KR20200083797A - Polyamide-imide copolymers and transparent films using the same - Google Patents

Abstract

The present invention relates to a polyamide-imide copolymer, and a transparent film using the same. When manufacturing the polyamide-imide copolymer by using 2,5-Furandicarbonyl dichloride (FDCACl) alone or mixing terephthaloyl chloride or 1,4-benzenedicarbonyl chloride together at a specific molar ratio, a yellowing degree (YI) is alleviated compared to an existing polyamide-imide film.

Description

Polyamide-imide copolymers and transparent films using the same}

It relates to a polyamide-imide copolymer and a transparent film using the same.

Due to its excellent thermal stability, mechanical properties, and birefringence properties, interest in transparent polyamide-imide (PAI) resins and films useful as substrates for plastic displays is increasing, but the thermal and mechanical properties still required by the market In addition, a polyamide-imide copolymer film that satisfies optical properties simultaneously is not supplied.

Polyamide-imide is a type of thermoplastic PI-based resin that simultaneously introduces polyamide (PA) units as a flexible chain structure as well as polyimide (PI) units in a molecular structure.Amoco Performance Products in the early 1970s It was first developed by the company under the trade name Torlon. Currently, in addition to Torlon, the injection molding <TRON> series and Toray <TI-5000> series are available.

Polyamide-imide is classified as a special engineering plastic because it has excellent heat resistance and general properties and excellent formability, and its use is gradually expanding mainly in the fields of electric, electronic, automotive, and mechanical.

The high temperature properties of the aromatic polyamide-imide are between PI and PA, and the processability is superior to that of PI and PA. When heated, it not only melts, but also melts well in general organic solvents, so injection moldability and solvent molding are superior to those of these two types of resins, and also has excellent physical properties.

Recently, studies on copolymerization of polyamide-imides for flexible display substrates having excellent mechanical and optical properties have been published.

In addition, the development of a polyamide-imide precursor for forming a film having low birefringence, colorless, transparent, and excellent mechanical properties and heat resistance, and a polyamide-imide film prepared by imidizing it (Patent Document 1, KR 10-1583845) ) And video display elements including the same have been announced.

The present inventor used 2,5-furandicarbonyl dichloride (FDCACl) alone, which was not used in the conventional polyamide-imide film production, or TPC (Terephthaloyl chloride; 1,4-benzenedicarbonyl) When the polyamide-imide film is prepared by mixing chloride) together in a specific molar ratio, the yellowing degree (YI) is improved compared to the conventional polyamide-imide film, so that it is a transparent polyamide-imide film for flexible display substrates. The invention has been completed and proved to be useful.

An object in one aspect of the present invention is to provide a polyamide-imide copolymer having a yellowness (Y.I) that can be improved relative to a conventional polyamide-imide film when formed into a film.

An object in another aspect of the present invention is to provide a method for preparing the polyamide-imide copolymer.

Another object of another aspect of the present invention is to provide a flexible display device comprising a transparent film for a flexible display substrate and a transparent film for a flexible display substrate formed of a polyamide-imide copolymer.

In order to achieve the above object,

One aspect of the present invention is a unit structure derived from a diamine compound;

Unit structure derived from dianhydride compound; And

A unit structure derived from 2,5-furandicarbonyl dichloride (FDCACl); Provides a copolymerized polyamide-imide.

Another aspect of the present invention is a first polymerization step of reacting a diamine compound and an dianhydride compound in solution, and a polymer obtained through the first polymerization step and 2,5-furandicarbonyl dichloride (2,5-Furandicarbonyl dichloride; FDCACl) a polyamic acid production process for preparing a polyamic acid solution, including a second polymerization step of reacting the solution; And

An imidization step of chemically imidating the polyamic acid solution prepared by the polyamic acid production process in the presence of an imidization catalyst; It provides a method for producing the polyamide-imide copolymer comprising a.

Another aspect of the present invention provides a flexible display device comprising a transparent film for a flexible display substrate formed of the polyamide-imide copolymer and a transparent film for the flexible display substrate.

