KR102247318B1 - Diamine compound, polyimide precursor and polyimide film prepared by using same - Google Patents

Abstract

The polyimide film prepared using the novel diamine according to the present invention not only can improve optical properties such as YI and light transmittance, but also has little change in residual stress due to moisture absorption, and thus cracks in the inorganic film that may occur therefrom. It can reduce the occurrence and can be usefully used in manufacturing a flexible device.

Description

A diamine compound, a polyimide precursor, and a polyimide film using the same TECHNICAL FIELD {DIAMINE COMPOUND, POLYIMIDE PRECURSOR AND POLYIMIDE FILM PREPARED BY USING SAME}

The present invention relates to a novel diamine, a polyimide precursor using the same, and a polyimide film with improved physical properties.

In recent years, light weight and miniaturization of products are becoming important in the display field, and the glass substrates currently used are heavy, brittle, and have limitations in that continuous processing is difficult, so a plastic substrate that has the advantage of being light, flexible, and capable of continuous processing as a substitute for glass substrates. Research is being actively conducted to apply the technology to mobile phones, notebook computers, and PDAs.

In particular, polyimide (PI) resins are easy to synthesize, can make thin films, and have the advantage of not needing a crosslinker for curing, so they are integrated into semiconductor materials such as LCD and PDP due to the recent light weight and precision phenomenon of electronic products. It is widely applied, and many studies are being conducted to use PI for a flexible plastic display board having a light and flexible property.

A polyimide (PI) film is produced by forming a film of the polyimide resin, and in general, the polyimide resin is a solution polymerization of an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative solution. It is manufactured by coating a silicon wafer or glass and curing it by heat treatment.

Flexible devices involving a high-temperature process require heat resistance at high temperatures. In particular, in the case of an OLED (organic light emitting diode) device using a low temperature polysilicon (LTPS) process, the process temperature may approach 500°C. However, at this temperature, even polyimide having excellent heat resistance is likely to undergo thermal decomposition by hydrolysis. Therefore, in order to manufacture a flexible device, it is necessary to develop a polyimide film capable of exhibiting excellent chemical resistance and storage stability in which thermal decomposition by hydrolysis does not occur even at a high temperature process.

The problem to be solved by the present invention is to provide a novel diamine capable of producing a polyimide with improved physical properties.

Another problem to be solved by the present invention is to provide a polyimide precursor for manufacturing a polyimide film with improved physical properties.

Another problem to be solved by the present invention is to provide a polyimide film using the polyimide precursor.

In addition, another object of the present invention is to provide a flexible device including the polyimide film and a manufacturing process thereof.

In addition, another problem to be solved by the present invention is to provide a method for preparing the novel diamine.

In order to solve the problem of the present invention,

It provides a diamine having the structure of the following formula (1).

[Formula 1]

In Formula 1,

R ₁ to R ₄ are each independently a C 1 to C 3 alkyl group, a C 1 to C 3 haloalkyl group or a halogen atom,

n1 to n4 are each independently an integer of 0 to 4, but not 0 at the same time.

According to an embodiment, each of R ₁ to R ₄ may independently be a fluoroalkyl group having 1 to 3 carbon atoms.

According to an embodiment, at least one of n1 and n4 may be 1, or at least one of n2 and n3 may be 1.

According to an embodiment, at least one of n1 and n4 may be 1, and at least one of n2 and n3 may be 1.

According to an embodiment, all of n1 to n4 may be 1.

According to an embodiment, the diamine of Formula 1 may be selected from compounds of Formulas 1-1 to 1-16 below.

In order to solve other problems of the present invention,

As a polyimide precursor obtained by polymerizing a polymerization component containing at least one diamine and at least one acid dianhydride,

The diamine provides a polyimide precursor containing the diamine of Formula 1.

According to an embodiment, the weight average molecular weight of the polyimide precursor may be 45,000 g/mol or more.

In order to solve another problem of the present invention,

It provides a polyimide film prepared using the polyimide precursor.

According to an embodiment, the polyimide film,

Applying a polyimide precursor composition including a polyimide precursor onto a carrier substrate; And

It may be prepared by a method including heating and curing the polyimide precursor composition.

According to an embodiment, the residual stress immediately after curing of the polyimide precursor composition may be 40 MPa or less.

According to an embodiment, after the polyimide film is left at 25° C. and 50% humidity for 3 hours, a change value of the residual stress may be 5 MPa or less.

The yellowness of the polyimide film may be 15 or less.

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

The present invention also includes the steps of applying the polyimide precursor composition on a carrier substrate;

Heating the polyimide precursor composition to imidize polyamic acid to form a polyimide film;

Forming a device on the polyimide film; And

It provides a manufacturing process of a flexible device comprising the step of peeling the polyimide film on which the device is formed from the carrier substrate.

According to an embodiment, the manufacturing process may include an LTPS (low temperature polysilicon) process, an ITO process, or an oxide process.

In order to solve other problems of the present invention,

Reacting the compound of formula (i) with the compound of formula (ii) to obtain a compound of formula (iii);

Oxidizing the compound of formula iii to obtain a compound of formula iv; And

It provides a method for preparing a diamine comprising the step of obtaining a compound of Formula 1 by reducing the compound of Formula iv:

[Scheme 1]

In the above formula,

R ₁ to R ₄ are each independently a C 1 to C 3 alkyl group, a C 1 to C 3 haloalkyl group or a halogen atom,

n1 to n4 are each independently an integer of 0 to 4, but not 0 at the same time.

According to an embodiment, the starting materials of the compounds of Formula (i) and Formula (ii) may be prepared through a suzuki coupling reaction as shown in Schemes 2 and 3, respectively.

[Scheme 2]

[Scheme 3]

In the above formula,

R ₁ to R ₄ are each independently a C 1 to C 3 alkyl group, a C 1 to C 3 haloalkyl group or a halogen atom,

n1 to n4 are each independently an integer of 0 to 4, but not 0 at the same time.

In the present invention, by preparing a polyimide film using a polyimide precursor prepared using a diamine having the structure of Formula 1, optical properties such as YI and light transmittance can be improved, as well as moisture absorption of the polyimide film. Due to the small change in residual stress, it is possible to reduce the occurrence of cracks in the inorganic film that may occur therefrom, and thus can be usefully used in manufacturing a flexible device.

Since the present invention can apply various transformations and have various embodiments, specific embodiments are illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

In the present specification, all compounds or organic groups may be substituted or unsubstituted unless otherwise specified. Here,'substituted' means that at least one hydrogen contained in the compound or organic group is a halogen atom, an alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group, a cycloalkyl group having 3 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, and a hydroxy group. , It means substituted with a substituent selected from the group consisting of an alkoxy group having 1 to 10 carbon atoms, a carboxylic acid group, an aldehyde group, an epoxy group, a cyano group, a nitro group, an amino group, a sulfonic acid group, and derivatives thereof.

