JP4929676B2 - Method for producing polyimide resin powder and polyimide resin molded body - Google Patents

Description

The present invention relates to a polyimide resin powder which can be formed into a molded article of polyimide having excellent heat resistance, particularly polyimide benzoxazole, and a method for producing a polyimide resin molded article.

Polyimide resins are known to vary in various properties depending on their chemical structure, and in particular, wholly aromatic polyimides have recently been used in the electronics, electrical industry, automotive industry, due to their excellent heat resistance, mechanical properties, and sliding properties. It is one of the engineering plastics attracting attention in the space and aviation industries, and high demand is expected.
In general, wholly aromatic polyimide does not have a heat softening point and is insoluble in a solvent, so it is often difficult to mold. For this reason, various studies have been conducted for the purpose of improving these problems. It was. Some polyimide resins obtained from monomers having a structural formula having a flexible chain in the molecular skeleton are known as so-called thermoplastic polyimides having a thermal softening point. However, even if the thermoplastic polyimide resin can be melted, the temperature is high and the viscosity is very high. Therefore, injection molding and extrusion molding using an extruder that are usually used for molding thermoplastic resins can be used. First, the molding is performed by applying the powder molding technique and the firing technique which are employed for molding powder metal and ceramic. Such thermoplastic polyimides have limited heat resistance, and many of the components that are copolymerized for the purpose of developing thermoplasticity are soft components, and the hardness and elastic modulus of the molded product are low, and the mechanical properties are satisfactory. It is not possible.
The molded body of polyimide is formed by, for example, compression molding an aromatic polyimide powder to form a green compact, and then sintering in an inert atmosphere such as nitrogen in a non-pressure state ( Patent Document 1).
Japanese Patent Publication No.49-005737

  A method for producing aromatic polyimide pieces and powders, which are a kind of heat-resistant polymer, is, for example, a method in which an aromatic polyimide powder is obtained by heating a polyamic acid solution in the presence of a tertiary amine (see Patent Documents 2 and 3), In addition, an equimolar amount of the biphenyltetracarboxylic acid component and the aromatic diamine component is stirred with a uniform solution having a low rotational viscosity, which is dissolved at a temperature lower than 155 ° C. in an amide solvent in which the resulting polyimide is not dissolved by 1 mass% or more. While heating to a temperature of 160 ° C. to 300 ° C. for a short time, maintaining the temperature within the above range to produce an aromatic polyimide having a logarithmic viscosity of 0.2 to 1, and depositing it as fine particles (Refer to Patent Document 4), at least one aromatic tetracarboxylic dianhydride capable of forming polyimide, and at least one aromatic polyily the same amount as this Cyanate is heat-polymerized in an organic solvent having a polar solvent as a main component at a temperature of 100 to 200 ° C. to precipitate the polyimide particles in a slurry state, and the polyimide particles are filtered or centrifuged. A method for producing a polyimide powder to obtain a spherical porous polyimide powder having an average particle size of 1 to 20 μm, which is washed with an organic solvent having a polar solvent as a main component as described above (see Patent Document 5), and polyamic acid in a good solvent The solution is dissolved in a polyamic acid solution, heat-treated at a temperature of 100 ° C. to 400 ° C. to precipitate polyimide particles in the solvent, the average particle size is 200 μm or less, and the crystallinity of the polymer by X-ray diffraction is A production method for directly collecting 50% or more of polyimide powder (see Patent Document 6), 30% or more of 2,3,3 ′, 4′-biphenyltetracar A partially esterified product of biphenyltetracarboxylic dianhydride containing an acid component is reacted with an aromatic diamine to separate and obtain the generated solid state polyimide precursor, preferably heated at 150 to 300 ° C. Many proposals have been made, such as a method for producing a polyimide powder that undergoes dehydration and ring closure (see Patent Document 7).

