KR20160003606A - Polyamic acid solution, transparent polyimide film, transparent substrate using the same - Google Patents

Abstract

The present invention relates to a polyamic acid solution applied to a substrate for a flexible display, a TFT substrate, a flexible printed circuit board, a flexible OLED surface lighting substrate, a substrate material for electric paper, etc. or used as a protection film and the like, and to a transparent polyimide resin film manufactured by using the polyamic acid solution, and a transparent substrate. The polyamic acid solution comprises (a) aromatic dianhydride containing fluorinated aromatic dianhydride and nonfluorinated aromatic dianhydride; (b) a dicarbonyl compound; (c) an aromatic diamine containing fluorinated aromatic diamine and m-phenyldiamine; and (d) an organic solvent.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyamic acid solution, a transparent polyimide resin film and a transparent substrate using the polyamic acid solution,

The present invention relates to a polyamic acid solution which can be applied to a substrate for a flexible display, a TFT substrate, a flexible printed circuit board, a flexible OLED surface illuminating substrate, a substrate for an electronic substrate or the like, or a protective film, and a polyamic acid solution prepared using the polyamic acid solution A transparent polyimide resin film and a transparent substrate.

Generally, polyimide resin has superior electrical, chemical, thermal and mechanical properties compared to other polymers. Therefore, polyimide resin is used in high-temperature-resistant materials such as automobile materials, aviation and spacecraft materials, insulating coatings, insulating films, It is widely used in electronic materials.

However, the polyimide resin has a low transmittance in the visible light region because the color is brown or yellow due to the high density of the aromatic rings. To solve this problem, attempts have been made to polymerize monomers and solvents with high purity to polymerize them, but the improvement of the transmittance is not significant. US Patent No. 5,053,480 discloses a method using an aliphatic cyclic dianhydride instead of an aromatic dianhydride. However, the transparency and color have been improved, but the transparency has not been satisfactorily high, and furthermore, the thermal and mechanical properties have deteriorated There was a problem.

As described above, conventionally known polyimide resins have limitations in use in fields requiring transparency. Particularly, in order for a plastic substrate made of polyimide resin to be applied to a flat panel display (FPD) such as a plasma display, a liquid crystal display, and an organic light emitting display instead of a glass substrate, And the coefficient of thermal expansion should be low.

Examples of the low heat expandable polyimide resin known so far include 3,3 ', 4,4'-biphenyl tetracarboxylic acid dianhydride and 3,3', 4,4'-biphenyl tetracarboxylic acid dianhydride, There is a polyimide resin obtained by polymerization of p-phenylenediamine. However, the film made of the polyimide resin had a low coefficient of thermal expansion of 12 ppm / 占 폚 or less, but had a low optical transmittance of 1% or less at 550 nm.

Accordingly, there is a demand for the development of a polyamic acid composition for producing a transparent plastic substrate exhibiting high transparency like a glass substrate and having excellent heat resistance and a low thermal expansion coefficient.

The present inventors have found that the polyamic acid solution contains an aromatic dianhydride, a dicarbonyl compound, an aromatic diamine and an organic solvent containing a fluorinated aromatic dianhydride and a non-fluorinated aromatic dianhydride, wherein the aromatic diamine component is a fluorinated aromatic diamine And a non-fluorinated aromatic diamine of a specific component are used in combination, it is possible to obtain a polyimide resin having improved optical characteristics and thermal characteristics.

Accordingly, it is an object of the present invention to provide a polyamic acid solution capable of simultaneously exhibiting a low thermal expansion coefficient, a high light transmittance, and a low yellow index.

Another object of the present invention is to provide a transparent polyimide resin film and a transparent substrate having high light transmittance, low thermal expansion coefficient and low yellowing degree by using the polyamic acid solution.

In order to achieve the above-mentioned object, the present invention relates to a fluorinated aromatic dianhydride, comprising: (a) an aromatic dianhydride containing a fluorinated aromatic dianhydride and a non-fluorinated aromatic dianhydride; (b) a dicarbonyl compound; (c) an aromatic diamine containing a fluorinated aromatic diamine and m-phenylenediamine; And (d) an organic solvent.

