WO2017130703A1

WO2017130703A1 - Production method for polyimide molded body

Info

Publication number: WO2017130703A1
Application number: PCT/JP2017/000706
Authority: WO
Inventors: 大樹魚山; 真情野
Original assignee: セントラル硝子株式会社
Priority date: 2016-01-26
Filing date: 2017-01-12
Publication date: 2017-08-03
Also published as: TW201728625A; JP2017132845A

Abstract

A production method for a polyimide molded body that has a repeating unit represented by general formula (1). The production method is characterized in that a polyimide solution that includes at least a solvent and a polyimide that has a repeating unit represented by general formula (1) is spray dried at a temperature that is at or above 50℃ below the boiling point of the solvent. The method makes it possible to efficiently produce a polyimide molded body. (In general formula (1), R¹ is a single bond, an ether linkage, a sulfide linkage, a sulfoxy linkage, a methylene group, or an ethylene group, R² and R³ are each independently a hydrogen atom, a methyl group, or a trifluoromethyl group, and R⁴ is a tetravalent organic group that includes an aromatic ring, said group being represented by one of the indicated structures.)

Description

Method for producing polyimide molded body

The present invention relates to a method for producing a polyimide molded body.

Polyimide is generally used in the electronics industry and aerospace industry because of its excellent heat resistance, mechanical strength, electrical properties, and solvent resistance. However, many polyimides are insoluble in organic solvents, and their precursor polyamic acid is relatively soluble in organic solvents. Therefore, in general, a method is adopted in which the polyamic acid is applied in the form of a varnish in which an organic solvent is dissolved, and then a polyimide molded body is formed by dehydration and ring closure by high-temperature heating. It is not advantageous in terms of work process. Moreover, since the polymerization solution of polyamic acid has poor storage stability, it must be stored frozen. For these reasons, polyimide has a limited range of use despite having various excellent properties.

Recently, research has been reported on solubilizing polyimide in an organic solvent in order to overcome the problem of solubility of polyimide in an organic solvent and expand the range of use. For example, in Patent Document 1 and Patent Document 2, an aromatic diamine containing a hexafluoroisopropanol group (hereinafter sometimes referred to as “HFIP group”) which is a soluble substituent in a raw material and a tetracarboxylic dianhydride. It is described that a soluble polyimide can be obtained by polymerizing a polyamic acid using an acid and then imidizing by a chemical method using acetic anhydride and pyridine. However, when preparing a varnish by this method, the kind and density | concentration of the solvent of a polyimide varnish may depend on the conditions at the time of superposing | polymerizing a polyamic acid, and the expansion of the further use range is desired.

In order to solve these problems, efforts have been made to take out and use polyimides containing HFIP groups from varnishes of polyimides containing HFIP groups. In Patent Document 1, a polyimide varnish containing HFIP groups is added to a poor solvent such as water or alcohol, and a polyimide containing HFIP groups is precipitated and isolated, and then re-dissolved in a solvent to obtain a polyimide solution. Is prepared and can be processed and molded. Patent Document 2 describes that polyimide containing an HFIP group can be used as a powder.

Even in these methods, polyimide containing HFIP groups can be provided for various uses. However, after reprecipitation, it is necessary to pulverize the polyimide, or it includes steps such as filtration, removal, and drying. There is a need for a more efficient method of producing polyimides containing HFIP groups.

JP 2013-10096 A JP 2014-129340 A

An object of the present invention is to provide an efficient method for producing a polyimide molded body.

The inventors of the present invention have made extensive studies to solve the above problems. As a result, it was found that a polyimide molded body can be easily obtained by spray-drying a polyimide varnish solution containing an HFIP group under a predetermined condition, thereby completing the present invention.

That is, the present invention includes the following inventions.

[Invention 1]
A method for producing a polyimide molded body having a repeating unit represented by the following general formula (1),
A method of producing, characterized in that a polyimide solution containing at least a polyimide having a repeating unit represented by the following general formula (1) and a solvent is spray-dried at a temperature not lower than −50 ° C. of the boiling point of the solvent.

Wherein R ¹ is a single bond, an ether bond, a sulfide bond, a sulfoxy bond, a methylene group or an ethylene group, and R ² and R ³ are each independently a hydrogen atom, a methyl group or a trifluoromethyl group, R ⁴ is a tetravalent organic group containing an aromatic ring, and is represented by any of the following structures:

[Invention 2]
The production method according to claim 1, wherein the solvent is an amide solvent, an ether solvent, an aromatic solvent, a halogen solvent or a lactone solvent.

