KR20120090778A - Polyimide film with improved variation of the oefficient of linear expansion - Google Patents

Abstract

PURPOSE: A polyimide film is provided to not to have problems in processability of a laminating method, not to occur bending, and to have excellent thermal resistance by having uniform linear expansion coefficient regardless of a location of a film. CONSTITUTION: A heat treated-polyimide film is obtained by heat treating a polyimide film, of which temperature that a rate of change of linear expansion coefficient in mechanical return direction(8) becomes 25% is 200°C or higher, at temperature 100-150 °C higher than the temperature that the rate of change of linear expansion coefficient becomes 25%. In random two point, difference between average linear expansion coefficient in mechanical return direction at 50-300 °C is 15 ppm/°C or less. Time of the heat treatment is 0-10 seconds.

Description

POLYIMIDE FILM WITH IMPROVED VARIATION OF THE OEFFICIENT OF LINEAR EXPANSION}

The present invention relates to a polyimide film which is preferably used as a material of a flexible printed wiring board used in the field of electric and electronic devices. More specifically, one side or both sides of the polyimide film as a base material The present invention relates to a polyimide film having a non-uniformity in coefficient of linear expansion, which is preferably used as a material of a flexible printed wiring board by adhering a copper plate to a polyimide adhesive.

In recent years, printed wiring boards are widely used in electronic and electrical equipment. Among them, flexible printed circuit boards (FPCs) that are bendable are widely used in parts that require bending such as a hinge portion of a personal computer, a digital video camera or a mobile phone, a hard disk, and the like.

As a main material constituting the flexible printed wiring board for electronic applications, a copper clad laminate (CCL) using a polyimide film in consideration of heat resistance is known. This copper foil laminated sheet is roughly classified into three-layer CCL and two-layer CCL. The two-layer CCL generally has better heat resistance, dimensional stability, and electrical characteristics than the three-layer CCL, and the three-layer CCL cannot satisfy the required characteristics (e.g., plasma display, folding mobile phone It is often used for branch offices, etc.).

As a manufacturing method of a two-layer CCL, the cast method which coats a polyimide resin to copper foil, the lamination method which bonds a copper foil and a polyimide film using a polyimide-type adhesive agent, and a metal to a polyimide film There is a sputtering method of copper plating after deposition or sputtering.

In the laminating method, an epoxy adhesive, an acrylic adhesive and the like are also used, but in order to fully utilize the excellent properties of the polyimide film, a polyimide adhesive having excellent heat resistance may be used (Patent Document 1). When a polyimide adhesive is used in the laminating method, the polyimide often has insufficient adhesiveness with copper foil due to its chemical structure and chemical resistance (solvent) stability, in order to increase the adhesiveness. It is necessary to laminate by laminating with copper foil at high temperature of 300 degreeC or more.

However, since the polyimide film shrinks after the laminating and the like after the etching treatment, even if a polyimide film having a small coefficient of linear expansion can be partially obtained, there are also sites where the coefficient of linear expansion is large, so that the nonuniformity of the linear expansion coefficient is large. Polyimide film was produced. Therefore, when using a polyimide film, it is necessary to select the site | part with a small linear expansion coefficient, and since a quality is not uniform as a product, it becomes a problem at the time of actual use, and the poly with a small linear expansion coefficient is uniform in the whole surface of a film. The development of the mid film was called for.

Japanese Patent Application Publication No. 2005-186274

An object of the present invention is to provide a polyimide film having a uniform linear expansion coefficient regardless of the position of the film, excellent dimensional stability, and improved nonuniformity of the linear expansion coefficient.

In view of the above-described circumstances, the present inventors have conducted extensive research, and in the laminating method, before the polyimide adhesive is applied on the polyimide film surface, a heat treatment is performed in a specific temperature range. It discovered that the polyimide film which has uniform dimensional stability in the width direction of a film was obtained, and further examined, and completed this invention.

That is, this invention includes the following invention.

[1] heat treatment at a temperature of 100 ° C to 150 ° C higher than a temperature at which the rate of change of the coefficient of linear expansion is 25% to a polyimide film having a temperature of 200% or more at which the rate of change of the coefficient of linear expansion in the mechanical conveyance direction is 25% Obtained, and the difference of the linear expansion coefficient of a machine conveyance direction is 15 ppm / degrees C or less with respect to arbitrary two points, The heat-treated polyimide film characterized by the above-mentioned.