Furthermore, a polyimide molded body having excellent moldability and excellent mechanical properties can be obtained. As a polyimide precursor powder having excellent solubility in a solvent, tetracarboxylic acid is used as a solvent that does not strongly interact with the polyimide precursor. When the dianhydride is dissolved or suspended, and diamine is added for polymerization, the solvent can be easily removed, and the polyimide precursor powder obtained has an intrinsic viscosity of 0.7 dl / g or more. It has been disclosed to obtain a granular material (see Patent Document 8).
Japanese Examined Patent Publication No. 39-030060 Japanese Patent Laid-Open No. 04-142332 Japanese Patent Laid-Open No. 57-200452 Japanese Examined Patent Publication No. 61-026926 Japanese Patent Laid-Open No. 07-033875 JP 2000-128893 A JP 05-271539 A

  However, all of the above polyimide resin powders are a method for obtaining a direct powder for obtaining a polyimide resin powder via a polyamic acid, etc., accompanied by separation / removal of the solvent, and the size and particles of the powder. There are many problems in controlling the diameter distribution. Furthermore, the method described in Patent Document 8 is a polymerization using a specific solvent close to a poor solvent, and is a very limited polyimide precursor powder, and the control during polymerization is extremely limited.

As a result of intensive studies, the present inventors can easily obtain a molded body of a polyimide resin excellent in heat resistance and mechanical properties, and are added to obtain the detachment of the solvent during molding and the ease of molding. The present invention has reached the present invention that can solve problems such as heat resistance due to thermoplastic polyimide and lowering of mechanical properties.
That is, the present invention has the following configuration.
1. A polyimide resin powder containing 0.1 to 3.0% by mass of a heated volatile component obtained by heating imidization treatment of a polyamic acid mainly composed of an aromatic diamine mainly having a benzoxazole skeleton and an aromatic tetracarboxylic acid.
2. Polyimide resin powder 34 having a heating volatile component of 0.1 to 3.0% by mass obtained by heating imidization treatment of a polyamic acid mainly composed of an aromatic diamine mainly having a benzoxazole skeleton and an aromatic tetracarboxylic acid. A method for producing a polyimide resin molded body, comprising mixing 95 parts by mass and 5 to 66 parts by mass of a polyimide precursor powder having a heating volatile component of 1 to 32% by mass, followed by pressure heating molding.
3. Polyimide resin powder 50 having a heating volatile component of 0.1 to 3.0% by mass obtained by heating imidization treatment of polyamic acid mainly composed of aromatic diamine having mainly benzoxazole skeleton and aromatic tetracarboxylic acid A method for producing a polyimide resin molded body, which comprises mixing ~ 95 parts by mass and 5 to 50 parts by mass of thermoplastic polyimide resin powder, followed by pressure and heat molding.

The molded body of the polyimide resin is obtained by pressurizing and heating a powder containing a thermoplastic polyimide resin in the manner of powder metallurgy. In general, a thermoplastic polyimide is copolymerized with a soft component, so that it is inferior in heat resistance and soft in mechanical properties, and its use is limited in applications where hardness and rigidity are required.
The diamines having a benzoxazole skeleton in the present invention have a high heat resistance and a rigid chemical structure, and have excellent mechanical properties and high heat resistance, especially when combined with aromatic tetracarboxylic acid anhydrides to form a polyimide. It becomes a polyimide resin. Since such a polyimide resin is insoluble and infusible, it is difficult to mold with a single component. However, the polyimide resin powder is blended with a predetermined polyamic acid resin powder or thermoplastic polyimide resin powder and heated. It can be set as the polyimide resin molding which has the outstanding mechanical characteristic and heat resistance by performing pressure molding. Surprisingly, even if a thermoplastic component is included in such a molded body, it exhibits sufficient heat resistance and is hardly soluble or infusible. It is suggested that a reaction has occurred.
Therefore, the molded product using the polyimide resin powder of the present invention is a molded product maintaining excellent heat resistance, mechanical properties, and sliding properties, and is an engineer plastic in the electronics / electric industry, automobile industry, space / aviation industry, etc. It can be used as and is extremely useful.

An aromatic diamine (diamine or derivative thereof) mainly having a benzoxazole skeleton according to the present invention and a polyamic acid obtained mainly from aromatic tetracarboxylic acids (anhydrides, halides, acids, etc.) are subjected to heat imidization treatment. A polyimide resin powder having a heating volatile component of 0.1 to 3.0% by mass is, for example, a dispersion polymerization method in which both of them are reacted in a solvent (a good solubility medium of a polyamic acid solution that is a polyimide precursor, and is generated simultaneously. It can be obtained by pulverizing the polyamic acid in a solvent which is a poorly soluble medium of the polyimide resin to be obtained by chemical imidization or by heat imidization and then dispersing in a solvent, or by reacting the two in a solvent. Mixed polyamic acid (polyimide precursor) solution with poor solvent and filtered the precipitated polyimide precursor 1 to 45 wt%, preferably dried until 3-38 mass%, obtained by a method of obtaining a polyimide resin powder subjected to heat treatment at 250 to 550 ° C..
The particle size of the polyimide resin powder of the present invention is preferably 1 to 500 μm, more preferably 5 to 200 μm, in terms of volume average particle size. The shape is not particularly limited. From the viewpoint of preventing scattering and facilitating handling, it is a preferred embodiment to be processed into granules.

