KR20190060811A - A method for producing a polyimide-based polymer varnish, a method for producing a polyimide-based polymer film, and a transparent polyimide-based polymer film - Google Patents

Abstract

A method for producing a polyimide-based polymer varnish comprises a step of polymerizing a raw material monomer of a polyimide-based polymer in a solvent to obtain a polyimide-based polymer precursor, and a step of polymerizing the polyimide-based polymer precursor in a solvent containing a tertiary amine And imidizing the imide-based polymer precursor to obtain a solution of the polyimide-based polymer.

Description

A method for producing a polyimide-based polymer varnish, a method for producing a polyimide-based polymer film, and a transparent polyimide-based polymer film

The present invention relates to a process for producing a polyimide-based polymer varnish, a process for producing a polyimide-based polymer film, and a transparent polyimide-based polymer film.

Conventionally, there is known a process for producing a polyimide solution in which a polyimide solution is obtained by polymerizing and imidizing a raw monomer of a polyimide in a solvent under a nitrogen gas stream. In such a reaction system, when the raw material monomers of the polyimide are mixed in the solvent, the starting monomer is polymerized to form the polyamic acid, and further, by heating the polyamic acid, the imidization of the polyamic acid proceeds to form the polyimide. At this time, it is known to add a tertiary amine compound as a catalyst promoting imidization.

Japanese Patent Application Laid-Open No. 2000-080272

However, when the catalyst-containing polyimide solution obtained by polymerization and imidization is directly molded into a film, it is difficult to obtain a film having good folding resistance. It is also known to perform purification by the alcohol precipitation method or the like before the film forming process. However, since the purification process is costly, the process including the purification process tends to be disadvantageous in terms of cost.

It is also required to maintain high transparency of the polyimide-based polymer at the time of mass production.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a process for producing a polyimide-based polymer varnish capable of imparting high bendability to a film without going through a purification step.

Another object of the present invention is to provide a process for producing a polyimide-based polymer varnish suitable for mass production of a polyimide-based polymer having high transparency.

A process for producing a polyimide-based polymer varnish according to the present invention comprises a polymerization step of polymerizing a raw monomer of a polyimide-based polymer in a solvent to obtain a polyimide-based polymer precursor, and a step of polymerizing And imidizing the polyimide-based polymer precursor in a solvent to obtain a solution of the polyimide-based polymer.

Here, the temperature of the imidation step may be 100 deg. C or higher and 250 deg. C or lower.

In addition, the tertiary amine may have a boiling point of 120 ° C or higher and 350 ° C or lower.

In addition, the polyimide-based polymer may contain 20 mass% or more of fluorine.

Also, the pressure of the reduced-pressure environment may be 350 mmHg or more and 730 mmHg or less, and the pressure of the reduced-pressure environment may be 500 mmHg or more and 730 mmHg or less.

In the imidation step, the concentration of oxygen in the gaseous phase in contact with the solvent may be 0.02% or less.

In addition, from 0.05 part by mass to 0.7 part by mass of the tertiary amine may be added to 100 parts by mass of the raw material monomer.

The method may further comprise the step of adding an ultraviolet absorber to the obtained solution of the polyimide-based polymer. The method may further comprise the step of adding silica sol to the obtained solution of the polyimide-based polymer.

The method for producing a polyimide-based polymer film according to the present invention comprises the steps of: (1) conducting the above-described method for producing a polyimide-based polymer varnish; (2) subjecting the obtained polyimide-based polymer varnish to precipitation and re- And a film forming step of forming the polyimide-based polymer varnish in a flexible manner without causing the polyimide-based polymer varnish.

The film relating to the present invention includes a polyimide-based polymer having a weight average molecular weight of 50,000 or more and 500,000 or less and a tertiary amine of 0.01% by mass or more and 0.25% by mass or less based on the total mass of the film.

The tertiary amine may have a boiling point of 120 ° C or higher and 350 ° C or lower.

Another method for producing a polyimide-based polymer varnish according to the present invention is a method for producing a polyimide-

(1) a step of reacting a monomer raw material in a solvent A in a reaction vessel to obtain a solution of a polyimide-based polymer,

(3) removing the solution from the reaction vessel,

(4) a step of washing the reaction vessel with the solvent C, and then removing the solvent C after the washing from the reaction vessel, wherein the steps (1), (3) and (4) And repeats this sequence. The polyimide-based polymer obtained in the step (1) is transparent and has a weight average molecular weight of 250,000 or more.

According to the present invention, it is possible to reduce the amount of the polymer produced in the previous step (1) remaining in the reaction vessel in the second and subsequent steps (1) by having a cleaning step. Therefore, deterioration of the transparency of the polyimide-based polymer synthesized in the second and subsequent steps (1) can be suppressed.

Here, the above-

(5) After the step (4), the step of washing the reaction vessel with the solvent D and taking out the solvent D from the reaction vessel after the step (4)

The above steps (1), (3), (4) and (5) can be repeated in this order using the same reaction vessel.

According to this, it is possible to further reduce the amount of the polymer remaining in the reaction vessel.

The method may further comprise, between the step (1) and the step (3)

(2) adding a solvent B to the reaction vessel to dilute the solution obtained in the step (1)

The above steps (1) to (4) or the above steps (1) to (5) may be repeated using the same reaction vessel.

According to this, since the concentration of the polyimide-based polymer in the reaction vessel before the solution is extracted is lowered, the residual amount of the polymer in the reaction vessel after the extraction can be further reduced.

Further, the solvent B may be the solvent C taken out of the reaction vessel in the step (4).

According to this, since the polymer recovered in the solvent B becomes a part of the polyimide-based polymer in the varnish produced in the next batch, the yield is improved.

According to the present invention, there is provided a method for producing a polyimide varnish, which can impart high bendability to a film even if the polyimide-based polymer is directly film-formed without going through a purification step.

According to the present invention, there is also provided a process for producing a polyimide-based polymer varnish suitable for mass production of a polyimide-based resin having high transparency.

A method for producing a polyimide-based polymer varnish according to an embodiment of the present invention will be described. This method comprises a polymerization step of polymerizing a raw material monomer of a polyimide-based polymer in a solvent to obtain a polyimide-based polymer precursor, and a step of polymerizing the polyimide-based polymer precursor in a solvent containing a tertiary amine under a reduced- And imidizing the polyimide-based polymer solution to obtain a polyimide-based polymer solution.

(Raw material monomer of polyimide-based polymer)

The raw material monomer includes a tetracarboxylic acid compound and a diamine.

(Tetracarboxylic acid compound)

Examples of the tetracarboxylic acid compound are an aromatic tetracarboxylic acid compound such as aromatic tetracarboxylic dianhydride and an aliphatic tetracarboxylic acid compound such as aliphatic tetracarboxylic dianhydride. The tetracarboxylic acid compound may be used alone or in combination of two or more. The tetracarboxylic acid compound may be a tetracarboxylic acid compound derivative such as tetracarboxylic acid chloride compound in addition to tetracarboxylic acid dianhydride.

Specific examples of the aromatic tetracarboxylic acid dianhydrides include non-condensed polycyclic aromatic tetracarboxylic dianhydrides, monocyclic aromatic tetracarboxylic dianhydrides, and condensed polycyclic aromatic tetracarboxylic dianhydrides.

Examples of the non-condensed polycyclic aromatic tetracarboxylic acid dianhydride include 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3 '- benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 3,3' Bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, , 4,4'- (hexafluoroisopropylidene) diphthalic acid dianhydride (sometimes referred to as 6FDA), 1, 2'-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, Bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2- (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 1,1- Dianhydride, 4,4 '- (p- phenylenedimaleimide oxy) diphthalic dianhydride, 4,4' - there may be mentioned (m- phenylenedimaleimide oxy) diphthalic acid dianhydride.

Examples of the condensed polycyclic aromatic tetracarboxylic acid dianhydride include 2,3,6,7-naphthalenetetracarboxylic dianhydride.

As the aromatic tetracarboxylic acid dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic dianhydride, 2,2', 3,3'- Benzophenone tetracarboxylic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 3,3 ', 4 (2,3-dicarboxyphenyl) propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2- , 2-bis (3,4-dicarboxyphenoxyphenyl) propane dianhydride, 4,4 '- (hexafluoroisopropylidene) diphthalic dianhydride, 1,2- Bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,2-bis (3,4-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, 4,4 '- (p- Deoxidized dianhydride and 4,4 '- (m-phenylenedioxy) diphthalic dianhydride. These may be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic acid dianhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydrides. The cyclic aliphatic tetracarboxylic acid dianhydride is tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples thereof include 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4- Cycloalkane tetracarboxylic dianhydride such as cyclobutane tetracarboxylic dianhydride and 1,2,3,4-cyclopentanetetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3, 5,6-tetracarboxylic dianhydride, dicyclohexyl 3,3'-4,4'-tetracarboxylic dianhydride, and their positional isomers. These may be used alone or in combination of two or more. Specific examples of the non-cyclic aliphatic tetracarboxylic acid dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-pentanetetracarboxylic dianhydride and the like, Or a combination of two or more.

