Method for producing polyimide powder and polyimide powder produced thereby

Abstract

The present invention provides a method for producing a polyimide powder having excellent intrinsic viscosity by controlling a polymerization reaction using a mixed solvent containing a polar organic solvent and a high-boiling aromatic hydrocarbon solvent to promote imidization, and a polyimide powder produced thereby.

Description

[Technical field]

[0001] The present invention relates to a method for producing a polyimide powder and a polyimide powder produced thereby, and more particularly, to a method for producing a polyimide powder using a mixed solvent containing a polar organic solvent and an aromatic hydrocarbon solvent having a high boiling point, and a polyimide powder produced thereby. [Background technology]

[0002] Highly heat-resistant polymeric materials such as polyimide are essential materials for making products smaller, lighter, thinner, more highly functional, and more reliable with the development of cutting-edge technology, and are used in a wide range of industrial fields such as space, aviation, electrical / electronics, automobiles, and precision instruments in the form of films, molded products, fibers, paints, adhesives, and composite materials. Polyimide has excellent mechanical strength, chemical resistance, weather resistance, and heat resistance due to the chemical stability of the imide ring. In addition, it has the advantages of being easy to synthesize, being able to be produced as a thin film, and not requiring a crosslinking group for curing, and due to its excellent electrical properties, it has been in the spotlight as a highly functional polymeric material in the fields of microelectronics and optics. In recent years, in the display field, weight reduction and miniaturization of products have become important, but the glass substrates currently used have the disadvantages of being heavy, easily broken, and difficult to process continuously. Therefore, a polyimide substrate, which is lightweight, flexible, and has the advantages of being able to be processed continuously, is prepared as an alternative to glass substrates, and can be used to form insulating films and protective coating agents for semiconductor devices, surface protective materials and base resins for flexible circuit boards and integrated circuits, and interlayer insulating films and protective films for fine circuits. In particular, when used as a coating material, a protective material in which a molded body such as a polyimide film is bonded with an adhesive, a liquid polyimide resin solution, etc. can be used.

[0003] A typical method for synthesizing polyimide involves first synthesizing a precursor polyamic acid by the reaction of an acid dianhydride with a diamine, and then imidizing the polyamic acid. The polyamic acid is synthesized by ring-opening and polyaddition of a diamine and an acid dianhydride dissolved in a solvent. A polar organic solvent is mainly used as the reaction solvent. The synthesized polyamic acid is imidized by dehydration and ring-closing reaction using a chemical or thermal method to produce a polyimide. The chemical imidization method is a method in which a chemical dehydrating agent, typically an acid anhydride such as acetic anhydride, and an imidization catalyst, typically a tertiary amine such as pyridine, are added to a polyamic acid precursor solution. In the case where a dehydrating agent or a catalyst is further added to carry out the imidization reaction, there are problems in that the productivity and process efficiency are low due to the cost of the catalyst and the need for an additional process for removing the catalyst. The thermal imidization method involves applying a polyamic acid solution, which is a precursor, to a substrate, evaporating the solvent, and then heating the substrate at 250°C to 350°C without a chemical dehydrating agent or catalyst to thermally imidize the polyamic acid. However, this method has the disadvantages of having a high degree of crystallinity and of decomposing the polymer when an amide-based solvent is used, which causes an amide exchange reaction. In the polyimide powder produced by such a method, if the degree of imidization is low, water, which is a by-product of the imidization reaction, is generated during processing, which causes problems such as the generation of pores, resulting in a decrease in mechanical properties and a decrease in physical properties. Therefore, there is a need for research and development of a method for producing polyimide powder that can promote imidization in a simple and efficient process without adding a separate dehydrating agent or catalyst, and can produce polyimide powder having excellent intrinsic viscosity and molded products having excellent tensile strength and elongation. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a method for producing a polyimide powder having excellent intrinsic viscosity by promoting imidization by carrying out a reaction using a mixed solvent containing a polar organic solvent and a high-boiling aromatic hydrocarbon solvent without adding a separate dehydrating agent or catalyst, and a polyimide powder produced thereby. The present invention also provides a method for producing a molded article containing the polyimide powder. The present invention also provides a molded article containing the polyimide powder. [Means for solving the problem]

[0005] Hereinafter, the embodiments of the present invention will be described in more detail in the order of "method of producing polyimide powder," "polyimide powder," "method of producing molded article containing polyimide powder," and "molded article containing polyimide powder."

