Polyimide resin powder and polyimide molded body

Abstract

Provided is a polyimide resin powder which contains a tetracarboxylic acid component and a diamine component. The tetracarboxylic acid component includes 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and 2,3,3',4'-biphenyltetracarboxylic acid dianhydride. The diamine component includes p-phenylenediamine and m-phenylenediamine and / or 4,4'-diaminodiphenyl ether. The content of p-phenylenediamine is 70-98 mol% based on the total molar amount of the diamine component. The total content of m-phenylenediamine and 4,4'-diaminodiphenyl ether is 2-30 mol% based on the total molar amount of the diamine component.

Description

Polyimide resin powder and polyimide molded body

[0001] The present invention relates to a polyimide resin powder and a polyimide molded article obtained using the same.

[0002] Polyimides, which are obtained from tetracarboxylic acid components and diamine components as main raw materials, have excellent properties such as heat resistance, mechanical strength, electrical properties, and solvent resistance, and are widely used as materials for electrical and electronic components, etc. Among these, polyimide resin powder processed into a powder form can be filled into a mold and pressed to obtain desired molded products, and is therefore widely used as a material for producing parts for industrial manufacturing equipment.

[0003] As an example of a polyimide molded article using such a polyimide resin powder, Patent Document 1 discloses a polyimide molded article using a polyimide resin powder that is composed of at least one aromatic tetracarboxylic dianhydride component (A) and at least one diamine component (B), wherein the at least one aromatic tetracarboxylic dianhydride component (A) comprises 60 to 100 mol % of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 40 to 0 mol % of pyromellitic dianhydride (PMDA), and the at least one diamine component (B) is a mixture of p-phenylenediamine (PPD), m-phenylenediamine (MPD), and 4,4'-diaminodiphenyl ether (ODA).

[0004] JP 2015-129277 A

[0005] However, conventional polyimide resin powders have a problem in that cracks and chips frequently occur when a molded body is processed (for example, when processed by cutting, etc.) The present invention has been made in view of the above problem, and an object of the present invention is to provide a polyimide resin powder that can give a polyimide molded body having high mechanical properties and can effectively suppress the occurrence of cracks and chips when the molded body is processed.

[0006] In order to achieve the above object, the present inventors have conducted extensive research and have found that the above object can be achieved by using a combination of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) as the tetracarboxylic acid component, and by incorporating p-phenylenediamine (PPD) and m-phenylenediamine (MPD) and / or 4,4'-diaminodiphenyl ether (ODA) in specific ratios as the diamine component, thereby completing the present invention.

[0007] That is, the present invention provides the following items [1] to [5]: [1] A polyimide resin powder containing units derived from a tetracarboxylic acid component (A) and units derived from a diamine component (B), wherein the units derived from the tetracarboxylic acid component (A) include units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride, and the units derived from the diamine component (B) include units derived from p-phenylenediamine and units derived from m-phenylenediamine and / or units derived from 4,4'-diaminodiphenyl ether, and the content of the units derived from p-phenylenediamine is 70 to 98 mol % based on the total molar amount of the units derived from the diamine component (B), A polyimide resin powder, wherein the total content of the units derived from m-phenylenediamine and the units derived from 4,4'-diaminodiphenyl ether is 2 to 30 mol % based on the total molar amount of the units derived from diamine component (B), and the content of the units derived from 4,4'-diaminodiphenyl ether is 18 mol % or less based on the total molar amount of the units derived from diamine component (B). [2] The polyimide resin powder according to [1], wherein the content of the units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride is 80 to 95 mol % and the content of the units derived from 2,3,3',4'-biphenyltetracarboxylic acid is 2 to 20 mol % based on the total molar amount of the units derived from tetracarboxylic acid component (A). [3] The polyimide resin powder according to [1] or [2], wherein the crystallinity measured by wide-angle X-ray diffraction is 25 to 36%. [4] A polyimide molded body obtained by molding the polyimide resin powder according to any one of [1] to [3]. [5] A method for producing the molded body according to [4], comprising the steps of compression-molding the polyimide resin powder at a pressure of 50 to 500 MPa and baking it at a temperature of 300 to 550°C.

[0008] According to the present invention, it is possible to provide a polyimide resin powder that can give a polyimide molded article having high mechanical properties and can effectively suppress the occurrence of cracks and chips when the molded article is processed (for example, when processed by cutting or the like).

[0009] <Polyimide Resin Powder> The polyimide resin powder of the present invention contains units derived from a tetracarboxylic acid component (A) and units derived from a diamine component (B), and the units derived from the tetracarboxylic acid component (A) include units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), and the units derived from the diamine component (B) include units derived from p-phenylenediamine (PPD) and units derived from m-phenylenediamine (MPD) and / or units derived from 4,4'-diaminodiphenyl ether (ODA).

