KR102301588B1 - Polyamide-imide film, preparation method thereof, and display front plate and display device comprising same - Google Patents

Abstract

The embodiment relates to a polyamide-imide film that maintains a clean appearance and transparency as well as excellent anti-blocking properties, a method for manufacturing the same, and a display front panel and a display device including the same, wherein the polyamide-imide film is a diamine a polyamide-imide polymer formed by polymerizing a compound, a dianhydride compound, and a dicarbonyl compound; and a filler; wherein the dicarbonyl compound includes a first dicarbonyl compound and a second dicarbonyl compound, and the first dicarbonyl compound and the second dicarbonyl compound are in a structural isomer relationship with each other. , the FH value of Equation 1 is 0.5 or less.

Description

Polyamide-imide film, manufacturing method thereof, and display front panel and display device including the same

The embodiment relates to a polyamide-imide film having excellent anti-blocking properties as well as maintaining a clean appearance and transparency, a manufacturing method thereof, and a display front panel and a display device including the same.

Polyimide-based resins such as poly(amide-imide) (PAI), etc. have excellent friction, heat, and chemical resistance, and are therefore primary electrical insulation materials, coatings, adhesives, extrusion resins, and heat-resistant paints. , heat-resistant plate, heat-resistant adhesive, heat-resistant fiber and heat-resistant film.

Polyimide is used in various fields. For example, polyimide is made in powder form and used as a coating agent for metal or magnet wire, etc., and is used by mixing with other additives depending on the purpose. In addition, polyimide is used together with fluoropolymers as paints for decoration and corrosion protection, and serves to bond fluoropolymers to metal substrates. In addition, polyimide is also used for coating on kitchen utensils, and is also used as a membrane used for gas separation due to its heat and chemical resistance, and is a filtering device for contaminants such as carbon dioxide, hydrogen sulfide and impurities in natural gas wells. is also used for

Recently, by filming polyamide-imide, a polyamide-imide-based film having excellent optical, mechanical and thermal properties while being cheaper has been developed. The polyamide-imide film of the organic light emitting diode (OLED; organic light-emitting diode ) or a liquid crystal display (LCD; liquid -crystal display) can be applied to the display material and the like, anti-reflection properties, the implementation phase difference film, a compensation film Or it can be applied to the retardation film.

Such a polyamide-imide-based film must be smoothly wound without causing defects such as scratches by smoothly running the interface with a high-hardness guide roll passed through during the production process.

Existing polyamide-imide-based films have been introduced with additives to implement anti-blocking properties, but the additives used in polymers with a high amide content in the film act as nucleating agents to cause particles to aggregate or to precipitate on the surface of the film, causing haze. , there was a problem that the yellowness increased or the appearance of the film was poor.

Accordingly, research on the development of a film having a clean appearance and excellent anti-blocking properties without deterioration of optical and mechanical properties is continuously required.

An embodiment is to provide a polyamide-imide film having excellent anti-blocking properties as well as maintaining a clean appearance and transparency, a manufacturing method thereof, and a display front panel and a display device including the same.

A polyamide-imide film according to an embodiment may include a polyamide-imide polymer formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound; and a filler; wherein the dicarbonyl compound includes a first dicarbonyl compound and a second dicarbonyl compound, and the first dicarbonyl compound and the second dicarbonyl compound have a structural isomer relationship with each other. , the FH value of Equation 1 is 0.5 or less.

X

<Formula 1> FH =

X

In Equation 1, FC is the filler content (ppm) based on the total weight of the polymer solids, and HZ is the haze (%) of the film.

A display front panel according to another embodiment includes a polyamide-imide film and a functional layer, the polyamide-imide film includes a polyamide-imide polymer and a filler, and the FH value of Equation 1 is 0.5 is below.

A display device according to another exemplary embodiment includes a display unit; and a display front plate disposed on the display unit, wherein the display front plate includes a polyamide-imide film, the polyamide-imide film includes a polyamide-imide polymer and a filler, wherein the The FH value of Equation 1 is 0.5 or less.

A method for preparing a polyamide-imide film according to an embodiment includes preparing a polyamide-imide polymer solution by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent; adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps; adding a filler dispersion in which the filler is dispersed into the polymer solution; pouring the polymer solution into a tank; manufacturing a gel sheet by extruding and casting the polymer solution in the tank and then drying; and heat-treating the gel sheet.

The polyamide-imide film according to the embodiment has excellent anti-blocking properties as well as excellent mechanical and optical properties.

In addition, the polyamide-imide film according to the embodiment has few defects such as scratches, exhibits excellent flexural properties, and has excellent haze and transmittance, so it is easy to apply to a display front panel and a display device.

When preparing the polyamide-imide film according to the embodiment, by controlling the viscosity and drying temperature of the polymer solution, it is possible to achieve an advantageous effect due to filler input without increasing haze.

1 is a cross-sectional view of a display device according to an exemplary embodiment.
2 is a schematic flowchart of a method for manufacturing a polyamide-imide film according to an embodiment.
3 schematically shows a process facility for a polyamide-imide film according to an embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the embodiment may be embodied in many different forms and is not limited to the embodiment described herein.

Where each film, window, panel, or layer, etc. is described herein as being formed "on" or "under" each film, window, panel, or layer, etc., "on" “(on)” and “under” include both “directly” or “indirectly through” other elements. In addition, the reference for the upper / lower of each component will be described with reference to the drawings. The size of each component in the drawings may be exaggerated for explanation, and does not mean the size actually applied. Also, like reference numerals refer to like elements throughout.

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.

In the present specification, unless otherwise specified, the expression "a" or "a" is interpreted as meaning including the singular or the plural as interpreted in context.

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

In this specification, terms such as first, second, etc. are used to describe various components, and the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

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

polyamide -imide film

The embodiment provides a polyamide-imide film having excellent anti-blocking properties as well as maintaining a clean appearance and transparency.

A polyamide-imide film according to an embodiment includes a polyamide-imide polymer and a filler. The polyamide-imide polymer is formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound.

Specifically, the dicarbonyl compound includes a first dicarbonyl compound and a second dicarbonyl compound, and the first dicarbonyl compound and the second dicarbonyl compound have a structural isomer relationship with each other.

The polyamide-imide film has an FH value of 0.5 or less in Equation 1 below.

X

<Formula 1> FH =

X

In Equation 1, FC is the filler content (ppm) based on the total weight of the polymer solids, and HZ is the haze (%) of the film.

