KR20140107865A - Method for producing porous scaffolds with unidirectionally macro-channel and porous scaffolds with unidirectionally macro-channel manufactured thereby - Google Patents

Abstract

The present invention relates to a method for producing porous scaffolds with a unidirectional macro-channel, which comprises the steps of: pouring slurry containing a precursor material forming a porous body, a dispersing agent, and a freezing medium into a cylindrical mold having a camphene rod at a central portion thereof, freezing the slurry at a temperature of a freezing point or less of the freezing medium, and extruding the slurry; stacking at least one extruded body and pressing the stacked extruded body; and freezing and drying the stacked body of the pressed extruded body to remove the freezing medium. The porous support with a unidirectional macro channel manufactured by the method according to the present invention has an excellent internal connecting porosity, has a dual porous structure, and can control the sizes of pores using a re-fusion phenomenon of the freezing medium. A complex structure can be directly manufactured by using a 3D robot instead of employing an existing method of indirectly making a complex structure using a mold.

Description

[0001] The present invention relates to a method for producing a porous support having unidirectional macrochannels and a porous support having unidirectional macrochannels manufactured by the method and a method for producing the porous support using unidirectionally macro-channels and porous scaffolds,

The present invention relates to a method for producing a porous support having a unidirectional macrochannel and a porous support having unidirectional macrochannels produced thereby.

Porous tubes and apertured fibers are one of the most widely used fields for fuel cells, piezoelectric devices, bioreactors, high temperature liquid / gas filters, and artificial bones. The production of these materials with relatively dense ceramic walls has been carried out by common methods such as extrusion, dip coating, injection molding and electrophoretic deposition. Therefore, in recent years, much attention has been focused on a new method for producing a material having a porous wall having a smooth liquid and gas exchange.

Examples of the method for producing such a porous ceramic wall material include extrusion of a ceramic paste containing fugitives including a melting material, centrifugal molding using organic pore-forming agents, Phase inversion / sintering process and freeze casting are used. However, the function of these materials is basically the same as that of the porous structure of the material, that is, the porosity, pore size, Shape and the like, there is a need for a new technique for easily controlling the pore structure.

Currently, the most effective method of forming a porous tubular support having a porous ceramic wall is a ceramic paste extrusion method. In this method, a support is prepared by adding a pore forming agent such as graphite, polymer and the like to the paste and extruding it [Non-Patent Document 1 ,2]. The above method has a problem in that it is troublesome to separately manufacture specially manufactured equipment (such as a tubular extruding die) and an uneconomical surface due to separate manufacture. Since the extrusion is performed in a structure in which the center is empty, There is a risk of destruction. Moreover, even if graphite, polymer or the like is filled in the center, there is a risk that the entire structure may collapse during the burnout process.

In addition, a casting technique using an indirect method is used to produce a porous support having a complicated shape (for example, a porous support having a unidirectional macrochannel). However, when the indirect method is used, there is a fear that the mold is separately manufactured and the ceramic is deformed and destroyed in removing the mold. One of the biggest problems of this method is that it can not easily change the structure.

Therefore, there is a need to develop a new technique capable of manufacturing a porous support having a complicated shape to overcome such disadvantages.

1. C. Kaya, S. Blackburn / Journal of the European Ceramic Society 24 (2004) 3663-3670 2. T. Isobe et al. / Journal of the European Ceramic Society 26 (2006) 957-960

 Accordingly, the inventors of the present invention have completed the present invention by developing a technique for manufacturing a porous support having a complicated pore structure by directly manufacturing a composite structure through a robot with the advantages of a coextrusion method and a 3D robot, .

Accordingly, it is an object of the present invention to provide a method of extruding a slurry containing a precursor (for example, a ceramic powder) constituting a porous body and freely manufacturing a structure desired by a user through the robot.

It is another object of the present invention to provide a porous support having a unidirectional macrochannel produced by the above method.