Polyamide-imide film using 2,5-furandicarbonyl dichloride (FDCACl) alone or mixing TPC (Terephthaloyl chloride; 1,4-benzenedicarbonyl chloride) together at a specific molar ratio When manufacturing, there is an effect that the yellowing degree (YI) is improved compared to the conventional polyamide-imide film.

1 is a view showing a GPC graph of Examples 1-3 and Comparative Example 1.
2 is a diagram showing a GPC graph of Example 4-7 and Comparative Example 2.

Hereinafter, the present invention will be described in detail.

Meanwhile, the embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Furthermore, "including" a component throughout the specification means that other components may be further included, rather than excluding other components, unless otherwise specified.

One aspect of the present invention is a unit structure derived from a diamine compound;

Unit structure derived from dianhydride compound; And

A unit structure derived from 2,5-furandicarbonyl dichloride (FDCACl) derived from biomass; Provides a copolymerized polyamide-imide.

At this time, the polyamide-imide copolymer,

The unit structure derived from TPC (Terephthaloyl chloride; 1,4-benzenedicarbonyl chloride) may be a copolymerized polyamide-imide copolymer.

If the polyamide-imide copolymer is a polyamide-imide copolymer in which the unit structure derived from terephthaloyl chloride (TPC), 1,4-benzenedicarbonyl chloride) is further copolymerized, the TPC and the FDCACl The molar ratio may be 1: 0.2 to 2.4, preferably 1: 0.5 to 2.4, and more preferably 1: 1.0 to 2.4.

The 2,5-furandicarbonyl dichloride (2,5-Furandicarbonyl dichloride; FDCACl) is used alone, or TPC (Terephthaloyl chloride; 1,4-benzenedicarbonyl chloride) is mixed together at a specific molar ratio to polyamide-imide When producing a film, the effect of improving the yellowness (YI) is generated compared to the conventional polyamide-imide film.

The diamine compound can be used without particular limitation as long as it is a known diamine compound, but for example, bis trifluoromethyl benzidine (TFDB), oxidianiline (ODA), p-phenylenediamine (pPDA), m-phenyl Rendiamine (mPDA), p-methylenedianiline (pMDA), m-methylenedianiline (mMDA), bis aminophenoxy benzene (133APB), bis aminophenoxy benzene (134APB), bis amino phenoxy phenyl hexafluoro Propane (4BDAF), bis aminophenyl hexafluoro propane (33-6F), bis aminophenyl hexafluoro propane (44-6F), bis aminophenylsulfone (4DDS), bis aminophenylsulfone (3DDS), cyclohexanediamine (13CHD), cyclohexane diamine (14CHD), bis amino phenoxy phenylpropane (6HMDA), bis aminohydroxy phenyl hexaflooropropane (DBOH), bis aminophenoxy diphenyl sulfone (DBSDA), bis (4-amino Phenyl) fluorene (FDA), bis (4-amino-3-fluorophenyl) fluorene (F-FDA), or the like can be used alone or in combination.

The dianhydride compound may be used without particular limitation as long as it is a known dianhydride compound, but for example, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), benzophenone Tetracarboxylic Dianhydride (BTDA), Biphenyl Tetracarboxylic Dianhydride (BPDA), 4-(2,5-dioxotetrahydrofuran-3-yl) 1,2,3,4-tetra Hydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellitic acid dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), biscarboxyphenyl dimethylsilane dianhydride (SiDA), bis Dicarboxyphenoxy diphenyl sulfide dianhydride (BDSDA), sulfonyl diphthalanhydride (SO2DPA), isopropylideneiphenoxy bis phthalanhydride (6HBDA), cyclobutanedihydride (CBDA), Cyclopentanedianhydride (CPDA), cyclohexanedianhydride (CHDA), bicyclohexanedianhydride (HBPDA), 9,9-bis(3,4-dicarboxyphenyl)fluorenedianhydride (BPAF) Etc. can be used alone or in combination.

As an example,

Bis trifluoromethyl benzidine (TFDB) as the diamine compound, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) as the dianhydride compound, TPC and FDCACl as the dicarbonyl compound If you use

The molar ratio of TFDB: 6FDA: TPC: FDCACl may be 2.5 to 7.0: 1.4 to 3.5: 1: 0.2 to 2.4, 2.5 to 7.0: 1.4 to 3.5: 1: 0.5 to 2.4, and 2.5 to It may be 7.0: 1.4 to 3.5: 1: 1.0 to 2.4, and 2.5 to 7.0: 1.4 to 3.5: 1: 2.33.

