WO2014133297A1 - Method for producing colorless and transparent polyimide film impregnated with glass fabric and planarizing surface thereof - Google Patents

Abstract

The present invention relates to a method for producing a polyimide film, the method comprising a two-stage planarization step for planarizing the surface of a colorless and transparent polyimide (CPI) film impregnated with a glass fabric by a roll-to-roll process, and the purpose of the present invention is to solve a problem of an increase in the surface roughness of a polyimide substrate, which inevitably occurs when a glass fabric is impregnated into a colorless and transparent polyimide film in order to improve thermal and mechanical properties of a film that is used for a flexible display substrate and a cover window of a flat panel display or a cellular phone. According to the present invention, the surface of a colorless and transparent polyimide film impregnated with a glass fabric is planarized such that the roughness thereof is reduced from a range of about several tens of nanometers to several microns to about several nanometers, which enables a TFT process to be carried out on a substrate made of the colorless and transparent polyimide film, and increases the optical transmittance and transparency of the colorless and transparent polyimide film, thereby allowing the colorless and transparent polyimide film to be used for a flexible display substrate and a cover window of a flat panel display or a cellular phone.

Description

Method for preparing colorless and transparent polyimide film impregnated with glass fiber fabric and surface planarization method

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a colorless transparent polyimide film impregnated with a glass fiber fabric and to a surface planarizing method, and more particularly, to a film for a cover window of a flexible display substrate and a flat panel display and a mobile phone. Increasing the surface roughness of polyimide substrates caused by impregnating glass fabric in colorless and transparent polyimide (CPI) films to improve thermal and mechanical properties. It relates to a method for producing a polyimide film impregnated with a glass fiber fabric that can solve the problem, and a method for planarizing the surface of the colorless transparent polyimide film impregnated with the glass fiber fabric.

Currently, flat panel displays using electronic paper (EPD), plasma display (PDP), liquid crystal display (LCD) and organic light emitting display (OLED) technologies are widely used in TVs, mobile phones, monitors, e-books and mobile devices. It is used.

However, in the next generation, it is expected that a flexible display that is easy to carry and can be conveniently used anytime and anywhere, will be widely used in electronic devices such as mobile phones, portable terminals, and notebook computers.

Flexible displays must use a substrate that is mechanically flexible so that it can bend or fold well. Very thin glass plates, thin stainless steel plates, plastic films and the like can be used as flexible substrates, of which plastic films are most advantageous.

In addition, glass is currently used as a cover window of flat panel displays such as TVs, monitors, and mobile phones. Glass has excellent characteristics in heat resistance, light transmittance, and mechanical strength, but has a disadvantage of being heavy and fragile. Colorless transparent plastic films are being reviewed in the art.

However, plastic film substrates are much more mechanically flexible than glass substrates, but their tensile strength is inferior to glass substrates. Impregnating a glass film with a plastic film, such as fiber reinforced plastic (FRP), The tensile strength of plastic films can be increased to the level of tempered glass, and Korean Patent Publication No. 10-2010-0118220 (Invention: Flexible Substrate for Display Panel and Manufacturing Method thereof), 10-2010-0118222 (Invention) Names: Flexible substrates for display panels and methods for manufacturing the same, No. 10-2012-0027632 (name of the invention: manufacturing method of a flexible device), and No. 10-2011-0055425 (name of the invention: excellent thermal expansion characteristics and Polymer-organic nanofiber composite having a light-transmitting property and a light-transmissive composite film using the same), and the like, and are widely used.

Polyimide films are widely used in electronic materials such as insulation films, flexible cables, and printed circuit boards because of their flexibility, heat resistance, abrasion resistance, insulation, chemical resistance and mechanical strength. Has been used. The general polyimide film has a dark brown color, and thus has not been used in display substrates despite the excellent physical properties, but recently, colorless and transparent polyimide has been developed and used as a display substrate.

In order to fabricate a display device, a thin film transistor (TFT) must be fabricated on a substrate to control individual pixels and adjust brightness. Currently, TFTs using amorphous silicon, polysilicon, oxides, organics, and the like are used, but in the case of amorphous silicon showing the most stable performance, the minimum process temperature required for deposition and heat treatment is about 230 ° C. After the TFT thin film process is performed on the plastic substrate at 230 ° C and the temperature is lowered to room temperature, the TFT thin film is peeled from the plastic substrate due to the difference in the coefficient of thermal expansion (CTE) between the plastic substrate and the TFT thin film material. In order to do this, the thermal expansion coefficient of the substrate must be 10 ppm (part per million) / ° C or less.

The thermal expansion coefficient of the colorless transparent polyimide (CPI) is at least 50 ppm / ° C, but the colorless transparent polyimide impregnated with the glass fiber fabric by impregnating the colorless transparent polyimide film with a glass fiber fabric having a coefficient of thermal expansion of about 5 ppm / ° C. It is possible to reduce the coefficient of thermal expansion of the film substrate to the level of 10 ppm / ° C.

In the process of forming a colorless transparent polyimide film impregnated with a glass fiber fabric using a solution process, the surface of the film is inevitably roughened to several 10 nm to 1 μm due to the following causes.

When the fiberglass fabric is placed on a glass plate and the polyamic acid solution is poured on it, the polyamic acid solution forms a complete horizontal plane by gravity, but since the woven surface of the fiberglass fabric is not flat, The thickness up to the surface of the acid solution depends on the location.

That is, the thickness of the polyamic acid solution in the glass fiber raised portion is thin, the polyamic acid solution located in the glass fiber lowered portion is thick (see Fig. 1a), the solvent evaporates during the colorless transparent polyimide film forming process and the polymerization reaction is When this occurs, shrinkage occurs in the thin part of the solution and shrinkage occurs in the thick part of the solution, so that the surface of the formed colorless transparent polyimide film has irregularities similar to the surface topography of the glass fiber fabric. (See FIG. 1B), the surface roughness of the concave-convex reaches up to 1 μm at the minimum of several 10 nm depending on the thickness of the glass fiber fabric.

In addition, when the surface of the substrate becomes rough, even if the refractive index of the colorless and transparent polyimide film and the refractive index of the glass fiber coincide, the surface roughness of the order of 10 nm to 1 μm scatters the light and scatters the light so that the light transmittance of the substrate In addition to significantly reducing optical transmittance and transparency, a problem arises that makes a thin film transistor (TFT) process essential for display device fabrication.

