KR20140110730A - Polyimide film and method for producing the same - Google Patents

Abstract

Provided are a thin polyimide film whose thickness is less than or equal to 8 μm, wherein tearing or overlapping of film hardly occurs while making the films, and to a method for manufacturing the same. The polyimide film has a resistance value of a tear electric wave greater than or equal to 1.7N/mm, a minimum value of ultrasonic wave transmitting velocity greater than or equal 2.0km/sec and a thickness less than or equal to 8 μm.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a polyimide film,

The present invention relates to an ultra-thin polyimide film.

An aromatic diamine and an aromatic tetracarboxylic acid dianhydride are subjected to a polymerization reaction in an organic solvent to obtain a polyamic acid polymer solution, the polyamic acid polymer solution is formed into a film shape, and this is thermally and / or chemically dehydrated, Since the polyimide film obtained by heat treatment is excellent in heat resistance, insulation, and mechanical properties (durability against external force), it can be used as an electrical insulating material for electric wires, a base film of a heat insulating material, a flexible printed substrate, Films, tapes for fixing lead frames of integrated circuits, and coverlay applications for the purpose of protecting and insulating conductive circuits.

Of these applications, a flexible printed circuit board has a basic structure in which a circuit pattern is formed on a flexible and thin base film and a cover layer is formed on the surface of the circuit pattern. With its excellent function such as flexibility, . However, according to recent advances in mounting technology, it has been required to increase the wiring density, and accordingly, high flexibility has been demanded. However, if the conventional flexible printed circuit board is multilayered or has a small bending radius, there is a problem that disconnection occurs after long-term use, so that sufficient flex resistance is not obtained.

One of effective means of miniaturization of the flexible printed circuit board and improvement of the bending property is the thinning of the polyimide. However, there is a problem that the film is weakened by thinning, and the film is easily broken or deformed. Also, the thinner the film thickness, the lower the rigidity of the film. If the film has a poor planarity, wrinkles tend to occur during transportation, resulting in problems such as poor coating performance and a lower product ratio. Therefore, it has been desired to develop a thin polyimide film having sufficient thermo-resistance even in the form of a thin film, good planarity, and excellent handling property in transportation.

However, in the polyimide film, an aromatic diamine represented by 4,4'-diaminodiphenyl ether and an aromatic tetracarboxylic acid dianhydride represented by pyromellitic dianhydride are polymerized in an organic solvent to obtain a polyamic acid polymer solution Followed by forming the polyamic acid polymerized solution in a film form and thermally and / or chemically dehydrating, cyclizing, or imidizing the polymerized solution. Specifically, a polyamic acid polymer solution or a solution prepared by adding a dehydrating agent having a stoichiometric amount or more and a catalytic amount of a tertiary amine to a polyamic acid polymer solution or a solution thereof is cast or coated on a drum or endless belt to form a film, Or less at a temperature of about 5 to 10 minutes to obtain a coating film of a polyamic acid polymer having self-supporting properties. Then, the film was peeled off from the support and the film was fixed with a plurality of pins or clips, and the film was introduced into a tenter oven. The film was slowly heated to about 100 to 300 DEG C while being stretched to obtain a green film, The film is heated at 550 DEG C for 1 to 5 minutes to obtain a polyimide film which is converted from polyamic acid to polyimide and from which solvent solvated in the polyamic acid has been removed.

However, when an extremely thin polyimide film having a thickness of 8.0 占 퐉 or less is produced by such a conventional method, since the film is thin, it tends to meander by tearing from the hole in the film- There is a problem that productivity is remarkably low due to easy occurrence of troubles. In addition, in a high adhesion treatment for improving adhesion between a film and a copper foil, a low heat shrinkage treatment for suppressing heat shrinkage of the film to enhance dimensional stability, a post-treatment process for bonding to a copper foil with a roll- Wrinkles are liable to occur due to their thinness, which makes it difficult to handle, resulting in a problem of lowering the yield.

As an industrial production method of an ultra-thin polyimide film having a thickness of 8.0 탆 or less, for example, in Patent Document 1 or 2, a method is disclosed in which a support film is once coated with a coater and then peeled and then the green film is introduced into a tenter . In this method, a separately prepared polyimide film with a green film is stuck with a pin to keep the strength of the film end in order to prevent the green film end from breaking from the pin hole. However, this method requires a separate polyimide film for end-holding, which is costly, resulting in poor production efficiency and a large amount of debris generated when punched. Further, since the film is not stretched at the time of preparing the green film, the molecular orientation in the film width direction can not be controlled uniformly, and tear propagation resistance is lowered and the planarity is likely to deteriorate. Particularly, in the case of a polyimide film having a very low porosity, if it has poor planarity, it causes various troubles during film formation or post-processing. For these reasons, there has been a demand for an efficient ultra-thin polyimide film which is excellent in planarity and has little trouble such as tearing, and a method for producing the same.

Japanese Patent Application Laid-Open No. 2008-285516 Japanese Patent Application Laid-Open No. 2009-13245

The present invention has been achieved as a result of examining the solution of the problems in the above-mentioned prior art. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a thin polyimide film having a film thickness of 8.0 탆 or less which is less liable to cause problems such as film tearing and wrinkling during transportation, and a manufacturing method thereof.

