Composite material for 3D printing, 3D printing wire rod and FFF printing method

Abstract

The invention provides a composite material for 3D printing, which comprises a first crystalline polymer and a second crystalline polymer, and the melting point of the second crystalline polymer is higher than that of the first crystalline polymer; the first crystalline polymer is a continuous matrix phase, the second crystalline polymer is a fiber dispersion phase, and the fiber dispersion phase is continuously distributed in the continuous matrix phase; wherein the fiber dispersion phase comprises a micro-nano-scale fiber structure. Compared with a blending modified material, the continuously distributed fiber dispersion phase is introduced into a common 3D printing material (a continuous matrix phase), so that the heat resistance and the warping resistance of a 3D printing piece can be improved at the same time, and the printing piece obtained through 3D printing by applying the composite material for 3D printing can have high heat resistance and high warping resistance at the same time.

Description

Technical Field

[0001] This specification belongs to the field of 3D printing technology, and specifically relates to a composite material for 3D printing, a 3D printing wire, and an FFF printing method. Background Art

[0002] Material-Extrusion Based 3D printing (ME-3DP) is one of the most mainstream forms of polymer material additive manufacturing technology. Its principle is to melt the polymer material at high temperature to obtain melt fluidity, and then stack it layer by layer in a certain quantitative manner. In extrusion 3D printing technology, fused filament fabrication (FFF) is one of the mainstream technical forms.

[0003] In FFF printing, some materials have poor heat resistance due to their low crystallinity, which limits their application scenarios. For example, polylactic acid (PLA) material is currently the most common printing material in FFF printing. Its excellent anti-warping properties, interlayer adhesion, and full bio-based biodegradability make it the "best and most market-recognized" type of material. However, with the expansion of FFF printing applications, the low heat resistance of PLA material prints (heat softening temperature of about 60°C) has become one of its long-standing pain points. Specifically, the glass transition temperature T of PLA material is about 60°C. g About 60℃, melting temperature T m The temperature of PLA is about 150-180℃. In theory, PLA material has the potential to achieve heat resistance above 100℃. However, its crystallization ability is poor. Under general FFF printing conditions, the crystallization rate is low and the crystallinity of the printed parts is low, resulting in its heat resistance of about 60℃, which can only meet some usage scenarios with low requirements for material heat resistance. In addition, PLA material has poor crystallization ability and low T g , which is also the source of its excellent warping resistance.

[0004] At present, several common technical routes to improve the heat resistance of PLA material prints are:

[0005] (1) Significantly improve the crystallization ability / crystallization rate of PLA materials.

[0006] This technical route is based on improving the crystallization ability of PLA materials, increasing the crystallization nucleation and growth rates during the printing process of PLA materials, so that the printed parts can obtain a higher degree of crystallinity, thereby achieving an improvement in the heat resistance of the printed parts. During the FFF printing process, due to the existence of forced heat dissipation and air cooling, after the material is melted and extruded from the nozzle, the melt will undergo a rapid cooling process. The cooling rate is even as high as hundreds or thousands of °C / s in the initial stage. During the high-speed cooling process, it is difficult for PLA materials to obtain a higher degree of crystallinity. Moreover, even if the above-mentioned crystallization ability problem is solved, there will still be a problem of significantly reduced warpage resistance during the printing of PLA materials due to the formation of a higher degree of crystallinity. The mechanism is that during the cooling / cooling and shaping process of the polymer melt, the formation of a crystal structure causes a large degree of volume shrinkage of the material, which generates internal stress and causes warping of the printed parts.

[0007] (2) PLA material is blended and modified with other materials such as those with high heat resistance.

[0008] PLA materials and other high T g Or high crystallinity materials are blended and modified to prepare blended materials. The improvement of heat resistance of this technical route generally depends on the addition amount of high heat-resistant components. If it is too low, the heat resistance effect will not be significantly improved. If it is too high, the adhesion between the printed layers will be seriously reduced due to the multi-phase system. At the same time, high T g The excessive introduction of highly crystalline materials will also lead to a decrease in the material's resistance to warping.

[0009] (3) Annealing and crystallization process of printed parts.

[0010] T g is the critical temperature at which the polymer molecular chain segments have the ability to move: T g Below the temperature, the polymer molecular chain segments are in a "frozen" state and have no ability to move; T g Above this temperature, the polymer molecular chain segments are "thawed" and have the ability to move. The polymer crystallization process is the process of orderly arrangement of molecular chains, which requires the chain segments to have the ability to move. g Temperatures above 100°C are the objective temperature conditions for polymer crystallization. One of the technical routes to improve the heat resistance of PLA prints is to perform T g Annealing heat treatment above temperature, its mechanism is to heat the PLA print to T g The above process enables the PLA molecular chain segments to move and crystallize, thus improving the crystallinity of the printed parts and further improving the heat resistance, which is called the "annealing crystallization process". g As mentioned above, the molecular chain segments acquire the ability to move, and during the crystallization process, the printed parts are also at risk of deformation. Moreover, adding the annealing crystallization process will also increase the process cost. Summary of the invention

[0011] The purpose of this specification is to provide a composite material for 3D printing, a 3D printing wire and an FFF printing method, so that the printing material suitable for the above-mentioned FFF printing technology can take into account both heat resistance and anti-warping performance.

[0012] The first aspect of this specification provides a composite material for 3D printing, which includes a first crystalline polymer and a second crystalline polymer, the melting point of the second crystalline polymer is higher than the melting point of the first crystalline polymer; the first crystalline polymer is a continuous matrix phase, the second crystalline polymer is a fiber dispersed phase, and the fiber dispersed phase is continuously distributed in the continuous matrix phase; wherein the fiber dispersed phase includes a micro-nanoscale fiber structure. The "micro-nanoscale fiber structure" involved in the above content means that the diameter of the fiber dispersed phase is micro-nanoscale, usually distributed in tens of nanometers, hundreds of nanometers, a few micrometers to tens of micrometers; the micro-nanoscale fiber dispersed phase has a high aspect ratio, a high specific surface area and excellent dispersion, so that it can form an intertwined microfiber network structure at a lower content of the fiber dispersed phase. 3D printing materials containing micro-nanoscale fibers have excellent properties in 3D printing.