The present invention also provides a transparent polyimide resin film prepared by imidizing the polyamic acid solution described above.

The present invention also provides a transparent substrate comprising the transparent polyimide resin film.

Disclosed is a polyimide resin composition comprising a fluorinated dianhydride, a non-fluorinated dianhydride, a dicarbonyl compound, and a fluorinated aromatic diamine and m-phenylenediamine as monomers to produce a polyimide resin, And a transparent polyimide resin film having a low yellowing degree can be produced. Such a transparent polyimide resin film can be used as a transparent substrate for a flexible display instead of a glass substrate.

Hereinafter, the present invention will be described.

≪ Transparent polyamic acid solution >

The polyamic acid solution of the present invention is for producing a polyimide resin film exhibiting high transparency and excellent heat resistance and having a low thermal expansion coefficient. The polyamic acid solution comprises (a) a fluorinated aromatic dianhydride and a non-fluorinated aromatic dianhydride ≪ RTI ID = 0.0 > dianhydride < / RTI > (b) a dicarbonyl compound; (c) an aromatic diamine containing a fluorinated aromatic diamine and m-phenylenediamine; And (d) an organic solvent.

(a) an aromatic dianhydride

The polyamic acid solution of the present invention comprises a fluorinated aromatic dianhydride and a non-fluorinated aromatic dianhydride as the aromatic dianhydride component.

When the fluorinated aromatic dianhydride and the non-fluorinated aromatic dianhydride are mixed and used in the polyamic acid solution, the optical and thermal properties of the polyimide resin can be simultaneously improved. Here, a polyimide resin having excellent optical properties can be produced by the fluorine substituent of the fluorinated aromatic dianhydride, and a polyimide resin having excellent thermal properties due to the rigid structure of the non-fluorinated aromatic dianhydride can be prepared .

The fluorinated aromatic dianhydride is not particularly limited as long as it is an aromatic dianhydride into which a fluorine substituent is introduced. For example, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6-FDA, 4- (tri (Trifluoromethyl) pyromellitic dianhydride, 4-TFPPMDA), but are not limited thereto. These may be used alone or in combination of two or more. According to one example, 6-FDA can be used as a fluorinated aromatic dianhydride.

The non-fluorinated aromatic dianhydride is not particularly limited as long as it is an aromatic dianhydride to which no fluorine substituent is introduced. For example, pyromellitic dianhydride (PMDA), 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (3,3'4,4'-biphenyltetracarboxylic acid dianhydride, BPDA), 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride (TDA), 4,4'oxydiphthalic anhydride (4,4'-oxydiphthalic anhydride, ODPA), 2,2-bis [4-3,4-dicarboxyphenoxy] phenyl] propanediamine hydride ) phenyl] propane dianhydride (BPADA), ethylene glycol bis (4-trimellitate anhydride), TMEG), but are not limited thereto. These may be used alone or in combination of two or more Can be used in combination. According to one example of the present invention, PMDA can be used as the non-fluorinated aromatic dianhydride.

The mixing ratio of the fluorinated aromatic dianhydride (a1) to the non-fluorinated aromatic dianhydride (a2) is not particularly limited, but is preferably in the range of a1: a2 = 20 to 95: 80 to 5 molar equivalents, preferably 35.0 to 45.0: When the molar ratio is 65.0 to 55.0 mol, the transmittance and the yellowing degree can be further improved.

The content of the above-mentioned aromatic dianhydride is not particularly limited, but when it is 30 to 90 mol%, preferably 50 to 90 mol% based on 100 mol% of the sum of the aromatic dianhydride and the dicarbonyl compound, The thermal expansion coefficient of the polyimide resin can be further lowered while maintaining the high transmittance and low yellowing degree of the polyimide resin.

(b) a dicarbonyl compound

The polyamic acid solution of the present invention comprises a dicarbonyl compound. The dicarbonyl compound reacts with an aromatic diamine to form an amide structure in the polymer chain, and the thermal expansion coefficient of the polyimide resin may be lowered due to the amide structure.

The dicarbonyl compound used in the present invention is not particularly limited as long as it is a compound containing a dicarbonyl group. For example, acid halides, dicarboxylic acids, and the like, but are not limited thereto.

