KR20160067409A

KR20160067409A - Polyimide film for flexible susbtrate of photoelectronic device

Info

Publication number: KR20160067409A
Application number: KR1020140172737A
Authority: KR
Inventors: 이진호; 김경준; 박찬효; 홍예지
Original assignee: 주식회사 엘지화학
Priority date: 2014-12-04
Filing date: 2014-12-04
Publication date: 2016-06-14
Also published as: KR101757519B1

Abstract

The present invention relates to a polyimide film for a flexible substrate of a photoelectric device formed from a mixture of a polyimide precursor including a structure of Chemical formula 2 and a polyimide precursor not including a structure of Chemical formula 2, and more particularly, to a polyimide film for a flexible substrate of a photoelectric device increasing productivity and a process efficiency by omitting a processing step for applying adhesion and remarkably improving surface adhesion while ensuring an excellent mechanical property and high heat resistance without degrading an appearance characteristic of the prepared polyimide resin. In Chemical formula 2, R1, R2, R3, R4, R5 and R6 are as described in the detailed description of the present invention.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyimide film for a flexible substrate of a photoelectric device. BACKGROUND OF THE INVENTION [0002]

TECHNICAL FIELD The present invention relates to a polyimide film for a flexible substrate of a photoelectric device, and more particularly to a polyimide film having improved surface adhesion without being subjected to a pretreatment step for adding an adhesive force.

Recently, weight reduction and miniaturization of products have been emphasized in the field of display, and glass substrates which are currently used are heavy, fragile and difficult to be continuously processed. Therefore, plastic substrates having advantages of light, To mobile phones, notebook computers, PDAs, and the like.

In particular, polyimide (PI) resin has advantages that it is easy to synthesize and can form a thin film and does not require a crosslinking agent for curing. Recently, lightweight and refinement of electronic products has led to the development of LCD, PDP, OLED, And a flexible plastic display board having light and flexible properties are being studied.

A polyimide (PI) film produced by film-forming the polyimide resin is generally prepared by solution polymerization of an aromatic dianhydride and an aromatic diamine or aromatic diisocyanate to prepare a polyamic acid derivative, Refers to a high heat-resistant resin which is prepared by dehydrating and cyclizing cyclic rings.

Flexible devices are typically manufactured on the basis of high temperature thin film transistor (TFT) processes. The TFT process temperature may vary depending on the types of the semiconductor layer, the insulating film and the barrier layer included in the device during the manufacture of the flexible device, but usually a temperature of about 450 to 500 ° C is required. However, the polymer material capable of withstanding such a processing temperature is extremely limited, and polyimide known to have excellent heat resistance is mainly used.

In order to use the polyimide resin on a circuit board, a semiconductor substrate, or a flexible display substrate, the polyimide resin must have excellent adhesion to a silicon wafer or glass in addition to physical properties such as heat oxidation, heat resistance, radiation resistance, low temperature characteristics and chemical resistance.

Generally, an adhesion promoting agent such as a silane compound is used to improve the adhesion between a polyimide film and glass. In the case where the adhesion promoting agent is applied to glass to improve the adhesion, foreign matter is generated due to application of the adhesion promoting agent, It may not be smoothly formed, and it may be economically disadvantageous to perform the coating step after coating once more.

When the adhesion promoter is directly added to the polyamic acid, the problem caused by the application can be minimized, but the amino group of the silane compound may be precipitated as a carboxylic acid and a salt of the polyamic acid to generate foreign substances on the substrate.

Further, when the molecular structure of the polyimide is changed for the purpose of increasing the adhesion, there is a problem that the thermal stability of the polyimide is lowered.

Accordingly, it is possible to improve the productivity and efficiency of the process by omitting the process steps for adhering the final product, and it is possible to improve the productivity and the process efficiency of the polyimide resin without deteriorating the appearance characteristics of the polyimide resin to be produced, Film development is needed.

The present invention can improve the productivity and efficiency of the process by omitting the steps for adhering the final product, and it is possible to provide a polyimide resin which has excellent mechanical properties and heat resistance without deteriorating the appearance characteristics of the polyimide resin to be produced, And a polyimide film for a flexible substrate of a photoelectric element.

The present invention also provides a display substrate and a solar cell substrate made of the polyimide film for a flexible substrate of the photoelectric element.

The polyimide precursor composition for a flexible substrate of a photoelectric device according to an embodiment of the present invention may be formed from a mixture of a precursor of a polyimide having a structure represented by the following formula 1 and a precursor of a polyimide having a structure represented by the following formula .

[Chemical Formula 1]

In Formula 1,

X ₁ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from an acid dianhydride,

Y ₁ is a divalent organic group containing a divalent organic group derived from a diamine represented by the following formula (2)

(2)

In Formula 2,

R ₁ and R ₂ are each independently a straight chain alkylene group having 1 to 5 carbon atoms,

R ₃ , R ₄ , R ₅ and R ₆ are each independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, n is an integer of 1 to 25,

(3)

In Formula 3,

X ₂ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from an acid anhydride,

Y ₂ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from a diamine.