The polyimide film of the present invention has a film thickness of 8.0 mu m or less, a tear propagation resistance of 1.7 N / mm or more, and a minimum value of ultrasonic wave propagation speed of 2.0 km / sec. It is also preferable that the value of the elongation at break, which indicates good and poor flatness of the film, is 8 mm or less.

The method for producing a polyimide film of the present invention is a method for producing a polyimide film by continuously extruding or coating a polyamic acid solution on a support in the form of a film, (The stretching ratio in the longitudinal direction x the stretching ratio in the transverse direction) between the steps of stretching the film on the support at a temperature of not less than 70 ° C and not more than 200 ° C after extrusion is not less than 1.60. The relative viscosity ratio of the polyamic acid solution and the 4.0% potassium bromide solution used in the membrane formation is preferably 1.40 or more and 1.80 or less.

(Effects of the Invention)

According to the present invention, it is possible to obtain an ultra-thin polyimide film having a film thickness of 8.0 mu m or less, excellent in thermal resistance and planarity, and having little trouble due to film tearing or conveyance wrinkles in the film forming step and the subsequent processing step. Particularly, by studying the polymer composition, the polymer viscosity, the stretching method, and the like in the production of an ultra-thin polyimide film having a thickness of 8.0 탆 or less, it is possible to provide a polyimide film having excellent resistance to heat and flatness, It is possible to industrially and efficiently produce an ultra-thin polyimide film with less handling.

It is possible to prevent film breakage during film formation by using a thin polyimide film having a film thickness of 8.0 占 퐉 or less with a tear propagation resistance and an ultrasonic transmission speed and a specific elongation of not less than a predetermined value, It is possible to prevent troubles due to defects and the like, thereby contributing to trouble avoidance and speeding up of the post-treatment process. It is also possible to suppress occurrence of conveying wrinkles and / or meandering at the time of heat lamination processing in other steps.

1 is a schematic view of a test piece in which a tear propagation resistance value of a film is measured.
Fig. 2 is a schematic diagram for explaining the film twist value. Fig.
3 is a schematic diagram for explaining a method of measuring the ultrasonic wave transmission rate.

Hereinafter, the polyimide film of the present invention and its production method will be described in detail.

In the polyimide film of the present invention, the minimum value of the ultrasonic wave transmission rate is required to be 2.0 km / sec. When the tearing phenomenon of the film is viewed in macro units, it corresponds to cutting the molecular chains. The tearing of a large number of molecular chains in a transverse direction hardly causes a large resistance. From this viewpoint, tearing in the direction in which the direction in which the orientation is not proceeding is likely to occur because the number of molecular chains to be transversed is small. The ultrasonic wave propagation speed is progressing in the polyimide orientation in that direction, and the molecular structure is steep and the higher the Young's modulus, the faster. That is, the smaller the ultrasonic wave propagation velocity is, the more easily the film tears due to the tearing. In the polyimide film of the present invention, the ultrasonic wave transmission rate is preferably 2.1 to 3.0 km / sec, more preferably 2.2 to 2.9 km / sec.

The ultrasonic wave transmission rate of the polyimide film in the present invention was measured using a SONIC SHEET TESTER (Model SST-2500, manufactured by Nomura Shoji Co., Ltd.) at a constant distance (12 cm in this case) And the time required for the ultrasonic pulse to be transmitted by the head is measured. The measurement unit angle was measured at a total of 16 points from 11.25 ° to 180 °, and the minimum value of all the measured values was set as the ultrasound transmission rate of the film. The measured value is an index of the molecular orientation in the direction, and the orientation is progressing as it is larger. Also, the higher the degree of polymerization and the longer the molecular chain, the easier it is for the components constituting the polyimide to take a planar structure, and the rigid structure tends to accelerate the ultrasonic transmission rate. The ultrasonic transmission rate is an index that can determine the degree of orientation, degree of polymerization, and rigidity of the molecular structure.

The tear propagation resistance of the polyimide film in the present invention is measured by a light load tester manufactured by Toyo Seiki Seisakusho Co., Ltd. according to the Elmendorf thermal method described in JIS K 7128-2 (established on November 20, 1998) Value. The measured value indicates the resistance when the film is torn, which means that it is difficult to tear the film in the entire thickness direction, and it can be said that the larger the measured value is, the more difficult the film tears. In the tear propagation resistance of the present invention, the longitudinal direction and the width direction of the film are measured, and the lower value thereof is taken as the tear propagation resistance of the film. The term " longitudinal direction " as used herein refers to the direction in which the film flows in the film production process. The width direction of the film is a direction orthogonal to the longitudinal direction of the film.

In the polyimide film of the present invention, the tear propagation resistance is required to be 1.7 N / mm or more, more preferably 1.8 N / mm or more, and further preferably 1.9 N / mm or more. If the tear propagation resistance is small, the resistance against tearing is small, and the film tears and the film tear easily occurs.

In the polyimide film of the present invention, the thickness of the film is 8.0 탆 or less, preferably 3.0 탆 or more, and more preferably 4.0 to 7.5 탆. As the film thickness becomes thinner, the stiffness of the film is low and the film tends to wrinkle easily, which tends to cause film tearing due to meandering or running defect. However, the tear propagation resistance is 1.7N / mm or more, the minimum value of the ultrasonic wave transmission speed is 2.0km / Sec, the film can be formed even if the thickness of the film is 8.0 mu m or less.