Aromatic polyimide is widely used in high-tech industries such as microelectronics, aerospace, insulating materials and refractory materials due to its excellent comprehensive properties such as thermal oxidation stability, high mechanical strength, and good mechanical strength. However, aromatic polyimide with strong absorbance in the ultraviolet-visible region exhibits a strong coloration from pale yellow to dark brown, which limits its wide application in the optoelectronics area, where transparency and colorless properties are basic requirements. The reason why coloration appears in the aromatic polyimide resin is that it forms charge transfer complexes (CT-complexes) between alternating electron donors (dianhydride) and electron acceptors (diamine) and between internal molecules in the polymer backbone.

To solve this problem, for the development of an optically transparent PI film having a high glass transition temperature (Tg), a functional group is introduced, a bulky attachment pendant group, a fluorinated functional group, etc. are introduced into the polymer main chain. , Methods of introducing flexible units (-S-, -O-, -CH ₂ -, etc.) have been studied.

In particular, in _{the case of aromatic polyimide containing DDS (4,4'-Diaminodiphenylsulfone) with sulfone (-SO 2} -) introduced, sulfone bonds with high electronegativity prevent the formation of internal or inter-molecular CT-complexes. As a result, it not only has the properties of low phase difference, low YI, and high transmittance, but also exhibits thermally stable properties.

However, the sulfonyl group of DDS (4,4'-Diaminodiphenylsulfone) may form intramolecular and intermolecular conjugation, thereby reducing the reactivity during polymerization of the polyimide precursor, and thus, may not reach the molecular weight for obtaining target properties. .

In order to solve such a conventional problem, the present invention provides a diamine represented by the following formula (1).

[Formula 1]

In Formula 1,

R ₁ to R ₄ are each independently a C 1 to C 3 alkyl group, a C 1 to C 3 haloalkyl group or a halogen atom,

n1 to n4 are each independently an integer of 0 to 4, but not 0 at the same time.

The present invention provides a polyimide precursor containing the diamine of Formula 1 as a polymerization component, so that a transparent polyimide film can be prepared without requiring a special combination of solvents. In addition, it is possible to provide a polyimide film having a low residual stress generated between the inorganic film, excellent chemical resistance, and a small effect on the increase of the YI value and the decrease in light transmittance due to the oxygen concentration during the curing process. .

The substituent of Formula 1 may have a more amorphous characteristic by reducing the intermolecular packing density of the polyimide, thereby improving optical characteristics (eg, YI value and transmittance). In addition, preferably, by having a fluoroalkyl group as a substituent, the water absorption property of the polyimide film can be improved.

In the case of polyimide containing DDS ((diaminodiphenyl) sulfone), residual stress changes according to the standing time after the TFT process are severe, and inorganic film cracks may occur due to such residual stress changes. On the other hand, since the diamine of Formula 1 contains a fluoroalkyl group as a substituent, moisture absorption according to the standing time may be significantly reduced, and the resulting change in residual stress may also be reduced.

According to an embodiment, the polyimide film containing the diamine of Formula 1 may have a residual stress of 40 MPa or less immediately after curing, and the change value of the residual stress after the polyimide film is left at 25° C. 50% humidity for 3 hours. It may be 5 MPa or less.

The diamine of Formula 1 is as shown in Reaction Formula 1 below,

Reacting the compound of formula (i) with the compound of formula (ii) to obtain a compound of formula (iii);

Oxidizing the compound of formula iii to obtain a compound of formula iv; And

It can be synthesized by a method comprising the step of obtaining a compound of Formula 1 by reducing the compound of Formula iv.

[Scheme 1]

In the above formula,

R ₁ to R ₄ and n1 to n4 are the same as in Formula 1.

Specifically, the reaction is

Dissolving the compounds of formula (i) and formula (ii) in dimethyl sulfoxide (DMSO) and then adding potassium carbonate (K ₂ CO ₃ ) and stirring at a temperature of 80°C to 100°C;

Adding water after stirring and washing the solid obtained by filtration with water and ethanol to obtain the compound of formula (iii);

Oxidizing the compound of Formula iii by dispersing the compound of Formula iii in glacial acetic acid (AcOH), _{adding potassium permanganate (KMnO 4} ) at 0° C., stirring, raising the temperature to room temperature, and stirring;

Adding water after completion of the oxidation reaction and recrystallizing the obtained solid with ethanol to obtain a compound of formula (iv);

Dispersing the compound of Formula iv in ethanol in a nitrogen atmosphere, adding tin chloride (SnCl ₂ ), heating and stirring to reduce the compound of Formula iv; And

After completion of the reduction reaction, the solid obtained by adding water is filtered and recrystallized with ethanol to obtain a compound of Formula 1.

In addition, the starting materials of Reaction Scheme 1, the compounds of Formula I and Formula ii, may be prepared through a suzuki cupling reaction as shown in Schemes 2 and 3, respectively.

[Scheme 2]

[Scheme 3]

According to an embodiment, at least one of n1 and n4 may be 1, or at least one of n2 and n3 may be 1.

According to an embodiment, at least one of n1 and n4 may be 1, and at least one of n2 and n3 may be 1.

According to an embodiment, all of n1 to n4 may be 1.

According to an embodiment, the diamine of Formula 1 may be a compound of Formulas 1-1 to 1-16 below.

In Formula 1, a substituent containing fluorine (F), for example, a substituent such as a fluoroalkyl group, can reduce packing within the polyimide structure or between chains, and due to steric hindrance and electrical effects, It is possible to exhibit high transparency in the visible light region by weakening the electrical interaction between the liver.

The present invention,

As a polyimide precursor obtained by polymerizing a polymerization component containing at least one diamine and at least one acid dianhydride,

It provides a polyimide precursor containing the diamine represented by the following formula (1) among the polymerized components.

According to an embodiment, the weight average molecular weight of the polyimide precursor prepared using the diamine may be 45,000 g/mol or more, and preferably 50,000 g/mol or more. If the molecular weight is less than 45,000 g/mol, the viscosity of the solution may decrease due to the decrease in polyimide reactivity, and the viscosity of the solution is low compared to the solid content, so it may not be easy to control the film thickness during the solution coating process and the final curing process. In addition, when the molecular weight is low, mechanical properties may be deteriorated, resulting in a problem that the film strength decreases .

