KR102242950B1 - Polyamide-based film, preparation method thereof, and cover window and display device comprising same - Google Patents

Abstract

The embodiment relates to a polyamide-based film that is colorless and transparent and has excellent mechanical properties and optical properties, and particularly exhibits gloss characteristics similar to glass, a method of manufacturing the same, and a cover window and a display device including the same, wherein the polyamide-based The film contains a polyamide-based polymer, and the film surface has a 20° glossiness (GL ₂₀ ) of 90 to 130, the film surface 60° glossiness (GL ₆₀ ) of 90 to 120, and The 85 degree glossiness (GL ₈₅ ) is 90-110.

Description

Polyamide-based film, a manufacturing method thereof, and a cover window and display device including the same TECHNICAL FIELD [0001]

The embodiment relates to a polyamide-based film, which is colorless and transparent, has excellent mechanical properties and optical properties, and particularly exhibits gloss characteristics similar to glass, a method of manufacturing the same, and a cover window 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 for 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. Is used.

Recently, by forming a film of polyimide, a polyimide-based film having excellent optical, mechanical, and thermal properties has been developed inexpensively. These polyimide-based film is an 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, in the implementation phase properties antireflection film, a compensation film or a retardation Applicable to film.

When the polyimide-based film is applied to a display device, the transparent cover window included in the display device includes a hard coating layer and a base film. A problem of deteriorating physical properties may occur, and since the polyimide-based film exhibits a higher level of gloss than glass, it is difficult to use it as a substitute for glass.

Therefore, while solving the above problem, while exhibiting a level of gloss similar to that of glass, research on the development of a film excellent in mechanical properties and optical properties is continuously required.

The embodiment is to provide a polyamide-based film that is colorless, transparent, has excellent mechanical and optical properties, and exhibits gloss characteristics similar to glass, a method for manufacturing the same, and a cover window and a display device including the same.

A polyamide-based film according to an embodiment includes a polyamide-based polymer, and a 20° glossiness (GL ₂₀ ) of the film surface is 90 to 130, and a 60° glossiness (GL ₆₀ ) of the film surface is 90 To 120, and 85° glossiness (GL ₈₅ ) of the film surface is 90 to 110.

A polyamide-based film according to another embodiment includes a polyamide-based polymer, and a GL _20-60 value defined in Equation 1 below is 0 to 15, or a GL _20-85 value defined in Equation 3 below is 0 to 30 to be.

<Equation 1> GL _{20- 60} = | GL ₂₀ -GL ₆₀ |

<Equation 3> GL _{20- 85} = | GL ₂₀ -GL ₈₅ |

In Equations 1 and 3, GL ₂₀ means a 20° glossiness of the film surface _{, GL 60 means a 60° glossiness of the film surface, and GL 85} means an 85° glossiness of the film surface.

The cover window for a display device according to another embodiment includes a polyamide-based film and a functional layer, the polyamide-based film includes a polyamide-based polymer, and a 20° glossiness (GL ₂₀ ) of the film surface is It is 90 to 130, the 60° glossiness (GL ₆₀ ) of the film surface is 90 to 120, and the 85° glossiness (GL ₈₅ ) of the film surface is 90 to 110.

A display device according to another embodiment includes a display unit; And a cover window disposed on the display unit, wherein the cover window includes a polyamide-based film and a functional layer, the polyamide-based film includes a polyamide-based polymer, and 20° of the film surface The glossiness (GL ₂₀ ) is 90 to 130, the 60° glossiness of the film surface (GL ₆₀ ) is 90 to 120, and the 85° glossiness (GL ₈₅ ) of the film surface is 90 to 110.

The polyamide-based film according to the embodiment is colorless and transparent, has excellent mechanical properties and optical properties. In particular, it has a gloss property similar to that of glass, and thus can be usefully applied to a cover window for a display device and a display device.

In addition, the polyamide-based film according to the embodiment has excellent folding characteristics and can be usefully applied to a foldable display device or a flexible display device.

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-based film according to an embodiment.
3 schematically shows a process equipment of a polyamide-based 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 various different forms and is not limited to the implementation described in the present specification.

In the present specification, when each film, window, panel, or layer is described as being formed in "on" or "under" of each film, window, panel, or layer, (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, which is interpreted in context, unless otherwise specified.

In addition, all numbers and expressions indicating amounts of constituents, reaction conditions, and the like described herein 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 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, 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 It can form a ring.

Polyamide type film

The embodiment provides a polyamide-based film that is colorless and transparent, has excellent mechanical properties and optical properties, and particularly exhibits gloss properties similar to glass.