Furthermore, in this invention, it is essential that the heating volatile component of the resin powder obtained by heat processing of a polyimide precursor powder is 0.01-3.0 mass%, Furthermore, 0.01-1.2 mass% In addition, it is preferable that it is 0.01-0.6 mass%. When the heating volatile component contained in the resin powder exceeds this range, it may easily cause voids and blisters during molding, and the long-term stability of the powder and the molded product obtained from the powder may be impaired. Further, when the heating volatile component of the polyimide resin powder is smaller than this range, a long-time heat treatment is required, which is not economical, and the polyimide resin may be deteriorated.
Specific examples of the aromatic diamine having a benzoxazole structure used in the present invention include the following.

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above. These diamines may be used alone or in combination of two or more.
In the present invention, the aromatic diamine having the benzoxazole structure is preferably used in an amount of 70 mol% or more of the wholly aromatic diamines.

In the present invention, the following aromatic diamines may be used, but preferably one or two diamines having no benzoxazole structure exemplified below as long as they are less than 30 mol% of the total aromatic diamines. The polyamic acid or polyimide precursor powder used in combination is as described above.
Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine,

3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 3,4'- Diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, bis [4- (4-aminophenoxy) phenyl] methane, 1 , 1-Bis [4- (4-aminophen Enoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] propane, 1,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,3-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane,

1,1-bis [4- (4-aminophenoxy) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) Phenyl] butane, 2,2-bis [4- (4-aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) Phenyl] -2- [4- (4-aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- ( 4-aminophenoxy) phenyl] -2- [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphen Le] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane,

1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) ) Biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- ( 4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) phenyl] ether, 1,3-bis [4- (4-aminophenoxy) ) Benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (3- Aminophenoxy) benzoyl] benzene, 4,4′-bis [(3-aminophenoxy) benzoyl] benzene, 1,1-bis [4- (3-aminophenoxy) phenyl] propane, 1,3-bis [4- (3-aminophenoxy) phenyl] propane, 3,4'-diaminodiphenyl sulfide,

2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] methane, 1,1 -Bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, bis [4- (3-aminophenoxy) phenyl] sulfoxide, 4,4 '-Bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4'-bis [4- (4-amino-α) , Α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- 4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4- Aminophenoxy) phenoxy-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [ 4- (4-amino-6-fluorophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-methylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-amino-6-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

  3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4′-diamino-4-bipheno Cibenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino-4-phenoxybenzoyl) benzene 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino-4-biphenoxybenzoyl) ) Benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-amino-5) -Biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile and the above Some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or some or all hydrogen atoms of alkyl groups or alkoxyl groups are halogens. Examples thereof include aromatic diamines substituted with C1-C3 halogenated alkyl groups or alkoxyl groups substituted with atoms.

  The aromatic tetracarboxylic acids used in the present invention are preferably aromatic tetracarboxylic anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.
In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as they are less than 30 mol% of the total aromatic tetracarboxylic acids. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene-2,3 5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-3 -(1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride.

Bicyclo [2.2.1] heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1 , 3-Dipropylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2.1] Heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and the like. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

  The solvent used when polymerizing (reacting) an aromatic diamine and an aromatic tetracarboxylic acid to obtain a polyamic acid is particularly limited as long as it can dissolve both the raw material monomer and the polyamic acid to be produced. Although not preferred, polar organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide Hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols and the like. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 30% by mass.

Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for 30 minutes. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines.
The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). And from the stability point of liquid feeding, Preferably it is 20-2000 Pa.s, More preferably, it is 200-1000 Pa.s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 3.0 dl / g or more, and more preferably 4.0 dl / g or more.

Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.
The above polyamic acid can be provided with or improved other functions such as slipperiness by adding a fine lubricant to the surface of the polyimide resin molded body by adding a lubricant to the solution.
As the lubricant, inorganic or organic fine particles having a volume average particle diameter of about 0.03 μm to 3 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate. , Magnesium oxide, calcium oxide, clay mineral and the like.