The polyimide precursor according to the present invention may contain a diamine or an acid dianhydride having a structure represented by the following formula (2) as a polymerization component:

[Formula 2]

In Formula 2,

R ₅ and R ₆ are each independently a monovalent organic group having 1 to 20 carbon atoms, and h is an integer of 3 to 200.

More specifically, the compound of Formula 2 may be a diamine compound of Formula 2-1.

[Formula 2-1]

In Formula 2-1,

R is a C1-C10 alkyl group or a C6-C24 aryl group,

p and q are mole fractions, when p+q=100, p is 70 to 90, and q is 10 to 30.

The compound of Formula 2 may be included in an amount of 5 to 50% by weight based on the total weight of the polymerization component, and preferably may be included in an amount of 10 to 20% by weight based on the total weight of the polymerization component.

If the polymerization component including the structure of Formula 2 is added excessively with respect to the total weight, mechanical properties such as modulus of the polyimide may be deteriorated, and the film strength may be reduced, such that the film is torn in the process. Physical damage may occur. In addition, when the diamine having the structure of Formula 2 is excessively added, Tg derived from the polymer having the siloxane structure may appear, and from this, Tg appears at a low process temperature of 350°C or less. During the inorganic film deposition process, wrinkles may occur on the film surface due to the flow phenomenon of the polymer, and the inorganic film may be cracked.

In general, in the case of a polyimide containing 10% by weight or more of a diamine or an acid dianhydride containing a silicone oligomer structure such as Formula 2 in the polymerization component, the effect of reducing residual stress may be increased, and in a composition higher than 50% by weight, Since Tg is lower than 390°C, heat resistance may be deteriorated.

On the other hand, the polyimide according to the present invention can maintain Tg at 390°C or higher even though it contains a silicone oligomer in an amount of 10% by weight or more based on the total polymerization component. Therefore, while maintaining the glass transition temperature above 390°C, the effect of reducing the residual stress due to the silicon oligomer structure can also be obtained.

The molecular weight of the silicone oligomer structure contained in the diamine or acid dianhydride having the structure of Formula 2 may be 4000 g/mol or more, wherein the molecular weight refers to the weight average molecular weight, and the molecular weight calculation is performed using NMR analysis or acid base titration method. A method of calculating the equivalent of the reactor such as amine or dianhydride can be used.

When the molecular weight of the silicone oligomer structure including the structure of Formula 2 is less than 4000 g/mol, heat resistance may be reduced, for example, the glass transition temperature (Tg) of the prepared polyimide is decreased, or the coefficient of thermal expansion It can increase excessively.

According to the present invention, since the size of the silicon oligomer domains distributed in the polyimide matrix is nano-sized, for example, 1 nm to 50 nm, or 5 nm to 40 nm, or 10 nm to 30 nm, it has a continuous phase, while maintaining heat resistance and mechanical properties. Residual stress can be minimized. In the case of not having such a continuous phase, there may be a residual stress reduction effect, but heat resistance and mechanical properties are remarkably reduced, making it difficult to use in the process.

Here, the domain of the silicone oligomer refers to a region in which a polymer having a silicon oligomer structure is distributed, and the size refers to the diameter of a circle surrounding the region.

It is preferable that the portion (domain) containing the silicon oligomer structure is connected in a continuous phase in the polyimide matrix, wherein the continuous phase means a shape in which nano-sized domains are uniformly distributed.

Therefore, although the present invention is a silicone oligomer having a high molecular weight, it can be uniformly distributed without phase separation in the polyimide matrix, so that the haze property is lowered to obtain a polyimide having more transparent properties, as well as a silicone oligomer structure. Since is present in a continuous phase, the mechanical strength and stress relaxation effect of the polyimide can be more efficiently improved. From these properties, the composition according to the present invention can provide a flat polyimide film by reducing not only thermal properties and optical properties, but also a phenomenon in which the substrate is warped after coating-curing.

In the present invention, by inserting the silicone oligomer structure into the polyimide structure, it is possible to appropriately improve the modulus strength of the polyimide and also relieve stress caused by an external force. At this time, the polyimide containing the silicon oligomer structure may exhibit polarity, and phase separation may occur due to the difference in polarity from the polyimide structure not including the siloxane structure, and due to this, the siloxane structure is distributed unevenly throughout the polyimide structure. Can be. In this case, not only it is difficult to exhibit the effect of improving the strength of the polyimide due to the siloxane structure and the effect of relieving stress, but also the haze may increase due to phase separation, thereby reducing the transparency of the film. In particular, when a diamine containing a siloxane structure has a high molecular weight, the polarity of the polyimide prepared therefrom is more pronounced, and a phase separation phenomenon between the polyimides may be more pronounced. At this time, in the case of using siloxane diamine having a low molecular weight structure, a large amount must be added in order to exhibit an effect such as stress relief, which may cause process problems such as Tg generation at a low temperature. Due to this, the physical properties of the polyimide film may be deteriorated. Accordingly, when a high molecular weight siloxane diamine is added, the relaxation segment can be formed large in the molecule, and thus, the stress relaxation effect can be effectively exhibited even with a small amount compared to the addition of a low molecular weight. Accordingly, in the present invention, by using the compound of Formula 2 having a siloxane structure having a high molecular weight, it can be more evenly distributed on a polyimide matrix without phase separation.

According to an embodiment, the acid dianhydride used to polymerize the polyimide precursor may be a tetracarboxylic dianhydride. For example, as the tetracarboxylic dianhydride, intramolecular aromatic, alicyclic, Alternatively, as an aliphatic tetravalent organic group or a combination thereof, a tetracarboxylic dianhydride containing a tetravalent organic group in which aliphatic, alicyclic or aromatic tetravalent organic groups are connected to each other through a crosslinked structure may be used. Preferably, it may include an acid dianhydride having a monocyclic or polycyclic aromatic, monocyclic or polycyclic alicyclic, or a structure in which two or more of them are linked by a single bond or a functional group. Or, tetracarboxylic acid containing a tetravalent organic group having a rigid structure such as a single or fused heterocyclic ring structure, or a structure linked by a single bond. May contain dianhydrides.

