Linear composite material for 3D printing and method for its preparation

Abstract

The application relates to the technical field of 3D printing, and particularly discloses a linear composite material for 3D printing and a preparation method thereof, wherein the preparation method comprises the following steps: S1, preparing PLLA / PCL-PEG-PDLA blend particles; S2, melt-extruding the blend particles to generate a melt filament; S3, performing multiple times of drawing treatment on the melt filament to obtain fiber spinning; S4, bundling the fiber spinning to generate an initial wire; and S5, performing pultrusion forming treatment on the initial wire to obtain the linear composite material; the preparation method is based on the PLLA / PCL-PEG-PDLA blend particles as a base material, the melt filament prepared from the base material is subjected to multiple times of drawing, bundling and pultrusion to obtain the linear composite material with a required size for 3D printing, so that the linear composite material has excellent toughness, crystallinity and size stability.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology, and more specifically, to a linear composite material for 3D printing and a method for preparing the same. Background Technology

[0002] 3D printing technology is a rapid prototyping technology that is completely opposite to traditional material processing methods. It is based on three-dimensional CAD model data and combines a layer-by-layer manufacturing method to directly manufacture three-dimensional physical test model that is completely consistent with the corresponding mathematical model.

[0003] Among them, fused deposition modeling (FDM) has been widely used in industry due to its low cost and simple operation.

[0004] Polylactic acid (PLA) not only has good biocompatibility and biodegradability, but also excellent mechanical properties, making it suitable for various processing methods. It is one of the most competitive biomass polymer materials. Existing 3D printing technology often prepares linear composite materials by mixing various additives into PLA, but it still cannot change the problem of insufficient toughness of linear composite materials due to the low crystallinity of PLA itself. Summary of the Invention

[0005] The purpose of this application is to provide a linear composite material for 3D printing and a method for preparing the same, so that the linear composite material has excellent toughness, crystallinity and dimensional stability.

[0006] In a first aspect, this application provides a method for preparing a linear composite material for 3D printing, the method comprising the following steps:

[0007] S1. Preparation of PLLA / PCL-PEG-PDLA blend particles;

[0008] S2. Melt extrusion of the blend particles to generate melt filaments;

[0009] S3. Perform multiple stretching processes on the molten filament to obtain fiber spinning;

[0010] S4. Bundle the fibers and spin them to form an initial thread;

[0011] S5. The initial wire is subjected to pultrusion molding to obtain the linear composite material.

[0012] The preparation method of the linear composite material for 3D printing of the present application is based on PLLA / PCL-PEG-PDLA blend particles as a base material, and the melt filaments made of the base material are stretched, bundled and pultruded multiple times to obtain a linear composite material with the required size for 3D printing, so that the linear composite material has excellent toughness, crystallinity and dimensional stability.

[0013] The preparation method of the linear composite material for 3D printing, wherein step S1 comprises:

[0014] S11, drying PCL-PEG-PDLA and PLLA respectively;

[0015] S12, mixing 5-15 wt% of PCL-PEG-PDLA with PLLA to obtain a mixture;

[0016] S13, using a double-screw extruder to melt blend and granulate the mixture to obtain the blend particles.

[0017] The preparation method of this example preferably adds 5-15 wt% of PCL-PEG-PDLA to PLLA to prepare the linear composite material, so as to improve the toughness of the linear composite material and avoid the phenomenon of broken filaments during the stretching process.

[0018] The preparation method of the linear composite material for 3D printing, wherein step S12 comprises:

[0019] mixing 5-15 wt% of PCL-PEG-PDLA with PLLA to obtain a preliminary mixture;

[0020] mixing the preliminary mixture with the previously prepared biomass charcoal and the grafting agent, and placing them in a shaker to obtain the mixture.

[0021] In this example, the biomass charcoal can be compatibilized through grafting coupling reaction with PDLA and PLLA through the grafting agent, so that there is interfacial compatibility between PCL-PEG-PDLA and biomass charcoal and between PLLA and biomass charcoal, and part of the material is replaced without affecting the formation of SC between PCL-PEG-PDLA and PLLA, so as to reduce the preparation cost; secondly, the biomass charcoal based on the grafting agent can reduce the brittleness of the linear composite material, thereby avoiding the phenomenon of broken filaments during the stretching process, and can greatly improve the tensile strength of the linear composite material.

