TW201807021A - Polyimide powder and method for producing same - Google Patents

Abstract

Provided are: a polyimide powder which forms a polyimide film having excellent heat resistance and transparency, and which is soluble in a solvent, while being reduced in coloring or impurities; and a method for producing this polyimide powder. A polyimide powder which is soluble in N, N-dimethyl acetamide, and which is produced through steps of: polymerization from at least one aromatic diamine compound and at least one tetracarboxylic acid dianhydride into a polyamide acid; a chemical imidization reaction; formation of a powder by means of precipitation of a produced polyimide; and drying. This polyimide powder is characterized in that: the average particle diameter of this polyimide powder is within the range of 0.02-0.8 mm; and a polyimide film, which is formed from an N, N-dimethyl acetamide solution of this polyimide powder and has a thickness of 50 [mu]m, has a light transmittance of 80% or more at the wavelength of 450 nm.

Description

Polyfluorene imide powder and manufacturing method thereof

The present invention relates to a polyimide powder and a method for manufacturing the same, and more particularly to a polyimide film which can be suitably used for display applications and electronic material applications, and which can impart excellent heat resistance and transparency. Imine powder and its manufacturing method.

Polyimide resins, as plastics with excellent heat resistance, are used in a wide range of applications requiring heat resistance and high reliability, such as aerospace, electrical insulation, and electronics. In recent years, transparent polyfluorene imines having both heat resistance and transparency have been proposed. For example, Patent Document 1 proposes a soluble polyfluorene imide synthesized from a specific monomer containing a fluorine atom and suitable for optical waveguides having excellent transparency. Patent Document 2 proposes the use of a transparent polyfluorene imide that is soluble in an organic solvent with a specific alicyclic diamine. However, since the polyimide described in Patent Document 1 is heat-treated at a temperature of 300 ° C or higher after film formation, it is difficult to ensure sufficient transparency. The polyimide described in Patent Document 2 Amine has a problem of lacking heat resistance due to the use of an alicyclic diamine as a raw material, and has a problem of coloring by heating.

Polyimide powder revealed in soluble polyimide A method of adding a weak solvent such as water or methanol to an amine varnish to precipitate a block polyimide resin (Patent Document 3).

In addition, Patent Document 4 proposes a powder of a polyimide compound obtained by polymerizing a diamine and an acid dianhydride.

However, the polyimide powder described in Patent Document 3 or Patent Document 4 does not pay much attention to the particle size of the polyimide powder. Therefore, the polyimide powder and the polyimide are contained in the polyimide powder. The removal of the amination accelerator was not sufficiently performed. As a result, the polyimide film obtained from these polyimide powders easily caused coloration, and there was a problem that it was difficult to obtain a polyimide film having excellent transparency.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 4-235505

[Patent Document 2] Japanese Patent Laid-Open No. 2000-169579

[Patent Document 3] Japanese Patent Laid-Open No. 2004-285355

[Patent Document 4] Japanese Patent Publication No. 2013-523939

The object of the present invention is to provide a polyimide powder which can impart a polyimide film excellent in heat resistance and transparency with less coloring, less impurities, and a solvent-soluble polyimide powder, and a method for producing the same.

The present inventors have discovered that by making a polyimide having transparency a powder having a specific average particle diameter, a polyimide that can adversely affect transparency in a polyimide powder and a fluorene can be adversely affected. The residual volatile components of the amination accelerator and the like have been reduced to the limit, and the present invention has been completed.

According to the present invention, a polyimide powder as described below and a method for producing the same are provided.

[1] A polyimide powder, characterized in that at least one aromatic diamine compound and at least one tetracarboxylic dianhydride are polymerized into a polyimide acid, a chemical amidine reaction, and The polyimide powder is formed by precipitation to form a powder, and the polyimide powder soluble in N, N-dimethylacetamide produced in the step of drying, the average of the polyimide powder The particle diameter is in the range of 0.02 ~ 0.8mm. The polyimide film with a thickness of 50 μm is obtained from a film of N, N-dimethylacetamide solution, and the light is at a wavelength of 450nm. The transmittance is above 80%.

[2] Polyimide powder as in [1], in which differential heat is used. The thermogravimetric device measures a weight reduction rate in a range of 200 to 300 ° C in a range of 0 to 0.2%.

[3] Polyimide powder according to [1] or [2], which uses at least one aromatic diamine compound having a fluorine group as the aromatic diamine compound, and uses at least one kind of a fluorine group Tetracarboxylic dianhydride is produced as a tetracarboxylic dianhydride.

[4] A method for producing a polyimide powder having an average particle diameter of 0.02 to 0.8 mm, comprising the following steps: (a) a step of preparing at least one aromatic diamine compound and at least one tetracarboxylic dianhydride; (b) polymerizing the aromatic diamine compound and the tetracarboxylic dianhydride into a polymer by stirring in a solvent; A step of obtaining a polyamic acid solution by the reaction of amidamic acid, (c) adding a fluorinating agent to the obtained polyamic acid solution, and performing a chemical fluorinating reaction to obtain a polyfluorine solution, (d) the step of obtaining the polyfluorene imide powder containing a volatile component while adding the weak solvent of the polyfluorene imide while stirring the obtained polyfluorene imine solution, (e) volatile The polyimide powder of ingredients is dried at a temperature of less than 100 ° C until the amount of volatile components becomes less than 5%, and then dried at a temperature of 100 to 350 ° C for 0.1 to 24 hours to remove the volatile components contained in the powder. , The step of obtaining polyimide powder.

[5] A method for producing polyimide powder, comprising the following steps: (A) adding a weak solvent of polyimide to a polyimide solution containing polyimide dissolved in a solvent In order to precipitate polyimide, and obtain polyimide powder containing volatile components, the weight ratio of the polyimide solution to the weak solvent is 1: 0.5 ~ 1: 10. The step of adding the aforementioned weak solvent per minute from the point before the start of the precipitation of the amine until the precipitation of the powder is completed is a step of 0.0005 to 0.1 times (g / min) of the aforementioned polyimide solution, (B) The volatile component-containing polyfluorene imide powder is not pulverized and dried at a temperature of less than 100 ° C until the amount of the volatile component in the volatile component-containing polyfluorine powder is less than 5%. And further drying at a temperature of 100 to 350 ° C for 0.1 to 24 hours to obtain a polyimide powder.

[6] The method according to [5], wherein the polyimide solution is obtained by the following steps: (A1) a step of preparing at least one aromatic diamine compound and at least one tetracarboxylic dianhydride, (A2 ) Polymerizing the aromatic diamine compound and the tetracarboxylic dianhydride in a solvent to obtain a polyfluorinated acid solution; (A3) adding a fluorinated imidizing agent to the obtained polyfluorinated acid solution and performing a chemical reaction Hydrazone imidization reaction to obtain a polyfluorene imide solution containing polyfluorene imide dissolved in a solvent.

[7] The method according to [6], wherein the step (A3) is performed at a temperature of 10 ° C or more and less than 50 ° C.

[8] The method according to [6] or [7], wherein at least one aromatic diamine compound having a fluorine group is used as the aforementioned aromatic diamine compound, and at least one tetracarboxylic dianhydride having a fluorine group is used As the aforementioned tetracarboxylic dianhydride.

[9] A polyimide powder produced by the method according to any one of [5] to [8].

[10] The polyimide powder according to [9], which is soluble in a solvent.