The content (FC) of the filler is 1 ppm when the polymer solid content is 1,000,000 g, the filler is 1 g.

Specifically, the polyamide-imide film may have the FH value of 0.4 or less, 0.3 or less, 0.3 or less, or 0.25 or less, but is not limited thereto.

The FH value is a value expressed using a correlation between the content of the filler and the haze of the film as variables.

In general, when the content of the filler is increased, defects such as scratches are decreased as the slip property is improved, while the haze is increased and the optical properties are rapidly deteriorated. On the other hand, when the content of the filler is low, there is a problem in that mechanical properties are deteriorated as the slip property is lowered.

Therefore, it is easy to apply the film to the front panel of the display and the display device only when the content of the filler is increased and the haze is lowered to achieve both mechanical and optical properties above a certain level.

In the polyamide-imide film according to the embodiment, when the FH value, which is a parameter value in which the filler content and haze are used as variables, is within the above range, windability when wound in a roll shape and runability in the production process Because it is excellent, defects such as scratches or wrinkles do not occur. In addition, it is advantageous to apply to a display front panel and a display device by implementing a film having excellent transmittance, haze, and yellowness, and having a high modulus. That is, when the FH value of the polyamide-imide film is within the above range, mechanical properties and optical properties can be realized at a level suitable for application to a display front panel and a display device.

Specifically, when the FH value of the polyamide-imide film exceeds the above range, haze and yellowness are significantly increased. Alternatively, aggregation of fillers may occur, which may cause a feeling of foreign matter on the surface of the film.

The filler is not particularly limited as long as it is a material capable of imparting various functions to the polyamide-imide film.

For example, the filler is a UV absorber having a UV blocking function to protect the inside of the display, an inorganic material having an anti-blocking function for good winding and unwinding during the film production process, and a color adjustment function to realize the aesthetics of the film It may be a pigment, etc. having, but is not limited thereto.

Specifically, the UV absorber may be at least one selected from a benzophenone-based compound, a benzotriazole-based compound, and a triazine-based compound, and the inorganic material may be a silica-based material, The pigment is CI Pigment Red 108, Cadmium zinc sulfide, C.I. Pigment Green 50 and C.I. It may be one or more selected from Pigment Blue 28, but is not limited thereto.

More specifically, the filler may be a silica-based material.

The average particle diameter of the filler is 70 nm to 120 nm. Specifically, the average particle diameter of the filler may be 70 nm to 110 nm, 80 nm to 120 nm, 80 nm to 110 nm, or 80 nm to 100 nm, but is not limited thereto.

The content of the filler is 300 to 2,000 ppm based on the total weight of the polyamide-imide polymer. Specifically, the content of the filler is 300 to 1,500 ppm, 300 to 1,200 ppm, 300 to 1,000 ppm, 500 to 1,000 ppm, 300 to 800 ppm, 400 to 800 ppm or It may be 500 to 800 ppm, but is not limited thereto.

In the case of the film having the particle size and content of the filler satisfying the above range, since the anti-blocking property is excellent, the winding property when wound in a roll shape and the running property in the production process are excellent. In addition, since the film has excellent slip properties, it is easy to apply as a display front panel and a display device because scratches, wrinkles, etc., occur less during winding and unwinding.

When the particle size and content of the filler are less than the above range, an appropriate level of anti-blocking property cannot be implemented, and defects in the film increase. there is a problem that

The IS value represented by the following formula 3 of the polyamide-imide film is 5 to 100.

<Equation 3> IS = IM +

In Equation 3, IM means the number of moles of the imide repeating unit when the total number of moles of the imide repeating unit and the amide repeating unit in the film is 100, and RS is the content (ppm) of the residual solvent in the film. ) means

For example, the IS value may be 5 to 80, 5 to 60, or 5 to 50, but is not limited thereto.

Since the IS value of the polyamide-imide film satisfies the above range, a film having excellent durability and excellent folding characteristics may be implemented.

In particular, when the imide content (IM) is high or the content (RS) of the residual solvent in the film is high and exceeds the above range, the long-term durability of the film is rapidly deteriorated. Specifically, if the imide content is too high and the amide content is relatively low, mechanical properties such as modulus and hardness of the film are deteriorated.

The content of the residual solvent in the polyamide-imide film according to the embodiment is 900 ppm or less. For example, the content of the residual solvent may be 800 ppm or less, 700 ppm or less, 500 ppm or less, or 300 ppm or less, but is not limited thereto.

The residual solvent refers to the amount of the solvent remaining in the finally prepared film without volatilization during the film production.

When the content of the residual solvent in the polyamide-imide film exceeds the above range, the durability of the film may be deteriorated, and in particular, post-processing of the film may be affected. Specifically, when the content of the residual solvent exceeds the above range, the hydrolysis of the film may be accelerated, thereby reducing mechanical properties or optical properties.

When the polyamide-imide film according to the embodiment is folded to have a radius of curvature of 2 mm based on a thickness of 50 μm, the number of times of folding before breaking is 100,000 or more.

The number of times of folding is to be bent and unfolded so that the radius of curvature of the film is 2 mm.

The polyamide-imide film may be usefully applied to a foldable display device or a flexible display device because the number of times of folding in the above-described range is satisfied.

The polyamide-imide film according to an embodiment includes a polyamide-imide polymer formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound.

The molar ratio of the dianhydride compound and the dicarbonyl compound is 2:98 to 50:50. Specifically, the molar ratio of the dianhydride compound to the dicarbonyl compound is 2:98 to 45:55, 2:98 to 40:60, 2:98 to 30:70, 2:98 to 25:75, 3 :97 to 25:75, 2:98 to 20:80, 3:97 to 20:80, 2:98 to 15:85, 3:97 to 15:86, 2:98 to 25:75 or 2:98 to 15:85.

When the molar ratio of the dianhydride compound to the dicarbonyl compound is within the above range, a film having strong durability and excellent mechanical properties and optical properties may be implemented.

Specifically, based on the molar ratio, when the dianhydride compound is more than the dicarbonyl compound, mechanical properties such as modulus may be reduced, and when the dicarbonyl compound is more than the dianhydride compound, haze However, the optical properties are rapidly deteriorated, and the mechanical properties may also be somewhat deteriorated.

In another embodiment, the dianhydride compound may consist of one type and the dicarbonyl compound may consist of two types.

The polyamide-imide polymer includes an imide repeating unit derived from polymerization of a diamine compound and a dianhydride compound and an amide repeating unit derived from polymerization of the diamine compound and a dicarbonyl compound. .

