JP2010189524A - Polyimide fine particle dispersion, polyimide fine particle, and method for producing them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide fine particle dispersion, a polyimide fine particle, and a method for producing them. <P>SOLUTION: The method for producing the polyimide fine particle dispersion, wherein a polyimide fine particle of 10 nm to 300 nm size is dispersed in a high density, comprises dissolving a polyamic acid, that is a precursor polymer of a polyamide, into a solvent that does not dissolve polyimides but dissolves polyamic acids, introducing the solution and a cyclodehydration reagent into a pressure vessel heated at a prescribed temperature, performing conversion of polyamic acids into polyimides, and discharging carbon dioxide, thus a polyimide fine particle dispersion and a polyimide fine particle are also produced. The method makes it possible to provide polyimide fine particles without using large amount of organic solvent with low burden to environment and can provide products derived from the same. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polyimide fine particle dispersion containing nanometer-size polyimide fine particles, a polyimide fine particle, and a method for producing them, and more specifically, a polyimide fine particle dispersion in which nanometer-size polyimide fine particles are dispersed at a high concentration. Further, the present invention relates to a polyimide fine particle having a particle size on the order of nanometers and a production method thereof. The present invention relates to a polyimide fine particle dispersion in which polyimide fine particles having a size of 10 nm to 300 nm are dispersed at a high concentration of 0.1 wt% to 5 wt%, polyimide fine particles having a particle diameter of 10 nm to 40 nm, and an organic solvent as in the conventional method. The present invention provides new technologies and new products related to the synthesis and the like of these polyimide fine particles that can be produced by a production method that has a low environmental impact without using a large amount of.

  Generally, polyimide is used in many technical fields because it has excellent heat resistance, solvent resistance, mechanical properties, electrical insulation, and the like, and is a chemically and mechanically stable material. . Polyimides having these various properties are used, for example, as substitutes for metals and ceramics, and in particular in the fields of electricity, electronics, aerospace, etc. used under harsh conditions, such as films and varnishes. , Adhesives, bulk molding materials, etc.

  In addition, the material in which the polyimide is finely divided tends to spread more new usage forms by combining the characteristics of the polyimide and the shape and structure thereof. That is, conventionally, for example, finely divided polyimide has been used as an additive for powder toner for image formation (Patent Document 1). Moreover, the micronized polyimide is added to a varnish and used as an additive for improving screen printability (Patent Document 2). Furthermore, the use of a new polyimide is expanding by introducing a functional group into polyimide and combining it with fine particles (Patent Document 3).

  As the prior art, for example, a polyimide precursor powder made of a polyimide precursor that has excellent stability and can be converted to a polyimide with a high degree of polymerization, and the polyimide precursor powder can be inexpensively used without using a large amount of solvent. In addition, in order to provide a production method that can be easily obtained, an aromatic diamine and 3,3 ′, 4,4′-biphenyltetracarboxylic acid are mixed in a poor solvent for the resulting polyimide precursor, There has been proposed a method of obtaining a wholly aromatic polyimide precursor powder by obtaining a suspension in which polyimide precursor particles are dispersed and isolating the polyimide precursor particles (Patent Document 1).

  In addition, as another prior art, a polyimide powder can be produced by a simple process, and the method for producing a polyimide powder capable of easily controlling the particle diameter, and the polyimide powder obtained by the production method, As an offer, aromatic tetracarboxylic dianhydride and aromatic diamine are heated and polymerized in an organic solvent to obtain a polyimide solution, and then the temperature of the solution is lowered to precipitate polyimide particles. There has been proposed a method for producing a polyimide powder including a step of causing (Patent Document 4).

  However, the polyimide particles described in the above two prior art documents and the production method thereof both relate to the production of polyimide particles of micrometer order, and the obtained polyimide particles are nanometers obtained in the present invention. Compared to the order, it is quite large.