The polyamide-based film according to one embodiment includes a polyamide-based polymer.

The surface of the polyamide-based film has a 20° glossiness (GL ₂₀ ) of 90 to 130.

Specifically, the 20° glossiness (GL ₂₀ ) of the surface of the polyamide-based film is 95 to 130, 90 to 125, 95 to 125, 95 to 120, 95 to 115, 95 to 110, 95 to 105 or 95 to 100 It may be, but is not limited thereto.

The surface of the polyamide-based film has a 60° glossiness (GL ₆₀ ) of 90 to 120.

Specifically, the 60° glossiness (GL ₆₀ ) of the surface of the polyamide-based film may be 95 to 120, 95 to 115, 95 to 110, 95 to 105, or 95 to 100, but is not limited thereto.

The surface of the polyamide-based film has an 85° glossiness (GL ₈₅ ) of 90 to 110.

Specifically, the 85° glossiness (GL ₈₅ ) of the surface of the polyamide-based film may be 90 to 105, 95 to 110, 95 to 105, 98 to 105, 98 to 102, 99 to 101, or 100 to 101, It is not limited thereto.

When the 20° glossiness (GL ₂₀ ), 60° glossiness (GL ₆₀ ), and 85° glossiness (GL ₈₅ ) of the polyamide-based film surface are in the above ranges, the bar has gloss characteristics similar to glass and It is possible to realize an aesthetic that looks similar. In addition, there is an effect of improving the visibility of the display compared to the existing film. In addition, it can secure light weight compared to glass.

In particular, when the 60° glossiness (GL ₆₀ ) of the surface of the polyamide-based film is in the above range, the angle corresponds to a particularly important physical property in that it is an angle that is generally visually recognized by humans, and 60° glossiness The (GL ₆₀ ) value exhibits a gloss characteristic similar to that of glass, thereby exhibiting an aesthetic similar to that of glass, and improving the visibility of the display.

When the surface of the polyamide-based film _{is out of the above ranges with 20° glossiness (GL 20} ), 60° glossiness (GL ₆₀ ), and 85° glossiness (GL ₈₅ ), it looks similar to the existing film and deteriorates aesthetics. There is a problem in that visibility is poor due to light reflection from the display.

_{The GL 20-60} value defined in the following formula 1 of the polyamide-based film is 0 to 15.

<Equation 1> GL _{20- 60} = | GL ₂₀ -GL ₆₀ |

In Equation 1, GL ₂₀ means a 20° glossiness _{of the film surface, and GL 60} means a 60° glossiness of the film surface.

_{Specifically, the GL 20-60} value of the polyamide-based film is 0 to 10, 0 to 9, 0 to 8, 0 to 7, 0 to 6, 0 to 5, 0 to 3, 0 to 2, 0 to 1 Alternatively, it may be 0.5 to 1, but is not limited thereto.

_{The GL 60-85} value defined in Equation 2 below of the polyamide-based film is 0 to 15.

<Equation 2> GL _{60- 85} = | GL ₆₀ -GL ₈₅ |

In Equation 2, GL ₆₀ means the 60° glossiness _{of the film surface, and GL 85} means the 85° glossiness of the film surface.

_{Specifically, the GL 60-85} value of the polyamide-based film is 0 to 13, 0 to 12, 0 to 11, 0 to 10, 0 to 9, 0 to 8, 0 to 7, 0 to 6, 0 to 5 , 0 to 4, 0 to 3, 0.5 to 3, 1 to 3, or may be 1 to 2.5, but is not limited thereto.

The polyamide-based film has a GL _20-85 value of 0 to 30 as defined in Equation 3 below.

<Equation 3> GL _{20- 85} = | GL ₂₀ -GL ₈₅ |

In Equation 3, GL ₂₀ means a 20° glossiness _{of the film surface, and GL 85} means an 85° glossiness of the film surface.

_{Specifically, the GL 20-85} value of the polyamide-based film is 0 to 25, 0 to 23, 0 to 22, 0 to 20, 0 to 18, 0 to 15, 1 to 15, 1 to 12, 1 to 10 , 1 to 8, 1 to 6, 1 to 5, 1 to 3, or may be 2 to 3, but is not limited thereto.

_{The GL max /min} value defined in Equation 3 below of the polyamide-based film is 80% to 100%.

<Equation 4> GL _{max /min} (%)= (GL _min / GL _max ) X 100

In Equation 4, GL _max means the highest glossiness among _{GL 20} , GL ₆₀ and GL _{85 , and GL min} means the lowest glossiness among GL ₂₀ , GL ₆₀ and GL _85.

