KR20180114668A - Filament compositions for 3D printers utilizing waste polystyrene resin foam and method for manufacturing the same - Google Patents

Abstract

Disclosed is a filament composition for a 3D printer utilizing a waste polystyrene resin foam and a method for manufacturing the same. The filament composition for a 3D printer utilizing a waste polystyrene resin foam comprises: 80-90 parts by weight of a molten product of the waste polystyrene resin foam melted by an organic solvent; 5-10 parts by weight of an inorganic filler containing graphite; 0.5-10 parts by weight of a metal powder; and 1-3 parts by weight of an additive.

Description

FIELD OF THE INVENTION The present invention relates to a filament composition for a 3D printer using a waste polystyrene resin foam and a method for manufacturing the filament composition for a 3D printer,

The present invention relates to a filament composition for a 3D printer and a method for producing the filament composition. More particularly, the present invention relates to a filament composition for a 3D printer, and more particularly to a filament composition for a 3D printer which comprises a waste polystyrene resin foam as a material of a filament composition, To a filament composition for a 3D printer utilizing a resin foam and a method of manufacturing the same.

3D printers have been developed for the purpose of making prototypes before a product is commercialized by a company but have developed in the early stages of the process, limited to plastic materials, expanded to nylon and metal materials, .

In general, it is divided into a 3D printer method (additive type or rapid prototyping method) and a cutting type machining method (computer numerically controlled engraving method) in which a large lump is cut by stacking up a layer by a method of forming a three-dimensional form. The object can be determined in various ways.

The FDM (Fused Deposition Modeling) method is a typical example of the laminated type, and is called a FFF (Fused Filament Fragment). A plastic wire called a filament is used as a material. The material is similar to glue guns used in home applications in a manner that melts while passing through a heated extruder and laminates the material flowing through the nozzle onto an output plate to shape the required shape.

The material of the 3D printer is realized by using a thin plastic yarn called a filament as described above, and melting the filaments and stacking them from the bottom up. These filaments have been developed and commercialized by manufacturers, and the quality of the filaments is different according to the materials, so it is very difficult to apply individual temperature control.

Especially, in Korea, most filament raw materials are imported from foreign countries. Therefore, there is a growing need to easily realize low cost filament.

1. Published Japanese Patent Application No. 10-2017-0039041 2. Patent Publication No. 10-1712506 3. Patent Publication No. 10-1701498

An object of the present invention is to provide a filament composition for a 3D printer, which utilizes a waste polystyrene resin foam as a material of a filament composition and blends graphite having excellent strength and elasticity to improve mechanical properties.

Another object of the present invention is to provide a filament for a 3D printer using a filament composition for a 3D printer utilizing the waste polystyrene resin foam.

It is still another object of the present invention to provide a method for manufacturing a filament for a 3D printer using the filament composition for a 3D printer.

The problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

In order to accomplish the object, the present invention provides a process for producing a polystyrene resin composition comprising 80 to 90 parts by weight of a melt of a waste polystyrene resin foam melted by an organic solvent, 5 to 10 parts by weight of an inorganic filler containing graphite, 0.5 to 10 parts by weight of a metal powder, 3 parts by weight of a polystyrene resin foam is provided.

Preferably, the inorganic filler is added to 100 parts by weight of graphite, 1 to 2.5 parts by weight of carbon black, 0.5 to 2 parts by weight of titanium dioxide, 0.3 to 1 part by weight of mica, 0.1 to 0.8 parts by weight of silica, 10 to 15 parts by weight of calcium sulfate 9 to 14 parts by weight of barium carbonate, 7.4 to 15 parts by weight of magnesium carbonate, 0.5 to 6 parts by weight of barium sulfate, 2 to 8 parts by weight of oxysulfate, 3 to 5 parts by weight of tin oxide, 0.7 to 2.5 parts by weight of kaolin, 5 to 9 parts by weight may be mixed.

Preferably, the metal powder is at least one selected from the group consisting of stainless steel, nickel, aluminum, and titanium, and the particle size of the metal powder may be 0.1 to 20 占 퐉.

Preferably, the additive is composed of a plasticizer, a flame retardant, an antistatic agent, and a crystal nucleating agent, wherein the plasticizer comprises 30 to 100 parts by weight of a plasticizer and at least one additive selected from the group consisting of isononyl 2-ethylhexanoate, 5 to 60 parts by weight of an additive comprising isodecyl 2-ethylhexanoate, or a mixture thereof.

