KR102464794B1 - Polyimide-based film and preparation method thereof - Google Patents

Abstract

An embodiment includes a polyimide and/or polyamideimide derived from an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound, wherein the AFM modulus of the first side is 40 to 90 MPa, and the first side is The AFM modulus of the opposite second surface is 45 to 95 MPa, and the difference between the AFM modulus of the first surface and the second surface satisfies 15 MPa or less. is about

Description

Polyimide-based film and manufacturing method thereof

The embodiment relates to a polyimide-based film having excellent mechanical and optical properties while being colorless and transparent, and a method for manufacturing the same.

Polyimide-based resins withstand friction and heat well, and have excellent chemical resistance, and are widely used in primary electrical insulation materials, coatings, adhesives, extrusion resins, heat-resistant paints, heat-resistant plates, heat-resistant adhesives, heat-resistant fibers, and heat-resistant films.

For example, the polyimide-based resin is made in a powder form and used as a coating agent such as a metal or a magnet wire, and is used by mixing with other additives according to the purpose. In addition, the polyimide-based resin is used as a paint for decoration and corrosion prevention together with the fluoropolymer, and serves to bond the fluoropolymer to the metal substrate. In addition, polyimide-based resins are also used for coating kitchen utensils, and are also used as a membrane used for gas separation due to their excellent heat resistance and chemical resistance. It is also used in devices to filter contaminants.

Recently, polyimide-based films in which amide groups are introduced into polyimides have been developed as polyimide-based films that are cheaper and have excellent optical, mechanical and thermal properties.

An embodiment is to provide a polyimide-based film having excellent mechanical and optical properties while being colorless and transparent, and a method for manufacturing the same.

The polyimide-based film according to an embodiment includes a first surface and a second surface opposite to the first surface, and has a modulus asymmetry (MA) of 0.03 to 0.2 according to Equation 1 below:

[Equation 1]

In Equation 1, AM1 is the AFM modulus measured from the first surface by atomic force microscopy, AM2 is the AFM modulus measured from the second surface by atomic force microscopy, and AM2 is greater than AM1 .

A method for preparing a polyimide-based film according to an embodiment includes preparing a polyamideimide solution by simultaneously or sequentially mixing and reacting an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound in an organic solvent; preparing a gel-sheet by casting the polyamideimide solution and then drying; preparing a cured film by heat-treating the gel-sheet while moving it on a belt; and winding the cured film.

The drying is carried out at a temperature of 60 ° C. to 200 ° C. for 10 minutes to 90 minutes,

The heat treatment is performed at 200 ° C to 450 ° C for 10 minutes to 120 minutes,

The AFM modulus of the first surface of the cured film is 40 to 90 MPa, and the AFM modulus of the second surface opposite to the first surface is 45 to 95 MPa, the difference between the AFM modulus of the first surface and the second surface is 15 MPa or less.

The cover window for a display according to an exemplary embodiment includes a polyimide-based film having an AFM modulus of 40 to 90 MPa on a first surface and an AFM modulus of 45 to 95 MPa on a second surface opposite to the first surface.

A display device according to an embodiment includes a display panel; and a cover window disposed on the display panel;

The cover window includes a polyimide-based film,

The polyimide-based film includes a first surface and a second surface opposite to the first surface, and in the polyimide-based film, the modulus asymmetry (MA) expressed by Equation 1 is 0.03 to 0.2.

The polyimide-based film according to the embodiment has mechanical properties such as haze, yellowness and surface hardness while being colorless and transparent by satisfying the AFM modulus values of the first surface and the second surface opposite to the first surface in a specific numerical range. It is possible to improve optical properties.

1 shows a cross-sectional view of a polyimide-based film according to an embodiment.
2 is a cross-sectional view of a display device according to an embodiment.
3 schematically illustrates a process facility for a polyimide-based film according to an embodiment.

Hereinafter, the invention will be described in detail through embodiments. The embodiments are not limited to the contents disclosed below and may be modified in various forms as long as the gist of the invention is not changed.

In this specification, when each film, panel, or layer, etc. is described as being formed "on" or "under" each film, panel, or layer, etc., "on" )" and "under" include both "directly" or "indirectly through other elements". In addition, the reference for the upper or lower of each component will be described with reference to the drawings.

In the present specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

It should be understood that all numbers and expressions indicating amounts of ingredients, reaction conditions, etc. described herein are modified by the term "about" in all cases unless otherwise specified.

In the present specification, "substituted" means deuterium, -F, -Cl, -Br, -I, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine group, hydrazone group, unless otherwise specified. , ester group, ketone group, carboxyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted alkynyl group, substituted or unsubstituted alkoxy group, substituted or unsubstituted alicyclic organic group, It means substituted with one or more substituents selected from the group consisting of a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group, and the above-listed substituents are linked to each other to form a ring This means that it can be formed.

polyimide film

One embodiment provides a polyimide-based film having excellent mechanical properties and optical properties such as haze, yellowness and surface hardness while being colorless and transparent.

The polyimide-based film according to an embodiment includes a first surface and a second surface opposite to the first surface, and has a modulus asymmetry (MA) of 0.03 to 0.2 according to Equation 1 below:

[Equation 1]

In Equation 1, AM1 is the AFM modulus measured from the first surface by atomic force microscopy, AM2 is the AFM modulus measured from the second surface by atomic force microscopy, and AM2 is greater than AM1 .

The first surface may be one surface of the polyimide-based film, and the second surface may be the other surface of the polyimide-based film.

The polyimide-based film may include a polyimide derived from an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound, or polyamideimide, and more specifically, may include polyamideimide.

The polyamideimide may be formed by simultaneously or sequentially reacting reactants including an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound. Specifically, the polyamideimide may be formed by polymerization of an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound.

The polyamideimide includes an imide component derived from polymerization of the aromatic diamine compound and the aromatic dianhydride compound and an amide component derived from polymerization of the aromatic diamine compound and the dicarbonyl compound. do.

