KR101811253B1 - Colorless and transparent polyamide-imide flim and preparation method of the same - Google Patents

Abstract

The present invention relates to a polyamide-imide film having transparency and characteristics of realizing surface hardness and mechanical properties, and a process for producing the polyamide-imide film.
The polyamide-imide film according to one aspect of the present invention comprises a copolymer of a unit structure derived from TFDB, 6-FDA, BPDC and TPC, wherein the TFDB forms an imide structure with 6-FDA, TFDB forms an amide structure with TPC or BPDC, and the unit structure derived from the 6-FDA and the unit structure derived from TPC and BPDC, relative to 100 mol% of the unit structure derived from TPC and BPDC, is 50 to 80 mol% And a unit structure derived from BPDC is copolymerized in an amount of 50 to 70 mol% with respect to 100 mol% of a unit structure derived from TPC and BPDC.
The polyamide-imide film according to the present invention can have transparency, excellent surface hardness and mechanical properties from polyamide-imide type copolymerized polyamide structure and polyimide structure.

Description

COLORLESS AND TRANSPARENT POLYAMIDE-IMIDE FLIM AND PREPARATION METHOD OF THE SAME Technical Field [1] The present invention relates to a colorless transparent polyamide-

The present invention relates to a polyamide-imide film which is colorless and transparent and has excellent mechanical properties such as surface hardness and a method for producing the polyamide-imide film.

The polyimide resin is a high heat resistant resin imidized by ring closure of a polyamic acid derivative solution-polymerized with an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate at a high temperature.

Examples of the aromatic dianhydride include pyromellitic dianhydride (PMDA) or biphenyltetracarboxylic dianhydride (BPDA), and the aromatic diamines include oxydianiline (ODA), p-phenylenediamine (p- PDA), m-phenylenediamine (m-PDA), methylene dianiline (MDA), and bisaminophenylhexafluoropropane (HFDA).

The polyimide resin is excellent in heat resistance, oxidation resistance, heat resistance, radiation resistance, low temperature characteristics, and chemical resistance. Therefore, it is widely used as an electronic material such as heat-resistant high-temperature material such as automobile material, air material, space ship material, insulating coating, insulation film, semiconductor, electrode protection film of TFT-LCD.

However, the polyimide resin has a high aromatic ring density and is colored in brown or yellow. Therefore, there is a limit in that it is difficult to use the film in a product requiring transparency.

Accordingly, there have been many attempts to improve the transparency of the polyimide film. As a part of the Korea 10-2003-0009437 Unexamined Publication No. -O-, -SO ₂ -, such as monomers of the connector, connected to the bent structure m- location other than the p- position, such as, -CF ₃ -, CH ₂ The problem of transparency and color transparency was solved with the use of aromatic dianhydride having a substituent and an aromatic diamine monomer as long as the thermal properties were not significantly deteriorated. However, the mechanical properties such as birefringence characteristics, surface hardness, and elastic modulus deteriorate and it was difficult to use it for a display.

Therefore, there is still a need for research to provide a polyimide film excellent in mechanical properties such as optical properties such as transparency and surface hardness.

Korean Laid-Open Publication No. 10-2003-0009437

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and limitations and has the following purpose.

It is an object of the present invention to provide a polyamide-imide film excellent in both mechanical and optical properties without the introduction of inorganic particles by properly mixing polyimide and polyamide.

The object of the present invention is not limited to the above-mentioned object. The objects of the present invention will become more apparent from the following description, which will be realized by means of the appended claims and their combinations.

In order to achieve the above object, the present invention can include the following configuration.

The colorless transparent polyamide-imide films according to the present invention can be prepared by reacting TFDB (2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl), 6-FDA (2,2- , 4-dicarboxyphenyl) hexafluoropropane dianhydride), BPDC (1,1-biphenyl-4,4-dicarbonyldichloride), and TPC (terephthaloyl chloride) Wherein the TFDB forms an imide structure with 6-FDA, the TFDB forms an amide structure with TPC and BPDC, and the unit structure derived from the 6-FDA and the unit structure derived from TPC and BPDC The unit structure derived from TPC and BPDC may be copolymerized in an amount of 50 to 80 mol% with respect to 100 mol%.

In a preferred embodiment of the present invention, a unit structure derived from BPDC is copolymerized in an amount of 50 to 70 mol% relative to 100 mol% of a unit structure derived from TPC and BPDC.

The method for preparing a colorless transparent polyamide-imide film according to the present invention comprises the steps of charging 6-FDA into a solution in which TFDB is dissolved, reacting with BPDC, and reacting with TPC To produce a polyamic acid solution; And preparing a polyamide-imide film using the polyamic acid solution. The total amount of the TPC and BPDC may be 50 to 80 mol% based on 100 mol% of TFDB.