In order to increase the light transmittance and transparency of the substrate and to enable the TFT process on the substrate, the surface roughness of the substrate must be on the order of 1 nm.

In general, since the thin film thickness of the coating used for the surface planarization of the display substrate is a few levels, it is difficult to planarize a film surface having a roughness of several 10 nm to 1 µm to a surface roughness of 1 nm level by the planarization coating.

Therefore, in order to planarize the surface of the colorless transparent polyimide film impregnated with glass fiber fabric to a surface roughness of 1 nm level using a flattening coating, it is necessary to make the surface roughness of the colorless transparent polyimide film impregnated with glass fiber fabric to several nm level. There is.

After all, the present invention has been made to solve the problems of the prior art, the main object of the present invention is to provide a method for producing a polyimide film impregnated with a glass fiber fabric comprising a two-step flattening step.

In addition, another object of the present invention is to provide the roughness of the film surface which is inevitably encountered when impregnated with a colorless transparent polyimide film in order to improve the thermal and mechanical properties of the glass substrate replacement substrate for flexible displays and flat panel displays. It is to provide a method for planarization in a continuous process.

 In addition, another object of the present invention to provide a colorless transparent polyimide film prepared by the above method.

In order to achieve the above object, the present invention provides a method for producing a polyimide film impregnated with a glass fiber fabric comprising a two-step flattening step.

In the present invention, in the first planarization step, after the solvent is evaporated from a colorless transparent polyamic acid solution, which is a precursor of polyimide, to prepare a film, two rollers having a smooth and cylindrical surface The film is positioned between the rollers and the gap between the two rollers is adjusted to pass the film between the two rollers while applying pressure to the film to planarize the film surface.

The flattened colorless transparent polyamic acid film has a ring-closing and dehydration reaction during imidization to produce a colorless transparent polyimide film, so that the surface of the colorless transparent polyimide film is Again, the roughness of the colorless transparent polyimide film is much smaller than the roughness before the polyamic acid film is flattened.

Therefore, in the second planarization step, the surface roughness of the colorless transparent polyimide film produced by the imidization reaction is flattened, and the colorless transparent polyimide film is formed between another pair of rollers having a smooth and cylindrical surface. By placing the film and adjusting the spacing between the pair of rollers to achieve a planarization of the film surface by passing the film between the two rollers while applying pressure to the film.

In addition, the present invention comprises the steps of flattening a polyamic acid film impregnated with a glass fiber fabric; And planarizing the polyimide film prepared by using the polyamic acid film of the above step.

In addition, the present invention provides a colorless transparent polyimide film impregnated with a glass fiber fabric prepared by the above method.

According to the present invention as described above, the present invention by flattening the surface roughness of the colorless transparent polyimide film substrate for flexible display and glass substrate replacement impregnated with glass fiber fabric from the level of several 10 nm to 1 ㎛ level to several nm level, By preventing the surface scattering of light to increase the light transmittance and transparency of the colorless transparent polyimide film substrate impregnated with glass fiber fabric, there is an effect that enables the TFT process on the substrate.

1A and 1B are schematic views showing the cause of the colorless transparent polyamic acid film or the colorless transparent polyimide film impregnated with glass fiber fabric having a large surface roughness.

Figure 2 is a schematic view illustrating the principle that the surface of the colorless transparent polyamic acid film or polyimide film impregnated with a glass fiber fabric.

Figures 3a to 3f is a schematic view showing the manufacturing process of a polyimide film impregnated with a glass fiber fabric comprising a two-step flattening step according to the present invention.

Figure 4 is a schematic diagram showing the planarization process of a colorless transparent polyamic acid film or polyimide film impregnated with a glass fiber fabric using N pairs of rollers according to the present invention.

5a to 5f are schematic views showing the planarization process of a polyimide film impregnated with a glass fiber fabric using a flat plate according to the present invention.

6 is an AFM photograph showing the surface roughness of a polyimide film impregnated with a flattened glass fiber fabric according to the first embodiment of the present invention.

7 is an AFM photograph showing the surface roughness of a polyimide film impregnated with a flattened glass fiber fabric according to a second embodiment of the present invention.

8A is an AFM photograph showing the surface roughness of a polyamic acid film impregnated with a flattened glass fiber fabric according to a third embodiment of the present invention.

8B is an AFM photograph showing the surface roughness of a polyimide film impregnated with a flattened glass fiber fabric according to a third embodiment of the present invention.

[Description of the code]

101: substrate

102: polyamic acid solution

103, 203, 302, 402, 503: glass fiber fabric

104, 301: Rough, colorless, transparent polyamic acid film impregnated with glass fiber fabric

201: Lower roller portion in contact with a rough, colorless, transparent polyamic acid film or polyimide film

202, 401: colorless transparent polyamic acid film with a rough surface impregnated with glass fiber fabric or colorless transparent polyimide film with a rough surface impregnated with glass fiber fabric

204: Part of the upper roller in contact with the rough surface colorless transparent polyamic acid film or polyimide film

305, 315, 405: lower roller

306, 316, 406: upper roller

303, 313, 403: lower roller heater

304, 314, 404: Upper Roller Heaters

307, 317, 407: lower roller shaft

308, 318, 408: upper roller shaft

309: Colorless and transparent polyamic acid film impregnated with glass fiber fabric with flattened surface

310: colorless transparent polyimide film having a rough surface impregnated with a glass fiber fabric

319: Colorless and transparent polyimide film impregnated with glass fiber fabric with flattened surface

409: colorless transparent polyamic acid film impregnated with glass fiber fabric with flattened surface or colorless transparent polyimide film impregnated with glass fiber fabric with flattened surface

501: lower glass plate

502: colorless transparent polyimide film having a rough surface impregnated with glass fiber fabric

504: upper glass plate

505: lower heater

506: upper heater

507: lower plate

508: upper plate

509: Colorless transparent polyimide film impregnated with glass fiber fabric with flattened surface

 Hereinafter, the present invention will be described in detail.

The present invention provides a method for producing a polyimide film impregnated with a glass fiber fabric comprising a two-step flattening step.