The aromatic diamine compound may be imide-bonded with the aromatic dianhydride compound, and may be amide-bonded with the dicarbonyl compound to form a copolymer.

The aromatic diamine compound may be a compound of Formula 1 below.

[Formula 1]

In Formula 1, E may be selected from the group consisting of a substituted or unsubstituted divalent C ₆ -C ₃₀ aromatic ring group and a substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaromatic ring group.

e is selected from an integer of 1 to 5, and when e is 2 or more, E is the same as or different from each other.

According to one embodiment, the aromatic diamine compound may include a compound having a fluorine-containing substituent. Alternatively, the diamine compound may be composed of a compound having a fluorine-containing substituent. In this case, the fluorine-containing substituent may be a fluorinated hydrocarbon group, specifically, a trifluoromethyl group, but is not limited thereto.

According to one embodiment, the aromatic diamine compound is 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl , TFMB).

Since the dianhydride compound has a low birefringence value, it may contribute to improvement of optical properties such as transmittance of the polyimide-based film.

The aromatic dianhydride compound may be a compound of Formula 2 below.

[Formula 2]

In Formula 2, G is a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aromatic ring group or a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaromatic ring group, the aromatic ring group or the heteroaromatic ring group A ring group exists alone, or is joined to form a condensed ring, or a substituted or unsubstituted C ₁ -C ₃₀ alkylene group, a substituted or unsubstituted C ₂ -C ₃₀ alkenylene group, a substituted or unsubstituted C ₂ -C ₃₀ alkynylene group, -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si(CH ₃ ) ₂ -, -C (CH ₃ ) ₂ — and —C(CF ₃ ) ₂ — may be linked by a linking group.

According to one embodiment, the aromatic dianhydride compound is 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (2,2'-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6-FDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-biphenyltetracarboxylic dianhydride), or a combination thereof.

According to one embodiment, the aromatic dianhydride compound may include a compound having a fluorine-containing substituent. Alternatively, the aromatic dianhydride compound may be composed of a compound having a fluorine-containing substituent. In this case, the fluorine-containing substituent may be a fluorinated hydrocarbon group, specifically, a trifluoromethyl group, but is not limited thereto.

In another embodiment, the aromatic dianhydride compound may consist of one single component or two mixed components.

For example, the aromatic dianhydride compound may include 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, but is not limited thereto.

According to one embodiment, the polyamideimide may include more than 0 to 50 parts by weight of the aromatic dianhydride compound based on 100 parts by weight of the aromatic diamine compound. For example, the polyamideimide may include 1 to 45 parts by weight, 3 to 45 parts by weight, or 3 to 40 parts by weight of the aromatic dianhydride compound based on 100 parts by weight of the aromatic diamine compound.

The aromatic diamine compound and the aromatic dianhydride compound may be polymerized to produce a polyamic acid.

Subsequently, the polyamic acid may be converted into polyimide through a dehydration reaction, and the polyimide includes an imide component.

The polyimide may form the following Chemical Formula A.

[Formula A]

In Formula A, the definitions of E, G, and e are the same as those described in Formulas 1 and 2.

For example, the polyimide may include the following Chemical Formula A-1, but is not limited thereto.

[Formula A-1]

In Formula A-1, n is an integer of 1 to 400.

The dicarbonyl compound may be a compound of Formula 3 below.

[Formula 3]

In Formula 3, J is a substituted or unsubstituted divalent C ₆ -C ₃₀ aliphatic ring group, a substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaliphatic ring group, a substituted or unsubstituted divalent C ₆ -C ₃₀ aromatic ring group, substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaromatic ring group, substituted or unsubstituted C ₁ -C ₃₀ alkylene group, substituted or unsubstituted C ₂ -C ₃₀ alkenylene group , substituted or unsubstituted C ₂ -C ₃₀ alkynylene group, -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si( CH ₃ ) ₂ —, —C(CH ₃ ) ₂ — and —C(CF ₃ ) ₂ —.

j is selected from an integer of 1 to 5, and when j is 2 or more, J is the same as or different from each other.

X is a halogen atom. Specifically, X may be F, Cl, Br or I. More specifically, X may be Cl, but is not limited thereto.

According to one embodiment, the dicarbonyl compound is terephthaloyl chloride (TPC), 1,1-biphenyl-4,4-dicarbonyl dichloride (1,1-biphenyl-4,4-dicarbonyl) dichloride, BPDC), isophthaloyl chloride (IPC), or a combination thereof.

According to one embodiment, the dicarbonyl compound may be a mixture of at least two different dicarbonyl compounds. Specifically, the dicarbonyl compound may include a first dicarbonyl compound and a second dicarbonyl compound.

Each of the first dicarbonyl compound and the second dicarbonyl compound may be an aromatic dicarbonyl compound. When each of the first dicarbonyl compound and the second dicarbonyl compound is an aromatic dicarbonyl compound, mechanical properties such as surface hardness of the prepared polyimide-based film may be improved.

According to one embodiment, the first dicarbonyl compound is terephthaloyl chloride, and the second dicarbonyl compound is 1,1-biphenyl-4,4-dicarbonyl dichloride, isophthaloyl chloride or its It can be a combination.

Specifically, the first dicarbonyl compound is terephthaloyl chloride, the second dicarbonyl compound is 1,1-biphenyl-4,4-dicarbonyl dichloride, or the first dicarbonyl compound is When the terephthaloyl chloride and the second dicarbonyl compound is isophthaloyl chloride, the oxidation resistance of the produced polyimide-based film may be improved.

According to one embodiment, the polyamideimide may include 50 to less than 100 parts by weight of the dicarbonyl compound based on 100 parts by weight of the aromatic diamine compound. For example, the polyamideimide may include 55 to less than 100 parts by weight or 60 to less than 100 parts by weight of the dicarbonyl compound based on 100 parts by weight of the aromatic diamine compound.

