Polyimide composite powder containing silane agent and its preparation method

Abstract

This invention relates to polyimide composite powders containing silane agents and methods for preparing the same. More specifically, the method for preparing the polyimide composite powder includes: step a), preparing polyamic acid by means of dianhydrides and diamines; and step b), imidizing the polyamic acid prepared in step a) by adding a silane agent. This invention uses a silane agent in a specific ratio and employs aqueous polymerization, thereby improving flowability and dispersibility without reducing mechanical properties.

Description

Technical Field

[0001] This invention relates to a method for preparing polyimide composite powder containing silane agents, and more specifically, to a polyimide composite powder and a method for preparing the same, wherein the polyimide composite powder is prepared by mixing silane agents in a specific ratio and then polymerizing them in an aqueous system, thereby imparting flowability and dispersibility without reducing mechanical properties. Background Technology

[0002] Polymer molding involves the physical processing of materials such as plastics and rubber to create molded products. It includes a series of steps, including shaping the polymer material into a specified shape by applying heat and pressure, and shaping it in a liquid state without heat or pressure. Polymer molding processes are classified by steps as primary molding (spraying, extrusion, blow molding, etc.) and secondary molding (thermoforming, bonding, etc.), and by methods as compression molding, calendering, spray molding, vacuum molding, blow molding, foam molding, and fiber spinning. Polymer molding requires products of a specified quality to be price-competitive. Even with the properties of a polymer, the heat and pressure conditions during molding cause various changes, making it difficult to directly manufacture molded products with the desired properties.

[0003] Polyimide generally refers to a high-heat-resistant polymer prepared by imidization after polycondensation of a tetracarboxylic acid or its derivative with an aromatic diamine or aromatic diisocyanate. Furthermore, polyimide possesses the properties of being insoluble in solvents and infusible upon heating, and can have various molecular structures depending on the type of monomer used. Typically, pyromellitic dianhydride (PMDA) or biphenyl dianhydride (BPDA) is used as the aromatic tetracarboxylic acid derivative component, and diaminodiphenyl ether (ODA) or p-phenylenediamine (p-PDA) is used as the aromatic diamine component, thereby preparing the polyimide through polycondensation.

[0004] Due to its high heat resistance and strength, polyimide has been the subject of much research in the automotive, aerospace, electrical, and electronic components industries. Polyimide is insoluble and infusible due to the repeated imide rings within its unit, and therefore is typically processed in the polyamic acid precursor state. Since the introduction of fully aromatic polyimide resins by DuPont in 1962, polyimides modified or improved in terms of heat resistance, alkali resistance, dimensional stability, and low absorption have been disclosed, such as polyamideimide and polyetherimide.

[0005] Polyimide resins can be prepared using relatively simple methods such as mechanical stirring and thermal imidization of polyimide monomers. However, in the molding process for preparing polyimide molded articles, the poor moldability and processability of polyimide resins make it difficult to produce molded articles using ordinary polymer processing equipment. As an effort to overcome these limitations, attempts have been made to prepare molded articles using polyimide powder.

[0006] Polyimide powder differs in morphology from polyimide resin, making it difficult to employ conventional molding methods such as heating and melting. Furthermore, the preparation of molded products from powder is influenced by various factors, including the powder's specific surface area, degree of imidization, degree of crystallinity, molecular weight, and particle size, requiring careful coordination of these conditions. Therefore, while molding products from polyimide resin is commonly used, separate research is needed on the preparation of molded products from polyimide powder.

[0007] Relatedly, U.S. Patent No. 9,469,048 discloses polyimide powder and polyimide molded articles prepared by mixing a mixture of 3,3′,4,4′-biphenyltetracarboxylic dianhydride and pyromellitic dianhydride with a mixture of p-phenylenediamine, m-phenylenediamine, and 4,4'-diaminodiphenyl ether. U.S. Patent No. 7,758,781 discloses polyimide microparticles formed by the polymerization of aliphatic diamines and tetracarboxylic acids, and molded articles prepared by dry mixing and compression molding thereof. Furthermore, Korean Patent No. 1,987,511 discloses a semi-crystalline, semi-aromatic thermoplastic polyimide powder prepared by aliphatic diamines and aromatic tetracarboxylic acids.

