KR101922169B1 - Polyamide-imide film and display device comprising the same - Google Patents

Abstract

An embodiment is a polyamide-imide film which is colorless and transparent and has excellent mechanical properties and optical properties, and comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound and a dicarbonyl compound, Wherein the polyamide-imide film has a haze of not more than 5%, a haze of not more than 2%, a surface hardness of not less than HB, a light transmittance of not less than 85% measured at 550 nm, A polyamide-imide film having an average light transmittance of 50% or more as measured at 400 nm can be provided.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a polyamide-imide film,

The present invention relates to a polyamide-imide film which is colorless and transparent and has excellent mechanical properties and optical properties, and a display device including the polyamide-imide film.

Polyamide-imide (PAI) is excellent in friction, heat, and chemical resistance, and is widely used as a primary electrical insulating material, coating agent, adhesive, extrusion resin, heat resistant paint, heat resistant plate, And heat resistant films.

Polyamide-imide is used in various fields. For example, the polyamide-imide is in the form of a powder and is used as a coating agent such as a metal or a magnetic wire, and is mixed with other additives depending on the application. In addition, polyamide-imide, together with fluoropolymer, is used as a coating for decoration and corrosion prevention, and it plays a role of bonding the fluoropolymer to the metal substrate. The polyamide-imide is also used for coating kitchenware, and is also used as a membrane for gas separation because of its heat resistance and chemical resistance. In the natural gas wells, contaminants such as carbon dioxide, hydrogen sulfide and impurities are filtered And the like.

In recent years, a polyamide-imide film has been developed which is less expensive and has excellent optical, mechanical, and thermal characteristics by film-forming polyamide-imide.

The examples are to provide a polyamide-imide film which is colorless and transparent, but also has excellent mechanical properties and optical properties, and a display device including the polyamide-imide film.

The polyamide-imide film according to one embodiment comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound and a dicarbonyl compound, wherein the polyamide-imide film has a thickness of 50 , The haze is not more than 2%, the surface hardness is not less than HB, the light transmittance measured at 550 nm is not less than 85%, and the average light transmittance measured at 370 to 400 nm is not more than 50% or more.

A display device according to another embodiment includes a polyamide-imide film; And a photocurable adhesive layer, wherein the polyamide-imide film has a haze of not more than 5, a haze of not more than 2%, a surface hardness of not less than HB, The light transmittance is 85% or more, and the average light transmittance measured at 370 to 400 nm is 50% or more.

The polyamide-imide film according to the embodiment is colorless and transparent, but has excellent mechanical and optical properties.

In particular, since the transmittance of the UV region in the optical properties is high, it is easy to use as a cover window of a display device including a photocurable adhesive layer.

FIG. 1 is a graph showing light transmittance according to wavelengths of Example 1 and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail by way of examples. The embodiments can be modified into various forms as long as the gist of the invention is not changed.

As used herein, " comprising "means that other elements may be included unless otherwise specified.

The terms first, second, etc. are used herein to describe various components, and the components should not be limited by the term. The terms are used only for the purpose of distinguishing one component from another.

[ Polyamide - imide film]

The examples provide a polyamide-imide film which is colorless and transparent and has excellent mechanical properties and optical properties.

A polyamide-imide film according to one embodiment comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound.

Wherein the polyamide-imide polymer comprises an imide repeating unit derived from the polymerization of the aromatic diamine compound and the aromatic dianhydride compound and an amide derived from the polymerization of the aromatic diamine compound and the dicarbonyl compound amide repeat units.

The aromatic diamine compound is a compound that imide bonds with the aromatic dianhydride compound and forms an amide bond with the dicarbonyl compound to form a copolymer.

For example, the aromatic diamine compound may be 2,2'-bis (trifluoromethyl) -4,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl represented by the following formula 4'-diaminodiphenyl, TFDB), but is not limited thereto.

 [Chemical Formula 1]

Since the aromatic dianhydride compound has a low birefringence value, it can contribute to improvement of optical properties such as the transmittance of the polyamide-imide film.