[Invention 3]
Solvents are N, N-dimethylformamide, N, N-dimethylacetamide, N-methylformamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, cyclopentyl Methyl ether, diphenyl ether, dimethoxyethane, diethoxyethane, tetrahydrofuran, dioxane, trioxane, benzene, anisole, nitrobenzene, benzonitrile, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, γ- Invention 1 characterized by being butyrolactone, γ-valerolactone, ε-valerolactone, γ-caprolactone, ε-caprolactone or α-methyl-γ-butyrolactone The method according.

[Invention 4]
Solvents are N, N-dimethylformamide, N, N-dimethylacetamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone, dibutyl ether, diphenyl ether, anisole, nitrobenzene, benzonitrile, 1,1,2,2 The production method according to invention 1, which is tetrachloroethane, γ-butyrolactone, γ-valerolactone, ε-valerolactone, γ-caprolactone, ε-caprolactone or α-methyl-γ-butyrolactone.

[Invention 5]
Invention 1 characterized in that the solvent is N-methylformamide, tetrahydrofuran, dipropyl ether, diisopropyl ether, cyclopentyl methyl ether, dimethoxyethane, dioxane, trioxane, benzene, chloroform, dichloromethane or 1,2-dichloroethane The manufacturing method as described in.

[Invention 6]
The production method according to any one of inventions 1 to 5, wherein the polyimide solution contains 1 to 30% by mass of polyimide with respect to the solvent.

[Invention 7]
The production method according to any one of inventions 1 to 6, wherein the spray drying is performed using a spray dryer.

[Invention 8]
The manufacturing method according to claim 7, wherein the spray dryer includes a two-fluid nozzle or a four-fluid nozzle.

[Invention 9]
9. The production method according to any one of inventions 1 to 8, wherein the spray drying is performed at a temperature of −50 ° C. or higher and + 100 ° C. or lower of the boiling point of the solvent.

[Invention 10]
The polyimide solution is a polyamic acid obtained by polycondensation of a diamine represented by the following general formula (2) and a tetracarboxylic dianhydride represented by the following general formula (3) in a solvent, The production method according to any one of inventions 1 to 9, which is a polyimide polymerization solution obtained by dehydrating and ring-closing polyamic acid.

(In the general formula ^{(2), R 1, R} 2 and R ³ are as in formula ⁽¹⁾ R 1, R ² and R ³ in the same meaning.)

(In the general formula (3), R ⁴ has the same meaning as R ⁴ in general formula (1).)

[Invention 11]
A method for producing a polyimide solution comprising at least a polyimide molded body having a repeating unit represented by the following general formula (1) and a solvent,
A polyimide molded body is obtained by spray-drying a polyimide solution containing at least the polyimide having the repeating unit represented by the general formula (1) and the first solvent at a temperature not lower than −50 ° C. of the boiling point of the first solvent. Process,
The manufacturing method characterized by including the process of mix | blending this polyimide molded object and a 2nd solvent, and obtaining a polyimide solution.

[Invention 12]
In a polyimide solution containing at least a polyimide molded body having a repeating unit represented by the following general formula (1) and a solvent, the solvent is replaced with another solvent,
A polyimide molded body is obtained by spray-drying a polyimide solution containing at least the polyimide having the repeating unit represented by the general formula (1) and the first solvent at a temperature not lower than −50 ° C. of the boiling point of the first solvent. Process,
A method comprising blending a polyimide molded body and a second solvent to obtain a polyimide solution.

According to the present invention, an efficient method for producing a polyimide molded body can be provided.

Hereinafter, the present invention will be described in more detail, but the present invention should not be construed as being limited to the description of the embodiments and examples shown below.

[Polyimide solution]
The polyimide solution according to the present invention contains at least a polyimide having a repeating unit represented by the following general formula (1) (hereinafter sometimes referred to as “polyimide (1)”) and a solvent.

In general formula (1), R ¹ is a single bond, an ether bond, a sulfide bond, a sulfoxy bond, a methylene group or an ethylene group. R ² and R ³ are each independently a hydrogen atom, a methyl group or a trifluoromethyl group. R ⁴ is a tetravalent organic group containing an aromatic ring and is represented by any of the following structures.

<Polyimide>
If the polyimide which concerns on this invention has a repeating unit represented by the said General formula (1), it will not restrict | limit in particular about another frame | skeleton. For example, you may have repeating units other than the repeating unit represented by the said General formula (1). The polyimide according to the present invention may have 50% by mole or more of the repeating unit represented by the general formula (1), preferably 75% by mole or more, more preferably only the repeating unit. Moreover, the repeating unit of the said General formula (1) may be regularly arranged in the polyimide, and may exist at random. Examples of the repeating unit other than the repeating unit represented by the general formula (1) include, but are not limited to, repeating units represented by any of the following.