Preferably, the antistatic agent is selected from the group consisting of diethylhexyl phthalate (DEHP), di-butyl phthalate (DBP), di-isodecyl phthalate (DIDP), butyl benzyl phthalate , Butyl benzyl phthalate, di-isononyl phthalate (DINP), and di-n-octyl phthalate (DNOP) .

Another object of the present invention is to provide a filament for a 3D printer utilizing a waste polystyrene resin foam obtained by pelletizing a filament composition for a 3D printer utilizing the above-described waste polystyrene resin foam.

According to another aspect of the present invention, there is provided a method for manufacturing a filament for a 3D printer using a waste polystyrene resin foam, comprising: collecting and sorting a waste polystyrene resin foam; Crushing the selected waste polystyrene resin foam to a predetermined size by a crusher; Melting the pulverized particulate waste polystyrene resin foam with an organic solvent; Mixing an inorganic filler, a metal powder, and an additive including a melt of a waste polystyrene resin foam and graphite into an agitator to mix; Continuously injecting the mixture into an extruder and having a diameter of 1.5 to 3 mm at an extrusion temperature of 100 to 130 캜; There is provided a method for manufacturing a filament for a 3D printer using a waste polystyrene resin foam provided by a method of cutting a mixture to be extruded to a predetermined size by a cutter to solidify the filament and then selecting a filament having a maximum compressive strength of 25 to 30 MPA .

As disclosed in the solution to the problem, the waste polystyrene is utilized as the main material of the filament corresponding to the ink of the 3D printer, so that the economical advantage of recycling the waste material can be obtained.

Further, by mixing graphite with waste polystyrene, it is possible to solve the problem that the moldability of polystyrene is better than that of ABS resin, but the durability is poor.

1 is a flow chart for explaining a method of manufacturing a filament for a 3D printer using a waste polystyrene resin foam according to the present invention;

Hereinafter, the preferred embodiments of the present invention and the physical properties of the respective components will be described in detail. However, it is to be understood that those skilled in the art will readily understand the present invention, And this does not mean that the technical idea and scope of the present invention are limited.

The present invention relates to a filament composition for a 3D printer using a waste polystyrene resin foam and a method of manufacturing the same, and is characterized by utilizing waste polystyrene.

First, a filament composition for a 3D printer using a waste polystyrene resin foam comprises a waste polystyrene resin foam melted by an organic solvent, an inorganic filler including graphite, a metal powder, and an additive.

The preferred content of the filament composition is 80 to 90 parts by weight of the waste polystyrene resin foam, 5 to 10 parts by weight of the inorganic filler containing graphite, 0.5 to 10 parts by weight of the metal powder, and 1 to 3 parts by weight of the additive .

Waste polystyrene is a material that can be easily picked up from the surrounding area. Polystyrene is expanded by a foaming agent. It is called foam polystyrene, styrofoam, foam styrene and styrofoam. It is also abbreviated as EPS. It is white and light, has excellent water resistance, insulation, soundproofing and buffering properties and is widely used where such a function is required.

Polystyrene (PS) is a thermoplastic plastic. It is brittle and rarely used alone. It is often mixed with other polymers. Typical examples are butadiene rubber, SBR, SBS, HIPS and so on.

Polystyrene, which is the main component of these pulp polystyrenes, is a low-priced and hard-hard plastic, and is a polymer frequently encountered in everyday life after polyethylene. HIPS polystyrene, which partially compensates for the disadvantages of pure polystyrene and pure polystyrene, It is divided into ABS resin which has good properties by mixing acryl and butene.

Pure polystyrene has good moldability compared to ABS resin, but it is mainly used for large black household appliances such as TV, because it has low durability and wears white. It is also widely used for remote control, general purpose electronic calculator, yogurt container and weighing cup .

Therefore, the present invention has the above-mentioned advantages of the polystyrene resin, but also has the advantage of reinforcing the strength by mixing the inorganic filler.

The amount of the waste polystyrene resin may be in the range of 80 to 90 parts by weight. When the amount of the waste polystyrene is less than 80 parts by weight, the economic benefit is small. When the amount of the waste polystyrene is more than 90 parts by weight, The physical properties are weakened and problems may occur in terms of strength.