[11] The polyfluorene imide powder according to [10], wherein the solvent is N, N-dimethylacetamide.

[12] Polyimide powder according to [9], whose average particle diameter is 0.02 ~ 0.8mm range.

[13] The polyimide powder according to [9], wherein the particles having a particle diameter in the range of 0.01 to 2 mm contain 95% by volume or more.

[14] The polyimide powder according to [9], wherein the weight reduction rate in the range of 200 to 300 ° C is in the range of 0 to 0.2%.

[15] The polyimide powder according to [11], which is dissolved in N, N-dimethylacetimide, and a polyimide film having a thickness of 50 μm is prepared from the solution, and the film is measured at 450 nm. When the light transmittance at the wavelength is displayed, a light transmittance of more than 80% is displayed.

[16] The polyimide powder according to [11], which is dissolved in N, N-dimethylacetimide, and a polyimide film having a thickness of 50 μm is prepared from the solution, and the yellowness of the film is measured. (YI), the yellowness (YI) of -5 to 5 is displayed.

[17] A polyimide film obtained by using a polyimide powder system film according to any one of [1] to [3] and [9] to [16].

According to the present invention, it is possible to provide a polyimide powder which can impart impurities such as residual volatile components of a polyimide film excellent in heat resistance and transparency, and has little coloration, and a method for producing the same.

The polyfluorene imide powder system of the present invention uses an aromatic diamine compound and a tetracarboxylic dianhydride, is polymerized to polyfluorinated acid, chemically fluorinated, and formed into a powder by precipitation of polyfluorinated imine. And drying steps Manufactured by step.

Raw material 1.1. Aromatic diamine compounds

As the aromatic diamine compound used in the production of the polyfluorene imine powder of the present invention, if it is reacted with a tetracarboxylic dianhydride in combination, it is used in a common solvent (for example, N, N-dimethylacetamide ( DMAC)) is an aromatic diamine compound that is soluble in polyfluorene imide and can impart specific transparency. Any aromatic diamine compound can be used. Specific examples include m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylsulfide , 3,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfonium, 3,4'-diaminodiphenylsulfonium , 4,4'-diaminodiphenylhydrazone, 3,3'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenyl Methane, 4,4'-diaminodiphenylmethane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (3-aminophenyl) propane, 2- (3- Aminophenyl) -2- (4-aminophenyl) propane, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2, 2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane -1,1,1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1 4,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 3 , 3'-bis (4-aminophenoxy) biphenyl, 3,4'-bis (3-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl ] Sulfide, bis [3- (4-aminobenzene ) Phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [3- (4-aminophenoxy) phenyl] sulfide, bis [3- (3-Aminophenoxy) phenyl] Sulfide, bis [3- (4-aminophenoxy) phenyl] fluorene, bis [4- (4-aminophenylphenyl) fluorene, bis [3- (3-aminophenoxy) phenyl ] 碸, bis [4- (3-aminophenoxy) fluorene, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) benzene Yl] ether, bis [3- (3-aminophenoxy) phenyl] ether, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminobenzene Oxy) phenyl] methane, bis [3- (3-aminophenoxy) phenyl] methane, bis [3- (4-aminophenoxy) phenyl] methane, 2,2-bis [ 4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-amine Phenylphenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2 -Bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (3-aminophenoxy) ) Phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4-aminophenoxy) phenyl] -1,1,1,3, 3,3-hexafluoropropane, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-Amino-6-fluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 2,2'-dimethyl-4,4'-diaminobiphenyl , 3, 3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 2,2'-bis (tri (Fluoromethyl) -4,4'-diaminobiphenyl and the like. These aromatic diamine compounds may be used alone, or two or more kinds of aromatic diamine compounds may be used. In addition, from the viewpoints of transparency and heat resistance, preferred aromatic diamine compounds include, for example, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane , 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminobenzene Group) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3, 3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3 -(3-aminophenoxy) phenyl]- 1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexa Fluoropropane, 1,3-bis [4- (4-amino-6-trifluoromethylphenoxy) -α, α-dimethylbenzyl] benzene, 3,3'-bis (trifluoromethyl) (Group) -4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, and other aromatic diamine compounds containing a fluorine group, preferably At least one of the aromatic diamine compounds to be used is an aromatic diamine compound having a fluorine group, and more preferably 2,2'-bis (trifluoromethyl) -4,4'-diamine-based biphenyl. By using an aromatic diamine compound having a fluorine group, transparency, heat resistance, and solubility in a solvent are easily obtained.

1.2. Tetracarboxylic dianhydride

In addition, as the tetracarboxylic dianhydride used in the production of the polyfluorene imine powder of the present invention, similar to the above-mentioned aromatic diamine compound, if it is a common solvent (for example, N, N-dimethylacetamide (DMAC) )), Tetracarboxylic dianhydride that is soluble in polyimide and can impart specific transparency. Any one can be used. Specific examples are 4,4 '-(1,1,1,3,3, 3-hexafluoropropane-2,2-diyl) diphthalic dianhydride, pyromellitic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 1, 4-hydroquinone dibenzoate-3,3 ', 4,4'-tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4 , 4'-diphenyl ether tetracarboxylic dianhydride and the like. The tetracarboxylic dianhydride may be used alone, or two or more kinds of tetracarboxylic dianhydride may be used. In addition, from the viewpoints of transparency, heat resistance, and solubility in solvents, 4,4 '-(1,1,1,3,3,3-hexafluoropropane-2,2-diyl) di Tetracarboxylic dianhydride having at least one kind of phthalic dianhydride having a fluorine group.

2. Polymerization to polyamic acid

Polymerization into polyamic acid is carried out by reacting the above-mentioned aromatic diamine compound with tetracarboxylic dianhydride in a solvent capable of dissolving the generated polyamino acid. The solvent used for polymerization to polyamic acid may be N, N-dimethylacetamide, N, N-dimethylformamide, N-methyl-2-pyrrolidone, 1,3-dimethyl Solvents such as -2-imidazolinone, dimethyl sulfene and the like.

The reaction of polymerization to polyamic acid can be performed while stirring in a reaction vessel provided with a stirring device. For example, for example, a method of dissolving a specific amount of an aromatic diamine compound in the above-mentioned solvent, and adding tetracarboxylic dianhydride to the reaction while stirring to obtain polyamic acid; after the tetracarboxylic dianhydride is dissolved in the solvent, stirring A method for obtaining polyamic acid by adding an aromatic diamine compound for reaction; a method for obtaining polyamic acid by alternately adding an aromatic diamine compound and tetracarboxylic dianhydride and reacting.

Although the reaction temperature for the polymerization of polyamic acid is not particularly limited, it is preferably carried out at a temperature of 0 to 70 ° C, more preferably 10 to 60 ° C, and still more preferably 20 to 50 ° C. The polymerization reaction proceeds within the above range, and a high-molecular-weight polyamine having less coloration and excellent transparency can be obtained.

In addition, the aromatic diamine compound and the tetracarboxylic dianhydride used for the polymerization to polyamic acid are used in about equal mole amounts. However, in order to control the degree of polymerization of the obtained polyamino acid, the molar amount of tetracarboxylic dianhydride / The molar amount (molar ratio) of the aromatic diamine compound can be changed in the range of 0.95 to 1.05. In addition, the molar ratio of the tetracarboxylic dianhydride to the aromatic diamine compound is preferably in the range of 1.001 to 1.02, and more preferably 1.001 to 1.01. In this way, a slight excess of tetracarboxylic dianhydride can stabilize the degree of polymerization of the obtained polyamic acid, and at the same time, the unit derived from tetracarboxylic dianhydride can be arranged at the end of the polymer. Polyimide with few colors and excellent transparency.

