High heat-resistant and chemical-resistant polyimide powder using glass fiber powder and method for producing it

Abstract

The present invention relates to a polyimide powder and a method for producing the same. According to the present invention, a diamine monomer and a dianhydride monomer are polymerized using glass fiber powder, thereby providing a highly heat-resistant polyimide powder having excellent chemical resistance while maintaining insulation and ensuring stability at high temperatures of up to 800°C.

Description

[Technical Field]

[0001] This invention relates to a highly heat-resistant and chemically resistant polyimide powder and a method for producing it using glass fiber powder. [Background technology]

[0002] Generally, polyimide (PI) is a polymer of imide monomers formed by solution polymerization of dianhydride and diamine or diisocyanate. Based on the chemical stability of the imide ring, it possesses excellent mechanical properties such as strength, chemical resistance, weather resistance, and heat resistance. In addition, polyimide is attracting attention as a high-performance polymer material applicable to a wide range of industrial fields such as electronics, communications, and optics due to its excellent electrical properties such as insulating properties and low dielectric constant.

[0003] On the other hand, conventional polyimides, as mentioned above, have excellent insulating and heat-resistant properties, but they have the problem of reduced stability at high temperatures of around 800°C. When using ceramic materials among inorganic materials to improve the high-temperature stability of such conventional polyimide powders, there is the problem of difficulty in processing, and when using metallic materials among inorganic materials, there is the problem that they are difficult to use as insulating materials due to their low insulating properties.

[0004] Therefore, there is a need for research into methods for producing highly heat-resistant polyimide powder that can maintain insulating properties while ensuring stability at high temperatures of around 800°C. [Overview of the project] [Problems that the invention aims to solve]

[0005] The present invention aims to solve the problems and technical challenges of the prior art described above.

[0006] The present invention provides a highly heat-resistant polyimide powder that maintains insulation while ensuring stability at high temperatures of around 800°C, and a method for producing the same.

[0007] Furthermore, the present invention provides a chemically resistant polyimide powder that can ensure stability against acids and / or bases, and a method for producing the same. [Means for solving the problem]

[0008] This invention relates to polyimide powder and a method for producing the same.

[0009] The polyimide powder according to the present invention has a dianhydride monomer component and a diamine monomer component as polymerization units.

[0010] Conventional polyimides, as mentioned above, have excellent insulating and heat-resistant properties, but they suffer from a decrease in stability or chemical resistance at high temperatures of around 800°C. When using ceramic materials among inorganic materials to ensure the high-temperature stability of such conventional polyimide powders, there is a problem in that they are difficult to process, and when using metallic materials among inorganic materials, there is a problem in that they are difficult to use as insulating materials due to their low insulating properties.

[0011] The present invention provides a highly heat-resistant and chemically resistant polyimide powder that maintains insulating properties and ensures stability at high temperatures of around 800°C, while also being resistant to acids and alkalis, by polymerizing a dianhydride monomer component and a diamine monomer component together with glass fiber powder.

[0012] A method for producing polyimide powder according to one embodiment of the present invention includes the steps of: producing a polyamic acid solution by solution polymerization of a dianhydride monomer and a diamine monomer in an organic solvent containing glass fibers; producing a polyimide mixture by heating the polyamic acid solution; and obtaining polyimide powder by filtering and drying the precipitate present in the mixture.

[0013] Conventionally, polyimide powder was produced by dispersing dianhydride monomers and diamine monomers in an aqueous solvent to create a dispersion, which was then heat-treated. However, when glass fiber powder is further added to the aqueous solvent to create a dispersion and then heat-treated, as in the conventional method, there was a problem in that the glass fiber powder aggregated in the dispersion, reducing its dispersibility.

[0014] In one embodiment of the present invention, a method for producing polyimide powder involves dispersing a dianhydride monomer, a diamine monomer, and glass fibers in a mixed organic solvent to form a polymerization solution (varnish), which is then heat-treated to produce polyimide powder. Therefore, the dispersibility of the glass fibers may be good.

[0015] In one specific example, the glass fiber is not particularly limited in shape, but can be used in the form of chopped strands or a powder obtained by pulverizing them. With special consideration for dispersibility, the diameter may be 5 μm or more, 7 μm or more, or 9 μm or more, and powders with a diameter of 18 μm or less, 15 μm or less, or 12 μm or less can be used.