For example, the tetracarboxylic dianhydride may include a tetravalent organic group having a structure represented by the following Formulas 3a to 3e:

[Formula 3a]

[Formula 3b]

[Formula 3c]

[Chemical Formula 3d]

[Formula 3e]

In Formulas 3a to 3e, R ₁₁ to R ₁₇ are each independently a halogen atom selected from -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), and a nitro A group (-NO ₂ ), a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms,

A1 is an integer of 0 to 2, a2 is an integer of 0 to 4, a3 is an integer of 0 to 8, a4 and a5 are each independently an integer of 0 to 3, a6 and a9 are each independently an integer of 0 to 3 , And a7 and a8 may each independently be an integer of 0 to 7,

The A ₁₁ and A ₁₂ are each independently a single bond, -O-, -CR'R"- (herein, R'and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, a methyl group , Ethyl group, propyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, etc.) and a haloalkyl group having 1 to 10 carbon atoms (eg, trifluoromethyl group, etc.) ), -C(=O)-, -C(=O)O-, -C(=O)NH-, -S-, -SO-, -SO ₂ -, -O[CH ₂ CH ₂ O] y- (y is an integer of 1 to 44), -NH(C=O)NH-, -NH(C=O)O-, a monocyclic or polycyclic cycloalkylene group having 6 to 18 carbon atoms (e.g. , Cyclohexylene group, etc.), a monocyclic or polycyclic arylene group having 6 to 18 carbon atoms (e.g., a phenylene group, a naphthalene group, a fluorenylene group, etc.), and a combination thereof. There is,

Alternatively, the tetracarboxylic dianhydride may include a tetravalent organic group selected from the group consisting of the following Chemical Formulas 4a to 4n.

At least one hydrogen atom in the tetravalent organic group of Formulas 4a to 4n is a halogen atom selected from -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group ( -NO ₂ ), a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms. For example, the halogen atom may be fluoro (-F), and the halogenoalkyl group is a fluoroalkyl group having 1 to 10 carbon atoms including a fluoro atom, and a fluoromethyl group, perfluoroethyl group, trifluoro The alkyl group may be selected from methyl group, ethyl group, propyl group, isopropyl group, t-butyl group, pentyl group, hexyl group, and the aryl group may be selected from phenyl group and naphthalenyl group. It may be, and more preferably, it may be a substituent including a fluoro atom such as a fluoro atom and a fluoroalkyl group.

Alternatively, the tetracarboxylic dianhydride has an aromatic ring or an aliphatic structure in which each ring structure is rigid, that is, a single ring structure, a structure in which each ring is bonded by a single bond, or each ring is It may include a tetravalent organic group including a directly linked heterocyclic structure.

According to an embodiment, at the time of polymerization of the polyimide precursor, one or more diamines may be further included in addition to the diamine of Formula 1, for example, a monocyclic or polycyclic aromatic divalent organic group having 6 to 24 carbon atoms, and 6 to carbon atoms. 18 monocyclic or polycyclic alicyclic divalent organic groups, or diamines containing a divalent organic group structure selected from a divalent organic group including a structure in which two or more of them are linked with a single bond or a functional group, and , Or, one selected from a divalent organic group having a rigid structure such as a single or fused heterocyclic ring structure, or a structure linked by a single bond in which a ring structure compound such as aromatic or alicyclic is selected. I can.

For example, the diamine may include a divalent organic group selected from Formulas 5a to 5e below.

[Formula 5a]

[Formula 5b]

[Formula 5c]

[Formula 5d]

[Formula 5e]

In Formulas 5a to 5e,

R ₂₁ to R ₂₇ are each independently a halogen atom selected from -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group (-NO ₂ ), and a cyanide group. It may be selected from the group consisting of a no group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy having 1 to 4 carbon atoms, a halogenoalkyl having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

In addition, A ₂₁ and A ₂₂ are each independently a single bond, -O-, -CR'R"- (herein, R'and R" are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, Selected from the group consisting of a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a tert-butyl group, a pentyl group, etc.) and a haloalkyl group having 1 to 10 carbon atoms (e.g., trifluoromethyl group, etc.) ), -C(=O)-, -C(=O)O-, -C(=O)NH-, -S-, -SO-, -SO ₂ -, -O[CH ₂ CH ₂ O ]y-(y is an integer of 1 to 44), -NH(C=O)NH-, -NH(C=O)O-, a monocyclic or polycyclic cycloalkylene group having 6 to 18 carbon atoms (e.g. For example, a cyclohexylene group), a monocyclic or polycyclic arylene group having 6 to 18 carbon atoms (e.g., a phenylene group, a naphthalene group, a fluorenylene group, etc.), and a combination thereof. Can,

b1 is an integer of 0 to 4, b2 is an integer of 0 to 6, b3 is an integer of 0 to 3, b4 and b5 are each independently an integer of 0 to 4, b7 and b8 are each independently 0 to It is an integer of 9, and b6 and b9 are each independently an integer of 0-3.

For example, the diamine may be one containing a divalent organic group selected from the following Chemical Formulas 6a to 6p.

Alternatively, the diamine may include a divalent organic group in which an aromatic ring or an aliphatic structure forms a rigid chain structure, for example, a single ring structure, a structure in which each ring is bonded by a single bond, or Each ring may include a divalent organic group structure including a heterocyclic ring structure in which each ring is directly fused.

According to an embodiment of the present invention, the total content of tetracarboxylic dianhydride and the content of diamine may be reacted in a molar ratio of 1:1.1 to 1.1:1, and preferably, in order to improve reactivity and processability, It is preferable that the total content of the tetracarboxylic dianhydride is reacted in an excessive amount compared to the diamine, or the content of the diamine is reacted in an excess of the total content of the tetracarboxylic dianhydride.

According to an embodiment of the present invention, the molar ratio of the total content of the tetracarboxylic dianhydride and the content of diamine may be 1:0.99 to 0.99:1, preferably 1:0.98 to 0.98:1. .

The polymerization reaction of the acid dianhydride and the diamine compound may be carried out according to a conventional polymerization method of polyimide or a precursor thereof, such as solution polymerization.

As organic solvents that can be used in the polyamic acid polymerization reaction, gamma-butyrolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4- Ketones such as methyl-2-pentanone; 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; 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, carbitol, dimethyl Propionamide (DMPA), diethylpropionamide (DEPA), dimethylacetamide (DMAc), N,N-diethylacetamide, dimethylformamide (DMF), diethylformamide (DEF), N -Methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N,N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, N- Methylcaprolactam, tetrahydrofuran, m-dioxane, P-dioxane, 1,2-dimethoxyethane, bis(2-methoxyethyl)ether, 1,2-bis(2-methoxyethoxy)ethane , Bis[2-(2-methoxyethoxy)]ether, Equamide M100, Equamide B100, and the like, and one of them alone or a mixture of two or more may be used.

According to an embodiment, as an organic solvent for polymerizing the polymerization component, a solvent having a partition coefficient LogP of 25° C. may be used. By using an organic solvent in which LogP is a positive number, even in a composition containing 10% by weight or more of methylphenylsilicone oligomer, Tg can be maintained at a high temperature of 390°C or more.

