KR102372798B1 - Polymer film, preparation method thereof, and cover window and display device comprising same - Google Patents

Abstract

The embodiment relates to a polymer film having excellent folding properties and transparency and maintaining excellent mechanical properties even after repeated stretching and contraction in an elastic region, a method for manufacturing the same, and a front plate and display device including the same, the polymer film contains a polymer resin selected from the group consisting of polyamide-based resins and polyimide-based resins, and MOR _0/9 of Formula 1 is 2% or less.

Description

Polymer film, manufacturing method thereof, and front panel and display device including the same

The embodiment relates to a polymer film having excellent folding properties and transparency, and maintaining excellent mechanical properties even after repeated stretching and contraction in an elastic region, a method for manufacturing the same, and a front plate and display device including the same.

Polyimide-based resins such as poly(amide-imide) (PAI), etc. have excellent friction, heat, and chemical resistance. , heat-resistant plate, heat-resistant adhesive, heat-resistant fiber and heat-resistant film.

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

In recent years, by filming polyimide, a polyimide-based film having excellent optical, mechanical and thermal properties while being cheaper has been developed. This polyimide-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 polyimide-based film is applied to a foldable display or a flexible display, there is a problem in that mechanical properties are deteriorated as the film is repeatedly folded or stretched/contracted. Additives are sometimes introduced to solve this problem, and in this case, optical properties may be deteriorated or compatibility may be deteriorated.

Therefore, there is a continuous need for research on the development of a film in which mechanical properties are maintained at a certain level or more even when folding or stretching/contraction is repeated.

An embodiment is to provide a polymer film having excellent folding characteristics and transparency and maintaining excellent mechanical properties even after repeated stretching and contraction in an elastic region, a method for manufacturing the same, and a front plate and display device including the same.

The polymer film for a display according to an embodiment includes a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin, and MOR _{0 / 9} of the following formula 1 is 2% or less.

×100<Equation 1> MOR _{0 /9} (%) =

×100

In Equation 1, MO0 means an initial modulus, and MO9 means a modulus measured after repeating extension and contraction 9 times until elongation becomes 2%.

A front panel for a display according to another embodiment includes a polymer film and a functional layer, wherein the polymer film includes a polymer resin selected from the group consisting of polyamide-based resins and polyimide-based resins, and MOR ₀ of Formula 1 _{/ 9} is less than 2%.

A display device according to another embodiment includes a display unit; and a front plate disposed on the display unit, wherein the front plate includes a polymer film, and the polymer film includes a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin, wherein the formula MOR _{0 / 9} of 1 is 2% or less.

A method of manufacturing a polymer film according to an embodiment includes preparing a solution containing a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin in an organic solvent; adding a solution containing the polymer resin to a tank; manufacturing a gel sheet by extruding and casting the polymer solution in the tank and then drying; and heat-treating the gel sheet, wherein the maximum temperature in the heat treatment step of the gel sheet is 300° C. or higher.

The polymer film according to the embodiment has excellent mechanical and optical properties by comprehensively controlling residual solvent content, heat treatment conditions, drying conditions, and the like, and can maintain excellent mechanical properties even after repeated stretching and contraction several times.

In addition, since the polymer film according to the embodiment can implement excellent folding characteristics, it can be usefully applied to a cover window for a display device, and 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 for manufacturing a polymer film according to an embodiment.
3 schematically shows a process facility for a polymer film according to an embodiment.

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

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 oil 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.

polymer film

The embodiment provides a polymer film having excellent folding properties and transparency, and maintaining excellent mechanical properties even after repeated stretching and contraction in an elastic region.

A polymer film according to an embodiment includes a polymer resin.

The polymer film has a MOR _{0 / 9} of 2% or less according to Equation 1:

×100<Equation 1> MOR _{0 /9} (%) =

×100

In Equation 1, MO0 means an initial modulus, and MO9 means a modulus measured after repeating extension and contraction 9 times until elongation becomes 2%.

Specifically, the MOR _{0 / 9} may be 1.8% or less, 1.6% or less, 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.05% or less, 0.1% or more, 0.2% or more, It is not limited.

In the polymer film according to the embodiment, MOR _{0 /9} according to Equation 1 satisfies the above range, so the change in modulus value is small even after repeated stretching and contraction, so the film has excellent durability and little deformation of mechanical properties It is easy to apply to a cover window and a display device.

In particular, since the change in the modulus value is small even after repeated stretching and contraction, it is suitable for application to a foldable display or a flexible display, which has recently been in the spotlight.

On the other hand, when the value of MOR _{0 /9} according to Equation 1 is out of the above range, when applied to a cover window for a display device, it is out of balance with other films or layers, so that interlayer separation or cracks may occur. Accordingly, the appearance of the film may deteriorate, and thus it is not suitable for application to a display device in which deformation of the film is repeated.

In repeating the stretching and contraction, the region where the elongation is 2% means the elastic region of the film. The more energy the material can store before plasticizing the film, the greater the extent of the elastic region. That is, the larger the range of the elastic region, the greater the resistance to plasticization and impact fracture, which means that the restoration after deformation is good.