[0016] Furthermore, while there are no particular restrictions on the type of glass fiber, glass fibers of a high grade with high acid resistance, base resistance, and electrical resistance can be used.

[0017] The content of the glass fiber contained in the organic solvent may be, for example, 5 to 90 parts by weight, 6 to 70 parts by weight, 7 to 60 parts by weight, 8 to 55 parts by weight, or 10 to 50 parts by weight per 100 parts by weight of the total of the dianhydride monomer and diamine monomer. If the content of glass fiber is too low, it is difficult to ensure stability or chemical resistance at high temperatures of around 800°C, and if the content is too high, mechanical properties such as tensile strength and elongation may decrease.

[0018] The organic solvent of the present invention can be a mixed solvent of an aprotic solvent and a protic solvent. When a mixed solvent is used, it has the advantage of superior moldability and processability compared to when an aprotic solvent or a protic solvent is used alone.

[0019] Although not bound by theory, in the case of an aprotic solvent, it is judged to act as a kind of imidization catalyst, and in the case of a protic solvent, it is judged to play a role in growing the molecular weight.

[0020] The aprotic solvent is not particularly limited, and one or more selected from the group consisting of toluene, xylene, naphtha, anisole, cresol, ethylbenzene, propylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, biphenyl, terphenyl, diphenyl ether, diphenyl sulfide, acetophenone, chlorinated biphenyl and chlorinated diphenyl ether can be used. The protic solvent is not particularly limited, and one or more selected from the group consisting of N-methyl-pyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), 3-methoxy-N,N-dimethylpropanamide (KJCMPA) and γ-butyrolactone (GBL) can be used.

[0021] The mixed solvent can contain 10 to 90 wt% of an aprotic solvent and 10 to 90 wt% of a protic solvent, for example, 20 to 80 wt% of an aprotic solvent and 20 to 80 wt% of a protic solvent. If the content of the aprotic solvent is excessively low, imidization is not sufficiently carried out in the heating step, so that the moldability cannot be ensured and there is a disadvantage that the intrinsic viscosity (IV) becomes low. If the content is excessively high, the molecular weight of the polymerization solution is formed too slowly (the chains are too small), and then there is a disadvantage that the moldability cannot be ensured when forming the molded product.

[0022] The step of producing the polyamic acid solution can be carried out at 50 to 100 °C, for example, 60 to 90 °C, 65 to 85 °C or 70 to 80 °C, and the step of producing the polyimide mixture can be carried out at 160 to 200 °C, for example, 170 to 190 °C or 175 to 185 °C.

[0023] When the heating temperature is lower than the above range, mechanical properties such as elongation and tensile strength may decrease, breakage may occur during the forming process, resulting in a decrease in the yield and a possible reduction in processability. Also, when the heating temperature is higher than the above range, the color of the powder may become darker and the particle size may increase.

[0024] The step of producing the polyamic acid solution and / or the step of producing the polyimide mixture may be carried out under pressurized conditions, for example, under conditions of 1 to 10 bar. In particular, in one embodiment of the present invention, since the dianhydride monomer, the diamine monomer and the glass fiber powder are dispersed in a mixed solvent and polymerized, the polymerization reaction can be carried out under normal pressure or under pressurized conditions of 1 bar to 3 bar or less. Pressurization can be achieved by injecting an inert gas into the reactor or by utilizing the water vapor generated inside the reactor. The inert gas can be nitrogen, argon, helium, neon, or the like.

[0025] When the pressurized conditions are lower than the above range, mechanical properties such as elongation and tensile strength may decrease, breakage may occur during the forming process, resulting in a decrease in the yield and a possible reduction in processability. Also, when the pressurized conditions are higher than the above range, the color of the powder may become darker and the particle size may increase.

[0026] The reaction time for the step of producing the polyamic acid solution and / or the step of producing the polyimide mixture may be from 1 to 20 hours, for example, it may be from 1 to 10 hours, from 1 to 8 hours, from 1 to 6 hours, or from 1 to 4 hours.

