Thermosetting polyimide resin, workpiece, preparation method, forming method and application

Abstract

The invention relates to thermosetting polyimide resin, a workpiece, a preparation method, a forming method and application, belongs to the technical field of 3D printing and intelligent manufacturing, and solves the problems that high temperature resistance and high interlayer binding force of an existing polymer material printed workpiece are difficult to achieve at the same time, and engineering application is limited. The thermosetting polyimide resin is composed of active group terminated high molecular weight polyimide and active group terminated imide oligomer. After the prepared thermosetting polyimide wire is subjected to FDM forming and subsequent heating curing, a polyimide workpiece resistant to high temperature and high interlayer binding force can be obtained. According to the invention, both high temperature resistance and high interlayer binding force of a polymer material printed piece are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing and intelligent manufacturing, and in particular to a thermosetting polyimide resin for fused deposition modeling, and a preparation method and application thereof. Background Art

[0002] Fused Deposition Modeling (FDM) is an emerging manufacturing technology that uses a high-temperature nozzle to melt and extrude polymer filaments layer by layer to quickly prepare three-dimensional physical entities. Compared with 3D printing technologies such as selective laser sintering and digital light processing, it has the advantages of low printing equipment cost, simple process and convenient equipment maintenance, and is widely used in aerospace, medical, automotive and other fields. However, FDM polymers still face many difficulties and challenges in engineering applications. The most critical one is that the temperature resistance level and interlayer bonding strength of printed parts need to be improved, and most of them are used as conceptual models or functional parts. One of the main reasons for this situation is that most of the existing polymer material systems used for FDM molding are thermoplastic materials and the types are limited. High-performance polymers used for FDM molding, such as polyetherimide (PEI), semi-crystalline polyimide (PI), polyetheretherketone (PEEK), etc., have relatively high temperature resistance, but their melt fluidity is low and semi-crystalline PI and PEEK will crystallize during the printing process, which makes it difficult for polymer molecular chains to diffuse and entangle between layers, resulting in problems such as weak interlayer bonding strength of printed parts. To improve the above problems, low-temperature additives such as polycarbonate (PC) are usually added or a third component is introduced to destroy the regularity of the molecular chain to weaken the crystallinity, but this often sacrifices the heat resistance of the material. Polymer materials such as polyamide (PA), polylactic acid (PLA) and acrylonitrile-butadiene-styrene terpolymer (ABS) with excellent melt fluidity have a lower operating temperature, and the upper temperature limit is only 100-125°C.

[0003] As a special high-temperature resistant polymer material, thermosetting polyimide is widely used in aerospace and rail transportation. The physical and chemical properties of thermosetting polyimide make it possible to combine it with 3D printing technology to achieve the molding and preparation of printed parts with high heat resistance and high inter-layer bonding strength. Therefore, it is urgent to develop thermosetting polyimide resins for 3D printing fused deposition molding that have high melt fluidity, heat resistance and mechanical properties, so as to achieve a synergistic improvement in the heat resistance and mechanical properties of 3D printed parts by optimizing the intrinsic properties of polymer materials. Summary of the invention

[0004] In view of the above analysis, the present invention aims to provide a thermosetting polyimide resin, a product, a preparation method, a molding method and an application, so as to solve the problem that it is difficult to achieve both high temperature resistance and high-layer bonding strength in existing polymer material printed products, and the engineering application is limited.

[0005] The purpose of the present invention is mainly achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides a thermosetting polyimide resin, comprising a high molecular weight polyimide terminated with an active group and an imide oligomer terminated with an active group;

[0007] The number average molecular weight M of the high molecular weight polyimide terminated with the active group n The number average molecular weight M of the active group-terminated imide oligomer is 15000-35000 g / mol. n It is 1000-5000g / mol, and the mass ratio of the two is (80-60):(20-40).

[0008] Optionally, the active group-terminated high molecular weight polyimide has a structure of general formula I:

[0009]

[0010] The repeating unit Contains any of the following structures:

[0011]

[0012] The end-capping group R is selected from at least one of the following groups:

[0013]

[0014] Optionally, the active group-terminated imide oligomer has a structure of general formula II:

[0015]

[0016]

[0017] Wherein, Ar' is selected from at least one of the following groups:

[0018]

[0019] R 2 At least one selected from the following groups:

[0020]

[0021] R 3 At least one selected from the following groups:

[0022]

[0023] The end-capping group R' is selected from at least one of the following groups:

[0024]

[0025] In a second aspect, the present invention provides a method for preparing a thermosetting polyimide resin, which is used to prepare the above-mentioned thermosetting polyimide resin, comprising the following steps:

[0026] Step 1: preparing a high molecular weight polyimide solution terminated with an active group and an imide oligomer solution terminated with an active group respectively;

[0027] Step 2: mixing the high molecular weight polyimide solution and the imide oligomer solution obtained in step 1 in proportion to obtain a thermosetting polyimide resin solution;

[0028] Step 3: Post-treating the thermosetting polyimide resin solution obtained in step 2 to obtain polyimide resin powder.

[0029] Optionally, in step 1, preparing the high molecular weight polyimide solution terminated with active groups comprises: synthesizing a high molecular weight polyamic acid solution terminated with active groups, and obtaining the high molecular weight polyimide solution terminated with active groups by imidization;

[0030] The method for preparing the active group-terminated imide oligomer solution comprises: synthesizing the active group-terminated amic acid oligomer solution, and obtaining the active group-terminated imide oligomer solution through imidization.

[0031] In a third aspect, the present invention provides a method for molding a thermosetting polyimide product, comprising the following steps:

[0032] Step a: Melting and extruding the thermosetting polyimide resin to obtain a printing filament;

[0033] Step b: melt-deposition printing the filament in step a into a self-supporting printed strip;

[0034] Step c: heating the printed sample strip to solidify it, and cooling it to obtain a thermosetting polyimide product.

[0035] Optionally, in step a, the temperature of zone I of the twin-screw extruder is 245-270°C, the temperature of zone II is 255-280°C, and the temperature of zone III is in the range of 265-290°C.

[0036] Optionally, in step b, the printing temperature is 350-420°C, the base plate temperature is 150-170°C, the chamber temperature is 80-100°C, and the printing speed is 30-60 mm / min.

[0037] In a fourth aspect, the present invention provides a thermosetting polyimide part prepared by the above-mentioned molding method, wherein the room temperature tensile strength of the thermosetting polyimide part in the X-axis direction is ≥90MPa, the room temperature tensile strength in the Z-axis direction is ≥70MPa, the glass transition temperature Tg is ≥270°C, and the part has high heat resistance, high mechanical properties and high inter-layer bonding strength.