The diamine compound is a compound that forms a copolymer by imide bonding with the dianhydride compound and amide bonding with the dicarbonyl compound.

The diamine compound is not particularly limited, but may be, for example, an aromatic diamine compound having an aromatic structure. For example, the diamine compound may be a compound of Formula 1 below.

<Formula 1>

In Formula 1,

E 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, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si(CH ₃ ) ₂ -, -C(CH ₃ ) ₂ - and -C(CF ₃ ) ₂ -.

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

(E) _e of Formula 1 may be selected from the group represented by Formulas 1-1a to 1-14a, but is not limited thereto.

Specifically, (E) _e of Formula 1 may be selected from the group represented by Formulas 1-1b to 1-13b, but is not limited thereto:

More specifically, (E)e of Formula 1 may be a group represented by Formula 1-6b or a group represented by Formula 1-9b.

In one embodiment, the diamine compound may include a compound having a fluorine-containing substituent or a compound having an ether group (-O-).

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.

In another embodiment, as the diamine compound, one type of diamine compound may be used. That is, the diamine compound may consist of a single component.

For example, the diamine compound is 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (2,2'-Bis(trifluoromethyl)-4,4 having the following structure '-diaminobiphenyl, TFMB), but is not limited thereto.

Since the dianhydride compound has a low birefringence value, it is a compound that can contribute to improvement of optical properties such as transmittance of a film including the polyimide-based polymer. The polyimide-based polymer refers to a polymer including an imide repeating unit.

The dianhydride compound is not particularly limited, but may be, for example, an aromatic dianhydride compound having an aromatic structure. For example, 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 aliphatic ring group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaliphatic ring group, or a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aromatic ring group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaromatic ring group, and the aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group or the heteroaromatic ring group exists alone, or , are bonded to each other to form a condensed ring, 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 -.

G in Formula 2 may be selected from the group represented by Formulas 2-1a to 2-9a, but is not limited thereto.

For example, G in Formula 2 may be a group represented by 2-2a, a group represented by Formula 2-8a, or a group represented by 2-9a.

In one embodiment, the dianhydride compound may include a compound having a fluorine-containing substituent, a compound having a biphenyl group, or a compound having a ketone group.

The 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 dianhydride compound may consist of one single component or two mixed components.

For example, the dianhydride compound is 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (2,2'-Bis- (3,4 -Dicarboxyphenyl)hexafluoropropane dianhydride, 6FDA), but is not limited thereto.

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

Subsequently, the polyamic acid may be converted to polyimide through a dehydration reaction, and the polyimide includes an imide repeating unit.

The polyimide may form a repeating unit represented by the following Chemical Formula A.

<Formula A>

In Formula A, descriptions of E, G and e are the same as described above.

For example, the polyimide may include a repeating unit represented by 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 is not particularly limited, but may be, for example, 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 may be the same as or different from each other.

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

(J) _j of Formula 3 may be selected from the group represented by Formulas 3-1a to 3-14a, but is not limited thereto.

Specifically, (J) _j in Formula 3 may be selected from the group represented by Formulas 3-1b to 3-8b, but is not limited thereto:

More specifically, (J) _j in Formula 3 may be a group represented by Formula 3-1b, a group represented by Formula 3-2b, a group represented by 3-3b, or a group represented by 3-8b. have.

In one embodiment, as the dicarbonyl compound, at least two different dicarbonyl compounds may be mixed and used. When two or more kinds of the dicarbonyl compound are _{used, two or more kinds selected from the group in which (J) j} in Chemical Formula 3 is represented by Chemical Formulas 3-1b to 3-8b may be used. have.

In another embodiment, the dicarbonyl compound may be an aromatic dicarbonyl compound including an aromatic structure.

For example, the dicarbonyl compound may include a first dicarbonyl compound and/or a second dicarbonyl compound.

Each of the first dicarbonyl compound and the second dicarbonyl compound may be an aromatic dicarbonyl compound.

The first dicarbonyl compound and the second dicarbonyl compound may be different compounds.

For example, the first dicarbonyl compound and the second dicarbonyl compound may be different aromatic dicarbonyl compounds, but is not limited thereto.

When the first dicarbonyl compound and the second dicarbonyl compound are each an aromatic dicarbonyl compound, since they contain a benzene ring, the surface hardness and tensile strength of the prepared polyamide-imide resin-containing film It can contribute to improving mechanical properties such as

In addition, the first dicarbonyl compound and the second dicarbonyl compound may have a structural isomer relationship with each other.

Specifically, the first dicarbonyl compound may be a compound having two carbonyl groups at the m-position, and the second dicarbonyl compound may be a compound having two carbonyl groups at the p-position, but is not limited thereto. .

The dicarbonyl compound is terephthaloyl chloride (TPC), 1,1'-biphenyl-4,4'-dicarbonyl dichloride (1,1'-biphenyl-4) having the following structure ,4'-dicarbonyl dichloride, BPDC), isophthaloyl chloride (Isophthaloyl chloride, IPC), or a combination thereof may be included, but is not limited thereto.

For example, the first dicarbonyl compound may include BPDC, and the second dicarbonyl compound may include TPC, but is not limited thereto.

When BPDC as the first dicarbonyl compound and TPC as the second dicarbonyl compound are appropriately used in combination, the prepared film including the polyamide-imide resin may have high oxidation resistance.

Alternatively, the first dicarbonyl compound may include IPC, and the second dicarbonyl compound may include TPC, but is not limited thereto.

When IPC as the first dicarbonyl compound and TPC as the second dicarbonyl compound are used in an appropriate combination, the prepared film including the polyamide-imide resin may have high oxidation resistance as well as It is economical because it can reduce costs.

The diamine compound and the dicarbonyl compound may be polymerized to form a repeating unit represented by the following Chemical Formula B.

<Formula B>

In Formula B, descriptions of E, J, e and j are the same as described above.

For example, the diamine compound and the dicarbonyl compound may be polymerized to form an amide repeating unit represented by Chemical Formulas B-1 and B-2.

Alternatively, the diamine compound and the dicarbonyl compound may be polymerized to form an amide repeating unit represented by Chemical Formulas B-2 and B-3.

<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.

<Formula B-3>

In Formula B-3, y is an integer of 1 to 400.