In a preferred embodiment of the present invention, the amount of the BPDC may be 50 to 70 mol% based on 100 mol% of the total amount of the TPC and BPDC.

The polyamide-imide film according to the present invention can be used in a flexible display or a cover window.

The present invention includes the above-described configuration, and thus has the following effects.

The polyamide-imide film according to the present invention is colorless and transparent and has excellent mechanical properties such as surface hardness and elastic modulus.

Accordingly, the polyamide-imide film according to the present invention is suitable for application to an optical film for a flexible display, a film for a cover window, and the like.

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

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention. As used herein, " comprising "means that other elements may be included unless otherwise specified.

The polyamide-imide film of the present invention is a film obtained by mixing TFDB (2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl), 6-FDA (2,2- Bisphenyl phenyl) hexafluoropropane dianhydride), BPDC (1,1-biphenyl-4,4-dicarbonyldichloride), and TPC (terephthaloyl chloride) Wherein the TFDB forms an imide structure with 6-FDA, the TFDB forms an amide structure with TPC and BPDC, and the unit structure derived from the 6-FDA and the TPC derived from TPC and BPDC The unit structure derived from TPC and BPDC is copolymerized in an amount of 50 to 80 mol% based on 100 mol% of the unit structure.

If the unit structure derived from the 6-FDA and the unit structure derived from TPC and BPDC is less than 50 mol% with respect to 100 mol% of the unit structure derived from TPC and BPDC, the surface hardness may be lowered, It can be easily damaged by friction or the like.

In addition, the modulus of the film may be lowered, and thus may be difficult to be used for an optical film for a flexible display and a film for a cover window.

If the unit structure derived from 6-FDA and the unit structure derived from TPC and BPDC from the 100 mol% of the unit structure derived from TPC and BPDC exceeds 80 mol%, the imide structure may be insufficient and the transparency may be lowered. Therefore, it may be difficult to use for a display film or the like.

Therefore, it is preferable that the polyamide-amide film has a unit structure derived from 6-FDA and a unit structure derived from TPC and BPDC of 50 to 80 mol% based on 100 mol% of the unit structure derived from TPC and BPDC.

The polyamide-imide film of the present invention has a unit structure derived from 6-FDA and a unit structure derived from TPC and BPDC of 50 mol% to 100 mol% of a unit structure derived from TPC and BPDC, and is composed of TPC and BPDC And 50 to 70 mol% of a unit structure derived from BPDC relative to 100 mol% of the derived unit structure.

When the unit structure derived from BPDC is less than 50 mol% as compared with 100 mol% of the unit structure derived from TPC and BPDC, the modulus of elasticity is lowered and the unit film is easily deformed by external force, so that an optical film for a flexible display and a cover window, It may be difficult to use it for a film or the like.

Also, when the unit structure derived from BPDC is more than 70 mol% based on 100 mol% of the unit structure derived from TPC and BPDC, a haze phenomenon may occur severely and yellowing may occur due to an increase in yellow index . This may lower the transmittance and thus may be difficult to use as a display film.

Thus, the polyamide-imide film has a unit structure derived from 6-FDA and a unit structure derived from TPC and BPDC in an amount of 50 to 80 mol% relative to 100 mol% of a unit structure derived from TPC and BPDC, and is derived from TPC and BPDC Is preferably copolymerized in an amount of 50 to 70 mol% based on 100 mol% of the unit structure derived from BPDC.

The imide structure of 6-FDA-TFDB contributes to transparency, the amide structure of TPC-TFDB contributes to surface hardness, and the amide structure of BPDC-TFDB contributes to surface hardness and modulus.

According to another aspect of the present invention, there is provided a method for producing a polyamic acid solution, which comprises reacting 6-FDA in a solution in which TFDB is dissolved, reacting BPDC and reacting the mixture with TPC, ; And preparing a polyamide-imide film using the polyamic acid solution, wherein the total amount of the TPC and BPDC is 50 to 80 mol% based on 100 mol% of TFDB .

The amount of the BPDC may be 50 to 70 mol% based on 100 mol% of the total amount of the TPC and BPDC.

The solvent for the polymerization reaction is not particularly limited as long as it is a solvent that dissolves the above monomers. As the known reaction solvent, there may be used, for example, m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO) One or more polar solvents may be used.

Although the content of the solvent is not particularly limited, the content of the solvent is preferably from 40 to 95% by weight, more preferably from 50 to 90% by weight, in order to obtain a suitable molecular weight and viscosity of the solution.