From the viewpoints of transparency and inhibition of coloring of the film, the tetracarboxylic acid compound is preferably the alicyclic tetracarboxylic acid dianhydride or the non-condensed polycyclic aromatic tetracarboxylic dianhydride. More specific examples include 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis (3,4 -Dicarboxyphenyl) propane dianhydride, and 4,4 '- (hexafluoroisopropylidene) diphthalic dianhydride (6FDA). These may be used alone or in combination of two or more.

(Tricarboxylic acid compound and dicarboxylic acid compound)

The raw material monomer may further include a tricarboxylic acid compound and / or a dicarboxylic acid compound.

Examples of the tricarboxylic acid compound include aromatic tricarboxylic acids, aliphatic tricarboxylic acids, and their flexible acid chloride compounds and acid anhydrides, and they may be used in combination of two or more.

Specific examples thereof include anhydrides of 1,2,4-benzenetricarboxylic acid; 2,3,6-naphthalenetricarboxylic acid-2,3-anhydride; Compounds in which phthalic anhydride and benzoic acid are linked by a single bond, -CH ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -SO ₂ - or phenylene group.

Examples of the dicarboxylic acid compound include aromatic dicarboxylic acids, aliphatic dicarboxylic acids and their flexible acid chloride compounds and acid anhydrides, and two or more of them may be used in combination. Specific examples include terephthalic acid; Isophthalic acid; Naphthalene dicarboxylic acid; 4,4'-biphenyldicarboxylic acid; 3,3'-biphenyldicarboxylic acid; A dicarboxylic acid compound of a cyclic hydrocarbon having 8 or less carbon atoms and a compound in which two benzoic acids are linked by -CH ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -SO ₂ - .

The ratio of the tetracarboxylic acid compound to the total of the tetracarboxylic acid compound, the tricarboxylic acid compound and the dicarboxylic acid compound is preferably 40 mol% or more, more preferably 50 mol% or more, Is at least 70 mol%, more preferably at least 90 mol%, particularly preferably at least 98 mol%.

(Diamine)

Examples of diamines are aliphatic diamines, aromatic diamines or mixtures thereof. In the present embodiment, the term "aromatic diamine" refers to a diamine in which an amino group is directly bonded to an aromatic ring, and a part of the structure may contain an aliphatic group or other substituent. The aromatic ring may be a monocyclic ring or a condensed ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring and a fluorene ring, but are not limited thereto. Of these, benzene rings are preferred. The term "aliphatic diamine" refers to a diamine in which an amino group is bonded directly to an aliphatic group, and a part of the structure may contain an aromatic ring or other substituent.

Examples of the aliphatic diamines include alicyclic diamines such as hexamethylene diamine and the like; aliphatic diamines such as 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, '-Diaminodicyclohexylmethane and the like, and they may be used alone or in combination of two or more.

Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,6 Diaminodiphenyl ether, aromatic diamine having one aromatic ring, such as 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3 , 4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diamino Bis (4-aminophenoxy) benzene, 4,4'-diaminodiphenylsulfone, bis [4- (4- Bis (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2- (3-aminophenoxy) phenyl] propane, 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) -4,4'- diaminodiphenyl (sometimes referred to as TFMB) 4 , 4'-bis (4-aminophenoxy) biphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, (4-aminophenyl) fluorene, 9,9-bis (4-amino-3-methylphenyl) fluorene, 9,9- -Bis (4-amino-3-fluorophenyl) fluorene, or an aromatic diamine having two or more aromatic rings. These may be used alone or in combination of two or more.

The diamine may have a fluorine-based substituent. Examples of the fluorine-based substituent include a perfluoroalkyl group having 1 to 5 carbon atoms such as a trifluoromethyl group, and a fluoro group.

Among these diamines, from the viewpoint of high transparency and low coloring property, it is preferable to use at least one selected from the group consisting of aromatic diamines having a biphenyl structure. At least one selected from the group consisting of 2,2'-dimethylbenzidine, 2,2'-bis (trifluoromethyl) benzidine (TFMB) and 4,4'-bis (4-aminophenoxy) It is more preferable to use it.

The diamine is preferably a diamine having a biphenyl structure and a fluorine-based substituent, and an example thereof is 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB).

The molar ratio of the diamine in the raw material monomer to the carboxylic acid compound such as the tetracarboxylic acid compound can be appropriately controlled within a range of from 0.9 mol or more to 1.1 mol or less of the tetracarboxylic acid with respect to 1.00 mol of the diamine. From the viewpoint of exhibiting high yielding properties, it is preferable that the polyimide-based polymer to be obtained has a high molecular weight, more preferably from 0.98 to 1.02 mol of tetracarboxylic acid with respect to 1.00 mol of diamine, more preferably from 0.99 mol% to 1.01 mol% desirable.

From the viewpoint of suppressing the yellowing degree of the obtained polyimide-based polymer film, it is preferable that the ratio of the amino group occupied to the terminal of the obtained polymer is low, and the ratio of the carboxylic acid compound such as tetracarboxylic acid compound to 1.00 mol of the diamine is 1.00 mol or more desirable.

The fluorine number in the molecule of the diamine and the carboxylic acid compound (for example, the tetracarboxylic acid compound) is adjusted so that the amount of fluorine in the obtained polyimide-based polymer is 1% by mass or more, 5% by mass or more, 10% by mass or more, and 20% by mass or more. The higher the proportion of fluorine, the higher the cost of the raw material. Therefore, the upper limit of the fluorine content is preferably 40% by mass or less. The fluorine-based substituent may be present either in the diamine or in the carboxylic acid compound, or may be present in both of them. The inclusion of a fluorine-based substituent may reduce the YI value in particular.

(Solvent A)

The solvent A used for the synthesis of the polyimide-based polymer (polymerization and imidization of the raw material monomer) is preferably a solvent capable of dissolving the polyimide-based polymer precursor produced by polymerization and the polyimide-based polymer produced by imidization Do. Examples of such solvents include lactone solvents, amide solvents, and sulfur solvents. Specific examples thereof include? -Butyrolactone (boiling point: 204 占 폚) (sometimes referred to as GBL), N, N-dimethylformamide (Boiling point: 153 占 폚), N, N-dimethylacetamide (boiling point: 165 占 폚) (sometimes referred to as DMAc), dimethylsulfoxide (boiling point: 189 占 폚) The solvent may be a mixture.

In the synthesis of the polyimide, when the imidization reaction described later is carried out at a high temperature, the solvent A is preferably a solvent having a high boiling point. The boiling point is preferably 160 DEG C or higher, more preferably 180 DEG C or higher. Examples of such solvent A are GBL, DMAc and dimethylsulfoxide.

(Tertiary amine)

The tertiary amine can function as a polyimide-based polymer precursor imidization catalyst in a solvent.

Examples of tertiary amines include tertiary amines (hereinafter also referred to as tertiary amines A), tertiary amines (hereinafter also referred to as tertiary amines B) represented by the formula (b) (Hereinafter, also referred to as a tertiary amine C) and a tertiary amine (hereinafter also referred to as a tertiary amine D) represented by the formula (d).

[Chemical Formula 1]

In formula (a), R _1A , R _2A and R _3A are each a monovalent hydrocarbon group of 1 to 12 carbon atoms, and the total number of carbon atoms of R _1A , R _2A and R _3A is 10 or more and 18 or less.

Specific examples of the tertiary amine A include tripropylamine, dibutylpropylamine and ethyldibutylamine.

(2)

In formula (b), R _1B is a monovalent hydrocarbon group having 2 to 10 carbon atoms, R _2B is a divalent aliphatic hydrocarbon group having 3 to 12 carbon atoms, and the total number of carbon atoms of R _1B and R _2B is 9 to 16 to be.

Specific examples of the tertiary amine B include N-ethylpiperidine, N-propylpiperidine, N-butylpyrrolidine, N-butylpiperidine and N-propylhexahydroazepine.

(3)

In the formula (c), R _1C is a trivalent aliphatic hydrocarbon group having 7 to 15 carbon atoms.

Specific examples of the tertiary amine C include azabicyclo [2.2.1] heptane, azabicyclo [3.2.1] octane, azabicyclo [2.2.2] octane and azabicyclo [3.2.2] nonane.

[Chemical Formula 4]

In the formula (d), R _1D is a trivalent aliphatic hydrocarbon group having 8 to 15 carbon atoms.

