JP6187273B2 - Polyamideimide resin fine particle dispersion and method for producing polyamideimide resin fine particle dispersion - Google Patents

Description

  The present invention relates to a polyamideimide resin fine particle dispersion and a method for producing a polyamideimide resin fine particle dispersion.

  Polyamideimide resin (hereinafter may be abbreviated as “PAI resin”) has excellent heat resistance, chemical resistance, wear resistance, etc., industrial equipment parts, films, electrical / electronic parts, automotive parts, aerospace related Used for parts. In addition to being used as pellets, polyamideimide resins are also used as varnishes dissolved in organic solvents.

  In recent years, in the fields of automobiles and electronic materials, lightening, downsizing, miniaturization, and thinning have been promoted, and in order to meet these demands, application of fine fine particles to the member surface is required. In order to coat the surface of the member with the polyamideimide resin fine particles, the dispersion liquid is uniformly applied to the member, and then the dispersion medium is removed. Polyamideimide resin fine particles are also known to be effective in improving resin physical properties such as imparting thixotropy and improving impact resistance by mixing with other resins and composite materials.

  As described above, the polyamideimide resin fine particles are used in many applications, and various application developments are expected. In order to reduce the weight, downsizing, miniaturization, and thinning of the member by coating the surface of the member with polyamideimide resin particles, the particle size of the polyamideimide resin particles is preferably 1 μm or less, but the polyamide of 1 μm or less Since the powder of the imide resin fine particles easily aggregates, it is usually difficult to disperse the powder in the resin. Therefore, a dispersion liquid in which polyamideimide resin fine particles are uniformly dispersed in a dispersion medium suitable for the application is desired. In order to uniformly disperse the polyamideimide resin fine particles in the dispersion medium, it is desirable that the average primary particle size of the fine particles is 300 nm or less, and furthermore, to produce a polyamideimide resin fine particle dispersion excellent in dispersion stability. It is necessary to select an appropriate surfactant and mechanically disperse it.

  As a method for synthesizing the polyamideimide resin fine particles, for example, a first solution containing an acid chloride such as trimellitic anhydride chloride and a second solution containing a diamine compound such as 4,4′-diaminodiphenyl ether are used. There is known a method of obtaining polyamideimide resin fine particles by stirring with ultrasonic waves in the presence of a solvent soluble in both the solution and the second solution (see, for example, Patent Documents 1, 2, and 3). However, Patent Documents 1, 2, and 3 only describe the production of polyamide fine particles using dicarboxylic acid chloride as the acid chloride as specific production examples, and specific production of polyamideimide resin fine particles. Examples and polyamideimide resin fine particle dispersions are not disclosed.

  Further, as a method for producing polyamideimide resin fine particles, a method using a spray drying method is disclosed (for example, see Patent Document 4). In this method, polyamideimide resin dissolved in N-methyl-2-pyrrolidinone is spray-dried by mobile minor type spray drying to obtain polyamideimide fine particles having an average particle size of 4.5 μm. Furthermore, for example, a method for producing polyamideimide resin fine particles having an average particle diameter of 3 μm from polymerization of 4,4′-diphenylmethane diisocyanate and trimellitic anhydride is disclosed (see, for example, Patent Documents 5 and 6). ). However, the methods according to Patent Documents 4, 5 and 6 cannot produce polyamideimide resin fine particles having an average particle diameter of 1 μm or less.

Also, there is a method in which polyamideimide resin dissolved in 1,3-dimethyl-2-imidazolidinone is added to a surfactant aqueous solution having a phenyl group to precipitate polyamideimide resin fine particles having an average particle size of 1 μm or less. It is disclosed (for example, see Patent Document 7).
Further, Patent Document 8 discloses a method for producing polyamideimide resin fine particles having an average primary particle size of 300 nm or less by dissolving a polyamideimide resin in an organic solvent and adding the polyamideimide resin to a poor solvent or flash crystallization. Has been reported. However, Patent Documents 7 and 8 do not describe the polyamideimide resin fine particle dispersion.

  Furthermore, Patent Document 9 describes a method for preparing an aqueous dispersion of polyamideimide resin powder, but the dispersant is limited to polyamic acid having an imidization rate of 0% to 30%, and is used for use. There is a limit.

  On the other hand, a method is disclosed in which polyphenylene sulfide resin dissolved in an organic solvent is flash-cooled to obtain polyphenylene sulfide resin fine particles, and the resin fine particles are used as a dispersion (Patent Document 10). However, Patent Document 10 neither describes nor suggests that a polyamideimide resin fine particle dispersion can be produced.

  Under such circumstances, development of a dispersion of polyamideimide resin fine particles having an average primary particle size of 300 nm or less and excellent in dispersion stability has been eagerly desired.

Japanese Patent No. 4304434 JP 2005-97370 A JP 2006-257345 A JP-A-4-285660 JP 11-246759 A JP 2000-17073 A JP 2009-066780 A International Publication No. 2011/062006 JP 2010-37506 A International Publication No. 2009/119466

  Accordingly, an object of the present invention is to provide a polyamideimide resin fine particle dispersion excellent in dispersion stability and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventors have surprisingly been able to disperse polyamideimide resin fine particles which are stable when suspended in a dispersion medium and mechanically dispersed in the presence of a surfactant. The inventors have found that a liquid can be obtained and have reached the present invention.
That is, the present invention is a polyamideimide resin fine particle dispersion comprising a polyamideimide resin fine particle having an average primary particle size of 100 nm to 300 nm, a surfactant, and a dispersion medium.
Further, the present invention includes a dispersion step of mechanically dispersing polyamideimide resin fine particles in a dispersion medium in the presence of an anionic surfactant, a cationic surfactant, a nonionic surfactant, or a polymer surfactant. This is a method for producing a polyamideimide resin fine particle dispersion.

  By using the present invention, it is possible to easily and stably produce a PAI resin fine particle dispersion having an average particle size of 300 nm or less, which has been difficult to obtain industrially and stably, and widely useful industrially useful materials. Can be provided.

  Hereinafter, embodiments of the present invention will be described in detail.