[0027] When the reaction time is lower than the above range, the reaction yield may decrease, mechanical properties such as elongation and tensile strength may decrease, breakage may occur during the forming process, resulting in a decrease in the yield and a possible reduction in processability. Also, when the reaction time is higher than the above range, the color of the powder may become darker and the particle size may increase.

[0028] The step of obtaining the polyimide powder is a step of filtering and drying the precipitate present in the mixture to obtain the polyimide powder.

[0029] The filtration and drying method is not particularly limited and can be, for example, vacuum drying or oven drying.

[0030] The dianhydride monomer is not particularly limited as long as it can react with a diamine monomer to form a polyimide. For example, the dianhydride monomer according to the present invention may include at least one selected from the group consisting of pyromellitic acid dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4-biphenyltetracarboxylic acid dianhydride (a-BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA), and p-phenylenebis(trimellitate anhydride) (TAHQ).

[0031] The diamine monomer is not particularly limited as long as it can react with a dianhydride monomer to form a polyimide. For example, the diamine monomer according to the present invention may include at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4-diaminobenzanilide (4,4-DABA), N,N-bis(4-aminophenyl)benzene-1,4-dicarboxamide (BPTPA), 2,2-dimethylbenzidine (M-TOLIDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-bisaminophenoxybenzene (TPE-Q), bisaminophenoxybenzene (TPE-R), 2,2-bisaminophenoxyphenylpropane (BAPP), and 2,2-bisaminophenoxyphenylhexafluoropropane (HFBAPP).

[0032] In this case, the molar ratio (b / a) representing the number of moles of the diamine monomer component (b) to the number of moles of the dianhydride monomer component (a) is 1 or less. For example, the upper limit of the molar ratio (b / a) of the diamine monomer component to the dianhydride monomer component may be 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, or 0.95 or less, and the lower limit of the molar ratio may be 0.9 or more, 0.91 or more, 0.92 or more, 0.93 or more, or 0.94 or more. Specifically, the molar ratio of the diamine monomer component to the dianhydride monomer component may be 0.9 to 0.99, 0.93 to 0.99, 0.94 to 0.99, 0.95 to 0.99, 0.95 to 0.98, or 0.96 to 0.98.

[0033] For example, in the present invention, the number of moles of the diamine monomer component is even smaller than the number of moles of the dianhydride monomer component. Stoichiometrically, polyimide can be produced by a 1:1 reaction of dianhydride monomer and diamine monomer, but the reaction proceeds mainly in the presence of a solvent and / or catalyst, and at this time, side reactions may occur between the working groups of the solvent or catalyst and the diamine, so generally, either an excess amount of diamine is added or dianhydride and diamine are added in equal mole amounts.

[0034] The solid content in the mixed solvent may be 1 to 30% by weight. The solid content may refer to dianhydride monomer components and diamine monomer components. For example, the solid content in the mixed solvent may be 1 to 20% or 10 to 20%. Having such a solid content allows the intrinsic viscosity of the polyimide powder to be adjusted to have suitable processability.

[0035] In particular, the method for producing polyimide powder according to one embodiment of the present invention involves dispersing dianhydride monomer components, diamine monomer components, and glass fiber powder in a mixed solvent to form a polymerization solution (varnish), and then heat-treating this solution to produce polyimide powder. As a result, the intrinsic viscosity of the polyimide powder is even higher than that of conventional aqueous polymerization methods (>0.9 dL / g), resulting in excellent moldability and processability.

[0036] The polyimide powder according to another embodiment of the present invention includes a polyimide matrix having polymerization units derived from a dianhydride monomer and a diamine monomer, and glass fibers dispersed in the polyimide matrix, and satisfies one or more of the following conditions.

[0037] a) The weight loss rate measured after leaving it at 800 °C for 25 hours is 35% or less, and the surface resistance is 10 14 Ω / cm 2 or more; b) The weight loss rate measured after immersion in an acidic aqueous solution with a pH of 5 or less for 168 hours is 2.6% or less; or c) The weight loss rate measured after immersion in an alkaline aqueous solution with a pH of 9 or more for 168 hours is 15% or less.

[0038] The glass fiber powder can be included in a content of 0.01 to 90 parts by weight, preferably 0.1 to 50 parts by weight, based on 100 parts by weight of the polyimide powder. The glass fiber powder may be included during the polymerization of the polyimide powder or may be additionally mixed into the polyimide powder.