[0038] In a fifth aspect, the present invention provides an application of the above-mentioned thermosetting polyimide resin, wherein the thermosetting polyimide resin is applied to 3D printing fused deposition modeling to rapidly mold high-performance complex components.

[0039] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0040] (1) The thermosetting polyimide resin for FDM molding provided by the present invention is a compound system composed of a high molecular weight polyimide terminated with an active group and an imide oligomer terminated with an active group. The high molecular weight polyimide terminated with an active group provides strength and modulus for the compound system, ensuring that the wire material can be smoothly extruded and rolled up and withstand the meshing force of the gears when the FDM printer feeds the wire. The imide oligomer terminated with an active group can significantly reduce the melt viscosity of the compound system, increase the gap between the melt extrusion temperature and the crosslinking temperature, and ensure that basically no crosslinking reaction occurs during the extrusion process. At the same time, the low melt viscosity is also conducive to the diffusion and entanglement of molecular chains between layers during the printing process, increasing the area of ​​the interlayer bonding area, and thus increasing the interlayer bonding strength. The high active end group content of the imide oligomer (the mass content of the end group is 9.93-49.6wt%) also lays a foundation for the construction of interlayer chemical crosslinking points during the curing process. The invention develops a thermosetting polyimide resin dedicated to FDM by synergistically regulating the chemical structure, molecular weight, end-capping group type and blending ratio of a high molecular weight polyimide and an imide oligomer end-capped with an active group.

[0041] (2) Existing fused deposition modeling uses thermoplastic polymer filaments as raw materials, and a printed part is obtained by one-step molding. During the molding process, only physical changes occur, and no chemical changes occur. The heat resistance of the molded part depends entirely on the heat resistance of the material itself. In order to meet the requirements of the FDM molding process, the polymer material must have excellent melt fluidity. Due to the mutual constraints between the melt fluidity and heat resistance of the polymer material, the heat resistance of this type of polymer material for FDM is generally low, and it is difficult to meet the application requirements of high-temperature environments in the industrial field. The present invention is based on a thermosetting polyimide composite material system and proposes a two-step molding strategy, namely a printing process and a thermal curing process. During the FDM molding process, the thermosetting polyimide resin melts (physical change), accompanied by a cross-linking reaction (chemical change) of a small amount of end-capping groups (molar percentage of 0.5%-10%), forming a printed part with support. In the subsequent temperature-raising thermal curing process, the end-capping groups of the thermosetting polyimide are completely cross-linked (chemical change) to obtain the final part. Therefore, the thermosetting polyimide resin provided by the present invention has excellent heat resistance and mechanical properties after melt deposition molding, which is specifically manifested as: the glass transition temperature of the printed part is ≥270°C, and the mechanical strength of the printed part in different directions is higher than 70MPa.

[0042] (3) The present invention realizes the combination of thermosetting polyimide resin and FDM molding process, which not only expands the types of polymer materials suitable for FDM molding, but also explores new rapid molding technology of thermosetting polyimide resin, and realizes the rapid molding preparation of complex components for high-temperature environment application in the industrial field.

[0043] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be obvious from the description or understood by practicing the present invention.

[0044] The methods in the present invention are conventional methods unless otherwise specified. The raw materials can be obtained from commercial public channels or homemade in the laboratory unless otherwise specified. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] The drawings are only for the purpose of illustrating specific embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0046] Figure 1 The room temperature mechanical properties of the thermosetting polyimide Z-direction 3D printed tensile specimens prepared in Example 9. DETAILED DESCRIPTION

[0047] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0048] The molecular weight of thermosetting polyimide resin is a key factor affecting the physical and chemical properties of resin. High molecular weight polyimide terminated with active groups has excellent mechanical properties. Imide oligomer terminated with active groups has a molecular weight far lower than that of high molecular weight polyimide terminated with active groups, and thus exhibits excellent melt fluidity. The present invention combines the two, and prepares a thermosetting polyimide resin suitable for fused deposition molding by regulating the chemical structure, end-capping group type, molecular weight and blending of the two. During fused deposition molding, the thermosetting polyimide resin exhibits low melt viscosity and is easy to diffuse and entangle the molecular chains. With the increase of the curing crosslinking degree, the three-dimensional network structure of the resin is gradually formed, and the heat resistance and mechanical properties of the resin are simultaneously improved. Therefore, through the two-step reaction molding process of FDM molding-thermal curing, the molding of the initial self-supporting printed parts and the final cured parts can be realized in turn. The present invention explores the technical method of combining thermosetting polyimide resin and FDM molding, realizes the rapid manufacturing of complex-shaped parts of polyimide materials and improves the temperature resistance level of FDM molded polymer parts.

[0049] In a first aspect, the present invention provides a thermosetting polyimide resin for fused deposition modeling, wherein the thermosetting polyimide resin comprises a high molecular weight polyimide terminated with an active group and an imide oligomer terminated with an active group. The high molecular weight polyimide terminated with an active group has a design number average molecular weight M n The design number average molecular weight of the active group-terminated imide oligomer is 15000-35000 g / mol. n It is 1000-5000 g / mol, and the mass ratio of the two is (80-60):(20-40), for example, 80:20, 70:30, 60:40.

[0050] Specifically, the active group-terminated high molecular weight polyimide has a structure of general formula I:

[0051]

[0052] Among them, the repeating unit It includes any one of the following combinations: bisphenol A diether dianhydride / m-phenylenediamine (BPADA / m-PDA), bisphenol A diether dianhydride / 3,5-diaminotrifluorotoluene (BPADA / 3FMDA), bisphenol AF dianhydride / m-phenylenediamine (BPAFDA / m-PDA), 4,4'-(hexafluoroisopropylidene) diphthalic anhydride / 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (6FDA / HFBAPP), 3,3',4,4'-diphenyl ether tetracarboxylic anhydride / 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (ODPA / 6FAPB) and 3,3',4,4'-diphenyl ether tetracarboxylic anhydride / 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (ODPA / HFBAPP), and the specific structure is shown below:

[0053]

[0054] Specifically, the end-capping group R is selected from at least one of the following groups:

[0055]

[0056] The active group-terminated imide oligomer has the structure of general formula II:

[0057]

[0058] Wherein, Ar' is selected from at least one of the following groups:

[0059]

[0060] R 2 At least one selected from the following groups:

[0061]

[0062] R 3 At least one selected from the following groups:

[0063]

[0064] The end-capping group R' is selected from at least one of the following groups:

[0065]

[0066] The ratio of x to y in the structural formula of the active group-terminated imide oligomer is (10-40):(90-60).