Specific examples of the tertiary amine D include 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, -Trimethylpyridine, 3,4-cyclopentenopyridine, 5,6,7,8-tetrahydroisoquinoline, and isoquinoline.

If the boiling point of the tertiary amine to be used is high, the amount of the catalyst which is excluded from the system (system) tends to be suppressed in distilling off the water under reduced pressure, which is preferable. A tertiary amine having a boiling point of 120 ° C or higher is preferable, a tertiary amine having a boiling point of 140 ° C or higher is more preferable, a tertiary amine having a boiling point of 170 ° C or higher is more preferable, and a tertiary amine having a boiling point of 200 ° C or higher is more preferable Do. The upper limit of the boiling point of the tertiary amine to be used is not specifically defined, but is usually 350 DEG C or lower. In the case of using a tertiary amine having a low boiling point, it is necessary to increase the amount of the catalyst to be used in consideration of distillation removal components.

The tertiary amine is preferably tertiary amine D, more preferably tertiary amine D having 6 to 13 carbon atoms. More preferably a tertiary amine D having 9 to 13 carbon atoms, and still more preferably isoquinoline and a hydride thereof.

(Production method of polyimide-based polymer varnish)

This method comprises a polymerization step of polymerizing a raw material monomer of a polyimide-based polymer in a solvent to obtain a polyimide-based polymer precursor, and a step of polymerizing the polyimide-based polymer precursor in a solvent containing a tertiary amine under a reduced- Imidization process in which imidization is carried out to obtain a polyimide-based polymer solution.

Further, in the present embodiment, the polyimide-based polymer varnish is a solution obtained by imidizing a polyimide-based polymer precursor and a solution and a solvent or an additive added to the polyimide-based polymer solution .

(Production of polyimide-based polymer precursor by polymerization of raw material monomer)

In the reaction vessel, the raw monomer of the polyimide-based polymer is polymerized in the solvent A described above. The amount of the raw material monomers in the total liquid including the raw material monomer and the solvent A may be 10 to 60% by mass. If the amount of the monomer is large, the polymerization rate tends to increase and the molecular weight can be increased. Further, the polymerization time can be shortened and the coloring of the polyimide-based polymer tends to be suppressed. If the amount of the monomer is excessively large, the viscosity of the solution containing the polymerized substance or the polymerized substance tends to be high, so that the stirring may become difficult or the polymerized substance may adhere to the reaction vessel or stirring vane, resulting in a low yield.

The order of the components of the raw material monomer and the order of mixing of the solvent A is not particularly limited and they may be all mixed at the same time or may be mixed with each other. However, it is also possible to add a carboxylic acid compound after mixing at least a part of the diamine with a solvent . The diamine and the carboxylic acid compound may be added in a divided manner or may be added stepwise for each compound.

The raw material monomer is stirred well in the reaction mass to promote the polymerization of the raw material monomer to form a polyimide-based polymer precursor. If necessary, the reaction mass may be heated to about 40 to 90 占 폚. The imidization step described later may be carried out simultaneously with the progress of the polymerization step of the raw material monomer. In this case, the reaction mass may be further heated at a high temperature in accordance with the imidation condition described later.

The reaction time of the polymerization may be, for example, 24 hours or less, and may be 1 hour or less, or 1 to 24 hours.

The reaction mass may contain a tertiary amine during the polymerization of the polyimide-based polymer precursor. In this case, the tertiary amine may be added before or after the mixing of the diamine and the solvent, or may be added after mixing the diamine, the solvent and the carboxylic acid compound. It may also be added to the reaction mass after being diluted with a part of the solvent used.

(Imidization of polyimide-based polymer precursor)

Subsequently, the reaction mass containing the tertiary amine is heated in a reduced pressure environment to promote the imidization of the polyimide-based polymer precursor, thereby distilling off water or the like as a by-product while producing the polyimide. It is preferable to imidize the polyimide-based polymer precursor in the solvent A in the reaction vessel subjected to the above polymerization. The tertiary amine may be added during or during the polymerization process for producing the polyimide-based polymer precursor by polymerizing the raw material monomer as described above, but may be added after the step for producing the polyimide-based polymer precursor .

The formation reaction and the imidization reaction of the polyimide-based polymer precursor may be carried out simultaneously. In this case, the amide group bond is cleaved by the water generated by the imidization reaction, and the molecular weight of the resulting polyimide-based polymer may be lowered. A film obtained from a varnish containing such a polyimide-based polymer may be degraded in endurance. During the imidation step, the decomposition reaction is carried out to remove water in the reaction solution at a rapid rate, whereby the cleavage reaction of the amide group can be suppressed and the molecular weight of the resulting polyimide-based polymer can be increased. Therefore, in particular, in the case where the formation reaction of the polyimide-based polymer precursor and the imidization reaction are simultaneously proceeded, the imidization step is performed under a reduced pressure environment to produce a film directly from the varnish containing the polyimide-based polymer There is a tendency that a high bendability can be imparted to the film.

The amount of tertiary amine added to 100 mass parts of the raw material monomer in the reaction mass is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, and still more preferably 0.1 parts by mass or more, 0.2 parts by mass or more. On the other hand, for the purpose of suppressing the coloring of the film, it is preferable that the addition amount of the catalyst is small. The amount of the tertiary amine to be added is preferably 2 parts by mass or less, more preferably 1 part by mass or less, still more preferably 0.7 parts by mass or less, still more preferably 0.5 parts by mass or less, 0.3 parts by mass or less.

The temperature of the imidation step is preferably from 100 캜 to 250 캜, and more preferably from 150 캜 to 210 캜. The pressure in the imidation step is preferably 730 mmHg or less, more preferably 700 mmHg or less, and still more preferably 675 mmHg or less.

The pressure of the imidation step may be, for example, 350 mmHg or more, or 500 mmHg or more. Depending on the vapor pressure of the solvent at the temperature of the imidation step, the pressure may preferably be at least 400 mmHg in order to enhance the stability of the reaction. For the same reason, it may be more preferable to perform at 600 mmHg.

If the imidation process pressure is set near the saturated vapor pressure of the solvent in the imidization process, YI tends to be suppressed. A pressure within 50 mmHg from saturated vapor pressure is preferred.

The heating time may be, for example, 1 to 24 hours. Preferably 1 to 12 hours, more preferably 2 to 9 hours, still more preferably 2 to 8 hours, still more preferably 2 to 6 hours, particularly preferably 2 to 5 hours. It is preferable to stir while heating.

When the reaction time is prolonged, the molecular weight is increased, but the yellowish taste of the resin tends to become strong. On the other hand, if the reaction time is short, the molecular weight tends to be lowered, and the yellowish color tends to weaken.

When the concentration of oxygen in the vapor phase in contact with the liquid phase (liquid phase) containing the solvent A in the reaction vessel is low in the imidation process, the coloring of the polyimide-based polymer tends to be suppressed, and the film obtained from the varnish The value of YI tends to be lowered. In the production method, the imidization step by heating the reaction mass under a reduced pressure environment is performed in a state in which the oxygen concentration in the gas phase of the reaction vessel is low, and before the heating under a reduced pressure environment, for example, Or the oxygen concentration may be low from the time when the raw material monomer or the like is added. The oxygen concentration is preferably 0.02% or less, more preferably 0.01% or less. If the oxygen concentration is high when heated to a high temperature, it may cause coloration. For example, when the temperature of the reaction solution is 130 ° C or higher, the oxygen concentration is preferably 0.02% or less. In the synthesis of the precursor and the imidization of the precursor, substantially no oxygen is generated. For example, by lowering the oxygen concentration in the gas phase by substituting the inside of the reaction vessel with nitrogen gas before the introduction of the raw material, It is possible to reduce the oxygen concentration in the gas phase in the gas phase. The oxygen concentration in the imidation process can be determined, for example, by analyzing the oxygen concentration in the gas removed from the reaction vessel when the pressure inside the reaction vessel is reduced. In the case where it is difficult to measure the oxygen concentration during the decompression, the oxygen concentration may be measured by sampling the gas phase before and after the decompression.

After heating, the mixture is returned to atmospheric pressure and cooled to obtain a polyimide-based polymer solution.

This polyimide-based polymer solution may be directly used as a polyimide-based polymer varnish.

(Dilution step)

Further, a polyimide-based polymer varnish can be obtained by further adding a solvent B to the obtained polyimide-based polymer solution and adjusting the concentration of the polyimide-based polymer. The solid content concentration in the preferable polyimide-based polymer varnish is 10 to 25 mass%.