According to one embodiment, R ₁ and R ₂ in Formula 2 may be a straight-chain alkylene group having 1 to 3 carbon atoms.

According to one embodiment, the polyimide having the repeating structure of the above formula (1) or (3) is a polyimide in which X ₁ and X ₂ are each represented by the following formula (4), or Y ₁ and Y ₂ are May be one containing at least one structure selected from the divalent organic groups represented by the general formula (6).

[Chemical Formula 4]

Each of R ₇ , R ₈ , R ₉ and R ₁₀ is independently selected from a hydrogen atom, a halogen atom or a hydroxyl group,

[Chemical Formula 5]

[Chemical Formula 6]

In the above formulas (5) and (6)

A is a single bond, -O-, -NH-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, -COO -, -, and or -OCO (CH ₂₎ _n3 OCO-, and n _1, n ₂ and n ₃ is an integer from 1 to _{10, - (CH 2) n1 -} , -O (CH 2) n2

R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , and R ₁₆ are each independently selected from hydrogen, fluorine, or a hydroxyl group.

According to one embodiment, the polyimide precursor having the structure of Formula 1 has a viscosity of 100 cP to 400 cP, a molecular weight (Mw) of 20,000 to 100,000 g / mol, and a polyimide having the structure of Formula 2 The precursor may be a polyimide precursor mixture having a viscosity of 6,000 cP to 15,000 cP and a molecular weight (Mw) of 90,000 to 130,000.

According to one embodiment, the proportion of the polyimide precursor including the structure of Formula 1 may be 0.5 to 10% by weight based on the total weight of the polyimide precursor composite.

According to one embodiment, the curing temperature of the polyimide precursor mixture may be 400 to 550 占 폚.

The present invention also provides a polyimide film for a flexible substrate of a photoelectric device obtained by applying the precursor composition onto a glass substrate and then curing.

According to one embodiment, the transmittance of the polyimide film may be at least 45%.

According to one embodiment, the adhesive force of the polyimide film to the glass substrate may be 0.2 N / cm or more after being allowed to stand for 7 days under constant temperature and humidity conditions of 25 ° C and 50%.

According to one embodiment, the coefficient of thermal expansion (CTE) of the polyimide film may be 5 ppm or less at 100 to 500 ° C.

The polyimide film may have a tensile modulus of 7 GPa or more, a tensile strength of 350 MPa or more, and a ductility ratio of 20% or more.

The present invention also provides a method for producing a flexible substrate of a photoelectric device by applying the precursor composition onto a glass substrate and curing the composition.

The present invention also provides a photoelectric device comprising the polyimide film as a flexible substrate.

The present invention also provides a flexible display comprising the polyimide film as a flexible substrate.

The present invention also provides a solar cell comprising a flexible substrate made of the polyimide film.

When the polyimide film for a flexible substrate of a photoelectric device is produced by using the precursor composition according to the present invention, the surface adhesive force is remarkably improved while ensuring excellent mechanical properties and high heat resistance without deteriorating the appearance characteristics, The productivity and the efficiency of the process can be improved. As a result, the polyimide precursor composition according to the present invention can be applied to a flexible display substrate in an electronic device such as an organic light emitting diode (OLED), a liquid crystal display (LCD), an electronic paper, It is useful for manufacturing.

In the present specification, the carbon ring group includes both an alicyclic ring group and an aromatic ring group, and also includes a hetero ring thereof. Means a functional group containing 1 to 3 hetero atoms selected from the group consisting of N, O, S, P and Si.

In the present specification, the "C4 to C20 condensed polycyclic carbon ring group" means a group in which two or more carbon rings are condensed with each other.

In the present specification, the term "C6 to C30 non-condensed polycyclic carbon ring group linked by a linker" means a linkage of two or more carbon rings by a linker. The linker may be a single bond, -O-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, -COO-, (CH ₂₎ _n1 -, and -O (CH ₂₎ and the like _{n2 O-, -OCO (CH 2)} n3 OCO-.

Unless otherwise defined herein, the meaning of "substituted" is a substituent selected from the group consisting of halogen, a C1 to C15 haloalkyl group, a nitro group, a cyano group, a C1 to C15 alkoxy group, and a C1 to C10 lower alkylamino group Substituted "

In the present specification, * in the formula means a bonding position.

Hereinafter, a polyimide precursor composition for a flexible substrate of a photoelectric device according to a specific embodiment of the present invention will be described in more detail.

The polyimide precursor composition for a flexible substrate of a photoelectric device according to the present invention may be formed from a mixture of a precursor of a polyimide having a structure represented by the following formula (1) and a precursor of a polyimide having a structure represented by the following formula (3).

