KR20180107641A - Uniaxially stretched polyimide-based film and method for preparing the same - Google Patents

Abstract

The present invention relates to a uniaxially stretched polyimide-based film, and a production method thereof. According to the present invention, the uniaxially stretched polyimide-based film ensures excellent bending resistance, thereby being suitable to be used in foldable displays. To this end, the uniaxially stretched polyimide-based film contains a polyimide-based block copolymer.

Description

TECHNICAL FIELD [0001] The present invention relates to a monoaxially stretched polyimide film and a method for producing the same,

The present invention relates to a uniaxially stretched polyimide film excellent in bendability and a method for producing the same.

The aromatic polyimide resin is a polymer having mostly an amorphous structure and exhibits excellent heat resistance, chemical resistance, electrical properties, and dimensional stability due to its rigid chain structure. Such a polyimide resin is widely used as an electric / electronic material.

However, the polyimide resin has many limitations in its use because it has a dark brown limit due to the formation of a charge transfer complex (CTC) of π electrons present in the imide chain.

To solve the above limitation, and to obtain a colorless and transparent polyimide resin, a strong electron withdrawing, such as methyl (-CF ₃₎ group, trifluoromethyl group, the introduction of restricting the movement of π electrons; A method of reducing the formation of the CTC by introducing a sulfone (-SO ₂ -) group, an ether (-O-) group or the like into the main chain to form a bending structure; Or introducing an aliphatic cyclic compound to inhibit the formation of resonance structures of? Electrons have been proposed.

On the other hand, in order to apply the polyimide resin according to the proposals to a foldable display, the film produced using the polyimide resin should exhibit sufficient resistance to repetitive stress that folds due to folding characteristics, but there is still a limit to exhibit poor bending resistance do.

The present invention is to provide a uniaxially stretched polyimide-based film having excellent endurance.

The present invention further provides a process for producing the uniaxially stretched polyimide film.

The present invention relates to a uniaxially stretched polyimide-based film comprising a polyimide block copolymer, wherein the polyimide block copolymer comprises: a first repeating unit represented by the following formula (1); And a second repeating unit represented by the following formula (2): " (1) "

[Chemical Formula 1]

In Formula 1,

R ¹ are the same or different from each other in each repeating unit, each independently a single bond, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 _{-, -Si (CH 3) 2} -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 _{-, -C (CF 3) 2} -, -C (= O) NH-, or C6 to C30 divalent aromatic organic group, and;

R ² are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n1 and m1 are each independently an integer of 0 to 3;

Y ¹ is the same or different from each other in each repeating unit, and each independently contains a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} -, or -C (= O) NH-, and are connected by a;

E ¹ , E ² and E ³ are each independently a single bond or -NH-;

Z ¹ is the same or different from each other in each repeating unit and is a trivalent linking group derived from at least one compound selected from the group consisting of triacyl halide, tricarboxylic acid and tricarboxylate;

(2)

In Formula 2,

Y ² is the same or different from each other in each repeating unit, and each independently includes a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} -, or -C (= O) NH-, and are connected by a;

E ⁴ , E ⁵ and E ⁶ are each independently a single bond or -NH-;

Z ² is the same or different from each other in each repeating unit and is -C (= O) -AC (= O) derived from at least one compound selected from the group consisting of diacyl halide, dicarboxylic acid and dicarboxylate, O) -form divalent linking group;

In Z ² , A represents a divalent aromatic organic group having 6 to 20 carbon atoms, a divalent heteroaromatic organic group having 4 to 20 carbon atoms, or a divalent alicyclic group having 6 to 20 carbon atoms. - are located at para positions relative to A.

According to the present invention, there is also provided a process for producing the uniaxially stretched polyimide film.

Hereinafter, the uniaxially stretched polyimide film according to embodiments of the present invention and a method for producing the same will be described in detail.

Prior to that, unless explicitly stated to the contrary, the terminology is used merely to refer to a specific embodiment and is not intended to limit the invention.

The singular forms as used herein include plural forms as long as the phrases do not expressly contradict it.

Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components and / And the like.

In the present specification, terms including ordinals such as 'first' and 'second' are used for distinguishing one element from another, and are not limited by the ordinal number. For example, within the scope of the present invention, a first component may also be referred to as a second component, and similarly, a second component may be named as a first component.

The polyimide block copolymer

In the present invention, the polyimide-based copolymer includes the following first repeating unit and second repeating unit below. The specific composition of the first repeating unit and the second repeating unit is as follows.