The range of the elongation and contraction may be appropriately adjusted according to the range of the elastic region of the film. For example, the stretching and contraction may be repeated until the elongation is 3%. The stretching and contraction can be repeated until the elongation is 2.5%. The stretching and contraction can be repeated until the elongation is 2%.

In the case of the film according to the embodiment, the modulus was measured while repeating elongation and contraction until the elongation became 2%, where the area where the elongation was 2% was an elastic area, that is, the film could be retracted without breaking. means the area

The modulus was cut to 10 cm or more in the MD direction and 10 mm in the TD direction using Instron's universal testing machine UTM 5566A, mounted on a clip spaced 10 cm apart, and elongated at room temperature at a rate of 12.5 mm/min. After stopping when the elongation was 2%, a stress-strain curve was obtained and measured through the slope of the load to the initial strain.

In the polymer film, dMO _{0 / 9} represented by the following formula 2 is 0.18 GPa or less.

<Equation 2> dMO _{0 /9} (GPa) =

In Equation 2, MO0 means an initial modulus, and MO9 means a modulus measured after repeating extension and contraction 9 times until elongation becomes 2%.

Specifically, the dMO _{0 / 9} of the polymer film may be 0.16 GPa or less, 0.15 GPa or less, 0.13 GPa or less, 0.12 GPa or less, 0.10 GPa or less, 0.08 GPa or less, and may be 0.01 GPa or more, but is not limited thereto. .

In the polymer film according to the embodiment, the dMO _{0 /9} according to Equation 2 satisfies the above range, and thus the film has excellent durability even after repeated stretching and contraction, and thus it is easy to apply to cover windows and display devices, in particular, It is suitable for application to a foldable display or a flexible display.

When the initial modulus of the polymer film is MO0 and the measured modulus after repeating elongation and contraction n times until the elongation becomes 2% is MOn, the modulus standard deviation calculated based on a total of 10 values, MO0 to MO9 is 0.06 GPa or less.

Specifically, the modulus standard deviation of the polymer film may be 0.05 GPa or less, 0.04 GPa or less, or 0.03 GPa or less, and may be 0.01 GPa or more or 0.02 GPa or more, but is not limited thereto.

In relation to the measurement of the modulus standard deviation, specifically, the initial modulus is MO0, the modulus measured after one stretch/contraction is MO1, the modulus measured after two stretches/contractions is MO2, and the modulus measured after three stretches/contractions is MO3, the modulus measured after 4 extensions/contractions is MO4, the modulus measured after 5 stretches/contractions is MO5, the modulus measured after 6 stretches/contractions is MO6, and the modulus measured after 7 stretches/contractions is MO7 , the modulus measured after stretching/retracting 8 times is called MO8, and the modulus measured after stretching/retracting 9 times is called MO9, MO0, MO1, MO2, MO3, MO4, MO5, MO6, MO7, MO8 and MO9 The modulus standard deviation was calculated based on the value.

Since the standard deviation of the modulus of the polymer film satisfies the above range, it means that the change in modulus is small even after repeated stretching/contraction, that is, the modulus value is uniform, and the phenomenon that the modulus rapidly drops does not occur. This means that it is suitable for application to a display device in which mechanical properties must be maintained at a certain level or higher even when the film is continuously deformed.

The initial modulus (MO0) of the polymer film is 5 GPa or more.

Specifically, the initial modulus (MO0) of the polymer film may be 5.5 GPa or more, 5.8 GPa or more, 6.0 GPa or more, or 6.5 GPa or more, and may be 20 GPa or less or 15 GPa or less, but is not limited thereto.

The modulus (MO9) measured after repeating the stretching and contraction of the polymer film 9 times until the elongation is 2% is 5 GPa or more.

Specifically, the modulus (MO9) measured after repeating elongation and contraction 9 times until the elongation of the polymer film becomes 2% may be 5.5 GPa or more, 5.8 GPa or more, 6.0 GPa or more, or 6.5 GPa or more, 20 It may be GPa or less or 15 GPa or less, but is not limited thereto.

The residual solvent content in the polymer film is 2,000 ppm or less. For example, the residual solvent content may be 1,800 ppm or less, 1,500 ppm or less, 1,400 ppm or less, or 1,300 ppm or less, and may be 100 ppm or more, 200 ppm or more, 300 ppm or more, or 500 ppm or more, but is limited thereto. it is not

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 polymer film exceeds the above range, when the stretching and contraction are repeated in the elastic region, the modulus value is remarkably lowered and the durability of the film may be reduced, especially during post-processing of the film can affect Specifically, when the content of the residual solvent exceeds the above range, the hydrolysis of the film may be accelerated, thereby reducing mechanical properties or optical properties.

The IRS value represented by the following formula 3 of the polymer film is 100 or less.

