KR101899098B1 - Method for preparing polyimide film and polyimide film using the same - Google Patents

Abstract

The present invention provides a method for preparing a polyimide film, which comprises the following steps: preparing a reaction composition comprising a tetracarboxylic dianhydride, a diamine compound, and a mixed solvent; preparing a coating composition comprising a polyimide precursor from the reaction composition; and preparing a polyimide film from the coating composition, wherein the mixed solvent is a mixture of an amide compound and a lactate compound. The polyimide film can easily be formed in an environmentally friendly environment by using a mixed solvent of the amide compound and the lactate compound, and the polyimide film can simultaneously have excellent mechanical properties.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing a polyimide film,

To a process for producing a polyimide film and a polyimide film produced thereby.

There is a growing need for a flexible display that is thin, lightweight, lightweight, and flexible as paper, free of any place and time, as a display that visualizes various information and transmits it to human beings in accordance with the deepening and popularization of informatization . In order to realize a flexible display, flexible substrates, organic and inorganic materials for low-temperature processes, flexible electronics, encapsulation and packaging technologies are required in combination. Among them, the flexible substrate is the most important part for determining the performance, reliability and price of the flexible display.

A plastic substrate is useful as a flexible substrate because of its ease of processing, low weight and continuous process. However, plastic substrates are inherently poor in thermal stability, and therefore, their physical properties must be improved in order to be practically applied. Therefore, polyimide polymer materials having excellent heat resistance are increasingly required.

In one embodiment of the present invention, there is provided a method for producing a polyimide film having excellent mechanical properties using an environmentally friendly solvent.

In another embodiment of the present invention, there is provided a polyimide film produced by the above method.

In one embodiment of the present invention, there is provided a process for preparing a reaction composition comprising: preparing a reaction composition comprising a tetracarboxylic dianhydride, a diamine compound and a mixed solvent; Preparing a coating composition comprising the polyimide precursor from the reaction composition; And preparing a polyimide film from the coating composition, wherein the mixed solvent is a mixture of an amide compound and a lactate compound.

In another embodiment of the present invention, there is provided a polyimide film produced by the method for producing the polyimide film.

A polyimide film is easily formed in an environmentally friendly environment by using a mixed solvent of an amide compound and a lactate compound, and the polyimide film can simultaneously have excellent mechanical properties.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art to which the invention pertains. Only.

In one embodiment of the present invention, a method for producing a polyimide film is provided. Specifically, there is provided a process for preparing a reaction composition, comprising: preparing a reaction composition comprising a tetracarboxylic dianhydride, a diamine compound, and a mixed solvent; Preparing a coating composition comprising the polyimide precursor from the reaction composition; And preparing a polyimide film from the coating composition, wherein the mixed solvent is a mixture of an amide compound and a lactate compound.

The method for producing the polyimide film easily forms a polyimide film in an environmentally friendly environment using a mixed solvent of an amide compound and a lactate compound, and the polyimide film can simultaneously have excellent mechanical properties.

The method for producing the polyimide film comprises firstly preparing a reaction composition comprising a tetracarboxylic dianhydride, a diamine compound and a mixed solvent, wherein the mixed solvent is a mixture of an amide compound and a lactate compound. The tetracarboxylic dianhydride and the diamine compound are easily dissolved in the above mixed solvent to prepare a reaction composition, from which a polyimide film can be prepared.

Generally, the reaction product of the tetracarboxylic dianhydride and the diamine compound has a good solubility in a solvent such as an amide compound and can form a polyimide film. However, solvents such as amide compounds are classified as harmful and their use is limited.

The polyimide film can be produced eco-friendly by using a mixed solvent of the amide compound and the lactate compound to reduce the use of a harmful amide compound and simultaneously using a lactate compound as a biodegradable solvent have.