  In addition, as another prior art, a method for synthesizing polyimide from tetracarboxylic anhydride and a diamine compound provides a method capable of producing polyimide fine particles with higher monodispersibility on an industrial scale. A first solution containing an excess amount of tetracarboxylic anhydride and a second solution containing a diamine compound in an amount exceeding the solubility of the solvent, respectively, and under stirring, the first solution and the second solution And a second step of precipitating the polyamic acid fine particles from the mixed solution and a third step of obtaining the polyimide fine particles by imidizing the polyamic acid fine particles. (Patent Document 5).

  In this method, nanometer-order nanoparticles similar to the present invention are obtained at a high concentration of 15 wt%, but the starting material is a tetracarboxylic acid which is a precursor of polyamic acid which is a precursor polymer of polyimide. A dianhydride and a diamine. The former is hydrolyzed by moisture in the air and opened, and the latter is oxidized by oxygen in the air and the amino group is changed to a nitro group. There is a problem that it is difficult to save.

  As another prior art, as a method for producing nano-sized polyimide fine particles by controlling the particle size and particle size distribution, polyamic acid is added to a good solvent selected from polar amide solvents in an amount of 0.1% by weight to 2%. A polymer solution dissolved at a concentration of% by weight is selected from paraffinic solvents, aromatic solvents, and CS2, and the temperature is controlled from 5 ° C to 50 ° C and injected into a poor solvent stirred under vigorous stirring conditions. Then, the temperature of the poor solvent is controlled so that the average particle size is 44 nm to 400 nm, and when the average particle size is 44 nm, about 80% of the particles fall within the range of ± 10 nm, and the average particle size is 400 nm. In this case, a polyamic acid fine particle having a particle size dispersibility in a range where about 80% of the particles fall within a range of ± 100 nm is formed, and the polyamic acid particle is chemically imidized to maintain the particle dispersibility. A method for producing fine particles has been proposed (Patent Document 6).

  In this method, as in the present invention, polyamic acid is used as a starting material, and the obtained particle size is on the order of nanometers. However, the polyamic acid solution used as the starting material is 0.1 The mixing ratio of the solution and the poor solvent is 0.1 mL: 10 mL, and the amount of nanoparticles in the finally obtained nanoparticle dispersion is 0.02 at most. It is a very thin dispersion with a low concentration of about wt%.

  Furthermore, as another prior art, as a technique for producing a polyimide fine particle aggregate that can easily separate and recover fine particles from a polyimide fine particle dispersion, a polyamic acid fine particle dispersion is prepared from polyamic acid by a reprecipitation method, and heat or After chemical imidization, the organic solvent and the poor solvent are phase-separated, and the polyimide fine particles are aggregated and formed at the liquid-liquid interface, and the polyimide fine particle aggregates produced by the above method are high by a simple separation operation. A method for producing a large amount of polyimide fine particle aggregates with high efficiency by separating and recovering them with time efficiency and drying (Patent Document 7) has been proposed. However, in this method, the polyimide fine particles can be obtained only in an aggregated state, and when obtained as a fine particle dispersion, a multi-step process of filtration, drying, and redispersion is required.

  As described above, various proposals have been made for the polyimide precursor, the polyimide fine particles, and their production techniques as conventional techniques. However, in the conventional method, it is necessary to use a large amount of an organic solvent, and there is a burden on the environment. As described above, even if the size of the polyimide is on the order of micrometers, the polyamic acid precursor is difficult to store as a starting material, or a nanoparticle dispersion is obtained, it is finally obtained. The amount of nanoparticles in the resulting nanoparticle dispersion is a very dilute dispersion of about 0.02% by weight. In this technical field, the amount of organic solvent used is reduced. , A nano-size and high-concentration polyimide fine particle dispersion containing high-concentration nanoparticles and a new The imide fine particle dispersion and to develop its mass production techniques are strongly requested was circumstances.

