WO2020179817A1

WO2020179817A1 - Purification method for diamine compound, neutral salt of diamine compound, diamine, and polyimide

Info

Publication number: WO2020179817A1
Application number: PCT/JP2020/009122
Authority: WO
Inventors: 斉二郎福田; 譲本松
Original assignee: 太陽ホールディングス株式会社
Priority date: 2019-03-04
Filing date: 2020-03-04
Publication date: 2020-09-10
Also published as: TW202104167A; JP2022068377A

Abstract

[Problem] To provide a purification method that enables purification of a diamine compound to which none of purification methods by distillation, sublimation, or recrystallization are applicable, and that, as another purpose of the method, enables provision of a polyimide compound having excellent colorlessness and transparency. [Solution] The purification method for a diamine compound according to the present invention is characterized by comprising: a step for preparing a neutral salt of a diamine compound and dissolving the neutral salt of the diamine compound in a solvent; a step for supplying, to a liquid separation tank, an extraction solvent and the solvent in which the neutral salt of the diamine compound has been dissolved, and bringing these solvents into a phase-separated state; a step for extracting, into the extraction solvent, impurities derived from the diamine compound and contained in the solvent in which the neutral salt of the diamine compound has been dissolved; and a step for causing the neutral salt of the diamine compound dissolved in the solvent to undergo a weak base liberation reaction in the presence of a reducing agent, to obtain a diamine.

Description

Diamine compound purification method, diamine compound neutralized salt, diamine, and polyimide

The present invention relates to a method for purifying a diamine compound, a neutralized salt of a diamine compound, a diamine, and a polyimide.

Diamine compounds are compounds that are widely used in the fields of organic chemistry and polymer chemistry, and are useful in a wide variety of fields for industrial applications such as fine chemicals, raw materials for medical and agricultural chemicals and resin raw materials, and electronic information materials and optical materials. It is a compound.

Among them, in the field of polymer chemistry, a polyimide obtained by polymerizing a diamine compound and an acid anhydride has various properties such as high heat resistance, insulating properties, toughness and dimensional stability. Widely used in various fields. In such a polyimide, it is known that the properties of the diamine compound and the acid anhydride as the raw material (monomer) due to the structure and the molecular weight greatly affect the properties of the polymerized polyimide.

For example, Japanese Unexamined Patent Application Publication No. 2018-118947 (Patent Document 1) describes a method for synthesizing a diamine compound having a specific structure, and a polyimide having high organic solvent solubility and melt moldability synthesized by using the diamine compound. Proposed.

On the other hand, as an industrial technology using polyimide in recent years, the glass base material such as the cover glass provided in the organic EL display device is changed to a resin film containing polyimide (also referred to as a polyimide film), and the organic EL display device is flexible. Is being considered.
Such a polyimide film is required to have not only the above-mentioned flexibility but also colorless transparency that does not interfere with the image of the organic EL display device.

Then, in order to synthesize a colorless and transparent polyimide or polyimide film, it is necessary to use a monomer (diamine) purified to an extremely high purity.
Further, for example, as a purification method of a diamine compound (crude diamine), a distillation purification method proposed in JP 2011-26224 A (Patent Document 2), R. Ishige, et al., Macromolecules 2017, 5, 2112-2123. (Non-patent document 1), a sublimation purification method and a generally known purification method by recrystallization in a solution can be mentioned.

Japanese Unexamined Patent Publication No. 2018-118947 Japanese Unexamined Patent Publication No. 2011-26224

However, the diamine compound as disclosed in Patent Document 1 has a problem that the distillation purification method proposed in Patent Document 2, the sublimation purification method proposed in Non-Patent Document 1, and the purification method by crystallization cannot be applied. Therefore, a new method for purifying a diamine compound has been sought.

The present invention was made in order to solve such a problem, and its main purpose is to enable purification of diamine compounds to which purification methods by distillation, sublimation and recrystallization cannot be applied, and is excellent in colorless transparency. It is to provide a purification method which enables the provision of a colorless polyimide.

Another object of the present invention is to provide a diamine compound neutralized salt that can be used in the above-mentioned purification method in order to provide a high-purity diamine.

Further, an object of the present invention is to provide a polyimide having a neutralizing salt of the diamine compound, a basic reagent, and a diamine consisting of a reaction product with a reducing agent, which has less impurities and is excellent in colorless transparency. Is to provide a diamine to be used.

Furthermore, an object of the present invention is to provide a polyimide made of the diamine and having excellent colorless transparency.

As a result of diligent research aimed at achieving the above objects, the present inventors have found that the diamine compound to which a purification method by distillation, sublimation and recrystallization cannot be applied has a high boiling point due to its structure, and therefore diamine or sublimation It was noticed that the coloration due to oxidation was progressing in the process of recrystallization because it was difficult to purify by the method and the crystallization was slow.