[2] The heat treatment polyimide film according to the above [1], wherein the heat treatment time is more than 0 seconds and 10 seconds or less.

[3] A film roll comprising a heat-treated polyimide film according to the above [1] or [2], which is 500 mm or more in width and 50 m or more in length.

[4] a step of subjecting a polyimide film having a temperature of 200% or more at a temperature of 25% change in the coefficient of linear expansion in the machine conveyance direction to a heat treatment at a temperature of 100 ° C. to 150 ° C. higher than a temperature at which the rate of change of the linear expansion coefficient is 25%. Method for producing a heat-treated polyimide film, characterized in that it comprises a.

[5] The method for producing a heat treated polyimide film according to the above [4], wherein the heat treatment time is more than 0 seconds and 10 seconds or less.

Since the heat-treated polyimide film of the present invention has a uniform coefficient of linear expansion and dimensional stability irrespective of the position on the film, there is no problem in workability in the laminating method, no warpage occurs, and excellent heat resistance, so that It is not necessary to use it separately, and also the processing, such as cut | disconnection for each site | part, is unnecessary and is especially useful for a flexible printed wiring board.

1 is a schematic view showing the heating apparatuses of Examples 1-3 and Comparative Examples 1-3.

EMBODIMENT OF THE INVENTION Hereinafter, invention is demonstrated concretely. The heat-treated polyimide film of the present invention is 100 ° C to 150 ° C higher than the temperature at which the rate of change of the coefficient of linear expansion is 25% to a polyimide film having a temperature of 200% or higher at which the rate of change of the coefficient of linear expansion in the machine conveyance direction is 25%. It is obtained by heat-processing at temperature, The difference of the linear expansion coefficient of a machine conveyance direction is 15 ppm / degrees C or less in 50 degreeC-300 degreeC with respect to arbitrary two points.

In the present invention, the heat-treated polyimide film means a polyimide film after the heat treatment. In addition, MD is the machine conveyance direction hereafter, TD is the width direction, and the linear expansion coefficient of a machine conveyance direction is also called (alpha) _MD . How to measure the rate of change α _MD and the method of measurement of α _MD is the same as will be described later.

The evaluation method of each characteristic in this invention, and the criteria of evaluation are as follows.

(1) linear expansion coefficient

A linear expansion coefficient is the value which heated up from room temperature to 320 degreeC at the temperature increase rate of 10 degree-C / min using the thermal analysis apparatus (TMA-50, the Shimadzu Corporation make), and analyzed the range of 50-300 degreeC. .

(2) Change rate of linear expansion coefficient

The change rate of (alpha) _MD was measured over 50 to 450 degreeC at the temperature increase rate of 10 degree-C / min using the thermal analyzer (TMA-50, the Shimadzu Corporation make). The average of the linear expansion coefficient was calculated | required in 10 degreeC steps from a 50 degreeC viewpoint, and the change rate was calculated | required by the following formula.

% Change = [(C2-C1) / C1] × 100

C2: coefficient of linear expansion of the temperature for which the rate of change is to be obtained

C1: Coefficient of linear expansion at temperature 10 ° C. lower than C2

(3) the temperature of the film

The measuring part of the sheath thermocouple (K type (T-35), manufactured by Okazaki Corporation) was mounted on the film surface, and the terminal was connected to a recorder (NR-1000, manufactured by Keyence Corporation). The inside of oven was conveyed by the process conditions of a film, and the actual temperature of the film was measured.

(4) measurement of wind speed

The wind speed of the air which hits the film surface was measured using the anemometer (Anemone anemometer MODEL6162, the product made by Kanomax).

