KR20190017527A - Polyimide precursor composition and method for producing polyimide film using the same - Google Patents

Abstract

Disclosed is a polyimide precursor composition which can be used for the production of a flexible substrate, a method of manufacturing a polyimide film using the same, and a display element including the polyimide film. The polyimide precursor composition comprises: a mixed solvent containing 3-methoxy-N,N-dimethylpropionamide (M3DMPA) and N,N-dimethylpropionamide (DMPA); and polyamic acid or polyimide. A purpose of the present invention to provide an environmentally friendly polyimide precursor composition using a novel mixed solvent replacing a solvent which is a target of environmental regulation.

Description

TECHNICAL FIELD The present invention relates to a polyimide precursor composition and a method for producing the polyimide film using the polyimide precursor composition.

The present invention relates to a polyimide precursor composition and a method for producing a polyimide film using the polyimide precursor composition. More particularly, the present invention relates to a polyimide precursor composition that can be used for the production of a flexible substrate, To a display element comprising a film.

Recently, there is an increasing demand for a flat panel display (FPD) that can be easily realized in a large area and can be made thin and light. Such a flat panel display includes a liquid crystal display (LCD), a plasma display panel (PDP), and an organic light emitting display (OLED). However, since conventional flat panel displays use a glass substrate, they are not flexible and thus have limited applications and applications. Accordingly, a flexible display device, which is manufactured so as to be bent by using a substrate of a flexible material such as plastic, foil or the like instead of a glass substrate having no flexibility, has been actively developed as a next generation display device.

The flexible display device is generally manufactured by a high-temperature TFT (Thin Film Transistor) process. The process temperature may vary depending on the type of the semiconductor layer, the insulating film, and the barrier layer included in the device, but a temperature of about 300 to 500 ° C is generally required in the TFT process. However, polymer materials that can withstand such process temperatures are extremely limited, and polyimides known to have excellent heat resistance are mainly used. Since polyimide materials have excellent thermal properties and are flexible and lightweight, polyimide substrates are attracting the most attention as plastic substrates that can replace conventional glass substrates.

There are various processes for manufacturing a polyimide substrate. Among them, the most commonly used method is a method in which a polyamic acid polymer solution is applied to a carrier glass using a spin or a slit coater And then the film is coated to a predetermined thickness and then subjected to a thermal imidization reaction and a solvent removal process through Convection Oven or IR Oven to produce a polyimide substrate. In the flexible display production process, a TFT backplane, an organic light emitting layer, and the like are formed on a polyimide substrate, and the product is separated from a carrier glass by a laser lift off method. Since the polyimide material is liable to warp, the subsequent process proceeds with the substrate fixed to the carrier glass. In a TFT or a deposition process, since the process proceeds at a relatively high temperature, when the difference in thermal expansion coefficient between the polyimide material and the carrier glass is large, it is important that the carrier glass has a similar thermal expansion coefficient.

, 끓는점: 165.1 ℃), 디메틸포름아미드(Dimethylformamide: DMF,

, 끓는점: 153 ℃), N-메틸피롤리돈(N- Methylpyrrolidone: NMP,

, 끓는점: 202, ℃) 등이 일반적으로 사용되고 있으나, 이들은 환경 규제 대상으로 사용이 제한되어 다른 용매로의 대체가 필요하다.The polyamic acid polymer solution is prepared by polymerizing a diamine and a dianhydride in a polar solvent, and the polar solvent includes dimethylacetamide (DMAC,

, Boiling point: 165.1 占 폚), dimethylformamide (DMF,

, Boiling point: 153 占 폚), N-methylpyrrolidone (NMP,

, Boiling point: 202, ℃) are generally used, but they are restricted to be used for environmental regulation and need to be replaced with other solvents.

In addition, in the thermal imidation process for fabricating the polyimide substrate, the lead time is determined by a high temperature curing process in the oven. In order to reduce the lead time, the temperature rise time is shortened and the holding time at each temperature step is shortened And various attempts have been made. In addition, defects are generated on the coated surface due to rapid solvent evaporation during the high-temperature process (120 ° C process start and 450 ° cure process) and high-speed drying process.