The polyimide film of the present invention satisfying the above characteristics is preferably produced by a method in which a polyamic acid solution is continuously extruded or stretched in a film form on a support, the gel film is peeled from the support, . The polyimide film of the present invention preferably has a total stretching ratio of the film (stretching magnification in the longitudinal direction x stretching magnification in the transverse direction) between the steps of stretching the film at a temperature of not less than 70 ° C and not more than 200 ° C after extruding the polyamic acid onto the support ) Is 1.60 or more. The total draw ratio of the film is more preferably 1.70 or more, and still more preferably 1.80 or more. The upper limit of the total draw ratio of the film is usually about 3.00 times. The gel film having self-supporting property peeled from the support is preferably stretched in the longitudinal direction by regulating the traveling speed with a stretching roll. The draw ratio in the longitudinal direction is preferably 1.05 times or more and 2.00 times or less, more preferably 1.10 times or more and 1.60 times or less, and more preferably 1.10 times or more and 1.50 times or less. The longitudinal stretching may be performed in two or more stages. The gel film stretched in the longitudinal direction is preferably introduced into the tenter in a state of holding both end portions in the width direction as a clip, and is stretched in the width direction while traveling together with the tenter clip. The draw ratio in the width direction is preferably 1.05 times or more and 2.00 times or less, more preferably 1.10 times or more and 1.80 times or less, and further preferably 1.10 times or more and 1.70 times or less. (The stretching ratio in the longitudinal direction x the stretching ratio in the transverse direction) of the film between the steps of stretching the film at 70 DEG C or more and 200 DEG C or less is 1.60 or more so that the orientation in the film width direction can be uniformly adjusted It is possible to obtain a polyimide film having good flatness.

In order to control the in-plane orientation of the polyimide film, it is most effective to perform the stretching at a temperature between 70 ° C and 200 ° C, in which the imidization reaction proceeds sufficiently and the solvent molecular evaporation is low and the fluidity of the polymer molecular chain is relatively high to be. It is difficult to efficiently control the orientation by stretching because the imidization reaction has not proceeded sufficiently at a temperature of 70 DEG C or lower. Stretching in a process at a temperature higher than 200 deg. C usually results in evaporation of the solvent, resulting in poor flowability of the polymer molecular chain, which makes stretching difficult. However, since the stretching degree becomes nonuniform in the width direction due to unevenness in drying, It becomes difficult to evenly adjust it.

The polyimide film of the present invention is preferably produced by setting the relative viscosity ratio of the polyamic acid solution used for the film formation and the 4.0% potassium bromide solution to 1.40 or higher. The tearing of the film corresponds to peeling off the intermolecular bonding of the polyimide molecules or the tangling of the molecular chains. The larger the molecular weight, the larger the intermolecular bonding or molecular chain entanglement in the film becomes. Therefore, when the relative viscosity of the polyamic acid solution and the 4.0% potassium bromide solution is less than 1.40, the intermolecular force of the polyimide components and the molecular chain tangling between the polyamic acid solution and the 4.0% potassium bromide solution are unlikely to be obtained, which tends to cause tearing of the film. In the present invention, the relative viscosity of the polyamic acid solution and the 4.0% potassium bromide solution is more preferably 1.40 or more and 1.80 or less, still more preferably 1.50 or more and 1.80 or less, still more preferably 1.60 or more and 1.80 or less. When the relative viscosity of the polyamic acid solution exceeds 1.80, since the viscosity of the polymer is too high, it becomes difficult to control the pressure loss in the claws, making it difficult to uniformly discharge the claws in the width direction from the claws, It may be easy to form.

The gel film after the stretching treatment is then preferably dried in a drying zone. In the case of heating by a hot air or the like in a drying zone, a means capable of exhausting hot air after use (air containing solvent or moisture-containing air) is provided, and a means for preventing mixing of used hot air in the drying zone is also preferably used. The hot air temperature in the drying zone is preferably in the range of 150 占 폚 to 350 占 폚. The drying time is preferably about 5 seconds to 10 minutes, more preferably 10 seconds to 5 minutes. Radiant heating as well as hot air may be used.

Since the imidization proceeds in the polymer chain molecule and between the polymer chain molecules to improve the mechanical properties (durability against external force), the film dried in the drying zone is subjected to a further heat treatment . The heat treatment is carried out by using known means such as hot air or an electric heater (for example, an infrared heater or the like). The heat treatment conditions are such that the heater output and the hot air temperature are adjusted so that the film L value is not less than 30 and not more than 55 and the final treatment conditions are 250 to 500 ° C and the treatment time is appropriately in the range of 15 seconds to 20 minutes desirable. If the film is heated rapidly in the heat treatment, defects such as increase of surface defects may occur. Therefore, it is preferable to appropriately select the heating method. The heat treated film is cooled and wound on a winding core.

The polyimide film obtained by the above method having a film thickness of 8.0 占 퐉 or less, preferably a film thickness of 3.0 占 퐉 or more and 8.0 占 퐉 or less, is industrially easily produced because of excellent film resistance and planarity, It is expected to be widely used for a base film of a flexible printed circuit board and a cover lay for the purpose of protecting or insulating a conductive circuit.