[0006] The present invention can be modified in various ways and can have various embodiments, and a specific embodiment will be illustrated in the drawings and described in detail. However, it should be understood that the present invention is not limited to the specific embodiment, and includes all modifications, equivalents, and alternatives within the spirit and technical scope of the present invention.

[0007] The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In the present invention, the terms "include" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood not to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Whenever an amount, concentration, or other value or parameter is given herein as a range, a preferred range, or a list of upper preferred values ​​and lower preferred values, that should be understood to specifically disclose all ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether a range is otherwise disclosed. Where a range of numerical values ​​is recited herein, unless otherwise stated, it is intended that the endpoints of the range, and the scope of the invention within that range, are not limited to the specific values ​​recited in defining the range.

[0008] As used herein, "dianhydrides" is intended to include precursors or derivatives thereof, but may also be referred to as "dianhydrides," "dianhydride acids," or "dianhydride acids," which may not technically be dianhydrides, but which nevertheless react with diamines to form polyamic acids, which may be converted back to polyimides. "Diamine" as used herein is intended to include precursors or derivatives thereof which may not technically be diamines, but which nevertheless react with dianhydrides to form polyamic acids which may be converted back to polyimides.

[0009] Unless otherwise specified, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person having ordinary skill in the art to which the present invention belongs. Terms similar to those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as ideal or overly formal unless clearly defined in this specification. Specific contents for realizing the above invention are described as follows.

[0010] The present invention provides a method for producing a polyimide powder using a mixed solvent containing a polar organic solvent and a high-boiling aromatic hydrocarbon solvent having a boiling point of 155° C. or higher. In one aspect, a method for producing a polyimide powder according to the present invention includes the steps of: (a) preparing a polyamic acid composition by mixing an acid dianhydride compound and a diamine compound in a mixed solvent; and (b) subjecting the mixture to an imidization reaction at a high temperature to form a polyimide powder; The mixed solvent contains a polar organic solvent and a high-boiling aromatic hydrocarbon solvent having a boiling point of 155° C. or higher.

[0011] The polar organic solvent in the present invention may have a boiling point of 150° C. or higher, preferably 160° C. or higher, more preferably 170° C. or higher, and even more preferably 200° C. or higher. The upper limit is not particularly limited, but may be 250° C. or lower. The polar organic solvent in the present invention may be N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), ethylene glycol, N-ethyl-2-pyrrolidone (NEP), dimethylolpropionic acid (DMPA), or a combination thereof, and is preferably N-methyl-2-pyrrolidone (NMP). In the present invention, the high boiling aromatic hydrocarbon may have a boiling point of 160° C. or more, preferably 160° C. to 250° C. The lower limit of the boiling point may be, for example, 160° C. or more, 161° C. or more, 162° C. or more, 163° C. or more, 164° C. or more, or 165° C. or more. The upper limit of the boiling point of the high boiling aromatic hydrocarbon may be, for example, 250° C. or less, 245° C. or less, 240° C. or less, 235° C. or less, 230° C. or less, 225° C. or less, 220° C. or less, 215° C. or less, 210° C. or less, 205° C. or less, 200° C. or less, 198° C. or less, 196° C. or less, 194° C. or less, 192° C. or less, 190° C. or less, 188° C. or less, 186° C. or less, 184° C. or less, 182° C. or less, or 180° C. or less.

