KR20200066155A - Polyimide film excellent in colorless transparency and flexibility and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a polyimide film with excellent colorless transparency and flexibility as well as a method for preparing the same. More particularly, the film comprises a polyimide resin having a repeating unit represented by chemical formula 1 and a repeating unit represented by chemical formula 2. The polyimide film comprising the polyimide resin having the repeating unit represented by the formula 1 and the repeating unit represented by the formula 2 not only has excellent mechanical properties and thermal stability, but also has excellent colorless transparency and flexibility, and thus can be useful in a transparent electrode film, a solar cell protective film, a flexible substrate and the like.

Description

Polyimide film with excellent colorless transparency and flexibility and its manufacturing method {POLYIMIDE FILM EXCELLENT IN COLORLESS TRANSPARENCY AND FLEXIBILITY AND MANUFACTURING METHOD THEREOF}

The present invention relates to a polyimide film having excellent colorless transparency and flexibility, and a method for manufacturing the same, more specifically, not only excellent mechanical properties and thermal stability, but also excellent colorless transparency and flexibility to provide a transparent electrode film, a solar cell protective film, and The present invention relates to a polyimide film excellent in colorless transparency and flexibility that can be usefully used for flexible substrates, and the like, and a method for manufacturing the same.

The polyimide film is generally obtained by subjecting a polymer solution obtained by solution polymerization of an aromatic dianhydride and an aromatic diamine to be mixed with a catalyst and then coated in a film form and dried at high temperature to undergo dehydration and ring closure. Since these polyimide films have excellent heat resistance and mechanical properties, they are used for a wide range of applications such as coating materials and composite materials.

However, the polyimide film is colored brown or yellow due to the high aromatic ring density, and thus it is difficult to use in a field where transparency is low due to low transmittance in the visible light region and yellow color, thereby exhibiting low light transmittance.

In order to solve this problem, a method of purifying the polymer by purifying the monomer and the solvent with high purity has been attempted, but the effect of improving the permeability is negligible. In addition, in order to improve the permeability of the existing polyimide film, for example, in the method disclosed in [Macromolecules 1991, 24, 5001-5005], a polyimide film is prepared using dianhydride and diamine containing fluorine atoms. The solvent resistance of the resulting polyimide film was not satisfactory.

US Patent Registration No. 5053480 discloses a method of using an aliphatic cyclic dianhydride component instead of an aromatic dianhydride. This method has improved transparency and color when it is in the form of a solution or film compared to the above purification method, but also has a limitation in improving the transmittance and has a problem of deteriorating thermal and mechanical properties.

In addition, Japanese Patent Laid-Open No. 2002-322274 produced a transparent polyimide film using hydrogenated monomers, but this also exhibited insufficient flexibility for the prepared polyimide film to be used as a material for a flexible substrate.

U.S. Patent Registration No. 5053480 (1991.10.01) Japanese Patent Publication No. 2002-322274 (2002.11.08)

Macromolecules 1991, 24, 5001-5005

The object of the present invention is not only excellent in mechanical properties and thermal stability, but also excellent in colorless transparency and flexibility, so that it can be usefully used in transparent electrode films, solar cell protective films, and flexible substrates. It is to provide a film and its manufacturing method.

An object of the present invention is a polyimide film having excellent colorless transparency and flexibility, 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]

[Formula 2]

In Formula 1 and Formula 2, R ₁ is

Consisting of one selected from the group consisting of,

The R ₂ is made of one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a phenyl group,

The n is made of an integer from 0 to 700,

The x is 0.01<x<0.99.

According to a more preferred feature of the present invention, the repeating unit represented by Chemical Formula 1 is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis (trifluoro It is assumed to be prepared by polymerization with romethyl)-[1,1'-biphenyl]-4,4'-diamine (TFMB) and bis(3-aminopropyl) terminal polydimethylsiloxane (PDMS).

According to a more preferred feature of the present invention, the repeating unit represented by Chemical Formula 2 is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis (trifluoro It is assumed to be prepared by polymerization with romethyl)-4,4'-diaminodiphenyl ether (6FODA) and bis(3-aminopropyl) terminal polydimethylsiloxane (PDMS).

