JP5728681B2 - Nanocarbon-dispersed polyimide solution and composite material produced using the same - Google Patents

Description

  The present invention relates to a polyimide solution in which soluble polyimide is dissolved and nanocarbon is dispersed. In addition, the present invention relates to an application product using the solution, for example, a coating material, an adhesive, and a composite material such as a porous pellet, a precipitate, a molded body, a coating film, and a film using the same. Among these, the present invention relates to a porous pellet produced using the solution.

  Conventionally, many applications of polyimide have been developed because of its high heat resistance and insulation. Polyimide is a resin having high heat resistance, and further has an insulation property that is high enough to be used for flexible circuit boards and the like. However, due to its high insulating property, it has been desired to prevent static electricity due to static electricity. However, polyimide has a difficulty in compounding with other materials such as a carbon material. Generally, as a method for compounding a resin, for example, a method of melt kneading or a method of compounding by removing a solvent in a solution can be considered.

  In the case of melt kneading, polyimide generally has high heat resistance, so it has been difficult to melt and knead it. Even if kneading can be performed, the material does not melt unless the temperature is very high, so that other materials are thermally decomposed during kneading.

  On the other hand, in the case of using a solution, polyimide is generally an insoluble resin, so it is difficult to dissolve it in a solvent. Therefore, since it is difficult to prepare a solution, complexation by this method has been difficult.

  Therefore, as a method for making polyimide into a solution, a method has been proposed in which a polyamic acid solution, which is a polyimide precursor, is mixed with a CNT dispersion, and after film formation, an imidization reaction is performed to disperse CNT in the polyimide. (Patent Document 1).

  In addition, there is a method of synthesizing a soluble block copolymer polyimide by adopting a method of synthesizing a block copolymer by a sequential reaction as a method of directly producing a polyimide film from a soluble polyimide, not via a conventional polyamic acid. It is disclosed. In this method, there is disclosed a method in which specific monomers are once oligomerized and further subjected to a polymerization reaction (Patent Document 2).

JP 2004-107657 A International Publication No. 2008-155811 Pamphlet

In the method according to Patent Document 1, since a high temperature of 400 ° C. is required for the heat treatment when imidizing the polyamic acid, there is a problem of thermal decomposition. Further, since the imidization reaction is performed after film formation, there is a problem that water is generated with the reaction. Moreover, the surface resistance value obtained is as high as 1.0 * 10 < ⁵ > -1.0 * 10 < ¹² > (omega | ohm). Therefore, an object of the present invention is to provide a solution for compounding polyimide and nanocarbon and a composite material obtained from the solution.

This invention (1) contains the soluble polyimide which is a polymer with a tetracarboxylic dianhydride and a diamine compound, the solvent which melt | dissolves the said soluble polyimide, and the nanocarbon currently disperse | distributed in the said solvent, The nanocarbon-dispersed polyimide solution is a polyimide precipitate obtained by dropping the nanocarbon in a poor solvent having a lower solubility in the soluble polyimide than the solvent,
A skin layer formed on the surface and formed by fusing polyimide primary particles;
A core layer having a porous structure formed inside the skin layer,
Having pores of 1 to 50 nm in the gaps between the primary particles of the skin layer;
It is a polyimide porous pellet in which carbon nanotubes are dispersed in polyimide in the skin layer and the core layer.

This invention ( 2 ) is a polyimide deposit of the said invention ( 1 ) whose solvent of the said polyimide solution is N-methylpyrrolidone (NMP) and whose said poor solvent is water.

This invention ( 3 ) is the polyimide porous pellet of the said invention ( 1 ) or (2) whose thickness of the said skin layer is 50-100 nm.

This invention ( 4 ) is a molded object obtained by press-molding any one of the polyimide porous pellets of the inventions ( 1 ) to ( 3 ).

The present invention (5) contains a soluble polyimide, nanocarbon dispersed solvent to dissolve the soluble polyimide, and in the solvent which is a polymer of tetracarboxylic dianhydride and diamine compound, nano This is a method for producing a carbon-dispersed polyimide precipitate, which includes a step of obtaining a precipitate by dropping a carbon-dispersed polyimide solution into a poor solvent having a lower solubility in the soluble polyimide than in the solvent.

In the present invention ( 6 ), the concentration of the soluble polyimide in the nanocarbon-dispersed polyimide solution is in the range of 2 to 20% by weight,
It is a manufacturing method of the said invention ( 5 ) with which nanocarbon has disperse | distributed to the inside and surface of the said precipitate.