[0012] In the present invention, the high boiling point aromatic hydrocarbon may be mesitylene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, propylbenzene, 1-ethyl-2-methylbenzene, etc., and preferably 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, propylbenzene, 1-ethyl-2-methylbenzene, or a combination thereof. In the present invention, the mixed solvent may further include a hydrocarbon-based solvent, and the hydrocarbon-based solvent may be hexane, cyclohexane, heptane, benzene, toluene, isopropylene, xylene, or a combination thereof, and preferably includes isopropylene or xylene, but the scope of the hydrocarbon-based solvent in the present invention is not limited thereto.

[0013] In the present invention, based on 100 parts by weight of the mixed solvent, the mixed solvent may contain 5 to 50 parts by weight of the high-boiling aromatic hydrocarbon solvent, specifically 10 to 45 parts by weight, more specifically 15 to 40 parts by weight, and even more specifically 20 to 35 parts by weight, and the remainder may be the polar organic solvent or the hydrocarbon solvent. In the present invention, based on 100 parts by weight of the mixed solvent, the mixed solvent may contain 50 to 95 parts by weight of a polar organic solvent, preferably 55 to 90 parts by weight, more preferably 60 to 85 parts by weight, and even more preferably 65 to 80 parts by weight, and the remainder may be the aromatic hydrocarbon solvent or the hydrocarbon-based solvent. The mixed solvent in the present invention may contain 50 to 95 parts by weight of a polar organic solvent, 5 to 50 parts by weight of a high-boiling aromatic hydrocarbon solvent, and may further contain 1 to 5 parts by weight of a hydrocarbon solvent.

[0014] In the present invention, the polyimide powder may be a wholly aromatic polyimide, a partially alicyclic polyimide, or a wholly alicyclic polyimide. In one embodiment of the present invention, the acid dianhydride compound is pyromellitic dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (sBPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride. , 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimellitic acid monoester) water), p-biphenylene bis(trimellitic acid monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic acid dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic acid dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, The dianhydride may be bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, etc., and preferably may be pyromellitic dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), or a combination thereof. The range of the dianhydride compound of the present invention is not limited to these, and a wide variety of dianhydrides used in the production of polyimides can be used.

[0015] The diamine compound may be, for example, paraphenylenediamine, metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 4,4'-diaminodiphenyl ether, 4,4'-oxydianiline (ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,4 ... ,2'-Bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether , 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'- Diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4 -aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl] phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, Bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, etc., are preferred.The diamine compound in the present invention is not limited to these, and a wide variety of diamine compounds used in the production of polyimides can be used.

[0016] In one embodiment, the polyimide powder can be produced by using pyromellitic dianhydride (PMDA) and oxydiphthalic dianhydride (ODPA) as the acid dianhydride compound and 4,4'-oxydianiline (ODA) as the diamine compound. In one embodiment, the polyamic acid composition may contain two or more kinds of acid dianhydride compounds, among which pyromellitic dianhydride (PMDA) may be included. Specifically, the pyromellitic dianhydride (PMDA) may be included in a ratio of 70 mol% or more in the total acid dianhydride components. The lower limit of the ratio may be, for example, 75 mol%, 78 mol%, 80 mol%, 82 mol%, 85 mol%, 87 mol%, 90 mol%, 92 mol%, 94 mol%, 95 mol%, 97 mol%, 99 mol%, or 100 mol% or more, and the upper limit may be, for example, 100 mol%, 99 mol%, 98 mol%, 97 mol%, 96 mol%, 95 mol%, 94 mol%, 93 mol%, 92 mol%, 91 mol%, or 90 mol% or less. In one embodiment, the polyamic acid composition may include two or more kinds of acid dianhydride compounds, among which oxydiphthalic dianhydride (ODPA) may be included. Specifically, the oxydiphthalic dianhydride (ODPA) may be included in a ratio of 30 mol% or less in the total acid dianhydride components. Preferably, it may be included in a ratio of 20 mol% or less, 19 mol% or less, 18 mol% or less, 17 mol% or less, 16 mol% or less, 15 mol% or less, 14 mol% or less, 13 mol% or less, 12 mol% or less, 11 mol% or less, 10 mol% or less, 8 mol% or less, 6 mol% or less, 4 mol% or less, or 2 mol% or less, or may be 0 mol%. In one embodiment, the polyamic acid composition may include one or more diamine compounds, and may preferably include 4,4'-oxydianiline (ODA). Specifically, the 4,4'-oxydianiline (ODA) may be included in a ratio of 70 mol % or more of the total diamine monomer components. The lower limit of the ratio may be, for example, 70 mol% or more, 71 mol% or more, 72 mol% or more, 73 mol% or more, 74 mol% or more, 75 mol% or more, 76 mol% or more, 77 mol% or more, 78 mol% or more, 80 mol% or more, 82 mol% or more, 85 mol% or more, 87 mol% or more, 90 mol% or more, 92 mol% or more, 94 mol% or more, 95 mol% or more, 97 mol% or more, 99 mol% or more, or 100 mol%, and the upper limit may be, for example, 100 mol% or less, 99 mol% or less, 98 mol% or less, 97 mol% or less, 96 mol% or less, 95 mol% or less, 94 mol% or less, 93 mol% or less, 92 mol% or less, 91 mol% or less, or 90 mol% or less. In the present invention, in the step (a), the molar ratio of the diamine compound to the acid dianhydride compound may be 0.5 to 2 equivalents. More specifically, the molar ratio may be 0.8 to 1.5 equivalents. If the molar ratio is less than 0.5 equivalents or exceeds 2 equivalents, the molecular weight of the polyimide finally formed becomes very small, which causes a problem that the physical and chemical properties of the polyimide are very poor.

