3D printing material, printing method and preparation method

Abstract

A 3D printing material, a printing method and a preparation method, relating to the technical field of 3D printing. For the 3D printing material, by means of, on the basis of a material only containing a single crystalline polymer, introducing a crystalline polymer having a higher melting point, the obtained 3D printing material has excellent printing warp resistance and heat resistance.

Description

3D printing material, printing method and preparation method Technical Field

[0001] This specification relates to the field of 3D printing technology, and in particular to a 3D printing material, a printing method, and a preparation method. Background Art

[0002] Material-Extrusion-Based 3D Printing (ME-3DP) is one of the most mainstream forms of polymer additive manufacturing technology, with Fused Filament Fabrication (FFF) being a key technique. Its principle is to melt a polymer material at high temperature to achieve melt fluidity, then extrude the melt in a metered manner to form a layered structure. Currently, amorphous polymers are widely used in FFF printing. However, for crystalline polymers, the cooling and shaping process after melt extrusion in FFF printing causes significant volumetric shrinkage in the printed part due to the formation of the polymer crystal structure, generating significant internal stress and causing warping. Therefore, highly crystalline polymers carry a greater risk of warping and a more complex forming mechanism. Specifically, the higher the crystallinity, the stronger the crystallization ability, and the faster the crystallization rate, the greater the risk and severity of warping. However, polymer crystallization is one of the most effective ways to improve the heat resistance of polymer printed parts. Therefore, for crystalline polymer printing materials, how to make them have both excellent printing anti-warping properties and high crystallinity during the printing process to achieve high heat resistance is a common technical problem.

[0003] Therefore, it is necessary to provide a 3D printing material and printing method that can not only ensure good anti-warping performance of the printed parts, but also improve the heat resistance of the printed parts.

[0004] Summary of the Invention

[0005] The main purpose of this specification is to provide a 3D printing material, printing method and preparation method with better heat resistance and printing warping resistance.

[0006] In a first aspect, the present specification provides a 3D printing material, comprising: a first crystalline polymer, the upper limit temperature of the crystalline melting temperature range of which is a first upper limit temperature; and a second crystalline polymer, the lower limit temperature of the crystalline melting temperature range of which is a second lower limit temperature, and the upper limit temperature of the crystalline melting temperature range of which is a second upper limit temperature, and the second lower limit temperature is higher than the first upper limit temperature; wherein, when the 3D printing material is heated to a target printing temperature: the first crystalline polymer melts, the 3D printing material is in a molten fluid state, at least a portion of the second crystalline polymer remains in a crystalline state, and the target printing temperature is between the first upper limit temperature and the second upper limit temperature.

[0007] In some embodiments, the target printing temperature is between the first upper limit temperature and the second lower limit temperature.

[0008] In some embodiments, under preset conditions, the warpage rate of the target part printed by the 3D printing material after cooling is 0-10%, wherein the length of the target part is 150 mm, the width is 9.6 mm, and the height is 20 mm. The preset conditions include: the printing raw material is a wire of the 3D printing material, the diameter specification of the wire is 1.75 mm ± 0.05 mm, the printing nozzle diameter is 0.4 mm, the slicing parameters during printing are a line width of 0.4 mm, a layer height of 0.2 mm, the number of wall layers is 13, the printing speed is 100 mm / s, the printing temperature is 190-230°C, and the base plate temperature is 30-60°C.

[0009] In some embodiments, the warpage rate is 0-5%.

[0010] In some embodiments, the second crystalline polymer is prepared from the same type of polymer with different optical activities.

[0011] In some embodiments, the first crystalline polymer comprises homogeneous crystals composed of a first high molecular weight polymer; and the second crystalline polymer comprises stereocomplex crystals composed of the first high molecular weight polymer.

[0012] In some embodiments, the first crystalline polymer comprises homogeneous crystals of polylactic acid; and the second crystalline polymer comprises stereocomplex crystals of polylactic acid.

[0013] In some embodiments, the first crystalline polymer has a crystalline melting temperature range of 150-180°C; and the second crystalline polymer has a crystalline melting temperature range of 200-250°C.

[0014] In some embodiments, the second crystalline polymer has a crystallinity of 5% to 80%.

[0015] In some embodiments, the second crystalline polymer has a crystallinity of 10% to 50%.

[0016] In some embodiments, the first crystalline polymer comprises homogeneous crystals composed of a first high molecular weight polymer; and the second crystalline polymer comprises homogeneous crystals composed of a second high molecular weight polymer.

[0017] In some embodiments, the first crystalline polymer comprises homogeneous crystals of polylactic acid; and the second crystalline polymer comprises homogeneous crystals of polybutylene terephthalate or homogeneous crystals of polycaprolactam.

[0018] In some embodiments, the first crystalline polymer has a crystalline melting temperature range of 150-180°C; and the second crystalline polymer has a crystalline melting temperature range of 200-250°C.

[0019] In some embodiments, the second crystalline polymer has a crystallinity of 5% to 80%.

[0020] In some embodiments, the second crystalline polymer has a crystallinity of 10% to 50%.

[0021] In a second aspect, this specification provides a method for printing 3D printing materials, comprising: inputting 3D printing materials into a print head of a 3D printer, wherein the 3D printing materials include any of the 3D printing materials described above; and heating the 3D printing materials to a target printing temperature, and curing the 3D printing materials after extruding them from the print head to complete printing.

[0022] In a third aspect, the present specification also provides a method for preparing a 3D printing material, comprising: obtaining a first polymer, the upper limit temperature of the crystalline melting temperature range of which is a first upper limit temperature; and obtaining a second polymer, the lower limit temperature of the crystalline melting temperature range of which is a second lower limit temperature, and the upper limit temperature of the crystalline melting temperature range of which is a second upper limit temperature, and the second lower limit temperature is higher than the first upper limit temperature; mixing the first polymer and the second polymer to obtain a blended composite material including a first crystalline polymer and a second crystalline polymer; and extruding the blended composite material to obtain the 3D printing material, wherein the target printing temperature of the 3D printing material is between the first upper limit temperature and the second upper limit temperature.

[0023] In some embodiments, the first crystalline polymer is L-polylactic acid; the second crystalline polymer is D-polylactic acid; the blended composite material includes stereocomposite crystals of polylactic acid and homogeneous crystals of polylactic acid, the homogeneous crystals include the L-polylactic acid or the D-polylactic acid, and the crystallinity of the stereocomposite crystals in the blended composite material is 5%-80%.