[0022] The preparation method of the linear composite material for 3D printing, wherein step S3 comprises:

[0023] S31, cooling the melt filaments to 60-80℃;

[0024] S32, heating the molten filaments after the cooling step S31 to 85-100°C and performing a drawing treatment;

[0025] S33, heating the molten filaments after the drawing treatment in step S32 to 130-150°C;

[0026] S34, cooling the molten filaments after the heating treatment in step S33 to 40-60°C;

[0027] S35, heating the molten filaments after the cooling step S34 to 85-100°C and performing a drawing treatment to obtain the fiber filaments.

[0028] The preparation method of the linear composite material for 3D printing, wherein the length of the cooling treatment in step S34 is greater than the length of the cooling treatment in step S31.

[0029] The preparation method of the linear composite material for 3D printing, wherein step S4 comprises:

[0030] The fiber filaments are bundled based on a bundler to form an initial wire with a cross-sectional diameter greater than a preset diameter.

[0031] The preparation method of the linear composite material for 3D printing, wherein step S5 comprises:

[0032] The initial wire is sequentially subjected to pultrusion molding, natural cooling, and winding into a wire to obtain a linear composite material with a preset cross-sectional diameter.

[0033] The preparation method of the linear composite material for 3D printing, wherein the temperature of the first section of the pultrusion molding process is 140-180°C, the temperature of the second section is 160-220°C, and the pultrusion speed is 0.5-1.5 m / min.

[0034] The preparation method of the linear composite material for 3D printing, wherein the cross-sectional diameter of the linear composite material is 1.70-1.80 mm.

[0035] In a second aspect, the application also provides a linear composite material for 3D printing, which is prepared based on the preparation method of the linear composite material for 3D printing provided in the first aspect.

[0036] The linear composite material for 3D printing of the application is prepared based on the preparation method of the linear composite material for 3D printing provided in the first aspect, which uses PLLA / PCL-PEG-PDLA blend particles as a base material, and the molten filaments made of the base material are subjected to multiple drawing, bundling, and pultrusion to obtain the linear composite material, which has excellent toughness, crystallinity, and dimensional stability.

[0037] As can be seen from the above, the application provides a linear composite material for 3D printing and a preparation method thereof, wherein the preparation method is based on PLLA / PCL-PEG-PDLA blend particles as a base material, and a melt filament made of the base material is subjected to multiple times of drawing, bundling and pultrusion to obtain a linear composite material with a required size for 3D printing, so that the linear composite material has excellent toughness, crystallinity and dimensional stability. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A flow chart of the preparation method of the linear composite material for 3D printing provided in the embodiments of the application. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the application will be clearly and completely described in connection with the drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments of the application. The components of the embodiments of the application described and shown in the drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the application. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the application.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the definitions in this specification prevail.

[0041] Unless otherwise stated, all percentages, parts, ratios, etc., are based upon weight.

[0042] When a range, a preferred range, or a preferred upper and lower limit is given as a range, a preferred range, or a preferred upper and lower limit, it is understood that all ranges formed from any of the upper limit ranges or preferred values and any of the lower limit ranges or preferred values are specifically disclosed, whether the range is expressly disclosed or not. Unless otherwise stated, when a range of values is recited, the stated range is intended to include both the end points thereof, and all integers and fractions within the range. The scope of the application is not limited to the specific values recited when defining a range.

[0043] The terms "about" and "approximately" when used in connection with a numerical value, generally mean that the recited numerical value and all numerical values within experimental error of the recited numerical value (e.g., within a 95% confidence interval of the mean) or within ±10% of the recited numerical value, or within a wider range.

[0044] When numerical values or ranges of values are described herein, it is understood that the disclosure encompasses the specific values or ranges recited, as well as any value or range within the recited values or ranges.

[0045] The expressions "comprising" or "including" or "containing" and variations thereof do not exclude the presence of extra, non-recited elements, steps, or components. The expression "consisting of" excludes any element, step, or component not specified. The expression "consisting essentially of" provides that the range of values or components is limited to those that do not materially affect the essential and novel characteristics of the claimed subject matter. It is to be understood that the expression "comprising" encompasses the expressions "consisting of" and "consisting essentially of". As used herein, the terms "one or more" or "at least one" mean one, two, three, four, five, six, seven, eight, nine, or more.

[0046] Furthermore, unless otherwise noted, singular forms of the components or elements like "a", "an" and "the" include plural referents unless the context clearly indicates otherwise. Thus, for example, reference to "a component" includes a plurality of such components, and so forth.