[0017] In step (a), the mixture may include a polyamic acid formed by a polymerization reaction of an acid dianhydride compound and a diamine compound. In addition, the step (a) can be carried out in various ways, for example, by dispersing each compound in a solvent (or a mixed solvent) and then adding the resulting mixture to a reaction vessel, or by preferentially adding a solvent (or a mixed solvent) to a reaction vessel and then adding each compound, or by preferentially adding each compound to a reaction vessel and then adding a solvent (or a mixed solvent), or by a combination of the above methods. In the present invention, the mixed solvent may be used in an amount of 5 to 50 times, 7 to 40 times, or 10 to 30 times the weight of the acid dianhydride compound as a reactant, and the amount of the mixed solvent may be appropriately adjusted depending on the amounts of the acid dianhydride compound and the diamine compound used in the reaction.

[0018] In addition, the step (a) may be carried out at a temperature in the range of 10 to 95°C. If the temperature is less than 10°C, the reaction does not proceed, and if the temperature exceeds 95°C, a separate heat source supplying device or a cooling and condensing device may be required, or an additional process may be required. In addition, step (a) may be performed for 5 minutes to 5 days, and more specifically, for 1 hour to 2 days. If step (a) is performed for less than 5 minutes, the reaction may not proceed sufficiently, whereas if it is performed for more than 5 days, the cost of the process may increase too much.

[0019] In the present invention, the step (b) may be performed at a high temperature in the range of 150° C. to 450° C. In particular, the step (b) may be performed in the range of 180° C. to 350° C. When the step (b) is performed at a temperature lower than 150° C., imidization may not proceed, whereas when the step (b) is performed at a temperature higher than 450° C., thermal decomposition of the monomer (or compound) or the polymer itself may occur. In the present invention, the step (b) may be performed for 5 minutes to 5 days, specifically 10 minutes to 2 days, more specifically 30 minutes to 1 day, and even more specifically 1 hour to 5 hours. If the step (b) is performed for less than 5 minutes, imidization may not be achieved, and if it is performed for more than 5 days, hydrolysis or thermal decomposition of the polymer may occur. In step (b), the heating may be performed by one or a combination of two or more methods selected from the group consisting of heat treatment, hot air treatment, corona treatment, high frequency treatment, ultraviolet treatment, infrared treatment, and laser treatment. In the step (b), the solid content of the polyimide powder is 1 to 25% by weight, specifically 1 to 20% by weight, more specifically 2 to 18% by weight, and even more specifically 3 to 15% by weight.