Specifically, non-limiting examples of the acid halide include p-terephthaloyl chloride (TPC), isophthaloyl dichloride (IPC), 1,3-adamantanedicarbonyl 1,3-adamantanedicarbonyl dichloride, 5-norbornene-2,3-dicarbonyl chloride, 4,4'-benzoyl dichloride (4,4 ' -benzoyl dichloride, 1,4-naphthalene dicarboxylic acid dichloride, 2,6-naphthalene dicarboxylic acid dichloride, 1,5-naphthalene dicarboxylic acid dichloride And the like. Non-limiting examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 4,4'-biphenyl dicarboxylic acid, naphthalene dicarboxylic acid and the like Dicarboxylic acid and the like, which may be used alone or in combination of two or more kinds thereof have. According to one example of the present invention, p-terephthaloyl chloride (TPC), isophthaloyl dichloride (IPC), or a mixture thereof may be used as the dicarbonyl compound.

The content of the dicarbonyl compound is not particularly limited, but the content of the dicarbonyl compound is preferably 10 to 70 mol%, more preferably 10 to 50 mol%, based on 100 mol% of the aromatic dianhydride and the dicarbonyl compound. , A polyimide resin having a very low thermal expansion coefficient can be produced while maintaining high transparency and low yellowing degree.

(c) An aromatic diamine

The polyamic acid solution of the present invention contains both a fluorinated aromatic diamine and m-phenylenediamine as an aromatic diamine component. Optionally, the polyamic acid solution may further comprise non-fluorinated aromatic diamines other than m-phenylenediamine.

When the polyamic acid solution contains a fluorinated aromatic diamine into which a fluorine substituent is introduced, the polyamic acid solution has an excellent optical property due to a charge transfer effect between fluorine substituents in the monomer, as compared with the case of using a non-fluorinated aromatic diamine A polyimide resin can be produced. In addition, when m-phenylenediamine is mixed with such a fluorinated aromatic diamine, a polyimide having a lower thermal expansion coefficient than m-phenylenediamine due to the bent form of the m-phenylenediamine monomer, Resin can be produced. When the m-phenylenediamine is used in combination with the fluorinated aromatic diamine, the reactivity of the aromatic diamine with the aromatic dianhydride is easily controlled by m-phenylenediamine to adjust the viscosity of the polyamic acid to 1,000 to 70,000 cps Can be controlled. Thus, when a fluorinated aromatic diamine and m-phenylenediamine are mixed as an aromatic diamine component of a polyamic acid solution, a polyimide resin having improved optical characteristics and thermal characteristics compared with the case of using a non-fluorinated aromatic diamine can be produced .

The fluorinated aromatic diamine used in the present invention is not particularly limited as long as it is an aromatic diamine containing fluorine. However, among the fluorinated aromatic diamines, diamines containing a fluorinated biphenyl structure can control the reactivity with an aromatic dianhydride and can realize a high glass transition temperature and a low thermal expansion property, thereby improving the thermal characteristics of the polyimide resin.

For example, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-bis (trifluoromethyl) -4,4'-Diaminobiphenyl, 2,2'-TFDB ), Bisaminohydroxyphebyl hexafluoropropane (DBOH), bisaminophenoxyphenyl hexafluoropropane (4BDAF), 2,2'-bis (trifluoromethyl) -4 , 3'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,5'-diaminobiphenyl ( 2,2'-Bis (trifluoromethyl) -5,5'-Diaminobiphenyl), but are not limited thereto. These may be used alone or in combination of two or more. Among them, when 2,2'-TFDB is used, the thermal expansion coefficient can be lowered while increasing the transmittance and the glass transition temperature.

The content of such a fluorinated aromatic diamine is not particularly limited. However, when the amount of the aromatic diamine is 80 to 95 mol% based on 100 mol% of the aromatic diamine, the optical transfer of the polyimide resin due to the charge transfer effect between the fluorine substituents in the monomer The characteristics can be further improved.