[0067] In a second aspect, the present invention further provides a method for preparing a thermosetting polyimide resin, which is used to prepare the above-mentioned thermosetting polyimide resin, comprising the following steps:

[0068] Step 1: preparing a high molecular weight polyimide solution terminated with an active group and an imide oligomer solution terminated with an active group respectively;

[0069] Step 2: Mix the high molecular weight polyimide solution and the imide oligomer solution obtained in step 1 in proportion, and stir at room temperature to obtain a thermosetting polyimide resin solution;

[0070] Step 3: Add a precipitation agent to the thermosetting polyimide resin solution obtained in step 2, and perform post-treatment to obtain a polyimide resin powder.

[0071] Specifically, in step 1, preparing a high molecular weight polyimide solution terminated with active groups includes: synthesizing a high molecular weight polyamic acid solution terminated with active groups, and obtaining a high molecular weight polyimide solution terminated with active groups by imidization. Specifically, the steps include:

[0072] Step i: dissolving a diamine in an organic solvent to obtain a homogeneous solution;

[0073] Step ii: adding dianhydride to the homogeneous solution of step i, adding an organic solvent, stirring at 180-220 r / min for 8-16 hours at room temperature, adding a reactive end-capping agent and an organic solvent, and continuing to stir at 180-220 r / min for 8-16 hours to obtain a polyamic acid solution;

[0074] Step iii: adding a dehydrating agent and a catalyst to the polyamic acid solution of step ii, stirring at 180-220 r / min for 8-16 hours to obtain a high molecular weight polyimide solution terminated with active groups.

[0075] Specifically, in step i, the diamine includes at least one of m-phenylenediamine (m-PDA), 3,5-diaminotrifluorotoluene (3FMDA), 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP), and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB).

[0076] The organic solvent is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF).

[0077] In step ii, the dianhydride includes at least one of bisphenol A diether dianhydride (BPADA), bisphenol AF dianhydride (BPAFDA), 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA).

[0078] In step ii, the solid content of the polyamic acid solution is 20wt.%-30wt.%, for example, 20wt.%, 22wt.%, 24wt.%, 25wt.%, 27wt.%, 29wt.%, 30wt.%.

[0079] In step ii, the stirring speed is 180-220 r / min, for example, 180 r / min, 190 r / min, 200 r / min, 210 r / min, 220 r / min. The stirring reaction time is 8-16 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours.

[0080] It should be noted that the organic solvent in steps i and ii is not added all at once, but is added in batches. The proportion of the organic solvent used when adding diamine, dianhydride and end-capping agent is: (75-85wt%): (5-15wt%): (5-15wt%), and the sum of the three is 100wt%. The purpose of adding in batches is to wash away the reaction monomers adhering to the wall to ensure the feed ratio.

[0081] In step iii, the catalyst is at least one of pyridine, picoline, isoquinoline, quinoline or triethylamine; and the dehydrating agent is at least one of acetic anhydride, propionic anhydride, benzoic anhydride and trifluoroacetic anhydride.

[0082] In step ii, the reactive end-capping agent includes at least one of 4-phenylethynylcarbonylphthalic anhydride, 4-(3-trifluoromethyl-1-phenylethynyl)phthalic anhydride, 4-phenylethynylphthalic anhydride (PEPA), and 4-phenylethynylphenoxyphthalic anhydride.

[0083] The reaction system for preparing the active group-terminated high molecular weight polyimide solution must satisfy the following molar ratio balance condition: 2 times the molar amount of aromatic dianhydride plus the molar amount of reactive end-capping agent is equal to 2 times the molar amount of aromatic diamine, so as to ensure the stoichiometric balance between the reactants and realize the smooth reaction.

[0084] Specifically, in step 1, preparing the active group-terminated imide oligomer solution comprises: synthesizing an active group-terminated amic acid oligomer solution, and obtaining the active group-terminated imide oligomer solution by imidization. Specifically, the steps include:

[0085] Step I: dissolving a rigid aromatic diamine and a flexible aromatic diamine in an organic solvent to obtain a homogeneous solution;

[0086] Step II: Add aromatic dianhydride to the homogeneous solution of step I, stir at 180-220 r / min at room temperature until it becomes clear, add a reactive end-capping agent and an organic solvent, continue stirring and reacting for 8-16 hours to obtain an amic acid oligomer solution;

[0087] Step III: Add a dehydrating agent and a catalyst to the amic acid oligomer solution of step II, and stir at 180-220 r / min for 8-16 hours to obtain an imide oligomer solution terminated with an active group.

[0088] Specifically, in step I, the rigid aromatic diamine includes at least one of p-phenylenediamine (p-PDA), 2,6-dimethylbenzene-1,4-diamine, 2,2'-dimethyl-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB). The flexible aromatic diamine includes at least one of 3,4'-diaminodiphenyl ether (3,4'-ODA), 3,3'-diaminodiphenyl ether (3,3'-ODA), 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 1,3-bis(3'-aminophenoxy)benzene (1,3,3'-APB), 4,4-bis(3'-aminophenoxy)biphenyl (m-BAPB), and 3,3'-diaminodiphenyl sulfide (3,3'-SDA).

[0089] The organic solvent is selected from at least one of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc) and N,N-dimethylformamide (DMF).

[0090] In step II, the aromatic dianhydride includes at least one of 2,3,3',4'-benzophenone tetracarboxylic dianhydride (a-BTDA), 2,3,3',4'-biphenyl tetracarboxylic dianhydride (a-BPDA), 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (a-ODPA), 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA), 3,3',4,4'-biphenyl tetracarboxylic dianhydride (BPDA), and 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA).

[0091] Reactive end-capping agents include 4-phenylethynylcarbonylphthalic anhydride, 4-(3-trifluoromethyl-1-phenylethynyl)phthalic anhydride, 4-phenylethynylphthalic anhydride (PEPA), and 4-phenylethynylphenoxyphthalic anhydride.

[0092] In step II, the stirring speed of the reaction is 180-220 r / min, for example, 180 r / min, 190 r / min, 200 r / min, 210 r / min, 220 r / min. The reaction time is 8-16 hours, for example, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours.

[0093] In step II, the solid content of the amic acid oligomer solution is 20 wt.%-30 wt.%, for example, 20 wt.%, 22 wt.%, 24 wt.%, 25 wt.%, 27 wt.%, 29 wt.%, 30 wt.%.

[0094] In steps I and II, the organic solvent is not added all at once, but is added in batches. The ratio of the organic solvent used when adding diamine, dianhydride and end-capping agent is: (75-85wt%): (5-15wt%): (5-15wt%), and the sum of the three is 100wt%. The purpose of adding in batches is to wash away the reaction monomers adhering to the wall to ensure the feed ratio.

