WO2023249053A1

WO2023249053A1 - Method for producing film

Info

Publication number: WO2023249053A1
Application number: PCT/JP2023/022937
Authority: WO
Inventors: 伝一朗水口; 治美米虫; 洋行涌井; 幸太北村
Original assignee: 東洋紡株式会社
Priority date: 2022-06-23
Filing date: 2023-06-21
Publication date: 2023-12-28
Also published as: TW202400399A

Abstract

[Problem] To provide a method for producing a film such that during the production of the film, no breakage, tearing or anomalies in external appearance are caused to the film not only at the central part of the film but also at both fixed edges of the film or the vicinity thereof. [Solution] This method for producing a film comprises: a step A in which fixtures are set at both edges in the width direction of one surface of a not-yet-heat-treated film, and the not-yet-heat-treated film is fixed in place using the fixtures; a step B in which hot air is blown onto both surfaces of the not-yet-heat-treated film; and a step C in which the not-yet-heat-treated film is conveyed. In the step B, the speed of the hot air blown onto the surface where the fixtures are not set is greater than or equal to the speed of the hot air blown onto the surface where the fixtures are set.

Description

Film manufacturing method

The present invention relates to a method for producing a film.

Traditionally, in the film manufacturing process, tension is applied to the film in the width direction by gripping both ends of the film with multiple pins or clips when transporting, drying, or heat-treating the film. A tenter-type conveying device is known that conveys the object in a state in which the object is held (see, for example, Patent Document 1).

There are several transport methods for tenter-type transport devices. Among these conveyance methods, the pin tenter conveyance device grips the film by piercing both ends of the film with a large number of pins along the flow direction. It has a large number of pins arranged on the sheet. The pin grips and transports the film, but if the tear strength of the film is low, it may break during transport.

In order to solve this problem, it has been proposed to overlap a film with high tear strength as a reinforcing film on the gripping part (end) of a film with low tear strength (see, for example, Patent Document 2).

Special Publication No. 39-29211 Japanese Patent Application Publication No. 11-254521

However, in the method of Patent Document 2, a film with high tear strength is superimposed on a film with low tear strength, so there is a problem that a large amount of raw material is wasted. In addition, when using such a conveying device to apply hot air to the film to advance a chemical reaction or volatilize the solvent, both ends of the film gripped by the pins are blocked by the pin sheets, so the central part is It is difficult for the hot air given to reach the area compared to . For this reason, even if a film with high tear strength is stacked on both ends, an unfinished state of chemical reaction or an undry state will occur near both ends of the film, resulting in breakage or tearing at the gripping part or the vicinity, and abnormal appearance. become. If both ends of the film are broken or torn in this way, the film being transported will come off the pin gripping portion, and the film will remain in the transport device, making it impossible to obtain the desired film. Furthermore, even if such accumulation in the conveying device does not occur, tearing or breaking at both ends of the film makes it difficult to maintain the proper tension of the film, and as a result, wrinkles occur throughout the film, causing damage to the edges. It can also be a cause of other quality deterioration. Furthermore, if tearing or abnormal appearance occurs near both ends of the film, it becomes necessary to cut more to the center when cutting the gripping portion, causing production loss.

Such problems occur in systems where chemical reactions proceed and solvent evaporates simultaneously during transport, such as systems such as polyimide films obtained by heat-treating a polyimide precursor film containing a certain amount of solvent while transporting. Cheap. In particular, in the case of transparent and highly heat-resistant films, it may be necessary to select a molecular structure that is brittle and easy to tear in order to ensure its physical properties, and solving the above problems becomes a bottleneck.

The present invention has been made in view of the above-mentioned problems, and its purpose is to prevent breakage, tearing, and appearance abnormalities at both ends of the film and the vicinity thereof when the film is transported with both ends fixed by a tenter-type transport device. It is an object of the present invention to provide a method for producing a film that can more effectively suppress the occurrence of the problem.

The present inventors have completed the present invention as a result of intensive studies to solve the above problems. That is, the present invention provides the following preferred embodiments.

[1] A method for producing a film, comprising:
Step A of installing fixtures at both ends in the width direction of one side of the film before heat treatment, and fixing the heat treated film with the fixtures;
Step B of blowing hot air onto both sides of the film before heat treatment
Step C of conveying the film before heat treatment
has
The process B is characterized in that the speed of the hot air blown to the surface where the fixing device is not installed is the same as or higher than the speed of the hot air blown to the surface where the fixing device is installed. Production method.
[2] The method for producing a film according to [1], wherein in the step B, the wind speed on the surface where the fixing device is not installed is 1.1 times or more the wind speed on the surface where the fixing device is installed. .
[3] The method for producing a film according to [1] or [2], wherein the fixture is a pin sheet.
[4] The method for producing a film according to any one of [1] to [3], wherein the film is a polyimide film.
[5] The method for producing a film according to [4], wherein the polyimide film is a transparent polyimide film.
[6] A film manufacturing device,
A fixing mechanism A in which fixing tools are installed at both ends in the width direction of one surface of the film before heat treatment, and the heat treated film is fixed with the fixing tools.
Blowing mechanism B blowing hot air to both sides of the film before heat treatment
Conveyance mechanism C that conveys the film before heat treatment
has
The blowing mechanism B is a film characterized in that the speed of the hot air blown to the surface where the fixing device is not installed is the same as or higher than the speed of the hot air blown to the surface where the fixing device is installed. manufacturing equipment.
[7] The production of the film according to [6], wherein the air blowing mechanism B has a wind speed on a surface where the fixing device is not installed is 1.1 times or more as a wind speed on the surface where the fixing device is installed. Device.
[8] The film manufacturing apparatus according to [6] or [7], wherein the fixture is a pin sheet.
[9] The film manufacturing apparatus according to any one of [6] to [8], wherein the film is a polyimide film.
[10] The film manufacturing apparatus according to [9], wherein the polyimide film is a transparent polyimide film.

