POLYAMIC ACID AQUEOUS SOLUTION COMPOSITION, AND METHOD FOR PREPARING POLYIMIDE POWDER

Abstract

The present invention provides a polyamic acid aqueous solution composition capable of polymerizing polyamic acid in water rather than in an organic solvent, as well as achieving a high imidization rate during low-temperature curing.

Claims

1. A polyamic acid aqueous solution composition comprising: a polyamic acid including a diamine monomer and a dianhydride monomer as polymerization units; and a pyridine derivative compound having at least one electron donating group as an aqueous catalyst.

2. A polyamic acid aqueous solution composition comprising: a polyamic acid including a diamine monomer and a dianhydride monomer as polymerization units; and a pyridine derivative compound as an aqueous catalyst, wherein an imidization rate ranges from 70 to 99.9% upon thermal curing at 200 C.

3. The polyamic acid aqueous solution composition of claim 1, wherein the aqueous catalyst satisfies the following Chemical Formula 1: ##STR00005## in Chemical Formula 1, at least one of R.sub.1 to R.sub.3 is an alkylamine group, a hydroxyl group, an alkoxy group, a thiol group, a thioether group, an alkyl group, or a heterocyclic group.

4. The polyamic acid aqueous solution composition of claim 1, wherein the aqueous catalyst satisfies the following Chemical Formula 2: ##STR00006## in Chemical Formula 2, at least one of R.sub.4 and R.sub.5 is a C1 to C4 monoalkylamino group, a C1 to C4 dialkylamino group, a hydroxyl group, a C1 to C4 alkoxy group, a thiol group, a C1 to C4 thioether group, a C1 to C4 alkyl group, a piperidino group, a morpholino group, or a pyrrolidino group.

5. The polyamic acid aqueous solution composition of claim 1, wherein the aqueous catalyst is included in a range of 0.5 to 5 equivalents with respect to 1 equivalent of the carboxyl group in the polyamic acid.

6. The polyamic acid aqueous solution composition of claim 1, wherein the dianhydride monomer includes at least one compound represented by the following Chemical Formula 3: ##STR00007## wherein X is a substituted or unsubstituted tetravalent aliphatic ring group, a substituted or unsubstituted tetravalent heteroaliphatic ring group, a substituted or unsubstituted tetravalent aromatic ring group, or a substituted or unsubstituted tetravalent heteroaromatic ring group, and the aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, and the heteroaromatic ring group are present alone, conjugated to each other to form a condensed ring, or connected by a linking group including one or more divalent substituents selected from the group consisting of a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkynylene group, a substituted or unsubstituted arylene group, O, S, C(O), S(O).sub.2, and Si(R.sub.a).sub.2 (where R.sub.a is hydrogen or an alkyl group).

7. The polyamic acid aqueous solution composition of claim 1, wherein a solid content ranges from 1 to 30 wt %.

8. The polyamic acid aqueous solution composition of claim 1, wherein a cured product of the polyamic acid aqueous solution composition has a tensile strength of 50 to 400 MPa measured in accordance with ASTM D882 or a 5% thermal decomposition temperature (Td) of 400 to 700 C. measured using a thermogravimetric analyzer (TGA, Q5000 commercially available from TA Instruments, USA).

9. A method of preparing a polyamic acid, comprising preparing a polyamic acid using a pyridine derivative compound as an aqueous catalyst.

10. A method of preparing a polyimide, comprising: preparing a polyamic acid using a pyridine derivative compound as an aqueous catalyst; and thermally curing the polyamic acid at 250 C. or less to prepare a polyimide.

11. A method of preparing a polyimide powder, comprising: polymerizing a diamine monomer and a dianhydride monomer in an aqueous solution including a pyridine derivative compound as an aqueous catalyst to prepare a polyamic acid; and chemically imidizing the prepared polyamic acid to prepare a polyimide powder.

12. The method of claim 11, wherein the chemical imidization is performed by reacting the polyamic acid and a dehydrating agent.