It is preferable to perform heat processing in this invention at the temperature which is about 100-150 degreeC higher than the temperature which the change rate of (alpha) _MD of the polyimide film heat-processed becomes 25%, and it is more preferable to carry out at the temperature which is about 100-140 degreeC high. Do. When the temperature of heat processing exceeds 150 degreeC more than the temperature which the change rate of (alpha) _MD of the polyimide film heat-processed becomes 25%, since expansion and contraction of a film advances partially, it is unpreferable in the point which cannot maintain favorable planarity. . Moreover, when the temperature of heat processing is less than 100 degreeC higher than the temperature which the change rate of (alpha) _MD of the polyimide film heat-processed becomes 25%, since the nonuniformity fall of a linear expansion rate is not enough, it is unpreferable.

The heat treatment may be performed in multiple stages. In this case, the temperature of the final stage is preferably higher than the temperature of the first stage. In the case where the heat treatment is performed in multiple stages, the temperature is about 100 to 150 ° C higher than the temperature at which the change rate of α _MD of the polyimide film subjected to the heat treatment is 25%, and the change rate of α _MD is at least 25%. It is preferable to make the minimum temperature.

It is preferable that the time to perform the said heat processing is about 0 second or more and about 10 second or less, It is more preferable that it is about 0 second or more and about 8 second or less, It is most preferable that it is about 3 second or more and about 8 second or less. In addition, the said heat processing may be divided into multiple times, and in this case, time to heat-process means total processing time. If the time for performing the heat treatment exceeds 10 seconds, the non-uniformity of α _MD is not suppressed and the planarity of the film obtained is significantly deteriorated, which is not preferable. The time for performing the heat treatment can be adjusted, for example, at the relative rotational speed of each roller. In the case where the heat treatment is performed in multiple stages, it is preferable that the sum of the processing times of all the stages is more than 0 seconds and about 10 seconds or less, more preferably more than 0 seconds and about 8 seconds or less, most preferably about 3 seconds or more and 8 seconds or less. desirable.

The heat treatment means in the present invention is not particularly limited as long as the effects of the present invention are not impaired. For example, a method of irradiating far infrared rays using a ceramic heater or the like, a method of blowing hot air, and a radiator heater are used. These methods may be used, and each method may be used independently and may use two or more methods together. As said far-infrared ray, since heat processing is performed in extremely short time, it is preferable to use what has a wavelength of about 2 micrometers-10 micrometers. In the method of blowing hot air, it is preferable that the wind speed of hot air is about 1.5-2.5 m / sec. By setting the wind speed to 1.5 m / sec or more, the heat transfer efficiency from the atmosphere is increased by circulating the air, and the film is more preferably heat treated evenly. In addition, when the wind speed exceeds 2.5 m / sec, the polyimide film tends to be loosely stretched by the pressure of the injected hot air, which is not preferable.

It is preferable to perform the said heat processing, for example, by running a film in the furnace provided with the said heat processing means. In this case, the residence time of the film in the furnace corresponds to the heat treatment time. Although the film tension at the time of running in a furnace is not specifically limited unless the effect of this invention is impaired, about 1-50 N / m is preferable and about 5-25 N / m is more preferable. When the tension is lower than the above-mentioned range, the running property of the film is deteriorated, and when the tension is higher than the above-mentioned range, the heat shrinkage in the MD direction of the obtained film is high, which is not preferable. The film tension during the heat treatment can be adjusted by, for example, the difference in rotational speeds of the feeding roller and the winding roller. Moreover, the running speed of a film is not specifically limited unless the effect of this invention is impaired, but about 10-200 m / min is preferable at the point which raises the nonuniformity reduction effect of (alpha) _MD , and is about 30-120 m / min is more preferred.

Moreover, as the heat-treated polyimide film of this invention, it is preferable that the difference of (alpha) _MD in arbitrary two points is about 15 ppm / degrees C or less within the range of 50 degreeC-300 degreeC, and it is more preferable that it is about 10 ppm / degrees C or less. . If the difference of α _MD is large, there is a possibility that a problem may occur if it is used as it is, and it is not preferable because it is necessary to select and use a small difference of α _MD . Moreover, it is preferable that it is about 50 ppm / degrees C or less, and, as for alpha _MD in each point, it is more preferable that it is about 40 ppm / degrees C or less.

Although it does not specifically limit as an aspect which provides the heat processing polyimide film of this invention, unless the effect of this invention is impaired, Usually, forms, such as a roll form and a sheet form, are mentioned. Since the nonuniformity of the coefficient of linear expansion by a site | part is low in the heat processing polyimide film of this invention, it is preferable to provide in the roll form which the film of 500 mm or more in width and / or 50 m or more in length wound up.