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

For example, the aromatic dianhydride compound may include 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (2,2'-Bis- (3, 4-Dicarboxyphenyl) hexafluoropropane dianhydride, 6-FDA).

 (2)

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

The polyamic acid can then be converted to a polyimide through a dehydration reaction, and the polyimide includes imide repeating units.

For example, the polyimide may include a compound represented by the following formula (3), but is not limited thereto.

 (3)

N in the general formula (3) is an integer of 1 to 400.

The dicarbonyl compound may include a first dicarbonyl compound and / or a second dicarbonyl compound.

The first dicarbonyl compound and the second dicarbonyl compound may be an aromatic dicarbonyl compound.

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

For example, the first dicarbonyl compound and the second dicarbonyl compound may be aromatic dicarbonyl compounds different from each other, but the present invention 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 mechanical properties such as the surface hardness and the tensile strength of the polyamide- Can be improved.

The dicarbonyl compound may be terephthaloyl chloride (TPC), 1,1'-biphenyl-4,4'-dicarbonyl dichloride, BPDC), or a combination thereof.

For example, the first dicarbonyl compound may be 1,1'-biphenyl-4,4'-dicarbonyl dichloride (1,1'-biphenyl-4,4'-dicarbonyldichloride, BPDC). ≪ / RTI >

[Chemical Formula 4]

The second dicarbonyl compound may include terephthaloyl chloride (TPC) represented by the following formula (5), but is not limited thereto:

[Chemical Formula 5]

1,1'-biphenyl-4,4'-dicarbonyldibromide (BPDC) is used as the first dicarbonyl compound and terephthaloyl chloride (TPC) is used as the second dicarbonyl compound , The produced polyamide-imide film may have high oxidation resistance.

Also, the aromatic diamine compound and the dicarbonyl compound may be polymerized to form amide repeating units represented by Formulas (6) and (7).

[Chemical Formula 6]

(7)

X in the above formula (6) is an integer of 1 to 400.

Y in the general formula (7) is an integer of 1 to 400.

The polyamide-imide film according to another embodiment comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound, wherein the aromatic diamine compound is one kind of Wherein the aromatic dianhydride compound comprises one aromatic dianhydride compound, and the dicarbonyl compound may include two kinds of dicarbonyl compounds.

For example, the aromatic diamine compound may be 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl, TFDB ), Wherein the aromatic dianhydride compound is selected from the group consisting of 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6-FDA), and the dicarbonyl compound includes terephthaloyl chloride (TPC), 1,1'-biphenyl-4,4'-dicarbonyldichloride (1,1'- biphenyl-4,4'-dicarbonyl dichloride, BPDC), or combinations thereof.

Alternatively, the aromatic dianhydride compound is composed of one kind of diamine compound, the aromatic dianhydride compound is composed of one kind of aromatic dianhydride compound, and the dicarbonyl compound is composed of two kinds of dicarbonyl compounds .

For example, the aromatic diamine compound may be 2,2'-bis (trifluoromethyl) -4,4'-diaminodiphenyl, TFDB ), Wherein the aromatic dianhydride compound is at least one selected from the group consisting of 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 6-FDA), and the dicarbonyl compound is terephthaloyl chloride (TPC) and 1,1'-biphenyl-4,4'-dicarbonyldichloride (1,1'- biphenyl-4,4'-dicarbonyl dichloride, BPDC).

One embodiment is characterized in that it is possible to obtain a polyamide-imide film in which the imide repeating unit and the amide repeating unit content are appropriately controlled to provide a balance of optical characteristics, mechanical properties and flexibility without complicated processes. In addition, a polyamide-imide film having improved optical characteristics, mechanical properties, and flexibility can be obtained without the steps of precipitation, filtration, drying, and redissolution as in the conventional art.

The content of each of the imide repeating unit and the amide repeating unit may be controlled by the amounts of the aromatic dianhydride compound and the dicarbonyl compound.

In the polyamide-imide polymer contained in the polyamide-imide film, the molar ratio of the imide repeating unit to the amide repeating unit may be 50:50 to 20:80, but is not limited thereto.

