KR20220043748A - Polyamide-based film, preparation method thereof, and cover window and display device comprising same - Google Patents

Abstract

The present invention relates to a polyamide-based film having excellent optical properties, such as transmittance, haze and yellowness, and mechanical properties, such as thickness uniformity, a method for manufacturing the same, and a cover window and display device including the same. The polyamide-based film includes a polyamide-based polymer, shows a combined peak of a first peak having the maximum value in a region of 2θ ranging from 10° to less than 20°combined with a second peak having the maximum value in a region of 2θ ranging from 20° to 25° on the XRD graph, and has a narrow-gap crystal ratio of larger than 67, as defined by formula 1 of [Narrow-gap crystal ratio= Area of second peak/Area of combined peak X 100].

Description

Polyamide-based film, manufacturing method thereof, and cover window and display device comprising the same

The embodiment relates to a polyamide-based film having excellent optical and mechanical properties, a method for manufacturing the same, and a cover window and a display device including the same.

Polyamide-based polymers have excellent friction, heat, and chemical resistance, and are applied to primary electrical insulation materials, coatings, adhesives, extrusion resins, heat-resistant paints, heat-resistant plates, heat-resistant adhesives, heat-resistant fibers, and heat-resistant films.

Polyamide is used in various fields. For example, polyamide is made in powder form and used as a coating agent for metal or magnet wire, etc., and is used by mixing with other additives depending on the purpose. In addition, polyamide is used together with fluoropolymers as decorative and corrosion-resistant paints, and serves to bond fluoropolymers to metal substrates. In addition, polyamide is also used for coating kitchen cookware, and has heat and chemical resistance, so it is used as a membrane used for gas separation. used

In recent years, by filming polyamide, a polyamide-based film that is cheaper and has excellent optical, mechanical and thermal properties has been developed. This polyamide-based film can be applied to display materials such as organic light-emitting diode (OLED) or liquid-crystal display (LCD), and when realizing phase difference properties, anti-reflection film, compensation film, or phase difference Applicable to film.

When such a polyamide-based film is applied to a foldable display or a flexible display, optical properties such as transparency and colorlessness and mechanical properties such as flexibility and hardness are required. However, in general, optical properties and mechanical properties have a trade-off relationship, and when the mechanical properties are improved, the optical properties may be deteriorated.

Therefore, there is a continuous need for research on polyamide-based films with improved mechanical properties and optical properties.

SUMMARY An embodiment is to provide a polyamide-based film having excellent optical and mechanical properties, a method for manufacturing the same, and a cover window and a display device including the same.

The polyamide-based film according to an embodiment includes a polyamide-based polymer, and on the XRD graph, the first peak having a maximum value in the section where the 2θ value is 10 to less than 20 ^o and the 2θ value is the maximum in the section of 20 to 25 ^o The second peak having a value includes the summed peak, and the narrow spacing ratio defined by Equation 1 below is greater than 67.

[Equation 1]

Narrow spacing determination ratio = area of second peak / area of summed peak * 100

A cover window for a display device according to an embodiment includes a polyamide-based film and a functional layer, wherein the polyamide-based film has a first peak and 2θ having a maximum value in a section in which the 2θ value is 10 to less than 20 ^o on the XRD graph. A second peak having a maximum value in the interval of 20 to 25 ^o includes a summed peak, wherein the narrow spacing determination ratio is greater than 67.

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, and the polyamide-based film has a maximum value in a section having a 2θ value of 10 to less than 20 ^o on an XRD graph. and a summed peak obtained by summing the first peak having a 2θ value and the second peak having a maximum value in a section having a 2θ value of 20 to 25 ^o , and the narrow spacing determination ratio is greater than 67.

A method of manufacturing a polyamide-based film according to an embodiment includes preparing a solution containing a polyamide-based polymer by polymerizing a diamine compound and a dicarbonyl compound in an organic solvent; casting the polymer solution to prepare a gel sheet; and heat-treating the gel sheet.

The polyamide-based film according to the embodiment has excellent optical properties (low yellowness and haze and high light transmittance) including a large amount of narrow-spaced crystalline form as the percentage of the second peak in the summed area of the first peak and the second peak is greater than 67% ), mechanical properties (modulus, thickness uniformity, etc.) can be improved.

For example, when the area of the first peak on the XRD pattern is 48% or less of the area of the second peak, the transparency of the polyamide-based film is improved, the haze is reduced, and an appropriate viscosity is ensured to form a film of a uniform thickness. It can be easy.

In addition, since the polymer film according to the embodiment has excellent mechanical properties and optical properties, it may be usefully applied to a cover window for a display device and a foldable/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 for manufacturing a polyamide-based film according to an embodiment.
3 is an XRD analysis graph (diffractogram) of the polyamide-based film of Example 2.

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

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

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

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

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

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

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

polyamide film

The embodiment provides a polyamide-based film having excellent optical properties such as high transmittance, low haze, and low yellowness, as well as excellent modulus and uniform thickness.

A polyamide-based film according to an exemplary embodiment includes a polyamide-based polymer.

The polyamide-based film includes at least two peaks including a first peak and a second peak on the XRD graph. In some embodiments, the summed peak may be composed of a sum of the first peak and the second peak.

