JP2022101301A - Filament manufacturing method - Google Patents

Abstract

To provide filaments with high roundness and few bubbles.SOLUTION: The invention provides a method for manufacturing filaments, comprising an extrusion process and a cooling and winding process. In the extrusion process, a melt-mixed raw material resin composition is continuously extruded from an extruder through a mouthpiece to form filaments, and in the cooling and winding process, the filaments are passed through water in a water tank to be cooled and solidified and then wound up. The water temperature in the water tank decreases with distance from the entrance of the water tank.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a filament that can be used in a fused deposition modeling 3D printer.

Patent Document 1 discloses a fused deposition modeling 3D printer in which filaments are extruded from a head and laminated and deposited.

It is important that the filament used in such a 3D printer has a constant wire diameter and a linear alignment close to a perfect circle. In Patent Document 2, a melt-kneaded resin material is continuously extruded from an extruder via a mouthpiece, and the extruded filament is cooled, solidified, and wound to produce a filament.

Special Table 2009-500194 Japanese Unexamined Patent Publication No. 2016-193601

By the way, air and moisture usually remain in the resin material used for manufacturing the filament, and bubbles caused by such air and moisture are formed on the filament. If the filament contains air bubbles, the linear molten resin extruded from the head of the 3D printer also contains air bubbles, which leads to deterioration of the quality of the modeled product obtained by 3D printing.

The present invention has been made in view of such circumstances, and provides a filament having high roundness and few bubbles.

According to the present invention, the filament manufacturing method includes an extrusion step, a cooling step, and a take-up step. In the extrusion step, the melt-kneaded raw material resin composition is continuously extruded from an extruder through a mouthpiece. In the cooling and winding steps, the filament is cooled and solidified by passing through water in the water tank and wound up, and the temperature of the water in the water tank decreases as the distance from the inlet of the water tank increases. A method is provided.

The present inventor has determined that by setting the temperature of the water in the water tank so that the temperature of the water in the water tank decreases as the distance from the inlet of the water tank increases, a filament having high roundness and few bubbles can be obtained. The heading has led to the completion of the present invention.

Preferably, in the method described above, the length of the filament passing through the water in the water tank is L, the temperature of the water that the filament first contacts in the water tank, and the filament exiting the water tank. Assuming that the difference in temperature of the water in contact immediately before is ΔT, ΔT / L is 3 ° C./m or more.
Preferably, in the method described above, the water tank comprises first to fourth zones in order from the inlet side of the water tank, and the filament passes through the first to fourth zones in this order, and the first It is a method in which T1 ≧ T2 ≧ T3 ≧ T4, where T1 to T4 are the temperatures of water in the fourth zone, respectively.

The configuration of the production line 30 of the filament 10 according to the embodiment of the present invention is shown. It is an exploded perspective view of the sizing device 33. FIG. 3 is a cross-sectional view taken along the horizontal plane passing through the center of the filament 10 for the configuration of the water tank 37 in FIG. 1 and its vicinity.

Hereinafter, embodiments of the present invention will be described. The various features shown in the embodiments shown below can be combined with each other. In addition, the invention is independently established for each feature.

1. 1. Filament 10 production line 30
First, the production line 30 of the filament 10 that can be used for carrying out the method for producing the filament 10 according to the embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 1, the production line 30 of the filament 10 includes an extruder 31, a base 32, a sizing device 33, a water tank 37, a fixed roller 41, an outer diameter measuring device 42, and a winding device 43.

The extruder 31 melts and kneads the raw material resin composition and continuously supplies the raw material resin composition to the base 32. For example, the extruder 31 is provided with a cylinder having a built-in screw, a hopper 31a for feeding raw materials, an injection nozzle, and the like. Has been done. The screw of the extruder 31 is not particularly limited, but is preferably a single-screw screw. The extruder 31 melts and kneads the raw material resin composition by rotating the screw in the cylinder and extrudes it from the injection nozzle to the base 32. The raw material can be charged in the form of pellets.

The base 32 extrudes the molten resin from the extruder 31 in the horizontal direction, and the molten resin extruded from the base 32 is cooled to become the filament 10.

The water tank 37 is formed in a long box shape along the transport direction of the filament 10. The filament 10 is introduced into the water tank 37 from the wall at one end of the water tank 37 and is led out from the wall at the other end of the water tank 37. Water 37a for immersing the filament 10 and cooling the filament 10 is stored in the water tank 37.

The sizing device 33 is arranged inside the wall at one end of the water tank 37. The sizing device 33 has a function of increasing the roundness of the filament 10 and making the outer diameter dimension of the filament 10 uniform to a predetermined dimension.

In the sizing device 33, the filament 10 is shaped by vacuum suction. This enhances the roundness. The sizing device 33 can be omitted if it is not needed.

