problem in 3D printing. In the present invention, a molded article may be prepared by preparing a slurry composition having a high viscosity and extruding the slurry composition.

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, and an acrylate-based monomer may be used, and specifically, 1,6-hexanediol diacrylate (HDDA), urethane dimethacrylate (Diurethane) At least one selected from the group consisting of dimethacrylate, UDMA), acryloyl morpholine, and triethylene glycol dimethacrylate (TEGDMA) may be used.

The content of the photocurable monomer may be 5 to 30 parts by weight, or 10 to 20 parts by weight based on 100 parts by weight of the slurry composition.

In the present invention, the freezing medium serves as a freezing medium for freeze-molding, and may be removed during freeze-drying to form micropores. The type of the freezing medium is not particularly limited, and campene, camphor, or a mixture thereof may be used.

The content of the freezing medium may be 20 to 50 parts by weight, or 30 to 40 parts by weight based on 100 parts by weight of the slurry composition. In addition, the freezing medium may be included in a volume of 50 to 70 vol% or 55 to 65 vol% in the slurry composition.

In the present invention, the dispersing agent may be used to facilitate dispersion of ceramic powder and freezing medium.

The type of the dispersant is not particularly limited, and for example, an alkylammonium salt copolymer compound, a polyester/polyether-based compound, a copolymer containing a phosphoric acid group, and a copolymer having an amine group. One or more selected from the group consisting of may be used.

The content of the dispersant may be 1 to 5 parts by weight, or 1 to 4 parts by weight based on 100 parts by weight of the slurry composition. A uniform slurry composition can be prepared in the above range.

In addition, in the present invention, the photoinitiator polymerizes the photocurable monomer by forming free radicals by UV in a specific wavelength band that is selectively controlled.

The type of the photoinitiator is not particularly limited, and 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-phenyl-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-hydroxyl) oxyethoxy) phenyl] -2-methyl-1-propanone (2-Hydroxy-1- [4- (2-hydroxyethoxy) phenyl] -2-methyl-1-propanone), methylbenzoylformate (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-morpholinyl)-1-propane One (2-Methyl-1- [4- (methylthio) phenyl] -2- (4-morpholinyl) -1-propanone) and diphenyl (2,4,6-trimethylbenzoyl) -phosphine oxide (Diphenyl (2 ,4, At least one selected from the group consisting of 6-trimethylbenzoyl)-phosphine oxide) may be used.

The content of the photoinitiator may be 0.1 to 1 parts by weight, or 0.2 to 0.5 parts by weight based on 100 parts by weight of the slurry composition. In addition, the content of the photoinitiator 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 the present invention, the porous ceramic slurry composition may be prepared by mixing the above-mentioned components, that is, ceramic powder, photocurable monomer, diluent, dispersant, and photoinitiator. The mixing method may be performed according to a general method in the art.

In one embodiment, the preparation of the porous ceramic slurry composition may be performed at 50 to 80 °C or 60 to 75 °C. Since the freezing medium may be hardened like clay at room temperature, the slurry composition may be prepared at the above temperature. In addition, in the present invention, it is possible to perform uniform mixing using a ball milling machine.

In addition, in the present invention, the carbon black slurry composition includes carbon black, a viscosity modifier and a dispersant.

In the present invention, carbon black is removed during sintering to enable the production of a hollow tubular filament, that is, a hollow tubular structure. The carbon black may be included in the slurry composition in a volume of 5 to 20 vol% and 7 to 15 vol%.

In addition, the content of carbon black may be 5 to 40 parts by weight, or 10 to 25 parts by weight based on 100 parts by weight of the carbon black slurry composition. In the above content range, it is possible to manufacture a hollow tubular structure.

In the present invention, the viscosity modifier may control the viscosity of the slurry composition. At least one selected from the group consisting of camphene and urethane dimethacrylate (UDMA) may be used as the viscosity modifier.

The content of the viscosity modifier may be 60 to 95 parts by weight, or 70 to 85 parts by weight based on 100 parts by weight of the carbon black slurry composition.