As another example, bis trifluoromethyl benzidine (TFDB) as a diamine compound, 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) as a dianhydride compound, and benzophenone tetracarboxyl Rick dianhydride (BTDA), when using TPC and FDCACl as dicarbonyl compounds,

The molar ratio of TFDB: BTDA: 6FDA: TPC: FDCACl can be 2-4: 0.5-0.95: 0.2-0.45:1: 0.2-2.4, and 2-4: 0.5-0.95: 0.2-0.45:1 : 0.2 to 1.0, 2 to 4: 0.5 to 0.95: 0.2 to 0.45: 1: 0.5 to 1.0, 2 to 4: 0.5 to 0.95: 0.2 to 0.45: 1: 1

Another aspect of the present invention is a first polymerization step of reacting a diamine compound and an dianhydride compound in solution, a polymer obtained through the first polymerization step, and 2,5-furandicarbonyl dichloride (2,5-Furandicarbonyl dichloride; FDCACl ) A polyamic acid production process for preparing a polyamic acid solution, including a second polymerization step of reacting the solution; And

An imidization step of chemically imidating the polyamic acid solution prepared by the polyamic acid production process in the presence of an imidization catalyst; It provides a method for producing the polyamide-imide copolymer comprising a.

Another aspect of the present invention provides a flexible display device comprising a transparent film for a flexible display substrate formed of the polyamide-imide copolymer and a transparent film for the flexible display substrate.

The present invention uses 2,5-furandicarbonyl dichloride alone, or by mixing TPC together at a specific molar ratio to prepare a polyamide-imide film, which results in yellowing (YI compared to a conventional polyamide-imide film). ) Has the effect of improving, which is directly supported by the examples and experimental examples described below.

Hereinafter, the present invention will be described in detail through examples and experimental examples described below.

However, the examples and experimental examples to be described later are merely examples of the present invention, and the present invention is not limited thereto.

< Example 1>

Polyamide -Preparation of imide copolymer

The polymerization experiment was carried out in a simple glove box in which the relative humidity was lowered to 15% or less through nitrogen substitution. After passing nitrogen through a 500 mL double jacketed reactor equipped with a stirrer and a stirring rod to create a nitrogen atmosphere, 13.00 g (0.0406 mol) of TFDB as diamine and 235.5 g of N,N-dimethylacetamide (DMAc) as a solvent were added and TFDB was added. It was stirred sufficiently until completely dissolved. At this time, the temperature of the reactor was maintained at 25°C using a temperature-controlled fluid circulation device. To this, 9.11 g (0.0205 mol) of 6FDA, a dianhydride having a molar ratio lower than TFDB, was added and stirred for a certain period of time to proceed the reaction to synthesize a polyamic acid (PAA) oligomer having amine groups at both ends.

Thereafter, a chain extension reaction was performed in which 1.18 g (0.0061 mol) of FDCACl and 2.88 g (0.0142 mol) of TPC were added to obtain a high molecular weight polyamide-amic acid solution.

To the polyamide-amic acid solution, 4.05 g of pyridine and 5.23 g of acetic anhydride were added as a catalyst and a dehydrating agent for a chemical imidization reaction, followed by stirring at room temperature for 30 minutes, raising the temperature to 80° C., stirring for 1 hour, and bringing it to room temperature. Cooled. Then, it was slowly added dropwise to 2 L of methanol to precipitate, and the precipitated solid was collected by filtration and washed 3 times with excess methanol. The finally obtained solid content was dried in a vacuum oven at 80° C. for 10 hours to obtain 23.45 g of solid content of a polyamide-imide copolymer.

Polyamide -Preparation of imide copolymer film

To prepare a polyamide-imide film, 23.45 g of the solid polyamide-imide copolymer was dissolved in 132.79 g of DMAc to obtain a 15 wt% solution, and the obtained solution was applied to a glass substrate to 290 μm. Cast and dry for 1 hour with hot air at 80°C. This was placed in a vacuum oven and slowly heat-treated at 30°C to 250°C at a rate of 3°C/min, but further heat-treated at 200°C and 250°C for another hour. Then it was cooled slowly and separated from the glass substrate to obtain a polyamide-imide film having a thickness of 45 µm.