When the molar ratio of the imide repeating unit to the amide repeating unit is in the above range, the polyamide-imide film is excellent in optical properties such as transmittance and haze.

The yellowness degree is 5 or less based on the thickness of the polyamide-imide film of 50 占 퐉. Specifically, the yellowness degree may be 3.8 or less, but is not limited thereto. More specifically, the yellowness may be 3 or less, or 2.8 or less, but is not limited thereto.

The haze is 2% or less based on the thickness of the polyamide-imide film of 50 m. Specifically, the haze may be 1.5% or less, but is not limited thereto. More specifically, the haze may be 0.8% or 0.6% or less, but is not limited thereto.

The surface hardness is at least HB, based on the thickness of the polyamide-imide film of 50 占 퐉. Specifically, the surface hardness may be H or higher, but the present invention is not limited thereto.

The light transmittance measured at 550 nm based on the thickness of the polyamide-imide film of 50 占 퐉 is 85% or more. Specifically, the light transmittance measured at 550 nm based on a thickness of 50 占 퐉 may be 88% or more or 89% or more, but is not limited thereto.

The average light transmittance measured at 370 to 400 nm is 50% or more based on the thickness of the polyamide-imide film of 50 占 퐉. Specifically, the average light transmittance measured at 370 to 400 nm on the basis of a thickness of 50 占 퐉 may be 52% or more, but is not limited thereto.

The average light transmittance is a value obtained by measuring light transmittance at wavelengths of 1 nm in the range of 370 to 400 nm.

The light transmittance measured at 370 nm is 10% or more based on the thickness of the polyamide-imide film of 50 占 퐉. Specifically, the light transmittance measured at 370 nm may be 11% or more or 12% or more based on a thickness of 50 占 퐉, but is not limited thereto.

The light transmittance measured at 388 nm is 60% or more based on the thickness of the polyamide-imide film of 50 占 퐉. Specifically, the light transmittance measured at 388 nm may be 62% or more or 64% or more based on a thickness of 50 占 퐉, but is not limited thereto.

The light transmittance measured at 400 nm based on the thickness of the polyamide-imide film of 50 占 퐉 is 65% or more. Specifically, the light transmittance measured at 400 nm may be 70% or more or 75% or more based on a thickness of 50 占 퐉, but the present invention is not limited thereto.

The tensile strength is not less than 20 kgf / mm ² based on the thickness of the polyamide-imide film of 50 μm. Specifically, the tensile strength may be 21 kgf / mm ^{2 or} more, but is not limited thereto.

The elongation is 10% or more based on the thickness of the polyamide-imide film of 50 占 퐉. Specifically, the elongation may be 11% or more, but is not limited thereto.

The modulus is 5.0 GPa or more based on the thickness of the polyamide-imide film of 50 탆. Specifically, the modulus may be 5.2 GPa or 5.3 GPa or higher, but is not limited thereto.

Various properties for the polyamide-imide films described above can be combined.

For example, the polyamide-imide film has a haze of not more than 5%, a haze of not more than 2%, a surface hardness of not less than HB, a light transmittance of not less than 85% measured at 550 nm, And the average light transmittance measured at 370 to 400 nm may be 50% or more.

As another example, the polyamide-imide film has a haze value of 3% or less, a haze value of 2% or less, a light transmittance of at least 85% as measured at 550 nm, a haze value of 370 to 400 nm , An average light transmittance of 50% or more, a tensile strength of 20 kgf / mm ² or more, and an elongation of 10% or more.

As another example, the polyamide-imide film comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound, and a dicarbonyl compound, wherein the aromatic diamine compound is 2,2 ' -Bis (trifluoromethyl) -4,4'-diaminodiphenyl (TFDB), and the aromatic dianhydride compound comprises 2 , 2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA), and the dicarbo The terephthaloyl chloride (TPC), 1,1'-biphenyl-4,4'-dicarbonyl dichloride (BPDC) or Wherein the polyamide-imide film has a thickness of 50 m and a yellowness value of 5 And, a haze of 2% or less, and the surface hardness is at least HB, and the light transmittance is 85% or more measured at 550 nm, an average light transmittance measured at 370 to 400 nm may be at least 50%.

