KR20210001860A - Polyamide-imide film, preparation method thereof, and display front plate and display device comprising same - Google Patents

Abstract

The present invention relates to a polyamide-imide film which maintains clean appearance and transparency as well as excellent anti-blocking properties, to a production method thereof, and to a display front plate and display device comprising the same, wherein the polyamide-imide film comprises: a polyamide-imide polymer formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound; and a filler, the dicarbonyl compound comprises: a first dicarbonyl compound; and a second dicarbonyl compound, the first dicarbonyl compound and the second dicarbonyl compound have a structural isomer relationship with each other, and the FH value of equation 1 is 0.5 or less.

Description

Polyamide-imide film, a manufacturing method thereof, and a display front plate and display device including the same TECHNICAL FIELD [0002] POLYAMIDE-IMIDE FILM, PREPARATION METHOD THEREOF, AND DISPLAY FRONT PLATE AND DISPLAY DEVICE COMPRISING SAME}

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

Polyimide resins such as poly(amide-imide), PAI) have excellent friction, heat, and chemical resistance, and are 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 such as metal or magnet wire, and is mixed with other additives depending on the application. In addition, polyimide is used as a paint for decoration and corrosion prevention along with fluoropolymers, and plays a role in bonding fluoropolymers to metal substrates. In addition, polyimide is also used to coat kitchen utensils, and because of its heat resistance and chemical resistance, it is also used as a membrane for gas separation, and a filtering device for contaminants such as carbon dioxide, hydrogen sulfide and impurities in natural gas wells. Also used for

In recent years, by forming a film of polyamide-imide, a polyamide-imide-based film has been developed that is cheaper and has excellent optical, mechanical and thermal properties. 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 a retardation film.

Such a polyamide-imide-based film should smoothly run on the interface with a high-hardness guide roll that goes through the production process so that defects such as scratches do not occur and smooth winding is performed.

Existing polyamide-imide-based films have added additives to realize anti-blocking properties, but the additives used in the polymer with a high amide content in the film act as nuclei, causing particles to aggregate or precipitate on the film surface, resulting in haze. , There was a problem that the yellowness was increased or the film appearance became poor.

Accordingly, research on the development of a film having a clean appearance and excellent anti-blocking properties without deteriorating optical properties 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 method for manufacturing the same, and a display front plate 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 are in a structural isomer relationship with each other. , The FH value of the following formula 1 is 0.5 or less.

X

<Equation 1> FH =

X

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

The 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 Formula 1 is 0.5 Below.

A display device according to another 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, The FH value in Equation 1 is less than 0.5.

A method of preparing a polyamide-imide film according to an embodiment includes the steps of polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent to prepare a polyamide-imide polymer solution; Adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps; Adding a filler dispersion in which a filler is dispersed in the polymer solution; Injecting the polymer solution into a tank; Extruding and casting the polymer solution in the tank, followed by drying, to prepare a gel sheet; 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 less defects such as scratches, exhibits excellent flexural properties, and has excellent haze and transmittance, so that it is easy to apply to a display front panel and a display device.

When preparing a polyamide-imide film according to an embodiment, by controlling the viscosity and drying temperature of the polymer solution, advantageous effects due to filler injection may be achieved 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 of manufacturing a polyamide-imide film according to an embodiment.
3 schematically shows a process equipment of 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 implement them. However, the implementation may be implemented in a variety of different forms and is not limited to the implementation described herein.

In the case where each film, window, panel, or layer, etc., is described as being formed "on" or "under" of each film, window, panel, or layer, the "top (on)" and "under" include both "directly" or "indirectly" formed. In addition, standards for the top/bottom of each component will be described based on the drawings. The size of each component in the drawings may be exaggerated for the sake of explanation, and does not mean a size that is actually applied. In addition, the same reference numerals refer to the same elements throughout the specification.

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, the singular expression is interpreted as meaning including the singular or plural, interpreted in context, unless otherwise specified.

In addition, all numbers and expressions representing amounts of components, reaction conditions, and the like described in the present specification are to be understood as being modified by the term "about" in all cases unless otherwise specified.

In the present specification, terms such as first and second 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 into another component.

In addition, "substituted" in the present specification means deuterium, -F, -Cl, -Br, -I, hydroxyl group, cyano group, nitro group, amino group, amidino group, hydrazine group, unless otherwise specified, Hydrazone group, 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 oil It means substituted with one or more substituents selected from the group consisting of a device, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted aryl group, and a substituted or unsubstituted heteroaryl group, and the substituents listed above are connected to each other Can form a ring.