Specifically, the dicarbonyl compound may include 10 to 80 parts by weight of the first dicarbonyl compound based on 100 parts by weight of the dicarbonyl compound. For example, the dicarbonyl compound is 15 to 80 parts by weight, 20 to 80 parts by weight, 25 to 80 parts by weight, 25 to 75 parts by weight of the first dicarbonyl compound based on 100 parts by weight of the dicarbonyl compound. It may be included in parts by weight or 29 to 75 parts by weight.

In addition, the dicarbonyl compound may include 15 to 60 parts by weight of the second dicarbonyl compound based on 100 parts by weight of the dicarbonyl compound. For example, the dicarbonyl compound is 15 to 55 parts by weight, 15 to 50 parts by weight, 20 to 50 parts by weight, or 22 to 47 parts by weight of the second dicarbonyl compound, based on 100 parts by weight of the dicarbonyl compound. It may be included in parts by weight.

The aromatic diamine compound and the dicarbonyl compound may be polymerized to form the following Chemical Formula B.

[Formula B]

In Formula B, the definitions of E, J, e, and j are the same as those described in Formulas 1 and 3.

For example, the aromatic diamine compound and the dicarbonyl compound may be polymerized to form an amide represented by Formula B-1 or B-2.

[Formula B-1]

In Formula B-1, x is an integer of 1 to 400.

[Formula B-2]

In Formula B-2, y is an integer of 1 to 400.

In another embodiment, the polyamideimide may include Formula A and Formula B below:

[Formula A]

[Formula B]

In Formulas A and B, the definitions of E, G, J, e and j are the same as those defined in Formulas 1 to 3.

The polyamide-imide may include an imide component and an amide component, and a molar ratio of the imide component and the amide component may be 20:80 to 80:20 or 20:80 to 50:50. In this case, the imide component may be of Formula A, and the amide component may be of Formula B. When the above range is satisfied, it is easy to control the viscosity of the polyamideimide, and it is easy to manufacture a uniform polyimide-based film having no defects on the surface.

1 shows a cross-sectional view of a polyimide-based film according to an embodiment. Specifically, FIG. 1 illustrates a polyimide-based film 100 including a first surface 101 and a second surface 102 opposite to the first surface 101 .

The first surface 101 may be a surface that is not in direct contact with the casting body 30 for casting the polyamide-imide in the process of manufacturing the polyimide-based film. That is, the first surface 101 may be an air surface in contact with air when the polyamideimide is cast.

The second surface 102 may be a surface in direct contact with the casting body 30 while the polyimide-based film is manufactured. That is, the second surface 102 may be a belt surface in contact with the casting body, for example, a belt in the casting process.

In the present specification, the AFM modulus of the first side or the second side (one side or the other side) opposite to the first side of the polyimide-based film may be measured by an AFM equipment, specifically XE-150 (manufacturer: Park System), and the AFM equipment may use a contact mode, a non-contact mode, or a tapping mode.

The AFM device may have a different set value of the measuring device according to each mode. In the present specification, AFM modulus and AFM hardness were measured in a non-contact mode using the set values in Table 1 below.

According to one embodiment, the AFM modulus (AM1) of the first surface of the polyimide-based film is 40 to 90 MPa, and the AFM modulus (AM2) of the second surface of the polyimide-based film is 45 to 95 Mpa. For example, AM1 of the polyimide-based film is 45 to 90 MPa, 45 to 88 MPa, 50 to 88 MPa, 53 to 85 MPa, 55 to 83 MPa, 55 to 80 MPa, 55 to 75 MPa or 59 to 72 MPa. AM2 of the polyimide-based film is 50 to 95 MPa, 50 to 90 MPa, 53 to 90 MPa, 53 to 88 MPa, 55 to 85 MPa, 58 to 83 MPa, 60 to 83 MPa, 60 to 80 MPa, 60 to 78 MPa, 63 to 78 MPa, 63 to 75 MPa or 63 to 73 MPa. In this case, the modulus asymmetry MA according to Equation 1 may be 0.03 to 0.2, 0.03 to 0.18, or 0.03 to 0.15. When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the polyimide-based film may be improved.

According to one embodiment, the difference between AM1 and AM2 of the polyimide-based film is 15 MPa or less. For example, the difference between AM1 and AM2 of the polyimide-based film is 13 MPa or less, 12 MPa or less, 11 MPa or less, 1 to 15 MPa, 1 to 13 MPa, 1 to 12 MPa, 2 to 13 MPa, or 2 to 12 MPa. When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the polyimide-based film may be improved.

According to one embodiment, the polyimide-based film may have a hardness asymmetry (HA) of 0.03 to 0.15, 0.03 to 0.1, or 0.03 to 0.08 according to Equation 2:

[Equation 2]

In Equation 2, AH1 is the AFM hardness measured from the first side by an atomic force microscope, AH2 is the AFM hardness measured from the second side by an atomic force microscope, and AH2 is greater than AH1.

According to one embodiment, AH1 of the polyimide-based film may be 15 to 40 MPa, and AH2 may be 20 to 50 MPa. For example, AH1 of the polyimide-based film may be 15 to 38 MPa, 18 to 38 MPa, 20 to 38 MPa, or 20 to 35 MPa, and AH2 of the polyimide-based film may be 20 to 48 MPa, 20 to 45 MPa, 20 to 43 MPa or 20 to 40 MPa. When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the polyimide-based film may be improved.

According to one embodiment, the difference between AH1 and AH2 of the polyimide-based film may be 10 MPa or less. For example, the difference between AH1 and AH2 of the polyimide-based film is 8 MPa or less, 6 MPa or less, 5 MPa or less, 4 MPa or less, 3 MPa or less, 1 to 10 MPa, 1 to 8 MPa, 1 to 6 MPa, 1 to 5 MPa, 1 to 4 MPa, 1 to 3 MPa or 1.5 to 3 MPa. When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the polyimide-based film may be improved.

