Polyimide precursor

Abstract

The present application provides a polyimide precursor capable of realizing an environmentally friendly polyimide having high adhesion, surface flatness, and durability, a method for producing the polyimide precursor, and a polyimide film including a cured product of the polyimide precursor.

Description

Technical Field

[0001] This application relates to a polyimide precursor, a method for producing the polyimide precursor, and a polyimide film containing a cured product of the polyimide precursor.

Background Art

[0002] Generally, polyimide (PI) is a polymer of imide monomers formed by solution polymerization of dianhydride and diamine or diisocyanate, and has excellent mechanical properties such as strength, chemical resistance, weather resistance, and heat resistance based on the chemical stability of the imide ring. Furthermore, polyimide has excellent electrical properties such as insulation properties and low dielectric constant, and has attracted attention as a high-functional polymer material applicable to a wide range of industrial fields such as electronics, communication, and optics.

[0003] Here, polyimide refers to a high heat-resistant resin produced by solution polymerization of a dianhydride monomer and a diamine monomer to produce a polyamic acid, and then subjecting it to ring-closing dehydration at a high temperature to imidize it.

Summary of the Invention

Problems to be Solved by the Invention

[0004] This application provides a polyimide precursor, a method for producing the polyimide precursor, and a polyimide film containing a cured product of the polyimide precursor, which are environmentally friendly, have high adhesive strength, surface flatness, and durability, and can embody polyimide with a high imidization rate.

Means for Solving the Problems

[0005] This application relates to a polyimide precursor. For example, the polyimide precursor may be a polyimide varnish that is imidized by thermosetting after being applied to a coating target. By including the composition described below, the polyimide precursor can provide a polyimide that is environmentally friendly and has high adhesive strength, surface flatness, and durability.

[0006] An exemplary polyimide precursor according to this application comprises a polyamic acid containing dianhydride monomers and diamine monomers as polymerization units; an organic solvent containing at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA); a first silicon-containing additive containing at least one functional group; and at least one second additive selected from a phosphorus-based additive having an aromatic ring group, or an amine-based additive having an aromatic or heteroaromatic ring group.

[0007] Furthermore, the weight-average molecular weight of the polyamic acid may be within the range of 40,000 to 100,000 g / mol, 45,000 to 90,000 g / mol, 48,000 to 80,000 g / mol, 50,000 to 75,000 g / mol, or 51,000 to 70,000 g / mol. In this application, the term "weight-average molecular weight" refers to the converted value relative to standard polystyrene measured by GPC (Gel permeation Chromatography).

[0008] The polyimide precursor according to the present invention may be a polyamic acid solution comprising polyamic acid, an organic solvent, a silicon-containing first additive, and at least one second additive selected from a phosphorus-based additive having an aromatic ring group or an amine-based additive having an aromatic or heteroaromatic ring group. In the present invention, polyimide precursor, polyamic acid solution, and polyimide varnish are interpreted as having the same meaning.

[0009] The polyamic acid may be produced by a polymerization reaction of a dianhydride monomer and a diamine monomer in the presence of the aforementioned organic solvent, and the polymer may be mixed with a silicon-containing additive. By polymerizing the polyamic acid of the present invention under the aforementioned organic solvent, the weight-average molecular weight increases and can satisfy the aforementioned numerical range.

[0010] In the present invention, the silicon-containing first additive may be a silane compound or a siloxane compound. Furthermore, the silicon-containing first additive does not need to be included in the polymerization units of the polyamic acid after the polymerization reaction is complete, as it is mixed with the polyamic acid. Instead, it can interact with the polyamic acid and polyimide via functional groups to contribute to the realization of a polyimide with high adhesive strength, surface flatness, and excellent durability. In addition, at least one second additive selected from phosphorus-based additives or amine-based additives can contribute to increasing the imidization rate and durability of the polyamic acid during curing by being mixed with the polyamic acid after the polymerization reaction is complete.

[0011] When mixed with polyamic acid polymerized in the presence of the aforementioned organic solvent, a polyimide with high adhesive strength, excellent surface flatness, and durability during curing can be provided.

[0012] In one specific example, the organic solvent may have a negative (-) value for the octanol / water partition coefficient (Log P) calculated by the following equation 1.

[0013] [Mathematics 1] Log P = Log(Kow) Kow=Co / Cw

[0014] In the above equation 1, Co is the concentration of the solute in octanol, and Cw is the concentration of the solute in water.

[0015] The aforementioned partition coefficient may also be calculated at a temperature of 25°C using the ACD / LogP module of ACD / Labs' ACD / Perceptaplatform, in which case the ACD / LogP module can utilize a QSPR (Quantitative Structure-Property Relationship) methodology-based algorithm using the 2D structure of the molecule. However, since the aforementioned partition coefficient is an experimental value, the possibility of it being measured as a positive (+) value cannot be ruled out depending on the measurement method and algorithm used.