+

<Equation 3> IRS =

+

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

Specifically, the IRS value of the polymer film may be 10 to 100, 20 to 100, 10 to 95, 10 to 92, 20 to 95, 30 to 100, 30 to 95, 40 to 100, or 40 to 95, It is not limited.

Since the IRS value of the polymer film satisfies the above range, it is possible to implement a film having excellent durability and excellent folding characteristics even after repeated stretching and contraction within the elastic region.

In particular, when the imide content (IM) is high or the content (RS) of the residual solvent in the film is high, and exceeds the above range, the long-term durability of the film is rapidly reduced. Specifically, if the amide content is too high and the amide content is relatively low or the residual solvent content is high, the hygroscopicity of the film is lowered and the modulus value is rapidly decreased as stretching and contraction are repeated.

The MPA value represented by the following formula 4 of the polymer film is 2% or less.

<Equation 4> MPA (%) = MOR _{0 /9} / AM

In Equation 4, AM means the number of moles of the amide repeating unit when the total number of moles of the imide repeating unit and the amide repeating unit in the film is 1 mole.

Specifically, the MPA may be 1.8% or less, 1.6% or less, 1.5% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.05% or less, 0.1% or more, 0.2% or more, but is limited thereto not.

In the polymer film according to the embodiment, the MPA value according to Equation 4 satisfies the above range, so even though the content of the amide repeating unit contained in the polymer is high, the change in the modulus value is small even after repeated stretching and contraction, so the film It has excellent durability and almost no deformation of mechanical properties, so it is easy to apply to cover windows and display devices.

In particular, compared to the amide content, the change in the modulus value is small even after repeated stretching and contraction, so it is suitable for application to a foldable display or a flexible display, which has recently been in the spotlight.

The polymer film according to the embodiment may improve mechanical properties by increasing the content of the amide repeating unit. In this case, the polymer film can be prevented from increasing the deviation of mechanical properties after repeated stretching and contraction by comprehensively and appropriately applying the composition, additives, residual solvent, and manufacturing process. That is, since the value of Equation 4 satisfies the above range, the polymer film has high mechanical properties, and deterioration of mechanical properties during the folding process of the polymer film can be prevented.

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

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

The polymer film can 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.

A polymer film according to an embodiment includes a polymer resin.

The polymer resin may be selected from the group consisting of a polyamide-based resin and a polyimide-based resin.

The polyamide-based resin is a resin including an amide repeating unit. The polyimide-based resin is a resin including an imide repeating unit. In addition, the resin including the imide repeating unit and including the amide repeating unit may be referred to as the polyamide-based resin, and may be referred to as the polyimide-based resin.

For example, the polymer resin may be a resin including a polyamide-based resin, a resin including a polyimide-based resin, or a resin including both a polyamide-based resin and a polyimide-based resin.

The polymer resin may be formed by polymerizing a diamine compound, a dianhydride compound, and optionally a dicarbonyl compound.

The polymer resin may be formed by simultaneously or sequentially reacting reactants including a diamine compound and a dianhydride compound. Specifically, the polymer resin is formed by polymerization of a diamine compound and a dianhydride compound.

Alternatively, the polymer resin may be formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound. In this case, the polymer resin 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.

The polymer film according to an embodiment includes a polymer resin, wherein the polymer resin is formed by polymerizing a diamine compound, a dianhydride compound, and a dicarbonyl compound, and the molar ratio of the dianhydride compound and the dicarbonyl compound is 0:100 to 50:50.

In another embodiment, the molar ratio of the dianhydride compound and the dicarbonyl compound may be 0:100 to 40:60, or 0:100 to 35:65, but is not limited thereto.

When the molar ratio of the dianhydride compound and the dicarbonyl compound is within the above range, excellent durability may be realized in optical properties, mechanical properties, and repeated many folding and stretching/contraction of the film. For example, when the molar ratio of the dicarbonyl compound is relatively increased, mechanical strength such as modulus may be decreased.

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-). 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/TFMB), but is not limited thereto.

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

The dianhydride compound is not particularly limited, but may be, for example, an aromatic dianhydride compound including an aromatic structure or an alicyclic dianhydride compound including an alicyclic structure.

For example, the aromatic dianhydride compound may be a compound of Formula 2 below.

<Formula 2>

In Formula 2, G is a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aliphatic ring group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaliphatic ring group, or a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aromatic ring group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaromatic ring group, and the aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group or the heteroaromatic ring group exists alone, or , are bonded to each other to form a condensed ring, a substituted or unsubstituted C ₁ -C ₃₀ alkylene group, a substituted or unsubstituted C ₂ -C ₃₀ alkenylene group, a substituted or unsubstituted C ₂ -C ₃₀ alkynylene group , -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si(CH ₃ ) ₂ -, -C(CH ₃ ) ₂ - and -C(CF ₃ ) ₂ - linked by a linking group selected from the group consisting of -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 addition, the alicyclic dianhydride compound may include a cyclobutane structure. Specifically, the alicyclic dianhydride compound may be CBDA (cyclobutane-1,2,3,4-tetracarboxylic dianhydride), but is not limited thereto.