According to a still more preferred feature of the present invention, the polyimide film is assumed to have a light transmittance of 80% or more.

According to a still more preferred feature of the present invention, the polyimide film has a thermal decomposition temperature of 400°C or higher.

In addition, the object of the present invention can also be achieved by providing a flexible substrate characterized in that it comprises a polyimide film excellent in colorless transparency and flexibility.

In addition, the object of the present invention can also be achieved by providing an electronic material characterized in that it comprises a polyimide film excellent in colorless transparency and flexibility.

In addition, the object of the present invention is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-[1,1'-ratio Phenyl]-4,4′-diamine (TFMB) and bis(3-aminopropyl) terminal polydimethylsiloxane are copolymerized in an organic solvent to prepare a polyamic acid solution to prepare a polyamic acid solution, and to prepare the polyamic acid solution. A polyimide solution preparation step of preparing a polyimide solution by imidizing a polyamic acid solution prepared through and a film manufacturing step of producing a film by heat-treating the polyimide solution prepared through the polyimide solution preparation step It can also be achieved by providing a method for producing a polyimide film having excellent colorless transparency and flexibility.

According to a preferred feature of the invention, the organic solvent is tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), m-cresol and It is assumed that one or more selected from the group consisting of chloroform.

According to a more preferred feature of the present invention, the polyimide solution preparation step is made by mixing and stirring an imidization catalyst and acetic anhydride in a polyamic acid solution.

According to a more preferred feature of the invention, the imidization catalyst is made of one selected from the group consisting of isoquinoline, β-picoline and pyridine.

According to a still more preferred feature of the present invention, the dehydrating agent is made of acetic anhydride.

According to a still more preferred feature of the present invention, the film production step is performed by heat-treating the polyimide solution at a heating rate of 5 to 10°C/min in a temperature range of 50 to 400°C for 1 to 5 hours.

The polyimide film excellent in colorless transparency and flexibility according to the present invention and its manufacturing method have excellent mechanical properties and thermal stability, as well as excellent colorless transparency and flexibility, such as transparent electrode films, solar cell protective films and flexible substrates. It has an excellent effect of providing a polyimide film that can be usefully used.

1 is a graph showing the light transmittance of polyimide films prepared through Examples 1 to 2 and Comparative Examples of the present invention.
Figure 2 is a photograph showing the flexibility of the polyimide film prepared through Examples 1 to 2 and Comparative Examples of the present invention.

Hereinafter, a preferred embodiment of the present invention and the physical properties of each component will be described in detail, but it is intended to be described in detail so that a person skilled in the art to which the present invention pertains can easily implement the invention. This does not mean that the technical spirit and scope of the present invention is limited.

The polyimide film excellent in colorless transparency and flexibility according to the present invention includes a polyimide resin having a repeating unit represented by the following Chemical Formula 1 and a repeating unit represented by the following Chemical Formula 2.

[Formula 1]

[Formula 2]

At this time, in Formula 1 and Formula 2, R ₁ is preferably made of one selected from the following formulas.

In addition, in Formula 1 and Formula 2, R ₂ is composed of one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a phenyl group, wherein n is an integer of 0 to 700, and x is 0.01<x< 0.99.

At this time, the molar ratio between the repeating unit represented by Chemical Formula 1 and the repeating unit represented by Chemical Formula 2 is defined due to the x value. The repeating unit represented by Chemical Formula 1 and the repeating unit represented by Chemical Formula 2 are 0.4:0.6 to Most preferably, it consists of a molar ratio of 0.6:0.4.

In addition, the repeating unit represented by Chemical Formula 1 is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-[1, It is prepared by polymerization with 1'-biphenyl]-4,4'-diamine (TFMB), bis(3-aminopropyl) terminal polydimethylsiloxane (PDMS), and the repeating unit represented by Formula 2 is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether (6FODA), It is preferably prepared by polymerization with bis(3-aminopropyl) terminated polydimethylsiloxane (PDMS).