Although the polyimide film used for manufacture of the heat-processing polyimide film of this invention is not specifically limited unless the effect of this invention is impaired, It is preferable that the temperature which the change rate of (alpha) _MD becomes 25% or more is about 200 degreeC, More preferably, it is at least about 250 ° C. Moreover, about 1-250 micrometers is preferable and, as for the thickness of the said polyimide film, a favorable uniformity is obtained, about 5-50 micrometers is more preferable. As such a film, a commercially available thing, the thing manufactured by a well-known method, etc. are used widely.

Hereinafter, an example of the manufacturing method of the polyimide film used by this invention is demonstrated. The polyimide film used in the present invention is a step of polymerizing a (a) aromatic diamine component and an acid anhydride component in an organic solvent to obtain a polyamic acid solution, and (b) cyclization of the polyamic acid solution. It may be produced according to a method including a step of reacting to obtain a gel film and (c) stretching the gel film obtained in the step (b).

The said process (a) is a process of polymerizing-reacting an aromatic diamine component and an acid anhydride component in an organic solvent, and obtaining a polyamic-acid solution. As a polyamic acid contained in the said polyamic acid solution, it is preferable that it consists of the repeating unit which consists of aromatic tetracarboxylic acid and aromatic diamine, and is shown by following General formula (1). The polyamic acid may be partially imidized in the solution, or may contain a small amount of an inorganic compound or the like.

[Formula 1]

In the general formula (1), R ¹ is a tetravalent organic group having at least one aromatic ring, its carbon number is 25 or less, and R ² is a divalent organic group having at least one aromatic ring, Carbon number is 25 or less.

Although the said aromatic tetracarboxylic acid and the said aromatic diamine are mix | blended in the ratio in which each mole number is about the same, it is mix | blended excessively with respect to the other in the range of about 10 mol%, preferably about 5 mol% in one of them. You 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 ', 4, 4'-benzophenonetetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, pyridine-2,3,5,6-tetracarboxylic acid or its Acid anhydrides, acid dianhydrides, or aromatic tetracarboxylic acids derived from ester compounds or halides thereof.

Specific examples of the aromatic diamines include paraphenylenediamine, metaphenylenediamine, benzidine, paraxylylenediamine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4, 4'-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.

As a particularly suitable combination of the aromatic tetracarboxylic acid component and the aromatic diamine component in the present invention, pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, and 3,3 ', 4,4'-biphenyltetracarboxylic acid 2 Combinations of anhydrides and 4,4'-diaminodiphenyl ethers are preferred. Moreover, as a polyamic acid obtained from the said aromatic tetracarboxylic acid component and an aromatic diamine component, what is obtained by these copolymerization and / or copolymerization with paraphenylenediamine is preferable.

Specific examples of the organic solvent used for preparing the polyamic acid solution include organic polar amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, and the like. Although these organic solvents are used individually or in combination of 2 or more types, you may use in combination with nonsolvents, such as benzene, toluene, and xylene.

Although the said polymerization reaction advances continuously for about 10 minutes-30 hours normally in the temperature range of about 0-80 degreeC, stirring and / or mixing in an organic solvent, you may adjust temperature suitably up and down as needed, You may divide a polymerization reaction into several times. Although the addition order of both reactants does not have a restriction | limiting in particular, It is preferable to add aromatic tetracarboxylic acids in the solution of aromatic diamines. Vacuum defoaming during the polymerization reaction is an effective method for producing an organic solvent solution of high quality polyamic acid. In addition, before the polymerization reaction, a small amount of terminal blocking agent may be added to the aromatic diamines to control the polymerization.

The polyamic acid solution contains a solid content, preferably about 5 to 40% by weight, more preferably about 10 to 30% by weight. In addition, since stable liquid feeding is possible, the viscosity is preferably about 10 to 2000 Pa · s, more preferably about 100 to 1000 Pa · s, as measured by a Brookfield viscometer.

