Plastic laminated film

Abstract

A plastic laminated film comprising a first layer comprising a polyamideimide copolymer and a second layer provided on at least one surface of the first layer and comprising a polyimide copolymer. The plastic laminated film has both excellent mechanical properties and UV weathering resistance while being colorless and transparent, and can be suitably used as cover films for various flexible or foldable devices.

Claims

1. A plastic laminated film comprising: a first layer comprising a polyamideimide copolymer, wherein the polyamideimide copolymer is an imide of a polyamic acid resulting from copolymerizing an aromatic diamine monomer, a dianhydride monomer, and an aromatic dicarbonyl monomer, and a second layer provided on at least one surface of the first layer and comprising a polyimide copolymer, wherein the polyimide copolymer is an imide of a polyamic acid resulting from copolymerizing an aromatic diamine monomer and a dianhydride monomer, wherein each dianhydride monomer is an aromatic dianhydride monomer, cyclobutane tetracarboxylic dianhydride, or cyclopentane tetracarboxylic dianhydride, and wherein the plastic laminate film has ΔYI represented by the following Mathematical Formula 1 of 2.0 or less: [Mathematical Formula 1]
ΔYI=YI.sub.1−YI.sub.0 wherein, in Mathematical Formula 1, YI.sub.0 and YI.sub.1 are yellowness indexes of the film measured according to ASTM D1925, where YI.sub.0 is an initial yellowness index of the film, and YI.sub.1 is a yellowness index of the film exposed to ultraviolet light and moisture for 96 hours according to ASTM G53, and wherein the plastic laminated film has a transmittance of 88% or more with respect to visible light having a wavelength of 550 nm at a thickness of 50±5 μm, and a transmittance of 13% or less with respect to ultraviolet light having a wavelength of 388 nm at a thickness of 50±5 μm.

2. The plastic laminated film of claim 1, wherein the second layer further comprises a silane-based compound in the polyimide copolymer.

3. The plastic laminated film of claim 2, wherein the silane-based compound comprises tetraethoxysilane.

4. The plastic laminated film of claim 1, wherein YI.sub.0 is 4.5 or less and YI.sub.1 is 6.0 or less.

5. The plastic laminated film of claim 1, wherein each aromatic diamine monomer is independently at least one compound selected from the group of 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine, 4,4′-diaminodiphenyl sulfone, 4,4′-(9-fluorenylidene)dianiline, bis(4-(4-aminophenoxy)phenyl)sulfone, 2,2′,5,5′-tetrachlorobenzidine, 2,7-diaminofluorene, 4,4-diaminooctafluorobiphenyl, m-phenylenediamine, p-phenylenediamine, 4,4′-oxydianiline, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(4-aminophenoxy)benzene, and 4,4′-diaminobenzanilide; each aromatic dianhydride monomer is independently at least one compound selected from the group of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride, 2,2-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic anhydride, and bis(3,4-dicarboxyphenyl)sulfone dianhydride; and the aromatic dicarbonyl monomer is at least one compound selected from the group of terephthaloyl chloride, isophthaloyl chloride, biphenyldicarbonyl chloride, terephthalic acid, pyridine-2,5-dicarbonyl chloride, pyridine-2,5-dicarboxylic acid, pyrimidine-2,5-dicarbonyl chloride, pyrimidine-2,5-dicarboxylic acid, 4,4′-biphenyldicarbonyl chloride, and 4,4′-biphenyldicarboxylic acid.

6. The plastic laminated film of claim 1, wherein a thickness ratio of the first layer and the second layer is 1:0.01 to 1:0.2.

7. The plastic laminated film of claim 1, wherein the film has a thickness of 10 to 100 μm.

8. A device comprising the plastic laminated film of claim 1 as a cover film, wherein the device is a flexible or foldable device.