[0010] The tetracarboxylic acid component (A) constituting the units derived from the tetracarboxylic acid component (A) includes tetracarboxylic acids and derivatives thereof, and tetracarboxylic acid anhydrides. The polyimide resin powder of the present invention contains 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (a-BPDA) as the tetracarboxylic acid component (A).

[0011] In the polyimide resin powder of the present invention, the content of units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) is preferably 80 to 98 mol%, more preferably 82 to 98 mol%, even more preferably 85 to 98 mol%, and particularly preferably 85 to 95 mol%, based on the total molar amount of units derived from tetracarboxylic acid component (A). It may be 91 mol% or more, 94 mol% or less, or 93 mol% or less. Furthermore, in the polyimide resin powder of the present invention, the content of units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) is preferably 2 to 20 mol%, more preferably 2 to 18 mol%, even more preferably 2 to 15 mol%, even more preferably 3 to 15 mol%, particularly preferably 6 to 15 mol%, and particularly preferably 7 to 15 mol%, and may be 9 mol% or less, based on the total molar amount of units derived from tetracarboxylic acid component (A). By setting the contents of the units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and the units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) within the above ranges, the mechanical strength of the obtained polyimide molded article can be further increased.

[0012] In addition, in the polyimide resin powder of the present invention, the tetracarboxylic acid component (A) constituting the units derived from the tetracarboxylic acid component (A) may contain a tetracarboxylic acid component other than the above-mentioned 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA).

[0013] Such other tetracarboxylic acid components are not particularly limited, but examples thereof include aromatic tetracarboxylic acid dianhydrides (tetracarboxylic acid dianhydrides having an aromatic group) and alicyclic tetracarboxylic acid dianhydrides (tetracarboxylic acid dianhydrides having an alicyclic structure).

[0014] Examples of aromatic tetracarboxylic dianhydrides include 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride (1,2,4,5-benzenetetracarboxylic dianhydride), benzophenonetetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, diphenylsulfonetetracarboxylic dianhydride, p-terphenyltetracarboxylic dianhydride, m-terphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, oxydiphthalic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride.

[0015] Examples of the alicyclic tetracarboxylic dianhydride include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, [1,1'-bi(cyclohexane)]-3,3',4,4'-tetracarboxylic dianhydride, [1,1'-bi(cyclohexane)]-2,3,3',4'-tetracarboxylic dianhydride, [1,1'-bi(cyclohexane)]-2,2',3,3'-tetracarboxylic dianhydride, 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic anhydride), 4,4'-thiobis(cyclohexane-1,2-dicarboxanhydride), and 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic anhydride). anhydride), 4,4'-sulfonylbis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid anhydride), octahydropentalene-1,3,4,6-tetracarboxylic acid dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic acid dianhydride, 6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3,5-tricarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo[2.2.2]oct-5-ene-2,3,7,8-tetracarboxylic acid dianhydride, tricyclo[4.2.2.0２，５ ] decane-3,4,7,8-tetracarboxylic dianhydride, tricyclo[4.2.2.0 ２，５ ] dec-7-ene-3,4,9,10-tetracarboxylic dianhydride, 9-oxatricyclo[4.2.1.0 ２，５ ] nonane-3,4,7,8-tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic dianhydride, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic dianhydride, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic dianhydride, decahydro-1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic dianhydride, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic dianhydride, and the like.

[0016] In the case where the polyimide resin powder of the present invention contains units derived from other tetracarboxylic acid components, the content of the units derived from other tetracarboxylic acid components is preferably 3 to 30 mol %, more preferably 5 to 20 mol %, based on the total molar amount of units derived from tetracarboxylic acid component (A).

[0017] The diamine component (B) constituting the units derived from the diamine component (B) is a compound having two amine structures, and the polyimide resin powder of the present invention contains p-phenylenediamine (PPD), m-phenylenediamine (MPD) and / or 4,4'-diaminodiphenyl ether (ODA) as the diamine component (B).

[0018] In the polyimide resin powder of the present invention, the content of units derived from p-phenylenediamine (PPD) is 70 to 98 mol % based on the total molar amount of units derived from diamine component (B), the total content of units derived from m-phenylenediamine (MPD) and units derived from 4,4'-diaminodiphenyl ether (ODA) is 2 to 30 mol % based on the total molar amount of units derived from diamine component (B), and the content of units derived from 4,4'-diaminodiphenyl ether (ODA) is 18 mol % or less based on the total molar amount of units derived from diamine component (B).