Polyamide -Imide film

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

The polyamide-imide film according to one 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 isomerism relationship with each other.

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

X

<Equation 1> FH =

X

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

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

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 by using a correlation between the content of the filler and the haze of the film used as variables.

In general, when the content of the filler is increased, defects such as scratches decrease as the slip property improves, while the haze increases, resulting in a phenomenon in which 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 properties described above are deteriorated.

Therefore, it is easy to apply the film to a display front panel and a display device only when both the mechanical and optical properties are achieved by lowering the haze while increasing the filler content.

In the polyamide-imide film according to the embodiment, when the FH value, which is a parameter value used as a variable in the content of the filler and the haze, is within the above range, the take-up property when wound in a roll shape and the running property in the production process As it is excellent, it does not cause defects such as scratches or wrinkles. In addition, by implementing a film having excellent transmittance, haze, and yellowness, and having a high modulus, it is advantageous for application to a front panel of a display and a display device. 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, a lumping phenomenon may occur between the fillers and a foreign body sensation may appear on the film surface.

The type of 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 has a UV absorber having a UV blocking function to protect the interior 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 aesthetic feeling of the film. It may be a pigment or the like, 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, based on the total weight of the polyamide-imide polymer or It may be 500 to 800 ppm, but is not limited thereto.

In the case of a film in which the particle diameter and content of the filler satisfy the above range, the anti-blocking property is excellent, and thus 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, scratches and wrinkles are less generated during winding and unwinding, making it easy to apply to a display front panel and a display device.

If the particle diameter and content of the filler are less than the above range, an appropriate level of anti-blocking properties cannot be realized, and thus defects increase in the film, and if it exceeds the above range, a transparent and clean appearance cannot be obtained due to a sharp increase in haze and transmittance. There is a problem.

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

<Equation 3> IS = IM +

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

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

When 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 residual solvent content (RS) in the film is high and exceeds the above range, the long-term durability of the film is rapidly deteriorated. Specifically, when the imide content is too high and the amide content is relatively small, 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 produced 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 lowered, and in particular, it may affect the post-processing of the film. Specifically, when the content of the residual solvent exceeds the above range, the hydrolysis of the film may be accelerated to reduce mechanical 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 folding before fracture is 100,000 or more.

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

Since the polyamide-imide film satisfies the number of folding times in the above-described range, it can be usefully applied to a foldable display device or a flexible display device.

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 and 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 and the dicarbonyl compound is within the above range, a film having strong durability and excellent mechanical properties and optical properties can 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 B. Optical properties are rapidly deteriorated, and mechanical properties may be slightly deteriorated.

In another embodiment, the dianhydride compound may be composed of one type, and the dicarbonyl compound may be composed 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 an imide bonded to the dianhydride compound and an amide bonded to the dicarbonyl compound to form a copolymer.

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 cyclic group, a substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaliphatic cyclic group, a substituted or unsubstituted divalent C ₆ -C ₃₀ aromatic cyclic group , A substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaromatic ring group, 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 -, It may be selected from -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 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 formed of a compound having a fluorine-containing substituent. In this case, the fluorine-containing substituent may be a fluorinated hydrocarbon group, and 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, TFDB), but is not limited thereto.

Since the dianhydride compound has a low birefringence value, the dianhydride compound is a compound capable of contributing to improvement of optical properties such as transmittance of a film containing the polyimide polymer. The polyimide-based polymer means a polymer containing 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 cyclic group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaliphatic cyclic group, 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 hetero aliphatic ring group, the aromatic ring group or the heteroaromatic ring group is present alone, or , Conjugated to each other 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 -.

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 formed of a compound having a fluorine-containing substituent. In this case, the fluorine-containing substituent may be a fluorinated hydrocarbon group, and specifically, a trifluoromethyl group, but is not limited thereto.

In another embodiment, the dianhydride compound may be composed of one single component or a mixture of two components.

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

The diamine compound and the dianhydride compound may be polymerized to produce 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 Formula A below.

<Formula A>

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

For example, the polyimide may include a repeating unit represented by Formula A-1 below, 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 represented by the following formula (3).

