KR101295653B1 - Polyimide film and method for preparing same - Google Patents

Abstract

The present invention relates to a polyimide film and a method for manufacturing the same, wherein the polyimide film of the present invention comprising a polyimide resin having a repeating unit represented by the formula (1) and a repeating unit represented by the formula (2) is colorless, transparent and solvent resistant and Excellent flexibility can be usefully used for transparent electrode films, solar cell protective film and flexible substrate.

Description

POLYIMIDE FILM AND METHOD FOR PREPARING SAME}

The present invention relates to a polyimide film that can be usefully used in transparent electrode films, solar cell protective films, flexible substrates, and the like, having colorless transparency and excellent solvent resistance and flexibility, and a method of manufacturing the same.

The polyimide film is generally obtained by dehydrating and ring closing the polymer solution obtained by solution polymerization of aromatic dianhydride and aromatic diamine with a catalyst, followed by coating in the form of a film and drying at a high temperature. Such polyimide films have excellent heat resistance and mechanical properties, and thus are used in a wide range of applications, such as coating materials and composite materials.

However, the polyimide film becomes yellow due to the high aromatic ring density and thus has low transmittance in the visible light region, making it difficult to use as an optical material.

Therefore, in order to improve the permeability of such a conventional polyimide film, for example, in the method disclosed in Macromolecules 1991, 24, 5001-5005, polyimide films are prepared using dianhydride and diamine containing fluorine atoms. The solvent resistance of the produced polyimide film was not satisfactory.

In addition, Japanese Patent No. 2002-322274 prepared a transparent polyimide film using a hydrogenated monomer, but this also showed insufficient flexibility to use the prepared polyimide film as a material of the flexible substrate.

Japanese Patent No. 2002-322274

Macromolecules 1991, 24, 5001-5005

Accordingly, an object of the present invention is a polyimide film that can be usefully used for transparent electrode films, solar cell protective films, flexible substrates, and the like due to its colorless transparency and excellent solvent resistance and flexibility unlike conventional polyimide films, and a method of manufacturing the same. To provide.

The present invention to achieve the above object

It provides a polyimide film comprising a polyimide resin having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2):

The present invention also

2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl ( 2,2'-TFMB) and a polymer of hydrogenated pyromellitic dianhydride (H-PMDA) and oxydianiline (ODA) were copolymerized in an organic solvent to obtain a polyamic acid solution. It provides the manufacturing method of the said polyimide film containing imidating and hardening.

Unlike the existing polyimide film, the polyimide film of the present invention is colorless and transparent, and has excellent solvent resistance and flexibility, and thus may be usefully used in transparent electrode films, solar cell protective films, and flexible substrates.

Polyimide film according to the invention is characterized in that it comprises a polyimide resin having a repeating unit represented by the formula (1) and 2, this polyimide film of the present invention is 2,2-bis (3,4-dica A polymer of carboxyphenyl) hexafluoropropane dianhydride (6-FDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFMB), A polymer of hydrogenated pyromellitic dianhydride (H-PMDA) and oxydianiline (ODA) is copolymerized in an organic solvent to obtain a polyamic acid solution, followed by imidization and curing of the polyamic acid solution.

The molar ratio of the repeating unit represented by Formula 1 (6-FDA / TFMB) and the repeating unit represented by Formula 2 (H-PMDA / ODA) is 1: 9 to 9: 1, preferably 4: 6 to 6: 4 Can be.

That is, the repeating unit represented by Formula 1 is derived from 6-FDA as the dianhydride component and 2,2'-TFMB as the diamine component and contributes to the transparency and flexibility of the film. The repeating unit represented by the formula (2) is derived from H-PMDA as the dianhydride component and ODA as the diamine component and contributes to the transparency and solvent resistance of the film.

In the present invention, 6-FDA and H-PMDA used as the dianhydride component are 5 to 95 mol% and 95 to 5 mol%, respectively, and 2,2'-TFMB and ODA used as the diamine component are respectively It may be used in amounts of 5 to 95 mol% and 95 to 5 mol%. At this time, the molar ratio between the total amount of the two dianhydride components and the total amount of the two diamine components is preferably in the range of 0.95 to 1.05.