9. The plastic laminated film of claim 1, wherein each aromatic diamine monomer is independently at least one compound selected from the group of 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine, 4,4′-diaminodiphenyl sulfone, 4,4′-(9-fluorenylidene)dianiline, bis(4-(4-aminophenoxy)phenyl)sulfone, 2,2′,5,5′-tetrachlorobenzidine, 2,7-diaminofluorene, 4,4-diaminooctafluorobiphenyl, m-phenylenediamine, p-phenylenediamine, 4,4′-oxydianiline, 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(4-aminophenoxy)benzene, and 4,4′-diaminobenzanilide.

10. The plastic laminated film of claim 1, wherein each aromatic dianhydride monomer is independently at least one compound selected from the group of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride, 2,2-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, benzophenone tetracarboxylic dianhydride, pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, oxydiphthalic anhydride, and bis(3,4-dicarboxyphenyl)sulfone dianhydride.

11. The plastic laminated film of claim 1, wherein the aromatic dicarbonyl monomer is at least one compound selected from the group of terephthaloyl chloride, isophthaloyl chloride, biphenyldicarbonyl chloride, terephthalic acid, pyridine-2,5-dicarbonyl chloride, pyridine-2,5-dicarboxylic acid, pyrimidine-2,5-dicarbonyl chloride, pyrimidine-2,5-dicarboxylic acid, 4,4′-biphenyldicarbonyl chloride, and 4,4′-biphenyldicarboxylic acid.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a cross-section of a plastic laminated film according to an embodiment of the present disclosure.

(2) FIG. 2 shows a cross-section of a plastic laminated film according to anther embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(3) Hereinafter, preferred examples are provided for better understanding. However, these examples are for illustrative purposes only, and the invention is not intended to be limited by these examples.

Preparation Example 1

(4) In a 1000 mL reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, and a temperature controller, 42.5 g of dimethylacetamide was placed while slowly flowing nitrogen, the temperature of the reactor was adjusted to 25° C., and 4.4354 g (0.0138507 mol) of 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine was added thereto to be completely dissolved. While maintaining the temperature of the solution at 25° C., 0.815 g (0.0027701 mol) of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride was added thereto to be dissolved.

(5) After the temperature of the solution was cooled down to −10° C., 0.2812 g (0.0013851 mol) of isophthaloyl chloride and 1.9684 g (0.0096955 mol) of terephthaloyl chloride were added thereto and polymerized for 12 hours or more to obtain a polyamic acid-containing varnish having a solid content concentration of 15% (w/V).

(6) Dimethylacetamide was added to the prepared polyamic acid-containing varnish to dilute the solid content concentration to 5 wt % or less, followed by precipitation of the solid content with 10 L of methanol. The precipitated solid content was filtered and then dried in a vacuum oven at 100° C. for 6 hours or more to obtain a polyamideimide copolymer in the form of a solid (weight average molecular weight: 110,000 g/mol).

(7) The polyamideimide copolymer was dissolved in dimethylacetamide to obtain a varnish containing polyamideimide having a solid content concentration of 15% (w/V).

Preparation Example 2

(8) In a 100 mL reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, and a temperature controller, 42.5 g of dimethylacetamide was placed while slowly flowing nitrogen, the temperature of the reactor was adjusted to 25° C., and 3.9088 g (0.012206 mol) of 2,2′-bis(trifluoromethyl)-4,4′-biphenyldiamine was added thereto to be completely dissolved. While maintaining the temperature of the solution at 25° C., 3.5912 g (0.012206 mol) of 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride was added thereto to be dissolved.

(9) After the temperature of the solution was cooled down to −10° C., it was polymerized for 12 hours or more to obtain a polyamic acid-containing varnish having a solid content concentration of 15 wt % (w/V) (weight average molecular weight: 80,000 g/mol).

Preparation Example 3

(10) 100 wt % of tetraethoxysilane based on the solid content was added to the polyamic acid-containing varnish according to Preparation Example 2 and stirred to prepare a varnish.