As means for solving the above problems,

Pouring a slurry containing a precursor, a dispersant and a freezing medium constituting a porous material into a cylindrical mold having a cam pin bar at its center, freezing and extruding the frozen medium at a freezing point or below;

Laminating at least one shaped body extruded in the step and pressing the laminated body; And

And lyophilizing the laminate of the pressed compact in the above step to remove the freezing medium. The present invention also provides a method of manufacturing a porous support having unidirectional macrochannels.

In addition, as another means for solving the above problems, the present invention provides a porous support having a unidirectional macrochannel capable of arbitrarily controlling a complicated structure.

According to another aspect of the present invention, there is provided a porous filter or scaffold structure including the porous support having the unidirectional macrochannel.

The present invention can arbitrarily manufacture a porous support having a complicated structure and control of a pore structure by using a co-extrusion method and a 3D robot.

In addition, the porous support having unidirectional macrochannels manufactured by the production method according to the present invention is excellent in internal connection pores, has a double pore structure, and can control the pore size using the remelting phenomenon of the freezing medium.

In addition, instead of the conventional method of creating a complicated structure using a mold indirectly using a 3D robot, a complicated structure can be directly manufactured.

FIG. 1 is a photograph (a) and a schematic view (b) showing a co-extrusion system and a 3D robot used in a method of manufacturing a porous substrate having a macro channel according to an embodiment of the present invention.
2 is an actual photograph and a micrograph of a porous support having a macrochannel manufactured by an example of the present invention.
FIGS. 3 and 4 are scanning electron microscopy (SEM) photographs showing the cross-sectional structure (FIG. 3) or the inner surface structure (FIG. 4) of the porous support having macrochannels prepared according to Examples 1 to 3.

The present invention relates to a method for producing a porous membrane, which comprises the steps of pouring a slurry containing a precursor, a dispersant and a freezing medium constituting a porous material into a cylindrical mold having a cam pin rod at the center thereof and freezing and extruding the freeze-

Laminating at least one shaped body extruded in the step and pressing the laminated body; And

And lyophilizing the laminate of the pressed compact in the above step to remove the freezing medium. The present invention also relates to a method for producing a porous support having unidirectional macrochannels.

A method of preparing the porous support having the macrochannel will be described in detail below.

First, the first step is a step of pouring a slurry containing a precursor, a dispersant and a freezing medium constituting a porous article into a cylindrical mold having a cam pin bar at its center, freezing at a freezing point of the freezing medium or below and freezing and extruding the slurry, Can be prepared by dispersing a precursor material forming a porous body in a freezing medium.

The precursor constituting the porous body contained in the slurry is not particularly limited as long as it is a material capable of producing a porous body, and specifically, a ceramic powder or the like can be used.

The type of the ceramic powder is not particularly limited and may be selected from the group consisting of calcium phosphate such as Hydroxyapatite (HA), Fluoridated Hydroxyapatite (FHA), Tricalcium Phosphate (TCP) At least one selected from the group consisting of biphasic calcium phosphate (BCP), alumina, zirconina, silica, and bioglass can be used.

The average particle size of the ceramic powder is not particularly limited and may be 0.3 to 45 탆, specifically 0.5 to 40 탆, more specifically 1 to 30 탆. It is easy to disperse in the freezing medium in the above range.

The freezing medium contained in the slurry can be used not only as a freezing medium for freeze-molding in the present invention but also as a binder. The type of the freezing medium is not particularly limited, and camphene, campho, naphthalene, or the like can be used. Specifically, camphin can be used.

The content of the freezing medium is not particularly limited and may be 80 to 500 parts by weight, specifically 100 to 400 parts by weight, more specifically 120 to 300 parts by weight based on 100 parts by weight of the precursor constituting the porous body. If the content is less than 80 parts by weight, the strength of the porous support may be too weak to be easily broken. When the content exceeds 500 parts by weight, It is difficult to prepare a slurry having a viscosity suitable for extrusion molding.

