Colorless polyimide film containing fluorine and cardo structure and preparation method thereof

Abstract

A polyimide film contains fluorinated substituents and cardo structures. The polyimide film exhibits excellent heat-resistance, transparency and mechanical properties. The polyimide film has a glass-transition temperature (Tg) of at least 360° C., a coefficient of thermal expansion (CTE) of 50 ppm/° C. or lower, a modulus of at least 4.0 Gpa, a b* value of 5 or lower and yellowness index of 8 or less. The polyimide film can be used as a display substrate or an optical film in a liquid crystal display (LCD), an organic light-emitting diode (OLED) and in other fields where the characteristic features are required.

Claims

1. A polyamic acid solution, comprising: a product, containing at least one fluorinated substituent and one cardo structure, obtained by co-polymerizing, in an organic solvent, at least one diamine and at least one tetracarboxylic dianhydride; wherein the molar ratio of total amount of diamine to the total amount of tetracarboxylic dienhydride is in the range of from 0.98 to 1.1; wherein the at least one diamine is a monomer having Structural Formula 1; wherein the at least one tetracarboxylic dianhydride is a combination of three monomers selected from Structural Formula 3, Structural Formula 4, and Structural Formula 5, such that, in the tetracarboxylic dianhydride: Structural Formula 3 is present in the range of from 10 mol % to 30 mol %, Structural Formula 4 is present in the range of from 30 mol % to 80 mol %, and Structural Formula 5 is present in the range of from 5 mol % to 50 mol %; wherein Structural Formula 1 is: ##STR00007## wherein Structural Formula 3 is: ##STR00008## wherein Structural Formula 4 is: ##STR00009## in which the substituent Ar is selected from the group consisting of any of the following structures: ##STR00010## wherein Structural Formula 5 is: ##STR00011## in which, in Structural Formula 4 and Structural Formula 5, Q.sub.5, Q.sub.6 and Q.sub.7 are each independently selected from the group comprising a single bond, —O—, —S—, —SO.sub.2—, —C(═O)—, —C(═O)O—, —C(═O)NH—, a phenylene group and a combination thereof.

2. The polyarnic acid solution of claim 1, wherein: Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are each selected from the group consisting of: a hydrogen, a halogen atom, or a C.sub.1-10 fluoroalkyl containing a fluorine atom, wherein the alkyl group is selected from the group consisting of: a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group, and a naphthalenyl group.

3. The polyamic acid solution of claim 1, wherein the organic solvent is selected from the group consisting of: m-cresol, dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone and combinations thereof.

4. The polyamic acid solution of claim 1, wherein the solid content is in the range of from 15 to 35 wt %.

5. A transparent polyimide film manufactured from the polyamic acid solution of claim 1.

6. The polyimide film of claim 5, wherein: the polyimide film has the following features: a glass-transition temperature (Tg) of at least 350° C.; a coefficient of thermal expansion (CTE) not exceeding 50 ppm/CC, based on measuring two times at 50 to 250° C.; a birefringence not exceeding 0.06; a light transmittance b* value not exceeding 5; a yellowness index not exceeding 8; a modulus of at least 4.0 Gpa; and a transmittance of at least 88% at 550 nm, with a haze not exceeding 0.5%.

7. A substrate for a display or a semiconductor, comprising: the colorless transparent polyimide film of claim 5.

8. A polyamic acid solution, comprising: a product, containing at least one fluorinated substituent and one cardo structure, obtained by co-polymerizing, in an organic solvent, at least one diamine and at least one tetracarboxylic dianhydride; wherein the molar ratio of total amount of diamine to the total amount of tetracarboxylic dianhydride is in the range of from 0.98 to 1.1; wherein the at least one diamine is a combination of two monomers, one having Structural Formula 1 and the other having Structural Formula 2, such that the total diamine is in the range of from 60 mol % to 95 mol % Structural Formula 1; wherein the at least one tetracarboxylic dianhydride is a combination of two monomers, one having Structural Formula 3 and the other having Structural Formula 4, such that, in the tetracarboxylic dianhydride: Structural Formula 3 is present in the range of from 10 mol % to 40 mol %; and Structural Formula 4 is present in the range of from 60 moi % to 90 mol %; wherein Structural Formula 1 is: ##STR00012## wherein Structural Formula 2 is: ##STR00013## in which each of Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are independently selected from the group consisting of: a hydrogen, a halogen, a hydroxyl group, a thiol group, a nitro group, a C.sub.1-10 alkyl group, a C.sub.1-4 halogenoalkoxyl group, a C.sub.1-10 halogenoalkyl group, a cyano group and a C.sub.6-20 aryl group; wherein Structural Formula 3 is: ##STR00014## wherein Structural Formula 4 is: ##STR00015## in which the substituent Ar is selected from the group consisting of any of the following structures: ##STR00016## in which, in Structural Formula 4 Q.sub.5 is selected from the group consisting of: a single bond, —O—, —S—, —SO.sub.2—, —C(═O)—, —C(═O)O—, —C(═O)NH—, a phenylene group and a combination thereof.

