KR20170136285A - High strength transparent polyamide-imide film and process for preparing same - Google Patents

Abstract

The present invention provides a polyamideimide film which maintains transparency and has greatly improved mechanical properties and heat resistance. The polyamideimide film of the present invention includes a repeating structure represented by chemical formula 1a together with a repeating structure represented by chemical formula 1b, wherein the polyamideimide film has physical properties such as a haze of 2 or less, a yellowness index (YI) of 4 or less, a pencil hardness of 2 H or more, and a modulus of 5 Gpa or more at a thickness of 20 to 100 m. The polyamideimide film is excellent in transparency, heat resistance, mechanical strength and flexibility. Therefore, the polyamideimide can be used in various fields including a substrate for elements, a cover substrate for displays, an optical film, an integrated circuit (IC) package, an adhesive film, a multilayer flexible printed circuit (FPC), a tape, a touch panel, a protective film for optical disks, and the like.

Description

TECHNICAL FIELD [0001] The present invention relates to a high strength transparent polyamide imide film and a method of manufacturing the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a polyamideimide which exhibits colorless, transparent and high strength mechanical properties, and a process for producing the same.

Polyimide (PI) is a polymer having a relatively low crystallinity or mostly noncrystalline structure. It is easy to synthesize and can produce a thin film film. It also has advantages of not requiring a crosslinking agent for curing, transparency, rigid chain structure Is a polymer material with excellent heat resistance, chemical resistance, excellent mechanical properties, electrical properties and dimensional stability. It is widely used in electric and electronic materials such as automobile, aerospace, flexible circuit board, liquid crystal alignment film for LCD, have

Although polyimide is a high-performance polymer material having high thermal stability, mechanical properties, chemical resistance, and electrical properties, it does not satisfy the basic requirement for use in the display field, which is a colorless transparent property, . For example, the coefficient of thermal expansion of Kapton sold by DuPont has a thermal expansion coefficient as low as about 30 ppm / ° C, but this is still below the requirements of plastic substrates. Therefore, many researches have been carried out to minimize changes in optical characteristics and thermal history while maintaining the basic characteristics of polyimide.

In general, the aromatic polyimide has a distinctive dark brown color because the π electrons of benzene present in the imide main chain have a charge transfer complex (CT-complex ), Because electrons can be excited because there are σ electrons, π electrons, and nonbonding non-covalent electron pairs in the imide structure.

In the case of a general polyimide, the color of yellow to red, which is a color of its color, becomes visible as it absorbs light in a visible light range from a wavelength of 400 nm or less to 500 nm. Therefore, in order to lower the CT-complex, which is a disadvantage of the aromatic polyimide, an element having relatively high electronegativity such as trifluoromethyl (-CF ₃ ), sulfone (-SO ₂ ), and ether (-O-) The introduction of an olefinic cycloolefin structure that is not benzene reduces the density of electrons present in the main chain to produce a colorless transparent polyimide film. have.

On the other hand, polyamideimide has been widely used as an industrial material for electric, electronic, mechanical, aviation, and the like since it has excellent heat resistance, mechanical strength and electrical characteristics. It is also known that polyamide imides are soluble in organic solvents, and they are also used for enamel varnishes, coatings for electrical insulation, coatings for paints, and other applications where solution molding is indispensable .

However, for use in the display field, it is necessary to develop a polymer for a flexible display having a lower coefficient of thermal expansion, high solubility, transparency and thermal stability.

A problem to be solved by the present invention is to provide a polyamideimide having improved transparency and mechanical strength.

Another object to be solved by the present invention is to provide a process for producing the polyamideimide.

Another object of the present invention is to provide a high strength transparent polyimide made of the above polyamideimide.

In order to solve the above-described technical problem,

1. A transparent polyamideimide film comprising a repeating structure represented by the following formula (1a) and a repeating structure represented by the following formula (1b), wherein the haze is 2 or less and the yellowness degree (YI) is 4 Or less, a pencil hardness of 2H or more, and a modulus of 5 GPa or more.

[Formula 1a]

[Chemical Formula 1b]

In the above general formulas (1a) and (1b)

X ₁ is A tetravalent organic group derived from a tetracarboxylic acid dianhydride represented by the following formula (2)

(2)

X ₂ is a divalent organic group derived from a compound represented by the following formula (3)

(3)

In Formula 3,

Z is one selected from a hydroxyl group (-OH), a halide group selected from -Cl, -Br, -F, -I and an alkoxy group having 1 to 5 carbon atoms (-OR)

Y ₁ and Y ₂ are divalent organic groups derived from a diamine represented by the following formula (4)

[Chemical Formula 4]

In Formula 4,

R ₁ and R ₂ each independently represent a halogen atom, -OH, -OH, -SH, nitro, -NH ₂ , 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,

Q is a single _{bond, -O-, -CR 18 R 19 -} , -C (= O) -, -C (= O) O-, -C (= O) NH-, -S-, -SO 2 - , A phenylene group and a combination thereof, wherein each of R ₁₈ and R ₁₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms Is selected.