[ Polyamide - Preparation method of imide film]

A method of producing a polyamide-imide film according to an embodiment is a method of polymerizing an aromatic diamine compound, an aromatic dianhydride compound and a dicarbonyl compound to prepare a polyamide-imide film having a viscosity of 100,000 to 500,000 cps, Preparing a polyamide-imide polymer solution having a molecular weight of 10,000 cps; And extruding and casting the polymer solution, followed by drying and heat treatment.

A process for producing a polyamide-imide film according to another embodiment comprises:

Polymerizing an aromatic diamine compound, an aromatic dianhydride compound, a first dicarbonyl compound and a second dicarbonyl compound in an organic solvent to obtain a first polymer solution; Further adding the second dicarbonyl compound to the first polymer solution to obtain a second polymer solution having a viscosity of 100,000 to 500,000 cps, specifically 150,000 to 350,000 cps; And extruding and casting the second polymer solution, followed by drying and heat-treating the second polymer solution.

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

The step of obtaining the first polymer solution may simultaneously or sequentially polymerize the aromatic diamine compound, the aromatic dianhydride compound, the first dicarbonyl compound, and the second dicarbonyl compound.

Specifically, in one embodiment, the step of obtaining the first polymer solution comprises simultaneously polymerizing the aromatic diamine compound, the aromatic dianhydride compound, the first dicarbonyl compound, and the second dicarbonyl compound have.

In another embodiment, the step of obtaining the first polymer solution comprises: polymerizing the aromatic diamine compound and the aromatic dianhydride compound to obtain a polyamic acid solution; And adding the first dicarbonyl compound and the second dicarbonyl compound to the polyamic acid solution and polymerizing the mixture. The polyamic acid solution is a solution containing polyamic acid.

In another embodiment, the step of obtaining the first polymer solution comprises: polymerizing the aromatic diamine compound and the aromatic dianhydride compound to obtain a polyamic acid solution; Conducting a dehydration reaction from the polyamic acid solution to obtain a polyimide solution; And polymerizing the polyimide solution by adding the first dicarbonyl compound and the second dicarbonyl compound to the polyimide solution. The polyimide solution is a solution containing a polymer having imide repeating units.

In another embodiment, the step of obtaining the first polymer solution comprises: polymerizing the aromatic diamine compound, the first dicarbonyl compound and the second dicarbonyl compound to obtain an amide polymer solution; And polymerizing the amide polymer solution by adding the aromatic dianhydride compound to the amide polymer solution. The amide polymer solution is a solution comprising a polymer having amide repeating units.

Wherein the copolymer contained in the first polymer solution contains an imide repeating unit derived from the polymerization of the aromatic dianhydride compound and the aromatic dianhydride compound and a second repeating unit derived from the polymerization of the aromatic diamine compound and the dicarbonyl compound ≪ / RTI > repeating units.

A catalyst may be further added after the step of obtaining the first polymer solution, the step of obtaining the second polymer, or the step of producing the second polymer.

Examples of the catalyst include, but are not limited to, beta-picoline or acetic anhydride.

By further adding the above-mentioned catalyst, the reaction rate can be increased and there is an effect of enhancing the bonding force between repeating unit structures or repeating unit structures.

In addition, the viscosity of the polymer solution can be appropriately adjusted in an extrusion process, such as addition of the catalyst, drying and remelting of the polymer solution, or addition of a solvent.

Another embodiment includes injecting the aromatic dianhydride, the first dicarbonyl compound and the second dicarbonyl compound into an excess of the aromatic diamine compound in the step of obtaining the first polymer solution.

Specifically, the aromatic dianhydride may be contained in an amount of 20 mol% to 50 mol% based on the total moles of the aromatic dianhydride, the first dicarbonyl compound, and the second dicarbonyl compound, But is not limited thereto.

When the content of the aromatic dianhydride is in the above range, the polyamide-imide film has excellent mechanical properties such as modulus, tensile strength, elongation and surface hardness.