According to the present invention, it is possible to provide a method for manufacturing a film that does not cause breakage, tearing, or abnormal appearance not only at the center of the film but also at and around both ends where the film is fixed.

If a break or tear occurs at both ends of the film, the film being transported will come off the film fixing structure (for example, a pin), and the film will remain in the transport device, making it impossible to obtain the desired film. Furthermore, even if such accumulation in the conveying device does not occur, tearing or breaking at both ends of the film makes it difficult to maintain the proper tension of the film, and as a result, wrinkles occur throughout the film, causing damage to the edges. It can also be a cause of other quality deterioration. Furthermore, if tearing or abnormal appearance occurs near both ends of the film, it becomes necessary to cut more to the center when cutting the fixing part (grip part), causing production loss.

On the other hand, according to the present invention, film transport defects caused by breakage and tearing of both ends of the film can be suppressed. Furthermore, wrinkles in the center caused by abnormalities at both ends can be suppressed, and a film of stable quality can be provided. Furthermore, since breakage, tearing, and abnormal appearance near both ends of the film can be suppressed, both ends to be cut can be made smaller, and production loss can be reduced. Furthermore, by using the method of the present invention, excessive heat is not applied to the center of the film, so a film of stable quality can be provided without causing abnormalities in the center of the film.

An explanatory diagram schematically showing the state of the film during transport of the present invention An explanatory diagram schematically showing another state of the film during conveyance according to the present invention.In addition, in FIGS. 1 and 2, the hot air is not blown out from three points each at the top and bottom, but is blown out evenly from the entire width direction of the air outlet. ing. In addition, a plurality of air outlets are arranged in the film transport direction.

Hereinafter, embodiments of the present invention will be described. Note that the scope of the present invention is not limited to the embodiments described here, and various changes can be made without departing from the spirit of the present invention.

When manufacturing a film, the film before heat treatment may be passed through a heating furnace to volatilize organic solvents, cause chemical reactions, and improve various physical properties. Here, the film for the purpose of volatilizing the organic solvent is the film before drying, and the film for the purpose of causing a chemical reaction is the precursor film (green film), but in this specification, these are collectively referred to as the film before heat treatment. That's what it means.

When the pre-heat-treated film is passed through a heating furnace in this way, it is necessary to install fixing tools at both ends in the width direction of one side of the pre-heat-treated film, and fix the heat-treated film with the fixing tools (step A). The fixing method is not particularly limited. When heat treatment is performed during transportation, a tenter-type transportation device is generally used. When using a tenter-type conveyance device, it is preferable to fix both ends of the film before heat treatment by piercing a plurality of pins of the pin tenter-type conveyance device. Preferably, the film before heat treatment is fixed only at both ends. By fixing only at both ends, air blowing at a location other than both ends (for example, the center) of the film before heat treatment is not blocked. When heating the film before heat treatment in the tenter-type conveying device, a hot air generation mechanism is often used as the heating source. The hot air generation mechanism blows hot air onto the surface of the film before heat treatment where the fixing device is not installed (e.g., the upper surface of the film before heat treatment) and the surface of the film before heat treatment where the fixer is installed (e.g., the lower surface of the film before heat treatment). and heat it (Step B). By heat treatment, it is possible to volatilize the organic solvent in the film before heat treatment, cause a chemical reaction, and improve various physical properties. It is necessary that the speed of the hot air on the surface of the film before heat treatment on which the fixture is not installed is equal to or higher than the speed of the hot air on the surface where the fixture is installed. Here, blowing hot air onto the film before heat treatment is also referred to as heat treatment.

Next, along with the heat treatment, the film before heat treatment is transported (Step C).