Specifically, the content of campin in the viscosity modifier may be 50 to 70 parts by weight, or 55 to 65 parts by weight, based on 100 parts by weight of the carbon black slurry composition, and the content of the monomer, that is, urethane dimethacrylate, is 10 to 30 parts by weight. parts, or 15 to 25 parts by weight.

In the present invention, a dispersing agent may be used to facilitate dispersion of carbon black.

The type of the dispersant is not particularly limited, and for example, an alkylammonium salt copolymer compound, a polyester/polyether-based compound, a copolymer containing a phosphoric acid group, and a copolymer having an amine group. One or more selected from the group consisting of may be used.

The content of the dispersant may be 1 to 5 parts by weight, or 1 to 4 parts by weight based on 100 parts by weight of the carbon black slurry composition. A uniform carbon black slurry composition can be prepared within the above range.

In the present invention, the carbon black slurry composition can be prepared by mixing the aforementioned components, that is, a carbon black viscosity modifier and a dispersant. The mixing method may be performed according to a general method in the art.

In one embodiment, the carbon black slurry composition may be prepared at 50 to 80°C or 60 to 75°C. In the present invention, specifically, since a campin is used as a viscosity modifier, the hardening of the campin may occur at room temperature. Therefore, it is possible to prepare the slurry composition in a liquid state by preparing at the above-mentioned temperature. Also, in the present invention, it is possible to perform uniform mixing using a ball milling machine.

In the present invention, a core-shell feed rod may be manufactured using a porous ceramic slurry composition as a shell feed rod and a carbon black slurry composition as a core feed rod.

The core-shell feed rod according to the present invention comprises the steps of: (A) preparing a shell feed rod by injecting a porous ceramic slurry composition into a mold equipped with a shell supporter;

(B) removing the shell supporter from the mold; and

(C) injecting a carbon black slurry composition into the space from which the shell supporter is removed to prepare a core feed rod.

The conventional method of manufacturing a core-shell structure feed rod uses a method of manufacturing a core-shell feed rod by first hardening the core and then injecting a shell slurry around it. However, since the slurry composition used in the present invention contains a freezing medium and/or a viscosity modifier, it exists in a state having a viscosity of about clay at room temperature, and exists as a liquid at a temperature of 70°C. Therefore, when the conventional method is used, a phenomenon in which the core feed rod is melted occurs when the shell slurry is injected. Therefore, by manufacturing the feed rod by the method according to the present invention, it is possible to manufacture a stable core-shell feed rod.

In the present invention, step (A) is a step of preparing a shell feed rod by injecting a porous ceramic slurry composition into a mold equipped with a shell supporter.

In one embodiment, the shape of the mold is not particularly limited, and in the present invention, a cylindrical mold may be used for the convenience of 3D printing. In one embodiment, a syringe equipped with a discharge port may be used as a mold.

In one embodiment, the shell supporter is mounted inside the mold, specifically in the central portion to enable the manufacture of a shell feed rod with a hole in the center.

The material of the shell supporter is not particularly limited, and may be a metal material, specifically aluminum.

The shape of the horizontal cross-section of the shell supporter may vary depending on the shape of the core in the extruded filament. Specifically, the shape of the horizontal cross-section of the shell supporter may be circular.

In one embodiment, the porous ceramic slurry composition may use the aforementioned porous ceramic slurry composition as the shell slurry composition.

In one embodiment, step (A) may be carried out at 50 to 80 °C or 60 to 75 °C. In the above temperature range, the shell slurry composition has fluidity and may be injected into a mold to form a shell feed rod.

In the present invention, the step of hardening the shell feed rod before performing step (B) may be additionally performed. The above-mentioned temperature, that is, the slurry composition injected at 50 to 80 ℃ has fluidity. Therefore, by performing the hardening step at 20 to 25 ℃, it is possible to prevent the shape of the shell feed rod from collapsing when the shell supporter is removed.

In one embodiment, the hardening step may use a method of rapid cooling using dry ice.

In the present invention, step (B) is a step of removing the shell supporter from the mold in which the shell feed rod is manufactured by step (A).