[0013] Based on the technical characteristics of 3D printing, this specification uses common 3D printing materials as the continuous matrix phase of the composite material for 3D printing. Based on the selection of the continuous matrix phase, a second crystalline polymer with a higher melting point is used to form a continuously distributed fiber dispersed phase in the continuous matrix phase. The resulting composite material for 3D printing allows the fiber dispersed phase to maintain its micro-nanoscale fiber structure during 3D printing. Based on the high specific surface area and high crystallinity of the fiber structure, it can play a significant role in crystallization heterogeneous nucleation of the continuous matrix phase during 3D printing, thereby improving the crystallinity of the printed part with the continuous matrix phase as the main component, thereby improving the heat resistance of the printed part. Different from the existing method of adding high T g(glass transition temperature) or high crystalline material blending modification, the 3D printing material provided in this specification is to fundamentally improve the crystallinity of the continuous matrix phase and improve its heat resistance, independent of the added modified material itself. In addition, since the melting point of the second crystalline polymer is higher than the melting point of the first crystalline polymer, the heat resistance of the second crystalline polymer is relatively higher, based on which it can also play a positive role in improving the heat resistance of the print. On the other hand, the fiber structure formed by the second crystalline polymer has the characteristics of a high specific surface area, so that the fiber structure can be evenly and closely compounded with the continuous matrix phase, whereby the fiber structure plays a certain skeletal support role for the continuous matrix phase. Thus, the introduction of the fiber dispersed phase will not only not have an adverse effect on the warpage of the print, but can also enhance the anti-warpage of the print to a certain extent. When using the above-mentioned 3D printing composite material for 3D printing, a temperature lower than the melting point of the second crystalline polymer and higher than the melting point of the first crystalline polymer is selected as the printing temperature, so that at the printing temperature, the first crystalline polymer is melted, and the morphology of the second crystalline polymer is not affected, so that the fiber dispersed phase in the 3D printing composite material can preserve the micro-nanoscale fiber structure during the printing process and the crystalline structure is not destroyed. In summary, compared with the blended modified material, this specification can simultaneously improve the heat resistance and warping resistance of the 3D printed part by introducing a continuously distributed fiber dispersed phase into the common 3D printing material (continuous matrix phase), so that the printed part obtained by 3D printing using the 3D printing composite material can take into account both high heat resistance and high warping resistance.

[0014] In some embodiments, the fiber structure is mainly a fiber mesh structure formed by interweaving fibers with an aspect ratio greater than 10.

[0015] In some embodiments, the melting point of the second crystalline polymer is more than 20° C. higher than the melting point of the first crystalline polymer.

[0016] In some embodiments, the difference between the melting point of the second crystalline polymer and the melting point of the first crystalline polymer is no less than 50°C.

[0017] In some embodiments, the mass percentage of the fiber dispersed phase in the composite material for 3D printing is 3% to 40%.

[0018] In some embodiments, the diameter of the fiber structure is 0.1-50 μm, and the fiber structure includes fibers with an aspect ratio greater than 10.

[0019] In some embodiments, the fibrous structure comprises fibers having an aspect ratio of no less than 30.

[0020] In some embodiments, the fibrous structure comprises fibers having an aspect ratio of no less than 50.

[0021] In some embodiments, the fiber structure comprises fibers having an aspect ratio of 65-80.

[0022] In some embodiments, the first crystalline polymer is polylactic acid.

[0023] In some embodiments, the second crystalline polymer includes at least one of a crystalline polyester material, a crystalline polyamide material, a crystalline polyether material, a crystalline polyolefin material, and a crystalline fluoropolymer.

[0024] In some embodiments, the second crystalline polymer includes polyethylene terephthalate, polycaprolactam, polyhexamethylene adipamide, polybutylene terephthalate, polyphenylene sulfide, polyterephthalamide, Hexamethylenediamine At least one of .

[0025] The second aspect of the present specification provides a method for preparing the composite material for 3D printing as described above, comprising: treating a blend of a first crystalline polymer and a second crystalline polymer by an in-situ fiber-forming technique, so that the second crystalline polymer forms a fiber dispersed phase in the first crystalline polymer. The composite material for 3D printing is obtained by the in-situ fiber-forming technique, so that the fiber dispersed phase in the composite material for 3D printing can be distributed in a relatively uniform manner in the continuous matrix phase.

[0026] In some embodiments, the fiber aspect ratio is regulated by adjusting the draft ratio of the material strip during extrusion. The draft ratio is defined as the ratio of the cross-sectional area of ​​the extruded material strip outlet die to the cross-sectional area after cooling and setting. The larger the draft ratio, the larger the fiber aspect ratio. The preferred draft ratio is >2, the preferred draft ratio is >20, and the more preferred draft ratio is >50.

[0027] A third aspect of the present specification provides a 3D printing wire, which is prepared from the composite material for 3D printing as described above.

[0028] In some embodiments, it includes extruding the composite material for 3D printing to form a wire; wherein the highest value of the extrusion temperature section is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer.

[0029] In some embodiments, it includes single-screw extrusion of the composite material for 3D printing to form a wire; wherein the highest value of the extrusion temperature section is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer. By selecting the above extrusion temperature, the 3D printing wire can be obtained in the process of preparing the 3D printing wire without destroying the micro-nanoscale fiber structure of the composite material for 3D printing.

[0030] The fourth aspect of this specification provides the application of the composite material for 3D printing as described above or the 3D printing wire as described above in extrusion 3D printing technology. The application here includes but is not limited to FFF printing.

[0031] In some embodiments, the temperature of 3D printing is lower than the melting point of the second crystalline polymer and higher than the melting point of the first crystalline polymer. Thus, during the 3D printing process, the micro-nano fiber structure of the fiber dispersed phase can be maintained, the crystal structure is not destroyed, and it is directly introduced into the printed part, and the fiber dispersed phase part will not be warped due to the internal stress of the crystal.

[0032] A fifth aspect of the present specification provides an FFF printing method, comprising: performing FFF printing using the 3D printing filament as described above, wherein the printing temperature is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer.

[0033] A sixth aspect of the present specification provides an FFF printed product, which is printed by the FFF printing method described above.

[0034] In some embodiments, the Vicat heat resistance temperature of the FFF printed product is greater than 100°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of this specification, the drawings required for use in the description of the embodiments will be briefly introduced below. 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 paying creative work.