The slurry according to the present invention comprises a dispersing agent for uniformly mixing the freeze medium and the precursor constituting the porous body. The kind of the dispersant is not particularly limited as long as a uniform slurry can be formed. For example, an oligomeric polyester may be used.

The content of the dispersing agent is not particularly limited and may be in the range of 0.5 to 20 parts by weight, specifically 1 to 15 parts by weight, more specifically 1.5 to 12 parts by weight, based on 100 parts by weight of the precursor constituting the porous body. If the content is less than 0.5 parts by weight, the precursor particles may aggregate with each other, making it difficult to produce a slurry having a uniform composition. If the amount exceeds 20 parts by weight, There is a concern.

In the present invention, since the slurry is prepared in a liquid phase, the dispersion of the precursor constituting the porous material is performed at a temperature above the melting point of the freezing medium. Here, the method of dispersing and uniformly mixing the precursors is not particularly limited. For example, a method of mixing using a hot plate with easy temperature control, a method of mixing Can be used. In the present invention, the latter method can be used for mass production.

In the slurry according to the present invention, the freezing medium serves as a binder, but since the freezing medium, for example, the cam pin, is removed in the process described below, the precursor forming the porous body after the freezing medium is removed is better retained in shape The slurry may further comprise a polymeric binder. The type of the polymeric binder is not particularly limited as long as it can reproduce the shape of the pore structure. Specifically, the polymeric binder is composed of a water-soluble water-soluble polymer such as polyvinyl alcohol, polyethylene glycol, polyvinyl butyral, gelatin and chitosan, and polyethylene oxide One or more selected from the group can be used.

The content of the polymeric binder is not particularly limited and may be in the range of 0.5 to 20 parts by weight, specifically 1 to 15 parts by weight, more specifically 1.5 to 12 parts by weight, based on 100 parts by weight of the precursor constituting the porous material. If the content of the polymeric binder is less than 0.5 parts by weight, there is a problem that the strength of the extruded molded article is lowered. When the content of the polymeric binder exceeds 20 parts by weight, cracking may occur during sintering

The slurry according to the present invention is present as a homogeneous slurry in a liquid state, which is a slurry having a desired viscosity for producing a slurry for extrusion molding, wherein the viscosity of the slurry is 0.1 to 10 Pa.s at 60 DEG C, 0.5 to 8 Pa 占 퐏, and more specifically, 1 to 5 Pa 占 퐏.

In the present invention, the prepared slurry is poured into a cylindrical mold having a cam pin bar at its center, and the pores are aligned by freezing after freezing at a freezing point of the freezing medium and extruding.

The cam pin is used as a binder (cam pin rod) for co-extrusion, and at the same time, has a pore structure different from that of the pore structure (Freezing medium), there is no risk of deformation or destruction because it does not require specially manufactured equipment as compared with the technology of making other tubular supports, nor does it require heat treatment for blowing the binder.

That is, in the above step, a pure camphin is used as a rod at the center to form a tube-shaped porous support, specifically, a porous support having a channel formed therein, and the outer wall is made of a precursor material and a freezing medium When the cam pin is removed after extrusion, a channel formed by the cam pin bar is formed at the center, and a porous support having porous pores is formed on the outer wall.

The average diameter (diameter) of the camphin rods is not particularly limited, and the average diameter (diameter) of the camphin rods after extrusion described later may be 500 to 1000 占 퐉, specifically 600 to 900 占 퐉, more specifically 700 to 800 占 퐉. A porous support having excellent physical properties within the above range can be produced.

In the present invention, the freeze-molding can be carried out at a temperature not higher than the melting point of the freezing medium, that is, -20 to 40 ° C, specifically -10 to 20 ° C, more specifically 0 to 10 ° C, So that the slurry can be maintained in a stable state. Further, the extrusion speed during extrusion can be controlled within the range of 0.5 to 10 mm / min, specifically 0.8 to 8 mm / min, more specifically 1 to 5 mm / min, so that the extruded molded body can be produced in a stable state.