[0024] In some embodiments, the first crystalline polymer comprises homogeneous crystals composed of the first high molecular weight polymer; and the second crystalline polymer comprises homogeneous crystals composed of the second high molecular weight polymer.

[0025] In some embodiments, the first polymer compound includes polylactic acid, and the first crystalline polymer includes homogeneous crystals of the polylactic acid; and the second polymer compound includes polybutylene terephthalate or polycaprolactam, and the second crystalline polymer includes homogeneous crystals of the polybutylene terephthalate or the homogeneous crystals of polycaprolactam.

[0026] As can be seen from the above technical solution, the 3D printing material provided in this specification introduces a crystalline polymer with a higher melting point (a second crystalline polymer) on the basis of a material containing only a single crystalline polymer (a first crystalline polymer), so that the obtained 3D printing material has excellent printing anti-warping and heat resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of this specification, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] FIG1 is a schematic diagram showing the crystallization melting temperature range of 3D printing materials according to some embodiments of this specification;

[0029] FIG2 is a schematic diagram showing the crystallization melting temperature range of 3D printing materials according to some embodiments of this specification;

[0030] FIG3 is a schematic diagram showing a crystallization melting temperature range of a 3D printing material according to some embodiments of this specification;

[0031] FIG4 is a schematic diagram showing a crystallization melting temperature range of a 3D printing material according to some embodiments of this specification;

[0032] FIG5 is a schematic diagram showing a target printing model used in accordance with some embodiments of this specification;

[0033] FIG6 shows a photo of the finished product after printing the 3D printing material in Example 1;

[0034] FIG7 shows a photo of the finished product after printing the 3D printing material in Example 2;

[0035] FIG8 shows a photo of the finished product after printing the 3D printing material in Example 3;

[0036] FIG9 shows a photo of the finished product after printing the 3D printing material in Example 4;

[0037] FIG10 shows a photo of the finished product after printing with the 3D printing material in Comparative Example 1;

[0038] FIG11 shows a photo of the finished product after printing with the 3D printing material in Comparative Example 2. DETAILED DESCRIPTION

[0039] The following description provides specific application scenarios and requirements for this specification, with the goal of enabling those skilled in the art to make and use the contents of this specification. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but is intended to be accorded the broadest scope consistent with the claims.

[0040] To facilitate understanding of this specification, a more comprehensive description of the specification will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of this specification. However, this specification can be implemented in many different forms without departing from the core spirit of this specification and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of this specification.

[0041] The terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. For example, as used herein, the singular forms "a," "an," and "the" may also include the plural forms unless the context clearly indicates otherwise. When used in this specification, the terms "comprise," "include," and / or "contain" are intended to refer to the presence of the associated integers, steps, operations, elements, and / or components, but do not preclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups or the addition of other features, integers, steps, operations, elements, components, and / or groups in the system / method.

[0042] In this application, "X includes at least one of A, B, or C" means that X includes at least A, or X includes at least B, or X includes at least C. In other words, X can include only any combination of A, B, and C, or it can include any combination of A, B, and C as well as other possible contents / elements. The arbitrary combination of A, B, and C can be A, B, C, AB, AC, BC, or ABC.

[0043] These and other features of this specification, as well as the operation and function of the associated elements of the structure, and the economical assembly and manufacture of the components, can be significantly improved by taking into account the following description. The description also includes all figures and text referenced in the drawings herein, all of which form a part of this specification. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale. Meanwhile, for ease of description, the following explanations of terms that may appear in this specification are first provided.

[0044] A crystalline polymer is a copolymer with at least one crystallizable component and sufficient sequence length to form crystals. In a crystalline polymer, regions with regularly arranged molecules are crystalline regions, while regions with disordered molecular arrangement are amorphous regions. The percentage of crystalline regions is referred to as crystallinity. For ease of description, the term "crystalline polymer" is used in this specification to refer to a crystalline polymer having both crystalline and amorphous regions. It should be noted that the first crystalline polymer and the second crystalline polymer in this specification are both crystalline polymers, but the first and second crystalline polymers contain different types of crystals.

[0045] The polymer molecules with side chains or end groups may be the reason why they cannot be completely crystallized. Due to the incomplete crystallization, the crystalline polymers are different from the low molecular weight crystalline compounds and have a clear melting point (T m ), the melting of crystalline polymers is completed within a relatively large temperature range. For ease of description, this specification uses the crystalline melting temperature range to represent the temperature range corresponding to the complete melting of crystalline polymers.

[0046] The lower melting point is the temperature at which the crystals in a crystalline polymer begin to melt. At this temperature, the material's molecular structure begins to change, from an ordered arrangement to a disordered one, causing the material to transition from a solid to a liquid state, thus becoming fluid and plastic.

[0047] In a first aspect, this specification provides a 3D printing material. The material comprises at least two crystalline polymers: a first crystalline polymer and a second crystalline polymer. The first crystalline polymer has a crystalline melting temperature range between a first lower temperature limit T1 and a first upper temperature limit T2; the second crystalline polymer has a crystalline melting temperature range between a second lower temperature limit and a second upper temperature limit. The second lower temperature limit is higher than the first upper temperature limit. In other words, the 3D printing material is formed by mixing two crystalline polymers with different crystalline melting temperature ranges, and the crystalline melting temperature ranges of the first and second crystalline polymers contained in the 3D printing material do not intersect. Thus, when the 3D printing material is heated to a target printing temperature between the first and second upper temperatures, the first crystalline polymer melts, while at least a portion of the second crystalline polymer remains crystalline. Thus, at the target temperature, the 3D printing material is both molten and fluid, and can flow. Furthermore, during cooling, because some of the material remains crystalline, its shrinkage and deformation are less than those of a 3D printing material that is entirely amorphous at the printing temperature.

[0048] The first and second crystalline polymers can be made of polylactic acid, nylon, photosensitive resin, or any combination thereof. For example, the first and second crystalline polymers can be the same type of polymers with different crystal structures, such as homogeneous crystals of polylactic acid and stereocrystals of polylactic acid. Alternatively, the first and second crystalline polymers can be different types of polymers, such as polylactic acid (PLA) and polybutylene terephthalate (PBT), or polylactic acid (PLA) and polycaprolactam (PA6).

