Polyimide molding powder and preparation method thereof as well as polyimide molding profile and preparation method thereof

Abstract

The invention discloses polyimide molding powder, a preparation method of the polyimide molding powder, a polyimide molding profile and a preparation method of the polyimide molding profile, and relates to the field of high polymer materials, and the logarithmic viscosity of the polyimide molding powder is 70-150ml / g; and / or the particle size of the polyimide molding powder is 10-90 [mu] m. Compared with the prior art, the polyimide molding powder provided by the invention has proper logarithmic viscosity and particle size, has better processability and avoids the problems of undesirable phenomena and the like in the molding process when being applied to preparation of polyimide molding profiles; the high-temperature resistance, the mechanical property, the balance between a pressed surface and a non-pressed surface and the like of the obtained polyimide molded profile can be remarkably improved, so that the use requirements in different fields are met, and the application prospect is wide.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high molecular materials, in particular to a kind of polyimide molding powder and preparation method thereof, polyimide molding profile and preparation method thereof. BACKGROUND

[0002] Polyimide is the most excellent special engineering plastics in heat resistance, its initial thermal decomposition temperature is above 500 DEG C, long-term use temperature can reach 250 DEG C, short-term use temperature can be above 400 DEG C.As engineering plastics, there are thermosetting and thermoplastic, can be molded into shape also can be injection molding, with excellent physical heat resistance, high wear resistance, self-lubricating and radiation resistance, be called the ideal choice of precision moving parts, for each field needing high reliability and pursuing miniaturization and light weight, mainly as gear, bearing, shaft coupling, sealing element, sliding friction piece etc.Particularly in the field of aerospace.With the widening of product spectrum and the reduction of cost, it is now widely used in new energy vehicles, power electronics, scientific instruments, industrial machinery, production equipment and other fields.

[0003] At present, the more common synthetic method in the industry is to make precursor polyamide acid react in a solvent environment, and precipitate polyimide powder by heating. But this method still has obvious defects: the precipitation temperature of polyimide powder is still high, resulting in the prepared powder having low intrinsic viscosity, uneven particle size, and prone to poor phenomenon during molding process, and poor processing performance. SUMMARY

[0004] To solve the above problems, the present application provides a kind of polyimide molding powder and preparation method thereof, polyimide molding profile and preparation method thereof.

[0005] In the first aspect, the present application provides a kind of polyimide molding powder, the specific viscosity of the polyimide molding powder is 70~150ml / g; And / or, the particle size of the polyimide molding powder is 10~90 μm.

[0006] Further, the following raw materials are included: Formula 1 shows a dianhydride compound A, an aromatic dianhydride compound B, an aromatic diamine compound C and an alkyne-containing diamine compound D; The formula 1 is: ; wherein R1 and R2 are each independently phenyl, methyl, ethyl, -CF3, -C2F5, -C2F5, -C3F7, hydroxyl, acetoxy, m (trifluoromethyl) phenyl, p (perfluoro) phenyl, p-chlorophenyl.

[0007] Further, the molar ratio of the dianhydride compound A shown in Formula 1 to the aromatic dianhydride compound B is (0~20):(80~100), such as (1~20):(80~99), and the molar ratio of the alkynyl-containing diamine compound D to the aromatic diamine compound C is (0~10):(90~100), such as (1~10):(90~99). The molar ratio of the total molar amount of the dianhydride compound A and the aromatic dianhydride compound B shown in Formula 1 to the total molar amount of the aromatic diamine compound C and the alkynyl-containing diamine compound D is (1.0~1.1):(0.99~1.05).