[0039] The polyimide powder may have a weight loss rate measured after leaving it at 800 °C for 25 hours of 35% or less, for example, 34% or less, 33% or less, 10 to 35%, 15 to 34% or 18% to 32%. If the weight loss rate is 35% or more, the high-temperature heat resistance may be insufficient.

[0040] The polyimide powder may have a surface resistance measured by ASTM D257 of 10 14 Ω / cm 2 or more. For example, the lower limit of the surface resistance of the polyimide powder according to the present invention measured by ASTM D257 may be 10 14 Ω / cm 2 or more, and the upper limit of the surface resistance may be 10 15 Ω / cm 2 or less. If the surface resistance is less than 10 14 Ω / cm 2 the insulating properties may be insufficient.

[0041] The polyimide powder may have a weight loss rate of 2.6% or less, for example, 2.5% or less, 0.5-2.6%, or 1-2.5%, measured after immersion in an acidic aqueous solution with a pH of 5 or less for 168 hours. The acidic aqueous solution with a pH of 5 or less is not particularly limited, but for example, a 45-55 wt% hydrofluoric acid aqueous solution can be used. The measurement temperature or pressure is not particularly limited, but measurements can be taken at room temperature or atmospheric pressure.

[0042] The polyimide powder may have a weight loss rate of 15% or less, for example, 13% or less, 1-11%, or 2-10%, after being immersed in an alkaline aqueous solution with a pH of 9 or higher for 168 hours. The alkaline aqueous solution with a pH of 9 or higher is not particularly limited, but for example, a 20-30 wt% ammonia aqueous solution can be used. The measurement temperature or pressure is not particularly limited, but measurements can be taken at room temperature or atmospheric pressure.

[0043] The dianhydride monomer of the polyimide powder may include at least one selected from the group consisting of pyromellitic acid dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4-biphenyltetracarboxylic acid dianhydride (a-BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA), and p-phenylenebis(trimellitate anhydride) (TAHQ).

[0044] The diamine monomer of the polyimide powder may include at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4-diaminobenzanilide (4,4-DABA), N,N-bis(4-aminophenyl)benzene-1,4-dicarboxamide (BPTPA), 2,2-dimethylbenzidine (M-TOLIDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-bisaminophenoxybenzene (TPE-Q), bisaminophenoxybenzene (TPE-R), 2,2-bisaminophenoxyphenylpropane (BAPP), and 2,2-bisaminophenoxyphenylhexafluoropropane (HFBAPP).

[0045] Furthermore, the present invention provides a method for producing a polyimide molded article, which includes the step of pressure molding the polyimide powder described above.

[0046] The pressure molding step may be carried out at a pressure of 30 to 1000 MPa, and the pressure molding step may be carried out at a temperature of 200 to 500°C. The pressure molding step may also include an additional step of sintering the polyimide powder, which has been pressure molded at room temperature, at a temperature of 200 to 500°C. If the pressure is lower than the aforementioned range, the moldability of the powder may be insufficient during molding, and if it is higher, the processability of the molded product may decrease. If the temperature is lower than the aforementioned range, the moldability may be greatly reduced because the fluidity of the molecules cannot be ensured, and if it is higher, some of the material may be oxidized due to overheating.

[0047] Furthermore, the present invention provides molded articles manufactured using polyimide powder. The polyimide powder manufactured according to the present invention can be manufactured into molded articles by various molding methods, for example, by compression molding, injection molding, slush molding, hollow molding, extrusion molding, or spinning methods to produce the required molded articles. The form of the molded article is not limited, but may be a film, sheet, pellet, tube, belt, injection molded article, or extruded article.

[0048] The polyimide powder produced by this invention can be used in a variety of fields, including electrical / electronics, semiconductors, displays, automobiles, medical equipment, batteries, and aerospace. [Effects of the Invention]

[0049] According to this application, it is possible to manufacture a highly heat-resistant polyimide powder that maintains insulating properties while ensuring stability at high temperatures of around 800°C.

[0050] The polyimide powder described in this application has a reference surface resistance of 10 for molded articles. 14 Ω / cm 2 Since it can be increased to this level, it is possible to maintain insulation properties.