FIG. 1 is an explanatory diagram schematically showing the state of the film before heat treatment during transportation according to the present invention. The film before heat treatment is conveyed from the back side of the page to the front side (or from the front side to the back side). A pin sheet 11 (film fixing device) is installed on the fixing device installation surface (lower surface) of the film 1 before heat treatment, and both ends of the film 1 before heat treatment are attached to pins 11a (film fixing structure) provided on the top surface of the pin sheet 11. ) to fix (grasp) it. Then, in this state, the pre-heat-treated film 1 is heat-treated. The heat treatment is performed using hot air 31 generated from a hot air outlet 21 provided on the non-fixing device installation surface side (upper surface) of the film 1 before heat treatment, and hot air 31 generated from the hot air outlet 21 provided on the non-fixing device installation surface side (lower surface) of the film 1 before heat treatment. This is done by simultaneously blowing hot air 32 generated from a hot air outlet 22 from both upper and lower surfaces of the film 1 before heat treatment. At this time, the hot air 31 is blown onto the pre-heat-treated film 1 without being blocked by the pin sheet 11, but a part of the hot air 32 is blocked by the pin sheet 11 and does not reach the edge 1b of the pre-heat-treated film. . Like the hot air 31, the hot air 32 is blown unobstructed to the central portion 1a of the film before heat treatment. Normally, this would cause the end portion 1b of the film before heat treatment to undergo an incomplete state of chemical reaction or an undried state of the solvent. In addition, if the total amount of hot air 31 and hot air 32 is increased in an attempt to increase the amount of hot air 31 (hot air that is not blocked by pin sheet 11) blown onto the film end 1b before heat treatment, the product may become damaged. Excessive heat is applied to the central portion 1a of the film, causing abnormalities such as clouding, yellowing, and breakage due to excessive drying. However, according to the present invention, by increasing the wind speed of hot air 31 to be the same as or higher than that of hot air 32 without changing the total volume of hot air 31 and hot air 32, hot air 32 (which is blocked by pin sheet 11) This reduces the proportion of hot air (hot air) and increases the proportion of hot air 31 (hot air that is not blocked by the pin sheet 11), making it possible to more efficiently apply hot air to the film edge 1b, thereby improving the quality of the product. The above-mentioned condition at the end portion 1b of the film before heat treatment can be avoided without causing the above-mentioned abnormality in the central portion 1a of the film. In FIG. 1, the hot air outlet 21 side of the film 1 before heat treatment is the non-fixing device installation surface, and the hot air outlet 22 side is the fixing device installation surface.

In the present invention, as shown in FIG. 2, a pin tenter 11 is installed on the upper surface of the film before heat treatment, and both ends of the film 1 before heat treatment are fixed by piercing pins 11a provided on the lower surface of the pin sheet 11. You can. In this case, the wind speed of the hot air 31 on the side of the film 1 before heat treatment where the fixing device is not installed (lower side) is the same as the wind speed of the hot air 32 on the side of the film 1 before heat treatment where the fixing device is installed (the upper side). , make it larger than that. In FIG. 2, the hot air outlet 22 side of the film 1 before heat treatment is the fixture installation surface, and the hot air outlet 21 side is the fixture non-installation surface.

The pin tenter type conveying device generally has a large number of pins arranged on a pin sheet fixed (grasped) by a pair of moving chains arranged parallel to each other. The pins arranged on this pin sheet may be on the upper surface or the lower surface of the pin sheet. The arrangement of the pins is not particularly limited, and conventionally known pins can be used.

It is preferable that the temperature of the hot air blown (blown) on the non-fixing device installation surface and the fixing device installation surface of the film before heat treatment is 80° C. or higher and 500° C. or lower in order to promote solvent volatilization and chemical reactions. The temperature is more preferably 120°C or higher because it is easy to remove the solvent contained in the film before heat treatment, and when the film before heat treatment is a polyimide precursor (polyamic acid), it is easy to imidize (thermal imidization). , more preferably 150°C or higher, particularly preferably 200°C or higher. Further, since damage to the film due to heat can be suppressed, the temperature is more preferably 450°C or lower, still more preferably 400°C or lower, and particularly preferably 380°C or lower. Within the above range, breakage and tearing of the film during transportation is suppressed, and the quality of the film is improved. The hot air temperatures on the fixture-free surface and the fixture-installed surface may be the same or different, but are preferably the same temperature from the viewpoint of simplifying the apparatus. Changes in the temperature of the hot air during film transport are not particularly limited, and the design may be such that multiple heating furnaces are connected to change the temperature of the hot air in stages. It may be designed to gradually rise or fall. When heat treatment is performed in a plurality of heating furnaces, the number of heating furnaces is preferably 2 or more and 10 or less, more preferably 3 or more and 8 or less, and even more preferably 4 or more and 6 or less. By performing heat treatment in multiple heating furnaces, the film before heat treatment can be dried in stages or thermally imidized, thereby improving the quality of the film.

It is preferable that the speed of the hot air blown to the surface of the film before heat treatment on which the fixing device is not installed is 0.5 m/sec or more and 15 m/sec or less. The hot air sufficiently reaches the film before heat treatment, making it easier to remove the solvent contained in the film before heat treatment, and if the film before heat treatment is a polyimide precursor (polyamic acid), it becomes easier to imidize (thermal imidization). Therefore, it is more preferably 1 m/sec or more, still more preferably 1.5 m/sec or more, even more preferably 2 m/sec or more, and particularly preferably 3 m/sec or more. In addition, the speed is preferably 13 m/sec or less, more preferably 12 m/sec or less, and even more preferably 10 m/sec or less, since it can suppress breakage, tearing, pin detachment, etc. due to flapping of the film before heat treatment. .

It is preferable that the speed of the hot air blown onto the fixing device installation surface of the film before heat treatment is 0.4 m/sec or more and 14 m/sec or less. More preferably 0.9 m, since it is easy to remove the solvent contained in the film before heat treatment, and when the film before heat treatment is a polyimide precursor (polyamic acid), it is easy to imidize (thermal imidization). /sec or more, more preferably 1.4 m/sec or more, even more preferably 1.9 m/sec or more. In addition, the speed is preferably 12 m/sec or less, more preferably 11 m/sec or less, and even more preferably 9 m/sec or less, since it can suppress breakage, tearing, pin detachment, etc. due to flapping of the film before heat treatment. .