Therefore, impurities (oxides of the diamine compound) are removed by temporarily converting such a diamine compound into a neutralizing salt (diamine compound neutralizing salt), and further, the diamine compound neutralizing salt is used as a reducing agent. The present invention has been completed based on the finding that a high-purity diamine without coloring can be obtained by allowing a basic reagent to react with a basic reagent in the presence of a weak base to cause precipitation.

That is, the method for purifying a diamine compound of the present invention, a step of dissolving the diamine compound as a neutralized salt in a solvent,
A solvent in which a neutralized salt of a diamine compound is dissolved, and an extraction solvent are supplied to a separation tank, and these are brought into a state of phase separation, and the neutralized salt of the diamine compound is derived from the diamine compound contained in the solvent. The process of extracting impurities in the extraction solvent and
A neutralized salt of a diamine compound dissolved in a solvent, a step of reacting a weak base in the presence of a reducing agent to obtain a diamine,
It is characterized by including.

In one embodiment, the ionization potential is 0.1 eV or more larger than the ionization potential of the diamine compound.

In one embodiment, the amount of the reducing agent used is 1 mol% or more and 20 mol% or less with respect to 100 mol% of the diamine compound.

In one embodiment, the diamine in the diamine compound is represented by the following general formula (1).

(In the above formula (1),
Any _{one of} R ₁ to R ₄ is selected from an aromatic group having 6 to 10 carbon atoms, a phenoxy group having 6 to 10 carbon atoms, a benzyl group having 6 to 10 carbon atoms and a benzyloxy group having 6 to 10 carbon atoms. , R ₁ to R ₄ other than the above are hydrogen atoms. )

The neutralized salt of the diamine compound of the present invention is characterized by being represented by the following general formula (2), and can be used in the above-mentioned purification method in order to provide a high-purity diamine.

(In the above formula (2),
Any _{one of} R ₁ to R ₄ is selected from an aromatic group having 6 to 10 carbon atoms, a phenoxy group having 6 to 10 carbon atoms, a benzyl group having 6 to 10 carbon atoms and a benzyloxy group having 6 to 10 carbon atoms. ,
The other R ₁ to R ₄ are hydrogen atoms,
X is selected from hydrochloric acid, sulfuric acid, sulfonic acid and organic acid. )

The diamine of the present invention is characterized by comprising a reaction product of a diamine compound neutralizing salt represented by the above general formula (2), a basic reagent, and a reducing agent. The diamine is a high-purity diamine that is not colored and whose oxidation in the process of recrystallization is effectively prevented.

In one embodiment, the ionization potential of the reducing agent is 0 eV or more and 4.86 eV or less.

In one embodiment, the reducing agent is aniline, triphenylphosphine, triphenyl phosphate, triphenyl phosphite, potassium sulfide, sodium sulfide, sodium sulfite, potassium sulfite, sodium hypophosphite, sodium disulfite, and One or more reducing agents selected from the group consisting of sodium borohydride.

The polyimide of the present invention is characterized by using the above diamine. The polyimide has excellent colorless transparency and can be suitably used as a substitute polyimide film for a cover glass provided in an organic EL display device.

According to the purification method of the present invention, it is possible to purify a diamine compound to which a purification method by distillation, sublimation and recrystallization cannot be applied, and to provide a polyimide excellent in colorless transparency.
Further, according to the present invention, it is possible to provide a neutralized salt of a diamine compound, which can be used in the above-described purification method in order to provide a high-purity diamine.
Further, according to the present invention, it is possible to provide a polyimide having a neutralizing salt of the above diamine compound, a basic reagent, and a diamine consisting of a reaction product of a reducing agent, having less impurities, and being excellent in colorless transparency. Can be provided.
Further, according to the present invention, it is possible to provide a polyimide that is prepared by using the above diamine and that has excellent colorless and transparent properties.

In addition, in this specification, "diamine" means the purified "diamine compound (crude diamine)".

[Purification method of diamine compound]
The method for purifying a diamine compound according to the present invention is
The process of using a diamine compound as a neutralizing salt and dissolving it in a solvent,
The solvent in which the neutralized salt of the diamine compound is dissolved, and the extraction solvent are supplied to the separation tank, and these are brought into a state of phase separation, and the diamine compound contained in the solvent in which the neutralized salt of the diamine compound is dissolved. The step of extracting the derived impurities into the extraction solvent and
A neutralized salt of a diamine compound dissolved in a solvent, a step of reacting a weak base in the presence of a reducing agent to obtain a diamine,
It is characterized by including.
Hereinafter, each step included in the method for purifying a diamine compound according to the present invention will be described in detail.