_{Specifically, the GL max /min} value of the polyamide-based film is 85% to 100%, 88% to 100%, 90% to 100%, 92% to 100%, 93% to 100%, 94% to 100% , 95% to 100%, 90% to 98%, 95% to 98%, 96% to 98%, or 97% to 98%, but is not limited thereto.

_{When the GL 20-60} value, GL _60-85 value, GL _20-85 value, and GL _{max /min} value of the polyamide-based film surface are in the above ranges, the difference in glossiness is not large depending on the angle, and the cover window and When applied to a display device, there is an effect of increasing the visibility of the display. In addition, since it has gloss characteristics similar to glass, it is possible to realize an aesthetic feeling that looks similar to glass.

The content of residual solvent in the polyamide-based film is 1,500 ppm or less. For example, the content of the residual solvent may be 1,200 ppm or less, 1,000 ppm or less, 800 ppm or less, or 500 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 film production.

When the content of the residual solvent in the polyamide-based film exceeds the above range, the durability of the film may be deteriorated and glossiness may also be affected.

In addition, the IS value represented by the following formula 5 of the polyamide-based film is 10 to 200.

<Equation 5> IS = IM +

In Equation 5, 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 10 to 150, 10 to 120, or 10 to 60, but is not limited thereto.

Since the IS value of the polyamide-based film satisfies the above range, it is possible to implement a film having excellent durability, excellent folding characteristics, and a gloss level similar to that of glass even under severe conditions.

When the polyamide-based film according to the embodiment is folded to have a radius of curvature of 3 mm based on a thickness of 50 μm, the number of folding before fracture is 200,000 or more.

The number of times of folding is one that is bent and unfolded so that the radius of curvature of the film is 3 mm.

Since the polyamide-based 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 surface roughness of the polyamide-based film according to the embodiment is 0.01 µm to 0.07 µm. Specifically, the surface roughness may be 0.01 µm to 0.07 µm or 0.01 µm to 0.06 µm, but is not limited thereto.

When the polyamide-based surface roughness satisfies the above range, a film having a gloss similar to that of glass can be implemented, and by reducing reflection of the display, there is an effect of increasing visibility.

The polyamide-based film according to an embodiment includes a polyamide-based polymer, and the polyamide-based polymer is a polymer including an amide repeating unit. In addition, the polymer included in the film may optionally contain an imide repeating unit.

The polyamide-based film includes a polyamide-based polymer, and the polyamide-based polymer may be formed by reacting reactants including a diamine compound and a dicarbonyl compound simultaneously or sequentially. Specifically, the polyamide-based polymer is formed by polymerization of a diamine compound and a dicarbonyl compound.

Alternatively, the polyamide-based polymer may be formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound. At this time, the polyamide-based 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 polyamide-based film according to an embodiment includes a polyamide-based polymer formed by polymerizing a diamine compound, a dicarbonyl compound, and optionally a dianhydride compound.

In one embodiment, the molar ratio of the dianhydride compound and the dicarbonyl compound is 0:100 to 50:50, 0:100 to 45:55, 0:100 to 30:70, 0:100 to 25:75 Or 0:100 to 20:80.

When the molar ratio of the dianhydride compound and the dicarbonyl compound is within the above range, a film having similar gloss characteristics to glass may be exhibited, and a film having excellent folding characteristics may be implemented.

In another embodiment, the dianhydride compound may be composed of 0 types, 1 type, or 2 types, and the dicarbonyl compound may be composed of 1 type or 2 types.

The diamine compound is a compound which is imide-bonded with the dianhydride compound and amide-bonded with 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, -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 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 '-diaminobiphenyl, TFDB), but is not limited thereto.

Since the dianhydride compound has a low birefringence value, the dianhydride compound is a compound that can contribute to improvement of optical properties such as transmittance of a film containing the polyimide polymer. The polyimide polymer refers to 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 cyclic group, 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 , 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 the following formula (A).

<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>

N in Formula A-1 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 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 as or different from each other.

X is a halogen atom. Specifically, X may be F, Cl, Br, I, and 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 they contain a benzene ring, such as the surface hardness and tensile strength of the film containing the prepared polyamide-based polymer It can contribute to improving mechanical properties.

The dicarbonyl compound is terephthaloyl chloride (TPC) having the following structure, 1,1'-biphenyl-4,4'-dicarbonyl dichloride (1,1'-biphenyl-4 , 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-based 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 using in an appropriate combination of IPC as the first dicarbonyl compound and TPC as the second dicarbonyl compound, the film containing the prepared polyamide-based resin can have high oxidation resistance as well as cost reduction. It is economical to be able to do it.