[0049] Figure 1 shows a schematic diagram of the crystallization melting temperature range of a 3D printing material according to some embodiments in this specification. As shown in Figure 1, on the temperature coordinate axis, point O represents the first lower limit temperature, point A represents the first upper limit temperature, and the temperature range between OA is the crystallization melting temperature range of the first crystalline polymer; point B represents the second lower limit temperature, point C represents the second upper limit temperature, and the temperature range between BC is the crystallization melting temperature range of the second crystalline polymer. For example, if the temperature corresponding to point A is 100 °C, the first lower limit temperature O of the crystallization melting temperature range corresponding to the first crystalline polymer can be a certain temperature lower than 100 °C, such as temperature values like 99 °C, 90 °C, 80 °C or 70 °C, etc.; at the same time, the crystallization melting temperature range [B, C] of the second crystalline polymer can be higher than point A. For another example, if the temperature corresponding to point A is 180 °C, the first lower limit temperature O of the crystallization melting temperature range corresponding to the first crystalline polymer can be a certain temperature lower than 180 °C, such as temperature values like 120 °C, 130 °C, 140 °C or 150 °C, etc.; at the same time, the crystallization melting temperature range [B, C] of the second crystalline polymer can be higher than point A, for example, [B, C] = [200 °C - 250 °C].

[0050] According to the positions of each point on the temperature coordinate axis, the order of temperatures from low to high is: O < A < B < C. When the 3D printing material is heated to the first lower limit temperature O, the first crystalline polymer begins to melt; when heating continues to point A, the first crystalline polymer is completely melted; when heating continues to point B, the crystals of the second crystalline polymer begin to melt; when the temperature is further increased to point C, the second crystalline polymer is completely melted.

[0051] Based on this, in this specification, the melting states of the first crystalline polymer and the second crystalline polymer contained in the 3D printing material can be adjusted by controlling the temperature, thereby adjusting the overall melting state of the 3D printing material. When the temperature is between point A and point C, the first crystalline polymer in the 3D printing material is completely melted, and a part of the second crystalline polymer is in a molten state. At this time, although there is still part of the second crystalline polymer in the crystal state in the 3D printing material, the 3D printing material as a whole can present a molten fluid state. In this case, since the 3D printing material as a whole presents a molten fluid state, normal printing operations can be completed; and because there is still part of the second crystalline polymer in the crystal state in the 3D printing material, it still shows a solid state, and these crystals are widely distributed at various positions of the molten fluid of the 3D printing material, which can play a role similar to "physical crosslinking points" or "composite filler particles", while improving the heat resistance of the 3D printing material, it can also effectively prevent the 3D printing material from warping and deforming due to internal stress formed by thermal expansion and contraction during the cooling and solidification process after printing, making the 3D printing material have excellent warping resistance. The 3D printing material provided in this specification has both excellent printing warping resistance and heat resistance.

[0052] Therefore, this specification introduces a crystalline polymer with a higher melting point (a second crystalline polymer) into a material containing only a single crystalline polymer (a first crystalline polymer), resulting in a 3D printing material with excellent heat resistance and printing warpage resistance. The printing operating temperature (i.e., the target printing temperature) of the 3D printing material provided in this specification is between the first upper limit temperature and the second upper limit temperature. Furthermore, the 3D printing material provided in this specification can have various forms. For example, depending on actual needs, it can be a filament-type 3D printing material, a granular 3D printing material, or, of course, a 3D printing material with other physical properties.

[0053] Based on the above, it can be seen that for the above-mentioned 3D printing material, the target printing temperature for 3D printing should be between the first upper limit temperature and the second lower limit temperature. Figure 2 shows the situation in which the temperature of the 3D printing material is controlled between points A and B according to some embodiments of this specification. At this point, the first crystalline polymer in the 3D printing material is completely melted, while the second crystalline polymer has not yet begun to melt, and the 3D printing material as a whole can present a molten fluid state. When the 3D printing material as a whole presents a molten fluid state, normal printing operations can be completed. Moreover, because the second crystalline polymer in the 3D printing material is in a crystalline state, these crystals are widely distributed throughout the molten 3D printing material, acting as "physical crosslinking points" or "composite filler particles." While improving the heat resistance of the 3D printing material, it can also effectively prevent warping and deformation caused by internal stress generated by thermal expansion and contraction during the cooling and solidification process after printing, resulting in the 3D printing material having excellent warping resistance. Therefore, the printing operation temperature (i.e., target printing temperature) of the 3D printing material provided in this specification can be further between the first upper limit temperature A and the second lower limit temperature B.

[0054] The 3D printing material can measure the printing warpage performance by the deformation generated during the printing process. The smaller the warpage of the printed 3D printed product, the better the anti-warpage performance of the 3D printing material. The warpage performance can be measured by the warpage rate. The warpage rate can be measured as follows: under a preset target external environment, the 3D printing material of the target size is printed on the target base plate with a target process flow into a target part of a rectangular block of target size (L×W×H), wherein the side of the target part contacting the target base plate is the bottom surface, and its length is L, width is W, and height is H; after the rectangular part cools down, the height of the four corners of the bottom surface of the rectangular part is measured from the target base plate (that is, the distance between the four corners and the highest point of the target base plate), and the average value h is calculated; then the warpage rate warp of the 3D material is defined as: the h value is divided by the height H of the target part, that is, it is calculated using the following formula:

[0055] Obviously, given a constant L, W, and H, the smaller the average height h of the four corners of the bottom surface of the cuboid after cooling, the less deformation the part will experience during cooling, and the lower the warpage. In this specification, warpage performance can be measured by the deformation of the 3D printing material during the printing process. The less warpage a 3D printed product experiences after printing, the better the material's warpage resistance.

[0056] It is understandable that for the same material, under different standard sizes and different external cooling environments, the cooling speed and cooling uniformity of the material are different, so the warpage rate may also be different.