As shown in FIG. 2, the sizing device 33 includes a pair of upper and lower lower members 33D and upper member 33U, and the mating surfaces of the lower member 33D and the lower member 33D are provided with a pair of upper and lower members 33D along the transport direction of the continuous body of the filament 10. A semi-cylindrical surface-shaped first groove 33a through which the filament 10 is passed, and a plurality of vacuums (in this example, seven vacuum lines arranged in parallel with each other) intersecting the first groove 33a so as to be orthogonal to the first groove 33a. A second groove 33b for suction is provided. The number of the second grooves 33b for vacuum suction is arbitrary, and may be appropriately set so that the shaping accuracy of the filament 10 after passing through the sizing device 33 is sufficiently good. Further, the second groove 33b for vacuum suction can be provided not only in the horizontal direction but also in any direction such as a vertical direction and an oblique direction, and is appropriately provided so that the shaping accuracy is sufficiently good. Just set it.

By performing vacuum suction in the sizing device 33, a vacuum suction force acts on the filament 10. As a result, the outer peripheral surface of the filament 10 is attracted to the wall surface facing the space having a circular cross section of the groove 33a provided in the lower member 33D and the upper member 33U, and is shaped into the shape and diameter of the space formed by the groove 33a. As a result, the filament 10 that has passed through the sizing device 33 has a substantially circular cross section, and its diameter substantially coincides with the set value (diameter of the space) and becomes constant.

The fixed roller 41 stabilizes the posture of the filament 10 in the water tank 37 via the sizing device 33, and conveys the filament 10 toward the winding device 43 side.

As shown in FIG. 3, the water tank 37 is divided into a plurality of zones Z1 to Z4 by a partition plate 37b. Zones Z1 to Z4 are arranged in this order from the inlet 37c side of the water tank 37. The filament 10 passes through zones Z1 to Z4 in this order, and is cooled and solidified while passing through the zones Z1 to Z4. A heater and a temperature sensor (not shown) are provided in each zone Z1 to Z4 so that the water temperature can be controlled independently. The partition plate 37b is configured to allow the filament 10 to pass through and to suppress the movement of water between zones. The number of zones is 2 or more, for example, 2 to 10, specifically 2, 3, 4, 5, 6, 7, 8, 9, 10, and any of the numerical values exemplified here. It may be within or above the range between the two.

The outer diameter measuring device 42 measures the outer diameter of the filament 10 cooled in the water tank 37. The take-up device 43 is arranged on the downstream side of a pair of upper and lower take-up rollers 43a that sandwich the filament 10 that has passed through the outer diameter dimension measuring device 42 and convey it to the downstream side, and take up the filament 10. A bobbin winder 43b having a take shaft 43c is provided.

2. 2. Method for Manufacturing Filament Next, a method for manufacturing the filament 10 according to the embodiment of the present invention will be described. Hereinafter, the description will be given with reference to the production line 30, but the method of the present embodiment may be carried out by using an apparatus other than the production line 30.

The method of the present embodiment includes an extrusion process, a sizing process, a cooling process, and a winding process. Hereinafter, each step will be described in detail.

(1) Extrusion Step In the extrusion step, the melt-kneaded raw material resin composition is continuously extruded from the extruder 31 via the base 32 to form the filament 10.

The raw material resin composition contains a thermoplastic resin and may contain additives. Examples of the thermoplastic resin include amorphous resins such as ABS resin, polystyrene, polyvinyl chloride, polymethylmethacrylate, polycarbonate and modified polyphenylene ether, polyolefin resins such as polyethylene and polypropylene, and crystalline resins such as polyester, polyamide and polyvinyl alcohol. , Olefin-based, styrene-based, polyester-based, urethane-based thermoplastic elastomers, and mixtures thereof.

Examples of the additive include inorganic additives such as carbon black, carbon fiber, glass fiber, talc, mica, nanoclay, and magnesium, antioxidants, lubricants, and colorants.

The filament 10 may have a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, in one example, the filament 10 includes a core and a coating layer covering the core. The core and the coating layer can each be formed by using the above-mentioned raw material resin composition. The multi-layered filament 10 can be formed by co-extruding the raw material resin composition that has been melt-kneaded and extruded in each of the plurality of extruders by merging them at the base 32.

Assuming that the diameter of the filament 10 extruded from the base 32 is D1, D1 is, for example, 1.5 to 4 mm, and specifically, for example, 1.5, 1.6, 1.7, 1.8, 1. 9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, It is 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0 mm, and is between any two of the numerical values exemplified here. It may be within the range.