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-based polymer may include a repeating unit represented by the following formula (A) and a repeating unit represented by the following 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 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 as 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 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 is 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 ) It is connected by a connector selected from _{2 -.}

In the polyamide-based polymer, the molar ratio of the repeating unit represented by Formula A and the repeating unit represented by Formula B is 0:100 to 50:50, 0:100 to 45:55, 0:100 to 30: It may be 70, 0:100 to 25:75, or 0:100 to 20:80, 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, a film exhibiting similar gloss properties as glass, having excellent folding properties, and excellent mechanical properties and optical properties Can be implemented.

According to another embodiment, the polyamide-based film may further include a matting agent.

The matting agent may be one or more selected from the group consisting of silica, poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), polystyrene (PS), melamine, silicon, and glass.

The average particle diameter of the matting agent may be 10 nm to 1,000 nm. For example, the average particle diameter of the matting agent may be 50 nm to 800 nm, 50 nm to 500 nm, 50 nm to 300 nm, 50 nm to 200 nm, 70 nm to 180 nm, or 100 nm to 150 nm, It is not limited thereto.

When the polyamide-based film includes the matting agent, a film having a gloss level similar to that of glass may be realized by lowering gloss. In addition, it is possible to improve the surface roughness and winding properties to improve the effect of improving the running scratches during film production, and it is possible to realize an aesthetic feeling that looks similar to glass. Furthermore, there is an effect of increasing visibility by reducing reflection of the display.

The polyamide-based film may contain the matting agent in an amount of 100 to 3000 ppm or 200 to 1000 ppm based on the total weight of the polyamide-based polymer.

When the content of the matting agent contained in the film exceeds the above range, the matting agent is precipitated on the film surface and thus cannot be used for subsequent processes, or the haze of the film increases, resulting in significant deterioration in optical properties.

The haze of the polyamide-based film is 1% or less. For example, the haze may be 0.8% or less, 0.6% or less, 0.5% or less, or 0.4% or less, but is not limited thereto.

The transmittance of the polyamide-based film is 80% or more. For example, the transmittance may be 82% or more, 85% or more, 88% or more, 89% or more, 80% to 99%, 88% to 99%, or 89% to 99%, but is not limited thereto. .

The yellow index of the polyamide-based film is 5 or less. For example, the yellowness may be 4 or less, 3.5 or less, or 3 or less, but is not limited thereto.

The modulus of the polyamide-based 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, 7.0 GPa or more, but is not limited thereto.

The compressive strength of the polyamide-based 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-based 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-based 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-based 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-based 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-based film according to the embodiment has excellent optical properties such as low haze, low yellowness, and high transmittance, as well as gloss characteristics similar to glass, and can secure excellent folding characteristics. As a result, there is an effect of increasing the aesthetics and visibility of the display.

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

Features of the composition and physical properties of the polyamide-based film described above may be combined with each other.

For example, the polyamide-based film contains a polyamide-based polymer, and the 20° glossiness (GL ₂₀ ) of the film surface is 90 to 130, and the 60° glossiness (GL ₆₀ ) of the film surface is 90 to 120 And, the film surface has an 85° glossiness (GL ₈₅ ) of 90 to 110.

Alternatively, the polyamide-based film includes a polyamide-based polymer, and the GL _20-60 value defined in Equation 1 is 0 to 15, or the GL _20-85 value defined in Equation 3 is 0 to 30.

As another example, the polyamide-based film includes a polyamide-based polymer, the 60° glossiness (GL ₆₀ ) of the film surface is 90 to 120, and the GL _20-60 value defined in Equation 1 is 0 to 15 to be.

As another example, the polyamide-based film includes a polyamide-based polymer, the 60° glossiness (GL ₆₀ ) of the film surface is 90 to 120, and the GL _20-85 value defined in Equation 3 is 0 to It's 30.

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

For example, the composition and content of the components that make up the polyamide-based film, the type and content of additives, the surface roughness range, and the heat treatment temperature and cooling temperature conditions in the film manufacturing process are all integrated to achieve the desired level of glossiness range. can do.

Cover for display device window

A cover window for a display device according to an embodiment includes a polyamide-based film and a functional layer.

The polyamide-based film includes a polyamide-based polymer, and the film surface has a 20° glossiness (GL ₂₀ ) of 90 to 130, and the film surface 60° glossiness (GL ₆₀ ) of 90 to 120, The 85° glossiness (GL ₈₅ ) of the film surface is 90 to 110.

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

The cover window for a display device may be usefully applied to a display device.