An object of the present invention is to provide an environmentally friendly polyimide precursor composition using a new mixed solvent replacing a solvent to be environmentally controlled.

Another object of the present invention is to provide a method for producing a polyimide film having excellent properties by using the polyimide precursor composition.

Disclosure of the Invention In order to achieve the above object, the present invention provides a mixed solvent comprising 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA); And a polyamic acid or polyimide.

The composition according to the present invention uses a new mixed solvent that replaces the environmentally regulated solvent. From the use of new mixed solvents, high temperature curing and quick drying processes can shorten the polyimide film manufacturing process lead time. Further, from the use of a mixed solvent containing two solvents having different volatilities, a polyimide film having excellent transmittance and surface characteristics can be obtained.

Hereinafter, the present invention will be described in detail.

The composition of the present invention comprises a mixed solvent comprising 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA); And polyamic acid or polyimide.

, 끓는점: 188.7℃) 및 N,N-디메틸프로피온아미드(N,N-Dimethylpropionamide; DMPA,

, 끓는점: 174-176℃)를 혼합한 것으로서, 고온 공정 시 용매의 급격한 휘발로 인한 표면 결함을 방지하고, 폴리이미드 필름의 투과율과 표면 특성을 개선한다.The mixed solvent used in the present invention is a mixture of 2-methoxy-N, N-dimethylpropionamide (M3DMPA,

, Boiling point: 188.7 占 폚) and N, N-Dimethylpropionamide (DMPA,

, Boiling point: 174-176 DEG C), which prevents surface defects due to rapid volatilization of the solvent during the high temperature process and improves the transmittance and surface characteristics of the polyimide film.

The mixing ratio (weight ratio) of the 3-methoxy-N, N-dimethylpropionamide (M3DMPA): N, N-dimethylpropionamide (DMPA) is 1: 99 to 99: 1, preferably 3: : 3, and can be, for example, a weight ratio of 5: 5. If the amount of the 3-methoxy-N, N-dimethylpropionamide (M3DMPA) is too small, there is a problem that the film surface is poor in the fast drying process. If the amount is too large, There is a problem of lowering.

The polyamic acid used in the composition of the present invention is a compound having an amine group and a carboxyl group in a molecule and reacts with an amine group and a carboxyl group by heating to form an imine group. In the mixed solvent, a diamine monomer and a dianhydride monomer are reacted Can be manufactured.

Examples of the diamine monomer include p-phenylenediamine (PPDA), 4,4'-oxydianiline (ODA), 4,4'-methylenedianiline (4,4 ' -Methylenedianiline (MDA), m-Tolidin (2,2'-Dimethyl-4,4'-Diaminobiphenyl), 1,3-bis (4'-aminophenoxy) benzene (2,2'-bis (trifluoromethyl) benzidine: TFMB) containing a fluorine group, 2, 2'-bis (trifluoromethyl) benzene: Bis (4-aminophenoxy) phenyl] hexafluoropropane (HFBAPP), 2,2-bis (3 Amino-4-hydroxyphenyl) hexafluoropropane (BIS-AP-AF), 1,3-diamino-2,4,5- 3,3'-Diaminodiphenyl Sulfone (DDS) containing 3-diamino-2,4,5,6-tetrafluorobenzene (DRFB) ), 4,4'-diaminodiphenyl sulfide (4,4'-Diaminodiphenyl Sulf (ASD), bis [4- (4-aminophenoxy) phenyl] sulfone: BAPS), 2,2-bis [4- Benzene] sulfone (m-BAPS) can be used. One or more monomers may be used in combination. In order to ensure high heat resistance, p-phenylenediamine (PPDA), which is an aromatic monomer, is suitable.