This invention ( 7 ) is a manufacturing method of the said invention ( 5 ) or ( 6 ) whose said solvent is N-methylpyrrolidone (NMP) and whose said poor solvent is water.

The present invention ( 8 ) is the production method according to any one of the inventions ( 5 ) to ( 7 ), wherein the nanocarbon is a carbon nanotube.

The present invention (9), the tetracarboxylic dianhydride is a benzophenone tetracarboxylic dianhydride,
The method according to any one of the inventions ( 5 ) to ( 8 ), wherein the diamine compound is 9,9-bis (4-aminophenyl) fluorene or bis [4- (3-aminophenoxy) phenyl] sulfone. It is.

  In the present invention, a soluble polyimide solution is prepared at a relatively low temperature of 200 ° C. or less by employing a soluble polyimide, and a CNT dispersion is mixed with the solution to solve the above-described problems. The resulting solution is dropped into a poor solvent to form porous pellets and powders, or the solution as it is or by mixing with various resin binders / adhesives, etc. And can be used for adhesives.

FIG. 1 is an explanatory view showing a manufacturing process of a polyimide porous pellet in which carbon nanotubes are dispersed. FIG. 2 (a) is an overall image of the porous pellet according to the present invention by an SEM photograph, FIG. 2 (b) is a sectional photograph of the porous pellet by SEM, and FIG. 2 (d) is an enlarged photograph of the internal cross section of the porous pellet, FIG. 2 (e) is an enlarged photograph of the internal cross section of the porous pellet, and FIG. 2 (f) is porous. It is an enlarged photograph of the internal cross section of a pellet. FIG. 3 is an enlarged photograph of the surface of the porous pellet.

(solution)
The solution according to the present invention is a polyimide solution in which nanocarbon is dispersed, including soluble polyimide, a solvent that dissolves the soluble polyimide, and nanocarbon dispersed in the solvent. By selecting a soluble polyimide, the solution according to the present invention was a polyimide solution and a solution in which nanocarbon was dispersed could be obtained. Soluble polyimide used in the present invention is a polymer of tetracarboxylic dianhydride and diamine compound.

  The tetracarboxylic dianhydride used in the soluble polyimide according to the present invention is not particularly limited. For example, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 1,3-bis (2,3-dicarboxyphenoxy) benzene dianhydride, 1,4-bis (2,3-dicarboxyphenoxy) ) Benzene dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,2 ′, 6,6′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4 '-Benzophenone tetracarboxylic dianhydride (BTDA), 2,3,3', 4'-benzophenone tetracarboxylic dianhydride, 2,2 ', 3,3'-benzophenone tetracarboxylic dianhydride, naphthalene -1 Aromatics such as 2,4,5-tetracarboxylic dianhydride, anthracene-2,3,6,7-tetracarboxylic dianhydride, phenanthrene-1,8,9,10-tetracarboxylic dianhydride Tetracarboxylic anhydride, aliphatic tetracarboxylic anhydride such as butane-1,2,3,4-tetracarboxylic dianhydride, cyclobutane-1,2,3,4-tetracarboxylic dianhydride, etc. Alicyclic tetracarboxylic anhydride, thiophene-2,3,4,5-tetracarboxylic anhydride, pyridine-2,3,5,6-tetracarboxylic anhydride, 4,4 ′-(hexafluoroisopropyl Heterocyclic tetracarboxylic anhydrides such as (Ridene) diphthalic dianhydride. From these, 1 type (s) or 2 or more types can be used.

  Although it does not specifically limit as a diamine compound used for the soluble polyimide which concerns on this invention, For example, 4,4'- diamino diphenyl methane (DDM), 4, 4'- diamino diphenyl ether (DPE), 4, 4'-bis ( 4-aminophenoxy) biphenyl (BAPB), 4,4′-bis (3-aminophenoxy) biphenyl, 1,4′-bis (4-aminophenoxy) benzene (TPE-Q), 1,3′-bis ( 4-aminophenoxy) benzene (TPE-R), 1,3-bis (3-aminophenoxy) benzene, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4, 4′-diaminodiphenyl sulfone, 3,4-diaminodiphenyl sulfone, 3,3′-di Aminodiphenylsulfone, bis [4- (3-aminophenoxy) phenyl] sulfone (BAPS-M), 4,4′-methylene-bis (2-chloroaniline), 3,3′-dimethyl-4,4′- Diaminobiphenyl, 4,4′-diaminodiphenyl sulfide, 2,6′-diaminotoluene, 2,4-diaminochlorobenzene, 1,2-diaminoanthraquinone, 1,4-diaminoanthraquinone, 3,3′-diaminobenzophenone, 3 , 4-diaminobenzophenone, 4,4′-diaminobenzophenone, 4,4′-diaminobibenzyl, R (+)-2,2′-diamino-1,1′-binaphthalene, S (+)-2,2 '-Diamino-1,1'-binaphthalene, 1,3-bis (4-aminophenoxy) alkane, 1,4-bis (4-a 1, n-bis (4-aminophenoxy) alkane (n is 3 to 10) such as 1,5-bis (4-aminophenoxy) alkane, n-bis [2- (4 -Aminophenoxy) ethoxy] ethane, aromatic diamines such as 9,9-bis (4-aminophenyl) fluorene (FDA), 1,2-diaminomethane, 1,4-diaminobutane, tetramethylenediamine, 1,5 -Aliphatic diamines such as diaminopentane, 1,6-diaminohexane, 1,8-diaminooctane, 1,10-diaminododecane, 1,11-diaminoundecane, 1,4-diaminocyclohexane, 1,2-diaminocyclohexane , Bis (4-aminocyclohexyl) methane, 4,4′-diaminodicyclohexylmethane, isophoronediamine, etc. Group diamines.