JP-A-11-140185 JP 2000-178506 A JP 2000-248063 A JP 2002-293947 A JP 2006-182845 A JP 2003-252990 A JP 2008-159769 A

  In such a situation, in view of the above-mentioned prior art, the present inventors can surely solve the problems of the above-mentioned conventional method, and nanometer-sized polyimide fine particles are dispersed at a high concentration. As a result of intensive research aimed at developing polyimide fine particle dispersions and polyimide fine particles, and their manufacturing technology, polyamic acid, which is a storable polyimide precursor polymer, was used as a starting material. Dissolve it in a solvent that dissolves the polyamic acid without dissolving it, put the solution and the dehydrating cyclization reagent in a pressure-resistant container, fill with carbon dioxide to normal pressure or more, convert the polyamic acid to polyimide, It has been found that the intended purpose can be achieved by discharging carbon, and the present invention has been completed.

  An object of the present invention is to provide a polyimide decomposition solution in which polyimide fine particles having a size of 10 nm to 300 nm are dispersed at a high concentration of 0.1 wt% to 5 wt%. Another object of the present invention is to provide polyimide fine particles having a particle size of 10 nm to 40 nm. Another object of the present invention is to provide a polyimide fine particle dispersion in which these polyimide fine particles are dispersed at a high concentration, and a method for producing the polyimide fine particles with low load on the environment using carbon dioxide. It is.

The present invention for solving the above problems is constituted by the following technical means.
(1) Polyamic acid that is a polyimide precursor polymer is dissolved in a solvent that dissolves polyamic acid without dissolving polyimide, and the solution and the dehydrating cyclization reagent are placed in a pressure-resistant container heated to a predetermined temperature, It is characterized by producing a dispersion in which polyimide fine particles having a size of 10 nm to 300 nm are dispersed at a high concentration by filling carbon dioxide up to normal pressure or more, converting polyamic acid to polyimide, and then discharging carbon dioxide. A method for producing a polyimide fine particle dispersion.
(2) The method for producing a polyimide fine particle dispersion liquid according to (1), wherein a filling pressure of the carbon dioxide is 5 MPa to 30 MPa.
(3) The method for producing a polyimide fine particle dispersion liquid according to (1) or (2), wherein the heating temperature of the pressure vessel is 0 ° C to 100 ° C.
(4) The method for producing a polyimide fine particle dispersion according to any one of (1) to (3), wherein the concentration of the polyimide fine particle dispersion is 0.1 wt% to 5 wt%.
(5) The method for producing a polyimide fine particle dispersion according to (1), wherein the polyamic acid solution in a ratio of 0.5 mL to 5 mL is placed in the pressure resistant container with respect to a pressure resistant container having a capacity of 50 mL.
(6) A polyimide fine particle dispersion, wherein polyimide fine particles having a size of 10 nm to 40 nm are dispersed at a high concentration of 0.1 wt% to 5 wt%.
(7) Polyimide fine particles, which are polyimide fine particles having a size of 10 nm to 40 nm and can be redispersed in a dispersion medium in a monodispersed form.

Next, the present invention will be described in more detail.
The present invention is a method for producing a polyimide fine particle dispersion in which polyimide fine particles are dispersed at a high concentration, wherein a polyamic acid that is a polyimide precursor polymer is dissolved in a solvent that dissolves the polyamic acid without dissolving the polyimide, The solution and the dehydrating cyclization reagent are placed in a pressure-resistant container heated to a predetermined temperature, and further filled with carbon dioxide to a normal pressure or higher to convert the polyamic acid to polyimide, and then discharge carbon dioxide to give 10 nm. To 300 nm-sized polyimide fine particles are dispersed at a high concentration to produce a dispersion.

  In the present invention, a polyamic acid (polyamic acid) which is a precursor polymer of polyimide is used as a starting material. Since the starting polyamic acid can be stored refrigerated, it is oxidized by, for example, tetracarboxylic dianhydride that is hydrolyzed by water in the air to open the ring, or oxygen in the air, and the amino group becomes a nitro group. This is advantageous compared to diamines that are difficult to preserve. This polyamic acid is dissolved in a solvent that dissolves the polyamic acid without dissolving the polyimide.

