POLYIMIDE-BASED POLYMER FILM, SUBSTRATE FOR DISPLAY DEVICE, AND OPTICAL DEVICE USING THE SAME

Abstract

The present disclosure relates to a polyimide-based resin film which is synthesized by the reaction of an acid anhydride compound and a diamine compound having a specific structure, thereby capable of ensuring excellent flatness even under high temperature heat treatment conditions, and stably maintaining flatness even during further heat treatment, a substrate for display device, and an optical device using the same.

Claims

1. A polyimide-based resin film comprising a polyimide-based resin containing a polyimide repeating unit represented by the following Chemical Formula 1, wherein Bow is 40 m or less: ##STR00016## in the Chemical Formula 1, X.sub.1 is a tetravalent functional group represented by the following Chemical Formula 2, Y.sub.1 is an aromatic divalent functional group having at least 15 carbon atoms in which at least one electron-withdrawing group is substituted, ##STR00017## in the Chemical Formula 2, Ar is a polycyclic aromatic divalent functional group.

2. The polyimide-based resin film of claim 1, wherein a Bow variation of the polyimide-based resin film obtained by the following Equation 1 is 5 m or less:
Bow Variation (m)=Bow.sub.fBow[Equation 1] in the Equation 1, Bow.sub.f is a final Bow value of the film measured after further heat-treatment of the polyimide-based resin film at a temperature of 400 C. to 450 C. for 50 minutes to 200 minutes, and Bow is the Bow value of the polyimide-based resin film.

3. The polyimide-based resin film of claim 1, wherein the Bow is defined as a distance in a central axis between a thickness central plane and a reference plane of the polyimide-based resin film.

4. The polyimide-based resin film of claim 1, wherein the Bow is measured for the polyimide-based resin film having a thickness of 5 m or more and 30 m or less.

5. The polyimide-based resin film of claim 1, wherein the Bow is determined according to the following Equation 2.
Bow=(Bow of the laminate including a substrate film and a polyimide-based resin film coated on the substrate film)(Bow of the substrate film)[Equation 2]

6. The polyimide-based resin film of claim 1, wherein the polycyclic aromatic divalent functional group of Ar of the Chemical Formula 2 includes a fused cyclic divalent functional group containing at least two aromatic cyclic compounds.

7. The polyimide-based resin film of claim 1, wherein the polycyclic aromatic divalent functional group of Ar of the Chemical Formula 2 includes a fluorenylene group.

8. The polyimide-based resin film of claim 1, wherein the tetravalent functional group represented by Chemical Formula 2 includes a functional group represented by the following Chemical Formula 2-1: ##STR00018##

9. The polyimide-based resin film of claim 1, wherein the aromatic divalent functional group having at least 15 carbon atoms of Y.sub.1 includes at least three aromatic cyclic compounds.

10. The polyimide-based resin film of claim 9, wherein the aromatic divalent functional group having at least 15 carbon atoms includes at least one group selected from a triphenylene group, a quarterphenylene group, and a pentaphenylene group.

11. The polyimide-based resin film of claim 1, wherein the electron-withdrawing group includes at least one group selected from a haloalkyl group, a halogen group, a cyano group, a nitro group, a sulfonic acid group, a carbonyl group, and a sulfonyl group.

12. The polyimide-based resin film of claim 1, wherein the aromatic divalent functional group having at least 15 carbon atoms of Y.sub.1 includes a functional group represented by the following Chemical Formula 3: ##STR00019## in the Chemical Formula 3, T.sub.1 to T.sub.3 are the same as or different from each other, and each independently, an electron-withdrawing group, m1 to m3 are the same as or different from each other, at least one of m1 to m3 is an integer of 1 to 4, the rest are an integer of 0 to 4, and n is an integer of 1 to 10.

13. The polyimide-based resin film of claim 1, wherein the aromatic divalent functional group having at least 15 carbon atoms of Y.sub.1 includes a functional group represented by the following Chemical Formula 3-1: ##STR00020##

14. The polyimide-based resin film of claim 1, wherein the polyimide-based resin includes a combination of a tetracarboxylic dianhydride represented by the following Chemical Formula 4 and an aromatic diamine having or more carbon atoms in which at least one electron withdrawing group is substituted: ##STR00021## in the Chemical Formula 4, Ar is a polycyclic aromatic divalent functional group.

15. The polyimide-based resin film of claim 1, wherein the polyimide-based resin further includes a polyimide repeating unit represented by the following Chemical; Formula 5: ##STR00022## in the Chemical Formula 5, X.sub.2 is one of tetravalent functional groups represented by the following Chemical Formula 6, and Y.sub.2 is an aromatic divalent functional group having at least 15 carbon atoms in which at least one of electron-withdrawing groups is substituted, ##STR00023## in the Chemical Formula 6, R.sub.1 to R.sub.6 are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, L is any one selected from the group consisting of a single bond, O, CO, COO, S, SO, SO.sub.2, CR.sub.7R.sub.8, (CH.sub.2).sub.t, O(CH.sub.2).sub.tO, COO(CH.sub.2).sub.tOCO, CONH, phenylene or a combination thereof, where R.sub.7 and R.sub.8 are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a haloalkyl group having 1 to 10 carbon atoms, and t is an integer from 1 to 10.