  Examples of the tetracarboxylic anhydride forming the soluble part of the soluble polyimide include 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA), 2,3,3 ′, 4′-benzophenonetetracarboxylic acid. It is preferable to use dianhydride, benzophenone tetracarboxylic dianhydride such as 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, or ethylene glycol-bis (anhydrotrimellitate). .

  As the diamine compound forming the soluble part of the soluble polyimide, 9,9-bis (4-aminophenyl) fluorene (FDA) or bis [4- (3-aminophenoxy) phenyl] sulfone (BAPS-M), It is preferred to use isophorone diamine.

  Examples of the solvent include aprotic polar solvents such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide (DMSO) and the like.

  Nanocarbon is dispersed in the polyimide solution according to the present invention. The nanocarbon-dispersed polyimide solution according to the present invention can be prepared by preparing a carbon dispersion in advance and mixing it with the polyimide solution. Hereinafter, the structure of the nanocarbon used in the present invention, the dispersant for dispersing the nanocarbon, and the dispersion will be described in detail.

  The “nanocarbon” of the solution of the present invention means carbon having a size of 1000 nm or less (preferably 500 nm or less) in the shape of the material. For example, carbon nanotubes (single-walled, double-walled, Multilayer type, cup stack type), carbon nanofiber, carbon nanohorn, fullerene, and graphene. Among these nanocarbons, carbon nanotubes are preferable. By using carbon nanotubes, a particularly remarkable effect of improving conductivity can be obtained. The carbon nanotube may be a single wall carbon nanotube (SWCNT) or a multi-wall carbon nanotube (MWCNT). The length of the carbon nanotube is preferably from 0.1 to 100 μm, more preferably from 0.1 to 50 μm, and further preferably from 0.1 to 20 μm. The diameter of the carbon nanotube is preferably 5 to 200 nm, more preferably 8 to 160 nm, and still more preferably 9 to 120 nm. In addition, the length and diameter of the tube are measured with respect to 100 or more structures existing within a predetermined range using an AFM (atomic force microscope), and set to a range in which 90% or more are included.