[0047] It has to be noted that like reference signs refer to like elements throughout the present description. Also, the terms "first", "second", and the like, whenever used in this description do not imply relative importance or a chronological sequence. The terms "first", "second", and the like can simply mean different or distinct elements.

[0048] In a first aspect, referring to Figure 1 Some embodiments of the present application provide a method for preparing a linear composite material for 3D printing, for preparing a linear composite material for 3D printing, the method comprising the following steps:

[0049] S1, preparing PLLA / PCL-PEG-PDLA blend particles;

[0050] S2, melt extruding the blend particles to generate a melt filament;

[0051] S3, performing multiple drawing processes on the melt filament to obtain fiber filaments;

[0052] S4, bundling the fiber filaments to generate an initial wire;

[0053] S5, performing a pultrusion process on the initial wire to obtain a linear composite material.

[0054] Specifically, the PLLA / PCL-PEG-PDLA blend particles are made of PLLA as the main material and PCL-PEG-PDLA as the auxiliary material, that is, PCL-PEG-PDLA is used to improve the performance of PLLA as the matrix, especially to enhance the toughness and strength of PLLA, so that the linear composite material finally made by the preparation method of the embodiment has excellent toughness.

[0055] More specifically, the stereocrystal formed by PLLA and PDLA can play the role of a compatibilizer and a nucleating agent, and PEG plays the role of toughening, so in the embodiment, the triblock copolymer PCL-PEG-PDLA as a modifier of PLLA can have the modification effects of PDLA and PEG on PLLA, so that the toughness of PLLA is greatly improved, and the tensile strength is relatively stable.

[0056] More specifically, PEG can also be used as a solubilizing agent between PCL and PLLA, so that the stereocrystal is formed in situ at the interface between PLLA and PCL and in the PLLA matrix during the reaction blending process, thereby promoting the interface bonding of PLLA and PCL, so that the toughness of the blend particles is effectively improved, and the blend particles have high notched impact strength and elongation at break at the same time; wherein PCL and PLLA both contain carboxyl and hydroxyl groups, and PEG can be used for reaction compatibilization, and in the embodiment, the blending of PLLA and PCL-PEG-PDLA can fully play the toughening effect of PCL.

[0057] More specifically, PCL-PEG-PDLA can also improve the crystallization temperature of PLLA, and the improvement amplitude is closely related to the melting temperature of the blend particles. During the cooling process of the melt extrusion of the blend particles to form the melt filaments in step S2, the SC (stereocrystal formed by PLLA and PDLA) formed in the melt filaments plays the role of heterogeneous nucleation for the α crystal, so that the crystallization temperature of the PLLA material modified based on PCL-PEG-PDLA is higher than that of the pure PLLA material, for example, the crystallization temperature of the PLLA / PCL-PEG-PDLA blend particles prepared by adding 10wt% of PCL-PEG-PDLA is about 127℃, which is higher than 100℃ of the pure PLLA material, so that the tensile temperature and the heat setting temperature of the PLLA / PCL-PEG-PDLA blend particles have a significant difference, thereby facilitating the preparation of the linear composite material and increasing the process fault tolerance.

[0058] It should be noted that the drawing treatment in step S3 should be performed at a material drawing treatment temperature, that is, when the preparation method of the embodiment is performed multiple times, the material needs to be heated to the drawing treatment temperature of the corresponding material before the material is drawn.

[0059] More specifically, the multiple drawing treatment of the molten filaments enables the molten filaments to gradually adjust to the required size, so that the fiber filaments have excellent linear size stability and further oriented crystallization to improve the crystallinity thereof.

[0060] More specifically, the fiber filaments prepared in step S3 have excellent toughness and size uniformity, and the size thereof is much smaller than the size of the linear material required for 3D printing, and the fineness thereof is generally between 0.5-5 dtex, and a plurality of fiber filaments need to be bundled and pultruded to form a linear composite material having a size required for 3D printing by combining steps S4-S5.

[0061] The preparation method of the linear composite material for 3D printing in the embodiments of the present application is based on PLLA / PCL-PEG-PDLA blend particles as a base material, and the molten filaments prepared from the base material are subjected to multiple drawing, bundling and pultrusion to obtain a linear composite material having a size required for 3D printing, so that the linear composite material has excellent toughness, crystallinity and size stability.