[0019] In the present invention, the polyimide resin powder contains, as the tetracarboxylic acid component (A) constituting the units derived from the tetracarboxylic acid component (A), units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), and, as the units derived from the diamine component (B), units derived from p-phenylenediamine (PPD), units derived from m-phenylenediamine (MPD) and / or 4,4'-diamino In addition, the content of units derived from p-phenylenediamine (PPD) and the total content of units derived from m-phenylenediamine (MPD) and units derived from 4,4'-diaminodiphenyl ether (ODA) are within the above ranges, which enables the polyimide resin powder to give a polyimide molded article having high mechanical properties and to effectively suppress the occurrence of cracks and chips during processing of the molded article. Note that if the content of units derived from 4,4'-diaminodiphenyl ether (ODA) exceeds 18 mol % based on the total molar amount of units derived from diamine component (B), the flexural strength and flexural modulus will decrease.

[0020] If the content of units derived from p-phenylenediamine (PPD) among the units derived from diamine component (B) is too low, the flexural strength and flexural modulus of the obtained molded article will be reduced, resulting in poor mechanical strength.On the other hand, if the content of units derived from p-phenylenediamine (PPD) is too high, the effect of suppressing cracking and chipping during processing of the molded article will be insufficient.

[0021] Furthermore, if the total content of units derived from m-phenylenediamine (MPD) and units derived from 4,4'-diaminodiphenyl ether (ODA) among the units derived from diamine component (B) is too low, the effect of suppressing cracking and chipping during processing of the molded article will be insufficient. On the other hand, if the total content of units derived from m-phenylenediamine (MPD) and units derived from 4,4'-diaminodiphenyl ether (ODA) is too high, the flexural strength and flexural modulus of the obtained molded article will be reduced, resulting in poor mechanical strength.

[0022] In the polyimide resin powder of the present invention, the content of units derived from p-phenylenediamine (PPD) is 70 to 98 mol %, preferably 75 to 95 mol %, more preferably 80 to 93 mol %, even more preferably 82 to 93 mol %, still more preferably 83 to 93 mol %, and particularly preferably 85 to 93 mol %, based on the total molar amount of units derived from the diamine component (B).

[0023] In the polyimide resin powder of the present invention, the total content of units derived from m-phenylenediamine (MPD) and units derived from 4,4'-diaminodiphenyl ether (ODA) is 2 to 30 mol %, preferably 5 to 25 mol %, and more preferably 7 to 20 mol %, based on the total molar amount of units derived from diamine component (B). When only one of units derived from m-phenylenediamine (MPD) and units derived from 4,4'-diaminodiphenyl ether (ODA) is contained, it is sufficient that the content of only one of them is within the above range, and when both are contained, it is sufficient that the total content of both is within the above range.

[0024] In the polyimide resin powder of the present invention, when units derived from m-phenylenediamine (MPD) are contained, the content of the units derived from m-phenylenediamine (MPD) is preferably 2 to 30 mol%, more preferably 5 to 25 mol%, and even more preferably 7 to 20 mol%, based on the total molar amount of units derived from diamine component (B). It may be 8 mol% or more, 12 mol% or more, 17 mol% or less, or 13 mol% or less. In the polyimide resin powder of the present invention, when units derived from m-phenylenediamine (MPD) are contained, the content of the units derived from p-phenylenediamine (PPD) is preferably 70 to 98 mol%, more preferably 75 to 95 mol%, and even more preferably 80 to 93 mol%, based on the total molar amount of units derived from diamine component (B). It may be 83 mol% or more, 87 mol% or more, 92 mol% or less, or 88 mol% or less.

[0025] Furthermore, when the polyimide resin powder of the present invention contains units derived from 4,4'-diaminodiphenyl ether (ODA), the content of the units derived from 4,4'-diaminodiphenyl ether (ODA) is preferably 2 to 18 mol%, more preferably 5 to 17 mol%, and even more preferably 7 to 15 mol%, based on the total molar amount of units derived from diamine component (B). It may be 12 mol% or more, or 9 mol% or less. When the polyimide resin powder of the present invention contains units derived from 4,4'-diaminodiphenyl ether (ODA), the content of the units derived from p-phenylenediamine (PPD) is preferably 82 to 98 mol%, more preferably 83 to 95 mol%, and even more preferably 85 to 93 mol%, based on the total molar amount of units derived from diamine component (B). It may be 91 mol% or more, or 88 mol% or less.

[0026] In addition, in the polyimide resin powder of the present invention, the diamine component (B) constituting the units derived from the diamine component (B) may contain a diamine component other than the above-mentioned p-phenylenediamine (PPD), m-phenylenediamine (MPD), and 4,4'-diaminodiphenyl ether (ODA).