In addition, the organic solvent having a positive partition coefficient as described above can reduce the clouding phenomenon caused by phase separation due to the polarity difference between a flexible polyimide repeating structure and a polyimide structure including a siloxane structure such as a silicone oligomer. have. Conventionally, two types of organic solvents have been used to solve the phase separation, but it is possible to reduce the clouding phenomenon by only using the organic solvent as described above, and thus a more transparent polyimide film can be prepared.

In order to solve the above problem, there is a method of using a mixture of a polar solvent and a non-polar solvent, but polar solvents tend to have high volatility, and therefore, problems such as volatilization in advance during the manufacturing process may occur. Not only may a problem such as a decrease in reproducibility of the polyimide film, but also a phase separation problem may not be completely improved, and thus haze of the manufactured polyimide film may increase, resulting in a decrease in transparency.

More specifically, by using a solvent containing a structure in which the molecule of the solvent has an amphiphilic structure, not only can the problem of the process caused by the use of a polar solvent be solved, but also one type of Even if only a solvent is used, the polyimide can be evenly distributed, which is very suitable for solving the problem due to phase separation, and thus, a polyimide having remarkably improved haze properties can be provided.

When the partition coefficient value is positive, it means that the polarity of the solvent is hydrophobic.According to the research of the present inventors, it can be seen that when a polyimide precursor composition is prepared using a specific solvent having a positive partition coefficient value, the edge back phenomenon is improved. there was. In addition, in the present invention, by using a solvent having a positive log P as above, it is possible to control the edge back phenomenon of the solution without using an additive that adjusts the surface tension of the material such as a leveling agent and the smoothness of the coating film. This does not use additional additives such as additives, so it is not only possible to eliminate quality and process problems such as containing low molecular weight substances in the final product, but also to more efficiently form a polyimide film having uniform properties. There is.

For example, in a process of coating a polyimide precursor composition on a glass substrate, edge back phenomenon may occur due to shrinkage of the coating layer during curing or under a condition of leaving the coating liquid under a humidity condition. The edge-back phenomenon of the coating solution can lead to variations in the thickness of the film, resulting in a phenomenon in which the film is broken due to the lack of bending resistance of the film or the edges are broken during cutting, resulting in poor workability in the process and a decrease in yield. Problems can arise.

In addition, when a fine foreign material having polarity is introduced into the polyimide precursor composition applied on the substrate, in the polyimide precursor composition containing a polar solvent having a negative log P, the position of the foreign material is based on the polarity of the foreign material. However, when a hydrophobic solvent with a positive log P is used, the occurrence of thickness change due to cracking of the coating is reduced or suppressed even when fine foreign substances with polarity are introduced. Can be.

Specifically, the polyimide precursor composition including a solvent in which Log P is a positive number may have an edge back ratio of 0% to 0.1% or less, defined by Equation 1 below.

[Equation 1]

Edge white rate (%) = [(A-B)/A]×100

In Equation 1 above,

A: The area in the state where the polyimide precursor composition is completely coated on the substrate (100mmΥ100mm),

B: The area after the edge-back phenomenon occurs from the edge of the substrate coated with the polyimide precursor composition or PI film.

Such an edge back phenomenon of the polyimide precursor composition and film may occur within 30 minutes after coating the polyimide precursor composition solution, and in particular, the thickness of the edge may be made thick by starting to roll from the edge.

After coating the polyimide precursor composition according to the present invention on a substrate, the edge white rate of the coated resin composition solution after being left in a humidity condition for 10 minutes or more, such as 10 minutes or more, such as 40 minutes or more, is 0.1 % Or less, for example, at a temperature of 20 to 30°C, a humidity condition of 40% or more, more specifically a humidity condition in the range of 40% to 80%, that is, 40%, 50%, 60%, 70% , In each humidity condition of 80%, for example, even after leaving for 10 to 50 minutes in a humidity condition of 50%, a very small edge white rate of 0.1% or less may be exhibited, preferably 0.05%, more preferably almost It can represent an edge percentage close to 0%.

The edge white rate as described above is maintained even after curing, for example, 10 minutes or more after coating the polyimide precursor composition on the substrate, for example, at a temperature of 20 to 30° C., under a humidity condition of 40% or more, more specifically Is allowed to stand for 10 to 50 minutes in a humidity condition of 40% to 80%, i.e., 40%, 50%, 60%, 70%, 80% of each humidity condition, for example, 50% humidity condition, and then cured. The edge-back ratio of the resulting polyimide film may be 0.1% or less, that is, the edge-back phenomenon may hardly occur or may not occur even in the curing process by heat treatment, specifically, the edge close to 0.05%, more preferably close to 0%. It can represent percentage.

The polyimide precursor composition according to the present invention can obtain a polyimide film having more uniform properties by solving such an edge back phenomenon, thereby further improving the yield of the manufacturing process.

In addition, the density of the solvent according to the present invention is ASTM as determined using the standard measurement method D1475, 1g / cm ³ can be less than a density of 1 g / If having a cm ³ or more values, it may increase the relative viscosity of the process the Efficiency can be reduced.

The solvent in which LogP is a positive number is, for example, N,N-diethylacetamide (N,Ndiethylacetamide, DEAc), N,N-diethylformamide (N,N-diethylformamide, DEF), N-ethylpyrroly It may be at least one selected from don (N-ethylpyrrolidone, NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA).

The organic solvent may have a boiling point of 300° C. or less, and more specifically, a partition coefficient LogP value may be 0.01 to 3, or 0.01 to 2, or 0.1 to 2.

The distribution coefficient can be calculated using the ACD/LogP module of the ACD/Percepta platform of ACD/Labs, and the ACD/LogP module uses an algorithm based on the quantitative structure-property relationship (QSPR) methodology using the 2D structure of the molecule. Use.

Further, aromatic hydrocarbons such as xylene and toluene may be further used, and in order to promote dissolution of the polymer, an alkali metal salt or alkaline earth metal salt of about 50% by weight or less based on the total amount of the solvent may be further added to the solvent.

In addition, in the case of synthesizing polyamic acid or polyimide, in order to inactivate excess polyamino group or acid anhydride group, a terminal sealant for sealing the end of the polyimide is further added by reacting the molecular end with dicarboxylic acid anhydride or monoamine. can do.

The method of reacting the tetracarboxylic dianhydride with diamine may be carried out according to a conventional polyimide precursor polymerization method such as solution polymerization. Specifically, it can be prepared by dissolving diamine in an organic solvent and then adding tetracarboxylic dianhydride to the resulting mixed solution for polymerization.