The first peak has a maximum value in a section having a 2θ value of less than 10 to 20 ^o , and the second peak has a maximum value in a section having a 2θ value of 20 to 25 ^o . For example, the maximum value or highest point of the first peak may be located in a section having a 2θ value of 10 to less than 20 ^o , and the maximum value or highest point of the second peak is located in a section having a 2θ value of 20 to 25 ^o . can do.

Then, the first peak and the second peak are summed to form a summed peak. In some embodiments, the summed peak may be located in a section having a 2θ value of 2 to 40 ^o , preferably 5 to 35 ^o .

As used herein, the term “peak” may mean an XRD pattern that deviates from the trend or a shape thereof when the XRD pattern outside the section where the peak is located on the XRD graph has a specific trend that can be expressed as a function, for example. there is.

The function may be, for example, an exponential function expressed as y=ae ^x +b. In this case, a and b may be constants.

The specific trend may be defined as a baseline on the XRD graph.

For example, the base line may correspond to an XRD pattern of an amorphous component in the polyamide-based polymer or film, and the peak may correspond to an XRD pattern of a crystalline component.

In this case, the peak may be defined as a portion having an intensity value greater than the baseline (a portion existing above the baseline). The base line may be provided as a base of the peak.

For example, the first peak and the second peak may correspond to various crystal types having different interplanar spacings.

Among crystalline forms with various interplanar spacings appearing in the XRD pattern, crystalline forms having relatively wide interplanar spacing may be defined as optical spacing crystalline forms, and crystalline forms having relatively narrow interplanar spacing may be defined as narrow spacing crystalline forms.

In some embodiments, the crystalline component corresponding to the first peak may include an optical spacing crystalline form having a relatively wide interplanar spacing among crystalline forms having various interplanar spacings in a high ratio, and the second peak The crystalline component corresponding to may include a narrow spacing crystalline form having a relatively narrow interplanar spacing among crystalline forms having various interplanar spacings in a high ratio.

In some embodiments, the area of the peak can be measured.

The polyamide-based film according to embodiments may have a narrow spacing ratio greater than 67.

The narrow gap determination ratio may be defined by the following Equation 1.

[Equation 1]

Narrow spacing determination ratio = area of second peak / area of summed peak * 100

For example, the area (second area) of the second peak to the area (sum area) of the summed peaks may be greater than 67%. In this case, among the crystalline forms having various interplanar spacings included in the polyamide-based polymer or the polyamide-based film, the narrow-spaced crystalline form is included in a high ratio to provide mechanical properties such as modulus and thickness uniformity of the polyamide-based film and Optical properties such as transmittance, haze, and yellowness may be improved together. Preferably, the narrow spacing ratio may be 69 or more, 72 or more, or 75 or more. Also, the narrow spacing ratio may be 90 or less, 85 or less, 80 or less, or 78 or less.

In an embodiment, the area of the summed peak may be defined as the sum of the area of the first peak and the area of the second peak.

In some embodiments, the XRD pattern of the polyamide-based film may satisfy Equation 2 below.

[Equation 2]

Area of 1st peak / Area of 2nd peak ≤ 48

For example, the area (first area) of the first peak may be less than or equal to 48% of the second area. In this case, the narrow spacing crystalline forms are included in a significantly larger amount (about 2 times or more) than the optical spacing crystalline forms, and mechanical properties such as modulus and thickness uniformity of the polyamide-based film and optical properties such as transmittance, haze and yellowness properties can be improved together. Preferably, the area of the first peak may be 45% or less, 40% or less, 35% or less, 30% or less, or 28% or less of the second area. In addition, the area of the first peak may be 10% or more, 15% or more, 20% or more, 25% or more, or 26% or more of the second area.

The x-direction refractive index (n _x ) of the polyamide-based film according to the embodiment may be 1.60 to 1.70, 1.61 to 1.69, 1.62 to 1.68, 1.64 to 1.68, 1.64 to 1.66, or 1.64 to 1.65.

In addition, the y-direction refractive index (n _y ) of the polyamide-based film may be 1.60 to 1.70, 1.61 to 1.69, 1.62 to 1.68, 1.63 to 1.68, 1.63 to 1.66, or 1.63 to 1.64.

Further, the z-direction refractive index (n _z ) of the polyamide-based film may be 1.50 to 1.60, 1.51 to 1.59, 1.52 to 1.58, 1.53 to 1.58, 1.54 to 1.58, or 1.54 to 1.56.

When the values of the refractive index in the x-direction, the refractive index in the y-direction, and the refractive index in the z-direction of the polyamide-based film are within the above ranges, when the film is applied to a display device, it has excellent visibility when viewed from the front as well as from the side, so that a wide viewing angle can be implemented.

The in-plane retardation (R _o ) of the polyamide-based film according to the embodiment may be 800 nm or less. Specifically, the in-plane retardation (R _o ) of the polyamide-based film is 700 nm or less, 600 nm or less, 550 nm or less, 100 nm to 800 nm, 200 nm to 800 nm, 200 nm to 700 nm, 300 nm to 700 nm nm, 300 nm to 600 nm, or 300 nm to 540 nm.

In addition, the thickness direction retardation (R _th ) of the polyamide-based film according to the embodiment may be 5000 nm or less. Specifically, the thickness direction retardation (R _th ) of the polyamide-based film is 4800 nm or less, 4700 nm or less, 4650 nm or less, 1000 nm to 5000 nm, 1500 nm to 5000 nm, 2000 nm to 5000 nm, 2500 nm to 5000 nm, 3000 nm to 5000 nm, 3500 nm to 5000 nm, 4000 nm to 5000 nm, 3000 nm to 4800 nm, 3000 nm to 4700 nm, 4000 nm to 4700 nm, or 4200 nm to 4650 nm.

