Filament for three-dimensional modeling, and method of manufacturing three-dimensional modeled object

Abstract

To provide a method of manufacturing a modeled object having excellent modelability, dimensional accuracy, and designability.SOLUTION: A filament for three-dimensional modeling is made of a polymer having 50 wt% or more of repeating units derived from methyl methacrylate. The filament has a fiber diameter of 1.5 mm or more and 3.0 mm or less. A light transmission loss at a wavelength 650 nm is 0.15 dB / m or more and 40 dB / m or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a three-dimensional modeling filament containing an acrylic resin excellent in transparency, and a method for manufacturing a three-dimensional object using the filament.

Background Art

[0002] As techniques for manufacturing three-dimensional objects (hereinafter sometimes referred to as shaped objects), a material extrusion method, a powder bed fusion method, a vat photopolymerization method, a sheet lamination method, etc. are known. Among these, in the material extrusion method, a filament is mainly used as a material, the filament is extruded from a heated nozzle, selectively deposited at a position corresponding to the cross-section of an object to form a layer, and these layers are adhered and laminated to manufacture a three-dimensional object. The material extrusion method can manufacture a three-dimensional object inexpensively, simply, and quickly compared to other shaping methods, and is preferably used for direct consumer use or large-scale production applications.

[0003] On the other hand, in the material extrusion method, there are almost no filament materials that have excellent dimensional accuracy, designability, and ease of three-dimensional modeling.

[0004] Polylactic acid (PLA) is a material excellent in three-dimensional formability and not easily warped, but its use temperature is low and its chemical stability is also low. When not colored with dyes or pigments, it is inferior in the designability and handleability of three-dimensional objects. ABS resin is widely used for three-dimensional modeling applications of the material extrusion method as a highly weather-resistant thermoplastic resin, but it is a material that is easily warped and not a transparent material.

[0005] Acrylic resins are known for their excellent transparency and weather resistance, and are used in applications such as the core material of optical fibers. However, due to its brittleness and easiness to warp due to hardness, it is not suitable for three-dimensional modeling applications of the material extrusion method.

[0006] In response to such problems, Patent Document 1 discloses a technique for suppressing filament breakage during three-dimensional shaping by using a filament having a composition containing a rubbery graft polymer in an acrylic resin copolymer. Patent Document 2 discloses a technique for providing a filament for a material extrusion method having dimensional stability while maintaining transparency and strength by using a filament composed of an acrylic resin copolymer having a low glass transition temperature and controlled viscosity.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, the technique of Patent Document 1 does not describe an example of actual application to three-dimensional shaping, and it was insufficient to suppress warping of the three-dimensional shaped object obtained by shaping or to obtain a three-dimensional shaped object having good dimensional accuracy. Although the technique of Patent Document 2 improves the formability by lowering the glass transition temperature, there is a problem that the heat resistance of the obtained three-dimensional shaped object is also lowered and the applications are limited.

[0009] Therefore, an object of the present invention is to provide a method for manufacturing a shaped object that is excellent in formability, dimensional accuracy, and designability by using an acrylic resin having a specific light transmittance loss as a filament with a specific diameter for three-dimensional shaping.