In the present invention, the method for producing a polyimide film impregnated with a glass fiber fabric,

(1) impregnating a glass fiber fabric with a polyamic acid solution to produce a polyamic acid film impregnated with a glass fiber fabric;

(2) planarizing the polyamic acid film impregnated with the glass fiber fabric prepared by step (1) (first planarization step);

(3) producing a polyimide film impregnated with a glass fiber fabric by imidizing the polyamic acid film prepared by step (2); And

(4) flattening the polyimide film impregnated with the glass fiber fabric prepared by step (3) (second flattening step).

The planarization step of the two steps of the present invention will be described in detail as follows.

The colorless transparent polyamic acid film of the present invention may be molded by dissolving a dianhydride compound and a diamine compound in a solvent and evaporating the solvent in a polyamic acid solution made through a polymerization reaction. The polyamic acid film is heated to dry for about 30 minutes at a temperature of 80 ° C or less to prepare a polyamic acid film having self-support.

The colorless transparent polyamic acid film having a surface roughness of about 0.3 μm has a ring-closing reaction between the glass transition temperature (T _g ) of the film and the temperature at which the imidization reaction starts to occur. Since this does not occur and the main chain of the polymer may have some fluidity, applying pressure to the polyamic acid film may easily induce deformation of the colorless transparent polyamic acid film.

After placing a colorless transparent polyamic acid film having a large surface roughness between two rollers having a smooth and cylindrical surface, between the two rollers between the glass transition temperature of the film and the temperature at which the imidization reaction starts to occur. When the two rollers are rotated in opposite directions while a constant pressure is applied to the colorless and transparent polyamic acid film by narrowing the intervals of the polymer, the polymer of the high part of the film surface moves to the low part (see FIG. 2). The surface is planarized to a surface roughness similar to that of the two rollers under pressure (see FIG. 3C).

However, when the planar colorless transparent polyamic acid film is thermally or chemically imidized to form a colorless transparent polyimide film, the surface roughness is roughened back to a few tens of nm due to ring-closing and dehydration reactions ( 3d).

The polymer main chain of the colorless transparent polyimide film has a long-range segmental motion above the glass transition temperature (T _g ) of the film. Therefore, applying a pressure to the colorless transparent polyimide film above the glass transition temperature of the film can induce deformation of the colorless transparent polyimide film. After placing the colorless transparent polyimide film between two rollers having a smooth and cylindrical surface, two rollers at a temperature between the glass transition temperature and the decomposition temperature of the colorless transparent polyimide film When the two rollers are rotated in opposite directions while a constant pressure is applied to the colorless and transparent polyimide film by narrowing the gap therebetween, the polyimide polymer in the high portion of the film surface moves to the low portion (see FIG. 2). The surface of the colorless transparent polyimide film is flattened to a surface roughness similar to that of the two rollers under pressure (see FIG. 3F).

In the present invention, the dianhydride compound, 4,4'-Oxydiphthalic anhydride (OPDA), Pyromellitic dianhydride (PMDA), 3,3 ', 4,4'- Diphenylsulfone tetracarboxylic dianhydride (DSDA), 3,3' , 4,4'-Benzophenone tetracarboxylic dianhydride (BTDA), 4- (2,5-Dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic Anhydride (DTDA), 4,4 '-Bisphenol A dianhydride (BPADA), 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), bicycle [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA), 3 , 3 ', 4,4'-Biphenyl tetracarboxylic dianhydride (BPDA), 5- (2,5-Dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOMDA), Ethylene diamine tetraacetic dianhydride (EDTE ), 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) is preferably any one or two or more selected from the group consisting of,

The diamine compound is 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane (BAHFP), 1,3-Bis (3-aminophenoxy) benzene (m-BAPB), 4,4'-Bis (4- aminophenoxy) biphenyl (p-BAPB), 2,2-Bis (3-aminophenyl) hexafluoropropane (BAPF), bis [4- (3-aminophenoxy) phenyl] sulfone (m-BAPS), 2,2-Bis [4- (4-aminophenoxy) phenyl] sulfone (p-BAPS), Bis (3-aminophenyl) sulfone (APS), m-xylylenediamine (m-XDA), p-xylylenediamine (p-XDA), 3,4'-Oxydianiline ( 3,4-ODA), 2,2-Bis (3-amino-4-methylphenyl) hexafluoropropane (BAMF), 4,4'-Diaminooctafluorobiphenyl, 3,3'-Dihydroxybenzidine, 2,2'-Ethylenedianilin, 2,2 '-bis (trifluoromethyl) benzidine (TFB), 2,2', 5,5'-Tetrachlorobenzidine, Bis (3-aminophenyl) methanone, 2,7-Diaminofluorene, 2-Chloro-p-phenylenediamine, 1,3-Bis (3-aminopropyl) -tetramethyldisiloxane, 1,1-Bis (4-aminophenyl) cyclohexane, 9,9-Bis (4-aminophenyl) fluorene, 5- (Trifluoromethyl) -1,3-phenylenediamine, 4,4'-methylenebis (2-methylcyclohexylamine), 4-Fluoro-1,2-phenylenediamine, 4,4 '-(1,3-Phenylenediisopropylidene) bisaniline, 4-Nitro-1,3-phenylenediamine, 4-Chloro-1,3-phenylenediamine, 1,3,5-Triazine-2,4,6-triamine (Melamine), 3,5-Diaminobenzonitrile, 1,3 -bis (aminomethyl) cyclohexane (m-CHDA), 1,4-Bis (aminomethyl) cyclohexane (p-CHDA), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (6FBAPP), 2,2 '-Bis (trifluoromethyl) benzidine (MDB), 4,4'-Oxydianiline (4,4'-ODA), 2,2-Bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 1,3- Cyclohexanediamine, 1,4-Cyclohexanediamine, Bis (4-aminophenyl) sulfide (4,4'-SDA) is preferably any one or two or more selected from the group consisting of.

In addition, in this invention, the manufacturing method of the said polyamic-acid solution does not need to specifically limit, Any method may be sufficient as it is a conventional synthetic method.

In addition, in the present invention, dimethyl acetamide (DMAc) may be exemplified as a solvent for dissolving the dianhydride compound and the diamine compound, but is not limited thereto.

In addition, in the present invention, the glass fiber fabric impregnated polyamic acid solution is preferably heated to a temperature range of 40 ~ 150 ℃ to evaporate the solvent to form a polyamic acid film impregnated with a glass fiber fabric, the polya The thermosetting by the thermal method of the mixed acid film is preferably made of a polyimide film impregnated with a glass fiber fabric through an imidization reaction in a temperature range of 100 ~ 300 ℃.