According to one embodiment, the polyamide-imide polymer may include a repeating unit represented by the following Chemical Formula A and a repeating unit represented by the following Chemical Formula B:

<Formula A>

<Formula B>

In Formulas A and B,

E and J are each independently, 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 -;

e and j are each independently selected from an integer of 1 to 5,

when e is 2 or more, 2 or more E are the same or different from each other,

when j is 2 or more, 2 or more J are the same or different from each other,

G is a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aliphatic ring group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaliphatic ring group, or a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aromatic ring group , a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaromatic ring group, and the aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group or the heteroaromatic ring group exists alone, or are fused to each other to form a condensed ring to form, 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 - are connected by a linking group selected from -.

In the polyamide-imide polymer, the molar ratio of the repeating unit represented by Formula A to the repeating unit represented by Formula B may be 2:98 to 50:50, but is not limited thereto. Specifically, the molar ratio of the repeating unit represented by Formula A and the repeating unit represented by Formula B is 2:98 to 45:55, 2:98 to 40:60, 2:98 to 30:70, 2:98 to 25:75, 3:97 to 25:75, 2:98 to 20:80, 3:97 to 20:80, 2:98 to 15:85, 3:97 to 15:86, 2:98 to 25 :75 or 2:98 to 15:85, but is not limited thereto.

When the molar ratio of the repeating unit represented by Formula A and the repeating unit represented by Formula B is within the above range, the polyamide-imide film has excellent anti-blocking properties, slip properties, folding properties, optical properties and mechanical properties. .

According to one embodiment, the transmittance of the polyamide-imide film may be 80% or more. For example, the transmittance may be 85% or more, 88% or more, 80% to 99%, 85% to 99%, or 88% to 99%.

The polyamide-imide film has a haze of 1% or less. Specifically, the haze may be 0.9% or less, but is not limited thereto.

The polyamide-imide film has a yellow index of 3 or less. For example, the yellowness may be 2.9 or less or 2.8 or less, but is not limited thereto.

The modulus of the polyamide-imide film is 5.0 GPa or more. Specifically, the modulus may be 5.5 GPa or more, 6.0 GPa or more, 6.5 GPa or more, 6.8 GPa or more, or 7.0 GPa or more, but is not limited thereto.

The compressive strength of the polyamide-imide film is 0.4 kgf/㎛ or more. Specifically, the compressive strength may be 0.45 kgf/㎛ or more or 0.46 kgf/㎛ or more, but is not limited thereto.

When the polyamide-imide film is perforated at a speed of 10 mm/min using a 2.5 mm spherical tip in UTM compression mode, the maximum diameter of perforation (mm) including cracks is 60 mm or less. Specifically, the maximum diameter of the perforation may be 5 to 60 mm, 10 to 60 mm, 15 to 60 mm, 20 to 60 mm, 25 to 60 mm, or 25 to 58 mm, but is not limited thereto.

The polyamide-imide film has a surface hardness of HB or more. Specifically, the surface hardness may be H or more or 2H or more, but is not limited thereto.

The polyamide-imide film has a tensile strength of 15 kgf/mm ² or more. Specifically, the tensile strength may be 18 kgf/mm ² or more, 20 kgf/mm ² or more, 21 kgf/mm ² or more, or 22 kgf/mm ^{2 or} more, but is not limited thereto.

The polyamide-imide film has an elongation of 15% or more. Specifically, the elongation may be 16% or more, 17% or more, or 17.5% or more, but is not limited thereto.

The polyamide-imide film according to the exemplary embodiment may secure excellent optical properties such as low haze, low yellowness (YI), and high transmittance, as well as excellent mechanical properties such as excellent folding properties and high modulus. Accordingly, long-term stable mechanical and optical properties can be implemented for a substrate that requires flexibility and transparency in terms of modulus, elongation, tensile properties, and elastic restoring force.

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

The above-described characteristics for the constituents and physical properties of the polyamide-imide film may be combined with each other.

In addition, the above-described physical properties of the polyamide-imide film, together with the chemical and physical properties of the components constituting the polyamide-imide film, process conditions of each step in the method for producing the polyamide-imide film to be described later It is the result of the aggregation of

display front panel

A display front panel according to an exemplary embodiment includes a polyamide-imide film and a functional layer.

The polyamide-imide film includes a polyamide-imide polymer and a filler, and the FH value of Equation 1 is 0.5 or less.

A detailed description of the polyamide-imide film is the same as described above.

The display front plate has excellent optical properties due to low haze and high transmittance, excellent flexural properties, high modulus and hardness, high scratch resistance, and excellent slip properties, resulting in defects during winding and unwinding Since this is small, it can be usefully applied to a display device.

display device

A display device according to an exemplary embodiment includes a display unit; and a display front plate disposed on the display unit, wherein the display front plate includes a polyamide-imide film.

The polyamide-imide film includes a polyamide-imide polymer and a filler, and the FH value of Equation 1 is 0.5 or less.

A detailed description of the polyamide-imide film and the display front panel is the same as described above.

1 is a cross-sectional view of a display device according to an exemplary embodiment.

Specifically, FIG. 1 includes a display unit 400 and a polyamide-imide film 100 and a functional layer 200 having a first surface 101 and a second surface 102 on the display unit 400 . A display device is exemplified in which a front panel 300 is disposed, and an adhesive layer 500 is disposed between the display unit 400 and the front panel 300 .

The display unit 400 may display an image, and may have a flexible characteristic.

The display unit 400 may be a display panel for displaying an image, for example, a liquid crystal display panel or an organic light emitting display panel. The organic light emitting display panel may include a front polarizing plate and an organic EL panel.

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

The organic EL panel displays an image by self-luminescence in units of pixels. The organic EL panel may include an organic EL substrate and a driving substrate. The organic EL 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 EL 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 500 may be included between the display unit 400 and the front plate 300 . The adhesive layer may be an optically transparent adhesive layer, and is not particularly limited.

The front plate 300 is disposed on the display unit 400 . The front plate may be positioned at the outermost portion of the display device according to the embodiment to protect the display unit.

The front plate 300 may include a polyamide-imide 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 polyamide-imide film.

polyamide -Manufacturing method of imide film

One embodiment provides a method for preparing a polyamide-imide film.

A method for preparing a polyamide-imide film according to an embodiment includes preparing a polyamide-imide polymer solution by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent; adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps; adding a filler dispersion in which the filler is dispersed into the polymer solution; pouring the polymer solution into a tank; manufacturing a gel sheet by extruding and casting the polymer solution in the tank and then drying; and heat-treating the gel sheet.