9. The polyamic acid solution of claim 8, wherein: Q.sub.1, Q.sub.2, Q.sub.3 and Q.sub.4 are each selected from the group consisting of: a hydrogen, a halogen atom, or a C.sub.1-10 fluoroalkyl containing a fluorine atom, wherein the alkyl group is selected from the group consisting of: a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group, and a naphthalenyl group.

10. The polyamic acid solution of claim 8, wherein the organic solvent is selected from the group consisting of: m-cresol, dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone and combinations thereof.

11. The polyamic acid solution of claim 8, wherein the solid content is in the range of from 15 to 35 wt %.

12. A transparent polyimide film manufactured from the polyamic acid solution of claim 11.

13. The polyimide film of claim 12, wherein: the polyimide film has the following features: a glass-transition temperature (Tg) of at least 350° C.; a coefficient of thermal expansion (CTE) not exceeding 50 ppm/° C., based on measuring two times at 50 to 250° C.; a birefringence not exceeding 0.06; a light transmittance b* value not exceeding 5; a yellowness index not exceeding 8; a modulus of at least 4.0 Gpa; and a transmittance of at least 88% at 550 nm, with a haze not exceeding 0.5%.

14. A substrate for a display or a semiconductor, comprising: the transparent polyimide film of claim 12.

Description

BEST MODE

(1) In the present invention, examples will be described in more details below, but is not limited to the following examples.

(2) The polymer components used in the embodiment are described below and are all marketed products:

(3) TFMB: 2,2′-bis(trifluoromethyl)benzidine

(4) BAFL: 9,9′-bis(4-aminophenyl)fluorene

(5) FFDA: 9,9′-bis(4-amino-3-fluorophenyl)fluorene

(6) 6FDA: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride

(7) s-BPDA: 3,3′,4,4′-biphenyl tetracaboxylic dianhydride

(8) BPAF: 9,9′-bis(phthalic anhydride) fluorene

(9) CBDA: Cyclobutane-1,2,3,4-tetracarboxylic dianhydride

(10) Isoquinoline

(11) The methods for measuring the properties are as described below:

Light Transmittance, b*, Haze, Yellowness Index

(12) The Light Transmittance, b* value, Haze and yellowness index of the film in each of the examples and comparative examples was measured using a UV spectrophotometer (X-rite Ci7800), all the values were averaged.

Birefringence

(13) The birefringence of the film of each of the examples and comparative examples was measured at 637 nm in TE (Transverse Electric) mode and TM (Transverse Magnetic) mode using a prism coupler (Metricon 2010/M).

Glass-Transition Temperature (Tg))

(14) The glass-transition temperature of the films in each of the examples and comparative examples were measured with Dynamic Mechanical Analyzer (DMA850) under the conditions of load of 0.05N, a heating rate of 3° C./min and a nitrogen atmosphere at 200° C. to 500° C., and then a inflection point of a curve with the max value was recorded as a glass-transition temperature.

Coefficient of Thermal Expansion (CTE))

(15) The coefficient of thermal expansion (CTE) of the film in each of the examples and comparative examples were measured two times at 50˜250° C. with Thermo Mechanical Analyzer (TMA 71000), the heating rate of first test was 10° C./min and the second test was 5° C. min, and a load of 20 mN was applied. The residual stress may have remained in the thermally treated film, but it can be completely removed upon the first scan. Therefore, the second value of the present invention is represented as the actual CTE value.

EXAMPLES

Example 1

(16) In a 500 reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 230.49 g of dimethylacetamide (DMAc) was placed as a solvent. Then 25.618 g (0.08 mol) of TFMB, 6.969 g (0.02 mol) of BAFL were dissolved. Thereafter, 8.885 g (0.02 mol) of 6FDA and 23.538 g (0.08 mol) of s-BPDA were added to the diamine solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(17) Isoquinoline 3.25 g (0.0252 mol) was added to the polyamic acid solution with stirring for 1 hr. After degassing, the polyamic acid solution was applied on a substrate with a bar coater. The coating film was dried at 100° C. for 10 min, then peeled off from the substrate and fixed on stainless steel frame, and then heated from 150° C. to 300° C. for 30 min, and kept at 300° C. for 15 min, slowly cooled, and separated from the frame to obtain the polyimide film.