In another embodiment, the dianhydride compound may include a compound having a fluorine-containing substituent, a compound having a biphenyl group, and a compound having a cyclobutane group. In this case, the fluorine-containing substituent may be a fluorinated hydrocarbon group, specifically, a trifluoromethyl group, but is not limited thereto.

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

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

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

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

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

<Formula A>

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

For example, the polyimide may include a repeating unit represented by the following Chemical Formula A-1, but is not limited thereto.

<Formula A-1>

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

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

<Formula 3>

In Formula 3,

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

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

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

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

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

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

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

<Formula B>

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

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

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

<Formula B-1>

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

<Formula B-2>

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

<Formula B-3>

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

According to one embodiment, the polymer resin may include an imide-based repeating unit and an amide-based repeating unit in a molar ratio of 0:100 to 50:50, 0:100 to 40:60, or 0:100 to 35:65. However, the present invention is not limited thereto.

When the molar ratio of the imide-based repeating unit and the amide-based repeating unit is within the above range, not only excellent mechanical and optical properties, but also a film capable of maintaining excellent mechanical properties even after repeated stretching and contraction several times can be implemented. . On the other hand, when the molar ratio of the amide-based repeating unit exceeds the above range, mechanical properties such as modulus may be deteriorated.

According to one embodiment, the polymer resin 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 ring group, a substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaliphatic ring group, a substituted or unsubstituted divalent C ₆ -C ₃₀ aromatic ring group, substituted or unsubstituted divalent C ₄ -C ₃₀ heteroaromatic ring group, substituted or unsubstituted C ₁ -C ₃₀ alkylene group, substituted or unsubstituted C ₂ -C ₃₀ alkenylene group , substituted or unsubstituted C ₂ -C ₃₀ alkynylene group, -O-, -S-, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si( CH ₃ ) ₂ -, -C(CH ₃ ) ₂ - and -C(CF ₃ ) ₂ -;

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

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

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

G is a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aliphatic ring group, a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaliphatic ring group, or a substituted or unsubstituted tetravalent C ₆ -C ₃₀ aromatic ring group , a substituted or unsubstituted tetravalent C ₄ -C ₃₀ heteroaromatic ring group, and the aliphatic ring group, the heteroaliphatic ring group, the aromatic ring group or the heteroaromatic ring group exists alone, or are fused to each other to form a condensed ring to form, a substituted or unsubstituted C ₁ -C ₃₀ alkylene group, a substituted or unsubstituted C ₂ -C ₃₀ alkenylene group, a substituted or unsubstituted C ₂ -C ₃₀ alkynylene group, -O-, - S-, -C(=O)-, -CH(OH)-, -S(=O) ₂ -, -Si(CH ₃ ) ₂ -, -C(CH ₃ ) ₂ - and -C(CF ₃ ) ) ₂ - connected by a linking group selected from among.

In the polymer resin, the molar ratio of the repeating unit represented by Formula A to the repeating unit represented by Formula B is 0:100 to 50:50, 0:100 to 40:60, or 0:100 to 35:65 may be, but is not limited thereto.

According to one embodiment, the polymer film may further include a filler.

The filler may be at least one selected from the group consisting of barium sulfate, silica and calcium carbonate. By including the filler, the polymer film may improve roughness and windability, as well as improve the effect of improving drivability and scratches during film production.

In addition, the particle diameter of the filler may be 0.01 μm or more and less than 1.0 μm. For example, the particle diameter of the filler may be 0.05 μm to 0.9 μm or 0.1 μm to 0.8 μm, but is not limited thereto.

The polymer film may include the filler in an amount of 0.01 to 3% by weight based on the total weight of the polymer film.

The transmittance of the polymer film is 80% or more. For example, the transmittance may be 85% or more, 87% or more, 88% or more, or 89% or more, and may be 99% or less, 98% or less, or 97% or less, but is not limited thereto.

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

When the haze of the polymer film exceeds the above range, transparency is lowered, and thus it is not suitable for application to a front panel or a display device. In addition, since the screen looks hazy and dark, there is a problem in that more power is consumed to maintain a brighter screen state to compensate for this.

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

For example, the transmittance of the polymer film is 80% or more, the haze is 1% or less, and the yellowness is 3% or less.

The compressive strength of the polymer film is 0.3 kgf/㎛ or more. Specifically, the compressive strength may be 0.4 kgf/㎛ or more, 0.45 kgf/㎛ or more, or 0.48 kgf/㎛ or more, but is not limited thereto.

When the polymer 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 including cracks (mm) is 65 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 polymer film has a surface hardness of HB or more. Specifically, the surface hardness may be H or more or 2H or more, but is not limited thereto.

The polymer film has a tensile strength of 14 kgf/mm ² or more. Specifically, the tensile strength may be 16 kgf/mm ² or more, 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 polymer film has an elongation of 13% or more. Specifically, the elongation may be 15% or more, 16% or more, 17% or more, or 17.5% or more, but is not limited thereto.