The inorganic filler plays a role of imparting excellent mechanical properties, i.e., hardness and strength, of the molded article when the filament is extruded. The inorganic filler is added in an amount of 5 to 10 parts by weight relative to the total filament composition . When the content is less than 5, the strength is lowered. When the content is more than 10, the working and surface properties are lowered, which is not preferable.

Such an inorganic filler may be composed of graphite, carbon black, graphite, mica (mica), silica, calcium sulfate, barium carbonate, magnesium carbonate, barium sulfate, oxysulfate, tin oxide, kaolin and silicon carbide.

The preferable content of each composition of the inorganic filler is 1 to 2.5 parts by weight of carbon black, 0.5 to 2 parts by weight of graphite, 0.3 to 1 part by weight of mica, 0.1 to 0.8 parts by weight of silica, 10 to 15 parts by weight of calcium sulfate, 9 to 14 parts by weight of barium carbonate, 7.4 to 15 parts by weight of magnesium carbonate, 0.5 to 6 parts by weight of barium sulfate, 2 to 8 parts by weight of oxysulfate, 3 to 5 parts by weight of tin oxide, 0.7 to 2.5 parts by weight of kaolin, And 5 to 9 parts by weight of silicon carbide may be mixed.

In particular, the graphite may include graphite, expanded graphite, oxidized graphite, etc. Carbon black may be CNT (carbon nanotube), graphite may be natural graphite, artificial graphite, and graphite used in the present invention may be fixed When the amount of carbon is 98 mass%, preferably 98.5 mass% or more, and more preferably 99 mass% or more, excellent compressive strength can be obtained. The graphite used in the present invention is produced by depositing graphite in a solution containing an acidic substance and an oxidizing agent to produce graphite intercalation compound and heating the graphite intercalation compound to expand graphite crystal in the C axis direction to produce expanded graphite . Although graphite used for the expanded graphite is not particularly limited, it is preferable to use graphite having high crystallinity, such as natural graphite and pyrolytic graphite, but it is preferable to use natural graphite in consideration of economical efficiency and the like. The natural graphite used is not limited, but commercial products can be adopted. Sulfuric acid or a mixture of sulfuric acid and nitric acid was used as an acidic substance used for expanding graphite. The acid concentration is preferably 95% or more. The amount of the acidic substance to be used is not particularly limited, and it is preferable to use 100 to 1000 weight parts per 100 parts by weight. In addition, it is preferable to use hydrogen peroxide or hydrochloric acid as the oxidizing agent to be used together with the acidic substance because it is possible to obtain expanded expanded graphite. When hydrogen peroxide is used as the oxidizing agent, the concentration of hydrogen peroxide is not particularly limited, but is preferably 20 to 40% by weight. There is no particular limitation on the amount, but it is preferable that the hydrogen peroxide content is 5 to 60 parts by weight based on 100 parts by weight of graphite. There is no limitation on the method of expanding graphite, but graphite is immersed in the acidic solution and washed with water. When the graphite is rapidly heated at a high temperature, the graphite can be entangled intensely in an insect-like manner to obtain expanded graphite in a form.

In addition, the mica belongs to a layered silicate having a generally two-dimensional plate-like structure. Among the major rock minerals, mica is common in all three rocks such as igneous rock, sedimentary rock, and metamorphic rock. These mica contain a considerable amount of metals in addition to potassium and aluminum, such as magnesium, lithium, manganese, titanium and iron. This contributes to strength improvement.

Since silica is an inorganic substance, it is photochemically stable to ultraviolet rays, transparent in ultraviolet ray region of 250 占 퐉 or more and visible light, chemically stable, harmless to human body and can be applied to cosmetics, medicines and other biomaterials. It can be processed in various forms such as bulk. In addition, the sol-gel reaction rate can be easily controlled as compared with other inorganic host materials. This serves as a quencher.

In addition, the calcium sulfate is precipitated when an aqueous solution of a sulfate is added to an aqueous solution of a calcium salt, and is naturally produced as a hard stone. It is a white crystal produced by gypsum (natural gypsum). It is colorless or white and does not dissolve well in water. It is used as a model, a statue, a fixing agent, etc., and serves as a coagulant in the present invention.