In addition, in the present invention, the first or second planarization step, it is preferable to pass through the two rollers of the cylindrical (cylindrical) to planarize the polyamic acid film or polyimide film impregnated with the glass fiber fabric. At this time, the width of the polyamic acid film or polyimide film is preferably less than or equal to the length of the two rollers. This is because if the area of the polyamic acid film or polyimide film impregnated with the glass fiber fabric is wider than the length of the two rollers, the film larger than the roller is not subjected to pressure and the surface is not planarized.

In addition, it is preferable that the polyamic acid film or polyimide film impregnated with the glass fiber fabric is located at the central portion of the two rollers so that the pressure can be uniformly applied from the two rollers.

 In addition, the roller may be a stainless steel or cylindrical glass of cylindrical shape having a hard surface, a surface roughness of 0.5 to 2 nm, and a melting point of 500 ° C. or more.

In addition, the temperature of the roller is controlled between the glass transition (T _g ) of the polyamic acid film impregnated with the glass fiber fabric in the first flattening step and the temperature at which the imidization reaction starts to occur, and the glass fiber in the second flattening step. It is desirable to control between the glass transition (T _g ) and thermal decomposition temperature of the fabric-impregnated polyimide film.

It is also possible to use N pairs of rollers in place of two rollers (pair of rollers). As shown in Figure 4, by using the N pair of rollers, the flattening time of the surface of the polyamic acid film or polyimide film impregnated with the glass fiber fabric can be reduced to 1 / N than when using a pair of rollers, This is equivalent to the effect of flattening N pairs of rollers at the same time with the effect of flattening N pairs of rollers.

In addition, the present invention, after positioning the polyamic acid film or polyimide film impregnated with a glass fiber fabric between the rollers, the roller and the polyamic acid film or polyimide film impregnated with the glass fiber fabric located therebetween The temperature of the furnace in an environmental chamber is the temperature at which the glass transition temperature (T _g ) of the polyamic acid film impregnated with the glass fiber fabric and the imidization reaction start to occur, or the glass transition temperature (T) of the polyimide film. _g ) and it is possible to planarize by adjusting to pyrolysis temperature range.

Further, in the present invention, the rotational speed of the roller is the glass transition temperature (T _g ) of the polyamic acid film impregnated with the glass fiber fabric in the first planarization step, the temperature at which the imidization reaction occurs, the temperature of the roller, the roller And according to the temperature of the atmosphere furnace for heating the polyamic acid film impregnated with the glass fiber fabric and the magnitude of the pressure applied between the rollers, and in the second planarization step, the glass transition temperature of the polyimide film impregnated with the glass fiber fabric (T _g ) and pyrolysis temperature, the temperature of the roller, it is preferable to adjust according to the temperature of the atmosphere furnace for heating the polyimide film impregnated with the roller and glass fiber fabric and the magnitude of the pressure applied between the rollers.

In addition, in the present invention, the first or second planarization step may be planarized by placing a polyamic acid film or a polyimide film between two flat surfaces and applying pressure thereto (see FIGS. 5A to 5F). .

Specifically, the planarization of the polyamic acid film or polyimide film is sandwiched between two glass plates in a sandwich structure, and then placed between two plates equipped with a heater to maintain a constant pressure perpendicular to the two plate surfaces. Can be achieved by application.

 In this case, the width of the polyamic acid film or polyimide film impregnated with the glass fiber fabric is preferably equal to the width of the two glass plates or at least 70% or more and the maximum of 100% or less of the two glass plates. If the area of the polyamic acid film or polyimide film impregnated with the glass fiber fabric is too small, less than 70% of the width of the two glass plates, the glass plate is more likely to be damaged due to uneven pressure and, conversely, larger than the two glass plates. If the film is larger (more than 100%), the film larger than the glass plate is not subjected to pressure and the surface is not planarized.

In addition, it is preferable that the polyamic acid film or polyimide film impregnated with the two glass plates and the glass fiber fabric laminated therebetween is located at the center portion of the two plates so that pressure can be uniformly applied from the two plates. .

In addition, the two glass plates used for laminating the polyamic acid film or polyimide film impregnated with the glass fiber fabric have a hard surface, a flat surface, a surface roughness of 0.5 to 2 nm, and a melting point of 500 ° C. It is preferable to use the above plate glass. It is also possible to use a stainless steal plate having a hard, flat surface, a surface roughness of 0.5 to 2 nm and a melting point of 500 ° C. or more in place of the glass plate.

In addition, the temperature of the two plates is the glass transition temperature (T _g ) of the polyamic acid film impregnated with the glass fiber fabric and the temperature at which the imidization reaction starts to occur, or the glass transition temperature (T _g ) of the polyimide film Pyrolysis temperatures are preferred.

In addition, the application time of the pressure to be applied perpendicular to the two plate surfaces is adjusted according to the temperature of the two plates and the magnitude of the pressure applied, or heating the polyamic acid film or polyimide film impregnated with the two plates and glass fiber fabric It is preferable to adjust according to the temperature of the furnace and the size of the applied pressure, for example, the temperature of the two plates is 300 ℃, the application time is preferably within 2 hours when applying a pressure of 17 MPa to the two glass plates.

In addition, the present invention, after placing a polyamic acid film or polyimide film impregnated with a glass fiber fabric between two flat surfaces, the polyamic acid film or polyimide impregnated with the glass fiber fabric positioned between the flat plate and the The temperature of the furnace in an environmental furnace together with the film is the temperature at which the glass transition temperature (T _g ) of the polyamic acid film impregnated with the glass fiber and the imidization reaction start to occur, or the glass transition of the polyimide film. It is also possible to planarize by adjusting the temperature (T _g ) and pyrolysis temperature range.

Advantages of the method of manufacturing a polyimide film including the two-step planarization step of the present invention as described above include a low polyamic acid film having low hardness and glass transition temperature (T _g ) at a low temperature and pressure. By planarization within a short time, the time required for planarization of a polyimide film having a very high hardness and glass transition temperature is significantly reduced. This has two important meanings in terms of mass production of film for display cover windows and substrates.

First, since the surface roughness of the polyimide film before the second planarization step is reduced to about 1/7, compared to the case where the first planarization step of planarization of the polyamic acid film is not performed, the second planarization of the polyimide film By drastically reducing the time required for the step, a gain of at least five times in production efficiency and production costs can be achieved.