The polymer film according to one embodiment has excellent folding properties, and excellent mechanical properties are maintained even after repeated stretching and contraction in the elastic region, and has a high transmittance, low haze and yellowness, thereby providing a clean appearance and transparency. can be maintained, so it can be usefully applied to a foldable display device/flexible display device.

The above-described physical properties of the polymer film film are based on a thickness of 40 μm to 60 μm, or 70 μm to 90 μm. For example, the physical properties of the polymer film are based on a thickness of 50 μm or 80 μm.

The characteristics of the components and properties of the polymer film described above may be combined with each other.

In addition, the above-described physical properties of the polymer film are the results of the synthesis of the process conditions of each step in the method for producing the polymer film to be described later, together with the chemical and physical properties of the components constituting the polymer film.

For example, the polymer film according to the embodiment is excellent because various process conditions such as drying conditions and heat treatment conditions are synthesized in the method for producing a polymer film to be described later, as well as the type, content, and content of residual solvents of the monomers constituting the polymer film. physical properties can be realized.

front panel

The front plate according to an embodiment includes a polymer film and a functional layer.

The front panel may be a front panel for a display.

The polymer film includes a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin.

In addition, in the polymer film, MOR _{0 / 9} represented by Formula 1 is 2% or less.

A detailed description of the polymer film is the same as described above.

The front panel may be usefully applied to a display device.

The polymer film has excellent folding characteristics and transparency, and excellent mechanical properties are maintained even after repeated stretching and contraction in an elastic region, so that it can be usefully applied to a display front panel.

display device

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

In addition, the polymer film includes a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin.

Furthermore, in the polymer film, MOR _{0 / 9} represented by Formula 1 is 2% or less.

A detailed description of the polymer film and the front plate 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 front plate including a display unit 400 and a polymer film 100 having a first surface 101 and a second surface 102 on the display unit 400 and a functional layer 200 ( 300 , and an adhesive layer 500 is exemplified between the display unit 400 and the front panel 300 .

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

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

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

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

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

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

The front plate 300 may include a polymer 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 polymer film.

Method for manufacturing polymer film

One embodiment provides a method of manufacturing a polymer film.

A method of manufacturing a polymer film according to an embodiment includes: preparing a solution containing a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin in an organic solvent; adding a solution containing the polymer resin to a tank; manufacturing a gel sheet by extruding and casting the polymer solution in the tank and then drying; and heat-treating the gel sheet, wherein the maximum temperature in the heat treatment step of the gel sheet is 300° C. or higher.

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

The polymer film is a film in which a polymer resin selected from the group consisting of a polyamide-based resin and a polyimide-based resin is a main component.

In the method for producing the polymer film, the polymer solution for producing the polymer resin is a diamine compound and a dianhydride compound, or a diamine compound, a dianhydride compound, and a dicarbonyl compound in an organic solvent in a polymerization facility. Or sequentially mixed and prepared by reacting the mixture (S100).

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

In another embodiment, the preparing of the polymer solution includes: preparing a polyamic acid solution by mixing and reacting the diamine compound and the dianhydride compound in a solvent; and dehydrating the polyamic acid solution to prepare a polyimide (PI) solution.

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

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

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

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

For example, the polymer included in the polymer solution may include an imide repeating unit derived from polymerization of the diamine compound and the dianhydride compound.

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

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

When the content of the solids contained in the polymer solution is within the above range, the polyamide-imide film can be effectively prepared in the extrusion and casting processes. In addition, the prepared polymer film may maintain an excellent modulus value even after repeated stretching and contraction within the elastic region, and may exhibit a clean appearance and transparency.

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

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

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

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

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

Specifically, preparing the polymer solution comprises the steps of: (a) preparing a first polymer solution by simultaneously or sequentially mixing and reacting a diamine compound, a dianhydride compound, and optionally a dicarbonyl compound in an organic solvent; (b) measuring the viscosity of the first polymer solution to evaluate whether a target viscosity is reached; and (c) when the viscosity of the first polymer solution does not reach the target viscosity, adding the dianhydride compound or dicarbonyl compound to prepare a second polymer solution having the target viscosity; can

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, the present invention 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 is different from the stirring speed when preparing the second polymer solution. For example, the stirring speed when preparing the first polymer solution is faster than the stirring speed when preparing the second polymer solution.

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, may be adjusted to 4.5 to 7, but is not limited thereto.

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

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

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

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

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

The molar ratio of the dianhydride compound and the dicarbonyl compound used to prepare the polymer solution may be 0:100 to 50:50, 0:100 to 40:60, or 0:100 to 35:65. , but is not limited thereto.

By using the dianhydride compound and the dicarbonyl compound in such a molar ratio, it is advantageous to achieve a target level of mechanical properties and optical properties of the polyamide-imide film prepared from the polymer solution.

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

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

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

Specifically, the polymer solution includes a polymer resin, and the polymer solution is put into a tank.