[0020] In addition, the method for producing a polyimide powder according to the present invention may further include the step of (c) washing, filtering, and drying the polyimide powder. The filtration may be performed by one or a combination of two or more methods selected from the group consisting of gravity filtration, reduced pressure filtration, vacuum filtration, pressure filtration, compression filtration, centrifugal filtration, microfiltration, ultrafiltration, and reverse osmosis. In particular, reduced pressure filtration is preferably used. The drying may be carried out by one or a combination of two or more methods selected from the group consisting of natural drying, pressure drying, hot air drying, spray drying, film drying, vacuum drying, freeze drying, spray freeze drying, electromagnetic wave drying and flash drying. In particular, drying at 50° C. or higher under vacuum is preferred. In the present invention, the imidization reaction carried out in the step (b) has an imidization rate of 97 to 100%, preferably 98 to 100%, more preferably 99 to 100%, and most preferably 100%.

[0021] In the method for producing a polyimide powder according to the present invention, the imidization reaction is carried out in a mixed solvent containing a polar organic solvent and a high-boiling aromatic hydrocarbon solvent having a boiling point of 155° C. or higher, and the high-boiling aromatic hydrocarbon solvent simultaneously serves as a dehydrating agent, thereby accelerating the imidization of the polyamic acid without the need for the addition of a separate catalyst or dehydrating agent. In addition, since the powder is precipitated by imidization at a temperature of about 150° C. to 160° C., sufficient imidization is achieved, and excellent physical properties such as improved intrinsic viscosity can be maintained.

[0022] In another aspect, the present invention provides a polyimide powder produced by the method for producing a polyimide powder. The polyimide powder has a high intrinsic viscosity of 1.0 dL / g or more, which is advantageous in that it allows easy post-processing such as molding while maintaining excellent mechanical properties. In one embodiment, the intrinsic viscosity of the polyimide powder in the present invention may be 1.0 to 1.5 dL / g, specifically 1.0 to 1.3 dL / g, more preferably 1.0 to 1.2 dL / g, and even more preferably 1.1 to 1.15 dL / g. If the intrinsic viscosity of the polyimide powder is less than 1.0 dL / g, there is a problem that the strength of the molded product (or molded body) molded with the polyimide powder is weakened, making post-processing difficult.

[0023] In another aspect of the present invention, a method for producing a polyimide powder comprising the steps of: (1) molding a polyimide powder produced by the method for producing a polyimide powder according to the present invention; and (2) a step of sintering the polyimide. In the molding step in step (1), methods such as compression molding, injection molding, blow molding, rotational molding, extrusion molding, thermoforming, slush molding, spinning, etc. can be applied.

[0024] In another aspect of the present invention, there is provided a polyimide molded article produced by the method for producing a polyimide molded article. In the present invention, the polyimide molded article may have a tensile strength of 85 MPa or more, preferably 90 MPa or more, more preferably 95 MPa or more, even more preferably 100 MPa or more, and even more preferably 110 MPa or more. There is no upper limit, but the upper limit may be 200 MPa or less. The polyimide molded article may have an elongation percentage of 7% or more, preferably 8% or more, more preferably 9% or more, and even more preferably 10% or more. There is no upper limit, but the elongation percentage may be 40% or less, 30% or less, or 20% or less. The polyimide molded article may have a modulus of 1.5 GPa or more, preferably 2.0 GPa or more, more preferably 2.5 GPa or more, and even more preferably 3.0 GPa or more. The polyimide molded article may have a flexural strength of 150 MPa or more, preferably 155 MPa or more, more preferably 160 MPa or more, and even more preferably 170 MPa or more. There is no upper limit, but the flexural strength may be 300 MPa or less.