The speed of the hot air blown to the surface of the pre-heat-treated film on which the fixing device is not installed needs to be the same as or higher than the speed of the hot air blown to the surface where the fixing device is installed. The ratio of wind speeds between the fixture non-installation surface and the fixture installation surface (fixture non-installation surface/fixture installation surface) is preferably greater than 1.0. Preferably, 1. 05 or more, more preferably 1.1 or more. In addition, it is preferably 10 or less because it suppresses the temperature drop in the space on the side where the fixture is installed and the temperature drop in the film itself due to the temperature drop, making it easier to dry the entire film before heat treatment and complete the chemical reaction. , more preferably 5 or less, still more preferably 3 or less.

If the speed of the hot air blown to the surface of the pre-heat-treated film on which the fixing device is not installed is smaller than the speed of the hot air blown to the surface where the fixing device is installed, the proportion of the hot air blocked by the film fixing device increases, and the edge of the film before heat treatment increases. This will reduce the amount of hot air hitting the area. Therefore, the edges of the film before heat treatment require more time to dry and complete the chemical reaction than the center of the film before heat treatment. When only the edges of the film are dry or the chemical reaction is not completed, the edges of the film do not have sufficient strength, and appearance abnormalities such as tearing and elongation may occur starting from the film fixing structure (pin 11a). It may cause If this abnormality occurs significantly, the broken film may get caught in the outlet of the furnace and remain there, making it difficult to transport the film itself. In addition, such abnormal appearance starting from the edges of the film may not be limited to the edges but may extend to the vicinity of the center of the film, causing quality deterioration and production loss.

The residual solvent contained in the heat-treated and dried film is preferably 500 ppm or less, more preferably 200 ppm or less, and still more preferably 100 ppm or less. The smaller the amount of residual solvent, the better; however, from an industrial perspective, it may be 1 ppm or more, and even 10 ppm or more.

The film of the present invention is preferably manufactured by a method in which it is wound up as a long film having a width of 300 mm or more and a length of 10 m or more. Furthermore, the method for fixing both widthwise ends of one side of the film before heat treatment is not particularly limited, and may be held by sticking it into a pin of a pin tenter-type conveyance device, or by holding it with a clip of a clip tenter-type conveyance device. It may also be gripped.

The width of both ends (width of each end) is not particularly limited as long as it can be fixed using a conventionally known tenter-type conveyance device. Specifically, the lower limit is preferably 5 mm or more, more preferably 10 mm or more. Alternatively, the total width of both ends is preferably 0.1% or more of the total width of the film before heat treatment, more preferably 0.5% or more, and still more preferably 1% or more.
Further, the upper limit of the width of both ends (width of each end) is preferably 100 mm or less, more preferably 50 mm or less. Alternatively, the total width of both ends is preferably at most 50% of the total width of the film, more preferably at most 30%, even more preferably at most 10%.

The central part in the width direction of the film before heat treatment is preferably a position 30 to 70% from one end, more preferably 40 to 60% when the full width of the film before heat treatment is 100%. The position is more preferably 45 to 55%.

The transport speed of the film before heat treatment can be appropriately set depending on the heat treatment conditions (hot air temperature, wind speed, etc.). Although it is difficult to determine an appropriate conveying speed strictly because it depends on the length of the heat treatment furnace, if it is slow, there is a risk that productivity will decrease. Preferably it is 0.05 m/min or more, more preferably 0.1 m/min or more.

<Film>
The film of the present invention (film after heat treatment) includes polyimide resins such as polyimide, polyamideimide, polyetherimide, and fluorinated polyimide (e.g., aromatic polyimide resin, alicyclic polyimide resin); polyolefin resins such as polyethylene and polypropylene. ; Copolymerized polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate (e.g., fully aromatic polyesters, semi-aromatic polyesters); Copolymerized (meth)acrylates represented by polymethyl methacrylate; Polycarbonates; Polyamides ; polysulfone; polyethersulfone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenol; polyarylate; polyphenylene sulfide; polyphenylene oxide; polystyrene.

Since the above-mentioned film is premised on being suitably used in a process involving heat treatment at 250° C. or higher, there are a limited number of polymer films that can actually be used among the exemplified polymer films. Among the above films, preferred are films using so-called super engineering plastics, more specifically polyimide resins, polyamide resins, polyamideimide resins, and azole resins. Particularly preferred specific examples include aromatic polyimide film, aromatic amide film, aromatic amide-imide film, aromatic benzoxazole film, aromatic benzothiazole film, aromatic benzimidazole film, and the like.

The film before heat treatment of the present invention is a film containing an organic solvent in the film (pre-drying film), a film before chemical reaction (precursor film), or a precursor film containing an organic solvent (dried precursor film). ) etc.
The organic solvent content of the film before heat treatment is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass, since both ends of the film before heat treatment can be fixed (held) and transported. % or less. Further, from the viewpoint of manufacturing efficiency and cost, the content is preferably 10% by mass or more, more preferably 15% by mass or more, and still more preferably 20% by mass or more.