In addition, barium carbonate is used as a raw material for barium salts, crystal glasses and optical glasses, and is also used as a glaze for ceramics and enamel, a carburizing agent for heat treatment of metals, a pesticide and a rodenticide, Do. In the present application, it acts as an antimicrobial agent.

Other additives such as magnesium carbonate, barium sulfate, oxysulfate and the like have the role of reinforcing the antimicrobial agent and strengthening strength such as barium carbonate. Tin oxide serves as a preservative, kaolin facilitates compounding, The hardness becomes larger after the diamond and serves as the strength reinforcing agent.

On the other hand, the inorganic filler is preferably surface-treated. The coupling agent used for such surface treatment is used for improving adhesion between the filler and the resin. For example, a silane-based coupling agent, a titanium- Can be selected and used.

Specific examples of the silane-based coupling agent include triethoxysilane, vinyltris (? -Methoxyethoxy) silane,? -Methacryloxypropyltrimethoxysilane,? -Glycidoxypropyltrimethoxysilane,? - (Aminoethyl) -? - aminopropyltrimethoxysilane, N-? (Aminoethyl) -? - aminopropyltrimethoxysilane, N- Aminopropyltriethoxysilane, N-phenyl? -Aminopropyltrimethoxysilane,? -Mercaptopropyltrimethoxysilane,? -Chloropropyltrimethoxysilane,? -Aminopropyltrimethoxysilane,? -Amino Propyl tris (2-methoxyethoxy) silane, N-methyl? -Aminopropyltrimethoxysilane, N-vinylbenzyl? -Aminopropyltriethoxysilane, triaminotropyltrimethoxysilane, 3- Propyl trimethoxysilane, 3-4,5-dihydro Imidazole in profile triethoxysilane, hexamethyldisilazane, N, O- (bis trimethylsilyl) amide, and N, N- bis (trimethylsilyl) urea and the like. Of these,? -Aminopropyltriethoxysilane, N-? (Aminoethyl)? -Aminopropyltrimethoxysilane,? -Glycidoxypropyltrimethoxysilane, or? - (3,4- Cyclohexyl) ethyl trimethoxysilane is preferable.

Specific examples of the titanium-based coupling agent include isopropyltriisostearoyl titanate, isopropyltridodecylbenzenesulfonyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetraisopropyl bis (dioctyl Pyro

Phosphate) titanate, tetraoctylbis (ditridecylphosphite) titanate, tetra (1,1-diallyloxymethyl 1-butyl) bis (ditridecylphosphite) titanate, bis (dioctylpyrophosphate ) Oxyacetate titanate, bis (dioctyl pyrophosphate) ethylene titanate, isopropyl trioctanoyl titanate, isopropyl dimethacryl isostearyl titanate, isopropyl isostearoyl diacrylate titanate, isopyro Isopropyltriacyl phenyl titanate, isopropyl tributyl (N-amidoethyl, aminoethyl) titanate, dicumylphenyloxyacetate titanate, and diisostearoyl ethylene titanate . Of these, isopropyl tri (N-amidoethyl, aminoethyl) titanate is suitable.

The method of treating such a coupling agent on the surface of the inorganic filler is not particularly limited and can be carried out by a usual method such as a sizing treatment, a spraying, a mixed drying method and the like.

The metal powder is in the group consisting of stainless steel, nickel, aluminum and titanium

And if it is contained in the synthetic resin component, acts as a filler to improve the mechanical properties.

If the content of the metal powder is less than 0.5 part by weight, the effect of improving the impact resistance of the filament composition is insignificant. If the content of the metal powder exceeds 10 parts by weight, the amount of the synthetic resin is decreased, And increases the manufacturing cost.

The metal powder is formed into a spherical shape having a particle size of 0.1 to 20 탆 through a gas spraying method or an electric wire explosion method. The metal powder exhibiting the particle size is uniformly mixed with the synthetic resin, .

The additive is composed of a plasticizer, a flame retardant, an antistatic agent, and a crystal nucleating agent, wherein the plasticizer is a mixture of 30 to 100 parts by weight of a plasticizer and at least one of isononyl 2-ethylhexanoate, isodecyl 2-ethylhexanoate Isodecyl 2-ethylhexanoate), or a mixture thereof.

Here, the stock removal agent is a substance added to impart flexibility to a polymer synthetic resin so as to be easily molded or to impart flexibility to a molded article, that is, a substance that mixes well with a polymer and acts like a solvent.