[0016] Organic solvents having a negative partition coefficient include N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), or N,N-dimethylpropionamide (DMPA). Considering environmental friendliness, DMPA is preferred.

[0017] From an environmental perspective, the organic solvent may be N,N-dimethylpropionamide (DMPA). DMPA is an environmentally friendly organic solvent, can be processed without a separate purification process after the polymerization reaction, and reduces costs. Furthermore, the weight-average molecular weight of the polyamic acid may be adjusted within the aforementioned numerical range during the polymerization reaction under the DMPA solvent. On the other hand, polyamic acid polymerized under the DMPA solvent may exhibit a low imidation rate during curing. However, the polyimide precursor according to the present invention, when containing a phosphorus-based or amine-based additive, has the effect of improving this low imidation rate.

[0018] On the other hand, the organic solvent does not necessarily have to contain N-methyl-2-pyrrolidone (NMP). Polyamic acids polymerized in the presence of N-methyl-2-pyrrolidone may not meet the weight-average molecular weight within the aforementioned range. Furthermore, NMP is classified as a hazardous substance, requiring additional costs for purification and potentially causing environmental pollution during processing.

[0019] In one specific example, the content of the silicon-containing first additive may be 0.0001 to 1% by weight based on the total polyimide precursor. For example, the content of the silicon-containing first additive may be 0.0001 to 0.9% by weight, 0.0001 to 0.8% by weight, 0.0001 to 0.7% by weight, 0.0001 to 0.6% by weight, 0.00001 to 0.5% by weight, 0.0001 to 0.4% by weight, 0.0001 to 0.3% by weight, 0.0001 to 0.2% by weight, 0.0001 to 0.1% by weight, 0.0001 to 0.09% by weight, or 0.0001 to 0.08% by weight based on the total polyimide precursor. Amount%, 0.0001~0.07wt%, 0.0001~0.06wt%, 0.0001~0.05wt%, 0.0001~0.04wt%, 0.0001~0.03wt%, 0.0001~0.02wt%, 0.0 001~0.01wt%, 0.001~0.9wt%, 0.001~0.8wt%, 0.001~0.7wt%, 0.001~0.6wt%, 0.001~0.5wt%, 0.001~0.4wt%, 0.001~ 0.3% by weight, 0.001~0.2% by weight, 0.001~0.1% by weight, 0.001~0.09% by weight, 0.001~0.08% by weight, 0.001~0.07% by weight, 0.001~0.06% by weight, 0.001~0 .05% by weight, 0.001~0.04% by weight, 0.001~0.03% by weight, 0.001~0.02% by weight, 0.001~0.01% by weight, 0.01~0.9% by weight, 0.01~0.8% by weight, 0.01~0.7% by weight The silicon content may be within the range of % by weight, 0.01-0.6% by weight, 0.01-0.5% by weight, 0.01-0.4% by weight, 0.01-0.3% by weight, 0.01-0.2% by weight, 0.01-0.1% by weight, 0.01-0.09% by weight, 0.01-0.08% by weight, 0.01-0.07% by weight, 0.01-0.06% by weight, 0.01-0.05% by weight, 0.01-0.04% by weight, 0.01-0.03% by weight, or 0.01-0.02% by weight. A silicon-containing first additive having a content within the above range can be mixed with polymerized polyamic acid to provide a polyimide with high adhesive strength, surface flatness, and excellent durability upon curing.

[0020] The functional group of the silicon-containing first additive may be an amine group, a carboxyl group, an alcohol, an alkoxy group, a mercapto, an epoxy group, or an isocyanate. The silicon-containing additive is a monomer or polymer containing at least one of the functional groups, and may be, for example, the compound shown in Chemical Formula 1 below.

[0021] [C1] R1 R2 R3Si-R-R4

[0022] In the above formula 1, At least one of R1 to R3 is an alkoxy group, and the rest are organic groups. R is a single bond or a divalent organic group. R4 is an organic group having at least one functional group selected from an amine group, a carboxyl group, an alcohol, an alkoxy group, a mercapto, an epoxy group, or an isocyanate.

[0023] When the functional group is an amine group, examples include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethylsilane, γ-aminopropylmethyldiethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-(N-phenylamino)propyltrimethoxysilane, γ-(N-phenylamino)propylmethyldimethoxysilane, γ-(N-methylamino)propyltrimethoxysilane, γ-(N-methylamino)propylmethyldimethoxysilane, γ-(N-ethylamino)propyltrimethoxysilane, γ-(N-ethylamino)propylmethyldimethoxysilane, or N-[3-(trimethoxysilyl)propyl]aniline.

[0024] When the functional group is mercapto, examples include γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, or γ-mercaptopropylmethyldimethoxysilane.