[0036] Figure 1 Schematic diagram of the process principle of in-situ fiber-forming composite materials;

[0037] Figure 2 A schematic diagram of a warping resistance printing model used in accordance with some embodiments of the present specification is shown;

[0038] Figure 3 This is a micrograph of the fiber structure in the 3D printing wire of Example 1 of this specification;

[0039] Figure 4 This is a graph showing the warpage test results of the 3D printed part of Example 1 of this specification;

[0040] Figure 5 This is a micrograph of the fiber structure in the 3D printing wire of Example 2 of this specification;

[0041] Figure 6This is a graph showing the warpage test results of the 3D printed part of Example 2 of this specification;

[0042] Figure 7 This is a micrograph of the fiber structure in the 3D printing wire of Example 3 of this specification;

[0043] Figure 8 This is a graph showing the warpage test results of the 3D printed part of Example 3 of this specification;

[0044] Fig. 9 This is a micrograph of the fiber structure in the 3D printing wire of Example 4 of this specification;

[0045] Fig.10 This is a graph showing the warpage test results of the 3D printed part of Example 4 of this specification;

[0046] Fig.11 This is a micrograph of the fiber structure in the 3D printing wire of Example 5 of this specification;

[0047] Fig.12 This is a graph showing the warpage test results of the 3D printed part of Example 5 of this specification;

[0048] Fig.13 This is a micrograph of the fiber structure in the 3D printing wire of Example 6 of this specification;

[0049] Fig.14 This is a graph showing the warpage test results of the 3D printed part of Example 6 of this specification;

[0050] Fig.15 This is a micrograph of the fiber structure in the 3D printing wire of Example 7 of this specification;

[0051] Fig.16 This is a graph showing the warpage test results of the 3D printed part of Example 7 of this specification;

[0052] Fig.17 This is a graph showing the warpage test results of the 3D printed part of Comparative Example 1 of this specification;

[0053] Fig.18 This is a graph showing the warpage test results of the 3D printed part of Comparative Example 2 of this specification;

[0054] Fig.19 This is a graph showing the warpage test results of the 3D printed part of Comparative Example 3 of this specification;

[0055] Fig. 20 This is a micrograph of the fiber structure in the 3D printing wire of Comparative Example 4 of this specification;

[0056] Fig.21 This is a graph showing the warpage test results of the 3D printed part of comparative example 4 of this specification. DETAILED DESCRIPTION

[0057] The following description provides specific application scenarios and requirements of this specification, with the purpose of enabling those skilled in the art to make and use the contents of this specification. Various local modifications to the disclosed embodiments will be 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 to the widest scope consistent with the claims.

[0058] In order to facilitate the understanding of this specification, the specification will be described more fully below with reference to the relevant drawings. The preferred embodiments of this specification are given in the drawings. 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. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of this specification more thorough and comprehensive.

[0059] The terms used herein are only used for the purpose of describing specific example embodiments and are not restrictive. For example, unless the context clearly indicates otherwise, as used herein, the singular forms "a", "an" and "the" may also include plural forms. When used in this specification, the terms "include", "comprise" and / or "contain" mean that the associated integers, steps, operations, elements and / or components exist, but do not exclude the existence of one or more other features, integers, steps, operations, elements, components and / or groups or that other features, integers, steps, operations, elements, components and / or groups may be added in the system / method.

[0060] In the present 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. That is, X may include any combination of A, B, and C, or X may also include any combination of A, B, and C and other possible contents / elements at the same time. The any combination of A, B, and C may be A, B, C, AB, AC, BC, or ABC.

[0061] In view of the following description, these and other features of this specification, as well as the operation and function of the relevant elements of the structure, and the economy of the combination and manufacture of the parts can be significantly improved. The description also includes all figures and text in the drawings referenced in this specification, all of which form a part of this specification. However, it should be clearly understood that the drawings are only for the purpose of illustration and description and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale. At the same time, for the convenience of description, the terms that may appear in this specification are first explained as follows.

[0062] In-situ fiberization technology refers to a fiber-reinforced material processing method in which after blending multiple incompatible polymers, the dispersed phase in the two-phase system is stretched or sheared by applying an external force field, and the phase morphology is fiberized to form oriented micro-nanoscale fibers in the continuous phase. This fiber-reinforced composite material that uses a special processing technology to form a fiber phase from the dispersed phase "in situ" is figuratively called "in-situ Micro Fibrillation Composites" (iMFC). The principle diagram is shown below. Figure 1 shown.

[0063] A crystalline polymer refers to a copolymer having at least one component that is crystallizable and has a sufficient sequence length to generate crystals. In a crystalline polymer, the region where the molecules are regularly arranged is the crystalline region, and the region where the molecules are disorderly arranged is the amorphous region. The percentage of the crystalline region is called the crystallinity. For ease of description, the crystalline polymer is used in this specification to represent 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, and the first crystalline polymer and the second crystalline polymer contain different types of crystals.

[0064] The first aspect of the present specification provides a composite material for 3D printing, which includes a first crystalline polymer and a second crystalline polymer, the melting point of the second crystalline polymer is higher than the melting point of the first crystalline polymer; the first crystalline polymer is a continuous matrix phase, and the second crystalline polymer is a fiber dispersed phase, and the fiber dispersed phase is continuously distributed in the continuous matrix phase; wherein the fiber dispersed phase includes a micro-nanoscale fiber structure.

[0065] The "micro-nanoscale fiber structure" mentioned in the above content means that the diameter of the fiber dispersed phase is micro-nanoscale, usually distributed in tens of nanometers, hundreds of nanometers, several micrometers to tens of micrometers; the micro-nanoscale fiber dispersed phase has a high aspect ratio, high specific surface area, and excellent dispersion, so that it can form an intertwined microfiber network structure at a lower content of fiber dispersed phase. 3D printing materials that include micro-nanoscale fiber structures have excellent printing performance.