According to one embodiment, the tensile strength of the polyimide-based film may be 4.0 GPa or more. For example, the tensile strength of the polyimide-based film is 5.0 GPa or more, 6.0 GPa or more, 6.5 GPa or more, 4.0 to 10.0 GPa, 4.5 to 10.0 GPa, 5.0 to 9.0 GPa, 5.5 to 9.0 GPa, 6.0 to 9.0 GPa, 6.3 to 8.5 GPa, 6.5 to 8.0 GPa, 6.5 to 7.8 GPa or 6.5 to 7.4 GPa. When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the polyimide-based film may be improved. Specifically, when the tensile strength of the polyimide-based film satisfies the above range, the difference between the AFM modulus and the AFM modulus of the first side of the polyimide-based film and the second side opposite the first side satisfies the above range , the effect of improving the mechanical properties and optical properties of the polyimide-based film is the most excellent.

According to one embodiment, the surface hardness of the polyimide-based film may be 2H or more. The surface hardness of the polyimide-based film may be 2H or more or 4H or more.

According to one embodiment, the transmittance of the polyimide-based film may be 85% or more. For example, the transmittance of the polyimide-based film may be 86% or more, 87% or more, 88% or more, or 88.5% or more.

According to one embodiment, the haze of the polyimide-based film may be 3% or less. For example, the polyimide-based film may have a haze of 2.5% or less, 2.0% or less, 1.8% or less, 1.5% or less, 1.3% or less, 1.0% or less, 0.8% or less, or 0.6% or less.

According to one embodiment, the yellowness (Y.I.) of the polyimide-based film may be 5 or less. For example, the yellowness of the polyimide-based film may be 4.5 or less, 4.0 or less, 3.8 or less, or 3.6 or less.

According to one embodiment, the thickness of the polyimide-based film may be 10 to 200 ㎛. For example, the polyimide-based film may have a thickness of 10 to 180 μm, 20 to 150 μm, 20 to 130 μm, 25 to 100 μm, 30 to 80 μm, or 40 to 60 μm.

Manufacturing method of polyimide-based film

A method for preparing a polyimide-based film according to an embodiment includes preparing a polyamideimide solution by simultaneously or sequentially mixing and reacting an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound in an organic solvent; preparing a gel-sheet by casting the polyamideimide solution and then drying; preparing a cured film by heat-treating the gel-sheet while moving it on a belt; and winding the cured film.

The drying is performed at a temperature of 60° C. to 200° C. for 10 minutes to 90 minutes, and the heat treatment is performed at 200° C. to 450° C. for 10 minutes to 120 minutes.

The AFM modulus of the first surface of the cured film is 40 to 90 MPa, and the AFM modulus of the second surface opposite to the first surface is 45 to 95 MPa, the difference between the AFM modulus of the first surface and the second surface is 15 MPa or less.

Specifically, the method for preparing the polyimide-based film includes preparing a polyamideimide solution by simultaneously or sequentially mixing and reacting an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound in an organic solvent (S100); Casting the polyamideimide solution on a belt and drying to prepare a gel-sheet (S200); Preparing a cured film by heat treatment while moving the gel-sheet (S300); cooling the cured film while moving it on a belt (S400); and winding the cooled cured film using a winder (S500).

In the method for producing the polyimide-based film, the polyamideimide solution is prepared by simultaneously or sequentially mixing and reacting an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound in an organic solvent (S100).

The description of the aromatic dianhydride compound, the aromatic diamine compound, and the dicarbonyl compound is the same as described above.

According to one embodiment, the polyamideimide solution may be prepared by reacting the aromatic diamine compound, the aromatic dianhydride compound, and the dicarbonyl compound in an organic solvent at the same time.

In another embodiment, the preparing of the polyamideimide solution includes: preparing a polyamic acid (PAA) solution by first mixing and reacting the aromatic diamine compound and the aromatic dianhydride compound in a solvent; and simultaneously forming an amide bond and an imide bond by secondary mixing and reacting the dicarbonyl compound with the polyamic acid (PAA) solution. The polyamic acid solution is a solution containing polyamic acid.

In another embodiment, the preparing of the polyamideimide solution includes: preparing a polyamic acid solution by first mixing and reacting the aromatic diamine compound and the aromatic dianhydride compound in a solvent; preparing a polyimide (PI) solution by dehydrating the polyamic acid solution; and secondary mixing and reacting the dicarbonyl compound with the polyimide (PI) solution to further form an amide bond. The polyimide solution is a solution containing polyamideimide having an imide component.

In another embodiment, the preparing of the polyamideimide solution includes: preparing a polyamide (PA) solution by first mixing and reacting the aromatic diamine compound and the dicarbonyl compound in a solvent; and secondary mixing and reacting the aromatic dianhydride compound with the polyamide (PA) solution to further form an imide bond. The polyamide solution is a solution containing polyamideimide having an amide component.

The polyamideimide solution prepared as described above may include at least one selected from the group consisting of a polyamic acid (PAA) component, a polyamide (PA) component, and a polyimide (PI) component.

Alternatively, the polyamideimide solution is an imide component derived from polymerization of the aromatic diamine compound and the aromatic dianhydride compound and an amide derived from polymerization of the aromatic diamine compound and the dicarbonyl compound. contains ingredients.

According to one embodiment, the step of preparing the polyamideimide solution may further include adding a catalyst.

The catalyst may include, for example, betapicoline or acetic anhydride, but is not limited thereto. When the catalyst is added, the reaction rate may be improved, and chemical bonding between structures or within the structures of each component may be improved.

In one embodiment, the preparing of the polyamideimide solution may further include adjusting the viscosity of the polyamideimide solution.

Specifically, the step of preparing the polyamideimide solution comprises: (a) mixing and reacting an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound simultaneously or sequentially in an organic solvent to obtain a first polyamideimide solution manufacturing; (b) measuring the viscosity of the first polyamideimide solution to evaluate whether the target viscosity is reached; and (c) when the viscosity of the first polyamideimide solution does not reach the target viscosity, adding the dicarbonyl compound to prepare a second polyamideimide solution having the target viscosity; have.