Here, the in-plane retardation (R _o ) is the product ( _{Δn xy} = | n _x -n _y |) of the refractive index of two orthogonal axes in the plane of the film and the film thickness (d) ( Δn _xy × d) as a parameter, which is a measure of optical isotropy or anisotropy.

In addition, thickness direction retardation (R _th ) refers to two birefringences _{Δn xz} (= | n _x -n _z |) and _{Δn yz} (= | n _y ) when viewed in a cross section in the film thickness direction. -n _z |) is a parameter defined as the average of retardation obtained by multiplying each film thickness (d).

When the values of the in-plane retardation and thickness direction retardation of the polyamide-based film are within the above ranges, optical distortion and color distortion can be minimized when the film is applied to a display device, and light leakage from the side can also be minimized. can

The polyamide-based film may further include a filler in addition to the polyamide-based polymer.

The average particle diameter of the filler may be 60 nm to 180 nm. Specifically, the average particle diameter of the filler may be 80 nm to 180 nm, 100 nm to 180 nm, 110 nm to 160 nm, 120 nm to 160 nm, or 130 nm to 150 nm, but is not limited thereto.

When the average particle diameter of the filler is within the above range, compared with other inorganic fillers, a decrease in optical properties may not occur even if a relatively large amount is added.

The refractive index of the filler may be 1.55 to 1.75. Specifically, the refractive index of the filler may be 1.60 to 1.75, 1.60 to 1.70, 1.60 to 1.68, or 1.62 to 1.65, but is not limited thereto.

When the refractive index of the filler satisfies the above range, birefringence values related to n _x , n _y and n _z may be appropriately adjusted, and luminance at various angles of the film may be improved.

On the other hand, when the refractive index of the filler is out of the above range, the presence of the film on the film may be visually recognized or the haze may increase due to the filler.

The content of the filler may be 100 ppm to 3000 ppm based on the total weight of the polyamide-based polymer solid content. Specifically, the content of the filler is 100 ppm to 2500 ppm, 100 ppm to 2200 ppm, 200 ppm to 2500 ppm, 200 ppm to 2200 ppm, 250 ppm to 2100 ppm, based on the total weight of the polyamide-based polymer solid content, Or it may be 300 ppm to 2000 ppm, but is not limited thereto.

When the content of the filler is out of the above range, the haze of the film increases rapidly, and aggregation of fillers occurs on the surface of the film, so that a foreign body feeling is visually confirmed, or a problem occurs in running in the production process, or winding property is reduced can be

The filler may include, for example, silica and barium sulfate, but is not limited thereto.

The filler may be included in the form of particles. In addition, the filler is in a state in which a special coating treatment is not applied to the surface, and may be evenly dispersed throughout the film.

When the polyamide-based film includes the filler, the film may secure a wide viewing angle without deterioration of optical properties.

The residual solvent content in the polyamide-based film may be 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 means the amount of the solvent remaining in the finally prepared film without volatilization during the film production.

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

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 times of folding before breaking may be 200,000 or more.

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

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

The surface roughness of the polyamide-based film according to the embodiment may be 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.

Since the polyamide-based surface roughness satisfies the above range, it may be advantageous to realize high luminance even when the angle from the normal direction of the surface light source is increased.

The polyamide-based film according to an embodiment includes a polyamide-based polymer, and the polyamide-based polymer may include an amide repeating unit, and may optionally include an imide repeating unit.

In some embodiments, the polyamide-based polymer may include only the amide repeating unit without including the imide repeating unit. In this case, the modulus of the polyamide-based film is increased, so that it can be effectively applied to a foldable/flexible display device.

The polyamide-based film may include a polyamide-based polymer, and the polyamide-based polymer may be formed by simultaneously or sequentially reacting reactants including a diamine compound and a dicarbonyl compound. Specifically, the polyamide-based polymer may be 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. In this case, the polyamide-based polymer may include 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. there is.

In some embodiments, the polyamide-based polymer may be polymerized without including the polyanhydride compound. In this case, the polyamide-based polymer may not include an imide repeating unit.

The polyamide-based film according to an embodiment may include a polyamide-based polymer in which a diamine compound and a dicarbonyl compound are polymerized to form an amide bond. The polyamide-based polymer may optionally include a polyamide-imide-based polymer in which a dianhydride compound is additionally polymerized to form an imide bond.

In some embodiments, the polyamide-based polymer may not include the polyamide-imide-based polymer. In this case, the modulus of the polyamide-based film is increased, so that it can be effectively applied to a foldable/flexible display device.

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

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

<Formula 1>

In Formula 1,

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

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

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

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

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

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

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

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

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

The dicarbonyl compound is not particularly limited, but may be, for example, a compound of Formula 3 below.

<Formula 3>

In Formula 3,

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

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

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

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

Specifically, (J) _j 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 in Formula 3 may be a group represented by Formula 3-1b, a group represented by Formula 3-2b, a group represented by 3-3b, or a group represented by 3-8b. there is.

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

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

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

In one embodiment, the polyamide-based polymer may include two or more amide-based repeating units.