The first dicarbonyl compound and the second dicarbonyl compound may be used in an amount of 50 mol% or more based on the total moles of the aromatic dianhydride, the first dicarbonyl compound and the second dicarbonyl compound, But it is not limited thereto.

 When the content of the dicarbonyl compound is within the above range, the polyamide-imide film has excellent optical properties such as light transmittance and haze.

In another embodiment, the first dicarbonyl compound and the second dicarbonyl compound are reacted in the step of obtaining the first polymer solution in an amount of 50 mol% to 70 Mol%, but the present invention is not limited thereto.

The first dicarbonyl compound is 1,1'-biphenyl-4,4'-dicarbonyl dichloride (BPDC), and the second dicarbonyl compound is 1,1'- The neil compound may be terephthaloyl chloride (TPC).

If the content of the first dicarbonyl compound is less than 50 mol%, the modulus of the polyamide-imide film may be lowered. If the content of the first dicarbonyl compound exceeds 70 mol%, optical properties such as haze may be deteriorated.

Preferably, in the step of obtaining the first polymer solution, an aromatic diamine compound having an i) an excessive amount of aromatic diamines equal to or more than the mole of the remaining reactant, ii) the aromatic dianhydride compound, the first dicarbonyl compound, Based on the total moles of the first dicarbonyl compound, the second dicarbonyl compound, and iii) the aromatic dianhydride compound, the first dicarbonyl compound, and the second dicarboyl compound, The first dicarbonyl compound and the second dicarbonyl compound in an amount of 50 mol% to 80 mol% based on the total molar amount of the first dicarbonyl compound and the second dicarbon compound.

Specifically, the first dicarbonyl compound (1,1'-biphenyl-4-thiophen-4-one) in an amount of 50 mol% to 70 mol%, based on the total moles of the first dicarbonyl compound and the second dicarbonyl compound , 4'-dicarbonyl dichloride (BPDC)) and 30 mol% to 50 mol% of the second dicarbonyl compound (terephthaloyl chloride, chloride, TPC).

In the step of obtaining the first polymer solution, the content of each of the imide repeating unit and the amide repeating unit is appropriately controlled, so that the optical characteristics, mechanical properties, and flexibility can be obtained without conventional processes such as precipitation, filtration, This balanced and improved polyamide-imide film can be obtained.

After the step of obtaining the first polymer solution, the second polymer solution having a viscosity of 100,000 to 500,000 cps can be obtained by further adding the second dicarbonyl compound to the first polymer solution.

The weight ratio of the second dicarbonyl compound added in the step of obtaining the first polymer solution and the second dicarbonyl compound added in the step of obtaining the second polymer solution may be 90:10 to 99: 1, But is not limited thereto.

In addition, the second dicarbonyl compound to be added in the step of obtaining the second polymer solution may be used as a second dicarbonyl compound solution prepared by mixing with an organic solvent at a concentration of 5 to 20 wt% no.

This is advantageous in that the desired viscosity can be achieved accurately.

The viscosity of the second polymer solution may be from 100,000 to 500,000 cps, or from 150,000 to 350,000 cps, but is not limited thereto.

When the viscosity of the second polymer solution is in the above range, the polyamide-imide film can be effectively produced in the extrusion and casting process. In addition, the polyamide-imide films produced may have improved mechanical properties such as modulus.

According to one embodiment, the amount of solids contained in the second polymer solution may be from 10% to 20% by weight. Specifically, the content of the solid content contained in the second polymer solution may be 12 wt% to 18 wt%, but is not limited thereto.

When the content of the solid content contained in the second polymer solution is in the above range, the polyamide-imide film can be effectively produced in the extrusion and casting process. In addition, the polyamide-imide films produced may have optical properties such as improved mechanical properties such as modulus and low yellowing.

After obtaining the second polymer solution, the pH of the second polymer solution can be adjusted by adding a neutralizing agent.

Examples of the neutralizing agent include, but are not limited to, amine-based neutralizing agents such as alkoxyamine, alkylamine or alkanolamine.