<Formula 3>

In Chemical Formula 3,

J is a substituted or unsubstituted divalent C ₆ -C ₃₀ aliphatic cyclic group, a substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaliphatic cyclic group, a substituted or unsubstituted divalent C ₆ -C ₃₀ aromatic cyclic group , A substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaromatic ring group, 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 -, It may be selected from -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 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 of 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 of 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, the dicarbonyl compound may be used by mixing at least two different dicarbonyl compounds. When two or more types of the dicarbonyl compounds are used, two or more types of dicarbonyl compounds selected from the group represented by (J) _j in Chemical Formula 3 may be used. have.

In another embodiment, the dicarbonyl compound may be an aromatic dicarbonyl compound having 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 are not limited thereto.

When the first dicarbonyl compound and the second dicarbonyl compound are each an aromatic dicarbonyl compound, since it contains a benzene ring, the surface hardness and tensile strength of the film containing the prepared polyamide-imide resin 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 (IPC), or a combination thereof, 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, a film including the prepared 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 the present invention is not limited thereto.

When using in an appropriate combination of IPC as the first dicarbonyl compound and TPC as the second dicarbonyl compound, the prepared 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 Formula B below.

<Formula B>

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

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

<Formula B-1>

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

<Formula B-2>

Y in Formula B-2 is an integer of 1 to 400.

<Formula B-3>

Y in Formula B-3 is an integer of 1 to 400.

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

<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 cyclic group, a substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaliphatic cyclic 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 -is selected from,

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 as or different from each other,

G is a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aliphatic cyclic group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaliphatic cyclic group, a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aromatic cyclic group , A substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaromatic cyclic group, and the aliphatic cyclic group, the hetero aliphatic cyclic group, the aromatic cyclic group or the heteroaromatic cyclic group is present alone or condensed with each other 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 ) It is connected by a connector selected from ₂ -.

In the polyamide-imide polymer, the molar ratio of the repeating unit represented by Formula A and 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 may be, 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 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 haze of the polyamide-imide film is 1% or less. Specifically, the haze may be 0.9% or less, but is not limited thereto.

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

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

When perforating the polyamide-imide film in UTM compression mode at a speed of 10 mm/min using a 2.5 mm spherical tip, the maximum perforation diameter (mm) including cracks is 60 mm or less. Specifically, the maximum perforation diameter 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 higher. 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 an embodiment may secure excellent optical properties such as low haze, low yellowness (YI), and high transmittance, as well as excellent folding properties and excellent mechanical properties such as high modulus. Accordingly, in terms of modulus, elongation, tensile properties, and elastic resilience, it is possible to implement long-term stable mechanical properties and optical properties for a substrate requiring flexibility and transparency.

The physical properties of the polyamide-imide film described above 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 features of the composition and physical properties of the polyamide-imide film described above may be combined with each other.

In addition, the above-described physical properties of the polyamide-imide film are the chemical and physical properties of the components constituting the polyamide-imide film, as well as the process conditions of each step in the method of manufacturing the polyamide-imide film to be described later. Is the result of the synthesis.

display Front panel

A display front panel according to an 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 Formula 1 is 0.5 or less.

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

The front panel of the display has excellent optical properties due to low haze and high transmittance, excellent bending characteristics, high modulus and hardness, high resistance to scratches, and excellent slip properties, resulting in defects during winding and unwinding. Since there is little, it can be usefully applied to a display device.

Display device

A display device according to an 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 contains a polyamide-imide polymer and a filler, and the FH value of Formula 1 below is 0.5 or less.

Detailed descriptions of the polyamide-imide film and the front panel of the display are 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 in which the front plate 300 is disposed and the adhesive layer 500 is disposed between the display unit 400 and the front plate 300 is illustrated.

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-emission 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 each corresponding to a pixel. 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 driveably coupled to the organic EL substrate. That is, the driving substrate is coupled so as to apply a driving signal such as a driving current to the organic EL substrate, so that current is applied to each of the organic electroluminescent 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 side of the display device according to the exemplary 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 anti-glare layer. The functional layer may be coated on at least one surface of the polyamide-imide film.

Polyamide -Method of manufacturing imide film

One embodiment provides a method of manufacturing a polyamide-imide film.

A method of preparing a polyamide-imide film according to an embodiment includes the steps of polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent to prepare a polyamide-imide polymer solution; Adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps; Adding a filler dispersion in which a filler is dispersed in the polymer solution; Injecting the polymer solution into a tank; Extruding and casting the polymer solution in the tank, followed by drying, to prepare a gel sheet; And heat-treating the gel sheet.