In particular, not only a polyamide-based film but also a functional layer has excellent folding characteristics, and the cover window may be usefully applied to a foldable display device or a flexible display device.

Display device

A display device according to an embodiment includes a display unit; And a cover window disposed on the display unit, wherein the cover window includes a polyamide-based film and a functional layer.

The polyamide-based film includes a polyamide-based polymer, and the film surface has a 20° glossiness (GL ₂₀ ) of 90 to 130, and the film surface 60° glossiness (GL ₆₀ ) of 90 to 120, The 85° glossiness (GL ₈₅ ) of the film surface is 90 to 110.

A detailed description of the polyamide-based film and the cover window is 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-based 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 cover window 300 is disposed and the adhesive layer 500 is disposed between the display unit 400 and the cover window 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 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 cover window 300. The adhesive layer may be an optically transparent adhesive layer, and is not particularly limited.

The cover window 300 is disposed on the display unit 400. The cover window may be positioned at the outermost side of the display device according to the embodiment to protect the display unit.

The cover window 300 may include a polyamide-based film and a functional layer. The functional layer may be at least one selected from the group consisting of a hard coating, a reflectance reducing layer, an antifouling layer, and an anti-glare layer. The functional layer may be coated on at least one surface of the polyamide-based film.

Polyamide type Film production method

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

A method of manufacturing a polyamide-based film according to an embodiment includes the steps of preparing a polyamide-based polymer solution in an organic solvent; Transferring the polymer solution to a tank; Casting the polymer solution in the tank on a belt and drying it to prepare a gel-sheet; Preparing a cured film by heat treatment while moving the gel-sheet; And cooling the cured film while moving it.

Referring to FIG. 2, in the method of manufacturing a polyamide-based film according to an embodiment, a diamine compound and a dicarbonyl compound, or a diamine compound, a dianhydride compound, and a dicarbonyl compound are mixed in an organic solvent in a polymerization facility. Simultaneously or sequentially mixing and 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-based film is a film mainly composed of a polyamide-based resin, and the polyamide-based resin is a resin containing an amide repeating unit as a structural unit. In addition, the polyamide-based resin may also contain an imide repeating unit.

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

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

In another embodiment, the preparing of the polymer solution may include preparing a polyamide (PA) solution by mixing and reacting the diamine compound and the dicarbonyl compound in a solvent. The polyamide solution is a solution containing a polymer having an amide repeating unit.

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 preparing of 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) repeating units, polyamide (PA) repeating units, and polyimide (PI) repeating units. .

The polymer contained in the polymer solution contains an amide repeating unit derived from polymerization of the diamine compound and the dicarbonyl compound.

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 content of solids 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-based film can be effectively produced in an extrusion and casting process. In addition, the prepared polyamide-based film may have mechanical properties such as improved modulus and optical properties such as low yellowness.

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

Specifically, in the step of preparing the polymer solution, (a) a diamine compound and a dicarbonyl compound or a diamine compound, a dianhydride compound, and a dicarbonyl compound are simultaneously or sequentially mixed and reacted in an organic solvent to obtain a first Preparing a polymer solution; (b) measuring the viscosity of the first polymer solution to evaluate whether it reaches a target viscosity; And (c) preparing a second polymer solution having a target viscosity by additionally adding the dicarbonyl compound when the viscosity of the first polymer solution does not reach the target viscosity.

The target viscosity may be 100,000 cps to 500,000 cps at room temperature. Specifically, the target viscosity may be 100,000 cps to 400,000 cps, 100,000 cps to 350,000 cps, 100,000 cps to 300,000 cps, 150,000 cps to 300,000 cps, or 150,000 to 250,000 cps at room temperature. However, it 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.

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.

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, it 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, prevent the occurrence of defects in the film prepared from the polymer solution, and aim 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 one or more selected from the group consisting of nitrogen, helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn), but are limited thereto. no. Specifically, the inert gas may be nitrogen.

In another embodiment, the method of manufacturing a polyamide-based film may further include adding a matting agent.

The step of introducing the matting agent may be performed before preparing the polymer solution, or may be performed after preparing the polymer solution. That is, first, a quencher may be dissolved in an organic solvent and then the mixture may be reacted to prepare a polymer, or a quencher may be added to the organic solvent after preparing a polymer by first reacting the mixture in an organic solvent.

Specifically, after preparing the polyamide-based polymer solution, the step of adding a matting agent to the organic solvent may be further included.

Accordingly, it is possible to implement a film having a gloss similar to that of glass by lowering the gloss. In addition, it is possible to improve the surface roughness and winding properties to improve the effect of improving the running scratches during film production, and it is possible to realize an aesthetic feeling that looks similar to glass. Furthermore, there is an effect of increasing the visibility of the display.