The details of a polyimide resin film (sometimes referred to as a polyimide film), which is an example of the film, will be described below. Generally, polyimide resin films are produced by applying a polyamic acid (polyimide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent to a support for polyimide film production, and drying it to form a green film (hereinafter referred to as green film). (also referred to as a "polyamic acid film"), and is obtained by further heat-treating the green film at a high temperature on a support for producing a polyimide film or in a state peeled from the support to perform a dehydration ring-closing reaction. This polyamic acid film is a polyimide precursor film.

Application of polyamic acid (polyimide precursor, hereinafter also referred to as polyamic acid) solution can be performed using, for example, spin coating, doctor blade, applicator, comma coater, screen printing method, slit coating, reverse coating, dip coating, curtain coating, Conventionally known solution coating means such as slit die coating can be used as appropriate.

The diamines constituting the polyamic acid are not particularly limited, and aromatic diamines, aliphatic diamines, alicyclic diamines, etc. commonly used in polyimide synthesis can be used. From the viewpoint of heat resistance, aromatic diamines are preferred. Diamines may be used alone or in combination of two or more.

The diamines are not particularly limited, and include, for example, oxydianiline (bis(4-aminophenyl) ether), paraphenylenediamine (1,4-phenylenediamine), and the like.

Tetracarboxylic acids constituting polyamic acids include aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), and alicyclic tetracarboxylic acids that are commonly used in polyimide synthesis. Acids (including their acid anhydrides) can be used. When these are acid anhydrides, the number of anhydride structures in the molecule may be one or two, but those having two anhydride structures (dianhydride) are preferable. good. Tetracarboxylic acids may be used alone or in combination of two or more.

The tetracarboxylic acid is not particularly limited and includes, for example, pyrolimet dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the like.

The polyimide film may be a transparent polyimide film.

A colorless and transparent polyimide, which is an example of the film, will be explained. Hereinafter, to avoid complexity, it will also be simply referred to as transparent polyimide. Regarding the transparency of the transparent polyimide, it is preferable that the total light transmittance is 75% or more. It is more preferably 80% or more, still more preferably 83% or more, even more preferably 84% or more, particularly preferably 85% or more. The upper limit of the total light transmittance of the transparent polyimide is not particularly limited, but for use as a flexible electronic device, it is preferably 98% or less, more preferably 97% or less. The colorless transparent polyimide in the present invention is preferably a polyimide having a total light transmittance of 75% or more.

Aromatic tetracarboxylic acids for obtaining colorless and highly transparent polyimide include 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid, 4,4'-oxydiphthalic acid, and bis(1,3- dioxo-1,3-dihydro-2-benzofuran-5-carboxylic acid) 1,4-phenylene, bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)benzene-1,4 -dicarboxylate, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzene-1,4-diyloxy)]dibenzene- 1,2-dicarboxylic acid, 3,3',4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis (Toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3-oxo-1,3-dihydro-2-benzofuran-1,1-diyl)bis(1, 4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2-benzofuran-1,1- diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-oxo-1,3-dihydro-2- benzofuran-1,1-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-) 1,1-dioxide-3,3-diyl)bis(benzene-1,4-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-benzophenonetetracarboxylic acid, 4,4'-[(3H -2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(toluene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[(3H- 2,1-Benzoxathiol-1,1-dioxide-3,3-diyl)bis(1,4-xylene-2,5-diyloxy)]dibenzene-1,2-dicarboxylic acid, 4,4'-[ 4,4'-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]dibenzene-1,2-dicarvone Acid, 4,4'-[4,4'-(3H-2,1-benzoxathiol-1,1-dioxide-3,3-diyl)bis(naphthalene-1,4-diyloxy)]dibenzene-1 , 2-dicarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-benzophenone tetracarboxylic acid, 3,3',4,4'-diphenylsulfone tetracarboxylic acid acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, pyromellitic acid, 4,4'-[spiro(xanthene-9,9') -fluorene)-2,6-diylbis(oxycarbonyl)]diphthalic acid, 4,4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]diphthalic acid, etc. Examples include tetracarboxylic acids and their acid anhydrides. Among these, dianhydrides having two acid anhydride structures are preferred, particularly 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, Acid dianhydrides are preferred. Incidentally, the aromatic tetracarboxylic acids may be used alone or in combination of two or more kinds. When heat resistance is important, the amount of copolymerized aromatic tetracarboxylic acids is preferably 50% by mass or more of the total tetracarboxylic acids, more preferably 60% by mass or more, and still more preferably 70% by mass. The content is more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