[0057] FIG5 shows a schematic diagram of a target printing model used in some embodiments of this specification. The target dimensions of the target part in the target printing model may be L = 150 mm, W = 9.6 mm, and H = 20 mm. In this case, the following formula is used for calculation:

[0058] According to some embodiments of the present application, the preset target external environment may include: PLA filament with a diameter of 1.75 mm ± 0.05 mm, a nozzle diameter of 0.4 mm, slicing parameters of 0.4 mm line width, 0.2 mm layer height, 13 shells, and a printing speed of 100 mm / s. Furthermore, the printing temperature in this embodiment is adjusted based on the material type and extrusion characteristics. For example, the printing temperature for PLA is 190-230°C, and the base plate temperature is 30-60°C.

[0059] For example, if the target part (printed part) has a length of 150 mm and a height of 20 mm, and the average warpage height h of the four corners after cooling is 1 mm, the warp rate is calculated to be 5%.

[0060] For example, in some embodiments, under the above-mentioned preset printing conditions (i.e., the target part has a length of 150 mm, a width of 9.6 mm, and a height of 20 mm, the preset conditions include: the printing material is a wire of a 3D printing material, the diameter specification of the wire is 1.75 mm ± 0.05 mm, the printing nozzle diameter is 0.4 mm, the slicing parameters during printing are a line width of 0.4 mm, a layer height of 0.2 mm, the number of wall layers is 13, the printing speed is 100 mm / s, the printing temperature is 190-230°C, and the base temperature is 0. The temperature is 30-60°C and the printing air cooling intensity is 100%), and the warpage of the target part printed by the 3D printing material after cooling is 0-10%, that is, the warpage of the target part after cooling can be any percentage between 0% and 10%, for example, it can be 0%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc. Furthermore, the warpage rate of the target part in the present application is maintained between 0% and 5%, that is, the warpage rate can be any percentage between 0% and 5%, for example, it can be 0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, 5.0%, etc.

[0061] In some embodiments, the second crystalline polymer is prepared from the same type of polymer with different optical activities.

[0062] Polymers are formed by the polymerization of monomer molecules. When the monomer molecules of a polymer exhibit different optical activities, the corresponding crystal types may vary. Accordingly, the same type of polymer may include multiple different crystal forms. Within the same type of polymer, different crystal forms also have different physical properties.

[0063] In this specification, the second crystalline polymer in the 3D printing material can be obtained by transforming another crystal form of the same type of polymer. That is, the first crystalline polymer and the second crystalline polymer in the 3D printing material can be derived from the same type of polymer. Because the first crystalline polymer and the second crystalline polymer are of the same type, polymers of the same type have good compatibility.

[0064] In some embodiments, the first crystalline polymer comprises homogeneous crystals composed of the high molecular weight polymer; and the second crystalline polymer comprises stereocomplex crystals composed of the high molecular weight polymer.

[0065] When the polymer crystal types include homogeneous crystals and stereocomplex crystals, the crystalline polymer corresponding to the homogeneous crystals can be used as the first crystalline polymer of the 3D printing material, and the crystalline polymer corresponding to the stereocomplex crystals can be used as the second crystalline polymer of the 3D printing material. Generally speaking, for the same type of polymer, the melting point of the stereocomplex crystals is higher than that of the homogeneous crystals. Therefore, the second lower limit temperature of the second crystalline polymer is higher than the first upper limit temperature of the first crystalline polymer.

[0066] For example, the first crystalline polymer may comprise homogeneous crystals of polylactic acid, and the second crystalline polymer may comprise stereocomplex crystals of the polylactic acid. Of course, those skilled in the art will appreciate that the first crystalline polymer and the second crystalline polymer may also comprise stereocomplex crystals of other materials. For illustrative purposes only, this application uses polylactic acid as an example.

[0067] Polylactic acid (PLA) is an aliphatic polymer compound and a new type of biodegradable polymer material. The polymeric monomer lactic acid exhibits stereoisomerism, with two optical isomers: L-lactic acid and D-lactic acid. Therefore, PLA also has three isomers: left-handed poly L-lactic acid (PLLA), right-handed poly D-lactic acid (PDLA), and racemic poly DL-lactic acid (PDLLA). PLLA and PDLA are both crystalline polymers, while PDLLA is a non-crystalline polymer that lacks crystallinity and is in an amorphous state. The crystallization properties of PLA have a significant impact on its mechanical properties. The regular and dense arrangement of the PLA molecular chains in the crystalline region allows for crystallization, which improves its mechanical properties and heat resistance.

[0068] Under different external environments, different types of crystal forms can be transformed into each other. The crystal formed by pure PLLA or pure PDLA alone is a homogeneous crystal (HC). Stereocomposite crystal (SC) is a special crystal form of polylactic acid, which can be formed in a blend of PLLA and PDLA. Compared with homogeneous crystals, stereocomposite crystals have better heat resistance and chemical stability. In this specification, the first crystalline polymer of the 3D printing material may be a crystalline polymer corresponding to the homogeneous crystal formed by pure PLLA alone, and the second crystalline polymer may be a crystalline polymer corresponding to the stereocomposite crystal formed by PLLA and PDLA; or the first crystalline polymer of the 3D printing material may be a crystalline polymer corresponding to the homogeneous crystal formed by pure PDLA alone, and the second crystalline polymer may be a crystalline polymer corresponding to the stereocomposite crystal formed by PLLA and PDLA.

[0069] In some embodiments, the first crystalline polymer may have a crystalline melting temperature range of 150-180°C; and the second crystalline polymer may have a crystalline melting temperature range of 200-250°C.

[0070] Figure 3 shows a schematic diagram of the crystallization and melting temperature ranges of 3D printing materials according to some embodiments of this specification. As shown in Figure 3, for a 3D printing material made of polylactic acid, point A (the first upper limit temperature) corresponds to 180°C, point B (the second lower limit temperature) corresponds to 200°C, and point C (the second upper limit temperature) corresponds to 250°C.

[0071] For 3D printing materials, when at 150°C, the first crystalline polymer (homogeneous crystals containing polylactic acid) begins to melt; when heated to 180°C, the first crystalline polymer is completely melted; when heated to 200°C, the crystals of the second crystalline polymer (stereocomplex crystals containing polylactic acid) begin to melt; when the temperature continues to rise to 250°C, the second crystalline polymer is completely melted.