As the dianhydride monomer, an aromatic dianhydride compound is suitable, and 3,3 ', 4,4'-benzophenone tetracarboxylic acid is an anhydride (3,3', 4,4'-benzophenonetetracarboxylic dianhydride: 2, 3,3 ', 4,4'-biphenyl tetracarboxylic acid dianhydride (BPDA), 2, 3', 4,4'-biphenyltetracarboxylic dianhydride (BTDA), pyromellitic dianhydride 2-bis (3,4-anhydrodicarboxyphenyl) -hexafluoropropane dianhydride (6FDA), 2,3,3 ', 4- Biphenyl tetracarboxylicacid dianhydride (a-BPDA), 4,4'-oxydiphthalic anhydride (ODPA), 3,3 ', 4,4'-biphenyl tetracarboxylic acid dianhydride , 4,4'-diphenylsulfone-tetracarboxylic dianhydride (DSDA), 2,2-bis [4- (3,4-dicarboxyphenoxy ) Phenyl] propane dianhydride (2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride (BPADA), hydroquinone diphthalic anhydride (HQDA), and the like. Among them, monomers or monomers of more than two kinds can be used in combination. In order to ensure high heat resistance, 3,3 ', 4,4'-biphenyl tetracarboxylic acid dianhydride (3,3'4,4'-Biphenyl tetracarboxylic acid dianhydride : BPDA) is appropriate.

The composition of the present invention may further contain additives as required. The additive may be a material containing an epoxy polyfunctional group and may serve to improve defects on the coated surface together with the mixed solvent. The additive may be, for example, an ethylene glycol diglycidyl ether represented by the following formula: [Formula 1-2] N, N-Diglycidyl-4-Glycidyloxyaniline, Bis ((2,3-epoxypropoxy) methyl) cyclohexane, 2,2 '- [1,3-Phenylenebis (oxymethylene)] dioxirane, , N-diglycidyl aniline, and the like, but the present invention is not limited thereto. A resin containing an epoxy polyfunctional group can be used as an additive.

The additive may be added in an amount of 0.02 to 1.2 parts by weight based on 100 parts by weight of polyamic acid or polyimide. If the added amount of the additive is too small, there is a problem that the surface of the film is floated, and when it is too much, the transmittance of the film is lowered (less than 50%).

The additive may be added to the composition of the present invention after dissolving in a solvent. The solvent in which the additive is dissolved is 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N- dimethylpropionamide (DMPA) But the present invention is not limited thereto, and other kinds of solvents may be used for improving the physical properties.

 [Formula 1-1]

[Formula 1-2]

[Formula 1-3]

[Chemistry 1-4]

[Formula 1-5]

In the composition of the present invention, the polyamic acid or polyimide may be used in an amount of 5 to 30 parts by weight, preferably 8 to 20 parts by weight, more preferably 10 to 15 parts by weight, based on 100 parts by weight of the mixed solvent. If the content of the polyamic acid or polyimide is too low, it is difficult to obtain a polyimide film having a uniform thickness because of low viscosity. When the polyamic acid or polyimide is added to a high-temperature bake, the surface is likely to be poor due to rapid solvent volatilization. The slit coating is difficult to control the thickness of the film, so that a relatively thick film is likely to be formed.

In the composition of the present invention, the viscosity of the composition may be 1000 to 20000 cps. When the viscosity is less than 1000 cps, a polyimide thin film having a small thickness can be formed due to a relatively large amount of low molecular weight, high flowability during coating, and when the viscosity exceeds 20000 cps, It may be difficult to obtain an adequate polyimide film thickness because a thick thick film is formed apart.

Next, a method for producing the polyimide film according to the present invention will be described.

In order to produce the polyimide film according to the present invention, first, the composition is coated on a carrier substrate (carrier glass or the like) with a thickness of 400 μm (wet thickness) using an applicator. As the carrier substrate, a glass substrate, a metal substrate, a plastic substrate, or the like can be used without any particular limitation. Among these, the carrier substrate is excellent in heat and chemical stability during the curing process for the polyimide precursor, A glass substrate that can be easily separated without damaging the mid-based film is preferred. The coating (coating) process may be carried out according to a conventional coating method. Specifically, the coating (coating) process may be performed by a spin coating method, a bar coating method, a roll coating method, an air-knife method, a gravure method, a reverse roll method, a kiss roll method, , A spray method, a dipping method, or a brushing method may be used