Examples of alicyclic tetracarboxylic acids include 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclohexanetetracarboxylic acid, 1 , 2,4,5-cyclohexanetetracarboxylic acid, 3,3',4,4'-bicyclohexyltetracarboxylic acid, bicyclo[2,2,1]heptane-2,3,5,6-tetracarboxylic acid, Bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic acid, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid, tetrahydroanthracene -2,3,6,7-tetracarboxylic acid, tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid, decahydronaphthalene-2 , 3,6,7-tetracarboxylic acid, decahydro-1,4:5,8-dimethanonaphthalene-2,3,6,7-tetracarboxylic acid, decahydro-1,4-ethano-5,8-methano Naphthalene-2,3,6,7-tetracarboxylic acid, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetra Carboxylic acid (also known as "norbornane-2-spiro-2'-cyclopentanone-5'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid"), methylnorbornane- 2-spiro-α-cyclopentanone-α'-spiro-2''-(methylnorbornane)-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclohexanone- α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid (also known as "norbornane-2-spiro-2'-cyclohexanone-6'-spiro-2''-norbornane -5,5'',6,6''-tetracarboxylic acid''), methylnorbornane-2-spiro-α-cyclohexanone-α'-spiro-2''-(methylnorbornane)-5,5'', 6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclopropanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane -2-spiro-α-cyclobutanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloheptanone-α' -spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclooctanone-α'-spiro-2''-norbornane-5, 5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclononanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid , norbornane-2-spiro-α-cyclodecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cycloundecanone- α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclododecanone-α'-spiro-2''-norbornane- 5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-cyclotridecanone-α'-spiro-2''-norbornane-5,5'',6,6'' -tetracarboxylic acid, norbornane-2-spiro-α-cyclotetradecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro -α-cyclopentadecanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclopentanone)- α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic acid, norbornane-2-spiro-α-(methylcyclohexanone)-α'-spiro-2''-norbornane Examples include tetracarboxylic acids such as -5,5'',6,6''-tetracarboxylic acid, and acid anhydrides thereof. Among these, dianhydrides having two acid anhydride structures are preferred, particularly 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclohexanetetracarboxylic dianhydride. Acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride is preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride Acid dianhydride is more preferred, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride is even more preferred. Note that these may be used alone or in combination of two or more. When emphasis is placed on transparency, the amount of copolymerized alicyclic tetracarboxylic acids is, for example, preferably 50% by mass or more of the total tetracarboxylic acids, more preferably 60% by mass or more, and still more preferably 70% by mass. % or more, still more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may even be 100% by mass.

Examples of tricarboxylic acids include aromatic tricarboxylic acids such as trimellitic acid, 1,2,5-naphthalene tricarboxylic acid, diphenyl ether-3,3',4'-tricarboxylic acid, and diphenylsulfone-3,3',4'-tricarboxylic acid. acids, or hydrogenated products of the above aromatic tricarboxylic acids such as hexahydrotrimellitic acid, alkylenes such as ethylene glycol bis trimellitate, propylene glycol bis trimellitate, 1,4-butanediol bis trimellitate, and polyethylene glycol bis trimellitate. Examples include glycol bistrimelitate, and monoanhydrides and esterified products thereof. Among these, monoanhydrides having one acid anhydride structure are preferred, and trimellitic anhydride and hexahydrotrimellitic anhydride are particularly preferred. Incidentally, these may be used alone or in combination.

Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, 4,4'-oxydibenzenecarboxylic acid, or the above-mentioned aromatic dicarboxylic acids such as 1,6-cyclohexanedicarboxylic acid. Hydrogenates of oxalic acid, succinic acid, glutaric acid, adipic acid, heptanedioic acid, octanedioic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, 2-methylsuccinic acid, and acid chlorides thereof Alternatively, examples include esterified products. Among these, aromatic dicarboxylic acids and hydrogenated products thereof are preferred, with terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzenecarboxylic acid being particularly preferred. Note that dicarboxylic acids may be used alone or in combination.

Diamines or isocyanates for obtaining colorless and highly transparent polyimides are not particularly limited, and include aromatic diamines, aliphatic diamines, and alicyclic diamines commonly used in polyimide synthesis, polyamide-imide synthesis, and polyamide synthesis. diisocyanates, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. can be used. From the viewpoint of heat resistance, aromatic diamines are preferred, and from the viewpoint of transparency, alicyclic diamines are preferred. Further, when aromatic diamines having a benzoxazole structure are used, it becomes possible to exhibit high elastic modulus, low thermal shrinkage, and low coefficient of linear expansion as well as high heat resistance. Diamines and isocyanates may be used alone or in combination of two or more.