The weight average molecular weight (Mw) of the polyimide according to the present invention is not particularly limited. The lower limit may be 30,000, preferably 40,000, particularly preferably 50,000. The upper limit may be 1,000,000, preferably 500,000, particularly preferably 200,000. The polyimide according to the present invention may have a weight average molecular weight of 30,000 to 1,000,000, preferably 40,000 to 500,000, particularly preferably 50,000 to 200,000. If the weight average molecular weight is less than 30,000, the polyimide re-molded after spray drying tends to cause deterioration of physical properties such as mechanical properties. If it exceeds 1,000,000, the viscosity of the solution is high, and molding by spraying is difficult. It can be difficult. In addition, the said weight average molecular weight says the value of standard polystyrene conversion by a gel permeation chromatography (henceforth GPC).

<Solvent>
The kind of solvent which concerns on this invention will not be restrict | limited especially if a polyimide (1) melt | dissolves. For example, an organic solvent such as an amide solvent, an ether solvent, an aromatic solvent, a halogen solvent, or a lactone solvent can be used, and these may be used alone or in combination of two or more. Good.

Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylformamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone and the like.

Examples of the ether solvent include diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, diphenyl ether, dimethoxyethane, diethoxyethane, tetrahydrofuran, dioxane, trioxane and the like.

Examples of the aromatic solvent include benzene, anisole, nitrobenzene, benzonitrile and the like.

Examples of the halogen solvent include chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane and the like.

Examples of the lactone solvent include γ-butyrolactone, γ-valerolactone, ε-valerolactone, γ-caprolactone, ε-caprolactone, α-methyl-γ-butyrolactone, and the like.

In one embodiment of the method of the present invention, N, N-dimethylformamide, N, N-dimethylacetamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone, dibutyl ether, diphenyl ether, anisole, nitrobenzene , Benzonitrile, 1,1,2,2-tetrachloroethane, γ-butyrolactone, γ-valerolactone, ε-valerolactone, γ-caprolactone, ε-caprolactone or α-methyl-γ-butyrolactone are preferred, and N, N -Dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone are particularly preferred.

In another embodiment of the method of the present invention, the solvent used is N-methylformamide, tetrahydrofuran, dipropyl ether, diisopropyl ether, cyclopentyl methyl ether, dimethoxyethane, dioxane, trioxane, benzene, chloroform, dichloromethane or 1,2 -Dichloroethane is preferred, with N-methylformamide, tetrahydrofuran, dipropyl ether, diisopropyl ether being particularly preferred.

In yet another embodiment of the method of the present invention, the solvent used is dipropyl ether, diisopropyl ether, tetrahydrofuran, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylformamide or N-methyl-2 -Pyrrolidone is preferred, tetrahydrofuran, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone are particularly preferred.

<Polyimide solution>
The concentration of the polyimide solution according to the present invention is not particularly limited. The polyimide is preferably 1% by mass to 30% by mass, more preferably 3% by mass to 15% by mass, and particularly preferably 3% by mass to 8% by mass with respect to the solvent component. If the concentration is within this range, the sprayed polyimide is unlikely to be thread-like, and the continuous operation of spray drying can be performed, so that the production efficiency is good. Moreover, the collection efficiency of a polyimide molded body is also good.

The polyimide solution according to the present invention contains at least a polyimide having a repeating unit represented by the general formula (1) and a solvent, and may contain other components. When other components are included, the content ratio is 15% by mass or less, preferably 10% by mass or less, and more preferably 5% or less, based on the total amount of polyimide (1) and the solvent. The type of other components is not particularly limited as long as it does not inhibit the method of the present invention. For example, the reaction material used for manufacture of polyimide (1) may be sufficient. Moreover, polyimide other than the polyimide which has a repeating unit represented by General formula (1) may be sufficient. This polyimide is not particularly limited, and one or more known polyimides can be appropriately selected and used. This polyimide may be a polyimide synthesized using “other diamine compound” described later or a tetracarboxylic dianhydride described later as a raw material.

<Production method of polyimide>
The manufacturing method of the polyimide which concerns on this invention is not specifically limited. For example, the polyimide according to the present invention can be produced according to the method for synthesizing a polyimide having an HFIP group described in Patent Document 1 and Patent Document 2. As a specific example, a diamine having an HFIP group represented by the following general formula (2) and a tetracarboxylic dianhydride represented by the following general formula (3) are essential raw materials and melted at 150 ° C. or higher. The method of making it include.