[0008] However, even with these efforts, polyimide powder is difficult to use as a material component due to its low dielectric properties. Its low dispersibility makes it difficult to mold and process, and the mechanical properties deteriorate during the process of solving molding and processing problems. These problems still exist.

[0009] Therefore, the inventors incorporated a silane agent into the preparation process of polyimide powder to prepare polyimide composite powder, which proved to have excellent mechanical strength and improved flowability and dispersibility, thus completing the present invention. Summary of the Invention

[0010] Technical issues

[0011] The purpose of this invention is to solve the problem that existing polyimide powders are difficult to mold due to low dispersibility and flowability, and to solve the problem that the dispersibility or mechanical properties cannot be improved when other fillers are used to improve this.

[0012] Technical solution

[0013] The present invention provides a polyimide composite powder comprising polyimide powder and a silane agent, wherein the content of the silane agent is greater than 0.1% by weight relative to the total weight.

[0014] According to one embodiment of the present invention, the content of the silane agent may be greater than 0.1% by weight and less than 20% by weight relative to the total weight.

[0015] According to one embodiment of the present invention, the content of the silane agent may be from 1% to 10% by weight relative to the total weight.

[0016] According to an embodiment of the present invention, the silane agent described above may be one or more selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, and 3-glycidyl etheroxypropylmethylethoxysilane.

[0017] According to a specific example of the present invention, the silane agent can be 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

[0018] Furthermore, the present invention provides a method for preparing polyimide composite powder, comprising: step a), preparing polyamic acid by containing dianhydride and diamine; and step b), imidizing the polyamic acid prepared by adding a silane agent.

[0019] Furthermore, the present invention provides a polyimide molded article prepared by including the step of sintering the above-mentioned polyimide composite powder.

[0020] According to an example of the present invention, the present invention is characterized in that, in step a) above, distilled water is used as a solvent to prepare polyamic acid.

[0021] According to an example of the present invention, in step a) above, the mixture can be stirred for 5 minutes to 4 hours at a temperature of 0°C to 150°C and a pressure of 0.1 bar to 10 bar.

[0022] According to an example of the present invention, in step a) above, the dianhydride may be a dianhydride represented by the following chemical formula 1.

[0023] Chemical Formula 1:

[0024]

[0025] In the above chemical formula 1, R1 is selected from the group consisting of the following chemical structures:

[0026]

[0027]

[0028] as well as

[0029]

[0030] According to an example of the present invention, in step a) above, the diamine may be a diamine represented by the following chemical formula 2.

[0031] Chemical formula 2:

[0032]

[0033] In the above chemical formula 2, R2 is selected from the group consisting of the following chemical structures:

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] as well as

[0041] According to an example of the present invention, in step b) above, the silane agent can be in liquid state.

[0042] According to an embodiment of the present invention, in step b) above, the silane agent may be one or more selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, and 3-glycidyl etheroxypropylmethylethoxysilane.

[0043] According to a specific example of the present invention, in step b) above, the silane agent can be 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

[0044] According to an embodiment of the present invention, in step b) above, the content of silane agent may be greater than 0.1% by weight and less than 20% by weight relative to the total weight of polyamic acid and silane agent.

[0045] According to a specific example of the present invention, in step b) above, the content of silane agent can be from 1% to 10% by weight relative to the total weight of polyamic acid and silane agent.

[0046] According to an example of the present invention, in step b) above, imidization can be carried out by stirring for 5 minutes to 10 hours at a temperature of 150°C to 400°C and a pressure of 10 bar to 300 bar.

[0047] According to an example of the present invention, the present invention provides a polyimide composite powder prepared by the above preparation method, wherein the polyimide composite powder can be used to prepare a molded article by a step including sintering at a temperature of 100°C to 550°C for 1 hour to 5 hours.

[0048] According to one embodiment of the present invention, the present invention is characterized in that the angle of repose of the above-mentioned polyimide composite powder is less than 40°.

[0049] According to one embodiment of the present invention, the present invention is characterized in that the above-mentioned polyimide composite powder can be used to prepare molded articles with a tensile strength of 50 MPa or more.