In order to maintain the viscosity of the solution appropriately and facilitate the processing in the subsequent steps, the concentration of the generated polyamic acid solution is preferably adjusted to an appropriate concentration (for example, about 10 to 30% by weight).

3. Chemical amidation reaction

Then, a polyamidation agent is added to the obtained polyamidic acid solution to perform a chemical polyimidation reaction. As the imidating agent, carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, succinic anhydride, phthalic anhydride, and benzoic anhydride can be used. From the viewpoint of cost and easy removal after reaction, acetic anhydride is preferably used. The equivalent of fluorene imidating agent used should be above the fluorene bond equivalent of the polyfluorinated acid that undergoes the chemical fluorination reaction, preferably 1.1 to 5 times the amine bond equivalent, and more preferably 1.5 to 4 times . In this way, by using a sulfonium imidating agent having a slight excess of a sulfonium bond, the sulfonization reaction can be efficiently performed even at a low temperature.

In the chemical amidine imidization reaction, aliphatic, aromatic, or heterocyclic tertiary amines such as pyridine, methylpyridine, quinoline, isoquinoline, trimethylamine, and triethylamine can be used as the accelerator. class. By using these amines, the fluorene imidization reaction can be efficiently performed at a low temperature. As a result, the coloration during the fluorene imidization reaction can be suppressed, and a more transparent polyfluorene can be obtained.

Although there is no particular limitation on the chemical hydrazone imidization reaction temperature, it is preferably carried out at a temperature of 10 ° C or more and less than 50 ° C, and more preferably at a temperature of 15 ° C or more and less than 45 ° C. By carrying out the chemical fluorene imidization reaction at a temperature of 10 ° C. or higher and less than 50 ° C., the coloration during the fluorene imidization reaction can be suppressed, and a polyfluorene imine having excellent transparency can be obtained.

4. Formed by the formation of a powder of polyimide

Next, in a polyfluorene imide solution obtained by a chemical hydrazone imidization reaction, a weak solvent of a polyfluorene imine is added to precipitate the polyfluorene imine to form a powder. As the weak solvent used for powdering, any weak solvent that can precipitate polyfluorene imine can be used, and it is desirable to have miscibility with the solvent of the polyfluorene imine solution, and specifically, water, methanol, ethanol, and the like can be used. Moreover, it is preferable to use methanol as a weak solvent to obtain a polyimide powder having a stable average particle diameter.

In the present invention, the amount of the weak solvent used in the polyimide powdering step must be put into a sufficient amount to carry out the precipitation of the polyimide powder, although the polyimide structure and the polyimide are considered. The solvent of the solution and the concentration of the polyimide solution are determined, but usually 0.5 times or more the weight of the polyimide solution, preferably 0.8 or more times the weight of the polyimide solution, and more preferably a polyimide solution Weak solvent with a weight greater than 1 weight. By using a weak solvent having a weight of more than 0.5 times the weight of the polyimide solution, a polyimide powder having a stable average particle size can be obtained in high yield. In addition, generally 10 times or less the weight of the polyimide solution, preferably 7 times or less the weight of the polyimide solution, more preferably 5 times or less the weight of the polyimide solution, and even more preferably polyimide A weak solvent having a weight of 4 times or less the weight of the amine solution.

Although the polyimide powder is formed by adding the above weak solvent to the polyimide solution, it is preferably carried out by adding the weak solvent dropwise while stirring the polyimide solution. Since the weak solvent easily diffuses, it is desirable to adjust the polyfluorene imine solution to 5 to 30% by weight, and more preferably 10 to 20 Concentration of about% by weight. In addition, although the preferred average particle diameter of the polyimide powder obtained by the present invention is 0.02 to 0.8 mm, the average particle diameter can be added to the polyimide solution by a weak solvent (addition amount per minute). And control. The preferred addition speed of the weak solvent is slightly affected by the structure of polyimide and the concentration of polyimide in the solution, but at the point before the slowest cause of polyimide precipitation, if it will be precipitated at this time, When the total amount of polyimide solution is set to Xg, the addition amount of weak solvent per minute is preferably 0.0005 to 0.1 times (g / min) of X, more preferably 0.001 to 0.05 times of X, and most preferably 0.001 of X Times to less than 0.04 times (g / min), and the addition rate is maintained within this range until the precipitation of the polyimide powder is completed, and a polyimide powder having a stable average particle diameter can be obtained. For example, in the case where the polyfluorene imine is powdered in 1000 g of the polyfluorene imine solution (concentration: 15% by weight), the preferred weak solvent addition rate is 0.5 to 100 g / min.

When the addition amount (addition rate) of the weak solvent per minute is less than 0.0005 times of the total amount of polyimide solution, the time required for pulverization will be significantly longer and the productivity will be reduced, and the resulting polyimide powder will be reduced. The volume average particle diameter is too small to be handled. On the other hand, when the addition amount (addition rate) of the weak solvent per minute is greater than 0.1 times of the total amount of the polyimide solution, the average particle diameter of the polyimide powder produced is too large, and it will be difficult to efficiently borrow it. The volatile components are removed by drying, and as a result, there is a possibility that problems such as polyimide coloration and reduction in heat resistance may occur.

In addition, although it is necessary to consider the control of the addition rate of the weak solvent at the beginning of the powdery precipitation of polyimide, no special consideration is required before the powdery precipitation of polyimide begins. Therefore, the weak solvent is added at the beginning. Before the precipitation of powder, a weak solvent is added at a high speed. Before the polyimide solution is turbid and the precipitation of the polyimide is confirmed to be powdered, that is, at a point before the start of precipitation, the addition rate is controlled within the above range. Within. After that, it is necessary to maintain this addition rate until the precipitation of powder is completed.

In the present invention, although there is no particular limitation on the temperature at which the polyimide precipitates into powder, from the viewpoint of suppressing the evaporation of the weak solvent used and efficient precipitation, it is preferably performed at a temperature of 50 ° C or lower, more preferably The temperature is below 40 ° C.

In addition, if a polyimide solution is added to an excessively weak solvent to powder the polyimide, the precipitated polyimide may be fibrous, which is not preferable.

5. Drying of powder

In the present invention, the precipitated polyimide powder is provided to the following drying step without being pulverized. The precipitated polyfluorene imide powder is filtered, and a washing step is performed as required. The polyfluorine imine solvent, the fluorene imidating agent, and the fluorene imidization accelerator are substantially removed and then dried to obtain the present invention. Polyimide powder.