[0025] In the present invention, the molded article may be referred to as a molding, and the molded article may be applied in various forms such as a film, adhesive, tape, fiber, multilayer film, etc., to a wide range of industrial fields such as aerospace, aviation, electrical / electronics, semiconductors, displays, liquid crystal alignment films, automobiles, precision instruments, packaging, medical materials, separators, fuel cells, and secondary batteries, and may be widely used in any product or field suitable for the physical properties and characteristics of the molded article manufactured from the polyimide powder of the present invention. In addition, a molded article containing a polyimide powder produced by the method for producing a polyimide powder according to the present invention has an advantage that tensile strength, elongation, modulus, and flexural strength are all improved at the same time, and can be applied to various fields where such physical properties are required. Effect of the Invention

[0026] The method for producing a polyimide powder according to the present invention can produce a polyimide powder having a high intrinsic viscosity and a high imidization rate through a simple and efficient process by promoting imidization through a reaction in a mixed solvent containing a polar organic solvent and a high boiling point aromatic hydrocarbon solvent without adding a separate dehydrating agent or catalyst. Molded products produced from the polyimide powder have excellent tensile strength, elongation, modulus and flexural strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Examples are presented to aid in understanding the present invention. The following examples are provided merely to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention.

[0028] <Example> Example 1. Preparation of polyimide powder using a high boiling point aromatic hydrocarbon solvent Example 1-1. Preparation of polyimide powder (1) A polyamic acid composition was prepared by dispersing the acid dianhydride compounds pyromellitic dianhydride (PMDA) (80 mol%) and oxydiphthalic dianhydride (ODPA) (20 mol%) and the diamine compound 4,4'-oxydianiline (100 mol%) in a mixed solvent of polar solvent N-methylpyrrolidone and high boiling point aromatic hydrocarbon solvent 1,2,3-trimethylbenzene (bp. 176°C) in a ratio of 70:30 (v / v%). The mixture was transferred to a 500 mL reaction vessel equipped with a stirrer, nitrogen injector, and temperature controller, and the air in the reaction vessel was replaced with nitrogen gas. The mixture was stirred in a high-temperature reactor at 180° C. for 6 hours to form a polyimide powder. The polyimide powder suspension was washed with distilled water and filtered under reduced pressure, and the resulting undried polyimide powder was dried in a vacuum oven at 60° C. for 24 hours to obtain a polyimide powder.

[0029] Example 1-2. Preparation of polyimide powder (2) The acid dianhydride compounds pyromellitic dianhydride (80 mol%) and oxydiphthalic dianhydride (ODPA) (20 mol%) and the diamine compound 4,4'-oxydianiline (100 mol%) were dispersed in a mixed solvent of polar solvent N-methylpyrrolidone and high boiling point aromatic hydrocarbon solvent 1,2,4-trimethylbenzene (bp. 169°C) in a ratio of 70:30 (v / v%) to prepare a mixture. The mixture was transferred to a 500 mL reaction vessel equipped with a stirrer, nitrogen injection device, and temperature controller, and the air in the reaction vessel was replaced with nitrogen gas. The mixture was stirred in a high-temperature reactor at 180° C. for 6 hours to form a polyimide powder. The polyimide powder suspension was filtered under reduced pressure while being washed with distilled water, and the obtained undried polyimide powder was dried in a vacuum oven at 60° C. for 24 hours to obtain a polyimide powder.

[0030] Example 2. Production of molded products from polyimide powder Example 2-1 and Example 2-2. Production of polyimide molded products The polyimide powders produced in Examples 1-1 and 1-2 were weighed into molds for evaluating physical properties, and heated to 450° C. while applying a pressure of 10,000 Psi or more with a hot press to produce molded products.

[0031] Comparative Example 1. Production of polyimide powder using a low boiling point aromatic hydrocarbon solvent Comparative Example 1-1. Production of polyimide powder A polyimide powder was prepared in the same manner as in Example 1, except that xylene (bp 139° C.), which is a low boiling point aromatic hydrocarbon solvent, was used instead of the high boiling point aromatic hydrocarbon solvent.

[0032] Comparative Example 1-2. Production of polyimide powder A polyimide powder was prepared in the same manner as in Example 1, except that toluene (bp 111° C.), which is a low boiling point aromatic hydrocarbon solvent, was used instead of the high boiling point aromatic hydrocarbon solvent.