[0027] Examples of such other diamine components include aromatic diamines (diamine compounds having an aromatic group) and alicyclic diamines (diamine compounds having an alicyclic structure).

[0028] Examples of aromatic diamines include 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4''-diaminoterphenyl, 5(6)-amino-2-(4-aminophenyl)-benzimidazole, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,4-toluenediamine, 3,3'-dihydroxy-4,4'-diaminobiphenyl, bis(4-amino-3-carboxyphenyl)methane, 2,2'- Examples include bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2,3,5,6-tetrafluoro-1,4-diaminobenzene, 2,4,5,6-tetrafluoro-1,3-diaminobenzene, 2,3,5,6-tetrafluoro-1,4-benzene(dimethaneamine), 2,2'-difluoro(1,1'-biphenyl)-4,4'-diamine, 4,4'-diaminooctafluorobiphenyl, and 4,4'-oxybis(2,3,5,6-tetrafluoroaniline).

[0029] Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclobutane, and 1,4-bis(aminomethyl)cyclohexane. , 1,3-bis(aminomethyl)cyclohexane, diaminobicycloheptane, diaminomethylbicycloheptane, diaminooxybicycloheptane, diaminomethyloxybicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobiindane.

[0030] In the case where the polyimide resin powder of the present invention contains units derived from other diamine components, the content of the units derived from other diamine acid components is preferably 3 to 28 mol %, more preferably 5 to 20 mol %, based on the total molar amount of units derived from diamine component (B).

[0031] The polyimide resin powder of the present invention has a crystallinity of preferably 25 to 36%, more preferably 25 to 30%, and even more preferably 25 to 28%, as measured by wide-angle X-ray diffraction. A crystallinity within this range can improve the toughness of a molded product without significantly reducing heat resistance, thereby more appropriately enhancing the effect of suppressing cracking and chipping during processing of the molded product.

[0032] The polyimide resin powder of the present invention preferably has an average primary particle diameter of 3 to 15 μm, more preferably 4 to 13 μm, and even more preferably 5 to 12 μm. By setting the average primary particle diameter within the above range, the mechanical strength of the resulting polyimide molded article can be further increased. In the present invention, the average primary particle diameter can be measured by observing the polyimide resin powder with a scanning electron microscope (SEM) and using the obtained SEM image. Specifically, the average primary particle diameter can be determined by using the obtained SEM image to identify each polyimide resin particle (primary particle) constituting the polyimide resin powder, measuring the particle diameter of each polyimide resin particle, and averaging the measured particle diameters (primary particle diameters). In this case, the particle diameters of at least 50 random polyimide resin particles are measured, and the average value is calculated from the obtained measurement results.

[0033] Furthermore, the polyimide resin powder of the present invention preferably has a volume average particle diameter, as measured by a laser diffraction / scattering method, of 5 to 100 μm, more preferably 6 to 80 μm, and even more preferably 7 to 70 μm. By setting the volume average particle diameter within the above range, the mechanical strength of the resulting polyimide molded article can be further improved. The volume average particle diameter can be determined by measurement by a laser diffraction / scattering method using a laser diffraction / scattering particle size distribution analyzer. When primary particles are aggregated, the laser diffraction / scattering method usually measures the aggregate particle diameter (secondary particle diameter).

[0034] The method for producing the polyimide resin powder of the present invention is not particularly limited, but examples thereof include a method in which the above-mentioned tetracarboxylic acid component (A) and the above-mentioned diamine component (B) are polymerized in a solvent to obtain a polyamic acid solution, and the obtained polyamic acid solution is subjected to an imidization reaction.

[0035] First, the tetracarboxylic acid component (A) and the diamine component (B) are polymerized to obtain a polyamic acid. The polyamic acid preferably contains a repeating unit represented by the following general formula (1): In the general formula (1), A represents two or more tetravalent groups obtained by removing a carboxyl group from the tetracarboxylic acid component (A), and B represents two or more divalent groups obtained by removing an amino group from the diamine component (B).

[0036] The polyamic acid can be obtained by reacting approximately equimolar amounts of a tetracarboxylic acid component (A) and a diamine component (B) in a solvent, optionally with heating, until the desired viscosity (or molecular weight) is achieved. In the present invention, "approximately equimolar" means that the molar ratio of the tetracarboxylic acid component (A) to the diamine component (B) is about 0.90 to 1.10, preferably about 0.95 to 1.05.