The polymerization reaction can be carried out under an inert gas or nitrogen stream, and can be carried out under anhydrous conditions.

In addition, the reaction temperature during the polymerization reaction may be carried out at -20 to 80 ℃, preferably 0 to 80 ℃. If the reaction temperature is too high, the reactivity may increase and the molecular weight may increase, and the viscosity of the precursor composition may increase, which may be disadvantageous in the process.

It is preferable to include a solid content in the polyamic acid solution prepared according to the above-described manufacturing method in an amount such that the composition has an appropriate viscosity in consideration of fairness such as coatability during the film formation process.

The polyimide precursor composition containing the polyamic acid may be in the form of a solution dissolved in an organic solvent, and in the case of having such a form, for example, when the polyimide precursor is synthesized in an organic solvent, the solution is the obtained reaction solution. It may be itself, or may be one obtained by diluting this reaction solution with another solvent. In addition, when the polyimide precursor is obtained as a solid powder, it may be dissolved in an organic solvent to obtain a solution.

According to an embodiment, the content of the composition may be adjusted by adding an organic solvent so that the content of the total polyimide precursor is 8 to 25% by weight, preferably 10 to 25% by weight, more preferably 10 to 20% by weight. It can be adjusted below %.

Alternatively, the polyimide precursor composition may be adjusted to have a viscosity of 3,000 cP or more, or 4,000 cP or more, and the viscosity of the polyimide precursor composition is 10,000 cP or less, preferably 9,000 cP or less, more preferably 8,000 cP It is preferable to adjust to have the following viscosity. When the viscosity of the polyimide precursor composition exceeds 10,000 cP, the efficiency of defoaming during the processing of the polyimide film decreases, so that not only the efficiency of the process, but also the surface roughness of the produced film is poor due to the generation of bubbles, so that the electrical, optical, and mechanical properties are poor. It can be degraded.

Subsequently, a transparent polyimide film can be prepared by imidizing the polyimide precursor obtained as a result of the polymerization reaction using a chemical or thermal imidization method.

According to an embodiment, applying a polyimide precursor composition on a carrier substrate; And

A polyimide film may be prepared by a method including heating and curing the polyimide precursor composition.

At this time, as the carrier substrate, glass, metal substrate, plastic substrate, etc. may be used without particular limitation, and among them, it has excellent thermal and chemical stability during the imidization and curing process for the polyimide precursor, and without a separate release agent treatment, A glass substrate that can be easily separated without damage to the polyimide-based film formed after curing may be desirable.

In addition, the coating process may be performed according to a conventional coating method, and specifically, a spin coating method, a bar coating method, a roll coating method, an air-knife method, a gravure method, a reverse roll method, a kiss roll method, a doctor blade method, Spray method, dipping method, brushing method, etc. may be used. Among these, a continuous process may be possible, and it may be more preferable to perform a casting method capable of increasing the imidation rate of the polyimide.

In addition, the polyimide precursor composition may be applied on the substrate in a thickness range such that the polyimide film finally produced has a thickness suitable for a display substrate.

Specifically, it may be applied in an amount such that it has a thickness of 10 to 30 μm. After the polyimide precursor composition is applied, a drying process for removing the solvent present in the polyimide precursor composition may be optionally further performed prior to the curing process.

The drying process may be performed according to a conventional method, and specifically, may be performed at a temperature of 140°C or less, or 80°C to 140°C. When the drying process is performed at a temperature of less than 80°C, the drying process is prolonged, and when it exceeds 140°C, imidization proceeds rapidly, making it difficult to form a polyimide film having a uniform thickness.

Subsequently, the polyimide precursor composition applied to the substrate is heat-treated on an IR oven, a hot air oven, or a hot plate, wherein the heat treatment temperature may be in the range of 300 to 500°C, preferably 320 to 480°C, and the temperature It can also be carried out in multi-stage heat treatment within the range. The heat treatment process may be performed for 20 to 70 minutes, and preferably may be performed for a time of about 20 to 60 minutes.

The residual stress immediately after curing of the polyimide film prepared as described above may be 40 MPa or less, and the residual stress change value after leaving the polyimide film at 25° C. 50% humidity for 3 hours may be 5 MPa or less. .

The yellowness of the polyimide film may be 15 or less, and preferably 13 or less. In addition, the haze of the polyimide film may be 2 or less, and preferably 1 or less.

In addition, the transmittance at 450 nm of the polyimide film may be 75% or more, the transmittance at 550 nm may be 85% or more, and the transmittance at 630 nm may be 90% or more.

The polyimide film may have high heat resistance, and for example, a thermal decomposition temperature (Td_1%) at which a mass decrease of 1% occurs may be 500°C or higher.

The polyimide film prepared as described above may have a modulus of 3 to 4 GPa. If the modulus (modulus of elasticity) is less than 0.1 GPa, the film has low rigidity and is easily fragile by external impact. If the modulus of elasticity exceeds 4 GPa, the coverlay film has excellent rigidity but cannot secure sufficient flexibility. I can.

In addition, the polyimide film may have an elongation of 20% or more, preferably 50% or more, and a tensile strength of 130 MPa or more, preferably 140 MPa or more.

In addition, the polyimide film according to the present invention may have excellent thermal stability according to temperature change, for example, the coefficient of thermal expansion after n+1 heating and cooling processes in a temperature range of 100°C to 350°C is -10 It may have a value of to 100 ppm/°C, preferably a value of -7 to 90 ppm/°C, more preferably 80 ppm/°C or less (where n is an integer greater than or equal to 0).

In addition, the polyimide film according to the present invention _{may exhibit optical isotropy by having a retardation in the thickness direction (R th} ) of -150 nm to +150 nm, preferably -130 nm to +130 nm, thereby improving visibility. .

According to an embodiment, the polyimide film may have an adhesive strength of 5 gf/in or more with a carrier substrate, and preferably 10 gf/in or more.

In addition, the present invention,

Applying the polyimide precursor composition onto a carrier substrate;

Heating the polyimide precursor composition to imidize polyamic acid to form a polyimide film;

Forming a device on the polyimide film; And

It provides a manufacturing process of a flexible device comprising the step of peeling the polyimide film on which the device is formed from the carrier substrate.

In particular, the manufacturing process of the flexible device may include a low temperature polysilicon (LTPS) process, an ITO process, or an oxide process.