The polyimide film composed of the repeating unit may have a light transmittance of 80% or more, a yellow index of 4 or less, and a b value of 3 or less when the thickness is 100 μm or less, and the thermal decomposition temperature is 400° C. or more. It can be used for flexible substrates or electronic materials.

In addition, the method for producing a polyimide film excellent in colorless transparency and flexibility according to the present invention is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(tri Fluoromethyl)-[1,1'-biphenyl]-4,4'diamine (TFMB) and bis(3-aminopropyl) terminal polydimethylsiloxane are copolymerized in an organic solvent to prepare a polyamic acid solution. Heat treatment of a polyimide solution prepared through imidization of a polyamic acid solution prepared by imidizing a polyamic acid solution prepared through a mixed acid solution preparation step and the polyamic acid solution preparation step and the polyimide solution preparation step It comprises a film production step to produce a film.

At this time, the organic solvent is selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), m-cresol and chloroform It consists of one or more.

The polyimide solution preparation step is a step of imidizing the polyamic acid solution prepared through the polyamic acid solution preparation step to prepare a polyimide solution, and a chemical imidization method may be used. The chemical imidization method is polyamic acid. It is a method of advancing the imidation reaction by introducing an imidization catalyst represented by tertiary amines such as isoquinoline, β-picoline, and pyridine, and a dehydrating agent represented by acid anhydride such as acetic anhydride. 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, and the imidization catalyst to 0.1 to 2 molar equivalents to the polyamic acid. It can be used in a molar equivalent, preferably 0.2 to 1.8 molar equivalents, more preferably 0.3 to 1.5 molar equivalents.

In this case, after the polyamic acid solution is chemically imidized through the above process to obtain a polyimide solution, it is added to a second solvent to precipitate solids, filtered and dried to obtain a polyimide resin as a solid content.

In addition, the polyimide solution is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-[1,1'-ratio Phenyl]-4,4´-diamine (TFMB) is polymerized with water to prepare a polyimide powder, and after dissolving the polyimide powder in an organic solvent, 4,4′-(hexafluoroisopropylidene) Diphthalic anhydride (6FDA), bis(3-aminopropyl) terminal polydimethylsiloxane may be added and copolymerized through the process.

The film manufacturing step is a step of heat-treating the polyimide solution prepared through the polyimide solution manufacturing step to produce a film, and applying or casting the polyimide solution prepared through the polyimide solution manufacturing step onto a support to 50 to It consists of heating for 1 minute to 5 hours at a heating rate of 5 to 10°C/min in the temperature range of 400°C.

In addition, in the present invention, a process for preparing a polyimide film from the polyamic acid solution may be performed by a conventional method, for example, after applying or casting a polyamic acid solution on a support such as a support plate, a rotating drum, or a steel belt, The imidization can be performed to produce the desired polyimide film. At this time, the imidization can be applied by thermal imidization, chemical imidization, or thermal imidization and chemical imidization. It is a method of advancing the imidation reaction by heating only.

In addition, in the process of manufacturing the polyimide solution prepared through the polyimide solution manufacturing step in addition to the above method as a film, the polyamic acid solution is chemically imidized to obtain a polyimide solution, and then it is introduced into a second solvent. After the solid content is precipitated and filtered and dried to obtain a polyimide resin solid content, the obtained polyimide resin solid content is dissolved in a first solvent to obtain a polyimide resin solution, and then it can be made into a process of producing a film.

At this time, the first solvent may use the same components as the organic solvent used in the polymerization of the polyamic acid solution, and the second solvent has a lower polarity than the first solvent to obtain a polyimide resin solid content, and thus polyi due to a difference in solubility. It should be a solvent capable of precipitating the mid resin as a solid content, and specifically, it may be made of one selected from the group consisting of water, alcohol, ethers and ketones. At this time, the amount of the second solvent is not particularly limited, but can be preferably used in an amount of 3 to 20 times the weight of the polyamic acid solution.