  In the present invention, a solvent that does not dissolve polyimide but dissolves polyamic acid is used as a solvent, but an organic polar solvent is used as a solvent for polyamic acid, that is, polyamic acid. Examples of the organic solvent include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, acetonitrile, alcohols (methanol, ethanol, isopropanol, etc.), N, N-dimethylacetamide, dimethylformamide, N-methylpyrrolidone (NMP), and the like. If they have the same effect, they can be used similarly.

  Among these, the organic solvent is preferably a solvent containing at least 50% of an amide solvent, and examples thereof include polar amide solvents N, N-dimethylacetamide, N-methylpyrrolidone, and dimethylformamide. The containing solvent is preferred. The concentration of the polyamic acid solution is an important factor that affects the size of the particles to be produced. In particular, the larger the molecular weight of the polyamic acid, the greater the influence of the concentration of the solution. For example, when the molecular weight is large, the concentration of the polyamic acid solution is preferably about 2 wt% to about 0.5 wt%.

  Next, in the present invention, a solution in which polyamic acid is dissolved in the solvent and the dehydrating reagent are placed in an appropriate pressure-resistant container as a high-pressure reaction container heated to a predetermined temperature, and carbon dioxide is usually added. Fill to pressure or higher to convert polyamic acid to polyimide. In this case, the filling pressure of carbon dioxide is 5 MPa to 30 MPa, preferably 5 to 10 MPa, or 5 to 20 MPa.

  The heating temperature of the pressure vessel is 0 ° C. to 100 ° C. and is preferably in the range of about 20 to 60 ° C., but the heating temperature is appropriately adjusted in the range of 0 ° C. to 100 ° C. Is possible. The heating temperature is an important condition for producing polyamic acid fine particles having a desired average particle diameter. In particular, a temperature of 20 to 60 ° C. is preferable for forming the desired polyamic acid fine particles. In order to improve dispersibility, ± 10 ° C. of these temperature ranges is preferable.

  The solution stirring conditions and carbon dioxide injection conditions are also important conditions for forming the polyamic acid fine particles. Specifically, for example, a polyamic acid solution, a dehydrating cyclization reagent, and a stirring bar are placed in a high-pressure reaction vessel. After sealing, for example, carbon dioxide is charged at 1 to 5 mL / min to 5 to 20 mL / min with vigorous stirring at about 500 ± 200 rpm to 1500 ± 500 rpm, and kept for about 1 to several hours under stirring. The pressure is returned to, and carbon dioxide is discharged to obtain a cloudy yellow polyimide fine particle dispersion.

  In the present invention, the size and type of the pressure-resistant vessel as the high-pressure reaction vessel are not particularly limited as long as the high-pressure reaction can be performed, and appropriately according to the volume of the reaction solution and the like. A high pressure reaction vessel having an appropriate shape and structure can be used. Regarding the relationship between the volume of the reaction solution and the high-pressure reaction vessel, for example, it is preferable to use a polyamic acid solution in a ratio of 0.5 mL to 5 mL with respect to a pressure vessel of about 50 mL capacity.

  In addition, the method and apparatus for filling the high pressure reaction vessel with carbon dioxide to normal pressure or higher are not particularly limited, and the filling pressure of carbon dioxide can be adjusted from 5 MPa to 30 MPa with respect to the pressure vessel. As long as it is a means, an appropriate method and apparatus can be used. In the present invention, it is important to fill the high-pressure reaction vessel with carbon dioxide at a pressure of 5 MPa to 30 MPa above the normal pressure.

  In the present invention, examples of the polyamic acid which is a precursor polymer of polyimide as a starting material include polymerization of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether, 3,3 ′, 4-4′- Polyamic acid synthesized by polymerization of diphenyltetracarboxylic dianhydride and p-phenylenediamine or the like can be used. Basically, the molecular weight of the polyimide used in the present invention is appropriately selected in relation to the use of the polyimide fine particles, but in order to stably produce fine particles having a desired particle size, the average molecular weight (weight) ) Is preferably in the range of 10,000 to 48000 to 48000 to 123,000.