The above polyfluorene imine powder can be dried at any temperature if the residues of the polyfluorene imine solvent, the fluorene imidization agent, the fluorene imidization accelerator, and the weak solvent can be removed. However, if the above weak solvent is used, When a weak solvent containing a hydroxyl group such as methanol or ethanol is suddenly dried at a temperature of 100 ° C or higher, the carboxylic acid group or carboxylic anhydride group in the polyfluorene imide will react with the weak solvent to form an ester bond, which may cause Possibility of decreased heat resistance and coloring Sex. Therefore, the drying step is preferably based on the volatile components in the polyimide powder being less than 5%, and more preferably less than 3%. After drying at a temperature of less than 100 ° C, it is preferably 100 to 350. ℃, better drying at a temperature of 150 ~ 300 ℃ for 0.1 ~ 24 hours, to remove the remaining volatile components, especially the hardly volatile components such as fluorene imidating agent and fluorene imidizing accelerator. From the viewpoints of preventing molecular weight reduction and preventing coloring, drying at a high temperature of 100 ° C. or higher is preferably performed in an inert and low water content environment. The polyimide powder may be dried at normal pressure or under reduced pressure. Furthermore, it is not necessary to dry and continuously increase the temperature from a low temperature of less than 100 ° C to a high temperature of 100 ° C or higher. In this case, it is preferable that the volatile component contained in the polyimide powder does not reach 5% before the drying temperature exceeds 100 ° C.

The amount of volatile components in the polyimide powder after drying at a temperature of less than 100 ° C is defined by the following formula.

Weight of polyimide powder after drying at a temperature below 100 ° C: Ag

Weight of polyimide powder after final drying at a temperature above 100 ° C: Bg

Residual volatile content after drying at a temperature below 100 ° C: (A-B) / A × 100%

6. Powder characteristics (one particle characteristic)

The average particle diameter of the polyimide powder thus obtained is 0.02 to 0.8 mm, preferably 0.03 to 0.6 mm, and more preferably 0.04 to 0.4 mm. When the average particle diameter is within the above range, the remaining volatile components can be efficiently removed, and it becomes a polyimide having very little coloring and excellent transparency.

In addition, regarding the particle size distribution of the polyimide powder of the present invention, it is preferred that 95% by volume or more of the particle size distribution falls within the range of 0.01 to 2 mm, and more preferably 99% by volume or more. When the particle size distribution is as described above, it is easy to handle, and the remaining volatile components can be efficiently removed, and it can be a polyimide with little coloring and excellent transparency.

The average particle diameter and particle size distribution of the polyimide powder of the present invention can be measured by a laser diffraction / scattering type particle size distribution measuring device.

The weight average molecular weight of the polyfluorene imine powder of the present invention is preferably 20,000 to 1,000,000, more preferably 50,000 to 500,000. If the weight average molecular weight does not reach the above lower limit, transparency and mechanical properties may be impaired. If the weight average molecular weight exceeds the above upper limit, the viscosity of the polyimide powder may increase excessively when dissolved in a solvent, making it difficult to handle. The weight average molecular weight of polyimide can be determined by a size exclusion chromatography apparatus. In addition, although the specific viscosity is used as an indicator of the degree of polymerization of polymers such as polyimide, the specific viscosity in the polyimide powder of the present invention is preferably in the range of 0.8 to 4 dL / g. It is more preferably within the range of 1 to 3 dL / g. If the reduced viscosity does not reach the lower limit described above, the transparency and mechanical properties may be impaired. If it exceeds the upper limit described above, the viscosity of the polyimide solution may increase excessively and it may be difficult to handle.

7. Powder characteristics (No. 2 film characteristics)

Regarding the transparency of the polyimide powder of the present invention, it is possible to dissolve the polyimide powder in N, N-dimethylacetamide (DMAC) and use it to make it 50 μm thick after drying. Films made by casting Obtained by measuring the light transmittance and yellowness using a spectrocolorimeter. In addition, the polyimide film obtained from the polyimide powder of the present invention has a light transmittance at a wavelength of 450 nm of 80% or more, and more preferably 85% or more. Furthermore, the yellowness is preferably -5 to 5, more preferably -3 to 3. When the light transmittance at 450 nm does not reach the above-mentioned lower limit, and when the yellowness is outside the above range, it may be difficult to provide optical properties such as displays. In the case of a film with excellent transparency. In addition, the fluorene imidization rate of the polyfluorene imine powder of the present invention is preferably 90% or more, and more preferably 95% or more. The fluorene imidization ratio can be obtained from the polyfluorene imine film obtained by the above method through Fourier transform infrared spectrometry (FT-IR method).

In addition, the polyfluorene imide powder of the present invention uses differential heat. The weight reduction rate measured by a thermogravimetric analysis device at a temperature range of 200 to 300 ° C is preferably 0 to 0.2%, and more preferably 0 to 0.1%. If the weight reduction rate of the polyimide powder in the temperature range of 200 to 300 ° C is within the above range, a polyimide film having less coloring and excellent transparency can be provided.

[Example]

Hereinafter, the present invention is specifically described by examples, but the present invention is not limited to these examples.

(Measurement method of average particle diameter and particle size distribution of polyimide powder)

The measurement was performed using a laser diffraction / scattering type particle size distribution measuring device (LA-950V2 manufactured by HORIBA, Ltd.) using ethanol as a dispersion medium.

(Measurement method of light transmittance and yellowness of polyimide)

(1) Method for making thin film samples for measurement

The polyfluorene imide powder was dissolved in N, N-dimethylacetamide to 20% by weight. Next, using a coater, a film was formed on a smooth glass plate so as to have a thickness of 50 μm after drying. After being held in a hot air oven at 130 ° C. for 60 minutes, the temperature was raised from 130 ° C. to 5 ° C./minute to 300 ° C. It was held at 300 ° C for 60 minutes to be dried, and then taken out of the hot air oven and cooled to room temperature, and then peeled from the glass plate as a polyimide film sample for measurement.

(2) Measurement of light transmittance

Using a spectrophotometer (Nippon Denshoku Industries Co., Ltd. SD6000), the light transmittance was measured in a wavelength range of 380 to 780 nm, and the light transmittance at 450 nm was obtained.

(3) Measurement of yellowness (YI)

A spectrocolorimeter (Nihon Denshoku Kogyo Co., Ltd. SD6000) was used to scan the wavelength range of 380 to 780 nm, and the yellowness (YI) was determined based on JIS K7373: 2006 and measured using a standard light source D65.

(Measurement method of hydrazone imidization rate)

A 50 μm-thick film sample made by the same method as the polyimide light transmittance measurement was used as a measurement sample, and the film was further heat-treated at 380 ° C. for 30 minutes to complete the imidization film as a comparison sample. , Fourier transform infrared spectrophotometer (Shimadzu Corporation) FT-IR (manufactured by Co., Ltd.), an infrared light absorption spectrum was obtained by the ATR method, and based on the spectrum, the imidization ratio was calculated by the following method.

In the infrared light absorption spectrum of the above comparative sample, one of the characteristic absorptions of fluorene imine in the vicinity of 1,365 cm ^-1 (variable angle vibration of the fluorene imine ring CN group) and the characteristic absorption of benzene ring was 1,500 cm ^-1 the absorbance ratio as A, determined by an infrared absorption spectrum of a sample of the sheet of 1,365cm ^-1 and the ratio of absorbance at 1,500cm ^-1 is B, by the following equation (PEI) ratio.

Polyimide imidization ratio (%) = (B / A) × 100

(Measurement method of weight reduction rate of polyimide powder at 200 ~ 300 ° C)

Use differential heat. Thermogravimetric simultaneous measuring device (DTG-60 manufactured by Shimadzu Corporation). 25mg of polyimide powder was fed into an aluminum pan, and the temperature was increased at a rate of 10 ° C / min in a nitrogen environment. The weight of the polyimide powder (M1) at 200 ° C and the polymerization at 300 ° C were measured. The weight (M2) of the sulfonium imine powder was determined by the following formula from 200 ° C to 300 ° C.