[Raw material PAI resin]
The polyamideimide resin used in the present invention is obtained by polymerizing an acid component such as trimellitic anhydride or trimellitic anhydride monochloride and an amine component.
As a method for producing PAI resin, an isocyanate method using trimellitic anhydride and diisocyanate as raw materials (for example, Japanese Patent Publication No. 50-33120), trimellitic anhydride chloride and diamine are polymerized in N, N-dimethylacetamide. Acid chloride method (for example, Japanese Examined Patent Publication No. S42-15637) In the presence of a trivalent or pentavalent inorganic or organic phosphorus compound, an aromatic tricarboxylic acid, its anhydride or its ester, and a diamine are dissolved in a solution. Although a direct polymerization method for reaction (for example, Japanese Patent Publication No. 49-4077) is known, the PAI resin in the present invention can be produced by any method.
The polyamideimide resin used in the present invention can be appropriately selected from commercially available ones, and specifically, polyamideimide resin TI-5013P manufactured by Toray Industries, Inc., Torlon manufactured by Solvay Co., etc. can be used. .

[Production of PAI resin fine particles]
The PAI resin fine particles in the present invention can be produced through a method including the dissolution step and the precipitation step described below for the PAI resin described above.

The dissolution step for producing the polyamideimide resin fine particles used in the present invention is selected from the following (a1) and (b1).
(A1) Dissolving the polyamideimide resin in an organic solvent to obtain a polyamideimide resin solution A1 having a polyamideimide resin concentration of less than 5% by mass (b1) Dissolving the polyamideimide resin in an organic solvent, and the polyamideimide resin concentration is The process which makes less than 10 mass% polyamideimide resin solution B1

The precipitation step for producing the polyamideimide resin fine particles used in the present invention is selected from the following (a2) and (b2).
(A2) Polyamideimide resin solution A1 is added to a solvent for precipitating polyamideimide resin microparticles substantially free of surfactant to precipitate polyamideimide resin microparticles (b2) Polyamideimide resin dissolution Step of precipitating fine particles of polyamideimide resin by flash crystallization of liquid B1

  In the dissolution step, when (a1) is selected, the precipitation step selects (a2), and when the dissolution step (b1) is selected, the precipitation step (b2) is performed. That is, in the dissolution step (a1) in which the concentration of the PAI resin is less than 5% by mass, fine particles are obtained by the precipitation step (a2) in which the PAI resin is simply added to the poor solvent. It becomes a lump. On the other hand, in the precipitation step (b2) by flash crystallization, it is possible to produce fine particles with a PAI resin concentration of less than 10% by mass.

[Dissolution process]
The dissolution step in the present invention is selected from the above-described dissolution steps (a1) and (b1).
First, a method for dissolving a polyamideimide resin in an organic solvent will be described below.

  In the present invention, in the dissolution step, the PAI resin is dissolved in the organic solvent in a dissolution tank charged with the organic solvent. The form of the PAI resin used in the present invention is not particularly limited, and specific examples include powders, granules, pellets, films, molded products and the like. From the viewpoint of shortening the operability and the time required for dissolution, powders, granules and pellets are desirable, and powdered PAI resin is particularly preferable. Here, in order to prevent the corrosion of the device due to coexisting inorganic ions, including when the target PAI resin fine particles are used for water-soluble paints, etc., powder, granules, pellets that do not contain inorganic ions The PAI resin is particularly preferred.

  Any organic solvent can be used as long as it dissolves the PAI resin. Specifically, N-alkylpyrrolidinones such as N-methyl-2-pyrrolidinone (hereinafter abbreviated as NMP), N-alkylcaprolactams such as N-methyl-ε-caprolactam, 1,3-dimethyl-2 -Ureas such as imidazolidinone (hereinafter abbreviated as DMI), chain structures such as N, N-dimethylacetamide (hereinafter abbreviated as DMAc), N, N-dimethylformamide (hereinafter abbreviated as DMF) Examples thereof include at least one solvent selected from sulfur oxide polar solvents such as amide solvents, dimethyl sulfoxide (hereinafter abbreviated as DMSO), dimethyl sulfone, and tetramethylene sulfone.

  The atmosphere of the dissolution tank in the dissolution process may be any of an air atmosphere, an inert gas atmosphere, or a solvent vapor atmosphere, but in order to suppress the decomposition and deterioration of the PAI resin, and to proceed more safely It is more preferable to lower the oxygen gas concentration. Here, examples of the inert gas include nitrogen gas, carbon dioxide gas, helium gas, argon gas, etc. In consideration of economy and availability, nitrogen gas, argon gas, carbon dioxide gas is preferable, Particularly preferably, nitrogen gas or argon gas is used. In addition, as a method for setting the atmosphere in a solvent vapor, (1) a method in which the dissolution tank is depressurized or vacuumed to remove air and then the reaction tank is heated, and (2) while sucking the air in the dissolution tank, (3) A method such as stopping the suction when the solvent vapor is filled while sucking the air in the dissolution tank while the temperature is raised and the solvent vapor is filled. 4) A method in which the same kind of vapor as the solvent is blown into the reaction tank while aspirating the air in the dissolution tank, or a combination of these methods can be mentioned, and thereby the atmosphere in the vaporized solvent vapor can be obtained. Can do. In addition, when employ | adopting the method of (2)-(4), it is desirable to grasp | ascertain the quantity of the solvent in a dissolution tank.

  The method for dissolving the PAI resin in the organic solvent is not particularly limited, but the PAI resin and the organic solvent are placed in a container used as a dissolution tank and dissolved while stirring. If not dissolved at room temperature, dissolve by heating. In order to produce fine PAI resin particles having a uniform particle size, a method in which the PAI resin is completely dissolved in an organic solvent and then added to the solvent to be precipitated or precipitated by flash crystallization is preferable. May be present.

The dissolution temperature of the PAI resin in the organic solvent varies depending on the type of the organic solvent used and the concentration of the PAI resin, but is usually room temperature to 250 ° C, preferably room temperature to 100 ° C.
The dissolution time of the PAI resin in the organic solvent varies depending on the type of the organic solvent, the charged concentration of the PAI resin, and the dissolution temperature, but is usually 5 minutes to 5 hours, preferably 10 minutes to 4 hours.
By the above operation, the PAI resin can be dissolved in the organic solvent.