The dispersant is not particularly limited. For example, phospholipid surfactants, amphoteric surfactants, nonionic surfactants, anionic surfactants, cationic surfactants and other surfactants, Examples include host compounds that form inclusion compounds such as dextrins, and other naturally-occurring polymer compounds such as nucleic acids and proteins. “Phospholipid surfactants” are anionic and zwitterionic surfactants that have phosphate groups as functional groups, including phospholipids (including both glycerophospholipids and sphingophospholipids) Any of phospholipids (for example, hydrogenated phospholipids, lysophospholipids, enzyme-converted phospholipids, lysophosphatidylglycerol, and complexes with other substances) may be used. Such phospholipids are present in various membrane systems of the cells that make up organisms, such as the plasma membrane, nuclear membrane, endoplasmic reticulum membrane, mitochondrial membrane, Golgi membrane, lysosomal membrane, chloroplast membrane, and bacterial cell membrane. Preferably, phospholipids used for preparing liposomes are suitable. Specifically, for example, phosphatidylcholine {for example, distearoylphosphatidylcholine (DSPC), dimyristoylphosphatidylcholine (DMPC), dipalmitrylphosphatidylcholine (DPPC)}, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol, diphosphatidylglycerol Lysophosphatidylcholine and sphingomyelin. Particularly preferred surfactants are zwitterionic surfactants. Zwitterionic surfactants include quaternary ammonium base / sulfonic acid group (—SO ₃ H) type, quaternary ammonium base / phosphate group (soluble in water), quaternary ammonium base / phosphate group. Examples include amphoteric surfactants of the type (insoluble in water) and quaternary ammonium base / carboxyl group type. The acid group may be a salt. In particular, the zwitterionic surfactant preferably has both + and-charges in one molecule, and the acid dissociation constant (pKa) of the acid group is preferably 5 or less. More preferably, it is more preferably 3 or less. Specifically, 3-[(3-colamidopropyl) dimethylamino] -2-hydroxy-1-propanesulfonic acid (CHAPSO), 3-[(3-colamidopropyl) dimethylamino] -propanesulfonic acid ( CHAPS), N, N-bis (3-D-gluconamidopropyl) -colamide, n-octadecyl-N, N′-dimethyl-3-amino-1-propanesulfonic acid, n-decyl-N, N ′ -Dimethyl-3-amino-1-propanesulfonic acid, n-dodecyl-N, N'-dimethyl-3-amino-1-propanesulfonic acid, n-tetradecyl-N, N'-dimethyl-3-amino-1 -Propanesulfonic acid {Zwittergent (TM) -3-14}, n-hexadecyl-N, N'-dimethyl-3-amino-1-propanesulfonic acid, n-octadecyl-N Ammonium sulfobetaines such as N'-dimethyl-3-amino-1-propanesulfonic acid, n-octylphosphocholine, n-nonylphosphocholine, n-decylphosphocholine, n-dodecylphosphocholine, n-tetradecylphosphocholine Phosphocholines such as choline and n-hexadecylphosphocholine, phosphatidylcholines such as dilauroylphosphatidylcholine, dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine, distearoylphosphatidylcholine, dioleoylphosphatidylcholine, and dilinoleoylphosphatidylcholine.

  The solvent used in the dispersion is not particularly limited, but for example, aprotic such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide (DMSO), etc. Examples include polar solvents. In addition, it is suitable for the solvent of a nanocarbon dispersion liquid to use the same seed | species as the solvent used for said soluble polyimide solution. By using the same type, aggregation of dispersed nanocarbons is prevented, and aggregation of dissolved polyimide is also prevented.

  When nanocarbon is dispersed in an aprotic polar solvent, it is preferable to select a nonionic or zwitterionic surfactant as the dispersant. In the case where the dispersant is selected, the effect of stably dispersing the nanocarbon in the aprotic polar solvent is obtained.

  1-30 mass% is suitable with respect to the mass of the whole solution, content of soluble polyimide is more suitable 3-20 mass%, and 5-15 mass% is still more suitable. The content of nanocarbon is preferably 0.01 to 20% by mass, more preferably 0.1 to 10% by mass, and still more preferably 0.2 to 5% by mass with respect to the entire solution. .

  The weight ratio of soluble polyimide and nanocarbon can be set arbitrarily, but the content of nanocarbon relative to the total amount of soluble polyimide and nanocarbon ([nanocarbon mass] / ([nanocarbon mass] + [Soluble polyimide mass]) × 100) is preferably 1 to 90% by mass, more preferably 1 to 50% by mass, and even more preferably 1 to 10% by mass. Even with such a high nanocarbon ratio, it can be uniformly compounded with polyimide.

  Although the manufacturing method of the carbon dispersion polyimide solution which concerns on this invention is not specifically limited, For example, it can manufacture by the following process. The production method according to the present invention is, for example, a method including a step of preparing a soluble polyimide solution and a step of mixing the soluble polyimide solution and a nanocarbon dispersion. In addition, a carbon-dispersed polyimide solution can be obtained by dissolving solid soluble polyimide in the nanocarbon dispersion.

  In the step of preparing the soluble polyimide solution, the soluble polyimide may be directly dissolved in a solvent capable of dissolving the polyimide, but it is preferable to adjust by a method of polymerizing the soluble polyimide.

It is dissolved in an aprotic polar solvent to dissolve the tetracarboxylic acid dianhydride and a diamine compound. Tetracarboxylic dianhydride used herein, the diamine compound and the aprotic polar solvent can be used those described above.

  After dissolution, a catalyst may be added. The catalyst used here is not particularly limited as long as it is a polyimide polymerization catalyst, and examples thereof include toluenesulfonic acid, γ-valerolactone and pyridine, and γ-valerolactone and N-methylmorpholine. Polyimide can be synthesized without addition of a catalyst, but a high molecular weight can be obtained by adding a catalyst. Even if the molecular weight is low, it is not impossible to increase the molecular weight by heat treatment after film formation or molding.