The present invention also provides a method for producing the polyamideimide.

In order to solve the other problems of the present invention, there is provided a polyamideimide film comprising the polyamideimide.

The present invention provides a polyamideimide film having improved mechanical properties and heat resistance while maintaining transparency. The polyamide imide is excellent in transparency, heat resistance, mechanical strength and flexibility and can be used as a substrate for a device, a cover substrate for a display, an optical film, an IC (integrated circuit) package, an adhesive film, a multilayer FRC ), Tapes, touch panels, protective films for optical discs, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the present specification, all the compounds or organic groups may be substituted or unsubstituted, unless otherwise specified. Herein, the term "substituted" means that at least one hydrogen contained in the compound or organic group is substituted with 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, 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.

In the present specification, the term " combination thereof " means an alkylene group having 1 to 10 carbon atoms (e.g., a methylene group (-CH ₂ -)) , an ethylene group (-CH ₂ CH ₂ -), and the like), having 1 to 10 fluoro-alkylene group (for example, a methylene group fluoroalkyl (-CF ₂ -), ethylene perfluoro (-CF ₂ CF ₂ -), etc.), N, O, P, S, or Si, for the functional groups (e.g., including heteroatoms or this like, a carbonyl group in the molecule (-C = O-), ether group (-O-), ester (Heteroalkylene group including a group (-COO-), -S-, -NH-, or -N = N-), or two or more functional groups are condensed and connected .

Polyimide is composed of rigid aromatic rings and imide bonds and shows excellent mechanical properties and heat resistance. Based on these characteristics, polyimide is used in various forms in many industrial fields. However, the conventional polyimide absorbs a part of visible light due to electron transfer between chains and chains, and may exhibit yellowing, which may hinder the possibility of a high heat-resistant transparent material for displays. This yellowing may be caused by charge transfer complexity, which may be more pronounced as the packing of the rigid polyimide polymer chains becomes more pronounced.

In order to solve such a conventional problem

1. A polyamideimide film comprising a repeating structure represented by the following formula (1a) and a repeating structure represented by the formula (1b), wherein the haze is 2 or less and the yellowing degree (YI) is 4 or less , A pencil hardness of 2H or more, and a modulus of 5 GPa or more.

[Formula 1a]

[Chemical Formula 1b]

In the above general formulas (1a) and (1b)

X ₁ is a tetravalent organic group represented by the following formula (2) derived from tetracarboxylic dianhydride,

(2)

X ₂ is a divalent organic group derived from a compound represented by the following formula (3)

(3)

In Formula 3,

Z is one selected from a hydroxyl group (-OH), a halide group selected from -Cl, -Br, -F, -I and an alkoxy group having 1 to 5 carbon atoms (-OR)

Y &_lt; ₁ > and Y &_lt; _{2 >} are divalent organic groups derived from a diamine, at least one of which contains the structure of formula (4)

[Chemical Formula 4]

In Formula 4,

Each of R ₁ and R ₂ independently represents a halogen atom consisting of -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH), a nitro group (-NO ₂ ) 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, preferably a halogen atom, a halogenoalkyl group , An alkyl group, an aryl group, and a cyano group. For example, the halogen atom may be fluoro (-F), and the halogenoalkyl group may be a fluoroalkyl group having 1 to 10 carbon atoms including a fluoro group, such as a fluoromethyl group, a perfluoroethyl group, And the alkyl group may be selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group and a hexyl group, and the aryl group may be selected from a phenyl group and a naphthalenyl group And more preferably a substituent group including a fluorine atom such as a fluorine atom and a fluoroalkyl group.

Q is a single _{bond, -O-, -CR 18 R 19 -} , -C (= O) -, -C (= O) O-, -C (= O) NH-, -S-, -SO 2 - , A phenylene group and a combination thereof, wherein each of R ₁₈ and R ₁₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms Is selected.

The present invention can provide a method for minimizing charge transfer by preventing the packing between polyimide chains by introducing a repeating unit containing another group into the polyimide main chain to solve such yellowing phenomenon. As the repeating unit, a polyamide may be introduced into the polyimide chain, and the polymer may have excellent mechanical properties and heat resistance similarly to polyimide.

According to one embodiment, the hydrogen of the aromatic ring included in Formula 2 may be a halogen atom of -F, -Cl, -Br and -I, a hydroxyl group (-OH), a thiol group (-SH) (-NO ₂ ), a cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy group having 1 to 4 carbon atoms, a halogenoalkyl group having 1 to 10 carbon atoms, or an aryl group having 6 to 20 carbon atoms . For example, the halogen atom may be fluoro (-F), and the halogenoalkyl group may be a fluoroalkyl group having 1 to 10 carbon atoms including a fluoro group, such as a fluoromethyl group, a perfluoroethyl group, And the alkyl group may be selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group and a hexyl group, and the aryl group may be selected from a phenyl group and a naphthalenyl group And more preferably a substituent group including a fluoro group such as a fluoro atom and a fluoroalkyl group.