The polyamic acid which is a precursor of the polyimide in the present invention is preferably composed of aromatic tetracarboxylic acids and aromatic diamines and composed of repeating units represented by the following formula [I].

In the above formula, R 1 is a tetravalent organic group having at least one aromatic ring, the number of carbon atoms thereof is 25 or less, R 2 is a divalent organic group having at least one aromatic ring, and the number of carbon atoms is 25 or less .

In the present invention, the molar ratio of the aromatic tetracarboxylic acids of the polyamic acid as the precursor of the polyimide to the aromatic diamines is approximately equal to 1, but the molar ratio is 0.82 or more, preferably 0.90 or more, One of them may be blended in excess, and the molar ratio is polymerized to be 0.980 or more, more preferably 0.985 or more, and further preferably 0.990 or more.

The polyimide film in the present invention is a film obtained by imidizing a film using polyamic acid dissolved in an organic solvent. The polyamic acid in the organic solvent solution may be partially imidized and contains a small amount of an inorganic compound There may be.

Specific examples of the aromatic tetracarboxylic acids include pyromellitic acid, 3,3 ', 4,4'-biphenyltetracarboxylic acid, 2,3', 3,4'-biphenyltetracarboxylic acid, 3,3 Naphthalenetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, pyridine-2,3,4'-benzophenonetetracarboxylic acid, 2,3,6,7- 5,6-tetracarboxylic acid or an acid anhydride or acid dianhydride, or an aromatic tetracarboxylic acid derived from an ester compound or a halide of the acid.

Specific examples of the aromatic diamines include para-phenylenediamine, metaphenylenediamine, benzidine, paraxylylenediamine, 4,4'-diaminodiniphenyl ether, 3,4'-diaminodiphenyl ether, '-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3'- Dimethoxybenzidine, 1,4-bis (3-methyl-5-aminophenyl) benzene, and derivatives thereof.

Examples of the combination of the aromatic tetracarboxylic acid component and the aromatic diamine component particularly suitable for the polyimide in the method of the present invention include pyromellitic dianhydride, 4,4'-diaminodiphenyl ether and 3,3 ', 4,4 '-Biphenyltetracarboxylic acid dianhydride and 4,4'-diaminodiphenyl ether, and the copolymerization of these and / or the copolymerization of p-phenylenediamine is preferred. In the case where the present invention is not hindered, it may be molded into a multilayer body at the time of film formation.

Specific examples of the organic solvent used for forming the polyamic acid solution in the present invention include organic polar amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methyl- These organic solvents may be used alone or in combination of two or more, but they may be used in combination with non-solvent such as benzene, toluene and xylene. In the present invention, the organic solvent used for forming the polyamic acid solution can be measured by using a solvent which is hydrolyzed to form an amine.

The organic solvent solution of the polyamic acid used in the present invention preferably contains a solid content of 5 to 40% by weight, more preferably 10 to 30% by weight, and is preferably capable of stable pumping.

The polymerization reaction proceeds continuously in the temperature range of 0 to 80 ° C for 10 minutes to 30 hours while stirring and / or mixing in an organic solvent, but the polymerization reaction may be divided or the temperature may be increased or decreased as necessary.

In this case, the order of adding the two reactants is not particularly limited, but it is preferable to add aromatic tetracarboxylic acids to the solution of the aromatic diamines.

Vacuum defoaming during the polymerization reaction is an effective method for producing an organic solvent solution of high quality polyamic acid. Further, a small amount of end blocker may be added to the aromatic diamines prior to the polymerization reaction to control the polymerization.

Specific examples of the ring-closing catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine and picoline, and heterocyclic tertiary amines At least one amine selected from the group consisting of

Specific examples of the dehydrating agent used in the present invention include an aliphatic carboxylic acid anhydride such as acetic anhydride, propionic anhydride, and butyric anhydride, and an aromatic carboxylic acid anhydride such as anhydrous benzoic acid, but acetic anhydride and / or benzoic anhydride are preferable .

The content of the ring-closing catalyst with respect to the polyamic acid is preferably in the range of the content (mol) of the ring-closing catalyst / the content (mol) of the polyamic acid in the range of 0.5 to 8.

The content of the dehydrating agent relative to the polyamic acid is preferably in the range of the content (mol) of the dehydrating agent / the polyamic acid content (mol) in the range of 0.1 to 4. In this case, a gelling retarder such as acetylacetone may also be used in combination.

As a typical method for producing a polyimide film from an organic solvent of a polyamic acid, an organic solvent solution of a polyimide acid not containing a ring-closing catalyst and a dehydrating agent is cast on a support from a slit-equipped nail and molded into a film, A film is peeled off from the support after it is made into a gel film having a self-supporting property, and the film is further subjected to a heat treatment at a high temperature to imidize the film; and an organic solvent of a polyamic acid containing a cyclization catalyst and a dehydrating agent, A film is formed on a support to form a film, a film having a self-supporting property is formed on the support by partially progressing the imidization, and then the film is peeled off from the support to heat-dry / . The present invention can adopt any of the above-described ring closing methods. However, the chemical ring closing method requires a facility for containing a ring-closing catalyst and a dehydrating agent in an organic solvent solution of polyamic acid, but a gel film having magnetic holding properties can be obtained in a short time, . The gel film in the present invention is a polyimide film containing a polyimide precursor and / or a partially imidized solvent.