The composition can be applied over the substrate in a thickness range such that the polyimide film to be finally produced has a suitable thickness as the display substrate. Specifically, after the solvent evaporation and curing, it may be applied in an amount such that the final thickness is 1 to 30 占 퐉. After the coating (coating) process, a drying process for removing the solvent present in the composition prior to the curing process may be further optionally performed. The drying process may be carried out according to a conventional method. Specifically, the drying process may be performed at a temperature of 140 ° C or lower, or 80-140 ° C. If the drying temperature is lower than 80 캜, the drying process becomes longer. If the drying temperature is higher than 140 캜, the imidization rapidly proceeds to make it difficult to form a polyimide film having a uniform thickness.

On the other hand, since the curing process through the thermal imidization process takes a long time, it is necessary to reduce the curing process time to increase the production amount. Attempts have been made to reduce the processing time by charging the next coated substrate without the oven being completely cooled. In the present invention, in a convection oven in which the cooling is not completed in a curing process, for example, at a temperature of 100 ° C, heating is carried out at a heating rate of 5 to 10 ° C per minute up to 450 ° C to produce a polyimide film Can be prepared. The curing process may optionally be carried out by heating to a temperature of 300 to 450 ° C. The curing process may be a multi-step process through a stepwise heat treatment within the temperature range described above. For example, the curing process may be first heat treatment at a temperature of 200 캜, second heat treatment at a temperature of 300 캜, But the present invention is not limited thereto. In addition, the curing time in the curing step is not particularly limited and can be, for example, 3 to 60 minutes.

After the curing step, a subsequent heat treatment step may be selectively performed to increase the imidization ratio of the polyimide resin in the polyimide film to form a polyimide film having excellent physical properties. The subsequent heat treatment may be performed at 200 ° C or higher, or 200 ° C to 450 ° C for 1 minute to 30 minutes. The subsequent heat treatment process may be performed once or may be performed in two or more stages. Specifically, it may be carried out in three stages including a first heat treatment at 200 to 220 占 폚, a second heat treatment at 300 to 350 占 폚, and a third heat treatment at 400 to 450 占 폚. Then, the polyimide film formed on the substrate after cooling can be completed by peeling off the carrier substrate from the substrate by a conventional method.

When the composition of the present invention contains a polyimide together with a mixed solvent, the polyimide film can be produced by coating the composition and then evaporating the solvent since the imidization is carried out. The evaporation of the solvent can be carried out, for example, by heating to a temperature of 200 DEG C or higher, but is not limited thereto.

A display substrate and an element including the polyimide film may be provided. Specifically, the device can be any solar cell having a flexible substrate (e.g., a flexible solar cell), organic light emitting diode (OLED) lighting (e.g., flexible OLED lighting) Device, or an organic electroluminescent device having a flexible substrate, an electrophoretic device, or an LCD device.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples illustrate the present invention and are not intended to limit the scope of the present invention.

[Example 1] Preparation of polyimide precursor composition :

Phenylenediamine (PPDA) 21.62 was added to 529.2 g of a mixed solvent in which 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA) g (0.2 mol) was completely dissolved at room temperature, and then 58.84 g (0.2 mol) of 3,3'4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added thereto and reacted. After stirring for 18 hours, A composition containing 15 parts by weight of polyamic acid (polyimide precursor) relative to 100 parts by weight of the mixed solvent was obtained. The viscosity of the composition was measured using a Brookfield viscometer to confirm whether the polymerization proceeded to make it possible to form a film, and the viscosity of the obtained polyamic acid composition was 13500 cps.

[Example 2] Production of polyimide precursor composition :

Except that the mixing ratio of 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA) was 3: 7, Polyimide precursor) composition. The viscosity of the obtained polyamic acid composition was 13000 cps.

[Example 3] Preparation of polyimide precursor composition :

The procedure of Example 1 was repeated except that the mixing ratio of 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA) was changed to 5: Polyimide precursor) composition. The viscosity of the obtained polyamic acid composition was 12500 cps.

