KR101780475B1 - Method of 3D Printing by Formation of Filaments - Google Patents

Abstract

In the present invention, since a filament can not be used in a 3D printer or can not be stored in a filament for a long period of time, a polymer that can not be used in the FDM method is formed into a filament in situ and used in a 3D printer The 3D printing method according to the present invention is useful in that various polymers that can not be used in a conventional FDM type 3D printer can be used.

Description

[0001] The present invention relates to a three-dimensional printing method capable of continuously forming a filament,

The present invention relates to a 3D printing method using a filament, and more particularly, to a 3D printing method using filament, which can not be used in a 3D printer in a powder form or can not be stored for a long period of time. The present invention relates to a method of forming a variety of products using a 3D printer while molding the polymer in a filament form in situ through melting, compression, and cooling processes.

3D (3-Dimension, 3-D) printer is a device that produces three-dimensional objects by stacking layers with fine thickness by sequentially injecting ink of a special material. 3D printing is spreading in various fields. In addition to the automotive field consisting of many parts, it is used by many manufacturers for a variety of applications ranging from household products such as medical manikins, toothbrushes, razors, and clothing.

The 3D printing method is divided into three types according to the type of the ink material used for printing. First, a method using a liquid-based ink material is a method of layering a desired molding material by using a UV laser to a photo-curable resin, and it is advantageous that precise molding approaching the original shape is possible. However, And the durability is deteriorated. Stereolithography (SLA), digital light processing (DLP), and polyjet method are examples of photocurable printing methods.

A method using a powder-based ink material is a method in which a molding material is printed through a process of melting or sintering a synthetic resin or a metal material made in powder form, and various raw materials from synthetic resin to metal and ceramics can be used. Although it has the advantage of being stronger than the result obtained by the photo-curing process of raw materials, it has a disadvantage in that it can not use transparent materials, color materials and flexible materials. Powder-based methods include selective laser sintering (SLS), direct metal laser sintering (DMLS), and electron beam melting (EBM).

The solid-based method is a method in which a solid material is poured or melted to form a molding. The laminated object manufactruing (LOM) method is a method in which a thin paper raw material is stacked one by one and cut in the shape of an object. Deposition modeling (FDM) is a method of melting filamentary raw materials and stacking them one by one. The FDM method was developed by S. Crump in the United States in 1988, and commercial products were launched at strastasys in 1990. At present, the period of original patent expires and various products are being marketed. The solid-based method has advantages in that the material strength is superior to the liquid-based method, and the color material can be used, although the precision and surface fineness are less than those of the liquid / powder-based method.

In terms of ink materials, the most commonly used material is photopolymer, which is a photocurable resin that solidifies when exposed to light. This accounts for 56% of the total market. The next most popular material is solid, thermoplastic, which is free to melt and solidify. It occupies 40% of the market and metal powder is expected to grow gradually in the future. The shape of the double thermoplastics material may be in the form of filaments, particles or powder powders. Filament-type 3D printing is faster than other types in terms of speed, so productivity is high and diffusion speed is fast.

Polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), HDPE (high density polyethylene), and polycarbonate (PC) are used as the existing filament materials. First, since the melting point is moderately high, the solidification speed is fast after printing, so that even if the printing speed is fast, it is not deformed and the dimensional and shape stability are good. Second, since the melting point is moderately low, the extrusion is easy and the production efficiency is high when the filament is manufactured. In addition, if the melting point is too high, it is necessary to dissolve the filament, which consumes a lot of electric power, and the parts in the printer must be made of a material capable of withstanding high temperatures.

The above-mentioned four materials are suitable for the above-mentioned various conditions. All of them are high hardness materials having Shore D hardness of 50 or more and can not satisfy the requirement as a 3D printing material requiring a soft feeling of low hardness . In addition, polymers in powder form that can not be stored for a long period of time or polymers that can not be used as a 3D printing material in powder form can not be used for 3D printers by the FDM method.

The present inventors have made efforts to use various polymers which can not be used in the conventional FDM method for 3D printing. As a result, they have found that polymer powder is produced in situ in a filament form by melting, extruding and cooling processes, And it is confirmed that a polymer which can not be used in the conventional FDM method can be used as a material for a 3D printer, thus completing the present invention.

It is an object of the present invention to provide a 3D printing method through formation of filaments of thermoplastic polymers having a Shore D of 50 or less.