In the dissolution step (a1) in the present invention, the PAI resin concentration is set to a PAI resin solution A1 having a PAI resin concentration of less than 5% by mass (hereinafter sometimes referred to as a solution A1).
The viscosity of the PAI resin solution A1 increases rapidly as the concentration of the PAI resin increases. For example, when the organic solvent is NMP, when the PAI resin concentration is 5% by mass, the viscosity of the PAI resin solution is 11 mPa · s, whereas 10% by mass is 54 mPa · s, 15% by mass is 225 mPa · s, In 20 mass%, it increases rapidly with 837 mPa * s (measured by the viscosity measuring method mentioned later).

If the viscosity of the PAI resin solution A1 is high, when the PAI resin solution A1 is added to a solvent for precipitating the PAI resin particles in the precipitation step (a2) described later, Adhesion or the like occurs and fine particles having a small particle size or a uniform particle size cannot be obtained.
Therefore, when the PAI resin solution A1 is added to the solvent for precipitating the PAI resin, the amount of the PAI resin used is usually less than 5 parts by mass with respect to 100 parts by mass in total of the organic solvent and the PAI resin. Is 0.1 to 5 parts by mass, more preferably 0.5 to 4 parts by mass.

On the other hand, in the dissolution step (b1), the PAI resin concentration is set to a PAI resin solution B1 having a concentration of less than 10% by mass (hereinafter sometimes referred to as a solution B1).
That is, when the PAI resin fine particles are produced using flash crystallization as in the precipitation step (b2) to be described later, if the PAI resin concentration in the PAI resin solution B1 is less than 10% by mass, it is stable. Thus, it is possible to produce PAI resin fine particles. That is, the amount of the PAI resin used in the dissolving solution B1 in the dissolving step (b1) is less than 10 parts by mass, preferably 0.1 parts by mass or more to 10 parts by mass with respect to 100 parts by mass in total of the PAI resin and the organic solvent. The amount is less than part by mass, more preferably 0.5 parts by mass or more and 7 parts by mass or less.
If it is the said range, in a precipitation process (b2), PAI resin microparticles | fine-particles are applicable to industrial production. In the present invention, a PAI resin is charged in the organic solvent and dissolved at room temperature or heated, and then the PAI resin solution is subjected to a precipitation step described later.

[Precipitation process]
The precipitation step in the present invention is selected from the precipitation steps (a2) and (b2).

[Precipitation step (a2)]
In the precipitation step (a2), the PAI resin solution A1 obtained in the dissolution step (a1) was charged with a solvent (hereinafter referred to as a precipitation solvent) that precipitates PAI resin fine particles substantially not containing a surfactant. The PAI resin fine particles are precipitated by adding in another container (hereinafter sometimes referred to as a receiving tank) or in a precipitation solvent in the receiving tank. In the precipitation step (a2), the PAI resin solution A1 dissolved under normal pressure conditions (or pressure conditions may be added) is added to the receiving tank or the precipitation solvent in the receiving tank under normal pressure conditions.

  The addition in the precipitation step (a2) simply means putting the PAI resin solution A1 into the precipitation solvent. Even if the PAI resin solution A1 is continuously poured into a container containing the solvent for precipitating the PAI resin. It may be good or may be dripped.

  The precipitation solvent for precipitating the PAI resin fine particles is not particularly limited, but from the viewpoint of uniformly dispersing the PAI resin solution A1 in the precipitation solvent, a solvent that is uniformly mixed with the organic solvent used in the dissolving step. Preferably there is. Here, uniform mixing means that when an organic solvent that dissolves the PAI resin and the solvent for precipitation are mixed, an interface does not appear even if the mixture is allowed to stand for one day, and is mixed uniformly. For example, with respect to water, NMP, DMF, DMAc, acetone, DMSO, tetrahydrofuran, methanol, ethanol and the like can be mentioned as a solvent in which they are uniformly mixed.

  Furthermore, from the point that fine PAI resin fine particles are obtained and the particle diameter is easily uniform, the precipitation solvent is a solvent that is uniformly mixed with the organic solvent used in the dissolution step (a1), and the PAI resin It is preferable that the solvent is a poor solvent or includes a poor solvent and a solvent that is uniformly mixed with the organic solvent used in the dissolution step (a1). In addition, since the solubility with respect to PAI resin changes with temperature even if it is the same solvent, the poor solvent here is a solvent which is hard to dissolve PAI resin at the temperature at the time of adding PAI resin solution A1, that is, Any solvent that can precipitate the PAI resin dissolved in the PAI resin solution A1 to be added can be used as a poor solvent. Therefore, even if it is an organic solvent which can be used for the solution A1, it can be used as a poor solvent if it is an organic solvent that lowers the solubility of the PAI resin to a desired level by lowering the temperature.

  For example, as a solvent for precipitation used in the precipitation step (a2), when NMP is selected as the organic solvent in the dissolution step (a1), NMP, alcohols, acetones, water and the like can be used. The solvent for precipitation can select the solvent to precipitate according to the objective. As the precipitation solvent, it is preferable to use water because it is easy to obtain fine PAI resin particles having a uniform particle size.

In addition, the precipitation solvent used in the precipitation step (a2) may be a single solvent or a mixture of two or more solvents as long as it is uniformly mixed with the organic solvent used in the dissolution step (a1). However, it is preferable to use a mixed solvent containing water from the viewpoint that fine particles having a uniform particle diameter are easily obtained.
Although the usage-amount of the solvent for precipitation used at a precipitation process (a2) is not specifically limited, The range of 0.3-100 mass parts can be illustrated with respect to 1 mass part of organic solvents of a melt | dissolution process (a1), Preferably Is 0.4-50 parts by mass, more preferably 0.4-10 parts by mass.

  When the PAI resin solution A1 is added to the precipitation solvent, the receiving tank charged with the precipitation solvent may or may not be cooled. By this addition, PAI resin fine particles are precipitated from the PAI resin solution A1, and a liquid in which the PAI resin fine particles are dispersed or suspended (hereinafter referred to as suspension A2) is obtained. When the receiving tank is cooled, it is cooled with a refrigerant or ice water. Although the cooling temperature of the receiving tank varies depending on the precipitation solvent used, the freezing point to the freezing point + 50 ° C. of the precipitation solvent for the PAI resin fine particles, specifically, when water is used as the precipitation solvent, the temperature immediately before the addition is 0. -40 degreeC is preferable and 0-30 degreeC is more preferable. Moreover, it is preferable that the solvent for precipitating the PAI resin fine particles is stirred during the addition.