[0050] The effects of the invention

[0051] The polyimide composite powder and its preparation method of the present invention have the advantages of improving the dispersibility of polyimide powder and maintaining excellent mechanical properties, which are different from existing fillers, by using silane agents. Detailed Implementation

[0052] Best way to carry out the invention

[0053] This invention relates to a polyimide composite powder comprising polyimide powder and a silane agent, wherein the content of the silane agent is from 1% to 10% by weight relative to the total weight.

[0054] Methods of implementing the present invention

[0055] The present invention will now be described in detail.

[0056] This invention relates to a polyimide composite powder comprising polyimide powder and a silane agent, wherein the content of the silane agent is greater than 0.1% by weight relative to the total weight.

[0057] Furthermore, the present invention relates to a method for preparing a polyimide composite powder, comprising: step a), preparing polyamic acid by containing dianhydride and diamine; and step b), imidizing the polyamic acid prepared by adding a silane agent.

[0058] Furthermore, the present invention relates to polyimide molded articles prepared by including the step of sintering the above-mentioned polyimide composite powder.

[0059] In this invention, silane agents refer to all kinds of silane compounds that can form an interface with the polyimide molecular structure of the polyimide powder through chemical or non-chemical bonds. In this invention, the method of obtaining silane agents is not limited.

[0060] According to one embodiment of the present invention, the content of the silane agent may be greater than 0.1% by weight and less than 20% by weight relative to the total weight.

[0061] Specifically, relative to the total weight, the content of the silane agent can be from 0.2 to 18% by weight, 0.3 to 17% by weight, 0.4 to 16% by weight, 0.5 to 15% by weight, 0.6 to 14% by weight, 0.7 to 13% by weight, 0.75 to 12.5% ​​by weight, 0.8 to 12% by weight, 0.85 to 11.5% by weight, 0.9 to 11% by weight, 0.95 to 10.5% by weight, or 1 to 10% by weight.

[0062] In this invention, if the weight percentage of the silane agent is less than the above range, the angle of repose of the polyimide composite powder is greater than 40°, the flowability will not be improved, and the molding problem will still exist. If it is greater than the above range, the aggregation between the silane agent and the polyimide will lead to non-dispersion and the formation of precipitates, which will result in a significant decrease in the tensile strength of the molded product due to the deformation of the molecular structure.

[0063] According to one embodiment of the present invention, the silane agent described above may be in liquid form.

[0064] According to an embodiment of the present invention, the silane agent is one or more selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-glycidyletheroxypropyltriethoxysilane, and 3-glycidyloxypropylmethylethoxysilane. More than one silane agent may be used, or two or more may be mixed in a prescribed ratio for use.

[0065] According to a specific example of the present invention, the silane agent is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

[0066] According to one embodiment of the present invention, the polyimide composite powder can be a fully aromatic polyimide, a partially alicyclic polyimide, or a fully alicyclic polyimide. However, the polyimide composite powder prepared by the preparation method according to the present invention has the excellent effect of maintaining flowability and dispersibility while retaining mechanical properties even when it is a fully aromatic polyimide.

[0067] According to one embodiment of the present invention, the above-mentioned polyimide composite powder can be used to prepare a molded article by a step including sintering at a temperature of 100°C to 550°C for 1 to 5 hours.

[0068] According to one embodiment of the present invention, the present invention is characterized in that the angle of repose of the above-mentioned polyimide composite powder is less than 40°.

[0069] Furthermore, according to one embodiment of the present invention, the polyimide composite powder described above can be used to prepare molded articles with a tensile strength of 50 MPa or more. According to a specific embodiment of the present invention, the polyimide composite powder described above can be used to prepare molded articles with a tensile strength of 60 MPa or more.

[0070] According to an embodiment of the present invention, the invention is characterized in that, in step a), distilled water is used as a solvent to prepare polyamic acid. In this invention, using distilled water as a solvent facilitates the dissolution of the silane agent, and no waste solvent is generated after the preparation of the polyimide composite powder; therefore, no reduction in mechanical properties occurs after removing the residual solvent.

[0071] In this invention, the term "distilled water" does not simply mean distilled water in the literal sense; it can also refer to water in any state, such as deionized water or tap water. Furthermore, the amount of distilled water can be appropriately adjusted according to the amounts of dianhydride and diamine.