[Example 4] Production of polyimide precursor composition :

Except that the mixing ratio of 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA) was changed to 7: 3, Polyimide precursor) composition. The viscosity of the obtained polyamic acid composition was 13,400 cps.

[Example 5] Preparation of polyimide precursor composition :

Except that the mixing ratio of 3-methoxy-N, N-dimethylpropionamide (M3DMPA) and N, N-dimethylpropionamide (DMPA) was changed to 9: 1. Polyimide precursor) composition. The viscosity of the obtained polyamic acid composition was 13,400 cps.

[Examples 1-1 to 1-5] Preparation of polyimide film :

N, N-Diglycidyl-4-Glycidyloxyaniline was added to the polyamic acid composition obtained in Example 1 in accordance with the amount of the polyamic acid monomer solid added to the amount of the polyamic acid monomer in Table 1, and the mixture was stirred to prepare a coating liquid composition. The prepared coating liquid composition was coated on a carrier glass to a thickness of 350 mu m (wet thickness) using an applicator and heated in a convection oven at 450 DEG C at a rate of 8 DEG C per minute Thermal imide reaction proceeded. The external shape and optical characteristics of the obtained polyimide film were analyzed and shown in Table 1.

[Examples 2-1 to 2-5] Preparation of polyimide film :

Except that N, N-Diglycidyl-4-Glycidyloxyaniline was mixed with the polyamic acid composition obtained in Example 2 in accordance with the amount of the polyamic acid monomer solid content added in Table 2 relative to the amount of the polyamic acid monomer solid content. The imide reaction proceeded, and the external shape and optical characteristics of the obtained polyimide film were analyzed and shown in Table 2.

[Examples 3-1 to 3-5] Preparation of polyimide film :

Except that N, N-Diglycidyl-4-Glycidyloxyaniline was mixed with the polyamic acid composition obtained in Example 3 in accordance with the amount of the polyamic acid monomer solid content added in Table 3 in relation to the amount of the polyamic acid monomer solid content. The imide reaction proceeded, and the external shape and optical characteristics of the polyimide film thus obtained were analyzed and shown in Table 3.

[Examples 4-1 to 4-5] Preparation of polyimide film :

Except that N, N-Diglycidyl-4-Glycidyloxyaniline was mixed with the polyamic acid composition obtained in Example 4 in accordance with the amount of the polyamic acid monomer solid content added in Table 4 with respect to the amount of the polyamic acid monomer solid content. Imide reaction proceeded, and the external shape and optical characteristics of the obtained polyimide film were analyzed and shown in Table 4. [

[Examples 5-1 to 5-5] Preparation of polyimide film :

Except that N, N-Diglycidyl-4-Glycidyloxyaniline was mixed with the polyamic acid composition obtained in Example 5 in accordance with the addition amount of the polyamic acid monomer in the amount shown in Table 5 with respect to the amount of the solid content of the polyamic acid monomer. Imide reaction proceeded, and the external shape and optical characteristics of the obtained polyimide film were analyzed and shown in Table 5.

[Comparative Examples 1-1 to 1-5] Preparation of polyimide film :

Except that polyamic acid composition was prepared using only 3-methoxy-N, N-dimethylpropionamide (M3DMPA) as a solvent, thermal imidization reaction was carried out in the same manner as in Examples 1-1 to 1-5 And the external shape and optical characteristics of the obtained polyimide film were analyzed and shown in Table 6.

[Comparative Examples 2-1 to 2-5] Preparation of polyimide film :

The thermal imide reaction was carried out in the same manner as in Examples 1-1 to 1-5 except that the polyamic acid composition was prepared using only N, N-dimethylpropionamide (DMPA) as a solvent, and the obtained polyimide The external shape and optical properties of the film were analyzed and shown in Table 7.

≪ Analysis of polyimide physical properties &

[Measurement of viscosity]

The average value was measured after three measurements at 25 ° C using a rotating high viscosity viscometer (BrookField corn-plate method).