[Precipitation step (b2)]
In the precipitation step (b2), the PAI resin solution B1 obtained in the dissolution step (b1) is flash crystallized to precipitate PAI resin fine particles.

  In the present invention, flash crystallization refers to the PAI resin solution B1 in the dissolution tank under heating and pressurization, and the temperature and pressure in the receiving tank charged with the precipitation solvent in the dissolution step (b1). It is controlled to below the boiling point of the organic solvent (the tank may be cooled) and below the pressure of the dissolution tank (may be under reduced pressure), and the nozzle is inserted into the controlled receiving tank or the precipitation solvent in the receiving tank. The pressure in the receiving tank charged with the deposition solvent is controlled to be equal to or lower than the pressure in the dissolving tank (or under reduced pressure). It refers to a method in which fine particles are crystallized by being ejected through a nozzle and transferred into a precipitation solvent in a tank or a receiving tank.

  When flash crystallization of the PAI resin solution B1 is performed, the nozzle tip is separated from the deposition solvent and deposited via the gas phase even when the tip of the nozzle from which the PAI resin solution B1 is ejected is placed in the solvent on the receiving tank side. Although it may be flushed in the solvent, it is preferable to flush by putting the tip of the nozzle in the solvent for precipitation.

In the production of PAI resin fine particles by flash crystallization of the PAI resin solution B1, PAI fine particles having an average primary particle size of 300 nm or less, particularly 200 nm or less can be obtained by controlling the concentration of the PAI resin to a predetermined concentration or less.
Moreover, in the flash crystallization, the PAI resin solution B1 is pushed out at a high pressure at a time, so that the PAI resin solution B1 diffuses into the precipitation solvent in the receiving tank in a shorter time and is fine, spherical or nearly spherical. Produces. When flash crystallization is performed by putting the tip of the nozzle in a precipitation solvent, the PAI resin solution B1 directly contacts the precipitation solvent and diffuses, so that fine, more spherical or near-spherical PAI fine particles can be obtained. Can do. Therefore, it is more preferable to use flash crystallization which flashes in the precipitation solvent.

  Further, the flash crystallization in the precipitation step (b2) is performed by flash crystallization of the PAI resin solution B1 in the dissolution tank held under pressure under heating or pressure in a receiving tank under atmospheric pressure (may be under reduced pressure). It is preferable to carry out by doing. For example, in the dissolution step (b1), when heated and dissolved in a pressure-resistant container such as an autoclave as a dissolution tank, the inside of the container is pressurized by a self-produced pressure by heating (may be further pressurized with an inert gas such as nitrogen) ). By releasing the pressure from this state and releasing it into a receiving tank under atmospheric pressure, the PAI resin fine particles can be deposited more easily. In the dissolution step (b1), when the PAI resin is dissolved in an organic solvent at room temperature and under pressure, the PAI resin solution B1 is added to the precipitation solvent in the receiving tank under atmospheric pressure (or under reduced pressure). PAI resin fine particles can be obtained by flash crystallization.

The precipitation solvent used in the precipitation step (b2) is not particularly limited, and is the same as described in the precipitation step (a2), for example, a solvent that is uniformly mixed with the organic solvent used in the dissolution step (b1). Moreover, it is a poor solvent of the PAI resin, or a mixed solution of a solvent and a poor solvent that are uniformly mixed with the organic solvent used in the dissolution step (b1) can be used.
Although the usage-amount of the solvent for precipitation used at a precipitation process (b2) is not specifically limited, The range of 0.3-100 mass parts can be illustrated with respect to 1 mass part of organic solvents used at a melt | dissolution process (b1). , Preferably it is 0.4-50 mass parts, More preferably, it is 0.4-10 mass parts.

  The flash crystallization method in the precipitation step (a2) is not particularly limited, but it is usually at a room temperature to 250 ° C., preferably at a temperature equal to or lower than the pressure at which the solution B1 at room temperature to 100 ° C. is pressurized, or one step in a container under reduced pressure. Or a method of flash crystallization in multiple stages in a vessel having a lower pressure than that in the dissolution tank containing the solution B1. Specifically, for example, in the melting step, when heated and dissolved in a pressure vessel such as an autoclave as a dissolution tank, the inside of the vessel is pressurized by a self-produced pressure by heating (further added with an inert gas such as nitrogen). Pressure). The solution B1 in a pressurized state is flushed in an atmospheric pressure receiving tank containing a solvent for precipitation of PAI resin fine particles, or is flushed in a receiving tank under reduced pressure. In addition, when dissolved in a pressure vessel such as an autoclave without heating, the solution B1 pressurized to an arbitrary pressure is flushed into an atmospheric pressure receiving tank containing a solvent for precipitation of PAI resin particles. Or flush into a receiving tank under reduced pressure. The pressure (gauge pressure) of the solution for flash crystallization is preferably 0.2 to 4 MPa. From this environment, it is preferable to perform flash crystallization, preferably flash crystallization in a receiving tank under atmospheric pressure, more preferably under atmospheric pressure.

  When the PAI resin fine particle solution B1 is subjected to flash crystallization, the receiving tank may be cooled or not cooled. PAI resin fine particles are precipitated from the PAI resin solution B1 by flash crystallization, and a liquid in which the PAI resin fine particles are dispersed or suspended (hereinafter referred to as flash liquid B2) is obtained. A dispersed liquid (hereinafter sometimes referred to as a dispersion liquid) refers to a liquid in which fine particles do not settle even if the liquid is allowed to stand for 1 day or more, and an interface between the dispersion medium and the fine particles does not appear, A suspended liquid (hereinafter sometimes referred to as a suspension) refers to a liquid in which fine particles settle out when allowed to stand for one day and an interface between the dispersion medium and the fine particles appears. Here, the dispersion liquid or suspension medium of the PAI resin fine particles is a mixture of an organic solvent used in the dissolution step and a precipitation solvent used in the precipitation step. When the receiving tank is cooled, it is cooled with a refrigerant or ice water. Although the cooling temperature of the receiving tank varies depending on the solvent for precipitation, the temperature at which the solvent for precipitating the PAI resin fine particles does not solidify to 15 ° C. Specifically, when water is used as the solvent for precipitation, the temperature immediately before flash crystallization is 0. -40 degreeC is preferable and 0-30 degreeC is more preferable.