< Example 2>

Polyamide -Preparation of imide copolymer

In Example 1, 13.00 g (0.0406 mol) of TFDB and 234.77 g of DMAc were added, and the mixture was sufficiently stirred at 25° C. until TFDB was completely dissolved. Here, 9.11 g (0.0205 mol) of 6FDA having a molar ratio lower than that of TFDB was added, and the mixture was stirred for a certain period of time to proceed the reaction to synthesize a polyamic acid oligomer having amine groups at both ends. Thereafter, a chain extension reaction was performed in which 2.74 g (0.0142 mol) of FDCACl and 1.24 g (0.0061 mol) of TPC were added to obtain a high molecular weight polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 1. Finally, 22.69 g of solid content of a polyamide-imide copolymer was obtained.

Polyamide -Preparation of imide copolymer film

The polyamide-imide copolymer of 22.69 g of solid content was dissolved in 128.51 g of DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Example 3>

Polyamide -Preparation of imide copolymer

In Example 1, 13.00 g (0.0406 mol) of TFDB and 234.22 g of DMAc were added and sufficiently stirred at 25° C. until TFDB was completely dissolved. Here, 9.11 g (0.0205 mol) of 6FDA having a molar ratio lower than that of TFDB was added, and the mixture was stirred for a certain period of time to proceed the reaction to synthesize a polyamic acid oligomer having amine groups at both ends. Thereafter, a chain extension reaction in which 3.92 g (0.0203 mol) of FDCACl was added was performed to obtain a high molecular weight polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 1. Finally, 22.90 g of solid content of a polyamide-imide copolymer was obtained.

Polyamide -Preparation of imide copolymer film

The polyamide-imide copolymer of 22.90 g of solid content was dissolved in 129.67 g of DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Comparative example 1>

Polyamide -Preparation of imide copolymer

In Example 1, 13.00 g (0.0406 mol) of TFDB and 236.05 g of DMAc were added and sufficiently stirred at 25° C. until TFDB was completely dissolved. Here, 9.11 g (0.0205 mol) of 6FDA having a molar ratio lower than that of TFDB was added, and the mixture was stirred for a certain period of time to proceed the reaction to synthesize a polyamic acid oligomer having amine groups at both ends. Thereafter, a chain extension reaction in which 4.12 g (0.0203 mol) of TPC was added was performed to obtain a high molecular weight polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 1. Finally, a polyamide-imide copolymer having a solid content of 21.51 g was obtained.

Polyamide -Preparation of imide copolymer film

The 21.51 g solid content copolymer polyamide-imide was dissolved in 121.80 g DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Example 4>

Polyamide -Preparation of imide copolymer

The polymerization experiment was carried out in a simple glove box in which the relative humidity was lowered to 15% or less through nitrogen substitution. After passing nitrogen through a 500 mL double-jacket reactor equipped with a stirrer and a stirring rod to create a nitrogen atmosphere, 13.00 g (0.0406 mol) of TFDB as diamine and 214.10 g of DMAc as a solvent were added and stirred sufficiently until TFDB was completely dissolved. At this time, the temperature of the reactor was maintained at 25°C using a temperature-controlled fluid circulation device. To this, 2.19 g (0.00492 mol) of 6FDA and 3.70 g (0.01148 mol) of dianhydride having a molar ratio of less than TFDB were added, and the mixture was stirred for a period of time and reacted to obtain polyamic acid (PAA) oligomer having amine groups at both ends. Synthesized.

Thereafter, chain extension reaction with 0.78 g (0.0041 mol) of FDCACl and 4.12 g (0.0203 mol) of TPC was performed to obtain a high molecular weight polyamide-amic acid solution.