[0095] In step III, the catalyst is at least one of pyridine, picoline, isoquinoline, quinoline or triethylamine; and the dehydrating agent is at least one of acetic anhydride, propionic anhydride, benzoic anhydride and trifluoroacetic anhydride.

[0096] The reaction system for preparing the active group-terminated imide oligomer solution must satisfy the following molar ratio balance condition: 2 times the molar amount of aromatic dianhydride plus the molar amount of reactive end-capping agent is equal to 2 times the molar amount of rigid aromatic diamine plus 2 times the molar amount of flexible aromatic diamine, so as to ensure the stoichiometric balance between the reactants and achieve smooth reaction. At the same time, in order to control the heat resistance and processing properties of the product, the molar ratio of rigid aromatic diamine to flexible aromatic diamine should be in the range of (10-40): (90-60).

[0097] It should be noted that the introduction of flexible aromatic diamine structure can improve the melt fluidity of imide oligomers, enhance the interlayer fusion of thermosetting polyimide resins during fused deposition molding, make printed parts denser and reduce porosity.

[0098] Specifically, in step 2, the stirring speed is 180-220 r / min, for example, 180 r / min, 190 r / min, 200 r / min, 210 r / min, 220 r / min. The stirring time is 2-4 hours, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours.

[0099] In step 3, the precipitation agent is ethanol, and the mass ratio of the addition amount of the precipitation agent to the solution is 1:(0.95-1.05).

[0100] Specifically, in step 3, the post-treatment includes filtering, washing with ethanol three times, and drying to obtain thermosetting polyimide resin powder. The drying includes first drying at 110-130° C. for 3-5 hours, and then drying at 190-210° C. for 10-14 hours.

[0101] In a third aspect, the present invention provides a method for molding a thermosetting polyimide product, comprising the following steps:

[0102] Step a: melt-extrude the thermosetting polyimide resin through a twin-screw extruder to obtain a printing filament;

[0103] Step b: using a 3D printer to melt-deposit the filament in step a into a self-supporting printed strip;

[0104] Step c: gradually heating the printed sample from room temperature to achieve dimensional curing, and naturally cooling it to room temperature to obtain a thermosetting polyimide product.

[0105] Specifically, in step a, the temperature range of zone I of the twin-screw extruder is 245-270°C, for example, 245°C, 250°C, 255°C, 260°C, 265°C, 270°C.

[0106] The temperature range of Zone II is 255-280°C, for example, 255°C, 260°C, 265°C, 270°C, 275°C, 280°C.

[0107] The temperature range of Zone III is 265-290°C, for example, 265°C, 270°C, 275°C, 280°C, 285°C, 290°C.

[0108] The rotation speed of the feeding zone is 20-30 rpm / min, for example, 20 rpm / min, 25 rpm / min, 30 rpm / min.

[0109] The spindle speed is 20-40 rpm / min, for example, 20 rpm / min, 25 rpm / min, 30 rpm / min, 35 rpm / min, 40 rpm / min.

[0110] Specifically, in step b, during the FDM molding process, the thermosetting polyimide resin undergoes a cross-linking reaction of some end-capping groups to obtain a self-supporting printed strip. The specific process parameters are as follows:

[0111] The printing temperature is 350-420°C, for example, 350°C, 370°C, 390°C, 420°C;

[0112] Printing speed is 30-60mm / min; for example, 30mm / min, 40mm / min, 50mm / min, 60mm / min;

[0113] The chamber temperature is 80-100° C., for example, 80° C., 90° C., 100° C. The bottom plate temperature is 150-170° C., for example, 150° C., 160° C., 170° C. The single layer thickness is 0.1-0.3 mm, for example, 0.1 mm, 0.2 mm, 0.3 mm.

[0114] In step c, the heating temperature is 375-385°C, for example, 375°C, 378°C, 380°C, 382°C, 385°C.

[0115] It should be noted that the heating process in step c is a gradient heating process, that is, in the process of heating from room temperature to 375-385°C, a constant temperature step is set at one or several temperatures. For example, the temperature of the constant temperature step is set to one or several of 250°C, 270°C, 290°C, 300°C, 320°C, 340°C, 360°C and 380°C.

[0116] The constant temperature time of each constant temperature step is 1-12h, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h.

[0117] The present invention can realize the dimensional curing of the thermosetting polyimide printed part by using gradient temperature increase in step c. Under high temperature conditions, the end-capping groups are completely cross-linked to obtain the final product.

[0118] It should be noted that the role of dimensional curing after 3D printing is to make the printed splines completely cross-linked, so that the printed splines show high heat resistance, high mechanical properties and high-layer bonding strength.

[0119] In a fourth aspect, the present invention provides a thermosetting polyimide product obtained by melt deposition molding, which is prepared by the above molding method, and the thermosetting polyimide product has high heat resistance, high mechanical properties and high inter-layer bonding strength. Specifically, the room temperature tensile strength of the thermosetting polyimide product in the X-axis direction is ≥90MPa, and the room temperature tensile strength in the Z-axis direction is ≥70MPa. Glass transition temperature T g ≥270℃.

[0120] In a fifth aspect, the present invention provides an application of a thermosetting polyimide resin, which is used in 3D printing fused deposition modeling to quickly form high-performance complex components, including honeycombs, gears, etc.

[0121] The present invention is described in detail below with reference to specific embodiments.

[0122] Example 1

[0123] Under nitrogen protection, 37.85g (0.35mol) of m-phenylenediamine (m-PDA) and 704.68g of N-methylpyrrolidone (NMP) were added to a reaction vessel equipped with mechanical stirring, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then 176.84g (0.34mol) of bisphenol A type diether dianhydride (BPADA) was added to the homogeneous solution of the diamine, and 88.09g of N-methylpyrrolidone (NMP) was added. After stirring and reacting for 8 hours at room temperature, 5.52g (0.02mol) of 4-phenylethynylphenoxyphthalic anhydride and 88.09g of N-methylpyrrolidone (NMP) were added to the solution, and the stirring and reacting was continued for 16 hours. 178.66g of acetic anhydride and 69.24g of pyridine were added to the above-mentioned polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0124] Under nitrogen protection, 6.76 g (0.06 mol) of p-phenylenediamine (p-PDA), 69.08 g (0.19 mol) of 4,4-bis(3'-aminophenoxy)biphenyl (m-BAPB) and 339.70 g of N-methylpyrrolidone (NMP) were added to a reaction vessel equipped with a mechanical stirrer, and stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 44.75 g (0.14 mol) of 2,3,3',4'-benzophenone tetracarboxylic dianhydride (a-BTDA) was added to the homogeneous solution of diamine, and 42.46 g of N-methylpyrrolidone (NMP) was added. After stirring at room temperature until clear, 61.39 g (0.22 mol) of 4-phenylethynylphenoxyphthalic anhydride and 42.46 g of N-methylpyrrolidone (NMP) were added to the solution, and the stirring reaction was continued for 10 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0125] The two solutions prepared above were blended in a mass ratio of 70:30 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0126] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 255℃, the temperature of the zone II is 265℃, the temperature of the zone III is 275℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 370℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0127] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 4h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 380°C / 1h, and then the temperature was lowered to obtain the final product. Its main properties are shown in Table 1.