The target viscosity may be 100,000 cps to 500,000 cps at room temperature. For example, the target viscosity is 100,000 cps to 400,000 cps, 100,000 cps to 350,000 cps, 100,000 cps to 300,000 cps, 150,000 cps to 300,000 cps, or 150,000 cps to 250,000 cps at room temperature However, the present invention is not limited thereto.

In another embodiment, the content of the solids contained in the polyamideimide solution may be 10 to 20% by weight. Specifically, the content of the solids included in the second polyamideimide solution may be 12 to 18 wt%, but is not limited thereto.

When the content of the solids contained in the polyamideimide solution is within the above range, the polyimide-based film may be effectively manufactured in the extrusion and casting processes. In addition, the prepared polyimide-based film may have mechanical properties such as improved surface hardness and optical properties such as low yellowness.

In one embodiment, the preparing of the polyamide-imide solution may further include adjusting the pH of the polyamide-imide solution. In this step, the pH of the polyamideimide solution may be adjusted to 4 to 7 or 4.5 to 7.

The pH of the polyamideimide solution may be adjusted by adding a pH adjusting agent. The pH adjusting agent is not particularly limited, but may include, for example, an amine-based compound such as an alkoxyamine, an alkylamine, or an alkanolamine.

By adjusting the pH of the polyamideimide solution to the above range, it is possible to prevent damage to equipment in the subsequent process, prevent the occurrence of defects in the film prepared from the polyamideimide solution, and in terms of yellowness and surface hardness It is possible to implement the desired optical and mechanical properties.

The pH adjusting agent may be added in an amount of 0.1 to 10 mol% based on the total number of moles of monomers in the polyamideimide solution.

The preparing of the polyamideimide solution may further include purging using an inert gas. By removing moisture and reducing impurities through the inert gas purging step, the reaction yield can be increased, and the surface appearance and mechanical properties of the final film can be excellently implemented.

The inert gas may be at least one selected from the group consisting of nitrogen, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), but is limited thereto not. Specifically, the inert gas may be nitrogen.

The polyamideimide used to prepare the polyamideimide solution may have a molar ratio of the imide component: the amide component of 20:80 to 80:20 or 20:80 to 50:50. In this case, the imide component may be of Formula A, and the amide component may be of Formula B. When the above range is satisfied, it is easy to control the viscosity of the polyamideimide, and it is easy to manufacture a uniform polyimide-based film having no defects on the surface.

By appropriately controlling the content of the imide component and the amide component, it is possible to obtain a polyimide-based film with improved optical properties, mechanical properties, and flexibility in a balanced way without a complicated process. In addition, it is possible to obtain a polyimide-based film with improved balance in optical properties, mechanical properties and flexibility while being transparent without undergoing processes such as precipitation, filtration, drying, and re-dissolution as in the prior art. The content of each of the imide component and the amide component may be adjusted by the amount of the aromatic dianhydride compound and the dicarbonyl compound added.

3 schematically illustrates a process facility for a polyimide-based film according to an embodiment.

Specifically, the polyamideimide solution described above is prepared in the polymerization facility 10 , and the polyamideimide solution thus prepared is moved and stored in the tank 20 . At this time, after preparing the polyamide-imide solution, the step of moving the polyamide-imide solution to a tank is performed without a separate process.

The polyamideimide solution prepared in the polymerization facility is moved to the tank as it is and stored without a separate precipitation and re-dissolution process to remove impurities. Conventionally, in order to remove impurities such as hydrochloric acid (HCl) generated during the preparation of the polyamide-imide solution, the prepared polyamide-imide solution is purified through a separate process to remove impurities and redissolved in a solvent. The process was carried out. However, in this case, the loss of the active ingredient increases in the process of removing impurities, and as a result, there is a problem that the yield is lowered.

Accordingly, in the manufacturing method according to an embodiment, the content of impurities is fundamentally minimized in the manufacturing process of the polyamide-imide solution, or even if certain impurities are present, they are appropriately controlled in a subsequent process to reduce the physical properties of the final film. This has the advantage of producing a film without a separate precipitation or re-dissolution process. In addition, since precipitation, filtration, drying, and re-dissolution of the polyamideimide solution can be omitted, and the solution generated in the polymerization process is directly applied to the casting process, the yield can be significantly improved.

The tank 20 is a place for storing the polyamideimide solution before filming, and the internal temperature thereof may be -20°C to 20°C. For example, the internal temperature may be -20°C to 15°C, -20°C to 10°C, -20°C to 5°C, or -20°C to 0°C, but is not limited thereto.

By controlling the temperature of the tank 20 in the above range, it is possible to prevent the polyamideimide solution from being deteriorated during storage, and it is possible to reduce the moisture content and prevent defects of the film prepared therefrom. .

The method of manufacturing the polyimide-based film may further include a step of vacuum defoaming the polyamide-imide solution moved to the tank 20 .

The vacuum defoaming may be performed for 30 minutes to 3 hours after reducing the internal pressure of the tank 20 to 0.1 bar to 0.7 bar. By performing vacuum defoaming under these conditions, it is possible to reduce bubbles inside the polyamideimide solution, and as a result, it is possible to prevent surface defects of the film prepared therefrom, and to achieve excellent optical properties such as haze.

In addition, the method of manufacturing the polyimide-based film may further include purging the polyamide-imide solution moved to the tank 20 using an inert gas.

Specifically, the purging is performed by purging the internal pressure of the tank 20 to 1 to 2 atmospheres using an inert gas. By performing nitrogen purging under these conditions, moisture in the polyamide-imide solution is removed and impurities are reduced, so that the reaction yield can be increased, and optical properties such as haze and mechanical properties can be excellently implemented.

The vacuum defoaming step and the step of purging the tank 20 with nitrogen gas are performed as separate processes. For example, the vacuum defoaming step is performed, and thereafter, the step of purging the tank 20 with nitrogen gas may be performed, but is not limited thereto.