[Dissolution step of diamine compound]
The purification method of the present invention includes a step of dissolving a diamine compound (crude diamine) as a neutralized salt in a solvent.
The diamine compound to be purified is not particularly limited, and conventionally known diamine compounds can be used. The purification method of the present invention can effectively purify even a diamine compound having a high boiling point.
For example, the diamine compound represented by the following general formula (1) was useful for obtaining a polyimide having high heat resistance and dimensional stability and structurally colorless and transparent, but had a high boiling point. Conventional purification methods could not be applied, and sufficient effects could not be obtained for colorless transparency. However, according to the purification method of the present invention, even such a diamine compound can be effectively purified, and in addition to high heat resistance and dimensional stability, an excellent colorless and transparent polyimide can be obtained. Can be done.

In the general formula _(1), any one of R 1 ~ _{R 4} are preferably either _{R 1} or _{R 3,} particularly preferably is _{R 3,} aromatic groups having 6 to 10 carbon atoms, 6 carbon atoms It is selected from a phenoxy group having a phenoxy group of about 10 and a benzyl group having 6 to 10 carbon atoms and a benzyloxy group having 6 to 10 carbon atoms, and the other R ₁ to R ₄ are hydrogen atoms.
The aromatic group having 6 to 10 carbon atoms includes a phenyl group, a trill group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group, a diethylphenyl group, a propylphenyl group, a butylphenyl group, a fluorophenyl group, and a pentafluorophenyl group. , Chlorphenyl group, bromophenyl group, methoxyphenyl group, dimethoxyphenyl group, ethoxyphenyl group, diethoxyphenyl group, methoxybenzyl group, dimethoxybenzyl group, ethoxybenzyl group, diethoxybenzyl group, aminophenyl group, aminobenzyl group , Nitrophenyl group, nitrobenzyl group, cyanophenyl group, cyanobenzyl group, phenethyl group, phenylpropyl group, phenylamino group, diphenylamino group, biphenyl group, naphthyl group and the like.
Examples of the phenoxy group having 6 to 10 carbon atoms include a methylphenoxy group, an ethylphenoxy group, a propylphenoxy group, a dimethylphenoxy group, a diethylphenoxy group, a methoxyphenoxy group, an ethoxyphenoxy group and a dimethoxyphenoxy group.
Examples of the benzyl group having 6 to 10 carbon atoms include a benzyl group, a methylbenzyl group, an ethylbenzyl group, a propylbenzyl group, a dimethylbenzyl group, a methoxybenzyl group, an ethoxybenzyl group and a methoxybenzyl group.
As the benzyloxy group having 6 to 10 carbon atoms, the methylbenzyloxy group includes a benzyloxy group, a betylbenzyloxy group, an ethylbenzyloxy group, a propylbenzyloxy group, a dimethylbenzyloxy group, a methoxybenzyloxy group and an ethoxy. Benzyloxy group and the like can be mentioned.
Among the above, from the viewpoint of transparency, an aromatic group having 6 to 10 carbon atoms is more preferable, and a phenyl group, a tolyl group, a methylphenyl group, a dimethylphenyl group, an ethylphenyl group and a diethylphenyl group are more preferable, and phenyl. Groups are particularly preferred.

The neutralized salt of the diamine compound is formed by adding an acidic reagent, and as the acidic reagent, for example, hydrochloric acid, sulfuric acid, sulfonic acid, phosphoric acid, organic acid or the like can be used. Above all, from the viewpoint of solubility, the hydrochloride salt using hydrochloric acid is preferable.

The solvent for dissolving the neutralized salt of the diamine compound is not particularly limited as long as it can dissolve the neutralized salt of the diamine compound, and examples thereof include water, acetone, methyl ethyl ketone, tetrahydrofuran, 1,2. -Dimethoxyethane, methanol, ethanol, propanol, 2-propanol, butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol Monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, γ-butyrolactone, acetonitrile, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and mixtures thereof A solvent etc. are mentioned.

[Extraction process]
As the extraction solvent used in the extraction step, phase separation occurs with a solvent in which a neutralizing salt of the diamine compound is dissolved, and impurities derived from the diamine compound contained in this solvent (for example, the amino group contained in the diamine are oxidized. The solvent is not particularly limited as long as it can dissolve the solvent and the neutralizing salt of the diamine compound is not dissolved. For example, chloroform, dichloromethane, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, etc. Butyl acetate, toluene, 2-methyltetrahydrofuran, anisole and the like can be mentioned.

The shape and size of the separating tank are not particularly limited. In one embodiment, a separating funnel can be used as the separating tank.