The mixed solvent may be included in the step of preparing the reaction composition to easily dissolve the tetracarboxylic dianhydride and the diamine compound and stably form the polyimide film from the polyimide precursor polyamic acid. Specifically, when the tetracarboxylic acid dianhydride and the diamine compound are dissolved in the mixed solvent of the amide compound and the lactate compound, the tetracarboxylic acid dianhydride and the diamine compound as the reactant are mainly dissolved in the amide compound. Thus, the polyimide precursor prepared from the reactant is mainly soluble in the amide compound, and can form a structure in which the lactate compound surrounds the periphery. Therefore, even when the solvent is removed by heat treatment, a stable polyimide film can be formed from the polyimide precursor.

On the other hand, in the case where a lactate compound is added to the coating composition after the reaction composition is prepared using the conventional amide compound solvent and the coating composition containing the polyimide precursor is formed on the reactant, Penetrate between the polyimide precursor and the amide compound, and react with the polyimide precursor. Therefore, when the solvent such as lactate is removed by heat treatment, a stable polyimide film can not be formed due to the reaction such as the removal of the lactate and the polyimide precursor.

The weight ratio of the amide compound to the lactate compound may be 80:20 to 50:50. By mixing the mixed solvent at the above weight ratio, the reaction composition can be easily prepared by dissolving the tetracarboxylic dianhydride and the diamine compound while reducing the use of the harmful amide compound. From this, the polyimide film can be easily prepared have. Specifically, when the weight ratio of the lactate compound is less than the above range, the toxicity of the lactate compound is too high to be used, and when the weight ratio of the lactate compound is more than the above range, the reactant does not dissolve, Can not be produced. More specifically, when the weight ratio of the lactate compound exceeds the above range, the diamine compound may not dissolve.

Specifically, the amide compound may be a compound having a structure represented by the following formula (1).

[Chemical Formula 1]

R 1 to R 3 in the general formula (1) are each independently hydrogen; Or a linear or branched alkyl group of 1 to 5 carbon atoms.

Generally, the amide compound may be a compound having a ring structure other than the compound having the structure of the formula (1). For example, N-methyl pyrrolidone and the like may be present. N-methylpyrrolidone can dissolve reactants such as tetracarboxylic dianhydride and diamine compounds well. However, N-methylpyrrolidone has been designated as a toxic substance under the Chemical Substance Control Law due to its reproductive toxicity and its use is restricted.

The amide compound does not have a cyclic structure and is a compound having a linear structure represented by the general formula (1), is mixed together with a lactate compound to form a solvent, the reaction product of the tetracarboxylic dianhydride and the diamine compound can be dissolved well From this, a film having excellent physical properties can be easily formed.

For example, the compound having the structure of Formula 1 may be selected from the group consisting of dimethylacetamide, dimethylformamide, and combinations thereof.

The lactate compound is included in the mixed solvent as a biodegradable material to produce a polyimide film having excellent physical properties in an environmentally friendly manner.

For example, the lactate compound may be selected from the group consisting of methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, ≪ / RTI > and combinations thereof.

The mixed solvent is a mixture of the amide compound and the lactate compound. The tetracarboxylic dianhydride and the diamine compound can be easily dissolved, and the polyimide film can be stably formed from polyamic acid as the polyimide precursor.

The amide compound and the lactate compound are similar to each other in breaking point and can be more economical in the course of coating or the like by using the compounds as a mixed solvent. As an example, the mixed solvent may be used for the mixing of dimethylacetamide and ethyl lactate.

The reaction composition may have a molar ratio of the tetracarboxylic dianhydride to the diamine compound of about 0.9: 1 to about 1.1: 1. The reaction composition contains the tetracarboxylic acid dianhydride and the diamine compound in the above range to produce a polyimide film having excellent physical properties. In particular, when the content of the diamine is less than the above range, the viscosity may excessively increase due to an increase in the content of the tetracarboxylic dianhydride, and thus the coating may be difficult. If the content of the diamine exceeds the above range, the molecular weight may be lowered and the heat resistance and the mechanical property value may be lowered.

