JP7112476B2 - Transparent polyimide resin film using polyimide-forming composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transparent polyimide resin film produced using a composition for forming polyimide , which is applicable to flexible display devices.

Polyimide (PI) resin is an insoluble and infusible ultra-high heat-resistant resin, and has excellent electrical, chemical, thermal, and mechanical properties. It is widely used as heat-resistant advanced materials such as spacecraft materials, and electronic materials such as insulating coating agents, insulating films, semiconductors, and LCD electrode protective films.

As a method for synthesizing such a polyimide resin, generally, a dianhydride and a diamine are polymerized in an organic solvent to prepare a polyamic acid solution, which is then cured by heat treatment to prepare a film. Alternatively, after chemical imidization, immersion, washing, re-dissolution, etc. are performed to produce a film.

First, the method of preparing a polyimide resin film by curing a polyamic acid solution by heat treatment includes heating at a high temperature of 250 to 400° C. for several hours. Since the resin is colored in the process, the transmittance and yellowness in the visible light range are lowered, making it difficult to use as an optical material that requires transparency. On the other hand, heating at a low temperature prolongs the time required to produce the polyimide resin film and lowers the molecular weight of the polyamic acid, resulting in a problem of reduced strength of the produced polyimide resin film.

In addition, the method of chemically imidizing a polyamic acid solution to produce a polyimide resin film includes adding xylene, toluene, or the like to the polyamic acid solution and imidizing by the Dean Stark method, or polyamic It includes a process of adding a catalyst such as pyridine and a dehydrating agent such as acetic anhydride to an acid solution and imidizing at a low temperature. However, the chemical imidization method requires a separate Dean-Stark apparatus, or requires processes such as immersion, washing, drying, and redissolution after imidization, resulting in a complicated process. However, there is a problem that a large amount of waste water is generated.

Therefore, there is a demand for the development of a polyamic acid solution for producing a transparent polyimide resin film exhibiting high transparency and excellent thermal and mechanical properties by a relatively simple process.

The present invention adopts a dianhydride monomer and a diamine monomer having a specific structure, adjusts their content to a specific range, and uses a catalyst having a boiling point within a specific range to The object is to produce a transparent polyimide film that can be cured to achieve a low YI (Yellow Index) and high light transmittance and to adjust mechanical properties.

The present invention also provides a transparent polyimide film that can be applied to plastic transparent substrates for LCD and OLED flexible display devices, TFT substrates, flexible printed circuit substrates, flexible OLED surface lighting substrates, electronic paper substrate materials, and the like. purpose.

In order to achieve the above object, the present invention provides (a) a diamine represented by the following chemical formula (1), a diamine represented by the following chemical formula (2), a diamine represented by the following chemical formula (2A), and 2, 2 a diamine mixture containing one or more diamines selected from the group consisting of '-dimethylbiphenyl-4,4'-diamine ; (b) a dianhydride represented by the following chemical formula (3); (c) a basic catalyst that is one or more selected from the group consisting of 2-methylpiperazine, 4-tert-butylpyridine, and 2,3,5-collidine ; and (d) an organic solvent; is produced by imidizing a polyimide-forming composition excluding a dehydrating agent, and satisfies the following physical property conditions (i) to (v) to provide a transparent polyimide resin film .
At a film thickness of 10 μm or less,
(i) a light transmittance of 88% or more at a wavelength of 550 nm;
(ii) a yellowness index of 5.0 or less according to the standard of ASTM E313;
(iii) haze is 1.0 or less,
(iv) an elastic modulus in the range of 3 to 6 GPa;
(v) Tensile strength is in the range of 120-200 MPa.

（前記化学式（１）中、
Ａは、単結合、－Ｃ（＝Ｏ）－、及び－Ｃ（＝Ｏ）ＮＨ－、並びにハロゲン、又はハロゲン原子で置換されたＣ _１ ～Ｃ _６ のアルキル基で置換されたＣ_６～Ｃ_２０のアリーレン基からなる群から選択され、
Ｘ_１及びＸ_２は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ_１～Ｃ_６のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基からなる群から選択され、
但し、Ａが単結合である場合、Ｘ_１及びＸ_２のうちの少なくとも１つ以上は、ハロゲン、またはハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基であり、
ｍは、０～２の整数である。）

(In the above chemical formula (1),
A is a single bond, -C(=O)- and -C(=O)NH-, and _{C6 -} C substituted with a halogen or a C1 _- C6 alkyl group substituted with a halogen atom selected from the group consisting of ₂₀ arylene groups,
X ₁ and X ₂ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ -C ₆ alkyl group, and a C ₁ -C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; is selected from the group consisting of
provided that when A is a single bond, at least one of X ₁ and X ₂ is a halogen or a C ₁ to C ₆ alkyl group substituted with a halogen atom ;
m is an integer from 0 to 2; )

（前記化学式（２）中、
Ｂ _１ は、Ｃ _１～Ｃ_６のアルキレン基、１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキレン基、－Ｏ－、－Ｓ－、－Ｓ（＝Ｏ）_２－、－Ｃ（＝Ｏ）ＮＨ－、及びＣ _１ ～Ｃ _６ のアルキル基で置換または非置換されたＣ_６～Ｃ_２０のアリーレン基からなる群から選択され、
Ｘ_３及びＸ_４は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ_１～Ｃ_６のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基からなる群から選択される。）

（前記化学式（２Ａ）中、
Ｂ _２ は、単結合、Ｃ _１ ～Ｃ _６ のアルキレン基、１つ以上の水素がハロゲン原子で置換されたＣ _１ ～Ｃ _６ のアルキレン基、及びＣ _１ ～Ｃ _６ のアルキル基で置換または非置換されたＣ _６ ～Ｃ _２０ のアリーレン基からなる群から選択され、
Ｘ _３ 及びＸ _４ は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ _１ ～Ｃ _６ のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ _１ ～Ｃ _６ のアルキル基からなる群から選択される。）

（前記化学式（３）中、
Ｃは、４価のＣ_６～Ｃ_２０の芳香族環基、及び４価のＣ_４～Ｃ_２０の脂肪族環基からなる群から選択され、
前記４価のＣ_６～Ｃ_２０の芳香族環基は、Ｃ_１～Ｃ_６のアルキル基で置換されることがあり、
前記Ｃは、複数個の環であることができ、複数個の環は、互いに同一または異なり、複数個の環同士が、－Ｃ（＝Ｏ）ＮＨ－、及び－Ｃ（＝Ｏ）－Ｏ－からなる群から選択される１種以上の連結基を介して連結されている。）

（前記化学式（４）中、
Ｄは、Ｃ_１～Ｃ_６のアルキレン基、１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキレン基、－Ｏ－、－Ｓ－、－Ｃ（＝Ｏ）－、及び－Ｓ（＝Ｏ）_２－からなる群から選択され、
Ｘ_５及びＸ_６は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ_１～Ｃ_６のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基からなる群から選択され、
ｎは、１～３の整数である。）