[0128] Example 2

[0129] Under nitrogen protection, 37.85 g (0.42 mol) of m-phenylenediamine (m-PDA) and 847.97 g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 176.84 g (0.41 mol) of bisphenol A diether dianhydride (BPADA) was added to the homogeneous solution of the diamine, and 106.00 g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 6.32 g (0.02 mol) of 4-(3-trifluoromethyl-1-phenylethynyl)phthalic anhydride and 106.00 g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 16 hours. 214.39 g of acetic anhydride and 83.09 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0130] Under nitrogen protection, 30.04 g (0.15 mol) of 3,4'-diaminodiphenyl ether (3,4'-ODA), 13.62 g (0.10 mol) of 2,6-dimethylbenzene-1,4-diamine and 308.06 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 38.16 g (0.12 mol) of 2,3,3',4'-benzophenonetetracarboxylic dianhydride (a-BTDA) was added to the homogeneous solution of diamine, and 38.51 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 83.22 g (0.26 mol) of 4-(3-trifluoromethyl-1-phenylethynyl)phthalic anhydride and 38.51 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 10 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0131] The two solutions prepared above were blended in a mass ratio of 60:40 between high molecular weight polyimide capped with active groups and imide oligomer. After stirring at room temperature for 4 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0132] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 245℃, the temperature of the zone II is 255℃, the temperature of the zone III is 265℃, the speed of the feeding zone is 30rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 350℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 40mm / min.

[0133] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 4h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 380°C / 1h, and then the temperature was lowered to obtain the final product. Its main properties are shown in Table 1.

[0134] Example 3

[0135] Under nitrogen protection, 81.02 g (0.46 mol) of 3,5-diaminotrifluorotoluene (3FMDA) and 1024.13 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 234.05 g (0.45 mol) of bisphenol A diether dianhydride (BPADA) was added to the homogeneous solution of the diamine, and 128.02 g of N,N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 128.02 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 234.80 g of acetic anhydride and 91.00 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0136] Under nitrogen protection, 35.04 g (0.18 mol) of 3,3'-diaminodiphenyl ether (3,3'-ODA), 15.92 g (0.08 mol) of 2,2'-dimethyl-4,4'-diaminobiphenyl and 266.90 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 59.36 g (0.18 mol) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was added to the homogeneous solution of diamine, and 33.36 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 39.72 g (0.16 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 32.66 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0137] The two solutions prepared above were blended in a mass ratio of 70:30 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0138] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 265℃, the temperature of the zone II is 275℃, the temperature of the zone III is 285℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 30rpm / min. The printing parameters are as follows: the printer nozzle temperature is 370℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 30mm / min.

[0139] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 4h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 380°C / 1h, and then the temperature was lowered to obtain the final product. Its main properties are shown in Table 1.

[0140] Example 4

[0141] Under nitrogen protection, 68.69 g (0.39 mol) of 3,5-diaminotrifluorotoluene (3FMDA) and 868.17 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then 197.64 g (0.38 mol) of bisphenol A diether dianhydride (BPADA) was added to the homogeneous solution of the diamine, and 108.52 g of N,N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 128.02 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 199.07 g of acetic anhydride and 77.15 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0142] Under nitrogen protection, 65.77 g (0.23 mol) of 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 8.01 g (0.03 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 297.13 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 71.61 g (0.22 mol) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was added to the homogeneous solution of diamine, and 37.14 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 13.79 g (0.06 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 37.14 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 10 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0143] The two solutions prepared above were blended in a mass ratio of 65:35 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 3 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0144] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 260℃, the temperature of the zone II is 270℃, the temperature of the zone III is 280℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 420℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0145] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 4h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 380°C / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0146] Example 5

[0147] Under nitrogen protection, 31.36g (0.29mol) of m-phenylenediamine (m-PDA) and 685.21g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with mechanical stirring, and the diamine was stirred until it was completely dissolved to obtain a homogeneous solution. Then 175.86g (0.28mol) of bisphenol AF dianhydride (BPAFDA) was added to the homogeneous solution of diamine, and 85.65g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 6.81g (0.02mol) of 4-phenylethynylphenoxyphthalic anhydride and 85.65g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 12 hours. 148.03g of acetic anhydride and 57.37g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0148] Under nitrogen protection, 73.69 g (0.20 mol) of 4,4-bis(3'-aminophenoxy)biphenyl (m-BAPB), 5.41 g (0.05 mol) of p-phenylenediamine (p-PDA) and 321.22 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 64.63 g (0.21 mol) of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (a-ODPA) was added to the homogeneous solution of diamine, and 40.15 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 28.36 g (0.08 mol) of 4-phenylethynylphenoxyphthalic anhydride and 40.15 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 12 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0149] The two solutions prepared above were blended in a mass ratio of 80:20 between high molecular weight polyimide capped with active groups and imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0150] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 270℃, the temperature of the zone II is 280℃, the temperature of the zone III is 290℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 390℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 50mm / min.

[0151] The thermosetting polyimide printed sample strip is placed in a high temperature oven for curing, and the curing process is 250℃ / 2h, 270℃ / 2h, 290℃ / 12h, 300℃ / 1h, 320℃ / 4h, 340℃ / 1h, 360℃ / 1h, 385℃ / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0152] Example 6

[0153] Under nitrogen protection, 52.99g (0.49mol) of m-phenylenediamine (m-PDA) and 1156.61g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with mechanical stirring, and the diamine was stirred until it was completely dissolved to obtain a homogeneous solution. Then 301.65g (0.48mol) of bisphenol AF dianhydride (BPAFDA) was added to the homogeneous solution of diamine, and 144.58g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 6.81g (0.02mol) of 4-phenylethynylphenoxyphthalic anhydride and 144.58g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 250.12g of acetic anhydride and 96.94g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0154] Under nitrogen protection, 48.67 g (0.23 mol) of 3,3'-diaminodiphenyl sulfide (3,3'-SDA), 3.40 g (0.03 mol) of 2,6-dimethylbenzene-1,4-diamine and 273.40 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 63.45 g (0.20 mol) of 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride (a-ODPA) was added to the homogeneous solution of diamine, and 34.18 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 40.84 g (0.12 mol) of 4-phenylethynylphenoxyphthalic anhydride and 34.18 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0155] The two solutions prepared above were blended in a mass ratio of 75:25 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 4 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0156] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 265℃, the temperature of the zone II is 275℃, the temperature of the zone III is 285℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 370℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed range is 45mm / min.