(Example)

The following examples illustrate the present invention but are not to be construed as limiting thereof. In addition, evaluation methods and evaluation criteria of each of the characteristics described in the above-mentioned and the following embodiments are as follows.

(1) Tear propagation resistance

The tear propagation resistance was measured using a No.193 type D light load tester of Toyo Seiki Seisakusho Co., Ltd. according to the Elmendorf thermal method described in JIS K 7128-2 (issued on November 20, 1998) This value is measured by the method described in the instruction manual of the second edition of May. As for the sample size, films having a sample size of 63.5 mm length x 50 mm width and a cut length of 12.7 mm were collected from the center of the film in the longitudinal direction and the width direction, respectively, as shown in Fig. The number of sheets to be measured is one sheet, and the smaller the value in the lengthwise direction and the widthwise direction is measured as the tear propagation resistance value of the film, measured at 25 캜 and 60% RH.

(2) Film thickness

The film thickness was measured using a Digital Micrometer M-30 manufactured by SONY Corporation, and the value obtained by rounding the first decimal place of the value obtained by dividing the thickness value by 10 was taken as the film thickness.

(3) Film elongation

The elongation of the film was strictly divided so that the width of each film was 500 mm around the center of the film, and 6.5 m in the longitudinal direction was sampled and spread uniformly on a flat plate. And the distance between the side of the film and the side of the film was determined at the end and the center, and the absolute value thereof was taken as the film elongation value (FIG. 2). The value of the maximum point of each of the split elongation values was taken as the elongation value of the film.

(4) Ultrasonic transmission speed

Was measured using a SONIC SHEET TESTER (model SST-2500, manufactured by Nomura Shoji Co., Ltd.). Each of the films was divided strictly at intervals of 262 mm around the center of the film, and films each having a length of 250 mm in length were sampled at eight positions. The time required for ultrasonic pulse transmission between the center of each sample film and the diameter of 12 cm was measured (Fig. 3). The orientation of one place was measured in 4 seconds by the multi-sensor type measuring head. The measurement unit angle was measured at 16 points in total from 11.25 ° to 180 °, and the minimum value of all the measured values was set as the ultrasonic transmission rate of the film (in the case of a thin film of 8.0 μm or less, the influence due to the molecular chain orientation and coarse structure Since this strong speed is sometimes measured at a low speed, 30 sheets were superimposed so that the speed was saturated).

(5) Relative viscosity

A sample for measurement in which a polyamic acid solution used for film formation was diluted in a 0.5% solution and a 4.0% lithium / bromide / N, N-dimethylacetamide solution were measured according to JIS K2283 (revised Nov. 20, 2000. Canon- , Temperature: 30 占 폚), and the fall time ratio was calculated as the relative viscosity.

Relative viscosity (? R) = 2 占 Ln (Ts / Tb)

Ts: Drop time of polyamic acid solution for viscosity measurement (s)

Tb: drop time (s) of 4.0% lithium bromide / N, N-dimethylacetamide solution.

Method of adjusting polyamic acid solution for viscosity measurement

1. Polymer concentration measurement

Weigh the polyamic acid solution in a pre-weighed aluminum container. Thereafter, the resultant was heated in an oven heated to 100 ° C for 0.5 hour, then heated to 350 ° C at a rate of 10 ° C / min, and then heated at 350 ° C for 2 hours. After the completion of the heating, the polymer was drawn out and cooled for 15 minutes, and the weight was measured to calculate the polymer concentration by the following formula.

Polymer concentration (%) = 100 - {(B - C) / (B - A)

A: Weight of aluminum container (g)

B: Weight of aluminum container (g) + weight of polymer solution before heating (g)

C: weight of container made of aluminum (g) + weight of polymer after heating (g)

2. Adjustment of polyamic acid solution for viscosity measurement

Weigh the polyamic acid solution in a pre-weighed aluminum container. A 4.0% solution of lithium bromide / N, N-dimethylacetamide in an amount of the following formula was added so that the polymer concentration was 0.5%.

(E) = ((E-D) x F / 100} /0.005- (E-D) The amount of the lithium bromide / N, N-dimethylacetamide solution added in 4.0%

D: Weight of aluminum container (g)

E: weight of aluminum container (g) + weight of polymer solution (g)

F: Polymer concentration (%)

(6) Young's modulus

The Young's modulus was determined from a gradient of an initial rising portion in a tensile-strain curve obtained at a tensile speed of 300 mm / min by a tensile-type tensile tester manufactured by ORIENREC at room temperature in accordance with JIS-K 7127 (revised August 20, 1999) (Gradient of initial rising portion x initial sample length) / (sample width x sample thickness). For the sample, a sample having a size of 10 mm x 250 mm was sampled from the center of the film and measured under an atmosphere of a distance between chucks of 100 mm and 25 DEG C and 60% RH. The film was measured in the longitudinal direction and the width direction, and the smaller the value, the Young's modulus of the film.