The polyamic acid solution is chemically inert such as titanium oxide, fine silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, polyimide filler or the like, as necessary to obtain diactivation of the film. A phosphorus organic filler, an inorganic filler, etc. can be contained, As such a filler, a silica is preferable.

The said process (b) is a process of obtaining the gel film by carrying out the cyclic reaction of the said polyamic acid solution. As said cyclic | annular reaction, there exist a thermal cyclization method and the chemical yclization method, for example. The thermal ring closure method comprises casting an organic solvent solution of the polyamic acid containing no ring closure catalyst and a dehydrating agent on a support from a mouth piece equipped with a slit to form a film, and heating and drying on the support. It is a method of obtaining a gel film by dehydrating annularizing. In the chemical ring closure method, a solution containing a ring closure catalyst and a dehydrating agent in an organic solvent solution of the polyamic acid is cast on a support from a mouthpiece equipped with a slit to form a film, and part of the annularization on the support is formed. After advancing, it is a method of obtaining a gel film by peeling from a support body and heating.

The gel film as used in the present invention means a film containing a partially imidized polyamic acid and a solvent and having a self supporting property. Although the amount of solvent contained in the said gel film is not specifically limited, Usually, what contains a solvent about 1 to 90% with respect to a gel film is used.

In the above cyclic reaction, any of the above-described ring-closing methods may be employed, and the chemical ring-closing method requires a facility in which a ring-closure catalyst and a dehydrating agent are contained in an organic solvent solution of polyamic acid. It can be said that it is a more preferable method from the point which can be obtained.

Specific examples of the ring-closure catalyst used in the present invention include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and beta picoline. Preference is given to using at least one amine selected from amines. As for content of the ring-closure catalyst with respect to polyamic acid, content (mol) / content (mol) of polyamic acid of the ring-closure catalyst is preferably in a range of about 0.5 to 8.

Specific examples of the dehydrating agent used in the present invention include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride and butanoic anhydride, aromatic carboxylic anhydrides such as benzoic anhydride, and the like, and acetic anhydride and / or benzoic anhydride are preferred. Moreover, as for content of the dehydrating agent with respect to polyamic acid, content (mol) / content (mol) of polyamic acid become the range which becomes about 0.1-4. In this case, gelling retardants such as acetylacetone may be used in combination.

The range of about 0.2-3.0 is preferable and, as for the intrinsic viscosity (measured in 25 degreeC sulfuric acid) of the polyimide contained in the said gel film, the range of about 0.8-2.0 is still more preferable.

The said process (c) is a process of extending | stretching the gel film obtained by the said process (b). Although the said extending method is not specifically limited unless the effect of this invention is impaired, It is preferable that it is biaxial stretching in a machine conveyance direction MD and the width direction TD.

Although the order of the said biaxial stretching process is not specifically limited, After extending | stretching (henceforth longitudinal extension) of the machine conveyance direction MD, after extending | stretching of the width direction TD (henceforth lateral) ), Also referred to as drawing). In addition, the process of longitudinal stretching, then the heat treatment, then the lateral stretching, or the longitudinal stretching, and then the lateral stretching in parallel with the heat treatment increases the uniformity of the linear thermal expansion coefficient. More preferable. The heat treatment here is for removing the solvent contained in a gel film and obtaining a polyimide film. In this invention, a heat processing is further performed to the said polyimide film, and a heat processing polyimide film is obtained.

It is preferable to divide | segment extending | stretching (longitudinal drawing) of MD in the said biaxial stretching process in 2 or more steps. Although the total draw ratio of MD is not specifically limited, About 1.04 times or more and about 1.5 times or less are preferable, About 1.05 times or more and about 1.4 times or less are more preferable. In addition, although the extending | stretching temperature of MD is not specifically limited, About 50-100 degreeC is preferable, and about 60 degreeC-90 degreeC is still more preferable. As the pattern of the longitudinal stretching, a method of stretching at a time from the stretching ratio 1 to the above-described stretching ratio, a method of sequentially stretching, a method of stretching gradually at an undetermined magnification, a method of stretching slightly at a predetermined magnification, or a combination of a plurality thereof Etc., and the method of extending | stretching at a fixed magnification especially little by little is preferable.

