KR102050362B1 - Manufacturing Method for Polymer composite with carbon fiber for 3D printers - Google Patents

Abstract

The present invention uses a carbon fiber as a reinforcing material, and relates to a method for producing a polymer composite for 3D printer with improved mechanical strength. The present invention comprises the steps of immersing the carbon fiber in the pretreatment agent; (b) drying the pretreated carbon fibers; And (c) provides a method for producing a polymer composite for molten laminated 3D printer using the carbon fiber comprising the step of mixing the dried carbon fiber and the thermoplastic resin.

Description

Manufacturing method for Polymer composite with carbon fiber for 3D printers}

The present invention relates to a method for manufacturing a polymer composite for 3D printer, and more particularly, to provide a method for manufacturing a polymer composite for 3D printer using carbon fiber as a reinforcing material and improving mechanical strength.

The use of 3D printers capable of molding three-dimensional objects is increasing. The product forming method of the 3D printer is a method of molding a photo-reflected portion into an object by scanning a laser beam on a photocurable material, a method of cutting and molding a molding material, and a method of melting and laminating a thermoplastic polymer composite material (FDM method). Etc.

Among these methods, 3D printers that melt and laminate polymer composites are cheaper to produce than 3D printers of other methods. For this reason, 3D printers using polymer composites are becoming popular for home and industrial use.

Meanwhile, the polymer composite material for 3D printer is made of a thermoplastic resin, and polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) may be used as the thermoplastic resin.

ABS is easy to purchase, has high tensile strength, is strong in heat and easy to make parts smaller than PLA, but it is difficult to mold due to heat shrinkage phenomenon.

Nowadays, PLA, which is harmless to humans and the environment, instead of ABS, has been spotlighted as a polymer composite material. However, due to the low tensile strength, it is only used for the production of simple prototypes such as sculptures and figures.

Therefore, the current situation is required to develop a composite material with improved strength in order to apply to high-strength parts.

Accordingly, the present invention is to provide a method for producing a polymer composite for 3D printer excellent mechanical properties.

In order to solve the above problems, the present invention comprises the steps of (a) immersing carbon fiber in the pretreatment agent; (b) drying the pretreated carbon fibers; And (c) provides a method for producing a polymer composite for molten laminated 3D printer using the carbon fiber comprising the step of mixing the dried carbon fiber and the thermoplastic resin.

The pretreatment may include one or more selected from the group consisting of hydrochloric acid, nitric acid, phosphoric acid, acetic acid, hydrofluoric acid, ammonium bicarbonate (NH ₄ HCO ₃ ) and ammonium carbonate ((NH ₄ ) ₂ CO ₃ ).

The step (a) is carried out under a current density of 0.7 ~ 7.0A / ㎡ and may be performed for 50 ~ 120 seconds.

Step (c) is carried out at 230 ~ 310 ℃, may have a temperature range of 2 to 10.

The polymer composite material is 95 to 99.9 parts by weight of a thermoplastic resin; And it may include 0.1 to 5 parts by weight of carbon fiber.

The thermoplastic resin is polylactic acid (PLA), acrylonitrile butadien styrene (ABS), high density polyethylene (HDPE), low density polyethylene (LDPE), styrene (Styrene), polypropylene (PP), And it may include one or more selected from the group consisting of polycarbonate (PC).

The carbon fiber may have a reinforced interfacial phase of 10 to 1,000nm thickness.

The reinforced interfacial phase may be formed by including 0.5 to 30 parts by weight of the interface material in 100 parts by weight of the carbon fiber.

The interfacial material may be a polymer, a copolymer, a block copolymer, a branched polymer, a hyperbranched polymer, a dendrimer, or the like, core-shell rubber particles, hard core-soft shell particles, soft core-hard shell particles, inorganic materials, metals, oxides, Carbonaceous materials, organic-inorganic hybrid materials, polymeric graft inorganic materials, organic-functionalized inorganic materials, polymeric graft carbonaceous materials, organic-functionalized carbonaceous materials, rubbery polymers, rubbery copolymers, block copolymers, cores And at least one of shell rubber particles and core-shell particles.