According to one embodiment, the formula (2) may be selected from tetracarboxylic acid dianhydrides having the structures of the following formulas (2a) to (2b).

The hydrogen of the aromatic ring included in Formula 2 may be substituted with a halogen atom, -OH, -OH, -SH, nitro, -NO ₂ , -F, -Cl, -Br, A cyano group, an alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy group having 1 to 4 carbon atoms, a halogenoalkyl group 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 examples thereof include a fluoromethyl group, a perfluoroethyl group, And the alkyl group may be selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a t-butyl group, a pentyl group and a hexyl group, and the aryl group may be selected from a phenyl group and a naphthalenyl group And more preferably a substituent group including a fluorine atom such as a fluorine atom and a fluoroalkyl group.

According to one embodiment, Formula 3 may be a dicarboxylic dichloride of Formula 3a or a dicarboxylic acid of Formula 3b.

[Chemical Formula 3]

(3b)

In addition,

Comprising the steps of: stirring a diamine comprising a structure of Formula 4;

Adding a tetracarboxylic dianhydride having a tetravalent organic group of formula (2) and a compound of formula (3) to the diamine solution to produce a polyamideimide precursor; And

And imidizing the polyamideimide precursor. The present invention also provides a process for producing a polyamideimide comprising the steps of:

  (2)

 (3)

In Formula 3,

Z is one selected from a hydroxyl group (-OH), a halide group selected from -Cl, -Br, -F, -I and an alkoxy group having 1 to 5 carbon atoms (-OR)

[Chemical Formula 4]

In Formula 4,

R ₁ and R ₂ each independently represent a halogen atom, -OH, -OH, -SH, nitro, -NH ₂ , An alkyl group having 1 to 10 carbon atoms, a halogenoalkoxy group having 1 to 4 carbon atoms, a halogenoalkyl group having 1 to 10 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

Q is a single _{bond, -O-, -CR 18 R 19 -} , -C (= O) -, -C (= O) O-, -C (= O) NH-, -S-, -SO 2 - , A phenylene group and a combination thereof, wherein each of R ₁₈ and R ₁₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms Is selected.

For example, the compound of formula (4) may be selected from the compounds of the following formulas (4a) to (4d).

The polyamideimide precursor includes a repeating structure of the following formulas (5a) and (5b), and a polyimide repeating structure of formula (1a) can be formed by imidizing the repeating structure of the following formula (5a).

[Chemical Formula 5a]

[Chemical Formula 5b]

According to one embodiment, the imidization ratio of the structure including the above-mentioned formula (Ia) may be 80 to 100%, preferably imidized at an imidization rate of 90 to 100%.

In the above general formulas (1a) to (1b)

According to the present invention, the repeating structure of Formula 1a and the repeating structure of Formula 1b may be polymerized in a molar ratio of 2: 8 to 8: 2, preferably in a molar ratio of 2: 8 to 7: 3, May be polymerized in a molar ratio of 3: 7 to 6: 4. That is, the tetracarboxylic acid dianhydride having the tetravalent organic group of Formula 2 and the compound of Formula 3 may be polymerized in a molar ratio of 2: 8 to 8: 2, preferably 2: 8 to 7: 3, more preferably in a molar ratio of 3: 7 to 6: 4, and reacted with the diamine of Formula 4 to prepare a polyamideimide precursor. At this time, when the compound of Formula 3 is reacted in an amount of 90 mol% or more, preferably 80 mol% or more, the viscosity of the polymerization solution is increased by the gelation, And the film produced therefrom may be degraded in uniformity and may affect optical properties such as transparency. When the tetracarboxylic dianhydride is contained in an amount of 90 mol% or more, preferably 80 mol% or more, or more than 70 mol%, the chain of the precursor may be decomposed by the structure of polyamic acid which is vulnerable to moisture Which may deteriorate the mechanical properties of the film.

According to one embodiment, the polyamideimide according to the present invention is a random copolymer, which may be in a randomly arranged configuration of repeating structures, which prevents intra-chain charge transfer and inhibits regular arrangement, It is possible to minimize the occurrence of partial crystallization by inter-chain hydrogen bonding of the polyamide-imide film of the present invention.

The present invention not only exhibits excellent heat resistance and mechanical properties by introducing a polyamide group into a conventional polyimide structure but also can prevent complexity of charge transfer due to packing phenomenon due to an increase in the distance between chains due to polyamide groups, , It is possible to provide a more colorless transparent polyamideimide while maintaining high heat resistance and mechanical properties.