(7) Film formability (ease of film formation)

A case where no film tear due to creasing or tearing occurred during film formation with a film length of 5000 m was indicated as & cir &

(8) Processability (ease of processing)

The polyimide film was coated on the polyimide film with a roll coater so that the total coating thickness after drying was 12.5 占 퐉 and dried by heating at 80 占 폚 for 2 minutes and at 120 占 폚 for 5 minutes and then at a temperature of 50 占 폚 and a linear pressure of 5 kg / At a speed of 2 m / min and a tension of 1 kg / m by means of a roll laminator to obtain a coverlay film. The processing conditions were evaluated based on the following criteria.

○: Bending and no wrinkles

B: Bended and partially wrinkled,

X: Bending on the front and wrinkles.

[Example 1]

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenyl (Molecular weight: 108.14) was prepared at a molar ratio of 65/35/82/18 (the monomer composition ratio was defined as A) and polymerized as a 20 wt% solution in N, N-dimethylacetamide, To obtain a polyamic acid solution of 3800 poise. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.59.

2.0 mol of N, N-dimethylacetamide dried in the polyamic acid solution, 4.0 mol of acetic anhydride in relation to the polyamic acid unit and 4.0 mol of beta-picoline in the polyamic acid unit To adjust the polyamic acid solution.

This polyamic acid solution was extruded from a T-die having a slit width of 1.3 mm and a length of 2000 mm to obtain a support ratio of 10.6, and cast on a rotating metal support having a temperature of 80 DEG C Gel film. This gel film was continuously peeled off from the support and transported in rolls while being stretched to 1.22 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction on the fin plate at a ratio of 1.62 times, and air of 250 DEG C was blown in the tenter for 20 to 40 seconds to be dried. Then, the gel film was heat-treated at 450 DEG C by using an electric heater And then cooled to room temperature while relaxing. Thereafter, the end of the film was peeled off from the fin, and the edge of the end of the film was cut to obtain a polyimide film having a width of 2300 mm and a thickness of 7.8 탆. Wrinkles or sagging did not occur in the film during the film formation, and the film could be formed stably with a length of 5000 m or more. The obtained film had a tear propagation resistance of 1.9 N / mm and an ultrasonic transmission speed of 2.28 km / sec. The value of the elongation at break was 2 mm, and the workability was also good.

[Example 2]

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenyl (Molecular weight: 108.14) at a molar ratio of 75/25/71/29 (the monomer composition ratio is represented by B) and polymerized as a 20 wt% solution in N, N-dimethylacetamide, To obtain a polyamic acid solution of 3800 poise. The relative viscosity of this solution with a 4.0% potassium bromide solution was 1.58. A polyimide film having a width of 2300 mm and a thickness of 7.5 탆 was obtained in the same manner as in Example 1 except that the stretching magnification in the film longitudinal direction was 1.24 and the stretching magnification in the width direction was 1.51. Wrinkles or sagging did not occur in the film during the film formation, and the film could be formed stably with a length of 5000 m or more. The obtained film had a tear propagation resistance of 2.0 N / mm and an ultrasonic transmission speed of 2.33 km / sec. In addition, the elongation value was 3 mm and the processability was good.

[Example 3]

Biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenylmethane dianhydride (molecular weight 218.12) / 3,3 ' (Molecular weight: 108.14) in a molar ratio of 75/25/75/25 (the monomer composition ratio is C) and polymerized as a 19 wt% solution in N, N-dimethylacetamide, To obtain a polyamic acid solution of 3800 poise. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.65.

2.0 mol of N, N-dimethylacetamide dried in the polyamic acid solution, 4.0 mol of acetic anhydride in relation to the polyamic acid unit and 4.0 mol of beta-picoline in the polyamic acid unit To adjust the polyamic acid solution.

The polyamic acid solution was extruded from a T-die having a slit width of 1.3 mm and a length of 2000 mm to obtain a support ratio of 9.8, and cast on a rotating metal support at 80 캜 to obtain a self- Gel film. The gel film was continuously peeled off from the support, and was transported into a roll while being stretched to 1.28 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction on the fin plate at a ratio of 1.46, and air of 250 DEG C was blown in the tenter for 20 to 40 seconds to be dried. Then, the gel film was heat-treated at 450 DEG C using an electric heater And then cooled to room temperature while relaxing. Thereafter, the end of the film was peeled off from the pin, and the edge of the end of the film was cut to obtain a polyimide film having a width of 2100 mm and a thickness of 7.8 탆. Wrinkles or sagging did not occur in the film during the film formation, and the film could be formed stably with a length of 5000 m or more. The obtained film had a tear propagation resistance of 2.2 N / mm and an ultrasonic transmission speed of 2.27 km / sec. The value of the elongation at break was 6 mm, and the workability was also good.

[Example 4]

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenyl (Molecular weight: 108.14) was prepared at a molar ratio of 65/35/82/18 (the monomer composition ratio was defined as A) and polymerized as a 20 wt% solution in N, N-dimethylacetamide, To obtain a polyamic acid solution of 3800 poise. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.64.

2.0 mol of N, N-dimethylacetamide dried in the polyamic acid solution, 4.0 mol of acetic anhydride in relation to the polyamic acid unit and 4.0 mol of beta-picoline in the polyamic acid unit To adjust the polyamic acid solution.