Means for Solving the Problems

[0010] In order to solve the above-described problems and achieve the object, the present invention has the following configuration. [1] A three-dimensional modeling filament made of a polymer having 50% by weight or more of repeating units derived from methyl methacrylate, the filament having a fiber diameter of 1.5 mm or more and 3.0 mm or less, and having a light transmission loss at a wavelength of 650 nm of 0.15 dB / m or more and 40 dB / m or less. [2] The three-dimensional modeling filament according to [1], wherein the weight average molecular weight of the polymer is 30,000 or more and 200,000 or less. [3] The three-dimensional modeling filament according to [1] or [2], wherein the complex viscosity of the polymer at 240 °C is 100 Pa·s or more and 10,000 Pa·s or less. [4] The three-dimensional modeling filament according to any one of [1] to [3], wherein the glass transition temperature of the polymer is 100 °C or more and 150 °C or less. [5] The three-dimensional modeling filament according to any one of [1] to [4], wherein the weight loss rate when held at 240 °C for 30 minutes is 1% by weight or less. [6] A method for manufacturing a three-dimensional object, comprising a step of heating the three-dimensional modeling filament according to any one of [1] to [5], and a step of discharging the heated three-dimensional modeling filament onto a plate to form a laminate of the three-dimensional modeling filament on the discharged object. [7] The method for manufacturing a three-dimensional object according to [6], wherein the nozzle temperature for discharging the three-dimensional modeling filament is 200 °C or more and 280 °C or less. [8] The method for manufacturing a three-dimensional object according to [6] or [7], wherein the plate temperature is Tg - 10 °C or more and Tg + 50 °C or less with respect to the glass transition temperature Tg of the polymer constituting the three-dimensional modeling filament. [9] The method for manufacturing a three-dimensional object according to any one of [6] to [8], wherein the heating temperature in the heating step is Tg - 70 °C or more and Tg or less with respect to the glass transition temperature Tg of the polymer constituting the three-dimensional modeling filament. [Effect of the Invention]

[0011] According to the present invention, by using an acrylic resin having a specific light transmission loss as a filament with a specific diameter for three-dimensional shaping, it is possible to manufacture a shaped article excellent in formability, dimensional accuracy, and designability.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be specifically described. However, the present invention is not limited to the following embodiments and can be variously modified and implemented according to the purpose and application.

[0013] In the present invention, "above" means the same as or greater than the numerical value shown therein. Also, "below" means the same as or less than the numerical value shown therein. Further, "less than" means less than the numerical value shown therein.

[0014] The filament for three-dimensional shaping of the present invention has a light transmission loss at a wavelength of 650 nm of 0.15 dB / m or more and 40 dB / m or less. The smaller the light transmission loss, the less the loss when transmitting light, indicating a more transparent filament. In the present invention, when the light transmission loss is 40 dB / m or less, there are few low-molecular-weight impurities, and it is less likely to undergo thermal degradation even in a high-temperature nozzle, and defects, warping, and nozzle blockage of the shaped article are less likely to occur. Furthermore, since the light transmission loss is small and the resin has a high degree of uniformity, a shaped article with high dimensional accuracy can be obtained. The upper limit is preferably 30 dB / m or less, more preferably 20 dB / m or less, still more preferably 10 dB / m or less, particularly preferably 5 dB / m or less, remarkably preferably 3 dB / m or less, and most preferably 1 dB / m or less. Also, in the present invention, when the light transmission loss is 0.15 dB / m or more, rapid shrinkage can be suppressed when softening with a high-temperature nozzle and solidifying on a plate during three-dimensional shaping. The lower limit is preferably 0.20 dB / m or more, more preferably 0.25 dB / m or more, and still more preferably 0.30 dB / m or more.

[0015] In the present invention, the light transmission loss at a wavelength of 650 nm is a value obtained by measuring the optical power A (dBm) at a position 30 m from the incident part and the optical power B (dBm) at a position 2 m from the incident part when parallel light of halogen (wavelength 650 nm, incident NA = 0.25) is incident, and calculating the light transmission loss C (dB / m) from (B - A) / (30 - 2).

[0016] The filament for three-dimensional modeling of the present invention has a fiber diameter of 1.5 mm or more and 3.0 mm or less. If the fiber diameter is too thick, the rigidity of the filament increases, and the filament is likely to break during three-dimensional modeling. If the fiber diameter is too thin, the speed of three-dimensional modeling decreases, and it becomes necessary to increase the filament supply speed, resulting in a decrease in the modeling accuracy. Therefore, 1.65 mm or more and 2.95 mm or less are preferable. When aiming to obtain a shaped object with excellent design properties, 1.70 mm or more and 1.80 mm or less are more preferable. When aiming to obtain a large-sized shaped object, 2.80 mm or more and 2.90 mm or less are more preferable.