[0062] In some preferred embodiments, step S1 comprises:

[0063] S11, drying PCL-PEG-PDLA and PLLA respectively;

[0064] S12, mixing 5-15 wt% of PCL-PEG-PDLA with PLLA to obtain a mixture;

[0065] S13, using a twin-screw extruder to melt blend and granulate the mixture to obtain blend particles.

[0066] Specifically, the melt zone temperature of the twin-screw extruder in step S13 is 190-235°C, the die temperature is 180-200°C, and the rotation speed is 80 r / min.

[0067] More specifically, the PLLA and PCL-PEG-PDLA mixed in step S12 are in powder form.

[0068] More specifically, the more PCL-PEG-PDLA added in step S12, the more stereocrystals in the linear composite material, but it will cause the brittleness of the linear composite material to increase, the preparation cost to increase, and the phenomenon of broken filaments to occur during the drawing process; therefore, the preparation method of the embodiments of the present application preferably adds 5-15 wt% of PCL-PEG-PDLA to the PLLA to prepare the linear composite material, so as to improve the toughness of the linear composite material and avoid the phenomenon of broken filaments during the drawing process.

[0069] In some preferred embodiments, step S11 comprises:

[0070] PCL-PEG-PDLA and PLLA were vacuum dried in an oven at 50°C and 80°C respectively for 8-16 hours to remove moisture in both to ensure that both can be smoothly prepared into melt filaments.

[0071] In some preferred embodiments, step S12 comprises:

[0072] S121, mixing 5-15 wt% of PCL-PEG-PDLA into PLLA to obtain a preliminary mixture;

[0073] S122, mixing the preliminary mixture with the pre-prepared biomass char and grafting agent, and placing them in a shaker to obtain a mixture.

[0074] Specifically, based on the foregoing, the brittleness and the preparation cost of the linear composite material made of the PLLA to which the PCL-PEG-PDLA is added will increase to a certain extent, therefore, the method of the embodiments of the present application compensates for the above defects by adding biomass char.

[0075] More specifically, biomass is subjected to thermo-chemical conversion under anoxic or anaerobic conditions to produce carbon-rich solid substances, which are called biomass char; biomass char is divided into pyrolytic char and hydrothermal char according to the difference between pyrolysis carbonization and hydrothermal carbonization, in the embodiments of the present application, the biomass char in step S122 is preferably pyrolytic char.

[0076] More specifically, in this embodiment, the biomass char can be compatibilized by grafting coupling reaction with PDLA and PLLA through the grafting agent, so that the PCL-PEG-PDLA and the biomass char and the PLLA and the biomass char both have interfacial compatibility, on the premise of not affecting the formation of SC between PCL-PEG-PDLA and PLLA, part of the materials is replaced to reduce the preparation cost; secondly, the biomass char based on the grafting agent can reduce the brittleness of the linear composite material to avoid the phenomenon of broken filaments during the drawing process, and can greatly improve the tensile strength of the linear composite material.

[0077] In some preferred embodiments, step S122 comprises:

[0078] Mixing the preliminary mixture with 5-10 wt% of the pre-prepared biomass char and 0.5-2 wt% of the grafting agent, and placing them in a shaker to obtain a mixture.

[0079] In some preferred embodiments, the oscillation treatment in step S122 is performed by using a high-speed oscillation machine, and the oscillation time is 60-90 seconds, and the oscillation speed is 2400-3600 rpm. In the embodiments of the present application, the oscillation time in step S122 is preferably 80 seconds, and the oscillation speed is preferably 3200 rpm, so as to ensure that the mixture is uniformly mixed by oscillation.

[0080] In some preferred embodiments, 0.1-0.2 wt% of antioxidant is further mixed in step S122.

[0081] Specifically, the antioxidant can inhibit or delay the oxidative degradation of the linear composite material and prolong the service life.

[0082] It should be noted that the draw ratio of the drawing treatment of the melt filament is limited by its tensile strength, and therefore, the draw ratio of the multiple drawing treatments in step S3 should be considered in combination with the material for preparing the melt filament; for example, the melt filament prepared by using the blend particles containing 10 wt% of PCL-PEG-PDLA will not produce broken filaments and fluff when the draw ratio is less than 3.3, and therefore, the product of the draw ratios of the multiple drawing treatments in step S3 should be less than 3.3; for another example, the melt filament prepared by using the blend particles containing 10 wt% of PCL-PEG-PDLA and 10 wt% of biomass charcoal will not produce broken filaments and fluff when the draw ratio is less than 3.8, and therefore, the product of the draw ratios of the multiple drawing treatments in step S3 should be less than 3.8.