(i) the first repeating unit

[Chemical Formula 1]

In the first repeating unit of the above formula (1)

R ¹ are the same or different from each other in each repeating unit, each independently a single bond, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 _{-, -Si (CH 3) 2} -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 _{-, -C (CF 3) 2} -, an aromatic organic group of -C (= O) NH-, or a divalent C 6 -C 30 (di-valent).

Here, the single bond means a case of chemically bonding to simply connect the groups R ¹ of the next amount in the formula (1).

The aromatic organic group having 6 to 30 carbon atoms may be present alone; Two or more aromatic organic groups are bonded to each other to form a condensed ring; Two or more aromatic organic group is -C (= O) a single bond, -O-, -S-, -, -CH (OH) -, -S (= O) 2 -, -Si (CH 3) 2 -, - (CH _{2) p} - (where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C (CF 3) 2 -, Or -C (= O) NH-.

Specifically, R ¹ is the same or different from each other in each repeating unit, and each independently represents a single bond, a single bond, -O-, -S-, -C (= O) -, -CH (OH) S (= O) ₂ -, -Si (CH ₃ ) ₂ -, - (CH ₂ ) _p - wherein ₁ ? _P ? 10, - (CF ₂ ) _q - _{C (CH 3) 2 -,} -C (CF 3) 2 - can be, or -C (= O) NH-. More specifically, R ¹ is the same as or different from each other in each repeating unit, and each independently may be a single bond, or -C (CF ₃ ) ₂ -.

In addition, R ² are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms.

N1 and m1 are each independently an integer of 0 to 3; Preferably, n1 and m1 each independently may be 0 or 1.

Y ¹ is the same or different from each other in each repeating unit, and each independently includes a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} -, or -C (= O) can be connected by NH-.

Specifically, Y ¹ may be a divalent organic group represented by the following structural formula:

In the above formula,

R ³ is the same or different from each other in each repeating unit and is independently a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;

R ⁴ each independently represents -H, -F, -Cl, -Br, -I, -CF ₃ , -CCl ₃ , -CBr ₃ , -CI ₃ , -NO ₂ , -CN, -COCH ₃ , -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n2 and m2 are each independently an integer of 1 to 4;

E ¹ , E ² and E ³ are each independently a single bond or -NH-. Here, the single bond means a case where E ¹ , E ² or E ³ is a chemical bond that simply connects groups or repeating units on both sides.

Z ¹ is a brancher having three reactive substituents, which are the same or different from each other in each repeating unit, and each is a group selected from the group consisting of triacyl halide, tricarboxylic acid and tricarboxylate Is a tri-valent linking group derived from the above compounds.

Specifically, Z ¹ is C 6 -C 20 aromatic tree acyl halides, C 6 -C 20 aromatic acid, having 6 to 20 carbon atoms the aromatic tricarboxylic acrylate, phosphorus-containing N 4 to 20 carbon atoms heteroaromatic tree acyl halide the aliphatic, having 4 to 20 carbon atoms in the N-containing heteroaromatic acid, having 4 to 20 carbon atoms in the N-containing heteroaromatic tricarboxylic rate, the alicyclic tree acyl halides having 6 to 20 carbon atoms having 6 to 20 carbon atoms tricarboxylic An alicyclic tricarboxylate having 6 to 20 carbon atoms, and an alicyclic tricarboxylate having 6 to 20 carbon atoms.

More specifically, Z ¹ can be selected from the group represented by the following structure:

For example, Z ¹ can be selected from the group consisting of benzene 1,3,5-benzenetricarbonyl trichloride, benzene 1,2,4-benzenetricarbonyl trichloride, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, trimethylbenzene 1 , Trimethyl 1,3,5-benzenetricarboxylate, and trimethyl 1,2,4-benzenetricarboxylate. In the present invention, at least one selected from the group consisting of trimethyl 1,3,5-benzenetricarboxylate and trimethyl 1,2,4- May be a trivalent linking group derived from a compound.

Preferably, the first repeating unit may include a repeating unit represented by the following formula (1-1):

[Formula 1-1]

In Formula 1-1,

R ¹ are the same or different from each other in each repeating unit, each independently a single bond, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 _{-, -Si (CH 3) 2} -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 _{-, -C (CF 3) 2} -, -C (= O) NH-, or C6 to C30 divalent aromatic organic group, and;

R ² and R ⁴ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3 , -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

R ³ is the same or different from each other in each repeating unit and is independently a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;

n1 and m1 are each independently an integer of 0 to 3;

n2 and m2 are each independently an integer of 1 to 4;

E ¹ , E ² and E ³ are each independently a single bond or -NH-;

Z ¹ is the same or different from each other in each repeating unit and is a trivalent linking group derived from at least one compound selected from the group consisting of triacyl halide, tricarboxylic acid and tricarboxylate.