For example, the two or more types of amide-based repeating units may include a first amide-based repeating unit and a second amide-based repeating unit. The first amide-based repeating unit may be formed by a reaction between a first dicarbonyl compound and the diamine compound, and the second amide-based repeating unit may be formed by a reaction between a second dicarbonyl compound and the diamine compound. there is.

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

The first dicarbonyl compound and the second dicarbonyl compound may each include two carbonyl groups. An angle between two carbonyl groups included in the first dicarbonyl compound may be greater than an angle between two carbonyl groups included in the second dicarbonyl compound.

In example embodiments, the first dicarbonyl compound and the second dicarbonyl compound may have a structural isomer relationship with each other. By using two kinds of dicarbonyl compounds in a structural isomeric relationship, a polyamide-based polymer satisfying the above-described crystal plane spacing can be formed, thereby improving optical and mechanical properties of the polyamide-based polymer.

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

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

When the first dicarbonyl compound and the second dicarbonyl compound are each an aromatic dicarbonyl compound, since they contain a benzene ring, the surface hardness and tensile strength of the film including the prepared polyamide-based polymer are the same. It can contribute to improving mechanical properties.

For example, the angle between the two carbonyl groups included in the first dicarbonyl compound may be 160 to 180 ^o , and the angle between the two carbonyl groups included in the second dicarbonyl compound is 80 to 140 ^o can be

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

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

When TPC as the first dicarbonyl compound and IPC as the second dicarbonyl compound are appropriately used in combination, the prepared film including the polyamide-based polymer has high oxidation resistance, productivity, light transmittance, transparency, and modulus. etc., and may have a low haze.

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

<Formula B>

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

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

<Formula B-1>

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

<Formula B-2>

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

In some embodiments, the molar ratio of the first amide-based repeating unit and the second amide-based repeating unit may be 10:90 to 90:10. By setting the molar ratio of the first and second amide-based repeating units to the above-described range, the crystal plane spacing of the polyamide-based polymer may be adjusted within the above-described range. Accordingly, physical properties such as haze, light transmittance, yellowness, and modulus of the polyamide-based film can be improved. Preferably, the molar ratio of the first amide-based repeating unit and the second amide-based repeating unit may be 25:75 to 79:21, 25:75 to 75:25, or 30:70 to 75:25.

In some embodiments, the thickness deviation of the polyamide-based film may be 4 μm or less based on a thickness of 50 μm. The thickness deviation may mean a deviation between a maximum or minimum value with respect to an average of thicknesses measured at 10 random positions of the film. In this case, since the polyamide-based film has a uniform thickness, optical and mechanical properties at each point may be uniformly displayed.

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

The transmittance of the polyamide-based film may be 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 polyamide-based film may have a yellow index of 3 or less. For example, the yellowness may be 2.5 or less or 2 or less, but is not limited thereto.

The polyamide-based film may have a modulus of 5.0 GPa or more. Specifically, the modulus may be 5.5 GPa or more or 6.0 GPa or more, but is not limited thereto.

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

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

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

The polyamide-based film may have 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 may have 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 may have uniform thickness as well as excellent optical properties such as low haze, low yellowness, and high transmittance to have uniform and excellent optical and mechanical properties over the entire area.

The above-described physical properties of the polyamide-based film 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.

The characteristics of the components and physical properties of the above-described polyamide-based film may be combined with each other.

For example, the polyamide-based film may include a polyamide-based polymer, transmittance of 80% or more, haze of 1% or less, and yellowness of 3 or less.

In addition, the characteristics and physical properties of the above-described XRD pattern of the polyamide-based film are the chemical and physical properties of the components constituting the polyamide-based film, and the process conditions of each step in the method of manufacturing the polyamide-based film to be described later. It may be an aggregated result.

For example, the composition and content of the components constituting the polyamide-based film, polymerization conditions and heat treatment conditions in the film manufacturing process, etc. are all combined to realize the desired characteristics of the XRD pattern.

Cover window for display devices

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 on the XRD graph, a first peak having a maximum value in a section having a 2θ value of 10 to less than 20 ^o and a second peak having a maximum value in a section having a 2θ value of 20 to 25 ^o It includes a summed peak in which two peaks are summed, and the narrow spacing determination ratio defined by Equation 1 is greater than 67.

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

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

The polyamide-based film may have excellent optical and mechanical properties because the position and area ratio of the peaks on the XRD analysis pattern have the above-described characteristics.

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 on the XRD graph, a first peak having a maximum value in a section having a 2θ value of 10 to less than 20 ^o and a second peak having a maximum value in a section having a 2θ value of 20 to 25 ^o It includes a summed peak in which two peaks are summed, and the narrow spacing determination ratio defined by Equation 1 is greater than 67.

A detailed description of the polyamide-based film and the cover window is the same as described above.

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

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

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 may display 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 respectively corresponding to pixels. Specifically, each may include a cathode, an electron transport layer, a light emitting layer, a hole transport layer, and an anode. The driving substrate may be drivably coupled to the organic EL substrate. That is, the driving substrate may be coupled to apply a driving signal, such as a driving current, to the organic EL substrate, thereby applying a current to each of the organic EL units to drive the organic EL substrate.

In addition, an adhesive layer 500 may be included between the display unit 400 and the cover window 300 . The adhesive layer may be an optically transparent adhesive layer, and is not particularly limited.

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

The cover window 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 antiglare layer. The functional layer may be coated on at least one surface of the polyamide-based film.