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

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

Accordingly, in the manufacturing method according to an embodiment, the content of impurities is fundamentally minimized in the manufacturing process of the polymer solution, or even if predetermined impurities are present, they are appropriately controlled in a subsequent process to prevent deterioration of the physical properties of the final film. It has the advantage of producing a film without a separate precipitation or redissolving process.

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

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

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

The method of manufacturing the polymer film may further include performing vacuum defoaming on the polymer solution moved to the tank 20 .

The vacuum defoaming may be performed for 30 minutes to 3 hours after reducing the internal pressure of the tank to 0.1 bar to 0.7 bar. By performing vacuum defoaming under these conditions, 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.

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

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

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

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

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

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

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

The method for producing the polymer film includes extruding and casting the polymer solution in the tank 20 and drying the gel-sheet (S400).

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

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

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 to the above thickness range and dried and heat treated to form a final film, appropriate thickness and thickness uniformity can be ensured.

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

After casting the polymer solution, it is dried at a temperature of 60° C. to 150° C. for a time of 5 minutes to 60 minutes to prepare a gel-sheet. Specifically, the drying may be performed for a time of 10 minutes to 50 minutes with hot air of 60° C. to 120° C. More specifically, the drying may be performed for a time of 20 minutes to 40 minutes with hot air of 60°C to 100°C. For example, the drying may be performed for 30 minutes with hot air at 80°C.

During the drying, some 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 during drying may be 0.1 m/min to 15 m/min, for example, 0.5 m/min to 10 m/min, but is not limited thereto.

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

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

The heat treatment of the gel-sheet is performed in a range of 80° C. to 500° C. for 5 minutes to 180 minutes. Specifically, the heat treatment of the gel-sheet may be performed for 5 minutes to 150 minutes while raising the temperature at a rate of 2°C/min to 80°C/min in the range of 80°C to 500°C. More specifically, the heat treatment of the gel-sheet may be performed by raising the temperature at a rate of 2°C/min to 80°C/min in a temperature range of 80°C to 400°C. For example, the heat treatment of the gel-sheet may be performed by raising the temperature at a rate of 2°C/min to 80°C/min in a temperature range of 80°C to 380°C.

In addition, in the heat treatment step of the gel-sheet, the maximum temperature is 300 ℃ or more. Specifically, the maximum temperature may be 320 °C or higher and 350 °C or higher, but is not limited thereto.

In the heat treatment step of the gel-sheet, when the maximum temperature is less than the above range, the manufactured film exhibits a result of a rapid decrease in modulus as it repeats stretching and contraction, so it is not suitable for application to a foldable display or a flexible display. Do.

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

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

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

Specifically, the heat treatment may be performed until the content of the residual solvent contained in the film is 2,000 ppm or less.

For example, when the content of the residual solvent exceeds 2,000 ppm even after the heat treatment conditions of the gel-sheet are performed, the heat treatment may be performed one or more times.

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

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

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

By heat treatment under these conditions, the gel-sheet can be cured to have appropriate surface hardness and modulus, and the prepared cured film has excellent folding properties, optical properties, and excellent mechanical properties even after repeated stretching and contraction several times. can

The manufacturing method of the polymer film includes the step of cooling while moving the cured film (S600).

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

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

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

For example, 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.

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

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

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

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

At this time, the ratio of the moving speed of the gel-sheet on the belt during drying to the moving speed of the cured film during winding is 1:0.95 to 1:1.40. Specifically, the ratio of the moving speed may be 1:0.99 to 1:1.20, 1:0.99 to 1:1.10, or 1:1.10 to 1:1.05, but is not limited thereto.

When the ratio of the moving speed is out of the above range, there is a fear that mechanical properties of the cured film may be damaged, and there is a fear that flexibility and elastic properties may be deteriorated.

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

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

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

The polymer film may exhibit excellent anti-blocking properties, optical and mechanical properties by being manufactured according to the above-described manufacturing method. The polymer film may be applicable to various uses requiring durability and transparency. For example, the polymer film may be applied to a solar cell, a semiconductor device, a sensor, etc. in addition to a display device.

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

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

< Example >

Example One

After filling 250 kg of dimethylacetamide (DMAc) as an organic solvent under a nitrogen atmosphere at 20°C in a double-jacketed, temperature-controlled, 1,000L glass reactor, 2,2'-bis(trifluoromethyl)-, an aromatic diamine 40 kg of 4,4'-diaminobiphenyl (TFMB) was slowly added and dissolved.

Then, 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA), which is an aromatic dianhydride, was slowly added and stirred for 1 hour. Then, after adding isophthaloyl chloride (IPC) as the first dicarbonyl compound and stirring for 1 hour, as the second dicarbonyl compound, terephthaloyl chloride (TPC) was added 94% of the input mole, and then 1 A first polymer solution was prepared by stirring for an hour.

After measuring the viscosity of the prepared first polymer solution, if the measured viscosity does not reach the target viscosity, prepare a 10 wt% TPC solution in DMAc organic solvent and add 1 mL until a viscosity of 200,000 cps After that, the process of stirring for 30 minutes was repeated to prepare a second polymer solution.