As a method for obtaining a molded body using the polyimide resin powder of the present invention, polyimide resin powder and 5 to 66 parts by mass of polyimide precursor powder having a heating volatile component of 1 to 32% by mass are mixed and heated under pressure. A molding method can be preferably applied.
The polyimide precursor powder used in the method for producing a polyimide resin molded body of the present invention is prepared by, for example, mixing a polyamic acid solution with a poor polyamic acid solvent, filtering the precipitated resin component, and heating volatile components of 1 to 32. It can be obtained by drying to a mass%. Here, the heated volatile component is mainly a solvent (illustrated above) used at the time of producing the polyamic acid, a poor solvent, and water generated during the dehydration ring-closing reaction.
The poor solvent is not particularly limited as long as it does not dissolve the polyamic acid, but it may be a single type selected from alcohols, ketones, ethers, aromatic solvents, or a mixed solvent composed of a combination thereof. It doesn't matter. Further, various other solvents may be mixed with the above solvent and used as a reaction solvent within the range not impeding the practice of the present invention.

Examples of alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, , 4-butanediol, 2,3-butanediol, 1,5-pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, glycerin, 2-ethyl-2- ( Hydroxymethyl) -1,3-propanediol, 1,2,6-hexanetriol and the like.
Examples of ethers include dioxane, tetrahydrofuran, trioxane, 1,2-dimethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethoxyethanol, and 2-isopropoxy. Ethanol, 2-butoxyethanol, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monoethyl ether, tetraethylene glycol, 1-methoxy-2-propanol, dipropylene glycol, diethylene glycol Propylene glycol monomethyl ether, dipropylene Recall monoethyl ether, tripropylene glycol monomethyl ether, and polypropylene glycol.
Examples of ketones include acetone and methyl ethyl ketone.
Examples of aromatic solvents include toluene and xylene.
Of these solvent species, methyl alcohol, acetone or dioxane is particularly preferred in the present invention.
The particle size of the polyimide precursor powder is 1 to 500 μm, preferably 5 to 200 μm, in terms of volume average particle size. The shape is not particularly limited. From the viewpoint of preventing scattering and facilitating handling, it is a preferred embodiment to be processed into granules.

In order to improve various properties of the polyimide obtained as described above, an inorganic or organic filler can be blended, and the blending of the filler can be carried out in the necessary amount during the polyamic acid polymerization reaction or after polyamic acid polymerization. Examples thereof include a method of adding to a solution, a method of blending after making a powder, a method of blending immediately before molding, and the like. In the present invention, it is particularly preferable to add a filler during the polyamic acid polymerization reaction or into the polyamic acid solution after polyamic acid polymerization. The addition amount of the filler is preferably about 0.1 to 50% by mass with respect to the polyamic acid.
As a method of obtaining a molded body using the polyimide resin powder of the present invention, a method in which 50 to 95 parts by mass of polyimide resin powder and 5 to 50 parts by mass of thermoplastic polyimide resin powder are mixed and pressure-heat-molded is also preferable. Applicable. As the thermoplastic polyimide resin powder, known polyether imide resins, polyamide imide resins, polyester imide resins, and other polyimide resins copolymerized with flexible components can be used. The particle size of the thermoplastic polyimide resin powder is 1 to 500 μm, preferably 5 to 200 μm, in terms of volume average particle size. The shape is not particularly limited. From the viewpoint of preventing scattering and facilitating handling, it is a preferred embodiment to be processed into granules.
The shape of the polyimide resin molding obtained by subjecting the polyimide precursor powder of the present invention to molding heat treatment is not particularly limited, but is preferably a structural material such as a sheet, a round bar or a flat plate, or a component having a complicated shape.
Further, in the present invention, various powder molding methods such as a commonly performed powder molding method, particularly a fluid immersion method, an electrostatic coating method, a powder spraying method, a powder rotation molding method, and a powder slush molding method are employed. be able to.

Evaluation methods used in Examples and the like are as follows.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. using an Ubbelohde type viscosity tube.

2. Volume average particle size The powder was dispersed in ion-exchanged water to which 0.1% by mass of sodium dodecylbenzenesulfonate was added using an ultrasonic cleaner, and a laser scattering particle size distribution analyzer LB-500 (manufactured by Horiba Ltd.) It was measured by.