Method for producing a polymer composite for 3D printer according to the present invention is a method for producing a polymer composite for 3D printer with improved mechanical properties such as tensile strength, tensile modulus, flexural strength, flexural modulus by mixing a thermoplastic resin and carbon fiber having a reinforced interfacial phase Can be provided.

Figure 1 shows a schematic 90 ° cross-sectional view of the carbon fiber surface treatment according to the present invention.
Figure 2 shows a schematic cross-sectional view of 0 ° of the carbon fiber surface treated according to the present invention.
3 is a photograph of a tensile specimen prepared according to one embodiment of the present invention.
Figure 4 is a photograph showing a carbon fiber surface treatment means according to an embodiment of the present invention.
5 is a photograph showing that the surface of the carbon fiber according to an embodiment of the present invention after the surface treatment at each current density, the surface was observed by an electron microscope.
6 is a graph showing the results of FT-IR analysis after surface treatment of carbon fibers according to an embodiment of the present invention at each current density.
Figure 7 is a photograph showing the polymer composite filament manufacturing means according to an embodiment of the present invention.
8 is a photograph showing an extrusion means having a temperature section of the polymer composite filament manufacturing means according to an embodiment of the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. Throughout the specification, when a part is said to "include" a certain component, it means that it may further include other components, not to exclude other components, unless otherwise stated.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all transformations, equivalents, and substitutes included in the spirit and scope of the present invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present invention, the terms including or having are intended to indicate that there is a feature, number, step, operation, component, part, or a combination thereof described in the specification, but one or more other features or numbers, step It is to be understood that the present invention does not exclude in advance the possibility of the presence or the addition of an operation, a component, a part, or a combination thereof.

The present invention comprises the steps of immersing the carbon fiber in the pretreatment agent; (b) drying the pretreated carbon fibers; And (c) provides a method for producing a polymer composite for molten laminated 3D printer using the carbon fiber comprising the step of mixing the dried carbon fiber and the thermoplastic resin.

The step (a) is a step of surface treatment of the carbon fiber is performed by immersing the carbon fiber in the point treatment agent. The pretreatment agent may be used without limitation as long as it reduces the roughness by etching the surface of the carbon fiber, and can increase the number of oxygen functional groups, preferably hydrochloric acid, nitric acid, phosphoric acid, acetic acid, hydrofluoric acid, ammonium bicarbonate ( NH ₄ HCO ₃ ) and ammonium carbonate ((NH ₄ ) ₂ CO ₃ ) It may include one or more selected from the group consisting of, more preferably hydrogen carbonate or ammonium carbonate, most preferably ammonium bicarbonate Can be used.

In addition, the acidic pretreatment agent can be used by selecting the appropriate concentration according to the type and pH of the pretreatment agent to be used, but preferably 0.1 to 1M, more preferably 0.2 to 0.5M most preferably 0.3M Can be. If the pretreatment agent has a concentration of less than 0.1M, the treatment time of the pretreatment agent is increased, or the surface roughness and oxygen functional groups are not expected to be increased by the pretreatment agent. In preparation, the stirring time may be long, and the bonding between the carbon and the thermoplastic polymer may be weakened by the pretreatment agent remaining in the washing.

In addition, the step (a) is carried out under a current density of 0.7 ~ 7.0A / ㎡ may be performed for 50 ~ 120 seconds, preferably 80 ~ 110 seconds under a current density of 0.75 ~ 6.82A / ㎡. . When surface treatment is performed for the current density less than 0.7A / m2 or less than 50 hours, the surface treatment is poor and the effect of reducing the surface roughness and the increase of the oxygen functional group can not be expected, and the current density exceeds 7.0A / m2 or 120 If the surface treatment is performed for more than a second, the amount of current used increases and the production time of the carbon fiber increases, thereby decreasing economic efficiency.