[0025] When the functional group is an epoxy group, examples include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-(2,3-epoxycyclohexyl)propyltrimethoxysilane, or γ-glycidoxypropyltrimethoxysilane.

[0026] Examples of the silicon-containing first additive that is a polymer while the functional group is an epoxy group include X-12-984S (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0027] Examples of the silicon-containing additive that is a monomer while the functional group is an isocyanate group include 3-isocyanatopropyltriethoxysilane.

[0028] In still other examples, the polyimide precursor may contain at least one second additive selected from a phosphorus-based additive having an aromatic ring group or an amine-based additive having an aromatic or heteroaromatic ring group.

[0029] The second additive may contribute to increasing the imidization rate and durability of the polyimide precursor.

[0030] In one specific example, the content of the second additive may be 0.001 to 2% by weight based on the total polyimide precursor. For example, the content of the second additive may be 0.001 to 1.9% by weight, 0.001 to 1.8% by weight, 0.001 to 1.7% by weight, 0.001 to 1.6% by weight, 0.001 to 1.5% by weight, 0.001 to 1.4% by weight, 0.001 to 1.3% by weight, 0.001 to 1.2% by weight, or 0.001 to 1% by weight based on the total polyimide precursor. 1% by weight, 0.001~1% by weight, 0.001~0.9% by weight, 0.001~0.8% by weight, 0.001~0.7% by weight, 0.001~0.6% by weight, 0.00 1~0.5wt%, 0.01~1.9wt%, 0.01~1.8wt%, 0.01~1.7wt%, 0.01~1.6wt%, 0.01~1.5wt%, 0.01 ~1.4wt%, 0.01~1.3wt%, 0.01~1.2wt%, 0.01~1.1wt%, 0.01~1wt%, 0.01~0.9wt%, 0.01~0 .8% by weight, 0.01~0.7% by weight, 0.01~0.6% by weight, 0.01~0.5% by weight, 0.1~1.9% by weight, 0.1~1.8% by weight, 0.1~1.7% by weight The content may be within the range of % by weight, 0.1-1.6% by weight, 0.1-1.5% by weight, 0.1-1.4% by weight, 0.1-1.3% by weight, 0.1-1.2% by weight, 0.1-1.1% by weight, 0.1-1% by weight, 0.1-0.9% by weight, 0.1-0.8% by weight, 0.1-0.7% by weight, 0.1-0.6% by weight, or 0.1-0.5% by weight. A second additive having a content within the above range can be mixed with polyamic acid polymerized together with a silicon-containing additive to not only achieve a high imidization rate during curing, but also contribute to improving durability.

[0031] In one example, the phosphorus-based additive may have aromatic ring groups. For example, the phosphorus-based additive may have one or more, two or more, or three or more aromatic ring groups, preferably three aromatic ring groups, and more preferably the phosphorus-based additive may be triphenyl phosphate or triphenylphosphine.

[0032] In one example, the amine additive may have a benzene ring group or a heteroaromatic ring group containing a nitrogen element. For example, the amine additive may be isoquinoline, β-picoline, 1,2-dimethylimidazole, benzimidazole, triphenylamine, or 2-phenylimidazole, and preferably triphenylamine.

[0033] In one specific example, the dianhydride monomer may be an aromatic tetracarboxylic dianhydride. For example, the dianhydride monomer contains at least one compound represented by the following chemical formula 2.

[0034] [ka]

[0035] In the above formula 2, X is a tetravalent aliphatic ring group, a tetravalent heteroaliphatic ring group, a tetravalent aromatic ring group, or a tetravalent heteroaromatic ring group, and the carbon atom of the carbonyl group in formula 2 is linked to the ring constituent atoms of the aliphatic ring group, heteroaliphatic ring group, aromatic ring group, or heteroaromatic ring group.

[0036] The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group are

[0037] Is it a monoring?

[0038] They join together to form a polyring, or

[0039] The groups are linked by a linking group which includes a single bond, a substituted or unsubstituted alkylene group, a substituted or unsubstituted alkylidene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted alkylylene group, a substituted or unsubstituted arylene group, and at least one divalent substituent selected from the group consisting of -O-, -S-, -C(=O)-, -S(=O)2- and -Si(Rb)2-, where Rb is hydrogen or an alkyl group.

[0040] Preferably, X is phenyl, biphenyl, [ka] or an aliphatic ring group,

[0041] The aforementioned M includes at least one selected from the group consisting of a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O)2-.

[0042] In this specification, the term "aliphatic ring group" means an aliphatic ring group having 3 to 30 carbon atoms, 4 to 25 carbon atoms, 5 to 20 carbon atoms, or 6 to 16 carbon atoms, unless otherwise specified. Specific examples of tetravalent aliphatic ring groups include, for example, groups obtained by removing four hydrogen atoms from rings such as cyclohexane, cycloheptane, cyclodecane, cyclododecane, norbornane, isobornane, adamantane, cyclododecane, and dicyclopentane rings.