3. Heating volatile component Measurement of the heated volatile component was performed by using a DSC measuring device to obtain a mass loss under the condition of raising the temperature from room temperature to 200 ° C at a rate of 5 ° C / min and holding at 200 ° C for 60 minutes, Calculated by the following formula.
Heated volatile component (%) = {(initial mass−mass after heating) / (initial mass)} × 100

[Example 1]
Nitrogen introduction tube, thermometer, vessel wetted part equipped with stirring rod, and infusion pipe were replaced with nitrogen in the reaction vessel of austenitic stainless steel SUS316L, and then 5-amino-2- (p-aminophenyl) ) Snowtex (registered trademark) DMAC-ST30 (Nissan Chemical Co., Ltd.) obtained by adding 223 parts by mass of benzoxazole and 4416 parts by mass of N, N-dimethylacetamide and completely dissolving it, and then dispersing colloidal silica in dimethylacetamide 40.5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at a reaction temperature of 25 ° C. for 24 hours. A was obtained. Ηsp / C of this product was 4.0 dl / g.
100 parts by mass of the obtained polyamic acid solution A was gently added dropwise to 1000 parts by mass of methanol under stirring at 25 ° C., and the coagulum was collected with a suction funnel. Next, the solidified product was washed with 1000 parts by mass of methanol, and filtered again with a suction funnel to obtain a polyamic acid crude powder. The obtained coarse powder was dried at 110 ° C. for 12 hours in a vacuum dryer and crushed in an agate mortar to obtain 11.8 parts by mass of polyimide precursor powder (a1).
The heating volatile component of the obtained polyimide precursor powder was 31 mass%.
Further, the obtained polyimide precursor powder was heated at 160 ° C. for 30 minutes using a muffle furnace, then heated to 420 ° C. at 20 ° C./min and held for 45 minutes, then cooled to room temperature, A polyimide resin powder (A1) was obtained. The obtained polyimide resin powder (A1) had a volume average particle diameter of 42 μm and a heating volatile component of 1.6% by mass.

[Example 2]
550 parts by mass of the same polyamic acid solution A as in Example 1 was gently stirred, and 3.2 parts by mass of triethylamine and 38.5 parts by mass of acetic anhydride were added dropwise thereto and stirring was continued for 10 hours. 10. Yellow-brown polyimide resin powder is precipitated in the system, and the slurry is filtered through a suction funnel, washed with methanol, dried at 130 ° C. for 12 hours, crushed in an agate mortar, 8 mass parts polyimide precursor powder (a2) was obtained.
The heating volatile component of the obtained polyimide precursor powder (a2) was 26 mass%.
Further, the obtained polyimide precursor powder was heated at 160 ° C. for 30 minutes using a muffle furnace, then heated to 510 ° C. at 20 ° C./min and held for 15 minutes, and then cooled to room temperature. 8 parts by mass of a brown polyimide resin powder (A2) was obtained. The obtained polyimide resin powder (A2) had a volume average particle size of 28 μm and a heating volatile component of 0.2% by mass.

[Comparative Example 1]
The liquid contact part of the vessel equipped with a nitrogen introduction tube, a thermometer, a stirring rod, and the pipe for infusion were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of diaminodiphenyl ether was added. Next, 4170 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then Snowtex (registered trademark) DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) in which colloidal silica was dispersed in dimethylacetamide. When 40.5 parts by mass (including 8.1 parts by mass of silica) and 217 parts by mass of pyromellitic dianhydride are added and stirred at 25 ° C. for 5 hours, a brown viscous polyamic acid solution B is obtained. Obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g.
Thereafter, the same operation as in Example 1 was performed to obtain a polyimide precursor powder (b) having a heating volatile component content of 33% by mass. Furthermore, it heat-processed similarly to Example 1 and obtained the polyimide resin powder (B). The obtained polyimide powder (B) had a volume average particle size of 35 μm and a heating volatile component of 2.2% by mass.