By performing the vacuum defoaming step and the step of purging the tank with nitrogen gas, the physical properties of the surface of the prepared polyimide-based film may be improved.

Thereafter, the step of storing the polyamideimide solution in the tank 20 for 12 hours to 360 hours; may further include. At this time, the internal temperature of the tank 20 may be continuously maintained at -20 °C to 20 °C.

The manufacturing method of the polyimide-based film further includes; casting the polyamideimide solution in the tank 20 and drying it to prepare a gel-sheet (S200).

The polyamideimide solution may be cast on a casting such as a casting roll or a casting belt.

Referring to FIG. 3 , in one embodiment, the polyamideimide solution may be applied as a casting body on the casting belt 30 and dried while moving, and may be manufactured into a gel sheet.

When the polyamideimide solution is injected onto the casting belt 30, the injection amount may be 300 g/min to 700 g/min. When the injection amount of the polyamideimide solution satisfies the above range, the gel-sheet may be uniformly formed with an appropriate thickness.

In addition, the casting thickness of the polyamideimide solution may be 200 to 700 ㎛. When the polyamideimide solution is cast in such a thickness range, and dried and heat-treated to form a final film, an appropriate thickness and thickness uniformity can be secured.

According to one embodiment, after casting the polyamideimide solution, it is dried at a temperature of 60° C. to 200° C. for 10 minutes to 90 minutes to prepare a gel-sheet. During the drying, some or all of the solvent of the polyamideimide solution is volatilized to prepare the gel-sheet. For example, drying may be performed at 60°C to 200°C or 60°C to 150°C or 80°C to 150°C for 10 minutes to 60 minutes, 10 minutes to 30 minutes, or 10 minutes to 20 minutes. When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the prepared polyimide-based film may be improved.

The viscosity of the polyamideimide solution may be 100,000 to 500,000 cps at room temperature. For example, it may be 100,000 to 400,000 cps, 100,000 to 350,000 cps, or 150,000 cps to 350,000 cps. By satisfying the above range, the polyamideimide solution can be cast to a uniform thickness without defects when cast on a belt.

The method of manufacturing the polyimide-based film includes the step of preparing a cured film by heat treatment while moving the gel-sheet (S300).

Referring to FIG. 3 , the heat treatment of the gel-sheet may be performed by passing through a thermosetting machine 40 .

According to an exemplary embodiment, the heat treatment may be performed at 200° C. to 450° C. for 10 minutes to 120 minutes. For example, the heat treatment is performed at 200 °C to 420 °C, 250 °C to 420 °C, 300 °C to 420 °C, or 380 °C to 420 °C for 10 minutes to 60 minutes, 10 minutes to 30 minutes, or 10 minutes to 120 minutes. can be When the above range is satisfied, mechanical and optical properties such as haze, yellowness, and surface hardness of the prepared polyimide-based film may be improved. Specifically, by satisfying the above range, the gel-sheet may be cured to have appropriate surface hardness and modulus, and the cured film may simultaneously secure high light transmittance and low haze.

According to one embodiment, the heat treatment may be performed while raising the temperature at a rate of 2 to 80 °C / min. For example, it may be carried out while raising the temperature at a rate of 5 to 80 °C / min or 10 to 80 °C / min.

The method of manufacturing the polyimide-based film includes cooling while moving the cured film (S400).

3, the cured film is performed after passing through the thermosetting machine 40, may be performed using a separate cooling chamber (not shown), and an appropriate temperature atmosphere without a separate cooling chamber It may be carried out by composition.

The cooling while moving the cured film may include a first temperature reduction step of reducing the temperature at a rate of 100° C./min to 1,000° C./min; and a second temperature reduction step of reducing the temperature at a rate of 40° C./min to 400° C./min.

In this case, the second temperature reduction step may be performed after the first temperature reduction step, and the temperature reduction rate of the first temperature reduction step may be faster than the temperature reduction rate of the second temperature reduction step. For example, the maximum speed during the first temperature reduction step may be faster than the maximum speed during the second temperature reduction step. Alternatively, the minimum speed during the first temperature reduction step may be faster than the minimum speed during the second temperature reduction step.

By performing the cooling step of the cured film in multiple steps as described above, the physical properties of the cured film can be more stabilized, and the optical and mechanical properties of the film secured in the curing process can be stably maintained for a long period of time.

The moving speeds of the gel-sheet and of the cured film are the same.

The method of manufacturing the polyimide-based film includes winding the cooled cured film using a winder (S500).

Referring to FIG. 3 , the winding of the cooled cured film may be performed using a roll-type winder 50 .

At this time, the ratio of the moving speed of the gel-sheet on the belt during drying to the moving speed of the cured film during winding is 1:0.95 to 1:1.40. For example, the ratio of the moving speed may be 1:0.99 to 1:1.20, 1:0.99 to 1:1.10, or 1:1.10 to 1:1.05, but is not limited thereto. When the ratio of the moving speed is out of the above range, there is a fear that mechanical properties of the cured film may be damaged, and there is a risk that flexibility and elastic properties may be deteriorated.

Specifically, the moving speed of the gel-sheet on the belt during drying may be 0.1 m/min to 15 m/min, for example, 0.5 m/min to 10 m/min.

In the method of manufacturing the polyimide-based film, the thickness deviation (%) according to Equation 3 below may be 3% to 30%, for example, 5% to 20%.

[Equation 3]

Thickness deviation (%) = (M1-M2)/M2 X 100

In Equation 3, M1 is the thickness (μm) of the gel-sheet, and M2 is the thickness (μm) of the cured film cooled during winding.

The above-described physical properties of the polyimide-based film are based on a thickness of 40 to 60 μm. For example, the physical properties of the polyimide-based film may be based on a thickness of 50 μm.

The polyimide-based film may exhibit excellent optical and mechanical properties by being manufactured according to the above-described manufacturing method. The polyimide-based film may be applicable to various uses requiring flexibility and transparency. For example, the polyimide-based film may be applied to a solar cell, a display, a semiconductor device, a sensor, and the like.

display device

One embodiment provides a cover window for a display comprising a polyimide-based film having an AFM modulus of 40 to 90 MPa on a first surface, and an AFM modulus of 45 to 95 MPa on a second surface opposite to the first surface. . The polyimide-based film is the same as described above.