Second, by significantly reducing the time required for the second planarization step, the browning phenomenon of the color of the polyimide film gradually turning brown near 300 ° C., which is the optimum temperature for the planarization of the polyimide film, is greatly reduced, without passing through the first planarization step. The yellowness index of the polyimide film is greatly reduced from 5.36 when only the second planarization step is performed, and to 2.65 when the first and second planarization steps are performed. Considering that high light transmittance (90% or more) is an essential condition for the display cover window and the film for the substrate, the two-step planarization method disclosed in the present invention has a very important meaning.

On the other hand, the method of manufacturing and planarizing the colorless transparent polyimide film impregnated with the glass fiber fabric of the present invention, the step of flattening the polyamic acid film, that is, the first planarization step of the polyimide film impregnated with the glass fiber fabric It can be achieved simply by leveling the surface.

However, in this case, since the rotational speed of the roller used for the flattening must be further reduced, the flattening takes more time, and the surface roughness is larger, so that the flattening is required at a higher temperature.

The present invention also provides a polyimide film impregnated with a glass fiber fabric produced by the above method.

In the present invention, the polyimide film impregnated with the glass fiber fabric preferably has a thickness of 10 to 1000 µm, and the glass fiber fabric preferably has a thickness of 5 to 500 µm.

Hereinafter, a two-stage planarization method according to the present invention will be described in more detail with reference to the drawings.

Figures 3a to 3f is a method for flattening the surface of a colorless transparent polyamic acid film impregnated with a glass fiber fabric and a colorless transparent polyimide (CPI) film substrate impregnated with a glass fiber fabric using a pair of rollers according to the present invention The configuration diagram for explaining the.

3A shows a colorless transparent polyamic acid film 301 impregnated with a glass fiber fabric and a glass fiber fabric 302 having a thickness of 25 μm impregnated in the polyamic acid film. The surface roughness of the colorless transparent polyamic acid film 301 impregnated with the glass fiber fabric is 273 nm (RMS).

In addition, as shown in Figure 3b, the glass fiber fabric impregnated colorless transparent polyamic acid film 301 is placed between a pair of rollers (305, 306) equipped with embedded heaters (303, 304) of the roller After the temperature was heated to 80 ° C., a pressure of 3 MPa was applied perpendicularly to the contact surface of the pair of rollers 305 and 306 and the colorless transparent polyamic acid film 301 impregnated with the glass fiber fabric as shown in FIG. 3C. 273 nm (RMS) by applying a pair of rollers and rotating the pair of rollers in opposite directions about the rotating shafts 307 and 308 to pass the colorless and transparent polyamic acid film 301 impregnated with the glass fiber fabric between the two rollers. The surface of the colorless transparent polyamic acid film 301 impregnated with the glass fiber fabric having a surface roughness of was planarized to a surface roughness 309 of about 2.51 nm (RMS) (see FIG. 8A).

At this time, the surface roughness of the two rollers 305 and 306 to be used is 2 nm (RMS) or less.

The colorless transparent polyamic acid film 309 impregnated with the glass fiber fabric flattened to the surface roughness of about 2.51 nm (RMS) was thermally imidized at a temperature ranging from 110 ° C. to 250 ° C. to impregnate the glass fiber fabric. When molded into a colorless transparent polyimide film 310, the film surface is roughened again with a surface roughness of 56 nm (RMS) as in FIG. 3D.

As shown in FIG. 3E, the colorless transparent polyimide film 310 impregnated with the glass fiber fabric formed by the imidization reaction is disposed between the pair of rollers 315 and 316 equipped with the embedded heaters 313 and 314. Position, and after heating the temperature of the two rollers to 300 ℃, as shown in Figure 3f perpendicular to the contact surface of the colorless transparent polyimide film 310 impregnated with the two rollers (315, 316) and the glass fiber fabric A pressure of 17 MPa was applied, and the two rollers were rotated in opposite directions at a rate of 0.05 revolutions / sec about the rotating shafts 317 and 318 to pass a colorless transparent polyimide film impregnated with fiberglass fabric between the two rollers. In other words, it is possible to planarize the polyimide film 310 impregnated with the glass fiber fabric having the surface roughness of 56 nm (RMS) to the surface roughness 319 of about 2.19 nm (RMS) (see FIG. 8B).

At this time, the surface roughness of the two rollers 315 and 316 to be used was 2 nm (RMS) or less.

When the two rollers have a temperature of 300 ° C., the maximum rotational speed of the pair of rollers required for the planarization of the surface of the colorless and transparent polyimide film impregnated with the glass fiber fabric is 17 MPa. Is within 0.05 revolutions / sec, but within 0.025 revolutions / sec when the applied pressure is 15 MPa. In addition, when the applied pressure is 20 MPa, the rotation speed of the roller is within 0.1 revolutions / sec. This is because the higher the pressure applied to the colorless transparent polyimide film for flexible display impregnated with glass fiber fabric, the faster the deformation of the colorless transparent polyimide film occurs, and the smaller the pressure applied to the colorless transparent polyimide film occurs slowly. .

For example, when the pressure applied between a pair of rollers is 17 MPa, if the time required for the flattening process is 1 hour, two hours are required when the pressure is 15 MPa, and 30 minutes when the pressure is 20 MPa. Decreases.

4 is a planarization time of the colorless transparent polyamic acid film impregnated with the glass fiber fabric and the colorless transparent polyimide film impregnated with the glass fiber fabric using N pairs of rollers instead of the two rollers (pair of rollers). It outlines how to reduce it.

As shown in FIG. 4, when N pairs of rollers are used instead of a pair of rollers, the flattening time of the colorless transparent polyamic acid film impregnated with the glass fiber fabric and the colorless transparent polyimide film impregnated with the glass fiber fabric It can be reduced to 1 / N than when using a pair of rollers. This is because the effect of flattening the N-pair rollers at the same time is equivalent to the effect of the flattening of the pair of rollers N times.