[0008] Further, the dianhydride compound A shown in Formula 1 includes 9,9-diphenyloxanthracene dianhydride, 9,9-dimethyloxanthracene dianhydride, 9-methyl-9-ethyloxanthracene dianhydride, 9,9-diethyloxanthracene dianhydride, 9,9-dibutyloxanthracene dianhydride, 9-methyl-9-trifluoromethyloxanthracene dianhydride, 9,9-di(trifluoromethyl)oxanthracene dianhydride, 9-trifluoromethyl-9-pentafluoroethyloxanthracene dianhydride, 9,9-pentamethyleneoxanthracene dianhydride, 9,9-hexamethyleneoxanthracene dianhydride, and 9-methyl-9-phenyloxanthracene dianhydride. At least one of the following: oxanthracene dianhydride, 9-trifluoromethyl-9-phenyloxanthracene dianhydride, 9-pentafluoromethyl-9-phenyloxanthracene dianhydride, 9-heptafluoropropyl-9-phenyloxanthracene dianhydride, 9-trifluoromethyl-9-m(trifluoromethyl)phenyloxanthracene dianhydride, 9-heptafluoropropyl-9-p(perfluoro)phenyloxanthracene dianhydride, 9-hydroxy-9-phenyloxanthracene dianhydride, 9-acetoxy-9-phenyloxanthracene dianhydride, 9-hydroxy-9-p-chlorophenyloxanthracene dianhydride, and 9-acetoxy-9-p-chlorophenyloxanthracene dianhydride; The aromatic dianhydride compound B includes at least one selected from the following: pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',3,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride, 4,4'-(4,4'-isopropyldiphenoxy)bisphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, and 4,4'-(hexafluoroisopropene)bisphthalic anhydride; The aromatic diamine compound C includes at least one selected from p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 3,4'-diaminodiphenyl ether; The alkynyl-containing diamine compound D includes at least one of 3,5-diaminodiphenylacetylene, 1,3-diamino-4-phenylacetylbenzene, 3,5-diamino-4'-phenylacetylbenzene, 2,4-diamino-4'-phenylacetylbenzene ether, 2,4-diamino-1-(1-fluoro-4-phenylacetylphenoxy)benzene, and bis(3-aminophenyl)acetylene.

[0009] Secondly, based on the same inventive concept, the present invention provides a method for preparing the polyimide molding powder described in the first aspect, the method comprising the following steps: In an inert gas atmosphere, the solvent and aromatic diamine compound C are stirred and mixed, and then aromatic dianhydride compound B, dianhydride compound A as shown in Formula 1 and alkynyl diamine compound D are added in sequence to react and obtain a polyamic acid solution. The polyamic acid solution was heated under an inert gas atmosphere, then filtered, washed and dried to obtain the polyimide molding powder.

[0010] Further, under an inert gas atmosphere, the solvent and aromatic diamine compound C are stirred and mixed, and then aromatic dianhydride compound B, dianhydride compound A as shown in Formula 1, and alkynyl-containing diamine compound D are added sequentially to react and obtain a polyamic acid solution. The steps include the following: Under a nitrogen atmosphere, the reaction temperature is controlled at -20~30℃. The solvent and the aromatic diamine compound C are added to the reaction vessel and stirred continuously for 30~60 min. The aromatic dianhydride compound B is added in batches and stirred continuously for 60~180 min. Then, the dianhydride compound A shown in Formula 1 is added in batches and stirred for 60~180 min. Then, the alkynyl-containing diamine compound D is added in batches and stirred for 60~180 min. The mixture is allowed to stand for defoaming for 8~12 h. The viscosity of the system is controlled at 1500~6000 P to obtain the polyamic acid solution with a solid content of 10~30 wt%. The solvent includes at least one of benzene, toluene, xylene, acetone, hexane, heptane, chlorobenzene, methanol, ethanol, n-propanol, isopropanol, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylchloroformamide, N,N-dimethylchloroformamide, N-diethylformamide, 2-chloro-4-hydroxybenzoic acid, dimethyl silicone oil, trimethyl silicone oil, tetramethyl silicone oil, γ-butyrolactone, cyclohexenone, cyclopentenone, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, dibromomethane, and tribromomethane; The steps of heating the polyamic acid solution under an inert gas atmosphere, followed by filtration, washing, and drying to obtain the polyimide molding powder include the following processes: Under a nitrogen atmosphere, stirring is turned on, and the polyamic acid solution is heated to 150-220°C at a heating rate of 2-5°C / min. After holding at this temperature for 5-10 hours, it is cooled to room temperature to obtain a polyimide molding powder suspension. The polyimide molding powder suspension is filtered, washed, and dried. The resulting solid is then ground and sieved to obtain the polyimide molding powder.

[0011] Thirdly, based on the same inventive concept, the present invention provides a polyimide molding profile, comprising the polyimide molding powder described in the first aspect or the polyimide molding powder prepared by the method described in the second aspect.