 The second step is a step of laminating at least one extruded molded body and pressing the extruded molded body, and the lamination of the extruded molded body can be performed through a 3D robot.

Specifically, the molded body extruded in the previous step can be programmed and stacked by a user in a desired structure using a 3D robot. Thereby, it is possible to easily produce a molded article laminate having a complicated structure.

The speed of the robot when stacking the molded bodies can be controlled according to the extrusion speed. In particular, in the present invention, the laminate can be laminated so that the cambin bars formed at the center of the molded article form a parallel structure. That is, the cambin bars of the laminated molded article have a structure aligned in one direction, and when the cambin bar is removed, a channel aligned in one direction is formed. Further, when the molded body is laminated, the deformation of the laminated structure can be minimized by using the mold.

A photograph and a schematic diagram of such a 3D robot are shown in Fig. As shown in FIG. 1, the 3D robot is connected to a co-extrusion system (co-extruder) for extruding a molded body so that the molded body extruded in the co-extrusion system can be aligned and laminated in one direction. Specifically, the extruded molded body can be aligned in a plurality of zigzags and laminated a plurality of times.

The laminate is then laminated, and then the laminate is pressed. In this case, the pressing may be performed within a range in which the structure of the laminate is not completely deformed. Through the above pressing, the adhesion between the precursors constituting the molded body, that is, the porous body constituting the outer wall of the molding can be improved.

The third step is a step of lyophilizing the laminate of the press molded article to remove the freezing medium. By this step, a porous support having a unidirectional macrochannel is produced.

In the present invention, a process of pretreating the laminates before freeze-drying can be further performed. The pretreatment is carried out under the melting point of the freezing medium. The freezing medium is grown through the pretreatment to enlarge the pore size while maintaining the pore structure, and to induce a difference in pore structure between the portion directly contacting the freezing medium and the portion not contacting the freezing medium can do.

Specifically, the pretreatment may be performed at 20 to 50 ° C, specifically at 25 to 45 ° C, for about 1 to 15 hours, specifically for about 2 to 10 hours, near the solidification temperature (melting point) of the slurry. If the pretreatment temperature is less than 20 ° C, dendritic growth of the camphin can not be induced and there is no change in the pore structure. If the pretreatment temperature is more than 50 ° C, the camphin melts and the porous form can not be maintained. Thus, the pore size can be controlled through the pretreatment, and the strength is enhanced by better aggregation of the precursor particles forming the porous body.

In the present invention, freeze-drying can be carried out at a temperature of -196 to -10 ° C, specifically -180 to -20 ° C and 0.1 to 20 mTorr, specifically 1 to 10 mTorr. The freezing medium can be easily removed without damaging the laminate of the molded body at the above temperature and pressure.

The freezing and thawing media formed by the freezing and drying of the cam pin bar and the molded body wall are removed to form unidirectional macrochannels in the laminate, and unidirectional macrochannels having a double pore structure having porous pores A porous support is prepared.

In addition, in the present invention, the porous support wall can be further densified by performing the sintering process after removing the freezing medium.

The sintering may be performed at 1300 to 1600 ° C for 1 to 5 hours. If the sintering temperature is too low or the time is too short, there is a fear that the mechanical strength is lowered and the polymer binder and the dispersant are not removed well. If the sintering temperature is too high or too long, the chemical composition may be changed .

The present invention also relates to a porous support having a unidirectional macrochannel produced by the above method.

In particular, the porous tubular support has a structure in which channels having an average diameter (diameter) of 300 to 1000 탆, specifically 400 to 900 탆, more specifically 500 to 800 탆, are aligned in one direction, And thus can be utilized as a bone substitute material.

In addition, the size (average particle size) of pores formed in the support wall in the porous support having unidirectional macrochannels of the present invention is not particularly limited and may be 10 to 300 탆, specifically 30 to 200 탆.