In addition, one embodiment is a display panel; and a cover window disposed on the display panel.

The cover window includes a polyimide-based film, the polyimide-based film includes a first surface and a second surface opposite to the first surface, and in the polyimide-based film, the polyimide-based film represented by Equation 1 The modulus asymmetry (MA) is 0.03 to 0.2.

2 is a cross-sectional view of a display device according to an embodiment. Specifically, FIG. 2 includes a display unit 400 and a polyimide-based film 100 having a first surface 101 and a second surface 102 on the display unit 400 and a functional layer 200 . A display device in which a cover window 300 is disposed, and an adhesive layer 500 is disposed between the functional layer 200 and the cover window 300 is exemplified.

The display unit may display an image, and may have a flexible characteristic.

The display unit may be a display panel for displaying an image, for example, a liquid crystal display panel or an organic electroluminescent display panel. The organic electroluminescent display panel may include a front polarizing plate and an organic electroluminescent panel.

The front polarizing plate may be disposed on the front surface of the organic electroluminescent panel. Specifically, the front polarizing plate may be adhered to a surface on which an image is displayed in the organic electroluminescent panel.

The organic electroluminescent panel displays an image by self-luminescence in units of pixels. The organic electroluminescent panel may include an organic electroluminescent substrate and a driving substrate. The organic electroluminescent substrate may include a plurality of organic electroluminescent units respectively corresponding to pixels. Specifically, each may include a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and an anode. The driving substrate may be drivably coupled to the organic electroluminescent substrate. That is, the driving substrate may be coupled to apply a driving signal, such as a driving current, to the organic EL substrate, thereby applying a current to each of the organic EL units to drive the organic EL substrate.

In addition, an adhesive layer may be included between the display unit and the cover window. The adhesive layer may be an optically transparent adhesive layer, and is not particularly limited.

The cover window is disposed on the display unit. The cover window may be positioned at the outermost portion of the display device according to the embodiment to protect the display unit.

The cover window may include a polyimide-based film and a functional layer. The functional layer may be at least one selected from the group consisting of a hard coating, a reflectance reducing layer, an antifouling layer, and an antiglare layer. The functional layer may be coated on at least one surface of the polyimide-based film.

The above will be described in more detail with reference to the following examples. However, the following examples are only for illustrating the invention, and the scope of the examples is not limited thereto.

[Example]

Example 1. Preparation of polyimide-based film

After filling 250 kg of dimethylacetamide (DMAc) as an organic solvent under a nitrogen atmosphere at 20°C in a double-jacketed glass reactor with temperature control for 1,000 L, an aromatic diamine 2,2'-bis(trifluoromethyl)- 10 kg of 4,4'-diaminobiphenyl (TFMB) was slowly added and dissolved.

Then, 2.4 kg of aromatic dianhydride, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA), was slowly added and stirred for 1 hour, followed by sulfuric acid as a filler After 150 g of barium was added, the mixture was stirred for 1 hour.

Then, as the first dicarbonyl compound, terephthaloyl chloride (TPC) was added 2.9 kg, which is 94% of the input mole, and stirred for 1 hour, and 1,1′-biphenyl- as the second dicarbonyl compound 4.7 kg of 4,4'-dicarbonyldichloride (BPDC) was added and stirred for 1 hour to prepare a first polyamideimide solution.

After measuring the viscosity of the prepared first polyamideimide solution, if the measured viscosity does not reach the target viscosity, a 10 wt% TPC solution is prepared in DMAc organic solvent until a viscosity of 200,000 cps is obtained. After adding mL, the process of stirring for 30 minutes was repeated to prepare a second polyamideimide solution.

The second polyamideimide solution was moved to a tank at -10° C. and stored, and after degassing for 1.5 hours so that the pressure in the tank became 0.3 bar, the internal pressure of the tank was purged to 1.5 atm using nitrogen gas. After purging, the second polyamideimide solution was stored in a tank for 30 hours.

Then, after casting the second polyamideimide solution, it was dried with hot air at 80° C. to 150° C. for 10 to 20 minutes to prepare a gel-sheet. Then, the gel-sheet was heat treated at 380° C. to 420° C. for 10 to 20 minutes while moving, after which the temperature was reduced in the first stage at a rate of about 800° C./min, and then the temperature was reduced in the second stage at a rate of about 100° C./min. to obtain a polyimide film, which was wound using a winder. At this time, the moving speed of the gel-sheet on the belt during drying is 1 m/s, and the ratio of the moving speed of the gel-sheet on the belt during drying: the moving speed of the film during winding is in the range of 1:1.01 to 1:1.10. By controlling the speed of the winder, a polyimide-based film (polyamideimide film) having a thickness of 50 μm was prepared.

Examples 2 to 6. Preparation of polyimide-based film

As shown in Table 2 below, the experiment was performed in the same manner as in Example 1, except that the content of each reactant, the drying temperature and time, and the heat treatment temperature and time were different.

[Evaluation example]

Evaluation Example 1: AFM modulus and AFM hardness

AFM modulus and AFM hardness were measured in non-contact mode of AFM equipment (manufacturer: Park System, equipment name: XE-150). The cantilever (manufacturer: Nanosensors, equipment name: NCHR) used when measuring AFM hardness has the following product specifications.

Evaluation Example 2: Tensile Strength

Using Instron's universal testing machine UTM 5566A, the sample was cut into pieces of 5 cm or more in the direction perpendicular to the main shrinkage direction and 10 mm in the main shrinkage direction, mounted on a clip with a spacing of 5 cm, and then 5 mm/min at room temperature Stress-strain curves were obtained until fracture occurred while stretching at a rate. In the stress-strain curve, the slope of the load with respect to the initial strain was defined as the tensile strength (GPa).