[0012] Furthermore, the physicochemical properties of the polyimide molded profile include: Density 1.45–1.55 g / cm³ 3 ; And / or, the ratio of the linear expansion coefficients of the non-compression surface to the compression surface is 1 to 1.3; And / or, the coefficient of linear expansion in the temperature range of 50℃≤T1<300℃ is not higher than 60ppm / ℃; And / or, the coefficient of linear expansion in the temperature range of 300℃≤T1<350℃ is not higher than 80ppm / ℃; And / or, the coefficient of thermal expansion in the temperature range of 350℃≤T1≤400℃ is not higher than 90ppm / ℃.

[0013] Fourthly, based on the same inventive concept, the present invention provides a method for preparing the polyimide molded profile described in the third aspect, comprising the following steps: The polyimide molding powder is pressed into shape to obtain the polyimide molded profile.

[0014] Further, the step of pressing the polyimide molding powder to obtain the polyimide molded profile includes the following processes: The polyimide molding powder is preheated at 200-300℃ for 30-180 minutes, and then evenly spread into the mold cavity. The temperature inside the mold cavity is increased to 300-360℃ at a rate of 3-10℃ / min, and the pressure is increased to 30-80MPa and stabilized for 30-60 minutes. The temperature is further increased to 350-450℃, and the pressure is increased to 70-120MPa. The temperature and pressure are maintained for 1-8 hours, and then heating is stopped. The temperature is allowed to drop naturally to 100-200℃, and the pressure is released and the mold is demolded to obtain the polyimide molded profile.

[0015] The technical solutions provided in the embodiments of the present invention have at least the following advantages compared with the prior art: This invention provides a polyimide molding powder and its preparation method, as well as a polyimide molding profile and its preparation method. Compared with the prior art, the polyimide molding powder provided by this invention has suitable specific viscosity, logarithmic viscosity, and particle size. When applied to the preparation of polyimide molding profiles, it exhibits superior processing performance and avoids problems such as defects during molding. It can significantly improve the high-temperature resistance, mechanical properties, and the uniformity of the pressure-bearing and non-pressure-bearing surfaces of the resulting polyimide molding profiles, thereby meeting the application needs of different fields and showing broad application prospects. Specifically: 1. The polyimide molding powder developed in this invention has small and uniform particle size and large molecular weight. The profiles prepared with this invention have high uniformity between the pressure-bearing and non-pressure-bearing surfaces, high high temperature resistance, and high mechanical properties.

[0016] 2. This invention, through innovative molecular structure design, introduces xanthracene units and coordinates them with aromatic diamine dianhydride units to achieve control over material properties. The rigid, large-volume, non-coplanar xanthracene units, containing ether bonds (-O-) and a three-dimensional aromatic heterocyclic structure, significantly increase the rigidity and aromaticity of the polyimide backbone, making the molecular chains more difficult to move and decompose at high temperatures, thus meeting the application requirements of extreme high-temperature environments. On the other hand, the rigid and large xanthracene units enhance the rigidity between molecular chains, thereby improving the material's modulus and strength. Simultaneously, its non-completely coplanar structure, to some extent, avoids excessively close packing of molecular chains, helping to maintain a certain degree of toughness. The ether bonds (-O-) further provide flexibility to the chain segments, while its non-coplanar three-dimensional structure effectively disrupts the regularity and planarity of the polyimide molecular chains, reducing close packing between molecular chains and the formation of strong charge-transfer complexes, thereby weakening intermolecular forces and endowing the molding powder with excellent processing properties.

[0017] 3. On the other hand, introducing diamines containing alkynyl groups into the molecular chain causes the polyimide molding powder to undergo a cross-linking reaction between polyimide molecules again at 300-450℃ during the molding process, forming a cross-linked network. This connects the originally linear or branched polyimide molecular chains into a robust three-dimensional network structure, which can further increase the rigidity and strength of polyimide molded profiles. At the same time, the cross-linked network firmly locks the molecular chains, suppresses thermal expansion, and ensures the stability and balance of the material's performance.

[0018] 4. The preparation process of this invention is simple, efficient, and easy to implement for industrial production. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The infrared spectrum of the polyimide molding powder provided in the embodiments of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. Furthermore, unless otherwise specified or detailed, the steps and parameters involved can be performed according to the polyimide molding powder preparation process steps and parameters disclosed in the prior art, or directly using existing equipment according to the instruction manual; these will not be elaborated upon further in this invention document.