Example 1

(11) The polyamideimide-containing varnish of Preparation Example 1 was poured onto a substrate (UPILEX-75s, a polyimide film), applied using a film applicator in order to have a thickness of 49±1 μm after drying, and dried at 80° C. for 10 minutes to form a first coating layer.

(12) Next, the varnish of Preparation Example 2 was poured onto the first coating layer, applied using a film applicator in order to have a thickness of 0.5±0.25 μm after drying, and dried at 80° C. for 5 minutes to form a second coating layer.

(13) Then, the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 280° C. for 30 minutes while flowing nitrogen, and then the cured film was peeled to obtain a plastic laminated film.

Example 2

(14) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 1.0±0.25 μm after drying.

Example 3

(15) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 1.5±0.25 μm after drying.

Example 4

(16) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying.

Example 5

(17) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.5±0.25 μm after drying.

Example 6

(18) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 3.0±0.25 μm after drying.

Example 7

(19) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 3.5±0.25 μm after drying.

Example 8

(20) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 4.0±0.25 μm after drying.

Example 9

(21) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 4.5±0.25 μm after drying.

Example 10

(22) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 5.0±0.25 μm after drying.

Example 11

(23) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 5.5±0.25 μm after drying.

Example 12

(24) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 6.0±0.25 μm after drying.

Example 13

(25) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 6.5±0.25 μm after drying.

Example 14

(26) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 7.0±0.25 μm after drying.

Example 15

(27) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 7.5±0.25 μm after drying.

Example 16

(28) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 8.0±0.25 μm after drying.

Comparative Example 1

(29) The polyamideimide-containing varnish of Preparation Example 1 was poured onto a substrate (UPILEX-75s, a polyimide film), applied using a film applicator in order to have a thickness of 49±1 μm after drying, and dried at 80° C. for 10 minutes to form a coating layer.

(30) Then, the coating layer was fixed to a frame of a vacuum oven, followed by curing at 280° C. for 30 minutes while flowing nitrogen, and then the cured film was peeled to obtain a polyamideimide film.

Experimental Example 1

(31) The following characteristics were measured for the films of Examples 1 to 16 and Comparative Example 1, and the results are shown in Tables 1 and 2 below.

(32) (1) Yellowness index (Y.I.): The initial yellowness index (YI.sub.0) of the film was measured according to the method of ASTM D1925 using a UV-2600 UV-Vis Spectrometer (SHIMADZU).

(33) In addition, the film was exposed to ultraviolet light and moisture for 96 hours according to ASTM G53 [Practice for Operating Light- and Water-Exposure Apparatus (Fluorescent UV-Condensation Type) for Exposure of Nonmetallic Materials] using a QUV Accelerated Weathering Tester (Q-LAB), and then the yellowness index (YI.sub.1) of the film was measured according to the method of ASTM D1925.

(34) (2) Transmittance (T): The total light transmittance of the film was measured using a UV-2600 UV-Vis Spectrometer (SHIMADZU), and the transmittance (T.sub.0) with respect to visible light having a wavelength of 550 nm and the transmittance (T.sub.0) with respect to ultraviolet light having a wavelength of 388 nm is shown in Table 2.

(35) In addition, the film was exposed to ultraviolet light and moisture for 96 hours according to ASTM G53 [Practice for Operating Light- and Water-Exposure Apparatus (Fluorescent UV-Condensation Type) for Exposure of Nonmetallic Materials] using a QUV Accelerated Weathering Tester (Q-LAB), and then the transmittance (T.sub.1) of the film was measured in the same manner as above.