In the general formula ^{(2), R 1, R} 2 and R ³ are as in formula ⁽¹⁾ R 1, R ² and R ³ in the same meaning. R ¹ , R ² and R ³ in the general formula (1) are derived from R ¹ , R ² and R ³ in the diamine compound represented by the general formula (2), respectively.

In the general formula (3), R ⁴ have the same meanings as in formula (1) R ⁴ in. R ⁴ in the general formula (1) is derived from R ⁴ in the tetracarboxylic dianhydride represented by the general formula (3).

As another example of the method for producing polyimide according to the present invention, a diamine having an HFIP group represented by the general formula (2) and a tetracarboxylic dianhydride represented by the general formula (3) The method of dehydrating and ring-closing the polyamic acid obtained by condensation polymerization in a solvent is mentioned. This polycondensation reaction is preferably carried out at −20 to 80 ° C., and the diamine and the tetracarboxylic dianhydride are preferably reacted in a one-to-one manner in a molar ratio.

Examples of the organic solvent that can be used in the polycondensation reaction include organic solvents of the same type as those mentioned as the solvent according to the present invention, which may be used alone or in combination of two or more kinds. Also good.

The polyimide according to the present invention can be obtained by further dehydrating and ring-closing the polyamic acid obtained by the condensation polymerization reaction. This dehydration cyclization reaction is performed under conditions such as a heating method and a chemical method that promote cyclization. In the heating method, the polyamic acid immediately after polymerization is imidized by heating at a high temperature of 150 to 250 ° C., and in the chemical method, a base such as pyridine or triethylamine and acetic anhydride are each 2 molar equivalents relative to the starting diamine at 0 to 50 ° C. By adding less than 10 equivalents as above, imidization can be performed to obtain a polyimide polymerization solution according to the present invention. The obtained polyimide polymerization liquid may be used as it is as the polyimide solution according to the present invention, or may be used as the polyimide solution according to the present invention after being concentrated or diluted. It is preferable to adjust the concentration of the polyimide solution according to the present invention described above. In the case of dilution, it is preferable to use the same type of organic solvent as mentioned as the solvent according to the present invention, and it may be used alone or two or more kinds of mixed solvents may be used. The kind of the organic solvent is not particularly limited as long as the polyimide according to the present invention is dissolved.

Hereinafter, the raw materials used for the production of the polyimide according to the present invention will be described in detail.

(Diamine having HFIP group)
In the production of the polyimide according to the present invention, a diamine having an HFIP group represented by the general formula (2) is used as one of the raw material compounds.

Among these diamines, a diamine represented by the following formula (4) (hereinafter sometimes referred to as “HFIP-MDA”) and a diamine represented by the following formula (5) (hereinafter referred to as “HFIP-MDA”) due to the availability of raw materials. And may be referred to as “HFIP-mTB”).

Organic solvent solubility, viscosity, strength during re-molding, surface characteristics (water repellency, oil repellency), resistance (weather resistance, corrosion resistance, etc.), other characteristics (transparent) Diamine having an HFIP group represented by the general formula (2) and other diamine compounds (hereinafter referred to as other diamine compounds) in order to adjust heat resistance, low refractive index, low dielectric constant, etc. May be used in combination. The amount of the other diamine compound used is 5% or more and 50% or less, preferably 10% or more and 30% or less, expressed as mass% with respect to the weight of the entire diamine. When the content ratio of other diamine compounds is less than 5%, the effect of adjusting characteristics such as mechanical strength becomes small. When the content ratio of other diamine compounds is more than 50%, there is a possibility that the solvent solubility is lowered and the viscosity is improved and spray drying cannot be performed.