[0066] Based on the technical characteristics of 3D printing, this specification uses common 3D printing materials as the continuous matrix phase of the composite material for 3D printing. Based on the selection of the continuous matrix phase, a second crystalline polymer with a higher melting point is used to form a continuously distributed fiber dispersed phase in the continuous matrix phase. The resulting composite material for 3D printing allows the fiber dispersed phase to maintain its micro-nanoscale fiber structure during 3D printing. Based on the high specific surface area and high crystallinity of the fiber structure, it can play a significant role in crystallization heterogeneous nucleation of the continuous matrix phase during 3D printing, thereby improving the crystallinity of the printed part with the continuous matrix phase as the main component, thereby improving the heat resistance of the printed part. Different from adding high T g (glass transition temperature) or high crystalline materials for blending and modifying 3D printing materials. The 3D printing materials provided in this specification are to improve the crystallinity of the continuous matrix phase and improve its heat resistance, and are independent of the added modified material itself. In addition, since the melting point of the second crystalline polymer is higher than the melting point of the first crystalline polymer, the heat resistance of the second crystalline polymer is relatively higher, and based on this, it can also play a positive role in improving the heat resistance of the print. On the other hand, the fiber structure formed by the second crystalline polymer has the characteristics of high specific surface area, so that the fiber structure can be evenly and tightly compounded with the continuous matrix phase, and thus, the fiber structure plays a certain skeleton support role for the continuous matrix phase. Thus, the introduction of the fiber dispersed phase will not only not have an adverse effect on the warpage of the print, but also can enhance the anti-warpage of the print to a certain extent. When the above-mentioned 3D printing composite material is used for 3D printing, a temperature lower than the melting point of the second crystalline polymer and higher than the melting point of the first crystalline polymer is selected as the printing temperature, so that at the printing temperature, the first crystalline polymer is melted, while the morphology of the second crystalline polymer is not affected, so that the continuous dispersed phase in the composite material for 3D printing can preserve the micro-nanoscale fiber structure and the crystal structure is not destroyed during the printing process.

[0067] In summary, compared with the blended modified materials, this specification can simultaneously improve the heat resistance and warping resistance of 3D printed parts by introducing a continuously distributed fiber dispersed phase into the common 3D printing material (continuous matrix phase), so that the printed parts obtained by 3D printing using the 3D printing composite material can have both high heat resistance and high warping resistance.

[0068] In some embodiments, the fiber structure is mainly a fiber mesh structure formed by interweaving fibers with an aspect ratio greater than 10.

[0069] In some embodiments, the melting point of the second crystalline polymer is more than 20° C. higher than the melting point of the first crystalline polymer.

[0070] In some embodiments, the difference between the melting point of the second crystalline polymer and the melting point of the first crystalline polymer is no less than 50°C.

[0071] In some embodiments, the mass percentage of the fiber dispersed phase in the composite material for 3D printing is 3% to 30%. The content of the fiber dispersed phase in the composite material for 3D printing will affect the processing performance and heat resistance enhancement effect of the material. Controlling the mass percentage of the fiber dispersed phase in the composite material for 3D printing within the above range can not only give full play to the crystallization heterogeneous nucleation effect of the fiber dispersed phase, so that the crystallinity of the 3D printed part is significantly improved, but also help the continuous matrix phase to maintain good printing performance and facilitate the uniform distribution of the fiber dispersed phase in the continuous matrix phase. If the content of the fiber dispersed phase is lower than the above range, the crystallinity of the continuous matrix phase will decrease; if the content of the fiber dispersed phase is higher than the above range, the printing performance of the collective dispersed phase will decrease, the dispersion uniformity of the fiber dispersed phase in the continuous matrix phase will also decrease, and the fiber dispersed phase will be more likely to agglomerate. The mass percentage of the fiber dispersed phase in the composite material for 3D printing can be any value between 3% and 40%. For example, 3%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39% or 40%, but are not limited to the listed values, other values ​​not listed within the numerical range are also applicable.

[0072] According to some embodiments of the present application, the mass percentage of the fiber dispersed phase in the composite material for 3D printing is any value between 3% and 30%.

[0073] According to some embodiments of the present application, the mass percentage of the fiber dispersed phase in the composite material for 3D printing is any value between 5% and 15%.

[0074] In some embodiments, the diameter of the fiber structure is 0.1-50 μm, and the fiber structure includes fibers with an aspect ratio greater than 10.

[0075] Under the premise that the fiber dispersed phase content in the composite material for 3D printing is the same, as the aspect ratio of the fiber structure increases, the 3D printed product made from the above-mentioned composite material for 3D printing has higher heat resistance and higher warping resistance.

[0076] In some embodiments, the fibrous structure comprises fibers having an aspect ratio of no less than 30.

[0077] In some embodiments, the fibrous structure comprises fibers having an aspect ratio of no less than 50.

[0078] In some embodiments, the fiber structure includes fibers with an aspect ratio of 65 to 80. When the aspect ratio of the fiber structure reaches 80, as the aspect ratio of the fiber structure further increases, its effect on improving the heat resistance and warping resistance of the 3D printed product enters a plateau period, and the growth trend of the heat resistance and warping resistance of the 3D printed product slows down.

[0079] In some embodiments, the first crystalline polymer is polylactic acid (PLA). As one of the most common materials for FFF printing, which is one of the mainstream technical forms in the current extrusion 3D printing technology, polylactic acid has the feasibility consistent with the above-mentioned embodiments of this specification, and can solve the long-term technical pain points of the high heat resistance technical route of FFF printing of polylactic acid materials.

[0080] In some embodiments, the second crystalline polymer includes at least one of a crystalline polyester material, a crystalline polyamide material, a crystalline polyether material, a crystalline polyolefin material, and a crystalline fluoropolymer.

[0081] In some embodiments, the second crystalline polymer includes at least one of polyhexamethylene adipamide (nylon 66), polycaprolactam (nylon 6), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and polyhexamethylene terephthalamide (PA6T).

[0082] The second aspect of the present specification provides a method for preparing a composite material for 3D printing as described above, comprising: treating a blend of a first crystalline polymer and a second crystalline polymer by an in-situ fiber-forming technology, so that the second crystalline polymer forms a fiber dispersed phase in the first crystalline polymer. Specifically, the blend is first heated to a temperature above the melting point of the second crystalline polymer; then the blend is led out, and the blend is cooled into a solid during the leading out process. During the cooling and solidification of the blend, the blend is physically stretched. Since the first crystalline polymer and the second crystalline polymer are incompatible, the second crystalline polymer always exists independently of the first crystalline polymer during the above process. Since the melting point of the second crystalline polymer is higher than that of the first crystalline polymer, this makes the temperature between T m1 and T m2 During the time between the first and second crystalline polymers, the second polymer solidifies while the first crystalline polymer remains in a fluid state. Therefore, after being stretched, the second crystalline polymer cools into a solid state before the first crystalline polymer to form fibers. The above-mentioned composite material for 3D printing is obtained by in-situ fiber formation technology, which can achieve a relatively good uniform distribution of the fiber dispersed phase in the continuous matrix phase in the composite material for 3D printing.