The polyamic acid solution according to the present invention further comprises m-phenylenediamine (m-PDA) together with the above-mentioned fluorinated aromatic diamine. Unlike other non-fluorinated aromatic diamines, in particular, p-PDA, the m-phenylenediamine is in the form of a curved form of the monomer itself. When used together with a fluorinated aromatic diamine, the optical properties of the polyimide resin The characteristics can be further improved.

The content of such m-phenylenediamine is not particularly limited, but when it is 5 to 20 mol% based on 100 mol% of aromatic diamine, the light transmittance and the yellowing property of the polyimide resin can be improved.

Optionally, the polyamic acid solution of the present invention may further comprise non-fluorinated aromatic diamines other than m-phenylenediamine as the aromatic diamine component. Non-limiting examples of such non-fluorinated aromatic diamines include p-phenylenediamine (p-PDA), oxydianiline (ODA), m-methylenediamine (m-MDA), bisaminophenoxyphenylpropane (6HMDA) Bisaminophenoxy diphenyl sulfone (DBSDA), etc. These may be used alone or in admixture of two or more.

The content of the other non-fluorinated aromatic diamine is not particularly limited, but may be about 0 to 40 mol%, preferably 0 to 20 mol%, based on 100 mol% of the aromatic diamine.

In the polyamic acid solution of the present invention, the mole ratio [c / (a + b)] of the mixture of the aromatic dianhydride (a) and the dicarbonyl compound (b) and the aromatic diamine (c) is not particularly limited , the viscosity of the polyamic acid solution is adjusted to about 1,000 to 70,000 cps when c / (a + b) is 0.9 to 1.1, preferably 0.99 to 1, so that the thickness of the polyamic acid solution can be easily controlled during coating, The surface can be uniformly formed.

(d) an organic solvent

The organic solvent usable in the present invention is not particularly limited as long as it is known in the art. (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, diethyl (N, N-dimethylformamide A polar solvent such as acetate may be used. In addition, a low boiling point solution such as tetrahydrofuran (THF), chloroform or the like or a low absorption solvent such as gamma -butyrolactone may be used.

The content of the aromatic dianhydride (a), the dicarbonyl compound (b), the aromatic diamine (c) and the organic solvent (d) in the polyamic acid solution of the present invention is not particularly limited.

In the polyamic acid solution, 5.0 to 9.0% by weight of aromatic dianhydride, 0.4 to 1.0% by weight of dicarbonyl compound, 6.0 to 9.0% by weight of aromatic diamine are contained in the polyamic acid solution in an organic solvent May be a balance amount adjusted so that the total amount of the polyamic acid solution becomes 100% by weight.

If the content of each component in the polyamic acid solution is less than the above range, the viscosity of the polyamic acid solution may be too low. On the other hand, if the content of the polyamic acid solution is more than the above range, the viscosity of the polyamic acid solution may become too high. Accordingly, when the content of each component in the polyamic acid solution according to the present invention is controlled within the above range, the polyamic acid solution may have a viscosity of about 1,000 to 70,000 cps, preferably about 3,000 to 20,000 cps, The solution is easy to control the thickness when coating, and the surface of the coated film can be uniformly formed.

The polyamic acid solution of the present invention may contain small amounts of additives such as a plasticizer, an antioxidant, a flame retardant, a dispersant, a viscosity modifier, and a leveling agent within a range that does not significantly impair the objects and effects of the present invention have.

When the polyamic acid solution of the present invention as described above is subjected to a solution polymerization reaction, a polyamic acid can be obtained. More specifically, when a fluorinated aromatic diamine and phenylenediamine are added to an organic solvent to dissolve the solution, and then a solution of a fluorinated aromatic dianhydride and a non-fluorinated aromatic dianhydride is added to the solution, the polyamic acid can be prepared have. At this time, the reaction conditions are not particularly limited, and the reaction can be carried out at -20 to 80 ° C for 1 to 12 hours (preferably 1 to 3 hours).

≪ Transparent polyimide resin film and production method thereof >

The present invention provides a transparent polyimide resin film prepared by imidizing the above-mentioned polyamic acid solution.

At this time, the polyimide resin may be in the form of a random copolymer or a block copolymer.