Further, the present invention can more efficiently prepare a polyamideimide chain into which an amide group is introduced by including an amide structure in a diamine structure, and can provide a substituent having a high electronegativity, such as R ₁ and R ₂ , It is possible to provide a polyamideimide having improved optical properties such as haze characteristics and yellowing degree while having high surface hardness and high mechanical strength such as modulus, and the like.

For example, the polyamide imide according to the present invention may include a repeating structure represented by the following general formulas (1a-1) and (1b-1).

[Formula 1a-1]

[Chemical Formula 1b-1]

According to one embodiment, the polyamideimide according to the present invention can be prepared by further adding a tetracarboxylic acid dianhydride represented by the following formula (6).

[Chemical Formula 6]

In Formula 6,

X ₃ is a cycloaliphatic or tetravalent organic group containing two or more aromatic rings.

For example, X ₃ may be a tetravalent organic group containing an aliphatic ring having 3 to 24 carbon atoms or an aromatic ring having 6 to 30 carbon atoms, for example, a tetravalent organic group represented by the following general formulas (8a) to (8h) More preferably, the aromatic ring or aliphatic structure is a structure in which each ring structure is rigid, that is, a structure in which each ring is bonded in a single bond, or a structure in which each ring is directly connected May be a tetravalent organic group including a recited structure.

At least one hydrogen atom in the tetravalent organic group of the general formulas (8a) to (8h) is an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, A fluoroalkyl group having 1 to 10 carbon atoms (e.g., a fluoromethyl group, a perfluoroethyl group or a trifluoromethyl group), an aryl group having 6 to 12 carbon atoms (e.g., a phenyl group, a naphthalenyl group, etc.) A sulfonic acid group, and a carboxylic acid group, and may be substituted with a fluoroalkyl group having preferably 1 to 10 carbon atoms.

In the polyamideimide according to the present invention, Y ₁ and Y ₂ may be the same or different, and at least one of Y ₁ and Y ₂ is derived from a diamine containing the structure of formula (4).

According to one embodiment, in addition to the divalent organic group represented by the formula (4), an aliphatic, alicyclic or aromatic divalent organic group having 12 to 30 carbon atoms or an aromatic divalent organic group having 12 to 30 carbon atoms, Or aromatic divalent organic groups are directly connected to each other, or are selected from divalent organic groups connected to each other through a crosslinking structure. For example, a monocyclic or polycyclic aromatic group having 12 to 30 carbon atoms, a monocyclic or polycyclic alicyclic group having 12 to 30 carbon atoms, or a structure in which two or more thereof are linked by a single bond, 7i < / RTI > divalent organic group.

At least one hydrogen atom in the divalent organic group of formulas (7a) to (7i) is an alkyl group having 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, isopropyl, t- butyl, pentyl, A fluoroalkyl group having 1 to 10 carbon atoms (e.g., a fluoromethyl group, a perfluoroethyl group or a trifluoromethyl group), an aryl group having 6 to 12 carbon atoms (e.g., a phenyl group, a naphthalenyl group, etc.) A sulfonic acid group, and a carboxylic acid group, and may be substituted with a fluoroalkyl group having preferably 1 to 10 carbon atoms.

In the repeating structure of the polyamideimide precursor of the present invention, one or more repeating structures may contain a divalent organic group and / or a tetravalent organic group containing a fluoro-based substituent. Here, the term "fluoro group substituent" means not only a "fluoro atom substituent" but also a "substituent group containing a fluoro atom". The fluorine-based substituent may be a fluoroalkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and is at least 30 mol%, preferably at least 40 mol%, more preferably at least 40 mol% Or 60 mol% or more, and may be included at most 100 mol%, preferably 90 mol% or 80 mol% or less.

The reaction of the tetracarboxylic acid dianhydride and the dicarboxylic acid or dicarboxylic chloride with the diamine can be carried out according to a conventional method for producing a polyamideimide precursor, such as solution polymerization. Specifically, it can be produced by dissolving a diamine in an organic solvent, and then adding a tetracarboxylic acid dianhydride and a dicarboxylic acid or a dicarboxylic chloride to the resultant mixed solution to carry out a polymerization reaction. At this time, it is preferable that the total amount of the tetracarboxylic acid dianhydride and the dicarboxylic acid or dicarboxylic chloride is in the range of 1: 1.1 to 1.1: 1, or 1: 1.05 to 1.05: 1, The viscosity can be obtained.

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

The polymerization reaction may be carried out at a temperature of -20 캜 to 60 캜, preferably 0 캜 to 30 캜.

Specific examples of the organic solvent that can be used in the polymerization reaction include? -Butyrolactone, 1,3-dimethyl-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 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; Examples of the solvent include ethyl acetate, butyl acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, ethanol, propanol, ethylene glycol, propylene glycol, (DMF), diethylformamide (DEF), N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), N-methylpyrrolidone N, N-dimethylmethoxyacetamide, dimethylsulfoxide, pyridine, dimethylsulfone, hexamethylphosphoramide, tetramethylurea, N-methylcarrolactam, tetra (2-methoxyethoxy) ethane, bis [2- (2-methoxyethoxy) ethane, (2-methoxyethoxy)] ether, and mixtures thereof. May be used.