In one embodiment, the shell supporter may be removed by removing the shell supporter from the mold in a vertical direction.

When the shell supporter is removed, the space where the shell supporter was located becomes empty. That is, it is possible to secure a space for the core feed rod.

In the present invention, step (C) is a step of preparing a core feed rod by injecting a carbon black slurry composition into the space where the shell supporter is removed.

In one embodiment, the carbon black slurry composition may use the aforementioned carbon black slurry composition as the core slurry composition.

In one embodiment, the carbon black slurry composition may be injected into the space from which the shell supporter is removed while being hardened at 20 to 25°C. The carbon black slurry composition hardened at 20 to 25°C maintains a high viscosity like clay.

In one embodiment, the step (C) may be carried out at 20 to 25 ℃.

In this temperature range, both the core feed rod and the shell feed rod maintain a high viscosity like clay. Accordingly, the core-shell feed rods may function as a core and a shell, respectively, without mixing with each other.

Further, the present invention relates to a core-shell feed rod manufactured by the method for manufacturing the core-shell feed rod described above.

The core-shell feed rod manufactured according to the above-described method has a structure in which the shell feed rod surrounds the core feed rod.

In the present invention, in order to control the hollow structure by the core feed rod and the microporous structure in the shell, the volume of the core feed rod and the shell feed rod can be controlled.

In one embodiment, the ratio of the volume of the core feed rod and the total volume of the core and shell feed rods (core feed rod volume: (core + shell) feed rod volume) is from 1:1.5 to 1:5 or from 1:1.5 to 1: can be 3 When the volume ratio of the core feed rod increases, the size of the hollow in the extruded filament may increase.

In addition, when the feed rod has a cylindrical structure, the ratio of the diameter of the core feed rod and the diameter of the core-shell feed rod may be 1:1.5 to 1:5 or 1:1.5 to 1:3.

In addition, the present invention relates to a method for manufacturing a hollow tubular porous structure using the photocurable three-dimensional plating method using the aforementioned core-shell feed rod.

The hollow tubular porous structure according to the present invention comprises the steps of (a) extruding and laminating a core-shell feed rod using 3D plating to prepare a scaffold;

(b) lyophilizing the scaffold; and

(c) it can be prepared through the step of heat-treating the lyophilized scaffold.

At this time, in step (a), the core-shell feed rod may be photocured by UV irradiation after extrusion.

In the present invention, in order to easily distinguish the products of the above steps, the product of step (a) is a scaffold, the product of step (b) is a green body or freeze-dried product, and the product of step (c) can be expressed as a sintered body. .

In the present invention, step (a) is a step of manufacturing a scaffold by extruding and laminating a core-shell feed rod using 3D plating. In this step, a scaffold may be manufactured by laminating the filaments extruded from the mold including the core-shell feed rod.

In the present invention, the hollow tubular porous structure may be manufactured by extruding the core-shell feed rod using 3D plating. Specifically, the structure may be manufactured by plating 3D drawing data according to a program designed in advance with a 3D computer. In the present invention, since the core-shell feedro is extruded and then photocured to have sufficient strength and maintain its shape, a separate support is not required (free-standing).

In the present invention, the core-shell feed rod extruded from the 3D plating nozzle can be expressed as a filament. The hollow tubular porous structure is a laminate of filaments.

In one embodiment, the manufactured structure may be a structure having a multi-layered layer of filaments, and one layer may be composed of filaments having one direction, and a constant interval may be formed between the filaments. At this time, one direction means that the filament is directed in one direction based on one layer. In addition, one layer is formed perpendicular to the other layer (a layer adjacent to one layer), and may have a microlattice (or grid) shape when viewed from above. In the present invention, the space between the microlattice may be expressed as pores, and the pores may be macro pores.

In the present invention, structures having various structures can be manufactured by controlling the extrusion pressure, the nozzle moving speed, and the intensity of the UV beam.