More specifically, in Formula 1-1,

R ¹ is the same or different from each other in each repeating unit, and each independently is a single bond or -C (CF ₃ ) ₂ -;

Z ¹ is selected from the group consisting of benzene 1,3,5-benzenetricarbonyl trichloride, 1,2,4-benzenetricarbonyl trichloride, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, trimethylbenzene 1,3,5 Derived from at least one compound selected from the group consisting of trimethyl 1,3,5-benzenetricarboxylate and trimethyl 1,2,4-benzenetricarboxylate. May be a trivalent linking group.

More preferably, the first repeating unit may include a repeating unit represented by the following general formula 1-2 or 1-3:

[Formula 1-2]

[Formula 1-3]

In Formulas 1-2 and 1-3,

R ² and R ⁴ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3 , -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n1 and m1 are each independently an integer of 0 to 3;

n2 and m2 are each independently an integer of 1 to 4;

As described above, the block copolymerized polyimide block copolymer including the first repeating unit in which a brancher having three reactive substituents is introduced into a polyimide chain having a linear structure has a low haze, Mechanical properties.

Particularly, the above-mentioned brancher imparts a network structure to the copolymer while preventing the formation of a charge transfer complex between the polymer chains, and the block copolymer including the repeating unit containing the repeating unit may have a stable and stable network structure. Due to this network structure, the polyimide-based block copolymer exhibits significantly reduced haze and improved transparency compared to polymers without branching.

(ii) Second  Repeating unit

(2)

On the other hand, in the second repeating unit of Formula 2,

Y ² is the same or different from each other in each repeating unit, and each independently includes a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} - and it is connected by a, or -C (= O) NH-.

Specifically, Y ² may be a divalent organic group represented by the following structural formula:

In the above formula,

R ⁵ is the same or different from each other in each repeating unit, and each independently represents a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;

R ⁶ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n3 and m3 are each independently an integer of 1 to 4;

E ⁴ , E ⁵ and E ⁶ are each independently a single bond or -NH-. Here, the single bond means a case where E ⁴ , E ⁵ or E ⁶ is a chemical bond that simply connects groups or repeating units on both sides.

Z ² is the same as or different from each other in each repeating unit and is -C (= O) -AC (= O) derived from at least one compound selected from the group consisting of diacyl halide, dicarboxylic acid and dicarboxylate, (= O) -form divalent linking group;

Wherein A is a divalent aromatic organic group having 6 to 20 carbon atoms, a divalent heteroaromatic organic group having 4 to 20 carbon atoms, or a divalent alicyclic group having 6 to 20 carbon atoms, - are located at para positions relative to A.

Specifically, Z ² can be selected from the group represented by the following structural formula:

In the above formula,

R ¹¹ and R ¹² each independently represent a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an organic group having 6 to 10 carbon atoms, which is independently -H, -F, -Cl, -Br, RTI ID = 0.0 > 20 < / RTI >

a1 and a2 are each independently an integer of 0 to 3;

a3 is an integer of 0 to 2;

More specifically, Z ² can be selected from the group represented by the following structural formula:

For example, Z ² may be selected from the group consisting of terephthaloyl chloride (TPC), terephthalic acid, cyclohexane-1,4-dicarbonyl chloride, cyclohexane- Cyclohexane-1,4-dicarboxylic acid, pyridine-2,5-dicarbonyl chloride, pyridine-2, 5-dicarboxylic acid, 2,5-dicarboxylic acid, pyrimidine-2,5-dicarbonyl chloride, pyrimidine-2,5-dicarboxylic acid, 4, (BPC) derived from at least one compound selected from the group consisting of 4,4'-biphenyldicarbonyl chloride, 4,4'-biphenyldicarbonyl chloride and 4,4'-biphenyldicarboxylic acid. May be a divalent linking group.

Preferably, the second repeating unit may include a repeating unit represented by the following formula (2-1):

[Formula 2-1]

In Formula 2-1,

R ⁵ is the same or different from each other in each repeating unit, and each independently represents a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;

R ⁶ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n3 and m3 are each independently an integer of 1 to 4;

E ⁴ , E ⁵ and E ⁶ are each independently a single bond or -NH-;

Z ² is the same as or different from each other in each repeating unit and is selected from the group represented by the following structural formula:

More preferably, the second repeating unit may include a repeating unit represented by the following formula (2-2) or (2-3):

[Formula 2-2]

[Formula 2-3]

In the above Formulas 2-2 and 2-3,

R ⁶ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n3 and m3 are each independently an integer of 1 to 4;

(Iii) the third repeating unit

Meanwhile, the polyimide block copolymer may further include a third repeating unit represented by the following formula (3). The third repeating unit may further include the third repeating unit to further improve the hardness of the film after the film is manufactured.