Referring to FIG. 2, in the method of manufacturing a polyamide-imide film according to an embodiment, a diamine compound, a dianhydride compound, and a dicarbonyl compound are simultaneously or sequentially mixed in an organic solvent in a polymerization facility, Reacting the mixture to prepare a polymer solution (S100); Injecting the polymer solution into 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); Manufacturing 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 containing an amide repeating unit and an imide repeating unit as structural units in a predetermined molar ratio.

In the method of manufacturing the polyamide-imide film, the polymer solution for preparing the polyamide-imide resin is a diamine compound, a dianhydride compound, and a dicarbonyl compound simultaneously or It is prepared by sequentially mixing and reacting the mixture (S100).

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

In another embodiment, the preparing of the polymer solution may include 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 step of preparing 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; Dehydrating the polyamic acid solution to prepare a polyimide (PI) solution; And forming an amide bond by secondary mixing and reacting the dicarbonyl compound to the polyimide (PI) solution. The polyimide solution is a solution containing a polymer having an imide repeating unit.

In another embodiment, the step of preparing the polymer solution may include preparing a polyamide (PA) solution by first mixing and reacting the diamine compound and the dicarbonyl compound in a solvent; It may include a step of forming an imide bond further by secondary mixing and reacting the dianhydride compound to the polyamide (PA) solution. 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 containing at least one selected from the group consisting of polyamic acid (PAA) repeat units, polyamide (PA) repeat units, and polyimide (PI) repeat units. .

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

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

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

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

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

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

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

In another embodiment, the method of manufacturing a polyamide-imide film may further include adjusting the viscosity of the polyamide-imide polymer solution. Specifically, the method of manufacturing 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, a method of preparing a polyamide-imide film includes 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 a target viscosity is reached; And (c) preparing a second polymer solution having a target viscosity by adding the dicarbonyl compound when the viscosity of the first polymer solution does not reach the target viscosity.

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. Alternatively, the viscosity of the second polymer solution is lower than that of the first polymer solution.

The stirring speed when preparing the first polymer solution and the stirring speed when preparing the second polymer solution are different. 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, the step of 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, may be adjusted 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, it is possible to prevent damage to the equipment in the subsequent process, to prevent the occurrence of defects in the film prepared from the polymer solution, and to target optical properties in terms of yellowness and modulus. And mechanical properties.

The pH adjuster 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 one or more 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 and 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, the polyamide-imide film prepared from the polymer solution has anti-blocking properties, folding properties, mechanical properties such as modulus, 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, dianhydride compound, and dicarbonyl compound is as described above.

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

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

In this case, a 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 evenly dispersed in the polymer solution containing the polyimide resin in the dispersion.

In this case, the dispersant is preferably a neutral dispersant.

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

When the content of the filler contained in the filler dispersion is within the above range, the filler is evenly dispersed and may be appropriately mixed with a polymer solution containing a polyimide resin. In addition, agglomeration between fillers is minimized, and when produced as a film, a foreign body sensation does 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, specifically, dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (N-methyl-2-pyrrolidone, NMP) , m-cresol (m-cresol), tetrahydrofuran (tetrahydrofuran, THF) and may be one or more 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 a tank (S200).

3 is a schematic diagram of a manufacturing process equipment for the polyamide-imide film according to an embodiment. 3, the above-described polymer solution is prepared in a polymerization facility 10, and the polymer solution thus prepared is transferred and stored in a tank 20.

In this case, after preparing the polymer solution, a step of moving the polymer solution to a tank without a separate process is performed. Specifically, the polymer solution prepared in the polymerization facility is transferred to and stored in the tank as it is without a separate precipitation and re-dissolution process for removing impurities. Conventionally, in order to remove impurities such as hydrochloric acid (HCl) generated during the preparation of the polymer solution, the prepared polymer solution was 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 that the loss of the active ingredient increases in the process of removing the impurities, and as a result, the yield decreases.

Accordingly, the manufacturing method according to an embodiment minimizes the content of impurities at a source 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 to store the polymer solution before filming it, and its internal temperature 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 within the above range, it is possible to prevent the polymer solution from being deteriorated during storage, and to reduce the moisture content to prevent defects in the film produced therefrom.