[0037] The solvent used in the synthesis of polyamic acid is not particularly limited, and any known solvent used in the synthesis of polyamic acid can be selected and used. For example, from the viewpoint of the solubility of the tetracarboxylic acid component (A), the diamine component (B), and the polyamic acid, it is preferable to include at least one nitrogen-containing solvent. Furthermore, from the viewpoint of the thermal imidization reaction temperature, a solvent having a boiling point of 100°C or higher is preferable. Examples of such solvents include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, 1,1,3,3-tetramethylurea, 1,3-dimethyl-2-imidazolidinone, N,N-dimethylisobutyramide, and N,N-dimethylpropionamide.

[0038] The polyamic acid can be produced by adding the tetracarboxylic acid component (A), the diamine component (B), and a solvent to a reaction vessel equipped with a stirrer and stirring the mixture. The order of addition of these raw materials is not particularly limited. For example, a predetermined amount of the diamine component (B) may be dissolved in the solvent and then the tetracarboxylic acid component (A) may be added, or the tetracarboxylic acid component (A) may be dissolved in the solvent and then the diamine component (B) may be added, or the tetracarboxylic acid component (A) and the diamine component (B) may be added alternately to the solvent. If necessary, additives such as known reaction catalysts may be added at any timing.

[0039] The reaction temperature is not particularly limited, but is preferably 0°C or higher and 100°C or lower, more preferably 10°C or higher, and even more preferably 20°C or higher. Also, the reaction temperature is more preferably 90°C or lower, and even more preferably 70°C or lower. Adjusting the reaction temperature within the above range results in the production of a polyimide resin powder with little variation in coloration and mechanical properties. The temperature may be constant or may be increased or decreased as appropriate.

[0040] Next, the obtained polyamic acid solution is subjected to a known reaction, such as a thermal imidization reaction by heating or a chemical imidization reaction using an imidizing agent, to obtain a polyimide resin powder. These imidization reactions are preferably carried out under an inert gas atmosphere by flowing in an inert gas such as nitrogen gas or argon gas.

[0041] By carrying out the imidization reaction, it is preferable to obtain a polyimide resin powder containing, as a main component (50 mol % or more) a polyimide containing a repeating unit represented by the following general formula (2): The proportion of the repeating unit represented by the following general formula (2) in the polyimide resin powder is preferably 75 mol % or more, more preferably 90 mol % or more. In the above general formula (2), X １ represents two or more tetravalent groups obtained by removing a carboxyl group from the tetracarboxylic acid component (A), and Y １ are two or more types selected from divalent groups obtained by removing the amino group from the diamine component (B).

[0042] The reaction temperature for the thermal imidization reaction may be appropriately set depending on the solvent used, but it is usually preferable to carry out the reaction in the range of 130 to 230°C, and more preferably in the range of 140 to 190°C.

[0043] The imidizing agent used in the chemical imidization reaction can be a carboxylic acid anhydride such as acetic anhydride, propionic anhydride, succinic anhydride, phthalic anhydride, or benzoic anhydride. Acetic anhydride is preferred from the standpoints of cost and ease of removal after the reaction. The catalyst added during polyamic acid formation can be used as is, or it can be added anew or in addition after polyamic acid formation. The equivalent weight of the imidizing agent used is equal to or greater than the equivalent weight of the amide bond in the polyamic acid undergoing the chemical imidization reaction, preferably 1.1 to 5 times, and more preferably 1.5 to 4 times, the equivalent weight of the amide bond. Using a slight excess of the imidizing agent relative to the amide bond allows the imidization reaction to be carried out efficiently even at relatively low temperatures.

[0044] In order to reduce variations in the physical properties of the resulting polyimide molded article, the polyimide resin powder preferably has an imidization rate of 95% or more, more preferably 98% or more. The imidization rate may be measured by infrared spectroscopy according to a conventional method.

[0045] <Polyimide Molded Body> The polyimide molded body of the present invention can be obtained by molding the polyimide resin powder of the present invention described above. The polyimide molded body of the present invention may be obtained by molding and sintering the polyimide resin powder of the present invention. That is, in the present invention, the term "polyimide molded body" refers not only to a molded body obtained by molding polyimide powder into a predetermined shape, but also to a fired body or sintered body obtained by firing or sintering such a molded body, and the term "polyimide molded body" refers to a fired polyimide body or a sintered polyimide body.

[0046] The method for molding the polyimide resin powder is not particularly limited, and examples thereof include a method in which the polyimide resin powder is filled into a mold and compression-molded and sintered by simultaneously or separately applying pressure and heat. Among these, from the viewpoint of improving the mechanical properties of the polyimide molded body and productivity, a method in which the polyimide resin powder is filled into a powder molding machine, molded into a predetermined shape by uniaxial molding at room temperature, and then sintered without pressure (so-called direct forming) is preferred. As described above, the polyimide resin powder of the present invention can effectively suppress the occurrence of cracks and chips during processing of a molded body. Therefore, even when uniaxial molding at room temperature is performed and then sintered without pressure, the occurrence of cracks and chips can be suppressed. In particular, even when heat-compression molding is performed, the occurrence of cracks and chips can be effectively suppressed, thereby appropriately improving productivity.