[0051] Furthermore, the polyimide powder according to this application, by containing glass fiber powder as a filler, maintains its insulating properties and ensures stability at high temperatures of around 800°C, unlike other fillers.

[0052] Furthermore, the polyimide powder according to this application exhibits superior chemical resistance compared to conventional polyimide powders, with a mass change rate of 1.0% to 2.6% when immersed in hydrofluoric acid solution and a mass change rate of 2.0% to 10.0% when immersed in ammonia water.

[0053] However, the effects of the present invention are not limited to those mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the following description. [Modes for carrying out the invention]

[0054] The present invention will be described in more detail below through examples and comparative examples that do not conform to the present invention, but the scope of the present invention is not limited to the examples presented below. [Examples]

[0055] <Example 1> A polyamic acid solution was prepared by sequentially adding 900g of a mixed solvent of 30wt% m-xylene and 70wt% NMP (N-methylpyrrolidone), 46g of ODA, 10g of glass fiber powder, 40g of PMDA, and 14g of ODPA to a glass reactor and stirring at 75°C for 2 hours. The completed polyamic acid solution was heated at 180°C under atmospheric pressure for 2 hours to prepare a polyimide mixture. The powder precipitated in the mixture was filtered and washed with ethanol, then dried for 24 hours to produce polyimide powder. The produced powder was pressure-molded at >50 MPa and >300°C to produce molded products.

[0056] <Example 2> The molded product was manufactured in the same manner as in Example 1, except that 15 g of glass fiber powder was used.

[0057] <Example 3> The molded product was manufactured in the same manner as in Example 1, except that 20g of glass fiber powder was used.

[0058] <Example 4> The molded product was manufactured in the same manner as in Example 1, except that 30g of glass fiber powder was used.

[0059] <Example 5> The molded product was manufactured in the same manner as in Example 1, except that 40g of glass fiber powder was used.

[0060] <Example 6> The molded product was manufactured in the same manner as in Example 1, except that 50g of glass fiber powder was used.

[0061] <Comparative Examples 1-5> As shown in Table 1 below, polyimide powder was produced using the same method as in Example 1, except that the filler components were different.

[0062] Specifically, Comparative Example 1 is the case where no filler is added, while Comparative Examples 2 to 5 are the cases where various conventionally used fillers are added.

[0063] <Example of experiment> The physical properties of the manufactured polyimide powder were measured using the following method, and the results are shown in Table 1 below.

[0064] Experimental Example 1 - Measurement of Weight Loss Rate To analyze the weight loss rate, compression-molded polyimide powder specimens (5mm*5mm*5mm hexahedron shape) were used, and the weight loss rate (%) at 800°C was measured using a thermogravimetric analyzer (TGA). Specifically, the weight loss rates were compared after leaving the specimens at 800°C for 25 hours under an air pressure of 0.61 MPa.

[0065] % weight loss = (initial weight - weight after exposure) / initial weight x 100

[0066] Experimental Example 2 - Measurement of Surface Resistance To measure surface resistance, compression-molded polyimide powder specimens were used, and the surface resistance of the examples and comparative examples was measured according to the ASTM-D257 standard. Specifically, surface resistance was measured under the ASTM-D257 measurement method at 55% RH, 23°C, and an applied voltage of 500V, using a 4-point probe meter (CMT-SR 1000N, AIT).

[0067] [Table 1]

[0068] Referring to Table 1, in Examples 2, 4, 5, and 6, which further include glass fiber powder as a polyimide powder having dianhydride monomer components and diamine monomer components as polymerization units as in the present invention, the surface resistance is 10 14 Ω / cm 2As described above, the weight loss rate (%) at 800°C is 18.1% to 31.5%, indicating that insulation properties can be maintained while ensuring stability at high temperatures of 800°C. In particular, in the case of Example 6, where the glass fiber powder content is 50 wt%, the weight loss rate (%) at 800°C is 18.1%, indicating excellent high heat resistance properties. Thus, in the cases of Examples 2, 4, 5 and 6 of the present invention, the molded product standard is 10 14 Ω / cm 2 In conclusion, it is possible to reduce the weight loss rate (%) at 800°C, thereby maintaining insulation properties while ensuring stability at high temperatures of 800°C.