[0083] In some embodiments, the aspect ratio of the fiber is controlled by adjusting the draft ratio.

[0084] A third aspect of the present specification provides a 3D printing wire, which is prepared from the composite material for 3D printing as described above.

[0085] In some embodiments, it includes extruding the composite material for 3D printing to form a wire; wherein the highest value of the extrusion temperature section is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer.

[0086] In some embodiments, it includes single-screw extrusion of the composite material for 3D printing to form a wire; wherein the highest value of the extrusion temperature section is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer. By selecting the above extrusion temperature, the 3D printing wire can be obtained in the process of preparing the 3D printing wire without destroying the micro-nanoscale fiber structure of the composite material for 3D printing.

[0087] The fourth aspect of this specification provides the application of the composite material for 3D printing as described above or the 3D printing wire as described above in extrusion 3D printing technology. The application here includes but is not limited to FFF printing.

[0088] In some embodiments, the temperature of 3D printing is lower than the melting point of the second crystalline polymer and higher than the melting point of the first crystalline polymer. In this way, the micro-nano fiber structure of the fiber dispersed phase can be maintained during the 3D printing process, and the crystal structure is not destroyed, and is directly introduced into the printed part, and the fiber dispersed phase part will not be warped due to the internal stress of the crystal.

[0089] A fifth aspect of the present specification provides an FFF printing method, comprising: performing FFF printing using the 3D printing filament as described above, wherein the printing temperature is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer.

[0090] A sixth aspect of the present specification provides an FFF printed product, which is printed by the FFF printing method described above.

[0091] In some embodiments, the Vicat heat resistance temperature of the FFF printed product is greater than 100°C.

[0092] The 3D printing composite materials and preparation methods thereof in the above embodiments are designed based on the material defects existing in the 3D printing behavior. The existing printing materials (such as polylactic acid) are used as the continuous matrix phase, and the fiber dispersed phase with a high melting point is introduced therein to prepare the 3D printing composite materials containing micro-nano fiber structure. Through the in-situ fiber forming process, the fiber dispersed phase forms a micro-nano fiber structure with a high specific surface area, which can play a significant role in crystallization heterogeneous nucleation and promote the crystallinity of the continuous matrix phase. At the same time, the micro-nano fiber structure can be used as a reinforcing phase. Under the condition of low content of fiber dispersed phase, the micro-nano fiber structure can form a microfiber grid structure in the continuous dispersed phase, thereby having an excellent reinforcing effect on the printed part and improving its anti-warping performance. In summary, based on the high crystallinity and high heat resistance of the micro-nano fiber structure, the 3D printing composite material provided in this specification has both better heat resistance and excellent anti-warping performance.

[0093] In the process of 3D printing using the above-mentioned composite materials for 3D printing, printing is performed below the melting point of the fiber dispersed phase. As a result, the fiber dispersed phase, i.e., the microfiber structure, can be "preserved" while the crystal structure is not destroyed and can be directly introduced into the printed part. The fiber dispersed phase part will not experience warping caused by internal crystal stress.

[0094] The features and performance of the present invention are further described in detail below in conjunction with the embodiments and comparative examples.

[0095] The test method of the aspect ratio of the fiber structure in the examples and comparative examples of this specification is as follows: the first crystalline polymer in the wire is removed by an organic solvent, the second crystalline polymer is extracted, and the fiber is spread on a glass slide. The fiber is observed under a microscope, the length of more than 100 fibers is measured and the average length LM is obtained by averaging, and the diameter of more than 10 fibers is measured and the average diameter D is obtained by averaging. The aspect ratio of the fiber is defined as: L M Divide by the diameter D, that is, use the following formula to calculate:

[0096]

[0097] The anti-warping printing test method in the embodiments and comparative examples of this specification is as follows:

[0098] Under a preset target external environment, the 3D printing material of the target size is printed on a target base plate with a target process flow into a target part of a cuboid of target size (L×W×H), Figure 2A schematic diagram of a target printing model used in some embodiments of the present specification is shown, 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 is cooled, the heights of the four corners of the bottom surface of the rectangular part away from the target base plate (that is, the distances between the four corners and the highest point of the target base plate) are measured, and the average value h is calculated; then the warp value of the 3D material is defined as: h value divided by the height H of the target part, that is, calculated using the following formula:

[0099]

[0100] Obviously, when L, W, and H are constant, the smaller the average height h of the four corners of the bottom surface of the cuboid from the ground after cooling, the smaller the deformation of the part during cooling, and the smaller the warping rate. In this specification, the anti-warping performance of the printing can be measured by the deformation generated by the 3D printing material during the printing process. The smaller the warping degree of the 3D printed product after printing, the better the anti-warping performance of the 3D printing material.

[0101] It is understandable that for the same material, under different standard sizes and different external cooling environments, the cooling speed and uniformity of the material are different, so the warpage may also be different.

[0102] According to some embodiments of the present application, the preset target external environment may include: the printing material is PLA wire, the wire diameter specification is 1.75mm±0.05mm, the printing nozzle diameter is 0.4mm, the slicing parameters during printing are line width 0.4mm, layer height 0.2mm, wall layer number (shell) 13, and printing speed 100mm / s. In addition, the printing temperature in this embodiment is matched as appropriate 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℃.

[0103] For example, if the target part (printed part) is 150 mm long and 20 mm high, and the average warping height h of the four corners after cooling is 1 mm, the Warp curvature is calculated to be 5%; when the model is severely warped and the height H does not reach 20 mm due to printing failure, it is calculated according to the actual printable height. For example, if the target part (printed part) is 150 mm long and 10 mm high, and the average warping height h of the four corners after cooling is 1 mm, the Warp curvature is calculated to be 10%.

[0104] Example 1

[0105] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0106] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0107] Polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyhexamethylene adipamide PA66 as the second crystalline polymer (fiber dispersed phase, melting point T m2 260℃)

[0108] In this embodiment, the amount of PLA and PA66 is such that the mass content of the second crystalline polymer PA66 in the composite material for 3D printing composed of the two is 20%. After PLA and PA66 are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and the strips are cooled and shaped in a normal temperature water tank, and the draft ratio is 5.2, so as to prepare a composite material for 3D printing.