[0047] Alternatively, as a method for molding the polyimide resin powder, a method may be adopted in which compression molding and baking are carried out simultaneously by heat compression molding, in which pressure and heat are simultaneously applied to the polyimide resin powder.

[0048] Examples of apparatuses for producing polyimide molded articles in hot compression molding include a four-column hydraulic press, a high-pressure hot press, a WIP machine, etc. Alternatively, hot compression molding may be performed after preforming a preform using, for example, a wet-cleaning-in-place (WIP), a dry-cleaning-in-place (DIP), a high-pressure press, a hydraulic press, a rotary press, or a tablet machine.

[0049] The conditions for compression molding and firing are not particularly limited, but the pressure is preferably 50 to 600 MPa, more preferably 50 to 500 MPa, even more preferably 60 to 450 MPa, and even more preferably 70 to 400 MPa. The heating temperature is preferably 300 to 550°C, more preferably 350 to 530°C, and even more preferably 400 to 510°C. By setting the pressure and heating temperature within the above ranges, it is possible to further increase productivity while further suppressing the occurrence of cracks and chips.

[0050] Furthermore, when producing the polyimide molded article of the present invention, any filler can be mixed with the polyimide resin powder and used. The filler is not particularly limited, but examples include inorganic fillers such as glass fiber, ceramic fiber, boron fiber, glass beads, whiskers, diamond powder, alumina, silica, natural mica, synthetic mica, alumina, carbon black, silver powder, copper powder, aluminum powder, nickel powder, metal fiber, ceramic fiber, whiskers, silicon carbide, silicon oxide, alumina, magnesium powder, titanium powder, carbon fiber, and graphite, as well as organic fillers such as fluorine-containing resin and aramid fiber. These fillers may be used alone or in combination of two or more.

[0051] The amount of filler used can be selected depending on the application, but can be, for example, in the range of 1 to 50 mass % based on the weight of the polyimide resin powder.

[0052] The polyimide molded article of the present invention has high mechanical properties, and thus, by taking advantage of these properties, can be suitably used as parts for semiconductor manufacturing equipment, such as pins, guides, evaluation sockets, and vacuum pads for semiconductor manufacturing-related equipment; automotive and aerospace parts, such as bushings, seal rings, trust washers, bearing retainers, piston rings, and lock nut inserts; and aerospace parts, such as bearing sleeves, roller bushings, and piston rings for industrial machinery-related equipment.

[0053] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these. Measurement methods used in the following examples are shown below.

[0054] <Average primary particle diameter of polyimide resin powder> The polyimide resin powder was observed with a scanning electron microscope (SEM), and using the obtained SEM image, the particle diameters of 50 polyimide resin particles constituting the polyimide resin powder were measured, and the measured particle diameters were averaged to determine the average primary particle diameter of the polyimide resin powder.

[0055] <Volume Average Particle Diameter of Polyimide Resin Powder> Using polyimide resin powder as a test sample, the volume average particle diameter was measured using a laser diffraction / scattering particle size distribution analyzer (product name "LA-920", manufactured by HORIBA).

[0056] <Crystallization degree of polyimide resin powder> The polyimide resin powder was measured using an X-ray diffractometer (product name: fully automatic horizontal sample multipurpose X-ray diffractometer SmartLab, manufactured by Rigaku Corporation). The X-ray diffraction spectrum obtained by the measurement, measured by wide-angle X-ray diffraction (WAXS), was analyzed by the area intensity ratio method to determine the crystallinity. In this example, the crystallinity was evaluated according to the following criteria: ⊚: The crystallinity was 25% or more and 28% or less. ◯: The crystallinity was more than 28% and 36% or less. ×: The crystallinity was more than 36% or could not be measured.

[0057] <Flexural Strength and Flexural Modulus of Polyimide Molded Article> The flexural strength and flexural modulus of the polyimide molded article were measured using a flexural strength tester at room temperature and a test speed of 0.5 mm / min. The measurement was performed six times, and the average values ​​were used as the flexural strength and flexural modulus values. In this example, the flexural strength and flexural modulus were evaluated according to the following criteria. (Flexural Strength) ◎: 70 MPa or more ◯: 28 MPa or more and less than 70 MPa ×: Less than 28 MPa (Flexural Modulus) ◎: 1.5 GPa or more ◯: 0.9 GPa or more and less than 1.5 GPa ×: Less than 0.9 GPa