[0083] In some preferred embodiments, the number of drawing treatments in step S3 is preferably twice, and step S3 comprises:

[0084] S31, cooling the melt filament to 60-80°C;

[0085] S32, heating the melt filament cooled in step S31 to 85-100°C and performing drawing treatment;

[0086] S33, heating the melt filament after the drawing treatment in step S32 to 130-150°C;

[0087] S34, cooling the melt filament after the heating treatment in step S33 to 40-60°C;

[0088] S35, heating the melt filament cooled in step S34 to 85-100°C and performing drawing treatment to obtain fiber spinning.

[0089] Specifically, the cooling treatment of the molten filaments in steps S31 and S34 can release the internal stress in the material, facilitate the drawing treatment in the next stage and avoid drawing deformation, and also make the molten filaments shrink and solidify to stabilize the shape of the molten filaments; the two-stage drawing treatment and the two-stage cooling treatment are provided, and the second cooling temperature is lower than the first cooling temperature, so that the fiber filaments with smaller size error can be obtained.

[0090] More specifically, based on the foregoing, it can be known that the PCL-PEG-PDLA increases the crystallization temperature of the PLLA (for example, the optimal drawing temperature of the PLLA / PCL-PEG-PDLA prepared by adding 10wt% of the PCL-PEG-PDLA is 85°C, and the optimal crystallization temperature is about 127°C), so that the heat setting temperature of the molten filaments is obviously different from the drawing temperature, the drawing treatment can be performed in a larger temperature error range, and the drawing treatment is ensured to be completed smoothly; in addition, the heating of the molten filaments after the drawing treatment to 130-150°C in step S33 can dry the molten filaments and soften the molten filaments again to be crystallized by cooling again, so as to facilitate the second drawing treatment.

[0091] In some preferred embodiments, the drawing ratio of the drawing treatment in step S35 is less than the drawing ratio of the drawing treatment in step S32.

[0092] Specifically, the drawing treatment is beneficial to improve the diameter precision of the fiber filaments and reduce the diameter error of each position of the fiber filaments; the drawing ratio of the second drawing treatment is set to be less than the drawing ratio of the first drawing treatment, so as to reduce the change amount of the cross-sectional diameter of the molten filaments in the second drawing treatment, and ensure that the fiber filaments obtained in this step have smaller size error.

[0093] In some preferred embodiments, the drawing speed of the drawing treatment in step S35 is greater than the drawing speed of the drawing treatment in step S32.

[0094] Specifically, the drawing speed of the drawing treatment is related to the size stability of the filaments obtained after the treatment, and in the embodiments of the present application, the drawing speed of the drawing treatment in step S35 is set to be greater than the drawing speed of the drawing treatment in step S32, so as to promote the oriented crystallization of the fiber filaments in the second drawing treatment, thereby improving the crystallinity and obtaining linear composites with higher strength.

[0095] In some preferred embodiments, in the embodiments of the present application, the drawing speed of the drawing treatment in step S32 is 20-40m / min; and the drawing speed of the drawing treatment in step S35 is 40-80m / min.

[0096] In some preferred embodiments, the cooling speed is too fast to cause the molten filaments to shrink excessively and result in uneven diameters, and the length of the cooling process in step S34 is preferably set to be greater than the length of the cooling process in step S31, so that the second cooling process is more gentle, thereby allowing the molten filaments to gradually release internal stress and ensuring uniform shrinkage of the diameters thereof everywhere, so as to reduce the dimensional error of the fiber filaments.

[0097] In some preferred embodiments, step S31 preferably uses air cooling or water cooling to cool the molten filaments, and step S34 preferably uses natural cooling.

[0098] In some preferred embodiments, step S4 comprises:

[0099] The bundler bundles the fiber filaments to form an initial wire material with a cross-sectional diameter greater than the preset diameter.

[0100] Specifically, based on the foregoing, the fiber filaments prepared in step S3 have a size less than the diameter required for the linear composite material for 3D printing, and therefore the preparation method of the embodiments of the present application needs to use the bundler to uniformly bundle the fiber filaments to prepare the linear composite material meeting the diameter requirement.