13. The method of claim 12, wherein the dehydrating agent is included in a range of 0.5 to 3 equivalents with respect to 1 equivalent of the carboxyl group in the polyamic acid.

14. The method of claim 1, wherein the preparation of a polyimide powder includes: refluxing a chemical imidization product of the polyamic acid at 100 to 150 C. for 1 to 5 hours; and thermally imidizing and drying the refluxed product at less than 500 C.

15. The method of claim 9, the aqueous catalyst satisfies the following Chemical Formula 1: ##STR00008## in Chemical Formula 1, at least one of R.sub.1 to R.sub.3 is an alkylamine group, a hydroxyl group, an alkoxy group, a thiol group, a thioether group, an alkyl group, or a heterocyclic group.

16. A method of manufacturing a polyimide molded article, comprising processing a polyimide powder prepared by the method of claim 11 to manufacture a polyimide molded article.

17. A polyimide powder prepared by the method of claim 11.

18. The polyimide powder of claim 17, wherein an average particle diameter ranges from 1 to 1000 m, or a 5% thermal decomposition temperature (Td) measured using a thermogravimetric analyzer ranges from 400 to 700 C.

19. A polyimide molded article manufactured by the method of claim 16.

20. The polyimide molded article of claim 19, wherein a 5% thermal decomposition temperature (Td) measured using a thermogravimetric analyzer ranges from 400 to 700 C., or a coefficient of thermal expansion (CTE) measured by thermomechanical analysis ranges from 10 to 100 ppm/ C.

Description

DESCRIPTION OF DRAWINGS

[0099] FIG. 1 is a graph showing the results of an imidization rate experiment according to an example of the present application.

[0100] FIG. 2 is a graph showing a relationship between an aqueous catalyst content and a particle size.

[0101] FIG. 3 is a graph showing a relationship between a polymerization temperature and a particle size.

MODES OF THE INVENTION

[0102] Hereinafter, the present application will be described in further detail with reference to examples of the present application. However, it should be understood that the following examples are not intended to limit the scope of the present application.

Example 1A: Polyamic Acid Aqueous Solution Composition

[0103] 63.7 g of distilled water as a solvent was input into a reactor equipped with a temperature controller and filled with nitrogen. 1.0814 g (0.0094 mol) of p-phenylenediamine (pPDA) and 2.5 equivalents (relative to a carboxyl group) of 4-dimethylaminopyridine were added thereto, and the resulting mixture was dissolved using a mechanical stirrer at 25 C. for 1 hour. Then, 2.9422 g (0.01 mol) of 3,3,4,4-biphenyltetracarboxylic dianhydride (s-BPDA) was added, and the resulting mixture was polymerized while stirring at 70 C. for 18 hours to prepare a water-soluble polyamic acid.

[0104] Afterward, the obtained polyamic acid was casted onto a glass substrate with a bar coater, defoamed and dried in a vacuum oven at 25 C. for 2 hours, and sequentially thermally imidized at 80 C. for 30 minutes, at 120 C. for 30 minutes, at 180 C. for 30 minutes, and at 200 C. for 30 minutes to prepare a 25 m-thick polyimide film.

[0105] Various polyamic acid aqueous solution compositions and polyimide films according to examples and comparative examples were prepared under the composition conditions shown in Table 1 in the same manner as in Example 9A (the amount of each aqueous catalyst added in the examples and comparative examples was 2.5 equivalents relative to a carboxyl group).