[0058] <Cutting resistance value of polyimide molded body> For each polyimide molded body, two holes (referred to as hole A and hole B) were drilled using a machining center (DMG Mori Seiki, NV5000α) with a drill (drill diameter: 2 mm, rotation speed: approximately 6000 rpm). During the drilling process, the cutting resistance was measured using a rotary dynamometer (Kistler, 9170A). The average cutting resistance values ​​for the ranges excluding the 10% immediately after the start of cutting and the 10% immediately before the end of cutting when machining hole A and hole B of each polyimide molded body were obtained, and the average cutting resistance value for hole A and the average cutting resistance value for hole B were averaged to calculate the average cutting resistance value. In this example, the average cutting resistance value was evaluated according to the following criteria. It can be determined that the lower the average cutting resistance value, the more effectively cracking and chipping can be suppressed when machining the molded body. ◎: 15N or less ○: More than 15N, 20N or less ×: More than 20N

[0059] Example 1 3825.00 g of N-methyl-2-pyrrolidone (NMP), 456.17 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 34.34 g of 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), 167.70 g of p-phenylenediamine (PPD), and 12.62 g of m-phenylenediamine (MPD) were placed in a stirring vessel equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred under a nitrogen atmosphere at 70°C for 30 minutes to react, yielding a polyimide precursor solution (polyamic acid solution). The molar ratio of s-BPDA:a-BPDA:PPD:MPD was 93:7:93:7.

[0060] The resulting polyimide precursor solution was then heated to 190°C and stirred for 120 minutes to allow the thermal imidization reaction to proceed, resulting in the precipitation of a polyimide resin powder. The precipitated powder was filtered, washed once with IPA, and filtered again. It was then dried in a vacuum oven at 50°C for 3 hours and then at 150°C for 2 hours. It was then dried in an atmospheric oven at 260°C for 2 hours to obtain aromatic polyimide powder A. The resulting aromatic polyimide resin powder A was subjected to crystallinity measurement according to the method described above. The results are shown in Table 1. The ratio of units derived from the tetracarboxylic acid component (A) and units derived from the diamine component (B) constituting the polyimide resin powder was substantially the same as the ratio of the tetracarboxylic acid component (A) and diamine component (B) used (this also applies to Examples 2 to 9 and Comparative Examples 1 to 6, which will be described later).

[0061] Aromatic polyimide powder A was uniaxially molded at room temperature under a pressure of 293 MPa for 1 minute using a powder molding machine to obtain an aromatic polyimide molded body measuring 5 mm wide x 40 mm long x 4 mm thick. The resulting aromatic polyimide molded body was then subjected to pressureless baking in an air atmosphere under the following temperature conditions: Heating rate: 10°C / min, First holding temperature: 50°C, First holding time: 30 minutes, Baking temperature: 500°C, Baking time: 15 minutes. The resulting polyimide molded body was then subjected to measurements of bending strength, bending modulus, and cutting resistance according to the methods described above. The results are shown in Table 1.

[0062] [Examples 2, 3, and 4] Polyimide resin powders and polyimide molded articles were obtained and evaluated in the same manner as in Example 1, except that the amounts of p-phenylenediamine (PPD) and m-phenylenediamine (MPD) used were changed so that the ratios (molar ratios) of the respective compounds were as shown in Table 1. The results are shown in Table 1.

[0063] [Examples 5 and 6] Polyimide resin powders and polyimide molded products were obtained and evaluated in the same manner as in Example 1, except that 4,4'-diaminodiphenyl ether (ODA) was used instead of m-phenylenediamine (MPD) and the proportions (molar ratios) of the compounds including p-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (ODA) were changed to those shown in Table 1. The results are shown in Table 1.

[0064] Example 7 A polyimide resin powder and a polyimide molded product were obtained and evaluated in the same manner as in Example 1, except that the amounts of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) used were changed, 4,4'-diaminodiphenyl ether (ODA) was used instead of m-phenylenediamine (MPD), and the proportions (molar ratios) of the respective compounds were changed to those shown in Table 1. The results are shown in Table 1.

[0065] Example 8 A polyimide resin powder and a polyimide molded product were obtained and evaluated in the same manner as in Example 1, except that the amounts of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) used were changed so that the ratios (molar ratios) of the respective compounds were as shown in Table 1. The results are shown in Table 1.

[0066] Example 9 Polyimide resin powder and polyimide molded products were obtained and evaluated in the same manner as in Example 1, except that the amounts of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), p-phenylenediamine (PPD), and m-phenylenediamine (MPD) used were changed so that the proportions (molar ratios) of the respective compounds were as shown in Table 1. The results are shown in Table 1.