[0043] In this specification, the term "aromatic ring group" means an aromatic ring group having 4 to 30 carbon atoms, 5 to 25 carbon atoms, 6 to 20 carbon atoms, or 6 to 16 carbon atoms, unless otherwise specified. The aromatic ring may be a monoring or a fused ring. Examples of tetravalent aromatic hydrocarbon ring groups include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, or a pyrene ring from which four hydrogen atoms have been removed.

[0044] In this specification, the term "arylene group" means a divalent organic group derived from the aromatic ring group.

[0045] In this specification, the term "heterocyclic group" includes heteroaliphatic and heteroaromatic groups.

[0046] In this specification, the term "heteroaliphatic ring group" means a ring group in which at least one carbon atom of the aliphatic ring group is replaced by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus.

[0047] In this specification, the term "heteroaromatic ring group" means, unless otherwise specified, a ring group in which at least one carbon atom of the aromatic ring is replaced by at least one heteroatom selected from the group consisting of nitrogen, oxygen, sulfur, and phosphorus. The heteroaromatic ring group may be a monoring or a fused ring.

[0048] The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group may each be independently replaced with at least one substituent selected from the group consisting of halogens, hydroxyl groups, carboxyl groups, halogen-substituted or unsubstituted C1-C4 alkyl groups, and C1-C4 alkoxy groups.

[0049] In this specification, the term “single bond” means a bond that connects two atoms without any other atoms. For example, in the above formula 2, X is [ka] Here, if M is a single bond, both aromatic rings may be directly linked to each other.

[0050] In this specification, the term "alkyl group" means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0051] In this specification, the term "alkenyl group" means an alkenyl group having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, unless otherwise specified. The alkenyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0052] In this specification, the term "alkynyl group" means an alkynyl group having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, or 2 to 4 carbon atoms, unless otherwise specified. The alkynyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0053] In this specification, the term "alkylene group" means an alkylene group having 2 to 30 carbon atoms, 2 to 25 carbon atoms, 2 to 20 carbon atoms, 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 10 carbon atoms, or 2 to 8 carbon atoms, unless otherwise specified. The alkylene group may have a linear, branched, or cyclic structure as a divalent organic group from which two hydrogen atoms have been removed from different carbon atoms, and may optionally be replaced by at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0054] In this specification, the term "alkylidene group" means an alkylidene group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 10 carbon atoms, or 1 to 8 carbon atoms, unless otherwise specified. The alkylidene group may have a linear, branched, or cyclic structure as a divalent organic group in which two hydrogen atoms have been removed from one carbon atom, and may optionally be replaced by at least one substituent. Examples of such substituents include polar functional groups such as halogens, hydroxyl groups, alkoxy groups, thiol groups, or at least one substituent consisting of a thioether group.

[0055] In this specification, the term "alkoxy group" means an alkoxy group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms, unless otherwise specified. The alkoxy group may have a linear, branched, or cyclic alkyl group, and the alkyl group may optionally be replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0056] In this specification, the term "alkylamine group" includes monoalkylamine (-NHR) or dialkylamine (-NR2) unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0057] In this specification, the term "alkylamide" includes monoalkylamides (-C(O)NHR) or dialkylamides (-C(O)NR2) unless otherwise specified, where R independently represents an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0058] In this specification, the terms "thioether group" or "sulfide" mean -SR unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0059] In this specification, the term "sulfoxide" means -S(O)R unless otherwise specified, where R independently means an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure and may be optionally replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0060] In this specification, the term "carbonyl" includes -C(O)R unless otherwise specified, where R independently represents an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure, and may optionally be replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0061] In this specification, the term "ester" includes -C(O)OR or -OC(O)R unless otherwise specified, where R independently represents an alkyl group having 1 to 30 carbon atoms, 1 to 25 carbon atoms, 1 to 20 carbon atoms, 1 to 16 carbon atoms, 1 to 12 carbon atoms, 1 to 8 carbon atoms, or 1 to 4 carbon atoms. Here, the alkyl group may have a linear, branched, or cyclic structure, and may optionally be replaced by at least one substituent. Examples of such substituents include at least one substituent consisting of a halogen, a hydroxyl group, an alkoxy group, a thiol group, or a thioether group.