The tetracarboxylic dianhydride included in the reaction composition may be an aromatic compound. By containing an aromatic compound as the tetracarboxylic acid dianhydride, the polyimide film is easily dissolved in a mixed solvent of an amide compound and a lactate compound, a polyimide film having excellent physical properties can be stably formed, and excellent heat resistance can be obtained.

The aromatic compound may be, for example, pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic acid dianhydride Water, 3,3 ', 4,4'-biphenyl ether tetracarboxylic dianhydride, 3,3', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride and the like.

The weight average molecular weight of the diamine may range from about 100 to about 400. By using a compound having a weight average molecular weight in the above range as the diamine, it is possible to stably form a polyimide film which is easily dissolved in a mixed solvent of an amide compound and a lactate compound, has excellent physical properties, have.

The diamines include, for example, paraphenylenediamine, 4,4 '- [isopropylidenebis (4,1-phenyleneoxy)] dianiline, 3,3-diaminobenzophenone, 2,2'-bis (Trifluoromethyl) benzidine. ≪ / RTI >

The coating composition may be prepared by stirring the reaction composition at about 0 캜 to about 60 캜 for about 1 hour to about 24 hours. By preparing the coating composition under the above conditions, the weight average molecular weight of the polyimide precursor can be controlled and the viscosity can be controlled.

The coating composition comprises a polyimide precursor prepared from the reaction composition. Specifically, the coating composition may comprise a polyamic acid which is a polyimide precursor produced from the polymerization reaction of the tetracarboxylic acid dianhydride and the diamine compound.

 The viscosity of the coating composition may be from about 1,000 cP to about 300,000 cP at 25 占 폚. In particular, the viscosity of the coating composition may be from about 5,000 cP to about 30,000 cP. The above coating composition has the above-mentioned range of viscosity, so that it can be uniformly coated to produce a smooth film. In particular, when the viscosity of the coating composition is less than the above range, the molecular weight of the polyamic acid is lowered, and the thermal, mechanical and electrical properties of the polyimide film formed through the heat treatment process are lowered. When the viscosity of the coating composition exceeds the above range There may be a problem that the coating is not uniform due to high viscosity.

The coating composition may be applied and heat-treated at about 80 캜 to about 400 캜 to produce a polyimide film. For example, the polyimide film may be prepared by heat-treating the polyimide film at a temperature of about 80 ° C, about 200 ° C, and about 350 ° C for 30 minutes, respectively.

Specifically, the coating composition can be applied on a substrate by using a spinner, a roll coder, a die coater, a screen printing method, or the like. The coating composition may be heat treated in the temperature range to remove the solvent and cure to form a polyimide film. Specifically, when the coating composition is heat-treated at a temperature lower than the above-mentioned range, the solvent may not be sufficiently removed, the film may not be properly formed, and heat resistance may be deteriorated.

The polyimide film may include a polyimide having a weight average molecular weight of about 1,000 to 3,000,000. Specifically, it may include a polyimide having a weight average molecular weight of about 100,000 to about 500,000. The polyimide film includes a polyimide having a weight average molecular weight within the above range, and thus a polyimide film having excellent physical properties can be stably produced.

The polyimide film may include a thermoplastic polyimide. The polyimide film includes a thermoplastic polyimide and can exhibit excellent elongation. The polyimide film can be easily adhered to a different kind of material such as metal through heat fusion or the like.

The glass transition temperature of the thermoplastic polyimide may be from about 200 캜 to about 400 캜. Specifically, the glass transition temperature of the thermoplastic polyimide may be from about 200 캜 to about 300 캜.

In another embodiment of the present invention, there is provided a polyimide film produced by the method for producing the polyimide film. The polyimide film is produced by the above-described method for producing a polyimide film, and the method for producing the polyimide film is as described above.

Generally, polyimide films are prepared by dissolving tetracarboxylic dianhydrides and diamine compounds in a solvent such as N-methylpyrrolidone and the like. However, N-methylpyrrolidone has been designated as a toxic substance in accordance with the Chemical Substance Control Law due to its reproductive toxicity and is no longer usable.