[0101] In some preferred embodiments, step S5 comprises:

[0102] The initial wire material is sequentially subjected to pultrusion, natural cooling, and winding into a wire process to obtain a linear composite material with a cross-sectional diameter of the preset diameter.

[0103] In some preferred embodiments, the temperature of the first section of the pultrusion process is 140-180°C, the temperature of the second section is 160-220°C, and the pultrusion speed is 0.5-1.5 m / min.

[0104] In some preferred embodiments, the cross-sectional diameter of the linear composite material is 1.70-1.80 mm.

[0105] In a second aspect, the present application also provides a linear composite material for 3D printing, which is prepared based on the preparation method of the linear composite material for 3D printing provided in the first aspect.

[0106] The linear composite material for 3D printing of the embodiments of the present application is prepared based on the preparation method of the linear composite material for 3D printing provided in the first aspect, which uses PLLA / PCL-PEG-PDLA blend particles as a base material, and the molten filaments prepared from the base material are subjected to multiple drawing, bundling, and pultrusion, and have excellent toughness, crystallinity, and dimensional stability.

[0107] Example 1

[0108] A1, preparing PLLA / PCL-PEG-PDLA blend particles, the step comprising:

[0109] A11, respectively placing PCL-PEG-PDLA and PLLA in ovens at 50°C and 80°C for vacuum drying for 12 hours to remove moisture in both;

[0110] A12, obtaining a mixture by mixing 5 wt% of PCL-PEG-PDLA with PLLA;

[0111] A13, melt blending and granulating the mixture by using a twin-screw extruder to obtain blend particles.

[0112] A2, melt extruding the blend particles to generate a melt filament;

[0113] A3, performing multiple drawing processes on the melt filament to obtain fiber filaments, the step comprising:

[0114] A31, cooling the melt filament to 80°C;

[0115] A32, heating the melt filament after cooling in step S31 to 90°C and performing a drawing process; the drawing rate of the drawing process is 40 m / min;

[0116] A33, heating the melt filament after the drawing process in step S32 to 140°C;

[0117] A34, cooling the melt filament after the heating process in step S33 to 60°C;

[0118] A35, heating the melt filament after cooling in step S34 to 90°C and performing a drawing process to obtain fiber filaments, the drawing rate of the drawing process in step A35 is 80 m / min;

[0119] A4, bundling multiple fiber filaments to generate an initial wire;

[0120] A5, performing a pultrusion process on the initial wire to obtain a linear composite material, wherein the temperature of the first section of the pultrusion process is 180°C, the temperature of the second section is 220°C, and the pultrusion speed is 1 m / min.

[0121] Example 2

[0122] B1, preparing PLLA / PCL-PEG-PDLA blend particles, the step comprising:

[0123] B11, respectively placing PCL-PEG-PDLA and PLLA in ovens at 50°C and 80°C for vacuum drying for 8 hours to remove moisture in both;

[0124] B12, mixing 15 wt% of PCL-PEG-PDLA and 0.2 wt% of antioxidant into PLLA to obtain a mixture;

[0125] B13, melt blending and granulating the mixture by using a twin-screw extruder to obtain blended granules.

[0126] B2, melt extruding the blended granules to generate a melt filament;

[0127] B3, performing multiple drawing processes on the melt filament to obtain a fiber filament, which comprises:

[0128] B31, cooling the melt filament to 70°C;

[0129] B32, heating the melt filament cooled in step S31 to 100°C and performing a drawing process; the drawing rate of the drawing process is 30 m / min;

[0130] B33, heating the melt filament after the drawing process in step S32 to 130°C;

[0131] B34, cooling the melt filament after the heating process in step S33 to 40°C;

[0132] B35, heating the melt filament cooled in step S34 to 100°C and performing a drawing process to obtain a fiber filament; the drawing rate of the drawing process is 60 m / min;

[0133] B4, bundling multiple fiber filaments to generate an initial wire;

[0134] B5, performing a pultrusion process on the initial wire to obtain a linear composite material, wherein the temperature of the first section of the pultrusion process is 140°C, the temperature of the second section is 160°C, and the pultrusion speed is 0.5 m / min.