[0017] The filament for three-dimensional modeling of the present invention is made of a polymer having 50% by weight or more of repeating units derived from methyl methacrylate. Therefore, in addition to a polymer composed of methyl methacrylate alone, a copolymer with methyl methacrylate is also possible. Specific examples include copolymers of methyl methacrylate and styrene, and copolymers of methyl methacrylate and methacrylic acid esters other than methyl methacrylate such as bornyl methacrylate, but it is not particularly limited. The composition of the monomers that form the polymer at that time is not particularly defined as long as it is a composition for obtaining the polymer determined by the copolymerization ratio or the like. The ratio of the repeating units derived from methyl methacrylate is preferably 70% by weight or more, more preferably 80% by weight or more, still more preferably 90% by weight or more, and particularly preferably 95% by weight or more in terms of being less likely to discolor during three-dimensional modeling and obtaining a more transparent shaped object. The upper limit is 100% by weight.

[0018] The filament for three-dimensional modeling of the present invention preferably has a weight-average molecular weight of the polymer constituting the filament of 30,000 or more and 200,000 or less. The upper limit is more preferably 150,000 or less, still more preferably 120,000 or less, and particularly preferably 100,000 or less in that if the weight-average molecular weight is too large, the adhesiveness to the plate deteriorates and warping is likely to occur. The lower limit is more preferably 40,000 or more, still more preferably 50,000 or more, and particularly preferably 60,000 or more in that if the weight-average molecular weight is too small, it is likely to soften and the peelability from the plate at the end of modeling deteriorates, and further, if the weight molecular weight is small, the shrinkage stress increases during the solidification process and the three-dimensional molded article is likely to warp.

[0019] In the present invention, the weight-average molecular weight is the weight-average molecular weight Mw calculated by using the gel permeation chromatography method and comparing it with the calibration curve using a polymethyl methacrylate standard substance.

[0020] The filament for three-dimensional modeling of the present invention preferably has a complex viscosity at 240 ° C of the polymer of 100 Pa·s or more and 10,000 Pa·s or less. The upper limit is more preferably 8,000 Pa·s or less, still more preferably 6,000 Pa·s or less, and particularly preferably 4,000 Pa·s or less in that if the complex viscosity at 240 ° C is large, the resin extruded from the nozzle during three-dimensional modeling does not soften sufficiently and peels between the resins. The lower limit is more preferably 300 Pa·s or more, still more preferably 500 Pa·s or more, and particularly preferably 1,000 Pa·s or more in that if the complex viscosity is small, the resin selectively extruded from the nozzle onto the plate during three-dimensional modeling cannot maintain its shape and it becomes difficult to form a complex shape.

[0021] In the present invention, the complex viscosity at 240 ° C is a value measured using a rheometer under a nitrogen atmosphere at a parallel plate with a diameter of 25 mm, a gap of 1 mm, an angular frequency of 6.28 rad / s, and a measurement temperature of 240 ° C constant.

[0022] The filament for three-dimensional modeling of the present invention preferably has a glass transition temperature of the polymer constituting the filament of 100°C or higher and 150°C or lower. The upper limit is more preferably 140°C or lower, still more preferably 135°C or lower, and particularly preferably 130°C or lower, because warping due to shrinkage is likely to occur on the plate during three-dimensional modeling. The lower limit is more preferably 105°C or higher, still more preferably 110°C or higher, and particularly preferably 115°C or higher, because the heat resistance is insufficient when a three-dimensional molded object is obtained and the use environment is limited.

[0023] In the present invention, the glass transition temperature is the temperature at the point where a straight line equidistant from the vertical axis direction from the straight lines extending the baseline on the low-temperature side and the high-temperature side intersects the curve of the stepwise change portion of the glass transition in the DSC curve obtained by using a differential scanning calorimeter and heating at a rate of 20°C / min from 30°C to 250°C in a nitrogen atmosphere.