The step (c) may be carried out by selecting appropriate conditions if the conditions for mixing the thermoplastic resin in the step of mixing the carbon fiber and the thermoplastic resin, but preferably may be carried out at 230 ~ 310 ℃. If the step (c) is carried out at less than 230 ° C the viscosity is lowered because the resin is not sufficiently liquefied. Therefore, the resin in the extruder may be cured and the carbon fiber may be wound so that the carbon fiber may be broken under high tension. In addition, when the temperature is low as described above, the surface of the filament may be uneven due to a decrease in viscosity. In addition, if the step (c) is carried out above 310 ° C, the viscosity of the resin may be increased, so that the diameter of the carbon fiber-polymer composite filament may be reduced than a prescribed value, and surface discoloration may occur.

In addition, the step (c) may have a temperature range of 2 to 10. When the step (c) is performed at a constant temperature, a temperature difference between the inside and the outside of the filament may occur, so that the surface may be uneven when the thermoplastic resin is extruded. Therefore, it is preferable to use a temperature section of the extruder 2 to 10 to be heated to a constant temperature. At this time, the temperature section may have a temperature of 230 ~ 310 ℃ and preferably may have a temperature of 260 ~ 280 ℃. In addition, the temperature section starts with a temperature of 260 ℃ to rise by 5 ~ 10 ℃ by each reaches the highest temperature section of 280 ℃, then it is most preferred to reach 260 ℃ by falling by 5 ~ 10 ℃ by.

The polymer composite material for the molten laminated 3D printer may include 0.01 to 5 parts by weight of the carbon fibers in 95 to 99.99 parts by weight of the thermoplastic resin, and more preferably 0.07 to 0.1 parts by weight of the carbon fibers. When the use range of the thermoplastic resin and the carbon fiber exceeds or falls below, a problem may occur in that the carbon fiber is buried or mechanical properties are reduced when the polymer composite is extruded. In addition, the carbon fiber is preferably 1000 to 7000 strands, preferably 2000 to 4000 strands per filament unit length (1 cm). If it is included less than 1000 strands can not be expected to improve the physical properties of the carbon fiber, if it contains more than 7000 strands, the filament may be exposed to the surface of the fiber, or the malleability, ductility may be reduced.

The thermoplastic resin refers to a polymer, such as polyethylene or polyvinyl chloride, which is stepped down when heated and then hardened again when cooled. These materials can be reshaped in various forms by heating. After forming by applying heat, it is possible to change the shape by applying heat again, which can be efficiently processed by extrusion molding or injection molding. Thermoplastic resins include crystalline thermoplastic resins and amorphous thermoplastic resins. The crystalline thermoplastic resins include polyethylene, nylon, polyacetal resin, and the like, and are milky white. There are many transparent thermoplastic resins such as vinyl chloride resin, polystyrene, ABS (Acrylonitrile Butadien Styrene) resin and acrylic resin.

In the method of manufacturing a polymer composite material for a 3D printer according to an embodiment of the present invention, the thermoplastic resin is polylactic acid (PLA), acrylonitrile butadiene styrene (Arylonitrile Butadien Styrene, ABS), high density polyethylene (HDPE), low density It may include one or more selected from the group consisting of polyethylene (LDPE), styrene (Styrene), polypropylene (PP), and polycarbonate (PC). PLA (Poly lactic Acid) is a polymer of low molecular weight compounds (monomers) present in the living body called lactic acid and does not exist in nature. In general, it is known to be hydrolyzed by water, low molecular weight, and then degraded by microorganisms.

In other words, PLA's biggest advantage is that it can be degraded in the ground, unlike ordinary plastics and synthetic fibers. Recently, it has been spotlighted as a substitute for plastic yogi. In the field of 3D printing raw materials, PLA raw materials have a merit that hardly shrinks and then cools again, so that shrinkage hardly occurs. ABS (Acrylonitrile Butadien Styrene) is an amorphous styrene-based thermoplastic resin, and has excellent impact resistance, rigidity, fluidity, and other characteristics such as dimensional stability, molding processability, and chemical resistance.