(In the above chemical formula (2),
B ₁ is a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are substituted with halogen atoms, —O — , —S—, —S(=O) ₂ — , —C(═O)NH—, and a C ₆ to C ₂₀ arylene group substituted or unsubstituted with a C ₁ to C ₆ alkyl group,
X ₃ and X ₄ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ to C ₆ alkyl group, and a C ₁ to C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; selected from the group consisting of )

(In the chemical formula (2A),
B ₂ is a single bond, a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are replaced with halogen atoms , and a C ₁ to C ₆ alkyl group substituted or unsubstituted selected from the group consisting of substituted C6 _{- C20} arylene groups;
X ₃ and X ₄ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ to C ₆ alkyl group, and a C ₁ to C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; selected from the group consisting of )

(In the above chemical formula (3),
C is selected from the group consisting of a tetravalent C6- _C20 aromatic cyclic group and a tetravalent _{C4 - C20} aliphatic cyclic group;
the tetravalent C ₆ to C ₂₀ aromatic ring group may be substituted with a C ₁ to C ₆ alkyl group;
The C may be a plurality of rings, the plurality of rings are the same or different, and the plurality of rings are -C(=O)NH- and -C(=O)-O It is linked via one or more linking groups selected from the group consisting of - . )

(In the above chemical formula (4),
D is a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are substituted with halogen atoms, —O—, —S—, —C(=O)—, and -S(=O) ₂ - is selected from the group consisting of
X ₅ and X ₆ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ -C ₆ alkyl group, and a C ₁ -C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms is selected from the group consisting of
n is an integer of 1-3. )

Furthermore, the present invention provides a transparent substrate including the transparent polyimide resin film.

According to the present invention, by adopting a diamine monomer and a dianhydride monomer having a specific structure, adjusting their contents within a specific range, and using a catalyst having a boiling point within a specific range, , it is possible to provide a transparent polyimide resin film having excellent optical properties, mechanical properties, thermal properties, etc. at the same time.

Further, according to the present invention, by applying the transparent polyimide resin film having excellent optical properties, mechanical properties, thermal properties, etc. to a substrate, a flexible display device exhibiting excellent physical properties and product reliability can be obtained. A transparent substrate can be provided.

The present invention will be described in detail below. However, the examples described below are merely examples, and the present invention is not limited to these examples, and the scope of the present invention is indicated by the claims described below.

< Transparent polyimide resin film >
The transparent polyimide resin film according to the present invention has improved mechanical properties and thermal properties while maintaining high transparency and excellent optical properties . (a) A diamine represented by the following chemical formula (1) and one or more diamines selected from the group consisting of a diamine represented by the following chemical formula (2), a diamine represented by the following chemical formula (2A), and 2,2′-dimethylbiphenyl-4,4′-diamine; (b) a dianhydride mixture containing a dianhydride represented by the following chemical formula (3) and a dianhydride represented by the following chemical formula (4); (c) 2-methylpiperazine, 4-tert-butyl pyridine, and a basic catalyst that is one or more selected from the group consisting of 2,3,5-collidine ; and (d) an organic solvent; It is produced and satisfies the following physical property conditions (i) to (v).
At a film thickness of 10 μm or less,
(i) a light transmittance of 88% or more at a wavelength of 550 nm;
(ii) a yellowness index of 5.0 or less according to the standard of ASTM E313;
(iii) haze is 1.0 or less,
(iv) an elastic modulus in the range of 3 to 6 GPa;
(v) Tensile strength is in the range of 120-200 MPa.

(a) diamine mixture
The polyimide-forming composition contains , as diamine components, a diamine represented by the following chemical formula (1) and a diamine represented by the following chemical formula (2).

（前記化学式（１）中、
Ａは、単結合、－Ｃ（＝Ｏ）－、及び－Ｃ（＝Ｏ）ＮＨ－、並びにハロゲン、又はハロゲン原子で置換されたＣ _１ ～Ｃ _６ のアルキル基で置換されたＣ_６～Ｃ_２０のアリーレン基からなる群から選択され、
Ｘ_１及びＸ_２は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ_１～Ｃ_６のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基からなる群から選択され、
但し、Ａが単結合である場合、Ｘ_１及びＸ_２のうちの少なくとも１つ以上は、ハロゲン、またはハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基であり、
ｍは、０～２の整数である。）

(In the above chemical formula (1),
A is a single bond, -C(=O)- and -C(=O)NH-, and _{C6 -} C substituted with a halogen or a C1 _- C6 alkyl group substituted with a halogen atom selected from the group consisting of ₂₀ arylene groups,
X ₁ and X ₂ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ -C ₆ alkyl group, and a C ₁ -C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; is selected from the group consisting of
provided that when A is a single bond, at least one of X ₁ and X ₂ is a halogen or a C ₁ to C ₆ alkyl group substituted with a halogen atom ;
m is an integer from 0 to 2; )

（前記化学式（２）中、
Ｂ _１ は、Ｃ _１～Ｃ_６のアルキレン基、１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキレン基、－Ｏ－、－Ｓ－、－Ｓ（＝Ｏ）_２－、－Ｃ（＝Ｏ）ＮＨ－、及びＣ _１ ～Ｃ _６ のアルキル基で置換または非置換されたＣ_６～Ｃ_２０のアリーレン基からなる群から選択され、
Ｘ_３及びＸ_４は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ_１～Ｃ_６のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基からなる群から選択される。）

(In the above chemical formula (2),
B ₁ is a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are substituted with halogen atoms, —O — , —S—, —S(=O) ₂ — , —C(═O)NH—, and a C ₆ to C ₂₀ arylene group substituted or unsubstituted with a C ₁ to C ₆ alkyl group,
X ₃ and X ₄ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ to C ₆ alkyl group, and a C ₁ to C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; selected from the group consisting of )

(In the chemical formula (2A),
B. ₂ is a single bond, C ₁ ～C ₆ C ₁ ～C ₆ The alkylene group of, and C ₁ ～C ₆ C substituted or unsubstituted with an alkyl group of ₆ ～C ₂₀ is selected from the group consisting of an arylene group of
X ₃ and X ₄ are the same or different from each other and each independently hydrogen, halogen, C ₁ ～C ₆ and C in which one or more hydrogens have been replaced with halogen atoms ₁ ～C ₆ are selected from the group consisting of alkyl groups of )

According to one preferred example of the present invention, said X ₁ and X ₄ can be electron withdrawing groups (Electron Withdrawing Group, EWG) well known in the art, each independently fluorine (F) or CF ₃ is preferred.

Also, A may be a C ₆ -C ₂₀ arylene group well known in the art, and specific examples thereof include phenylene, biphenylene, triphenylene, and the like. In particular, A is preferably selected from the group of substituents represented by the following chemical formula (5).

前記化学式（５）中、＊は、前記化学式（１）における連結部位である。また、Ｒ_１～Ｒ_３は、互いに同一または異なり、それぞれ独立に、Ｆ、及びＣＦ_３からなる群から選択される。

In the chemical formula (5), * is a linking site in the chemical formula (1). R ₁ to R ₃ are the same or different and each independently selected from the group consisting of F 3 and CF ₃ .