200 ~ 300 ℃ weight reduction rate (%) = (M1-M2) / M1 × 100

(Determination of specific viscosity of polyimide)

The polyimide powder was dissolved in N, N-dimethylacetamide (DMAC) at a concentration of 0.5 dL / g to prepare a polyimide solution. The outflow time (T) of the polyfluorene imine solution and the outflow time (T0) of only the solvent DMAC were measured using a Ubbelohde viscometer at a temperature of 30 ° C, and the specific viscosity was obtained from the following formula.

Specific viscosity (dL / g) = (T-T0) /T0/0.5

(Determination of average molecular weight and polydispersity of polyimide)

A size exclusion chromatography device (HLC-8320GPC manufactured by Tosoh Corporation) was used, and the measurement was performed by using eluent tetrahydrofuran and a differential refractometer detector using standard polystyrene as a standard substance.

(Example 1)

In a 2L separable glass flask equipped with a stirring device and a stirring wing, 460 g of a solvent N, N-dimethylacetamide (DMAC) and 2,2'-bis of an aromatic diamine compound having a fluorine group were added. (Trifluoromethyl) -4,4'-diaminobiphenyl (TFMB) 64.048 g (0.200 mole) was stirred and TFMB was dissolved in DMAC. Next, in a separable flask, the tetracarboxylic dianhydride 4,4 '-(1,1,1,3,3,3-hexafluoropropane- 2,2-diyl) diphthalic dianhydride (6FDA) 89.294 g (0.201 mole), while directly adjusting the temperature to a temperature range of 20 to 40 ° C., continuously stirring for 6 hours to carry out the polymerization reaction to obtain a thick viscosity Polyamine solution. The molar ratio of the tetracarboxylic dianhydride / aromatic diamine compound used was 1.005, and the concentration of the polyamidic acid solution was 25% by weight.

Next, 409 g of DMAC was added to the obtained polyamic acid solution to dilute the polyamic acid concentration to 15% by weight, and then 25.83 g of isoquinoline was added as a fluorinated imidization agent, and the polyamic acid solution was maintained while stirring. In a temperature range of 30 to 40 ° C, 122.5 g (1.20 mol) of acetic anhydride as a sulfonium imidating agent was slowly added dropwise therein, and then the liquid temperature was maintained at 30 to 40 ° C. Continuous stirring for 12 hours for chemical amidation reaction A polyimide solution was obtained.

Then, 1000 g of the polyfluorene imide solution containing the fluorene imidating agent and the fluorene imidization accelerator was transferred to a 5 L separable flask equipped with a stirring device and a stirring wing, and kept at 15 rpm while stirring at 120 rpm. At a temperature of ~ 25 ° C, 1500 g of methanol was added dropwise thereto at a rate of 10 g / min. After about 800 g of methanol was added, it was confirmed that the polyfluorene imide solution was turbid, and the powdery polyfluorene imine was confirmed to precipitate. Continue to add a total of 1500g of methanol to complete the precipitation of polyimide.

Then, the contents of the separable flask were filtered with a suction filtration device, and then washed with 1,000 g of methanol and filtered.

After that, 50 g of the polyimide powder containing volatile component residues after filtration was dried at 50 ° C. for 24 hours with a dryer equipped with a local exhaust device, and the weight was measured, followed by drying at 260 ° C. for 2 hours. To obtain a polyimide powder for the purpose of removing residual volatile components. The weight after drying at 50 ° C for 24 hours was 43.8 g, and the weight after drying at 260 ° C for 2 hours was 43.3 g. It was confirmed that the amount of volatile components after 1.1 hours at 50 ° C was 1.1%.

The average particle diameter of the obtained polyimide powder was 0.10 mm, and the particle diameter distribution in the range of 0.01 to 2 mm contained 100% by volume. In addition, the reduced viscosity was 2.1 dL / g, the weight average molecular weight (Mw) measured by size exclusion chromatography was 210,000, and the polydispersity expressed in weight average molecular weight (Mw) / number average molecular weight (Mn) was 2.1. . In addition, when the weight reduction rate in the range of 200 to 300 ° C was investigated with a differential thermal and thermogravimetric analysis device, it was 0.03%, and the fluorene imidization rate was 95% or more.

20 g of the obtained polyimide powder was dissolved in 80 g of DMAC to become After homogeneous polyimide solution, a film was coated on a glass plate using a coater, and DMAC was dried under specific conditions, and then peeled off from the glass plate to form a 50 μm thick polyimide film. The obtained polyimide film had a high light transmittance at 450 nm of 90%, a yellowness of 1.5, and no discoloration was observed even by visual inspection, and it was extremely excellent in transparency.

(Example 2)

A glass 2L separable flask equipped with a stirring device and a stirring wing was charged with 484 g of a solvent N, N-dimethylacetamide (DMAC) and 2,2'-bis (trifluoromethyl) of an aromatic diamine compound. ) -4,4'-diaminobiphenyl (TFMB) 51.238g (0.160 mole) and 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1, 20.738 g (0.040 mol) of 3,3,3-hexafluoropropane (BAPP-F) was stirred and TFMB and BAPP-F were dissolved in DMAC. Next, in a separable flask, while stirring, under nitrogen gas flow, it took about 10 minutes to add 4,4 '-(1,1,1,3,3,3-hexafluoropropane-2 of tetracarboxylic dianhydride. , 2-diyl) diphthalic dianhydride (6FDA) 89.294g (0.201 mole), while directly adjusting the temperature to the range of 20 ~ 40 ° C, continuously stirring for 6 hours to carry out the polymerization reaction to obtain a thick polymer Phenylamine solution. The molar ratio of the tetracarboxylic dianhydride (6FDA) / aromatic diamine compound (total of TFMB and BAPP-F) used was 1.005, and the polyamic acid solution concentration was 25% by weight.

Next, 430 g of DMAC was added to the obtained polyamic acid solution to dilute the polyamic acid concentration to 15% by weight, and then 25.83 g of isoquinoline was added as a fluorene imidation accelerator, and the polyamino acid solution was maintained while stirring. A temperature range of 30 ~ 40 ℃, which takes about 10 minutes to slowly drop into the 122.5 g (1.20 moles) of acetic anhydride of the amidine imidating agent, and then the liquid temperature was maintained at 30 to 40 ° C. and the stirring was continued for 12 hours to perform a chemical amidine imidization reaction to obtain a polyammine solution.

Then, 1000 g of the polyfluorene imide solution containing the fluorene imidating agent and the fluorene imidization accelerator was transferred to a 5 L separable flask equipped with a stirring device and a stirring wing, and kept at 15 rpm while stirring at 120 rpm. At a temperature of ~ 25 ° C, 1500 g of methanol was added dropwise thereto at a rate of 10 g / min. After about 900 g of methanol was added, the turbidity of the polyfluorene imine solution was confirmed, and the precipitation of the powdery polyfluorene imine was confirmed. Continue to add a total of 1500g of methanol to complete the precipitation of polyimide.

Next, the contents of the separable flask were filtered using a suction filtration device, and then washed with 1,000 g of methanol and filtered.

After that, 50 g of the filtered polyimide powder containing volatile component residues was dried at 50 ° C for 24 hours using a dryer equipped with a local exhaust device, and the weight was measured, and further dried at 260 ° C for 2 hours. A polyimide powder was obtained for the purpose of removing residual volatile components. The weight after drying at 50 ° C for 24 hours was 44.1 g, and the weight after drying at 260 ° C for 2 hours was 43.7 g. It was confirmed that the amount of volatile components after 0.9 hours at 50 ° C was 0.9%.