In the case of producing a film from a polyimide-based polymer varnish, when a varnish containing 30 mass% or more of a polyimide-based polymer is used for the entire solid content in the varnish, one of the main components described below is a polyimide- Based polymer film can be easily obtained. The concentration of the polyimide-based polymer is preferably 10% by mass or more, and more preferably 13% by mass or more, based on the total mass of the varnish.

The dilution may be performed in the reaction vessel, or may be performed on the solution after recovery from the reaction vessel.

When the concentration of the polyimide-based polymer in the reaction vessel is diluted by adding the solvent B to the imidized polyimide-based polymer solvent in the reaction vessel, the amount of the polymer remaining in the reaction vessel in the next extraction step is reduced And the yield of the polymer can be improved. Further, if the amount of the polymer remaining in the reaction vessel is reduced, the coloration (for example, yellow color) of the obtained polyimide-based polymer is improved in a subsequent step of polymerization and imidization using this reaction vessel.

The solvent B for dilution may be the solvent A described above. The solvent B and the solvent A may be the same or different from each other. By appropriately selecting a solvent having high solubility for the polyimide resin as the diluting solvent B, the recovery rate of the polyimide-based polymer from the reaction vessel is increased. As such a solvent, N, N-dimethylacetamide, cyclopentanone (boiling point 131 ° C) and the like can be given.

Dilution in the reaction vessel may be performed several times by using a plurality of different kinds of solvents B. [

(Solution extraction step)

Subsequently, the polyimide-based polymer varnish is withdrawn from the reaction vessel. The varnish thus taken out can be used in a film forming process to be described later.

(Cleaning of reaction vessel with solvent C)

Subsequently, the solvent C is supplied into the reaction vessel after the extraction to dissolve the polymer remaining in the reaction vessel in the solvent C. Thereafter, the solvent C in which the polymer is dissolved is recovered from the reaction vessel to further remove the polymer remaining in the reaction vessel .

The amount of the polymer remaining in the reaction vessel can be reduced by washing the reaction vessel. In the next step of polymerization and imidization using this reaction vessel, the coloration (for example, yellow) of the obtained polyimide- .

Solvent C may be one exemplified by Solvent A and Solvent B. The solvent C may be of the same species as the solvent A and may be different from the solvent A. The solvent C may be of the same species as the solvent B and may be of a different kind from the solvent B. By employing a suitable cleaning solvent, the amount of the polymer remaining in the reaction vessel can be reduced. Examples of such a solvent include N, N-dimethylacetamide and cyclopentanone.

After the solvent C is supplied to the reaction vessel and then recovered, the solvent D may be supplied to the reaction vessel to dissolve the polymer, and then the solvent D may be recovered. The solvent D may be washed several times. The solvent D may be the same as or different from the solvent C.

(repeat)

After the cleaning, the polyimide-based polymer varnish is efficiently produced by using one reaction vessel by repeating the steps of polymerization, imidization, dilution, extraction, and washing using the washed reaction vessel again .

(Reuse of Solvent C and Solvent D)

As the solvent B used in the dilution process described above, it is preferable to use the solvent C used for washing the reaction vessel. As the solvent B, a solvent D used for cleaning may also be used. As the diluting solvent B, it is preferable to use at least the solvent C. By using a solvent C or the like containing a polymer as the diluting solvent B, the yield of the polymer can be increased.

Here, the yield is the weight of the resin solid content in the polyimide varnish actually obtained in the subsequent extraction step, with respect to the theoretical amount (weight) of the polyimide-based polymer calculated from the amount of the raw material monomers charged in the polymerization step once. In the case where the polyimide varnish contains the solvent C after washing the reaction vessel, the weight of the resin solid content in the polyimide varnish is the sum of the resin solid content contained in the solvent C and the resin solid content in the polyimide varnish synthesized in the reaction vessel .

Particularly, in the production of a transparent polyimide-based polymer varnish having a weight average molecular weight of 250,000 or more, the obtained polymer tends to adhere to the reaction vessel, and the polymer remains in the reaction vessel after the solution is withdrawn and the yield is lowered. Adversely affects the synthesis of the polyimide in the next step, so that the yellowish color of the obtained polymer may be increased, or the foreign matter contained in the obtained polymer may be increased.

This problem can be solved by diluting the solution before extraction with the solvent B and / or cleaning the reaction vessel using the solvent C. [ There is a tendency that cleaning of the reaction vessel is further facilitated by performing cleaning using solvent D in addition to the solvent C, that is, washing several times in two or more kinds of solvents.

For example, in the case where the reaction vessel is not cleaned or the polymerization is repeatedly performed in a state where the washing is insufficient, adherence originating from the polymer remains on the wall surface of the reaction vessel and the YI value of the polyimide- have. In such a case, washing in a plurality of solvents (solvent C and solvent D) further strengthens the cleaning of the reaction vessel and suppresses an increase in the YI value.

The above-mentioned " transparent " means that the total light transmittance (Tt) of the polyimide-based polymer contained in the varnish is measured by preparing a polymer film having a thickness of 80 m according to JIS K7105: 1981 85% or more. The total light transmittance is preferably 90% or more.

The weight average molecular weight is a standard polystyrene reduced molecular weight measured by GPC.

The solvent A used for the synthesis of the polyimide and the solvent B and / or the solvent C used for dilution and washing may be the same solvent, but if different, the degree of polymerization of the reaction vessel is improved and the transparency of the obtained polymer can be improved. As preferred solvents for the solvents B and C, there are N, N-dimethylacetamide, cyclopentanone and the like as described above. These solvents have a boiling point lower than that of GBL, but the viscosity of the polyimide-based polymer varnish is lowered, so that it is advantageous for the removal from the reaction vessel. On the other hand, when the imidization reaction is carried out at a high temperature as described above, the solvent A used in the synthesis of the polyimide is preferably a solvent having a high boiling point such as GBL.

In addition, a polyimide-based polymer varnish may be prepared by adding an additive other than a solvent to the polyimide-based polymer solution. Examples of the additive include inorganic particles and ultraviolet absorbers.

(Inorganic particles)

Specific examples of the inorganic particles include silica fine particles.

The average primary particle diameter of the inorganic particles used in the present invention is usually 100 nm or less.

When the average primary particle diameter of the inorganic particles is 100 nm or less, transparency of the film tends to be improved. The primary particle size of the inorganic particles in the film can be measured by a transmission electron microscope (TEM) in a constant direction. The average primary particle size can be determined, for example, by measuring 10 points of the primary particle size by TEM observation and calculating the average value thereof.

When the inorganic particles are silica fine particles, the silica fine particles may be either silica sol dispersed silica particles in an organic solvent or the like, or silica fine particle powders prepared by the vapor phase method, but silica sol is preferable because of easy handling. The average primary particle size of the raw silica particles can be determined, for example, by BET measurement.

The addition amount of the inorganic particles can be set, for example, in accordance with the amount of the resin component in the polyimide-based polymer solution so that the concentration of the inorganic particles in the film after the molding is 0 mass% or more and 90 mass% or less. Preferably 10 mass% or more and 60 mass% or less, and more preferably 20 mass% or more and 50 mass% or less. If the compounding ratio is within the above range, the transparency and the mechanical strength of the optical film tends to be compatible with each other.

(Ultraviolet absorber)

The ultraviolet absorber is suitably selected because it is commonly used as an ultraviolet absorber in the field of resin materials. The ultraviolet absorber is a compound which absorbs light having a wavelength of 400 nm or less, and the kind and amount of the ultraviolet absorber can be determined according to the required properties of the light absorptive capacity depending on the application. Examples of the ultraviolet absorber include at least one compound selected from the group consisting of a benzophenone compound, a salicylate compound, a benzotriazole compound, and a triazine compound. The ultraviolet absorber is preferably a benzotriazole-based compound.

In the present embodiment, the term "system compound" refers to a derivative of a compound to which the "system compound" is attached. For example, the "benzophenone compound" refers to a compound having a substituent bonded to benzophenone and benzophenone as a matrix skeleton.

(Other additives)

To the polyimide-based polymer solution, other additives may be further added within a range that does not impair transparency and flexibility. Examples of the other components include antioxidants, releasing agents, stabilizers, coloring agents such as bluing agents, flame retardants, lubricants, thickeners and leveling agents.

The total amount of the additive components other than the inorganic particles can be appropriately set so that the concentration in the film after the molding is from 0% to 20% by mass, preferably from more than 0% to 10% by mass or less.

(A polyimide-based polymer obtained by polymerization and imidization)

In the present embodiment, the polyimide is a polymer containing a repeating structural unit containing an imide group, and the polyamide is a polymer containing a repeating structural unit containing an amide group. The polyimide-based polymer includes polyimide; A polymer containing repeating structural units including both an imide group and an amide group; And a polymer containing both a repeating structural unit including an imide group and a repeating structural unit including an amide group.