In the above chemical formula (1), by introducing at least one electron-withdrawing group (EWG) such as fluorine (F) or _CF3 , inter-chain and intra-chain charge transfer complexes (Change Transfer Complex, CTC) ) can improve the transparency of the polyimide resin.

In the present invention, the diamine represented by the chemical formula (1) includes 2,2′-bis(trifluoromethyl)biphenyl-4,4′-diamine (TFDB), 4-amino-N-(4-aminophenyl ) benzamine, bis(4-aminophenyl)methanone, etc., but not limited thereto. However, diamines containing a fluorinated biphenyl structure can improve thermal properties by achieving a high glass transition temperature and low thermal expansion while controlling reactivity with dianhydrides. For example, when TFDB is used, the transmittance and glass transition temperature of the polyimide resin can be increased and the thermal expansion coefficient can be decreased.

The content of the diamine represented by the chemical formula (1) is not particularly limited, but may be 50 to 99.9 mol%, preferably 70 to 99 mol%, based on 100 mol% of the diamine mixture. in mol %. When the diamine represented by the chemical formula (1) is contained within the above range, optical properties can be further improved due to the effect of charge transfer between substituent groups in the monomer.

In the present invention, the diamine represented by the chemical formula (2) or the chemical formula (2A) includes 4,4′-oxydibenzenamine (4,4′-ODA), 3,4-oxydibenzenamine (3 ,4′-ODA), 3,3′-oxydibenzenamine (3,3′-ODA), 4,4′-oxy(3-(trifluoromethyl)benzenamine) (FODA), 4,4′ -(1,4-phenylenebis(oxy))bis(3-(trifluoromethyl)benzenamine) (FAPB), 4,4′-(perfluoropropane-2,2′-diyl)dibenzenamine, 4 ,4′-(2,2′-(1,4-phenylene)bis(1,1,1,3,3,3-hexafluoropropane-2,2-diyl)dibenzenamine, 4,4′- Sulfonyldibenzenamine (4,4'-DDS), 4,4'-(4,4'-(perfluoropropane-2,2-diyl)bis(4,1-phenylene))bis(oxy)dibenzene Amine, 4,4'-(4,4'-sulfonylbis(4,1-phenylene)bis(oxy))dibenzenamine, 4,4'-(1,4-phenylenebis(oxy))dibenzenamine , 4,4′-(4,4′-(propane-2,2-diyl)bis(4,1-phenylene))bis(oxy)dibenzenamine, etc. but not limited to, such diamines represented by formula ( ₂ ) can be monomers containing phenyl, biphenyl, sulfone group (SO2), silane group, etc. 4,4 When using '-ODA, FODA, FAPB, DABA (4,4'-Diaminobenzanilide), 4,4'-DDS, or 4,4'-(perfluoropropane-2,2'-diyl)dibenzenamine can further improve the optical properties without lowering the thermal properties of the polyimide resin.

The total content of the diamine represented by the chemical formula (2) , the diamine represented by the chemical formula (2A) , and 2,2′-dimethylbiphenyl-4,4′-diamine (m-Tolidine) is not particularly limited. , 0.01 to 50 mol %, preferably 0.1 to 30 mol %, relative to 100 mol % of the diamine mixture. One or more selected from the group consisting of the diamine represented by the chemical formula (2), the diamine represented by the chemical formula (2A), and 2,2′-dimethylbiphenyl-4,4′-diamine (m-Tolidine) When the diamine is contained within the above range, optical properties (light transmittance and yellowness) can be further improved.

The (a) diamine according to the present invention uses TFDB as the diamine represented by the chemical formula (1) in consideration of the high transparency and low yellowness of the polyimide resin, and is represented by the chemical formula (2). As one or more diamines selected from the group consisting of diamines, diamines represented by the chemical formula (2A), and 2,2'-dimethylbiphenyl-4,4'-diamine (m-Tolidine) , m-Tolidine, 4 , 4′-ODA, FODA, FAPB, DABA, 4,4′-DDS or 4,4′-(perfluoropropane-2,2′-diyl)dibenzenamine are preferably used in combination.

(b) Dianhydride Mixture The polyimide-forming composition according to the present invention contains a dianhydride represented by the following chemical formula (3) and a dianhydride represented by the following chemical formula (4) as dianhydride components.

（前記化学式（３）中、
Ｃは、４価のＣ_６～Ｃ_２０の芳香族環基、及び４価のＣ_４～Ｃ_２０の脂肪族環基からなる群から選択され、
前記４価のＣ_６～Ｃ_２０の芳香族環基は、Ｃ_１～Ｃ_６のアルキル基で置換されることがあり、
前記Ｃは、複数個の環であることができ、複数個の環は、互いに同一または異なり、複数個の環同士が、－Ｃ（＝Ｏ）ＮＨ－、及び－Ｃ（＝Ｏ）－Ｏ－からなる群から選択される１種以上の連結基を介して連結されている。）

(In the above chemical formula (3),
C is selected from the group consisting of a tetravalent C6- _C20 aromatic cyclic group and a tetravalent _{C4 - C20} aliphatic cyclic group;
the tetravalent C ₆ to C ₂₀ aromatic ring group may be substituted with a C ₁ to C ₆ alkyl group;
The C may be a plurality of rings, the plurality of rings are the same or different, and the plurality of rings are -C(=O)NH- and -C(=O)-O It is linked via one or more linking groups selected from the group consisting of - . )

（前記化学式（４）中、
Ｄは、Ｃ_１～Ｃ_６のアルキレン基、１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキレン基、－Ｏ－、－Ｓ－、－Ｃ（＝Ｏ）－、及び－Ｓ（＝Ｏ）_２－からなる群から選択され、
Ｘ_５及びＸ_６は、互いに同一または異なり、それぞれ独立に、水素、ハロゲン、Ｃ_１～Ｃ_６のアルキル基、及び１つ以上の水素がハロゲン原子で置換されたＣ_１～Ｃ_６のアルキル基からなる群から選択され、
ｎは、１～３の整数である。）

(In the above chemical formula (4),
D is a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are substituted with halogen atoms, —O—, —S—, —C(=O)—, and -S(=O) ₂ - is selected from the group consisting of
X ₅ and X ₆ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ -C ₆ alkyl group, and a C ₁ -C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms is selected from the group consisting of
n is an integer of 1-3. )

According to a preferred example of the present invention, C is a tetravalent hydrocarbon ring group well known in the art, and the hydrocarbon ring group includes, for example, a C ₆ to C ₂₀ aromatic ring group, or a C ₄ to C ₄₀ aliphatic cyclic group. C is preferably a tetravalent 6-membered aromatic ring group or a tetravalent 6-membered alicyclic ring group. When C is a tetravalent 6-membered aromatic ring group, the dianhydride represented by the chemical formula (3) is an aromatic dianhydride containing a diamine structure, and C is a tetravalent 6-membered aliphatic ring. If a group, the dianhydride of formula (3) can be a non-aromatic dianhydride containing a diamine structure.