Diethylhexyl phthalate (DEHP), di-butyl phthalate (DBP), di-isodecyl phthalate (DIDP), butyl benzyl phthalate (BBP), butyl Benzyl phthalate, di-isononyl phthalate (DINP), and di-n-octyl phthalate (DNOP) may be used alone or in combination of two or more.

The content of the main scouring agent is preferably 30 to 100 parts by weight based on 100 parts by weight of the polyvinyl chloride resin. When the content is less than 30 parts by weight, sol has a viscosity which is too high to make workability. When the content is more than 100 parts by weight, there is no problem in workability, but there is a high possibility that the plasticizer migrates and bleeds in the product . The additive agent of the present invention means an additive which is used together with the main additive to reduce the viscosity of the filament composition and increase the viscosity stability and improve the physical properties such as tensile strength, elongation and heating loss.

Examples of such additives include isononyl 2-ethylhexanoate, isodecyl 2-ethylhexanoate, and mixtures thereof.

The content of the additive is preferably 5 to 60 parts by weight based on 100 parts by weight of the polyvinyl chloride resin. If the content is less than 5 parts by weight, the viscosity reduction effect can not be sufficiently achieved as desired. If the content is more than 60 parts by weight, the added plasticizer is not completely absorbed by the resin, It is difficult to apply the plastisol as a product even if it is processed even if the plasticizer is evaporated during the drying process.

Hereinafter, an embodiment of a filament composition for a 3D printer utilizing a waste polystyrene resin foam according to the present invention will be described.

87 parts by weight of the melt of the waste polystyrene resin foam melted by the organic solvent, 5 parts by weight of the inorganic filler containing graphite, 5 parts by weight of the metal powder and 2 parts by weight of the additive were mixed to prepare filaments.

Here, the filament production temperature was 95 ° C, the filament extrusion diameter was 1.5 mm, and acetone in acetone or toluene was used as an organic solvent for melting the waste polystyrene resin foam.

The procedure of Example 1 was followed except that the content of the inorganic filler was increased to 7 parts by weight and the filament temperature was changed to 110 ° C to prepare filaments.

The procedure of Example 2 was followed except that the content of the inorganic filler was increased to 11 parts by weight to prepare filaments.

[Comparative Example 1]

Filament was prepared by applying high-density polystyrene in place of the waste polystyrene resin foam, inorganic filler, metal powder and additive, setting the filament temperature to 110 ° C, and filament extrusion diameter to 1.5 to 2 mm.

Item Example 1 Example 2 Example 3 Comparative Example 1 Main material Waste polystyrene resin foam Waste polystyrene resin foam Waste polystyrene resin foam High density polystyrene Organic solvent Acetone Acetone Acetone - Inorganic filler
(Parts by weight) 5 7 11 - filament
Manufacturing temperature (캜) 95 110 110 110 Diameter of filament (mm) 1.5 1.5 1.5 1.5 Maximum compressive strength
(MPA) 17 29 29 29

As can be seen from the above Table 1, Examples 1 and 2 show that when the content of the inorganic filler is small or large, the maximum compressive strength is greatly increased when the content of the inorganic filler is large. . That is, the content of the inorganic filler is proportional to the compressive strength within the setting range.

On the other hand, even when the content of the inorganic filler in Example 3 and the content of the inorganic filler were increased beyond the set range, it can be seen that the maximum compressive strength was not changed as compared with Example 2.

In Comparative Example 1, when high-priced high-density polystyrene was used in place of the waste polystyrene resin foam, it was found that the maximum compressive strength was the same as in Example 2 using a waste polystyrene resin foam. In view of this, when the waste polystyrene resin foam and the inorganic filler are appropriately combined, it is possible to produce a filament which can obtain the same compressive strength as that in the case of using high-priced high-density polystyrene.

On the other hand, it is a method for producing a filament for a 3D printer utilizing the above-described waste polystyrene resin foam (see Fig. 1).

In a first step, the waste polystyrene resin foam is collected (S10).

The first step is a step of collecting the waste polystyrene resin foam that has been discarded after use, and a process such as washing and drying may be selectively added.

In step 2, the pulverized polystyrene resin foam is crushed (S20).