The polyimide-based polymer obtained by polymerization and imidization has a repeating structural unit represented by the following formula (10). Here, G is a tetravalent organic group and A is a divalent organic group. G, and / or A may include two or more kinds of structures represented by formula (10). The polyimide-based polymer according to the present embodiment may be any one of the structures represented by the formulas (11), (12) and (13) within the range of not impairing various physical properties of the obtained polyimide- Or more.

The polyimide-based polymer according to the present embodiment can be produced as a main raw material of a tetracarboxylic acid compound and a diamine compound described later. When the repeating structural unit represented by the formula (10) is a main structural unit of the polyimide-based polymer , In view of the strength and transparency of the film. The repeating structural unit represented by the formula (10) is preferably at least 40 mol%, more preferably at least 50 mol%, still more preferably at least 70 mol%, based on the total repeating structural units of the polyimide polymer , Particularly preferably 90 mol% or more, and even more preferably 98 mol% or more. The repeating structural unit represented by the formula (10) may be 100 mol%.

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

G and G ¹ are each a tetravalent organic group and are preferably organic groups which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group and are represented by the following formulas (20), (21), (22) ) And a tetravalent chain hydrocarbon group having 6 or less carbon atoms represented by the formula (24), (25), (26), (27), (28) or (29) Z represents a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH (CH ₃ ) -, -C (CH ₃ ) ₂ -, - -O-Ar-, -Ar-CH ₂ -Ar-, -Ar-C (CF ₃ ) ₂ -, -Ar-, -SO ₂ -, -CO-, -O-Ar-O-, (CH ₃ ) ₂ -Ar- or -Ar-SO ₂ -Ar-. Ar represents an arylene group having 6 to 20 carbon atoms which may be substituted with a fluorine atom, and specific examples thereof include a phenylene group. The groups represented by formulas (20) to (27) are preferable because the yellowing degree of the resulting film is easily suppressed.

[Chemical Formula 9]

G ² is a trivalent organic group and is preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As the organic group of G ^2, of the formula 20, formula 21, formula 22, formula 23, formula 24, formula 25, formula 26, formula 27, formula A group in which one of the bonding hands of the group represented by the formula (28) or (29) is substituted with a hydrogen atom and a trivalent chain hydrocarbon group having a carbon number of 6 or less are exemplified.

G ³ is a divalent organic group and is preferably an organic group which may be substituted with a hydrocarbon group or a fluorine-substituted hydrocarbon group. As the organic group of G ^3, of the formula 20, formula 21, formula 22, formula 23, formula 24, formula 25, formula 26, formula 27, formula A group in which two nonadjacent groups are substituted with a hydrogen atom and a divalent chain hydrocarbon group having a carbon number in a range of 6 or less are exemplified among the bonds of the groups represented by formulas (28) and (29).

A, A ¹ , A ² and A ³ are all bivalent organic groups. (30), (31), (32), (33), (34) and (35) below, which may be substituted with a hydrocarbon group or a fluorine- , Equation (36), equation (37) or equation (38); A group substituted by a methyl group, a fluoro group, a chloro group or a trifluoromethyl group; And a chain hydrocarbon group having 6 or less carbon atoms.

Z ¹ , Z ² and Z ³ each independently represent a single bond, -O-, -CH ₂ -, -CH ₂ -CH ₂ -, -CH (CH ₃ ) -, _{, -C (CH 3) 2 -} , -C (CF 3) 2 - or denotes a -CO- -, -SO _2. As one example, Z ¹ and Z ³ are -O- and Z ² is -CH ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ - or -SO ₂ -. Z ¹ and Z ² , and Z ² and Z ³ are each preferably a meta position or a para position with respect to each ring.

[Chemical formula 10]

The repeating structural units represented by formulas (10) and (11) are usually derived from diamines and tetracarboxylic acid compounds. The repeating structural unit represented by the formula (12) is usually derived from a diamine and a tricarboxylic acid compound. The repeating structural unit represented by the formula (13) is usually derived from a diamine and a dicarboxylic acid compound.

The polyimide-based polymer according to the present embodiment may be a copolymer containing a plurality of different repeating structural units. The weight average molecular weight of the polyimide-based polymer is usually 50,000 to 500,000. The weight average molecular weight of the polyimide-based polymer is preferably 80,000 to 500,000, more preferably 100,000 to 500,000, and still more preferably 130,000 to 400,000. The weight average molecular weight is the standard polystyrene reduced molecular weight measured by GPC. If the weight average molecular weight of the polyimide-based polymer is large, high flexibility is likely to be obtained. However, if the weight average molecular weight of the polyimide-based polymer is too large, the viscosity of the varnish tends to be high and the workability tends to be lowered.

When the polyimide-based polymer and the polyamide contain a fluorine-substituted group, the elastic modulus of the obtained film is improved and the YI value of the film tends to be reduced. If the elastic modulus of the film is high, the occurrence of scratches and wrinkles tends to be suppressed. From the viewpoint of transparency of the film, it is preferable that the polyimide-based polymer and the polyamide have a fluorinated substituent. Specific examples of fluorine-substituted groups include a fluoro group and a trifluoromethyl group.

The content of the fluorine atom in the polyimide-based polymer may be 1% by mass or more, 5% by mass or more, 10% by mass or more and 20% by mass or more based on the mass of the polyimide-based polymer. The upper limit may be 40 mass% or less.

(Film forming method)

An example of a method for producing a polyimide-based polymer film using the obtained polyimide varnish will be described. A polyimide-based polymer varnish is plied on the substrate to form a coating film, the solvent is removed from the coating film, and the dried coating film is peeled from the substrate. Thereby, a polyimide-based polymer film is obtained.

Flexing can be performed on a resin substrate, a stainless steel belt, or a glass substrate by a roll-to-roll method or a batch method. Examples of the resin substrate include PET, PEN, polyimide, polyamideimide and the like. The resin base material is preferably a resin having excellent heat resistance.

In the case of a polyimide-based polymer film, the PET substrate is preferable from the viewpoint of adhesiveness with the film and cost.

The varnish obtained by the production method of the present invention can obtain a film having good physical properties even if it is made into a film without going through a purification step. For this reason, it is preferable that the polyimide-based polymer is firstly deposited as a solid and then film-formed without going through a purification step of re-dissolving in a solvent. Thereby, the process becomes advantageous in terms of cost.

In the method for producing a polyimide film of the present invention, a predetermined amount of organic solvent is volatilized by passing a coated film through a dryer in which warmed gas is brought into contact with the surface of the coated film, and the coated film is made into a self- Or may be obtained by peeling from a support. The operating temperature is controlled by the substrate to be used, and in the case of using a resin substrate, it is generally carried out at a temperature lower than the glass transition temperature thereof. Usually, it is sufficient to heat to a suitable temperature of 50 ° C to 300 ° C, and the heating temperature may be controlled in multiple steps or have a temperature gradient. Suitably, it is also preferably carried out under an inert atmosphere or under reduced pressure.

If necessary, the peeled polyimide-based polymer film may be further heated to 80 to 300 占 폚.

(Polyimide-based polymer film)

The polyimide-based polymer film thus obtained is formed of the solid component in the polyimide-based polymer varnish, and one of the main components is a polyimide-based polymer. The polyimide-based polymer is preferably 30 mass% or more based on the total amount of the polyimide-based polymer film. The polyimide-based polymer film may contain the fine silica particles, the ultraviolet absorbent and / or the additive. The concentration of the polyimide-based polymer is preferably 10% by mass or more, and more preferably 13% by mass or more, based on the total mass of the polyimide-based polymer film.

The polyimide-based polymer film contains a tertiary amine. Preferred examples of tertiary amines are as described in (tertiary amines) above. From the viewpoint of improving the endurance of the obtained polyimide-based polymer film, the content of the tertiary amine in the polyimide-based polymer film is preferably small. The content of the tertiary amine is preferably 0.25 mass% or less, more preferably 0.20 mass% or less, and further preferably 0.15 mass% or less. By decreasing the content, the coloration of the film tends to be suppressed.

On the other hand, when a laminate of a polyimide-based film is prepared and applied to various applications, it is preferable that a tertiary amine is contained in order to suppress ultraviolet transmission. The content of the tertiary amine is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, and still more preferably 0.05 mass% or more.

The thickness of the polyimide-based polymer film may be 10 to 200 mu m.

The polyimide-based polymer film obtained by this embodiment can exhibit a bending number of times of 5,000 times or more in an endurance test of R = 1 mm. It is also possible to obtain a film exhibiting a number of bending times of 6,000 or more, 8,000 or more, 10,000 times or more, and 20,000 times or more by optimizing the production conditions of the polyimide-based polymer varnish. The endurance test of R = 1 mm is a test where the center of a film cut into a 10 mm x 100 mm short strip is measured with a radius of curvature of 1.0 mm, a bending angle of 135, a load of 750 g, This is the number of times of bending when bent alternately in both directions.