[0024] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then generally accepted international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0025] Example 1 This example provides a polyimide molding powder and a polyimide molded profile prepared using the polyimide molding powder, including the following steps: Under a nitrogen atmosphere, with the reaction temperature controlled at 20℃, 100g of N,N-dimethylacetamide, 25g of xylene, and 0.041mol of 4,4'-diaminodiphenyl ether were added to the reactor and stirred continuously for 30min. Then, 0.042mol of pyromellitic dianhydride was added in batches and stirred for 60min. Next, 0.001mol of 9,9-diphenyloxanthracene dianhydride was added in batches and stirred for 120min. Finally, 0.002mol of 1,3-diamino-4-benzynebenzene was added in batches and stirred for 120min. The mixture was allowed to stand for 8h to defoam and the viscosity of the system was controlled to obtain a polyamic acid solution. Under a nitrogen atmosphere, stirring was started, and the above polyamic acid solution was heated to 165°C at 3°C / min, kept at this temperature for 6 hours, and then cooled to room temperature to obtain a polyimide molding powder suspension. The above polyimide molding powder suspension was filtered multiple times, washed, filtered, and then pre-dried under reduced pressure at 180°C for 3 hours, and then dried in a rotary drum or spiral at 250°C for 6 hours. After grinding and sieving, polyimide molding powder was obtained. The above-mentioned polyimide molding powder is preheated at 230℃ for 60 minutes, and then evenly spread into the mold cavity. The heating rate is controlled at 5℃ / min, and the temperature inside the cavity is raised to 300℃. The pressure is increased to 50MPa and stabilized for 30 minutes. The temperature is then increased to 400℃ and the pressure is increased to 105MPa. The temperature and pressure are maintained for 5 hours. Heating is then stopped, and the temperature is allowed to drop naturally to 150℃. The pressure is released and the mold is demolded to obtain the polyimide molded profile.

[0026] Example 2 The only difference between this embodiment and Embodiment 1 is that: (1) Replace only 9,9-diphenyloxanthracene dianhydride with 9-methyl-9-phenyloxanthracene dianhydride.

[0027] Example 3 The only difference between this embodiment and Embodiment 1 is that: (1) Replace only 1,3-diamino-4-benzylidene with 2,4-diamino-4'-benzylidene diphenyl ether.

[0028] Example 4 The only difference between this embodiment and Embodiment 1 is that: (1) Only 0.042 mol pyromellitic dianhydride and 0.001 mol 9,9-diphenyloxane dianhydride were adjusted to 0.041 mol pyromellitic dianhydride and 0.002 mol 9,9-diphenyloxane dianhydride, respectively.

[0029] Example 5 The only difference between this embodiment and Embodiment 1 is that: (1) Only 0.041 mol 4,4'-diaminodiphenyl ether and 0.002 mol 1,3-diamino-4-benzylidene were adjusted to 0.042 mol 4,4'-diaminodiphenyl ether and 0.001 mol 1,3-diamino-4-benzylidene, respectively.

[0030] Comparative Example 1 This example provides a polyimide molding powder and a polyimide molded profile prepared using the polyimide molding powder, including the following steps: Under a nitrogen atmosphere, the reaction temperature was controlled at 20℃. 100g of N,N-dimethylacetamide, 25g of xylene, and 0.042mol of 4,4'-diaminodiphenyl ether were added to the reactor and stirred continuously for 30min. 0.042mol of pyromellitic dianhydride was added in batches and stirred for 120min. The mixture was allowed to stand for 8h to remove foam and the viscosity of the system was controlled to obtain a polyamic acid solution. Under a nitrogen atmosphere, stirring was started, and the above polyamic acid solution was heated to 165°C at 3°C / min, kept at this temperature for 6 hours, and then cooled to room temperature to obtain a polyimide molding powder suspension. The above polyimide molding powder suspension was filtered multiple times, washed, filtered, and then pre-dried under reduced pressure at 180°C for 3 hours, and then dried in a rotary drum or spiral at 250°C for 6 hours. After grinding and sieving, polyimide molding powder was obtained. The above molding powder is preheated at 230℃ for 60 minutes, then evenly spread into the mold cavity. The heating rate is controlled at 5℃ / min, and the temperature inside the cavity is raised to 300℃. The pressure is increased to 50MPa and stabilized for 30 minutes. The temperature is then increased to 400℃ and the pressure is increased to 105MPa. The temperature and pressure are maintained for 5 hours. Heating is then stopped, and the temperature is allowed to drop naturally to 150℃. The pressure is released and the mold is demolded to obtain the polyimide molded profile.