  In the present invention, for example, pyridine, acetic anhydride, or a mixed solution thereof is used as a dehydrating cyclization reagent, and chemically imidized with stirring to prepare a polyimide fine particle dispersion. In this imidization step, thermal imidization can be performed, and thermal imidization can be performed after chemical imidization. In this case, for example, about 0.1 ml of a mixed solution having a molar ratio of pyridine / acetic anhydride of about 1/1 is preferably added with stirring and held for several hours to perform chemical imidization. Thermal imidization can be carried out by holding at about 250 ° C. for several hours.

  Next, in the present invention, as tetracarboxylic acid or dianhydride thereof used for forming polyimide fine particles, for example, 3,3′-4-4′-benzophenonetetracarboxylic acid (BTDA), 3,3′- Examples include 4-4′-tetracarboxybiphenyl, 2,2- (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane, and dianhydrides thereof.

  In addition, as a diamine, for example, 4,4′-diamine diphenyl ether is used to react with the tetracarboxylic acid or its dianhydride to form a polyimide precursor polyamic acid and then form a polyimide by imidization or the like. 4,4′-bis (4-aminophenoxy) biphenyl, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-diaminebenzene, 4'-methylenebis (methylcyclohexylamine), 4,4'-methylenebis (ethylcyclohexylamine) and the like are used.

  According to the present invention, a dispersion in which the concentration of the polyimide fine particle dispersion is as high as 0.1 wt% to 5 wt% and polyimide fine particles having a size of 10 nm to 300 nm are dispersed at a high concentration is manufactured by the above-described reaction method. be able to. More preferably, for example, a polyimide fine particle dispersion in which polyimide fine particles having a size of 10 nm to 40 nm are dispersed at a high concentration of 0.1 wt% to 5 wt% and a particle diameter of 10 nm to 40 nm from the above dispersion liquid. Polyimide fine particles can be prepared and provided, and these polyimide fine particles have a special feature that they can be redispersed in a monodisperse form in an appropriate dispersion medium.

  Conventionally, in order to produce nanometer-sized particles in a particle production method using polyamic acid as a starting material, it is generally necessary to carry out under a dilute concentration. Therefore, a large amount of organic solvent is used. It was necessary and it was inevitable that it would put a heavy load on the environment. In contrast, the present invention replaces the solvent that has been used in large quantities with carbon dioxide recovered from the air, and the carbon dioxide can be easily recovered and reused. The invention has a high technical significance in that it is a manufacturing method having a low load on the environment.

The present invention has the following effects.
(1) A polyimide fine particle dispersion in which nanometer-sized polyimide fine particles are dispersed at a high concentration of 0.1 wt% to 5 wt% can be provided.
(2) It is possible to provide polyimide fine particles having a size of 10 nm to 300 nm.
(3) Polyimide fine particles that can be redispersed in a dispersion medium in a monodispersed form can be produced from the polyimide fine particle dispersion.
(4) It is possible to provide polyimide fine particles that can be redispersed in a dispersion medium in the form of a monodisperse produced by the above method.
(5) According to the present invention, it is possible to supply a large amount of polyimide fine particles which can be redispersed in various dispersion media.
(6) The polyimide fine particles of the present invention can be redispersed in a monodisperse form in various types of dispersion media, and a polyimide fine particle product can be provided according to the purpose of use.
(7) According to the present invention, for example, it is possible to establish a polyimide fine particle dispersion and a mass production technique of polyimide fine particles that can supply a large amount of polyimide fine particles having a particle size of 10 to 300 nm.

The electron microscope (SEM) photograph of the polyimide fine particle obtained in Example 1 is shown. The particle size distribution by the dynamic light scattering (DLS) measurement of the polyimide fine particle obtained in Example 1 is shown. The electron microscope (SEM) photograph of the polyimide fine particle obtained in Example 2 is shown. The electron microscope (SEM) photograph of the polyimide fine particle obtained in Example 3 is shown. The electron microscope (SEM) photograph of the polyimide microparticles | fine-particles obtained in Example 4 is shown.

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.