  In the flash crystallization method, there is a method in which the outlet of the connecting pipe from the dissolution tank is placed in the atmosphere of the receiving tank or in the solvent for precipitation, and flash crystallization is performed. It is preferable because fine particles can be obtained.

  The PAI resin fine particles obtained by the precipitation step (b2) can be obtained in the state of a dispersion or suspension. At this time, when coarse particles such as an undissolved portion of the charged PAI resin are included, it can be removed by filtration or the like.

  The PAI resin fine particles obtained by the precipitation step (a2) and the precipitation step (b2) are fine particles having an average primary particle size of 100 nm to 300 nm, and more preferably 100 nm to 200 nm. The lower limit of the primary particle size of the PAI resin fine particles is about 90 nm. Further, fine particles having a uniform particle size can be obtained, and polyamideimide resin fine particles having a coefficient of variation of usually 70% or less, and in a preferred embodiment 60% or less are obtained.

[Filtration / isolation process]
In the present invention, the method for isolating the PAI resin fine particles from the suspension A2 or the flash solution B2 containing the PAI resin fine particles obtained in the precipitation steps (a2) and (b2) includes filtration, centrifugation, centrifugal filtration, etc. The conventionally known solid-liquid separation method can be used. In order to efficiently isolate fine PAI resin particles having an average primary particle size of 300 nm or less by solid-liquid separation operation, after increasing the particle size by aggregation, solid-liquid separation operations such as filtration and centrifugation are performed. It is desirable. As a method for increasing the particle size by agglomeration, a natural agglomeration method for agglomeration with time, an agglomeration method by salting out, or the like can be used. By using these aggregation methods, aggregates having a large particle size suitable for industrial solid-liquid separation methods can be obtained. The average particle size of the PAI resin fine particles obtained by aggregation is 5 to 100 μm (particle size according to the measurement method described later), preferably 20 to 100 μm.

  Specifically, in the case of the natural agglomeration method, the suspension A2 or the flash solution B2 obtained in the precipitation steps (a2) and (b2) is allowed to stand for 1 day or more, or an inorganic metal salt, or 0.01 to 1000 parts by mass, preferably 0.02 to 500 parts by mass, based on 1 part by mass of PAI resin fine particles, an organic metal salt (which may be abbreviated as a salting-out agent together with inorganic metal salt and organic metal salt) Agglomerates having a large particle size can be obtained by salting out to an extent. When the resin fine particles are aggregated by salting out, specifically, a salting-out agent is added directly to the suspension A2 or the flash solution B2, or a 0.1 to 20% by mass solution of the salting-out agent is added. Examples thereof include a method of adding to the suspension A2 or the flash solution B2. Examples of the inorganic metal salt used as the salting-out agent include sodium chloride, magnesium chloride, calcium chloride, lithium chloride, and potassium chloride. Examples of the organic metal salt used as the salting-out agent include sodium acetate, magnesium acetate, calcium acetate, sodium oxalate, magnesium oxalate, calcium oxalate, sodium citrate, magnesium citrate, and calcium citrate. As a solvent for dissolving the salting-out agent, water is preferable. The salting-out agent may be added in advance to the precipitation solvent in the precipitation step (a2) or the precipitation step (b2) and dissolved. In this case, water is preferable as the solvent for precipitation of the PAI resin fine particles. The amount of the salting-out agent to be added is preferably 0.01 parts by mass or more with respect to 1 part by mass of the PAI resin fine particles and less than or equal to the saturated dissolution amount in the solvent in which the PAI resin fine particles are precipitated. The PAI resin fine particles obtained by the precipitation step (a2) or (b2) as in the present invention can be easily solid-liquid separated by agglomeration by such a method. Further, PAI resin fine particles that are extremely easily redispersed can be obtained even if they are aggregated by such a method.

Examples of the method for solid-liquid separation of the PAI resin fine particles obtained by the aggregation include methods such as filtration and centrifugation. In the case of filtration or centrifugation, a membrane filter (filtration) or a filter cloth (filtration, centrifugation) can be used. The opening of the filter is appropriately determined according to the particle size of the PAI resin fine particles to be obtained. In the case of a membrane filter, it is usually about 0.1 to 50 μm. In the case of a filter cloth, the air permeability is 5 cm ³ / cm. Those of ² · sec at 124.5 Pa or less can be used. In order to redisperse the wet cake after solid-liquid separation in a dispersion medium to prepare a dispersion (dispersion step), the solvent in the wet cake is replaced with a dispersion medium used in the dispersion step. In order to replace with the dispersion medium, the wet cake may be reslurried with the dispersion medium used in the dispersion process, or may be washed by washing with the dispersion medium used in the dispersion process.

[Dispersion process]
The PAI resin fine particle dispersion of the present invention is obtained by redispersing the aggregated PAI resin fine particles by mechanically dispersing the PAI resin fine particles obtained in the filtration / isolation step together with a surfactant and a dispersion medium. A PAI resin fine particle dispersion is obtained. In order to obtain a PAI resin fine particle dispersion liquid having a desired average particle size, the PAI resin fine particles used in the dispersion step contain a dispersion medium. It is necessary to keep it in a state. The PAI resin fine particles used in the dispersion step are preferably in a state containing 50% by mass or more of a dispersion medium.