[Chemical Formula 1]

In Formula 1,

and p is an integer of 1 or more representing a repeating unit.

(2)

In Formula 2,

Each of R1 and R2 is independently a straight chain alkylene group having 1 to 5 carbon atoms,

R3, R4, R5 and R6 are each independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms,

n is an integer from 1 to 25,

(3)

In Formula 3,

Y ₂ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from a diamine,

and q is an integer of 1 or more representing a repeating unit.

In the conventional high heat resistant polyimide film, an adhesion promoting agent such as a silane compound is coated on a support such as glass in order to improve adhesion with glass. However, in this method, foreign matter is generated due to the application of the adhesion promoter The substrate may not be formed smoothly, and further processing such as a post-application coating process may be further required, which may reduce the economical efficiency.

In addition, even when the conventional adhesion promoter is added directly to the polyimide resin precursor, the amino group of the adhesion promoter is precipitated with the carboxylic acid of the polyamic acid by the salt.

In order to solve the above problems, the silane-based monomer is directly introduced into the polyimide main chain. However, the mechanical and thermal properties of the polyimide film containing the silane-based monomer may be deteriorated.

In order to solve the above problems, the inventors of the present invention conducted research to produce a polyimide having high adhesion and high heat resistance, and a polyimide precursor composition containing a siloxane and a polyimide precursor composition not containing a siloxane Thereby completing a polyimide film capable of strongly bonding to the glass surface.

Particularly, the polyimide precursor composition according to one embodiment of the present invention can omit the step of adding an adhesive force to the final product, thereby improving the productivity and efficiency of the process, and at the same time, without deteriorating the appearance characteristics of the polyimide resin Excellent mechanical properties and surface adhesion can be improved, and the adhesive force can be controlled by controlling the content of the precursor composition.

The polyimide precursor composition according to one embodiment of the present invention may be prepared by mixing a siloxane-containing polyimide and a polyimide not containing a siloxane in a certain ratio, , The mechanical and thermal properties are lowered, and high heat resistance can be ensured even in a heat treatment process at 500 ° C or more.

Specifically, the precursor composition according to the present invention is a tetravalent organic compound in which X ₁ and X ₂ in the general formulas ( ₁₎ and (3) are represented by the following general formula (4), Y ₁ and Y ₂ are 2 May be one or more structures selected from organic groups.

[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]

In the formulas (5) and (6)

A is a single bond, -O-, -NH-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, -COO -, - (CH ₂ ) n ₁ -, -O (CH ₂ ) n ₂ O-, or -OCO (CH ₂ ) n ₃ OCO-, n ₁ , n ₂ and n ₃ are each an integer of 1 to 10 ego,

R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , and R ₁₆ are each independently selected from a hydrogen atom, a halogen atom, or a hydroxyl group.

In the polyimide structure of the formula (1), the content of the monomer containing the siloxane of the formula (2) may be 5 mol% or more or 30 mol% or less, preferably 5 to 20 mol% in the polyimide structure of the formula (1). If the content of the polyimide precursor is less than 5 mol%, the adhesion of the polyimide film may be deteriorated. If the content of the polyimide precursor is more than 20 mol%, the molecular weight and heat resistance of the polyimide may be deteriorated. The mechanical and thermal properties of the polyimide film can be lowered in the heat treatment step of the polyimide film.

The precursor containing the polyimide structure of formula (1) may further comprise a monomer having a tetravalent organic group of the formula (4) and a divalent organic group selected from the formula (5) or (6), and the content thereof may be 10 mol% or more or 50 mol% , Preferably 25 mol% to 50 mol%, and more preferably 35 mol% to 50 mol%.

In the polyimide structure of formula (3), the content of the monomer having a divalent organic group of formula (5) or (6) and the tetravalent organic group of formula (4) is 5 mol% or more or 50 mol% or less, preferably 20 to 50 mol% And preferably from 40 mol% to 50 mol%. The flexibility of the polyimide and the flowability during the high temperature process can be improved according to the content ratio of the compounds of the formulas (4) to (6), and the heat resistance characteristics of the polyimide molecules can be improved at high temperature.

According to the present invention, in the polyimide having the repeating structure of the above formulas (1) and (3), X ₁ and X ₂ are a substituted or unsubstituted C4 to C20 carbon ring group; A substituted or unsubstituted C4 to C20 condensed polycyclic carbon ring group; And a C6 to C30 non-condensed polycyclic carbon ring group linked by a substituted or unsubstituted linker.

Alternatively, X ₁ and X ₂ may be one quaternary organic group selected from the group consisting of the following formulas (7a) to (7d).