In one embodiment, in the core-shell feed rod, the extrusion pressure of the core feed rod may be 2 to 3 MPa, and the extrusion pressure of the shell feed rod may be 2.5 to 3.5 MPa. In the above extrusion pressure range, the core and the shell may have the same extrusion behavior. At this time, the extrusion pressure means the pressure when a load is applied at a rate of 1 mm per minute. In addition, the moving speed of the nozzle during 3D plating may be 4 to 30 mm/s or 8 to 20 mm/s.

Further, in one embodiment, the core-shell feed rod of the present invention may be photocured by ultraviolet irradiation after extrusion. Specifically, the core-shell feed rod is extruded from the nozzle and photocuring may be performed while it is in contact with the bottom or the surface of the already extruded filament. UV irradiation may be performed by a UV beam or the like.

That is, the filament extruded from the nozzle is photocured and solidified by the UV beam, and in this case, the intensity of the ultraviolet ray irradiated from the UV beam may be 1 to 5 W, or 2 to 4 W.

In the present invention, while the plate moves according to a pre-designed movement, the extruded filament is hardened in situ and solidified to form a structure.

Specifically, in the present invention, since the filaments continuously plated immediately form a scaffold (structure) at the position, it has the advantage that a significant reduction in working time is possible. In addition, since a process of removing unreacted raw materials is not required, loss of raw materials can be minimized, and the spacing between filaments can be more finely controlled when the structure is manufactured into a microlattice structure.

In one embodiment, the size of the nozzle may be appropriately adjusted according to the desired structure and density of the porous structure. In addition, the cross section of the nozzle hole may have a circular or polygonal shape.

In one embodiment, the feed rod extruded into a filament in the present invention has a core-shell structure. Accordingly, the cross-section of the extruded filament also has a core-shell structure in which the porous ceramic slurry composition surrounds the carbon black slurry composition.

In the present invention, by assembling two or more scaffolds of various shapes, it is possible to implement a composite scaffold having various shapes and capable of variously controlling the pore structure.

In the present invention, step (b) is a step of freeze-drying the scaffold prepared in step (a).

Through the freeze-drying, the freezing medium in the porous ceramic slurry composition and the viscosity modifier in the carbon black slurry composition can be removed.

The removed freezing medium forms micro-pores, and the micro-pores at this time may mean micro-sized pores.

In one embodiment, freeze-drying may be performed with equipment and conditions used in the art. Specifically, freeze-drying may be performed for 24 hours or more at a condenser temperature of -50 to -60°C and a pressure of 0.005 mTorr.

In the present invention, step (c) is a step of heat-treating the lyophilized scaffold.

In one embodiment, the heat treatment may be performed by dividing the first heat treatment and the second heat treatment.

The primary heat treatment is a degreasing process. In the heat treatment, monomers, dispersants, unreacted photoinitiators, carbon black, and the like in the freeze-dried product may be removed. The first heat treatment may be performed at 80 to 700° C., or 100 to 650° C. for 2 to 15 hours, or 4 to 8 hours. In addition, by performing heat treatment while increasing the temperature step by step, it is possible to more easily remove impurities.

In one embodiment, the primary heat treatment is heating from 20°C to 260°C at a rate of 5°C per minute (46 minutes), held at 260°C for 1 hour, and then heated to 415°C at a rate of 1°C per minute (2 time 35 minutes), maintained at 415° C. for 2 hours, heated to 600° C. at a rate of 5° C. per minute (37 minutes), and maintained at 600° C. for 1 hour.

The secondary heat treatment is a sintering process, and a sintered body may be manufactured by densifying the shell portion through heat treatment. The secondary heat treatment may be performed at 1000 to 1500° C. for 1 minute to 5 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 sintered body, that is, the hollow tubular porous structure may be changed.

In one embodiment, the secondary heat treatment may be performed by heating at a rate of 5°C per minute to 1250°C (2 hours and 10 minutes) and then maintaining the temperature at 1250°C for 3 hours.

In addition, the present invention relates to a hollow tubular porous structure manufactured by the method for manufacturing the aforementioned hollow tubular porous structure.

The hollow tubular porous structure according to the present invention has a structure in which two or more filaments are aligned in one direction, and the filaments have a hollow tubular structure. In addition, micropores are formed in the shell portion of the filament.