[0062] Aliphatic tetracarboxylic dianhydrides satisfying formula 2 above are 1,2,4,5-cyclohexanetetracarboxylic dianhydride (or HPMDA), bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BODA), 1,2,3,4-cyclohexanetetracarboxylic dianhydride (CHMDA), bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic 2:3,5:6-dianhydride (BHDA), butane-1,2,3,4-tetracarboxylic dianhydride (BTD), and bicyclo-[2.2.2]octo -7-ene-2-exo,3-exo,5-exo,6-exo-2,3:5,6-dianhydride (BTA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicyclo[4.2.0]octane-3,4,7,8-tetracarboxylic dianhydride (OTD), norbornane-2-spiro-α-cyclohexanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride (ChODA), cyclopentanonebis-spironorbornanetetracarboxylic dianhydride (CpODA), bicyclo[2.2.1]Heptane-2,3,5-tricarboxyl-5-acetic acid dianhydride (BSDA), dicyclohexyl-3,3',4,4'-tetracarboxylic acid dianhydride (DCDA), dicyclohexyl-2,3'-3,4'-tetracarboxylic acid dianhydride (HBPDA), 5,5'-oxybis(hexahydro-1,3-isobenzoflangion) (HODPA), 5,5'-methylenebis(hexahydro-1,3-isobenzoflangion) (HMDPA), 3,3'-(1,4-piperazinediyl)bis[dihydro-2,5-flangion] (PDSA), 5-(2,5-dioxotetrahydrofurfuryl)-3-methyl-3-cyclohexane-1,2-dicarboxylic acid anhydride (DOCDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid dianhydride Water (TDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-6-methyl-1-naphthalenesuccinate dianhydride (MTDA), 3,4-dicarboxy-1,2,3,4-tetrahydro-6-fluoro-1-naphthalenesuccinate dianhydride (FTDA), 3,3,3',3'-tetramethyl-1,1'-spirobisindan-5,5',6,6'-tetracarboxylic anhydride (S Examples include BIDA, 4,4,4',4'-tetramethyl-3,3',4,4'-tetrahydro-2,2'-spirobio[flo[3,4-g]chromene]-6,6',8,8'-tetraone (SBCDA), or 9,10-difluoro-9,10-bis(trifluoromethyl)-9,10-dihydroanthracene-2,3,6,7-tetracarboxylic dianhydride (6FDA).

[0063] Aromatic tetracarboxylic dianhydrides satisfying Formula 2 are pyromelitic acid dianhydride (or PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (or α-BPDA), oxydiphthalic acid dianhydride (or ODPA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianhydride (or DSDA), bis(3,4-dicarboxyphenyl) sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3,3',4'-benzophenonetetracarboxylic dianhydride (or BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl ) Propane dianhydride, p-phenylenebis(trimellitic acid monoester anhydride), p-biphenylenebis(trimellitic acid monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic acid dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic acid dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene Examples include zen dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, or 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianhydride (6-FDA).

[0064] The compound represented by formula 2 is preferably an aromatic tetracarboxylic dianhydride, and may particularly include 3,3',4,4'-biphenyltetracarboxylic dianhydride (or BPDA) or 2,3,3',4'-biphenyltetracarboxylic dianhydride (or α-BPDA).

[0065] As an example, the diamine monomer may contain at least one compound represented by the following chemical formula 3.

[0066] [ka]

[0067] In the above chemical formula 3, any of B1 to B5 is an amino group, and the remainder represents hydrogen, halogen, hydroxyl group, carboxyl group, or alkyl group substituted or unsubstituted for a halogen.

[0068] Furthermore, diamine monomers that may be used in the production of polyamic acid solutions are aromatic diamines, and examples can be given by classifying them as follows.

[0069] 1) Diamines that structurally have one benzene ring and have a relatively rigid structure, such as 1,4-diaminobenzene (or paraphenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, or 3,5-diaminobenzoic acid (or DABA),

[0070] 2) Diaminodiphenyl ethers such as 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenyl Nylmethane, 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl) sulfide, 4,4'-diaminobenzanilide, 3,3'-dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'- Diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4'-dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, Diamines that structurally have two benzene rings, such as 4,4'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, or 4,4'-diaminodiphenyl sulfoxide,

[0071] 3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-amino)phenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q), 1,4-bis(4-aminophenoxy)benzene (or TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone Diamines that structurally have three benzene rings, such as 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide)benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis(4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, or 1,4-bis[2-(4-aminophenyl)isopropyl]benzene,

[0072] 4) 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl] ether, bis[3-(4-aminophenoxy)phenyl] ether, bis[4-(3-aminophenoxy)phenyl] ether, bis[3-(3-aminophenoxy)phenyl] ketone, bis[3-(4-aminophenoxy) [xy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide, bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl] 2,2-bis[3-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy]propane, 2,2-bis[4-(4-aminophenoxy] Diamines that structurally have four benzene rings, such as bis(phenyl)propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, or 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0073] The diamine monomer may be used alone or in combination of two or more as needed, and may include, for example, 1,4-diaminobenzene (PPD), 1,3-diaminobenzene (MPD), 2,4-diaminotoluene, 2,6-diaminotoluene, or 4,4'-methylenediamine (MDA). Preferably, the compound represented by Chemical Formula 2 may include 1,4-diaminobenzene (PPD).