The carbon fiber preferably has a reinforcing interfacial phase having a thickness of 10 to 1,000 nm, and it is preferable to form the reinforcing interfacial phase by including 0.5 to 30 parts by weight of an interfacial material in 100 parts by weight of the carbon fiber.

If the interfacial material is less than 0.5 parts by weight, it is difficult to form the reinforced interface phase, and if it exceeds 30 parts by weight, the thickness of the reinforced interface phase may exceed 1,000 nm.

When the thickness of the reinforced interfacial phase is less than 10nm, the mechanical properties of the polymer composite is reduced, when the thickness of the reinforced interfacial phase exceeds 1,000nm, it may not be well mixed with the carbon fiber and the thermoplastic resin.

The interfacial material may be a toughening agent or a mixture of a toughening agent containing one or more components that are incompatible with the transition agent. The toughening agents may be elastomers, branched polymers, hyperbranched polymers, dendrimers, rubbery polymers, rubbery copolymers, block copolymers, core-shell particles, oxides or inorganic materials such as clays, polyhedral oligomericsilsesquioxanes ( POSS), carbon black, carbon nanotubes, carbon nanofibers, carbonaceous materials such as fullerene, ceramics and silicon carbide, but are not limited to these.

Examples of block copolymers having a composition described in US Pat. No. 6,494,113 (Court et al., Atofina, 2005) include "Nanostrength" SBM (polystyrene-polybutadiene-polymethacrylate) and MBM (polymethacryl). Latex-polybutylacrylate-polymethacrylate), both of which are manufactured by Arkema. Other block copolymers include Fortegra® and amphipathic block copolymers (described in US 7820760B2 by Dow Chemical). Examples of known core-shell particles include core-shell (dendrimer) particles (the composition of which is described in US 20100280151A1 (Nguyen et al., Toray, Inc., 2010), having unsaturated carbon-carbon bonds). The amine branched polymer is grafted as a shell to the core polymer polymerized from the polymerizable monomer; Core-shell rubbery particles [The composition is described in Kaneka's EP 1632533A1 and EP 2123711A1, and the KaneAce MX product family of such particles / epoxy blends is characterized in that the particles are polymerizable monomers, such as butadiene. , Polymer cores polymerized from styrene, other unsaturated carbon-carbon bond monomers, or combinations thereof, and polymer shells corresponding to epoxy, generally polymethylmethacrylate, polyglycidylmethacrylate, polyacrylonitrile or equivalent Water and the like]; "JSR SX" series of carboxylated polystyrene / polydivinylbenzene manufactured by JSR Corporation; "Kureha paraloid" EXL-2655 (manufactured by Kureha Co., Ltd.), which is a butadiene alkyl methacrylate styrene copolymer; "Stafiloid" AC-3355 and TR-2122, both of which are acrylate methacrylate copolymers (both manufactured by Takeda Yakuhin Kogyo Co., Ltd.); "PARALOID" EXL-2611 and EXL-3387 (both manufactured by Rohm & Haas), each of which is a butyl acrylate methyl methacrylate copolymer. Examples of known oxide particles include Nanopox (registered trademark) manufactured by nanoresins AG. This is a master blend of functionalized nanosilica particles and epoxy.

Toughening agents used as interfacial materials include core-shell particles (eg, MX416, MX125, MX156) found in the Kane Ace MX product family by Kaneka, KK; Or materials having a shell composition or surface chemistry similar to Kane Ace MX materials; Or a rubbery material such as a material having a surface chemistry that corresponds to the surface chemistry of the adherend, which allows the material to move near the adherend and have a higher concentration than the bulk adhesive composition. These core-shell particles are generally sufficiently dispersed in the epoxy base material at typical addition amounts of 25% and can be used directly in adhesive compositions for high performance bonding to adherends.