[0069] On the other hand, when no filler is added (Comparative Example 1) and when conventional fillers are added (Comparative Examples 2-5), it can be seen that there is a problem of low surface resistance and low insulation performance, or that the 800°C weight loss rate (%) increases and high-temperature stability decreases.

[0070] Furthermore, the method for producing polyimide powder according to this application involves mixing glass fibers during in-situ polymerization, resulting in excellent dispersibility of the polyimide powder. The glass fibers also act as seeds, enabling the production of a more uniform powder.

[0071] Furthermore, the polyimide powder according to this application contains aromatic chains and further contains glass fiber powder as a filler, which may result in superior heat resistance compared to conventional polyimide powders.

[0072] Experimental Example 2 - Measurement of Chemical Resistance (Weight Loss Rate) For chemical resistance analysis, polyimide molded products were processed into 5mm*5mm*5mm cubic test specimens. The cubic test specimens were immersed in a 49% hydrofluoric acid solution for 168 hours. Changes in appearance and weight loss after immersion were measured.

[0073] Using the same method, cubic specimens were immersed in 25-28% ammonia water for 168 hours, and the changes in appearance and weight loss rate before and after immersion were measured.

[0074] [Table 2]

[0075] Referring to Table 2 above, in Examples 1, 3, 4, and 6, which include glass fiber powder dispersed in polyimidemetrics having polymerization units derived from dianhydride monomers and diamine monomers as in the present invention, the weight loss rate measured when immersed in hydrofluoric acid solution was 1.0% to 2.6%, and the weight loss rate measured when immersed in aqueous ammonia solution was 2.0% to 10.0%, indicating excellent chemical resistance.

[0076] On the other hand, when no filler was added (Comparative Example 1), the weight loss rate measured during immersion in hydrofluoric acid solution and ammonia water was high, indicating low chemical resistance.

[0077] Table 3 below shows experimental results comparing the intrinsic viscosity (IV), moldability, and processability of examples using a mixed solvent of an aprotic solvent and a protic solvent according to one embodiment of the present invention, and comparative examples using either an aprotic solvent alone or a protic solvent alone.

[0078] Specifically, Comparative Example 6 is the case where m-cresol is used alone, and Comparative Example 7 is the case where NMP is used alone, except that it is the same as Example 1. Furthermore, Example 7 is the case of a 50 / 50 wt% mixture of m-cresol / NMP, Example 8 is the case of a 30 / 70 wt% mixture of m-cresol / NMP, and Example 9 is the case where a 70 / 30 wt% mixture of m-cresol / NMP is the same as Example 1, except that it is the same as Example 1.

[0079] [Table 3]

[0080] As shown in Table 3 above, in the case of Comparative Examples 6 and 7, in which a protic solvent alone or an aprotic solvent alone was used, the intrinsic viscosity (IV) was low, making it difficult to ensure moldability and processability.

[0081] On the other hand, in the case of Examples 7 to 9, which use a mixed solvent of a protic solvent and an aprotic solvent as in the embodiments of the present invention, it can be seen that the intrinsic viscosity (IV) is high and that the moldability and processability are all excellent.

[0082] The present invention, as described above, is not limited to the embodiments described above, as it can be substituted or modified in various ways without departing from the technical concept of the invention by a person with ordinary skill in the art to which the invention belongs.

Claims

1. A step in which a polyamic acid solution is produced by solution polymerization of a dianhydride monomer and a diamine monomer in an organic solvent containing glass fiber powder; A step of heating the polyamic acid solution to produce a polyimide mixture; and The process includes filtering and drying the precipitate present in the mixture to obtain polyimide powder. A method for producing polyimide powder, characterized in that the content of the glass fiber powder contained in the organic solvent is 30 to 90 parts by weight per 100 parts by weight of the total of the dianhydride monomer and the diamine monomer.

2. The method for producing polyimide powder according to claim 1, characterized in that the organic solvent is a mixed solvent of a non-protic solvent and a protic solvent.