[0109] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0110] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0111] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Figure 3 As shown, the fiber aspect ratio is about 10.2.

[0112] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0113] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Figure 4 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Figure 4 As shown, the warpage rate of the printed part tested was 5.2%, and the anti-warpage performance was poor.

[0114] At the same time, the printed parts were subjected to a Vicat heat resistance test using the GB / T 1633-2000 Vicat softening temperature (VST) of thermoplastics, the A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 108.3°C, and the heat resistance was average.

[0115] It can be seen from this that the PLA-based iMFC printing material provided in this embodiment cannot have both excellent printing anti-warping properties and print heat resistance.

[0116] Example 2

[0117] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0118] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0119] Polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyhexamethylene adipamide PA66 as the second crystalline polymer (fiber dispersed phase, melting point T m2 260℃)

[0120] In this embodiment, the amount of PLA and PA66 is such that the mass content of the second crystalline polymer PA66 in the composite material for 3D printing composed of the two is 20%. After PLA and PA66 are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and the strips are cooled and shaped in a normal temperature water tank, and the draft ratio is 20.3, so as to prepare a composite material for 3D printing.

[0121] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0122] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0123] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Figure 5 As shown, the fiber aspect ratio is about 20.5.

[0124] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0125] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Figure 6 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Figure 6 As shown, the warpage rate of the printed part tested was 4.3%, and the warpage resistance of the printed part was average.

[0126] At the same time, the printed parts were subjected to a Vicat heat resistance test using the GB / T 1633-2000 Vicat softening temperature (VST) of thermoplastics, the A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 112.2°C, and the heat resistance performance was acceptable.

[0127] It can be seen from this that the PLA-based iMFC printing material provided in this embodiment cannot have both excellent printing anti-warping properties and print heat resistance.

[0128] Example 3

[0129] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0130] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0131] Polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyhexamethylene adipamide PA66 as the second crystalline polymer (fiber dispersed phase, melting point T m2 260℃)

[0132] In this embodiment, the amount of PLA and PA66 is such that the mass content of the second crystalline polymer PA66 in the composite material for 3D printing composed of the two is 20%. After PLA and PA66 are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and the strips are cooled and shaped in a normal temperature water tank, and the draft ratio is 30.6, so as to prepare a composite material for 3D printing.

[0133] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0134] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0135] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Figure 7 As shown, the fiber aspect ratio is about 42.5.

[0136] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0137] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Figure 8 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Figure 8 As shown, the warpage rate of the printed part tested was 1.6%, and the warpage resistance was good.

[0138] At the same time, the printed parts were subjected to a Vicat heat resistance test using the GB / T 1633-2000 Vicat softening temperature (VST) of thermoplastics, the A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 124.3°C, indicating good heat resistance.

[0139] It can be seen that the PLA-based iMFC printing material provided in this embodiment has both good printing anti-warping properties and heat resistance of printed parts.

[0140] Example 4

[0141] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0142] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0143] Polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyhexamethylene adipamide PA66 as the second crystalline polymer (fiber dispersed phase, melting point T m2 260℃)

[0144] In this embodiment, the amount of PLA and PA66 is such that the mass content of the second crystalline polymer PA66 in the composite material for 3D printing composed of the two is 20%. After PLA and PA66 are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and the strips are cooled and shaped in a normal temperature water tank, and the draft ratio is 40.4, so as to prepare a composite material for 3D printing.

[0145] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0146] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0147] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Fig. 9 As shown, the fiber aspect ratio is about 67.8.

[0148] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0149] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Fig.10The printed part (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Fig.10 As shown, the printed part test showed a warpage rate of 0.8%, which has excellent warpage resistance.

[0150] At the same time, the printed parts were subjected to a Vicat heat resistance test using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 130.0°C, indicating good heat resistance.

[0151] It can be seen that the PLA-based iMFC printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0152] Example 5

[0153] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0154] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0155] With polylactic acid PLA as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyhexamethylene adipamide PA66 as the second crystalline polymer (fiber dispersed phase, melting point T m2 is 260°C);

[0156] In this embodiment, the amount of PLA and PA66 is such that the mass content of the second crystalline polymer PA66 in the composite material for 3D printing composed of the two is 20%. After PLA and PA66 are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and the strips are cooled and shaped in a normal temperature water tank, and the draft ratio is 60.9, so as to prepare a composite material for 3D printing.

[0157] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0158] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0159] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Fig.11 As shown, the fiber aspect ratio is about 98.6.

[0160] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0161] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Fig.12 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Fig.12 As shown, the printed part test showed a warpage rate of 0.64%, which has excellent warpage resistance.

[0162] At the same time, the printed parts were subjected to a Vicat heat resistance test using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 145.8°C, indicating excellent heat resistance.

[0163] It can be seen that the PLA-based iMFC printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0164] Example 6

[0165] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0166] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0167] Polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyethylene terephthalate PET as the second crystalline polymer (fiber dispersed phase, melting point T m2 is 245°C);

[0168] In this embodiment, the amount of PLA and PET is such that the mass content of the second crystalline polymer PET in the composite material for 3D printing composed of the two is 30%. After PLA and PET are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and the strips are cooled and shaped in a normal temperature water tank, and the draft ratio is 60.5, so as to prepare a composite material for 3D printing.

[0169] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0170] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0171] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Fig.13 As shown, the fiber aspect ratio is about 105.2.

[0172] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0173] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Fig.14 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Fig.14 As shown, the printed part test showed a warpage rate of 0.72%, which has excellent warpage resistance.

[0174] At the same time, the printed parts were subjected to a Vicat heat resistance test using GB / T 1633-2000 Thermoplastic Vicat Softening Temperature (VST) determination, A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 163.4°C, indicating excellent heat resistance.

[0175] It can be seen that the PLA-based iMFC printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0176] Example 7

[0177] This embodiment provides an FFF printing method, which specifically includes the following steps:

[0178] 1) Preparation of in-situ fiberized composite materials for 3D printing.

[0179] Polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyethylene terephthalate PET as the second crystalline polymer (fiber dispersed phase, melting point T m2 is 245°C).