  A solution was prepared by dissolving polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide at a concentration of 1.0% by mass. 1 mL of the solution, 250 μL of acetic anhydride, and 50 μL of pyridine were placed in a high-pressure reaction vessel (capacity 50 mL) sufficiently heated in an oven set at 40 ° C., and a stir bar was further sealed.

  While stirring these with a magnetic stirrer, in order to further fill the high-pressure reaction vessel with carbon dioxide to a normal pressure or higher, carbon dioxide was added at a flow rate of 2.5 mL / min at 10 MPa (a) and 15 MPa, respectively. (B) Filled up to 20 MPa (c). This was held for 2 hours under stirring, then returned to normal pressure, carbon dioxide was discharged, and a cloudy yellow polyimide fine particle dispersion was obtained.

  The average particle sizes of the obtained polyimide fine particles are 194 nm, 172 nm, and 163 nm, the standard deviations are 46 nm, 24 nm, and 70 nm, respectively, and the coefficient of variation (CV) is 24%, 14%, and 43%, respectively. there were. An electron microscope (SEM) photograph of the obtained particles is shown in FIG. Moreover, the result of the particle size distribution by dynamic light scattering (DLS) measurement is shown in FIG.

  A solution was prepared by dissolving polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide at a concentration of 1.0% by mass. 1 mL of the solution, 250 μL of acetic anhydride, and 50 μL of pyridine were placed in a high-pressure reaction vessel (capacity 50 mL) sufficiently heated in an oven set at 60 ° C., and a stir bar was further sealed.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 10 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. This was held for 2 hours under stirring, then returned to normal pressure, carbon dioxide was discharged, and a slightly turbid yellow polyimide fine particle dispersion was obtained. An electron microscope (SEM) photograph of the obtained particles is shown in FIG. The particle size was 10 nm.

  A solution in which polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether is dissolved in N-methyl-2-pyrrolidone or dimethyl sulfoxide at a concentration of 1.0 mass%. Was prepared. 1 mL of the solution, 250 μL of acetic anhydride, and 50 μL of pyridine were placed in a high-pressure reaction vessel (capacity 50 mL) sufficiently heated in an oven set at 40 ° C., and a stir bar was further sealed.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 10 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. This was held for 2 hours under stirring, then returned to normal pressure, carbon dioxide was discharged, and a slightly turbid yellow polyimide fine particle dispersion was obtained. FIG. 4 shows an electron microscope (SEM) photograph of the fine particles obtained using N-methyl-2-pyrrolidone. The particle size was 10 nm.

  A solution was prepared by dissolving polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide at a concentration of 1.0% by mass. In a high-pressure reaction vessel (capacity: 50 mL) sufficiently heated in an oven set at 40 ° C., 2.5 mL or 5 mL of the solution, 250 μL of acetic anhydride, and 50 μL of pyridine were added, and a stir bar was added to seal.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 10 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. This was kept under stirring for 2 hours, then returned to normal pressure, carbon dioxide was discharged, and a slightly turbid yellow polyimide fine particle dispersion was obtained. FIG. 5 shows an electron microscope (SEM) photograph of fine particles obtained by adding 5 mL of the polyamic acid solution. The particle size was 30 nm.

  A solution was prepared by dissolving polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide at a concentration of 1.0% by mass. 1 mL of the solution, 250 μL of acetic anhydride, and 50 μL of pyridine were placed in a high-pressure reaction vessel (capacity 50 mL) that was cooled with water at 20 ° C., and a stir bar was added to seal the solution.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 10 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. After holding for 2 hours under stirring, the pressure was returned to normal pressure, carbon dioxide was discharged, and a slightly turbid yellow polyimide fine particle dispersion was obtained.

  A solution was prepared by dissolving polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide at a concentration of 1.0% by mass. 1 mL of the solution and 250 μL of acetic anhydride were placed in a high-pressure reaction vessel (capacity: 50 mL) sufficiently heated in an oven set at 40 ° C., and a stir bar was added to seal the solution.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 10 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. After maintaining this for 5 hours under stirring, the pressure was returned to normal pressure, carbon dioxide was discharged, and a cloudy yellow polyimide fine particle dispersion was obtained.