The second step is a step of crushing the pulverized polystyrene resin foam collected in a suitable size using a clearing-dried crusher, wherein the crushing process is replaced or selected as a relatively fine particle shape process than crushing, or crushing and crushing are alternately performed .

In step 3, the waste polystyrene resin foam is melted (S30).

The third step is a step of melting the pulverized particulate waste polystyrene resin foam with an organic solvent. The organic solvent may be, for example, acetone, toluene or the like.

In step 4, the molten waste polystyrene and the mixture are mixed (S40).

In the fourth step, an inorganic filler, a metal powder, and an additive containing molten waste polystyrene melt and graphite are mixed in a stirrer and stirred.

In step 5, the mixture is put in an extruder and extruded (S50).

In the step 5, the mixture is introduced into an extruder and continuously extruded at an extrusion temperature of 100 to 130 DEG C so as to have a diameter of 1.5 to 3 mm.

In step 6, the mixture to be extruded is cut to a predetermined size (S60).

In the sixth step, the mixture extruded from the extruder is cut into a predetermined size by a cutter and then solidified. Filaments having a maximum compressive strength of 25 to 30 MPA are selected and used as filaments.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the same is by way of illustration and example only and is not to be construed as limiting the present invention. It is obvious that the modification or improvement is possible.

Further, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (7)

80 to 90 parts by weight of a melt of a waste polystyrene resin foam melted by an organic solvent, 5 to 10 parts by weight of an inorganic filler containing graphite, 0.5 to 10 parts by weight of a metal powder and 1 to 3 parts by weight of an additive To a filament composition for a 3D printer.
The method according to claim 1,
The inorganic filler is added to 100 parts by weight of graphite in an amount of 1 to 2.5 parts by weight of carbon black, 0.5 to 2 parts by weight of graphite, 0.3 to 1 part by weight of mica, 0.1 to 0.8 parts by weight of silica, 10 to 15 parts by weight of calcium sulfate, By weight of calcium carbonate, 7.4 to 15 parts by weight of magnesium carbonate, 0.5 to 6 parts by weight of barium sulfate, 2 to 8 parts by weight of oxysulfate, 3 to 5 parts by weight of tin oxide, 0.7 to 2.5 parts by weight of kaolin and 5 to 9 parts by weight of silicon carbide Wherein the resin composition is a polypropylene resin.
The method according to claim 1,
Wherein the metal powder is at least one selected from the group consisting of stainless steel, nickel, aluminum, and titanium, and the particle size of the metal powder is 0.1 to 20 占 퐉.
The method according to claim 1,
Wherein the additive comprises a plasticizer, a flame retardant, an antistatic agent, and a crystal nucleating agent,
Wherein the plasticizer is a plasticizer containing 30 to 100 parts by weight of a plasticizer and an additive including isononyl 2-ethylhexanoate, isodecyl 2-ethylhexanoate, 5 to 60 parts by weight based on 100 parts by weight of the thermoplastic resin.
The method of claim 4,
The antistatic agent may be selected from the group consisting of diethylhexyl phthalate (DEHP), di-butyl phthalate (DBP), di-isodecyl phthalate (DIDP), butyl benzyl phthalate phthalate, di-isononyl phthalate (DINP), and di-n-octyl phthalate (DNOP), or a mixture of two or more thereof Filament composition for a 3D printer using a waste polystyrene resin foam.
A filament for a 3D printer utilizing a waste polystyrene resin foam obtained by pelletizing a filament composition for a 3D printer utilizing the waste polystyrene resin foam according to any one of claims 1 to 5.
A method for producing a filament for a 3D printer using the waste polystyrene resin foam according to claim 6,
Collecting and sorting the waste polystyrene resin foam;
Crushing the selected waste polystyrene resin foam to a predetermined size by a crusher;
Melting the pulverized particulate waste polystyrene resin foam with an organic solvent;
Mixing an inorganic filler, a metal powder, and an additive including a melt of a waste polystyrene resin foam and graphite into an agitator to mix;
Continuously injecting the mixture into an extruder and having a diameter of 1.5 to 3 mm at an extrusion temperature of 100 to 130 캜;
A step of selecting a filament having a maximum compressive strength of 25 to 30 MPA by cutting the mixture to be extruded to a predetermined size by a cutter and then solidifying the filament; and a step of selecting a filament having a maximum compressive strength of 25 to 30 MPA by using the waste polystyrene resin foam.

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