Each of the polymer of 6-FDA and 2,2'-TFMB and the polymer of H-PMDA and ODA can be obtained by solution polymerization of the corresponding monomer raw materials in an organic solvent, and these polymers are mixed in the form of a solution and reacted to copolymerize. Prepare a polyamic acid solution.

Although the conditions in the said polymerization reaction are not specifically limited, It is preferable to make it react for 1 to 24 hours at the temperature of -10-60 degreeC in inert atmosphere, such as nitrogen. The organic solvent for the solution polymerization of the above monomers is not particularly limited as long as it is a solvent that dissolves polyamic acid, but specific examples thereof include dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methyl-2-pyrroli. Ton (NMP), m-cresol, tetrahydrofuran (THF), chloroform and mixtures thereof.

In order to obtain the molecular weight of the appropriate polyamic acid and the viscosity of the polyamic acid solution, the copolymerization reaction solution may preferably have a solid content of 5 to 80% by weight, more preferably 10 to 50% by weight. The preferred number average molecular weight (Mn) of the polyamic acid is 10,000 to 1,000,000, and the preferred viscosity of the polyamic acid solution may be 1,000 to 500,000 cP (rotary viscometer, 25 ° C.), more preferably 5,000 to 200,000 cP.

Preparation of the polyimide film from the polyamic acid solution may be carried out by a conventional method, for example, by applying or casting a polyamic acid solution on a support such as a support plate, a rotating drum or a steel belt, and then performing imidization and curing. Can be carried out to produce the desired polyimide film. At this time, imidation can be applied in combination with a thermal imidation method, a chemical imidation method, or a thermal imidation method and a chemical imidation method.

The thermal imidization method is a method in which the imidation reaction proceeds only by heating after applying or casting a polyamic acid solution to a support. The chemical imidization method is a tertiary method such as isoquinoline, β-picolin, pyridine, etc. The imidation catalyst represented by amines, and the dehydrating agent represented by acid anhydrides, such as acetic anhydride, are thrown in and the imidation reaction is advanced. At this time, the dehydrating agent may be used in a ratio of 1 to 10 molar equivalents, preferably 1.5 to 8 molar equivalents, more preferably 2 to 5 molar equivalents, relative to the polyamic acid, and the imidization catalyst is 0.1 to 2 relative to the polyamic acid. It may be used in a molar equivalent, preferably 0.2 to 1.8 molar equivalents, more preferably 0.3 to 1.5 molar equivalents.

In the present invention, the polyamic acid solution is thermally or chemically imidized to obtain a polyimide solution, which is then added to a second solvent to precipitate solids, which is filtered and dried to obtain a polyimide resin solids. The desired polyimide film can be manufactured by dissolving the obtained polyimide resin solid content in a 1st solvent, obtaining a polyimide resin solution, and then film-forming it. The first solvent may be selected from the same embodiments as used in the polymerization of the polyamic acid solution, the second solvent has a lower polarity than the first solvent to obtain a polyimide resin solid content, so that the polyimide resin It should be a solvent capable of being precipitated as a solid, and specific examples thereof include water, alcohols, ethers, ketones, and mixtures thereof. At this time, the amount of the second solvent is not particularly limited, but may be preferably used in an amount of 3 to 20 times the weight of the polyamic acid solution. After filtering the precipitated polyimide resin solids, 5 at a temperature of 50 to 120 ° C. in consideration of the boiling point of the first and second solvents to remove all of the first and second solvents remaining in the filtered polyimide resin solids. It is preferable to carry out drying for ˜24 hours. Thereafter, the polyimide resin solution dissolved in the first solvent is coated or cast on a support to obtain a desired polyimide film by heating for 1 minute to 5 hours at a temperature increase rate of 0.5 to 10 ° C / min in a temperature range of 50 to 400 ° C. Can be.

The polyimide film of the present invention may preferably have an average thickness in the range of 5 to 250 μm, more preferably in the range of 20 to 100 μm, but is not particularly limited thereto.