[0074] In one example, the dianhydride monomer may be present in an amount of 90 to 102 mol% relative to 100 mol% of the diamine monomer. For example, the dianhydride monomer may be present in an amount of 91 to 102 mol%, 92 to 102 mol%, 93 to 102 mol%, 94 to 102 mol%, 95 to 102 mol%, 96 to 102 mol%, 97 to 102 mol%, 98 to 102 mol%, 90 to 101 mol%, 90 to 100 mol%, or 90 to 99 mol% relative to 100 mol% of the diamine monomer.

[0075] In one specific example, the polyimide precursor may contain 5-40% by weight, 10-30% by weight, or 15-20% by weight of solids based on the total weight. This application makes it possible to control the increase in viscosity while preventing the increase in manufacturing costs and process time that would otherwise be required to remove a large amount of solvent during the curing process, by adjusting the solids content of the polyimide precursor.

[0076] The polyimide precursor of this application may contain a high molecular weight polyamic acid and may also have low viscosity properties. The polyimide precursor of this application is measured at a temperature of 23°C and 1 s- 1The viscosity measured under the shear rate conditions may be 50,000 cP or less, 40,000 cP or less, 30,000 cP or less, 20,000 cP or less, 10,000 cP or less, 9,000 cP or less, 5,000 cP or less, 4,000 cP or less, or 3,000 cP or less. The lower limit is not particularly limited, but may be 500 cP or more, or 1,000 cP or more. In one specific example, the polyimide precursor of this application may be in the range of 500 to 10,000 cP. The viscosity may be measured, for example, at a temperature of 23°C using Haake's MARS40. By adjusting the viscosity range, this application can provide a polyimide precursor with excellent processability and ease of product application.

[0077] This application relates to a method for producing polyamic acid. The production method can provide polyamic acid having a high weight-average molecular weight by polymerizing polyamic acid under a specific solvent, and by mixing the polymerized polyamic acid with a silicon-containing first additive and a second additive containing at least one of a phosphorus-based additive or an amine-based additive, it is possible to provide a polyimide that is environmentally friendly, has high adhesive strength, excellent surface flatness and durability, and exhibits a high imidization rate.

[0078] Specifically, the manufacturing method includes a polymerization step of polymerizing a dianhydride monomer and a diamine monomer in an organic solvent containing at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA) to produce a polyamic acid; and a manufacturing step of mixing the produced polyamic acid with a silicon-containing first additive containing at least one functional group and at least one second additive selected from a phosphorus-based additive having an aromatic ring group or an amine-based additive having an aromatic or heteroaromatic ring group to produce a polyimide precursor.

[0079] The second additive, when mixed with the polyamic acid after the polymerization reaction has been completed, may contribute to increasing the imidization rate during curing.

[0080] A detailed explanation of each of the above configurations would be redundant with what has been stated above, so it will be omitted below.

[0081] This application further relates to a polyimide film comprising a cured polyimide precursor as described above. The polyimide film may be made into a film by imidizing the polyimide precursor by thermal curing. The thermal curing conditions are not particularly limited, but may be carried out within a temperature range of 100 to 400°C. The polyimide film may be attached to the bottom of a substrate of a display device.

[0082] Therefore, the thickness of the film may be formed to be thin enough to be suitable for attachment to the product, for example, the thickness may be within the range of 1-100 μm, 5-90 μm, 5-80 μm, 5-70 μm, 10-100 μm, 10-90 μm, 10-80 μm, 10-70 μm, 10-60 μm, or 10-50 μm.

[0083] Furthermore, by adjusting the composition and content ratio of the polyimide precursor mentioned above, the film can have a variety of physical properties controlled within the following numerical range.

[0084] For example, the polyimide film is UTM (Universal Testing The elongation measured using the machine may be 100% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, 30% or less, or 25% or less; the tensile strength may be 700 MPa or less, 650 MPa or less, 600 MPa or less, 550 MPa or less, 500 MPa or less, 450 MPa or less, 400 MPa or less, 350 MPa or less, 300 MPa or less, 250 MPa or less, 200 MPa or less, or 150 MPa or less; and the modulus may be 12 Gpa or less, 11 Gpa or less, 10 Gpa or less, 9 Gpa or less, 8 Gpa or less, 7 Gpa or less, 6 Gpa or less, 5 Gpa or less, 4 Gpa or less, or 3 Gpa or less. The above measurement may be performed using a UTM device under the conditions of a width of 20 mm, a grip distance of 50 mm, and a crosshead speed of 20 min / min.

[0085] Furthermore, the 1% thermal decomposition temperature (td) of the polyimide film, as measured using a TGA (Thermo Gravimetric analysis) apparatus, may be within the range of 300-600°C, 350-600°C, 400-600°C, 450-600°C, 500-600°C, 540-600°C, 560-600°C, or 570-600°C. The 1% thermal decomposition temperature (td) may be measured by removing moisture from the film at 150°C using a TGA apparatus, and then heating it to 600°C at a heating rate of 10°C / min.