  In the PAI resin fine particle dispersion of the present invention, the solvent used as a dispersion medium is, for example, a straight chain having 1 to 6 carbon atoms such as pentane, hexane, heptane, octane, cyclohexane, cyclopentane, decane, dodecane, tridecane, and tetradecane. Chain or cyclic aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents such as benzene, toluene, xylene and 2-methylnaphthalene, ester systems such as ethyl acetate, methyl acetate, butyl acetate, butyl propionate and butyl butyrate Solvent, chloroform, bromoform, methylene chloride, 1,2-dichloroethane, 1,1,1-trichloroethane, chlorobenzene, o-dichlorobenzene, p-dichlorobenzene, 2,6-dichlorotoluene, 1-chloronaphthalene, hexafluoroisopropanol Halogen solvents such as C1-C6 linear or branched ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl butyl ketone, etc., C1-C6 such as methanol, ethanol, isopropanol, n-propanol, etc. Linear or branched alkyl having 1 to 6 carbon atoms on the nitrogen in the lactam ring such as linear or branched alcohol solvents, N-methyl-2-pyrrolidinone, N-ethyl-2-pyrrolidinone, etc. A linear or branched alkyl group having 1 to 6 carbon atoms in the nitrogen in the lactam ring such as N-alkylpyrrolidinone solvent, N-methyl-ε-caprolactam, N-ethyl-ε-caprolactam, etc. -Bonded N-alkylcaprolactam solvents, 1,3-dimethyl-2-imidazolidinone, N, N-dimethylacetamide, N, N-dimethyl Polar solvents such as formamide, hexamethylphosphoric triamide, dimethyl sulfoxide, dimethyl sulfone, tetramethylene sulfone, straight chain having 1 to 6 carbon atoms such as diethyl ether, tetrahydrofuran, diisopropyl ether, dioxane, diglyme, dimethoxyethane, An organic solvent such as a branched or cyclic ether solvent, and at least one solvent selected from water can be exemplified. Water or a linear or branched alcohol solvent having 1 to 6 carbon atoms, a ketone solvent in which the same or different alkyl group having 1 to 6 carbon atoms is bonded to the carbonyl carbon, nitrogen in the lactam ring N-alkylpyrrolidinone in which a linear or branched alkyl group having 1 to 6 carbon atoms is bonded to is preferable. When an organic solvent is used in the manufacturing process of electronic parts, etc., and the use of water is not preferred, a dispersion of the organic solvent is used. Applications such as water-based paints and aqueous coating agents, and applications where water can be used in the manufacturing process of components Then, an aqueous dispersion is used. Thus, depending on the application, a dispersion liquid using an organic solvent as a dispersion medium and a dispersion liquid using water as a dispersion medium are properly used, and a PAI resin fine particle dispersion liquid that can select a dispersion medium according to the application is required. .

  The PAI resin fine particle dispersion of the present invention is subjected to a dispersion step by adding a surfactant and a dispersion medium to the aggregated PAI resin fine particles obtained by solid-liquid separation operation or the like. In order to suppress reaggregation of PAI resin fine particles generated by mechanical dispersion and improve dispersibility in the dispersion medium, a surfactant is added. Surfactant may be added before or after mechanical dispersion, but to prevent aggregation of PAI resin fine particles during mechanical dispersion, addition before dispersion, or addition method using both addition before dispersion and addition during dispersion Is preferred.

  The surfactant used in the present invention is not particularly limited as long as it is soluble in the dispersion medium to be used. Cationic surfactants, anionic surfactants, zwitterionic surfactants, nonionic surfactants, polymers Surfactant etc. are mentioned.

  Examples of anionic surfactants include fatty acid sodium, fatty acid potassium, sodium alkyl sulfate ester, sodium polyoxyethylene alkyl ether sulfate ester, sodium alkylbenzene sulfonate, sodium alkyl naphthalene sulfonate, sodium alkyl diphenyl ether disulfonate, polyoxyethylene alkyl ether Sodium sulfate ester, sodium alkyl sulfonate, dipotassium alkenyl succinate, sodium alkyl ether sulfate, potassium monoalkyl phosphate, potassium polyoxyethylene alkyl ether phosphate, sodium fatty acid ester sulfonate, sodium fatty acid ester sulfate, fatty acid alkylose amide Sodium sulfate ester, sodium fatty acid amide sulfonate And the like.

  Examples of the cationic surfactant include alkylmethylammonium chloride, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkyldimethylbenzylammonium chloride, and alkylpyridinium chloride.

  Examples of zwitterionic surfactants include alkylaminocarboxylates, carboxybetaines, alkylbetaines, sulfobetaines, and phosphobetaines.

  Nonionic surfactants include sucrose fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene lanolin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene glycol mono fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene Oxyethylene monobenzyl phenyl ether, polyoxyethylene dibenzyl phenyl ether, polyoxyethylene tribenzyl phenyl ether, polyoxyethylene monostyryl phenyl ether, polyoxyethylene distyryl phenyl ether, polyoxyethylene tristyryl phenyl ether, polyoxyethylene Biphenyl ether, polyoxyethylene phenoxyphenyl ether, polyoxyethylene cumylphenyl ether Ether, polyoxyethylene alkyl ethers, fatty acid alkanolamides, fatty acid monoethanolamide, fatty acid diethanolamide, fatty acid triethanol amide, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amines, and alkyl alkanol amides.

  In the examples of the surfactant, the alkyl includes a straight-chain saturated hydrocarbon group having 1 to 30 carbon atoms or a branched saturated hydrocarbon group. A linear unsaturated hydrocarbon group or a branched unsaturated hydrocarbon group may be used instead of alkyl.

Polymeric surfactants include polyvinylpyrrolidone (PVP), polypyrrole, polythiophene, (meth) acrylic acid copolymer, maleic acid copolymer, polystyrene sulfonate, vinylpyridine copolymer, polyethyleneimine, polyvinyl alcohol, polyvinyl ether, synthetic polymer surfactant such as polyacrylamide, Cal Bo carboxymethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyethyl Seth loin, semisynthetic polymer surfactant such as hydroxypropyl methylcellulose is used.

  In addition, the polymeric surfactant is a non-ionic surfactant, an anionic surfactant, and other general surfactants with a structure having a pair of hydrophilic groups and lipophilic groups in the molecule. The surfactant has a complicated structure having a large number of hydrophilic groups and lipophilic groups, and has a large molecular weight. Thus, general surfactants and polymer surfactants are greatly different both in structure and molecular weight. The polymer surfactant used in the present invention is preferably a polymer surfactant having a number average molecular weight of 1000 or more (GPC measurement, styrene conversion), and more preferably 5,000 or more. Although there is no restriction | limiting in particular as an upper limit, It is preferable that it is 1,000,000 or less.