[Weak base release reaction step]
The purification method of the present invention includes a step of reacting a neutralized salt of a diamine compound dissolved in a solvent with a weak base in the presence of a reducing agent. By carrying out the weak base release reaction in the presence of such a reducing agent, crystallization as shown by the above general formula (1) is slow, and even a diamine that requires a long time to be precipitated is suppressed by the reducing agent. Therefore, it is possible to stably obtain a high-purity diamine without coloring.
In one embodiment, the weak base liberation reaction step includes a step of causing a neutralization salt of a diamine compound dissolved in a solvent to undergo a weak base liberation reaction to precipitate a diamine.
Moreover, in one embodiment, the weak base liberation reaction step includes a step of filtering the precipitated diamine.
Further, in one embodiment, the weak base liberation reaction step includes a step of washing the precipitated diamine.
Further, in one embodiment, the weak base release reaction step includes the step of drying the washed diamine.

In the weak base liberation reaction step, the reducing agent that can be used is not particularly limited as long as it has an ionization potential smaller than that of diamine (diamine compound).
Preferably, a reducing agent having an ionization potential lower than that of the diamine compound by 0.1 eV or more, more preferably 0.2 eV or more is used.
For example, the following diamine compound satisfying the above general formula (1) has an ionization potential of about 4.96 eV. Therefore, any reducing agent having a value equal to or higher than this value can be used without particular limitation. For example, aniline, triphenylphosphine, triphenyl phosphate, triphenyl phosphite, potassium sulfide, sodium sulfide, sodium sulfite, sulfite. Potassium, sodium hypophosphite, sodium disulfite, sodium borohydride and the like can be used.

In the present invention, the ionization potential is estimated from the energy of the highest occupied molecular orbital (HOMO: Highest Occupied Molecular Orbital) obtained by quantum calculation. The HOMO energy level E _HOMO was calculated by the density functional theory (DFT) using B3LYP / 6-31 (d, p) as a basis function using Gaussian16. And using the HOMO energy level of ferrocene as estimated by the calculation method (-5.16EV), the ionization potential _E OX of each diamine (compound) and a reducing agent (eV) is
E _OX =-(E _HOMO -(-5.16) -4.80) = -E _HOMO +0.36 (eV)
Can be expressed as Here, E _HOMO is the HOMO energy level of each diamine (compound) and reducing agent obtained by DFT calculation, and the ionization potential of ferrocene is set to 4.80 eV.

The amount of the reducing agent used is preferably 1 mol% or more and 20 mol% or less, and more preferably 5 mol% or more and 10 mol% or less, based on 100 mol% of the diamine compound. This makes it possible to improve the colorless transparency of the polyimide synthesized by the diamine obtained by purification.

The weak base release reaction of the solvent in which the neutralized salt of the diamine compound is dissolved is carried out by adding a basic reagent.
Examples of the basic reagent include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide (TMAH), sodium methoxide, sodium ethoxide, potassium-tert-butoxide, triethylamine, pyrimidine, and diazabicycloundecene (DBU). ), Potassium carbonate, sodium carbonate, cesium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate and the like can be used.
Among the above, sodium hydroxide, sodium methoxide, sodium ethoxide, sodium carbonate and sodium hydrogen carbonate are preferable.

In one embodiment, the weak base liberation reaction step includes a step of filtering the precipitated diamine, and the filtering method is not particularly limited, and natural filtration, suction filtration, pressure filtration and the like can be used.

In one embodiment, the weak base liberation reaction step includes a step of washing the precipitated diamine, and as the washing liquid, alcohols such as methanol, ethanol and propanol can be used.

In one embodiment, the weak base release reaction step comprises the step of drying the washed diamine. The drying conditions are not particularly limited, but for example, in a reduced pressure environment (10 ^-1 to 10 ^-3 Torr), the conditions should be 2 hours or more and 12 hours or less at a temperature of 25 ° C. or higher and 50 ° C. or lower. Can be done.

[Polyimide synthesis method]
The method for synthesizing a polyimide of the present invention is characterized by being a reaction product of a diamine obtained by the above-mentioned purification method and an acid anhydride.