In addition, after filtering the solid content of the precipitated polyimide resin, if the first solvent and the second solvent component remain in the filtered polyimide resin solid, the boiling point of the first solvent and the second solvent is considered to remove the solvent component. It is preferred to dry for 5 to 24 hours at a temperature of 50 to 120°C.

The polyimide film prepared through the above process 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 limited thereto.

The polyimide film of the present invention prepared as described above has a light transmittance of 80% or more, a yellow index of 4 or less, and a b value of 3 or less when the film thickness is 100 μm or less, and is also excellent in solvent resistance and flexibility, and thus is transparent. It can be usefully used for electrode films, solar cell protective films and flexible substrates.

Hereinafter, a method for manufacturing a polyimide film excellent in colorless transparency and flexibility according to the present invention and physical properties of the polyimide film produced through the manufacturing method will be described with reference to examples.

<Example 1> Preparation of polyimide film excellent in colorless transparency and flexibility

14.3 mL of tetrahydrofuran (THF) was added to a 100 mL 2-neck round bottom flask substituted with nitrogen gas, and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) 0.888 g (0.002 mol) ), 2,2´-bis(trifluoromethyl)-[1,1´-biphenyl]-4,4´-diamine (TFMB) 0.198g (0.001mol) and bis(3-aminopropyl) terminal After adding 2.5 g of polydimethylsiloxane (0.001 mol), a polyamic acid solution was prepared by reacting at room temperature for 24 hours, pyridine and acetic anhydride were added to the prepared polyamic acid solution and stirred to prepare a polyimide solution, The prepared polyimide solution was coated on a glass substrate to a thickness of 100 µm, put into an oven, and heat treated at 50° C. for 1 hour, followed by heat treatment at 8° C./min. Mid films were prepared.

<Example 2> Preparation of a polyimide film excellent in colorless transparency and flexibility

14.3 mL of tetrahydrofuran (THF) was added to a 100 mL 2-neck round bottom flask substituted with nitrogen gas, and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) 0.888 g (0.002 mol) ), 2,2'-bis(trifluoromethyl)-4,4'-diaminodiphenyl ether 0.336 (0.001mol) and bis(3-aminopropyl) terminal polydimethylsiloxane (0.001mol) 2.5g After the addition, the mixture was reacted at room temperature for 24 hours to prepare a polyamic acid solution, pyridine and acetic anhydride were added to the prepared polyamic acid solution and stirred to prepare a polyimide solution, and the prepared polyimide solution was 100 μm on a glass substrate. It was coated with a thickness of, and put into an oven, and heat treated at 50° C. for 1 hour, followed by heat treatment for 1 hour while heating up to 100° C. at a heating rate of 8° C./min.

<Comparative Example> Preparation of polyimide film

Put 14.3 mL of tetrahydrofuran (THF) in a 100 mL 2-neck round bottom flask substituted with nitrogen gas, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) 0.444 g (0.001 mol) , 2,2´-bis(trifluoromethyl)-[1,1´-biphenyl]-4,4´-diamine (TFMB) 0.198g (0.001mol) was added and reacted at room temperature for 24 hours to make polya Prepare a mixed acid solution, apply the prepared polyamic acid solution to a thickness of 100 µm on a glass substrate, and heat it for 1 hour at 50°C, 100°C, and 150°C in a vacuum oven, respectively, and then 250°C. After heating for 2 hours in the furnace and heated at a temperature of 300 ℃ for 30 minutes) to prepare a polyimide film.

The light transmittances of the polyimide films prepared through Examples 1 to 2 and Comparative Examples were measured and are shown in Table 1 and FIG. 1 below.

(However, in Table 1 below, the light transmittance of the polyimide film was measured at a wavelength of 550 nm, and the light transmittance of the polyimide film was measured using a light transmittance meter.)

<Table 1>

As shown in Table 1 and Figure 1 below, it can be seen that the polyimide films prepared through Examples 1 to 2 of the present invention have excellent light transmittance.

In particular, as shown in Figure 1 below, it can be seen that it shows excellent transmittance in the visible light region of 380 to 800 nm.

