High-plasticity polyimide molding powder and preparation method thereof

Abstract

The invention discloses high-plasticity polyimide molding powder and a preparation method thereof, and relates to the field of polyimide molding powder.The preparation method comprises the following steps that in the inert gas atmosphere, a diamine monomer A1 and a dianhydride monomer H1 are added into a first solvent to be subjected to a first stirring reaction, a resin solution with the viscosity being 5-100 Wcp is obtained, and the like. The polyimide molding powder with the core-shell structure is mainly prepared by adopting specific raw material monomers, the polyimide resin A is an inner core and has the characteristics of higher rigidity, higher heat resistance grade, poorer plasticity and the like, and the polyimide resin B is an outer shell and has the characteristics of lower rigidity, better plasticity and the like. The two kinds of materials are matched for use, so that the defects of poor mold pressing performance and impact performance and the like of the existing polyimide molding powder are overcome, and the defects in the prior art are overcome.

Description

Technical Field

[0001] This invention relates to the field of polyimide molding powder, and more particularly to a high-plasticity polyimide molding powder and its preparation method. Background Technology

[0002] Polyimide is a polymer material with extremely high heat resistance, capable of short-term temperature resistance up to 400℃ and long-term temperature resistance above 280℃. It also possesses high strength, high modulus, solvent resistance, radiation resistance, and ultra-high dimensional stability, making it one of the best-performing organic polymer materials. Polyimide molding products are widely used in the manufacture of key components for aircraft, ships, and heavy machinery. Because high-heat-resistant polyimide molding compounds lack a significant softening point, they cannot be molded using injection molding or extrusion processes and can only be formed through high-temperature compression molding. The particle size and high-temperature plasticity of the molding powder are key indicators affecting the molding effect.

[0003] The polyimide molding compound with the highest temperature resistance is typically the pyromellitic polyimide molding compound represented by DuPont's Vespal, synthesized from pyromellitic tetracarboxylic anhydride and diaminodiphenyl ether. The polyimide molding powder synthesized from this formulation has high rigidity, making compression molding difficult and requiring sophisticated molding equipment. Furthermore, the product exhibits poor toughness and low impact strength. Therefore, improving its moldability and impact resistance is crucial for product improvement. Summary of the Invention

[0004] To overcome the problems in the prior art, the present invention provides a high-plasticity polyimide molding powder and its preparation method.

[0005] In a first aspect, the present invention provides a method for preparing a highly ductile polyimide molding powder, comprising the following steps: Under an inert gas atmosphere, diamine monomer A1 and dianhydride monomer H1 are added to a first solvent for a first stirring reaction to obtain a resin solution with a viscosity of 5 W to 100 W cp; then a dehydrating agent is added to the resin solution for a second stirring reaction, followed by filtration, washing and drying to obtain polyimide resin powder A; Under an inert gas atmosphere, the polyimide resin powder A and the dehydrating agent are added to the second solvent, followed by the addition of diamine monomer A2 and dianhydride monomer H2 for a third stirring reaction. After filtration, washing and drying, a high-plasticity polyimide molding powder containing polyimide resin powder A and polyimide resin powder B is obtained. The polyimide resin powder A and the polyimide resin powder B are of different types.

[0006] Furthermore, the physicochemical properties of the polyimide resin powder A and the polyimide resin powder B satisfy the following relationship: The rigidity of the polyimide resin powder A is greater than that of the polyimide resin powder B; And / or, the plasticity of the polyimide resin powder A is less than the plasticity of the polyimide resin powder B.

[0007] Further, the diamine monomer A1 includes at least one of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl sulfone; The dianhydride monomer H1 is at least one of pyromellitic dianhydride, biphenyl dianhydride, diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, and 3,4,9,10-perylenetetracarboxylic dianhydride.

[0008] Furthermore, the total mass of the diamine monomer A1 and the dianhydride monomer H1 accounts for 5-10% of the total solution mass; The amount of dehydrating agent added is 0.5 to 2 times the sum of the masses of the diamine monomer A1 and the dianhydride monomer H1 (the amount of dehydrating agent used in the preparation of resin B is similar to that used in the preparation of resin A).