Evaluation Example 3: Surface Hardness

According to ASTM D3363, using a pencil hardness tester, after drawing 5 times under the conditions of a load of 0.5 kg and 10 mm, it was measured whether or not there was a scratch on the surface.

Evaluation Example 4: Transmittance

The light transmittance at 550 nm was measured using a haze meter NDH-5000W of Denshoku Kogyo, Japan.

Evaluation Example 5: Haze

The haze was measured using a haze meter NDH-5000W manufactured by Denshoku Kogyo, Japan.

Evaluation Example 6: Yellowness

Yellowness (Yellow Index, Y.I.) was measured using a CIE colorimeter by a spectrophotometer (UltraScan PRO, Hunter Associates Laboratory).

Evaluation Example 7: Film thickness

Using a digital micrometer 547-401 of Mitsutoyo, Japan, 5 points were measured in the width direction, and the thickness was measured as an average value.

The results of Evaluation Examples 1 to 7 are shown in Tables 4 and 5 below.

As shown in Tables 4 and 5, it can be seen that the films prepared according to Examples have a well-balanced mechanical and optical properties such as tensile strength, surface hardness, haze, modulus, yellowness and transmittance.

10: polymerization plant
20: tank
30: casting body (casting belt)
40: thermosetting machine
50: winder
100: polyimide-based film
101: first page
102: second side
200: functional layer
300: cover window
400: display unit
500: adhesive layer

Claims (15)

It contains polyamideimide formed by polymerization of an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound,
a first surface and a second surface opposite to the first surface;
The modulus asymmetry (MA) according to the following Equation 1 is 0.03 to 0.2,
A polyimide-based film having a hardness asymmetry (HA) of 0.03 to 0.1 according to Equation 2 below:
[Equation 1]

[Equation 2]

In Equations 1 and 2 above,
AM1 is the AFM modulus measured from the first side by atomic force microscopy,
AM2 is the AFM modulus measured from the second side by an atomic force microscope,
AM2 is greater than AM1,
AH1 is the AFM hardness measured from the first side by atomic force microscopy,
AH2 is the AFM hardness measured from the second side by means of an atomic force microscope,
AH2 is larger than AH1. According to claim 1,
The AM1 is 40 to 90 MPa, and the AM2 is 45 to 95 MPa, a polyimide-based film. 3. The method of claim 2,
The difference between the AM1 and the AM2 is 15 MPa or less, a polyimide-based film. 4. The method of claim 3,
The difference between the AM1 and the AM2 is 2 to 12 MPa, a polyimide-based film. delete According to claim 1,
The AH1 is 15 to 40 MPa, and the AH2 is 20 to 50 MPa, a polyimide-based film. 7. The method of claim 6,
The difference between the AH1 and the AH2 is 10 MPa or less, a polyimide-based film. According to claim 1,
The aromatic diamine compound comprises 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl;
The aromatic dianhydride compound is 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride or its including combinations,
Wherein the dicarbonyl compound comprises terephthaloyl chloride, 1,1-biphenyl-4,4-dicarbonyl dichloride, isophthaloyl chloride, or a combination thereof. According to claim 1,
Wherein the polyamideimide contains more than 0 to 50 parts by weight of the aromatic dianhydride compound, and 50 to less than 100 parts by weight of the dicarbonyl compound, based on 100 parts by weight of the aromatic diamine compound. . According to claim 1,
tensile strength of 4.0 GPa or more,
surface hardness of 2H or more,
The transmittance is 85% or more,
Haze is 3% or less,
A polyimide-based film having a yellowness (YI) of 4 or less. According to claim 1,
A polyimide-based film having a thickness of 10 to 200 μm. preparing a polyamideimide solution by simultaneously or sequentially mixing and reacting an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound in an organic solvent;
preparing a gel-sheet by casting the polyamideimide solution and then drying;
preparing a cured film by heat-treating the gel-sheet while moving it on a belt; and
Including; winding the cured film;
The ratio of the moving speed of the gel-sheet on the belt when drying: the moving speed of the film during winding is 1:1.01 to 1:1.10,
The method for producing the polyimide-based film of claim 1. delete Including a polyimide-based film and a functional layer,
The polyimide-based film comprises polyamideimide formed by polymerization of an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound,
The polyimide-based film includes a first surface and a second surface opposite to the first surface,
In the polyimide-based film, the modulus asymmetry (MA) according to the following Equation 1 is 0.03 to 0.2, and the hardness asymmetry (HA) according to the following Equation 2 is 0.03 to 0.1, a cover window for a display:
[Equation 1]

[Equation 2]

In Equations 1 and 2 above,
AM1 is the AFM modulus measured from the first side by atomic force microscopy,
AM2 is the AFM modulus measured from the second side by an atomic force microscope,
AM2 is greater than AM1,
AH1 is the AFM hardness measured from the first side by atomic force microscopy,
AH2 is the AFM hardness measured from the second side by means of an atomic force microscope,
AH2 is larger than AH1. display panel; and
Including; a cover window disposed on the display panel;
The cover window includes a polyimide-based film and a functional layer,
The polyimide-based film comprises polyamideimide formed by polymerization of an aromatic dianhydride compound, an aromatic diamine compound, and a dicarbonyl compound,
The polyimide-based film includes a first surface and a second surface opposite to the first surface,
In the polyimide-based film, the modulus asymmetry (MA) according to Equation 1 is 0.03 to 0.2, and the hardness asymmetry (HA) according to Equation 2 is 0.03 to 0.1, a display device:
[Equation 1]

[Equation 2]

In Equations 1 and 2 above,
AM1 is the AFM modulus measured from the first side by atomic force microscopy,
AM2 is the AFM modulus measured from the second side by an atomic force microscope,
AM2 is greater than AM1,
AH1 is the AFM hardness measured from the first side by atomic force microscopy,
AH2 is the AFM hardness measured from the second side by means of an atomic force microscope,
AH2 is larger than AH1.

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