The transparent polyimide resin film of the present invention has a low thermal expansion coefficient and a high glass transition temperature while exhibiting high transparency because it is produced using the polyamic acid solution.

Specifically, since the polyimide resin film of the present invention has a rigid chemical structure, when the thickness of the film is 10 占 퐉, the glass transition temperature is as high as 250 占 폚 or more and the coefficient of thermal expansion in the range of 50 to 250 占 폚 is about 22 the light transmittance at a wavelength of 550 nm is as high as not less than 90%, the yellow index (YI) at a wavelength of 550 nm is not more than 3.5, preferably not more than 20 ppm / It is as low as 3 or less. As described above, the polyimide resin film of the present invention having a low thermal expansion coefficient and a high glass transition temperature can suppress misalignment of display pixels, wiring, and the like on the substrate due to expansion and contraction of the substrate. Further, the polyimide resin film of the present invention can be applied to a flexible display due to high light transmittance and low yellowing.

In addition, since the transparent polyimide resin film contains an imide, it is excellent in heat resistance, chemical resistance, abrasion resistance, and electrical characteristics.

The method for producing the transparent polyimide resin film of the present invention is not particularly limited. For example, the polyamic acid solution is coated (cast) on a glass substrate, and then the temperature is gradually raised , Followed by imidization for 0.5 to 8 hours.

Examples of the coating method include spin coating, dip coating, solvent casting, slot die coating, and the like. , Spray coating, and the like, but are not limited thereto.

The thickness of the polyimide resin film is not particularly limited, but the polyamic acid solution may be coated one or more times so as to have a thickness of several hundreds of nm to several tens of micrometers.

The polyimide resin film of the present invention can be used in a variety of fields, and particularly, a display for an organic EL device (OLED), a display for a liquid crystal device, a TFT substrate, a flexible printed circuit board, a flexible printed circuit board, Can be utilized as substrates and protective films for flexible displays such as OLED surface light-emitting substrates and substrate materials for electron bombardment.

<Transparent Substrate>

The present invention provides a transparent substrate using the above-mentioned polyamic acid solution.

For example, the transparent substrate is formed by laminating one or more transparent polyimide resin films prepared by imidizing the above-described polyamic acid solution. Such a transparent substrate exhibits high transparency like a glass substrate and can have a low thermal expansion property.

Therefore, the transparent substrate of the present invention can be applied to various fields, and can be utilized as a substrate for a flexible display such as an OLED display and a liquid crystal display, which require high transparency and heat resistance.

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

[Example 1]

1-1. Preparation of transparent polyamic acid solution

N, N-dimethylacetamide (DMAc) (63.769 g, 84.15 wt%) was placed in a 150 ml three-necked round bottom flask, and the internal temperature of the flask was raised to 50 ° C. Thereafter, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 7.92 wt%) was added to the flask, (M-PDA) (0.22 g, 0.29 wt%) was added and stirred for 1 hour to completely dissolve 2,2'-TFDB and m-PDA. The flask was then charged with isophthaloyl dichloride (IPC) (0.7592 g, 1.00 wt%), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6-FDA) , 3.65 wt%) and pyromellitic dianhydride (PMDA) (2.265 g, 2.99 wt%) were sequentially added, and the mixture was cooled to 30 DEG C and dissolved. At this time, the solid content was 15%, and then the reaction was carried out with stirring for 3 hours. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a clear polyamic acid solution [solution viscosity at 25 ° C: 42 poise (4200 CPs)].

1-2. Preparation of transparent polyimide resin film

The transparent polyamic acid solution prepared in Example 1-1 was spin-coated on a glass for LCD, and then dried in a convection oven at 80 DEG C for 30 minutes, at 150 DEG C for 30 minutes, at 200 DEG C for 1 hour, at 300 DEG C for 1 And then imidization was carried out to prepare a transparent polyimide resin film (imidization ratio: 85%) having a thickness of 10 탆. Thereafter, the polyimide resin film was taken by etching the glass with hydrofluoric acid.