[0157] The thermosetting polyimide printed sample strip is placed in a high temperature oven for curing, and the curing process is 250℃ / 2h, 270℃ / 2h, 290℃ / 12h, 300℃ / 4h, 320℃ / 3h, 340℃ / 1h, 360℃ / 1h, 380℃ / 1h, and then the temperature is lowered to obtain the final product. Its main properties are shown in Table 1.

[0158] Example 7

[0159] Under nitrogen protection, 134.80 g (0.26 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) and 802.63 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 111.06 g (0.25 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) was added to the homogeneous solution of the diamine, and 100.33 g of N,N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 127.77 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 132.72 g of acetic anhydride and 51.44 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0160] Under nitrogen protection, 43.85 g (0.15 mol) of 1,3-bis(3'-aminophenoxy)benzene (1,3,3'-APB), 21.23 g (0.10 mol) of 2,2'-dimethyl-4,4'-diaminobiphenyl and 341.41 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 43.83 g (0.14 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of diamine, and 42.68 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 73.98 g (0.22 mol) of 4-phenylethynylphenoxyphthalic anhydride and 42.68 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0161] The two solutions prepared above were blended in a mass ratio of 65:35 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0162] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 260℃, the temperature of the zone II is 270℃, the temperature of the zone III is 280℃, the speed of the feeding zone is 30rpm / min, and the spindle speed is 30rpm / min. The printing parameters are as follows: the printer nozzle temperature is 350℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0163] The thermosetting polyimide printed sample strip is placed in a high temperature oven for curing, and the curing process is 250℃ / 2h, 270℃ / 2h, 290℃ / 12h, 300℃ / 4h, 320℃ / 6h, 340℃ / 1h, 360℃ / 1h, 380℃ / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0164] Example 8

[0165] Under nitrogen protection, 160.72 g (0.31 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) and 956.66 g of N,N-dimethylformamide (DMF) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then 133.27 g (0.30 mol) of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) was added to the homogeneous solution of the diamine, and 119.58 g of N,N-dimethylformamide (DMF) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 119.58 g of N,N-dimethylformamide (DMF) were added to the solution, and the stirring and reaction was continued for 8 hours. 132.72 g of acetic anhydride and 51.44 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0166] Under nitrogen protection, 35.04 g (0.18 mol) of 3,4'-diaminodiphenyl ether (3,4'-ODA), 24.02 g (0.08 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 370.26 g of N,N-dimethylformamide (DMF) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 28.85 g (0.08 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of diamine, and 46.28 g of N,N-dimethylformamide (DMF) was added. After stirring at room temperature until clear, 122.52 g (0.36 mol) of 4-phenylethynylphenoxyphthalic anhydride and 46.28 g of N,N-dimethylformamide (DMF) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0167] The two solutions prepared above were blended in a mass ratio of 70:30 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0168] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 265℃, the temperature of the zone II is 275℃, the temperature of the zone III is 285℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 350℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0169] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 8h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 381°C / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0170] Example 9

[0171] Under nitrogen protection, 184.18 g (0.43 mol) of 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6FAPB) and 1022.19 g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 130.29 g (0.42 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 127.77 g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 127.77 g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 219.49 g of acetic anhydride and 85.07 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0172] Under nitrogen protection, 54.81 g (0.19 mol) of 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 20.01 g (0.06 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 314.17 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 36.78 g (0.13 mol) of 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) was added to the homogeneous solution of diamine, and 40.52 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until it was clear, 59.98 g (0.24 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 40.52 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.36 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0173] The two solutions prepared above were blended in a mass ratio of 60:40 between high molecular weight polyimide capped with active groups and imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0174] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 255℃, the temperature of the zone II is 265℃, the temperature of the zone III is 275℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 390℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0175] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 4h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 380°C / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0176] Example 10

[0177] Under nitrogen protection, 154.20 g (0.36 mol) of 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6FAPB) and 856.67 g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 108.58 g (0.35 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 107.10 g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 107.10 g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 183.76 g of acetic anhydride and 71.22 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0178] Under nitrogen protection, 37.55 g (0.19 mol) of 3,3'-diaminodiphenyl ether (3,3'-ODA), 6.76 g (0.06 mol) of p-phenylenediamine (p-PDA) and 263.05 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 47.29 g (0.16 mol) of 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) was added to the homogeneous solution of diamine, and 32.88 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 49.33 g (0.18 mol) of 4-phenylethynylcarbonylphthalic anhydride and 32.88 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0179] The two solutions prepared above were blended in a mass ratio of 60:40 between high molecular weight polyimide capped with active groups and imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0180] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 255℃, the temperature of the zone II is 265℃, the temperature of the zone III is 275℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 350℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0181] The thermosetting polyimide printed sample strip is placed in a high temperature oven for curing, and the curing process is 250℃ / 2h, 270℃ / 2h, 290℃ / 12h, 300℃ / 4h, 320℃ / 4h, 340℃ / 1h, 360℃ / 1h, 377℃ / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0182] Embodiment 11

[0183] Under nitrogen protection, 197.01 g (0.38 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) and 1013.62 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 114.78 g (0.37 mol) of 3,3',4,4'-diphenylether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 126.70 g of N,N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 126.70 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 193.97 g of acetic anhydride and 75.18 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0184] Under nitrogen protection, 30.04 g (0.15 mol) of 3,3'-diaminodiphenyl ether (3,3'-ODA), 13.62 g (0.10 mol) of 2,6-dimethylbenzene-1,4-diamine and 242.39 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 55.17 g (0.19 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to the homogeneous solution of diamine, and 30.30 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 29.79 g (0.12 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 30.30 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0185] The two solutions prepared above were blended in a mass ratio of 70:30 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0186] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 265℃, the temperature of the zone II is 275℃, the temperature of the zone III is 285℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 350℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0187] The thermosetting polyimide printed sample strip is placed in a high temperature oven for curing, and the curing process is 250℃ / 2h, 270℃ / 2h, 290℃ / 12h, 300℃ / 4h, 320℃ / 4h, 340℃ / 1h, 360℃ / 1h, 375℃ / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0188] Example 12