[0009] Furthermore, the diamine monomer A2 includes at least one of p-phenylenediamine, m-phenylenediamine, and 4,4'-diaminodiphenyl ether; The dianhydride monomer H2 includes at least one of 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride and bisphenol A type diether dianhydride; Alternatively, the diamine monomer A2 comprises at least one of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl, and 4,4'-bis(3-aminophenoxy)diphenyl sulfone; The dianhydride monomer H2 includes at least one of biphenyltetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and bisphenol A type diether dianhydride.

[0010] Furthermore, the dehydrating agent includes at least one of toluene, xylene, dichloroethane, acetic anhydride, and propionic anhydride.

[0011] Furthermore, the particle size of the polyimide resin powder A is 5-15 micrometers.

[0012] Further, the mass ratio of the polyimide resin powder A to the polyimide resin powder B is (60~95):(5~40). The molar ratio of the diamine monomer A1 to the dianhydride monomer H1 is (0.9~1.1):(0.9~1.1). The molar ratio of the diamine monomer A2 to the dianhydride monomer H2 is (0.9~1.1):(0.9~1.1).

[0013] Furthermore, the operating conditions for both the second and third stirring reactions include: a temperature of 130~190℃ and a time of 2~6h.

[0014] Secondly, based on the same inventive concept, the present invention provides a high-plasticity polyimide molding powder, which is prepared by the method for preparing high-plasticity polyimide molding powder described in the first aspect.

[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 primarily involves preparing a core-shell structured polyimide molding powder using specific raw material monomers. Polyimide resin A forms the core, characterized by high rigidity, high heat resistance, and poor plasticity. Polyimide resin B forms the outer shell, characterized by lower rigidity and better plasticity. The combination of these two materials overcomes the shortcomings of existing polyimide molding powders, such as poor molding performance and impact resistance, thus compensating for the deficiencies of current technologies. Specifically: 1. To address the difficulty in molding high-temperature-resistant polyimide molding powders in existing technologies, this invention prepares an A+B structured polyimide powder. Formula A maintains the material's temperature resistance, while formula B possesses certain plasticity, improving the material's moldability. Therefore, the polyimide powder provided by this invention significantly expands the powder molding process window while maintaining a substantially unchanged heat resistance level.

[0016] 2. To address the problem of poor stability of A+B polyimide molding powder in the prior art, the high-plasticity polyimide molding powder provided by the present invention uses anhydride-terminated polymer formulation for the A structure, which can be covalently linked with the amino group in the B structure polymer, effectively preventing core-shell structure separation failure, thereby making up for the shortcomings of the prior art.

[0017] 3. This invention prepares A-structure powder by chemical imidization, resulting in powder with uniform and fine particle size. The B structure coats the outer surface of the A structure, forming PI powder with a narrow particle size distribution, which makes the powder uniform in particle size, has good flowability, and is easy to process as a molding filler. Attached Figure Description

[0018] 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.

[0019] 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.

[0020] Figure 1 This is a schematic diagram of the core-shell structure of the high-plasticity polyimide molding powder provided in an embodiment of the present invention.

[0021] Figure 2 Infrared spectra of the high-plasticity polyimide molding powders provided in Examples 1-3 and Comparative Example 1 of this 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] The technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for preparing a highly ductile polyimide molding powder, comprising the following steps: Under an inert gas atmosphere, diamine monomer A1 and dianhydride monomer H1 are added to a first solvent for a first stirring reaction to obtain a resin solution with a viscosity of 5 W to 100 W cp; then a dehydrating agent is added to the resin solution for a second stirring reaction, followed by filtration, washing and drying to obtain polyimide resin powder A; Under an inert gas atmosphere, the polyimide resin powder A and the dehydrating agent are added to the second solvent, followed by the addition of diamine monomer A2 and dianhydride monomer H2 for a third stirring reaction. After filtration, washing and drying, a high-plasticity polyimide molding powder containing polyimide resin powder A and polyimide resin powder B is obtained.