Referring to FIG. 2, in the method for preparing a polyamide-imide film according to an embodiment, a diamine compound, a dianhydride compound and a dicarbonyl compound are mixed simultaneously or sequentially in an organic solvent in a polymerization facility, reacting the mixture to prepare a polymer solution (S100); adding the polymer solution to a tank (S200); Purging using an inert gas (S300); Casting the polymer solution in the tank on a belt and drying it to prepare a gel-sheet (S400); Preparing a cured film by heat treatment while moving the gel-sheet (S500); cooling while moving the cured film (S600); and winding the cooled cured film using a winder (S700).

The polyamide-imide film is a film mainly composed of a polyamide-imide resin, and the polyamide-imide resin is a resin including, as structural units, an amide repeating unit and an imide repeating unit in a predetermined molar ratio.

In the method for producing the polyamide-imide film, the polymer solution for preparing the polyamide-imide resin is a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent in a polymerization facility. It is prepared by sequentially mixing and reacting the mixture (S100).

In one embodiment, the polymer solution may be prepared by simultaneously adding a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent to react.

In another embodiment, the preparing of the polymer solution includes: preparing a polyamic acid (PAA) solution by first mixing and reacting the diamine compound and the dianhydride compound in a solvent; and 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.

Alternatively, the preparing of the polymer solution may include: preparing a polyamic acid solution by first mixing and reacting the diamine compound and the dianhydride compound in a solvent; preparing a polyimide (PI) solution by dehydrating the polyamic acid solution; Secondary mixing and reaction of the dicarbonyl compound with the polyimide (PI) solution to further form an amide bond; may include. The polyimide solution is a solution containing a polymer having an imide repeating unit.

In another embodiment, the preparing of the polymer solution includes: preparing a polyamide (PA) solution by first mixing and reacting the diamine compound and the dicarbonyl compound in a solvent; Secondary mixing and reaction of the dianhydride compound with the polyamide (PA) solution to further form an imide bond; may include. The polyamide solution is a solution containing a polymer having an amide repeating unit.

The polymer solution prepared as described above may be a solution containing a polymer including at least one selected from the group consisting of polyamic acid (PAA) repeating units, polyamide (PA) repeating units, and polyimide (PI) repeating units. .

Alternatively, the polymer contained in the polymer solution is an imide repeating unit derived from the polymerization of the diamine compound and the dianhydride compound and an amide derived from the polymerization of the diamine compound and the dicarbonyl compound. Includes repeating units.

The content of the solids contained in the polymer solution may be 10% by weight to 30% by weight. Alternatively, the content of the solids included in the second polymer solution may be 15 wt% to 25 wt%, but is not limited thereto.

When the content of the solids contained in the polymer solution is within the above range, the polyamide-imide film can be effectively prepared in the extrusion and casting processes. In addition, the prepared polyamide-imide film may have excellent mechanical properties that are hardly deteriorated even under high temperature and high humidity and optical properties such as low yellowness.

In one embodiment, preparing the polymer solution may further include adding a catalyst.

In this case, the catalyst may include at least one selected from the group consisting of betapicoline, acetic anhydride, isoquinoline (IQ) and pyridine-based compounds, but is not limited thereto.

The catalyst may be added in 0.01 to 0.4 molar equivalents based on 1 mole of the polyamic acid, but is not limited thereto.

When the catalyst is added, the reaction rate may be improved, and chemical bonding between repeating unit structures or within the repeating unit structure may be improved.

In another embodiment, the method for preparing the polyamide-imide film may further include adjusting the viscosity of the polyamide-imide polymer solution. Specifically, the method for preparing the polyamide-imide film may further include adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps.

Specifically, the method for preparing a polyamide-imide film comprises the steps of (a) preparing a first polymer solution by simultaneously or sequentially mixing and reacting a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent; (b) measuring the viscosity of the first polymer solution to evaluate whether the target viscosity is reached; and (c) when the viscosity of the first polymer solution does not reach the target viscosity, preparing a second polymer solution having the target viscosity by additionally adding the dicarbonyl compound.

The target viscosity may be 250,000 cps to 450,000 cps at room temperature. Specifically, the target viscosity may be 250,000 cps to 350,000 cps or 350,000 cps to 450,000 cps at room temperature, but is not limited thereto.

In the case of the step of preparing the first polymer solution and the step of preparing the second polymer solution, the viscosity of the prepared polymer solution is different. For example, the viscosity of the second polymer solution is higher than that of the first polymer solution. or the second polymer solution has a lower viscosity than the first polymer solution.

The stirring speed when preparing the first polymer solution is different from the stirring speed when preparing the second polymer solution. For example, the stirring speed when preparing the first polymer solution is faster than the stirring speed when preparing the second polymer solution. Alternatively, the stirring speed when preparing the first polymer solution is slower than the stirring speed when preparing the second polymer solution.

In another embodiment, preparing the polymer solution may further include adjusting the pH of the polymer solution. In this step, the pH of the polymer solution may be adjusted to 4 to 7, for example, to 4.5 to 7.

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

By adjusting the pH of the polymer solution to the above range, damage to equipment can be prevented in the subsequent process, the occurrence of defects in the film prepared from the polymer solution is prevented, and desired optical properties in terms of yellowness and modulus and mechanical properties.

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

In another embodiment, preparing the polymer 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 no. Specifically, the inert gas may be nitrogen.

The molar ratio of the dianhydride compound and the dicarbonyl compound used to prepare the polymer solution may be 2:98 to 50:50. Specifically, the molar ratio of the dianhydride compound to the dicarbonyl compound is 2:98 to 45:55, 2:98 to 40:60, 2:98 to 30:70, 2:98 to 25:75, 3 :97 to 25:75, 2:98 to 20:80, 3:97 to 20:80, 2:98 to 15:85, 3:97 to 15:86, 2:98 to 25:75 or 2:98 to 15:85, but is not limited thereto.

By using the dianhydride compound and the dicarbonyl compound in such a molar ratio, mechanical properties such as anti-blocking properties, folding properties, and modulus of the polyamide-imide film prepared from the polymer solution, and optical properties such as haze and transmittance It is advantageous to achieve the desired level of physical properties.

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

In one embodiment, the organic solvent is dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP), m- It may be at least one selected from the group consisting of cresol (m-cresol), tetrahydrofuran (THF) and chloroform. The organic solvent used in the polymer solution may be dimethylacetamide (DMAc), but is not limited thereto.

After preparing a polymer solution including a polyamide-imide resin in an organic solvent as described above, a filler dispersion in which the filler is dispersed is added to the solution.