[0024] The filament for three-dimensional modeling of the present invention preferably has a weight loss rate of 1% by weight or less when held at 240°C for 30 minutes. When an acrylic resin is three-dimensionally modeled, a lower volatile content at the temperature at which it is extruded from the nozzle makes it possible to obtain a three-dimensional molded object with higher transparency. Therefore, 0.8% by weight or less is more preferable, 0.6% by weight or less is still more preferable, and 0.5% by weight or less is particularly preferable.

[0025] The filament for three-dimensional modeling of the present invention can be used for three-dimensional modeling by a material extrusion method to obtain a three-dimensional molded object. In the three-dimensional modeling by the material extrusion method, the filament for three-dimensional modeling is introduced into a heated nozzle, and the softened resin is selectively deposited on a heated plate at a position corresponding to the cross-section of the object.

[0026] In the method for manufacturing a three-dimensional object of the present invention, there are a step of heating the three-dimensional modeling filament of the present invention, and a step of discharging the heated three-dimensional modeling filament onto a plate to form a laminate of the three-dimensional modeling filament on the discharged object. The step of heating the three-dimensional modeling filament may be performed during the production of the three-dimensional modeling filament or immediately before three-dimensional modeling as pre-drying. However, in terms of being affected by moisture absorption and the like, it is preferably performed immediately before three-dimensional modeling.

[0027] In the method for manufacturing a three-dimensional object of the present invention, it is preferable that the nozzle temperature for discharging the three-dimensional modeling filament is 200°C or higher and 280°C or lower. The upper limit is more preferably 270°C or lower, still more preferably 260°C or lower, and particularly preferably 250°C or lower, in that if the nozzle temperature is too high, oxidation coloring occurs and transparency is impaired. The lower limit is more preferably 210°C or higher, still more preferably 220°C or higher, and particularly preferably 230°C or higher, in that when the nozzle temperature is low, the resin does not soften sufficiently, resulting in insufficient welding when a three-dimensional object is formed and an increase in voids in the object.

[0028] In the method for manufacturing a three-dimensional object of the present invention, it is preferable that the plate temperature for forming the three-dimensional object is Tg - 10°C or higher and Tg + 50°C or lower with respect to the glass transition temperature Tg of the three-dimensional modeling filament. The upper limit is more preferably Tg + 40°C or lower, still more preferably Tg + 30°C or lower, and particularly preferably Tg + 25°C or lower, in that if the plate temperature is too high, it becomes difficult for the three-dimensional object to maintain its shape on the plate and it becomes difficult to reproduce a delicate structure. The lower limit is more preferably Tg or higher, still more preferably Tg + 5°C or higher, and particularly preferably Tg + 10°C or higher, in that if the plate temperature is low, it becomes difficult to adhere the three-dimensional object to the plate and warping is likely to occur.

[0029] In the method for manufacturing a three-dimensional object of the present invention, it is preferable that the heating temperature in the heating step of the three-dimensional modeling filament is Tg - 70°C or higher and Tg or lower with respect to the glass transition temperature Tg. By performing the heating step, volatile components such as moisture contained in the three-dimensional modeling filament can be reduced, and a more transparent three-dimensional object can be obtained. The upper limit of the temperature at which the heating step is performed is more preferably Tg - 10°C or lower, still more preferably Tg - 20°C or lower, and particularly preferably Tg - 30°C or lower in terms of preventing filament deformation and thermal degradation. The lower limit is more preferably Tg - 60°C or higher, still more preferably Tg - 50°C or higher, and particularly preferably Tg - 45°C or higher because if it is too low, volatile components cannot be sufficiently removed.

Example

[0030] Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to these examples only.