Producing a polyimide is not particularly limited, can be synthesized in the usual manner, for example, a tetracarboxylic dianhydride is reacted with a diamine compound, after which to synthesize a polyamic acid, and subjected to dehydration reaction polyamide Can be obtained. The reaction conditions for synthesizing the polyamic acid are not particularly limited, but the temperature is preferably 0 to 120 ° C, more preferably 5 to 30 ° C. The reaction atmosphere may be air, but it is preferable that the reaction is performed in an atmosphere of an inert gas such as nitrogen gas or argon gas. Although reaction time is not specifically limited, For example, it is 0.5 to 48 hours. In this way, subjected to dehydration reaction with a tetracarboxylic dianhydride and a diamine compound, it is out to obtain a polyamic acid. Subsequently, a dehydration reaction is performed from the polyamic acid. The dehydration reaction is not particularly limited, and dehydration can be performed by a usual method to obtain a soluble polyimide.

  When a solvent that dissolves the soluble polyimide is used as a solvent in the reaction system, a solution in which the soluble polyimide is dissolved may be used, and may be directly mixed with the nanocarbon dispersion. Alternatively, a soluble polyimide may be isolated and dissolved in a nanocarbon dispersion to prepare a nanocarbon-dispersed polyimide solution.

(Composite material)
A composite material can be prepared using the nanocarbon-dispersed polyimide solution according to the present invention. More specifically, the composite material is obtained by removing the solvent from the polyimide solution of the present invention. That is, by using a polyimide solution, a composite material in which nanocarbon is more uniformly dispersed in the polyimide can be obtained. In particular, since the ratio of polyimide and nanocarbon can be freely set, a high concentration of nanocarbon can be dispersed in the polyimide. Further, by using the solution according to the present invention, it is possible to make a composite of a high molecular weight polyimide and nanocarbon without performing a heat treatment at a high temperature.

(Polyimide precipitate)
By dropping the polyimide solution according to the present invention into a poor solvent having low solubility in soluble polyimide, a composite in which polyimide and nanocarbon are deposited can be obtained. Here, various shapes of composite materials can be obtained by changing the dropping conditions.

  For example, by using a low-concentration polyimide solution, polyimide particles in which nanocarbon is dispersed can be obtained. In addition, even when a high-concentration polyimide solution is used, polyimide particles can be obtained by dropping the poor solvent while stirring. Moreover, an elliptical pellet can be obtained by increasing the dripping amount to a poor solvent. In addition, by lowering the dropping height, the dropping liquid may float in a poor solvent, and a film-like precipitate may be obtained. By dropping a nanocarbon-dispersed polyimide solution adjusted to an appropriate concentration into a poor solvent, a polyimide porous pellet having a porous structure in which nanocarbon is dispersed is obtained.

  The “poor solvent” into which the polyimide solution is dropped means a solvent having lower solubility in the soluble polyimide dissolved in the solution than the solvent used in the dropped solution. Moreover, it is suitable that the said poor solvent has a property mixed with the said solvent uniformly. Although it does not specifically limit as a poor solvent, For example, water, acetone, diethyl ether, methanol, ethanol, ethyl acetate, methyl acetate, a dioxane etc. are mentioned. Also, a plurality of combinations of these poor solvents may be used.

(Polyimide porous pellet)
By dropping a nanocarbon-dispersed polyimide solution adjusted to an appropriate concentration into a poor solvent, a polyimide porous pellet having a porous structure in which nanocarbon is dispersed is obtained. The polyimide porous pellet according to the present invention is formed on the particle surface, a skin layer formed by closely fusing the primary particles of the polyimide, and a porous structure formed inside the skin layer And a core layer. In the gap between the primary particles of the skin layer, pores that connect the inside of the 1-50 nm particle and the outside of the particle are formed. And carbon nanotubes are dispersed in the polyimide in the skin layer and the core layer,

  The presumed mechanism by which such a porous pellet is obtained is demonstrated. First, the dropped droplets are immersed in a poor solvent. Thereafter, precipitation of polyimide occurs on the surface of the droplet, and a dense skin layer in which fine primary particles are aggregated is formed. In the skin layer, fine pores are formed at the primary particle interface. It is thought that solvent exchange is performed between the inside and outside of the skin layer through the minute pores, and the polyimide and nanocarbon existing inside the skin layer are precipitated to form a core layer having a porous structure. It is done.

  Regarding the skin layer, the average particle size of primary particles of polyimide is 30 nm to 60 nm. And the thickness of a skin layer is 50-100 nm. The size of the holes formed in the skin layer is 1 to 50 nm. By having the pores in the range, the carbon nanotubes dispersed in the solution are hardly released out of the pores.