[0072] In this specification, the target printing temperature can be controlled between 180°C and 250°C. For example, the target printing temperature can be any one of 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C, or 250°C, or any temperature between any two of the above temperature values. At such a temperature, the homogeneous crystals of polylactic acid in the 3D printing material are completely melted, and a portion of the second crystalline polymer (including stereocomplex crystals of polylactic acid) is in a molten state. At this point, although some of the second crystalline polymer (including stereocomplex crystals of polylactic acid) in the 3D printing material is still in a crystalline state, the 3D printing material as a whole can present a molten fluid state. In this case, when the 3D printing material as a whole is in a molten fluid state, normal printing operations can be completed; and since some second crystalline polymers (including stereocomposite crystals of polylactic acid) in the 3D printing material are in a crystalline state, they still appear to be solid. These crystals are widely distributed in various positions of the molten fluid of the 3D printing material, which can play a role similar to that of "physical cross-linking points" or "composite filling particles". While improving the heat resistance of the 3D printing material, it can also effectively reduce the warping and deformation phenomenon caused by thermal expansion and contraction and crystallization during the cooling and solidification process of the 3D printing material after printing is completed, so that the 3D printing material has excellent anti-warping properties.

[0073] FIG4 is a schematic diagram illustrating the crystallization and melting temperature ranges of 3D printing materials according to some embodiments of this specification. As shown in FIG4 , this specification further provides for controlling the target printing temperature between 180°C and 200°C. For example, the target printing temperature may be any one of 180°C, 182°C, 185°C, 188°C, 190°C, 193°C, 195°C, 197°C, or 200°C, or any temperature between any two of these values. At this point, the homogeneous crystals of polylactic acid in the 3D printing material are completely melted, while the stereocomplex crystals of polylactic acid have not yet begun to melt, resulting in the 3D printing material as a whole being in a molten, fluid state. When the 3D printing material as a whole is in a molten fluid state, normal printing operations can be completed; and because the stereocomposite crystals of polylactic acid in the 3D printing material are completely in a crystalline state, these crystals are widely distributed in various positions of the molten fluid of the 3D printing material, which can play a role similar to "physical cross-linking points" or "composite filling particles". While improving the heat resistance of the 3D printing material, it can also effectively reduce the warping deformation phenomenon caused by thermal expansion and contraction and crystallization-formed internal stress during the cooling and solidification process of the 3D printing material after printing, making the 3D printing material have excellent anti-warping properties.

[0074] In some embodiments, the crystallinity of the second crystalline polymer is 5% to 80%. In 3D printing materials using polylactic acid as a raw material, the crystallinity of the second crystalline polymer is 5% to 80%, that is, the stereocomplex crystals of polylactic acid account for 5% to 80% of the 3D printing material. If the crystallinity of the second crystalline polymer is too low, the effect of effectively improving the heat resistance of the printed part cannot be achieved; if the crystallinity of the second polymer is too high, the degree of insufficient melting of the material at the printing temperature is too high, the melt viscosity is too high, and the wire cannot be extruded for printing. Specifically, the crystallinity of the second crystalline polymer can be any percentage value of 5%, 10%, 20%, 30%, 40%, 50%, 60%, 79%, or 80%, or any percentage between any two of the above percentage values.

[0075] In some embodiments, the second crystalline polymer may have a crystallinity of 10% to 50%. Experimental results show that when the crystallinity of the second crystalline polymer is between 10% and 50%, for example, when the crystallinity of the second crystalline polymer is 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc., the printing material melts moderately during the printing process, exhibits better printing processing performance, and the printed product exhibits superior heat resistance.

[0076] According to some embodiments of the present application, the differential scanning calorimetry (DSC) method is used in this specification to test the crystallinity of 3D printing materials. The specific testing method is as follows:

[0077] (1) Take 3D printing filament as the test object and take 3-8 mg of filament sample;

[0078] (2) Using a differential scanning calorimeter (DSC), the sample was tested under a nitrogen atmosphere for a single heating curve from low temperature to a completely molten state at a heating rate of 10°C / min;

[0079] (3) Obtain the melting enthalpy value ΔH of the second crystalline polymer from the DSC first heating curve m , then the crystallinity of the second crystalline polymer in the 3D printing filament is defined as follows:

[0080] Where, is the theoretical melting enthalpy of complete crystallization of the second crystalline polymer.

[0081] In a second aspect, this specification provides a method for printing 3D printing materials. The method may include: inputting 3D printing materials into the print head of a 3D printer, wherein the 3D printing materials include any of the 3D printing materials described above; and heating the 3D printing materials to a target printing temperature, and curing them after being extruded from the print head to complete printing. The 3D printing materials provided in this specification can be applied to various 3D printing processes to prepare 3D printed products of various forms, and the printing temperature is controlled within the target printing temperature described above during the printing process. The original form of the 3D printing material can be selected or adjusted according to user needs. For example, the 3D printing material provided in this specification can be a melt extrusion 3D printing material, which mainly includes two forms: ① wire material, suitable for wire melt manufacturing; ② granular material, suitable for large-scale additive manufacturing. Currently, the 3D printing materials provided in this specification can also be in other forms, which are not described here one by one.

[0082] In a third aspect, this specification also provides a method for preparing a 3D printing material. The method may include: obtaining L-polylactic acid and D-polylactic acid; mixing the L-polylactic acid and the D-polylactic acid in a predetermined ratio to obtain a composite blend, wherein the composite blend includes stereocomposite crystals of polylactic acid and homogeneous crystals of polylactic acid, the homogeneous crystals including the L-polylactic acid or the D-polylactic acid, and the stereocomposite crystals in the composite blend have a crystallinity of 5% to 80%; and extruding the composite blend to obtain the 3D printing material.

[0083] In this specification, pure left-handed polylactic acid and pure right-handed polylactic acid can be mixed to form stereocomposite crystals of polylactic acid in the blend system. Left-handed polylactic acid and right-handed polylactic acid can be co-crystallized in a ratio of 1:1 to form stereocomposite crystals of polylactic acid. During the preparation process, the addition ratio of left-handed polylactic acid and right-handed polylactic acid can be regulated. When the addition ratio of left-handed polylactic acid to right-handed polylactic acid is not equal to 1, the excess one will form a corresponding homogeneous crystal, and the corresponding blended composite material contains both homogeneous crystals and stereocomposite crystals of polylactic acid, that is, the 3D printing material provided in this specification. Therefore, in order to obtain a 3D printing material containing both homogeneous crystals and stereocomposite crystals of polylactic acid, the preset ratio between L-polylactic acid and D-polylactic acid can be controlled within a certain range deviating from 1:1. For example, the preset ratio can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1 or other ratios.