The method of manufacturing the polyamide-imide film may further include performing vacuum defoaming on the polymer solution transferred 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 such conditions, air bubbles inside the polymer solution can be reduced, and as a result, surface defects of the film produced 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 transferred 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 such 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 one or more 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 degassing step may be performed, and thereafter, the step of purging the tank with an inert gas may be performed, but the present invention is not limited thereto.

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

Thereafter, it may further include storing the polymer solution in the tank 20 for 1 to 360 hours. At this time, the internal temperature of the tank may be kept at -20 ℃ to 20 ℃.

The method of manufacturing the polyamide-imide film further includes the step of preparing a gel-sheet by extruding and casting the polymer solution in the tank 20 and then drying it (S400).

The polymer solution may be cast on a casting body 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 as a gel-like sheet.

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 may 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 in the above thickness range and then dried and heat treated into a final film, an 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 between 150,000 cps and 250,000 cps. By satisfying the viscosity range, when the polymer solution is cast on a belt, it can be cast to a uniform thickness without defects.

After casting the polymer solution, the gel-sheet can be prepared by drying at a temperature of 80°C to 150°C. 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 for 5 to 60 minutes at the drying temperature to prepare a gel-sheet. During the drying, the solvent of the polymer solution is partially or completely volatilized to prepare the gel-sheet.

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

+

<Equation 2> VT =

+

In Equation 2, PV is the adjusted viscosity (cps) of the polymer solution, and 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, and the 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 higher.

When preparing the polyamide-imide film, by adjusting the viscosity and drying temperature of the polymer solution to make the VT value within the above range, advantageous effects such as improved anti-blocking properties and 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 produced due to the nucleation action of the filler used, and a foreign body sensation may be seen on the film appearance, making it unsuitable for application to a later process.

The moving speed of the gel-sheet on the casting body upon 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 manufacturing method of 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 for 5 minutes to 180 minutes in the range of 80°C to 500°C. 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 subjected to hot air treatment.

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

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 contained in the film is 1,000 ppm or less.

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

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

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

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

The gel-sheet may be simultaneously stretched 1.01 to 1.05 times 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 1.01 times to 1.05 times in the TD direction in sequence.

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

The manufacturing method of 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 can also be carried out by composition.

The step of cooling while moving the cured film may include: a first temperature reduction step of reducing temperature at a rate of 100°C/min to 1000°C/min; And a second temperature reduction step of reducing temperature at a rate of 40°C/min to 400°C/min.

In this case, specifically, the second temperature reduction step is performed after the first temperature reduction step, and the temperature reduction speed of the first temperature reduction step may be faster than the temperature reduction speed of the second temperature reduction step.

For example, a maximum speed during the first temperature reduction step is faster than a 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 properties and mechanical properties of the film established in the curing process can be more stably maintained for a long period of time.

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

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

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: the moving speed of the cured film upon 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 concern that mechanical properties of the cured film may be damaged, and flexibility and elastic properties may be deteriorated.

In the method of manufacturing 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 General 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 prepared according to the above-described manufacturing method. The polyamide-imide film may be applicable to various applications requiring slip properties and transparency. For example, the polyamide-imide film may be applied to solar cells, displays, semiconductor devices, and sensors.

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

The above will be described in more detail by the following examples. However, the following examples are for illustrative purposes only, and the scope of the examples is not limited thereto.

< Example >

Example One

2,2'-bis(trifluoromethyl)-4,4' -Diaminophenyl (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, the mixture was stirred while adding 10% by weight of a dicarbonyl compound solution (TPC solution, solvent DMAc) until the viscosity of the polymer solution reached 250,000 cps. Then, a solution in which silica particles were dispersed was added to the polymer solution whose viscosity was adjusted and stirred. At this time, the content of the added silica (average particle diameter 80 nm ~ 100 nm) was 500 ppm based on the total weight of the polymer solid content.

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

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

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 drying temperature were different.

< Evaluation example >

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

Evaluation example 1: Measuring the thickness of the film

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

Evaluation example 2: Measurement of viscosity of polymer solution

The viscosity of the polymer solution was measured using a TOKI SANGYO company BH II equipment.

Evaluation example 3: transmittance and Haze Measure

The light transmittance and haze at 550 nm were measured using a haze meter NDH-5000W manufactured by 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 Measure

Using Instron's universal testing machine UTM 5566A, cut at least 5 cm in the direction orthogonal to the main contraction direction of the sample and 10 mm in the main contraction direction, attach it to a clip at 5 cm intervals, and at room temperature at a speed of 5 mm/min. The stress-strain curve was obtained until fracture occurred while stretching to. In the stress-strain curve, the slope of the load against the initial deformation was taken 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 molar ratio 3 3 3 3 0 52 3 3 Amide molar ratio 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 have lower haze and yellowness and excellent modulus compared to the films of Comparative Examples 1 to 5, so that overall mechanical and optical properties are It was confirmed to be excellent.