[0067] Comparative Examples 1 and 2 Polyimide resin powder and polyimide molded products were obtained and evaluated in the same manner as in Example 1, except that the amounts of p-phenylenediamine (PPD) and m-phenylenediamine (MPD) used were changed so that the ratios (molar ratios) of the respective compounds were as shown in Table 2. The results are shown in Table 2.

[0068] [Comparative Examples 3 and 4] Polyimide resin powder and polyimide molded products were obtained and evaluated in the same manner as in Example 1, except that 4,4'-diaminodiphenyl ether (ODA) was used instead of m-phenylenediamine (MPD), and the amounts of p-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (ODA) used were changed so that the proportions (molar ratios) of the respective compounds were as shown in Table 2. The results are shown in Table 2.

[0069] Comparative Example 5 A polyimide resin powder and a polyimide molded product were obtained and evaluated in the same manner as in Example 1, except that the amounts of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), p-phenylenediamine (PPD), and m-phenylenediamine (MPD) used were changed so that the proportions (molar ratios) of the respective compounds were as shown in Table 2. The results are shown in Table 2.

[0070] Comparative Example 6 A polyimide resin powder and a polyimide molded product were obtained in the same manner as in Example 1, and evaluated in the same manner, except that the amounts of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) used were changed, 4,4'-diaminodiphenyl ether (ODA) was used instead of m-phenylenediamine (MPD), and the amounts of p-phenylenediamine (PPD) and 4,4'-diaminodiphenyl ether (ODA) used were changed so that the proportions (molar ratios) of the respective compounds were as shown in Table 2. The results are shown in Table 2.

[0071]

[0072]

[0073] As shown in Table 1, the units derived from the tetracarboxylic acid component (A) include units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), and the units derived from the diamine component (B) include 70 to 98 mol % of units derived from p-phenylenediamine (PPD) and 2 to 30 mol % of units derived from m-phenylenediamine (MPD) and / or 4,4'-diaminodiphenyl ether (ODA). Polyimide resin powder containing 18 mol% or less of units derived from diaminodiphenyl ether (ODA) had a crystallinity of 25% to 36% as measured by wide-angle X-ray diffraction. The resulting polyimide molded articles had a low average cutting resistance of 20 N or less, which effectively prevented cracking and chipping during processing (e.g., cutting) while maintaining good mechanical strength. The resulting polyimide molded articles also had high flexural strength and flexural modulus, resulting in excellent mechanical properties. In Example 9 and Comparative Examples 2, 5, and 6, the boundaries of the average primary particles were unclear on SEM images, making it impossible to measure the average primary particle diameter.

[0074] Furthermore, in Examples 8 and 9, the crystallinity of the polyimide resin powder was in the range of 25% or more and 36% or less, and therefore, the obtained polyimide molded body is considered to have an average cutting resistance of 20 N or less, similar to Examples 1 to 7, and similarly, it is considered that the occurrence of cracks and chips when processing the molded body (for example, when processing by cutting processing) can be effectively suppressed while maintaining good mechanical strength.

[0075] The polyimide resin powder of the present invention is suitably used for producing polyimide molded articles for various applications.

Claims

1. A polyimide resin powder comprising units derived from a tetracarboxylic acid component (A) and units derived from a diamine component (B), wherein the units derived from the tetracarboxylic acid component (A) include units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride and units derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride, and the units derived from the diamine component (B) include units derived from p-phenylenediamine, units derived from m-phenylenediamine and / or units derived from 4,4'-diaminodiphenyl ether, and the content of the units derived from p-phenylenediamine is 70 to 98 mol% based on the total molar amount of the units derived from the diamine component (B), a polyimide resin powder in which the total content of the units derived from m-phenylenediamine and the units derived from 4,4'-diaminodiphenyl ether is 2 to 30 mol % based on the total molar amount of the units derived from diamine component (B), and the content of the units derived from 4,4'-diaminodiphenyl ether is 18 mol % or less based on the total molar amount of the units derived from diamine component (B).

2. The polyimide resin powder according to claim 1, wherein the content of units derived from 3,3',4,4'-biphenyltetracarboxylic dianhydride is 80 to 98 mol % and the content of units derived from 2,3,3',4'-biphenyltetracarboxylic acid is 2 to 20 mol % based on the total molar amount of units derived from the tetracarboxylic acid component (A).

3. The polyimide resin powder according to claim 1 or 2, which has a crystallinity of 25 to 36% as measured by wide-angle X-ray diffraction.

4. A polyimide molded article obtained by molding the polyimide resin powder according to claim 1 or 2.

5. A method for producing the molded article according to claim 4, comprising the steps of compressing and molding the polyimide resin powder at a pressure of 50 to 500 MPa and firing the polyimide resin powder at a temperature of 300 to 550°C.

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