[0084] In this specification, after the L-polylactic acid and the D-polylactic acid are mixed, the temperature can be controlled within the range of 150-250° C. to ensure that the L-polylactic acid and the D-polylactic acid co-crystallize, thereby forming stereocomplex crystals of polylactic acid.

[0085] The following are specific preparation examples involved in the above content of this disclosure. It should be clear that the following examples are only for illustrating the 3D printing materials, printing methods of 3D printing materials and preparation methods of 3D printing materials disclosed above, and the specific implementation methods and parameters used therein are only one or a concentrated method among the many processes and methods described above. Those skilled in the art can use other parameters according to the above method to prepare the 3D printing materials based on the contents introduced in this specification without deviating from the core spirit disclosed in the application. For example, the following examples use polylactic acid as a raw material to prepare 3D printing materials. Those skilled in the art can fully understand that the above-mentioned 3D printing materials, printing methods of 3D printing materials and preparation methods of 3D printing materials can also apply other raw materials, as long as they comply with the core spirit disclosed in this specification. It is only due to space limitations that this disclosure does not provide a detailed description of the embodiments of other raw materials.

[0086] As mentioned above, the performance tests of the examples and comparative examples in this specification were carried out using the same method.

[0087] 1. Warpage test conditions:

[0088] (1) Target printing model size, rectangular parallelepiped: length L = 150 mm, width W = 9.6 mm, height H = 20 mm;

[0089] (2) Printing material wire diameter specification: 1.75mm±0.05mm, printing nozzle diameter 0.4mm;

[0090] (3) Slicing parameters: line width 0.4 mm, layer height 0.2 mm, number of wall layers (shell) 13;

[0091] (4) Printing speed: 100 mm / s;

[0092] (5) The printing temperature should be matched according to the material type and extrusion characteristics. For example, the printing temperature of PLA material is 190-230℃, and the base plate temperature is 30-60℃;

[0093] (6) Printing air cooling intensity is 100%;

[0094] In the warpage resistance test, the same printer, build plate material, and slicing parameters were used for comparison. After printing, the height of the four corners of the printed part separated from the build plate was measured and the average value h was calculated. The warpage rate was defined as h divided by the total height of the printed part (20mm). It was calculated using the following formula:

[0095] 2. Heat resistance test: GB / T 1633-2000 Thermoplastic Vicat Softening Temperature (VST) is used for determination. 120 The method used a force of 10 N and a heating rate of 120 °C / h.

[0096] 3. Crystallinity test conditions of the second crystalline polymer:

[0097] (1) Take 3D printing filament as the test object and take 3-8 mg of filament sample;

[0098] (2) Using a differential scanning calorimeter (DSC), the sample was tested under a nitrogen atmosphere for a single heating curve from low temperature to a completely molten state at a heating rate of 10°C / min;

[0099] (3) Obtain the melting enthalpy value ΔH of the second crystalline polymer from the DSC first heating curve m , then the crystallinity of the second crystalline polymer in the 3D printing filament is defined as follows:

[0100] Where, is the theoretical melting enthalpy of complete crystallization of the second crystalline polymer.

[0101] Example 1

[0102] This embodiment provides a 3D printing material, which is prepared by the following method: L-polylactic acid and D-polylactic acid are mixed in a molar ratio of 4:1, and the processing temperature is controlled at 150-250°C. The resulting blended composite material is an SC-PLA printing material containing homogeneous crystals and stereocomposite crystals, i.e., a 3D printing material.

[0103] In the preparation method of this embodiment, the raw material contains an excess of L-polylactic acid, and the first crystalline polymer of the corresponding 3D printing material includes an excess of L-polylactic acid. The second crystalline polymer in the 3D printing material is a stereocomplex crystal of polylactic acid. The above-mentioned crystallinity test method is used to control the primary temperature rise range to 30-250°C and the heating rate to 10°C / min. The melting enthalpy value of the second crystalline polymer is 36.4 J / g. Since the theoretical melting enthalpy value of the stereocomplex crystal of polylactic acid is The molecular weight of the second crystalline polymer is 142 J / g, so the crystallinity of the second crystalline polymer is calculated to be 25.6%.

[0104] SC-PLA printing materials were tested for warpage resistance at 210°C to produce printed products. Figure 6 shows a photograph of the finished product. The dimensions of the finished product in Figure 6 are identical to those of the target printed model: a rectangular parallelepiped with a length of 150 mm, a width of 9.6 mm, and a height of 20 mm. As shown in Figure 6, the printed product exhibited no warpage, demonstrating excellent warpage resistance. The warpage rate of the printed product shown in Figure 6 was measured using the aforementioned warpage test method, and the result was a warpage rate of 0.24%.

[0105] At the same time, the printed product was subjected to Vicat heat resistance test, using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A 120 The method uses a force of 10N and a heating rate of 120℃ / h. The Vicat heat resistance temperature of the printed product is measured to be 156.9℃, which has good heat resistance.

[0106] It can be seen that the SC-PLA printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0107] Example 2

[0108] This embodiment provides a 3D printing material, which is prepared by the following method: L-polylactic acid and D-polylactic acid are mixed in a molar ratio of 7:3, and the processing temperature is controlled at 150-250°C. The resulting blended composite material is an SC-PLA printing material containing homogeneous crystals and stereocomposite crystals, i.e., a 3D printing material.

[0109] In the preparation method of this embodiment, the raw material contains an excess of L-polylactic acid, and the first crystalline polymer of the corresponding 3D printing material includes an excess of L-polylactic acid. The second crystalline polymer in the 3D printing material is a stereocomplex crystal of polylactic acid. The above-mentioned crystallinity test method is used to control the primary temperature rise range to 30-250°C and the heating rate to 10°C / min. The melting enthalpy value of the second crystalline polymer is 53.2 J / g. Since the theoretical melting enthalpy value of the stereocomplex crystal of polylactic acid is The molecular weight of the second crystalline polymer is 142 J / g, so the crystallinity of the second crystalline polymer is calculated to be 37.5%.