[0031] [Measurement and Evaluation Methods] (1) Light Transmittance Loss at a Wavelength of 650 nm Halogen parallel light (wavelength 650 nm, incident NA = 0.25) was incident, and the light quantity A (dBm) at a position 30 m from the incident part and the light quantity B (dBm) at a position 2 m from the incident part were measured. The light transmittance loss C (dB / m) was obtained from (B - A) / (30 - 2).

[0032] (2) Number-Average Molecular Weight Mn, Weight-Average Molecular Weight Mw, Molecular Weight Distribution Mw / Mn The weight-average molecular weight was calculated by using gel permeation chromatography and comparing it with a calibration curve using a polymethyl methacrylate standard substance to obtain the number-average molecular weight Mn and the weight-average molecular weight Mw. Also, the molecular weight distribution Mw / Mn was obtained from the ratio of Mw to Mn. The measurement sample was prepared by dissolving about 3 mg of polymer powder in about 3 g of hexafluoroisopropanol. Apparatus: Waters e-Alliance GPC system Column: HFIP-806M × 2 manufactured by Showa Denko K.K. Mobile phase: 5 mmol / L sodium trifluoroacetate / hexafluoroisopropanol Flow rate: 1.0 ml / min Temperature: 30 °C Detection: Differential refractive index meter.

[0033] (3) Complex viscosity at 240 °C Using an Anton Paar MCR501, with a parallel plate of 25 mm diameter and a gap of 1 mm, under a nitrogen atmosphere, at an angular frequency of 6.28 rad / s and a constant measurement temperature of 240 °C, the complex viscosity was measured.

[0034] (4) Glass transition temperature Using a differential scanning calorimeter (DSC Q20) manufactured by TA Instruments, under a nitrogen atmosphere, in a DSC curve where the temperature was raised from 30 °C to 30 °C higher than the endothermic peak indicating the melting point of the resin at a rate of 20 °C / min from the endothermic peak indicating the melting point of the resin to a temperature 30 °C higher, the temperature at the point where a straight line equidistant from the vertical axis from the straight lines extending the baseline on the low-temperature side and the high-temperature side intersects the curve of the step-like change part of the glass transition was defined as the glass transition temperature. In the case of an amorphous polymer that does not show a melting point peak, a DSC curve was obtained by raising the temperature from 30 °C to 250 °C. The sample required for the measurement was approximately 8 mg.

[0035] (5) Weight loss rate when held at 240 °C for 30 minutes Using a differential thermal gravimetric analyzer (DTG-60) manufactured by Shimadzu Corporation, under a nitrogen atmosphere, after raising the temperature from 30 °C to 240 °C at a rate of 10 °C / min and then holding at 240 °C for 30 minutes, in the DTG curve, the weight loss amount from raising the temperature from 30 °C to 240 °C and holding for 30 minutes was divided by the weight of the sample and then expressed as a percentage to obtain the weight loss rate. The sample required for the measurement was approximately 10 mg.

[0036] [Example 1] PMMA produced by a continuous polymerization apparatus was continuously extruded from a die and wound around a bobbin to obtain a PMMA filament.

[0037] The light transmission loss of the obtained PMMA filament at a wavelength of 650 nm was 0.4 dB / m, the average fiber diameter was 1.75 mm, the weight average molecular weight Mw = 85,000, the molecular weight distribution Mw / Mn = 1.8, the complex viscosity at 240 °C was 2,700 Pa·s, and the glass transition temperature was 118 °C.

[0038] The PMMA filament was pre-dried in a vacuum dryer at 80 °C for 12 hours. The weight loss rate of the dried filament when held at 240 °C for 30 minutes was 0.39%. This filament was used for three-dimensional modeling.

[0039] Three-dimensional modeling was performed using the three-dimensional modeling device FUNMAT HT manufactured by Intamsys under the conditions of a nozzle temperature of 240 °C, a plate temperature of 140 °C, a chamber temperature of 40 °C, a preheating time of 15 minutes, a nozzle moving speed of 60 mm / s, a filling rate of 20%, and a layer stacking interval of 0.2 mm.