Specific examples of other diamine compounds that can be used in combination include benzidine, 2,2′-dimethoxybenzidine, 3,3′-dimethoxybenzidine, 2,2′-dimethylbenzidine, 3,3′-dimethylbenzidine, 2,2 '-Bis (trifluoromethyl) benzidine, 3,3'-bis (trifluoromethyl) benzidine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-diamino Toluene, 2,4-diamino-m-xylene, 2,4-diamino-1,3,5-trimethylbenzene, 2,3,5,6-tetramethyl-1,4-phenylenediamine, 4,4'- Diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylsulfone, 4,4 -Diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4'-bis ( 4-aminophenoxy) biphenyl, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 2,2-bis (4- (4-aminophenoxy) phenyl ) Propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 2,2-bis (4- (3-aminophenoxy) phenyl) propane, 2,2-bis (4-amino) Phenyl) hexafluoropropane, 2,2-bis (3-aminophenyl) hexafluoropropane, 2,2-bis (3-amino-) -Hydroxyphenyl) hexafluoropropane, 2,2-bis (3-amino-4-methylphenyl) hexafluoropropane, 4,4'-diaminobenzanilide, 4,4'-ethylenedianiline, 1,1-bis (4-aminophenyl) cyclohexane, 9,9-bis (4-aminophenyl) fluorene, 2,7-diaminofluorene, α, α'-bis (4-aminophenyl) -1,4-diisopropylbenzene, or 1 , 3-bis (1- (4-aminophenyl) -1-methylethyl) benzene and the like. A part of hydrogen atoms of the aromatic ring of the diamine may be substituted with a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, a fluoroalkyl group, a carboxyl group, an HFIP group, a hydroxy group, or a cyano group. . Moreover, these may be used independently and can also be used together 2 or more types.

Among these, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,5-diaminotoluene, 4-diamino-m-xylene, 2,4- 2,2-bis (4- (4-aminophenyl) hexafluoropropane, 2,2-bis (4- (4-aminophenyl) hexafluoropropane, or 2,2′-bis (trifluoromethyl) benzidine is particularly preferred.

(Tetracarboxylic dianhydride)
In the production of the polyimide according to the present invention, a tetracarboxylic dianhydride represented by the above general formula (3) is used as one of the raw material compounds.

Specifically, benzene-1,2,4,5-tetracarboxylic dianhydride (hereinafter sometimes referred to as “PMDA”), 3,6-bis (trifluoromethyl) benzene-1,2 , 4,5-tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter sometimes referred to as “BPDA”), 4,4 ′-(hexa Fluoroisopropylidene) diphthalic anhydride (hereinafter sometimes referred to as “6FDA”), 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride (hereinafter sometimes referred to as “BTDA”) ), 4,4′-oxydiphthalic dianhydride (hereinafter sometimes referred to as “ODPA”), thiophene-2,3,4,5-tetracarboxylic dianhydride, and the like. . These may be used alone or in combination of two or more.

Among these, PMDA, BPDA, BTDA, 6FDA, and ODPA are preferable from the viewpoint of availability, and BPDA, 6FDA, and ODPA are particularly preferable because of high solvent solubility of polyimide.

<Spray drying of polyimide solution>
The polyimide molded body according to the present invention can be obtained by spray drying the polyimide solution according to the present invention at a predetermined temperature.

The method for spray drying the polyimide solution according to the present invention is not particularly limited as long as the polyimide molded body according to the present invention is obtained. Usually, a spray dryer (spray dryer) is used. As this spray dryer, a spray dryer having at least a pressure nozzle for ejecting the polyimide solution and a drying chamber for drying the ejected polyimide is preferable. As the spray dryer, for example, a spray dryer device described in JP-A-1-194901, a spray-drying device described in JP-A-8-299701, and the like can be used. Not.

噴霧 Conventional methods such as rotating disk, pressure nozzle, one-fluid nozzle, two-fluid nozzle, four-fluid nozzle, and ultrasonic nozzle can be adopted as the spraying method. In particular, the two-fluid nozzle and the four-fluid nozzle are preferable because the shape of the obtained polyimide molded body is likely to be a powder that can be easily processed and molded.

The temperature at the time of spray drying may be adjusted according to the boiling point of the solvent to be used. However, in order to obtain a solid polyimide, the boiling point of the solvent to be used is preferably −50 ° C. or higher. The temperature at the time of spray drying is more preferably −40 ° C. or more, particularly preferably −25 ° C. or more, of the boiling point of the solvent used. Although the upper limit of the temperature at the time of the spray drying depends on the durability of the spray dryer, it is preferably + 100 ° C. or less, preferably + 50 ° C. or less, particularly preferably + 25 ° C. of the boiling point of the solvent used. If the temperature is too high, the solvent may rapidly evaporate and a desired polyimide molded body may not be obtained, or the polyimide may solidify near the sprayer and clogging may occur. If the temperature is too low, drying may be insufficient, and the polyimide molding may adhere or become sticky.

In particular, when tetrahydrofuran (boiling point: 66 ° C.) is used as a solvent, the temperature at the time of spray drying may be 40 ° C. to 160 ° C., preferably 45 ° C. to 155 ° C., particularly preferably 50 to 150 ° C. .