The neutralizing agent may be added in an amount of about 0.1 mol% to about 10 mol% based on the total moles of monomers in the polyamide-imide polymer solution.

The pH of the second polymer solution adjusted via the neutralizing agent may be from about 4 to about 7. Specifically, the pH of the controlled second polymer solution may be from about 4.5 to about 7. [

When the pH of the second polymer solution is in the above-described range, it is possible to prevent damage to equipment caused in the extrusion and casting process described below. In addition, the polyamide-imide film produced may have an effect in terms of mechanical properties such as lowering the yellowness degree of the polyamide-imide film and improving the optical property and modulus, such as preventing the increase in yellow color.

After the step of obtaining the second polymer solution, the second polymer solution may be extruded and cast, dried, and heat treated to produce a polyamide-imide film.

In the extrusion and casting process, the above-mentioned organic solvent may be used.

The second polymer solution is extruded and cast into a casting body, such as a casting roll or casting belt. At a rate of from about 5 m / min to about 15 m / min, and in a thickness of from 400 to 500 m, to the casting body. When the extrusion and casting speed is within the above range, the polyamide-imide film produced by the manufacturing method according to the embodiment can have improved optical and mechanical properties.

That is, when the second polymer solution has the above-mentioned viscosity, extrusion and casting at such an extrusion rate can be advantageous to have improved optical and mechanical properties.

After the second polymer solution is cast into the casting body, the solvent contained in the second polymer solution is removed by a drying process, whereby a gel sheet is formed on the casting body.

The drying process may be conducted at a temperature of about 60 ° C to about 150 ° C for a time of about 5 minutes to about 60 minutes.

Thereafter, the gel sheet is subjected to a heat treatment in an atmospheric environment to produce the polyamide-imide film according to the embodiment.

The heat treatment process may be conducted at a temperature of about 60 ° C to about 470 ° C for about 5 minutes to about 20 minutes. More specifically, the heat treatment process can be conducted for about 5 minutes to about 15 minutes in an inline heat treatment apparatus having an inlet temperature of about 80 캜 to about 300 캜 and an elevated temperature condition of 1 캜 / min to 25 캜 / min .

Since the polyamide-imide polymer has high oxidation resistance, it is hardly affected by oxygen contained in the atmosphere during the heat treatment process. Thus, the polyamide-imide films according to the embodiments can have improved optical properties.

Further, in the prior art, in the production of a polyimide film, the yellowing of the film is prevented and the transparency is secured by nitrogen gas purging during the heat treatment in the film formation process. However, according to the embodiment, -Imide film can be obtained.

[Display device]

Another embodiment provides a display device comprising a polyamide-imide film which is colorless and transparent but has excellent mechanical properties and optical properties.

A display device according to one embodiment includes a polyamide-imide film; And a photocurable adhesive layer.

For a description of the polyamide-imide film, refer to the description given in [Polyamide-imide film] and [Manufacturing method of polyamide-imide film].

In one embodiment, the display device comprises a polyamide-imide film; And a photo-curable adhesive layer, wherein the polyamide-imide film comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound and a dicarbonyl compound, wherein the aromatic dianhydride The compound may be composed of a compound having a fluorine-containing substituent.

The photocurable adhesive layer may be formed on one side of the polyamide-imide film.

In this instance, forming "on" includes all that is "directly" or "indirectly" formed.

That is, the photo-curable adhesive layer may be directly formed on one side of the polyamide-imide film, and at least one layer may be interposed between the polyamide-imide film and the photo-curable adhesive layer.

The photocurable adhesive layer is a cured adhesive layer by irradiating light in the UV region. Specifically, the photocurable adhesive layer may be a cured adhesive layer by irradiating light of 370 to 400 nm.

In addition, in the display device including the polyamide-imide film and the photo-curable adhesive layer, the photo-curable adhesive layer is formed by irradiating light of 370 to 400 nm transmitted through the polyamide-imide film to form a cured adhesive layer have.