When heat-processing after the said longitudinal stretching, heating temperature is although it does not specifically limit, The temperature higher than the temperature at the time of extending | stretching MD is preferable. In addition, you may heat-process in multiple steps at different temperature, In this case, it is preferable that the heating temperature of a final stage is temperature higher than the heating temperature of a 1st stage. In the heat treatment, a heating device such as a casting furnace or a heating furnace having a plurality of blocks (regions) having different temperatures can be used. The heat treatment is preferably performed by fixing both ends of the film by a pin type tenter device, a clip type tenter device, a chuck, or the like. By the said heat processing, a solvent can be removed.

When transverse stretching is performed after longitudinal stretching, the gel film stretched in the MD direction is introduced into the tenter device, and both ends of the width direction are gripped in the tenter clip and the like, and travel in the width direction (TD) while traveling with the tenter clip or the like. Stretched. Although it does not specifically limit as a draw ratio (henceforth a lateral stretch ratio) of TD, 1.1 times or more and 2.0 times or less are preferable, and 1.2 times or more and 1.8 times or less are more preferable. It is preferable to set the draw ratio (lateral stretch ratio) of TD higher than the draw ratio (longitudinal stretch ratio) of MD, and specifically 1.10 times or more and 1.50 times or less of the total draw ratio of MD are preferable, and 1.15 times 1.45 times or more is more preferable. By setting the draw ratio of TD high compared with the draw ratio of MD of a film, the film which suppressed the linear thermal expansion coefficient of TD of a film can be obtained, maintaining the linear thermal expansion coefficient approximated to metal in MD of a film. The heat-treated polyimide film of the present invention produced using the film can be preferably used for a flexible printed wiring board and the like.

Although extending | stretching of TD may be performed after the said heat processing, and may be performed before the said heat processing, performing in parallel with the said heat processing is more preferable at the point which improves the uniformity of a linear thermal expansion coefficient. Although the stretching time of TD is not specifically limited, It is about 5 second-about 10 minutes, and 10 second-8 minutes are preferable. As said lateral stretch pattern, the method of extending | stretching at once from the draw ratio 1 to the above-mentioned lateral stretch magnification, the method of sequential stretching, the method of extending | stretching little by little at an undetermined magnification, the method of extending | stretching little by little at a predetermined magnification, or combining these in multiple numbers The method etc. are mentioned, for example. In particular, in the case where the lateral stretching and the multi-step heat treatment are performed in parallel, it is preferable to set the draw ratio of the TD to be the maximum draw ratio at the time of the heat treatment in the first step, and to decrease the draw ratio little by little. Moreover, it is also preferable to set so that the draw ratio of TD may become a maximum draw ratio at the time of the heat processing of a 2nd step or a final stage little by little by increasing the draw ratio of TD after the 1st step heat processing.

The gel film peeled off from the said support body extends in a running direction MD, restrict | limiting a running speed by a rotating roll. Since the rotary roll requires a holding force for regulating the traveling speed of the gel film, the rotary roll may be a nipple roll, a vacuum roll, a multi-stage tension cutting roll, or a pressure reduction suction system formed by combining a metal roll and a rubber roll. It is preferable to use a suction roll or the like.

[Example]

Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

[Production Example 1]

1900.6 kg of dried N, N-dimethylacetamide was placed in a polymerization apparatus equipped with a stirrer, and 12.43 kg (0.115 mmol) of paraphenylenediamine was dissolved therein under stirring. Subsequently, 24.45 kg (0.112 kmol) of pyromellitic dianhydrides were thrown in small amounts, and stirring was continued for 1 hour after completion | finish of addition. Thereafter, 169.17 kg (0.845 kmol) of 4,4'-diaminodiphenyl ether was added thereto, stirred until uniform, and then 56.49 kg (3,3'-4,4'-diphenyltetracarboxylic acid dianhydride) 0.192 kmol) was added and reacted for 1 hour. Subsequently, 143.09 kg (0.656 kmol) of pyromellitic dianhydrides were added to this, and it was further made to react for 1 hour, and the polyamic-acid solution was obtained. This solution was 320 Pa.s viscosity at 20 degreeC. To this polyamic acid solution, 250.0 kg of dried N, N-dimethylacetamide and acetic anhydride were mixed with 2.5 mol and 2.5 mol of pyridine with respect to the polyamic acid unit to prepare a polyamic acid solution. did.