3.24 g of pyridine and 4.19 g of acetic anhydride are added to the polyamide-amic acid solution as a catalyst and a dehydrating agent for a chemical imidization reaction, followed by stirring at room temperature for 30 minutes, raising the temperature to 80° C., stirring for 1 hour, and bringing it to room temperature. Cooled. Then, it was slowly added dropwise to 2 L of methanol to precipitate, and the precipitated solid was collected by filtration and washed 3 times with excess methanol. The finally obtained solid content was dried in a vacuum oven at 80° C. for 10 hours to obtain a polyamide-imide copolymer having a solid content of 20.34 g.

Polyamide -Preparation of imide copolymer film

The 20.34 g solid content copolymer polyamide-imide was dissolved in 115.17 g DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Example 5>

Polyamide -Preparation of imide copolymer

In Example 4, 13.00 g (0.0406 mol) of TFDB and 213.74 g of DMAc were added and sufficiently stirred at 25° C. until TFDB was completely dissolved. To this, 2.19 g (0.00492 mol) of 6FDA and 3.70 g (0.01148 mol) of 6FDA with a molar ratio lower than TFDB were added, and the mixture was stirred for a period of time to react to synthesize a polyamic acid oligomer having amine groups at both ends. Then, a chain extension reaction was performed in which 1.57 g (0.0081 mol) of FDCACl and 3.30 g (0.0162 mol) of TPC were added to obtain a high molecular weight polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 4. Finally, 20.33 g of solid content of a polyamide-imide copolymer was obtained.

Polyamide -Preparation of imide copolymer film

The 20.33 g solid content copolymer polyamide-imide was dissolved in 115.12 g DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Example 6>

Polyamide -Preparation of imide copolymer

In Example 4, 13.00 g (0.0406 mol) of TFDB and 213.37 g of DMAc were added and sufficiently stirred at 25° C. until TFDB was completely dissolved. To this, 2.19 g (0.00492 mol) of 6FDA and 3.70 g (0.01148 mol) of 6FDA with a molar ratio lower than TFDB were added, and the mixture was stirred for a period of time to react to synthesize a polyamic acid oligomer having amine groups at both ends. Thereafter, a chain extension reaction was performed in which 2.35 g (0.0122 mol) of FDCACl and 2.47 g (0.0122 mol) of TPC were added to obtain a high molecular weight polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 4. Finally, 22.10 g of solid content of a polyamide-imide copolymer was obtained.

Polyamide -Preparation of imide copolymer film

The 22.10 g solid content copolymer polyamide-imide was dissolved in 125.23 g DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Example 7>

Polyamide -Preparation of imide copolymer

In Example 4, 13.00 g (0.0406 mol) of TFDB and 213.0 g of DMAc were added and sufficiently stirred at 25° C. until TFDB was completely dissolved. To this, a polyamic acid oligomer having amine groups at both ends was synthesized by adding 2.19 g (0.00492 mol) of 6FDA and 3.70 g (0.01148 mol) of BTF with a molar ratio lower than TFDB and stirring for a period of time to proceed the reaction. Thereafter, a chain extension reaction was performed in which 3.13 g (0.0162 mol) of FDCACl and 1.65 g (0.0081 mol) of TPC were added to obtain a high molecular weight polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 4. Finally, 22.41 g of solid polyamide-imide copolymer was obtained.

Polyamide -Preparation of imide copolymer film

The 22.41 g of solid content copolymer polyamide-imide was dissolved in 126.92 g of DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Comparative example 2>

Polyamide -Preparation of imide copolymer

In Example 4, 13.00 g (0.0406 mol) of TFDB and 214.47 g of DMAc were added and sufficiently stirred at 25° C. until TFDB was completely dissolved. To this, 2.19 g (0.00492 mol) of 6FDA and 3.70 g (0.01148 mol) of 6FDA with a molar ratio lower than TFDB were added, and the mixture was stirred for a period of time to react to synthesize a polyamic acid oligomer having amine groups at both ends. Thereafter, a chain extension reaction in which 4.95 g (0.0244 mol) of TPC was added was performed to obtain a polyamide-amic acid solution.

The chemical imidization reaction of the polyamide-amic acid solution and the recovery of solid content were carried out in the same manner as in Example 4. Finally, a polyamide-imide copolymer having a solid content of 21.16 g was obtained.