[0086] In one example, the adhesive strength of the polyimide film to the polyimide substrate may be within the range of 0.05-0.5 N / cm, 0.05-0.45 N / cm, 0.05-0.4 N / cm, 0.05-0.35 N / cm, 0.05-0.3 N / cm, 0.05-0.25 N / cm, 0.05-0.2 N / cm, or 0.05-0.15 N / cm. The adhesive strength was measured using a 100 × 10 mm polyimide substrate and polyimide film with an INSTRON UTM5546 model under 90° Peel mode and a Cross Head Speed ​​of 50 mm / min.

[0087] This application further relates to a display device. For example, the device includes a substrate and the aforementioned polyimide film attached to the bottom of the substrate. The type of the display device is not particularly limited and can be applied to a variety of types without restriction. The display device has excellent heat resistance, light resistance and electrical properties because the aforementioned polyimide film is attached to the bottom of the substrate. [Effects of the Invention]

[0088] This application provides a polyimide precursor that can embody an environmentally friendly polyimide with high adhesive strength, excellent surface flatness and durability, a method for producing the polyimide precursor, a polyimide film containing a cured product of the polyimide precursor, and a display device in which the polyimide film is attached to the bottom of a substrate. [Modes for carrying out the invention]

[0089] The present application will be specifically described through the following embodiments, but the scope of this application is not limited by the embodiments described below.

[0090] Example 1 In a 500 mL glass reaction vessel equipped with a stirrer, nitrogen gas introduction and discharge pipes, N,N-dimethylpropionamide (DMPA) was added as an organic solvent, followed by 100 mol% of 1,4-diaminobenzene (PPD) and 100 mol% of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA). Polymerization was carried out at 25°C to produce a polyamic acid solution with a solid content of 15%. To the total amount of the produced polyamic acid solution, 0.01% by weight of glycidooxypropyltrimethoxysilane (silicon-containing additive) and 0.1% by weight of triphenylamine (TPA) (amine-based additive) were added, and the mixture was stirred at room temperature for 12 hours to produce a polyimide precursor.

[0091] Furthermore, the polyimide precursor was thermocured from 100°C to 460°C at a heating rate of 5°C / min to produce a polyimide film with a thickness of 10 μm.

[0092] Examples 2-7 A polyimide precursor was prepared in the same manner as in Example 1, except that it was composed as shown in Table 1 below.

[0093] Comparative Examples 1-5 A polyamic acid solution was prepared in the same manner as in Example 1, except that it was composed as shown in Table 1 below.

[0094] For reference, the phosphorus-based additive used in Table 1 was triphenyl phosphate (TPP), and this phosphorus-based additive was added to the polymerized polyamic acid solution. The content of the phosphorus-based additive is shown relative to the total polyamic acid solution.

[0095] [Table 1]

[0096] Experimental Example 1 - Surface Flatness The surfaces of the polyimide films produced in the examples and comparative examples were visually observed to check for the presence or absence of bubbles and evaluate the surface flatness. The results are shown in Table 2 according to the following criteria.

[0097] O: No bubbles are generated (excellent surface flatness) △: Few bubbles (normal surface flatness) ×: Many air bubbles are generated (the surface is not flat).

[0098] Experimental Example 2 - 1% thermal decomposition temperature (1% Td) Using a TA thermogravimetric analysis (Q50 model), polyimide films were heated to 150°C at a rate of 10°C / min under a nitrogen atmosphere, and then kept isothermal for 30 minutes to remove moisture. Subsequently, the temperature was increased to 600°C at a rate of 10°C / min, and the temperature at which a 1% weight loss occurred was measured. The results are shown in Table 2 below.

[0099] Experimental Example 3 - Adhesion The adhesion strength of the polyimide films produced in the examples and comparative examples to polyimide-coated substrates was measured.

[0100] The aforementioned adhesive strength was measured using a 100 x 10 mm polyimide substrate and polyimide film with an INSTRON UTM5546 model under 90° Peel mode and a Cross Head Speed ​​of 50 mm / min.

[0101] [Table 2]

[0102] As shown in Table 2 above, the examples containing silicon-containing additives and phosphorus-based or amine-based additives were found to be bubble-free, have excellent appearance (excellent surface flatness), and exhibit high adhesive strength.

[0103] On the other hand, NMP in Comparative Example 1 is classified as a hazardous substance, requiring additional costs for purification and posing a problem of causing environmental pollution during the processing.