The ratio of the transition agent to the interfacial material may be about 0.1 to about 30 or about 0.1 to about 20. Examples of the transition agent include polyvinyl formal, polyamide, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamideimide, polyimide, polyetherimide, and phenyltrimethyl indane structure. Polyimide, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyaramid, polyethernitrile, polybenzimidazole, derivatives thereof, and mixtures thereof may be used.

The reinforcing interfacial phase may be applied by mechanical applications such as pumps, control systems, dosing gun assemblies, swirl techniques using remote feeders and applicator guns, steaming, or by hot melt methods. It may be formed on the carbon fiber.

When mixing the thermoplastic resin and the carbon fiber, the rotation speed of the mixing screw may be 15 to 17 RPM. If the rotation speed of the mixing screw is less than 15 RPM, the thickness of the polymer composite may be thickened, there may be a problem of clogging during printing, and if it exceeds 17 RPM, there may be a problem that the polymer composite is thin and not inserted into the printer. .

Hereinafter, the present invention will be described in detail through examples.

Example 1

Using the apparatus of FIG. 4, carbon fiber was subjected to 0.3 M ammonium bicarbonate, a toughening agent (core-shell particles by Kaneka, MX416) and a transition agent (polyvinyl formal) at a current density of 0.75 A / m 2. After soaking for 90 seconds in a mixture of), washed with distilled water, dried and surface-treated to prepare a carbon fiber having a reinforced interface of 100nm.

Example 2

The same process as in Example 1 was conducted except that the current density was 1.52 A / m 2.

Example 3

The same process as in Example 1 except that the current density was 2.27 A / m 2.

Example 4

The same procedure was followed as in Example 1 except that the current density was 3.03 A / m 2.

Example 5

The same process as in Example 1 except that the current density was 3.79 A / m 2.

Example 6

The same process as in Example 1 except that the current density was 4.55 A / m 2.

Example 7

The same process as in Example 1 except that the current density was 5.31 A / m 2.

Example 8

The same process as in Example 1 except that the current density was set to 6.07 A / m 2.

Example 9

The same procedure as in Example 1 was conducted except that the current density was set to 6.82 A / m 2.

Experimental Example 1

The surface of the carbon fiber prepared in Examples 1 to 9 was observed using an electron microscope. As shown in Figure 5, it was confirmed that the roughness decreases due to the surface etching of the carbon fiber as the current density increases.

In addition, FT-IR analysis results of the carbon fibers prepared in Examples 1 to 9, as shown in Figure 6, the peak value of 3500cm-1, 1720cm-1, 1082cm-1 is increased with increasing current density I could confirm that. Therefore, when the current density increases, it was confirmed that the peak of the oxygen functional group increased.

Example 10

The composite filament was manufactured by supplying 0.075 parts by weight of carbon fiber of Example 1 and 99.925 parts by weight of the fiber of Example 1 to the extrusion equipment (Fig. 8) set to the temperature section shown in Table 1 below.

section One 2 3 4 5 6 Temperature (℃) 260 270 280 280 275 260

Example 11

Except for using the carbon fiber of Example 4 instead of the carbon fiber of Example 1 in Example 10 was carried out in the same manner.

Example 12

Except for using the carbon fiber of Example 7 instead of the carbon fiber of Example 1 in Example 10 was carried out in the same manner.

Example 13

Except for using the carbon fiber of Example 9 instead of the carbon fiber of Example 1 in Example 10 was carried out in the same manner.

Example 14

Except for using PLA instead of ABS in Example 13 it was carried out in the same manner.

Comparative example

As a comparative example, Stratasys Inc., the world's highest level of polymer composite materials for 3D printers, was used.

Experimental Example 2

In order to evaluate the mechanical properties of the polymer composite according to the present invention, the tensile strength (ASTM D 638) and flexural specimen (ASTM D 790) by using a FDM 3D printer with the polymer composite of Example 10 and Comparative Example to prepare a tensile strength , Experimental results for tensile modulus, flexural strength and flexural modulus are shown in Table 2 below.