In the case of the polyamide-based film according to the embodiment, it is simply applied in the form of a film to the outside of the display device without changing the display driving method, the color filter inside the panel, the laminated structure, etc. to achieve uniform thickness, low-haze, and high-transmittance , a display device having high-transparency can be provided, and since excessive process changes or cost increases are not required, there is also an advantage in that production costs can be reduced.

The polyamide-based film according to the embodiment may have excellent optical properties such as high transmittance, low haze, and low yellowness, as well as have a uniform thickness.

In addition, the polyamide-based film according to the embodiment may minimize optical distortion by having an in-plane retardation and a thickness-direction retardation below a certain level, and may also reduce light leakage from the side.

In particular, as the screen size of the display device increases, image quality may be different for each area of the screen. quality can be realized.

Manufacturing method of polyamide-based film

One embodiment provides a method for producing a polyamide-based film.

A method for preparing a polyamide-based film according to an embodiment includes preparing a solution containing a polyamide-based polymer in an organic solvent by polymerizing a diamine compound and a dicarbonyl compound; pouring the polymer solution into a tank; manufacturing a gel sheet by extruding and casting the solution in the tank and then drying; and heat-treating the gel sheet.

Referring to FIG. 2 , the method for preparing a polyamide-based film according to an embodiment includes the steps of preparing a solution including a polyamide-based polymer by polymerizing a diamine compound and a dicarbonyl compound in an organic solvent (S100); Casting the polymer solution to prepare a gel sheet (S200); and heat-treating the gel sheet (S300).

The method for producing a polyamide-based film according to some embodiments includes the steps of adjusting the viscosity of the polyamide polymer solution (S110), aging the polyamide polymer (S120), and/or degassing the polyamide polymer solution It may further include step (S130).

The polyamide-based film is a film containing a polyamide-based polymer as a main component, and the polyamide-based polymer is a resin including an amide repeating unit as a structural unit. Optionally, the polyamide-based polymer may include imide repeat units.

In the method for producing the polyamide-based film, the polymer solution for preparing the polyamide-based polymer is prepared by simultaneously or sequentially mixing a diamine compound and a dicarbonyl compound in an organic solvent in a reactor, and reacting the mixture can be manufactured (S100).

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

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

In one embodiment, preparing the polymer solution may be performed using two different dicarbonyl compounds as the dicarbonyl compound. In this case, the two kinds of dicarbonyl compounds may be mixed and reacted simultaneously or sequentially. Preferably, the first dicarbonyl compound and the diamine compound may react to form a prepolymer, and the prepolymer and the second dicarbonyl compound may react to form the polyamide-based polymer. In this case, the polyamide-based polymer and the polyamide-based film having the above-described position and area of the peak of the XRD pattern can be easily controlled.

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

Alternatively, the polymer included in the polymer solution is an imide repeating unit derived from the polymerization of the diamine compound and the dianhydride compound and an amide derived from the polymerization of the diamine compound and the dicarbonyl compound. It may include a repeating unit.

In one embodiment, the step of preparing a solution containing the polyamide-based polymer may be performed at a temperature of -20 to 25 ^o C. For example, mixing and reaction of the solvent, the diamine compound, and the dicarbonyl compound may be performed at a temperature of -20 to 25 ^o C. When the temperature is out of the above temperature range, excessively few or many polymerization nuclei are formed, thereby making it difficult to form a polyamide-based polymer having desired properties. Accordingly, the ratio of the second area to the summed area on the XRD pattern may be out of the above-described range. Therefore, the yellowness of the polyamide-based film may increase, or the viscosity of the polymer solution may be less than a predetermined range, so that the thickness deviation of the formed film may increase. Preferably, the step of preparing a solution containing the polyamide-based polymer is -20 to 20 ^o C, -20 to 15 ^o C, -20 to 10 ^o C, -15 to 20 ^o C, -15 to 15 ^o C, -15 to 10 ^o C, -10 to 20 ^o C, -10 to 15 ^o C, -10 to 10 ^o C, -8 to 20 ^o C, -8 to 15 ^o C, -8 to 10 ^o C, -5 to 20 ^o C, -5 to 15 ^o C or -5 to 10 ^o C temperature conditions.

The content of the solids included in the polymer solution may be 10 wt% to 30 wt%, but is not limited thereto.

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

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

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

By adjusting the pH of the polymer solution to the above-mentioned range, it is possible to prevent the occurrence of defects in the film prepared from the polymer solution, and to implement desired optical and mechanical properties in terms of yellowness and modulus.

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.

The molar ratio of the first dicarbonyl compound and the second dicarbonyl compound used to prepare the polymer solution may be 10:90 to 79:21, preferably, 25:75 to 79:21, 25:75 to 75:25 or 30:70 to 75:25.

By using the first dicarbonyl compound and the second dicarbonyl compound in such a ratio, a polyamide-based polymer and film having the above-described XRD pattern can be prepared, and the thickness uniformity of the polyamide-based film , modulus, haze, transmittance, yellowness, and the like can be improved.

If it is out of the above range, optical properties such as luminance or haze may be deteriorated.

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

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

The polymer solution may be stored at -20°C to 20°C, -20°C to 10°C, -20°C to 5°C, -20°C to 0°C, or 0°C to 10°C.

When stored at the above temperature, it is possible to prevent deterioration of the polymer solution and to reduce the moisture content, thereby preventing defects in the film prepared therefrom.