The polyimide-based polymer film obtained by the present embodiment can sufficiently suppress the yellowness YI according to JIS K7373: 2006, and the yellowness YI can be 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less. It can be set to 2.1 or less, 2.0 or less, 1.9 or less, or 1.8 or less by optimizing the synthesis conditions such as the temperature at the time of film formation.

The polyimide-based polymer film obtained by this embodiment is transparent. Specifically, the polyimide-based polymer film may have a total light transmittance (Tt) measured according to JIS K7105: 1981 of 85% or more, preferably 90% or more.

, More preferably not less than 91%, and even more preferably not less than 92%. In addition, the polyimide-based polymer film may have a haze measured according to JIS K 7105: 1981 of 1% or less, preferably 0.8% or less. Or less, more preferably 0.5% or less, and still more preferably 0.3% or less.

The coloring of the polyimide-based polymer film obtained by the present embodiment may be reduced particularly by containing a fluorine-containing substituent. The content of the fluorine atom in the polyimide-based polymer may be 1% by mass or more, 5% by mass or more, 10% by mass or more and 20% by mass or more based on the mass of the polyimide-based polymer. The upper limit may be 40 mass% or less.

(Usage)

Such an optical film can be suitably used as an optical member such as a front plate of a flexible device because it has high endurance and good optical characteristics (yellow tint, Tt, haze).

Examples of the flexible device include an image display device (a flexible display, an electronic paper, etc.), a solar cell, and the like. The flexible display includes, for example, a front plate / a polarizing plate protective film / a polarizing plate / a polarizing plate protective film / a touch sensor film / an organic EL element layer / a TFT substrate in this order from the front side. A hard coating layer, an adhesive layer, an adhesive layer, a retardation layer, and the like may be included between the respective layers. Such a flexible display can be used as an image display unit of a tablet PC, a smart phone, a portable game machine or the like.

Further, a multilayer body in which various functional layers such as an ultraviolet absorbing layer, a hard coating layer, an adhesive layer, a color adjusting layer, and a refractive index adjusting layer are added to the surface of the optical film may be used.

Example

(Evaluation of bending resistance)

The bending resistance of the polyimide-based polymer films obtained in Examples and Comparative Examples was evaluated based on the following criteria. The film was cut with a dumbbell cutter into a 10 mm x 100 mm stage. The cut film was set in an MIT-DA MIT internal fatigue tester manufactured by Toyo Seiki Seisakusho Co., Ltd. and bent in both the front and back directions under the condition of a test speed of 175 cpm, a bending angle of 135 DEG, a load of 750 g, and a bending clamp R of 1.0 mm, The number of bending times until the bending was measured.

(Measurement of total light transmittance Tt)

The total light transmittance of the polyimide-based polymer films obtained in the examples and comparative examples was measured according to JIS K7105: 1981, using a fully automatic Hayes machine HGM-2DP manufactured by Suga Tester.

(Haze measurement)

The total light transmittance of each of the polyimide polymer films obtained in Examples and Comparative Examples was measured according to JIS K7105: 1981 by means of a fully automatic Hayes computer HGM-2DP manufactured by Suga Tester.

(Measurement of yellowness value (YI value)) [

The yellow index (YI value) of each of the polyimide-based polymer films obtained in Examples and Comparative Examples was measured by an infrared spectrophotometer V-670 manufactured by Nippon Bunko K.K. After the background measurement was performed in the absence of the sample, the polyimide-based film was set in the sample holder, and the transmittance was measured with respect to the light of 300 to 800 nm to obtain the tristimulus values (X, Y, Z). The YI value was calculated based on the following equation.

YI = 100 x (1.2769X-1.0592Z) / Y

(Evaluation of weight average molecular weight)

Gel Permeation Chromatography (GPC) measurement

(1) Pre-processing method

The sample was dissolved in? -Butyrolactone (GBL) to prepare a 20% solution. The sample was diluted 100 times with DMF eluant and filtered through a 0.45 占 퐉 membrane filter to obtain a measurement solution.

(2) Measurement conditions

Column: TSKgel SuperAWM-H x 2 + SuperAW 2500 x 1 (6.0 mm I.D. x 150 mm x 3)

Eluent: DMF (10 mM lithium bromide added)

Flow rate: 0.6 ml / min.

Detector: RI detector

Column temperature: 40 DEG C

Injection amount: 20 μl

Molecular weight standard: Standard polystyrene

(Evaluation of concentration of residual catalyst in film)

GC measurement was conducted under the following conditions to quantify the tertiary amine.

Solution preparation: 100 mg of the film is weighed into a screw tube and dissolved by addition of 5 ml of DMSO.

50 占 폚 (5 min)? 20 占 폚 / min? 350 占 폚 (5 min), column temperature BPX-5 (0.25 mm 占 30 m, film thickness 0.25 占 퐉) DMSO, syringe cleaning solvent A: 3 times (volume): 280 占 폚, flow rate: He at 1.0 ml / min, detector: FID, detector ON: 350 占 폚, sample injection amount: 1.0 占 퐇, split ratio: , B: 3 times

(Example 1)

(Preparation of polyimide varnish)

Under a nitrogen atmosphere, 1.25 g of isoquinoline was added to a reaction vessel to which a vacuum pump equipped with a solvent trap and a filter was connected. Next, 375.00 g of? -Butyrolactone (GBL) and 104.12 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB) were added to the reaction vessel and stirred Completely dissolved. 145.88 g of 4,4 '- (hexafluoroisopropylidene) diphthalic acid dianhydride (6FDA) was further added, and then the temperature in the oil bath was elevated with stirring. The molar ratio of the added TFMB to 6FDA was 6FDA: TFMB was 1.00: 0.99, and the monomer concentration in the liquid was 40 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.5. When the internal temperature reached 80 占 폚, the pressure was reduced to 650 mmHg, and then the internal temperature was raised to 180 占 폚. After reaching 180 ° C, the mixture was further heated and stirred for 4 hours, then the pressure was restored to atmospheric pressure, and the solution was cooled to 155 ° C to obtain a polyimide solution. GBL was added at 155 캜 to obtain a uniform solution having a solid content of polyimide of 24 wt%, and then polyimide varnish was taken out from the reaction vessel.

(Production of polyimide film)

38.31 g of GBL and 11.82 g of N, N-dimethylacetamide (DMAc) were added to 200.00 g of the obtained polyimide varnish and further diluted. The coating film was formed by molding it on a PET (polyethylene terephthalate) film, and then heated at 50 占 폚 for 30 minutes and at 140 占 폚 for 10 minutes to obtain a polyimide film. PET and further heated at 200 캜 for 40 minutes to obtain a film having a thickness of 80 탆, a Tt of 92.6%, a Haze of 0.1% and a yellowness of 2.2.

(Example 2)

A film having a Tt of 92.7%, a haze of 0.1% and a yellowness of 2.0 was obtained in the same manner as in Example 1 except that the heating and agitation time of the liquid after reaching 180 캜 was changed to 3 hours.

(Example 3)

A film having Tt of 92.4%, Haze of 0.1% and yellow of 1.8 was obtained in the same manner as in Example 2 except that the amount of isoquinoline was changed to 0.75 g. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.3.

(Comparative Example 1)

Except that the amount of isoquinoline was changed to 2.00 g and the inside temperature was changed to 180 deg. C without performing any decompression during the process, and the mixture was heated and stirred for 5 hours. Then, Tt 92.5%, Haze 0.1% The film of Fig. 2.4 was obtained. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.8.

(Comparative Example 2)

The amount of isoquinoline was changed to 2.50 g, the amount of γ-butyrolactone (GBL) was 464.29 g, the amount of TFMB was 103.50 g, the amount of 6FDA was 146.50 g, the molar ratio of TFMB and 6FDA was changed to 6FDA: TFMB Of Tt was 92.5% in the same manner as in Example 1, except that the monomer concentration in the liquid was 35% by weight and the inside temperature was 180 占 폚 and the heating and stirring were carried out without performing any decompression during the process for 5 hours. Haze 0.1%, and yellow 3.0 was obtained. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 1.0.

(Comparative Example 3)

3.00 g of triethylamine was added instead of isoquinoline, the amount of TFMB was 104.73 g, the amount of 6FDA was 145.27 g, the molar ratio of TFMB and 6FDA was 1.00: 1.00, and the monomer concentration in the liquid was 40 wt% And a film having a yellowness of 2.1 was obtained in the same manner as in Example 1 except that heating and stirring were carried out for 5 hours after the internal temperature reached 180 占 폚 without performing any decompression during the process. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 1.2.