Example 2

(18) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 229.49 g of dimethylacetamide (DMAc) was placed as a solvent. Then 28.821 g (0.09 mol) of TFMB, 3.484 g (0.01 mol) of BAFL were dissolved. Thereafter, 8.885 g (0.02 mol) of 6FDA and 23.538 g (0.08 mol) of s-BPDA were added to the diamine solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(19) Isoquinoline 3.24 g (0.0251 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 3

(20) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 234.80 g of dimethylacetamide (DMAc) was placed as a solvent. Then 28.821 g (0.09 mol) of TFMB, 3.484 g (0.01 mol) of BAFL were dissolved. Thereafter, 13.327 g (0.03 mol) of 6FDA and 20.595 g (0.07 mol) of s-BPDA were added to the diamine solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(21) Isoquinoline 3.31 g (0.0256 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 4

(22) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 241.13 g of dimethylacetamide (DMAc) was placed as a solvent. Then 25.618 g (0.08 mop of TFMB, 6.969 g (0.02 mol) of BAFL were dissolved. Thereafter, 17.770 g (0.04 mol) of 6FDA and 17.653 g (0.06 mol) of s-BPDA were added to the diamine solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(23) Isoquinoline 3.40 g (0.0263 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 5

(24) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 241.40 g of dimethylacetamide (DMAc) was placed as a solvent. Then 28.821 g (0.09 mol) of TFMB, 3.844 g (0.01 mol) of FFDA were dissolved. Thereafter, 17.770 g (0.04 mol) of 6FDA and 17.653 g (0.06 mol) of s-BPDA were added to the diamine solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(25) Isoquinoline 3.40 g (0.0263 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 6

(26) in a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 243.68 g of dimethylacetamide (DMAc) was placed as a solvent. Then 25.618 g (0.08 mol) of TFMB, 7.688 g (0.02 mol) of FFDA were dissolved. Thereafter, 17.770 g (0.04 mol) of 6FDA and 17.653 g (0.06 mol) of s-BPDA were added to the diamine solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(27) Isoquinoline 3.44 g (0.0266 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 7

(28) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 240.13 g of dimethylacetamide (DMAc) was placed as a solvent. Then 32.023 g (0.1 mol) of TFMB was dissolved. Thereafter, 8.885 g (0.02 mol) of 6FDA, 17.653 g (0.06 mol) of s-BPDA and 9.169 g (0.02 mol) of BPAF were added to the TFMB solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(29) Isoquinoline 3.39 g (0.0262 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 8

(30) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 239.63 g of dimethylacetamide (DMAc) was placed as a solvent. Then 32.023 g (0.1 mol) of TFMB was dissolved. Thereafter, 13.327 g (0.03 mol) of 6FDA, 17.653 g (0.06 mol) of s-BPDA and 4.584 g (0.01 mol) of BPAF were added to the TFMB solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(31) Isoquinoline 3.38 g (0.0262 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Example 9

(32) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 238.36 g of dimethylacetamide (DMAc) was placed as a solvent. Then 32.023 g (0.1 mol) of TFMB was dissolved. Thereafter, 22.922 g (0.05 mol) of BPAF, 4.442 g (0.01 mol) of 6FDA and 7.844 g (0.04 mol) of CBDA were added to the TFMB solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(33) Isoquinoline 3.36 g (0.026 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Comparative Example 1

(34) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 228.49 g of dimethylacetamide (DMAc) was placed as a solvent. Then 32.023 q (0.1 mol) of TFMB was dissolved. Thereafter, 8.885 g (0.02 mol) of 6FDA and 23.538 g (0.08 mol) of s-BPDA were added to the TFMB solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(35) Isoquinoline 3.22 g (0.0249 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Comparative Example 2

(36) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 306.573 g of dimethylacetamide (DMAc) was placed as a solvent. Then 32.023 g (0.1 mol) of TFMB was dissolved. Thereafter, 17.77 g (0.04 mol) of 6FDA and 17.653 g (0.06 mid) of s-BPDA were added to the TFMB solution, respectively. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic acid solution with the solid content of 22 wt %.

(37) Isoquinoline 3.37 g (0.0261 mol) was added to the polyamic acid solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Comparative Example 3

(38) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 221.85 g of dimethylacetamide (DMAc) was placed as a solvent. Then 19.214 g (0.06 mol) of TFMB and 13.938 g (0.04 mol) of BAFL were dissolved. Thereafter, 29.422 g (0.1 mol) of s-BPDA was added to the diamine solution. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic add solution with the solid content of 22 wt %.