As described above, the polyimide film may include a mixed solvent of the amide compound and the lactate compound in the step of preparing the reaction composition to reduce the use of the harmful amide compound and simultaneously use the lactate compound as a biodegradable solvent , The polyimide film can be produced environmentally. In addition, the polyimide film thus produced can have an equivalent or superior mechanical property, as compared with a film produced in a solvent such as N-methylpyrrolidone and the like.

The polyimide film may have a thickness of about 1 [mu] m to about 20 [mu] m. When the film is less than the above-mentioned thickness, the coating may not be uniform, and if it exceeds this range, a surface bubble problem may occur.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and thus the present invention should not be limited thereto.

< Example  And Comparative Example >

Example  One:

Dimethylacetamide and ethyl lactate were mixed at a weight ratio of 80:20 to prepare a mixed solvent, and pyromellitic acid dianhydride and 4,4 '- [isopropylidenebis (4,1-phenyleneoxy)] dianiline Was added to the mixed solvent at a molar ratio of 0.91: 1 to prepare a reaction composition. The reaction composition was then stirred at 0 占 폚 for 4 hours to prepare a coating composition having a polyimide precursor polyamic acid and having a viscosity of 7,000 cP at 25 占 폚. The coating composition was applied and heat-treated at a temperature of about 80 캜 for about 30 minutes, about 200 캜 for about 30 minutes, and then at a temperature of about 350 캜 for about 30 minutes to have a weight average molecular weight of 2,000,000 and a glass transition temperature (Tg) A film having a thickness of 10 占 퐉 including the thermoplastic polyimide at 280 占 폚 was prepared.

Example  2:

A film was prepared in the same manner as in Example 1 except that dimethylacetamide and ethyl lactate were mixed at a weight ratio of 70:30 to prepare a mixed solvent.

Example  3:

Dimethylacetamide and ethyl lactate were mixed in a weight ratio of 60:40 to prepare a mixed solvent. A film was prepared in the same manner as in Example 1.

Example  4:

Dimethylacetamide and ethyl lactate were mixed in a weight ratio of 50:50 to prepare a mixed solvent.

Example  5:

Dimethylacetamide and ethyl lactate were mixed in a weight ratio of 70:30 to prepare a mixed solvent, and pyromellitic dianhydride and 4,4-oxydianiline were added to the mixed solvent at a molar ratio of 0.95: 1 to prepare a reaction composition , A thermosetting polyimide film was produced by the same method as in Example 2. [

Comparative Example  One

A film was prepared in the same manner as in Example 2, except that the reaction composition was prepared using a single solvent of dimethylacetamide instead of the mixed solvent.

Comparative Example  2

Pyromellitic dianhydride and 4,4 '- [isopropylidenebis (4,1-phenyleneoxy)] dianiline in a molar ratio of 0.91: 1 to a single solvent of dimethylacetamide to prepare a reaction composition. The reaction composition was then stirred at 0 占 폚 for 4 hours to prepare a coating composition having a polyimide precursor polyamic acid and having a viscosity of 5,000 cP at 25 占 폚. To the coating composition, ethyl lactate was added in an amount of about 43 parts by weight relative to 100 parts by weight of the dimethylacetamide. After coating, the coating composition was applied to the coating composition at about 80 DEG C for about 30 minutes, at about 200 DEG C for about 30 minutes, For about 30 minutes.

<Evaluation>

Experimental Example  1: Whether the film is formed

Whether or not a film was formed in the above Examples and Comparative Examples was visually observed and shown in Table 1. When the film was observed with the naked eye, it was marked with "" and when no film was formed, it was marked with "X ".

Experimental Example  2: tensile strength ( Mpa )

After each specimen was manufactured according to ASTM D-638, the specimen was pulled until the specimen was broken at a speed of 50.8 mm / min using a universal testing machine (UTM, Universal Testing Machine, model: WITHLAB WL2100) The results are shown in Table 1

Experimental Example  3: Elongation at break ( % )

After each specimen was manufactured according to ASTM D-638, the specimen was pulled until the specimen was broken at a speed of 50.8 mm / min using a universal testing machine (UTM, Universal Testing Machine, model: WITHLAB WL2100) And the elongation at break was calculated and shown in Table 1.