When N, N-dimethylacetamide (boiling point: 165 ° C.) is used as the solvent, the temperature during the spray drying may be 130 ° C. to 260 ° C., preferably 140 ° C. to 260 ° C., preferably 150 ° C. A temperature of ˜250 ° C. is particularly preferred.

When N-methyl-2-pyrrolidone (boiling point: 202 ° C.) is used as the solvent, the temperature at the time of spray drying may be 160 ° C. to 300 ° C., preferably 170 ° C. to 280 ° C., preferably 180 ° C. to 270 ° C. is particularly preferred.

The shape of the polyimide molded body obtained by spray drying is not particularly limited. It may be in various shapes such as powder, thread, and cotton. Especially, since the continuous operation of spray drying can be performed more stably, it is preferable that a powdery polyimide molded body is obtained. Of course, there is no problem in the shape of the product even if the polyimide molded body has other shapes.

The particle size of the polyimide molded body obtained by spray drying is not particularly limited. From the viewpoint of handling, the particle size of the polyimide molded body may be 1 to 20 μm, preferably 2 to 15 μm, particularly preferably 4 to 10 μm.

Here, the particle diameter of the polyimide molded body was measured by wet laser diffraction using a Microtrac particle size analyzer (MT-3300EX2 manufactured by Nikkiso Co., Ltd.) and 1-butanol (solvent refractive index = 1.40) as a measurement solvent. This is the center particle diameter when measured by the method and assuming that the refractive index of the particles is 1.81.

The amount of the solvent remaining in the polyimide molded body obtained by spray drying is preferably 30% by mass or less, and more preferably 20% by mass or less. When the residual solvent amount is higher than 30% by mass, the polyimide molded body may be adhered or sticky.

The polyimide molded body obtained by the method of the present invention can be easily used for various applications. Moreover, the polyimide polymerization liquid synthesize | combined from the above-mentioned raw material compound is used for the method of this invention, The polyimide molded body of various shapes can be isolate | separated easily from a polymerization liquid.

The obtained polyimide molded body may be subjected to various uses as a polyimide solution dissolved in another type of solvent in addition to the solvent according to the present invention. Thus, the solvent (first solvent) contained in the polyimide solution according to the present invention can be replaced with another type of solvent (second solvent) according to the desired application. The other type of solvent is not particularly limited. For example, amide solvents, ether solvents, aromatic solvents, halogen solvents, lactone solvents, alcohol solvents, ketone solvents, ester solvents, and other organic solvents can be used. Alternatively, two or more kinds may be used in combination.

Examples of the alcohol solvent include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and ethylene glycol.

Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and cyclohexanone.

Examples of the ester solvent include methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate, and methyl butyrate.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the examples.

1. Preparation of polyimide solution (varnish) [Preparation Example 1] Preparation of THF solution of polyimide (A) 212.1 g (400 mmol) of HFIP-MDA, 177 was placed in a 2 L three-necked flask equipped with a nitrogen introduction tube and a stirring blade. 0.7 g (400 mmol) of 6FDA and 480 g of tetrahydrofuran (THF) were added and stirred at 20 ° C. under a nitrogen atmosphere to obtain a reaction solution. To the obtained reaction solution, 126.6 g (1600 mmol) of pyridine and 163.3 g (1600 mmol) of acetic anhydride were added in order, and the mixture was further stirred at 20 ° C. for 24 hours for imidation. Polyimide (A) was obtained. Thereafter, 717.3 g of THF was added to prepare a 20 wt% THF solution of polyimide (A) (hereinafter sometimes referred to as “varnish A”).
When GPC measurement of varnish A (model name: HLC-8320GPC (manufactured by Tosoh Corporation), column: TSKgel SuperHZM-H (manufactured by Tosoh Corporation), solvent: tetrahydrofuran) was performed, Mw = 74100, Mw / Mn = 1 .91.

A part of a THF solution (varnish A) of polyimide (A) is diluted with THF, and a 10 wt% THF solution of polyimide (A) (hereinafter sometimes referred to as “varnish B”), polyimide (A) A 5 wt% THF solution (hereinafter sometimes referred to as “varnish C”) was prepared.

[Preparation Example 2] Preparation of DMAc solution of polyimide (A) 20 wt% of polyimide (A) represented by the following reaction formula by the same method as Preparation Example 1 except that dimethylacetamide (DMAc) was used instead of THF. % DMAc solution (hereinafter sometimes referred to as “varnish D”) was prepared.
When the GPC measurement of varnish D was performed, Mw = 57200 and Mw / Mn = 2.08.