  With respect to the core layer, the core layer has a porous structure. The porous structure has a skeleton that forms the porous structure. The skeleton may be formed by aggregation of primary particles, or may be a smooth columnar skeleton in which the traces of primary particles cannot be confirmed. The nanocarbon may be present anywhere in the core layer, but is preferably dispersed within the skeleton forming the porous structure from the viewpoint of increasing the strength of the skeleton.

  When trying to obtain a polyimide porous pellet, the concentration of the soluble polyimide is preferably in the range of 2 to 20% by mass, and in the range of 5 to 20% by mass, although there is a balance with the molecular weight of the polyimide. It is more preferable that it is in the range of 6 to 20% by mass, and it is particularly preferable that it is in the range of 6 to 10% by mass. By using a solution having a concentration within the above range, polyimide aggregates in a poor solvent to form a pellet. Nanocarbon dispersed in the solution is dispersed in the pellet or the pellet surface.

  When obtaining a polyimide porous pellet, the amount of one drop of the polyimide solution to the poor solvent is not particularly limited. For example, 0.01 to 2.0 ml is preferable, and 0.1 to 1.0 ml is more preferable. 0.1 to 0.5 ml is more preferable.

  The particles according to the present invention may be used as they are, but the particles may be pressed and molded to be used as a molded body. In the polyimide porous pellet according to the present invention, nanocarbon is dispersed in porous polyimide. Therefore, since the polyimide porous pellet according to the present invention has conductivity, generation of static electricity is prevented. Therefore, the pellets are less likely to scatter due to the repulsion of static electricity at the time of molding, and handling properties are improved.

  Moreover, it can also be set as the heat insulating material which has electroconductivity by combining and shape | molding the polyimide porous pellet and resin binder which concern on this invention. In addition, it can be used as a pellet for purifying water, a catalyst carrier, or an electrode material.

(Polyimide particles)
When trying to obtain particles as a precipitate produced from a polyimide solution, particularly when a low molecular weight polyimide is used, powdery particles are easily obtained. Even in the case of using a high molecular weight polyimide, if it is dropped while stirring at high speed with a homogenizer or the like, fine particles can be obtained. Here, the average particle diameter of the polyimide particles is 30 nm to 60 nm. By preparing particles by such a method, it is possible to obtain nanocarbon-polyimide composite particles in which nanocarbon is present inside or on the surface of the particles. The particles may be pressed and molded to be used as a molded body.

(Other uses)
A nanocarbon-polyimide composite film can be obtained by casting using the solution according to the present invention.

  The polyimide solution according to the present invention can be used for various applications. For example, the solution according to the present invention can be used as a paint, a pressure sensitive adhesive or a curable adhesive.

  As the coating material, a solution obtained by adding a known resin binder to the solution according to the present invention is used. For example, a coating film is obtained by applying and drying the solution according to the present invention or the coating material. Examples of the object to be applied include a normal polyimide resin and other materials such as metal, glass, and ceramic.

  As an adhesive, an adhesive resin such as an acrylic adhesive resin or a rubber adhesive resin may be added to the solution according to the present invention, and the solution may be applied to a film or the like to be used as an adhesive. it can.

  Further, the solution according to the present invention can be used as it is and used as a hot melt adhesive. It is also preferable to add an epoxy-based thermosetting resin to the solution. It is preferable to use this as a thermosetting adhesive.

  Moreover, you may form a film using the solution which concerns on this invention, or the said coating material. The film can be formed using a known method. Alternatively, the solution according to the present invention may be applied on a film substrate and used as a film having a carbon nanotube-polyimide layer.

Production Example 1 (Preparation of soluble polyamide (FDA-BTDA))
In a 2000 mL separable flask, 64.44 g (0.2 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 9,9-bis (4-aminophenyl) fluorene 69.7 g (0.2 mol) of (FDA) and 1000 mL of NMP as a solvent were further added and stirred at room temperature. This produced a polyamic acid. Further, 2.5 g (0.024 mol) of γ-valerolactone, 5.85 g (0.074 mol) of pyridine, and 200 mL of xylene were further added as catalysts, and the mixture was reacted at 180 ° C. for 5 hours with stirring. At that time, a Dean-Stark tube is installed between the reflux condenser and the separable flask, and water produced as a by-product in the imidation reaction is trapped in the Dean-Stark tube outside the reaction system by azeotropy with xylene. Returned to the flask. Thereby, imidation reaction advanced and the NMP solution of soluble polyimide (FDA-BTDA) was obtained. The NMP solution of the obtained soluble polyimide (FDA-BTDA) was distilled off under reduced pressure at 180 ° C., washed successively with water and acetone, and then dried to obtain a polyimide solid.