[0031] Comparative Example 2 This example provides a polyimide molding powder and a polyimide molded profile prepared using the polyimide molding powder, including the following steps: Under a nitrogen atmosphere, with the reaction temperature controlled at 20℃, 100g of N,N-dimethylacetamide, 25g of xylene, and 0.041mol of 4,4'-diaminodiphenyl ether were added to the reactor and stirred continuously for 30min. Then, 0.042mol of pyromellitic dianhydride was added in batches and stirred for 120min. Next, 0.001mol of 1,3-diamino-4-benzyne benzene was added in batches and stirred for 120min. The mixture was allowed to stand for 8h to defoam and the viscosity of the system was controlled to obtain a polyamic acid solution. Under a nitrogen atmosphere, stirring was started, and the above polyamic acid solution was heated to 165°C at 3°C / min, kept at this temperature for 6 hours, and then cooled to room temperature to obtain a polyimide molding powder suspension. The above polyimide molding powder suspension was filtered multiple times, washed, filtered, and then pre-dried under reduced pressure at 180°C for 3 hours, and then dried in a rotary drum or spiral at 250°C for 6 hours. After grinding and sieving, polyimide molding powder was obtained. The above molding powder is preheated at 230℃ for 60 minutes, then evenly spread into the mold cavity. The heating rate is controlled at 5℃ / min, and the temperature inside the cavity is raised to 300℃. The pressure is increased to 50MPa and stabilized for 30 minutes. The temperature is then increased to 400℃ and the pressure is increased to 105MPa. The temperature and pressure are maintained for 5 hours. Heating is then stopped, and the temperature is allowed to drop naturally to 150℃. The pressure is released and the mold is demolded to obtain the polyimide molded profile.

[0032] Test case This example demonstrates the performance testing of the polyimide molding powder and polyimide molding profiles obtained in the above embodiments and comparative examples; the performance test results of the polyimide molding powder are shown in Table 1, and the performance test results of the polyimide molding profiles are shown in Table 2.

[0033] Table 1 Table 1 shows that, compared with Comparative Examples 1-2, Examples 1-5 have higher specific logarithmic viscosity (higher molecular weight), more uniform and finer molding powder particle size, which is beneficial for processing. This indicates that the present invention achieves the regulation of material properties by introducing xanthracene units and synergistically using aromatic diamine dianhydride units. Among them, the rigid, large-volume, non-coplanar xanthracene units with a three-dimensional aromatic heterocyclic structure containing ether bonds (-O-) greatly increase the rigidity and aromaticity of the polyimide backbone, making the molecular chains more difficult to move and decompose at high temperatures, thus meeting the application requirements of extreme high-temperature environments. On the other hand, the rigid and large xanthracene units enhance the rigidity between molecular chains, thereby improving the modulus and strength of the material. At the same time, its non-completely coplanar structure avoids the excessively close packing of molecular chains to a certain extent, which helps to maintain a certain degree of toughness. The ether bonds (-O-) further provide the flexibility of the chain segments, while its non-coplanar three-dimensional structure effectively disrupts the regularity and planarity of the polyimide molecular chains, reduces the close packing between molecular chains and the formation of strong charge-transfer complexes, thereby weakening the intermolecular forces.

[0034] Table 2 As shown in Table 2, compared with the comparative examples (Examples 1-5), the polyimide profiles prepared using this patent have higher density, more uniformity, and a smaller coefficient of linear expansion (balance between compressed and non-compressed surfaces), ensuring the stability and uniformity of the material's performance. The polyimide profiles prepared by this method have a density of 1.45–1.55 g / cm³. 3 The ratio of the linear expansion coefficient of the non-compression surface to that of the compression surface is 1~1.3, with the linear expansion coefficient not exceeding 60ppm / ℃ at 50~300℃, not exceeding 80ppm / ℃ at 300~350℃, and not exceeding 90ppm / ℃ at 350~400℃. It exhibits higher and more uniform overall performance.