(2) Sizing step In the sizing step, the filament 10 extruded from the base 32 is passed through the sizing device 33 while being vacuum-sucked. As a result, the roundness of the filament 10 is increased, and the outer diameter dimension of the filament 10 is made uniform to a predetermined dimension. The sizing step can be omitted if it is not needed.

Assuming that the diameter of the filament 10 immediately after passing through the sizing device 33 is D2, the value of (D1-D2) is, for example, 0 to 1 mm, preferably 0.1 to 1 mm, and specifically, for example, 0,0. 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 mm, here It may be within the range between any two of the numerical values exemplified in.

(3) Cooling and winding step In the cooling and winding step, the filament 10 is cooled and solidified by passing through the water in the water tank 37 and wound by the winding shaft 43c.

The diameter of the filament 10 is reduced by cooling in the water tank 37. Assuming that the diameter of the filament 10 immediately after cooling in the water tank 37 is D3, the value of (D3-D1) is, for example, 0.01 to 0.5 mm, specifically, for example, 0.01, 0.02. 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, specifically, for example, 0.1, 0.2, 0.2, 0.3, It is 0.3, 0.4, 0.4, 0.5, 0.5 mm, and may be within the range between any two of the numerical values exemplified here.

D3 is, for example, 1.3 to 3.8 mm, preferably 2.0 to 3.8 mm, and specifically, for example, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3. It is 0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8 mm, and is within the range between any two of the numerical values exemplified here. May be.

When D3 is less than 2.0 mm, bubbles are relatively unlikely to be generated in the filament 10, and even if they are generated, bubbles are unlikely to be discharged from the head during 3D printing. On the other hand, when D3 is 2.0 mm or more, bubbles are likely to be generated in the filament 10, and the generated bubbles are likely to be discharged from the head during 3D printing. Therefore, when D3 is 2.0 mm or more, the technical significance of suppressing the generation of bubbles by the present invention is remarkable.

In the present embodiment, the temperature of the water in the water tank 37 is set to decrease as the distance from the inlet 37c of the water tank 37 increases. When the water temperature is set in this way, it is possible to suppress the generation of bubbles in the filament 10 and suppress the decrease in the roundness of the filament 10. Bubbles in the filament 10 are generated when the surface of the filament 10 is rapidly cooled and solidified, and then the inside of the filament 10 contracts to a reduced pressure state. When the temperature of the water in the water tank 37 is set as described above, the timing at which the surface of the filament 10 is solidified is delayed, so that the inside of the filament 10 is less likely to be in a decompressed state, and the generation of bubbles is suppressed.

Let L be the length of the filament 10 passing through the water in the water tank 37, and the temperature of the water that the filament 10 first contacts in the water tank 37 (in this embodiment, the temperature T1 of the water in the first zone Z1) and the filament 10 Let ΔT (= T1-T4) be the difference in the temperature of the water in contact immediately before leaving the water tank 37 (in this embodiment, the temperature T4 of the water in the fourth zone Z4), and ΔT / L is 3 ° C./m or more. Is preferable. If this value is too small, the roundness of the filament 10 tends to decrease, or bubbles tend to be generated in the filament 10. ΔT / L is, for example, 3 to 15 ° C./m, specifically, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 ° C./m. Yes, it may be within or above the range between any two of the numerical values exemplified here. ΔT is, for example, 10 to 50 ° C., specifically, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50 ° C., and is between any two of the numerical values exemplified here. It may be within the range. L is, for example, 1 to 10 m, specifically, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 m, and is between any two of the numerical values exemplified here. It may be within the range of.

The speed at which the filament 10 passes through water in the water tank 37 is, for example, 5 to 15 m / min. Specifically, this speed is, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 m / min, and is within the range between any two of the numerical values exemplified here. May be.

The temperature of the water that the filament 10 first contacts in the water tank 37 is, for example, 50 to 80 ° C. If this temperature is too low, bubbles are likely to be generated in the filament 10, and if this temperature is too high, the roundness of the filament 10 is likely to decrease. Specifically, this temperature is, for example, 50, 55, 60, 65, 70, 75, 80 ° C., and may be in the range between any two of the numerical values exemplified here. The temperature of the water that the filament 10 comes into contact with immediately before leaving the water tank 37 is, for example, 15 to 45 ° C. If this temperature is too low, bubbles are likely to be generated in the filament 10, and if this temperature is too high, the roundness of the filament 10 is likely to decrease. Specifically, this temperature is, for example, 15, 20, 25, 30, 35, 40, 45 ° C., and may be in the range between any two of the numerical values exemplified here.

Assuming that the temperatures of the water in the first to fourth zones Z1 to Z4 are T1 to T4, respectively, it is preferable that T1 ≧ T2 ≧ T3 ≧ T4. “≧” means “=” or “>”.