[0072] According to an embodiment of the present invention, in step a) above, using the dianhydride compound as a reference, 100 parts by weight of the dianhydride compound, 80 to 120 parts by weight of the diamine, and 1000 to 1200 parts by weight of the mixed solvent can be used to prepare polyamic acid. Distilled water can be used as a solvent within the corresponding part-by-part range to form the monomer salt.

[0073] According to an example of the present invention, in step a) above, the mixture can be stirred for 5 minutes to 4 hours at a temperature of 0°C to 150°C and a pressure of 0.1 bar to 10 bar.

[0074] Specifically, in step a) above, the temperature can be 30°C to 130°C, 50°C to 120°C, or 60°C to 100°C. Furthermore, in step a) above, the pressure can be 0.2 bar to 8 bar, 0.3 bar to 6 bar, or 0.5 bar to 5 bar. Furthermore, in step a) above, the time can be 10 minutes to 3.5 hours or 30 minutes to 3 hours. Since imidization does not directly occur under the above temperature, pressure, and time conditions, polyamate can be prepared.

[0075] According to an example of the present invention, in step a) above, the dianhydride may be a dianhydride represented by the following chemical formula 1.

[0076] Chemical Formula 1:

[0077]

[0078] In the above chemical formula 1, R1 is selected from the group consisting of the following chemical structures:

[0079]

[0080]

[0081] as well as

[0082]

[0083] According to an example of the present invention, in step a) above, the diamine may be a diamine represented by the following chemical formula 2.

[0084] Chemical formula 2:

[0085]

[0086] In the above chemical formula 2, R2 is selected from the group consisting of the following chemical structures:

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093] as well as

[0094] According to an example of the present invention, in step b) above, the silane agent can be in liquid state.

[0095] According to an embodiment of the present invention, in step b) above, the silane agent is one or more selected from the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-glycidyletheroxypropyltriethoxysilane, and 3-glycidyloxypropylmethylethoxysilane. More than one silane agent may be used, or two or more may be mixed in a prescribed ratio for use.

[0096] According to a specific example of the present invention, in step b) above, the silane agent is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

[0097] Furthermore, according to an embodiment of the present invention, in step b) above, the content of silane agent may be greater than 0.1% by weight and less than 20% by weight relative to the total weight of polyamic acid and silane agent.

[0098] Specifically, relative to the total weight of polyamic acid and silane agent, the content of the silane agent is 0.2 to 18 wt%, 0.3 to 17 wt%, 0.4 to 16 wt%, 0.5 to 15 wt%, 0.6 to 14 wt%, 0.7 to 13 wt%, 0.75 to 12.5 wt%, 0.8 to 12 wt%, 0.85 to 11.5 wt%, 0.9 to 11 wt%, 0.95 to 10.5 wt%, and 1 to 10 wt%.

[0099] In this invention, a silane agent can be added in the polyamic acid salt state to modify the polymer structure. Furthermore, the silane agent can be maintained in a specified proportion during the preparation of the polyimide composite powder to achieve excellent properties in terms of angle of repose, dispersibility, and mechanical properties.

[0100] According to an example of the present invention, in step b) above, imidization may be carried out by stirring for 5 minutes to 10 hours at a temperature of 150°C to 400°C and a pressure of 10 bar to 300 bar.

[0101] Specifically, in step b) above, the temperature can be 160°C to 250°C, 170°C to 240°C, or 180°C to 220°C. If the reaction temperature is less than 150°C, the reaction rate will be too low; if the reaction temperature is greater than 400°C, thermal decomposition of monomers or polymers may occur.

[0102] Furthermore, in step b) above, the pressure can be from 10 bar to 300 bar, from 10 bar to 100 bar, or from 10 bar to 80 bar. If the reaction pressure is less than 10 bar, it is difficult to control the reactivity; if the reaction pressure is greater than 300 bar, it is difficult to obtain high molecular weight polyimide composite powder.

[0103] Furthermore, in step b) above, the reaction time can be from 10 minutes to 10 hours or from 10 minutes to 5 hours. If the reaction time is less than 5 minutes, the reaction will not be very good; if the reaction time is greater than 10 hours, hydrolysis of the polymer may occur.

[0104] Furthermore, in this invention, a filtration and drying step may be included after step b) above to prepare the polyimide composite powder.