(3)

In the third repeating unit of the above formula (3)

Y ³ is the same as or different from each other in each repeating unit, and each independently includes a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} - and it is connected by a, or -C (= O) NH-.

Specifically, Y ³ may be a divalent organic group represented by the following structural formula:

In the above formula,

R ⁷ is the same or different from each other in each repeating unit and each independently represents a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;

R ⁸ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n4 and m4 are each independently 1 to 4;

In addition, E ^7, E ⁸ and E ⁹ is a single bond or -NH-, each independently. Here, the single bond means a case where E ⁷ , E ^8, and E ⁹ are chemical bonds that simply connect groups or repeating units on both sides.

Z ³ is the same or different from each other in each repeating unit and is -C (= O) -A (= O) derived from at least one compound selected from the group consisting of diacyl halide, dicarboxylic acid and dicarboxylate A divalent linking group of the form -C (= O) -;

In Z ³ , A 'is a divalent aromatic organic group having 6 to 20 carbon atoms, a divalent heteroaromatic organic group having 4 to 20 carbon atoms, or a divalent alicyclic group having 6 to 20 carbon atoms, and two -C ) - are located at meta positions with respect to A '.

Specifically, Z ³ can be selected from the group represented by the following structural formula:

In the above formula,

R ¹³ is a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms, such as -H, -F, -Cl, -Br, ego;

a4 is an integer of 0 to 3;

a5 is an integer of 0 to 2;

More specifically, Z < ³ > can be selected from the group represented by the following structural formula:

For example, Z ³ may be selected from the group consisting of isophthaloyl dichloride (IPC), isophthalic acid, cyclohexane-1,3-dicarbonyl chloride, Cyclohexane-1,3-dicarboxylic acid, pyridine-3,5-dicarbonyl chloride, pyridine-3,5-dicarboxylic acid (pyridine- -3,5-dicarboxylic acid, pyrimidine-2,6-dicarbonyl chloride, and pyrimidine-2,6-dicarboxylic acid. ≪ / RTI > may be a divalent linking group derived from at least one compound selected from the group consisting of < RTI ID = 0.0 >

Preferably, the third repeating unit may include a repeating unit represented by the following formula (3-1): < EMI ID =

[Formula 3-1]

In Formula 3-1,

R ⁷ is the same or different from each other in each repeating unit and each independently represents a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;

R ⁸ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n4 and m4 are each independently 1 to 4;

E ⁷ , E ⁸ and E ⁹ are each independently a single bond or -NH-;

Z ³ is the same as or different from each other in each repeating unit and is selected from the group represented by the following structural formula:

More preferably, the third repeating unit may include a repeating unit represented by the following formula (3-2):

[Formula 3-2]

In the above formula (3-2)

R ⁸ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;

n4 and m4 are each independently 1 to 4;

On the other hand, in the above-mentioned polyimide block copolymer, the molar ratio of the first repeating unit: the second repeating unit may be 1:10 to 10: 1. For example, the molar ratio of the first repeating unit to the second repeating unit may be 1: 5 to 5: 1.

Z ¹ introduced into the first repeating unit is a brancher that imparts a network structure to the copolymer, and a network having a stable and stable structure can be formed in the copolymer by the block copolymerization of the repeating unit containing the branching agent . Therefore, when the weight ratio of the first repeating unit is too low, the network structure may not be sufficiently formed in the copolymer, and the effect of improving the physical properties may be insignificant. However, if the weight ratio of the first repeating unit is too high, gelation may occur during the polymerization.

When the polyimide block copolymer further comprises a third repeating unit, the molar ratio of the first repeating unit: the second repeating unit: the third repeating unit is 1: 9.9: 0.1 to 10: 0.1: 0.9. For example, the molar ratio of the first repeating unit: the second repeating unit: the third repeating unit may be 1: 0.2: 0.8 to 1: 0.8: 0.2.

As described above, the polyimide block copolymer including both the first repeating unit, the second repeating unit, and the third repeating unit can be obtained by a method in which the transparency of the produced film according to the first repeating unit into which the brancher (Z ¹ ) effect and the two -C (= O) - as well as improved processability effect of the second repeating units of the Z ² which is located at the para position introduced into two -C (= O) - Z which is located in the meta-position ³ can be expected to improve the hardness of the produced film according to the second repeating unit.