In one embodiment, after the step of preparing the polymer solution, the step of adjusting the viscosity of the polymer solution (S110) may be further included. The viscosity of the polymer solution may be adjusted to 200,000 cPs to 350,000 cPs at room temperature. In this case, thickness uniformity can be improved by improving the film-forming property of a polyamide-type film.

Specifically, the preparing of the polymer solution includes: preparing a first polymer solution by simultaneously or sequentially mixing and reacting a diamine compound and a dicarbonyl compound in an organic solvent; and preparing a second polymer solution having a target viscosity by additionally adding the dicarbonyl compound.

In the case of preparing the first polymer solution and preparing the second polymer solution, the viscosity of the prepared polymer solution may be different. For example, the viscosity of the second polymer solution may be 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 may be different. For example, the stirring speed when preparing the first polymer solution may be faster than the stirring speed when preparing the second polymer solution.

In some embodiments, the polymer solution or the viscosity-adjusted polymer solution may be aged (S120).

The aging may be performed by leaving the polymer solution at a temperature of -10 to 10 ^o C for 24 hours or more. In this case, the polyamide-based polymer or unreacted material contained in the polymer solution may be homogenized by, for example, completing the reaction or achieving chemical equilibrium, and mechanical/optical of the polyamide-based film formed therefrom The properties may be substantially uniform over the entire area of the film. Preferably, the aging may be performed at -5 to 10 ^o C, -5 to 5 ^o C, or -3 to 5 ^o C temperature conditions.

In one embodiment, the step of degassing the polyamide polymer solution (S130) may be further included. By removing moisture in the polymer solution through the degassing and reducing impurities, the reaction yield can be increased, and the surface appearance and mechanical properties of the final film can be excellently implemented.

The degassing may include vacuum degassing or inert gas purging.

The vacuum defoaming may be performed for 30 minutes to 3 hours after depressurizing the reactor in which the polymer solution is accommodated to 0.1 bar to 0.7 bar. By performing vacuum defoaming under these conditions, it is possible to reduce air bubbles inside the polymer solution, and as a result, it is possible to prevent surface defects of the film prepared therefrom, and to achieve excellent optical properties such as haze.

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

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

The vacuum defoaming and the inert gas purging may be performed as separate processes.

For example, a vacuum defoaming process is performed, and thereafter, a purging process with an inert gas may be performed, but is not limited thereto.

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

After preparing a solution containing the polyamide-based polymer in an organic solvent as described above, a filler may be added to the solution.

The filler has an average particle diameter of 60 nm to 180 nm, a refractive index of 1.55 to 1.75, and a content of 100 ppm to 3,000 ppm based on the total weight of the polyamide-based polymer solid content. In addition, the filler may be silica or barium sulfate.

A more detailed description of the filler is as described above.

A gel sheet may be prepared by casting the polymer solution (S200).

For example, the polymer solution may be extruded, applied and/or dried on a support to form a gel sheet.

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

As described above, the polymer solution may be 200,000 cPs to 350,000 cPs at room temperature. By satisfying the above viscosity range, the polymer solution can be cast to a uniform thickness without defects when cast, and a polyamide film having a substantially uniform thickness can be formed without local/partial thickness change during drying.

After casting the polymer solution, it is dried at a temperature of 60 ^o C to 150 ^o C for a time of 5 minutes to 60 minutes to prepare a gel sheet. Specifically, the polymer solution may be dried at a temperature of 70 ^o C to 90 ^o C for a time of 15 to 40 minutes to prepare a gel sheet.

During the drying, some or all of the solvent of the polymer solution may be volatilized to prepare the gel sheet.

The dried gel sheet may be heat-treated to form a polyamide-based film (S300).

The heat treatment of the gel sheet may be performed, for example, through a thermosetting machine.

The thermosetting machine may heat-treat the gel sheet through hot air.

When the heat treatment by hot air is performed, the amount of heat may be uniformly provided. If the amount of heat is not evenly distributed, a 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 may be performed in a range of 60° C. to 500° C. for 5 minutes to 200 minutes. 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 ^o C to 20 ^o C in the range of 80 ^o C to 300 ^o C.

At this time, the heat treatment start temperature of the gel sheet may be 60 ^o C or more. Specifically, the heat treatment start temperature of the gel sheet may be 80 ℃ to 180 ℃.

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

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 minutes 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 a range of 120° C. to 350° C.; may include.

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

According to one 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 ^o 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 ^o C to 500 ^o C.

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 uses requiring flexibility, transparency, and a specific level of brightness. For example, the polyamide-based film may be applied to a solar cell, a display, a semiconductor device, a sensor, and the like.

In particular, since the polyamide-based film has excellent thickness uniformity and optical properties, it can be usefully applied to a cover window for a display device and a display device, and has excellent folding properties, so that it can be usefully applied to a foldable display device or a flexible display device can

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

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

<Example>

Example 1

In a double-jacketed 1L glass reactor with temperature control, 567 g of dimethylacetamide (DMAc), an organic solvent, was filled under a nitrogen atmosphere at 10°C, and 2,2'-bis(trifluoromethyl)-4, an aromatic diamine, 64.0 g (0.200 mol) of 4'-diaminobiphenyl (TFDB) was slowly added while dissolving.