This polyamic acid solution was extruded from a T-die having a bending slit width of 1.3 mm and a length of 2000 mm to give a ratio of the support speed to the bare metal discharge speed of 12.7 and cast on a rotating metal support at 80 캜, Gel film. This gel film was continuously peeled off from the support and transported in rolls while being stretched to 1.22 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction on the fin plate at a rate of 1.55 times, and air of 250 DEG C was blown in the tenter for 20 to 40 seconds to be dried. Then, the gel film was heat-treated at 450 DEG C using an electric heater And then cooled to room temperature while relaxing. Then, the end of the film was peeled off from the pin, and the edge of the end of the film was cut to obtain a polyimide film having a width of 2100 mm and a thickness of 6.8 탆. Wrinkles or sagging did not occur in the film during the film formation, and the film could be formed stably with a length of 5000 m or more. The obtained film had a tear propagation resistance of 1.9 N / mm and an ultrasonic transmission speed of 2.24 km / sec. The value of the elongation at break was 4 mm, and the workability was also good.

[Example 5]

The support film was formed in the same manner as in Example 4 except that the ratio of the support speed to the nipping speed was 15.9 to obtain a polyimide film having a width of 2100 mm and a thickness of 5.1 탆. Wrinkles or sagging did not occur in the film during the film formation, and the film could be formed stably with a length of 5000 m or more. The obtained film had a tear propagation resistance of 1.9 N / mm and an ultrasonic transmission speed of 2.24 km / sec. A film roll having a width of 500 mm and a length of 3000 m was obtained by slitting on a commercially available slit machine. The value of the elongation at break was 6 mm, and the workability was also good.

[Example 6]

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenyl (Molecular weight: 108.14) was prepared at a molar ratio of 75/25/71/29 (the monomer composition ratio was defined as B) and polymerized as a 20 wt% solution in N-methyl-2-pyrrolidone, A polyamic acid solution of 3800 poise at 25 占 폚 was obtained. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.60.

2.0 mol of N-methyl-2-pyrrolidone dried in the polyamic acid solution, 4.0 mol of anhydrous propionic acid and 4.0 mol of pyridine in relation to the polyamic acid unit, To adjust the polyamic acid solution.

The polyamic acid solution was extruded from a T-die having a slit width of 1.3 mm and a length of 2000 mm to obtain a ratio of the support speed to the screw discharge speed of 15.5 and cast on a rotatable metal support having a temperature of 80 캜, Gel film. This gel film was continuously peeled off from the support and transported in rolls while being stretched to 1.22 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction at 1.54 times on the fin plate, and air of 250 DEG C was blown in the tenter for 20 to 40 seconds to be dried. Then, the gel film was heat-treated at 450 DEG C by using an electric heater And then cooled to room temperature while relaxing. Thereafter, the end of the film was peeled off from the pin, and the edge of the end of the film was cut to obtain a polyimide film having a width of 2100 mm and a thickness of 6.0 占 퐉. Wrinkles or sagging did not occur in the film during the film formation, and the film could be formed stably with a length of 5000 m or more. The obtained film had a tear propagation resistance of 2.0 N / mm and an ultrasonic transmission speed of 2.34 km / sec. The value of the elongation at break was 2 mm, and the workability was also good.

[Comparative Example 1]

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenyl (Molecular weight: 108.14) was prepared at a molar ratio of 65/35/82/18 (the monomer composition ratio was defined as A) and polymerized as a 20 wt% solution in N, N-dimethylacetamide, To obtain a polyamic acid solution of 3200 poise. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.32.

2.0 mol of N, N-dimethylacetamide dried in the polyamic acid solution, 4.0 mol of acetic anhydride in relation to the polyamic acid unit and 4.0 mol of beta-picoline in the polyamic acid unit To adjust the polyamic acid solution.

This polyamic acid solution was extruded from a T-die having a bore slit width of 1.3 mm and a length of 2000 mm to give a ratio of the support speed to the die discharge speed of 10.6 and cast on a rotating metal support having a temperature of 80 캜, Gel film. This gel film was continuously peeled off from the support and transported in rolls while being stretched to 1.22 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction on the fin plate at a stretching ratio of 1.61, and then air of 250 DEG C was blown in the tenter for 20 to 40 seconds to dry. Then, the gel film was heat-treated at 450 DEG C using an electric heater And then cooled to room temperature while relaxing. Thereafter, the film end portion was removed from the fin, and the edge of the end portion of the film was cut to obtain a polyimide film having a width of 2300 mm and a thickness of 7.8 탆. However, after reaching the above-mentioned condition, tearing occurred from the end of the film after film formation for 500 m, resulting in film tearing. The film was re-tried under the same conditions, but the film tearing occurred again in the film formation of about 100 m, and the film formation could not be continued stably. The tear propagation resistance of the film immediately before the film tear was 1.5 N / mm, and the ultrasonic transmission speed was 2.22 km / sec. Further, the elongation value was 6 mm, and the workability was good.

[Comparative Example 2]

(Molecular weight: 218.12) / 4,4'-diaminodiphenyl ether (molecular weight: 200.24) at a molar ratio of 100/100 (this monomer composition ratio is referred to as D) and N, N-dimethyl Acetamide as a 23 wt% solution to obtain a polyamic acid solution having a molecular weight of 3200 at 25 ° C. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.38.