That is, in the present invention, it is possible to provide a porous structure having various shapes by manufacturing the hollow tubular porous structure by the method according to the present invention using 3D printing technology.

The porosity of the hollow tubular porous structure may vary depending on the content of the core feed rod, extrusion conditions, and the spacing between filaments. In one embodiment, the total porosity of the structure may be 60% or more.

Advantages and features of the present invention, and methods for 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

Experimental Example 1. Control of the extrusion behavior of the core and shell in the feed rod

Before the production of a feedrod having a core-shell structure for producing a hollow tubular structure, it is necessary that the core and the shell have the same extrusion behavior.

Therefore, in this experimental example, a feed rod of a porous ceramic slurry composition serving as a shell with a fixed composition in advance and a feed rod of a carbon black slurry composition having different carbon black contents serving as a core were prepared, and the feed rod was prepared at the same extrusion rate. was tested and each extrusion pressure was compared. Through this, the optimal carbon black content was investigated.

Specifically, the composition and content (g) of the porous ceramic slurry composition are shown in Table 1 below.

Freezing medium ceramic powder monomer dispersant photoinitiator campin camper HA UDMA KD-4 PPO HA slurry 33.18 16.59 59.2 15.2 4.14 0.3

In addition, the composition and content (g) of the carbon black slurry composition are shown in Table 2 below.

powder viscosity modifier dispersant carbon black campin UDMA KD-4 11g CB 11.1 40 15 1.47 13g CB 13 40 15 1.56

Extrusion behavior was measured by using a feed rod of HA slurry having a fixed composition and a feed rod of carbon black slurry having a different content, and extruding using a syringe equipped with a 17G nozzle having an inner diameter of about 0.97 mm.

The extrusion behavior measurement result is shown in FIG. 1 .

1 shows the results of comparison of extrusion behavior by extruding several contents of a slurry for similar extrusion of a core and a shell slurry in photocurable three-dimensional plating.

As shown in FIG. 1 , it can be confirmed that the extrusion pressure is maintained at a constant value after the extrusion pressure is rapidly increased as a result of the extrusion behavior test. And, it can be confirmed that 11g CB (9.5 vol%) has similar feed rod and extrusion behavior of the HA slurry.

Based on this experimental example, it was decided to fix the amount of carbon black in the carbon black slurry composition below to 9.5 vol%.

Example 1. Preparation of a feed rod for the implementation of a hollow tubular porous structure

(1) Confirmation and preparation of porous ceramic slurry composition and carbon black slurry composition

The amount of the freezing medium of the porous ceramic slurry composition forming the shell was set so that the porosity of the prepared ceramic sample was 60%, and the content was set so that the content of the sample was about 50 vol% when final sintering.

In a 125 mL polypropylene mouthpiece bottle, the freezing medium campin and camphor, ceramic powder, photocurable monomer, dispersant and photoinitiator were put, and mixed for 1 hour through a ball milling machine set at 70°C.

A carbon black slurry composition for forming the core was also prepared in the same manner as in the previous method.

The composition of the slurry composition is shown in Tables 3 and 4 below. Table 3 shows the composition of the porous ceramic slurry composition, and Table 4 shows the composition of the carbon black slurry composition.

Camphene: Camphene 95% (sigma aldrich, Germany)

Camphor: Camphor 96% (sigma aldrich, Germany)

HA: Hydroxyapatite (sunmedical. korea)

UDMA: Diurethane dimethacrylate 97% (sigma aldrich, Germany)

KD-4: Hypermer KD-4 dispersant (croda)

PPO: Phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide 97% (sigma aldrich, Germany)

Carbon black: (Cabot Black Pearls BP-120; Cabot Corp., Boston, MA, USA)

(2) Preparation of carbon black core-porous ceramic shell feed rod

In order to form a hollow tubular structure while co-extrusion of the two types of slurry compositions is performed, it is necessary to provide a core-shell structure feed rod.

Using the slurry composition described above in (1), a method for manufacturing a core-shell feed rod was secured.