The reaction conditions are not particularly limited, but the reaction temperature is preferably -20 to 80 占 폚, and the reaction time is preferably 30 minutes to 24 hours. It is more preferable that the reaction atmosphere is an inert atmosphere such as argon or nitrogen.

The thickness of the obtained polyamide-imide film is not particularly limited, but is preferably in the range of 10 to 250 탆, more preferably 25 to 150 탆.

Hereinafter, embodiments of the present invention will be described in detail as specific examples for carrying out the present invention. It is to be understood, however, that these examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention.

Example  One : Polyamide - Imide  Production of film

710.8 g of dimethylacetamide (DMAc) was charged in a 1 L glass reactor equipped with a temperature controllable double jacket under a nitrogen atmosphere at 20 캜, and 2,2'-bis (trifluoromethyl) -4,4'-diamino 64 g (0.2 mol) of biphenyl (2,2'-TFDB) was slowly added and dissolved, and then 2,6-bis (3,4-dicarboxyphenyl) hexafluoropropanediol hydride (0.06 mol) was slowly added thereto and stirred for 1 hour.

Then, 23.4 g (0.084 mol) of 1,1-biphenyl-4,4-dicarbonyldichloride (BPDC) was added thereto, followed by stirring for 1 hour. 11.4 g (0.056 mol) of terephthaloyl chloride (TPC) was added and stirred for 1 hour to prepare a polymerization solution.

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

Example  2

A film was prepared in the same manner as in Example 1 except that 26.6 g (0.06 mol) of 6-FDA, 27.3 g (0.098 mol) of BPDC and 8.5 g (0.042 mol) of TPC were added.

Example  3

A film was prepared in the same manner as in Example 1 except that 35.5 g (0.08 mol) of 6-FDA, 20 g (0.072 mol) of BPDC and 9.8 g (0.048 mol) of TPC were added.

Example  4

A film was prepared in the same manner as in Example 1 except that 44.3 g (0.1 mol) of 6-FDA, 16.7 g (0.06 mol) of BPDC and 8.1 g (0.04 mol) of TPC were added.

Comparative Example  One

A film was prepared in the same manner as in Example 1, except that 26.6 g (0.06 mol) of 6-FDA and 28.5 g (0.14 mol) of TPC were added without adding BPDC.

Comparative Example  2

A film was prepared in the same manner as in Example 1, except that 26.6 g (0.06 mol) of 6-FDA and 39 g (0.14 mol) of BPDC were added without TPC.

Comparative Example  3

A film was prepared in the same manner as in Example 1 except that 17.7 g (0.04 mol) of 6-FDA and 32.6 g (0.16 mol) of TPC were added without adding BPDC.

Comparative Example  4

A film was prepared in the same manner as in Example 1 except that 26.6 g (0.06 mol) of 6-FDA, 31.2 g (0.112 mol) of BPDC and 5.7 g (0.028 mol) of TPC were added.

Comparative Example  5

A film was prepared in the same manner as in Example 1 except that 44.3 g (0.1 mol) of 6-FDA and 20.3 g (0.1 mol) of TPC were added without adding BPDC.

Comparative Example  6

A film was prepared in the same manner as in Example 1, except that 62.1 g (0.14 mol) of 6-FDA, 10 g (0.036 mol) of BPDC and 4.9 g (0.024 mol) of TPC were added.

Comparative Example  7

A film was prepared in the same manner as in Example 1 except that 8.9 g (0.02 mol) of 6-FDA and 30 g (0.108 mol) of BPDC and 14.6 g (0.072 mol) of TPC were added.

The amounts of the components in the above Examples and Comparative Examples are shown in Table 1 below.

division 6-FDA [mol] TPC [mol] BPDC [mol] TFMB [mol] Example 1 0.06 0.056 0.084 0.2 Example 2 0.06 0.042 0.098 0.2 Example 3 0.08 0.048 0.072 0.2 Example 4 0.1 0.040 0.06 0.2 Comparative Example 1 0.06 0.14 0 0.2 Comparative Example 2 0.06 0 0.14 0.2 Comparative Example 3 0.04 0.16 0 0.2 Comparative Example 4 0.06 0.028 0.112 0.2 Comparative Example 5 0.1 0.1 0 0.2 Comparative Example 6 0.14 0.024 0.036 0.2 Comparative Example 7 0.02 0.072 0.108 0.2

Test Example

The physical properties of the films prepared by Examples and Comparative Examples were measured by the following methods and are shown in Table 2 below.

1. Surface Hardness

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.

2. Yellowness (YI)

YI (Yellow Index), i.e., yellowness, was measured using a CIE colorimeter of a spectrophotometer (UltraScan PRO, Hunter Associates Laboratory).