The C may be a plurality of rings, the plurality of rings are the same or different, and the plurality of rings are -C(=O)-, -C(=O)NH-, - It is linked via one or more linking groups selected from the group consisting of C(=O)-O- and -S(=O) ₂ -.

For example, when C is a tetravalent 6-membered aromatic ring group, one or more C ₆ to C ₄₀ arylene groups, sulfone groups, or arylene groups and sulfone groups known in the art are linked. can be in the form Specific examples include phenylene, biphenylene, triphenylene, sulfonyldiphenylene, and the like. In particular, C is preferably selected from the group of substituents represented by the following chemical formula (6).

前記化学式（６）中、＊は、前記化学式（３）における連結部位であり、Ｒ_４～Ｒ_６は、互いに同一または異なり、それぞれ独立に、水素、またはＣ_１～Ｃ_６のアルキル基である。好ましくは、それぞれ独立に、水素、またはメチル基であることができる。

In the chemical formula (6), * is a linking site in the chemical formula (3), and R ₄ to R ₆ are the same or different and each independently represents hydrogen or a C ₁ to C ₆ alkyl group. . Preferably, each independently can be hydrogen or a methyl group.

The dianhydride represented by the chemical formula (3) is resistant to external impact without being decomposed by heat or light by introducing an arylene group and/or a sulfone group having a rigid structure between the dianhydrides. Since it is stable, the optical properties, thermal properties, mechanical properties, etc. of the polyimide resin produced using it are significantly improved. In addition, the compound represented by the chemical formula (3) reacts with oxygen atoms in other dianhydride monomers by introducing an amide group (-C(=O)-NH-) between dianhydrides. As a result, hydrogen bonds are formed and a certain bonding force is generated in the main chain of the polymer, which significantly improves the mechanical properties and heat resistance of the polyimide resin.

In addition, when the C is a tetravalent six-membered aliphatic ring group, there is no π electron in the structure of the compound, so by controlling the formation of a charge transfer complex (CTC), the polyimide resin has a high transparency. And it comes to play a big role in realization of low yellowness.

Examples of the dianhydride represented by the chemical formula (3) include 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA). , 1,2,3,4-cyclopentanetetracarboxylic dianhydride (CPBA), bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, bicyclo[2. 2.2] Oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 3,3′,4,4′-biphenyltetracarboxylic dianhydride (S-BPDA), 2, 3,3′,4′-biphenyltetracarboxylic dianhydride (a-BPDA), pyromellitic dianhydride (PMDA), N,N′-(4,4′-sulfonylbis(4,1-phenylene )) bis(1,3-dioxo-octahydroisobenzofuran-5-carboxamide) and the like, but not limited thereto.

The content of the dianhydride represented by the chemical formula (3) is not particularly limited, but can be 10 to 95 mol%, preferably 50 to 90 mol, relative to 100 mol% of the dianhydride mixture. %. When the dianhydride represented by the chemical formula (3) is contained within the range described above, the polyimide resin can maintain high light transmittance and yellowness and can have a low coefficient of thermal expansion.

Also, according to a preferred example of the present invention, X ₅ and X ₆ can be electron-withdrawing groups (EWG) well known in the art, each independently fluorine (F) or CF ₃ Preferably.

Examples of the dianhydride represented by the chemical formula (4) include 5,5′-(perfluoropropane-2,2-diyl)diisobenzofuran-1,3-dione (6-FDA), 5,5′-oxy Diisobenzofuran-1,3-dione (ODPA), 5,5′-sulfonyldiisobenzofuran-1,3-dione (DSDA), Benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (BTDA) and the like, but not limited to these. When 6FDA is used, the transparency of the polyimide resin can be improved by controlling the formation of inter- and intra-molecular charge transfer complexes (CTC).

The content of the dianhydride represented by the chemical formula (4) is not particularly limited, but may be 5 to 90 mol%, preferably 10 to 50 mol%, based on 100 mol% of the dianhydride. is.

As described above, in one example of the present invention, the diamine represented by the chemical formula (1) and the diamine represented by the chemical formula (2) are used as the diamine components, and the diamine represented by the chemical formula (3) is used as the dianhydride component. The hydride and the dianhydride represented by the chemical formula (4) are mixed and used. At this time, (a) the diamine mixture and (b) the dianhydride mixture improve the yellowness and mechanical properties of the polyimide resin. Therefore, (a):(b) can be mixed at a weight ratio of 1:0.1 to 10.

(c) Basic catalyst The basic catalyst is a basic catalyst having a boiling point of 140 to 200°C, such as 4-tert-butylpyridine, 4-ethylpyridine, 2-methylpiperazine, 2,6-dimethyl piperazine, 4-tert-butylpyridine, 2-propylpyridine, 4-propylpyridine, 2,3,5-collidine, 2,5-lutidine, 2,6-lutidine, 2,3-lutidine, 4-diazabicyclo[2 .2.2] octane, 3-ethylpyridine, 3-picoline, 2,3-dimethylpyrazine, 2,5-dimethylpyrazine and the like, and these may be used alone or in combination of two or more. can.

In addition, when the boiling point of the basic catalyst is less than 140° C., it becomes difficult to form a film. On the other hand, if the boiling point exceeds 200° C., it becomes difficult to remove the catalyst at the curing temperature of the present invention, and when the curing temperature is raised to remove the catalyst, optical properties are impaired.

(d) Organic Solvent The solvent for synthesizing the polyimide-forming composition is not particularly limited as long as it is well known in the art. Examples of the solvent include m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone, diethyl acetate, dimethyl phthalate (DMP), and the like. Polar solvents, low boiling point solvents such as tetrahydrofuran (THF) and chloroform, low absorption solvents such as γ-butyrolactone, and the like can be mentioned, and these can be used alone or in combination of two or more.

In the polyimide- forming composition according to the present invention as described above, the contents of the diamine mixture, the dianhydride mixture, the catalyst, and the organic solvent are not particularly limited, but are , (a) 1-20% by weight of a diamine mixture, (b) 1-20% by weight of a dianhydride mixture, (c) a catalyst content well known in the art, such as about 0.01-20% by weight, specifically typically about 0.01 to 15% by weight, more particularly about 0.1 to 10% by weight, and (d) the balance being organic solvent. Here, if the content of each component in the polyimide-forming composition is less than the above range, the viscosity of the polyimide-forming composition may become too low. can make the viscosity of the polyimide-forming composition too high. Therefore, by adjusting the content of each component in the polyimide-forming composition according to the present invention within the above range, the polyimide-forming composition can be obtained from about 1,000 to 500,000 cps, preferably about 10,000 cps 000 to 200,000 cps. In addition, when the viscosity of the polyimide-forming composition is within the above range, the thickness of the polyimide-forming composition can be easily adjusted during coating, and the surface of the coating film to be coated can be formed uniformly. Become so.