Examples of aromatic diamines include 2,2'-dimethyl-4,4'-diaminobiphenyl, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis (4-amino-2-trifluoromethylphenoxy)benzene, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 4, 4'-bis(3-aminophenoxy)biphenyl, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy) phenyl] sulfone, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3 -hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4-amino-N-(4-aminophenyl)benzamide, 3,3' -diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2'-trifluoromethyl-4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4' -diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)phenyl]ethane, 1, 2-bis[4-(4-aminophenoxy)phenyl]ethane, 1,1-bis[4-(4-aminophenoxy)phenyl]propane, 1,2-bis[4-(4-aminophenoxy)phenyl] Propane, 1,3-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 1,1-bis[4-(4-amino) phenoxy)phenyl]butane, 1,3-bis[4-(4-aminophenoxy)phenyl]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4- (4-aminophenoxy)phenyl]butane, 2,3-bis[4-(4-aminophenoxy)phenyl]butane, 2-[4-(4-aminophenoxy)phenyl]-2-[4-(4- aminophenoxy)-3-methylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3-methylphenyl]propane, 2-[4-(4-aminophenoxy)phenyl]-2-[ 4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4-(4-aminophenoxy)-3,5-dimethylphenyl]propane, 2,2-bis[4- (4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 1,4-bis(3-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene , 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(4-amino) phenoxy)phenyl] sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[ 4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4-aminophenoxy)benzoyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzoyl]benzene, 1, 4-bis[4-(3-aminophenoxy)benzoyl]benzene, 4,4'-bis[(3-aminophenoxy)benzoyl]benzene, 1,1-bis[4-(3-aminophenoxy)phenyl]propane , 1,3-bis[4-(3-aminophenoxy)phenyl]propane, 3,4'-diaminodiphenyl sulfide, 2,2-bis[3-(3-aminophenoxy)phenyl]-1,1,1 , 3,3,3-hexafluoropropane, bis[4-(3-aminophenoxy)phenyl]methane, 1,1-bis[4-(3-aminophenoxy)phenyl]ethane, 1,2-bis[4 -(3-aminophenoxy)phenyl]ethane, bis[4-(3-aminophenoxy)phenyl]sulfoxide, 4,4'-bis[3-(4-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis [3-(3-aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzophenone, 4,4'-bis[4-(4- Amino-α,α-dimethylbenzyl)phenoxy]diphenylsulfone, bis[4-{4-(4-aminophenoxy)phenoxy}phenyl]sulfone, 1,4-bis[4-(4-aminophenoxy)phenoxy-α , α-dimethylbenzyl]benzene, 1,3-bis[4-(4-aminophenoxy)phenoxy-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-trifluoro) methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-fluorophenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-( 4-Amino-6-methylphenoxy)-α,α-dimethylbenzyl]benzene, 1,3-bis[4-(4-amino-6-cyanophenoxy)-α,α-dimethylbenzyl]benzene, 3,3 '-Diamino-4,4'-diphenoxybenzophenone, 4,4'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'-diphenoxybenzophenone, 3,3'- Diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3'-diamino -4,4'-Dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'-diamino-4 -Biphenoxybenzophenone, 4,4'-diamino-5-biphenoxybenzophenone, 3,4'-diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl)benzene, 1,4-bis(3-amino-4-phenoxybenzoyl)benzene, 1,3-bis(4-amino-5-phenoxybenzoyl)benzene, 1,4- Bis(4-amino-5-phenoxybenzoyl)benzene, 1,3-bis(3-amino-4-biphenoxybenzoyl)benzene, 1,4-bis(3-amino-4-biphenoxybenzoyl)benzene, 1 , 3-bis(4-amino-5-biphenoxybenzoyl)benzene, 1,4-bis(4-amino-5-biphenoxybenzoyl)benzene, 2,6-bis[4-(4-amino-α, α-dimethylbenzyl)phenoxy]benzonitrile, 4,4'-[9H-fluorene-9,9-diyl]bisaniline (also known as "9,9-bis(4-aminophenyl)fluorene"), spiro(xanthene-9 ,9'-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(xanthene-9,9'-fluorene)-2,6-diylbis(oxycarbonyl)]bisaniline, 4 , 4'-[spiro(xanthene-9,9'-fluorene)-3,6-diylbis(oxycarbonyl)]bisaniline, and the like. Further, some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine may be substituted with a halogen atom, an alkyl group or alkoxyl group having 1 to 3 carbon atoms, or a cyano group, and further, Part or all of the hydrogen atoms of the alkyl group or alkoxyl group of ~3 may be substituted with a halogen atom. Further, the aromatic diamines having the benzoxazole structure are not particularly limited, and examples thereof include 5-amino-2-(p-aminophenyl)benzoxazole, 6-amino-2-(p-aminophenyl)benzoxazole, Oxazole, 5-amino-2-(m-aminophenyl)benzoxazole, 6-amino-2-(m-aminophenyl)benzoxazole, 2,2'-p-phenylenebis(5-aminobenzoxazole), 2 , 2'-p-phenylenebis(6-aminobenzoxazole), 1-(5-aminobenzoxazolo)-4-(6-aminobenzoxazolo)benzene, 2,6-(4,4'-diamino) diphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole , 2,6-(3,4'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3,4'-diaminodiphenyl)benzo[1,2 -d:4,5-d']bisoxazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,4-d']bisoxazole, 2,6-(3 , 3'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisoxazole, and the like. Among these, in particular, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 4-amino-N-(4-aminophenyl)benzamide, 4,4'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone is preferred. Incidentally, the aromatic diamines may be used alone or in combination.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propyl Cyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, Examples include 1,4-diamino-2-tert-butylcyclohexane and 4,4'-methylenebis(2,6-dimethylcyclohexylamine). Among these, 1,4-diaminocyclohexane and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-diaminocyclohexane is more preferred. Incidentally, the alicyclic diamines may be used alone or in combination.