Then, while slowly adding terephthaloyl chloride (TPC) as the first dicarbonyl compound, the mixture was stirred for 1 hour. Then, as the second dicarbonyl compound, isophthaloyl chloride (IPC) was added in 94% of the total amount and stirred for 1 hour to prepare a first polymer solution. A 10 wt% IPC solution was prepared in DMAc organic solvent, 1 mL was added, and the process of stirring was repeated for 30 minutes to react 4% IPC with respect to the total input amount to prepare a second polymer solution. At this time, the viscosity of the second polymer solution was adjusted to about 230,000 cPs, and the temperature during polymerization was maintained at 10 °C.

The second polymer solution was applied to a glass plate and then dried. After peeling the dried polyamide polymer from the glass plate, heat treatment was performed to obtain a polyamide-based film having a thickness of 50 μm.

With respect to the content of the diamine compound (TFMB) and the dicarbonyl compound (IPC, TPC), the number of moles of the dicarbonyl compound based on 100 moles of the diamine compound is shown in Table 1.

Examples 2 to 5 and Comparative Examples 1 to 3

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

<Evaluation example>

The physical properties of the films prepared in Examples and Comparative Examples were measured and evaluated as follows, and the results are shown in Table 1 below.

Evaluation Example 1: Film thickness measurement and uniformity evaluation

Using a digital micrometer 547-401 from Mitsutoyo, Japan, the thicknesses of 10 random positions on the film were measured and averaged.

When measuring 10 points, the difference between the maximum value and the minimum value was defined as the thickness deviation, and the thickness uniformity was evaluated as “good” when the thickness deviation was 4 μm or less and “bad” when the thickness deviation was more than 4 μm.

Evaluation Example 2: Modulus Measurement

Using Instron's universal testing machine UTM 5566A, cut the sample to 10 cm or more in the direction orthogonal to the main shrinkage direction and 10 mm in the main shrinkage direction, attach it to a clip spaced 10 cm apart, and wait until fracture occurs at room temperature A stress-strain curve was obtained while stretching at a rate of 12.5 mm/min. In the stress-strain curve, the slope of the load with respect to the initial strain was defined as the modulus (GPa).

Evaluation Example 3: Transmittance and haze measurement

Light transmittance and haze were measured according to JIS K 7105, JIS K 7136, and JIS K 7161 standards using a haze meter NDH-5000W of Denshoku Kogyo, Japan.

Evaluation Example 4: Measurement of yellowness

Yellowness (Yellow Index, YI) was measured by a spectrophotometer (UltraScan PRO, Hunter Associates Laboratory) at d65, 10° condition, according to ASTM-E313 standard.

Evaluation Example 5: Viscosity Measurement

The temperature of the polymer solution (Varnish) was maintained at 10° C. and measured using a viscometer of TOKI SANGYO's BH-II Model. RPM was set to 4, and it was checked whether the target viscosity was realized using spindle number 7 or not.

Evaluation Example 6: X-ray diffraction crystallography (XRD) analysis

XRD analysis was performed on the polyamide-based films of Examples and Comparative Examples. In this case, Rigaku's Ultima IV was used, and the analysis conditions were set as follows.

-Scan Source: Cu(40kV,30mA)

-Scan Range (2-Theta): 5~45º

-Scan Size: 0.02º

-Scan Speed: 0.24º/sec

3 is an XRD analysis graph (diffractogram) of the polyamide-based film of Example 2.

Referring to FIG. 3 , a summed peak 10 in which two peaks are summed in a section having a 2θ value of about 5 to 35 ^o was observed.

The summed peak 10 was separated into a first peak 11 and a second peak 12, and the first peak 11 is located in a section (first section) in which the maximum value of 2θ is less than 10 to 20 ^o , The second peak 12 was located in a section (second section) in which the maximum value of 2θ was 20 to 25 ^o . The summed peak 10 is separated so that the first peak 11 and the second peak 12 have the form of a Gaussian distribution with respect to the base line 18 .

The starting point 14 (a point at which the 2θ value is about 5 ^o ) and the ending point 15 (the point at which the 2θ value is about 35 ^o ) of the summed peak 10 are converted to an exponential function (eg, y=ae ^x +b; a and b are constant), and connected to an XRD pattern of a section excluding the summation peak to establish a baseline 18 .

In the summed peak 10 , the first peak 11 , and the second peak 12 , the area of a portion having an intensity value greater than that of the baseline 18 was analyzed using an analysis program.

And, the narrow spacing ratio was calculated according to Equation 1 and shown in Table 1 below, and the percentage of the area (first area) of the first peak to the area (second area) of the second peak 12 also It is shown in Table 1 below.