[0033] Comparative Example 1-3. Production of polyimide powder A polyimide powder was produced in the same manner as in Example 1, except that the high boiling point aromatic hydrocarbon was omitted.

[0034] Comparative Example 2. Production of molded products using polyimide powder with a low boiling point aromatic hydrocarbon solvent Comparative Examples 2-1 to 2-3. Production of polyimide molded products The polyimide powders produced in Comparative Examples 1-1 to 1-3 were weighed into molds for evaluating physical properties, and heated to 450°C while applying a pressure of 10,000 Psi or more using a hot press, to produce polyimide molded products of Comparative Examples 2-1, 2-2, and 2-3.

[0035] The components and contents of the acid dianhydride compounds and diamine compounds used in producing the polyimide powders in Examples 1-1, 1-2, Comparative Examples 1-1, 1-2, and 1-3, and the components of the mixed solvents are summarized in Table 1 below.

[0036] [Table 1]

[0037] <Experimental Example> Analysis of physicochemical properties of polyimide powder and molded products Experimental Example 1. Imidation rate The imidization rate was measured by pelletizing the polyimide powder and then measuring it using a Nicolet iZ20 FT IR (ATR) from Thermo Scientific. -1 / 1490cm -1 The values ​​were calculated by comparing the imidization rates, with a polyimide film in which imidization had progressed 100% being taken as the standard.

[0038] Experimental Example 2. Intrinsic Viscosity 0.1 g of the polyimide powder prepared in the examples and comparative examples was dissolved in 20 ml of N,N'-dimethylacetamide, and the viscosities were measured using an Ubbelohde viscometer in a thermostatic chamber maintained at 30°C.

[0039] The imidization rate and intrinsic viscosity of the polyimide powder analyzed in Experimental Examples 1 and 2 are shown in Table 2 below.

[0040] [Table 2]

[0041] Experimental Example 3. Tensile strength The tensile strength of the samples was measured using a universal testing machine (model name Instron 5564, Instron Corporation) according to the method set forth in ASTM D1708.

[0042] Experimental Example 4. Elongation The polyimide molded bodies produced in the Examples and Comparative Examples were cut to a width of 10 mm and a length of 40 mm, and the elongation was measured using an Instron 5564 UTM device manufactured by Instron Corporation according to the ASTM D-882 method.

[0043] Experimental Example 5. Flexural strength Flexural strength was measured using a UTM according to ASTM D790 method.

[0044] The physical properties of the polyimide molded articles analyzed in Experimental Examples 3 to 5 are shown in Table 3 below.

[0045] [Table 3]

[0046] Experimental Example 6. Modulus (elastic coefficient) The polyimide molded articles (width 15 mm) produced in the Examples and Comparative Examples were subjected to modulus measurement according to the ASTM D-882 method using an Instron 5564 model (Grip Speed=200 mm / min). The modulus of the polyimide molded article analyzed in Experimental Example 6 is shown in Table 4 below.

[0047] [Table 4]

[0048] In the case of the examples of the present invention in which the imidization reaction was carried out using a high boiling aromatic hydrocarbon solvent having a boiling point of 155°C or more, a high imidization rate of 100% was achieved, and an excellent intrinsic viscosity of 1.0 dL / g or more was shown. In addition, the molded article produced using the polyimide powder according to the present invention had a tensile strength of 110 MPa or more, an elongation of 10% or more, and a flexural strength of 170 MPa or more, which were significantly superior to the comparative examples. In addition, the molded article produced using the polyimide powder according to the present invention was shown to have excellent rigidity, since it had a modulus of 1.5 GPa or more. Comparative Examples 1-1 and 1-2, in which the imidization reaction was carried out using an aromatic hydrocarbon solvent having a low boiling point of less than 155°C, and Comparative Example 1-3, which did not contain an aromatic hydrocarbon solvent, showed lower imidization rates than the Examples. The molded products of the polyimide powder produced in the Comparative Examples had significantly lower tensile strength, elongation, and flexural strength than the Examples, and were not suitable for application to actual products.