In addition, the polyimide block copolymer has a network of a stable and stable structure, and thus can have a higher molecular weight than a polyimide resin having a general linear structure. Specifically, the polyimide block copolymer may have a weight average molecular weight of 100,000 to 1,000,000 g / mol, and preferably 200,000 to 800,000 g / mol.

Meanwhile, the polyimide block copolymer may be prepared by mixing a compound forming the first repeating unit in an appropriate solvent to initiate a reaction; Adding a compound forming the second repeating unit to the reaction mixture of the above step and reacting; And adding a compound such as acetic anhydride or pyridine to the reaction mixture to induce a chemical imidization reaction.

When the polyimide-based block copolymer further comprises the third repeating unit, mixing the compound forming the first repeating unit in an appropriate solvent to initiate the reaction; Adding a compound forming the second repeating unit to the reaction mixture of the above step and reacting; Adding a compound forming the third repeating unit to the reaction mixture of the above step and reacting; And adding a compound such as acetic anhydride or pyridine to the reaction mixture to induce a chemical imidization reaction.

The polyimide block copolymer may be prepared by low temperature solution polymerization, interfacial polymerization, melt polymerization, solid phase polymerization, or the like.

Uniaxially oriented polyimide film

The uniaxially stretched polyimide film according to the present invention includes the above-mentioned polyimide block copolymer. In this case, the uniaxial stretching means that the unstretched film including the above-mentioned polyimide block copolymer is stretched in one of the machine direction (MD) and the transverse direction (TD).

As a result of continuous research by the present inventors, uniaxially stretched polyimide films have stronger interchain interactions due to stretched polymer chains and improved mechanical properties as compared with unstretched polyimide films. (Folding Endurance).

The biaxiality of such a film can be measured by MIT test using an MIT Folding Endurance Tester. Specifically, the uniaxially stretched polyimide film has an angle of 135 deg. According to ISO 5626, a radius of curvature of 0.8 mm, a load of 250 g And when subjected to the MIT impact strength test in the TD direction at a speed of 175 rpm, breakage may occur at over 20,000 cycles. Preferably, the uniaxially stretched polyimide block copolymer film may undergo breakage in an MIT impact strength test under the above conditions at 25,000 cycles or more, 30,000 cycles or more, or 35,000 cycles or more.

In particular, the stretching direction of the uniaxial stretching of the polyimide-based film may be the TD direction. A polyimide-based film stretched only in the TD direction is preferable from the optical viewpoint. Since the stretching of the polyimide film in the MD direction is performed by the difference in speed between the winder and the unwinder, the film may be damaged due to slip or scratches at the portion abutted against the roll. However, The film to be stretched is fixed with a tender, and the film is stretched at a specific temperature by floating in the air, so that damage to the film can be prevented.

The stretching magnification of the polyimide-based film may be 1.05 to 2 times. The stretching aligns the copolymer and affects the properties of the stretched film produced according to the degree of stretching. More preferably, the stretching magnification of the uniaxial stretching is 1.05 to 1.5 times in the TD direction. This stretching magnification can be confirmed by a change in the length of the film before and after stretching.

As a result, the uniaxially stretched polyimide film can be used as a material for a folding display requiring high bending resistance.

Production method of uniaxially stretched polyimide film

The uniaxially stretched polyimide-based film described above is prepared by the following steps:

Preparing an unstretched polyimide-based film comprising a polyimide-based block copolymer; And

Uniaxially stretching the unstretched polyimide film.

First, an unstretched film containing the polyimide block copolymer is prepared by coating a polyimide block copolymer composition on an arbitrary support and then drying to form an unstretched film; And separating the unstretched film from the substrate.

Thereafter, this unstretched film is stretched 1.05 to 2 times in the TD direction. In this case, the uniaxial stretching can be performed at a temperature of 150 ° C to 400 ° C. Specifically, the uniaxial stretching may be performed at a temperature of 150 ° C to 250 ° C. Alternatively, the uniaxial stretching may be performed at a temperature of 300 ° C to 400 ° C, for example, a temperature of 350 ° C to 380 ° C. In particular, when the unstretched film is uniaxially stretched at a temperature of 380 DEG C, the stretching is performed at a temperature higher than the glass transition temperature of all the repeating units of the polyimide block copolymer, and the orientation and stretching of the polymer chains are effectively performed .

Also, the uniaxial stretching may be performed so that the thickness of the polyimide-based film is 20 to 200 탆, but it may vary depending on the applied product.