Description of the type and content of the matting agent is as described above.

The molar ratio of the dianhydride compound: the dicarbonyl compound used to prepare the polymer solution may be 0:100 to 50:50, for example, 0:100 to 45:55, 0:100 to It may be 30:70, 0:100 to 25:75 or 0:100 to 20:80. When the dianhydride compound and the dicarbonyl compound are used in such a molar ratio, it is advantageous to achieve a target level in terms of mechanical properties and optical properties, particularly gloss, of the polyamide-based film prepared from the polymer solution.

If it is out of the above range, mechanical properties such as the number of folding and hardness, or optical properties such as transparency may deteriorate.

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.

Next, after the step of preparing the polymer solution, the polymer solution is moved to a tank (S200).

3 schematically shows the manufacturing process equipment of the polyamide-based 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 to remove impurities. Conventionally, in order to remove impurities such as hydrochloric acid (HCl) generated in the process of preparing 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 exist, 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 adjusting 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 of the film produced therefrom.

The method of manufacturing the polyamide-based 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-based 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 are 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 step of vacuum degassing 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 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-based 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 continuously maintained at -20°C to 20°C.

The manufacturing method of the polyamide-based film further includes the step of producing a gel-sheet by casting and drying the polymer solution in the tank 20 (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-described thickness range and then dried and heat-treated to form 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 above 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, it is dried at a temperature of 60° C. to 150° C. for a period of 5 minutes 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.

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-based film includes the step of manufacturing a cured film by heat treatment while moving the gel-sheet (S500).

Referring to FIG. 2, the heat treatment of the gel-sheet may be performed by passing through a thermosetting machine 40.

When passing through the thermosetting machine 40, the gel-sheet is subjected to hot air treatment.

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

The heat treatment of the gel-sheet is performed for 5 minutes to 200 minutes in the range of 60°C to 500°C. Specifically, the heat treatment of the gel-sheet may be performed for 10 to 150 minutes while raising the temperature at a rate of 1.5°C/min to 80°C/min in the range of 75°C to 460°C.

At this time, the start temperature of the heat treatment of the gel-sheet may be 60°C or higher. Specifically, it may be 60 ℃ to 200 ℃, more specifically 80 ℃ to 180 ℃.

In addition, the maximum temperature during the heat treatment may be 300 ℃ to 500 ℃. For example, the maximum temperature during the heat treatment may be 350°C to 500°C, 380°C to 500°C, 400°C to 500°C, 410°C to 480°C, 410°C to 470°C, or 410°C to 450°C.

That is, referring to FIG. 2, an inlet temperature of the thermosetting machine 40 may be a heat treatment start temperature, and a temperature of a predetermined region inside the thermosetting machine 40 may be a maximum temperature during heat treatment.

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

Specifically, the heat treatment is a first hot air treatment step performed for 5 to 30 minutes in the range of 60 ℃ to 120 ℃; And a second hot air treatment step performed for 10 minutes to 120 minutes in the range of 120°C to 350°C.

By heat treatment under these conditions, the gel-sheet can be cured to have an appropriate surface hardness and modulus, and the cured film can simultaneously secure high light transmittance, low haze, and an appropriate level of gloss.

According to another embodiment, the heat treatment may include passing through an IR heater. The heat treatment by the IR heater may be performed for 1 minute to 30 minutes at a temperature range of 300° C. or higher. Specifically, the heat treatment by the IR heater may be performed for 1 minute to 20 minutes at a temperature range of 300 ℃ to 500 ℃.

The method of manufacturing the polyamide-based 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 may be more stabilized, and the optical and mechanical properties of the film established during the curing process may 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-based film includes the step of winding the cooled cured film using a winder (S700).

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-based 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-based film may exhibit excellent optical and mechanical properties by being manufactured according to the above-described manufacturing method. The polyamide-based film may be applicable to various applications requiring flexibility, transparency, and a certain level of gloss. For example, the polyamide-based film may be applied to solar cells, displays, semiconductor devices, sensors, and the like.

In particular, since the polyamide-based film can achieve a certain level of gloss, it can be usefully applied to a cover window for a display device and a display device, and has excellent folding characteristics, so it is usefully applied to a foldable display device or a flexible display device. I can.