(36) TABLE-US-00001 TABLE 1 YI.sub.0 YI.sub.1 ΔYI Example 1 3.61 5.52 1.91 Example 2 3.69 5.09 1.40 Example 3 3.71 4.58 0.87 Example 4 3.74 4.52 0.78 Example 5 3.78 4.50 0.72 Example 6 3.81 4.49 0.68 Example 7 3.84 4.48 0.64 Example 8 3.86 4.41 0.55 Example 9 3.87 4.35 0.48 Example 10 3.90 4.35 0.45 Example 11 3.95 4.36 0.41 Example 12 4.01 4.40 0.39 Example 13 4.10 4.47 0.37 Example 14 4.11 4.53 0.42 Example 15 4.23 4.65 0.42 Example 16 4.36 4.74 0.38 Comparative 3.56 6.12 2.56 Example 1

(37) TABLE-US-00002 TABLE 2 T % (@550 nm) T % (@388 nm) T.sub.0 T.sub.1 T.sub.0 T.sub.1 Example 1 88.66 88.81 3.28 2.85 Example 2 88.63 88.87 2.86 2.59 Example 3 88.58 88.80 2.58 2.39 Example 4 88.55 88.74 2.46 2.08 Example 5 88.49 88.74 2.35 2.04 Example 6 88.49 88.72 2.27 2.00 Example 7 88.45 88.73 2.20 1.98 Example 8 88.47 88.70 2.26 1.94 Example 9 88.43 88.65 1.95 1.89 Example 10 88.42 88.67 1.99 1.87 Example 11 88.40 88.61 1.93 1.85 Example 12 88.42 88.58 1.90 1.83 Example 13 88.39 88.55 1.85 1.81 Example 14 88.35 88.52 1.70 1.81 Example 15 88.37 88.42 1.66 2.15 Example 16 88.33 88.44 1.43 1.65 Comparative 88.74 89.04 2.90 2.63 Example 1

(38) Referring to Table 1, as the YI.sub.1 value of the film according to Comparative Example 1 significantly increased to 6.12, the ΔYI value rapidly increased to 2.56.

(39) On the other hand, referring to Tables 1 and 2, the laminated films according to Examples 1 to 16 exhibited the transmittance equivalent level to that of the film of Comparative Example 1, and the ΔYI values were as small as 0.37 to 1.91, indicating excellent UV weathering resistance.

Example 17

(40) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 240° C. for 30 minutes while flowing nitrogen.

Example 18

(41) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 250° C. for 30 minutes while flowing nitrogen.

Example 19

(42) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 260° C. for 30 minutes while flowing nitrogen.

Example 20

(43) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 270° C. for 30 minutes while flowing nitrogen.

Example 21

(44) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 290° C. for 30 minutes while flowing nitrogen.

Example 22

(45) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 2 was applied in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 300° C. for 30 minutes while flowing nitrogen.

Comparative Example 2

(46) A polyamideimide film was obtained in the same manner as in Comparative Example 1, except that the coating layer was fixed to a frame of a vacuum oven, followed by curing at 240° C. for 30 minutes while flowing nitrogen.

Comparative Example 3

(47) A polyamideimide film was obtained in the same manner as in Comparative Example 1, except that the coating layer was fixed to a frame of a vacuum oven, followed by curing at 250° C. for 30 minutes while flowing nitrogen.

Comparative Example 4

(48) A polyamideimide film was obtained in the same manner as in Comparative Example 1, except that the coating layer was fixed to a frame of a vacuum oven, followed by curing at 260° C. for 30 minutes while flowing nitrogen.

Comparative Example 5

(49) A polyamideimide film was obtained in the same manner as in Comparative Example 1, except that the coating layer was fixed to a frame of a vacuum oven, followed by curing at 270° C. for 30 minutes while flowing nitrogen.

Comparative Example 6

(50) A polyamideimide film was obtained in the same manner as in Comparative Example 1, except that the coating layer was fixed to a frame of a vacuum oven, followed by curing at 290° C. for 30 minutes while flowing nitrogen.

Comparative Example 7

(51) A polyamideimide film was obtained in the same manner as in Comparative Example 1, except that the coating layer was fixed to a frame of a vacuum oven, followed by curing at 300° C. for 30 minutes while flowing nitrogen.