In this embodiment, after manufacturing a shell feed rod with a hole in the center, a feed rod was manufactured by injecting a core slurry into an empty space.

In the present invention, FIG. 2 shows a process for manufacturing a core-shell feed rod using two types of slurries, namely, a porous ceramic slurry composition and a carbon black slurry composition.

Specifically, a custom-made shell supporter and a syringe were mounted as shown in the drawing. At this time, Figure 3 shows a photograph of the shell supporter (left) and the syringe (right) used in the present invention. After injecting the porous ceramic slurry into the syringe, the shell supporter was removed. A tubular core-shell feed rod was prepared by removing the shell cellter and injecting a pre-hardened carbon black slurry composition into the resulting empty space to form a core. At this time, the diameter of the core feed rod was 7 mm, and the diameter of the core-shell feed rod was 15 mm.

At this time, the core was prepared by putting the carbon black slurry composition in a separate syringe, hardening it at 20 to 25° C., and then injecting it into the empty space from which the shell supporter was removed through the inlet of the syringe.

Example 2. Structure Sample Preparation with Hollow Tubular Porous Structure

(1) Preparation of filaments and scaffolds using photocurable three-dimensional plating technology

In the present invention, Figure 4 shows a process of manufacturing a core-shell feed rod as a scaffold using a photo-curable three-dimensional plating technology.

As shown in FIG. 4, a scaffold was prepared by printing the core-shell feed rod prepared in Example 1 by irradiating light through a photocurable three-dimensional plating technique while extruding at a constant speed.

Existing photocurable three-dimensional plating only manufactures dense ceramic filaments and scaffolds, but in the present invention, filaments and scaffolds having a higher porosity than conventional ones can be manufactured.

(2) lyophilization of the prepared sample, and degreasing and sintering

In scaffold samples made through photocurable 3D plating, micropores can be formed on the spot by removing campin and camphor, which are freezing media inside. Therefore, the freezing medium was completely removed by drying for 24 hours or more at a condenser temperature of -60°C and a condition of 0.005 mTorr through a freeze-drying machine.

The freeze-dried samples were subjected to degreasing and sintering to remove monomers, dispersants, and remaining photoinitiators, and to densify ceramics.

Figure 5 shows a schematic diagram for the photocuring and freeze-drying process.

As shown in FIG. 5 , the porous ceramic slurry composition constituting the shell is photocured through UV irradiation, and then a freezing vehicle may be removed through a freeze drying process. A green body may be manufactured by the above process.

In addition, Table 5 below shows the degreasing and sintering steps for preparing a sintered body from the green body from which campin and camphor, which are freezing media, have been removed.

Experimental Example 2. Analysis of the macroscopic (macro) and microstructure of the sintered body

(1) Observation of internal structure of filament through optical microscope and FE-SEM

The core-shell feed rod was extruded in the form of filaments (extrusion rate: 156 mm/min) using a syringe equipped with a 17 G nozzle having an inner diameter of about 0.97 mm, and photocured (scaffold manufacturing). The scaffold was freeze-dried to prepare a green body, and the internal structure of the sintered body prepared by degreasing and sintering was confirmed through an optical microscope and FE-SEM.

The results are shown in FIGS. 6 and 7 .

6 shows the results of observing the internal structures of the filament-shaped green body (A) and the sintered body (B) through an optical microscope and FE-SEM.

As shown in FIG. 6 , as a result of checking with an optical microscope, it can be confirmed that there is carbon black in the center of the green body of the filament and ceramic on the outside.

After that, carbon black was completely burned out in the final sintered filament, and it can be seen that the diameter of the filament was reduced. Through this, it can be confirmed that the ceramic contracted through the sintering process.

In addition, as a result of observation through FE-SEM ( FIG. 7 ), it can be confirmed that carbon black disappeared after sintering. As a result of gradually magnifying the ceramic part in the green body of the filament, it can be confirmed that there are micropores within 10 μm. can confirm that there is

(2) Check the design and actual shape of the scaffold

The core-shell feed rod was extruded in the form of filaments using a syringe equipped with a 17 G nozzle having an inner diameter of about 0.97 mm and photocured (scaffold manufacturing).