[0024] Specifically, the preparation of this highly ductile polyimide molding powder includes the following steps: Step 1, Synthesis of Component A Resin Powder: Diamine A1 is dissolved in an aprotic polar solvent, and the temperature is maintained at 0–40℃ under inert gas protection. Then, dianhydride H1 is added in batches, with thorough stirring after each addition until the resin solution viscosity reaches 5 W–100 Wcp. At this point, the molar ratio of diamine A1 to dianhydride H1 is approximately 1:1. The actual amount of dianhydride H1 added is determined by whether the resin solution viscosity reaches the specified value. A dehydrating agent is then added to the resin solution, and the temperature is slowly raised to 130–190℃. The solution is stirred thoroughly for 2–6 hours, resulting in the precipitation of a pale yellow powder. Through multiple filtrations, washings (commonly used detergents include one or more of DMF, DMAc, NMP, DMSO, THF, acetone, and ethanol), drying, and sieving, the polyimide resin powder of component A is obtained.

[0025] Step 2, Synthesis of A+B Structure Resin Powder: Resin powder A is uniformly dispersed in an aprotic polar solvent, and a certain amount of dehydrating agent is added and stirred until homogeneous. Diamine monomer A2 is dissolved in an aprotic polar solvent containing A powder, maintaining the temperature between 0 and 40°C under inert gas protection. Then, dianhydride monomer H2 is added in batches, with thorough stirring after each addition to ensure uniform reaction. The molar ratio of diamine A2 to dianhydride H2 is 1:1. The resin solution temperature is slowly raised to 130–190°C and stirred thoroughly for 2–6 hours. Through multiple filtrations, washing, and drying processes, polyimide resin powder with the A+B structure is obtained.

[0026] Secondly, the present invention provides a highly ductile polyimide molding powder, such as... Figure 1 As shown, it has the following core-shell structure, in which polyimide resin A is the core, and its main component is polyimide with high rigidity, high heat resistance and poor plasticity, and polyimide resin B is the shell, and its main component is polyimide with low rigidity and good plasticity.

[0027] 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 existing technology's disclosed high-plasticity polyimide molding powder preparation process steps and parameters, or directly using existing equipment according to the instruction manual. These will not be elaborated upon further in this invention document.

[0028] 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.

[0029] Example 1 This example provides a highly ductile polyimide molding powder, the preparation method of which includes the following steps: ① Synthesis of Resin Powder of Component A: In a 1L three-necked flask equipped with a mechanical stirrer, thermometer, and nitrogen inlet tube, 400 g of N-methylpyrrolidone (NMP) was added, and high-purity nitrogen was introduced for protection. 21.6 g (0.2 mol) of m-phenylenediamine (m-PDA) was weighed and added to the flask, stirred to dissolve, and the reaction system temperature was maintained at 20±5℃. 43.2 g (0.2 mol) of biphenyltetracarboxylic dianhydride (BPDA) was added in 5 batches, stirring thoroughly after each addition until the solution was homogeneous before adding the next batch, until the resin solution viscosity reached approximately 20,000 cP as measured by a rotational viscometer. Subsequently, 130 g of acetic anhydride (dehydrating agent) and 60 mL of xylene (azeotropic dehydrating agent) were added to the resin solution, and stirred until homogeneous. The reaction system temperature was slowly increased to 180℃ at a rate of 1℃ / min, and the reaction was continuously stirred at this temperature for 4 hours. During the reaction, a pale yellow powder gradually precipitated. After the reaction was completed, the mixture was cooled to room temperature, and the product was filtered multiple times and washed three times alternately with ethanol and acetone to thoroughly remove the solvent and byproducts. The filter cake was dried in a vacuum oven at 120°C for 12 hours and finally passed through a 400-mesh sieve to obtain a pale yellow polyimide resin powder of component A with a particle size of approximately 10 micrometers.

[0030] ② Synthesis of A+B structure resin powder: Take 80 g of the dried A component powder mentioned above and redisperse it in 500 g of NMP. Sonicate the powder for 30 minutes to ensure uniform dispersion. Add 50 g of acetic anhydride to the dispersion and stir until homogeneous. Weigh 4.0 g (0.02 mol) of 4,4'-diaminodiphenyl ether (ODA) and add it to the NMP dispersion containing the A powder. Maintain the temperature at 25±5℃ and purge with nitrogen. Add 5.9 g (0.02 mol) of benzophenone tetracarboxylic dianhydride (BTDA) in batches, maintaining a diamine to dianhydride molar ratio of 1:1, and stir thoroughly after each addition. Similarly, slowly raise the resin solution temperature to 175℃ and stir for 5 hours. After the reaction is complete, cool, filter, wash repeatedly with DMF and ethanol, and finally vacuum dry at 120℃ to obtain the core-shell structured A+B polyimide molding powder. The mass ratio of A component to B component in the final product is 80:20.