[0040] The peelability from the plate was good, and there was no warping of the molded product. The dimensional accuracy was 79.7 mm in actual size for a data dimension of 80 mm, with an error of 0.4%, which was good. The flexural modulus measured according to Japanese Industrial Standard (JIS standard) JIS K7171 (2016) "Plastics - Method for Determining Flexural Properties" was 2.8 GPa, and the flexural strength was 57 MPa. The transparency was good, and no whitening was observed in the molded product.

[0041] [Example 2] Three-dimensional modeling was performed in the same manner as in Example 1 except that the PMMA filament was not pre-dried before three-dimensional modeling. The weight loss rate of the PMMA filament without pre-drying when held at 240 °C for 30 minutes was 1.45%.

[0042] The peelability from the plate was good, and there was no warping of the molded product. Compared with Example 1, the transparency was inferior, and the molded product was slightly cloudy.

[0043] [Comparative Example 1] Except for using a PMMA filament with a light transmittance loss of 48 dB / m at a wavelength of 650 nm, an average fiber diameter of 1.75 mm, a weight average molecular weight Mw = 35,000, a molecular weight distribution Mw / Mn = 1.7, a complex viscosity of 410 Pa·s at 240°C, and a glass transition temperature of 77°C for three-dimensional shaping, three-dimensional shaping was performed in the same manner as in Example 1. The weight loss rate of the PMMA filament without prior drying when held at 240°C for 30 minutes was 0.46%.

[0044] During three-dimensional shaping, the PMMA filament clogged inside the nozzle, resulting in poor ejection. Also, the peelability of the three-dimensional shaped object from the plate was poor, and the shaped object was damaged when peeled from the plate. No warping was observed in the shaped object. The shaped object was whitened and transparency could not be obtained.

[0045] [Comparative Example 2] Except for changing the plate temperature in three-dimensional shaping to 100°C, three-dimensional shaping was performed in the same manner as in Example 1. The resin extruded from the nozzle immediately showed shrinkage warping on the plate, and shaping could not be performed.

Claims

1. A filament for three-dimensional modeling, which is made of a polymer having 50% by weight or more of repeating units derived from methyl methacrylate, has a fiber diameter of 1.5 mm or more and 3.0 mm or less, and has a light transmission loss at a wavelength of 650 nm of 0.15 dB / m or more and 40 dB / m or less.

2. The filament for three-dimensional modeling according to Claim 1, wherein the weight average molecular weight of the polymer is 40,000 or more and 200,000 or less.

3. The filament for three-dimensional modeling according to Claim 1, wherein the complex viscosity of the polymer at 240 °C is 500 Pa·s or more and 10,000 Pa·s or less.

4. The filament for three-dimensional modeling according to Claim 1, wherein the glass transition temperature of the polymer is 100 °C or more and 150 °C or less.

5. The filament for three-dimensional modeling according to Claim 1, wherein the weight loss rate when held at 240 °C for 30 minutes is 1% by weight or less.

6. A method for manufacturing a three-dimensional object, comprising a step of heating the filament for three-dimensional modeling according to any one of Claims 1 to 5, and a step of discharging the heated filament for three-dimensional modeling onto a plate to form a laminate of the filament for three-dimensional modeling on the discharged object.

7. The method for manufacturing a three-dimensional object according to Claim 6, wherein the nozzle temperature for discharging the filament for three-dimensional modeling is 200 °C or more and 280 °C or less.

8. The method for manufacturing a three-dimensional object according to Claim 6, wherein the plate temperature is Tg - 10 °C or more and Tg + 50 °C or less with respect to the glass transition temperature Tg of the polymer constituting the filament for three-dimensional modeling.

9. The method for manufacturing a three-dimensional object according to Claim 6, wherein the heating temperature in the heating step is Tg - 70 °C or more and Tg or less with respect to the glass transition temperature Tg of the polymer constituting the filament for three-dimensional modeling.