[0135] Example 3

[0136] C1, preparing PLLA / PCL-PEG-PDLA blended granules, which comprises:

[0137] C11, vacuum drying PCL-PEG-PDLA and PLLA in ovens at 50°C and 80°C respectively for 16 hours to remove moisture in both;

[0138] C12, mixing 10 wt% of PCL-PEG-PDLA into PLLA to obtain a mixture, which comprises:

[0139] C121, mixing 10 wt% of PCL-PEG-PDLA into PLLA to obtain a preliminary mixture;

[0140] C12, mixing the primary mixture and 10 wt% of biomass char, 2 wt% of grafting agent, 0.1 wt% of antioxidant, and placing in a shaker to shake, to obtain a mixture; wherein the shaking treatment is performed by using a high-speed shaker, and the shaking time is 90 seconds, and the shaking speed is 2400 revolutions / minute;

[0141] C13, melt blending and granulating the mixture by using a twin-screw extruder, to obtain blended granules;

[0142] C2, melt extruding the blended granules to generate a melt filament;

[0143] C3, performing multiple drawing treatments on the melt filament to obtain fiber filaments, which comprises:

[0144] C31, cooling the melt filament to 60°C;

[0145] C32, heating the melt filament after step S31 to 85°C and performing a drawing treatment; the drawing rate of the drawing treatment is 20 m / min.

[0146] C33, heating the melt filament after step S32 to 150°C;

[0147] C34, cooling the melt filament after step S33 to 50°C;

[0148] C35, heating the melt filament after step S34 to 85°C and performing a drawing treatment to obtain fiber filaments; the drawing rate of the drawing treatment is 40 m / min.

[0149] C4, bundling multiple fiber filaments to generate an initial wire;

[0150] C5, performing a pultrusion treatment on the initial wire to obtain a linear composite material, wherein the temperature of the first section of the pultrusion process is 160°C, the temperature of the second section is 190°C, and the pultrusion speed is 1.5 m / min.

[0151] Example 4

[0152] D1, preparing PLLA / PCL-PEG-PDLA blended granules, which comprises:

[0153] D11, respectively placing PCL-PEG-PDLA and PLLA in ovens at 50°C and 80°C for vacuum drying for 12 hours to remove moisture in both;

[0154] D12, mixing 12 wt% of PCL-PEG-PDLA with PLLA to obtain a mixture, which comprises:

[0155] D121, obtain a preliminary mixture by mixing 12wt% of PCL-PEG-PDLA into PLLA;

[0156] D122, mix the preliminary mixture with 5wt% of biomass charcoal, 0.5wt% of grafting agent, and 0.1wt% of antioxidant, and place in a shaker for oscillation to obtain a mixture; wherein the oscillation treatment is performed by using a high-speed shaker, and the oscillation time is 60 seconds, and the oscillation speed is 3600 revolutions / minute;

[0157] D13, melt blend and granulate the mixture by using a twin-screw extruder to obtain blended granules.

[0158] D2, melt extrude the blended granules to generate a melt filament;

[0159] D3, perform multiple drawing treatments on the melt filament to obtain a fiber filament, which comprises:

[0160] D31, cool the melt filament to 65℃;

[0161] D32, heat the melt filament cooled in step S31 to 90℃ and perform a drawing treatment; the drawing rate of the drawing treatment is 35m / min;

[0162] D33, heat the melt filament after the drawing treatment in step S32 to 135℃;

[0163] D34, cool the melt filament after the heating treatment in step S33 to 45℃;

[0164] D35, heat the melt filament cooled in step S34 to 90℃ and perform a drawing treatment to obtain a fiber filament; the drawing rate of the drawing treatment is 75m / min;

[0165] D4, bundle multiple fiber filaments to generate an initial wire;

[0166] D5, perform a pultrusion treatment on the initial wire to obtain a linear composite material, wherein the temperature of the first section of the pultrusion process is 170℃, the temperature of the second section is 200℃, and the pultrusion speed is 0.8m / min.

[0167] Example 5

[0168] E1, prepare PLLA / PCL-PEG-PDLA blended granules, which comprises:

[0169] E11, respectively place PCL-PEG-PDLA and PLLA in ovens at 50℃ and 80℃ for vacuum drying for 14 hours to remove moisture in both;

[0170] E12, mixing 8 wt% of PCL-PEG-PDLA with PLLA to obtain a mixture, which comprises;

[0171] E121, mixing 8 wt% of PCL-PEG-PDLA with PLLA to obtain a preliminary mixture;

[0172] E122, mixing the preliminary mixture with 8 wt% of biomass charcoal, 0.8 wt% of a grafting agent, and 0.15 wt% of an antioxidant, and placing the mixture in a shaker to obtain a mixture; wherein the shaking treatment is performed using a high-speed shaker, and the shaking time is 80 seconds and the shaking speed is 3200 rpm;

[0173] E13, melt blending and granulating the mixture using a twin-screw extruder to obtain blended granules.