The average particle size of the obtained polyimide powder was 0.36 mm, and the particle size distribution in the range of 0.01 to 2 mm contained 100% by volume. Moreover, the reduced viscosity was 2.4 dL / g, the weight average molecular weight measured by size exclusion chromatography was 250,000, and the polydispersity was 2.4. In addition, the weight reduction rate in the range of 200 to 300 ° C was measured with a differential thermal and thermogravimetric analysis device, and it was 0.05%, and the fluorene imidization rate was 95% or more.

20 g of the obtained polyimide powder was dissolved in 80 g of DMAC to form a homogeneous polyimide solution, and then a film was coated on a glass plate using a coater. After the DMAC was dried under specific conditions and peeled from the glass plate, 50 μm was formed. Thick polyimide film. The obtained polyimide film had a high light transmittance at 450 nm of 88%, a yellowness of 2.6, and no discoloration was observed even visually, and it was an excellent transparency.

(Example 3)

A glass 2L separable flask equipped with a stirring device and a stirring wing was charged with 444 g of a solvent N, N-dimethylacetamide (DMAC) and 2,2'-bis (trifluoromethyl) of an aromatic diamine compound. ) -4.4'-diaminobiphenyl (TFMB) 64.048 g (0.200 mole) and stirred, TFMB was dissolved in DMAC. Next, in a separable flask, while stirring, under nitrogen gas flow, it took about 10 minutes to add 4,4 '-(1,1,1,3,3,3-hexafluoropropane-2 of tetracarboxylic dianhydride. , 2-diyl) diphthalic dianhydride (6FDA) 71.524g (0.161 mole), and then it takes about 5 minutes to add 3,3 ', 4,4'-diphenyl ether tetracarboxylic dianhydride ( ODPA) 12.408 g (0.040 mol), while continuously adjusting the temperature to a range of 20 to 40 ° C. for 6 hours to carry out the polymerization reaction to obtain a thick polyamic acid solution. The molar ratio of the tetracarboxylic dianhydride (total of 6FDA and ODPA) / aromatic diamine compound (TFMB) used was 1.005, and the polyamic acid solution concentration was 25% by weight.

Next, 395 g of DMAC was added to the obtained polyamic acid solution to dilute the polyamic acid concentration to 15% by weight, and then 25.83 g of isoquinoline was added as a fluorenimation accelerator, and the polyamine solution was maintained while stirring. 30 ~ 40 ℃ Within the temperature range, it took about 10 minutes to slowly add 122.5 g (1.20 mol) of acetic anhydride as a sulfonium imidating agent, and then further maintain the liquid temperature at 30 ~ 40 ° C and continue stirring for 12 hours. A chemical amidine imidization reaction is performed to obtain a polyammine solution.

Then, 1000 g of the polyimide solution containing the fluorene imidating agent and the fluorene imidization accelerator was transferred to a 5L separable flask equipped with a stirring device and a stirring wing, and kept at 15 ~ while stirring at 120 rpm. At a temperature of 25 ° C, 1500 g of methanol was added dropwise thereto at a rate of 10 g / min. After about 850 g of methanol was added dropwise, the turbidity of the polyfluorene imine solution was confirmed, and the precipitation of the powdery polyfluorene imine was confirmed. Continue to add a total of 1500g of methanol to complete the precipitation of polyimide.

Then, the contents of the separable flask were filtered with a suction filtration device, and then washed with 1,000 g of methanol and filtered.

After that, 50 g of the filtered polyimide powder containing volatile component residues was dried at 50 ° C for 24 hours using a dryer equipped with a local exhaust device, and the weight was measured, and further dried at 260 ° C for 2 hours. A polyimide powder was obtained for the purpose of removing residual volatile components. The weight after drying at 50 ° C for 24 hours was 43.9g, and the weight after drying at 260 ° C for 2 hours was 43.4g. It was confirmed that the amount of volatile components after 1.1 hours at 50 ° C was 1.1%.

The average particle diameter of the obtained polyimide powder was 0.25 mm, and the particle diameter distribution in the range of 0.01 to 2 mm contained 100% by volume. In addition, the reduced viscosity was 2.3 dL / g, the weight average molecular weight measured by size exclusion chromatography was 250,000, and the polydispersity was 2.5. In addition, the differential thermal and thermogravimetric analysis equipment After investigating the weight reduction rate in the range of 200 ~ 300 ℃, it is 0.06%, and the imidization rate is more than 95%.

20 g of the obtained polyimide powder was dissolved in 80 g of DMAC to form a homogeneous polyimide solution, and then a film was coated on a glass plate using a coater. After the DMAC was dried under specific conditions, it was peeled from the glass plate to make 50 μm. Thick polyimide film. The obtained polyimide film had a high light transmittance of 87% and a yellowness of 2.3. No discoloration was observed even visually, and it was extremely excellent in transparency.

(Example 4)

A glass 2L separable flask equipped with a stirring device and a stirring wing was charged with 460 g of a solvent N, N-dimethylacetamide (DMAC) and 2,2'-bis (trifluoromethyl) of an aromatic diamine compound. ) -4.4'-diaminobiphenyl (TFMB) 64.048 g (0.200 mole) and stirred, TFMB was dissolved in DMAC. Next, in a separable flask, while stirring, under nitrogen gas flow, it took about 10 minutes to add 4,4 '-(1,1,1,3,3,3-hexafluoropropane-2 of tetracarboxylic dianhydride. , 2-diyl) diphthalic dianhydride (6FDA) 89.294g (0.201 mole), while directly adjusting the temperature to the range of 20 ~ 40 ° C, continue to stir for 6 hours to carry out the polymerization reaction, and obtain a viscous Polyamic acid solution. The molar ratio of the tetracarboxylic dianhydride / aromatic diamine compound used was 1.005, and the polyamic acid solution concentration was 25% by weight.

Next, 409 g of DMAC was added to the obtained polyamic acid solution to dilute the polyamic acid concentration to 15% by weight, and then 25.83 g of isoquinoline was added as a fluorene imidization accelerator, and the polyamino acid solution was maintained while stirring. 30 ~ 40 ℃ Within the temperature range, it took about 10 minutes to slowly add 122.5 g (1.20 mol) of acetic anhydride as a sulfonium imidating agent, and then further maintain the liquid temperature at 30 ~ 40 ° C and continue stirring for 12 hours. A chemical amidine imidization reaction is performed to obtain a polyammine solution.

Then, 1000 g of the polyfluorene imide solution containing the fluorene imidating agent and the fluorene imidization accelerator was transferred to a 5 L separable flask equipped with a stirring device and a stirring wing, and kept at 15 rpm while stirring at 120 rpm. At a temperature of ~ 25 ° C, 700 g of 1500 g of methanol prepared was added at a rate of 200 g / min, and then the remaining methanol was added dropwise at a rate of 10 g / min. At the time when the first 700 g of methanol was added, the polyimide solution was not observed to be turbid and remained transparent, but the polyimide solution became turbid by the subsequent dropwise addition of methanol, and it was confirmed that the polymer was in powder form. Precipitation of hydrazone. Then continue to add a total of 1500g of methanol to complete the precipitation of polyfluorene.