TABLE-US-00001 TABLE 1 Solid Solution content viscosity Inherent Dianhydride Diamine Aqueous catalyst (wt %) (cps) viscosity Example 1A BPDA pPDA 4-(methylamino)pyridine 10 873 0.67 Example 2A BPDA pPDA 4-(dimethylamino)pyridine 20 19303 0.90 Example 3A BPDA pPDA 2-(dimethylamino)pyridine 10 8426 0.87 Example 4A BPDA ODA 4-(dimethylamino)pyridine 8 1834 0.52 Example 5A BPDA ODA 2-(dimethylamino)pyridine 8 1650 0.46 Example 6A OPDA pPDA 4-(dimethylamino)pyridine 2 508 0.45 Example 7A BPDA ODA 4-hydroxypyridine 8 2767 0.70 Example 8A BPDA ODA 2-hydroxypyridine 8 1021 0.63 Example 9A BTDA pPDA 4-methoxypyridine 10 1423 0.39 Example 10A BTDA pPDA 2-ethoxypyridine 10 1753 0.42 Example 11A BPDA pPDA 4-mercaptopyridine 10 2369 0.86 Example 12A BPDA pPDA 2-mercaptopyridine 10 2559 0.79 Example 13A 6FDA pPDA 4-(methylthio)pyridine 10 567 0.36 Example 14A 6FDA pPDA 2-(methylthio)pyridine 10 992 0.46 Example 15A BPDA m-TB 4-methylpyridine 7 1810 0.36 Example 16A BPDA m-TB 2-ethylpyridine 4 756 0.55 Example 17A BPDA m-TB 4-propylpyridine 7 980 0.45 Example 18A BPDA m-TB 2,4,6-trimethylpyridine 7 6508 0.95 Example 19A BPDA ABIZ 4-piperidinopyridine 9 1352 0.77 Example 20A BPDA pPDA 4-morpholinopyridine 15 17567 0.87 Example 21A BPDA pPDA 4-pyrrolidinopyridine 9 5142 0.74 Comparative BPDA pPDA NMP (organic solvent) 10 20000 2.01 Example 1A Comparative BPDA pPDA Pyridine Polymerization X Example 2A Comparative BPDA pPDA 1,2-dimethylimidazole 10 2369 0.96 Example 3A BPDA: 3,3,4,4-biphenyltetracarboxylic dianhydride BTDA: 3,3,4,4-benzophenonetetracarboxylic dianhydride pPDA: p-Phenylenediamine ODA: 4,4-diaminodiphenyl ether m-TB: 2,2-dimethylbenzidine ABIZ: 2-(p-aminophenyl)-5-aminobenzimidazole

[0106] Comparative Example 1A is an example in which polyamic acid is polymerized under an organic solvent, and Comparative Example 3A exhibited a low imidization rate at 200 C. even though polyamic acid was polymerized under water. Also, Comparative Example 2A showed that polyamic acid was not polymerized under water.

[0107] On the other hand, in the case of Examples 2A to 21A, it can be confirmed that polyamic acid was aqueous-polymerized, and a polyimide was prepared with a high imidization rate after the polymerized polyamic acid was thermally cured at 200 C.

1A. Measurement of Solution Viscosity

[0108] The solution viscosity of each polyamic acid composition prepared in the examples and comparative examples was measured at a shear rate of 30/s, a temperature of 25 C., and a plate gap of 1 mm using VT-550 commercially available from Haake, and results thereof are shown in Table 1.

2A. Inherent Viscosity

[0109] Each polyamic acid composition prepared in the examples and comparative examples was diluted so that a concentration became 0.5 g/dl (solvent:water) based on a solid concentration. The flow time (Ti) of the resulting solution was measured at 30 C. using a Cannon-Fenske viscometer No. 100. An inherent viscosity was calculated by the following equation using the flow time (To) of blank water, and results thereof are shown in Table 1.

[00002]$\mathrm{Inherent}\mathrm{viscosity}=\left\{\ln \left(T_1/T_0\right)\right\}/0.5$

3A. Measurement of Imidization Rate

[0110] The imidization rates of several examples and comparative examples were analyzed by an attenuated total reflectance (ATR) method using a Bruker ALPHA-P infrared spectrometer (IR). The imide bond strength calculated by IR analysis was represented as a percentage, and a ratio of the intensity of CN stretching of a polyimide prepared by thermally treating each polyamic acid aqueous solution of the examples and comparative examples at 200 C. relative to the intensity of CN stretching (1375 cm.sup.1) of a polyimide completely imidized at 400 C. was represented as a percentage. The imidization rate was calculated by the following Equation, and results thereof are shown in FIG. 1 and Table 2.