The polyimide film of the present invention prepared as described above has a transmittance of 80% or more, a yellowness of 4 or less, and a b value of 3 or less as well as excellent solvent resistance and flexibility when the film thickness is 100 μm or less. It can be usefully used for films, solar cell protective films and flexible substrates. Accordingly, the present invention also provides a flexible substrate and electronic material comprising the polyimide film of the present invention.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

Example 1 Preparation of Polyimide Film of the Invention-(1)

A 1L glass reactor for temperature control as a first reactor was charged with 240.6 g of dimethylformamide (DMF) under a nitrogen atmosphere of 10 ° C., followed by 2,2-bis (3,4-dicarboxyphenyl) hexafluoro 44.2 g (0.1 mol) of rotropane dianhydride (6-FDA) was dissolved. Thereafter, 15.9 g (0.05 mol) of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (2,2'-TFMB) was slowly added thereto, followed by stirring for 2 hours. At the same time, after filling 124.8 g of DMF in a second reactor of the same type as the first reactor under the same temperature environment as the first reactor, 20.0 g (0.1 mol) of oxydianiline (ODA) was dissolved and hydrogenated pyromellitic dian 11.2 g (0.05 mol) of hydride (H-PMDA) was slowly added thereto and stirred for 2 hours. After 2 hours, the solution in the first reactor was slowly added to the second reactor and reacted under a 10 ° C. environment for 24 hours to obtain a polyamic acid solution.

26 g of isoquinoline (IQ) as a catalyst and 61.2 g of acetic anhydride (AA) as a dehydrating agent were added to this polyamic acid solution, and it stirred at 60 degreeC for 3 hours, and manufactured the polyimide solution. The polyimide solution was precipitated in ethanol 5 times the weight of the polyimide solution to obtain a polyimide resin solid, which was filtered and dried at 90 ° C. for 24 hours to obtain about 55 g of polyimide resin powder. The obtained polyimide resin powder was dissolved in 220 g of DMF to prepare a 20 wt% polyimide resin solution, and then heated up at a rate of 2 ° C./min in a temperature range of 80 to 300 ° C. to obtain a polyimide film having a thickness of 90 μm.

Example 2: Preparation of Polyimide Film of the Invention-(2)

As a first reactor, 26.8 g (0.05 mol) of 6-FDA was dissolved after filling 216.8 g of DMF under a nitrogen atmosphere of 10 ° C. in a 1 L glass reactor capable of temperature control. Thereafter, 32.0 g (0.10 mol) of 2,2'-TFMB was slowly added thereto and stirred for 2 hours. At the same time, after filling 129.6 g of DMF in a second reactor of the same type as the first reactor under the same temperature environment as the first reactor, 10.0 g (0.05 mol) of ODA was dissolved and 22.4 g (0.10 mol) of H-PMDA was slowly added. Charged and stirred for 2 hours. After 2 hours, the solution in the second reactor was slowly added to the first reactor, and then reacted under a 10 ° C. environment for 24 hours to obtain a polyamic acid solution.

26 g of isoquinoline (IQ) as a catalyst and 61.2 g of acetic anhydride (AA) as a dehydrating agent were added to this polyamic acid solution, and it stirred at 60 degreeC for 3 hours, and manufactured the polyimide solution. The polyimide solution was precipitated in ethanol 5 times the weight of the polyimide solution to obtain a polyimide resin solid, which was filtered and dried at 90 ° C. for 24 hours to obtain about 52 g of polyimide resin powder. The obtained polyimide resin powder was dissolved in 208 g of DMF to prepare a 20 wt% polyimide resin solution, and then heated up at a rate of 2 ° C./min in a temperature range of 80 to 300 ° C. to obtain a polyimide film having a thickness of 90 μm.

Comparative Example 1

A Kapton HN100 film from DuPont-Toray was used.

Comparative Example 2

In a double jacket 1L glass reactor capable of temperature control, 469.6 g (0.23 mol) of ODA was dissolved after filling 429.6 g of DMF under a nitrogen atmosphere of 10 ° C. Thereafter, 51.5 g (0.23 mol) of H-PMDA was slowly added thereto, and stirred for 24 hours to obtain a polyamic acid solution. Into this polyamic acid solution, 3.7 g of isoquinoline (IQ) and 8.8 g of acetic anhydride (AA) were added and stirred, and the mixture solution was cast on a support, followed by casting at 2 to 80 ° C. in a temperature range of 80 to 300 ° C. It heated up at the min speed and obtained the polyimide film of thickness 90micrometer.