[Formula 7a]

[Formula 7b]

[Formula 7c]

[Formula 7d]

In the above formulas (7a) to (7d)

R ₃₁ to R ₃₅ each independently represent an alkyl group having 1 to 10 carbon atoms (for example, methyl, ethyl, propyl, isopropyl, t-butyl, pentyl or hexyl) A fluoroalkyl group (for example, a fluoromethyl group, a perfluoroethyl group, a trifluoromethyl group, etc.)

A ₁ is an integer of 0 or 2, b ₁ is an integer of 0 to 4, c ₁ is an integer of 0 to 8, d ₁ and e ₁ each independently may be an integer of 0 to 3,

A ₁ is a single bond, -O-, -CR ₄₆ R ₄₇ -, -C (═O) -, -C (═O) NH-, -S-, -SO ₂ - R ₄₆ and R ₄₇ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group , A pentyl group, a hexyl group, etc.) and a fluoroalkyl group having 1 to 10 carbon atoms (for example, a fluoromethyl group, a fluoroethyl group, a trifluoromethyl group, etc.).

Preferably, X ₁ and X ₂ are each independently selected from the group consisting of tetravalent organic groups represented by the following formulas (8a) to (8t).

The aromatic tetravalent organic group of the general formulas (8a) to (8n) is a group in which at least one hydrogen atom present in the tetravalent organic group is an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, , Pentyl group, hexyl group, etc.) or a fluoroalkyl group having 1 to 10 carbon atoms (for example, a fluoromethyl group, a perfluoroethyl group, a trifluoromethyl group, etc.).

More specifically, the tetravalent organic group derived from the acid anhydride is selected from butanetetracarboxylic dianhydride, pentanetetracarboxylic dianhydride, hexanetetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, Bicyclo-pentane tetracarboxylic dianhydride, cyclopropane tetracarboxylic dianhydride, methylcyclohexane tetracarboxylic dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride Rid, 3,4,9,10-perylene tetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, Hydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 1,4,5,8- Tetracarboxylic dianhydride, 2,3,5,6-pyridine tetracarboxylic dianhydride, m-terphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, p-terphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 1,1,1,3,3,3-hexafluoro -2,2-bis [(2,3 or 3,4-dicarboxyphenoxy) phenylpropanedione hydride, 2,2-bis [4- (2,3- or 3,4- dicarboxyphenoxy) Phenyl] propanedialdehyde, 1,1,1,3,3,3-hexafluoro-2,2-bis [4- (2,3- or 4-dicarboxyphenoxy) phenyl] And mixtures thereof.

According to the present invention, in the structure of the polyimide having the repeating structure of the above formulas (1) and (3), Y ₁ and Y ₂ are each a substituted or unsubstituted C1 to C20 alkylene group, a substituted or unsubstituted C5 to C40 arylene group, A substituted or unsubstituted C3 to C40 heteroarylene group, a substituted or unsubstituted C5 to C40 cycloalkylene group, and a substituted or unsubstituted C5 to C40 heterocycloalkylene group can do.

Wherein Y ₂ is to have one or two selected from the group consisting of formula 9a to 9d can be an organic group.

[Formula 9a]

[Formula 9b]

In Formula 9b, L ₁ represents a single bond, -O-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, _{-COO-, - (CH 2) n} 1 -, -O (CH 2) n 2 O-, -OCH 2 -C (CH 3) 2 -CH 2 O- or COO (CH ₂₎ n OCO- and ₃ , N ₁ , n ₂ and n ₃ are integers of 1 to 10, respectively.

[Chemical Formula 9c]

L ₂ and L ₃ may be the same or different and each represents a single bond, -O-, -CO-, -S-, -SO ₂ -, -C (CH ₃ ) ₂ -, -C (CF ₃ ) ₂ -, -CONH-, -COO-, - (CH ₂ ) n ₁ -, -O (CH ₂ ) n ₂ O-, -OCH ₂ -C (CH ₃ ) ₂ -CH ₂ O- Or COO (CH ₂ ) n ₃ OCO-, and n ₁ , n ₂ and n ₃ are integers of 1 to 10, respectively.

[Chemical Formula 9d]

In the formula 9d, L _4, L ₅ and L ₆ may be the same or different from each other, and respectively a single bond, -O-, -CO-, -S-, -SO 2 -, -C (CH 3) 2 - _{, -C (CF 3) 2 -} , -CONH-, -COO-, - (CH 2) n 1 -, -O (CH 2) n 2 O-, -OCH 2 -C (CH 3) 2 -CH ₂ O- or COO (CH ₂ ) n ₃ OCO-, and n ₁ , n ₂ and n ₃ are integers of 1 to 10, respectively.

Specifically, Y ₂ may be selected from the group consisting of divalent organic groups represented by the following formulas (10a) to (10q).

Wherein A ₂ is a single bond, -O-, -C (= O) -, -C (= O) NH-, -S-, -SO ₂ -, phenylene group and combinations thereof , And v is an integer of 0 or 1.