[Acid anhydride]
The acid anhydride is not particularly limited, and is, for example, pyromellitic anhydride, biphenyl-3,4,3', 4'-tetracarboxylic dianhydride, benzophenone-3,4,3', 4'. -Tetracarboxylic acid dianhydride, oxydiphthalic acid dianhydride, diphenylsulfone-3,4,3', 4'-tetracarboxylic acid dianhydride, 4,4'-(2,2-hexafluoroisopropyridene) diphthal Acid dianhydride, 9,9-bis (3,4-dicarboxyphenyl) fluorene hydride, 4,4'-(4,4'-isopropylidene diphenoxy) diphthalic anhydride, 2,3 6,7-naphthalenetetracarboxylic acid 2,3: 6,7-dianhydride, bis (1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) 1,4-phenylene, butane-1 , 2,3,4-tetracarboxylic acid dianhydride, pentane-1,2,4,5-tetracarboxylic acid dianhydride, cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride, 1, 2,3,4-Tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, octahydrobiphenylene-4a, 8b: 4b, 8a-tetracarboxylic acid dianhydride, cyclopentane-1,2 , 3,4-Tetracarboxylic acid dianhydride, Cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride, Cyclohexa-1-ene-2,3,5,6-tetracarboxylic acid dianhydride, 3-Ethylcyclohexa-1-ene-3- (1,2), 5,6-tetracarboxylic hydride, 1-methyl-3-ethylcyclohexane-3- (1,2), 5,6- Tetracarboxylic acid dianhydride, 1-methyl-3-ethylcyclohexa-1-ene-3- (1,2), 5,6-tetracarboxylic acid dianhydride, 1-ethylcyclohexane-1- (1, 2), 3,4-Tetracarboxylic acid dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-Tetracarboxylic acid dianhydride, 1,3-dipropylcyclohexane-1- (2) , 3), 3- (2,3) -Tetracarboxylic acid dianhydride, Dicyclohexyl-3,4,3', 4'-Tetracarboxylic acid dianhydride, Bicyclo [2.2.1] heptane-2, 3,5,6-Tetracarboxylic acid dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-Tetracarboxylic acid dianhydride, 1,3-dipropylcyclohexane-1- (2,3) 3), 3- (2,3) -Tetracarboxylic acid dianhydride, bicyclo [2.2.2] octa N-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo [2.2.2] octo-7-en-2,3,5,6-tetracarboxylic acid dianhydride, octahydro-3H, 3''H-dispyro [4,7-methanoisobenzofuran-5,1'-cyclopentane-3', 5''-[4,7] methanoisobenzofuran] -1,1'', 2', 3 , 3 ″ (4H, 4 ″ H) -pentaone, 3- (carboxymethyl) -1,2,4-cyclopentanetricarboxylic acid 1,4: 2,3-dianhydride, 5- (2,5) -Dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, 4- (2,5-dioxotetrahydrofuryl) -1,2,3,4-tetrahydronaphthalene Among these, -1,2-dicarboxylic acid anhydride and the like can be mentioned. From the viewpoint of transparency of the polyimide compound, cyclobutane-1,2,3,4-tetracarboxylic acid dianhydride and cyclopentane-1,2. , 3,4-Tetracarboxylic acid dianhydride, Cyclohexane-1,2,4,5-Tetracarboxylic acid dianhydride, 4,4'-(2,2-hexafluoroisopropylidene) diphthalic acid dianhydride, Octahydro-3H, 3 ″ H-dispyro [4,7-methanoisobenzofuran-5,1'-cyclopentane-3', 5''-[4,7] methanoisobenzofuran] -1,1'', 2′,3,3″(4H,4″H)-pentaone is preferred.

[Method for producing cured product]
The method for producing the cured product is a step of blending a resin composition containing a polyimide synthesized from the diamine and an acid anhydride, a resin composition containing a polyimide precursor (so-called polyamide resin), and the resin composition on a substrate. And a step of removing a volatile component such as a solvent by heat treatment, or a step of subjecting a polyimide precursor to a ring-closing reaction to imidize to form a cured film.

From the viewpoint of transparency, the content of the polyimide in the cured product is preferably 60% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more.

The cured product has a yellow index at a thickness of 15 μm, preferably 3.5 or less, more preferably 2 or less, and a light transmittance at a wavelength of 400 nm, preferably 75% or more, more preferably 80% or more. is there.
By setting the yellow index of the cured product and the light transmittance at a wavelength of 400 nm in such a numerical range, the colorless transparency of the cured product can be improved.

The yellow index of the cured product can be measured according to ASTM E313-73, and the light transmittance of the cured product at a wavelength of 400 nm is measured by a spectrophotometer (Konica Minolta, CM-5, transmission measurement mode, The light transmittance of the cured product is measured with the light source D65 and the measurement region of 360 nm to 730 nm (every 10 nm), and the light transmittance of 400 nm is obtained.

The resin composition may contain a solvent such as N-methylpyrrolidone, N,N′-dimethylformamide, N,N′-dimethylacetamide, or γ-butyrolactone as long as the characteristics of the present invention are not impaired. Including additives such as photoacid generators, photosensitizers such as photopolymerization initiators and photobase generators, sensitizers, adhesives, surfactants, leveling agents, colorants, fibers, plasticizers and fine particles. You may.

The method for applying the resin composition onto the substrate is not particularly limited, and examples thereof include a method of applying using a spin coater, a bar coater, a blade coater, a curtain coater, a screen printing machine, and the like, and a method of spray applying with a spray coater. , And the inkjet method.

As a method for heating the coating film, methods such as air drying, heating drying using an oven or a hot plate, and vacuum drying are used.