[0180] In this embodiment, the amount of PLA and PET is such that the mass content of the second crystalline polymer PET in the composite material for 3D printing composed of the two is 20%. After PLA and PET are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strip is pulled, and it is cooled and shaped in a normal temperature water tank, and the draft ratio is 60.3, so as to prepare a composite material for 3D printing.

[0181] 2) Processing the prepared 3D printing composite material into 3D printing wire.

[0182] The specific operation is: single-screw extrusion molding of the above-mentioned composite material for 3D printing is carried out at a temperature of 160-240°C to prepare the 3D printing wire iMFC-Filament.

[0183] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Fig.15 As shown, the fiber aspect ratio is about 85.4.

[0184] 3) Perform FFF printing test on the 3D printing filament iMFC-Filament.

[0185] The prints obtained by FFF printing were subjected to anti-warping printing test at a temperature of 210°C. Fig.16 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Fig.16 As shown, the printed part test showed a warpage rate of 0.83%, which has excellent warpage resistance.

[0186] At the same time, the printed parts were subjected to a Vicat heat resistance test using GB / T 1633-2000 Thermoplastics Vicat Softening Temperature (VST) determination, A120 method, a force of 10N, and a heating rate of 120°C / h. The Vicat heat resistance temperature of the printed parts was measured to be 143.5°C, indicating excellent heat resistance.

[0187] It can be seen that the PLA-based iMFC printing material provided in this embodiment has both excellent printing anti-warping properties and heat resistance of printed parts.

[0188] Comparative Example 1

[0189] This comparative example uses the same PLA material as in Example 1 to prepare a 3D printing material.

[0190] PLA raw material particles were used to prepare PLA wires by single-screw extrusion molding. The single-screw in-and-out molding process used in this comparative example adopted the same process conditions as the single-screw in-and-out molding process in Example 1.

[0191] The PLA filament prepared in this comparative example was used to perform an FFF printing test, and the process conditions were consistent with the FFF printing test involved in Example 1. Fig.17 The finished product photo after printing is shown. Fig.17 The printed part shown (PLA-based iMFC printing material) is a rectangular parallelepiped with a length of L = 150 mm, a width of W = 9.6 mm, and a height of H = 20 mm. Fig.17As shown, the printed part has no warping as a whole, and the warping rate is 0.75% as tested. The printed part has excellent anti-warping properties.

[0192] At the same time, the printed part was subjected to a Vicat heat resistance test using the GB / T 1633-2000 thermoplastic Vicat softening temperature (VST) determination, the A120 method, a force of 10 N, and a heating rate of 120°C / h. The test showed that the Vicat heat resistance temperature of the printed part was 61.7°C, indicating that the heat resistance of the printed part prepared in this comparative example was relatively low.

[0193] It can be seen that compared with the composite materials for 3D printing prepared in Examples 1 to 7, the heat resistance of the PLA printing material provided in Comparative Example 1 is significantly poorer, and it is impossible for the printed parts prepared using it to have both excellent printing anti-warping and printed part heat resistance.

[0194] Comparative Example 2

[0195] This comparative example uses the same PLA material as in Example 1, and adds an organic hydrazide crystallization nucleating agent at 1% by weight relative to the polylactic acid material. The same twin-screw mixing process and single-screw extrusion wire processing process as in Example 1 are used to prepare a 3D printing material.

[0196] The PLA filament prepared in this comparative example was used to perform an FFF printing test, and the process conditions were consistent with the FFF printing test involved in Example 1. Fig.18 The finished product after printing is shown in the figure. Fig.18 As shown, the printed part has significant warping, and the warping rate is 17.3% as tested, which shows poor anti-warping property compared with Examples 1 to 7.

[0197] At the same time, the printed parts were subjected to a Vicat heat resistance test using GB / T 1633-2000 Thermoplastic Vicat Softening Temperature (VST) determination, A120 method, a force of 10N, and a heating rate of 120°C / h. The test showed that the Vicat heat resistance temperature of the printed parts was 145.3°C.

[0198] It can be seen that the PLA printing material provided in Comparative Example 2 cannot make the printed parts made using it have both excellent printing anti-warping properties and printed part heat resistance.

[0199] Comparative Example 3

[0200] In this comparative example, we used the in-situ fiber-forming composite material wire in Example 5 and changed the printing temperature in the FFF printing test to conduct a comparative test.

[0201] In this comparative example, the anti-warping printing test was carried out at a printing temperature of 280°C, and the results were Fig.19The printout shown is a rectangular parallelepiped with length L = 150 mm, width W = 9.6 mm, and height H = 20 mm. Fig.19 As shown, the warpage rate of the printed part tested was 11.4%.

[0202] The Vicat softening temperature (VST) of thermoplastics was determined according to GB / T 1633-2000, the A120 method was used, a force of 10N was used, and the heating rate was 120°C / h. The test showed that the Vicat heat resistance temperature of the printed part was 82.5°C.

[0203] Compared with Example 1, when the printing temperature is greater than the melting point of the PA66 fiber-forming phase, the micro-nanoscale fiber structure in the composite material for 3D printing is destroyed, resulting in a significant decrease in the warping resistance of the printed material and the heat resistance of the printed parts, further verifying the technical effect of the present specification.

[0204] In summary, compared with the composite materials for 3D printing prepared in Examples 1 to 7, the heat resistance and warping resistance of the PLA printing material provided in Comparative Example 3 are significantly poorer, and it is impossible for the printed parts prepared using it to have both excellent printing warping resistance and printed part heat resistance.

[0205] Comparative Example 4

[0206] This comparative example specifically comprises the following steps:

[0207] 1) Preparation of in-situ fiber-forming 3D printing materials.

[0208] As in Examples 1 to 5, polylactic acid PLA is used as the first crystalline polymer (continuous matrix phase, melting point T m1 170℃), with polyhexamethylene adipamide PA66 as the second crystalline polymer (fiber dispersed phase, melting point T m2 is 260℃).

[0209] In this embodiment, the amount of PLA and PA66 is sufficient, and in the 3D printing material composed of the two, the mass content of the second crystalline polymer PA66 is 20%. After PLA and PA66 are mixed in proportion, a twin-screw extrusion process is used for mixing, the processing temperature is 220-280°C, the extruded material strips are pulled, and cooled and shaped in a normal temperature water tank, and the draft ratio is 1.5, so as to prepare a composite material for 3D printing.

[0210] 2) Processing the prepared 3D printing material into 3D printing filament.