[0189] Under nitrogen protection, 197.01 g (0.38 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) and 1013.62 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 114.78 g (0.37 mol) of 3,3',4,4'-diphenylether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 126.70 g of N,N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 126.70 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 193.97 g of acetic anhydride and 75.18 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0190] Under nitrogen protection, 58.47 g (0.20 mol) of 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 16.01 g (0.05 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 299.92 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 55.17 (0.19 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to the homogeneous solution of diamine, and 37.49 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until clear, 29.79 g (0.12 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 37.49 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.46 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0191] The two solutions prepared above were blended in a mass ratio of 80:20 between high molecular weight polyimide capped with active groups and imide oligomer. After stirring at room temperature for 4 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0192] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 270℃, the temperature of the zone II is 280℃, the temperature of the zone III is 290℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 350℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0193] The thermosetting polyimide printed sample strip is placed in a high temperature oven for curing, and the curing process is 250℃ / 2h, 270℃ / 2h, 290℃ / 12h, 300℃ / 4h, 320℃ / 4h, 340℃ / 1h, 360℃ / 1h, 378℃ / 1h, and then cooled to obtain the final product. Its main properties are shown in Table 1.

[0194] Comparative Example 1

[0195] Under nitrogen protection, 184.18 g (0.43 mol) of 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6FAPB) and 1022.19 g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 130.29 g (0.42 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 127.77 g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 127.77 g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 219.49 g of acetic anhydride and 85.07 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0196] Under nitrogen protection, 43.85 g (0.15 mol) of 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 16.01 g (0.05 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 259.33 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 29.42 g (0.10 mol) of 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA) was added to the homogeneous solution of diamine, and 32.42 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until it was clear, 49.65 g (0.20 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 32.42 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 102.09 g of acetic anhydride and 39.57 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0197] The two solutions prepared above were blended in a mass ratio of 50:50 between the high molecular weight polyimide containing active group end-capping and the imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0198] Thermosetting polyimide was melt extruded through a twin-screw extruder to prepare a wire with a diameter of 1.75±0.05 mm. The process parameters for wire preparation were as follows: the temperature of the twin-screw extruder zone I was 255°C, the temperature of the zone II was 265°C, the temperature of the zone III was 275°C, the speed of the feeding zone was 20rpm / min, and the speed of the main shaft was 40rpm / min. Its main properties are shown in Table 1.

[0199] Comparative Example 2

[0200] Under nitrogen protection, 43.85 g (0.15 mol) of 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 16.01 g (0.05 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 259.33 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 29.42g (0.10mol) of 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA) was added to the homogeneous solution of diamine, and 32.42g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until it was clear, 49.65g (0.20mol) of 4-phenylethynylphthalic anhydride (PEPA) and 32.42g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 102.09g of acetic anhydride and 39.57g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups. Ethanol was added to the reaction solution to precipitate the resin in a powder state. After filtering and washing, the thermosetting polyimide resin was obtained by drying in a blast oven. Its main properties are shown in Table 1.

[0201] Comparative Example 3

[0202] Under nitrogen protection, 184.18 g (0.43 mol) of 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6FAPB) and 1022.19 g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 130.29 g (0.42 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 127.77 g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 127.77 g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 219.49 g of acetic anhydride and 85.07 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end capping. Ethanol was added to the reaction solution to precipitate the resin in a powder state, which was filtered and washed, and then dried in a blast oven to obtain a thermosetting polyimide resin.

[0203] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 290℃, the temperature of the zone II is 300℃, the temperature of the zone III is 310℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 390℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0204] The thermosetting polyimide printed sample was placed in a high temperature oven for curing, and the curing process was 250°C / 2h, 270°C / 2h, 290°C / 12h, 300°C / 4h, 320°C / 4h, 340°C / 1h, 360°C / 1h, 380°C / 1h, and then the temperature was lowered to obtain the final product. Its main properties are shown in Table 1.

[0205] Comparative Example 4

[0206] Under nitrogen protection, 184.18 g (0.43 mol) of 1,4-bis (4-amino-2-trifluoromethylphenoxy) benzene (6FAPB) and 1022.19 g of N, N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 130.29 g (0.42 mol) of 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride (ODPA) was added to the homogeneous solution of the diamine, and 127.77 g of N, N-dimethylacetamide (DMAc) was added. After stirring and reacting at room temperature for 8 hours, 4.96 g (0.02 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 127.77 g of N, N-dimethylacetamide (DMAc) were added to the solution, and the stirring and reaction was continued for 8 hours. 219.49 g of acetic anhydride and 85.07 g of pyridine were added to the polyamic acid resin solution and stirred rapidly to obtain a high molecular weight polyimide solution containing active group end-capping.

[0207] Under nitrogen protection, 54.81 g (0.19 mol) of 1,3-bis(4'-aminophenoxy)benzene (1,3,4'-APB), 20.01 g (0.06 mol) of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) and 314.17 g of N,N-dimethylacetamide (DMAc) were added to a reaction vessel equipped with a mechanical stirrer, and the mixture was stirred until the diamine was completely dissolved to obtain a homogeneous solution. Then, 36.78 g (0.13 mol) of 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) was added to the homogeneous solution of diamine, and 40.52 g of N,N-dimethylacetamide (DMAc) was added. After stirring at room temperature until it was clear, 59.98 g (0.24 mol) of 4-phenylethynylphthalic anhydride (PEPA) and 40.52 g of N,N-dimethylacetamide (DMAc) were added to the solution, and the stirring reaction was continued for 8 hours. 127.61 g of acetic anhydride and 49.36 g of pyridine were added to the above polyamic acid resin solution and stirred rapidly to obtain an imide oligomer solution containing active groups.

[0208] The two solutions prepared above were blended in a mass ratio of 60:40 between high molecular weight polyimide capped with active groups and imide oligomer. After stirring at room temperature for 2 hours, ethanol was added to the mixed solution to precipitate the resin in a powder state. After filtering and washing, the mixture was dried in a blast oven to obtain a thermosetting polyimide resin.

[0209] Thermosetting polyimide was melt-extruded through a twin-screw extruder to prepare a filament with a diameter of 1.75±0.05mm, and a fused deposition 3D printer was used to print the standard tensile specimen. The filament preparation process parameters are as follows: the temperature of the twin-screw extruder zone I is 255℃, the temperature of the zone II is 265℃, the temperature of the zone III is 275℃, the speed of the feeding zone is 20rpm / min, and the spindle speed is 40rpm / min. The printing parameters are as follows: the printer nozzle temperature is 390℃, the base plate temperature is 160℃, the chamber temperature is 90℃, and the printing speed is 60mm / min.