As the substrate, glass, ceramic, silicon wafer, metal, polyimide, polyethylene terephthalate, polyethylene naphthalate (PEN), paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth/nonwoven cloth epoxy, glass cloth/paper Examples thereof include substrates and films made of epoxy, synthetic fiber epoxy, fluororesin/polyethylene/polyphenylene ether, polyphenylene oxide/cyanate, etc., and wiring boards in which circuits are formed on these substrates and films by copper or the like.

[Neutralized salt of diamine compound]
The neutralized salt of the diamine compound according to the present invention is represented by the following general formula (2). This diamine compound neutralizing salt can be used in the above-described method for purifying a diamine compound, and by using this diamine compound neutralizing salt, a high-purity diamine can be obtained.

In the above formula (2), any one of R ₁ to R ₄ is an aromatic group having 6 to 10 carbon atoms, a phenoxy group having 6 to 10 carbon atoms, a benzyl group having 6 to 10 carbon atoms, or a carbon atom having 6 to 10 carbon atoms. Selected from the benzyloxy groups, and R ₁ to R ₄ other than the above are hydrogen atoms.
The aromatic group having 6 to 10 carbon atoms, the phenoxy group having 6 to 10 carbon atoms, the benzyl group having 6 to 10 carbon atoms and the benzyloxy group having 6 to 10 carbon atoms are as described in the above general formula (1). Therefore, the description is omitted here.

In the above general formula (2), X is selected from hydrochloric acid, sulfuric acid, sulfonic acid, phosphoric acid and organic acid.
Among the above, hydrochloric acid, sulfonic acid and organic acid are preferable.
As the sulfonic acid, methanesulfonic acid and trifluoromethanesulfonic acid are preferable.
As the organic acid, trifluoroacetic acid is preferable.

[Diamine]
The diamine according to the present invention is characterized by comprising a reaction product of a neutralizing salt of a diamine compound represented by the general formula (2), a basic reagent, and a reducing agent. Oxidation in the recrystallization process is effectively suppressed by the presence of the reducing agent, and the diamine is a high-purity diamine with no coloration.

In the diamine according to the present invention, a reaction product of a diamine compound neutralizing salt, a basic reagent, and a reducing agent is filtered by the above method (filtrate), washed by the above method, and optionally dried. Includes things (cleaned items).

The diamine of the present invention includes, in addition to the diamine represented by the above general formula (1), a component derived from an acidic reagent, a component derived from a basic reagent and a component derived from a reducing agent used for preparing the diamine compound neutralized salt. It can be.
Further, the diamine of the present invention may inevitably include an oxide of the diamine represented by the general formula (1), but this oxidation reaction is effectively suppressed by the presence of a reducing agent, The presence of the oxide is extremely low.

The diamine according to the present invention is dissolved in N,N-dimethylacetamide so that the content of the diamine is 10% by mass. The diamine solution has a yellow index of 20 or less at an optical path length of 1 cm and a light of 450 nm at an optical path length of 1 cm. The transmittance is preferably 70% or more.
Further, the diamine according to the present invention is dissolved in N,N-dimethylacetamide so that the content is 40% by mass, and the diamine solution has a yellow index of 50 or less at an optical path length of 1 cm and a light transmittance of 450 nm. Is preferably 40% or more.
By using such a diamine, it becomes possible to provide a polyimide having extremely excellent colorless transparency.

The light transmittance at 450 nm is measured as follows.
First, the light transmission spectrum of N,N-dimethylacetamide was measured with a spectrophotometer (manufactured by Konica Minolta, CM-5, liquid measurement mode, light source D65, measurement region 360 nm to 730 nm (10 nm intervals)), and 450 nm. Calculate the light transmittance of.
Next, the light transmission spectrum of the diamine solution prepared by dissolving diamine in N,N-dimethylacetamide is measured to determine the light transmittance at 450 nm.
The transmittance of light at 450 nm is measured by substituting the integrated value of the light transmittance spectrum of N, N-dimethylacetamide and the integrated value of the light transmittance spectrum of the diamine solution obtained as described above into the following equations. can do.
450 nm light transmittance=450 nm light transmittance of diamine solution-(100-N,N-dimethylacetamide 450 nm light transmittance)
In addition, the yellow index can be measured by complying with ASTM E313-73.

[Basic reagent]
Examples of the basic reagent include sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide (TMAH), sodium methoxide, sodium ethoxide, potassium-tert-butoxide, triethylamine, pyrimidine, and diazabicycloundecene (DBU). ), Potassium carbonate, sodium carbonate, cesium carbonate, potassium hydrogen carbonate, sodium hydrogen carbonate and the like can be used.
Among the above, sodium hydroxide, sodium methoxide, sodium ethoxide, sodium carbonate and sodium hydrogen carbonate are preferable.