[Example 2]

2-1. Preparation of transparent polyamic acid solution

N, N-dimethylacetamide (DMAc) (68.858 g, 84.21 wt%) was placed in a 150 ml three-neck round bottom flask, and the internal temperature of the flask was raised to 50 ° C. Then, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 7.34 wt%) was added to the flask, Phenylenediamine (m-PDA) (0.497 g, 0.61 wt%) was added and stirred for 1 hour to completely dissolve 2,2'-TFDB and m-PDA. Thereafter, terephthaloyl chloride (TPC) (0.7592 g, 0.93 wt%), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6-FDA) 3.80 wt%) and pyromellitic dianhydride (PMDA) (2.545 g, 3.11 wt%) were sequentially added, and the mixture was cooled to 30 DEG C and dissolved. At that time, the solid content was 15%, and the reaction was carried out for 3 hours with stirring. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a transparent polyamic acid solution [solution viscosity at 25 캜: 75 poise (7500 CPs)].

2-2. Preparation of transparent polyimide resin film

A transparent polyimide resin film was produced in the same manner as in Example 1-2, except that the polyamic acid solution obtained in Example 2-1 was used in place of the polyamic acid solution used in Example 1-2.

[Example 3]

3-1. Preparation of transparent polyamic acid solution

N, N-dimethylacetamide (DMAc) (63.769 g, 84.15 wt%) was charged into a 150 ml three-neck round bottom flask, and then the internal temperature of the flask was raised to 50 ° C. Thereafter, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 7.92 wt%) was added to the flask, and after 30 minutes, Phenylenediamine (m-PDA) (0.220 g, 0.29 wt%) was added and stirred for 1 hour to completely dissolve 2,2'-TFDB and m-PDA. Thereafter, terephthaloyl chloride (TPC) (0.3796 g, 0.50 wt%), isophthaloyl dichloride (IPC) (0.3796 g, 0.50 wt%), 2,2- bis (3,4-dicarboxyphenyl) (2.768 g, 3.65 wt%) and pyromellitic dianhydride (PMDA) (2.265 g, 2.99 wt%) were sequentially added, followed by cooling to 30 ° C . At that time, the solid content was 15%, and the reaction was carried out for 3 hours with stirring. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a clear polyamic acid solution [solution viscosity at 25 ° C: 56 poise (5600 CPs)].

3-2. Preparation of transparent polyimide resin film

A transparent polyimide resin film was produced in the same manner as in Example 1-2, except that the polyamic acid solution obtained in Example 3-1 was used in place of the polyamic acid solution used in Example 1-2.

[Example 4]

4-1. Preparation of transparent polyamic acid solution

N, N-dimethylacetamide (DMAc) (66.636 g, 84.58 wt%) was placed in a 150 ml three-neck round bottom flask, and the internal temperature of the flask was raised to 50 캜. Thereafter, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 7.61 wt%) was added to the flask and after 30 minutes, m -Phenylenediamine (m-PDA) (0.110 g, 0.14 wt%) was added and stirred for 1 hour to completely dissolve 2,2'-TFDB and m-PDA. The flask was then charged with isophthaloyl dichloride (IPC) (0.3796 g, 0.48 wt%), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6-FDA) , 4.45 wt%) and pyromellitic dianhydride (PMDA) (2.150 g, 2.74 wt%) were sequentially added, and the mixture was cooled to 30 DEG C and dissolved. At that time, the solid content was 15%, and the reaction was carried out for 3 hours with stirring. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a transparent polyamic acid solution (solution viscosity at 47 ° C: 47 poise (4700 CPs)).

4-2. Preparation of transparent polyimide resin film

A transparent polyimide resin film was produced in the same manner as in Example 1-2, except that the polyamic acid solution obtained in Example 4-1 was used instead of the polyamic acid solution used in Example 1-2.

[Example 5]

5-1. Preparation of transparent polyamic acid solution

N, N-dimethylacetamide (DMAc) (63.769 g, 82.45 wt%) was placed in a 150 ml three-neck round bottom flask, and the internal temperature of the flask was raised to 50 ° C. Thereafter, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 7.75 wt%) was added, and after 30 minutes, Diamine (m-PDA) (0.497 g, 0.65 wt%) was added and stirred for 1 hour to completely dissolve 2,2'-TFDB and m-PDA. Thereafter, terephthaloyl chloride (TPC) (0.3796 g, 0.49 wt%), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6-FDA) 5.37 wt%), and pyromellitic dianhydride (PMDA) (2.545 g, 3.29 wt%) were sequentially added, and the mixture was cooled to 30 DEG C and dissolved. At that time, the solid content was 15%, and the reaction was carried out for 3 hours with stirring. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a transparent polyamic acid solution [solution viscosity at 25 占 폚: 60 poise (6000 CPs)].