3. The aprotic solvent is one or more selected from the group consisting of toluene, xylene, naphtha, anisole, cresol, ethylbenzene, propylbenzene, chlorobenzene, dichlorobenzene, trichlorobenzene, biphenyl, terphenyl, diphenyl ether, diphenyl sulfide, acetophenone, chlorinated biphenyl, and chlorinated diphenyl ether. The method for producing polyimide powder according to claim 2, characterized in that the protic solvent is one or more selected from the group consisting of N-methylpyrrolidone (NMP), N,N'-dimethylformamide (DMF), N,N'-diethylformamide (DEF), N,N'-dimethylacetamide (DMAc), dimethylpropanamide (DMPA), N,N-diethylacetamide (DEAc), 3-methoxy-N,N-dimethylpropanamide (KJCMPA), and γ-butyrolactone (GBL).

4. The method for producing polyimide powder according to claim 2, characterized in that the mixed solvent comprises 10 to 90 wt% of an aprotic solvent and 10 to 90 wt% of a protic solvent.

5. The method for producing polyimide powder according to claim 1, characterized in that the step of producing the polyamic acid solution is carried out at 50 to 100°C.

6. The method for producing polyimide powder according to claim 1, characterized in that the step of producing the polyimide mixture is carried out at 140 to 200°C.

7. The method for producing polyimide powder according to claim 1, characterized in that the dianhydride monomer comprises at least one selected from the group consisting of pyromellitic acid dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4-biphenyltetracarboxylic acid dianhydride (a-BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA), and p-phenylenebis(trimellitate anhydride) (TAHQ).

8. The method for producing polyimide powder according to claim 1, characterized in that the diamine monomer comprises at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4-diaminobenzanilide (4,4-DABA), N,N-bis(4-aminophenyl)benzene-1,4-dicarboxamide (BPTPA), 2,2-dimethylbenzidine (M-TOLDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-bisaminophenoxybenzene (TPE-Q), bisaminophenoxybenzene (TPE-R), 2,2-bisaminophenoxyphenylpropane (BAPP), and 2,2-bisaminophenoxyphenylhexafluoropropane (HFBAPP).

9. Polyimidemetrics having polymerization units derived from dianhydride monomers and diamine monomers, and The polyimide metric contains glass fiber powder dispersed within it. The content of the glass fiber powder contained in the organic solvent is 30 to 90 parts by weight per 100 parts by weight of the total of the dianhydride monomer and the diamine monomer. Polyimide powder characterized by satisfying one or more of the following conditions: a) The weight loss rate measured after being left at 800°C for 25 hours is 35% or less, and the surface resistance is 10 １４ Ω / cm ２ That's all; b) A weight loss rate of 2.6% or less, measured after immersion in an acidic aqueous solution with a pH of 5 or less for 168 hours; or c) A weight loss rate of 15% or less, measured after immersion in an alkaline aqueous solution with a pH of 9 or higher for 168 hours.

10. The polyimide powder according to claim 9, characterized in that the dianhydride monomer comprises at least one selected from the group consisting of pyromellitic acid dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA), 2,3,3',4-biphenyltetracarboxylic acid dianhydride (a-BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), oxydiphthalic acid dianhydride (ODPA), 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA), and p-phenylenebis(trimellitate anhydride) (TAHQ).

11. The polyimide powder according to claim 9, characterized in that the diamine monomer comprises at least one selected from the group consisting of 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminodiphenyl ether (ODA), 4,4'-methylenediamine (MDA), 4,4-diaminobenzanilide (4,4-DABA), N,N-bis(4-aminophenyl)benzene-1,4-dicarboxamide (BPTPA), 2,2-dimethylbenzidine (M-TOLDINE), 2,2-bis(trifluoromethyl)benzidine (TFDB), 1,4-bisaminophenoxybenzene (TPE-Q), bisaminophenoxybenzene (TPE-R), 2,2-bisaminophenoxyphenylpropane (BAPP), and 2,2-bisaminophenoxyphenylhexafluoropropane (HFBAPP).

12. A method for producing a polyimide molded article, characterized by including the step of press-molding the polyimide powder described in claim 9.

13. The method for producing a polyimide molded article according to claim 12, characterized in that the pressure molding step is performed at a pressure of 30 to 1,000 MPa.

14. The method for producing a polyimide molded article according to claim 12, characterized in that the pressure molding step is performed at 200 to 500°C.

15. A method for producing a polyimide molded article according to claim 12, characterized by further comprising the step of sintering the pressure-molded polyimide powder at 200 to 500°C.

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