(A) melting a thermoplastic polymer powder having a shore D of 50 or less and melting the polymer powder; (b) extruding and cooling the melt of step (a) to form a filament; (c) feeding the filament of the formed step to the printhead of the 3D printer; (d) discharging the melted material of the 3D printer filament heated from the printhead; And (e) solidifying the discharged melt to form a 3D product.

The 3D printing method through filament formation according to the present invention is advantageous in that a polymer which can not be used in the conventional FDM method can be utilized for 3D printing.

FIG. 1 is a photograph of an experiment in which a powdery polymer is produced in the form of a filament using an extruder.
Fig. 2 is a photograph comparing the shapes of the filament of the third party filament and the extruded filament.
3 is a photograph of a 3D product obtained by directly feeding an extruded filament to a 3D printer head.
FIG. 4 is a photograph of a 3D product printed with a bone chip type bone graft scaffold mixed with an extruded filament and β-TCP powder at 10% in different lengths of strands.
FIG. 5 is a photograph of a 3D product printed with a bone chip type bone graft scaffold mixed with extruded filaments and 30% of β-TCP powder by different sizes of nozzles.
FIG. 6 is a photograph of a 3D product printed with different lengths of a strand by a bone graft scaffold in the form of a bone chip in which 50% of the extruded filament and β-TCP powder are mixed
Fig. 7 shows the results of an experiment in which the extruded filaments and the scaffold including β-TCP were examined for biocompatibility.
FIG. 8 is a graph showing the results of experiments measuring bone-differentiation inducing activity of extruded filaments and cells inoculated into a scaffold containing β-TCP.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.

In the present invention, it was confirmed that the present invention can be used in 3D printing by forming in situ filaments of polymers which can not be used in the conventional FDM method.

In one embodiment of the present invention, the bioabsorbable polymer powder and the physiologically active substance are mixed and then melted, extruded and cooled to form a filament in situ , and the formed filament is 3D printed to form a bone graft scaffold .

Accordingly, in one aspect, the present invention provides a method for producing a thermoplastic resin composition, comprising: (a) melting a thermoplastic polymer powder having a shore hardness of 50 or less; (b) extruding and cooling the melt of step (a) to form a filament; (c) feeding the formed filament to a print head of a 3D printer; (d) discharging the melted material of the 3D printer filament heated from the printhead; And (e) solidifying the discharged melt to form a 3D product.

In the present invention, at least one selected from the group consisting of a colorant, a flame retardant, a plasticizer and a physiologically active substance may be further added when the polymer powder is melted.

In the present invention, the polymer powder may be used as a polymer having a Shore D value of 50 or less and being a thermoplastic polymer without any bonding. Preferably, the polymer powder is selected from the group consisting of polyglycolic acid (PGA), polylactic acid (PLA), poly- (PLLA), poly-D-lactic acid (PDLA), chitosan, acrylonitrile butadiene styrene (ABS), polyamide, polycarbonate (PC), polyethylene, polypropylene Polyvinyl alcohol (PVA), polyurethane, epoxy, acryl, polyethylene glycol (PEG), polyvinyl pyrrolidone (PVP), polystyrene (PS), polyacryl ether ketone (PAEK) (POM), and polymethylmethacrylate (PMMA). ≪ Desc / Clms Page number 7 >

In the present invention, the polymer powder may have a particle size of 50 to 10 mm.

In the present invention, the temperature at which the melting of step (a) is performed may be performed at a temperature range suitable for the kind of the thermoplastic polymer powder selected, but may be performed at, for example, 100 to 300 ° C .

In the present invention, the step (b) may be characterized in that the melt is injected at a rate of 0.5 to 3 m / min at a pressure of 50 to 300 kpa to be formed into a filament form.

In the present invention, the filaments of the step (b) may have a diameter of 0.1 to 2.0 mm.

According to the printing method of the present invention, since the polymer can not be used in a 3D printer or can not be stored for a long period of time in a powder form, it is possible not only to mold a polymer into filaments that could not be used in the conventional FDM method, Improved products can be produced.

Hereinafter, the present invention will be described in more detail with reference to Examples. It is to be understood by those skilled in the art that these embodiments are only for illustrating the present invention and that the scope of the present invention is not construed as being limited by these embodiments.