16. The polyimide-based resin film of claim 15, wherein the polyimide repeating unit represented by Chemical Formula 5 and the polyimide repeating unit represented by Chemical Formula 1 are contained in an amount of 70 mol % or more with respect to the total repeating units contained in the polyimide-based resin.

17. The polyimide-based resin film of claim 1, wherein the polyimide-based resin film includes a cured product in which the polyimide-based resin is cured at a temperature of 400 C. or more.

18. A substrate for display device comprising the polyimide-based resin film of claim 1.

19. An optical device comprising the polyimide-based resin film of claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0127] FIG. 1 shows a cross-sectional view of measuring the bow of Experimental Example 1 and Experimental Example 2.

[0128] Hereinafter, embodiments of the present disclosure will be described in more detail by way of examples. However, these examples are provided for illustrative purposes only, and are not intended to limit the scope of the present disclosure.

EXAMPLE: PREPARATION OF POLYIMIDE FILM

Example 1

[0129] (1) Preparation of Polyimide Precursor Composition

[0130] The organic solvent. DEAc was filled in a reactor under a stream of nitrogen, and then 0.735 mol of a diamine represented by the following Chemical Formula a was added and dissolved at the same temperature while maintaining the temperature of the reactor to 25 C. To the solution to which the diamine represented by the following Chemical Formula a was added, 0.3675 mol of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (BPAF) represented by Chemical Formula b and 0.3675 mol of 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA) were added as an acid dianhydride at the same temperature, and stirred for 24 hours to give a polyimide precursor composition.

##STR00015##

[0131] (2) Preparation of Polyimide Film

[0132] The polyimide precursor composition was spin coated on a glass substrate. The polyimide precursor composition-coated glass substrate was put in an oven and heated at a rate of 5 C./min, and a curing process was performed by maintaining at 80 C. for 20 minutes and at 450 C. for 70 minutes, thereby preparing a polyimide film (thickness: 10 m).

Example 2

[0133] A polyimide film was prepared in the same manner as in Example 1, except that 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) was used as acid dianhydride instead of 3,3,4,4-Biphenyltetracarboxylic dianhydride (BPDA).

Example 3

[0134] A polyimide film was prepared in the same manner as in Example 1, except that pyromellitic dianhydride (PMDA) was used as acid dianhydride instead of 3,3,4,4-Biphenyltetracarboxylic dianhydride (BPDA).

COMPARATIVE EXAMPLE: PREPARATION OF POLYIMIDE FILM

Comparative Example 1

[0135] (1) Preparation of Polyimide Precursor Composition

[0136] The organic solvent. DEAc was filled in a reactor under a stream of nitrogen, and then 0.735 mol of 2,2-bis(trifluoromethyl)benzidine (TFMB) was added and dissolved at the same temperature while maintaining the temperature of the reactor to 25 C. To the solution to which 2,2-bis(trifluoromethyl)benzidine (TFMB) was added, 0.735 mol of 3,3,4,4-Biphenyltetracarboxylic dianhydride (BPDA) was added as an acid dianhydride at the same temperature, and stirred for 24 hours to give a polyimide precursor composition.

[0137] (2) Preparation of Polyimide Film

[0138] The polyimide precursor composition was spin coated on a glass substrate. The polyimide precursor composition-coated glass substrate was put in an oven and heated at a rate of 5 C./min, and a curing process was performed by maintaining at 80 C. for 20 minutes and at 450 C. for 70 minutes, thereby preparing a polyimide film (thickness: 10 m).

Comparative Example 2

[0139] A polyimide film was prepared in the same manner as in Comparative Example 1, except that 0.3675 mol of 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA) and 0.3675 mol of 4,4-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) were added as an acid dianhydride.

Experimental Example: Measurement of Physical Properties of Polyimide Films Obtained in Examples and Comparative Examples

[0140] The physical properties of the polyimide films obtained in Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1 below.

[0141] 1. Bow (Warpage)

[0142] The bow value of the polyimide film laminate (glass substrate+polyimide film) coated on a glass substrate obtained in each of Examples and Comparative Examples, and the bow value of only the glass substrate were measured, and the bow of the polyimide film was calculated according to the following Equation and described in Table 1 below.

Bow of Polyimide Film=(Bow of the polyimide film laminate coated on the glass substrate)(Bow of the substrate only)[Equation]

[0143] The bow is defined as a distance in a central axis between a thickness central plane and a reference plane (best fit plane of thickness central plane) as shown in FIG. 1, and the measurement of the bow was performed on a sample at room temperature using a stress analyzes (TENCOR FLX-2320).