More preferred are sulfoxide type solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide type solvents such as N, N-dimethylformamide and N, N-diethylformamide, N, N-dimethylacetamide , And N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone, phenol, o-, phenol-based solvents such as p-cresol, xylenol, halogenated phenol and catechol, and hexamethylphosphoramide and? -butyrolactone, which may be used alone or as a mixture. However, the present invention is not limited to this, and aromatic hydrocarbons such as xylene and toluene may be further used. In order to accelerate the dissolution of the polymer, about 50% by weight or less of the alkali metal salt or alkaline earth metal salt May be added.

The polyamideimide precursor composition prepared according to the above-described production method preferably contains a solid content in an amount such that the composition has an appropriate viscosity in consideration of processability such as coating properties in a film forming process. According to one embodiment, the content of the composition may be controlled such that the total polymer content is 5 to 25 wt%, preferably 5 to 20 wt%, more preferably 5 to 20 wt%, or 5 to 15 wt% % ≪ / RTI >

Or the polyamideimide precursor composition may have a viscosity of 500 cP or more, or 1,000 cP or more, preferably 3,000 cP or more, and the viscosity of the polyamideimide precursor composition is 30,000 cP or less, or 20,000 cP or less, Preferably 18,000 cP or less, or 15,000 cP or less. When the viscosity of the polyamideimide precursor composition is less than 500 cP or more than 30,000 cP, bubble generation and surface roughness may be poor during processing of the polyamideimide film, resulting in deterioration of optical properties.

The molecular weight of the polyamideimide according to the present invention may be 10,000 to 200,000 g / mol, or 20,000 to 100,000 g / mol, or 30,000 to 100,000 g / mol.

The molecular weight distribution (Mw / Mn) of the polyamideimide according to the present invention is preferably 1.1 to 2.5. When the imidization rate and weight average molecular weight or molecular weight distribution of the polyamideimide deviate from the above range, film formation may be difficult or the properties of the polyamideimide-based film such as transmittance, heat resistance and mechanical properties may deteriorate.

The polyamideimide precursor composition may be in the form of a solution dissolved in an organic solvent. When the polyamideimide precursor composition has such a form, for example, when a polyamideimide precursor is synthesized in an organic solvent, the solution may be the reaction solution itself , Or the reaction solution may be diluted with another solvent. When a polyamideimide precursor is obtained as a powder, it may be dissolved in an organic solvent to form a solution.

The powder of the polymer component may be dissolved in an organic solvent and heated at the time of preparing the solution. The heating temperature is preferably 20 to 150 占 폚, particularly preferably 20 to 80 占 폚.

Next, the polyamideimide precursor obtained as a result of the polymerization reaction is imidized to prepare a transparent polyamideimide film. At this time, the imidization process may be specifically a chemical imidization or thermal imidization process.

For example, it is preferable to add a dehydrating agent and an imidation catalyst to the polymerized polyamideimide precursor solution and heat the solution to a temperature of 50 to 100 ° C to imidize the solution by a chemical reaction, or to remove the alcohol while refluxing the solution And then imidizing the polyamide-imide.

In the above chemical imidization method, pyridine, triethylamine, picoline or quinoline may be used as the imidization catalyst. In addition, a nitrogen-containing heterocyclic compound substituted or unsubstituted, a nitrogen-containing heterocyclic compound N- A substituted or unsubstituted amino acid compound, an aromatic hydrocarbon compound having a hydroxyl group or an aromatic heterocyclic compound, particularly 1,2-dimethylimidazole, N-methylimidazole, N-benzyl- Lower alkyl imidazole such as methyl imidazole, 2-methyl imidazole, 2-ethyl-4-methyl imidazole and 5-methylbenzimidazole, and N-benzyl- Substituted pyridines such as pyridine, pyridine, pyridine, isothiazole, isothiazole, isothiazole, isoquinoline, 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine and 4- May be used.

As the dehydrating agent, an acid anhydride such as acetic acid anhydride may be used

Alternatively, the precursor solution may be applied to a substrate and heat-treated on an oven or a hot plate at a temperature of 100 ° C to 300 ° C, or may be subjected to a multi-step heat treatment at various temperatures within the temperature range.

The organic solvent contained in the polyamideimide precursor composition of the present invention may be the same as the aforementioned polymerization solvent.

In the present invention, a silane coupling agent, a crosslinkable compound, an imidization accelerator for promoting imidization efficiently, and the like may be added as long as the effect is not impaired.

By introducing a polyamide structure into the molecular structure of the polyimide having a rigid structure, the interchain packing is reduced by increasing the interchain distance, and the substitution with high electronegativity is bonded to the diamine structure to lower the charge transfer. A polyamideimide film excellent in color and transparency can be produced.