[0035] In summary, the embodiments of the present invention provide a polyimide molding powder and its preparation method, as well as a polyimide molding profile and its preparation method. Compared with the prior art, the polyimide molding powder provided by the present invention has suitable specific viscosity, logarithmic viscosity, and particle size. When applied to the preparation of polyimide molding profiles, it has better processing performance and avoids problems such as adverse phenomena during the molding process. It can significantly improve the high temperature resistance, mechanical properties, and the balance between the pressure surface and the non-pressure surface of the obtained polyimide molding profile, thereby meeting the application needs of different fields and having broad application prospects.

[0036] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0037] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A polyimide molding powder, characterized in that, The specific logarithmic viscosity of the polyimide molding powder is 70~150 ml / g; And / or, the particle size of the polyimide molding powder is 10~90μm.

2. The polyimide molding powder according to claim 1, characterized in that, Including the following raw materials: The compounds shown in Formula 1 are: dianhydride compound A, aromatic dianhydride compound B, aromatic diamine compound C, and alkynyl-containing diamine compound D; Equation 1: R1 and R2 are each independently phenyl, methyl, ethyl, -CF3, -C2F5, -C2F5, -C3F7, hydroxyl, acetoxy, m-(trifluoromethyl)phenyl, p-(perfluoro)phenyl, and p-chlorophenyl.

3. The polyimide molding powder according to claim 2, characterized in that, The molar ratio of the dianhydride compound A shown in Formula 1 to the aromatic dianhydride compound B is (0~20):(80~100), and the molar ratio of the alkynyl-containing diamine compound D to the aromatic diamine compound C is (0~10):(90~100). The molar ratio of the total molar amount of the dianhydride compound A and the aromatic dianhydride compound B shown in Formula 1 to the total molar amount of the aromatic diamine compound C and the alkynyl-containing diamine compound D is (1.0~1.1):(0.99~1.05).

4. The polyimide molding powder according to claim 2, characterized in that, The dianhydride compound A shown in Formula 1 includes 9,9-diphenyloxanthracene dianhydride, 9,9-dimethyloxanthracene dianhydride, 9-methyl-9-ethyloxanthracene dianhydride, 9,9-diethyloxanthracene dianhydride, 9,9-dibutyloxanthracene dianhydride, 9-methyl-9-trifluoromethyloxanthracene dianhydride, 9,9-di(trifluoromethyl)oxanthracene dianhydride, 9-trifluoromethyl-9-pentafluoroethyloxanthracene dianhydride, 9,9-pentamethyleneoxanthracene dianhydride, 9,9-hexamethyleneoxanthracene dianhydride, and 9-methyl-9-phenyloxanthracene dianhydride. At least one of anthracene dianhydride, 9-trifluoromethyl-9-phenyloxanthracene dianhydride, 9-pentafluoromethyl-9-phenyloxanthracene dianhydride, 9-heptafluoropropyl-9-phenyloxanthracene dianhydride, 9-trifluoromethyl-9-m(trifluoromethyl)phenyloxanthracene dianhydride, 9-heptafluoropropyl-9-p(perfluoro)phenyloxanthracene dianhydride, 9-hydroxy-9-phenyloxanthracene dianhydride, 9-acetoxy-9-phenyloxanthracene dianhydride, 9-hydroxy-9-p-chlorophenyloxanthracene dianhydride and 9-acetoxy-9-p-chlorophenyloxanthracene dianhydride; The aromatic dianhydride compound B includes at least one selected from the following: pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 2,3',3,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3',3,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxybisphthalic anhydride, 4,4'-(4,4'-isopropyldiphenoxy)bisphthalic anhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, and 4,4'-(hexafluoroisopropene)bisphthalic anhydride; The aromatic diamine compound C includes at least one selected from p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, and 3,4'-diaminodiphenyl ether; The alkynyl-containing diamine compound D includes at least one of 3,5-diaminodiphenylacetylene, 1,3-diamino-4-phenylacetylbenzene, 3,5-diamino-4'-phenylacetylbenzene, 2,4-diamino-4'-phenylacetylbenzene ether, 2,4-diamino-1-(1-fluoro-4-phenylacetylphenoxy)benzene, and bis(3-aminophenyl)acetylene.