On the other hand, the polyimide-forming composition according to the present invention may optionally contain a plasticizer, an antioxidant, a flame retardant, a dispersant, a viscosity modifier, and a Additives such as leveling agents may be included in minor amounts.

A polyamic acid can be obtained by carrying out a solution polymerization reaction of the polyimide-forming composition according to the present invention as described above. Specifically, after dissolving the diamine represented by the chemical formula (1) and the diamine represented by the chemical formula (2) in an organic solvent, the dianhydride represented by the chemical formula (3) and the chemical formula (4) ) is added and then a solution polymerization reaction is performed to obtain a polyamic acid. At this time, the reaction conditions are not particularly limited, but the reaction can be carried out at -20 to 80°C for 1 to 12 hours (preferably 1 to 3 hours).

In addition, the polyimide resin may be in the form of a random copolymer or a block copolymer.

Since the transparent polyimide resin film according to the present invention is produced using the polyimide-forming composition, it has optical properties (transparency and yellowness) and improved mechanical properties (elasticity, strength). Excellent thermal properties (thermal expansion coefficient and glass transition temperature) can be expected. Specifically, the transparent polyimide resin film according to the present invention has a light transmittance of 88% or more at a wavelength of 550 nm, a yellowness index (YI) at a wavelength of 550 nm of 5.0 or less, and a haze ( Haze) is 1.0 or less, elastic modulus (Modulus) is 3 to 6 GPa, and mechanical strength (Strength) is 120 to 200 MPa.

Moreover, since the transparent polyimide resin film according to the present invention contains imide groups, it is excellent in heat resistance, chemical resistance, abrasion resistance, and electrical properties.

The method for producing such a transparent polyimide resin film is not particularly limited. A polyimide resin film can be produced by performing an imidization reaction (imidation) for 1 to 12 hours while gradually raising the temperature in the range of .

As the coating method, methods known in the art can be used without limitation, such as spin coating, dip coating, solvent casting, and slot die coating. (Slot die coating), spray coating, and the like.

The thickness of the transparent polyimide resin film is not particularly limited, but can be adjusted by coating the polyimide-forming composition one or more times so as to be several hundred nanometers to several tens of micrometers.

Such transparent polyimide resin films can be used in various fields, and in particular, organic EL element (OLED) displays, liquid crystal element displays, TFT substrates, and flexible printed circuits that require high transparency and heat resistance. It can be used as a substrate, a flexible OLED surface lighting substrate, a flexible display device substrate such as a substrate material for electronic paper, and a protective film.

Hereinafter, the present invention will be described in detail based on examples and comparative examples, but the present invention is not limited by the examples and comparative examples described later.

[Example 1]
1-1. Preparation of Polyimide-Forming Composition A 1500 ml three-necked round-bottomed flask was charged with 640.016 g of N,N-dimethylacetamide (DMAc), and the temperature of the flask was raised to 50.degree. Next, 85.0 g of 2,2′-bis(trifluoromethyl)biphenyl-4,4′-diamine (TFDB) was added to the flask, and after 60 minutes, 2,2′-dimethylbiphenyl-4,4 1.743 g of '-diamine (m-Tol) was added. This was stirred for 1 hour to completely dissolve TFDB and m-Tol. Next, 45.615 g of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 5,5′-(perfluoropropane-2,2-diyl)diisobenzofuran-1 were added to the fresco. , 3-dione (6FDA) (18.235 g) was sequentially added and dissolved. At this time, the solid content was 15%, and the reaction was then stirred for 5.5 hours. After confirming the completion of the reaction between the monomers by checking whether the viscosity increased, 37 g of 4-tert-butylpyridine was gradually added and stirred for 4.5 hours. Next, it was naturally cooled to obtain a polyimide-forming composition (solution viscosity at 25° C.: 85000 CPs).

1-2. Production of transparent polyimide resin film Example 1, 1-1. After coating the polyimide-forming composition obtained in , using a bar coater on a glass plate for LCD, in a convection oven under a nitrogen atmosphere, at 80 ° C. for 30 minutes, at 150 ° C. for 30 minutes, The film was dried at 200° C. for 1 hour and then at 280° C. for 1 hour while gradually raising the temperature stepwise to carry out an imidization reaction. As a result, a transparent polyimide resin film (imidation rate: 85% or more) having a thickness of 52 μm was obtained. Next, the film was separated from the glass plate to obtain a transparent polyimide resin film.

[Example 2]
2-1. Production of Polyimide-Forming Composition 1-1 of Example 1 above. A polyimide-forming composition (solution viscosity at 25° C.: 85000 CPs) was obtained in the same manner as above.

2-2. Production of transparent polyimide resin film In a nitrogen atmosphere, dry in a convection oven at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 320°C for 1 hour while gradually increasing the temperature. , 1-2. of Example 1, except that the imidization reaction is performed. was produced in the same manner as

[Example 3]
3-1. Production of Polyimide-Forming Composition 1-1 of Example 1 above. A polyimide-forming composition (solution viscosity at 25° C.: 85000 CPs) was obtained in the same manner as above.

3-2. Production of transparent polyimide resin film In a nitrogen atmosphere, dry in a convection oven at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 350°C for 1 hour while gradually increasing the temperature. , 1-2. of Example 1, except that the imidization reaction is performed. was produced in the same manner as

[Example 4]
4-1 Production of Polyimide-Forming Composition The procedure of 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 79000 CPs) was obtained in the same manner as above.

4-2. Production of transparent polyimide resin film Example 1, 1-2. was produced in the same manner as

[Example 5]
5-1. Preparation of Polyimide-Forming Composition 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 82000 CPs) was obtained in the same manner as above.

5-2. Production of transparent polyimide resin film Example 1, 1-2. Instead of the polyimide-forming composition used in 5-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 6]
6-1. 1-1. of Example 1 except that 2-methylpiperazine was used instead of 4-tert- butylpyridine . A polyimide-forming composition (solution viscosity at 25° C.: 81000 CPs) was obtained in the same manner as above.

6-2. Production of transparent polyimide resin film Example 1, 1-2. 6-1. of Example 6 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 7]
7-1. Preparation of Polyimide-Forming Composition 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 122000 CPs) was obtained in the same manner as above.

7-2. Production of transparent polyimide resin film Example 1, 1-2. 7-1. of Example 7 instead of the polyimide-forming composition used in 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 8]
8-1. 7-1. of Example 7 above, except that 4-diazabicyclo[2.2.2]octane is used instead of 4-tert- butylpyridine . A polyimide-forming composition (solution viscosity at 25° C.: 118000 CPs) was obtained in the same manner as above.

8-2. Production of transparent polyimide resin film Example 1, 1-2. 8-1. of Example 8 instead of the polyimide-forming composition used in 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 9]
9-1. 7-1. of Example 7 except that 4-methoxypyridine was used instead of 4-tert- butylpyridine . A polyimide-forming composition (solution viscosity at 25° C.: 119000 CPs) was obtained in the same manner as above.