The polyamide-imide film has haze of 2 or less, preferably 1 or less, more preferably 0.9 or less, in a thickness of 20 to 100 탆, and has a haze of 380 to 100 탆 in a film thickness range of 10 to 30 탆. Transparent polyamideimide having a transmittance to light of 760 nm wavelength of 80% or more and a yellowness index (YI) of about 7 or less, preferably about 5 or less, more preferably about 4 or less, or 3 or less Film. By having excellent light transmittance and yellowness as described above, it is possible to exhibit significantly improved transparency and optical characteristics.

In addition, the polyamide-imide-based films are in-plane retardation value (R _in) is from about 0 to about 100nm, or at least about 200nm retardation value (R _th) in a thickness direction or in-plane retardation value (R _in) is about 0 to And a retardation value (R _th ) in the thickness direction of about 300 nm or more.

The polyamide-imide-based film has a modulus of about 5.0 GPa or more, or about 5 to 9 GPa. The surface hardness of the polyamide-imide-based film is measured with a pencil hardness tester according to the measurement standard JIS K5400, The hardness can be confirmed by measuring the degree of scratching and pressing after 3 measurements. The surface hardness may be higher than HB or higher than F, preferably higher than H, more preferably higher than 2H. have.

Accordingly, another embodiment of the present invention provides a molded article comprising the polyamideimide copolymer.

The molded article may be a film, a fiber, a coating material, an adhesive, and the like, but is not limited thereto. The molded article may be formed by a dry-wet method, a dry method, a wet method, or the like using a composite composition of the copolymer and the inorganic particles, but is not limited thereto. Specifically, as described above, the molded article may be an optical film. In this case, the composition comprising the polyamide-imide copolymer may be applied to a substrate by a method such as spin coating, followed by drying and curing Can be easily produced.

INDUSTRIAL APPLICABILITY The polyamideimide according to the present invention can exhibit excellent colorless and transparent characteristics while maintaining the properties such as heat resistance and mechanical strength due to a rigid structure, and can be used as a substrate for devices, a cover substrate for displays, optical films, Can be used in various fields such as an IC (integrated circuit) package, an adhesive film, a multilayer FRC (flexible printed circuit), a tape, a touch panel, a protective film for an optical disc and the like, .

Specifically, by including the high-strength transparent polyamide-imide film according to the present invention, it is possible to provide a transparent polyamide-imide substrate useful as a flexible electronic device cover substrate which has excellent scratch resistance and can prevent life scratches in flexible electronic devices.

The transparent polyamideimide substrate according to the present invention is a transparent polyamideimide substrate,

High strength transparent polyamide imide film;

A transparent polyamideimide substrate formed on at least one surface of the polyamideimide film and including a cured layer of a polyisocyanate having an acrylate group and having 2 to 5 isocyanate groups.

According to one embodiment, the polyisocyanate may be represented by the following general formula (10).

[Chemical formula 10]

In Formula 10,

R < ₁₀ > has the structure of formula (11)

R ₁₂ is an alkyl group having 1 to 5 carbon atoms,

(11)

In Formula 11,

R ₁₁ is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom,

n is an integer of 0 to 5, and m is an integer of 1 to 5.

The transparent polyamideimide substrate according to one embodiment of the present invention may include a silicon oxide layer formed between the transparent polyamideimide film and the cured layer in view of improving solvent resistance, water permeability and optical properties , The silicon oxide layer may be formed by curing the polysilazane.

Specifically, the silicon oxide layer is formed by coating and drying a solution containing the polysilazane before the step of forming a coating layer on at least one side of the transparent polyamideimide film, and then curing the coated polysilazane .

According to another embodiment of the present invention, there is provided a display device including the molded article. Specifically, the display device may be a liquid crystal display device (LCD), an organic light emitting diode (OLED), or the like, but is not limited thereto.

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

Example 1 TFMB (1) / BPDA (0.5) _TPC (0.5)

N, N-dimethylacetamide (DMAc) (200 g) was charged into a stirrer through which a nitrogen gas stream was flowed. The reactor was maintained at 25 ° C and TFMB (2,2'-bis (trifluoromethyl) -4,4'- biphenyl diamine) To dissolve 21.7 g. 10 g of BPDA (3,3 ', 4,4'-biphenyltetracarboxylic dianhydride) is added to the TFMB solution at the same temperature and dissolved for a predetermined time and stirred. When sufficient agitation has been achieved, the temperature is lowered to 0 ° C and 7 g of TPC (terephthaloyl chloride) is added to continue stirring. Pyridine and acetic anhydride are added to the polyamideimide precursor solution prepared from the reaction, and the mixture is stirred sufficiently. Then, a precipitate is formed with a mixed solution of methanol and water, followed by drying. The dried polyamideimide powder was dissolved in DMAc to adjust the solid concentration to 13% to prepare a polyamideimide precursor solution.