The description of the polyamide-based film manufactured 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' after filling 779.1 g of dimethylacetamide (DMAc) as an organic solvent in a nitrogen atmosphere at 20°C in a 1L glass reactor with temperature control. -Diaminophenyl (TFMB) 64g (0.2mol) was slowly added and dissolved. Then, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) 21.3 g (0.048 mol) was slowly added and stirred for 1 hour. Then, isophthaloyl chloride (IPC) 2.44 g (0.012 mol) was added and stirred for 1 hour, terephthaloyl chloride (TPC) 28.42 g (0.14 mol) was added and stirred for 1 hour to prepare a polymer solution. Thereafter, 500 ppm of silica (average particle diameter of 100 nm to 150 nm) was added and stirred as a matting agent based on the total weight of the polyamide-based polymer to the prepared polymer solution.

The obtained polymer solution was applied to a glass plate, dried with hot air at 80°C for 30 minutes, peeled from the glass plate, fixed to a pin frame, and dried with hot air while heating at a rate of 2°C/min at 80-300°C. A 50 µm polyamide film was obtained.

Regarding the contents of TFMB, 6FDA, IPC and TPC, 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 to 6, Comparative example One

As shown in Table 1 below, a film was prepared in the same manner as in Example 1, except for different types and contents of each reactant.

<Evaluation example>

The following physical properties were measured and evaluated for the films prepared in Examples 1 to 6 and Comparative Example 1 and the existing GLASS (Reference Example), and the results are shown in Table 1 below.

Evaluation example 1: Measurement of 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: 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 3: Measurement of yellowness

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

Evaluation example 4: Gloss measurement

For a film sample of 20 mm X 60 mm X 50 μm, the glossiness when the light source was 20°, the glossiness at 60°, and the glossiness at 85° were measured using a VG-7000 equipment.

Evaluation example 5: Surface roughness Measure

The surface roughness (Ra) was measured by loading the stylus tip onto the film sample using the Kosaka SE500A.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Reference example Diamine TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 GLASS Dianhydride 6FDA 24 6FDA 17 6FDA 3 - 6FDA 25
BPDA 20 6FDA 3 6FDA 3 - Dicarbonyl compound TPC 70
IPC 6 TPC 75
IPC 8 TPC 75
IPC 22 TPC 75
IPC 25 TPC 55 TPC 75
IPC 22 TPC 75
IPC 22 - Imide: amide 24:76 17:83 3:97 0:100 45:55 3:97 3:97 - Quencher Silica
500 ppm Silica
500 ppm Silica
500 ppm Silica
500 ppm Silica
300 ppm Silica
3200ppm Silica
50 ppm - Thickness(um) 50 50 50 50 50 50 50 1000 Haze (%) 0.43 0.46 0.40 0.48 0.72 1.12 0.47 0.51 TT(%) 89.0 89.0 89.1 89.0 89.0 89.6 89.1 92.0 YI 2.34 2.49 2.95 2.92 3.57 2.87 2.65 0.07 20º 124 111 98 105 121 91 133 97.2 60º 114 105 99 107 112 93 113 97.7 85º 101 101 100 100 101 99 100 100 GL _20-60 10 6 One 2 9 2 20 0.5 GL _60-85 13 4 One 7 11 6 13 2.3 GL _20-85 23 10 2 5 20 8 33 2.8 GL _{max /min} (%) 81.45 90.99 98 93.46 83.47 91.92 75.19 97.2 Ra(㎛) 0.02 0.04 0.06 0.05 0.02 0.08 0.02 0.01

As can be seen in Table 1, it was confirmed that all of the polyamide-based films of Examples 1 to 6 achieved a level of gloss similar to that of GLASS described in Reference Examples.

In addition, Examples 1 to 6 showed excellent results in optical properties such as transmittance, haze, and yellowness, and overall surface roughness also showed excellent results.

On the other hand, in the case of the polyamide-based film of Comparative Example 1, the content of the matting agent is relatively small, so the surface roughness is as low as 0.02 µm, whereas the 20° gloss value is particularly high in terms of gloss, making it difficult to realize an aesthetic similar to that of glass. Not suitable for use as a glass replacement film

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

Claims (17)