For example, forming a blocking layer containing _{SiO 2} on the polyimide film;

Depositing an a-Si (Amorphous Silicon) thin film on the blocking layer;

A dehydrogenation annealing step of heat-treating the deposited a-Si thin film at a temperature of 450±50°C; And

After the LTPS thin film manufacturing process including the step of crystallizing the a-Si thin film with an excimer laser or the like, the carrier substrate and the polyimide film are peeled off by laser peeling or the like, thereby obtaining a flexible device including the LTPS layer.

The oxide thin film process can be heat treated at a lower temperature than the process using silicon. For example, the heat treatment temperature of the ITO TFT process may be 240℃±50℃, and the heat treatment temperature of the oxide TFT process is 350℃±50℃. Can be

Hereinafter, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

<Preparation Example 1> Preparation of Chemical Formula 1-1

After dissolving the compounds of formula A (20.0g, 92.2mmol) and formula B (27.6g, 92.2mmol) in DMSO (200mL), potassium carbonate (19.0g. 138.3mmol) was added and stirred at 90°C. After 12 hours, water (200 mL) was added and the solid obtained by filtration was washed with water and ethanol to prepare a compound of Formula C (39.6 g, yield 91.8%).

MS[M+H]+=497

After dispersing the compound of formula C (30g, 60.5mmol) in glacial acetic acid (300mL), potassium permanganate (28.6g, 181.5mmol) was added at 0°C, stirred for 1 hour, and then heated to room temperature and stirred for 7 hours. After completion of the reaction, water (300 ml) was added, and the obtained solid was recrystallized with ethanol to prepare a compound of formula D (27.4 g, yield 85.8%).

MS[M+H] ⁺ =529

After dispersing the compound of Formula D (25g, 47.4mmol) in ethanol (250mL) in a nitrogen atmosphere, tin chloride (35.9g, 189.6mmol) was added, heated, and stirred at 50°C for 8 hours. After completion of the reaction, water (250 ml) was added to obtain a solid. The solid obtained after filtration was recrystallized with ethanol to prepare a compound of Formula 1-1 (19.9g, yield 89.9%).

MS[M+H] ⁺ =469

<Preparation Example 2> Preparation of Chemical Formula 1-2

A compound of Formula G was prepared in the same manner as the method of preparing a compound of Formula C, except that the compound of Formula E instead of Formula A and the compound of Formula F instead of Formula B was used.

Next, the compound of Formula H was prepared in the same manner as the method of preparing the compound of Formula D, except that the compound of Formula H was used instead of the compound of Formula C.

Finally, the compound of Formula 1-2 was prepared in the same manner as the method of preparing the compound of Formula 1-1, except that the compound of Formula H was used instead of Formula D.

MS[M+H] ⁺ =469

<Preparation Example 3> Preparation of Chemical Formula 1-4

A compound of formula (K) was prepared in the same manner as the method of preparing a compound of formula (C), except that the compound of formula (I) instead of formula (A) and the compound of formula (J) were used instead of formula (B).

Next, a compound of Formula L was prepared in the same manner as the method of preparing a compound of Formula D, except that the compound of Formula K was used instead of Formula C.

Finally, the compound of Formula 1-4 was prepared in the same manner as the method of preparing the compound of Formula 1-1, except that the compound of Formula L was used instead of Formula D.

MS[M+H] ⁺ =537

<Preparation Example 4> Preparation of Chemical Formula 1-7

A compound of Formula N was prepared in the same manner as the method of preparing a compound of Formula C, except that the compound of Formula M was used instead of Formula A.

Next, a compound of Formula O was prepared in the same manner as the method of preparing Formula D, except that the compound of Formula N was used instead of Formula C.

Finally, the compound of Formula 1-7 was prepared in the same manner as the method of preparing the compound of Formula 1-1, except that the compound of Formula O was used instead of Formula D.

MS[M+H]+=537

<Preparation Example 5> Preparation of Chemical Formula 1-9

A compound of Formula Q was prepared in the same manner as the method of preparing a compound of Formula C, except that the compound of Formula M instead of Formula A and the compound of Formula P instead of Formula B was used.

Next, a compound of Formula R was prepared in the same manner as the method of preparing Formula D, except that the compound of Formula Q was used instead of Formula C.

Finally, the compound of Formula 1-9 was prepared in the same manner as the method of preparing the compound of Formula 1-1, except that the compound of Formula R was used instead of Formula D.

MS[M+H] ⁺ =537

<Preparation Example 6> Preparation of Chemical Formula 1-10

A compound of Formula S was prepared in the same manner as the method of preparing a compound of Formula C, except that the compound of Formula M instead of Formula A and the compound of Formula J instead of Formula B was used.

Next, a compound of Formula T was prepared in the same manner as the method of preparing a compound of Formula D, except that the compound of Formula S was used instead of Formula C.

Finally, the compound of Formula 1-10 was prepared in the same manner as the method of preparing the compound of Formula 1-1, except that the compound of Formula T was used instead of Formula D.

MS[M+H] ⁺ =537

<Preparation Example 7> Preparation of Chemical Formula 1-12

A compound of Formula V was prepared in the same manner as the method of preparing the compound of Formula C, except that the compound of Formula U was used instead of Formula A.

Next, a compound of Formula W was prepared in the same manner as the method of preparing Formula D, except that the compound of Formula V was used instead of Formula C.

Finally, the compound of Formula 1-12 was prepared in the same manner as the method of preparing the compound of Formula 1-1, except that the compound of Formula W was used instead of Formula D.

MS[M+H] ⁺ =605

<Comparative Example 1> PMDA/DDS

After filling 50 g of DEAc (Diethylacteamide) into the reactor where nitrogen stream flows, 0.0458 mol of 4,4'-DDS (4,4'-diaminodiphenyl sulfone) was added and dissolved at the same temperature while maintaining the temperature of the reactor at 25°C. Made it. To the solution to which DDS was added, 0.0458 mol of pyromellitic dianhydride (PMDA) was added together with 50 g of DEAc and reacted for 48 hours to prepare a polyimide precursor solution.

<Comparative Example 2> BPDA/DDS

After filling 40 g of DEAc into a reactor through which a nitrogen stream flows, 0.03395 mol of 4,4'-DDS was added and dissolved at the same temperature while maintaining the temperature of the reactor at 25°C. To the solution to which DDS was added, 0.03395 mol of BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) was added together with 46 g of DEAc and reacted for 48 hours to prepare a polyimide precursor solution .

<Example 1> PMDA/Formula 1-1 Diamine

After filling 100 g of DEAc in a reactor through which a nitrogen stream flows, 0.04585 mol of diamine of Formula 1-1 prepared in Preparation Example 1 was added and dissolved at the same temperature while maintaining the temperature of the reactor at 25°C. To the solution to which the diamine of Formula 1-1 was added, 0.04585 mol of PMDA (pyromellitic dianhydride) was added together with 62 g of DEAc and reacted for 48 hours to prepare a polyimide precursor solution.