The composition solution was spin-coated on a glass substrate to a thickness of about 30 탆. The glass substrate coated with the polyamideimide composition was placed in an oven, heated at a rate of 4 ° C / min, and cured at 300 ° C for 60 minutes. After completion of the curing process, the film formed on the glass substrate was peeled off to produce a film.

Example 2 TFMB (1) / BPDA (0.4) _TPC (0.6)

The procedure of Example 1 was repeated except that the composition of BPDA and TPC was 0.4 mol: 0.6 mol.

Example 3 TFMB (1) / BPDA (0.3) _TPC (0.7)

The procedure of Example 1 was repeated except that the composition of BPDA and TPC was 0.3 mol: 0.7 mol.

<Experimental Example 1>

The optical characteristics and the films of the respective polyamide-imide films prepared in Examples 1 to 3 were measured for transparency, yellowness and haze by the following methods, Respectively.

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

Yellowness Index (YI) was measured using a color difference meter (Color Eye 7000A).

The retardation in the plane direction (R _in ) and the retardation _{in the} thickness direction (R _th ) of the film were measured using Axoscan.

The surface hardness was measured using a pencil hardness meter according to the measurement standard JIS K5400. The hardness of the surface hardness was measured by measuring a total of three scratches per pencil under a load of 750 gf and measuring the degree of scratching and pressing .

BPDA (0.5) /
TPC (0.5)
Example 1 BPDA (0.4) /
TPC (0.6)
Example 2 BPDA (0.3) /
TPC (0.7)
Example 3 thickness
(탆) 33 31 32 YI 3.4 3.1 2.9 Haze 0.83 0.79 0.75 Rth 520 553 652 Rin 67 67 67 Hardness (750gf) 2H
1/3 2H
0/3 2H
0/3

From the results of Examples 1 to 3, it can be seen that the polyamideimide according to the present invention has excellent haze characteristics and yellowing property as well as excellent hardness characteristics.

<Example 4>

A solution of polysilazane dissolved in DBE (dibutyl ether) at 2 wt% was applied to one side of the polyamide-imide film prepared in Example 2 by wire and dried at a temperature of about 80 캜 to form a polysilazane film having a thickness of 300 nm Respectively.

Thereafter, the substrate was allowed to stand at room temperature for about 5 minutes, and thermally cured at a temperature of about 250 ° C to form a silicon oxide layer, thereby preparing a substrate having a colorless transparent polyamideimide film / silicon oxide layer structure.

The silicon oxide layer in the formula (10) on the silicon oxide layer of a colorless and transparent polyamideimide film formed on one surface R ₁₀ is m is 1 ~ 5, n to have a whole number of 0 ~ 5, R ₁₁ is a methyl group in the formula (11) And R ₁₂ is an ethyl group, is coated on the silicon oxide layer using a dip coater and dried at a temperature of 80 캜 to form a coating film having a thickness of 10 탆 . Thereafter, the cured film of polyisocyanate containing acrylate was formed on one surface by irradiating two wavelengths simultaneously with energy of 100 mW / cm ² for 10 seconds by using an ultraviolet ray curing machine of 312 nm and 365 nm to obtain a colorless transparent polyamide imide film / A substrate having a structure of a cured film of a polyisocyanate containing an oxide layer / acrylate was prepared.

<Experimental Example 2>

The properties were measured in the following manner, and the results are shown in Table 2.

 (1) Yellowness

The yellowness was measured using a spectrophotometer (CU-3700D, KONICA MINOLTA).

(2) Water permeability (g / m ² * day)

Water permeability (WVTR) was measured using a water-in-oil transient (MOCON / US / Aquatran-model-1).

(3) Pencil Hardness

The pencil hardness was measured by using an electric pencil hardness tester with a Mitsubishi Evaluation Pencil (UNI), drawing 5 times 50 mm at a rate of 180 mm / min under a load of 1 kg, and then measuring the pencil hardness without any scratches on the surface.

(5) Adhesiveness (detachable with tape 100 times)

And measured by tapping 100 times with a standard (ASTM D3359).

(6) Flexural properties

The substrate was placed in a circular tool with a diameter of 10 mm. The substrate was wound repeatedly. The film was observed by naked eyes and a microscope to see if the film was cracked.

(7) scratch resistance

The number of scratches was measured with a naked eye and an optical microscope after rubbing a 500 g load and a 100 mm speed at a speed of 50 mm / sec using a steelwool reciprocating 500 times.