Polyamide -Preparation of imide copolymer film

The 21.16 g of solid content of the copolymerized polyamide-imide was dissolved in 119.91 g of DMAc to obtain a 15 wt% solution. Then, a polyamide-imide film was prepared in the same manner as in Example 1.

< Experimental Example 1> Property evaluation

The composition, weight average molecular weight (Mw), molecular weight distribution (PDI) of the polyamide-imide copolymer prepared in Examples 1-7 and Comparative Examples 1-2; The modulus, tensile strength, elongation, expansion coefficient (CTE) and yellowness (Y.I) of the transparent film were evaluated.

(One) Polyamide -Imide molecular weight

The molecular weight of the polyamide-imide is dried with a polyamide-imide copolymer, dissolved in N,N -dimethylformamide (DMF) at a concentration of about 1%, filtered through a 0.45 μm PTFE syringe filter, and then gel permeation chromatography (GPC, Young Lin SP930D solvent delivery pump). Detailed GPC analysis conditions are as follows. Columns: Shodex GPC KD-806M (8.0mml.D. x 300mm)x2, Flow rate: 1.0 mL/min, Eluent: 0.01M LiBr in DMF.

(2) Tensile strength

It was measured according to the standard of ASTM-D882 using a universal tensile testing machine. The size of the specimen was 20 mm x 160 mm, the load cell 1 kN, and the tensile speed was 10.0 mm/min, measured 7 times per specimen, and the elastic modulus and tensile strength were determined by the average value excluding the maximum and minimum values among the measured values.

(3) Yellowing

The yellowness index (Yellowness index, Y.I.) at 550 nm was measured by using the Konica Minolta CM-3600A spectrophotometer.

(4) Coefficient of thermal expansion

Coefficient of thermal expansion (CTE) at 50 to 270° C. was measured in two times using a TMA/SDTA840 Thermomechanical Analysis (TMA) from Mettler Toledo. The heating rate was 5°C/min and a load of 0.1 N was applied. Since residual stress may remain in the formed polyamide-imide film, the residual stress is completely removed by the first test, and the value determined through the second test is presented as the actual measurement.

The results for Examples 1-7 and Comparative Examples 1-2 are shown in Tables 1, 2 and 1 and 2, respectively.

[Table 1]

As shown in Table 1 above,

In the case of Comparative Example 1 using only TPC as the dicarbonyl compound, the yellowing degree (YI) was high at 1.70, making it difficult to secure the transparency required as a transparent film, but in the case of Example 3 using only FDCACl as a substitute for TPC, yellowing degree (YI) Improved to 1.62.

When TPC and FDCACl are used together as a dicarbonyl compound, yellowing degree (YI) is 1.74 in Example 1 in which the molar ratio of TPC and FDCACl is 1:0.42, compared to Comparative Example 1 using TPC alone. There was a problem that the degree was high.

On the other hand, in Example 2, in which the mole ratio (molar) of TPC and FDCACl was 1:2.33, the yellowness (Y.I) was found to be significantly improved to 1.43.

From this, it can be seen that when TPC and FDCACl are used together as a dicarbonyl compound, when the molar ratio of TPC and FDCACl is adjusted to a specific ratio, transparency required as a transparent film can be significantly improved.

[Table 2]

As shown in Table 2 above,

In the case of Comparative Example 2 using only TPC as the dicarbonyl compound, the yellowing degree (YI) is 4.21, which makes it difficult to secure the transparency required as a transparent film, but it can be seen that the yellowing degree (YI) is improved when TPC and FDCACl are used together. have.

More specifically, in Example 7 in which the molar ratio of TPC and FDCACl is 1:2, yellowness (YI) was improved to 4.17, and in Example 4 in which the molar ratio of TPC and FDCACl was 1:0.2. In the case of Example 5, where the yellowness (YI) was improved to 3.82, and the molar ratio of TPC and FDCACl was 1: 0.5, the yellowness (YI) was improved to 3.69, and the molar ratio of TPC and FDCACl was In the case of Example 1, which was 1:1, the yellowness (YI) was improved to 3.61.