In addition, in the process of flattening the surface of the colorless transparent polyamic acid film and the polyimide film impregnated with the glass fiber fabric using the N pairs of rollers, the roller temperature of each pair is changed from the glass transition temperature of the colorless transparent polyamic acid film to the colorless transparent polyimide. Gradually increasing before the thermal decomposition temperature of the film roll-to-roll the surface planarization process and imidization reaction of the colorless transparent polyamic acid film impregnated with the glass fiber fabric, and the surface planarization process of the colorless transparent polyimide film impregnated with the glass fiber fabric This can be achieved by a roll to roll process.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example 1. Planarization of Polyimide Film Using Flat Plate

2.31 g (5.2 × 10 ^-3 mol) of 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) as dianhydride monomer and 1.29 g (5.2 × 10 ^-3 ) Bis (3-aminophenyl) sulfone (APS) as diamine monomer mol) was added to 26.99 g of dimethyl acetamide (DMAc) as a solvent, and slowly stirred in a magnetic stirrer for 1 hour in a nitrogen atmosphere at 0 ° C. to completely dissolve the monomers, and the solution was very vigorously at room temperature (25 ° C.) for more than 15 hours. By stirring, a polyamic acid solution (PA-1) was prepared through polymerization.

In addition, the dianhydride monomer hydride ^{6FDA 5.47 g (1.231 × 10 -2} mol) and 2,2-Bis (3-amino- 4-methylphenyl) hexafluoropropane (BAMF) 4.46 g (1.231 × 10 -2 mol) and the solvent is DMAc 74.44 g of the polyamic acid solution PA-1 and PA-2 were prepared in the same manner as described above, and the polyamic acid solution PA-1 and PA-2 were each added in a weight ratio of 4: 6 (5.96 g, 8.94 g) was prepared to prepare a polyamic acid mixed solution.

A glass fiber fabric having a thickness of 25 μm was placed on a glass substrate having an area of 10 cm × 10 cm, and the polyamic acid mixture solution prepared above was evenly poured onto the glass fiber fabric and placed in a vacuum oven to obtain a temperature inside the vacuum oven at 50 ° C. at room temperature. After raising at 5 ℃ / min speed to maintain 5 minutes at 50 ℃, up to 2.5 ℃ / min speed from 50 ℃ to 110 ℃ and maintained at 110 ℃ for 3 hours and the degree of vacuum inside the vacuum oven to -0.1 MPa or less The solvent was evaporated rapidly to form a polyamic acid film.

The polyamic acid film impregnated with the glass fiber fabric was raised from 110 ° C to 170 ° C at a rate of 0.4 ° C / min at a vacuum degree of -0.1 MPa or less, and then from 170 ° C to 250 ° C at a rate of 1 ° C / min. By raising and maintaining for 30 minutes at 250 ℃ to prepare a colorless and transparent polyimide film (CPI) impregnated with a glass fiber fabric through the imidation reaction of the polyamic acid film by step thermosetting.

On the colorless transparent polyimide film (CIP) impregnated with the glass fiber fabric, a glass plate of the same size and same type as the glass substrate was placed. At this time, the surface roughness of the two glass plates used was 1.2 nm (RMS) or less. Place them in the center between the lower plate with the heater and the upper plate with the other heater, heat the temperature of the two plates to 300 ° C using the heaters embedded in the two plates, and then Vertically, a pressure of 17 MPa was applied to the polyimide film for 1 hour to planarize the surface of the colorless transparent polyimide film.

The pressure applied to the two plates was removed, and the two glass plates and the flattened colorless transparent polyimide film laminated therebetween were separated from the two plates together. A colorless transparent polyimide film impregnated with a glass fiber fabric was separated from the lower glass substrate and the upper glass substrate to obtain a flattened transparent polyimide film.

The surface roughness of the polyimide film impregnated with glass fiber fabric was measured by alpha step (XE-100, Park Systems, Korea) when the surface roughness of the film was 0.2 μm or more, and AFM (atomic force) when the roughness was less than 0.2 μm. microscope; Dektak-8, VEECO, USA).

As a result, the surface roughness of the colorless transparent polyimide film impregnated with the glass fiber fabric before flattening was 0.4 μm (RMS), whereas the surface roughness of the flattened colorless transparent polyimide film was reduced to 1.184 nm (RMS) (FIG. 6). Reference).

In addition, the coefficient of thermal expansion (CTE) of the flattened colorless transparent polyimide film obtained as described above was measured by a thermo-mechanical analyzer (TMA-2940, TA Instruments, USA). The thermal expansion coefficient of the colorless transparent polyimide film impregnated with glass fiber was 11 ppm at a temperature range from room temperature to 400 ° C. This can be seen that the glass fiber fabric is very effective in suppressing the thermal expansion of the colorless transparent polyimide film considering that the thermal expansion coefficient of the colorless transparent polyimide film not impregnated with the glass fiber fabric.

Example 2. Planarization of Polyimide Film Using Rollers

After preparing a polyamic acid mixed solution in the same manner as in Example 1, the glass fiber fabric was placed on a support, and the polyamic acid mixed solution was evenly poured on the glass fiber fabric.

The glass fiber fabric impregnated with the polyamic acid mixed solution and the whole support were put in a temperature atmosphere, and the internal temperature was raised at a rate of 5 ° C./min from room temperature to 50 ° C. and maintained at 50 ° C. for 5 minutes, and the temperature was increased from 50 ° C. to 110 ° C. 2.5. The polyamic acid film was formed by evaporating the solvent while raising the mixture at a rate of ° C / min and maintaining the same at 110 ° C for 3 hours.

After raising the temperature of the colorless transparent polyamic acid film impregnated with the glass fiber fabric at a rate of 0.4 ° C./min from 110 ° C. to 170 ° C., and then again at 170 ° C. to 250 ° C. at a rate of 1 ° C./min, 250 The polyamic acid film was subjected to an imidization reaction by step thermosetting by maintaining at 30 ° C. to prepare a colorless transparent polyimide film impregnated with a glass fiber fabric.

A colorless transparent polyimide film impregnated with the glass fiber fabric was placed between a pair of rollers having a surface roughness of 2 nm (RMS) and a diameter of 20 cm, and a pair using a buried heater mounted on the pair of rollers. After heating the temperature of the roller to 300 ° C, a pressure of 17 MPa was applied perpendicularly to the contact surface of the pair of rollers and the colorless and transparent polyimide film impregnated with the glass fiber fabric, and the pair of rollers were rotated on a rotating shaft. By rotating at a rate of 0.01 revolutions / sec in the opposite direction to each other, the colorless and transparent polyimide film impregnated with glass fiber was passed between a pair of rollers.