[0104] Furthermore, although DMPA was used as the organic solvent, Comparative Examples 2-4, which did not contain silicon-containing additives, showed poor appearance due to the generation of bubbles (surface flatness was average or poor), and the adhesive strength was also found to be lower compared to the examples containing silicon-containing additives. In addition, Comparative Example 5, which contained only silicon-containing additives and did not contain either phosphorus-based or amine-based additives, showed excellent adhesive strength, but it was confirmed that the low imidization rate resulted in a 1% lower thermal decomposition temperature compared to the examples.

[0105] On the other hand, the examples containing amine-based or phosphorus-based additives had a higher 1% thermal decomposition temperature due to the high imidation rate, and Comparative Examples 3 and 4, which also contained amine-based or phosphorus-based additives, had a higher 1% thermal decomposition temperature compared to Comparative Example 2 due to the high imidation rate.

[0106] Since a higher 1% thermal decomposition temperature indicates superior durability, the above results confirm that amine-based or phosphorus-based additives have an effect on improving the durability of polyimide.

Claims

1. A polyamic acid containing dianhydride monomers and diamine monomers as polymerization units, An organic solvent comprising at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA), A silicon-containing first additive comprising at least one functional group, A polyimide varnish comprising a second additive containing a phosphorus-based additive having an aromatic ring group.

2. The polyimide varnish according to claim 1, wherein the organic solvent is N,N-dimethylpropionamide (DMPA).

3. The polyimide varnish according to claim 1, wherein the content of the silicon-containing first additive is 0.0001 to 1% by weight based on the total polyimide varnish.

4. The polyimide varnish according to claim 1, wherein the functional group of the silicon-containing first additive is an amine group, a carboxyl group, an alcohol, an alkoxy group, a mercapto, an epoxy group, or an isocyanate.

5. The polyimide varnish according to claim 1, wherein the content of the phosphorus-based additive is 0.001 to 2% by weight based on the total polyimide varnish.

6. The polyimide varnish according to claim 1, wherein the phosphorus-based additive is triphenylphosphate or triphenylphosphine.

7. The polyimide varnish according to claim 1, wherein the dianhydride monomer comprises at least one compound represented by the following chemical formula 2. 【Chemistry 1】 In the above formula 2, X is a tetravalent aliphatic ring group, a tetravalent heteroaliphatic ring group, a tetravalent aromatic ring group, or a tetravalent heteroaromatic ring group, and the carbon atom of the carbonyl group in formula 2 is linked to the ring constituent atoms of the aliphatic ring group, heteroaliphatic ring group, aromatic ring group, or heteroaromatic ring group. The aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group, or the heteroaromatic ring group are Is it a monoring? They join together to form a polyring, or Single bond, substituted or unsubstituted alkylene group, substituted or unsubstituted alkylidene group, substituted or unsubstituted alkenylene group, substituted or unsubstituted alkylylene group, substituted or unsubstituted arylene group, -O-, -S-, -C(=O)-, -S(=O) ２ - and -Si(R ｂ ) ２ It is linked by a linking group which contains at least one divalent substituent selected from the group consisting of -, where R ｂ These are hydrogen atoms or alkyl groups.

8. The above X is phenyl, biphenyl, 【Chemistry 2】 or an aliphatic ring group, The above M is a single bond, an alkylene group, an alkylidene group, -O-, -S-, -C(=O)-, and -S(=O) ２ The polyimide varnish according to claim 7, comprising at least one selected from the group consisting of -.

9. The polyimide varnish according to claim 7, wherein the compound represented by formula 2 comprises 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA).

10. The polyimide varnish according to claim 1, wherein the diamine monomer comprises at least one compound represented by the following chemical formula 3. 【Transformation 3】 In the above formula 3, B １ ~B ５ One of these is an amino group, and the rest represent hydrogen, halogen, hydroxyl group, carboxyl group, or halogen-substituted or unsubstituted alkyl group.

11. The polyimide varnish according to claim 10, wherein the compound represented by chemical formula 3 comprises 1,4-diaminobenzene (PPD).

12. A polymerization step to produce polyamic acid by polymerizing a dianhydride monomer and a diamine monomer under an organic solvent containing at least one selected from the group consisting of N,N-diethylacetamide (DEAc), N,N-diethylformamide (DEF), N-ethylpyrrolidone (NEP), dimethylpropionamide (DMPA), and diethylpropionamide (DEPA), and A method for producing a polyimide varnish, comprising the manufacturing step of mixing the manufactured polyamic acid with a silicon-containing first additive having at least one functional group and a second additive having a phosphorus-based additive having an aromatic ring group to produce a polyimide varnish.

13. A polyimide film comprising a cured polyimide varnish according to claim 1.

14. The polyimide film according to claim 13, wherein the thickness is in the range of 1 to 100 μm.

15. The polyimide film according to claim 13, wherein the adhesive strength to the polyimide substrate is in the range of 0.05 to 0.5 N / cm.

16. The polyimide film according to claim 13, wherein the 1% thermal decomposition temperature (Td) is in the range of 300 to 600°C.

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