5-2. Preparation of transparent polyimide resin film

A transparent polyimide resin film was produced in the same manner as in Example 1-2, except that the polyamic acid solution obtained in Example 5-1 was used in place of the polyamic acid solution used in Example 1-2.

[Comparative Example 1]

1-1. Preparation of polyamic acid solution

N, N-dimethylacetamide (DMAc) (77.295 g, 87.25 wt%) was placed in a 150 ml three-neck round bottom flask, and the internal temperature of the flask was raised to 50 캜. Then, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 6.77 wt%) was added to the flask and stirred for 1 hour To completely dissolve the 2,2'-TFDB. Thereafter, terephthaloyl chloride (TPC) (0.7592 g, 0.85 wt%), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6-FDA) 2.497 g and 2.81 wt%), and pyromellitic dianhydride (PMDA) (2.043 g, 2.32 wt%) were sequentially added, and the mixture was cooled to 30 DEG C and dissolved. At that time, the solid content was 15%, and the reaction was carried out for 3 hours with stirring. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a polyamic acid solution [solution viscosity at 25 ° C: 43.2 poise (4320 CPs)].

1-2. Production of polyimide resin film

A polyimide resin film was produced in the same manner as in Example 1-2, except that the polyamic acid solution obtained in Comparative Example 1-1 was used instead of the polyamic acid solution used in Example 1-2.

[Comparative Example 2]

2-1. Preparation of polyamic acid solution

N, N-dimethylacetamide (DMAc) (77.295 g, 87.25 wt%) was placed in a 150 ml three-neck round bottom flask, and the internal temperature of the flask was raised to 50 캜. Then, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFDB) (6 g, 6.77 wt%) was added to the flask and stirred for 1 hour To completely dissolve the 2,2'-TFDB. Then, to the flask was added isophthaloyl dichloride (IPC) (0.7592 g, 0.85 wt%), 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6-FDA) , 2.81 wt%) and pyromellitic dianhydride (PMDA) (2.043 g, 2.32 wt%) were sequentially added, and the mixture was cooled to 30 DEG C and dissolved. At that time, the solid content was 15%, and the reaction was carried out for 3 hours with stirring. After completion of the reaction between the monomers, the solution was naturally cooled to obtain a polyamic acid solution [solution viscosity at 25 캜: 29 poise (2900 CPs)].

2-2. Production of polyimide resin film

A polyimide resin film was produced in the same manner as in Example 1-2, except that the polyamic acid solution obtained in Comparative Example 2-1 was used in place of the polyamic acid solution used in Example 1-2.

[Experimental Example 1] Evaluation of physical properties of transparent polyimide resin film

The properties of the transparent polyimide resin films prepared in Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated as follows. The results are shown in Table 2 below.

1. Light transmittance and birefringence measurement

The measurement was performed at a viewing angle of 2 degrees with a C light source of ASTM E313-73 using a UV-Vis NIR Spectrophotometer and a birefringence measuring device (Retarder, Otsuka RETs-100) at a wavelength of 550 nm.

2. Measurement of Yellow Index (YI)

The yellowing at 550 nm was measured according to the ASTM E313 standard using a UV spectrometer (Kotikaminolta CM-3700d).

3. Coefficient of thermal expansion (CTE)

TMA (Perkin Elmer, Diamond TMA) was used to measure the thermal expansion coefficient at 50 to 300 ° C. twice at a rate of 10 ° C./min and a load of 100 mN. However, since the residual stress may remain in the film, the first test is carried out to remove the residual stress completely, and the results obtained from the second test are described.