From the results of Table 1 and Table 2 above,

When TPC and FDCACl are used together as a dicarbonyl compound, the molar ratio of the TPC and the FDCACl should be adjusted to 1: 0.2 to 2.4, preferably 1: 0.5 to 2.4, and more preferably It can be seen that the transparency required as a transparent film is secured when the ratio is 1: 1.0 to 2.4.

Above, the present invention has been described in detail through preferred examples and experimental examples, but the scope of the present invention is not limited to specific examples, and should be interpreted by the appended claims. In addition, those skilled in the art should understand that many modifications and variations are possible without departing from the scope of the present invention.

Claims (10)

A unit structure derived from a diamine compound;
Unit structure derived from dianhydride compound; And
A unit structure derived from 2,5-furandicarbonyl dichloride (FDCACl); Copolymerized polyamide-imide copolymer.
According to claim 1,
The polyamide-imide copolymer,
A polyamide-imide copolymer characterized in that the unit structure derived from TPC (Terephthaloyl chloride; 1,4-benzenedicarbonyl chloride) is a copolymerized polyamide-imide copolymer.
According to claim 2,
The polyamide-imide copolymer, characterized in that the molar ratio of the TPC and the FDCACl is 1: 0.2 to 2.4.
According to claim 2,
The polyamide-imide copolymer, characterized in that the molar ratio of the TPC and the FDCACl is 1:0.5 to 2.4.
According to claim 2,
The polyamide-imide copolymer, characterized in that the molar ratio of the TPC and the FDCACl is 1:1 to 2.4.
According to claim 1,
The diamine compound is bis trifluoromethyl benzidine (TFDB), oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenedianiline (pMDA), m- Methylenedianiline (mMDA), bis aminophenoxy benzene (133APB), bis aminophenoxy benzene (134APB), bis amino phenoxy phenyl hexafluoropropane (4BDAF), bis aminophenyl hexafluoro propane (33-6F) , Bis aminophenyl hexafluoro propane (44-6F), bis aminophenylsulfone (4DDS), bis aminophenylsulfone (3DDS), cyclohexanediamine (13CHD), cyclohexane diamine (14CHD), bisamino phenoxy phenylpropane (6HMDA), bis aminohydroxy phenyl hexaflooropropane (DBOH), bis aminophenoxy diphenyl sulfone (DBSDA), bis (4-aminophenyl) fluorene (FDA) and bis (4-amino-3-fluor) Phenyl) Polyamide-imide copolymer, characterized in that at least one member selected from the group consisting of fluorene (F-FDA).
According to claim 1,
The dianhydride compound is 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), benzophenone tetracarboxylic dianhydride (BTDA), biphenyl tetracarboxylic dian Hydride (BPDA), 4-(2,5-dioxotetrahydrofuran-3-yl) 1,2,3,4-tetrahydronaphthalene-1,2-dicarboxyanhydride (TDA), fatigue Melic acid dianhydride (PMDA), oxydiphthalic dianhydride (ODPA), biscarboxyphenyl dimethylsilane dianhydride (SiDA), bisdicarboxyphenoxy diphenyl sulfide dianhydride (BDSDA), sulfonyl diphthalic Anhydride (SO2DPA), isopropylidene phenoxy bis phthalic anhydride (6HBDA), cyclobutane di hydride (CBDA), cyclopentane di hydride (CPDA), cyclohexane di anhydride (CHDA), Polyamide-imide, characterized by at least one member selected from the group consisting of bicyclohexanedianhydride (HBPDA) and 9,9-bis(3,4-dicarboxyphenyl)fluorenedianhydride (BPAF) Copolymer.
A first polymerization step in which the diamine compound and the dianhydride compound are reacted in solution, and a polymerization reaction product obtained through the first polymerization step and 2,5-furandicarbonyl dichloride (FDCACl) in solution. Polyamic acid production process for producing a polyamic acid solution, including a two-polymerization step; And
An imidization step of chemically imidating the polyamic acid solution prepared by the polyamic acid production process in the presence of an imidization catalyst; A method for producing a polyamide-imide copolymer of claim 1, comprising:
A transparent film for a flexible display substrate formed of the polyamide-imide copolymer of claim 1.
A flexible display device comprising the transparent film for a flexible display substrate of claim 9.

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