Production Example 2 (Preparation of polyamide solution: (BAPS-M-BTDA)
In a 1000 mL separable flask, 32.22 g (0.1 mol) of 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and bis [4- (3-aminophenoxy) phenyl] 43.25 g (0.1 mol) of sulfone (BAPS-M) and 500 mL of NMP as a solvent were added and stirred at room temperature. This produced a polyamic acid. Further, 1.25 g (0.012 mol) of γ-valerolactone, 2.93 g (0.037 mol) of pyridine, and 100 mL of xylene were further added as catalysts, and the mixture was reacted at 180 ° C. for 5 hours with stirring. At that time, a Dean-Stark tube is installed between the reflux condenser and the separable flask, and water produced as a by-product in the imidation reaction is trapped in the Dean-Stark tube outside the reaction system by azeotropy with xylene. Returned to the flask. Thereby, imidation reaction advanced and the NMP solution of soluble polyimide (BAPS-M-BTDA) was obtained. The NMP solution of the obtained soluble polyimide (BAPS-M-BTDA) was distilled off under reduced pressure at 180 ° C., washed successively with water and acetone, and then dried to obtain a polyimide solid.

(Examples 1-6)
(Preparation of carbon nanotube (CNT) -polyimide complex solution)
The NMP dispersion (concentration: 1% by weight) of the polyimide synthesized in the above example and carbon nanotubes (Nanosil, NC-7000) was mixed at the ratio shown in the table below to obtain a CNT-polyimide composite (CNT concentration in the composite). : 1 wt%) solution was prepared.

(Example 3)
(Preparation of porous pellet of CNT-polyimide composite)
About 0.2 ml of the above solution was sucked into a syringe and dropped into water (large amount, 2 L) from an injection needle having an inner diameter of 1 mm to prepare a porous pellet of a CNT-polyimide composite (FIG. 1). Immediately after the dropped droplet enters the water, the polyimide undergoes phase separation at the interface between the droplet and water to form a film (dense porous film, skin layer), and polyimide and carbon nanotubes (manufactured by Nanosil) NC-7000) NMP dispersion. Thereafter, it is considered that the outer layer water and the inner layer NMP are exchanged through the membrane, and the polyimide in the membrane is phase-separated to form a porous body combined with CNT (FIG. 1). The physical properties of the prepared porous pellets are shown in the table below. An SEM photograph of the obtained porous pellet is shown in FIG. FIG. 2 (a) is an overall image of the porous pellet according to the present invention by an SEM photograph, FIG. 2 (b) is a sectional photograph of the porous pellet by SEM, and FIG. 2 (c) is a sectional view of the porous pellet. 2 (d) is an enlarged photograph of the internal cross section of the porous pellet, FIG. 2 (e) is an enlarged photograph of the internal cross section of the porous pellet, and FIG. 2 (f) is porous. It is an enlarged photograph of the internal cross section of a pellet. FIG. 3 is an enlarged photograph of the surface of the porous pellet. According to FIG.2 (b) and FIG.2 (c), a mode that the skin layer is formed in the surface vicinity of the porous pellet can be observed. According to these photographs, the thickness of the skin layer was 50 to 100 nm. Moreover, according to FIG.2 (e) and FIG.2 (f), a carbon nanotube is observed in the cut surface of frame | skeleton. Thus, carbon nanotubes are dispersed inside the skeleton of the porous pellet. According to FIG. 3, it can be observed that primary particles forming the skin layer of the porous pellet are observed, and fine pores of about 10 nm are formed between the primary particles.

The values in the above table were measured by the following method.
Bulk density: It was determined by dividing the weight measured with a balance by the measured volume. The particle size was measured with a MacView image analysis type particle size distribution measurement software Mac View from a photograph magnified 10 times. The average value of 10 particles was taken.
Glass transition temperature: Measured using a DSC6220 manufactured by SII NanoTechnology Co., Ltd. at a heating rate of 20 degrees / min and in nitrogen (50 ml / min).
Thermal decomposition temperature: TG / DTA6300 manufactured by SII Nano Technology Co., Ltd. was used, and the temperature was increased at a rate of 10 degrees / min and in nitrogen (200 ml / min).