[Film thickness]

The thickness of the film was measured 10 times using ultrasonic thickness measuring equipment (Qnix4500) and the mean value and standard deviation were confirmed.

[Measurement of transmittance]

The average transmittance in the visible light region was measured five times using an optical measuring instrument (Nippon Denshoku Co., COH-400), and the average value was measured.

[Mechanical Properties - Stress, Strain]

The UTM (Universal Test Machine) of Ametek LLOYD Instrument was used to measure the mechanical properties of the polyimide film. The film specimen was prepared with a width of 5 mm and a length of 70 mm or more. The grip to grip size was set to 30 mm. The tensile rate was measured 10 times at a rate of 10 mm / min.

(M3DMPA: PPDA = 1: 9) division Example 1-1 Examples 1-2 Example 1-3 Examples 1-4 Examples 1-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 60 58 56 52 49 Film surface condition Surface unevenness and floating Good surface Good surface Good surface Good surface thickness
(μm) Average 17.42 16.85 17.42 17.55 16.56 stdev 1.2 1.4 1.2 1.1 1.0 Stress
(MPa) Average 353.2 348.1 359.8 363.1 361.1 stdev 10.2 10.7 10.3 11.2 12.1 Strain
(%) Average 28.3 25.3 26.2 27.1 25.1 stdev 0.8 1.0 0.9 1.1 1.2

(M3DMPA: PPDA = 3: 7) division Example 2-1 Example 2-2 Example 2-3 Examples 2-4 Example 2-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 57 56 53 51 48 Film surface condition Surface unevenness and floating Good surface Good surface Good surface Good surface thickness
(μm) Average 17.23 17.34 17.15 17.49 17.51 stdev 1.2 0.6 0.8 0.9 0.9 Stress
(MPa) Average 343.9 352.4 356.3 364.4 361.1 stdev 8.0 7.8 9.3 7.9 8.2 Strain
(%) Average 28.9 31.2 35.2 33.5 32.9 stdev 0.7 0.8 0.7 0.7 0.5

(M3DMPA: PPDA = 5: 5) division Example 3-1 Example 3-2 Example 3-3 Example 3-4 Example 3-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 57 55 54 51 47 Film surface condition Surface unevenness and floating Good surface Good surface Good surface Good surface thickness
(μm) Average 17.11 17.24 17.39 17.33 17.39 stdev 1.2 0.3 0.1 0.1 0.3 Stress
(MPa) Average 341.0 360.1 364.2 369.8 368.7 stdev 7.3 4.7 3.5 4.4 3.9 Strain
(%) Average 27.3 30.2 31.8 30.2 32.9 stdev 0.5 0.3 0.4 0.3 0.2

(M3DMPA: PPDA = 7: 3) division Example 4-1 Example 4-2 Example 4-3 Example 4-4 Example 4-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 56 53 51 50 46 Film surface condition Surface unevenness and floating Good surface Good surface Good surface Good surface thickness
(μm) Average 17.07 17.30 17.35 17.14 17.88 stdev 1.1 0.9 0.9 1.0 1.0 Stress
(MPa) Average 333.1 348.4 349.1 354.7 350.04 stdev 10.4 8.0 8.1 7.1 7.9 Strain
(%) Average 24.6 29.2 27.1 27.9 28.7 stdev 1.1 0.7 0.6 0.8 0.8

(M3DMPA: PPDA = 9: 1) division Example 5-1 Example 5-2 Example 5-3 Examples 5-4 Example 5-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 57 51 51 51 46 Film surface condition Surface unevenness and floating Good surface Good surface Good surface Good surface thickness
(μm) Average 17.51 16.91 16.94 17.38 17.30 stdev 1.4 1.0 1.2 1.4 1.2 Stress
(MPa) Average 333.1 351.3 347.7 348.3 355.2 stdev 15.0 11.4 10.4 9.7 10.3 Strain
(%) Average 24.4 27.4 28.6 29.1 28.2 stdev 1.8 1.1 1.2 1.2 1.4