In addition, at least one hydrogen atom in the divalent groups of the general formulas (10a) to (10q) may be an alkyl group having 1 to 10 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, , A fluoroalkyl group having 1 to 10 carbon atoms (e.g., a fluoromethyl group, a perfluoroethyl group or a trifluoromethyl group), an aryl group having 6 to 12 carbon atoms (e.g., a phenyl group or a naphthalenyl group) A sulfonic acid group and a carboxylic acid group.

Specific examples of the diamine having a divalent organic group include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, Bis (4-aminophenoxy) phenyl] propane, 2,2-bis [4- ( 4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 4,4'- (4-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] sulfoxide, bis [4- Bis (4-aminophenoxy) phenyl] ether, 4,4'-bis (4-aminophenylsulfonyl) diphenyl ether, 4,4'- Benzene] benzene, 3,3'-diaminodiphenyl ether, 3,3-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, Diaminodiphenylsulfone, 3,3'-diaminobenzophenone, bis [4- (3-aminophenoxy) phenyl-1, 2-bis [4- (3-aminophenoxy) (3-aminophenoxy) benzene, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- Bis (3-aminothiophenoxy) diphenyl sulfone, 1,4-bis [4 - (3-aminophenoxy) benzoyl] benzene, and mixtures thereof.

The production of the polyamic acid through the polymerization of the acid dianhydride and the diamine can be carried out according to a conventional method for producing a polyamic acid such as solution polymerization. Specifically, it can be produced by dissolving the above-mentioned diamine in an organic solvent, and then adding an acid anhydride to the resultant mixed solution to effect polymerization reaction. The reaction may be carried out under anhydrous conditions, and the temperature during the polymerization may be 25 to 50 ° C, preferably 40 to 45 ° C. Specific examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; Aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; Ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether , Glycol ethers (cellosolve) such as dipropylene glycol diethyl ether and triethylene glycol monoethyl ether; Examples of the solvent include ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, ethanol, propanol, ethylene glycol, propylene glycol, N-dimethylacetamide (DMAc), dimethylformamide (DMF), N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) There can be used at least one compound selected from the group consisting of N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethane, (2-methoxyethoxy)] ether and mixtures thereof May be used be selected from the group. And the like. These solvents may be used alone or as a mixture of two or more thereof.

The organic solvent may be one which is easy to dissolve the tetracarboxylic dianhydride, diamine, adhesion promoter or optionally further additives, and is particularly preferably a solvent which can be easily dried during the coating process. The content of the organic solvent may be 100 to 1000 parts by weight based on 100 parts by weight of the tetracarboxylic dianhydride and diamine solid in the polyimide resin precursor composition. If the content of the organic solvent is too low, the viscosity of the composition may become excessively high and the coating property may be deteriorated. If the content is too high, the composition may not be dried easily, .

As a result of the polymerization reaction, polyamic acid, which is a precursor of polyimide, is produced. The polyamic acid is an acid or an acid derivative containing an -CO-NH- group and a CO-OR group (wherein R is a hydrogen atom or an alkyl group) according to the reaction of an acid anhydride group with an amino group, According to the examples there is provided a polyamic acid having the structure of the following formulas (11) and (12): < EMI ID =

(11)

In Formula 11, X ₁ and Y ₁ are the same as defined above.

[Chemical Formula 12]

Wherein X ₂ and Y ₂ are the same as defined above

The polyamic acid thus obtained as a result of the polymerization reaction is subjected to an imidation process. At this time, the imidization process may be specifically performed by a chemical imidization or thermal imidization process.

Specifically, the chemical imidization may include acid anhydrides such as acetic anhydride, propionic anhydride, benzoic anhydride, or acid chlorides thereof; A carbodiimide compound such as dicyclohexylcarbodiimide, or the like. The dehydrating agent may be used in an amount of 0.1 to 10 mol based on 1 mol of the acid dianhydride.

The chemical imidization may also be carried out at a temperature of 60 to 120 ° C.

In the case of thermal imidization, the thermal imidization may be carried out by heat treatment at a temperature of 80 to 400 ° C. At this time, a step of azeotropically removing water generated as a result of the dehydration reaction using benzene, toluene, May be more preferable.

On the other hand, the chemical or thermal imidization process may be carried out in the presence of a base catalyst such as pyridine, isoquinoline, trimethylamine, triethylamine, N, N-dimethylaminopyridine, imidazole, 1-methylpiperidine, . The base catalyst may be used in an amount of 0.1 to 5 mol based on 1 mol of the acid dianhydride.

By the imidation process, OH of -CO-NH- and OH of -CO-OH in the polyamic acid molecule are dehydrated to obtain a polyimide having the cyclic chemical structure (-CO-N-CO-) .