[0144] 2. Heat Resistant Bow (Bow)

[0145] (1) Additional Condition for Two High-Temperature Heat Curing (450 070 Min.fwdarw.410 C./60 Min.fwdarw.445 C./60 Min Curing)

[0146] The bow value was measured after further curing the polyimide film laminate. (glass substrate+polyimide film) coated on the glass substrate obtained in each of Examples and Comparative Examples at 410 C. for 60 minutes, followed further curing at 445 C. for 60 minutes, and the bow value of only the glass substrate was measured, and the final bow (Bow.sub.f) of the polyimide film was obtained according to the following Equation. Using this, the bow variation (Bow) of the polyimide film was calculated according to the following Equation, and described as heat-resistant bow (Bow) in Table 1 below. The measurement method of the how is the same as described in Experimental Example 1.

[0147] (2) Additional Conditions for Four High Temperature Heat Curing (450 C./70 Min.fwdarw.445 C./20 Min.fwdarw.445 C./20 Min.fwdarw.410 C./60 Min)

[0148] The bow value was measured after further curing the polyimide film laminate (glass substrate+polyimide film) coated on the glass substrate obtained in each of Examples and Comparative Examples at 445 C. for 20 minutes, followed by further curing at 410 C. for 60 minutes, and the bow value of only the glass substrate was measured, and the final bow (Bow.sub.f) of the polyimide film was determined according to the following Equation. Using this, the bow variation (Bow) of the polyimide film was calculated according to the following Equation, and described as heat-resistant bow (Bow) in Table 1 below. The measurement method of the bow is the same as described in Experimental Example 1.

[0149] (3) Additional Conditions for Four High Temperature Heat Curing (450 C./70 Min.fwdarw.445 C./20 Min.fwdarw.445 C./20 Min.fwdarw.410 C./60 Min.fwdarw.445 C./60 Min Curing)

[0150] The bow value was measured after further curing the polyimide film laminate (glass substrate+polyimide film) coated on the glass substrate obtained in each of Examples and Comparative Examples at 445 C. for 20 minutes, followed further curing at 445 C. for 20 minutes, then further curing 410 C. for 60 minutes, and then further curing 445 C. for 60 minutes, and the bow value of only the glass substrate was measured, and the final bow (Bow.sub.f) of the polyimide film was determined according to the following Equation. Using this, the bow variation (Bow) of the polyimide film was calculated according to the following Equation, and described as heat-resistant bow (Bow) in Table 1 below. The measurement method of the bow is the same as described in Experimental Example L

Final bow of polyimide film(Bow.sub.f)=(Bow of the polyimide film laminate coated on the glass substrate after additional heat treatment)(Bow of the glass substrate)[Equation]

Bow variation of polyimide film (Bow)=(Final bow of the polyimide film obtained in Experimental Example 2 (Bow.sub.f))(Bow of the polyimide film obtained in Experimental Example 1)[Equation]

TABLE-US-00001 TABLE 1 Experimental Example Measurement Results of Examples and Comparative Examples Heat-resistant bow (Bow) Category 450 C./70 min .fwdarw. High 445 C./20 min .fwdarw. temperature Bow 450 C./70 min .fwdarw. 450 C./70 min .fwdarw. 445 C./20 min .fwdarw. curing 450 C./ 410 C./60 min .fwdarw. 445 C./20 min .fwdarw. 410 C./60 min .fwdarw. condition 70 min 445 C./60 min 410 C./60 min 445 C./60 min Example 1 30.2 m 0.1 m 0.4 m 1.9 m Example 2 31.5 m 0.3 m 0.6 m 2.6 m Example 3 28.9 m 0.1 m 0.3 m 1.4 m Comparative 56.4 m 5.6 m 8.4 m 11.8 m Example 1 Comparative 72.6 m 9.2 m 16.3 m 19.1 m Example 2

[0151] As shown in Table 1 above, the polyimide-based resin films of Examples 1 to 3 obtained through a curing process at 450 C. for 70 minutes showed a bow of 28.9 m or more and 31.5 m or less. Meanwhile, the polyimide-based resin films of Comparative Examples 1 and 2 obtained through a curing process at 450 C. for 70 minutes showed a bow of 56.4 m or more and 72.6 m or less, which is much higher than that of Examples.

[0152] Through this, it was confirmed that the polyimide-based resin films of Examples could have excellent flatness even during high temperature curing at 400 C. or more.

[0153] In addition, the polyimide-based resin films of Examples 1 to 3 showed a heat resistant bow (Bow) of 0.1 m or more and 2.6 m or less even when further heat treatment was performed at a high temperature of 400 C. or more.

[0154] On the other hand, when additional heat treatment was performed at a high temperature of 400 C. or more, the polyimide-based resin film of Comparative Examples 1 and 2 showed a heat resistant bow (Bow) of 5.6 m or more and 19.1 m or less, which was much higher than that of Examples.

[0155] Through this, it was confirmed that the polyimide-based resin films of Examples stably maintained the flatness even during high temperature heat treatment of 400 C. or more.

DESCRIPTION OF SYMBOLS

[0156] 1: thickness central plane [0157] 2: reference plane (Best fit plane of thickness central plane) [0158] 3: central axis [0159] 4: bow