The polyamide-imide film is characterized in that it does not contain a UV absorber. The UV absorber may be selected from the group consisting of benzophenone, oxanilide, benzotriazole and triazine, but is not limited thereto.

The polyamide-imide film can be used as a cover window in the display device.

The cover window is located at the outermost portion of the display device and serves to protect the display panel. Further, the cover window may further include a hard coating layer in addition to the polyamide-imide film, but is not limited thereto.

When the polyamide-imide film is used as a cover window of the display device, the polyamide-imide film has improved mechanical characteristics and optical characteristics, and can be applied to a flexible display such as a foldable display to realize an improved folding property. That is, the display device according to the embodiment may be a flexible display. The cover window can be easily bent, and the display device according to the embodiment can have improved image quality and improved folding and bending properties.

[ Example ]

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example  One

710.8 g of dimethylacetamide (DMAc) as an organic solvent was charged in a 1 L glass reactor equipped with a temperature controllable double jacket under a nitrogen atmosphere at 20 ° C, and then 2,2'-bis (trifluoromethyl) -4 , And 64 g (0.2 mol) of 4'-diaminobiphenyl (TFDB) were slowly added to dissolve.

Subsequently, 26.6 g (0.06 mol) of 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA) as an aromatic dianhydride was slowly added thereto and stirred for 1 hour.

Then, 23.4 g (0.084 mol) of 1,1'-biphenyl-4,4'-dicarbonyldichloride (BPDC) as a first dicarbonyl compound was added and stirred for 1 hour to obtain a second dicarbonyl compound (0.074 mol) of terephthaloyl chloride (TPC) was added in an amount of 96% based on the molar amount of the reaction mixture, and the mixture was stirred for 1 hour to prepare a first polymer solution.

When the viscosity of the prepared first polymer solution was measured and the measured viscosity did not reach the target viscosity, a 10 wt% TPC solution was prepared in DMAc organic solvent until the viscosity became 200,000 cps, and 1 mL was added And then stirring for 30 minutes was repeated to prepare a second polymer solution.

The second polymer solution was coated on a glass plate and then dried with hot air at 80 DEG C for 30 minutes. The dried polyamide-imide polymer was peeled off from the glass plate, and fixed on a pin frame. The temperature was raised at a rate of 2 ° C / min in a temperature range of 80 to 300 ° C to obtain a polyamide-imide film having a thickness of 50 μm.

According to Example 1, the yield reaches about 100% immediately before the film formation (just before coating). In this specification, 'yield' refers to the mole of the material remaining in the solution for coating, ).

According to the conventional production method, the yield immediately before the film-forming step is about 60%, because the loss of the material inevitably occurs at the steps of polyimidization, precipitation, filtration and drying.

Comparative Example  One

710.8 g of dimethylacetamide (DMAc) as an organic solvent was charged in a 1 L glass reactor equipped with a temperature controllable double jacket under a nitrogen atmosphere at 20 ° C, and then 2,2'-bis (trifluoromethyl) -4 , And 64 g (0.2 mol) of 4'-diaminobiphenyl (TFDB) were slowly added to dissolve.

Subsequently, 26.6 g (0.06 mol) of 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6-FDA), which is an aromatic dianhydride, was slowly added thereto and stirred for 1 hour , And 6.47 g (0.22 mol) of 3,3'4,4'-biphenyltetracarbonyl dianhydride (BPDA) were slowly added thereto while stirring for 1 hour.

Then, 23.4 g (0.084 mol) of 1,1'-biphenyl-4,4'-dicarbonyldichloride (BPDC) as a first dicarbonyl compound was added and stirred for 1 hour to obtain a second dicarbonyl compound (0.074 mol) of terephthaloyl chloride (TPC) was added in an amount of 96% based on the molar amount of the reaction mixture, and the mixture was stirred for 1 hour to prepare a first polymer solution.

When the viscosity of the prepared first polymer solution was measured and the measured viscosity did not reach the target viscosity, a 10 wt% TPC solution was prepared in DMAc organic solvent until the viscosity became 200,000 cps, and 1 mL was added And then stirring for 30 minutes was repeated to prepare a second polymer solution.