[0174] E2, melt extruding the blended granules to generate a melt filament;

[0175] E3, performing multiple drawing treatments on the melt filament to obtain a fiber filament, which comprises:

[0176] E31, cooling the melt filament to 70°C;

[0177] E32, heating the melt filament cooled in step S31 to 85°C and performing a drawing treatment; the drawing rate of the drawing treatment is 35 m / min;

[0178] E33, heating the melt filament after the drawing treatment in step S32 to 140°C;

[0179] E34, cooling the melt filament after the heating treatment in step S33 to 40°C;

[0180] E35, heating the melt filament cooled in step S34 to 85°C and performing a drawing treatment to obtain a fiber filament; the drawing rate of the drawing treatment is 70 m / min;

[0181] E4, bundling multiple fiber filaments to generate an initial wire;

[0182] E5, performing a pultrusion treatment on the initial wire to obtain a linear composite material, wherein the temperature of the first section of the pultrusion process is 165°C, the temperature of the second section is 185°C, and the pultrusion speed is 1 m / min.

[0183] In summary, the embodiments of the present application provide a linear composite material for 3D printing and a preparation method thereof, wherein the preparation method is based on PLLA / PCL-PEG-PDLA blended granules as a base material, and multiple drawing, bundling, and pultrusion treatments are performed on the melt filament made of the base material to obtain a linear composite material with a required size for 3D printing, so that the linear composite material has excellent toughness, crystallinity, and dimensional stability.

[0184] The above merely provides an example of the present application, and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a linear composite material for 3D printing, characterized in that, The method includes the following steps: S1. Preparation of PLLA / PCL-PEG-PDLA blend particles; S2. Melt extrusion of the blend particles to generate melt filaments; S3. Perform multiple stretching processes on the molten filament to obtain fiber spinning; S4. Bundle the fibers and spin them to form an initial thread; S5. Perform pultrusion molding on the initial wire to obtain the linear composite material; Step S1 includes: S11. Dry PCL-PEG-PDLA and PLLA separately; S12. Mix PLLA with 5-15 wt% PCL-PEG-PDLA to obtain a mixture; S13. The mixture is melt-blended and granulated using a twin-screw extruder to obtain the blend particles; Step S12 includes: A preliminary mixture was obtained by mixing PLLA with 5-15 wt% PCL-PEG-PDLA; The preliminary mixture is mixed with the pre-prepared biochar and grafting agent, and then placed in a shaker to obtain the mixture.

2. The method for preparing linear composite materials for 3D printing according to claim 1, characterized in that, Step S3 includes: S31. Cool the molten wire to 60-80°C; S32. Heat the molten wire cooled in step S31 to 85-100℃ and perform a stretching process. S33. Heat the molten wire after the stretching treatment in step S32 to 130-150℃; S34. Cool the molten wire after the heat treatment in step S33 to 40-60℃; S35. Heat the molten yarn cooled in step S34 to 85-100°C and perform a stretching process to obtain the fiber spinning.

3. The method for preparing linear composite materials for 3D printing according to claim 2, characterized in that, The cooling process in step S34 lasts longer than the cooling process in step S31.

4. The method for preparing linear composite materials for 3D printing according to claim 1, characterized in that, Step S4 includes: The fibers are bundled together by a bundler to form an initial wire with a cross-sectional diameter larger than a preset diameter.

5. The method for preparing linear composite materials for 3D printing according to claim 1, characterized in that, Step S5 includes: The initial wire is sequentially subjected to pultrusion molding, natural cooling, and winding into a wire to obtain a linear composite material with a preset cross-sectional diameter.

6. The method for preparing linear composite materials for 3D printing according to claim 1, characterized in that, The temperature of the first section of the pultrusion process is 140-180℃, the temperature of the second section is 160-220℃, and the pultrusion speed is 0.5-1.5m / min.

7. The method for preparing linear composite materials for 3D printing according to claim 1, characterized in that, The cross-sectional diameter of the linear composite material is 1.70-1.80 mm.

8. A linear composite material for 3D printing, characterized in that, It is prepared based on the method for preparing linear composite materials for 3D printing as described in any one of claims 1-7.

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