In particular, in the case of the polyamide-imide films of Examples 1 to 3, the FH value related to the content of the filler and the haze satisfies 0.5 or less, and the viscosity and drying temperature of the polymer solution during the preparation of the polyamide-imide film. By satisfying the VT value of 160 or higher, not only excellent anti-blocking properties but also excellent mechanical and optical characteristics.

On the other hand, in the case of Comparative Example 1, when the two types of dicarbonyl compounds used in the preparation of the polymer were not structural isomers of each other, the optical properties were decreased due to high haze and yellowness. In the case of 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, which was inappropriate for use in a display front panel and a display device. In Comparative Example 3, there were more imide repeat units than the amide repeat units contained in the polymer, and mechanical properties such as modulus were slightly lower. In addition, in the case of Comparative Examples 4 and 5, when the FH value was 0.55 and 0.575, respectively, exceeding 0.5, and the VT value was less than 160, the optical properties were markedly deteriorated as 2 or more haze and 6 or more yellowness were displayed.

10 polymerization equipment 20 tank
30: belt 40: thermosetting machine
50: winder
100: polyamide-imide film
101: page 1 102: page 2
200: functional layer 300: front plate
400: display unit 500: adhesive layer

Claims (14)

A polyamide-imide polymer formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound; And a filler; including,
The dicarbonyl compound includes a first dicarbonyl compound and a second dicarbonyl compound,
The first dicarbonyl compound and the second dicarbonyl compound are in a structural isomer relationship with each other,
A polyamide-imide film having an FH value of 0.5 or less in Formula 1 below.
<Equation 1> FH =

X

In Equation 1, FC is a filler content (ppm) based on the total weight of the polymer solid content, and HZ means haze (%) of the film.
The method of claim 1,
The FH value is less than 0.3, a polyamide-imide film.
The method of claim 1,
The filler is a silica-based material, polyamide-imide film.
The method of claim 1,
The average particle diameter of the filler is 70 nm to 120 nm, polyamide-imide film.
The method of claim 1,
The content of the filler based on the total weight of the polymer solid content is 300 ppm to 2,000 ppm, polyamide-imide film.
The method of claim 1,
The first dicarbonyl compound is a compound in which two carbonyl groups are in the m-position,
The second dicarbonyl compound is a compound having two carbonyl groups at the p-position, a polyamide-imide film.
The method of claim 1,
A polyamide-imide film in which the molar ratio of the dianhydride compound and the dicarbonyl compound is 2:98 to 50:50.
The method of claim 1,
Transmittance is 80% or more,
Haze is less than 1%,
Yellowness is 3 or less,
Polyamide-imide film with a modulus of 5 GPa or more.
Including 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 Formula 1 below is 0.5 or less.
<Equation 1> FH =

X

In Equation 1, FC is a filler content (ppm) based on the total weight of the polymer solid content, and HZ means haze (%) of the film.
Display; And
Includes; a display front plate disposed on the display unit,
The display front panel includes a polyamide-imide film,
The display device, wherein the polyamide-imide film includes a polyamide-imide polymer and a filler, and the FH value of Formula 1 below is 0.5 or less.
<Equation 1> FH =

X

In Equation 1, FC is a filler content (ppm) based on the total weight of the polymer solid content, and HZ means haze (%) of the film.
Polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent to prepare a polyamide-imide polymer solution;
Adjusting the viscosity of the polyamide-imide polymer solution to 250,000 cps to 450,000 cps;
Adding a filler dispersion in which a filler is dispersed in the polymer solution;
Injecting the polymer solution into a tank;
Extruding and casting the polymer solution in the tank, followed by drying, to prepare a gel sheet; And
Including; heat treatment of the gel sheet;
The method for producing the polyamide-imide film of claim 1.
The method of claim 11,
The drying temperature is 80 ℃ to 150 ℃, the method of producing a polyamide-imide film.
The method of claim 11,
A method for producing a polyamide-imide film having a VT value of 160 or more in Equation 2 below.
<Equation 2> VT =

+

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

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