A part of a 20 wt% DMAc solution (varnish D) of polyimide (A) is diluted with DMAc, and a 10 wt% DMAc solution of polyimide (A) (hereinafter sometimes referred to as “varnish E”), polyimide (A). ) 7.5 wt% DMAc solution (hereinafter sometimes referred to as “varnish F”) and polyimide (A) 5 wt% DMAc solution (hereinafter sometimes referred to as “varnish G”). .

[Preparation Example 3] Preparation of NMP solution of polyimide (A) Polyimide represented by the following reaction formula by the same method as Preparation Example 1 except that N-methyl-2-pyrrolidone (NMP) was used instead of THF. A 20 wt% NMP solution of (A) (hereinafter sometimes referred to as “varnish H”) was prepared.
When the GPC measurement of the DMAc solution (varnish H) of polyimide (A) was performed, Mw = 122000 and Mw / Mn = 1.96.

A 20 wt% NMP solution (varnish H) of polyimide (A) was diluted with NMP to prepare a 5 wt% NMP solution of polyimide (A) (hereinafter sometimes referred to as “varnish I”).

[Preparation Example 4] Preparation of DMAc solution of polyimide (B) Instead of HFIP-MDA, 6FDA and DMAc, 212.1 g (400 mmol) of HFIP-mTB, 117.7 g (400 mmol) of BPDA, 480 g of DMAc A DMAc solution of polyimide (B) represented by the following reaction formula (hereinafter sometimes referred to as “varnish J”) was prepared in the same manner as in Example 2 except that was used.
When the GPC measurement of the DMAc solution (varnish J) of polyimide (B) was performed, Mw = 76100 and Mw / Mn = 1.80.

A part of a 20 wt% DMAc solution (varnish J) of polyimide (B) was diluted with DMAc to prepare a 5 wt% DMAc solution of polyimide (B) (hereinafter sometimes referred to as “varnish K”).

2. Spray drying of polyimide solution (varnish) [Examples 1 to 16, Comparative Examples 1 and 2]
The polyimide solutions obtained in Preparation Examples 1 to 4 were sprayed using a spray dryer (spraying method: 4-fluid nozzle), with a predetermined flow rate, a predetermined pressure (nozzle gas pressure), and a predetermined temperature (spray dryer inlet temperature). ) To obtain polyimide molded bodies. These results are shown in Table 1.

As shown in Table 1, in any of Examples 1 to 16 in which spray drying was performed at a temperature of −50 ° C. or higher, which is the boiling point of the solvent used, a solid polyimide molded body was obtained by spray drying. On the other hand, in Comparative Examples 1 and 2 in which spray drying was performed at a temperature lower than the boiling point of the solvent used, −50 ° C., the polyimide molded body could not be sufficiently dried, and a solid polyimide molded body could not be obtained. .

<Particle size distribution measurement>
The particle size of the obtained polyimide molded body was measured by a wet laser diffraction method using a Microtrac particle size analyzer (MT-3300EX2 manufactured by Nikkiso Co., Ltd.). At this time, 1-butanol (solvent refractive index = 1.40) was used as a measurement solvent, and the center particle diameter when the refractive index of the particles was assumed to be 1.81 was determined.
The particle sizes of the obtained polyimide moldings were as follows: Example 2 (8.94 μm), Example 4 (4.82 μm), Example 7 (15.5 μm), and Example 8 (13 .3 μm), Example 9 (9.89 μm), Example 10 (6.36 μm), Example 11 (6.67 μm), Example 16 (9.36 μm).

[Reference Example] Preparation of polyimide powder by precipitation / drying process with poor solvent In a mixed solution of water (500 g) and methanol (500 g) stirred with a mechanical stirrer, a 20 wt% DMAc solution (296. 1 g) was dropped to solidify the polyimide (A). The solidified polyimide (A) was recovered, and the recovered polyimide (A) and water (200 g) were placed in a mixer and pulverized. Thereafter, the polyimide (A) recovered by filtration was placed in a mixed solution of water (500 g) and methanol (500 g), stirred for 1 hour, and then filtered under reduced pressure to recover the polyimide (A). The recovered polyimide (A) was put in a petri dish and dried in a vacuum oven at 100 ° C. and 0.5 Pa for 16 hours to obtain 103.8 g (theoretical recovery amount: 94.98 g) of polyimide (A) powder. It was.