2.0 mol of N, N-dimethylacetamide dried in the polyamic acid solution, 4.0 mol of acetic anhydride in relation to the polyamic acid unit and 4.0 mol of beta-picoline in the polyamic acid unit To adjust the polyamic acid solution.

This polyamic acid solution was extruded from a T-die having a slit width of 1.3 mm and a length of 2000 mm to obtain a ratio of the supporter speed to the embossing speed of 12.0, and cast on a rotating metal support having a temperature of 80 캜, Gel film. This gel film was continuously peeled off from the support and transported in rolls while being stretched to 1.22 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction on the fin plate at a rate of 1.55 times, and air of 250 DEG C was blown in the tenter for 20 to 40 seconds to be dried. Then, the gel film was heat-treated at 450 DEG C using an electric heater And then cooled to room temperature while relaxing. Thereafter, the end of the film was peeled off from the pin, and the edge of the end of the film was cut to obtain a polyimide film having a width of 2200 mm and a thickness of 7.6 탆. However, after reaching the above-mentioned condition, wrinkles occurred on the film on the gel film conveying roll after 2000m film formation, and the film tore from the film end to cause film tearing. The tear propagation resistance of the film just before the film tear was 1.4 N / mm, and the ultrasonic transmission rate was 1.62 km / sec. In addition, the elongation value was 9 mm, and there was a partly noticeable wrinkle in the film after the coverlay processing.

[Comparative Example 3]

(Molecular weight 218.12) / 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride (molecular weight 294.22) / 4,4'-diaminodiphenyl ether (molecular weight 200.24) / paraphenyl (Molecular weight: 108.14) at a molar ratio of 94/6/87/13 (the monomer composition ratio is E) and polymerized as a 19 wt% solution in N, N-dimethylacetamide, To obtain a polyamic acid solution of 3800 poise. The relative viscosity of this solution with 4.0% potassium bromide solution was 1.60.

2.0 mol of N, N-dimethylacetamide dried in the polyamic acid solution, 4.0 mol of acetic anhydride in relation to the polyamic acid unit and 4.0 mol of beta-picoline in the polyamic acid unit To adjust the polyamic acid solution.

This polyamic acid solution was extruded from a T-die having a bending slit width of 1.3 mm and a length of 2000 mm to adjust the ratio of the support speed to the bead discharge speed to 13.5 and cast on a rotating metal support at 80 캜, Gel film. The gel film was continuously peeled from the support and transported in a roll while being stretched to 1.15 times in the longitudinal direction of the film in a room at 70 캜. The both ends of the gel film were pressed by a roller while continuously sticking to the pin plate on the chain to fix the gel film, and the gel film was first dried and fixed by blowing air at 250 DEG C for 5 to 10 seconds on the pin plate. The gel film having both ends fixed by pins was stretched in the width direction on the fin plate at a ratio of 1.35, and air of 250 DEG C was blown in the tenter for 20 to 40 seconds to be dried. Then, the gel film was heat-treated at 450 DEG C using an electric heater And then cooled to room temperature while relaxing. Thereafter, the end of the film was peeled off from the pin, and the edge of the end of the film was cut to obtain a polyimide film having a width of 2100 mm and a thickness of 5.5 탆. However, after reaching the above condition, wrinkles were formed on the film on the gel film conveying roll after 1700 m film formation, and the film was torn off when the film end was peeled off from the fin. The tear propagation resistance of the film immediately before the film tear was 1.6 N / mm, and the ultrasonic wave transmission rate was 1.94 km / sec. Further, the value of the half-elongation was 12 mm, and wrinkles were mostly present on the entire surface of the film after the coverlay processing.

Table 1 summarizes the above results.

Although the polyimide film obtained in the present invention has a thickness of 8.0 탆 or less and is excellent in heat resistance and planarity, it is industrially easy to produce and has excellent handling properties during processing, so that the base film of the flexible printed substrate and the conductive circuit It is expected that it will be widely used for coverlay applications for protection or insulation purposes.

Claims (6)

Wherein the tear propagation resistance value of the film is 1.7 N / mm or more, and the minimum value of the ultrasonic wave transmission rate of the film is 2.0 km / sec or more and the film thickness is 8.0 占 퐉 or less. The method according to claim 1,
Wherein the film elongation is 8 mm or less. 3. The method according to claim 1 or 2,
Wherein the polyimide film is in the form of a polyimide film roll having a width of 500 mm or more and 3000 mm or less and a length of 1000 m or more. The polyamide acid solution is continuously extruded or stretched in the form of a film on a support, or a coated gel film is peeled from the support and is subjected to stretching, drying and heat treatment. (A stretching ratio in the longitudinal direction x a stretching ratio in the transverse direction) of not less than 1.60 and a tear propagation resistance value of the film of 1.7 N / mm or more in the film stretching process, Wherein a polyimide film having a minimum ultrasonic transmission rate of 2.0 km / sec or more and a film thickness of 8.0 탆 or less is produced. 5. The method of claim 4,
The polyamic acid solution is continuously extruded or film-coated on the support in the form of a film. The gel film is peeled off from the support and is subjected to stretching, drying and heat treatment. The polyamic acid solution used for the production of the polyimide film is 4.0% Wherein the relative viscosity to the potassium solution is 1.40 or more and 1.80 or less. The method according to claim 4 or 5,
Wherein the film elongation is 8 mm or less.

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