[0110] SC-PLA printing materials were tested for warpage resistance at 210°C to produce printed products. Figure 7 shows a photograph of the finished product. The dimensions of the finished product in Figure 7 are identical to those of the target print model: a rectangular parallelepiped with a length of 150 mm, a width of 9.6 mm, and a height of 20 mm. As shown in Figure 7, the printed product exhibited no warpage, demonstrating excellent warpage resistance. The warpage rate of the printed product shown in Figure 7 was measured using the aforementioned warpage test method, and the result was a 3% warpage rate.

[0111] At the same time, the printed product was subjected to Vicat heat resistance test, using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A 120 The method uses a force of 10N and a heating rate of 120℃ / h. The Vicat heat resistance temperature of the printed product is measured to be 166.3℃, which has good heat resistance.

[0112] It can be seen that the SC-PLA printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0113] Example 3

[0114] This embodiment provides a 3D printing material, which is prepared by the following method: polylactic acid (PLA) and polybutylene terephthalate (PBT) are mixed in a mass ratio of 4:1, and the processing temperature is controlled at 150-250°C. The resulting blended composite material is a 3D printing material containing PLA crystalline phases and PBT crystalline phases.

[0115] In the preparation method of this embodiment, polylactic acid corresponds to the first crystalline polymer of the 3D printing material, and the second crystalline polymer in the 3D printing material is PBT material. The above-mentioned crystallinity test method is used to control the primary temperature rise range to 30-250°C and the heating rate to 10°C / min. The melting enthalpy value of the second crystalline polymer is 18.4 J / g. Since the theoretical melting enthalpy value of PBT is The molecular weight of the second crystalline polymer is 140.5 J / g, so the crystallinity of the second crystalline polymer is calculated to be 13.1%.

[0116] The printed material was subjected to a warpage resistance test at 210°C to produce a printed product. Figure 8 shows a photograph of the finished product. The dimensions of the finished product in Figure 8 are identical to those of the target printed model: a rectangular parallelepiped with a length of 150 mm, a width of 9.6 mm, and a height of 20 mm. As shown in Figure 8, the printed product exhibited no warpage, demonstrating excellent warpage resistance. The warpage rate of the printed product shown in Figure 8 was measured using the aforementioned warpage test method, and the result was a warpage rate of 0.46%.

[0117] At the same time, the printed product was subjected to Vicat heat resistance test, using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A 120 The method uses a force of 10N and a heating rate of 120℃ / h. The Vicat heat resistance temperature of the printed product is measured to be 144.3℃, which has good heat resistance.

[0118] It can be seen that the PLA printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0119] Example 4

[0120] This embodiment provides a 3D printing material, which is prepared by the following method: polylactic acid (PLA) and polycaprolactam (PA6) are mixed in a mass ratio of 3:1, and the processing temperature is controlled at 150-250°C. The resulting blended composite material is a 3D printing material containing PLA crystalline phases and PA6 crystalline phases.

[0121] In the preparation method of this embodiment, polylactic acid corresponds to the first crystalline polymer of the 3D printing material, and the second crystalline polymer in the 3D printing material is PA6 material. The above-mentioned crystallinity test method is used to control the primary temperature rise range to be 30-250°C, and the heating rate is 10°C / min. The melting enthalpy value of the second crystalline polymer is 37.3 J / g. Due to the theoretical melting enthalpy value of PA6 The molecular weight of the second crystalline polymer is 230 J / g, so the crystallinity of the second crystalline polymer is calculated to be 16.2%.

[0122] The printed material was subjected to a warpage resistance test at 210°C to produce a printed product. Figure 9 shows a photograph of the finished product. The dimensions of the finished product in Figure 9 are identical to those of the target printed model: a rectangular parallelepiped with a length of 150 mm, a width of 9.6 mm, and a height of 20 mm. As shown in Figure 9, the printed product exhibited no warpage, demonstrating excellent warpage resistance. The warpage rate of the printed product shown in Figure 9 was measured using the aforementioned warpage test method, and the result was a warpage rate of 4.2%.

[0123] At the same time, the printed product was subjected to Vicat heat resistance test, using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A 120 The method uses a force of 10N and a heating rate of 120℃ / h. The Vicat heat resistance temperature of the printed product is measured to be 151.5℃, which has good heat resistance.

[0124] It can be seen that the PLA printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0125] Comparative Example 1

[0126] In this comparative example, ordinary L-polylactic acid material was used to prepare 3D printing material according to the same material processing technology as Example 1.

[0127] The same anti-warping printing test method as in Example 1 was used for testing. FIG10 shows a photo of the printed product. As shown in FIG10 , the printed product has excellent anti-warping properties, and the warping rate obtained by the test is 0.21%.

[0128] However, the Vicat softening temperature (VST) of thermoplastics in GB / T 1633-2000 is used for determination. 120 The method uses a force of 10N and a heating rate of 120℃ / h. The test shows that the Vicat heat resistance temperature of the printed part is 61.7℃, indicating that the heat resistance of the 3D printing material prepared in this comparative example is low.

[0129] It can be seen that compared with the material in Example 1, the PLA printing material provided in Comparative Example 1 cannot have both excellent printing anti-warping properties and print heat resistance.

[0130] Comparative Example 2

[0131] In this comparative example, ordinary L-polylactic acid material was used, 1% of a crystallization nucleating agent was added, and the 3D printing material was prepared according to the same material processing process as in Example 1.

[0132] The same anti-warping printing test method as in Example 1 was used for testing. FIG11 shows a photo of the printed product. As shown in FIG11 , the printed product exhibits significant warping, and the warping rate obtained from the test is 17.3%, which exhibits poor anti-warping properties compared to Example 1.

[0133] Under the same experimental conditions, the test showed that the Vicat heat resistance temperature of its printed parts was 160.7℃.

[0134] It can be seen from this that the PLA printing material provided in Comparative Example 2 also fails to have both excellent printing anti-warping properties and heat resistance of printed parts.

[0135] In summary, after reading this detailed disclosure, those skilled in the art will appreciate that the foregoing detailed disclosure may be presented by way of example only and may not be limiting. Although not expressly stated herein, those skilled in the art will understand that this specification is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are intended to be suggested by this specification and are within the spirit and scope of the exemplary embodiments of this specification.

[0136] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0137] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, “one embodiment,” “an embodiment,” and / or “some embodiments” mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is emphasized and should be understood that two or more references to “an embodiment,” “one embodiment,” or “an alternative embodiment” in various parts of this specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be appropriately combined in one or more embodiments of this specification.