The polyimide resin precursor composition may further comprise a heat crosslinking agent, a curing accelerator, a phosphorus flame retardant, a defoaming agent, a leveling agent, an antigelling agent or a mixture thereof. Such additives can be used without limitation as long as they are known to be usable in the polyimide resin precursor composition. The additives can be used in appropriate amounts in consideration of the physical properties of the polyimide resin precursor composition or films obtained therefrom.

According to the present invention, there is provided a process for producing a polyimide precursor composition comprising: preparing and mixing a polyimide precursor composition represented by Chemical Formulas 1 and 3; Applying the polyimide precursor composition to one surface of a support and curing the polyimide precursor composition to produce a polyimide film; There is also provided a method of manufacturing a polyimide film for a flexible substrate of a photoelectric device, which comprises separating the polyimide film from a support.

According to the present invention, the acid dianhydride and the diamine may react with each other to form a polyamic acid, and the formed polyamic acid may be imidized to provide a polyimide resin.

According to the present invention, the polyimide precursor having the structure of formula (1) having a divalent organic group derived from a diamine containing the siloxane of formula (2) has a viscosity of 100 cP to 400 cP and a molecular weight (Mw) of 20,000 to 100,000 g / mol, and the precursor of the polyimide having the structure of Formula 3 may have a viscosity of 6,000 cP to 15,000 cP and a molecular weight (Mw) of 90,000 to 130,000.

The viscosity of the mixed precursor composition according to the present invention may be 10,000 to 20,000 cP.

The proportion of the polyimide precursor having the structure of Formula 1, i.e., the polyimide precursor containing siloxane in the molecular structure may be about 0.5 to 10% by weight based on the total weight of the polyimide precursor composite, 0.5 to 8% by weight, more preferably about 0.9 to 5% by weight.

When the proportion of the polyimide precursor containing the siloxane is 0.5% by weight or less, sufficient adhesion may not be obtained. When it is 10% by weight or more, the heat resistance of the polyimide is lowered, The thermal properties and the transmittance of the film may be lowered.

Examples of the support include polyethylene terephthalate, polyethylene naphthalate, polypropylene, polyethylene, cellulose triacetate, cellulose acetate 2, alkyl (meth) acrylates, poly (meth) Various kinds of plastic films such as polyolefins, alcohols, polycarbonates, polystyrenes, cellophanes, polyvinylidene chloride copolymers, polyamides, polyimides, vinyl chloride-vinyl acetate copolymers, polytetrafluoroethylene and polytrifluoroethylene, glass A substrate or a metal substrate. Also, a composite material composed of two or more of these materials may be used, and the thickness of the support is preferably 5 to 150 占 퐉. Among these, the polyimide precursor is excellent in heat and chemical stability during the curing process, A glass substrate which can be easily separated without damaging the polyimide film formed after curing may be preferable.

More specifically, after the application of the polyimide-based solution, a drying process for removing the solvent present in the polyimide-based solution prior to the curing process may be further optionally performed.

The method of applying the polyimide resin precursor composition is not particularly limited and may be, for example, spraying, roll coating, spin coating, slit coating, extrusion coating, curtain coating, die coating, wire bar coating, Knife coating method and the like can be used. The drying of the polyimide resin precursor composition is preferably carried out at 60 to 100 캜 for 30 seconds to 15 minutes although it depends on the kind of each constituent component and the type of organic solvent and the content ratio. Specifically, it may be carried out at a temperature of 140 占 폚 or lower, or 80 to 140 占 폚. If the drying temperature is lower than 80 캜, the drying process becomes longer. If the drying temperature is higher than 140 캜, the imidization rapidly proceeds to make it difficult to form a polyimide film having a uniform thickness.

Also, the curing process may be performed by heat treatment at a temperature of 80 to 500 ° C, or may be performed by a multi-stage heat treatment process at various temperatures within the temperature range. According to one embodiment, the polyimide precursor composite may be cured at a temperature of 400 to 500 占 폚, and preferably 450 to 500 占 폚. The curing process may be carried out by a multi-stage heat treatment at various temperatures within the above-mentioned temperature range. The curing time in the curing step is not particularly limited and can be, for example, 3 to 30 minutes.

The film thickness of the polyimide film after drying and curing is 5 to 95 탆, preferably 10 to 50 탆, more preferably 10 to 20 탆. If the film thickness of the film is 5 mu m or less, the insulating property is not good. If it exceeds 95 mu m, the transparency and resolution may be lowered.

After the curing step, a subsequent heat treatment step may be optionally performed to increase the imidization ratio of the polyimide resin in the polyimide film to form the polyimide film having the above-mentioned physical properties.

The subsequent heat treatment is preferably performed at 200 ° C or higher, or 200 ° C to 500 ° C, preferably 400 ° C to 500 ° C for 1 minute to 30 minutes. The subsequent heat treatment process may be performed once or may be performed in two or more stages. Specifically, it may be carried out in three steps including a first heat treatment at 200 to 220 ° C, a second heat treatment at 300 to 450 ° C, and a third heat treatment at 400 to 550 ° C.