Experimental Example 2

(52) The yellowness index of the films of Examples 17 to 22 and Comparative Examples 2 to 7 were measured in the same manner as in Experimental Example 1, and the results are shown in Tables 3 and 4 below.

(53) TABLE-US-00003 TABLE 3 Curing temp (° C.) YI.sub.0 YI.sub.1 ΔYI Example 17 240 3.38 4.67 1.29 Example 18 250 3.46 4.73 1.27 Example 19 260 3.51 4.75 1.24 Example 20 270 3.70 4.74 1.04 Example 4 280 3.74 4.52 0.78 Example 21 290 4.05 4.35 0.30 Example 22 300 4.20 4.35 0.15

(54) TABLE-US-00004 TABLE 4 Curing temp (° C.) YI.sub.0 YI.sub.1 ΔYI Comparative 240 3.40 6.67 3.27 Example 2 Comparative 250 3.45 6.62 3.17 Example 3 Comparative 260 3.48 6.64 3.16 Example 4 Comparative 270 3.51 6.47 2.96 Example 5 Comparative 280 3.56 6.12 2.56 Example 1 Comparative 290 3.70 6.17 2.47 Example 6 Comparative 300 3.87 6.14 2.27 Example 7

(55) Referring to Table 4, as the YI.sub.1 values of the films according to Comparative Examples 1 to 7 significantly increased from 6.12 to 6.67, the ΔYI values rapidly increased from 2.27 to 3.27.

(56) On the other hand, referring to Table 3, it was confirmed that the films of Examples 4 and 17 to 22 exhibited excellent UV weathering resistance because the ΔYI values are as small as 0.15 to 1.29. In addition, it was confirmed that the ΔYI value tended to decrease as the curing (heating) temperature of the film according to the examples increased in the range of 240 to 300° C.

Example 23

(57) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 240° C. for 30 minutes while flowing nitrogen.

Example 24

(58) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 250° C. for 30 minutes while flowing nitrogen.

Example 25

(59) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 260° C. for 30 minutes while flowing nitrogen.

Example 26

(60) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 270° C. for 30 minutes while flowing nitrogen.

Example 27

(61) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 280° C. for 30 minutes while flowing nitrogen.

Example 28

(62) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 290° C. for 30 minutes while flowing nitrogen.

Example 29

(63) A plastic laminated film was obtained in the same manner as in Example 1, except that the varnish of Preparation Example 3 was applied instead of the varnish of Preparation Example 2 in order to have a thickness of 2.0±0.25 μm after drying, and the first and second coating layers were fixed to a frame of a vacuum oven, followed by curing at 300° C. for 30 minutes while flowing nitrogen.

Experimental Example 3

(64) The yellowness index of the films of Examples 23 to 29 was measured in the same manner as in Experimental Example 1, and the results are shown in Table 5 below.

(65) TABLE-US-00005 TABLE 5 Curing temp (° C.) YI.sub.0 YI.sub.1 ΔYI Example 23 240 3.30 4.62 1.32 Example 24 250 3.39 4.60 1.21 Example 25 260 3.41 4.58 1.07 Example 26 270 3.44 4.55 0.91 Example 27 280 3.19 4.39 0.82 Example 28 290 3.21 3.90 0.69 Example 29 300 3.57 3.83 0.26

(66) Referring to Table 5, the films of Examples 23 to 29 in which the tetraethoxysilane-containing varnish of Preparation Example 3 was used showed a tendency that the increase of the YI.sub.0 value was slowed with an increase in the curing temperature, and had the small ΔYI value compared with the films of Examples 17 to 22 and Comparative Examples 1 to 7. Thus, it was confirmed that the films exhibit excellent UV weathering resistance while being colorless and transparent.

DESCRIPTION OF SYMBOLS

(67) 1: first layer including a polyamideimide copolymer

(68) 2: second layer including a polyimide copolymer

(69) 2′: second layer including a polyimide copolymer