The surface roughness of the polyimide film impregnated with glass fiber fabric is measured by alpha step (XE-100, Park Systems, Korea) when the surface roughness of the film is 0.2 μm or more, and AFM (atomic force) when the roughness is less than 0.2 μm. microscope; Dektak-8, VEECO, USA).

As a result, the surface roughness of the colorless transparent polyimide film impregnated with the glass fiber fabric before flattening was 0.4 μm (RMS), whereas the surface roughness of the flattened colorless transparent polyimide film was reduced to 2.031 nm (RMS) (FIG. 7). Reference).

In addition, the coefficient of thermal expansion (CTE) of the flattened colorless transparent polyimide film obtained as described above was measured by a thermo-mechanical analyzer (TMA-2940, TA Instruments, USA). The thermal expansion coefficient of the colorless transparent polyimide film impregnated with glass fiber was 11 ppm at a temperature range from room temperature to 400 ° C. This can be seen that the glass fiber fabric is very effective in suppressing the thermal expansion of the colorless transparent polyimide film considering that the thermal expansion coefficient of the colorless transparent polyimide film not impregnated with the glass fiber fabric.

Example 3. Planarization of Polyimide Film Using Two-Step Planarization Process

A polyamic acid film was molded in the same manner as in Example 2.

After the polyamic acid film was separated from the support, the surface roughness with embedded heater was placed between a pair of rollers having a diameter of 2 nm (RMS) and a diameter of 20 cm, and the temperature of the roller was heated to 80 ° C., Adjusting the distance of the roller to apply a pressure of 3 MPa perpendicular to the contact surface of the colorless transparent polyamic acid film impregnated with the roller and the glass fiber fabric, the pair of rollers of 0.1 revolutions / sec about the axis of rotation The surface of the polyamic acid film impregnated with the glass fiber fabric was flattened by passing the colorless and transparent polyamic acid film impregnated with the fiberglass fabric through a pair of rollers by rotating in opposite directions at a speed.

After raising the temperature of the colorless transparent polyamic acid film impregnated with the flattened glass fiber fabric at a rate of 0.4 ° C./min from 110 ° C. to 170 ° C., and then increasing the temperature at a rate of 1 ° C./min from 170 ° C. to 250 ° C. The polyamic acid film was subjected to an imidization reaction by step thermosetting by maintaining at 250 ° C. for 30 minutes to form a colorless transparent polyimide film impregnated with a glass fiber fabric. At this time, the surface of the polyimide film was again roughened with a surface roughness of 56 nm (RMS).

The colorless transparent polyimide film impregnated with the fiberglass fabric was placed between a pair of rollers having a surface roughness of 2 nm (RMS) and a diameter of 20 cm with a embedded heater, and a pair of rollers using the embedded heater. After raising the temperature to 300 ° C, by adjusting the distance between the pair of rollers and applying a pressure of 17 MPa perpendicular to the contact surface of the colorless transparent polyimide film impregnated with the roller and the glass fiber fabric, The pair of rollers were rotated in opposite directions at a speed of 0.05 revolutions / sec about the rotation axis to pass the colorless and transparent polyimide film impregnated with the glass fiber fabric between the pair of rollers to be flattened (second flattening step).

The surface roughness of the polyimide film impregnated with glass fiber fabric is measured by alpha step (XE-100, Park Systems, Korea) when the surface roughness of the film is 0.2 μm or more, and AFM (atomic force) when the roughness is less than 0.2 μm. microscope; Dektak-8, VEECO, USA).

As a result, in the first planarization step, the surface of the polyamic acid film impregnated with the glass fiber fabric having the surface roughness of 273 nm (RMS) was flattened to the surface roughness of about 2.51 nm (RMS) (see FIG. 8A). However, the surface of the colorless and transparent polyimide film impregnated with the glass fiber fabric subjected to the imidization reaction was again roughened with a surface roughness of 56 nm (RMS), and the 56 through the second planarization step of flattening the polyimide film. A polyimide film impregnated with a glass fiber fabric having a surface roughness of nm (RMS) was flattened to a surface roughness of 2.19 nm (RMS) (see FIG. 8B).

In addition, the coefficient of thermal expansion (CTE) of the flattened colorless transparent polyimide film obtained as described above was measured by a thermo-mechanical analyzer (TMA-2940, TA Instruments, USA).

The coefficient of thermal expansion of the colorless transparent polyimide film without impregnation of glass fiber was about 61 ppm / ℃ in the temperature range from room temperature to glass transition temperature (264), but rapidly increased to 2837 ppm / ℃ above the glass transition temperature. It was. On the other hand, the thermal expansion coefficient of the colorless and transparent polyimide film impregnated with glass fiber fabric at a temperature range from room temperature to 400 ° C. was very small at 11 ppm / ° C. without increasing the coefficient of thermal expansion due to glass transition. This confirmed that the glass fiber fabric is very effective in suppressing thermal expansion of the colorless transparent polyimide film.

As described above, specific portions of the contents of the present invention have been described in detail, and for those skilled in the art, these specific techniques are merely preferred embodiments, and the scope of the present invention is not limited thereto. Will be obvious. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

As described above, the method of manufacturing a colorless transparent polyimide film impregnated with a glass fiber fabric according to the present invention, the surface roughness of the colorless transparent polyimide film impregnated with a glass fiber fabric is several 10 nm ~ 1 ㎛ level By flattening to a few nm level, which enables the TFT process on the flexible display substrate, prevents surface scattering and increases the light transmittance and transparency of the colorless transparent polyimide film to cover windows of flat panel displays and mobile phones Can be used as

In addition, the glass fiber fabric impregnated with the colorless transparent polyimide film can increase the tensile strength of the colorless transparent polyimide film, which can greatly increase the flexibility and life of the substrate and cover window for flexible display, By replacing the glass cover window with a colorless transparent polyimide cover window impregnated with fiberglass fabric, it is advantageous to significantly reduce the weight of the display and eliminate the risk of breakage.

Therefore, the colorless transparent polyimide film impregnated with the flattened glass fiber fabric according to the present invention can be very usefully used in the flexible display industry and the flat panel display industry.