Claims

A method for producing a polyimide molded body having a repeating unit represented by the following general formula (1),
A method of producing, characterized in that a polyimide solution containing at least a polyimide having a repeating unit represented by the following general formula (1) and a solvent is spray-dried at a temperature not lower than −50 ° C. of the boiling point of the solvent.

(In the general formula (1), R 1 is a single bond, an ether bond, a sulfide bond, a sulfoxy bond, a methylene group or an ethylene group, and R 2 and R 3 are each independently a hydrogen atom, a methyl group or trifluoromethyl. R 4 is a tetravalent organic group containing an aromatic ring, and is represented by any of the following structures)
The production method according to claim 1, wherein the solvent is an amide solvent, an ether solvent, an aromatic solvent, a halogen solvent or a lactone solvent.
Solvents are N, N-dimethylformamide, N, N-dimethylacetamide, N-methylformamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, cyclopentyl Methyl ether, diphenyl ether, dimethoxyethane, diethoxyethane, tetrahydrofuran, dioxane, trioxane, benzene, anisole, nitrobenzene, benzonitrile, chloroform, dichloromethane, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, γ- 8. Butyrolactone, γ-valerolactone, ε-valerolactone, γ-caprolactone, ε-caprolactone or α-methyl-γ-butyrolactone, The method according to.
Solvents are N, N-dimethylformamide, N, N-dimethylacetamide, hexamethylphosphoric triamide, N-methyl-2-pyrrolidone, dibutyl ether, diphenyl ether, anisole, nitrobenzene, benzonitrile, 1,1,2,2 The production method according to claim 1, characterized in that it is tetrachloroethane, γ-butyrolactone, γ-valerolactone, ε-valerolactone, γ-caprolactone, ε-caprolactone or α-methyl-γ-butyrolactone.
The solvent is N-methylformamide, tetrahydrofuran, dipropyl ether, diisopropyl ether, cyclopentyl methyl ether, dimethoxyethane, dioxane, trioxane, benzene, chloroform, dichloromethane or 1,2-dichloroethane. 2. The production method according to 1.
6. The production method according to claim 1, wherein the polyimide solution contains 1 to 30% by mass of polyimide with respect to the solvent.
The production method according to any one of claims 1 to 6, wherein the spray drying is performed using a spray dryer.
The manufacturing method according to claim 7, wherein the spray dryer includes a two-fluid nozzle or a four-fluid nozzle.
The production method according to any one of claims 1 to 8, wherein the spray drying is performed at a temperature not lower than -50 ° C and not higher than 100 ° C of the boiling point of the solvent.
The polyimide solution is a polyamic acid obtained by polycondensation of a diamine represented by the following general formula (2) and a tetracarboxylic dianhydride represented by the following general formula (3) in a solvent, 10. The production method according to claim 1, which is a polyimide polymerization solution obtained by dehydrating and ring-closing polyamic acid.

(In the general formula (2), R 1, R 2 and R 3 are as in formula (1) R 1, R 2 and R 3 in the same meaning.)

(In the general formula (3), R 4 has the same meaning as R 4 in general formula (1).)
A method for producing a polyimide solution comprising at least a polyimide molded body having a repeating unit represented by the following general formula (1) and a solvent,
A step of obtaining a polyimide molded body by spray-drying a polyimide solution containing at least a polyimide having a repeating unit represented by the general formula (1) and a first solvent at a temperature of −50 ° C. or higher of the first solvent; ,
The manufacturing method characterized by including the process of mix | blending this polyimide molded object and a 2nd solvent, and obtaining a polyimide solution.

(In the general formula (1), R 1 is a single bond, an ether bond, a sulfide bond, a sulfoxy bond, a methylene group or an ethylene group, and R 2 and R 3 are each independently a hydrogen atom, a methyl group or trifluoromethyl. R 4 is a tetravalent organic group containing an aromatic ring, and is represented by any of the following structures)
In a polyimide solution containing at least a polyimide molded body having a repeating unit represented by the following general formula (1) and a solvent, the solvent is replaced with another solvent,
A step of obtaining a polyimide molded body by spray-drying a polyimide solution containing at least a polyimide having a repeating unit represented by the general formula (1) and a first solvent at a temperature of −50 ° C. or higher of the first solvent; ,
A method comprising blending a polyimide molded body and a second solvent to obtain a polyimide solution.

(In the general formula (1), R 1 is a single bond, an ether bond, a sulfide bond, a sulfoxy bond, a methylene group or an ethylene group, and R 2 and R 3 are each independently a hydrogen atom, a methyl group or trifluoromethyl. R 4 is a tetravalent organic group containing an aromatic ring, and is represented by any of the following structures)