Then, the contents of the separable flask were filtered with a suction filtration device, and then washed with 1,000 g of methanol and filtered.

After that, 50 g of the filtered polyimide powder containing volatile component residues was dried at 50 ° C. for 24 hours using a dryer equipped with a local exhaust device, and then the weight was measured, and further dried at 260 ° C. for 2 hours. A polyimide powder was obtained for the purpose of removing residual volatile components. The weight after drying at 50 ° C for 24 hours was 43.9g, and the weight after drying at 260 ° C for 2 hours was 43.4g. It was confirmed that the amount of volatile components after 1.1 hours at 50 ° C was 1.1%.

The average particle diameter of the obtained polyimide powder was 0.13 mm, and the particle diameter distribution in the range of 0.01 to 2 mm contained 100% by volume. And, the reduced viscosity is 1.9dL / g, and the weight-average molecular weight measured by size exclusion chromatography is 190,000 with a polydispersity of 2.1. In addition, the differential weight and thermogravimetric analysis device was used to investigate the weight reduction rate in the range of 200 to 300 ° C, and it was 0.03%, and the ammonium imidization rate was 95% or more.

20 g of the obtained polyfluorene imide powder was dissolved in 80 g of DMAC to form a homogeneous polyimide solution, and then a film was coated on a glass plate with a coater. After the DMAC was dried under specific conditions, it was peeled from the glass plate to make 50 μm Thick polyimide film. The obtained polyimide film had a high light transmittance at 450 nm of 89%, a yellowness of 2.4, and no discoloration was observed even by visual inspection, and it was extremely excellent in transparency.

(Comparative example 1)

A glass 2L separable flask equipped with a stirring device and a stirring wing was charged with 460 g of a solvent N, N-dimethylacetamide (DMAC) and 2,2'-bis (trifluoromethyl) of an aromatic diamine compound. ) -4.4'-diaminobiphenyl (TFMB) 64.048 g (0.200 mole) and stirred, TFMB was dissolved in DMAC. Next, in a separable flask, while stirring, under nitrogen gas flow, it took about 10 minutes to add 4,4 '-(1,1,1,3,3,3-hexafluoropropane-2 of tetracarboxylic dianhydride. , 2-diyl) diphthalic dianhydride (6FDA) 89.294 g (0.201 mole), while directly adjusting the temperature to the range of 20 ~ 40 ° C, continue to stir for 6 hours to carry out the polymerization reaction to obtain a thick polymer. Phenylamine solution. The molar ratio of the tetracarboxylic dianhydride / aromatic diamine compound used was 1.005, and the polyamic acid solution concentration was 25% by weight.

Next, 409 g of DMAC was added to the obtained polyamic acid solution to dilute the polyamic acid concentration to 15% by weight, and then 25.83 g of isoquinoline was added as The hydrazone imidization accelerator is maintained at a temperature range of 30 to 40 ° C while agitating the hydrazone solution, and 122.5 g of acetic anhydride, which is a hydrazone imidating agent, is slowly dropped in about 10 minutes ( 1.20 moles), and then the liquid temperature was further maintained at 30 to 40 ° C. and the stirring was continued for 12 hours to perform a chemical ammonium imidization reaction to obtain a polyfluorene imine solution.

Then, 1000 g of the polyfluorene imide solution containing the fluorene imidating agent and the fluorene imidization accelerator was transferred to a 5 L separable flask equipped with a stirring device and a stirring wing, and kept at 15 rpm while stirring at 120 rpm. At a temperature of ~ 25 ° C, 1500 g of methanol was added dropwise at a rate of 200 g / min. About 900 g of methanol was added, and it was confirmed that polyimide having a relatively large particle size was precipitated. Then continue to add a total of 1500g of methanol to complete the precipitation of polyfluorene.

Then, the contents of the separable flask were filtered using a suction filtration device, and then washed with 1,000 g of methanol and filtered.

After that, 50 g of the filtered polyimide powder containing volatile component residues was dried at 50 ° C for 24 hours using a dryer equipped with a local exhaust device, and the weight was measured, and further dried at 260 ° C for 2 hours. A polyimide powder was obtained for the purpose of removing residual volatile components. The weight after drying at 50 ° C for 24 hours was 43.4 g, and the weight after drying at 260 ° C for 2 hours was 40.8 g. It was confirmed that the amount of volatile components after drying at 50 ° C for 24 hours was 6.0%.

Those having a larger average particle diameter of 2.5 mm, and those having a particle diameter distribution in the range of 0.01 to 2 mm contained less than 30% by volume. In addition, the reduced viscosity is 2.1dL / g, and the weight is determined by size exclusion chromatography. The average molecular weight was 210,000 and the polydispersity was 2.1. In addition, a differential thermal and thermogravimetric analysis device was used to investigate a weight reduction rate in the range of 200 to 300 ° C, and it was confirmed that the weight reduction was 0.42%.醯 The imidization rate is above 95%.

After dissolving 20 g of the obtained polyimide powder in 80 g of DMAC to form a uniform polyimide solution, a film was coated on a glass plate using a coater, and the DMAC was dried and peeled off the glass plate under specific conditions to make 50 μm. After the thick polyimide film, the obtained polyimide film had a low light transmittance of 450% at 450 nm and a yellowness of 10.5. The film became yellow even when visually observed.

(Comparative example 2)

A glass 2L separable flask equipped with a stirring device and a stirring wing was charged with 460 g of a solvent N, N-dimethylacetamide (DMAC) and 2,2'-bis (trifluoromethyl) of an aromatic diamine compound. ) -4.4'-diaminobiphenyl (TFMB) 64.048 g (0.200 mole) and stirred, TFMB was dissolved in DMAC. Next, in a separable flask, while stirring, under nitrogen gas flow, it took about 10 minutes to add 4,4 '-(1,1,1,3,3,3-hexafluoropropane-2 of tetracarboxylic dianhydride. , 2-diyl) diphthalic dianhydride (6FDA) 89.294g (0.201 mole), while directly adjusting the temperature to the range of 20 ~ 40 ° C, continue to stir for 6 hours to carry out the polymerization reaction, and obtain a viscous Polyamic acid solution. The molar ratio of the tetracarboxylic dianhydride / aromatic diamine compound used was 1.005, and the polyamic acid solution concentration was 25% by weight.

Next, 409 g of DMAC was added to the obtained polyamic acid solution to dilute the polyamic acid concentration to 15% by weight, and then 25.83 g of isoquinoline was added as The hydrazone imidization accelerator is maintained at a temperature range of 30 to 40 ° C while agitating the hydrazone solution, and 122.5 g of acetic anhydride, which is a hydrazone imidating agent, is slowly dropped in about 10 minutes ( 1.20 moles), and then the liquid temperature was maintained at 30 to 40 ° C. and the stirring was continued for 12 hours to carry out a chemical hydrazone imidization reaction to obtain a polyfluorene imine solution.

Then, 1000 g of the polyfluorene imide solution containing the fluorene imidating agent and the fluorene imidization accelerator was transferred to a 5 L separable flask equipped with a stirring device and a stirring wing, and kept at 15 rpm while stirring at 120 rpm. At a temperature of ~ 25 ° C, 1500 g of methanol was then added dropwise thereto at a rate of 10 g / min. After about 800 g of methanol was charged, it was confirmed that the polyfluorene imide solution was cloudy, and it was confirmed that powdery polyfluorene imine was precipitated. Then continue to add a total of 1500g of methanol to complete the precipitation of polyfluorene.