Conditions and results are shown in Table 1.

In Examples 1 to 3 in which the tertiary amine was added and the pressure was reduced during heating, high bendability was achieved. On the other hand, in Comparative Examples 1 to 3, in which the pressure was not reduced during heating, even when the catalyst amount was higher than that in Examples, it was still impossible to increase the bending resistance. When the amount of the catalyst in the comparative example is made to the same degree as in the examples, it is expected that the bending resistance is further deteriorated.

(Example A1)

(Preparation of polyimide varnish)

Under a nitrogen atmosphere, 1.25 g of isoquinoline was added to a reaction vessel to which a vacuum pump equipped with a solvent trap and a filter was connected. Next, 305.58 g of? -Butyrolactone (GBL) and 104.43 g of 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFMB) were added to the reaction vessel and stirred Completely dissolved. 145.59 g of 4,4 '- (hexafluoroisopropylidene) diphthalic acid dianhydride (6FDA) was further added, and then the temperature in the oil bath was elevated with stirring. The molar ratio of the added TFMB to 6FDA was 6FDA: TFMB of 1.00: 0.995, and the monomer concentration was 45 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.5. When the internal temperature reached 120 ° C, the pressure was reduced to 610 mmHg, and then the internal temperature was raised to 200 ° C. After reaching 200 deg. C, the mixture was further heated and stirred for 5.5 hours, and then the pressure was restored to atmospheric pressure and cooled to 170 deg. C to obtain a polyimide solution. When the oxygen concentration in the reaction vessel was checked before and after the decompression, it was 0.2%. GBL (solvent B) was added at 170 ° C to obtain a uniform solution having a solid content of 40 wt% of polyimide. Further, N, N-dimethylacetamide (solvent B) was added at 155 캜 to obtain a polyimide having a solid content of 20 wt% %, And the polyimide varnish was taken out from the reaction vessel.

(Production of polyimide film)

To 200.00 g of the polyimide varnish obtained, 50 g of N, N-dimethylacetamide (DMAc) was further added and diluted. The coating film was formed by molding it on a PET (polyethylene terephthalate) film, and then heated at 50 占 폚 for 30 minutes and at 140 占 폚 for 10 minutes to obtain a polyimide film. PET and further heated at 200 ° C for 40 minutes to obtain a film having a thickness of 80 μm, Tt 92.0%, Haze 0.1% and a yellowness of 3.9.

(Example A2)

The amount of gamma -butyrolactone (GBL) was changed to 375.03 g, and the internal pressure was reduced to 610 mmHg at the time when the internal temperature reached 120 DEG C, and then the internal temperature was raised to 180 DEG C, A polyimide solution was obtained in the same manner as in Example A1 except that heating and stirring were carried out for 8.5 hours. In the total solution in the reaction vessel, the monomer concentration was 40 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.5. When the oxygen concentration in the reaction vessel was checked before and after the decompression, it was 0.2%. N, N-dimethylacetamide (DMAc) (solvent B) was added at 155 캜 to obtain a uniform solution having a solid content of polyimide of 20 wt%, and polyimide varnish was taken out from the reaction vessel.

Using the obtained polyimide varnish, a polyimide film was produced in the same manner as in Example A1 to obtain a film having a thickness of 80 占 퐉, Tt of 92.0%, Haze of 0.1%, and a yellow degree of 3.9.

(Example A3)

The amount of isoquinoline was changed to 0.5 g and the amount of gamma -butyrolactone (GBL) was changed to 375.03 g. When the internal temperature reached 120 ° C, the pressure was reduced to 400 mmHg, A polyimide solution was obtained in the same manner as in Example A1 except that the temperature was elevated and the temperature was raised to 180 deg. C and further the heating and stirring were carried out for 8.5 hours. In the total solution in the reaction vessel, the monomer concentration was 40 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.2. When the oxygen concentration in the reaction vessel was checked before and after the decompression, it was less than 0.01%. N, N-dimethylacetamide (DMAc) (solvent B) was added at 155 캜 to obtain a homogeneous solution having a solid content of polyimide of 20 wt%, and polyimide varnish was taken out from the reaction vessel.

Using the obtained polyimide varnish, a polyimide film was produced in the same manner as in Example A1 to obtain a film having a thickness of 80 占 퐉, a Tt of 92.6%, a Haze of 0.1% and a yellowness of 2.0.

(Example A4)

The amount of isoquinoline was changed to 0.5 g, the pressure was reduced to 400 mmHg at the time when the internal temperature reached 120 캜, and then the internal temperature was raised to 180 캜. After reaching 180 캜, the mixture was further heated and stirred for 5.5 hours , A polyimide solution was obtained in the same manner as in Example A1. In the total solution in the reaction vessel, the monomer concentration was 45 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.2. When the oxygen concentration in the reaction vessel was checked before and after the decompression, it was less than 0.01%. GBL (solvent B) and N, N-dimethylacetamide (solvent B) were added to the polyimide solution in the same manner as in Example A1 to prepare a homogeneous solution having a solid content of polyimide of 20 wt% The polyimide varnish was taken out.

Using the polyimide varnish thus obtained, a polyimide film was produced in the same manner as in Example A1 to obtain a film having a thickness of 80 占 퐉, Tt 92.7%, Haze 0.1% and yellow 1.7.

(Example A5)

A polyimide varnish was prepared in the same manner as in Example A4. Except that N, N-dimethylacetamide (DMAc) to which a UV absorber (trade name: Sumisorb340, manufactured by Sumitomo Chemical Co., Ltd.) was added to the polyimide varnish during the production of the film was changed to polyimide A film was prepared. The obtained film had a thickness of 80 탆, Tt of 92.4%, Haze of 0.2%, and a yellowness of 2.3. In addition, the unit phr in Table 2 means the parts by mass relative to 100 parts by mass of the polyimide-based polymer contained in the varnish.

(Example A6)

The amount of isoquinoline was changed to 0.5 g, the pressure was reduced to 500 mmHg at the time when the internal temperature reached 120 캜, and then the internal temperature was raised to 180 캜. After reaching 180 캜, the mixture was further heated and stirred for 5.5 hours , A polyimide solution was obtained in the same manner as in Example A1. In the total solution in the reaction vessel, the monomer concentration was 45 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.2. When the oxygen concentration in the reaction vessel was checked before and after the decompression, it was less than 0.01%. GBL (solvent B) and N, N-dimethylacetamide (solvent B) were added to the polyimide solution in the same manner as in Example A1 to prepare a homogeneous solution having a solid content of polyimide of 20 wt% The polyimide varnish was taken out.

Using the obtained polyimide varnish, a polyimide film was produced in the same manner as in Example A1 to obtain a film having a thickness of 80 占 퐉, a Tt of 92.6%, a haze of 0.2% and a yellowness of 2.0.

(Example A7)

The amount of isoquinoline was changed to 0.5 g, the pressure was reduced to 400 mmHg at the time when the internal temperature reached 120 캜, and then the internal temperature was raised to 180 캜. After reaching 180 캜, the mixture was further heated and stirred for 5.5 hours , A polyimide solution was obtained in the same manner as in Example A1. In the total solution in the reaction vessel, the monomer concentration was 45 wt%. The mass part of the tertiary amine relative to 100 parts by mass of the raw material monomer is 0.2. When the oxygen concentration in the reaction vessel was checked before and after the decompression, it was less than 0.01%. GBI (solvent B) was added to the polyimide solution at 170 캜 to prepare a uniform solution having a solid content of 40% by weight of polyimide. Further, cyclopentanone (solvent B) was added at 130 캜 to obtain a solid component Of 20 wt%, and the polyimide varnish was taken out from the reaction vessel.

A polyimide film was prepared in the same manner as in Example A1 except that 50 g of cyclopentanone was added to 200.00 g of the obtained polyimide varnish in place of DMAc to further dilute the film. The film thickness was 80 占 퐉, Tt 92.6%, Haze 0.1% And a yellow 1.9 film was obtained.

(Example A8)

A polyimide varnish was prepared in the same manner as in Example A7. A polyimide film was produced in the same manner as in Example A7 except that cyclopentanone to which an ultraviolet absorber (trade name: Sumisorb340, manufactured by Sumitomo Chemical Co., Ltd.) was added to the polyimide varnish during the production of the film. The obtained film had a thickness of 80 탆, Tt 92.5%, Haze 0.1%, and a yellowness of 2.4. In addition, the unit phr in Table 2 means the parts by mass relative to 100 parts by mass of the polyimide-based polymer contained in the varnish.

Conditions and results are shown in Table 2.