The addition amount of the surfactant in the PAI resin fine particle dispersion of the present invention is in the range of 0.01 to 100 parts by mass, preferably in the range of 0.5 to 100 parts by mass with respect to 100 parts by mass of the PAI resin fine particles. More preferably, it is the range of 1-100 mass parts. By using an amount of the surfactant in this range, the PAI resin fine particles obtained by mechanical dispersion can be uniformly dispersed in the dispersion medium.
Further, the mixing ratio of the PAI resin fine particles and the dispersion medium in the PAI resin fine particle dispersion of the present invention is preferably in the range of 1 to 50 parts by mass of PAI resin fine particles with respect to 100 parts by mass of the dispersion medium. It is preferably ~ 30 parts by mass.

In the present invention, the PAI resin fine particles obtained in the filtration / isolation step are mechanically dispersed so that the average particle size is minimized. The average particle diameter of the PAI resin fine particles in the PAI resin fine particle dispersion after mechanical dispersion is 500 nm or less in the measurement method described later. Even in the PAI resin fine particle dispersion, coarse particles and precipitates may be included in some cases. In that case, coarse particles or precipitates may be separated from the dispersed portion. When only the dispersion liquid is obtained, the coarse particles and precipitates may be separated from the dispersion portion. For that purpose, decantation, filtration, centrifugation, etc. may be performed to remove the coarse particles and precipitate portions.
In the present specification, the dispersion means a state in which the interface between the PAI resin fine particles and the dispersion medium does not appear even after standing at room temperature (25 ° C.) for 1 day or longer.

  In the present invention, the PAI resin fine particles obtained in the filtration / isolation step are preferably mechanically dispersed together with the surfactant and the dispersion medium until the average particle size becomes 500 nm or less by a measurement method described later. . In the PAI resin fine particle dispersion of the present invention, the lower limit of the average particle diameter of the dispersed PAI resin fine particles is not limited, but is preferably 100 nm or more from the viewpoint of suppressing aggregation.

  Examples of the mechanical dispersion device used in the present invention include a commercially available mechanical dispersion device. In particular, an ultrasonic dispersion device, a ball mill device, a bead mill device, a sand mill device, a colloid mill device are suitable as a mechanical dispersion device for efficiently dispersing PAI resin fine particles and preparing a dispersion of PAI resin fine particles having a small particle size. , Wet jet mill device, wet atomizer (eg, Sugino Machine Ultimate), among others, ultrasonic dispersion device, bead mill device, colloid mill device, wet atomizer, wet jet mill device The device is preferred. The average particle size of PAI resin particles obtained as the dispersion force during mechanical dispersion generally increases and the dispersion time becomes longer tends to decrease. However, if these are excessive, reaggregation tends to occur. , Controlled to an appropriate range. For example, the bead mill can be controlled by selecting the bead diameter and the bead amount and adjusting the peripheral speed, and the ultrasonic dispersing device can be controlled by selecting the ultrasonic frequency and adjusting the ultrasonic output.

As described above, a highly stable dispersion of PAI resin particles in which the PAI resin particles are finely dispersed can be obtained.
Such a fine PAI resin fine particle dispersion does not agglomerate PAI resin fine particles even when allowed to stand at room temperature (25 ° C.) for 5 days, and is a particularly useful addition in the paint, adhesive and polymer compound fields. It can be used as an agent.

[Measurement of average particle size]
The average particle size of the PAI resin fine particles is Nikkiso's laser diffraction / scattering type particle size distribution analyzer MT3300EXII, and the dispersion medium is polyoxyethylene cumylphenyl ether (trade name Nonal 912A, manufactured by Toho Chemical Industries, hereinafter referred to as Nonal 912A) It measured using 0.5 mass% aqueous solution. Specifically, the cumulative curve is obtained by setting the total volume of fine particles obtained by analyzing the scattered light of the laser by the microtrack method to 100%, and the particle diameter (median diameter: d50) at which the cumulative curve becomes 50% is obtained. The average particle size of the fine particles was used.

[Measurement of average primary particle size]
In the present invention, the average primary particle size is selected from 100 images (magnification: 30,000 times) obtained with a scanning electron microscope JEOL JMS-6700F manufactured by JEOL Ltd. The particle diameter was measured as the diameter, and the average value was defined as the average primary particle diameter.

[Mechanical dispersion]
Mechanical dispersion is an ultrasonic homogenizer manufactured by Nippon Seiki Co., Ltd., US-300T (ultrasonic oscillator: rated output 300 W, oscillation frequency 19.5 KHz ± 1 KHz (automatic frequency tracking type), ultrasonic transducer: φ26 mm PZT (bolt clamped strain type) The ultrasonic oscillation chip was adjusted in contact with the PAI resin fine particle dispersion so as to obtain a predetermined output using a vibration element.

Production Example 1
[Dissolution process]
A 10 L autoclave was used as a dissolution tank, and a stirrer, a temperature measuring device, and an internal solution extraction pipe were attached to the autoclave. A connecting pipe that can be opened and closed is attached to the extraction pipe. In addition, a 50 L pressure tank is used as a receiving tank for flash crystallization, and the other end (flash crystal precipitation port) of the connecting pipe attached to the stirrer, condenser, gas vent pipe, and dissolution tank is connected to the pressure tank. It was mounted at a position that entered the solvent for precipitation.
A dissolution tank was charged with 180 g of PAI resin (manufactured by Toray Industries, Inc., TI-5013P) and 5,820 g of NMP (manufactured by Kanto Chemical Co., Ltd.) (PAI resin concentration: 3% by mass), sealed with nitrogen, and sealed for 1 hour at room temperature. After stirring, the pressure was increased to 0.5 MPa with nitrogen gas.
[Precipitation process]
Into the receiving tank, 6,000 g of water was added as a solvent for precipitation, and the tip of the connecting pipe installed in the receiving tank was put in water. The receiving tank was ice-cooled and nitrogen gas was vented. At this time, the temperature of the receiving tank was 5 ° C. The valve of the connecting pipe of the dissolution tank was opened, and the PAI resin solution was flash crystallized in the receiving water to obtain a flash liquid.
Next, 180 g of a 5 mass% magnesium acetate aqueous solution was added to the flash solution, stirred for 30 minutes, and allowed to stand for 1 hour. The suspension was filtered and washed with water to obtain a PAI resin fine particle wet cake (solid content concentration: 17.5% by mass). The average primary particle size was 110 nm.