In addition, the flexibility of the polyimide films prepared through Examples 1 and 2 and Comparative Examples was confirmed and shown in FIG. 2 below.

As shown in Figure 2 below, it can be seen that the polyimide films prepared through Examples 1 to 2 of the present invention have excellent bent, twisted, rolled-up and wrapped properties.

Therefore, the polyimide film having excellent colorless transparency and flexibility according to the present invention and its manufacturing method have excellent mechanical properties and thermal stability, as well as excellent colorless transparency and flexibility, making the transparent electrode film, solar cell protective film and flexible. Provided is a polyimide film that can be usefully used for a substrate.

Claims (13)

A polyimide film having excellent colorless transparency and flexibility, comprising a polyimide resin having a repeating unit represented by Formula 1 and a repeating unit represented by Formula 2:
[Formula 1]

[Formula 2]

In Formula 1 and Formula 2, R ₁ is

Consisting of one selected from the group consisting of,
The R ₂ is composed of one selected from the group consisting of an alkyl group having 1 to 3 carbon atoms and a phenyl group,
The n is made of an integer from 0 to 700,
The x is 0.01<x<0.99.
The method according to claim 1,
The repeating unit represented by Chemical Formula 1 is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-[1,1' -Biphenyl]-4,4´-diamine (TFMB), bis(3-aminopropyl) polyimide having excellent colorless transparency and flexibility, characterized by being produced by polymerization with terminal polydimethylsiloxane (PDMS) film.
The method according to claim 1,
The repeating unit represented by Chemical Formula 2 is 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-4,4'- A polyimide film having excellent colorless transparency and flexibility, characterized by being produced by polymerization with diaminodiphenyl ether (6FODA) and bis(3-aminopropyl) terminal polydimethylsiloxane (PDMS).
The method according to claim 1,
The polyimide film is a polyimide film excellent in colorless transparency and flexibility, characterized in that the light transmittance is 80% or more.
The method according to claim 1,
The polyimide film is a polyimide film excellent in colorless transparency and flexibility, characterized in that the thermal decomposition temperature is 400 ℃ or more.
A flexible substrate comprising a polyimide film excellent in colorless transparency and flexibility according to any one of claims 1 to 5.
An electronic material comprising a polyimide film having excellent colorless transparency and flexibility according to any one of claims 1 to 5.
4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), 2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4´ A polyamic acid solution preparation step of preparing a polyamic acid solution by copolymerizing diamine (TFMB) and bis(3-aminopropyl) terminal polydimethylsiloxane in an organic solvent;
A polyimide solution preparation step of imidizing the polyamic acid solution prepared through the polyamic acid solution preparation step to prepare a solution of polyimide; And
Method for producing a polyimide film excellent in colorless transparency and flexibility, comprising; a film production step of producing a film by heat-treating the polyimide solution prepared through the polyimide solution manufacturing step.
The method according to claim 8,
The organic solvent is at least one selected from the group consisting of tetrahydrofuran (THF), dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), m-cresol and chloroform. Method for producing a polyimide film excellent in colorless transparency and flexibility, characterized in that consisting of.
The method according to claim 8,
The manufacturing method of the polyimide solution is a method for producing a polyimide film having excellent colorless transparency and flexibility, which is achieved by mixing and stirring an imidation catalyst and a dehydrating agent in a polyamic acid solution.
The method according to claim 10,
The imidization catalyst is a method for producing a polyimide film having excellent colorless transparency and flexibility, characterized in that it consists of one selected from the group consisting of isoquinoline, β-picoline and pyridine.
The method according to claim 10,
The dehydrating agent is a method for producing a polyimide film having excellent colorless transparency and flexibility, which is made of acetic anhydride.
The method according to claim 8,
The film production step is a polyimide solution of 50 to 400 ℃ temperature range of 5 to 10 ℃ / min at a heating rate of 1 minute to 5 hours heat treatment is characterized in that the colorless transparency and flexibility to produce a polyimide film excellent in flexibility Way.

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