[0105] According to an embodiment of the present invention, the polyimide composite powder prepared can be used to prepare molded articles by compression molding, spray molding, slush molding, blow molding, extrusion molding or spinning methods, including the sintering step described above.

[0106] Furthermore, the polyimide composite powder prepared according to an embodiment of the present invention improves formability and tensile strength, thereby enabling its application in various industrial fields such as aerospace, aviation, electrical / electronics, semiconductors, transparent / flexible displays, liquid crystal backsheets, automobiles, precision equipment, packaging, medical materials, separation membranes, fuel cells, and secondary batteries.

[0107] The following examples illustrate the preparation method of the polyimide composite powder of the present invention and the physical properties of the polyimide composite powder prepared by the method. However, the present invention is not limited to the following examples.

[0108] <Example 1> Preparation of polyimide composite powder containing silane agent

[0109] After metering 255 g of distilled water into a 5-necked beaker-type reaction vessel, 23.46 g of pyromellitic dianhydride (PMDA) was added and dissolved using a high-speed stirrer to convert it into a tetracarboxylic acid form (70 °C, 1 h). Then, 21.54 g of 4,4′-diaminodiphenyl ether (4,4′-oxydianiline (ODA)) was added, and the reaction was carried out at 70 °C for 2 h to synthesize the monomer salt. Under these conditions, the monomer salt concentration was 15% by weight, and the solid content was ~15% by weight.

[0110] 0.45 g of powdered aminopropyltriethoxysilane was added to the mixture of the formed monomer salts. The high-temperature, high-pressure reactor was set to a pressure of 12-15 bar and stirred at 190°C for 6 hours. Afterwards, the polyimide composite powder suspension was washed with distilled water and filtered under reduced pressure to obtain the polyimide composite powder.

[0111] <Example 2> Preparation of polyimide composite powder containing silane agent

[0112] Except for the use of 2.37g of silane agent, polyimide composite powder was prepared in the same manner as in Example 1 above.

[0113] <Example 3> Preparation of polyimide composite powder containing silane agent

[0114] Except for the use of 5.00 g of silane agent, polyimide composite powder was prepared in the same manner as in Example 1 above.

[0115] <Comparative Example 1> Preparation of Polyimide Powder

[0116] Polyimide powder was prepared in the same manner as in Example 1 above, without the presence of silane agents.

[0117] <Comparative Example 2> Preparation of polyimide composite powders with different silane content.

[0118] Except for the use of 0.045g of silane agent, polyimide composite powder was prepared in the same manner as in Example 1 above.

[0119] <Comparative Example 3> Preparation of polyimide composite powders with different silane agent contents

[0120] Except for the use of 11.25g of silane agent, polyimide composite powder was prepared in the same manner as in Example 1 above.

[0121] <Evaluation>

[0122] The angle of repose was measured by dropping polyimide composite powder or polyimide powder prepared in Examples 1 to 3 and Comparative Examples 1 to 3 from a predetermined height onto a horizontal substrate using a powder tester (PT-X).

[0123] Furthermore, the dispersibility of the polyimide composite powder or polyimide powder prepared by Examples 1 to 3 and Comparative Examples 1 to 3 was confirmed by placing the powder in water and stirring it with a magnetic stirrer for more than 3 minutes.

[0124] Furthermore, using an ASTM D1708 standard specimen mold, 2g of each of the polyimide composite powder or polyimide powder prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were compressed and molded under a pressure of 96,000 psi. Ten specimens were then prepared by heating and sintering under a nitrogen atmosphere at 100°C for 1 hour, 250°C for 1 hour, and 450°C for 1 hour. The tensile strength of the specimens prepared by the above steps is shown in Table 1. The tensile strength of the specimens was measured using an Instron 5564 UTM according to ASTM D1708 standard.

[0125] Table 1

[0126]

[0127]

[0128] As shown in Table 1, it was confirmed that the polyimide composite powder prepared according to Examples 1 to 3 of the present invention exhibits increased powder flowability due to an angle of repose of less than 40°. Furthermore, it demonstrates excellent dispersibility and a tensile strength of 50 MPa or higher, resulting in almost no decrease in mechanical strength, thus confirming that excellent molded articles can be prepared.