The uniaxially stretched polyimide film according to the present invention is excellent in bending resistance and is suitable for use in folding displays.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. However, the following embodiments are intended to illustrate the invention, but the invention is not limited thereto.

Production Example 1

1.01 eq. Of 2,2'-bis (trifluoromethyl) benzidine (TMFB) in a 250 mL round flask equipped with a dean-stark apparatus and a condenser; 4,4 '- (hexafluoroisopropylidene) diphthalic anhydride (FDA) 0.9825 eq .; And 0.005 eq. Of benzene 1,3,5-tricarbonyl trichloride (TMC) were dissolved in 60 ml of anhydrous dimethylacetamide (14 wt%) and the reaction was initiated at room temperature. The reaction mixture was stirred with ice water at 0 ° C for 4 hours under a nitrogen atmosphere.

Thereafter, the reaction product was taken out to room temperature, and 1.01 eq. Of terephthaloyl dichloride (TPC) was added thereto. And 120 ml of additional dimethylacetamide were added, and the mixture was stirred for 4 hours.

After the polyamic acid polymer was formed by the above reaction, acetic anhydride (10 eq.) Was added to the reaction mixture. And pyridine (10 eq.) Were added. The mixture was stirred for 15 hours in an oil bath at a temperature of 40 ° C to conduct a chemical imidization reaction.

After completion of the reaction, the mixture was precipitated in water and ethanol to obtain a polyimide block copolymer (weight average molecular weight: about 400,000 g / mol) containing the following first and second repeating units in a molar ratio of 1: 1.

[First Repeating Unit]

[Second Repeating Unit]

¹ H NMR (DMSO-d6, standard TMS) δ (ppm): 10.815 (s), 8.378 (a), 8.253 (d), 8.168 (d), 8.001 (d), 7.841 (d), 7.792 (s ), 7.789 (d)

Example 1

The polyimide-based copolymer obtained in Preparation Example 1 was dissolved in dimethylacetamide to prepare a polyimide-based copolymer composition containing about 15% (w / v) of the polyimide-based copolymer. The composition was cast on a PI substrate using a roll-to-roll machine, and then dried at 80 ° C, 140 ° C and 120 ° C to form an undrawn film having a thickness of 24 μm. Then, the unstretched film was separated from the PI substrate to obtain a polyimide-based unstretched film.

The obtained polyimide-based unstretched film was stretched by 15% in the TD direction at 350 캜 using a TD stretcher to prepare a uniaxially stretched polyimide film having a thickness of 21 탆.

Example  2 and 3

A film was produced using the same method as in Example 1 except that the polyimide-based copolymer obtained in Preparation Example 1 was stretched under the conditions shown in Table 1 below to prepare a uniaxially stretched polyimide-based film Respectively.

Comparative Example 1

A polyimide-based unstretched film was produced in the same manner as in Example 1, except that the polyimide-based copolymer obtained in Preparation Example 1 was not stretched.

Test Example 1

The polyimide-based films prepared in Examples 1 to 3 and Comparative Example 1 were evaluated for bending resistance in the following manner. The results are shown in Table 1 below.

1) Endurance: Endurance was measured using MIT Folding Endurance Tester (Cometech). Specifically, the produced film was cut into specimens having a width of 1 cm and a length of 7 cm, and then bending was repeated at an angle of 135 ° according to ISO 5626, a radius of curvature of 0.8 mm, a load of 250 g and a speed of 175 rpm , And the number of cycles until fracture was measured. At this time, the measurement was performed by dividing each of the TD direction in which the drawing was performed and the MD direction in which the drawing was not performed.

Stretching direction Stretching temperature
(° C) Stretching magnification
(ship) Number of breaks
(TD direction,
cycle) Number of breaks
(MD direction,
cycle) Example 1 TD 350 1.15 35,990 77,478 Example 2 TD 380 1.15 203,257 257,869 Example 3 TD 380 1.50 102,264 45,709 Comparative Example 1 - - - 14,043 16,054

Referring to Table 1, it can be seen that the film according to the uniaxially stretched film exhibits remarkably excellent bending resistance as compared with the film according to the unstretched comparative example.