This polyamic acid solution was extruded from a T-die having a mouthpiece slit width of 2.5 mm and a length of 1600 mm, and cast on a metal endless belt at 70 ° C to obtain a self supporting gel film. This gel film was conveyed while extending | stretching 1.15 times in MD direction in the room temperature of 60 degreeC. After holding both ends of the width direction of a gel film with a pin by the pin type | mold tenter apparatus, and extending | stretching by 1.35 times in conveyance and TD direction, it dried at 260 degreeC for 2 minutes, and heat-processed at 340 degreeC for 5 minutes, It cooled at 30 degreeC for 2 minutes, relaxing. Moreover, the edge of the edge part of a film was cut | disconnected conveying, and 3200 m of polyimide films of width 1600mm and 12 micrometers of thickness were extract | collected by cleaning the film surface with a wave cleaner (MODEL SC2202, product made by Hug Electronics). By slitting this with a slit machine, a film roll (hereinafter referred to as PI roll-1) having a width of 510 mm and a length of 300 m was obtained. And the temperature which the change rate of (alpha) _MD of PI roll-1 becomes 25% was 250 degreeC, and the difference of the maximum value and the minimum value of (alpha) _MD which measured 16 points in 30 mm intervals in the width of 510 mm was 18 ppm / degreeC.

[Production Example 2]

The polyamic acid solution prepared in the same manner as in Production Example 1 was extruded from a T die having a slit width of 2.5 mm and a length of 1600 mm of the mouthpiece, and cast on a 58 ° C metal endless belt to obtain a self supporting gel film. This gel film was conveyed while extending | stretching 1.10 times in MD direction in the room temperature of 65 degreeC. While holding both ends of the width direction of a gel film with a pin by the pin type | mold tenter apparatus, and extending | stretching by 1.40 times in conveyance and TD direction, it dries at 260 degreeC for 3 minutes, heat-processes at 340 degreeC for 7.5 minutes, and relaxes in a cooling area, Cooled at 30 ° C. for 1.5 minutes. Moreover, the edge of the edge part of a film was cut | disconnected conveying, and the film surface was cleaned with a wave cleaner (MODEL SC2202, product made by Hug Electronics Co., Ltd.), and 1100 m of polyimide film of width 1585mm and thickness of 25 micrometers was extract | collected. By slitting with a slit machine, a film roll (hereinafter referred to as PI roll-2) having a width of 510 mm and a length of 300 m was obtained. And the temperature which the change rate of (alpha) _MD of PI roll-2 becomes 25% was 250 degreeC, and the difference of the maximum value and the minimum value of (alpha) _MD which measured 16 points in 30 mm intervals within the width of 510 mm was 22 ppm / degreeC.

Example 1

PI roll-1 was continuously sent to the heating apparatus with the delivery roller, and heat-processed for 7 second on the conditions of 10 N / m of tension, and the maximum process temperature of 385 degreeC. As shown in Fig. 1, the heating apparatus used in this embodiment has two heating chambers (hereinafter referred to as heating chamber 1 and heating chamber 2 in turn from the releasing side), and the heating chamber includes a ceramic heater 2, The upper air supply nozzle 3 and the lower air supply nozzle 4 are provided, and the exhaust port is provided in the position shifted from the film processing part in the width direction. After heat processing, it cooled to room temperature, winding up outside the heating apparatus. Both the temperature of the ceramic heater was adjusted to 630 degreeC, and the wind speed was 2.4 m / sec in both the upper and lower sides. The temperature of the air introduced from the upper and lower air supply nozzles was 130 ° C. for the heating chamber 1 and 150 ° C. for the heating chamber 2, and a 250-m polyimide film roll was obtained at a delivery speed of 50 m / min. The delivery speed here is corresponded to the traveling speed of the said film. The difference between the maximum value and minimum value of (alpha) _MD which measured 16 points within the width of 510 mm of the obtained film at 30 mm intervals was 9 ppm / degreeC.