[Reducing agent]
The reducing agent preferably has an ionization potential of 0 eV or more and 4.86 eV or less. By setting the ionization potential of the reducing agent within the above numerical range, the oxidation of the diamine compound can be effectively suppressed.
Examples of the reducing agent include aniline, triphenylphosphine, triphenyl phosphate, triphenyl phosphite, potassium sulfide, sodium sulfide, sodium sulfite, potassium sulfite, sodium hypophosphite, sodium disulfite, and borohydride. Sodium or the like can be used.

[Polyimide]
The polyimide according to the present invention comprises the above diamine. Specifically, it is a reaction product of the above-mentioned diamine and an acid anhydride.
The diamine used for producing the polyimide according to the present invention has an extremely small content of an oxide that causes coloring, and thus the polyimide has excellent colorless transparency.

It is preferable that the yellow index of the film composed of polyimide according to the present invention is 3.5 or less, and the light transmittance at 400 nm is 80% or more. Thereby, it can be suitably used as a substitute polyimide film for a cover glass included in an organic EL display device.
The content of polyimide in the film used for the measurement is 30% by mass or more and 100% by mass or less, and the thickness of the film is 15 μm.
The light transmittance of the film at 400 nm can be measured using a spectrophotometer (manufactured by Konica Minolta, CM-5, transmission measurement mode, light source D65, measurement region 360 nm to 730 nm (every 10 nm)).
The yellow index of the film can be measured according to ASTM E313-73.

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

<Example 1>
Diamine compound (crude diamine) before purification of diamine represented by the following chemical formula (A) (manufactured by Nippon Pure Chemicals Co., Ltd., ionization potential 4.96 eV) 7 g (23 mmol) and 12 mol/L hydrochloric acid 4 mL (48 mmol), It was added to a solvent containing 50 mL of acetone and 300 mL of water to prepare a solution A in which a diamine compound hydrochloride represented by the following chemical formula (B) was dissolved.

The solution A prepared as described above was supplied to a separating funnel together with 100 mL of isopropyl acetate as an extraction solvent, and a liquid separating operation was performed.

After standing, the extraction solvent was discarded, and in solution A, aniline (reducing agent, ionization potential 4.67 eV) 0.2 mL (2.3 mmol) and 10 mol/L sodium hydroxide aqueous solution 4.8 mL (basic reagent 48 mmol) was added to obtain a diamine, which is a reaction product (weak base liberation reaction) of the neutralizing salt of the diamine compound represented by the chemical formula (B), the basic reagent, and the reducing agent.

The precipitated diamine was suction-filtered and then washed with methanol. After washing, the diamine was dried under reduced pressure (10 ⁻² Torr) at 50° C. for 16 hours to obtain a purified diamine.

<Example 2>
A purified diamine was obtained in the same manner as in Example 1 except that the reducing agent was changed from aniline to sodium sulfite.

<Example 3>
A purified diamine was obtained in the same manner as in Example 1 except that the extraction solvent was changed from isopropyl acetate to chloroform.

<Comparative Example 1>
A diamine compound was obtained in the same manner as in Example 1 except that a reducing agent was not used.

<Comparative example 2>
Without performing the purification step of Example 1, a diamine compound (crude diamine) before purification of the diamine represented by the chemical formula (A) was prepared.

<<Transparency Evaluation of Polyimide>>
(Synthesis of polyimide precursor)
A stirrer chip and 8 g of N-methylpyrrolidone were placed in a 50 mL screw vial, 1.11 g (4.06 mmol) of the purified diamine obtained in Example 1 above, and cyclobutane-1,2, represented by the following chemical formula (C). 0.796 (4.06 mmol) of 3,4-tetracarboxylic dianhydride (CBDA) was added, the mixture was sealed with nitrogen, and stirring was continued at room temperature for 16 hours to obtain a varnish of polyimide precursor A.

The obtained varnish of polyimide precursor A was applied on a silicon substrate with a spin coater, and dried by heating with a hot plate at 120° C. for 10 minutes. Then, it was heated and dried at 250° C. for 1 hour under a nitrogen stream in an inert gas oven to form a polyimide (cured film) of the resin composition having a thickness of 15 μm. This polyimide was peeled off from the silicon substrate and cut to obtain a test piece of 100 mm length×100 mm width×15 μm thickness.
The light transmittance of the test piece at a wavelength of 400 nm was measured with a spectrophotometer (manufactured by Konica Minolta, CM-5, transmission measurement mode, light source D65, measurement area 360 nm to 730 nm (10 nm intervals)). The light transmittance of 400 nm was measured and measured, and evaluated according to the following evaluation criteria.
The light transmittance of the test piece at a wavelength of 400 nm was measured and evaluated in the same manner except that the diamine used for preparing the varnish was changed to the diamine in Examples 2 and 3 and Comparative Examples 1 and 2.
The results of these evaluations are summarized in Table 1.
(Evaluation criteria)
⊚: The transmittance was 80% or more.
◯: The transmittance was 75% or more and less than 80%.
X: The transmittance was less than 75%.