Evaluation item Comparative example Example 10 Example 11 Example 12 Example 13 Example 14 Assessment Methods Tensile Strength (MPa) 32 38 38 40 41 42 ASTM D 638 Tensile Modulus (GPa) 2.2 2.4 2.5 2.7 2.8 2.7 ASTM D 638 Flexural Strength (MPa) 60 70 74 76 78 77 ASTM D 790 Flexural Modulus (GPa) 2.0 2.5 2.6 2.6 2.6 2.5 ASTM D 790

Referring to Table 2, it was found that the tensile strength, tensile modulus, flexural strength and flexural modulus of Examples 13 and 14 were more excellent than those of Comparative Examples. In Examples 10-12 having a low current density during surface treatment, tensile strength, tensile modulus, flexural strength, and flexural modulus were higher than those of the conventional comparative example, but were lower than those of Example 13, which is an optimal example. This is because the oxygen functional group of the carbon fiber increases as the current density increases during the surface treatment, and the bonding strength with the thermoplastic resin increases according to the number of oxygen functional groups. do.

As described above in detail specific parts of the present invention, it will be apparent to those skilled in the art that these specific descriptions are merely preferred embodiments, and thus the scope of the present invention is not limited thereto. will be. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

1: carbon fiber
2: interfacial material
3: one layer of interfacial material
4: interphase
5: carbon fiber bobbin
6: pretreatment bath
7: washing tank
8: drying control device
9: carbon fiber recovery machine
10: winder
11: nozzle
12: carbon fiber
13: resin supply unit
a ~ f: Temperature range

Claims (9)

(a) immersing the carbon fiber in ammonium bicarbonate (NH 4 HCO 3) or ammonium carbonate ((NH 4) 2 CO 3) as a pretreatment agent;
(b) drying the pretreated carbon fibers; And
(c) mixing the dried carbon fibers with the thermoplastic resin;
In the polymer composite manufacturing method for a molten laminated 3D printer using a carbon fiber comprising a,
The step (a) is a polymer composite manufacturing method for a molten laminated 3D printer using carbon fibers, characterized in that performed for 90 seconds under a current density of 5.31 ~ 6.82 A / ㎡. delete delete The method of claim 1,
The step (c) is carried out at 230 ~ 310 ℃, the method for producing a polymer composite for molten laminated 3D printer using carbon fibers, characterized in that having a temperature range of 2 to 10. The method of claim 1,
The polymer composite is
95 to 99.99 parts by weight of the thermoplastic resin; And
Carbon fiber is 0.01 to 5 parts by weight; Method for producing a polymer composite for molten laminated 3D printer using the carbon fiber comprising a. The method of claim 1,
The thermoplastic resin is polylactic acid (PLA), acrylonitrile butadien styrene (ABS), high density polyethylene (HDPE), low density polyethylene (LDPE), styrene (Styrene), polypropylene (PP), And polycarbonate (PC). 1. A method for manufacturing a polymer composite for a molten laminated 3D printer using carbon fibers, characterized in that it comprises one or more selected from the group consisting of polycarbonate (PC). The method of claim 1,
The carbon fiber is a polymer composite manufacturing method for a molten laminated 3D printer using a carbon fiber, characterized in that having a reinforced interfacial phase of 10 to 1,000nm thickness. The method of claim 7, wherein
Method for producing a polymer composite for a molten laminated 3D printer using carbon fibers, characterized in that to form the reinforced interfacial phase comprising 0.5 to 30 parts by weight of the interface material in 100 parts by weight of the carbon fiber. The method of claim 8,
The interfacial materials include block copolymers, branched polymers, hyperbranched polymers, dendrimers, hard core-soft shell particles, soft core-hard shell particles, metals, oxides, carbonaceous materials, polymeric graft inorganic materials, organic-functionalized inorganic materials , Polymeric graft carbonaceous material, organic-functionalized carbonaceous material, rubber-like copolymer and core-shell rubber particles, characterized in that it comprises at least one or more of the composite material for the molten laminated 3D printer using a carbon fiber .

Images