The porous support having the unidirectional macrochannel may satisfy the following general formula (1)

[Formula 1]

5? X? 50

X represents the compressive strength (MPa) measured at a crosshead speed of 1 mm / min of the universal testing machine (OTU-05D).

The present invention also relates to a product comprising a porous support having said unidirectional macrochannels.

Since the porous support having unidirectional macrochannels according to the present invention has a double pore structure and excellent physical properties, it can be used not only in a porous filter or a bone filler but also in a piezoelectric device, a bioreactor or a fuel cell field.

The present invention relates to a new method for manufacturing a porous support which can co-extrude a camphin based on a porous material and directly produce a complicated structure using a 3D robot. The unidirectional macrochannel manufactured by this method The porous support having a porous structure having an aligned pore structure (channel structure) can have mechanical properties (strength) much higher than those of existing materials. In addition, since the coextrusion method has the merits of extrusion, it is not limited in length and can be mass-produced in producing a porous support having a unidirectional macrochannel.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by the following examples.

Example 1: Preparation of Porous Ceramic Support

Alumina powder in circulation [high purity particle size 0.3 ㎛, Kojundo Chem-ical Co. , Ltd, Japan) 8 g and the cam pins _{[C 10 H 16, Alfa Aesar} / Avocado Organics, Ward Hill, MA, USA] 10 g of the porous body And freezing medium, respectively. And 0.25 g of an oligomer polyester (Hypermer KD-4, UniQema, Everburg, Belgium) as a dispersant was ball-milled at 60 DEG C for 24 hours to prepare a slurry. At this time, the viscosity of the slurry was about 1 Pa.s at 60 占 폚.

A solid camphin with a diameter of 10 mm (average diameter) was prepared as a camphin rod to be used as a core in the center to make an initial structure for coextrusion. The slurry was poured into a die having a diameter of 20 mm (after placing the cam pin rod in the center) and waited for solidification at room temperature for about 30 minutes.

The mixture was co-extruded at a rate of 1 mm / min at room temperature using a universal material tester (OTU-05D, Oriental TM Corp., Korea) through a hole with an extrusion size of 1 mm in diameter.

The extruded molded body was laminated by using a 3D robot, and the molded body extruded with a diameter of 1 mm was zigzag so as to be 10 mm in the lateral direction, and the number of times of lamination was set to 5 mm in the height direction. Thereafter, the stacked laminate was pressed in a pressure range of 1 MPa.

The laminated laminate was pretreated at 43 DEG C for 6 hours for continuous growth on the camphin resin. Then, the camphin was removed by freeze drying (-54 ° C, vacuum of 10 mTorr or less) and sintered at 1500 ° C. for 3 hours in order to densify the alumina wall to prepare a porous support having unidirectional macrochannels.

Example 2

A porous support having unidirectional macrochannels was prepared in the same manner as in Example 1, except that 12 g of alumina powder and 0.5 g of dispersant were used.

Example 3

A porous support having unidirectional macrochannels was prepared in the same manner as in Example 1, except that 16 g of alumina powder and 0.75 g of dispersant were used.

Experimental Example : Confirmation of property improvement

1) Experimental process

(FE-SEM; JSM-6701F; JEOL Techniques, Tokyo, Japan) was used to confirm the aligned pore structure of the porous support on which the unidirectional macrochannel prepared in Examples 1 to 3 was formed .

The porosity of the porous support formed with the unidirectional macrochannel was calculated by its cross-sectional area and weight. The size of the pores was calculated by photographing a field-emission scanning electron microscope of a sample filled with epoxy. The compressive strength was measured to evaluate the structure of the channel with aligned pore structure. The compressive strength was measured by using a universal testing machine (OTU-05D, Oriental TM Corp., Korea) at a crosshead speed of 1 mm / min.

2) Experimental results

2 shows an actual photograph of a porous support sample having a unidirectional macrochannel manufactured by an embodiment of the present invention. The porous support having al prepared aromatic macrochannel has a width of 10 mm and a height of 40 mm, respectively.