3. Haze

And a haze meter NDH-5000W manufactured by Denso Corporation of Japan.

4. Transmission

The transmittance at 380-780 nm was measured using a UV spectrometer.

5. Modulus

And was measured using UTM (4206-001), a universal testing machine manufactured by Instron.

First, when a polyamide-imide film was prepared with the composition as shown in Table 1, it was found that (i) the unit structure derived from 6-FDA and the unit structure derived from TPC and BPDC relative to 100 mol% (Hereinafter referred to as 'unit structure derived from TPC and BPDC'), ii) unit structure derived from BPDC relative to 100 mol% of unit structure derived from TPC and BPDC (hereinafter referred to as 'unit structure derived from BPDC' ) Are shown in Table 2 below.

division From TPC and BPDC
Derived unit structure [mol%] The unit structure derived from BPDC [mol%] Example 1 70 60 Example 2 70 70 Example 3 60 60 Example 4 50 60 Comparative Example 1 70 0 Comparative Example 2 70 100 Comparative Example 3 80 0 Comparative Example 4 70 80 Comparative Example 5 50 0 Comparative Example 6 30 60 Comparative Example 7 90 60

The results of the above test examples are shown in Table 3 below.

division Hardness Permeability [%] Haze [%] YI Modulus [Gpa] Example 1 H 89.9 0.4 2.1 5.5 Example 2 2H 89.7 0.6 2.3 6.0 Example 3 H 90.1 0.3 1.9 5.3 Example 4 HB 90.2 0.3 1.8 5.2 Comparative Example 1 HB 89.9 0.4 2.1 3.9 Comparative Example 2 H 88.8 5.6 3.7 5.7 Comparative Example 3 H 89.8 0.6 2.3 4.0 Comparative Example 4 H 88.0 3.9 2.7 6.0 Comparative Example 5 HB 89.5 0.4 1.9 3.8 Comparative Example 6 6B 90.8 0.2 1.3 3.7 Comparative Example 7 H 87.7 15.2 4.6 6.5

Referring to Table 3, it can be seen that Comparative Examples 1, 3 and 5 do not include a unit structure derived from BPDC, so that the modulus (elastic modulus) is extremely low as compared with Examples 1 to 4 have.

In Comparative Example 2 and Comparative Example 4, the unit structure derived from BPDC is more than 70 mol%, YI (yellowing degree) is high, haze is generated, and the permeability is decreased.

In Comparative Example 6, the unit structure derived from TPC and BPDC was less than 50 mol% and the surface hardness was drastically lowered. In Comparative Example 7, the unit structure derived from TPC and BPDC had a unit structure exceeding 80 mol% The transparency (transparency, Haze and YI) was reduced due to the shortage.

On the contrary, the polyamide-imide films according to Examples 1 to 4 have excellent mechanical properties with a surface hardness of not less than HB and a modulus (elastic modulus) of 5 GPS or more. Also, it has excellent transparency of 89% or more, YI (yellow color) of 3 or less, transparency of 89% or more, and excellent optical properties. From this, it can be confirmed that the polyamide-imide film according to the present invention is colorless and transparent and has excellent mechanical properties.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Modified forms are also included within the scope of the present invention.

Claims (6)

TFDB (2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl), 6-FDA (2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine Imide film comprising a copolymer of a unit structure derived from terephthaloyl chloride (PTFE) (trimethylolpropane triacrylate), BPDC (1,1-biphenyl-4,4-dicarbonyldichloride), and TPC (terephthaloyl chloride)
The TFDB forms an imide structure with 6-FDA, the TFDB forms an amide structure with TPC and BPDC,
The unit structure derived from the 6-FDA and the unit structure derived from TPC and BPDC is 50 to 80 mol% to 100 mol% of the unit structure derived from TPC and BPDC,
Wherein the unit structure derived from BPDC relative to 100 mol% of the unit structure derived from TPC and BPDC is 50 to 70 mol%.
delete Preparing a polyamic acid solution by adding 6-FDA to a solution in which TFDB is dissolved to cause reaction, adding BPDC to react, and reacting with TPC to prepare a polyamic acid solution; And
Preparing a polyamide-imide film using the polyamic acid solution;
Lt; / RTI >
The total amount of the TPC and BPDC is 50 to 80 mol% based on 100 mol% of TFDB,
Wherein the amount of the BPDC is 50 to 70 mol% based on 100 mol% of the total amount of the TPC and BPDC.
delete A flexible display comprising the polyamide-imide film according to claim 1.
A cover window comprising a polyamide-imide film according to claim 1.