YI Water permeability
(gm ^-2 / day) Pencil hardness
(1 kg 180 mm / min) Adhesiveness Bending characteristic
(Radius of curvature: 10 mm) Scratch resistance
(steel wool 500 times) Example 4 3.8 20 5H 5B OK 0

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

Claims (14)

1. A polyamideimide film comprising a repeating structure represented by the following formula (1a) and a repeating structure represented by the following formula (1b), wherein the haze is 2 or less and the yellowing degree (YI) is 4 or less , A pencil hardness of 2H or more, and a modulus of 5 GPa or more. The polyamide-
[Formula 1a]

[Chemical Formula 1b]

In the above general formulas (1a) and (1b)
X ₁ is a tetravalent organic group derived from tetracarboxylic dianhydride represented by the following formula (2)
(2)

X ₂ is a divalent organic group derived from a compound represented by the following formula (3)
(3)

In Formula 3,
Z is one selected from a hydroxyl group (-OH), a halide group selected from -Cl, -Br, -F, -I and an alkoxy group having 1 to 5 carbon atoms (-OR)
Y ₁ and Y ₂ are divalent organic groups derived from a diamine, at least one of which contains a divalent organic group represented by the following formula (4)
[Chemical Formula 4]

In Formula 4,
R ₁ and R ₂ each independently represent a halogen atom, -OH, -OH, -SH, nitro, -NH ₂ , 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,
Q is a single _{bond, -O-, -CR 18 R 19 -} , -C (= O) -, -C (= O) O-, -C (= O) NH-, -S-, -SO 2 - , A phenylene group and a combination thereof, wherein each of R ₁₈ and R ₁₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms Is selected. The method according to claim 1,
Wherein the divalent organic group of the formula (4) is one selected from compounds represented by the following formulas (4a) to (4d):

The method according to claim 1,
Wherein the repeating structure of Formula 1a and the repeating structure of Formula 1b are polymerized in a molar ratio of 2: 8 to 7: 3. The method according to claim 1,
Wherein the repeating structure of Formula 1a and the repeating structure of Formula 1b are polymerized in the form of a random copolymer. The method according to claim 1,
Wherein the repeating units represented by the general formulas (1a) and (1b) include repeating units represented by the following general formulas (1a-1) and (1b-1)
[Formula 1a-1]

[Chemical Formula 1b-1]

Comprising the steps of: stirring a diamine solution comprising a structure of Formula 4;
Adding a tetracarboxylic dianhydride having a structure represented by the following formula 2 and a compound of the following formula 3 to the diamine solution to produce a polyamideimide precursor; And
A process for producing a polyamide-imide film according to claim 1, comprising the step of imidizing the polyamide-imide precursor:
(2)

(3)

In Formula 3,
Z is one selected from the group consisting of a hydroxyl group (-OH), a halide group (-Cl, -Br, -F, -I), and an alkoxy group having 1 to 5 carbon atoms (-OR)
[Chemical Formula 4]

In Formula 4,
R ₁ and R ₂ each independently represent a halogen atom, -OH, -OH, -SH, nitro, -NH ₂ , 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,
Q is a single _{bond, -O-, -CR 18 R 19 -} , -C (= O) -, -C (= O) O-, -C (= O) NH-, -S-, -SO 2 - , A phenylene group and a combination thereof, wherein each of R ₁₈ and R ₁₉ is independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, and a fluoroalkyl group having 1 to 10 carbon atoms Is selected. The method according to claim 6,
Wherein the tetracarboxylic acid of Formula 2 and diisocyanate of Formula 3 are added in a molar ratio of 2: 8 to 7: 3. The method according to claim 6,
Wherein the compound of Formula 2 and Formula 3 is reacted with the diamine of Formula 4 in a molar ratio of 1: 1.1 to 1.1: 1. The method according to claim 6,
Wherein the compound of Formula 3 is a compound of Formula 3a or Formula 3b:
[Chemical Formula 3]

(3b)

The method according to claim 6,
Wherein the polyamide-imide is cured at a temperature in the range of 200 占 폚 to 300 占 폚. A high strength transparent polyamide imide film according to claim 1;
A transparent polyamideimide substrate formed on at least one surface of the polyamideimide film, the transparent polyamideimide substrate comprising an acrylate group and a cured layer of a polyisocyanate having 2 to 5 isocyanate groups. 12. The method of claim 11,
Wherein the polyisocyanate is represented by the following formula (10): &lt; EMI ID =
[Chemical formula 10]

In Formula 10,
R &lt; ₁₀ &gt; has the structure of formula (11)
R ₁₂ is an alkyl group having 1 to 5 carbon atoms,
(11)

In Formula 11,
R ₁₁ is an alkyl group having 1 to 3 carbon atoms or a hydrogen atom,
n is an integer of 0 to 5, and m is an integer of 1 to 5. 12. The method of claim 11,
A transparent polyimide substrate further comprising a silicon oxide layer formed between the transparent polyamideimide film and the cured layer. 12. The method of claim 11,
A transparent polyamide further comprising a silicon oxide layer formed by coating and drying a solution containing the polysilazane and curing the coated polysilazane before forming the coating layer on at least one side of the transparent polyamideimide film, Mid substrate.