The filament 10 cooled in the water tank 37 may be wound as it is by the take-up shaft 43c, or may be taken up by the take-up shaft 43c after measuring the outer diameter dimension by the outer diameter dimension measuring device 42. In the latter case, if the obtained outer diameter dimension is outside the standard width range, each manufacturing condition can be reviewed so that the outer diameter is within the standard width range. After the filament 10 having a predetermined length is wound around the take-up shaft 43c, the filament 10 is wound around a new take-up shaft 43c.

By the above steps, the filament 10 wound around the take-up shaft 43c can be manufactured.

The filament 10 preferably has a bubble generation rate of 0 to 5%. By slowly cooling the filament 10 as in the present embodiment, the bubble generation rate can be reduced. Specifically, the bubble generation rate is, for example, 0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5. , 5.0%, which may be within the range between any two of the numerical values exemplified here.

For the bubble generation rate, 100 or more samples were prepared by cutting the filament 10 with a width of 1 cm, the cut surface of this sample was visually observed, and the number of samples in which bubbles with a diameter of 0.3 mm or more were found was counted. , Calculated based on the following formula.
Bubble generation rate (%) = 100 x (number of samples in which bubbles were found) / (number of observed samples)

The filament 10 preferably has a roundness of 1.00 to 1.07. The roundness of the perfect circle is 1, and the closer the cross section of the filament 10 is to the perfect circle, the closer the roundness of the filament 10 is to 1. It is expressed as.). By slowly cooling the filament 10 as in the present embodiment, the roundness can be brought close to 1. Specifically, the roundness of the filament 10 is, for example, 1.00, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, and here. It may be within the range between any two of the exemplified values.

The roundness of the filament 10 can be measured by the following method.
First, the maximum length and the minimum length passing through the center of the filament 10 are measured at each cross section of three or more measurement points of the filament 10 (the distance between adjacent measurement points is 10 cm), and the maximum length and the minimum length are measured at each measurement point. Calculate the roundness (= maximum length / minimum length). The filament 10 has a substantially elliptical shape, and the maximum length and the minimum length correspond to the major axis length and the minor axis length of the ellipse.
-The average value of the roundness at all the measurement points is defined as the roundness of the filament 10.

The filament 10 made of ABS resin was manufactured using the production line 30. The base 32 and the sizing device were set so that D1 to D3 were 3.00 mm, 2.90 mm, and 2.85 mm, respectively. The lengths of zones Z1 to Z4 were set to 0.75 m, respectively. The temperature of the water in zones Z1 to Z4 was set as shown in Table 1. The passing speed of the filament 10 in the water tank 37 was set to 7.2 m / min. For the filaments 10 obtained in each Example / Comparative Example, the bubble generation rate and the roundness were measured. The results are shown in Table 1.

As shown in Table 1, the filaments 10 of all the examples had high roundness and a small bubble generation rate. On the other hand, the filaments 10 of all the comparative examples had a high bubble generation rate or a low roundness. As a result, by setting the temperature of the water in the water tank 37 so that the temperature of the water in the water tank 37 decreases as the distance from the inlet 37c of the water tank 37 increases, the filament 10 having high roundness and few bubbles can be obtained. It shows that it can be obtained.

10: Filament 30: Production line 31: Extruder 31a: Hopper 32: Base 33: Sizing device 33D: Lower member 33U: Upper member 33a: First groove 33b: Second groove 37: Water tank 37a: Water 37b: Partition Plate 37c: Inlet 41: Fixed roller 42: Outer diameter dimension measuring device 43: Winding device 43a: Winding roller 43b: Bobbin winding machine 43c: Winding shaft Z1: First zone Z2: Second zone Z3: Third Zone Z4: Zone 4

Claims (3)

It is a method of manufacturing filaments.
Equipped with extrusion process, cooling and winding process,
In the extrusion step, the melt-kneaded raw material resin composition is continuously extruded from an extruder via a mouthpiece to form filaments.
In the cooling and winding steps, the filament is cooled and solidified by passing it through water in a water tank, and then wound.
A method in which the temperature of water in the aquarium decreases as it moves away from the inlet of the aquarium. The method according to claim 1.
Let L be the length of the filament passing through the water in the water tank, and let ΔT be the difference between the temperature of the water that the filament first contacts in the water tank and the temperature of the water that the filament comes into contact with immediately before leaving the water tank. Then,
ΔT / L is 3 ° C./m or higher, the method. The method according to claim 1 or claim 2.
The water tank includes first to fourth zones in order from the inlet side of the water tank.
The filament passes through the first to fourth zones in this order.
Assuming that the temperatures of water in the 1st to 4th zones are T1 to T4, respectively,
A method in which T1 ≧ T2 ≧ T3 ≧ T4.

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