Thereafter, the polyimide-based film formed on the substrate can be produced from the substrate by a conventional method to produce a polyimide-based film.

The step of preparing the display and the solar cell substrate from the polyimide film thus produced may be carried out by peeling off the polyimide film formed on the support according to a conventional method.

According to the present invention, it is possible to adjust the adhesive strength of the polyimide film prepared by controlling the precursor content of the polyimide having the structure of the formula (1) and the polyimide having the structure of the formula (2), and the polyimide including the siloxane Polyimide precursor is polymerized and mixed with a polyamic acid to prepare a polyamic acid composition containing the siloxane. The polyamic acid composition containing the siloxane has a high heat resistance, that is, mechanical and thermal properties of the polyamic acid composition, , A polyimide film having good mechanical and thermal properties can be formed even at a curing temperature of up to 500 캜.

In addition, the polyimide film formed by the above method can have a transmittance of 45% or more and can be usefully used as a substrate of an optoelectronic device that transmits light such as an OLED, an LCD, an electronic paper, and a solar cell.

The polyimide film may have a good adhesion property and at the same time have a good flexibility and can be in a stable form without breaking.

The adhesive strength of the polyimide film formed on the glass substrate from the precursor of the polyimide according to the present invention is not less than 0.1 N / cm, preferably not less than 0.2 N / cm, after being left for 7 days under constant temperature and humidity conditions of 25 DEG C and 50% cm or more, more preferably 0.5 N / cm or more.

Also, the thermal expansion coefficient (CTE) according to an exemplary embodiment may be less than 5 ppm at 100 to 500 ° C.

The modulus of the polyimide film according to the present invention may be 7 GPa or more, the maximum stress may be 350 MPa or more, and the maximum elongation may be a polyimide-based film having excellent mechanical properties of 20% or more.

The polyimide precursor composition having the improved high heat resistance of the present invention can be particularly useful for the production of flexible substrates in electronic devices such as OLEDs, LCDs, electronic paper, and solar cells.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example 1

0.054 mol of p-phenylenediamine (p-PDA) and 0.0232 mol of 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyl-1,3-disiloxane were dissolved in 150 g of NMP, , 4,4'-biphenyltetracarboxylic anhydride (BPDA) and 100 g of a solvent (NMP) were added, and the mixture was stirred at 15 ° C for 2 hours and then at 25 ° C for 10 hours. The reaction was carried out under anhydrous conditions. The resultant polyamic acid was analyzed and found to have a weight average molecular weight of 56,600 g / mol, a PDI (Mw / Mn) of 1.65 and a viscosity of 230 cP. The composition prepared by the above method corresponds to the formula (1).

The precursor corresponding to Formula 3 was prepared by using 0.51 mol of p-PDA and 0.52 mol of BPDA and NMP in the same manner as described above. The resultant polyamic acid was analyzed to have a weight average molecular weight of 96,000 g / mol, a PDI (Mw / Mn) of 1.42, and a viscosity of 8,000 cP.

The precursors of Formulas 1 and 3 prepared above were mixed in a weight ratio of 3: 100 to prepare a final polyimide precursor composition.

Example 2

A final polyimide precursor composition was prepared in the same manner as in Example 1 except that the precursors of Formulas 1 and 3 prepared in Example 1 were mixed in a weight ratio of 1: 100.

Comparative Example 1

A polyimide precursor composition was prepared in the same manner as in Example 1, except that the precursor of formula (1) was not used.

Manufacturing example

The prepared polyimide precursor solution was spin-coated on the glass substrate to a thickness of 20 탆. The glass substrate coated with the polyimide precursor solution was heated in the oven at a rate of 2 ° C / min and cured at 80, 120, 180, 250, 350, 400 and 500 ° C for 30 minutes to 1 hour Respectively.

Test Example 1

The maximum elongation, modulus, maximum stress and coefficient of thermal expansion were measured for each of the polyimide films prepared according to the preparation examples.

The thermal expansion coefficient (CTE) of the film was also measured using Q400 of sms TA.

Prepare the film in 5x20mm size and load the sample using accessories. The actual measured film length was equal to 16 mm. The pulling force of the film was set to 0.02 N, and the linear thermal expansion coefficient was measured by heating the measurement starting temperature to 30 ° C at a rate of 5 / min to 500 ° C.

Zwick's UTM was used to measure the mechanical properties (modulus, maximum stress, maximum elongation) of the film. The film was cut to a width of 5 mm or more and a length of 60 mm or more. The gap between the grips was set to 40 mm, and the sample was pulled at a speed of 20 mm / min.

Test Example 2. Measurement of Adhesion

The adhesion of the films prepared in Examples and Comparative Examples was measured by the KS M ISO B510 method.

The results of the tests performed as described above are summarized in Table 1 below.