In this case, the detailed description of the filler is as described above.

Specifically, the filler may be a silica-based material.

The filler dispersion may further include a dispersant.

The dispersant serves to help the filler to be uniformly dispersed in the dispersion solution and in the polymer solution including the polyimide-based resin.

In this case, it is preferable to use a neutral-based dispersant as the dispersant.

In the filler dispersion, the content of the filler solids contained in the filler dispersion is 10% by weight to 30% by weight.

When the content of the filler included in the filler dispersion is within the above range, the filler is evenly dispersed and may be appropriately mixed with the polymer solution including the polyimide-based resin. In addition, aggregation between fillers is minimized, and when it is made into a film, foreign substances do not appear on the film surface, and optical and mechanical properties of the film can be improved together.

In addition, the filler dispersion may further include a solvent.

The solvent may be an organic solvent, and specifically, dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP) , m-cresol (m-cresol), tetrahydrofuran (tetrahydrofuran, THF) and may be at least one selected from the group consisting of chloroform. Preferably, the solvent included in the filler dispersion may be dimethylacetamide (DMAc), but is not limited thereto.

Next, after the step of preparing the polymer solution, the polymer solution is put into the tank (S200).

FIG. 3 schematically shows equipment for manufacturing the polyamide-imide film according to an embodiment. Referring to FIG. 3 , the polymer solution described above is prepared in a polymerization facility 10 , and the polymer solution thus prepared is moved and stored in a tank 20 .

At this time, after preparing the polymer solution, the step of moving the polymer solution to the tank is performed without a separate process. Specifically, the polymer 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 polymer solution, the prepared polymer solution is purified through a separate process to remove impurities, and a process of re-dissolving it in a solvent was performed. . However, in this case, there is a problem in that the loss of the active ingredient increases in the process of removing the impurities, and as a result, 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 polymer solution, or even if predetermined impurities are present, they are appropriately controlled in a subsequent process so as not to deteriorate the physical properties of the final film. It has the advantage of producing a film without a separate precipitation or re-dissolution process.

The tank 20 is a place for storing the polymer solution before filming, and the internal temperature thereof may be -20°C to 20°C.

Specifically, the internal temperature may be -20°C to 10°C, -20°C to 5°C, -20°C to 0°C, or 0°C to 10°C, but is not limited thereto.

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

The method for producing the polyamide-imide film may further include performing vacuum defoaming on the polymer 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 to 0.1 bar to 0.7 bar. By performing vacuum defoaming under these conditions, bubbles inside the polymer solution can be reduced, and as a result, surface defects of the film prepared therefrom can be prevented, and optical properties such as haze can be excellently implemented.

In addition, the method of manufacturing the polyamide-imide film may further include purging the polymer solution moved to the tank 20 using an inert gas (S300).

Specifically, the purging is performed by purging the internal pressure of the tank to 1 to 2 atmospheres using an inert gas. By performing nitrogen purging under these conditions, moisture in the polymer 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 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 no. Specifically, the inert gas may be nitrogen.

The vacuum defoaming step and the step of purging the tank using an inert gas are performed as separate processes.

For example, the vacuum defoaming step may be performed, and thereafter, the step of purging the tank with an inert gas may be performed, but is not limited thereto.

By performing the vacuum defoaming step and/or purging the tank using an inert gas, the physical properties of the surface of the prepared polyamide-imide film may be improved.

Thereafter, the method may further include storing the polymer solution in the tank 20 for 1 hour to 360 hours. At this time, the internal temperature of the tank may be continuously maintained at -20 °C to 20 °C.

The method for producing the polyamide-imide film further includes extruding and casting the polymer solution in the tank 20 and drying it to prepare a gel-sheet (S400).

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

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

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

In addition, the casting thickness of the polymer solution may be 200㎛ to 700㎛. When the polymer solution is cast to the above thickness range and dried and heat treated to form a final film, appropriate thickness and thickness uniformity can be ensured.

As described above, the polymer solution may be 100,000 cps to 500,000 cps at room temperature, for example, 100,000 cps to 400,000 cps, 100,000 cps to 350,000 cps, 150,000 cps to 350,000 cps or It may be 150,000 cps to 250,000 cps. By satisfying the above viscosity range, the polymer solution can be cast to a uniform thickness without defects when cast on a belt.

After casting the polymer solution, it is dried at a temperature of 80° C. to 150° C. to prepare a gel-sheet. Specifically, the drying temperature may be 100°C to 150°C, 100°C to 135°C, or 125°C to 135°C, but is not limited thereto.

Specifically, after casting the polymer solution, it is dried at the drying temperature for 5 to 60 minutes to prepare a gel-sheet. During the drying, a part or all of the solvent of the polymer solution is volatilized to prepare the gel-sheet.

In the polyamide-imide manufacturing method, the VT value according to the following Equation 2 is 160 or more:

+

<Equation 2> VT =

+

In Equation 2, the PV is the adjusted viscosity (cps) of the polymer solution, and the DT is the drying temperature (°C).

Specifically, the VT value may be 160 or more, 170 or more, 180 or more, 185 or more, 160 to 200, 170 to 200, 180 to 200, or 185 to 200, but is not limited thereto.

The above-described physical properties of the polyamide-imide film are a result of the synthesis of the components, contents, and process conditions of each step in the film manufacturing method, which constitute the polyamide-imide film, and are polyamide-imide according to the embodiment. In order to secure excellent mechanical and optical properties of the film, the VT value, which is a parameter related to the viscosity and drying temperature of the polymer solution, is preferably 160 or more.

By adjusting the viscosity and drying temperature of the polymer solution during the preparation of the polyamide-imide film to bring the VT value within the above range, advantageous effects such as anti-blocking properties and improved slip properties due to filler injection can be achieved without increasing haze. have.

Specifically, when the VT value is less than the above range, a film with increased haze and yellowness may be prepared due to the nucleating action of the filler used, and a foreign body feeling may be seen on the film appearance, making it unsuitable for application in a later process.

The moving speed of the gel-sheet on the casting body during drying may be 0.1 m/min to 15 m/min, for example, 0.5 m/min to 10 m/min, but is not limited thereto.

The method of manufacturing the polyamide-imide film includes the step of preparing a cured film by heat treatment while moving the gel-sheet (S500).

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

The heat treatment of the gel-sheet is performed in a range of 80° C. to 500° C. for 5 minutes to 180 minutes. Specifically, the heat treatment of the gel-sheet may be performed for 5 minutes to 150 minutes while raising the temperature at a rate of 2°C/min to 80°C/min in the range of 80°C to 500°C.