(Example 13)
(Preparation of powder of CNT-polyimide composite)
In Example 13, the same procedure as in Example 7 was performed except that the solution was diluted with a 5% polyimide solution. The fine particles of the CNT-polyimide composite settled in water. It collect | recovered similarly to Example 7, and performed washing | cleaning and drying.

(Example 14)
In Example 14, the same procedure as in Example 11 was performed except that the solution was diluted with a 5% polyimide solution. The fine particles of the CNT-polyimide composite settled in water. It collect | recovered similarly to Example 11, and performed washing | cleaning and drying.

(Examples 15 and 16)
(Manufacture of molded products of CNT-polyimide composite)
In Example 15, the powder of the CNT-polyimide composite obtained in Example 13 was compression-molded with a press machine at 280 ° C. and 10 MPa for 1 hour, and a disk-shaped sample having a thickness of 1 mm and a diameter of 20 mm was obtained. Obtained. In Example 16, a disk-like sample was obtained under the same conditions as in Example 15 except that the CNT-polyimide composite powder obtained in Example 14 was used. Table 5 shows the physical properties.

(Example 17)
(CNT-polyimide composite film)
A solution prepared in the same manner as in Example 2 except that 6 g of polyimide (FDA-BTDA), 30 ml of CNT dispersion, and 20 ml of NMP were used was applied to a PET film using an applicator (clearance: 0.2 mm). After coating, it was dried at 110 ° C. for 10 minutes to prepare a CNT-polyimide composite thin film. The thickness was 30 μm. As a result of measuring the surface resistance of this coating film with Loresta manufactured by Mitsubishi Chemical Corporation, the surface resistance was 4.5 × 10 ⁴ Ω / □.

  In the obtained CNT-polyimide composite, CNTs are uniformly dispersed, and the concentration can be freely adjusted. Taking advantage of its properties, it can be used for various purposes.

  Porous pellets can be used as-is or processed to filter materials, micromachine parts that make use of slidability, PC parts, and heat-resistant and heat-dissipating materials that make use of foaming properties (automobile parts, demetalization around the engine). Used. Further, the powder is processed by a press or the like, and used as an automotive part or a structural material as a heat and heat dissipation material similar to the above.

  Furthermore, the composite solution can be applied to a heat- and heat-resistant coating such as HD or a heating element as a coating material (applicable anywhere, lightweight and conductive). Moreover, what formed this into the film is used also as electronic devices, such as a flexible circuit board, and a planar heating element similarly as a heat-resistant and heat radiating material.

Claims (9)

A nanocarbon-dispersed polyimide solution containing a soluble polyimide that is a polymer of tetracarboxylic dianhydride and a diamine compound, a solvent that dissolves the soluble polyimide, and nanocarbon that is dispersed in the solvent, A polyimide precipitate in which the nanocarbon is dispersed, obtained by dropping in a poor solvent having a lower solubility in the soluble polyimide than the solvent,
A skin layer formed on the surface and formed by fusing polyimide primary particles;
A core layer having a porous structure formed inside the skin layer,
Having pores of 1 to 50 nm in the gaps between the primary particles of the skin layer;
A polyimide porous pellet in which carbon nanotubes are dispersed in polyimide in the skin layer and the core layer. The solvent of the polyimide solution, N- methyl a pyrrolidone (NMP), wherein the poor solvent is water, according to claim 1 polyimide deposit according. The polyimide porous pellet according to claim 1 or 2 , wherein the skin layer has a thickness of 50 to 100 nm. The molded object obtained by press-molding the polyimide porous pellet as described in any one of Claims 1-3 . Soluble polyimide is a polymer of tetracarboxylic dianhydride and diamine compound, the solvent for dissolving the soluble polyimide, and containing a nanocarbon dispersed in the solvent, the nanocarbon dispersed polyimide solution, wherein The manufacturing method of the polyimide deposit in which carbon was disperse | distributed including the process of obtaining a deposit by dripping in the poor solvent whose solubility with respect to the said soluble polyimide is lower than a solvent. The concentration of soluble polyimide in the nanocarbon-dispersed polyimide solution is in the range of 2 to 20% by weight,
The production method according to claim 5 , wherein nanocarbon is dispersed inside and on the surface of the precipitate. The production method according to claim 5 or 6 , wherein the solvent is N-methylpyrrolidone (NMP) and the poor solvent is water. The manufacturing method according to claim 5 , wherein the nanocarbon is a carbon nanotube. The tetracarboxylic dianhydride is a benzophenone tetracarboxylic dianhydride,
The production method according to any one of claims 5 to 8 , wherein the diamine compound is 9,9-bis (4-aminophenyl) fluorene or bis [4- (3-aminophenoxy) phenyl] sulfone.