In the following examples, the yield of the polyimide is calculated from the amount of the raw material monomer / resin solid content contained in the solvent C after cleaning + the total amount (unit: weight) of resin solid content in the polyimide varnish produced Theoretical amount (unit: weight) of polyimide-based polymer x 100 ". The solvent C after cleaning is a cleaning liquid which is obtained after the first production of the polyimide varnish in the following examples. The produced polyimide varnish is a polyimide varnish obtained by the production of a second polyimide varnish in the following examples. The theoretical amount of the polyimide-based polymer calculated from the input amount of the raw material monomer is the theoretical amount of the polyimide-based polymer calculated from the input amount of the raw material monomer in the production of the second polyimide varnish in the following examples.

(Example B1)

A polyimide varnish was prepared in the same manner as in Example A7, and the obtained polyimide varnish was taken out of the reaction vessel. Then, cyclopentanone was injected into the reaction vessel as a solvent C, heated to 130 캜 and heated for 3 hours and washed. Cyclopentanone used for washing was withdrawn from the reaction vessel and recovered (solvent C after washing). Then, GBL was injected into the reaction vessel as solvent D, and the temperature was raised to 200 占 폚 and heated for 8 hours to be cleaned. The reaction vessel was re-synthesized in the same manner as in Example 10 to obtain a second polyimide varnish. A polyimide varnish was obtained by using the solvent C after washing as the cyclopentanone of the diluting solvent B to be added to the solution before being taken out from the reaction vessel. The polyimide contained in the second polyimide varnish obtained had a weight average molecular weight in terms of polystyrene of 320,000, and the yield of polyimide was 97.2%.

Subsequently, a polyimide film was produced in the same manner as in Example A7 using this second polyimide varnish to obtain a film having a thickness of 80 占 퐉, Tt 92.5%, Haze 0.1% and a yellowness degree of 2.1.

(Example B2)

Except that the cleaning time in the cyclopentanone in the solvent C after the polyimide varnish was withdrawn from the reaction vessel was changed to 28 hours and the washing liquid was recovered (solvent C after washing), the second poly I got a mid varnish. The polyimide contained in the second polyimide varnish obtained had a weight average molecular weight in terms of polystyrene of 340,000, and the yield of polyimide was 96.6%.

Subsequently, a polyimide film was produced in the same manner as in Example A7 using this second polyimide varnish to obtain a film having a thickness of 80 占 퐉, Tt 92.6%, Haze 0.1%, and a yellowness value of 2.2.

(Example B3)

Polyimide varnish was prepared in the same manner as in Example A4, and the obtained polyimide varnish was withdrawn from the reaction vessel. Then, GBL was injected into the reaction vessel as a solvent C. The temperature was raised to 200 占 폚 and the reaction vessel was heated for 8 hours and then washed. The GBL used for washing was withdrawn from the reaction vessel and recovered. Then, GBL was injected into the reaction vessel as solvent D, and the temperature was raised to 200 占 폚 and heated for 8 hours to be cleaned. In the washed reaction vessel, a second polyimide varnish was prepared in the same manner as in Example A4. At this time, the solvents C and D after the cleaning were not added to the production (dilution) of the second polyimide varnish. The polyimide contained in the second polyimide varnish obtained had a weight average molecular weight in terms of polystyrene of 360,000, and the yield of polyimide was 92.2%.

Subsequently, a polyimide film was produced in the same manner as in Example A4 by using the second polyimide varnish to obtain a film having a thickness of 80 占 퐉, Tt 92.7%, Haze 0.1%, and a yellowness of 1.7.

(Example B4)

A polyimide varnish was prepared in the same manner as in Example A7, and the obtained polyimide varnish was taken out of the reaction vessel. Then, GBL was injected into the reaction vessel as a solvent C, heated to 200 캜 and heated for 8 hours and washed. The GBL used for washing was withdrawn from the reaction vessel and recovered. Then, GBL was injected into the reaction vessel as solvent D, and the temperature was raised to 200 占 폚 and heated for 8 hours to be cleaned. In the washed reaction vessel, a second polyimide varnish was prepared in the same manner as in Example A7. At this time, the solvents C and D after the cleaning were not added to the production (dilution) of the second polyimide varnish. The polyimide contained in the second polyimide varnish obtained had a weight average molecular weight in terms of polystyrene of 311,000, and the yield of polyimide was 91.3%.

Subsequently, a polyimide film was produced in the same manner as in Example A7 using this second polyimide varnish to obtain a film having a thickness of 80 탆, Tt 92.6%, Haze 0.1%, and a yellowness value of 1.9.

(Reference Example B1)

Polyimide varnish was prepared in the same manner as in Example A2, and the obtained polyimide varnish was taken out from the reaction vessel. Then, GBL was injected into the reaction vessel as a solvent C, heated to 200 DEG C, heated for 8 hours and washed. The GBL used for washing was withdrawn from the reaction vessel and recovered. Then, GBL was injected into the reaction vessel as solvent D, and the temperature was raised to 200 占 폚 and heated for 8 hours to be cleaned. In the washed reaction vessel, a second polyimide varnish was prepared in the same manner as in Example A2. At this time, the solvents C and D after the cleaning were not added to the production (dilution) of the second polyimide varnish. The polyimide contained in the second polyimide varnish obtained had a weight average molecular weight in terms of polystyrene of 220,000, and the yield of polyimide was 94.5%.

Subsequently, a polyimide film was produced in the same manner as in Example A2 by using the second polyimide varnish to obtain a film having a thickness of 80 탆, Tt 92.0%, Haze 0.1%, and a yellowness value of 3.9. Conditions and results are shown in Table 3.

Claims (17)

Polymerizing a raw material monomer of a polyimide-based polymer in a solvent to obtain a polyimide-based polymer precursor; and polymerizing the polyimide-based polymer precursor in a solvent containing a tertiary amine in a reduced- A method for producing a polyimide-based polymer varnish, which comprises an imidization step of obtaining a solution of a mid-system polymer. The method according to claim 1,
Wherein the temperature of the imidation step is 100 占 폚 or higher and 250 占 폚 or lower. 3. The method according to claim 1 or 2,
Wherein the tertiary amine has a boiling point of from 120 캜 to 350 캜. 4. The method according to any one of claims 1 to 3,
Wherein the polyimide-based polymer contains fluorine at 20 mass% or more. 5. The method according to any one of claims 1 to 4,
Wherein the pressure of the reduced-pressure environment is not less than 350 mmHg and not more than 730 mmHg. 6. The method of claim 5,
Wherein the pressure of the reduced-pressure environment is not less than 500 mmHg and not more than 730 mmHg. 7. The method according to any one of claims 1 to 6,
Wherein the concentration of oxygen in the gaseous phase in contact with the liquid phase containing the solvent in the imidation step is 0.02% or less. 8. The method according to any one of claims 1 to 7,
0.05 parts by mass or more and 0.7 parts by mass or less of the tertiary amine is added to 100 parts by mass of the raw material monomer. 9. The method according to any one of claims 1 to 8,
Further comprising a step of adding an ultraviolet absorber to the obtained solution of the polyimide-based polymer. 10. The method according to any one of claims 1 to 9,
And further adding a silica sol to the obtained solution of the polyimide-based polymer. A process for producing a polyimide-based polymer varnish as claimed in any one of claims 1 to 10,
And polymerizing the polyimide-based polymer varnish without causing precipitation and re-dissolution of the polyimide-based polymer in the obtained polyimide-based polymer varnish. A polyimide polymer having a weight average molecular weight of 50,000 or more and 500,000 or less and a tertiary amine in an amount of 0.01% by mass or more and 0.25% by mass or less based on the total mass of the film. 13. The method of claim 12,
Wherein the tertiary amine has a boiling point of from 120 캜 to 350 캜. (1) a step of reacting a monomer raw material in a solvent A in a reaction vessel to obtain a solution of a polyimide-based polymer,
(3) removing the solution from the reaction vessel,
(4) a step of washing the reaction vessel with the solvent C, and then removing the solvent C after the washing from the reaction vessel, wherein the steps (1), (3) and (4) And repeating this process in this order,
The polyimide-based polymer obtained in the step (1) is transparent and has a weight average molecular weight of 250,000 or more. 15. The method of claim 14,
(5) After the step (4), the step of cleaning the reaction vessel with the solvent D and taking out the solvent D after cleaning from the reaction vessel,
Wherein the steps (1), (3), (4) and (5) are repeated in this order using the same reaction vessel. 16. The method according to claim 14 or 15,
Between the step (1) and the step (3)
(2) adding a solvent B to the reaction vessel to dilute the solution obtained in the step (1)
Wherein the steps (1) to (4) or the steps (1) to (5) are repeated using the same reaction vessel. 17. The method of claim 16,
Wherein the solvent B is a solvent C taken out of the reaction vessel in the step (4).