[0031] Example 2 This example provides a highly ductile polyimide molding powder, the preparation method of which includes the following steps: ① Synthesis of component A resin powder: p-phenylenediamine (p-PDA, 21.6 g, 0.2 mol) was used as diamine A1, and pyromellitic dianhydride (PMDA, 43.6 g, 0.2 mol) was used as dianhydride H1. The operation procedure was the same as in Example 1. After controlling the reaction viscosity to approximately 50,000 cP, 150 g of propionic anhydride and 70 mL of toluene were added as dehydrating agent and azeotropic agent, respectively. The temperature was raised to 190 °C and the reaction was carried out for 3 hours. Subsequent washing was performed using DMAc and acetone, and the powder was obtained after drying and sieving.

[0032] ② Synthesis of A+B structure resin powder: 90 g of the above component A powder was dispersed in 600 g of DMAc. 40 g of acetic anhydride was added as a dehydrating agent. 2.88 g (0.01 mol) of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB) was added as diamine A2. 4.44 g (0.01 mol) of 4,4'-(hexafluoroisopropylidene) phthalic anhydride (6FDA) was added in batches as dianhydride H2. The mixture was heated to 160 °C and reacted for 6 hours. Subsequent treatment was the same as in Example 1. The mass ratio of component A to component B in the final product was 90:10.

[0033] Example 3 This example provides a highly ductile polyimide molding powder, the preparation method of which includes the following steps: ① Synthesis of component A resin powder: A mixture of 4,4'-diaminodiphenyl sulfone (DDS, 24.8 g, 0.1 mol) and 4,4'-diaminodiphenyl ether (ODA, 20.0 g, 0.1 mol) was used as diamine A1. Diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA, 49.6 g, 0.2 mol) was used as dianhydride H1. The operation procedure was the same as in Example 1. After controlling the reaction viscosity to approximately 80,000 cP, dehydration and cyclization were carried out. The temperature was raised to 170°C and the reaction was carried out for 5 hours. After washing and drying, component A powder was obtained.

[0034] ② Synthesis of A+B structure resin powder: 70 g of the above component A powder was dispersed in 550 g of NMP. 60 g of acetic anhydride was added. 18.32 g (0.04 mol) of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) was added as diamine A2. 12.88 g (0.04 mol) of biphenyltetracarboxylic dianhydride (BPDA) was added in batches as dianhydride H2. The temperature was raised to 130 °C and reacted for 6 hours. Subsequent treatment was the same as in Example 1. The mass ratio of component A to component B in the final product was 70:30.

[0035] Comparative Example 1 This example provides a polyimide plastic, the preparation method of which includes the following steps: In a 1L three-necked flask equipped with a mechanical stirrer and nitrogen protection, add 450 g of DMAc. Weigh 40.0 g (0.2 mol) of 4,4'-diaminodiphenyl ether (ODA) and add it to the solvent, stirring until completely dissolved, maintaining the temperature at 30°C. Add 43.6 g (0.2 mol) of pyromellitic dianhydride (PMDA) in 6 batches, strictly controlling the amount added each time and stirring thoroughly to ensure a uniform reaction. Continue the reaction until the viscosity of the polyamic acid solution reaches approximately 60,000 cP. Add 150 g of acetic anhydride and 80 mL of xylene to the solution. Program the temperature of the reaction system to 185°C at a rate of 1.5°C / min, and stir the reaction at this temperature for 4 hours, precipitating a yellow powder. After the reaction is complete, cool, filter, and wash repeatedly with acetone to remove all impurities and solvent. The filter cake was dried in a vacuum oven at 130°C for 10 hours, then mechanically pulverized and passed through a 400-mesh sieve to obtain a yellow polyimide homopolymer molding powder with a wide particle size distribution.