[0211] The specific operation is: single-screw extrusion molding is performed on the above-mentioned 3D printing material at a temperature of 160-240°C to prepare the 3D printing wire.

[0212] The fiber structure of the cross section of the obtained 3D printing wire iMFC-Filament was observed under a microscope. The micro-nanoscale fiber structure is as follows Fig. 20 As shown in the figure, PA66 did not achieve fiberization and the fiberization effect was poor.

[0213] In this comparative example, the anti-warping printing test was carried out at a printing temperature of 210°C, and the results were Fig.21 The printout shown is a rectangular parallelepiped with length L = 150 mm, width W = 9.6 mm, and height H = 20 mm. Fig.21 As shown, the warpage rate of the printed part tested was 18.2%.

[0214] The Vicat softening temperature (VST) of thermoplastics was determined according to GB / T 1633-2000, the A120 method was used, a force of 10N was used, and a heating rate of 120°C / h. The test showed that the Vicat heat resistance temperature of the printed part was 75.8°C.

[0215] Compared with Examples 1 to 7, when the fiber aspect ratio is relatively low, the warping resistance of the printed material and the heat resistance of the printed parts are significantly reduced, which further verifies the technical effect of the present specification.

[0216] In summary, compared with the composite materials for 3D printing prepared in Examples 1 to 7, the heat resistance and warping resistance of the PLA printing material provided in Comparative Example 4 are significantly poorer, and it is impossible for the printed parts prepared using it to have both excellent printing warping resistance and printed part heat resistance.

[0217] In summary, after reading this detailed disclosure, it will be apparent to those skilled in the art that the foregoing detailed disclosure may be presented only by way of example and may not be limiting. Although not explicitly stated herein, it will be appreciated by those skilled in the art that this specification is intended to encompass various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be proposed by this specification and are within the spirit and scope of the exemplary embodiments of this specification.

[0218] The above is a description of a specific embodiment of the specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0219] In addition, 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 conjunction with the embodiment may be included in at least one embodiment of this specification. Therefore, it can be emphasized and should be understood that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics may be appropriately combined in one or more embodiments of this specification.

[0220] It should be understood that in the foregoing description of the embodiments of this specification, in order to help understand a feature and for the purpose of simplifying this specification, this specification sometimes combines various features in a single embodiment, drawing or its description. Alternatively, this specification also disperses various features in 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 those 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 is also true when the content of each secondary embodiment is less than all the features of a single aforementioned disclosed embodiment.

Claims

1. A composite material for 3D printing, characterized in that: include: A continuous matrix phase, which is a first crystalline polymer; as well as A fiber dispersed phase, which is a second crystalline polymer, includes a micro-nanoscale fiber structure and is continuously distributed in the continuous matrix phase; The second crystalline polymer has a melting point higher than a melting point of the first crystalline polymer.

2. The composite material for 3D printing according to claim 1, characterized in that: The melting point of the second crystalline polymer is higher than the melting point of the first crystalline polymer by 20° C. or more.

3. The composite material for 3D printing according to claim 1, characterized in that: The difference between the melting point of the second crystalline polymer and the melting point of the first crystalline polymer is not less than 50°C.

4. The composite material for 3D printing according to claim 1, characterized in that: The mass percentage of the fiber structure in the composite material for 3D printing is 3% to 40%.

5. The composite material for 3D printing according to claim 1, characterized in that: The fiber structure has a diameter of 0.1 to 50 μm, and the fiber structure includes fibers with an aspect ratio greater than 10.

6. The composite material for 3D printing according to claim 5, characterized in that: The fiber dispersed phase includes fibers with an aspect ratio of not less than 30.

7. The composite material for 3D printing according to claim 6, characterized in that: The fiber structure includes fibers with an aspect ratio of not less than 50.

8. The composite material for 3D printing according to any one of claims 1 to 7, characterized in that: The first crystalline polymer is polylactic acid.

9. The composite material for 3D printing according to any one of claims 1 to 7, characterized in that: The second crystalline polymer includes at least one of a crystalline polyester material, a crystalline polyamide material, a crystalline polyether material, a crystalline polyolefin material, and a crystalline fluoropolymer.

10. The composite material for 3D printing according to claim 9, characterized in that: The second crystalline polymer includes at least one of polyethylene terephthalate, polybutylene terephthalate, polycaprolactam, polyhexamethylene adipamide, polyphenylene sulfide, and polyhexamethylene terephthalamide.

11. A method for preparing a composite material for 3D printing according to any one of claims 1 to 10, characterized in that: It includes: heating the blend of the first crystalline polymer and the second crystalline polymer to a temperature above the melting point of the second crystalline polymer; The blend is physically stretched during the cooling and solidification process of the blend, so that the cooled second crystalline polymer forms the fiber dispersed phase in the first crystalline polymer.

12. The method for preparing a composite material for 3D printing according to claim 11, characterized in that: The fiber aspect ratio is controlled by adjusting the draw ratio during the extrusion process. The draw ratio is defined as the ratio of the cross-sectional area of ​​the extruded material outlet die to the cross-sectional area after cooling and shaping. The larger the draw ratio, the larger the fiber aspect ratio. The preferred draw ratio is >2, the more preferred draw ratio is >20, and the more preferred draw ratio is >50.

13. A 3D printing wire, characterized in that: The 3D printing wire is prepared from the composite material for 3D printing according to any one of claims 1 to 10.

14. A method for preparing a 3D printing wire, characterized in that: include: Extruding the composite material for 3D printing as claimed in any one of claims 10 to form a wire; The highest value of the extrusion temperature section is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer.

15. Use of the composite material for 3D printing according to any one of claims 1 to 10 or the 3D printing wire according to claim 13 in extrusion 3D printing technology.

16. The use according to claim 15, wherein a temperature lower than the melting point of the second crystalline polymer and higher than the melting point of the first crystalline polymer is used as the printing temperature for 3D printing.

17. A FFF printing method, characterized in that: It includes: FFF printing is performed using the 3D printing wire as described in claim 13, wherein the printing temperature is greater than the melting point of the first crystalline polymer and less than the melting point of the second crystalline polymer.

18. An FFF printed product, characterized in that: It is printed by the FFF printing method as claimed in claim 17.

19. The FFF printed product according to claim 18, characterized in that: The Vicat heat resistance temperature of the FFF printed product is greater than 100°C.

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