Experimental Example  4: Tensile modulus ( Mpa )

After each test piece was manufactured according to ASTM D-638, the test piece was stretched until the specimen was broken at a rate of 5.08 mm / min using a universal testing machine (UTM, Universal Testing Machine, WITHLAB WL2100) The tensile modulus was calculated by calculating the slope and is shown in Table 1.

Whether the film is formed The tensile strength Elongation at break Tensile modulus Example 1 ○ 112 28 3057 Example 2 ○ 115 26 3049 Example 3 ○ 119 24 3041 Example 4 ○ 116 25 3061 Example 5 ○ 97 12 1818 Comparative Example 1 ○ 120 4 3084 Comparative Example 2 X - - -

As shown in Table 1, Examples 1 to 5 are polyimide films prepared by using a mixed solvent obtained by mixing an amide compound and a lactate compound. Compared with Comparative Example 1 used as a sole solvent for an amide compound, It can be confirmed that a polyimide film having excellent mechanical properties can be easily formed even if a solvent is used. In particular, the polyimide film prepared from Example 2 using a mixed solvent had a remarkably excellent effect in terms of elongation at break compared with the polyimide film prepared in Comparative Example 1 under the same conditions except that a single solvent of dimethylacetamide was used Able to know.

Claims (15)

Preparing a reaction composition comprising a tetracarboxylic dianhydride, a diamine compound, and a mixed solvent;
Preparing a coating composition comprising the polyimide precursor from the reaction composition; And
Preparing a polyimide film from the coating composition,
The diamine compound may be at least one selected from the group consisting of paraphenylenediamine, 4,4 '- [isopropylidenebis (4,1-phenyleneoxy)] dianiline, 3,3-diaminobenzophenone or 2,2'- Lt; / RTI &gt; benzyl,
Wherein the mixed solvent is a mixture of an amide compound and a lactate compound and the weight ratio of the amide compound to the lactate compound is 80:20 to 50:50
A method for producing a polyimide film.
delete The method according to claim 1,
The lactate compound may be selected from the group consisting of methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and combinations thereof. Lt; RTI ID = 0.0 &gt;
A method for producing a polyimide film.
The method according to claim 1,
The amide compound is a compound having a structure represented by the following formula
Method of producing polyimide film:
[Chemical Formula 1]

R 1 to R 3 in the general formula (1) are each independently hydrogen; Or a linear or branched alkyl group of 1 to 5 carbon atoms.
The method according to claim 1,
Wherein the reaction composition has a molar ratio of the tetracarboxylic dianhydride to the diamine compound of from 0.9: 1 to 1.1: 1
A method for producing a polyimide film.
The method according to claim 1,
The tetracarboxylic acid dianhydride is an aromatic compound
A method for producing a polyimide film.
The method according to claim 1,
The diamine has a weight average molecular weight of 100 to 400
A method for producing a polyimide film.
The method according to claim 1,
The reaction composition is stirred at 0 ° C to 60 ° C for 1 hour to 24 hours to prepare the coating composition
A method for producing a polyimide film.
The method according to claim 1,
The viscosity of the coating composition is from 1,000 cP to 300,000 cP at &lt; RTI ID = 0.0 &gt; 25 C &
A method for producing a polyimide film.
The method according to claim 1,
The coating composition is applied and heat-treated at 80 to 400 캜 to produce a polyimide film
A method for producing a polyimide film.
The method according to claim 1,
Wherein the polyimide film comprises a polyimide having a weight average molecular weight of 1,000 to 3,000,000
A method for producing a polyimide film.
The method according to claim 1,
Wherein the polyimide film comprises a thermoplastic polyimide
A method for producing a polyimide film.
13. The method of claim 12,
The glass transition temperature of the thermoplastic polyimide is preferably from 200 캜 to 400 캜
A method for producing a polyimide film.
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