[0049] The specification omits detailed descriptions of contents that a person having ordinary skill in the technical field of the present invention can fully recognize and infer, and various modifications are possible within the scope of the technical idea and essential configuration of the present invention other than the specific examples described in the specification. Therefore, the present invention can be implemented in a manner different from that specifically described and exemplified in the specification, and this is something that a person having ordinary skill in the technical field of the present invention can understand.

Claims

1. (a) dispersing an acid dianhydride compound and a diamine compound in a mixed solvent to prepare a polyamic acid composition; and (b) subjecting the mixture to an imidization reaction at a high temperature to form a polyimide powder; The method for producing a polyimide powder, wherein the mixed solvent contains a polar organic solvent and a high-boiling aromatic hydrocarbon solvent having a boiling point of 155° C. or higher.

2. The method for producing a polyimide powder according to claim 1 , wherein the polar organic solvent has a boiling point of 150° C. or higher.

3. 2. The method for producing a polyimide powder according to claim 1, wherein the polar organic solvent comprises at least one selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), ethylene glycol, N-ethyl-2-pyrrolidone (NEP), and dimethylolpropionic acid (DMPA).

4. 2. The method for producing a polyimide powder according to claim 1, wherein the high-boiling aromatic hydrocarbon solvent further comprises at least one selected from the group consisting of mesitylene, 1,2,4-trimethylbenzene, 1,2,3-trimethylbenzene, propylbenzene, and 1-ethyl-2-methylbenzene.

5. 2. The method for producing a polyimide powder according to claim 1, wherein the high boiling point aromatic hydrocarbon includes a high boiling point aromatic hydrocarbon solvent having a boiling point of 160° C. or higher.

6. The method for producing a polyimide powder according to claim 1 , wherein the mixed solvent further contains a hydrocarbon solvent.

7. 7. The method for producing a polyimide powder according to claim 6, wherein the hydrocarbon solvent comprises at least one selected from the group consisting of hexane, cyclohexane, heptane, benzene, toluene, isopropylene, and xylene.

8. 2. The method for producing a polyimide powder according to claim 1, wherein the mixed solvent contains 50 to 95 parts by weight of a polar organic solvent and 5 to 50 parts by weight of a high-boiling aromatic hydrocarbon solvent, based on 100 parts by weight of the mixed solvent.

9. 2. The method for producing a polyimide powder according to claim 1, wherein the polyimide powder is any one selected from the group consisting of wholly aromatic polyimides, partially alicyclic polyimides, and wholly alicyclic polyimides.

10. The acid dianhydride compound is pyromellitic dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (sBPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene and one or more selected from the group consisting of 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, The diamine compound is, for example, paraphenylenediamine, metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 4,4'-oxydianiline (ODA), 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2 '-Bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-di Aminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4 -aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl)isopropyl]benzene, 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone , bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy 2,2-bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, The method for producing a polyimide decomposition product according to claim 1, wherein the polyimide decomposition product is one or more selected from the group consisting of 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

11. 2. The method of claim 1, further comprising: (c) washing, filtering and drying the polyimide powder.

12. 2. The method for producing a polyimide powder according to claim 1, wherein the imidization reaction has an imidization rate of 97 to 100%.

13. A polyimide powder produced by the method for producing a polyimide powder according to any one of claims 1 to 12.

14. The polyimide powder according to claim 13, wherein the intrinsic viscosity of the polyimide powder is 1.0 to 1.5 dL / g.

15. (1) A step of molding a polyimide powder produced by the method for producing a polyimide powder according to any one of claims 1 to 12; and (2) sintering, A method for manufacturing polyimide molded products.

16. A polyimide molded article produced by the method for producing a polyimide molded article according to claim 15.

17. The polyimide molded article is The tensile strength is 85 MPa or more, The elongation rate is 7% or more, The modulus is 1.5 GPa or more, 17. The polyimide molded article according to claim 16, having a flexural strength of 150 MPa or more.

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