According to one embodiment, the gel-sheet may be treated with hot air.

When the heat treatment by hot air is performed, the amount of heat may be uniformly provided. If the amount of heat is not evenly distributed, satisfactory mechanical properties cannot be achieved. In particular, a satisfactory surface roughness cannot be realized, and in this case, the surface tension may be too high or too low.

According to one embodiment, the heat treatment of the gel-sheet may be performed in two or more steps.

According to another embodiment, the heat treatment may be performed until the content of the residual solvent included in the film is 1,000 ppm or less.

Specifically, the heat treatment is a first heat treatment step performed for 5 minutes to 30 minutes in the range of 60 ℃ to 120 ℃; and a second heat treatment step performed in the range of 150° C. to 350° C. for 30 minutes to 120 minutes.

In the heat treatment, the second heat treatment step is performed after the first heat treatment step. At this time, when the content of the organic solvent contained in the gel-sheet exceeds 1,000 ppm after performing the second heat treatment step, a third heat treatment step may be additionally performed.

For example, the third heat treatment step may be performed in a range of 200° C. to 350° C. until the content of the organic solvent included in the gel-sheet becomes 1,000 ppm or less.

In addition, in the heat treatment step, the gel-sheet may be stretched 1.01 times to 1.05 times in the MD direction. Between the first heat treatment step and the second heat treatment step, the gel-sheet may be stretched 1.01 times to 1.05 times in the MD direction.

In the heat treatment step, the gel-sheet may be stretched 1.01 times to 1.05 times in the TD direction. In the second heat treatment step, the gel-sheet may be stretched 1.01 times to 1.05 times in the MD direction.

The gel-sheet may be stretched 1.01 times to 1.05 times simultaneously in the MD direction and the TD direction. The gel-sheet may be stretched 1.01 times to 1.05 times in the MD direction, and sequentially stretched 1.01 times to 1.05 times in the TD direction.

By heat treatment under these conditions, the gel-sheet may be cured to have an appropriate surface hardness and modulus, and the prepared cured film may secure excellent folding properties and optical properties and excellent mechanical properties even under high temperature and high humidity.

The method for producing the polyamide-imide film includes cooling while moving the cured film (S600).

3, the cured film is performed after passing through the thermosetting machine 40, and 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 1000° C./min; and a second temperature reduction step of reducing the temperature at a rate of 40° C./min to 400° C./min.

In detail, 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 is faster than the maximum speed during the second temperature reduction step. Alternatively, the lowest speed during the first temperature reduction step is faster than the lowest 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 established in the curing process can be stably maintained for a long period of time.

The moving speed of the gel-sheet and the cured film is the same.

The method of manufacturing the polyamide-imide film includes winding the cooled cured film using a winder (S700).

Referring to FIG. 3 , a roll-type winder 50 may be used to wind the cooled cured film.

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. Specifically, the ratio of the moving speed may be 1:0.99 to 1:1.20, 1:0.99 to 1:1.10, or 1:1.0 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 fear that flexibility and elastic properties may be deteriorated.

In the manufacturing method of the polyamide-imide film, the thickness deviation (%) according to the following general formula 1 may be 3% to 30%. Specifically, the thickness deviation (%) may be 5% to 20%, but is not limited thereto.

<General formula 1> Thickness deviation (%) = {(M1-M2)/M1} X 100

In Formula 1, M1 is the thickness (μm) of the gel-sheet, and M2 is the thickness (μm) of the cured film cooled during winding.

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

The description of the polyamide-imide film prepared according to the above-described manufacturing method is the same as described above.

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

< Example >

Example One

In a double-jacketed 1L glass reactor with temperature control, 585.68 g of dimethylacetamide (DMAc), an organic solvent, was filled under a nitrogen atmosphere at 20°C, and then 2,2'-bis(trifluoromethyl)-4,4' -Diaminobiphenyl (TFMB) was slowly added and dissolved. Then, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was slowly added and stirred for 1 hour. Then, isophthaloyl chloride (IPC) was added and stirred for 1 hour, terephthaloyl chloride (TPC) was added and stirred for 1 hour to prepare a polymer solution. Thereafter, a 10 wt% dicarbonyl compound solution (TPC solution, solvent DMAc) was added and stirred until the polymer solution had a viscosity of 250,000 cps. Then, a solution in which silica particles are dispersed was added to the polymer solution whose viscosity was adjusted, and the mixture was stirred. At this time, the content of the injected silica (average particle diameter of 80 nm to 100 nm) was 500 ppm based on the total weight of the polymer solid content.

The polymer solution thus prepared was put into a tank, the polymer solution in the tank was applied to a glass plate, and then dried with hot air at about 135° C. for 20 minutes to prepare a gel-sheet. After peeling the gel-sheet from the glass plate, it was fixed to a pin frame. After heat treatment of the fixed gel-sheet at about 270° C. for 30 minutes, a polyamide-imide film having a thickness of 50 μm was obtained.

With respect to the contents of TFMB, 6FDA, TPC and IPC, the number of moles of the dianhydride compound and the dicarbonyl compound based on 100 moles of the diamine compound is shown in Table 1.

Example 2, 3 and comparative example 1 to 5

As shown in Table 1 below, a film was prepared in the same manner as in Example 1, except that the type and content of each reactant, the viscosity of the polymer solution, and the drying temperature were changed.

< evaluation example >

The films prepared in Examples 1 to 3 and Comparative Examples 1 to 5 were measured and evaluated for the following physical properties, and the results are shown in Table 1 below.

evaluation example 1: Measuring the thickness of the film

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.

evaluation example 2: Measurement of the viscosity of the polymer solution

The viscosity of the polymer solution was measured using TOKI SANGYO's BH Ⅱ equipment.

evaluation example 3: transmittance and haze measurement

Light transmittance and haze at 550 nm were measured using a haze meter NDH-5000W of Denshoku Kogyo, Japan.

evaluation example 4: Yellowness measurement

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

evaluation example 5: modulus measurement

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 installed at a speed of 5 mm/min at room temperature. A stress-strain curve was obtained until fracture occurred while stretching. In the stress-strain curve, the slope of the load with respect to the initial strain was defined as the modulus (GPa).