9-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 9, 9-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 10]
10-1. Preparation of Polyimide-Forming Composition The procedure described above was used except that TFDB:FODA:CHDA:6FDA was used in a molar ratio of 9:1:8:2 and 4-methoxypyridine was used in place of 4-tert-butylpyridine. 1-1 of Example 1. A polyimide-forming composition (solution viscosity at 25° C.: 47000 CPs) was obtained in the same manner as above.

10-2. Production of transparent polyimide resin film Example 1, 1-2. 10-1. of Example 10 instead of the polyimide-forming composition used in 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 11]
11-1. Production of polyimide-forming composition Example 10, 10-1. A polyimide-forming composition (solution viscosity at 25° C.: 47000 CPs) was obtained in the same manner as above.

11-2. Production of transparent polyimide resin film Example 1, 1-2. 11-1. of Example 11 instead of the polyimide-forming composition used in . in a convection oven under a nitrogen atmosphere, stepwise at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 320°C for 1 hour. 1-2. A transparent polyimide resin film was produced in the same manner as above.

[Example 12]
12-1. Production of polyimide-forming composition Example 10, 10-1. A polyimide-forming composition (solution viscosity at 25° C.: 47000 CPs) was obtained in the same manner as above.

12-2. Production of transparent polyimide resin film Example 1, 1-2. 12-1. of Example 12 instead of the polyimide-forming composition used in . using the polyimide-forming composition prepared in stepwise, in a convection oven under a nitrogen atmosphere, at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 350°C for 1 hour. 1-2. A transparent polyimide resin film was produced in the same manner as above.

[Example 13]
13-1. Preparation of polyimide-forming composition except that TFDB:FODA:s-BPDA:6FDA is used in a molar ratio of 9:1:9:1 and 4-methoxypyridine is used instead of 4-tert-butylpyridine. , 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 112000 CPs) was obtained in the same manner as above.

13-2. Production of transparent polyimide resin film Example 1, 1-2. 13-1. of Example 13 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 14]
14-1. 13-1. of Example 13 except that 4-tert- butylpyridine was used instead of 4-methoxypyridine. A polyimide-forming composition (solution viscosity at 25° C.: 113000 CPs) was obtained in the same manner as above.

14-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 14, 14-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 15]
15-1. 13-1 . of Example 13 except that 3-picoline was used instead of 4-methoxypyridine. A polyimide-forming composition (solution viscosity at 25° C.: 110,000 CPs) was obtained in the same manner as above.

15-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 15, 15-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 16]
16-1. 13-1 . of Example 13 except that 2,3-lutidine was used instead of 4-methoxypyridine. A polyimide-forming composition (solution viscosity at 25° C.: 112000 CPs) was obtained in the same manner as above.

16-2. Production of transparent polyimide resin film Example 1, 1-2. 16-1. of Example 16 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 17]
17-1. 13-1. of Example 13 except that 2,3,5 -collidine was used instead of 4-methoxypyridine. A polyimide-forming composition (solution viscosity at 25° C.: 119000 CPs) was obtained in the same manner as above.

17-2. Production of transparent polyimide resin film Example 1, 1-2. 17-1. of Example 17 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 18]
18-1. Preparation of Polyimide-Forming Composition TFDB:FAPB:a-BPDA:ODPA was used in a molar ratio of 9:1:7:3 and 4-diazabicyclo[2.2.2] was used instead of 4-tert-butylpyridine. 1-1. of Example 1 above except that octane is used. A polyimide-forming composition (solution viscosity at 25° C.: 52000 CPs) was obtained in the same manner as above.

18-2. Production of transparent polyimide resin film Example 1, 1-2. 18-1. of Example 18 instead of the polyimide-forming composition used in 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 19]
19-1. Production of composition for forming polyimide Example 18, 18-1. A polyimide-forming composition (solution viscosity at 25° C.: 52000 CPs) was obtained in the same manner as above.

19-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 19, 19-1. in a convection oven under a nitrogen atmosphere, stepwise at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 320°C for 1 hour. 1-2. A transparent polyimide resin film was produced in the same manner as above.

[Example 20]
20-1. Production of composition for forming polyimide Example 18, 18-1. A polyimide-forming composition (solution viscosity at 25° C.: 52000 CPs) was obtained in the same manner as above.

20-2. Production of transparent polyimide resin film Example 1, 1-2. 20-1. of Example 20 instead of the polyimide-forming composition used in . using the polyimide-forming composition prepared in stepwise, in a convection oven under a nitrogen atmosphere, at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 350°C for 1 hour. 1-2. A transparent polyimide resin film was produced in the same manner as above.

[Example 21]
21-1. Preparation of Polyimide-Forming Composition 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 83000 CPs) was obtained in the same manner as above.

21-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 21, 21-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 22]
22-1. 21-1. of Example 21 except that 2,3,5 -collidine was used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 81000 CPs) was obtained in the same manner as above.

22-2. Production of transparent polyimide resin film Example 1, 1-2. 22-1. of Example 22 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 23]
23-1. 21-1 . of Example 21 except that 4-methoxypyridine was used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 82000 CPs) was obtained in the same manner as above.

23-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 23, 23-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 24]
24-1. Preparation of Polyimide-Forming Composition TFDB:4,4′-DDS:s-BPDA:6FDA was used in a molar ratio of 9:1:7:3 and 4-diazabicyclo[2 .2.2] 1-1. of Example 1 above except that octane is used. A polyimide-forming composition (solution viscosity at 25° C.: 61000 CPs) was obtained in the same manner as above.

24-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 24, 24-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 25]
25-1. Production of polyimide-forming composition Example 24, 24-1. A polyimide-forming composition (solution viscosity at 25° C.: 61000 CPs) was obtained in the same manner as above.

25-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 25, 25-1. using the polyimide-forming composition prepared in stepwise, in a convection oven under a nitrogen atmosphere, at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 350°C for 1 hour. 1-2. A transparent polyimide resin film was produced in the same manner as above.

[Example 26]
26-1. Preparation of Polyimide-Forming Composition TFDB:4,4-(perfluoropropane-2,2'-diyl)dibenzenamine:CBDA:6FDA was used in a molar ratio of 9:1:7:3 and 4-tert 1-1. of Example 1 above, except that 4-methoxypyridine is used instead of -butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 47000 CPs) was obtained in the same manner as above.

26-2. Production of transparent polyimide resin film Example 1, 1-2. 26-1. of Example 26 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 27]
27-1. Preparation of Polyimide-Forming Composition 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 107000 CPs) was obtained in the same manner as above.

27-2. Production of transparent polyimide resin film Example 1, 1-2. 27-1. of Example 27 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 28]
28-1. Preparation of Polyimide-Forming Composition 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 89000 CPs) was obtained in the same manner as above.

28-2. Production of transparent polyimide resin film Example 1, 1-2. 28-1. of Example 28 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 29]
29-1. 28-1 . of Example 28 except that 4-methoxypyridine was used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 85000 CPs) was obtained in the same manner as above.