(39) Isoquinoline 3.13 g (0.0242 mol) was added to the polyamic add solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

Comparative Example 4

(40) In a 500 mL reactor, which was equipped with a stirrer, nitrogen inlet and a temperature controller, 271.04 g of dimethylacetamide (DMAc) was placed as a solvent. Then 32.023 g (0.1 mol) of TFMB was dissolved. Thereafter, 44.424 g (0.1 mol) of 6FDA was added to the diamine solution. The resulting solution was kept at room temperature and reacted for 12 hr to 24 hr, then obtained a polyamic add solution with the solid content of 22 wt %.

(41) Isoquinoline 3.8° g (0.0296 mol) was added to the polyamic add solution with stirring for 1 hr. And then a polyimide film was formed in the same way as in example 1.

(42) As shown in Tables 1 and 2 below, the polyimide film of Examples 1 to 9 of the present invention has a high transparency, and the glass-transition temperature is 360° C. or more, even close to 390° C. in addition, the polyimide film of the present invention has a coefficient of thermal expansion (CTE) of 50 ppm/° C. or less, a modulus of 4.0 Gpa or more, and a yellowness index of 8 or less. The Comparative Examples 1 to 4 of Table 2 show that the polyimide film exhibits an increased glass transition temperature by introducing a cardo structure. Besides, the polyimide film with a higher content of fluorinated substituent shows a higher transparency according to the Examples 1 to 9 of Table 1 and Table 2. By the comparison of Example 1, Example 2 and Comparative Example 1, when a cardo structure was introduced on the basis of Comparative Example 1, the glass transition temperature could be significantly increased. While Comparative Example 3 shows that when the content of the cardo structure in diamine was too high, the mechanical properties and optical properties of the film were decreased (such as the yellowness index increased). Therefore, the polyimide film according to the present invention can be optimized by adjusting the contents of the fluorinated substituent and the cardo structure to possess the excellent heat-resistance, transparency and high modulus at the same time, and thus can be used as display substrate, optical film in liquid crystal display (LCD), organic light-emitting diode (OLED) and other fields.

(43) TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 polyamic acid (molar ratio) diamine TFMB 80 90 90 80 90 80 100 BAFL 20 10 10 20 FFDA 10 20 6FDA 20 20 30 40 40 40 20 tetracarboxylic s-BPDA 80 80 70 60 60 60 60 dianhydride BPAF 20 CBDA Catalyst (solid Isoquinoline 5 5 5 5 5 5 5 content/%) polyimide film film thickness (μm) 23 25 23 27 24 26 24 Tg (° C.) 389 377 376 369 367 365 370 CTE.sup.2nd@50-250° C./ppm .Math. ° C..sup.−1 34 33 39 45 49 49 46 Young's modular (Gpa) 4.2 4.4 4.3 4.0 4.0 4.0 4.3 b* 4.7 3.4 3.2 3.7 2.4 2.8 2.1 Yellowness Index 7.6 5.8 5.2 6.0 4.0 4.6 3.5 birefringence 0.04 0.05 0.04 0.03 0.03 0.02 0.03 Transmittance at 550 nm (%) 88.3 88.4 88.7 88.9 89.2 89.1 88.8 Haze (%) 0.23 0.3 0.31 0.32 0.22 0.15 0.15

(44) TABLE-US-00002 TABLE 2 Comp. Comp. Comp. Comp. Ex. 8 Ex. 9 Ex. 1 Ex. 2 Ex. 3 Ex. 4 polyamic acid (molar ratio) diamine TFMB 100 100 100 100 60 100 BAFL 40 FFDA 6FDA 30 10 20 40 100 tetracarboxylic s-BPDA 60 80 60 100 dianhydride BPAF 10 50 CBDA 40 Catalyst Isoquinoline 5 5 5 5 5 5 (solid content/%) polyimide film film thickness (μm) 23 26 26 25 25 25 Tg (° C.) 365 389 362 357 417 340 CTE.sup.2nd@50-250° C./ppm .Math. ° C..sup.−1 46 31 30 48 37 65 Young's modular (Gpa) 4.2 4.6 4.7 4.2 / 3.7 b* 2.0 1.3 2.5 2.0 9.1 1.3 Yellowness Index 3.5 2.5 4.24 3.5 14.1 2.5 birefringence 0.04 0.03 0.06 0.04 0.03 0.01 Transmittance at 550 nm (%) 89.0 89.3 88.6 89.3 87.4 90.7 Haze (%) 0.17 0.2 0.44 0.2 0.41 0.1