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 diamine TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 dianhydride 6FDA 3 6FDA 3 6FDA 3 6FDA 3 - 6FDA 52 6FDA 3 6FDA 3 dicarbonyl compound TPC 72 TPC 72 TPC 72 TPC 72 TPC 100 TPC 48 TPC 72 TPC 72 IPC 25 IPC 25 IPC 25 BPDC 25 - - IPC 25 IPC 25 imide molby 3 3 3 3 0 52 3 3 amide molarby 97 97 97 97 100 48 97 97 Additive type silica silica silica silica silica silica silica silica Additive content (FC)
(ppm) 500 500 500 500 500 500 500 500 Transmittance (%) 88.7 88.9 89.2 88.1 87.4 89.0 87.7 87.8 Haze (HZ)
(%) 0.9 0.6 0.4 1.2 2.8 0.7 2.2 2.3 yellowness 2.8 2.5 2.4 3.5 8.2 2.6 6.3 6.6 modulus
(GPa) 7.2 7.0 7.1 6.9 5.2 4.3 7.1 7.0 FH value 0.225 0.15 0.1 0.3 0.7 0.175 0.55 0.575 viscosity of polymer solution 250,000 350,000 450,000 250,000 250,000 250,000 150,000 450,000 drying temperature 135 125 100 125 125 125 105 60 VT value 185 195 190 175 175 175 135 150

As can be seen in Table 1, the polyamide-imide films of Examples 1 to 3 had lower haze and yellowness and excellent modulus compared to the films of Comparative Examples 1 to 5, so that overall mechanical and optical properties were improved. Excellent was confirmed.

In particular, in the case of the polyamide-imide films of Examples 1 to 3, the FH value related to the filler content and haze satisfies 0.5 or less, and the viscosity of the polymer solution and the drying temperature are related to the polyamide-imide film production. Since the VT value satisfies 160 or more, not only the anti-blocking property is excellent, but also both the mechanical and optical properties are excellent.

On the other hand, in the case of Comparative Example 1, two kinds of dicarbonyl compounds used in the preparation of the polymer were not structural isomers, and the optical properties were lowered due to high haze and yellowness. In Comparative Example 2, when the amide repeating unit was 100% and the FH value was high, it was confirmed that the haze and yellowness were remarkably high, making it unsuitable for use in a display front panel and a display device. In Comparative Example 3, there were more imide repeating units than amide repeating units included in the polymer, and mechanical properties such as modulus were somewhat lower. In addition, in the case of Comparative Examples 4 and 5, the FH values were 0.55 and 0.575, respectively, exceeding 0.5, and the VT value was less than 160, and the optical properties were remarkably deteriorated as they exhibited haze of 2 or more and yellowness of 6 or more.

10: polymerization plant 20: tank
30: belt 40: thermosetting machine
50 : winder
100: polyamide-imide film
101: first surface 102: second surface
200: functional layer 300: front panel
400: display unit 500: adhesive layer

Claims (14)

a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and an aromatic dicarbonyl compound; and a filler;
The aromatic dicarbonyl compound includes a first aromatic dicarbonyl compound and a second aromatic dicarbonyl compound,
The first aromatic dicarbonyl compound and the second aromatic dicarbonyl compound have a structural isomer relationship with each other,
The FH value of Equation 1 below is 0.5 or less,
A polyamide-imide film having a residual solvent content of 900 ppm or less.
<Formula 1> FH =

X

In Equation 1, FC is the filler content (ppm) based on the total weight of the polymer solids, and HZ is the haze (%) of the film.
According to claim 1,
wherein the FH value is less than 0.3.
According to claim 1,
wherein the filler is a silica-based material.
According to claim 1,
The average particle diameter of the filler is 70 nm to 120 nm, polyamide-imide film.
According to claim 1,
The polyamide-imide film, wherein the content of the filler based on the total weight of the polymer solids is 300 ppm to 2,000 ppm.
According to claim 1,
The first aromatic dicarbonyl compound is a compound in which two carbonyl groups are at the m-position,
wherein the second aromatic dicarbonyl compound is a compound in which two carbonyl groups are at the p-position.
According to claim 1,
The molar ratio of the aromatic dianhydride compound and the aromatic dicarbonyl compound is 2:98 to 50:50, a polyamide-imide film.
According to claim 1,
The transmittance is 80% or more,
haze is less than 1%,
yellowness of 3 or less,
A polyamide-imide film having a modulus of at least 5 GPa.
A polyamide-imide film and a functional layer,
The polyamide-imide film comprises a polyamide-imide polymer and a filler formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and an aromatic dicarbonyl compound,
The aromatic dicarbonyl compound includes a first aromatic dicarbonyl compound and a second aromatic dicarbonyl compound,
The first aromatic dicarbonyl compound and the second aromatic dicarbonyl compound have a structural isomer relationship with each other,
The FH value of Equation 1 below is 0.5 or less,
The display front panel, wherein the content of residual solvent is 900 ppm or less.
<Formula 1> FH =

X

In Equation 1, FC is the filler content (ppm) based on the total weight of the polymer solids, and HZ is the haze (%) of the film.
display unit; and
and a display front plate disposed on the display unit;
The display front plate comprises a polyamide-imide film,
The polyamide-imide film comprises a polyamide-imide polymer and a filler formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and an aromatic dicarbonyl compound,
The aromatic dicarbonyl compound includes a first aromatic dicarbonyl compound and a second aromatic dicarbonyl compound,
The first aromatic dicarbonyl compound and the second aromatic dicarbonyl compound have a structural isomer relationship with each other,
The FH value of Equation 1 below is 0.5 or less,
The display device, wherein the content of the residual solvent is 900 ppm or less.
<Formula 1> FH =

X

In Equation 1, FC is the filler content (ppm) based on the total weight of the polymer solids, and HZ is the haze (%) of the film.
preparing a polyamide-imide polymer solution by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and an aromatic dicarbonyl compound in an organic solvent;
adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps;
adding a filler dispersion in which the filler is dispersed into the polymer solution;
pouring the polymer solution into a tank;
manufacturing a gel sheet by extruding and casting the polymer solution in the tank and then drying; and
Including; heat-treating the gel sheet.
The method for producing the polyamide-imide film of claim 1.
12. The method of claim 11,
The drying temperature is 80 ℃ to 150 ℃, polyamide-method for producing an imide film.
12. The method of claim 11,
A method for producing a polyamide-imide film, wherein the VT value of Equation 2 is 160 or more.
<Equation 2> VT =

+

In Equation 2, the PV is the adjusted viscosity (cps) of the polymer solution, and the DT is the drying temperature (°C).
12. The method of claim 11,
A method for producing a polyamide-imide film in which the filler is a silica-based material.

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