[0036] Test case In this example, the polyimide powders obtained in Examples 1-3 and Comparative Example 1 were subjected to molding process performance tests and slab performance tests under the same process conditions. The test results are shown in Table 1 (Note: "√" in Table 1 indicates that the molded slab is intact, without cracks or missing corners; "×" indicates that the molded slab is broken, cracked, or missing corners) and Table 2.

[0037] Table 1. Test results of molding process Table 2 Slab performance test results As shown in Tables 1 and 2, the polyimide powder prepared by the method of the present invention exhibits better molding process performance and slab performance. Furthermore, the infrared spectra of the polyimide molding powders obtained in Examples 1-3 and Comparative Example 1 are as follows: Figure 2 As shown.

[0038] 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.

[0039] 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 method for preparing a high-plasticity polyimide molding powder, characterized in that, Includes the following steps: Under an inert gas atmosphere, diamine monomer A1 and dianhydride monomer H1 are added to a first solvent for a first stirring reaction to obtain a resin solution with a viscosity of 5 W to 100 W cp; then a dehydrating agent is added to the resin solution for a second stirring reaction, followed by filtration, washing and drying to obtain polyimide resin powder A; Under an inert gas atmosphere, the polyimide resin powder A and the dehydrating agent are added to the second solvent, followed by the addition of diamine monomer A2 and dianhydride monomer H2 for a third stirring reaction. After filtration, washing and drying, a high-plasticity polyimide molding powder containing polyimide resin powder A and polyimide resin powder B is obtained. The polyimide resin powder A and the polyimide resin powder B are of different types.

2. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The physicochemical properties of the polyimide resin powder A and the polyimide resin powder B satisfy the following relationship: The rigidity of the polyimide resin powder A is greater than that of the polyimide resin powder B; And / or, the plasticity of the polyimide resin powder A is less than the plasticity of the polyimide resin powder B.

3. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The diamine monomer A1 includes at least one of p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl sulfone; The dianhydride monomer H1 is at least one of pyromellitic dianhydride, biphenyl dianhydride, diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, and 3,4,9,10-perylenetetracarboxylic dianhydride.

4. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The total mass of the diamine monomer A1 and the dianhydride monomer H1 accounts for 5-10% of the total solution mass. The amount of dehydrating agent added is 0.5 to 2 times the sum of the masses of the diamine monomer A1 and the dianhydride monomer H1.

5. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The diamine monomer A2 includes at least one of p-phenylenediamine, m-phenylenediamine, and 4,4'-diaminodiphenyl ether; The dianhydride monomer H2 includes at least one of 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride and bisphenol A type diether dianhydride; Alternatively, the diamine monomer A2 comprises at least one of 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 4,4'-diaminodiphenylmethane, 4,4'-diamino-2,2'-bistrifluoromethylbiphenyl, and 4,4'-bis(3-aminophenoxy)diphenyl sulfone; The dianhydride monomer H2 includes at least one of biphenyltetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, 4,4'-biphenyl ether dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride, and bisphenol A type diether dianhydride.

6. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The dehydrating agent includes at least one of toluene, xylene, dichloroethane, acetic anhydride, and propionic anhydride.

7. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The particle size of the polyimide resin powder A is 5-15 micrometers.

8. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The mass ratio of the polyimide resin powder A to the polyimide resin powder B is (60~95):(5~40). The molar ratio of the diamine monomer A1 to the dianhydride monomer H1 is (0.9~1.1):(0.9~1.1). The molar ratio of the diamine monomer A2 to the dianhydride monomer H2 is (0.9~1.1):(0.9~1.1).

9. The method for preparing the high-plasticity polyimide molding powder according to claim 1, characterized in that, The operating conditions for both the second and third stirring reactions include: a temperature of 130~190℃ and a time of 2~6h.

10. A high-plasticity polyimide molding powder, characterized in that, It is prepared by the method of any one of claims 1 to 9 for the preparation of high-plasticity polyimide molding powder; The highly ductile polyimide molding powder has a core-shell structure, wherein the polyimide resin powder A is the core and the polyimide resin powder B is the outer shell.

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