Example 1
To 34.3 g of the PAI resin fine particle wet cake of Production Example 1, 12 g of a 10 mass% polyoxyethylene oleyl ether (ethylene oxide 24 mol adduct) aqueous solution and 28.7 g of ion-exchanged water were added, and the suspension was stirred at 1400 rpm for 10 minutes. Got. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 287 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 200 nm. This dispersion was stable without agglomeration even when allowed to stand for 5 days at room temperature.

Example 2
To 34.3 g of the PAI resin fine particle wet cake of Production Example 1, 12 g of a 10 mass% polyoxyethylene oleyl ether (ethylene oxide 40 mol adduct) aqueous solution and 28.7 g of ion-exchanged water were added, and the suspension was stirred at 1400 rpm for 10 minutes. Got. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 285 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 200 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Example 3
Latem ASK (Kao Corporation, dipotassium alkenyl succinate) 4.3 g and ion-exchanged water 36.4 g were added to 34.3 g of PAI resin fine particle wet cake of Production Example 1 and stirred at 1400 rpm for 10 minutes to obtain a suspension. It was. The suspension was treated with ultrasonic waves (120 W) for 40 minutes, and dispersed to an average particle size of 288 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 198 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Example 4
Neoperex G-15 (Kao Corporation, dodecylbenzenesulfonic acid) 7.5 g and ion-exchanged water 33.2 g were added to 34.3 g of the PAI resin fine particle wet cake of Production Example 1 and suspended by stirring at 1400 rpm for 10 minutes. A liquid was obtained. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 290 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 198 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Example 5
1.2 g of polyvinylpyrrolidone K30 (Tokyo Kasei Co., Ltd.) and 39.5 g of ion-exchanged water were added to 34.3 g of the PAI resin fine particle wet cake of Production Example 1 and stirred at 1400 rpm for 10 minutes to obtain a suspension. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 286 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 199 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Example 6
1.2 g of polystyrene carboxylic acid (Tosoh Corporation) and 39.5 g of ion-exchanged water were added to 34.3 g of the PAI resin fine particle wet cake of Production Example 1 and stirred at 1400 rpm for 10 minutes to obtain a suspension. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 290 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 200 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Example 7
Water in the PAI resin fine particle wet cake of Production Example 1 was replaced with isopropyl alcohol to obtain a wet cake of isopropyl alcohol (solid content concentration: 17.9% by mass). To 20.9 g of the wet cake, 0.75 g of polyvinylpyrrolidone K30 (Tokyo Kasei Co., Ltd.) and 53.4 g of isopropyl alcohol were added and stirred at 1400 rpm for 10 minutes to obtain a suspension. The suspension was treated with ultrasonic waves (120 W) for 40 minutes, and dispersed to an average particle size of 1.5 μm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 240 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Example 8
Water in the PAI resin fine particle wet cake of Production Example 1 was replaced with n-propyl alcohol to obtain a wet cake of n-propyl alcohol (solid content concentration: 18.3 mass%). To 20.5 g of the wet cake, 0.75 g of polyvinylpyrrolidone K30 (Tokyo Kasei Co., Ltd.) and 53.9 g of n-propyl alcohol were added and stirred at 1400 rpm for 10 minutes to obtain a suspension. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 1.7 μm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 248 nm. This dispersion was stable without agglomeration even when allowed to stand at room temperature for 5 days.

Comparative Example 1
40.7 g of ion-exchanged water was added to 34.3 g of the PAI resin fine particle wet cake of Production Example 1 and stirred at 1400 rpm for 10 minutes to obtain a suspension. The suspension was treated with ultrasonic waves (120 W) for 40 minutes and dispersed to an average particle size of 292 nm. Coarse particles were removed by centrifugation to obtain a dispersion having an average particle size of 200 nm. When this dispersion was allowed to stand at room temperature, it gradually aggregated, and the average particle size after 2 days was 4.5 μm.

Comparative Example 2
To 20.9 g of the wet cake of Example 7, 54.1 g of isopropyl alcohol was added and stirred at 1400 rpm for 10 minutes to obtain a suspension. The suspension was treated with ultrasonic waves (120 W) for 40 minutes, but could only be dispersed up to an average particle size of 5.5 μm.

Claims (6)

Polyamideimide resin fine particles having an average primary particle size of 100 nm to 300 nm , polyoxyethylene oleyl ether, dipotassium alkenyl succinate, dodecylbenzenesulfonic acid, polyvinyl pyrrolidone, polystyrene carboxylic acid, (meth) acrylic acid copolymer, and carboxymethyl cellulose A polyamidoimide resin fine particle dispersion comprising at least one surfactant selected from : and a dispersion medium. 2. The polyamideimide resin according to claim 1, wherein the surfactant is at least one surfactant selected from polyoxyethylene oleyl ether, dipotassium alkenyl succinate, dodecylbenzene sulfonic acid, polyvinyl pyrrolidone, and polystyrene carboxylic acid. Fine particle dispersion.   The polyamideimide resin fine particle dispersion according to claim 1, wherein the dispersion medium is water or an organic solvent.   The polyamideimide resin fine particle dispersion according to claim 3, wherein the organic solvent is an alcohol solvent, a ketone solvent, or an N-alkylpyrrolidinone solvent.   The alcohol solvent is a linear or branched alcohol solvent having 1 to 6 carbon atoms, and the ketone solvent has a carbonyl carbon bonded to the same or different alkyl group having 1 to 6 carbon atoms. The N-alkylpyrrolidinone solvent is a N-alkylpyrrolidinone in which a linear or branched alkyl group having 1 to 6 carbon atoms is bonded to nitrogen in the lactam ring. The polyamideimide resin fine particle dispersion described in 1. At least one surfactant selected from polyoxyethylene oleyl ether, dipotassium alkenyl succinate, dodecylbenzene sulfonic acid, polyvinyl pyrrolidone, polystyrene carboxylic acid, (meth) acrylic acid copolymer, and carboxymethyl cellulose , average primary particles A method for producing a polyamideimide resin fine particle dispersion comprising a dispersion step of mechanically dispersing a mixture of polyamideimide resin fine particles having a diameter of 100 nm to 300 nm and a dispersion medium.