3 and 4 show cross-sectional and internal structures of a porous support having al directional macrochannels prepared according to Examples 1 to 3 in the present invention.

Specifically, FIGS. 3 and 4 (A) and 4 (D) show Example 1, (B) and (E) show the cross-sectional structures of the porous support according to Example 2, Show inner structure.

The aligned pore structure of the porous support wall is best illustrated in Figures 3 and 4. The pore structure aligned with the pore structure, such as the honeycomb structure, is shown in FIG. 3, respectively, and the pore structure in the aligned direction is shown in FIG. This shows the successful manufacture of a support having an aligned pore structure due to replication of the well-laid camphin resin due to co-extrusion. In FIG. 4, unlike the conventional pore structure, the pore structure directly contacting the cam pin is much larger than that of the conventional pore structure, which can facilitate the growth of bone when used as a bone filler.

Table 1 below shows the porosity and compressive strength of the porous support prepared according to Examples 1 to 3.

The porosity of the porous support prepared according to the Examples was measured to have a high porosity of about 60% or more. In addition, the compressive strength was found to have a high strength of about 10 MPa or more.

Porosity  [%] Strength  [ MPa ] ( normal ) Example 1 83 ± 0.6 12.2 ± 3.3 Example 2 76 ± 0.9 12.9 ± 1.9 Example 3 67 ± 4.5 16.5 ± 2.5

One of the most important advantages of the process according to the invention is that the porous support has at least one unidirectional macrochannel and the pores of the porous support can have a pore structure aligned in the support wall (in particular, The degree of connection is excellent), which can not be obtained through the extrusion method using existing pore former. Fundamentally, the camphin resinous phase forms a three-dimensional network of pores within the support wall and contributes to the connectivity of aligned pores even after co-extrusion. Another notable feature of the method is the possibility of using various materials (ceramics, metals, etc.) and is applicable to various fields (filters, bone substitutes, bone fillers, fuel cells, gas / liquid separating agents, etc.).

Claims (13)

Pouring a slurry containing a precursor, a dispersant and a freezing medium constituting a porous body into a cylindrical mold having a cam pin rod at its center, freezing the freezing medium at a freezing point of the freezing medium, and extruding the slurry;
Laminating at least one molded body extruded in the step and pressing the laminated body; And
And lyophilizing the laminate of the pressurized molded article to remove the freezing medium.
The method according to claim 1,
A method for producing a porous support having a unidirectional macrochannel as a ceramic powder as a precursor constituting a porous article.
The method according to claim 1,
Wherein the dispersing agent is an oligomer polyester.
The method according to claim 1,
Wherein the freezing medium is a camphin, a campo or a naphthalene.
The method according to claim 1,
Wherein the slurry further has a unidirectional macrochannel that further comprises a polymeric binder.
The method according to claim 1,
Wherein the freezing is performed at -20 to < RTI ID = 0.0 > 40 C < / RTI >
The method according to claim 1,
Wherein the stacking of the extruded molded body has a unidirectional macrochannel carried out through a 3D robot.
The method according to claim 1,
Wherein the lamination of the extruded molded bodies has unidirectional macrochannels in which the cambin rods formed in the center of the at least one formed body are laminated so as to face in one direction.
The method according to claim 1,
Further comprising the step of pretreating the laminate of the press molded article at 20 to 50 DEG C for 1 to 15 hours before freeze-drying the laminated article.
The method according to claim 1,
Wherein the freeze-drying of the laminate of the press molded article is carried out at -196 to -10 DEG C and 0.1 to 20 mTorr.
The method according to claim 1,
Further comprising sintering at 1300 to 1600 캜 for 1 to 5 hours after freeze-drying.
11. A porous support having a unidirectional macrochannel which is manufactured by the method according to any one of claims 1 to 11 and has a structure in which one or more channels having an average diameter of 300 to 1000 占 퐉 are aligned in one direction.
A porous filter or bone filler comprising a porous support having unidirectional macrochannels according to claim 12.

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