At this time, the printing code was set so that each sample (scaffold) had a size of 16 x 16 x 15 mm. In addition, in order to show that the macroporosity can be adjusted as desired by controlling the filament gap inside the scaffold, scaffolds having different filament gaps were prepared.

8 shows a schematic diagram (A) of a three-dimensional design of a scaffold using a computer program and a green body and a sintered body (B) of the scaffold made after printing.

As shown in FIG. 8, when compared to the computer-designed three-dimensional design, the shape of each scaffold was almost similar, and the shape was maintained without large cracks and layer separation in the green body and sintered body. that can be checked

(3) The image of the internal structure of the sintered body confirmed through optical microscopy, FE-SEM and micro-CT

In order to confirm that the hollow tubular structure is uniform inside the sintered body, the inside was checked through an optical microscope and FE-SEM.

Specifically, in order to prevent catastrophic fracture during cutting of the sintered body, the inside of the sintered body was filled with an epoxy resin to harden, and then cut so that the hollow tubular structure inside the sintered body was uniformly seen.

9 and 10 show the results of observing the internal structure of the sintered body through an optical microscope and FE-SEM and micro-CT after hardening the prepared sintered body using an epoxy resin. indicates.

At this time, the sintered scaffold having a filament spacing of 0.5 mm and 1 mm was filled with an epoxy resin and taken.

In FIG. 9 (A), an optical microscope (B) shows an image taken through FE-SEM. In addition, FIG. 10 shows an image taken inside through micro-CT.

As can be seen from the optical microscope and FE-SEM images, it can be confirmed that there is a hollow tubular structure inside each filament. In addition, as a result of checking the internal structure of the sintered scaffold through micro-CT to confirm that this structure is uniform throughout the sintered body, it can be confirmed that a hollow tubular structure exists in all filaments of the sintered scaffold.

Therefore, it can be confirmed that the hollow tubular porous structure manufactured through the core-shell feed rod according to the present invention can have a hollow tubular structure inside all filaments.

Experimental Example 3. Measurement of porosity

(1) Measurement of total porosity and macro, microporosity

The porosity of the sintered body having different filament spacing was measured using different methods.

11 shows the results of measuring overall, macro, and micro porosity, respectively, using the presented formula, micro CT, and image J program. In the figure, the macroporosity is a value measured through micro-CT, and the microporosity is a value measured through the Image J program of an SEM image of a microporous ceramic part in a scaffold filled with an epoxy resin. The total porosity was calculated using the following formula.

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In the above formula, P means total porosity, pa means apparent density, and ps means theoretical density.

11, the total porosity of the sintered body having a filament spacing of 0.5 mm was 74.3±0.4%, and the macroporosity was measured to be 50.7%, and the total porosity of the scaffold having a filament spacing of 1 mm was 79.3± 0.5%, macroporosity was measured to be 64.6%. Also, the microporosity was approximately 60% similar for both 0.5 mm and 1 mm.

The difference in total and macroporosity is due to the difference in the size of macropores caused by having different filament spacing. The microporosity was similarly measured in the two sintered bodies because the two sintered bodies had the same freezing medium content of 60 vol%.

These results show that the size of macropores can be controlled by arbitrarily adjusting the filament spacing, thereby changing macro and overall porosity. Accordingly, it is shown that a ceramic structure having a hollow tubular porous structure having a desired porosity can be manufactured during scaffold manufacturing.

(2) Measurement of mechanical strength of sintered scaffolds

In order to confirm the mechanical properties of the sintered scaffolds having different filament spacing, that is, the sintered body, a compressive strength test through UTM was performed. All tests were performed so that the direction of the filament and the direction of applying the load were horizontal, and the load was applied at a constant rate of 1 mm/min.

12 shows the results of measuring the compressive strength of the sintered body having different filament spacing through a universal testing machine (UTM).

In FIG. 12, the graph on the right shows representative compression test behavior of the sintered body, and the bar graph on the left shows the average and standard deviation of maximum compressive strength and compressive modulus. In addition, the table below shows the numerical values of the bar graph data.