[00003]$\begin{array}{cc}\mathrm{Imidization}\mathrm{rate}\left(\%\right)=\left\{{\left(1375{\mathrm{cm}}^{-1}\right)}_{200C.}/{\left(1510{\mathrm{cm}}^{-1}\right)}_{200C.}\right\}/\left\{{\left(1375{\mathrm{cm}}^{-1}\right)}_{400C.}/{\left(1510{\mathrm{cm}}^{-1}\right)}_{400C.}\right\}& \left[\mathrm{Equation}\right]\end{array}$

[0111] FIG. 1 is a graph showing an imidization rate result according to Example 1. From FIG. 1, it can be confirmed that the polyamic acid aqueous solution composition according to Example 1 stably exhibited a high imidization rate upon low-temperature curing.

4A. Tensile Strength

[0112] Each polyimide film of several examples and comparative examples was cut to a width of 10 mm and a length of 40 mm, and modulus and tensile strength were measured in accordance with ASTM D-882 using an Instron 5564 UTM instrument commercially available from Instron. In this case, measurement was made at a cross head speed of 50 mm/min, and results thereof are shown in Table 2 below.

5A. 5% Thermal Decomposition Temperature

[0113] A thermogravimetric analyzer (Q5000 model commercially available from TA Instruments) was used, each polyimide film (molded article) of several examples and comparative examples was heated to 800 C. at 10 C./min under a nitrogen atmosphere, and a temperature at which a weight loss of 5% occurred was measured. Results thereof are shown in the following Table 2.

TABLE-US-00002 TABLE 2 200 C. imidization Tensile Td Dianhydride Diamine Aqueous catalyst rate (%) strength 5% Example 1A BPDA pPDA 4-(methylamino)pyridine 99.2 378 604 Example 2A BPDA pPDA 4-(dimethylamino)pyridine 97.4 255 591 Example 7A BPDA ODA 4-hydroxypyridine 91.8 299 553 Example 9A BTDA pPDA 4-methoxypyridine 98.4 167 550 Example 11A BPDA pPDA 4-mercaptopyridine 95.3 234 587 Example 13A 6FDA pPDA 4-(methylthio)pyridine 92.5 150 516 Example 18A BPDA m-TB 2,4,6-trimethylpyridine 98.6 312 576 Example 19A BPDA ABIZ 4-piperidinopyridine 90.1 240 559 Comparative BPDA pPDA NMP (organic solvent) 73.4 352 616 Example 1A Comparative BPDA pPDA 1,2-dimethylimidazole 88.6 275 589 Example 3A

Example 1B: Polyimide Powder

[0114] 446 g of distilled water as a solvent and 21.3798 g (1.25 equivalents relative to a carboxyl group) of 4-dimethylaminopyridine were input into a 1 L round bottom flask equipped with a temperature controller and a reflux condenser and filled with nitrogen, and the resulting mixture was dissolved using a mechanical stirrer at 25 C. Subsequently, 7.5698 g (0.07 mol) of p-phenylenediamine (pPDA) was dissolved, 20.5954 g (0.07 mol) of biphenyltetracarboxylic dianhydride (BPDA) was added, and polymerization was performed while stirring at 25 C. for 18 hours. Then, 16.54 mL (1.25 equivalents relative to a carboxyl group) of acetic anhydride was added, chemical imidization was performed while stirring for 20 minutes to precipitate a polyimide powder, and the precipitated polyimide powder was refluxed at 120 C. for 2 hours to prepare a polyimide powder.

[0115] The polyimide powder was washed and subjected to imidization and drying at 400 C. The dried polyimide powder was input into a mold, heated at 300 C. for 10 minutes, then pressurized at 20 MPa for 2 minutes, and heated at 450 C. for 5 minutes to obtain a polyimide molded article.

[0116] Various polyimide powders and polyimide molded articles according to examples and a comparative example were prepared under composition and reaction temperature conditions shown in Table 3 in the same manner as in Example 1B.