The second polymer solution was coated on a glass plate and then dried with hot air at 80 DEG C for 30 minutes. The dried polyamide-imide polymer was peeled off from the glass plate, and fixed on a pin frame. The temperature was raised at a rate of 2 ° C / min in a temperature range of 80 ° C to 300 ° C to obtain a polyamide-imide film having a thickness of 50 μm.

[ Evaluation example ]

The properties of the polyamide-imide films according to Example 1 and Comparative Example 1 were measured and evaluated. The results are shown in the following Table 1 and FIG.

Evaluation example  1: Measurement of film thickness

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

Evaluation example  2: Light transmittance  And Hayes (HZ) measurement

The light transmittance and haze at 550 nm were measured using a haze meter NDH-5000W manufactured by Denso Corporation of Japan. Further, using an UV-VIS SPECTROPHOTOMETER (UV-2450) manufactured by Shimadzu Corporation of Japan, the average light transmittance at 370 to 400 nm, the light transmittance at 370 nm, the light transmittance at 388 nm and the light transmittance at 400 nm were measured . The results of light transmittance according to wavelength for each of the films prepared in Example 1 and Comparative Example 1 are shown graphically in FIG.

Evaluation example  3: Yellowness ( YI ) Measure

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

Evaluation example  4: Modulus modulus measurement

Using an Instron universal testing machine UTM 4206-001, the sample was cut at a distance of 5 cm or more in the direction orthogonal to the main shrinkage direction of the sample and 15 mm in the main shrinkage direction, mounted on a clip spaced 5 cm apart, Stress-strain curves were obtained until this occurred. The modulus (GPa) was defined as the force applied when the fracture occurred.

Evaluation example  5: Surface hardness measurement

The surface hardness was measured with a pencil hardness measuring instrument (CT-PC1, CORE TECH, Korea) with a pencil hardness measuring pencil at a 45 ° angle and a pencil speed of 300 mm / min while applying a constant load (750 g). The pencil used was a Mitsubishi pencil, and pencils indicating the strength of H-9H, F, HB, B-6B and the like were used.

Item unit Example  One Comparative Example  One thickness ㎛ 50 50 Light Transmittance (@ 550 nm) % 89.8 89.7 Hz % 0.53 0.52 YI - 2.56 3.96 Modulus GPa (room temperature) 5.33 4.52 Surface hardness H H Average light transmittance
(370-400 nm) % 53.4 19.6 UV transmittance (@ 370 nm) % 12.0 0.0 UV Transmittance (@ 388 nm) % 64.3 21.4 UV Transmittance (@ 400 nm) % 78.1 57.3

As can be seen from the above Table 1, it was confirmed that Example 1 was colorless and transparent compared to Comparative Example 1, but also excellent mechanical and optical properties. In particular, it was confirmed that Example 1 is easier to use as a cover window of a display device including a photocurable adhesive layer because the transmittance of the UV region in optical properties is higher than that of Comparative Example 1.

Claims (13)

delete delete delete delete delete delete delete delete Polyamide-imide film; And
1. A display device comprising a light curable adhesive layer,
Wherein the polyamide-imide film comprises a polyamide-imide polymer formed by polymerizing an aromatic diamine compound, an aromatic dianhydride compound and a dicarbonyl compound,
Wherein the dicarbonyl compound is an aromatic dicarbonyl compound,
Wherein the polyamide-imide film has a haze value of not more than 5, a haze value of not less than HB, a surface hardness of not less than HB, an elongation of not less than 10%, a light transmittance measured at 550 nm The light transmittance measured at 370 nm is 10% or more, the light transmittance measured at 388 nm is 60% or more, the average light transmittance measured at 370 to 400 nm is 50% or more,
The photocurable adhesive layer is cured by irradiating light of 370 to 400 nm transmitted through the polyamide-imide film,
Wherein the polyamide-imide film does not comprise a UV absorber. 10. The method of claim 9,
Wherein the aromatic dianhydride compound is composed of a compound having a fluorine-containing substituent. delete delete delete

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