[Example 2]

As processing conditions, the 250 m polyimide film roll was obtained by performing the same operation as Example 1 except having changed the temperature of all the ceramic heaters to 580 degreeC, and the maximum processing temperature to 350 degreeC. The difference between the maximum value and minimum value of (alpha) _MD which measured 16 points within the width | variety of 510 mm of the obtained film at 30 mm intervals was 10 ppm / degreeC.

Comparative Example 1

As processing conditions, the 250 m polyimide film roll was obtained by performing the same operation as Example 1 except having changed all the temperature of the ceramic heater to 480 degreeC, and the maximum processing temperature to 280 degreeC. The difference between the maximum value and minimum value of (alpha) _MD which measured 16 points within the width | variety of 510 mm of the obtained film at 30 mm intervals was 20 ppm / degreeC.

Comparative Example 2

As a processing condition, 250 m of polyimide film rolls were made by performing the same operation as Example 1 except having changed the temperature of all the ceramic heaters to 480 degreeC, the maximum processing temperature to 265 degreeC, and delivery speed 100 m / min. Got it. The difference between the maximum value and minimum value of (alpha) _MD which measured 16 points within the width | variety of 510 mm of the obtained film at 30 mm intervals was 23 ppm / degreeC.

Comparative Example 3

As a processing condition, 250 m of polyimide film rolls were obtained by performing the operation similar to Example 1 except having changed all the temperature of a ceramic heater to 680 degreeC and the maximum processing temperature to 420 degreeC. The difference between the maximum value and minimum value of (alpha) _MD which measured 16 points within the width | variety of 510 mm of the obtained film at 30 mm intervals was 17 ppm / degreeC.

[Example 3]

A 250-m polyimide film roll was obtained by performing the same operation as Example 1 except for changing the treatment roll to PI Roll-2 and sending the feed rate at 100 m / min. The difference between the maximum value and minimum value of (alpha) _MD which measured 16 points within the width | variety of 510 mm of the obtained film at 30 mm intervals was 11 ppm / degreeC.

[Table 1]

In the heat-treated polyimide film of Comparative Examples 1 to 3, the difference between the maximum value and the minimum value of α _MD at 16 points measured was 20 ppm / ° C, 23 ppm / ° C, and 17 ppm / ° C, respectively, and α _MD was formed on the film. It was heterogeneous depending on location. On the other hand, in Examples 1-3 of this invention, alpha _MD was uniform regardless of the position on a film, and the high quality heat processing polyimide film by which the nonuniformity was reduced was obtained.

Since the heat-treated polyimide film of the present invention has a uniform α _MD regardless of the position on the film, there is no problem in workability in the laminating method, no warpage occurs, the coefficient of linear expansion after etching is small, and the heat resistance is also high. It is excellent, and the nonuniformity of (alpha) _MD is improved and it is especially useful as a material for flexible printed wiring boards.

1: polyimide film
2: ceramic heater
3: upper air supply nozzle
4: lower air supply nozzle
5: bounce roll
6: heating chamber 1
7: heating chamber 2
8: conveying direction of a polyimide film

Claims (5)

By heat-processing the polyimide film whose temperature of change of the coefficient of linear expansion in a mechanical conveyance direction to 25% is 200 degreeC or more at the temperature of 100 to 150 degreeC higher than the temperature of the rate of change of the said linear expansion coefficient to 25% It is obtained and the heat treatment polyimide film whose difference in average linear expansion coefficient of a machine conveyance direction is 15 ppm / degrees C or less with respect to arbitrary two points. The method of claim 1,
The heat treatment polyimide film whose time of the said heat processing is more than 0 second and 10 second or less. The method according to claim 1 or 2,
The film roll which consists of a heat processing polyimide film of Claim 1 or 2 which is 500 mm or more in width and 50 m or more in length. Including a step of subjecting the polyimide film having a temperature of 200% or more to a temperature at which the rate of change of the linear expansion coefficient in the machine conveyance direction is 25% to a temperature of 100 ° C to 150 ° C higher than the temperature at which the rate of change of the linear expansion coefficient is 25%. Method for producing a heat treated polyimide film. The method of claim 4, wherein
The manufacturing method of the heat processing polyimide film whose time of the said heat processing is more than 0 second and 10 second or less.

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