As a polyamide-based film containing a polyamide-based polymer,
The polyamide-based polymer is formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic dianhydride compound,
The film surface has a 20° glossiness (GL ₂₀ ) of 90 to 130,
The film surface has a 60° glossiness (GL ₆₀ ) of 90 to 120,
85° glossiness (GL ₈₅ ) of the film surface is 90 to 110,
The transmittance of the film is 80% or more,
The polyamide-based film further comprises a matting agent,
The matting agent is at least one selected from the group consisting of silica, poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), polystyrene (PS), melamine, silicon, and glass,
The content of the matting agent is 100 to 3000 ppm based on the total weight of the polyamide-based polymer, a polyamide-based film for a cover window.
The method of claim 1,
A polyamide-based film for a cover window having _{a GL 20-60} value of 0 to 15 defined in Equation 1 below.
<Equation 1> GL _20-60 = | GL ₂₀ -GL ₆₀ |
The method of claim 1,
A polyamide-based film for a cover window having _{a GL 60-85} value of 0 to 15 defined in Equation 2 below.
<Equation 2> GL _60-85 = | GL ₆₀ -GL ₈₅ |
The method of claim 1,
A polyamide-based film for a cover window having _{a GL 20-85} value of 0 to 30 defined in Equation 3 below.
<Equation 3> GL _20-85 = | GL ₂₀ -GL ₈₅ |
The method of claim 1,
_{The GL max/min} value defined in Equation 4 below is 80% to 100%, a polyamide-based film for a cover window.
<Equation 4> GL _max/min (%)= (GL _min / GL _max ) X 100
In Equation 4, GL _max means the highest glossiness among _{GL 20} , GL ₆₀ and GL _{85 , and GL min} means the lowest glossiness among GL ₂₀ , GL ₆₀ and GL _85.
The method of claim 1,
A polyamide-based film for a cover window, wherein the polyamide-based polymer comprises a repeating unit represented by the following formula A and a repeating unit represented by the following formula B in a molar ratio of 0:100 to 50:50:
<Formula A>

<Formula B>

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, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si(CH ₃ ) ₂ -, -C(CH ₃ ) _2- And is selected from -C(CF ₃ ) _{2 -,}
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 is selected from -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 as 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 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 is 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 ) Connected by a connector selected from _2-
delete delete delete The method of claim 1,
A polyamide-based film for a cover window having a surface roughness of 0.01 to 0.07 µm.
The method of claim 1,
A polyamide-based film for cover windows with a haze of 1% or less.
delete The method of claim 1,
A polyamide-based film for a cover window having a yellowness of 5 or less.
As a polyamide-based film containing a polyamide-based polymer,
The polyamide-based polymer is formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic dianhydride compound,
_{The GL 20-60} value defined in Equation 1 below is 0 to 15, or
_{The GL 20-85} value defined in Equation 3 below is from 0 to 30,
The transmittance of the film is 80% or more,
The polyamide-based film further comprises a matting agent,
The matting agent is at least one selected from the group consisting of silica, poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), polystyrene (PS), melamine, silicon, and glass,
The content of the matting agent is 100 to 3000 ppm based on the total weight of the polyamide-based polymer,
Polyamide-based film for cover windows.
<Equation 1> GL _20-60 = | GL ₂₀ -GL ₆₀ |
<Equation 3> GL _20-85 = | GL ₂₀ -GL ₈₅ |
In Equations 1 and 3, GL ₂₀ means a 20° glossiness of the film surface _{, GL 60 means a 60° glossiness of the film surface, and GL 85} means an 85° glossiness of the film surface.
The method of claim 14,
A polyamide-based film for a cover window having a 60° glossiness (GL _{60) of 90 to 120 of the film surface.}
Including a polyamide-based film and a functional layer,
The polyamide-based film contains a polyamide-based polymer,
The polyamide-based polymer is formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic dianhydride compound,
The film surface has a 20° glossiness (GL ₂₀ ) of 90 to 130,
The film surface has a 60° glossiness (GL ₆₀ ) of 90 to 120,
85° glossiness (GL ₈₅ ) of the film surface is 90 to 110,
The transmittance of the film is 80% or more,
The polyamide-based film further comprises a matting agent,
The matting agent is at least one selected from the group consisting of silica, poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), polystyrene (PS), melamine, silicon, and glass,
The content of the matting agent is 100 to 3000 ppm based on the total weight of the polyamide-based polymer,
Cover window for display devices.
A display unit; And
Includes; a cover window disposed on the display unit,
The cover window includes a polyamide-based film and a functional layer,
The polyamide-based film contains a polyamide-based polymer,
The polyamide-based polymer is formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic dianhydride compound,
The film surface has a 20° glossiness (GL ₂₀ ) of 90 to 130,
The film surface has a 60° glossiness (GL ₆₀ ) of 90 to 120,
85° glossiness (GL ₈₅ ) of the film surface is 90 to 110,
The transmittance of the film is 80% or more,
The polyamide-based film further comprises a matting agent,
The matting agent is at least one selected from the group consisting of silica, poly(methyl methacrylate) (PMMA), poly(butyl methacrylate) (PBMA), polystyrene (PS), melamine, silicon, and glass,
The content of the matting agent is 100 to 3000 ppm based on the total weight of the polyamide-based polymer,
Display device.

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