Then, the second polymer solution was cast on a stainless steel belt and dried with hot air at 80° C. for 30 minutes to prepare a gel-sheet. Then, while moving the gel-sheet, the temperature was raised from 80° C. to 380° C. at a rate of 2° C./min to 80° C./min, heat-treated at the highest temperature for about 25 minutes, and then produced at a rate of about 800° C./min. After temperature reduction in one step, the temperature was reduced in a second step at a rate of about 100° C./min to obtain a base film, which was wound up using a winder.

With respect to the content of diamine compound (TFMB), dianhydride compound (6FDA, BPDA, CBDA), and dicarbonyl compound (IPC, TPC), based on 100 moles of diamine compound, dianhydride compound and dicarbonyl Table 1 shows the number of moles of the compound.

Example 2 to 6, comparative example 1 and 2

As shown in Table 1 below, a film was prepared in the same manner as in Example 1, except that the type, content, and maximum temperature during heat treatment were different for each reactant.

< evaluation example >

The films prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were measured and evaluated for the following physical properties, and the results are shown in Table 1 below.

evaluation example 1: Measuring the thickness of the film

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

evaluation example 2: Measurement of residual solvent in the film

After taking 0.02 g of the sample to be measured, using Purge&Trap-GC/MSD equipment, purging at 30°C for 1 hour, collecting the outgassing at 300°C for 10 minutes, and performing quantitative and qualitative analysis of outgassing, residual solvent was measured.

evaluation example 3: modulus measurement

Using Instron's universal testing machine UTM 5566A, the sample was cut to more than 10 cm in the MD direction and 10 mm in the TD direction, mounted on a clip with a gap of 10 cm, and elongated at 12.5 mm/min at room temperature while elongating at a rate of 2 By stopping when %, a stress-strain curve was obtained. In the stress-strain curve, the slope of the load with respect to the initial strain was defined as the modulus (GPa).

The modulus measurement was repeated as described above. Specifically, the initial modulus is MO0, the modulus measured after one stretch/contraction is MO1, the modulus measured after two stretches/contractions is MO2, the modulus measured after three stretches/contractions is MO3, and the modulus measured after four stretches/contractions is MO3. The measured modulus is MO4, the modulus measured after 5 stretches/contractions is MO5, the modulus measured after 6 stretches/contractions is MO6, the modulus measured after 7 stretches/contractions is MO7, and the modulus measured after 8 stretches/contractions The modulus is called MO8, and the modulus measured after stretching/retracting 9 times is called MO9, and the values of MO0 and MO9 are described in Table 1.

Based on the respective values of MO0 to MO9 (10 values in total), the modulus standard deviation during repeated stretching/contraction was calculated and described in Table 1.

evaluation example 4: transmittance and haze measurement

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

evaluation example 5: Yellowness measurement

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

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Furtherance diamine TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 TFMB 100 dianhide
ride 6FDA 5 6FDA 25 6FDA 25
BPDA 10 6FDA 25
CBDA 10 6FDA 5 6FDA 5 6FDA 25
BPDA 10 dicarbonyl
compound IPC 30
TPC 65 IPC 30
TPC 70 IPC 15
TPC 60 TPC 65 TPC 65 IPC 30
TPC 65 IPC 30
TPC 65 TPC 65 imide:
amide 5:95 0:100 25:75 35:65 35:65 5:95 5:95 35:65 Residual solvent in film (ppm) 1221 1186 1253 1120 1109 813 2209 2119 IRS value 66.05 59.3 87.65 91 90.45 45.65 115.45 140.95 MO0 (Gpa) 7.52 7.78 6.97 6.85 7.47 7.66 7.61 6.88 MO9 (Gpa) 7.49 7.7 6.98 6.91 7.52 7.61 7.42 6.64 Modulus standard deviation (Gpa) 0.03 0.03 0.02 0.03 0.03 0.02 0.07 0.08 dMO _{0 /9} (Gpa) 0.03 0.08 0.01 0.06 0.05 0.05 0.19 0.24 MOR _{0 /9} (%) 0.40 1.03 0.14 0.88 0.67 0.65 2.50 3.49 MPA (%) 0.42 1.03 0.19 1.35 1.03 0.68 2.63 5.37 Maximum temperature during heat treatment (℃) 350 350 350 350 350 380 250 250 thickness (um) 50 50 50 50 50 50 50 50 Permeability (%) 89 89.1 89 89 89 89 89 89 Haze (%) 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 yellowness 2.4 2.9 2.4 2.6 2.6 2.6 2.4 2.7

As can be seen in Table 1, the polymer films of Examples 1 to 6 all satisfy the modulus standard deviation of 0.06 or less, thereby confirming that the change in the modulus value is small even after repeated stretching and contraction.