Claims (14)

1. (1) impregnating a glass fiber fabric with a polyamic acid solution to produce a polyamic acid film impregnated with a glass fiber fabric;

   (2) planarizing the polyamic acid film impregnated with the glass fiber fabric prepared by step (1) (first planarization step);

   (3) producing a polyimide film impregnated with a glass fiber fabric by imidizing the polyamic acid film prepared by step (2); And

   (4) planarizing the polyimide film impregnated with the glass fiber fabric prepared by step (3) (second planarization step); a method of manufacturing a polyimide film impregnated with a glass fiber fabric comprising a.
2. The method of claim 1,

   The polyamic acid solution in the step (1) is a polyimide film impregnated with a glass fiber fabric, characterized in that the dianhydride compound and diamine (diamine) compound dissolved in a solvent to produce a polymerization reaction.
3. The method of claim 2,

   The dianhydride compound is 4,4'-Oxydiphthalic anhydride (OPDA), Pyromellitic dianhydride (PMDA), 3,3 ', 4,4'- Diphenylsulfone tetracarboxylic dianhydride (DSDA), 3,3', 4,4'- Benzophenone tetracarboxylic dianhydride (BTDA), 4- (2,5-Dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic Anhydride (DTDA), 4,4'-Bisphenol A dianhydride ( BPADA), 4,4 '-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), bicycle [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA), 3,3', 4, 4'-Biphenyl tetracarboxylic dianhydride (BPDA), 5- (2,5-Dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOMDA), Ethylene diamine tetraacetic dianhydride (EDTE), 1,2, 4,5-cyclohexanetetracarboxylic dianhydride (CHDA) A method for producing a polyimide film impregnated with a glass fiber fabric, characterized in that any one or two or more selected from the group consisting of.
4. The method of claim 2,

   The diamine compound is 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane (BAHFP), 1,3-Bis (3-aminophenoxy) benzene (m-BAPB), 4,4'-Bis (4-aminophenoxy biphenyl (p-BAPB), 2,2-Bis (3-aminophenyl) hexafluoropropane (BAPF), bis [4- (3-aminophenoxy) phenyl] sulfone (m-BAPS), 2,2-Bis [4- ( 4-aminophenoxy) phenyl] sulfone (p-BAPS), Bis (3-aminophenyl) sulfone (APS), m-xylylenediamine (m-XDA), p-xylylenediamine (p-XDA), 3,4'-Oxydianiline (3 , 4-ODA), 2,2-Bis (3-amino-4-methylphenyl) hexafluoropropane (BAMF), 4,4'-Diaminooctafluorobiphenyl, 3,3'-Dihydroxybenzidine, 2,2'-Ethylenedianilin, 2,2 ' -bis (trifluoromethyl) benzidine (TFB), 2,2 ', 5,5'-Tetrachlorobenzidine, Bis (3-aminophenyl) methanone, 2,7-Diaminofluorene, 2-Chloro-p-phenylenediamine, 1,3-Bis ( 3-aminopropyl) -tetramethyldisiloxane, 1,1-Bis (4-aminophenyl) cyclohexane, 9,9-Bis (4-aminophenyl) fluorene, 5- (Trifluoromethyl) -1,3-phenylenediamine, 4,4'-methylenebis ( 2-methylcyclohexylamine), 4-Fluoro-1,2-phenylenediamine, 4,4 '-(1,3-Phenylenediisopropylidene) bisaniline, 4 -Nitro-1,3-phenylenediamine, 4-Chloro-1,3-phenylenediamine, 1,3,5-Triazine-2,4,6-triamine (Melamine), 3,5-Diaminobenzonitrile, 1,3-bis ( aminomethyl) cyclohexane (m-CHDA), 1,4-Bis (aminomethyl) cyclohexane (p-CHDA), 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane (6FBAPP), 2,2'-Bis (trifluoromethyl) benzidine (MDB), 4,4'-Oxydianiline (4,4'-ODA), 2,2-Bis [4- (4-aminophenoxy) phenyl] propane (BAPP), 1,3-Cyclohexanediamine, 1 , 4-Cyclohexanediamine, Bis (4-aminophenyl) sulfide (4,4'-SDA) A method for producing a polyimide film impregnated with a glass fiber fabric, characterized in that any one or two or more selected from the group consisting of.
5. The method of claim 1,

   Method of producing a polyimide film impregnated with a glass fiber fabric, characterized in that to pass between two cylindrical rollers in the step (2) or (4) to planarize the polyamic acid film or polyimide film.
6. The method of claim 5,

   The temperature of the cylindrical roller is heated to the glass transition temperature (T _g ) of the polyamic acid film impregnated with the glass fiber fabric and the imidization temperature at which the imidization reaction starts to occur, or the glass fiber fabric is impregnated. Method of producing a polyimide film impregnated with a glass fiber fabric, characterized in that heating between the glass transition temperature (T _g ) and thermal decomposition temperature (thermal decomposition temperature) of the polyimide film.
7. The method of claim 5,

   Surface roughness of the cylindrical roller is a method of producing a polyimide film impregnated with a glass fiber fabric, characterized in that 0.5 to 2 nm.
8. The method of claim 1,

   The method of manufacturing a polyimide film impregnated with a glass fiber fabric, characterized in that the step of (2) or (4) to planarize by placing a polyamic acid film or polyimide film between the two flat surfaces and applying pressure.
9. The method of claim 8,

   The temperature of the plate is heated to the glass transition temperature (T _g ) of the polyamic acid film impregnated with the glass fiber fabric and the imidization temperature at which the imidization reaction starts to occur, or the glass fiber fabric is impregnated. A method for producing a polyimide film impregnated with a glass fiber fabric, characterized in that heating is carried out between the glass transition temperature (T _g ) and the pyrolysis temperature of the polyimide film.
10. The method of claim 8,

    The surface roughness of the flat plate is a polyimide film impregnated glass fiber fabric, characterized in that 0.5 to 2 nm.
11. The method of claim 1,

    Method for producing a polyimide film impregnated with a glass fiber fabric, characterized in that the polyimide film impregnated by the thermal method in the step (3) to produce a polyimide film impregnated with a glass fiber fabric.
12. The method of claim 11,

    Method for producing a polyimide film impregnated with a glass fiber fabric, characterized in that the polyamic acid film is thermally imidized at a temperature range of 100 ~ 300 ℃.
13. The method of claim 1,

    Method of producing a polyimide film impregnated with a glass fiber fabric, characterized in that the polyimide film impregnated by the chemical method in the step (3) to produce a polyimide film impregnated with a glass fiber fabric.
14. A polyimide film produced by the method of any one of claims 1 to 13.

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