[0129] In Comparative Example 1, which did not contain silane agent, and Comparative Example 2, which contained 0.1% by weight of silane agent, the angle of repose was 40° or more, and the flowability of the powder was not improved. In Comparative Example 3, which contained 20% by weight of silane agent, the angle of repose was less than 40°, but the dispersibility decreased, and precipitates were formed. Since the tensile strength was less than 50 MPa, molded articles with poor mechanical properties were prepared.

[0130] Therefore, the method for preparing polyimide composite powder of the present invention imparts flow properties to the polyimide composite powder by adding a silane agent in the state of a monomer salt as an intermediate step in the preparation of the polyimide composite powder. Furthermore, by adjusting the amount of silane agent added, excellent flowability and dispersibility are achieved while maintaining excellent mechanical strength. Moreover, the preparation process is highly efficient due to the low reaction temperature and short reaction time, and the use of water as a reaction solvent is environmentally friendly, resulting in cost reduction.

[0131] Industrial availability

[0132] This invention provides polyimide composite powders that improve flow properties, maintain mechanical strength, and enhance dispersibility with varying amounts of specific silane agents. Therefore, molded articles can be effectively produced using the powder.

Claims

1. A polyimide composite powder for preparing molded articles, characterized in that, The product contains polyimide powder and a silane agent, wherein the content of the silane agent is 1% to 10% by weight relative to the total weight. The polyimide composite powder has an angle of repose of less than 40°. The polyimide composite powder can be used to prepare molded articles with a tensile strength of 50 MPa or more. The polyimide composite powder is prepared by imidizing polyamic acid prepared from dianhydride and diamine after adding the silane agent.

2. The polyimide composite powder for preparing molded articles according to claim 1, characterized in that, The silane agent mentioned above is in liquid form.

3. The polyimide composite powder for preparing molded articles according to claim 1, characterized in that, The aforementioned silane agent is selected from one or more of the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, and 3-glycidyl etheroxypropylmethylethoxysilane.

4. The polyimide composite powder for preparing molded articles according to claim 1, characterized in that, The aforementioned silane agent is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

5. The polyimide composite powder for preparing molded articles according to claim 1, characterized in that, The above-mentioned polyimide composite powder can be used to prepare molded articles by a step including sintering at a temperature of 100°C to 550°C for 1 to 5 hours.

6. A method for preparing a polyimide composite powder for molding articles, characterized in that, include: Step a) involves preparing polyamic acid by stirring dianhydride and diamine under temperature conditions from 0°C to 150°C and pressure conditions from 0.1 bar to 10 bar. as well as Step b) involves adding a silane agent to the polyamic acid prepared in step a) above, and stirring under conditions of 150°C to 400°C and 10 bar to 300 bar to induce imidization. In step b) above, the content of silane agent is 1% to 10% by weight relative to the total weight, and the angle of repose of the polyimide composite powder is less than 40°.

7. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step a) above, distilled water is used as a solvent to prepare polyamic acid.

8. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step a) above, stir for 5 minutes to 4 hours.

9. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step a) above, the dianhydride is a dianhydride represented by the following chemical formula 1: Chemical Formula 1: ， In the above chemical formula 1, R1 is selected from the group consisting of the following chemical structures: 。 10. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step a) above, the diamine is a diamine represented by the following chemical formula 2: Chemical formula 2: ， In the above chemical formula 2, R2 is selected from the group consisting of the following chemical structures: 。 11. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step b) above, the silane agent is in liquid state.

12. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step b) above, the silane agent is selected from one or more of the group consisting of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-(2-aminoethyl)aminopropyltrimethoxysilane, 3-phenylaminopropyltrimethoxysilane, 2-aminophenyltrimethoxysilane, and 3-aminophenyltrimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-glycidyl etheroxypropyltriethoxysilane, and 3-glycidyl etheroxypropylmethylethoxysilane.

13. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step b) above, the silane agent is 3-aminopropyltrimethoxysilane or 3-aminopropyltriethoxysilane.

14. The method for preparing polyimide composite powder for molding articles according to claim 6, characterized in that, In step b) above, imidization is performed by stirring for 5 minutes to 10 hours.

15. A polyimide molded article, characterized in that, It is prepared by a step including sintering the polyimide composite powder according to any one of claims 1 to 5.

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