[0138] It should be understood that in the foregoing descriptions of the embodiments of this specification, in order to facilitate understanding of a feature and for the purpose of simplifying this specification, this specification sometimes combines various features in a single embodiment, drawing, or description thereof. Alternatively, this specification may disperse various features across multiple embodiments of this specification. However, this does not mean that the combination of these features is necessary. When reading this specification, it is entirely possible for a person skilled in the art to extract some of the features and understand them as separate embodiments. In other words, the embodiments in this specification can also be understood as the integration of multiple secondary embodiments. This also applies when the content of each secondary embodiment is less than all the features of a single aforementioned disclosed embodiment.

Claims

1. A 3D printing material, characterized in that: include: The first crystalline polymer has an upper limit temperature of a crystalline melting temperature range as a first upper limit temperature; as well as a second crystalline polymer, wherein the lower limit temperature of the crystalline melting temperature range is a second lower limit temperature, and the upper limit temperature of the crystalline melting temperature range is a second upper limit temperature, and the second lower limit temperature is higher than the first upper limit temperature; Wherein, when the 3D printing material is heated to the target printing temperature: The first crystalline polymer is melted, and the 3D printing material is in a molten fluid state. at least a portion of the second crystalline polymer remains in a crystalline state, and The target printing temperature is between the first upper limit temperature and the second upper limit temperature.

2. The 3D printing material according to claim 1, characterized in that: The target printing temperature is further between the first upper limit temperature and the second lower limit temperature.

3. The 3D printing material according to any one of claims 1 to 2, characterized in that: Under preset conditions, the target part printed by the 3D printing material has a warpage rate of 0-10% after cooling, wherein the length of the target part is 150 mm, the width is 9.6 mm, and the height is 20 mm, and the preset conditions include: the printing raw material is a wire of the 3D printing material, the diameter specification of the wire is 1.75 mm±0.05 mm, the printing nozzle diameter is 0.4 mm, the slicing parameters during printing are a line width of 0.4 mm, a layer height of 0.2 mm, a wall layer number of 13, a printing speed of 100 mm / s, a printing temperature of 190-230°C, and a base plate temperature of 30-60°C.

4. The 3D printing material according to claim 3, characterized in that: The warpage rate is 0 to 5%.

5. The 3D printing material according to any one of claims 1 to 4, characterized in that: The second crystalline polymer is prepared by using the same type of polymers with different optical activities.

6. The 3D printing material according to any one of claims 1 to 5, characterized in that: The first crystalline polymer comprises homogeneous crystals composed of a first high molecular polymer; and The second crystalline polymer includes stereocomplex crystals composed of the first high molecular weight polymer.

7. The 3D printing material according to any one of claims 1 to 6, characterized in that: The first crystalline polymer comprises homogeneous crystals of polylactic acid; and The second crystalline polymer includes stereocomplex crystals of polylactic acid.

8. The 3D printing material according to claim 7, characterized in that: The first crystalline polymer has a crystalline melting temperature range of 150-180°C; and The second crystalline polymer has a crystalline melting temperature range of 200-250°C.

9. The 3D printing material according to any one of claims 7 to 8, characterized in that: The second crystalline polymer has a crystallinity of 1% to 50%.

10. The 3D printing material according to claim 9, characterized in that: The second crystalline polymer has a crystallinity of 2% to 30%.

11. The 3D printing material according to any one of claims 1 to 5, characterized in that: The first crystalline polymer comprises homogeneous crystals composed of a first high molecular polymer; and The second crystalline polymer includes homogeneous crystals composed of a second high molecular weight polymer.

12. The 3D printing material according to claim 11, characterized in that: The first crystalline polymer comprises homogeneous crystals of polylactic acid; and The second crystalline polymer includes homogeneous crystals of polybutylene terephthalate or homogeneous crystals of polycaprolactam.

13. The 3D printing material according to claim 12, characterized in that: The first crystalline polymer has a crystalline melting temperature range of 150-180°C; and The second crystalline polymer has a crystalline melting temperature range of 200-250°C.

14. The 3D printing material according to any one of claims 12 to 13, characterized in that: The second crystalline polymer has a crystallinity of 1% to 50%.

15. The 3D printing material according to claim 14, characterized in that: The second crystalline polymer has a crystallinity of 2% to 30%.

16. A method for printing 3D printing materials, characterized in that: include: Inputting a 3D printing material into a print head of a 3D printer, wherein the 3D printing material comprises the 3D printing material according to any one of claims 1 to 15; as well as The 3D printing material is heated to a target printing temperature, extruded from the print head and then solidified to complete printing.

17. A method for preparing 3D printing materials, characterized in that: include: A first high molecular polymer is obtained, the upper limit temperature of the crystal melting temperature range of which is a first upper limit temperature; as well as Obtaining a second high molecular polymer, the lower limit temperature of the crystal melting temperature range of which is a second lower limit temperature, and the upper limit temperature of the crystal melting temperature range of which is a second upper limit temperature, and the second lower limit temperature is higher than the first upper limit temperature; Mixing the first high molecular weight polymer and the second high molecular weight polymer to obtain a blended composite material including a first crystalline polymer and a second crystalline polymer; as well as The 3D printing material is obtained by extruding the blended composite material, and the target printing temperature of the 3D printing material is between the first upper limit temperature and the second upper limit temperature.

18. The method according to claim 17, characterized in that The first crystalline polymer is L-polylactic acid; The second crystalline polymer is dextrorotatory polylactic acid; The blended composite material comprises stereocomposite crystals of polylactic acid and homogeneous crystals of polylactic acid, wherein the homogeneous crystals comprise the left-handed polylactic acid or the right-handed polylactic acid, and the crystallinity of the stereocomposite crystals in the blended composite material is 5%-80%.

19. The method according to claim 17, characterized in that The first crystalline polymer includes homogeneous crystals composed of the first high molecular polymer; and The second crystalline polymer includes homogeneous crystals composed of the second high molecular weight polymer.

20. The method of claim 19, wherein: The first high molecular polymer comprises polylactic acid, and the first crystalline polymer comprises homogeneous crystals of the polylactic acid; and The second molecular polymer includes polybutylene terephthalate or polycaprolactam, and the second crystalline polymer includes homogeneous crystals of the polybutylene terephthalate or the homogeneous crystals of the polycaprolactam.

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