[Equation 1]

Narrow spacing determination ratio = area of second peak / area of summed peak * 100

division Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 of polyamide-based polymers
polymerization ratio diamine compound TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 dicarbonyl
compound TPC 30 TPC 50 TPC 60 TPC 70 TPC 75 TPC 75 TPC 5 TPC 95 IPC 70 IPC 50 IPC 40 IPC 30 IPC 25 IPC 25 IPC 95 IPC 5 polymerization temperature ( ^o C) 10 10 10 10 10 30 10 10 Viscosity (only cPs) 23 26 28 24.5 24 4 5 22 Film properties Thickness (㎛) 50 50 50 50 50 50 50 50 thickness uniformity Good Good Good Good Good error error Good Narrow Gap Determination Ratio 80 78 75 69 72 65 62 67 Percentage of first area to second area (%) 25.4 27.9 33.2 44.9 39.1 53.3 61 48.3 Modulus (Gpa) 5.1 5.3 6.4 6.9 6.8 5.9 3.9 5.7 Permeability (%) 88.9 88.5 88.5 89 88.9 88.3 89.3 76.9 Haze (%) 0.32 0.5 0.4 0.4 0.4 0.5 0.3 68.7 yellowness 1.6 2.2 2.4 2.9 2.7 3.4 3.6 31.1

As can be seen in Table 1, in the case of the examples in which the percentage of the second area on the XRD graph exceeds 67%, it was confirmed that it has excellent properties such as modulus, transmittance, haze, and yellowness compared to the comparative examples. did

On the other hand, in Comparative Examples in which the percentage of the second area was 67% or less on the XRD graph, it was confirmed that the percentage of the second area was decreased, and properties such as yellowness, modulus, transmittance, and haze were lowered.

Specifically, in the case of Comparative Example 1 in which the polyamide-based polymer was polymerized at 30 ^o C, the viscosity of the polymer solution was lowered, making it difficult to form a film of uniform thickness, and the percentage of the second area was 65%, and yellow degree increased.

Comparative Example 2 in which the polymerization molar ratio of TPC was 5% Also, as the viscosity of the polymer solution did not reach the appropriate viscosity, it was substantially difficult to uniformly form a film, the percentage of the second area decreased, the yellowness increased, and the modulus was decreased.

Also, in Comparative Example 3 in which the polymerization molar ratio of TPC was 95%, the percentage of the second area was 67%, and optical properties such as transmittance, haze, and yellowness were significantly reduced.

100: polyamide-based film
101: first surface 102: second surface
200: functional layer 300: cover window
400: display unit 500: adhesive layer

Claims (14)

It contains a polyamide-based polymer,
On the XRD graph, the first peak having the maximum value in the section where the 2θ value is less than 10 to 20 ^o and the second peak having the maximum value in the section where the 2θ value is 20 to 25 ^o include a summed peak summed,
A polyamide-based film having a narrow spacing crystallization ratio greater than 67, defined by the following formula:
[Equation 1]
Narrow spacing determination ratio = area of second peak / area of summed peak * 100
According to claim 1,
The polyamide-based polymer comprises two or more amide-based repeating units, a polyamide-based film.
3. The method of claim 2,
The two or more kinds of amide-based repeating units include a first amide-based repeating unit derived from a first dicarbonyl compound and a second amide-based repeating unit derived from a second dicarbonyl compound,
and an angle between two carbonyl groups in said first dicarbonyl compound is greater than an angle between two carbonyl groups in said second dicarbonyl compound.
3. The method of claim 2,
The two or more kinds of amide-based repeating units include a first amide-based repeating unit derived from a first dicarbonyl compound and a second amide-based repeating unit derived from a second dicarbonyl compound,
The molar ratio between the first amide-based repeating unit and the second amide-based repeating unit is 10:90 to 90:10, a polyamide-based film.
According to claim 1,
A polyamide-based film satisfying the following formula 2:
[Equation 2]
Area of 1st peak / Area of 2nd peak ≤ 48
According to claim 1,
Based on the film thickness of 50 μm,
A polyamide-based film having a yellowness of 3 or less.
According to claim 1,
Based on the film thickness of 50 μm,
a modulus of 5 GPa or more,
The transmittance is 80% or more,
A polyamide-based film having a haze of 1% or less.
Including a polyamide-based film and a functional layer,
The polyamide-based film is a summed peak in which the first peak having the maximum value in the section where the 2θ value is less than 10 to 20 ^o and the second peak having the maximum value in the section where the 2θ value is 20 to 25 ^o on the XRD graph are summed. includes,
A cover window for a display device, wherein the narrow gap determination ratio defined by the following formula (1) is greater than 67:
[Equation 1]
Narrow spacing determination ratio = area of second peak / area of summed peak * 100
display unit; and
It 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 is a summed peak in which the first peak having the maximum value in the section where the 2θ value is less than 10 to 20 ^o and the second peak having the maximum value in the section where the 2θ value is 20 to 25 ^o on the XRD graph are summed. includes,
A display device, wherein the narrow gap determination ratio defined by the following formula (1) is greater than 67:
[Equation 1]
Narrow spacing determination ratio = area of second peak / area of summed peak * 100
preparing a solution containing a polyamide-based polymer by polymerizing a diamine compound and a dicarbonyl compound in an organic solvent;
casting the polymer solution to prepare a gel sheet; and
Including; heat-treating the gel sheet;
The method for producing the polyamide-based film of claim 1.
11. The method of claim 10,
The method for producing a polyamide-based film, wherein the temperature at the time of polymerization of the polyamide-based polymer is -10 ℃ to 25 ℃.
11. The method of claim 10,
The viscosity of the solution containing the polyamide-based polymer is 200,000 cPs to 350,000 cPs, the method for producing a polyamide-based film.
11. The method of claim 10,
The method for producing a polyamide-based film, further comprising the step of aging the solution containing the polyamide-based polymer at -10 ^o C to 10 ^o C.
11. The method of claim 10,
The method for producing a polyamide-based film, wherein the angle between the two carbonyl groups in the first dicarbonyl compound is greater than the angle between the two carbonyl groups in the second dicarbonyl compound.

Images