The yellow index of the polyimide (cured film) using the diamine of each of the above Examples and the diamine compound of each Comparative Example was measured according to ASTM E313-73 and evaluated according to the following evaluation criteria. The results of these evaluations are summarized in Table 1.
(Evaluation criteria)
⊚: The yellow index was 2 or less.
◯: The yellow index was more than 2 and 3.5 or less.
X: The yellow index was over 3.5.

As is clear from the evaluation results shown in the above table, the cured product produced by using the polyimide synthesized using the diamine that has undergone the purification step in Examples 1 to 3 has high transparency. all right.

<< Measurement of light transmittance of diamine solution at 450 nm >>
The content of the purified diamine, which is a reaction product of the diamine compound neutralizing salt, the basic reagent, and the reducing agent obtained in Example 1 above, is 10% by mass or 20% by mass in N, N-dimethylacetamide. , 30% by mass, and 40% by mass, respectively, to prepare purified diamine solutions A to D, respectively.
Further, the above-mentioned unpurified diamine (manufactured by Nippon Pure Chemical Industries, Ltd.) was dissolved in N, N-dimethylacetamide so that the contents were 10% by mass, 20% by mass, 30% by mass, and 40% by mass, respectively. Purified diamine solutions a to d were prepared.

The light transmission spectra (at an optical path length of 1 cm) of the purified diamine solutions A to D and the unpurified diamine solutions a to d prepared as described above were measured by a spectrophotometer (manufactured by Konica Minolta, CM-5, liquid). Measurement was performed using the measurement mode, the light source D65, and the measurement region of 360 nm to 730 nm (every 10 nm), and the integrated value was obtained.
Next, the integrated value of the light transmittance spectrum of N, N-dimethylacetamide was also obtained, and by substituting into the following equation, the light transmittance at 450 nm at an optical path length of 1 cm was obtained and summarized in Table 2.

<< Measurement of yellow index of diamine solution >>
The yellow indexes (at an optical path length of 1 cm) of the purified diamine solutions A to D and the unpurified diamine solutions a to d were measured according to ASTM E313-73, and are summarized in Table 2.

Claims

The process of using a diamine compound as a neutralizing salt and dissolving it in a solvent,
A solvent in which the neutralized salt of the diamine compound is dissolved, and an extraction solvent are supplied to a separation tank, and these are brought into a phase separation state, and the diamine contained in the solvent in which the neutralized salt of the diamine compound is dissolved. A step of extracting impurities derived from a compound into the extraction solvent,
A neutralized salt of a diamine compound dissolved in the solvent, a weak base release reaction in the presence of a reducing agent, to obtain a diamine,
A method for purifying a diamine compound, which comprises.
The method for purifying a diamine compound according to claim 1, wherein the highest occupied molecular orbital level of the reducing agent is 0.1 eV or more higher than the highest occupied molecular orbital level of the diamine compound.
The method for purifying a diamine compound according to claim 1 or 2, wherein the amount of the reducing agent used is 1 mol% or more and 20 mol% or less with respect to 100 mol% of the diamine compound.
The method for purifying a diamine compound according to any one of claims 1 to 3, wherein the diamine in the diamine compound is represented by the following general formula (1).

(In the above formula (1),
Any one of R1 to R4 is selected from an aromatic group having 6 to 10 carbon atoms, a phenoxy group having 6 to 10 carbon atoms, a benzyl group having 6 to 10 carbon atoms and a benzyloxy group having 6 to 10 carbon atoms, R1 to R4 other than are hydrogen atoms. )
A diamine compound neutralized salt, which is represented by the following general formula (2).

(In the above formula (2),
Any of R1 to R4 is selected from an aromatic group having 6 to 10 carbon atoms, a phenoxy group having 6 to 10 carbon atoms, a benzyl group having 6 to 10 carbon atoms, and a benzyloxy group having 6 to 10 carbon atoms.
The other R1 to R4 are hydrogen atoms,
X is selected from hydrochloric acid, sulfuric acid, sulfonic acid, phosphoric acid and organic acid. )
A diamine comprising a reaction product of a diamine compound neutralizing salt represented by the above general formula (2), a basic reagent, and a reducing agent.
The diamine according to claim 6, wherein the ionization potential of the reducing agent is 0 eV or more and 4.86 eV or less.
The reducing agent is selected from aniline, triphenylphosphine, triphenyl phosphate, triphenyl phosphite, potassium sulfide, sodium sulfide, sodium sulfite, potassium sulfite, sodium hypophosphite, sodium disulfite, and sodium borohydride. The diamine according to claim 5 or 6, which is one or more reducing agents selected from the group.
A polyimide comprising the diamine according to any one of claims 6 to 8.