Claims (20)

In a uniaxially stretched polyimide-based film comprising a polyimide block copolymer,
The polyimide-based block copolymer may contain,
A first repeating unit represented by the following formula (1); And
A second repeating unit represented by the following formula (2)
/ RTI >
Uniaxially stretched polyimide film:
[Chemical Formula 1]

In Formula 1,
R ¹ are the same or different from each other in each repeating unit, each independently a single bond, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 _{-, -Si (CH 3) 2} -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 _{-, -C (CF 3) 2} -, -C (= O) NH-, or C6 to C30 divalent aromatic organic group, and;
R ² are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
n1 and m1 are each independently an integer of 0 to 3;
Y ¹ is the same or different from each other in each repeating unit, and each independently contains a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} -, or -C (= O) NH-, and are connected by a;
E ¹ , E ² and E ³ are each independently a single bond or -NH-;
Z ¹ is the same or different from each other in each repeating unit and is a trivalent linking group derived from at least one compound selected from the group consisting of triacyl halide, tricarboxylic acid and tricarboxylate;
(2)

In Formula 2,
Y ² is the same or different from each other in each repeating unit, and each independently includes a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} -, or -C (= O) NH-, and are connected by a;
E ⁴ , E ⁵ and E ⁶ are each independently a single bond or -NH-;
Z ² is the same or different from each other in each repeating unit and is -C (= O) -AC (= O) derived from at least one compound selected from the group consisting of diacyl halide, dicarboxylic acid and dicarboxylate, O) -form divalent linking group;
In Z ² , A represents a divalent aromatic organic group having 6 to 20 carbon atoms, a divalent heteroaromatic organic group having 4 to 20 carbon atoms, or a divalent alicyclic group having 6 to 20 carbon atoms. - are located at para positions relative to A.
The method according to claim 1,
Wherein the uniaxially stretched polyimide film has a TD stretching direction.
The method according to claim 1,
The uniaxially stretched polyimide film has a stretching magnification of 1.05 to 2 times.
The method according to claim 1,
Wherein the first repeating unit comprises a repeating unit represented by the following formula (1-1): < EMI ID =
[Formula 1-1]

In Formula 1-1,
R ¹ are the same or different from each other in each repeating unit, each independently a single bond, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 _{-, -Si (CH 3) 2} -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 _{-, -C (CF 3) 2} -, -C (= O) NH-, or C6 to C30 divalent aromatic organic group, and;
R ² and R ⁴ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3 , -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
R ³ is the same or different from each other in each repeating unit and is independently a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;
n1 and m1 are each independently an integer of 0 to 3;
n2 and m2 are each independently an integer of 1 to 4;
E ¹ , E ² and E ³ are each independently a single bond or -NH-;
Z ¹ is the same or different from each other in each repeating unit and is a trivalent linking group derived from at least one compound selected from the group consisting of triacyl halide, tricarboxylic acid and tricarboxylate.
5. The method of claim 4,
In Formula 1-1,
R ¹ is the same or different from each other in each repeating unit, and each independently is a single bond or -C (CF ₃ ) ₂ -;
Z ¹ is selected from the group consisting of benzene 1,3,5-benzenetricarbonyl trichloride, 1,2,4-benzenetricarbonyl trichloride, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, trimethylbenzene 1,3,5 Derived from at least one compound selected from the group consisting of trimethyl 1,3,5-benzenetricarboxylate and trimethyl 1,2,4-benzenetricarboxylate. Monoaxially oriented polyimide film, which is a trivalent linkage group.
The method according to claim 1,
Wherein the first repeating unit comprises a repeating unit represented by the following general formula (1-2) or (1-3): a monoaxially oriented polyimide film:
[Formula 1-2]

[Formula 1-3]

In Formulas 1-2 and 1-3,
R ² and R ⁴ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3 , -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
n1 and m1 are each independently an integer of 0 to 3;
n2 and m2 are each independently an integer of 1 to 4;
The method according to claim 1,
Z ² is a monoaxially oriented polyimide film selected from the group consisting of the following structural formulas:

In the above formula,
R ¹¹ and R ¹² each independently represent a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an organic group having 6 to 10 carbon atoms, which is independently -H, -F, -Cl, -Br, RTI ID = 0.0 > 20 < / RTI >
a1 and a2 are each independently an integer of 0 to 3;
a3 is an integer of 0 to 2;
The method according to claim 1,
Wherein the second repeating unit comprises a repeating unit represented by the following formula (2-1): " (1) " a monoaxially oriented polyimide film:
[Formula 2-1]

In Formula 2-1,
R ⁵ is the same or different from each other in each repeating unit, and each independently represents a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;
R ⁶ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
n3 and m3 are each independently an integer of 1 to 4;
E ⁴ , E ⁵ and E ⁶ are each independently a single bond or -NH-;
Z ² is the same as or different from each other in each repeating unit and is selected from the group represented by the following structural formula:

The method according to claim 1,
Wherein the second repeating unit comprises a repeating unit represented by the following formula (2-2) or (2-3): a monoaxially oriented polyimide film:
[Formula 2-2]

[Formula 2-3]