Comparative Example 3

In a 1L glass reactor for temperature control, a double reactor was filled with DMF 403.9g under a nitrogen atmosphere of 10 ° C., and TFMB 38.4g (0.12mol) was dissolved. Thereafter, 53.3 g (0.12 mol) of 6-FDA was slowly added thereto, and stirred for 24 hours to obtain a polyamic acid solution. 15.5 g of isoquinoline (IQ) and 36.7 g of acetic anhydride (AA) were added to the polyamic acid solution, and stirred at 60 ° C. for 3 hours to prepare a polyimide solution. The polyimide solution was precipitated in ethanol at 5 times the weight of the polyimide solution to obtain a polyimide resin solid, which was filtered and dried at 90 ° C. for 24 hours to obtain about 70 g of polyimide resin powder. The obtained polyimide resin powder was dissolved in 280 g of DMF to prepare a 20 wt% polyimide resin solution, and then heated up at a rate of 2 ° C./min in a temperature range of 80 to 300 ° C. to obtain a polyimide film having a thickness of 90 μm.

Test Example: Evaluation of Physical Properties of Polyimide Film

The transmittance (transmittance at 550 nm, yellowness, b value), flexibility and solvent resistance of the polyimide films prepared in Examples 1 and 2 and Comparative Examples 1 to 3, respectively, were measured, and the results are shown in Table 1 below. Indicated. In this case, the transmittance, yellowness, and b value were measured using the CIE colorimeter L and b values of the spectrophotometer (UltraScan PRO of Hunter Associates Laboratory). The solvent resistance was determined by dissolution in DMF for 30 minutes.

thickness Permeability Yellowness b value flexibility Solvent resistance Furtherance Example 1 90 90.1 1.92 1.1 OK OK Invention Example 2 90 90 1.91 0.9 OK OK Invention Comparative Example 1 25 70.5 116 48.3 OK OK PMDA / ODA Comparative Example 2 90 89.1 4.49 2.35 X OK H-PMDA / ODA Comparative Example 3 90 92.6 1.76 0.5 OK X 6-FDA / TFMB

From the results of Table 1, the polyimide films of Examples 1 and 2 according to the present invention have excellent transmittance, flexibility, and solvent resistance, whereas the commercial film of Comparative Example 1 has a low transmittance and has a single repeating unit. And it can be seen that the polyimide film of 3 is low in flexibility or solvent resistance.

Claims (11)

A polyimide film comprising a polyimide resin having a repeating unit represented by the following formula (1) and a repeating unit represented by the following formula (2):
[Formula 1]

(2)

The method of claim 1,
The repeating unit represented by Chemical Formula 1 is 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA) and 2,2'-bis (trifluoromethyl) -4 A polyimide film obtained by polymerization with, 4'-diaminobiphenyl (2,2'-TFMB). The method of claim 1,
A repeating unit represented by the formula (2) is a polyimide film, characterized in that obtained by the polymerization of hydrogenated pyromellitic dianhydride (H-PMDA) and oxydianiline (ODA). The method of claim 1,
The polyimide film, characterized in that the polyimide resin comprises a repeating unit represented by the formula (1) and a repeating unit represented by the formula (2) in a molar ratio of 1: 9 to 9: 1. delete 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA) and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl ( 2,2'-TFMB) and a polymer of hydrogenated pyromellitic dianhydride (H-PMDA) and oxydianiline (ODA) were copolymerized in an organic solvent to obtain a polyamic acid solution. The manufacturing method of the polyimide film of Claim 1 containing imidating and hardening. The method according to claim 6,
Method of producing a polyimide film, characterized in that the polymerization is carried out for 1 to 24 hours at a temperature of -10 ~ 60 ℃ in an inert atmosphere. The method according to claim 6,
The organic solvent is a group consisting of dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), m-cresol, tetrahydrofuran (THF), chloroform and mixtures thereof Method for producing a polyimide film, characterized in that selected from. The method according to claim 6,
The said imidation is performed by the thermal imidation method, the chemical imidation method, or the combination of the thermal imidation method and the chemical imidation method. The manufacturing method of the polyimide film characterized by the above-mentioned. The flexible substrate containing the polyimide film of any one of Claims 1-4. Electronic material containing the polyimide film of any one of Claims 1-4.