Example 1: Preparation of PLLA + beta-TCP bone graft material

The PLLA powders were mixed at 10% or 30%, melted at 190 to 210 DEG C, extruded at a rate of 1 m / min with a pressure of 100 kPa, cooled at 4 DEG C to form filaments, A scaffold having various strand thicknesses and porosities of various sizes was manufactured under the conditions of a pressure of 400 to 900 kPa and a velocity of 40 to 900 mm / min. The manufacturing conditions used at this time are shown in Table 1.

β-TCP 30% Manufacturing conditions Length 8mm 6mm 4mm Nozzle Size (mm) 0.3 Strand diameter /
Pore size (mm) 0.3 / 0.3 Temperature (℃) 190-210 Speed (mm / min) 60-70 Pressure (kPa) 800-900

A bone graft scaffold was prepared by mixing PLLA powder with 10% of β-TCP powder. The scaffold structure of 8 mm, 6 mm and 4 mm according to the length of the strand is shown in FIG.

When mixing the β-TCP powder with PLLA powder at 30%, it may be difficult to obtain a uniform diameter strand and porosity when the nozzle is changed during the manufacture of the scaffold. The structure of the scaffold manufactured using the 0.4 mm nozzle and the 0.5 mm nozzle diameter according to the diameter of the nozzle is as shown in Fig. It has been difficult to manufacture a scaffold in which uniformity and sufficient porosity are secured so as to be suitable for bone grafting when the nozzle is changed from a 0.4 mm nozzle to a 0.5 mm nozzle.

Plasma powders were mixed with 50% of β-TCP powder and the same results were obtained in the scaffold prepared under the conditions of Table 2. The structure of the scaffold of 8 mm, 6 mm and 4 mm according to the length of the strand is shown in Fig. 6, and it can be confirmed that it is difficult to fabricate a scaffold having a porosity suitable for a uniform diameter strand and bone graft material.

β-TCP 50% Manufacturing Conditions Length 8mm 6mm 4mm Nozzle Size (mm) 0.5 Strand diameter /
Pore size (mm) 0.4 / 0.4 Temperature (℃) 210 Speed (mm / min) 300-420 300 600 Pressure (kPa) 900 Operating time 1 minute 40 seconds 47 seconds 13 seconds

Test Example 1: Analysis of cell proliferation characteristics according to beta-TCP content

To confirm the biocompatibility of the prepared PLLA and PLLA + β-TCP scaffolds, proliferation and differentiation were measured using MG-63 cells. Cells were divided into three groups: PLLA, PLLA + β-TCP10% and PLLA + β-TCP30. Cells were sterilized for 20 min under 70% ethanol and UV. Cells were plated at 8 × 10 ⁶ / After inoculation, the scaffold media solution was changed daily and 1, 4, and 7 days later, cell proliferation assays were performed using the WST-1 kit. As shown in FIG. 7, the higher the concentration of β-TCP, the more proliferation of bone cells was confirmed.

Test Example 2: Characterization of cell differentiation according to beta-TCP content

To induce bone differentiation of MG-63 cells in the scaffold, 100 nM Dexamethasone, 50 ug / ml Ascorbic acid and 10 mM β-glycerol 2 phosphate were added to the medium and cultured. After 4, 7 and 14 days, (Alkaline phosphate) was determined by Takara kit. As shown in FIG. 8, it was confirmed that the higher the concentration of? -TCP, the more active the differentiation of bone cells.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereto will be. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (7)

A 3D printing method by filament formation of a polymer comprising the steps of:
(a) melting poly-L-lactic acid (PLLA) powder;
(b) extruding and cooling the melt of step (a) to form a filament;
(c) feeding the formed filament to a print head of a 3D printer;
(d) discharging the melted material of the 3D printer filament heated from the printhead; And
(e) solidifying the discharged melt to form a 3D product.
The method according to claim 1,
The method of 3D printing according to claim 1, wherein the poly-L-lactic acid (PLLA) powder is further added with at least one selected from the group consisting of a colorant, a flame retardant, a plasticizer and a physiologically active substance.
delete The method according to claim 1,
Wherein the poly-L-lactic acid (PLLA) powder has a particle size of 50 to 10 mm.
The method according to claim 1,
Wherein the melting of the step (a) is performed at 100 to 300 ° C.
The method according to claim 1,
Wherein the step (b) is performed by injecting a melt at a speed of 0.5 to 3 m / min at a pressure of 50 to 300 kPa to form a filament.
The method according to claim 1,
Wherein the filaments of step (b) have a diameter of 0.1 to 2.0 mm.

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