29-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 29, 29-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 30]
30-1. 28-1 . of Example 28 above, except that 4-diazabicyclo[2.2.2]octane is used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 87000 CPs) was obtained in the same manner as above.

30-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 30, 30-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 31]
31-1 Preparation of Polyimide Forming Composition TFDB:4,4′-DDS:s-BPDA:6FDA was used in a molar ratio of 8:2:7:3, replacing 4-tert-butylpyridine with 4- 1-1. of Example 1 above, except that diazabicyclo[2.2.2]octane is used. A polyimide-forming composition (solution viscosity at 25° C.: 46000 CPs) was obtained in the same manner as above.

31-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 31, 31-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 32]
32-1. Preparation of polyimide-forming composition TFDB: 4,4′-DDS:bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride:6FDA 8:2:7:3 1-1. of Example 1 except that the molar ratio of A polyimide-forming composition (solution viscosity at 25° C.: 37000 CPs) was obtained in the same manner as above.

32-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 32, 32-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 33]
33-1. 32-1 . of Example 32 except that 2,3,5-collidine was used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 35000 CPs) was obtained in the same manner as above.

33-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 33, 33-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 34]
34-1. 32-1 . of Example 32 except that 4-methoxypyridine was used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 35000 CPs) was obtained in the same manner as above.

34-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 34, 34-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 35]
35-1. Preparation of polyimide-forming composition 1-1. of Example 1 above, except that the molar ratio is used. A polyimide-forming composition (solution viscosity at 25° C.: 41000 CPs) was obtained in the same manner as above.

35-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 35, 35-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 36]
36-1. Preparation of Polyimide-Forming Composition 35-1. A polyimide-forming composition (solution viscosity at 25° C.: 41000 CPs) was obtained in the same manner as above.

36-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 36, 36-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Example 37]
37-1. 35-1 . of Example 35 except that 4-methoxypyridine was used instead of 4-tert-butylpyridine. A polyimide-forming composition (solution viscosity at 25° C.: 40000 CPs) was obtained in the same manner as above.

37-2. Production of transparent polyimide resin film Example 1, 1-2. In place of the polyimide-forming composition used in Example 37, 37-1. 1-2. of Example 1, except for using the polyimide-forming composition produced in A transparent polyimide resin film was produced in the same manner as above.

[Comparative Example 1]
1-1. Preparation of Polyimide-Forming Composition 1-1. A polyimide-forming composition (solution viscosity at 25° C.: 82000 CPs) was obtained in the same manner as above.

1-2. Production of transparent polyimide resin film Example 1, 1-2. 1-1. of Comparative Example 1 instead of the polyimide-forming composition used in . 1-2. of Example 1, except for using the polyimide-forming composition produced in After producing in the same manner as in , an attempt was made to separate the film from the glass plate, but the formed film cracked and no film was obtained.

[Comparative Example 2]
2-1. Preparation of Polyimide-Forming Composition 1-1. of Comparative Example 1 except that isoquinoline is used instead of pyridine. A polyimide-forming composition (solution viscosity at 25° C.: 80000 CPs) was obtained in the same manner as above.

2-2. Production of transparent polyimide resin film Comparative Example 1, 1-2. 2-1. of Comparative Example 2 instead of the polyimide-forming composition used in . 1-2. of Comparative Example 1, except for using the polyimide-forming composition produced in However, the remaining amount of isoquinoline was too large to obtain a normal film.

[Comparative Example 3]
3-1. 1-1. of Comparative Example 1 except that TFDB :BTDA:6FDA was used in a molar ratio of 10:7:3. A polyimide-forming composition (solution viscosity at 25° C.: 73000 CPs) was obtained in the same manner as above.

3-2. Production of transparent polyimide resin film Example 1, 1-2. 3-1. of Comparative Example 3 instead of the polyimide-forming composition used in . 1-2. of Comparative Example 1, except for using the polyimide-forming composition produced in After producing in the same manner as in , an attempt was made to separate the film from the glass plate, but the formed film cracked and no film was obtained.

[Comparative Example 4]
4-1. Manufacture of polyimide-forming composition
1-1. of Comparative Example 1, except that TFDB:BTDA:6FDA was used in a molar ratio of 10:7:3. A polyimide-forming composition (solution viscosity at 25° C.: 73000 CPs) was obtained in the same manner as above.

4-2. Production of transparent polyimide resin film Example 1, 1-2. Instead of the polyimide-forming composition used in Comparative Example 4, 4-1. using the polyimide-forming composition prepared in stepwise, in a convection oven under a nitrogen atmosphere, at 80°C for 30 minutes, 150°C for 30 minutes, 200°C for 1 hour, and 350°C for 1 hour. 1-2. was produced in the same manner as Next, a polyimide film was obtained by separating from the glass plate.

The compositions of the diamine mixtures, dianhydride mixtures, and catalysts used in Examples 1-37 and Comparative Examples 1-4 above are shown in Table 1 below.

[Experimental Example 1] Evaluation of physical properties of transparent polyimide resin film The physical properties of the transparent polyimide resin films obtained in Examples 1 to 37 and Comparative Examples 1 to 4 described above were evaluated by the following methods, and the results are shown. 2.

(1) Measurement of light transmittance (T%) At a wavelength of 550 nm, using a UV-Vis NIR Spectrophotometer (manufactured by Shimadzu Corporation, model name: UV-3150), C light source and viewing angle 2 according to ASTM E313-73 standards. Measured in °.

(2) Measurement of yellowness index (YI) Using a spectrophotometer (manufactured by Konica Minolta, model name: CM-3700d), yellowness at a wavelength of 550 nm was measured according to ASTM E313 standards.

(3) Measurement of mechanical properties UTM (manufactured by Instron, model name: 5942) was used to measure tensile strength (Strength, MPa) and elastic modulus (Modulus, GPa) according to ISO 527-3 standards.

From Tables 1 and 2 above, changes in properties depending on the composition of the obtained transparent polyimide resin film can be seen.

First, from the results of Examples 1 to 37, when the same composition and the same catalyst are used, but different curing temperatures are applied, the higher the curing temperature, the worse the optical properties, and the greater the difference in mechanical properties. It turns out that there is no That is, it can be seen that a transparent polyimide resin film having excellent properties can be obtained in the imidization step at a curing temperature of 280°C.

Also, from the results of Examples 1 and 4-6, it can be seen that transparent polyimide resins with similar properties can be obtained when catalysts with different boiling points are used at the same curing temperature (280° C.). However, in Example 5, it is confirmed that the obtained film is partially damaged.

Furthermore, from the results of Examples 7 to 37, when various basic catalysts having a boiling point of 140 to 200 ° C. are used, the curing temperature is relatively low at 300 or less in the imidization step. It can be seen that a polyimide resin film is obtained. That is, it is confirmed that it is possible to improve the high-temperature process during manufacturing.

Results such as those described above confirm that it is possible to adjust optical and mechanical properties by combining composition, curing temperature, and type of catalyst.