In addition, the polymer films of Examples 1 to 6 had a MOR _{0 /10} value of 2% or less, and the change in modulus value was small even after repeated stretching and contraction within the elastic region. was found to be suitable for

On the other hand, in the case of the films according to Comparative Examples 1 and 2, the MOR _{0 /10} value shows a high value of 2.5% or more, and when applied to a cover window for a display device, cracks may occur due to imbalance with other layers, Defects may occur in terms of appearance stability. In particular, the films according to Comparative Examples 1 and 2 are not suitable for application to a foldable display device or a flexible display device in which the deformation of the film is continuously repeated.

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

Claims (13)

A polymer resin comprising a polyamide-based resin formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic or alicyclic dianhydride compound,
The content of residual solvent in the film is 2,000 ppm or less,
MOR _0/9 of the following formula 1 is 2% or less,
dMO _0/9 of the following formula 2 is 0.18 GPa or less,
The IRS value of Equation 3 is 100 or less,
Polymer film for display:
<Formula 1> MOR _0/9 (%) =

×100
<Equation 2> dMO _0/9 (GPa) =

<Equation 3> IRS =

+

In Equations 1 and 2, MO0 means the initial modulus, and MO9 means the modulus measured after repeating extension and contraction 9 times until the elongation becomes 2%,
In Equation 3, IM means the number of moles of the imide repeating unit when the total number of moles of the imide repeating unit and the amide repeating unit in the film is 100 moles, and RS is the content of residual solvent in the film ( ppm).
delete The method of claim 1,
When the initial modulus is MO0, and the modulus measured after repeating extension and contraction n times until the elongation becomes 2% is MOn, the standard deviation of the modulus calculated based on 10 values from MO0 to MO9 is 0.06 GPa or less. , polymer film for display.
The method of claim 1,
an initial modulus (MO0) of 5 GPa or more,
A polymer film for display, having a modulus (MO9) of 5 GPa or more, measured after repeating stretching and contraction 9 times until the elongation becomes 2%.
delete delete The method of claim 1,
A polymer film for a display, wherein the polymer resin contains an imide-based repeating unit and an amide-based repeating unit in a molar ratio of 0:100 to 50:50.
The method of claim 1,
The transmittance is 80% or more,
haze is less than 1%,
A polymer film for display that has a yellowness of 3 or less.
8. The method of claim 7,
The MPA value of Formula 4 is 2% or less, a polymer film for display:
<Equation 4> MPA (%) = MOR _{0 /9} / AM
In Equation 4, AM means the number of moles of the amide repeating unit when the total number of moles of the imide repeating unit and the amide repeating unit in the film is 1 mole.
Including a polymer film and a functional layer,
The polymer film comprises a polymer resin comprising a polyamide-based resin formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic or alicyclic dianhydride compound,
The content of the residual solvent in the film is 2,000 ppm or less,
MOR _0/9 of the following formula 1 is 2% or less,
dMO _0/9 of the following formula 2 is 0.18 GPa or less,
The IRS value of Equation 3 is 100 or less,
Front panel for display:
<Formula 1> MOR _0/9 (%) =

×100
<Equation 2> dMO _0/9 (GPa) =

<Equation 3> IRS =

+

In Equations 1 and 2, MO0 means the initial modulus, and MO9 means the modulus measured after repeating extension and contraction 9 times until the elongation becomes 2%,
In Equation 3, IM means the number of moles of the imide repeating unit when the total number of moles of the imide repeating unit and the amide repeating unit in the film is 100 moles, and RS is the content of residual solvent in the film ( ppm).
display unit; and
Including; a front plate disposed on the display unit;
The front plate comprises a polymer film,
The polymer film comprises a polymer resin comprising a polyamide-based resin formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic or alicyclic dianhydride compound,
The content of the residual solvent in the film is 2,000 ppm or less,
MOR _0/9 of the following formula 1 is 2% or less,
dMO _0/9 of the following formula 2 is 0.18 GPa or less,
The IRS value of Equation 3 is 100 or less,
Display device:
<Formula 1> MOR _0/9 (%) =

×100
<Equation 2> dMO _0/9 (GPa) =

<Equation 3> IRS =

+

In Equations 1 and 2, MO0 means the initial modulus, and MO9 means the modulus measured after repeating extension and contraction 9 times until the elongation becomes 2%,
In Equation 3, IM means the number of moles of the imide repeating unit when the total number of moles of the imide repeating unit and the amide repeating unit in the film is 100 moles, and RS is the content of residual solvent in the film ( ppm).
preparing a solution containing a polymer resin including a polyamide-based resin formed by polymerizing an aromatic diamine compound, an aromatic dicarbonyl compound, and optionally an aromatic or alicyclic dianhydride compound in an organic solvent;
adding a solution containing the polymer resin to a tank;
manufacturing a gel sheet by extruding and casting the polymer solution in the tank and then drying; and
Including; heat-treating the gel sheet;
The highest temperature in the heat treatment step of the gel sheet is 300 ° C. or more,
Performing the heat treatment until the content of the residual solvent contained in the film is 2,000 ppm or less,
The method for producing the polymer film of claim 1. delete

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