Next, the contents of the separation flask were filtered using a suction filtration device, and then washed with 1,000 g of methanol and filtered.

After that, 50 g of the filtered polyimide powder containing volatile component residues was dried using a dryer equipped with a local exhaust device, especially at a temperature not higher than 100 ° C, and dried only at 260 ° C for 2 hours. After removing the volatile components, 43.6 g of polyfluorene imine powder was obtained.

The average particle diameter of the obtained polyimide powder was 0.10 mm, and the particle diameter distribution in the range of 0.01 to 2 mm contained 100% by volume. In addition, the reduced viscosity was 2.1 dL / g, the weight-average molecular weight measured by size exclusion chromatography was 210,000, and the polydispersity was 2.1. In addition, a differential thermal and thermogravimetric analysis device was used to investigate the weight reduction rate in the range of 200 to 300 ° C, and it was confirmed that the weight reduction was 0.31%.醯 The imidization rate is above 95%.

20 g of the obtained polyimide powder was dissolved in 80 g of DMAC to form a homogeneous polyimide solution, and then a film was coated on a glass plate using a coater. After the DMAC was dried under specific conditions, it was peeled from the glass plate to make 50 μm. Thick polyimide film. The obtained polyimide film had a low light transmittance at 450 nm of 79% and a yellowness of 7.5, and even when visually observed, it turned yellow.

The conditions and results of the examples and comparative examples are summarized in Tables 1 and 2.

As can be seen from the above, the average particle diameter (mm) in Examples 1 to 4, the particle size distribution (volume%) in the range of 0.01 to 2 mm, the weight reduction rate (%) at 200 to 300 ° C, the light transmittance (%), yellow Degree (YI) is good, but does not satisfy the comparative example 1 of the powder forming conditions and the powder drying conditions of the polyimide precipitated in the present invention, all of which have poor characteristics; and the comparative example 2 that does not satisfy the powder drying conditions , Its weight reduction rate (%), light transmittance (%), and yellowness (YI) are 200-300 ° C.

In addition, since the polyimide powder of the present invention has different properties due to these powder formation conditions and powder drying conditions, the polyimide powder cannot be directly specified by its structure or specificity. , Or generally unrealistic.

[Industrial availability]

By using the polyimide powder of the present invention, a polyimide film having excellent heat resistance and transparency can be manufactured, which is particularly suitable for display applications and electronic material applications, and has extremely high industrial value.

Claims (17)

A polyimide powder is characterized in that at least one aromatic diamine compound and at least one tetracarboxylic dianhydride are polymerized into polyimide acid, chemically imidized, and polyimide is formed. The imine precipitates to form a powder, and the polyimide powder soluble in N, N-dimethylacetamide produced in the step of drying, the average particle diameter of the polyimide powder is In the range of 0.02 to 0.8 mm, the polyimide powder of 50 μm thick polyimide film obtained by forming a film of N, N-dimethylacetamide solution from the polyimide powder has a light transmittance at a wavelength of 450 nm. More than 80%. Such as the polyimide powder of item 1, which uses differential heat. The thermogravimetric device measures a weight reduction rate in a range of 200 to 300 ° C in a range of 0 to 0.2%. For example, the polyfluorene imide powder of claim 1 or 2 uses at least one aromatic diamine compound having a fluorine group as the aromatic diamine compound, and uses at least one tetracarboxylic dianhydride having a fluorine group. Produced as a tetracarboxylic dianhydride. A method for producing polyimide powder having an average particle diameter of 0.02 to 0.8 mm, comprising the following steps: (a) preparing at least one aromatic diamine compound and at least one tetracarboxylic dianhydride, (b) performing the reaction of polymerizing the above aromatic diamine compound and tetracarboxylic dianhydride to polyamic acid while stirring in a solvent to obtain a polyamino acid solution; (c) using the obtained polyamino acid Add amidine imidating agent to the solution The step of obtaining a polyfluorene imine solution by amidation reaction, (d) stirring the obtained polyfluorene imine solution and adding a weak solvent of the polyfluorene imide to precipitate the polyfluorene imine to obtain a polymer containing volatile components In the step of amidine powder, (e) drying the obtained polyammine powder containing volatile components at a temperature of less than 100 ° C until the amount of volatile components becomes less than 5%, and then at a temperature of 100 to 350 ° C. The step of drying for 0.1 to 24 hours, removing volatile components contained in the powder, and obtaining a polyimide powder. A method for producing polyimide powder, comprising the following steps: (A) adding a weak solvent of polyimide to a polyimide solution containing polyimide dissolved in a solvent, so that The step of depositing polyimide to obtain polyimide powder containing volatile components. The weight ratio of the polyimide solution to the weak solvent is 1: 0.5 ~ 1: 10, and the polyimide is precipitated from the polyimide. The addition amount of the aforementioned weak solvent per minute from the previous point of time until the completion of the precipitation of powder is a step of 0.0005 to 0.1 times (g / min) of the aforementioned polyfluorene imine solution, (B) the aforementioned polyfluorene containing volatile components The imine powder is dried at a temperature of less than 100 ° C without being pulverized, and dried to a temperature of 100 to 350 ° C after the volatile content of the volatile component-containing polyimide powder is less than 5%. 0.1 to 24 hours, the step of obtaining polyimide powder. The method according to claim 5, wherein the polyimide solution is obtained by the following steps: (A1) preparing at least one aromatic diamine compound and at least one tetracarboxylic acid The step of acid dianhydride, (A2) the step of polymerizing the above aromatic diamine compound and tetracarboxylic dianhydride in a solvent to obtain a polyamic acid solution, (A3) adding to the obtained polyamino acid solution A step of obtaining a polyimide solution containing a polyimide in a solvent by performing a chemical imidation reaction with the imidating agent. The method of claim 6, wherein step (A3) is performed at a temperature of 10 ° C or more and less than 50 ° C. The method according to claim 6 or 7, wherein at least one aromatic diamine compound having a fluorine group is used as the aforementioned aromatic diamine compound, and at least one tetracarboxylic dianhydride having a fluorine group is used as the aforementioned tetracarboxylic acid Dianhydride. A polyimide powder produced by a method according to any one of claims 5 to 8. For example, the polyimide powder of claim 9 is solvent-soluble. The polyfluorene imide powder according to claim 10, wherein the solvent is N, N-dimethylacetamide. For example, the polyimide powder of claim 9 has an average particle diameter in a range of 0.02 to 0.8 mm. For example, the polyimide powder of claim 9, wherein the particles having a particle diameter in the range of 0.01 to 2 mm contain 95% by volume or more. For example, the polyimide powder of claim 9 has a weight reduction rate in the range of 200 to 300 ° C in the range of 0 to 0.2%. For example, the polyimide powder of claim 11 is dissolved in N, N-dimethylacetamide, and a polyimide film having a thickness of 50 μm is prepared from the solution, and When the light transmittance of the film at a wavelength of 450 nm was measured, it showed a light transmittance of more than 80%. For example, the polyimide powder of claim 11 is dissolved in N, N-dimethylacetamide, a polyimide film having a thickness of 50 μm is prepared from the solution, and the yellowness (YI) of the film is measured. When displaying, the yellow degree (YI) of -5 ~ 5 is displayed. A polyimide film obtained by using a polyimide powder system film according to any one of claims 1 to 3 and 9 to 16.