On the other hand, from the results of Comparative Examples 1 and 2, when pyridine having the same composition and a boiling point as low as 115°C was used as a catalyst, no film was obtained (Comparative Example 1), and isoquinoline having a boiling point of 240°C is used as the catalyst, a film is obtained, but it is confirmed that the residual amount of catalyst is too high. Needless to say, such problems may cause serious troubles when applied to devices after mass production.

In addition, from the results of Comparative Examples 3 and 4, when using a catalyst having a boiling point of 115 ° C., a film was not obtained at a low curing temperature of 280 ° C. (Comparative Example 3), and at a curing temperature of 350 ° C., A film is obtained, but it is confirmed that partial damage occurs (Comparative Example 4).

As a result of analyzing the above results, the transparent polyimide resin films of Examples 1 to 37 according to the present invention have excellent optical properties and excellent mechanical properties such as increased tensile strength and elastic modulus. turned out to be something.

Specifically, the transparent polyimide resin films obtained in Examples 1 to 37 had a transmittance of 88% or more, a yellowness of 5.0 or less, an elastic modulus of 3 to 6 GPa, and a strength of 120 to 60 MPa. Compared to the transparent polyimide resin film obtained in 4, it has high light transmittance, low yellowness, and excellent mechanical properties, so it satisfies the conditions applicable as a material for flexible display devices. I found out.

As described above, the transparent polyimide resin film produced using the polyimide-forming composition according to the present invention has improved high-temperature processes during production, high light transmittance, low yellowness, and , It was confirmed that it can be applied as a material for a flexible display device, a substrate or a protective film because of its excellent mechanical properties.

Claims (9)

(a) from a diamine represented by the following chemical formula (1), a diamine represented by the following chemical formula (2), a diamine represented by the following chemical formula (2A), and 2,2′-dimethylbiphenyl-4,4′-diamine a diamine mixture comprising one or more diamines selected from the group consisting of;
(b) a dianhydride mixture containing a dianhydride represented by the following chemical formula (3) and a dianhydride represented by the following chemical formula (4);
(c) a basic catalyst that is one or more selected from the group consisting of 2-methylpiperazine, 4-tert-butylpyridine, and 2,3,5-collidine; and (d) an organic solvent;
and a transparent polyimide resin film produced by imidizing a polyimide-forming composition containing no dehydrating agent and satisfying the following physical property conditions (i) to (v).
(i) at a film thickness of 52 μm or less, the light transmittance at a wavelength of 550 nm is 88 to 89.5%;
(ii) a yellowness index of 1.4 to 5.0 according to the standard of ASTM E313;
(iii) a haze of 0.4 to 1.0;
(iv) an elastic modulus in the range of 3 to 6 GPa;
(v) Tensile strength is in the range of 120-200 MPa.

(In the above chemical formula (1),
A is a single bond, -C(=O)- and -C(=O)NH-, and _{C6 -} C substituted with a halogen or a C1 _- C6 alkyl group substituted with a halogen atom selected from the group consisting of ₂₀ arylene groups,
X ₁ and X ₂ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ -C ₆ alkyl group, and a C ₁ -C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; is selected from the group consisting of
provided that when A is a single bond, at least one of X ₁ and X ₂ is a halogen or a C ₁ to C ₆ alkyl group substituted with a halogen atom;
m is an integer from 0 to 2; )

(In the above chemical formula (2),
B ₁ is a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are substituted with halogen atoms, —O—, —S—, —S(=O) ₂ — , and C ₆ -C ₂₀ arylene groups substituted or unsubstituted with C ₁ -C ₆ alkyl groups,
X ₃ and X ₄ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ to C ₆ alkyl group, and a C ₁ to C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; selected from the group consisting of )

(In the chemical formula (2A),
B ₂ is substituted or unsubstituted with a C ₁ -C ₆ alkylene group, a C ₁ -C ₆ alkylene group in which one or more hydrogen atoms are replaced with a halogen atom, and a C ₁ -C ₆ alkyl group selected from the group consisting of C6 _{- C20} arylene groups;
X ₃ and X ₄ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ to C ₆ alkyl group, and a C ₁ to C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms; selected from the group consisting of )

(In the above chemical formula (3),
C is selected from the group consisting of a tetravalent C6- _C20 aromatic cyclic group and a tetravalent _{C4 - C20} aliphatic cyclic group;
the tetravalent C ₆ to C ₂₀ aromatic ring group may be substituted with a C ₁ to C ₆ alkyl group;
The C may be a plurality of rings, the plurality of rings may be the same or different, and the plurality of rings may be a single bond, -C(=O)NH-, and -C(=O ) is linked via one or more linking groups selected from the group consisting of —O—. )

(In the above chemical formula (4),
D is a C ₁ to C ₆ alkylene group, a C ₁ to C ₆ alkylene group in which one or more hydrogen atoms are substituted with halogen atoms, —O—, —S—, —C(=O)—, and -S(=O) ₂ - is selected from the group consisting of
X ₅ and X ₆ are the same or different from each other and are each independently hydrogen, halogen, a C ₁ -C ₆ alkyl group, and a C ₁ -C ₆ alkyl group in which one or more hydrogen atoms are substituted with halogen atoms is selected from the group consisting of
n is an integer of 1-3. ) 2. The transparent polyimide resin film according to claim 1, wherein X ₁ to X ₆ are each independently an electron-withdrawing group (EWG) that is F or CF ₃ . The transparent polyimide resin film according to claim 1, wherein A is selected from the group of substituents represented by the following chemical formula (5):

(In the above chemical formula (5),
* is a linking site in the chemical formula (1),
R ₁ to R ₃ are the same or different from each other and are each independently selected from the group consisting of F and CF ₃ . ) The transparent polyimide resin film according to claim 1, wherein C is selected from the substituent group represented by the following chemical formula (6):

(In the chemical formula (6),
* is a linking site in the chemical formula (3),
R ₄ to R ₆ are the same or different from each other and are each independently selected from hydrogen or C ₁ to C ₆ alkyl groups. ) The content of the diamine represented by the chemical formula (1) is 50 to 99.9 mol% with respect to 100 mol% of the diamine mixture,
The total content of the diamine represented by the chemical formula (2), the diamine represented by the chemical formula (2A), and 2,2'-dimethylbiphenyl-4,4'-diamine is based on 100 mol% of the diamine mixture. , 0.1 to 50 mol %, the transparent polyimide resin film according to claim 1. 2. The transparent polyimide resin film according to claim 1, wherein the content of the dianhydride represented by the chemical formula (3) is 10 to 95 mol % with respect to 100 mol % of the dianhydride mixture. 2. The transparent polyimide resin film according to claim 1, wherein the content ratio of (a) the diamine mixture and (b) the dianhydride mixture is (a):(b)=1:0.1 to 10 by weight. The transparent polyimide resin film according to claim 1, wherein the polyimide-forming composition has a viscosity of 1,000 to 500,000 cps. A transparent substrate comprising the transparent polyimide resin film according to any one of claims 1 to 8.