4. Thickness measurement

A transparent polyamic acid solution was coated on a silicon wafer to a film thickness of 20 m or more, dried and imidized to synthesize a polyimide resin film. Then, a polyimide resin film was formed by using a non-contact refractive index measuring device (Elli-RP, Ellipso technology) The thickness of the film was measured at the wavelength.

content Example Comparative Example One 2 3 4 5 One 2 a component 6-FDA wt% 3.65 3.80 3.65 4.45 5.37 2.81 2.81 mol% 30 30 30 40 40 30 30 PMDA wt% 2.99 3.11 2.99 2.74 3.29 2.32 2.32 mol% 50 50 50 50 50 50 50 Component b IPC wt% 1.00 - 0.50 0.48 - - 0.85 mol% 20 - 10 10 - - 20 TPC wt% - 0.93 0.50 - 0.49 0.85 - mol% - 20 10 - 10 20 - Component c
2,2-TFDB wt% 7.92 7.34 7.92 7.61 7.75 6.77 6.77 mol% 90 80 90 95 80 100 100 m-PDA wt% 0.29 0.61 0.29 0.14 0.65 - - mol% 10 20 10 5 20 - - component d DMAc wt% 84.15 84.21 84.15 84.58 82.45 87.25 87.25 a: aromatic dianhydride
b: dicarbonyl compound
c: aromatic diamine
d: organic solvent

Thickness (㎛) Permeability (%) Y.I. CTE (ppm / ° C) Example 1 22 90.7 2.6 19.8 Example 2 21 90.2 2.8 9.6 Example 3 23 90.0 2.9 19.5 Example 4 21 91.0 2.5 15.7 Example 5 22 90.1 3.0 10.2 Comparative Example 1 25 88.0 3.9 25.1 Comparative Example 2 23 90.0 3.1 31.5

As a result of the experiment, it was confirmed that the colorless transparent polyimide resin films of Examples 1 to 5 had a trade-off relationship that the colorless transparency was high and the thermal expansion properties were low.

The colorless transparent polyimide resin films of Examples 1 to 5 had a YI value of 3 or less and a thermal expansion coefficient at 50 to 300 占 폚 of 20 ppm / 占 폚 or less, and were excellent in optical characteristics and thermal properties as compared with Comparative Examples .

As described above, since the polyimide resin film prepared using the polyamic acid solution according to the present invention has high light transmittance, low yellowing degree, and low thermal expansion coefficient, it can be applied to a flexible display material, a substrate, or a protective film I could.

Claims (7)

(a) comprising a fluorinated aromatic dianhydride and a pyromellitic dianhydride (PMDA) comprising 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6-FDA) Aromatic dianhydrides containing non-fluorinated aromatic dianhydride;
(b) a dicarbonyl compound;
(c) an aromatic diamine containing a fluorinated aromatic diamine including 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and m-phenylenediamine; And
(d) an organic solvent,
The content of the fluorinated aromatic diamine and the m-phenylenediamine is in the range of 80 to 95 mol% and 5 to 20 mol%, respectively, based on 100 mol% of the aromatic diamine,
Wherein the viscosity is in the range of 3,000 to 70,000 cps. The method according to claim 1,
Wherein the mixing ratio of the fluorinated aromatic dianhydride to the non-fluorinated aromatic dianhydride is 20 to 95: 80 to 5 molar ratio. The method according to claim 1,
Wherein the content of the dicarbonyl compound is 10 to 70 mol% based on 100 mol% of the sum of the aromatic dianhydride and the dicarbonyl compound. The method according to claim 1,
The dicarbonyl compound may be selected from the group consisting of p-terephthaloyl chloride (TPC), isophthaloyl dichloride (IPC), terephthalic acid and 1,3-adamantanedicarbonyl di (1,3-adamantanedicarbonyl dichloride). &Lt; Desc / Clms Page number 13 &gt; The method according to claim 1,
Wherein the molar ratio [c / (a + b)] of the mixture of the aromatic dianhydride (a) and the dicarbonyl compound (b) to the aromatic diamine (c) is 0.9 to 1.1. . A transparent polyimide resin film produced by imidizing the transparent polyamic acid solution according to any one of claims 1 to 5. A transparent substrate comprising the transparent polyimide resin film according to claim 6.