5. A method for preparing the polyimide molding powder according to any one of claims 1 to 4, characterized in that, Includes the following steps: In an inert gas atmosphere, the solvent and aromatic diamine compound C are stirred and mixed, and then aromatic dianhydride compound B, dianhydride compound A as shown in Formula 1 and alkynyl diamine compound D are added in sequence to react and obtain a polyamic acid solution. The polyamic acid solution was heated under an inert gas atmosphere, then filtered, washed and dried to obtain the polyimide molding powder.

6. The method for preparing polyimide molding powder according to claim 5, characterized in that, In an inert gas atmosphere, the solvent and aromatic diamine compound C are stirred and mixed, followed by the sequential addition of aromatic dianhydride compound B, dianhydride compound A (as shown in Formula 1), and alkynyl-containing diamine compound D to obtain a polyamic acid solution. The steps include the following: Under a nitrogen atmosphere, the reaction temperature is controlled at -20~30℃. The solvent and the aromatic diamine compound C are added to the reaction vessel and stirred continuously for 30~60 min. The aromatic dianhydride compound B is added in batches and stirred continuously for 60~180 min. Then, the dianhydride compound A shown in Formula 1 is added in batches and stirred for 60~180 min. Then, the alkynyl-containing diamine compound D is added in batches and stirred for 60~180 min. The mixture is allowed to stand for defoaming for 8~12 h. The viscosity of the system is controlled at 1500~6000 P to obtain the polyamic acid solution with a solid content of 10~30 wt%. The solvent includes at least one of benzene, toluene, xylene, acetone, hexane, heptane, chlorobenzene, methanol, ethanol, n-propanol, isopropanol, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylchloroformamide, N,N-dimethylchloroformamide, N-diethylformamide, 2-chloro-4-hydroxybenzoic acid, dimethyl silicone oil, trimethyl silicone oil, tetramethyl silicone oil, γ-butyrolactone, cyclohexenone, cyclopentenone, dichloromethane, chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, dibromomethane, and tribromomethane; The steps of heating the polyamic acid solution under an inert gas atmosphere, followed by filtration, washing, and drying to obtain the polyimide molding powder include the following processes: Under a nitrogen atmosphere, stirring is turned on, and the polyamic acid solution is heated to 150-220°C at a heating rate of 2-5°C / min. After holding at this temperature for 5-10 hours, it is cooled to room temperature to obtain a polyimide molding powder suspension. The polyimide molding powder suspension is filtered, washed, and dried. The resulting solid is then ground and sieved to obtain the polyimide molding powder.

7. A polyimide molded profile, characterized in that, The polyimide molding powder includes any one of claims 1 to 4 or the polyimide molding powder prepared by the method of any one of claims 5 to 6.

8. The polyimide molded profile according to claim 7, characterized in that, The physicochemical properties of the polyimide molded profile include: Density 1.45–1.55 g / cm³ 3 ; And / or, the ratio of the linear expansion coefficients of the non-compression surface to the compression surface is 1 to 1.3; And / or, the coefficient of linear expansion in the temperature range of 50℃≤T1<300℃ is not higher than 60ppm / ℃; And / or, the coefficient of linear expansion in the temperature range of 300℃≤T1<350℃ is not higher than 80ppm / ℃; And / or, the coefficient of thermal expansion in the temperature range of 350℃≤T1≤400℃ is not higher than 90ppm / ℃.

9. A method for preparing a polyimide molded profile according to any one of claims 7-8, characterized in that, Includes the following steps: The polyimide molding powder is pressed into shape to obtain the polyimide molded profile.

10. The method for preparing polyimide molding powder according to claim 9, characterized in that, The step of pressing the polyimide molding powder to obtain the polyimide molded profile includes the following processes: The polyimide molding powder is preheated at 200-300℃ for 30-180 minutes, and then evenly spread into the mold cavity. The temperature inside the mold cavity is increased to 300-360℃ at a rate of 3-10℃ / min, and the pressure is increased to 30-80MPa and stabilized for 30-60 minutes. The temperature is further increased to 350-450℃, and the pressure is increased to 70-120MPa. The temperature and pressure are maintained for 1-8 hours, and then heating is stopped. The temperature is allowed to drop naturally to 100-200℃, and the pressure is released and the mold is demolded to obtain the polyimide molded profile.

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