(M3DMPA: PPDA = 100%) division Comparative Example 1-1 Comparative Example 1-2 Comparative Example 1-3 Comparative Example 1-4 Comparative Example 1-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 51 50 49 47 47 Film surface condition Surface unevenness and floating Surface unevenness and floating Surface unevenness and floating Surface unevenness and floating Surface unevenness and floating thickness
(μm) Average 17.46 17.61 17.31 17.38 17.27 stdev 2.1 1.6 1.5 1.3 1.4 Stress
(MPa) Average 329.5 336.4 359.2 349.3 340.7 stdev 20.1 17.2 15.2 12.0 14.8 Strain
(%) Average 21.8 24.4 27.9 27.1 26.2 stdev 1.6 1.2 1.2 1.5 1.8

(100%) division Comparative Example 2-1 Comparative Example 2-2 Comparative Example 2-3 Comparative Example 2-4 Comparative Example 2-5 Additive input
(ppm) 100 200 5,000 12,000 12,500 Permeability (%) 64 63 60 57 52 Film surface condition Surface unevenness and floating Surface unevenness and floating Surface unevenness and floating Surface unevenness and floating Surface unevenness and floating thickness
(μm) Average 17.25 17.32 17.09 17.36 17.45 stdev 2.1 1.5 1.3 1.4 1.6 Stress
(MPa) Average 334.2 349.2 359.8 364.5 347.3 stdev 17.2 16.4 17.6 15.7 15.2 Strain
(%) Average 21.5 24.3 24.5 26.3 22.5 stdev 1.7 1.5 1.6 1.4 1.5

As can be seen from Tables 1 to 7, it can be seen that the surface state of the polyimide film is good and a transmittance of 50% or more can be obtained by using a mixed solvent. However, it can be seen that when the amount of the additive is small, the transmittance is excellent, but the surface condition can be poor, and when an excessive amount of additive is added, the transmittance is remarkably decreased to less than 50%.

In addition, when M3DMPA or DMPA, which is not a mixed solvent of the present invention, was used alone, it was confirmed that the surface state of the film was poor. From the results, it was found that the surface state of the polyimide film It can be seen that there is an effect that can be improved,

In particular, when the composition is rapidly dried at a rapid heating rate, for example, at a heating rate of 8 ° C as in the examples, the composition using the mixed solvent of the present invention has a good effect on the surface condition of the film, while DMPA When the same kind of solvent is used, it can be confirmed that the surface condition of the film is poor.

Further, from the viewpoint of the standard deviation of the film thickness, it can be seen that the standard deviation of the thickness is not more than 1, that is, the difference in thickness is not so large when the mixed solvent of the present invention is used,

In the case of using the mixed solvent of the present invention, the deviations were respectively less than 10 and not more than 1 in the stress and the strain, and the mechanical properties of the polyimide film produced from the mixed solvent It can be seen that the polyimide film is excellent in reliability because no large fluctuation occurs.

Claims (6)

A mixed solvent comprising 3-methoxy-N, N-dimethylpropionamide and N, N-dimethylpropionamide; And
Polyamic acid or polyimide. The composition according to claim 1, comprising 5 to 30 parts by weight of a polyamic acid or polyimide based on 100 parts by weight of the mixed solvent. [3] The method according to claim 1, wherein the ethylene glycol diglycidyl ether, N, N-diglycidyl-4-glycidyloxyaniline, 1,4-bis ((2,3- One or two selected from the group consisting of 2,2 '- [1,3-phenylenebis (oxymethylene)] dioxirane and 4,4'-methylenebis N, N-diglycidylaniline. ≪ / RTI > more than one kind of additive.
4. The composition of claim 3 comprising from 0.02 to 1.2 parts by weight of the additive based on 100 parts by weight of the polyamic acid or polyimide. The composition of claim 1, wherein 3-methoxy-N, N-dimethylpropionamide and N, N-dimethylpropionamide are included in a weight ratio of 3: 7 to 7: 3. The composition of claim 1, wherein the composition has a viscosity of from 1,000 to 20,000 cps.