As shown in FIG. 12, it can be confirmed that both ultimate compressive strength and compressive modulus are larger in the sintered body having a filament spacing of 0.5 mm. This result seems to have occurred due to the difference in porosity of the sintered body at 0.5 mm and 1 mm intervals.

This result shows that a hollow tubular porous structure having a desired porosity and compressive strength can be made by controlling the filament spacing.

Claims (12)

preparing a shell feed rod by injecting a porous ceramic slurry composition into a mold equipped with a shell supporter;
removing the shell supporter from the mold; and
and injecting a carbon black slurry composition into the space from which the shell supporter is removed to prepare a core feed rod,
The porous ceramic slurry composition comprises 30 to 70 parts by weight of ceramic powder, 5 to 30 parts by weight of a photocurable monomer, 20 to 50 parts by weight of a freezing medium, 1 to 5 parts by weight of a dispersant, and a photoinitiator based on 100 parts by weight of the slurry composition,
The carbon black slurry composition comprises 5 to 40 parts by weight of carbon black, 50 to 70 parts by weight of a viscosity modifier, and 1 to 5 parts by weight of a dispersant based on 100 parts by weight of the carbon black slurry composition.
The method of claim 1,
In the porous ceramic slurry composition, the ceramic powder is hydroxyapatite (HA), fluoridated hydroxyapatite (FHA), tricalciumphosphate (TCP), biphasic calcium phosphate (BCP), alumina, zirconia (zirconina), silica (silica) and a method for producing a core-shell feed rod comprising at least one selected from the group consisting of bioglass.
The method of claim 1,
In the porous ceramic slurry composition, the photocurable monomer is 1,6-hexanediol diacrylate (HDDA), urethane dimethacrylate (UDMA), and acryloyl morpholine. and triethylene glycol dimethacrylate (TEGDMA).
The method of claim 1,
In the porous ceramic slurry composition, the freezing medium is campin, camphor, or a mixture thereof. A method for producing a core-shell feed rod.
The method of claim 1,
In the porous ceramic slurry composition and the carbon black slurry composition, the dispersing agent is each independently an alkylammonium salt copolymer compound, a polyester/polyether-based compound, a copolymer containing a phosphoric acid group, and a copolymer having an amine group A method of manufacturing a core-shell feed rod comprising at least one selected from the group consisting of.
The method of claim 1,
The photoinitiator in the porous ceramic slurry composition is phenylbis(2,4,6-trimethyl benzoylphosphine oxide) (PPO), 1-hydroxy-cyclohexyl-pennyl-ketone, 2-hydroxy-2-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 comprising at least one selected from the group consisting of a core-shell feed rod manufacturing method.
The method of claim 1,
In the carbon black slurry composition, the viscosity modifier is at least one selected from the group consisting of campin and urethane dimethacrylate (UDMA).
The method of claim 1,
The method for producing a core-shell feed rod, wherein the ratio of the volume of the core feed rod and the total volume of the core and shell feed rods is 1:1.5 to 1:5.
manufacturing a scaffold by extruding and laminating the core-shell feed rod manufactured by the manufacturing method according to claim 1 using 3D plating;
lyophilizing the scaffold; and
Comprising the step of heat-treating the lyophilized scaffold,
The method of manufacturing a hollow tubular porous structure in which the core-shell feed rod is photocured by ultraviolet irradiation after extrusion.
10. The method of claim 9,
A method of manufacturing a hollow tubular porous structure wherein the core feed rod has an extrusion pressure of 2 to 3 MPa and the shell feed rod has an extrusion pressure of 2.5 to 3.5 MPa when the core-shell feed rod is extruded.
10. The method of claim 9,
Freeze-drying is a method for producing a hollow tubular porous structure carried out at -50 to -60 ℃.
10. The method of claim 9,
After performing the first heat treatment for 2 to 15 hours at 80 to 700 ° C.,
A method of manufacturing a hollow tubular porous structure by performing a secondary heat treatment at 1000 to 1500 ℃ for 1 minute to 5 hours.

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