[Comparative Example 2]
The wetted part of the vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, and the infusion piping were substituted with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 108 parts by mass of phenylenediamine was added. Next, Snowtex (registered trademark) DMAC-ST30 (manufactured by Nissan Chemical Industries, Ltd.) obtained by dispersing 4010 parts by mass of N-methyl-2-pyrrolidone and completely dissolving the colloidal silica in dimethylacetamide. When 40.5 parts by mass (including 8.1 parts by mass of silica) and 292.5 parts by mass of diphenyltetracarboxylic dianhydride are added and stirred at 25 ° C. for 12 hours, a brown viscous polyamic acid solution C was obtained. The reduced viscosity (ηsp / C) was 4.5 dl / g. Thereafter, the operation was performed in the same manner as in Example 2 to obtain a polyimide precursor powder (c) having a heating volatile component content of 27% by mass. Furthermore, it heat-processed similarly to Example 2 and obtained the polyimide resin powder (C). The obtained polyimide resin powder (C) had a volume average particle diameter of 33 μm and a heating volatile component of 0.7% by mass.

[Comparative Example 3]
Using the same polyamic acid solution as in Example 1, the same operation as in Example 1 was performed to obtain a polyimide precursor powder (a3) having a heated volatile component of 31% by mass. Further, the obtained polyimide precursor powder was heated at 130 ° C. for 30 minutes using a muffle furnace, then heated to 380 ° C. at 20 ° C./min and held for 5 minutes, then cooled to room temperature, 48. 3 parts by mass of a brown polyimide resin powder (A3) was obtained. The obtained polyimide resin powder (A3) had a volume average particle size of 51 μm and a heating volatile component of 3.7% by mass.

[Prototype of molded polyimide]
(Manufacture of thermoplastic polyimide resin powder)
A polyetherimide resin, ULTEM round bar made by GE Plastics Co., Ltd., is machined by cutting with a table lathe and further pulverized with a freezer mill to produce thermoplastic polyimide resin powder (E) Got. The obtained powder (E) had a volume average particle diameter of 18 μm and a heated volatile component of 2.3 mass%.
Polyimide resin powder and polyamic acid powder were mixed in the following combinations. The obtained mixed powder was pressed into a flat plate mold having a side of 100 mm and a thickness of 15 mm, and pressed at 300 ° C. and 150 kg / cm ² to obtain a molded body having a thickness of 3 mm.
Hereinafter, the bending strength and bending elastic modulus of the obtained molded body were measured and evaluated by a method based on JIS K7171. The results are shown in Table 1.

The polyimide powder of the present invention can be molded with a high degree of freedom, and a polyimide resin molded body having practically sufficient strength can be obtained without distortion of the shape by heat treatment.
Also, the polyimide powder and the polyimide precursor powder of the present invention are mixed and pressure-heat molded, or the polyimide resin molded body is mixed with the polyimide resin powder and the thermoplastic polyimide resin powder and pressure-heat-molded. Polyimide resin moldings obtained in this way can be used as engineering plastics in the electronics, electrical, automotive, space, aviation industries, etc., with excellent heat resistance, mechanical properties, and sliding properties maintained. Can be extremely useful.

Claims (3)

A polyamic acid mainly composed of an aromatic diamine having a benzoxazole skeleton and mainly an aromatic tetracarboxylic acid is heated and imidized, and the rate is 5 ° C./min from room temperature to 200 ° C. using a DSC measuring apparatus. The polyimide resin powder whose heating volatile component computed by the following formula is 0.01-3.0 mass% which calculated | required the mass loss on the conditions which heat up and hold | maintain for 60 minutes at 200 degreeC.

A polyamic acid mainly composed of an aromatic diamine having a benzoxazole skeleton and mainly an aromatic tetracarboxylic acid is heated and imidized, and the rate is 5 ° C./min from room temperature to 200 ° C. using a DSC measuring apparatus. The polyimide resin powder 34-95 mass whose heating volatile component computed by the following formula is 0.01-3.0 mass% was calculated | required in the temperature hold | maintained at 200 degreeC and hold | maintaining for 60 minutes. And a polyimide precursor powder having a heat volatile component content of 1 to 32% by mass obtained by the above method and mixed with pressure and heat molding, and a method for producing a polyimide resin molded body.

A polyamic acid mainly composed of an aromatic diamine having a benzoxazole skeleton and mainly an aromatic tetracarboxylic acid is heated and imidized, and the rate is 5 ° C./min from room temperature to 200 ° C. using a DSC measuring apparatus. The polyimide resin powder 50-95 mass whose heating volatile component computed by the following formula was 0.01-3.0 mass% was calculated | required in the temperature hold | maintained at 200 degreeC and hold | maintaining for 60 minutes. And a polyimide resin molded body, wherein 5 to 50 parts by mass of thermoplastic polyimide resin powder are mixed and pressure-heat-molded.