Example 1 Example 2 Comparative Example 1 Final curing temperature (캜) 500 500 500 Composition ratio Formula 1 3 One 0 (3) 100 100 100 Viscosity (cP) 13,000 13,300 13,500 Thickness (μm) 20 20 20 CTE (ppm / ° C) 2.9 2.6 2.5 Tensile stress (GPa) 7.5 7.56 7.6 Maximum tensile strength (MPa) 415 422 430 Maximum elongation (%) 24.5 24.5 25 Adhesion (N / cm) 0.9 0.8 0.1

As shown in Table 1, the adhesive strength of the polyimide film prepared from the polyimide composition according to the present invention shows a remarkably increased value as compared with Comparative Example 1, and the physical properties and thermal properties are maintained to be excellent.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims

A polyimide precursor composition for a flexible substrate of a photoelectric device comprising a precursor of a polyimide having a structure represented by the following formula (1) and a precursor mixture of a polyimide having a structure represented by the following formula (3)
[Chemical Formula 1]

In Formula 1,
X ₁ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from an acid dianhydride,
Y ₁ is a divalent organic group comprising a divalent organic group derived from a diamine represented by the following formula (2)
p is an integer of 1 or more representing a repeating unit,
(2)

In Formula 2,
R ₁ and R ₂ are each independently a straight chain alkylene group having 1 to 5 carbon atoms,
R ₃ , R ₄ , R ₅ and R ₆ are each independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms,
n is an integer from 1 to 25,
(3)

In Formula 3,
X ₂ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from an acid anhydride,
Y ₂ is a divalent organic group containing an aromatic, alicyclic or aliphatic group derived from a diamine,
and q is an integer of 1 or more representing a repeating unit.

The method according to claim 1,
Wherein R ₁ and R ₂ in Formula 2 are each independently a straight-chain alkylene group having 1 to 3 carbon atoms, in the polyimide precursor composition for a flexible substrate of a photoelectric device.

The method according to claim 1,
The polyimide having a repeating structure represented by the above formula (1) or (3) is a tetravalent organic compound in which X ₁ and X ₂ are each represented by the following formula (4), Y ₁ and Y ₂ are each a 2- Wherein the polyimide precursor composition for a flexible substrate of a photoelectric device comprises at least one structure selected from the group consisting of:
[Chemical Formula 4]

Each of R ₇ , R ₈ , R ₉ and R ₁₀ is independently selected from a hydrogen atom, a halogen atom or a hydroxyl group,
[Chemical Formula 5]

[Chemical Formula 6]

In the formulas (5) and (6)
A single bond, -O-, -NH-, -CO-, -S- , -SO2-, -C (CH 3) 2 -, -C (CF 3) 2 -, -CONH-, -COO-, - (CH ₂ ) n ₁ -, -O (CH ₂ ) n ₂ O- or -OCO (CH ₂ ) n ₃ OCO-, n ₁ , n ₂ and n ₃ are each an integer of 1 to 10,
R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , R ₁₅ , and R ₁₆ are each independently selected from hydrogen, fluorine, or a hydroxyl group.

The method according to claim 1,
The polyimide precursor having the structure of Formula 1 has a viscosity of 100 cP to 400 cP and a molecular weight (Mw) of 20,000 to 100,000. The polyimide precursor having the structure of Formula 3 has a viscosity of 6,000 cP to 15,000 cP And has a molecular weight (Mw) of 90,000 to 130,000. The polyimide precursor composition for a flexible substrate of a photoelectric device.

The method according to claim 1,
Wherein the proportion of the polyimide precursor having the structure of Formula 1 is 0.5 to 10% by weight based on the total weight of the polyimide precursor composite.

The method according to claim 1,
Wherein the polyimide precursor mixture has a curing temperature of 400 to 550 占 폚.

A polyimide film for a flexible substrate of a photoelectric device obtained by applying the composition of any one of claims 1 to 6 onto a glass substrate and curing the composition.

8. The method of claim 7,
Wherein the polyimide film has a transmittance of 45% or more.

8. The method of claim 7,
Wherein the polyimide film has an adhesive force of 0.2 N / cm or more to the glass substrate.

8. The method of claim 7,
Wherein the polyimide film has a coefficient of thermal expansion (CTE) of 5 ppm or less at 100 to 500 占 폚.

8. The method of claim 7,
Wherein the film has a tensile modulus of 7 GPa or more, a tensile strength of 350 MPa or more, and an elongation of 20% or more.

A method for producing a flexible substrate of a photoelectric device by applying the composition of any one of claims 1 to 6 on a glass substrate and curing the composition.

A photoelectric device comprising the polyimide film according to claim 8 as a flexible substrate.

A flexible display comprising a flexible substrate made of a polyimide film according to claim 8.

A solar cell comprising a flexible substrate made of a polyimide film according to claim 8.