In the above Formulas 2-2 and 2-3,
R ⁶ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
n3 and m3 are each independently an integer of 1 to 4;
The method according to claim 1,
A monoaxially stretched polyimide film further comprising a third repeating unit represented by the following formula (3)
(3)

In Formula 3,
Y ³ is the same as or different from each other in each repeating unit, and each independently includes a divalent aromatic organic group having 6 to 30 carbon atoms; The aromatic organic group is present alone; Two or more aromatic organic groups are bonded to each other to form a divalent condensed ring; Or two or more aromatic organic group is a single bond, a fluorenyl group, -O-, -S-, -C (= O) -, -CH (OH) -, -S (= O) 2 -, -Si ( _{CH 3) 2 -, - (} CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where _{1≤q≤10), -C (CH 3)} 2 -, -C ( CF _{3) 2} -, or -C (= O) NH-, and are connected by a;
E ⁷ , E ⁸ and E ⁹ are each independently a single bond or -NH-;
Z ³ is the same or different from each other in each repeating unit and is -C (= O) -A'-R '' derived from at least one compound selected from the group consisting of diacyl halide, dicarboxylic acid and dicarboxylate, C (= O) -form divalent linking group;
In Z ³ , A 'is a divalent aromatic organic group having 6 to 20 carbon atoms, a divalent heteroaromatic organic group having 4 to 20 carbon atoms, or a divalent alicyclic group having 6 to 20 carbon atoms, and two -C ) - are located at meta positions with respect to A '.
11. The method of claim 10,
Z ³ is a monoaxially stretched polyimide film selected from the group consisting of the following structural formulas:

In the above formula,
R ¹³ is a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms, such as -H, -F, -Cl, -Br, ego;
a4 is an integer of 0 to 3;
a5 is an integer of 0 to 2;
11. The method of claim 10,
Wherein the third repeating unit comprises a repeating unit represented by the following formula (3-1):
[Formula 3-1]

In Formula 3-1,
R ⁷ is the same or different from each other in each repeating unit and each independently represents a single bond, a fluorenylene group, -O-, -S-, -C (= O) -, -CH (OH) _{(= O) 2 -, -Si} (CH 3) 2 -, - (CH 2) p - ( where _{1≤p≤10), - (CF 2)} q - ( where 1≤q≤10), -C _{(CH 3) 2 -, -C} (CF 3) 2 -, or -C (= O) NH-, and;
R ⁸ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
n4 and m4 are each independently 1 to 4;
E ⁷ , E ⁸ and E ⁹ are each independently a single bond or -NH-;
Z ³ is the same as or different from each other in each repeating unit and is selected from the group represented by the following structural formula:

11. The method of claim 10,
Wherein the third repeating unit comprises a repeating unit represented by the following formula (3-2): < EMI ID =
[Formula 3-2]

In the above formula (3-2)
R ⁸ are each independently -H, -F, -Cl, -Br, -I, -CF 3, -CCl 3, -CBr 3, -CI 3, -NO 2, -CN, -COCH 3, -CO ₂ C ₂ H ₅ , a silyl group having three aliphatic organic groups having 1 to 10 carbon atoms, an aliphatic organic group having 1 to 10 carbon atoms, or an aromatic organic group having 6 to 20 carbon atoms;
n4 and m4 are each independently 1 to 4;
The method according to claim 1,
Wherein the molar ratio of the first repeating unit to the second repeating unit is 1:10 to 10: 1.
11. The method of claim 10,
Wherein the molar ratio of the first repeating unit: the second repeating unit: the third repeating unit is 1: 9.9: 0.1 to 10: 0.1: 0.9.
The method according to claim 1,
Wherein the polyimide block copolymer has a weight average molecular weight of 100,000 to 1,000,000 g / mol.
The method according to claim 1,
The uniaxially stretched polyisobutylene, which undergoes break at more than 20,000 cycles when subjected to an MIT tensile strength test in the TD direction at an angle of 135 ° according to ISO 5626, a radius of curvature of 0.8 mm, a load of 250 g and a speed of 175 rpm Mid-film.
Preparing an unstretched polyimide-based film comprising a polyimide-based block copolymer; And
Uniaxially stretching the unstretched polyimide film;
Based film according to any one of claims 1 to 17, wherein the uniaxially stretched polyimide film is a polyimide film.
19. The method of claim 18,
Wherein the uniaxial stretching is performed at a temperature of from 150 캜 to 400 캜.
19. The method of claim 18,
Wherein the uniaxial stretching is performed so that the thickness of the polyimide-based film is 20 to 200 占 퐉.