[0210] The thermosetting polyimide printed sample is placed in a high-temperature oven for curing. The curing process is to directly heat the temperature to 380°C for 1 hour and then cool down to obtain the final product. Its main properties are shown in Table 1.

[0211] Table 1. Summary of thermosetting polyimide resin formulations and printed parts performance for FDM

[0212]

[0213] It can be seen from Table 1 that the T values ​​of the thermosetting polyimide resins in Examples 1-12 of the present invention are g The temperature is 270.4-290.7°C, the tensile strength of the printed strip in the X direction is 90.1-103.6 MPa, and the tensile strength of the printed strip in the Z direction is 70.2-88.4 MPa.

[0214] The difference between Example 9, Comparative Example 1, Comparative Example 2 and Comparative Example 3 is that the thermosetting polyimide resin in Example 9 is prepared by blending a high molecular weight polyimide containing active end groups and an imide oligomer, and the blending ratio (parts by mass) is 60:40; the thermosetting polyimide resin in Comparative Example 1 is also blended, but the blending ratio (parts by mass) is 50:50, and its mass ratio is not within the appropriate ratio range; in Comparative Example 2, only an imide oligomer end-capped with active groups exists; in Comparative Example 3, only a high molecular weight polyimide end-capped with active groups exists; the four thermosetting polyimide resins exhibit different properties due to different formulations.

[0215] As can be seen from Table 1, the mechanical properties of the thermosetting polyimide resin in Example 9 are higher than those in Comparative Examples 1, 2, and 3. The reason is that after the imide oligomer in Example 9 is implemented, the melt viscosity of the resin prepolymer can be reduced, which is beneficial to the interlayer melting of the resin during the melt deposition and curing process, and the printed parts have high density and improved mechanical properties. In Comparative Example 1, the mass fraction of the imide oligomer in the thermosetting polyimide resin is too high. Although the printing filament can be prepared, the filament has poor toughness and is difficult to withstand the meshing force of the gears during the printing process, and the spline cannot be printed. In Comparative Example 2, the thermosetting polyimide resin only contains imide oligomers, and the printing filament cannot be prepared due to poor mechanical properties. In Comparative Example 3, the thermosetting polyimide resin only contains high molecular weight polyimide terminated with active groups, and the melt viscosity is high. When preparing the printing filament, the temperature of the twin-screw extruder zone I, zone II, and zone III needs to be set to a higher temperature value than that of Example 9 to promote resin melt extrusion. During fused deposition molding, it is difficult for molecular chains to diffuse and entangle between layers, resulting in weak interlayer bonding and low mechanical properties of printed parts. At the same time, the cross-linking density of the printed parts is low and the heat resistance is poor. Comparative Example 4 uses a direct heating method, so the parts are difficult to solidify in a fixed shape, and there are a large number of pores inside, resulting in low mechanical properties.

[0216] The above performance comparison fully demonstrates that the thermosetting polyimide resin adopts two forms of high molecular weight polyimide and imide oligomer capped with active groups, and the mass ratio is within the appropriate range to give the best comprehensive performance to the thermosetting polyimide resin parts formed by fused deposition molding. The excellent comprehensive performance of the thermosetting polyimide resin in Examples 1-12 is a manifestation of the beneficial effects of the present invention compared with the prior art.

[0217] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A thermosetting polyimide resin, characterized in that: It includes active group-terminated high molecular weight polyimide and active group-terminated imide oligomer; The number average molecular weight M of the high molecular weight polyimide terminated with the active group n The number average molecular weight M of the active group-terminated imide oligomer is 15000-35000 g / mol. n It is 1000-5000g / mol, and the mass ratio of the two is (80-60):(20-40).

2. The thermosetting polyimide resin according to claim 1, characterized in that: The active group-terminated high molecular weight polyimide has a structure of general formula I: The repeating unit Contains any of the following structures: The end-capping group R is selected from at least one of the following groups:

3. The thermosetting polyimide resin according to claim 1 or 2, characterized in that: The active group-terminated imide oligomer has a structure of general formula II: Wherein, Ar' is selected from at least one of the following groups: R2 is selected from at least one of the following groups: R3 is selected from at least one of the following groups: The end-capping group R' is selected from at least one of the following groups:

4. A method for preparing a thermosetting polyimide resin, characterized in that: The method for preparing the thermosetting polyimide resin according to any one of claims 1 to 3 comprises the following steps: Step 1: preparing a high molecular weight polyimide solution terminated with an active group and an imide oligomer solution terminated with an active group respectively; Step 2: mixing the high molecular weight polyimide solution and the imide oligomer solution obtained in step 1 in proportion to obtain a thermosetting polyimide resin solution; Step 3: Post-treating the thermosetting polyimide resin solution obtained in step 2 to obtain polyimide resin powder.

5. The preparation method according to claim 4, characterized in that: In step 1, preparing a high molecular weight polyimide solution terminated with active groups comprises: synthesizing a high molecular weight polyamic acid solution terminated with active groups, and obtaining a high molecular weight polyimide solution terminated with active groups by imidization; The method for preparing the active group-terminated imide oligomer solution comprises: synthesizing the active group-terminated amic acid oligomer solution, and obtaining the active group-terminated imide oligomer solution through imidization.

6. A method for molding a thermosetting polyimide product, characterized in that: The steps include: Step a: melt-extrude the thermosetting polyimide resin according to any one of claims 1 to 3 to obtain a printing filament; Step b: melt-deposition printing the filament in step a into a self-supporting printed strip; Step c: heating the printed sample strip to solidify it, and cooling it to obtain a thermosetting polyimide product.

7. The molding method according to claim 6, characterized in that: In step a, the temperature of zone I of the twin-screw extruder is 245-270°C, the temperature of zone II is 255-280°C, and the temperature of zone III is 265-290°C.

8. The molding method according to claim 6 or 7, characterized in that: In step b, the printing temperature is 350-420°C, the base plate temperature is 150-170°C, the chamber temperature is 80-100°C, and the printing speed is 30-60 mm / min.

9. A thermosetting polyimide article, characterized in that: The thermosetting polyimide product is prepared by the molding method according to any one of claims 6 to 8, and has a room temperature tensile strength of ≥90MPa in the X-axis direction, a room temperature tensile strength of ≥70MPa in the Z-axis direction, a glass transition temperature Tg ≥270°C, and has high heat resistance, high mechanical properties and high inter-layer bonding strength.

10. Use of the thermosetting polyimide resin according to any one of claims 1 to 3, characterized in that: The thermosetting polyimide resin is applied to 3D printing fused deposition modeling to form components.

Images