<Example 2> BPDA/ Formula 1-1 Diamine

After filling 80 g of DEAc into a reactor through which a nitrogen stream flows, 0.03395 mol of diamine of Formula 1-1 prepared in Preparation Example 1 was added and dissolved at the same temperature while maintaining the temperature of the reactor at 25°C. To the solution to which the diamine of Formula 1-1 was added, 0.03395 mol of BPDA (3,3',4,4'-biphenyltetracarboxylic dianhydride) was added together with 52 g of DEAc and reacted for 48 hours to prepare a polyimide precursor solution.

<Experimental Example 1>

Each of the polyimide precursor solutions prepared in Examples 1 and 2 and Comparative Examples 1 and 2 was spin-coated on a glass substrate. The glass substrate coated with the polyimide precursor solution was placed in an oven and heated at a rate of 5°C/min, and the curing process was carried out by holding at 80°C for 30 minutes, 250°C for 30 minutes, and 410°C for 30 to 40 minutes. A polyimide film was prepared. The physical properties of each film were measured and shown in Table 1 below.

<Yellowness (YI)>

Yellowness (YI) was measured with Color Eye 7000A.

<Haze>

Haze was measured by the method according to ASTM D1003 using a Haze Meter HM-150.

<Transmittance>

The transmittance was measured for the wavelengths of 450nm, 550nm and 630nm with a transmittance meter (model name HR-100, manufactured by Murakami Color Research Laboratory) according to JIS K 7105.

<Thickness direction phase difference (Rth)>

The retardation in the thickness direction (Rth) was measured using Axoscan. The film was cut to a certain size and the thickness was measured, and then the retardation was measured with Axoscan. In order to compensate for the retardation value, the measured thickness was input while correcting it in the C-plate direction.

<Pyrolysis temperature (Td1%)>

Using TGA, the temperature was measured when the weight reduction ratio of the polymer was 1% in a nitrogen atmosphere.

<Modulus (GPa), tensile strength (MPa), elongation (%)>

A film having a length of 5 mm X 50 mm and a thickness of 10 μm was stretched at a speed of 10 mm/min in a tensile tester (manufactured by Instron Co., Ltd.: Instron 3342) to measure modulus (GPa), tensile strength (MPa), and elongation (%).

<Residual stress measurement>

Using a residual stress measuring device measuring device (FLX2320 from Tencor Inc.), the resin composition is coated on a 4in silicon wafer with a thickness of 525um, which has been measured in advance by measuring the [warpage amount] of the wafer (manufactured by Koyo Lindbergh), and an oven is installed. Using, heat curing treatment at 250° C. 30 min and 400° C. 60 min under a nitrogen atmosphere was performed, and after curing, a silicone wafer with a resin film having a thickness of 10 μm was prepared. The amount of warpage of this wafer was measured using the above-described residual stress measuring device by the above method, and residual stress generated between the silicon wafer and the resin film was measured.

Thereafter, the same polyimide film was left at 25° C. and 50% humidity for 3 hours, and then the residual stress was measured.

sample Comparative Example 1
PMDA_DDS Comparative Example 2
BPDA_DDS Example 1
PMDA_Chemical Formula 1-1 Example 2
BPDA_Chemical Formula 1-1 Sol. Con. (wt%) 22.6 21.5 18.9 18.9 Viscosity (cps) 3424 3020 3320 3320 Curing condition(5℃/min)
80℃ 30min → 250℃ 30min 400℃ 30min 400℃ 40min 400℃ 40min 400℃ 40min Thickness(㎛) 9.8 9.53 9.4 9.68 YI 18.2 4.3 12.8 3.2 Haze 0.1 0.27 0.4 0.2 Rth (nm) 550 nm 200 100 125 35 Transmittance
(%) 450 nm 71.4 83.2 77.5 85.4 550 nm 84.3 89.9 88.7 90.1 630 nm 86.1 90.3 93.3 90.7 Td1% (℃) 495 527 505 537 Modulus (Gpa) 2.3 2.9 2.6 3.2 Tensile strength (Mpa) 125 132 110 130 Strain (%) 90 50 65 45 Residual stress(Mpa) right after hardening 40 42 36 39 Residual stress (Mpa) 3h after curing
@25℃ 50% 32 32 32 35

From the results of Table 1, it can be seen that in the case of the polyimide film according to the present invention, the change in residual stress due to moisture is very low. In addition, compared to the use of DDS diamine under the same acid dianhydride composition, it can be seen that optical properties such as _{YI, retardation in the thickness direction (R th ), and transmittance are also improved.}

As described above, specific parts of the present invention have been described in detail, and for those of ordinary skill in the art, it is obvious that this specific technique is only a preferred embodiment, and the scope of the present invention is not limited thereby. something to do. Therefore, it will be said that the practical scope of the present invention is defined by the appended claims and their equivalents.

Claims (18)

delete delete delete delete delete Diamines selected from compounds of the following formulas 1-1 to 1-3, 1-6, 1-8 to 1-13, and 1-15:

. As a polyimide precursor obtained by polymerizing a polymerization component containing at least one diamine and at least one acid dianhydride,
The polyimide precursor that the diamine comprises the diamine of claim 6. The method of claim 7,
A polyimide precursor having a weight average molecular weight of 45,000 g/mol or more. A polyimide film prepared using the polyimide precursor according to claim 7. Applying a polyimide precursor composition comprising the polyimide precursor of claim 7 on a carrier substrate; And
A polyimide film prepared by a method comprising heating and curing the polyimide precursor composition. The method of claim 10,
A polyimide film having a residual stress of 40 MPa or less of the polyimide film obtained immediately after curing of the polyimide precursor composition. The method of claim 9,
A polyimide film having a residual stress change value of 5 MPa or less after leaving the polyimide film at 25° C. and 50% humidity for 3 hours. The method of claim 9,
A polyimide film having a yellowness of 15 or less of the polyimide film. A flexible device comprising the polyimide film according to claim 9 as a substrate. Applying a polyimide precursor composition comprising the polyimide precursor of claim 7 on a carrier substrate;
Heating and curing the polyimide precursor composition to form a polyimide film;
Forming a device on the polyimide film; And
A manufacturing process of a flexible device comprising the step of peeling the polyimide film on which the device is formed from the carrier substrate. The method of claim 15,
The manufacturing process of a flexible device, wherein the step of forming the device includes an LTPS (low temperature polysilicon) process, an ITO process, or an oxide process. delete delete