  A solution was prepared by dissolving polyamic acid obtained by polymerization of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether in N, N-dimethylacetamide at a concentration of 1.0% by mass. 1 mL of the solution, 150 μL or 500 μL of acetic anhydride, and 50 μL of pyridine were placed in a high-pressure reaction vessel (capacity 50 mL) sufficiently heated in an oven set at 40 ° C., and a stir bar was further sealed.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 15 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. This was held for 2 hours under stirring, then returned to normal pressure, carbon dioxide was discharged, and a cloudy yellow polyimide fine particle dispersion was obtained.

  Polyamic acid obtained by polymerization of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine is dissolved in N, N-dimethylacetamide at a concentration of 1.0 mass%. A prepared solution was prepared. 1 mL of the solution, 150 μL of acetic anhydride, and 50 μL of pyridine were placed in a high-pressure reaction vessel (capacity 50 mL) sufficiently heated in an oven set at 40 ° C., and a stir bar was further sealed.

  While stirring these with a magnetic stirrer, carbon dioxide was charged up to 15 MPa at a flow rate of 2.5 mL / min in order to fill the high-pressure reaction vessel with carbon dioxide up to normal pressure or higher. This was held for 2 hours under stirring, then returned to normal pressure, carbon dioxide was discharged, and a cloudy yellow polyimide fine particle dispersion was obtained.

  As described above in detail, the present invention relates to a polyimide fine particle dispersion, a polyimide fine particle, and a production method thereof. According to the present invention, a polyimide fine particle that can be redispersed in a dispersion medium is obtained from a polyimide fine particle dispersion. A method of manufacturing can be provided. In addition, according to the present invention, it is possible to provide polyimide fine particles which can be redispersed in a dispersion medium, which is produced by the above method. The polyimide fine particles of the present invention can be redispersed in a monodisperse form in a dispersion medium, and the present invention can supply a large amount of polyimide fine particles. The polyimide fine particles of the present invention can be redispersed in a monodisperse form in various types of dispersion media, and according to the present invention, a product corresponding to the purpose of use can be easily configured. The present invention makes it possible to mass-produce polyimide fine particles by a production method having a low load on the environment, and thereby to supply a large amount of nano-sized polyimide fine particles having a particle size of 10 to 300 nm. Useful as.

Claims (7)

  Polyamide acid, which is a polyimide precursor polymer, is dissolved in a solvent that dissolves polyamide acid without dissolving polyimide, and the solution and the dehydrating cyclization reagent are placed in a pressure-resistant container heated to a predetermined temperature, and carbon dioxide is further added. A polyimide characterized by producing a dispersion in which polyimide fine particles having a size of 10 nm to 300 nm are dispersed at a high concentration by filling up to normal pressure or higher, converting polyamic acid to polyimide, and then discharging carbon dioxide. A method for producing a fine particle dispersion.   The method for producing a polyimide fine particle dispersion according to claim 1, wherein a filling pressure of the carbon dioxide is 5 MPa to 30 MPa.   The manufacturing method of the polyimide fine particle dispersion of Claim 1 or 2 whose heating temperature of the said pressure | voltage resistant container is 0 to 100 degreeC.   The manufacturing method of the polyimide fine particle dispersion in any one of Claim 1 to 3 whose density | concentration of the said polyimide fine particle dispersion is 0.1 wt% to 5 wt%.   The manufacturing method of the polyimide fine particle dispersion of Claim 1 which puts the said polyamic-acid solution of the ratio of 0.5 mL to 5 mL with respect to a 50 mL capacity | capacitance pressure vessel in this pressure vessel.   A polyimide fine particle dispersion, which is a dispersion in which polyimide fine particles having a size of 10 nm to 40 nm are dispersed at a high concentration of 0.1 wt% to 5 wt%.   Polyimide fine particles, which are polyimide fine particles having a size of 10 nm to 40 nm and can be redispersed in a dispersion medium in a monodispersed form.