TABLE-US-00003 TABLE 3 Reaction temperature Dianhydride Diamine Aqueous catalyst ( C.) Example 1B BPDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 120 Example 2B BPDA pPDA 4-dimethylaminopyridine (2.0 equivalents) 120 Example 3B BPDA pPDA 4-dimethylaminopyridine (3.0 equivalents) 120 Example 4B BPDA pPDA 4-dimethylaminopyridine (3.5 equivalents) 120 Example 5B BPDA pPDA 4-dimethylaminopyridine (4.0 equivalents) 120 Example 6B BPDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 80 Example 7B BPDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 100 Example 8B BPDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 140 Example 9B PMDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 120 Example 10B OPDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 120 Example 11B BTDA pPDA 4-dimethylaminopyridine (2.5 equivalents) 120 Comparative BPDA pPDA dimethylimidazole (2.5 equivalents) 120 Example B BPDA: Biphenyltetracarboxylic dianhydride BTDA: 3,3,4,4-benzophenonetetracarboxylic dianhydride pPDA: p-Phenylenediamine PMDA: Pyromellitic dianhydride

[0117] In addition, the polyamic acid compositions prepared in the examples and comparative examples had a solid content of 10 wt %, and the properties thereof were evaluated by methods described below.

1B. Average Particle Diameter

[0118] The particle size of each powder prepared in the examples and comparative example, which was in a dispersed state in D.I water, was measured using a particle size analyzer (Microtrac S3000 model), and results thereof are shown in Table 4 below.

2B. 5% Thermal Decomposition Temperature

[0119] A thermogravimetric analyzer (Q5000 model commercially available from TA Instruments) was used, the polyimide molded article was heated to 800 C. at 10 C./min under a nitrogen atmosphere, and a temperature at which a weight loss of 5% occurred was measured. Results thereof are shown in Table 4 below.

3B. Coefficient of Thermal Expansion

[0120] Measurement was made by thermomechanical analysis (TMA, Q400 commercially available from TA instruments). In this case, a measurement temperature was 280 C., a heating rate was 10 C./min, and a force applied to pull the molded article was set to 0.05 N. Results thereof are shown in Table 4 below.

4B. Tensile Strength

[0121] The polyimide molded article was cut into a dog-bone-type piece with a width of 10 mm and a length of 40 mm, and modulus and tensile strength were measured in accordance with ASTM D-1708 using an Instron 5564 UTM instrument commercially available from Instron. In this case, measurement was made at a cross head speed of 5 mm/min, and results thereof are shown in the following Table 4.

TABLE-US-00004 TABLE 4 Average 5% thermal Coefficient particle decomposition of thermal Tensile diameter temperature expansion strength (m) ( C.) (ppm/ C.) (MPa) Example 1B 55.2 624 53.6 35.5 Example 2B 89.3 603 51.7 32.2 Example 3B 42.3 610 57.6 37.0 Example 4B 25.6 609 56.8 38.7 Example 5B 13.7 616 61.4 39.1 Example 6B 417.5 583 62.0 15.3 Example 7B 275.9 591 59.4 20.0 Example 8B 14.1 620 52.8 34.4 Example 9B 20.6 455 42.5 12.1 Example 10B 46.0 548 66.1 23.4 Example 11B 35.3 539 65.3 33.1 Comparative Example B

[0122] In the case of Comparative Example B, polyimide particles with a uniform size were not prepared.

[0123] In addition, FIG. 2 is a graph showing a relationship between an aqueous catalyst content and a particle size, and FIG. 3 is a graph showing a relationship between a polymerization temperature and a particle size. Specifically, in FIGS. 2 and 3, A is a result of Example 1B, B is a result of Example 2B, C is a result of Example 3B, D is a result of Example 4B, E is a result of Example 5B, F is a result of Example 6B, G is a result of Example 7B, and H is a result of Example 8B.

[0124] From FIGS. 2 and 3, it can be confirmed that the particle size can be controlled by an aqueous catalyst content and a polymerization temperature.