Examples of diisocyanates include diphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2'- or 5,3' - or 6,2'- or 6,3'-dimethyldiphenylmethane-2,4'-diisocyanate, 3,2'- or 3,3'- or 4,2'- or 4,3'- or 5,2 '-or 5,3'-or 6,2'-or 6,3'-diethyldiphenylmethane-2,4'-diisocyanate, 3,2'-or 3,3'-or 4,2'-or 4, 3'- or 5,2'- or 5,3'- or 6,2'- or 6,3'-dimethoxydiphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3, 3'-diisocyanate, diphenylmethane-3,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, benzophenone-4,4'-diisocyanate, diphenylsulfone-4,4'-diisocyanate, tolylene-2,4-diisocyanate, Tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-(2,2bis(4-phenoxyphenyl)propane) diisocyanate, 3, 3'- or 2,2'-dimethylbiphenyl-4,4'-diisocyanate, 3,3'- or 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4, Aromatic diisocyanates such as 4'-diisocyanate, 3,3'-diethoxybiphenyl-4,4'-diisocyanate, and diisocyanates obtained by hydrogenating any of these (e.g., isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate) and the like. Among these, diphenylmethane-4,4'-diisocyanate, tolylene-2,4-diisocyanate, tolylene-2,6-diisocyanate, 3,3'- Dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 1,4-cyclohexane diisocyanate are preferred. Note that the diisocyanates may be used alone or in combination.

The solvent may be any solvent as long as it can dissolve polyimide or a precursor of polyimide, and aprotic polar solvents and the like can be suitably used. For example, N,N-dilower alkylcarboxylamides such as N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide, N-methyl-2-pyrrolidone , N-ethyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfone, 1,3-dimethyl-2-imidazolidinone, γ-butyrolactone, diglyme, m-cresol, hexamethylphosphoramide, N-acetyl-2-pyrrolidone , hexamethylphosphoramide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, p-chlorophenol and the like. Note that the solvent may be a mixture of two or more kinds.

The thickness of the film is preferably 3 μm or more, more preferably 7 μm or more, even more preferably 14 μm or more, and even more preferably 20 μm or more. The upper limit of the thickness of the film is not particularly limited, but in order to use it as a flexible electronic device, it is preferably 250 μm or less, more preferably 100 μm or less, and still more preferably 50 μm or less.

When the film is a transparent polyimide film, its yellowness index (hereinafter also referred to as "yellow index" or "YI") is preferably 10 or less, more preferably 7 or less, and still more preferably 5 or less. Yes, and even more preferably 3 or less. The lower limit of the yellowness index of the transparent polyimide is not particularly limited, but in order to use it as a flexible electronic device, it is preferably 0.1 or more, more preferably 0.2 or more, and still more preferably 0.3 or more. It is.

The film is preferably obtained in the form of a rolled film having a width of 300 mm or more and a length of 10 m or more at the time of manufacture, and is in the form of a rolled film wound around a winding core. is more preferable. When the film is wound into a roll, it becomes easy to transport the film in the form of a roll.

In the above film, in order to ensure ease of handling and productivity, approximately 0.03 to 3% by mass of lubricant (particles) with a particle size of approximately 10 to 1000 nm is added to the film surface. It is preferable to provide fine irregularities to ensure slipperiness. The particle size of the lubricant is preferably 20 to 500 nm, more preferably 30 to 300 nm, and even more preferably 50 to 200 nm. By setting the particle size of the lubricant to 10 nm or more, sufficient slipperiness can be achieved with respect to the amount added. Furthermore, by setting the particle size of the lubricant to 1000 nm or less, problems such as a decrease in mechanical strength and clouding of the film can be reduced.

The film manufacturing apparatus of the present invention includes:
A fixing mechanism A in which fixing tools are installed at both ends in the width direction of one surface of the film before heat treatment, and the heat treated film is fixed with the fixing tools.
Blowing mechanism B blowing hot air to both sides of the film before heat treatment
Conveyance mechanism C that conveys the film before heat treatment
has
The blowing mechanism B is manufactured in such a manner that the speed of hot air blown to a surface where no fixture is installed is the same as or higher than the speed of hot air blown to a surface where a fixture is installed. It is a device.
The film and mechanisms A to C in the manufacturing apparatus have the same meaning as described in the film manufacturing method.

Hereinafter, the present invention will be explained in detail using Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

<Synthesis Example 1 (Preparation of polyamic acid solution A)>
After replacing the inside of the reaction vessel equipped with a nitrogen introduction tube, a reflux tube, and a stirring bar with nitrogen, 33.36 parts by mass of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), A dispersion of 270.37 parts by mass of N,N-dimethylacetamide (DMAC) and colloidal silica dispersed in dimethylacetamide ("Snowtex (registered trademark) DMAC-ST" manufactured by Nissan Chemical Industries) was prepared by dispersing silica into polyamide. The total amount of polymer solids in the acid solution was added to be 0.15% by mass and completely dissolved, and then 9.81 parts by mass of 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA ), 11.34 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), and 4.85 parts by mass of 4,4'-oxydiphthalic anhydride (ODPA). After adding the solid in portions, the mixture was stirred at room temperature for 24 hours. Thereafter, 165.7 parts by mass of DMAc was added and diluted to form a polyamic acid solution A (PAA-A) with a solid content of 18 mass% and a reduced viscosity of 2.7 dl/g (TFMB//molar ratio of CBDA/BPDA/ODPA= 1.00//0.48/0.37/0.15).

<Synthesis Example 2 (Preparation of polyamic acid solution B)>
While passing nitrogen through a reactor equipped with a nitrogen introduction tube and a stirring blade, 3.16 parts by mass of pyromellitic dianhydride (PMDA) and 3,3',4,4'-biphenyltetracarboxylic dianhydride ( Add 2.84 parts by mass of BPDA), 7.73 parts by mass of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), and add N,N-dimethylacetamide (DMAc, 77.8 parts by mass). Parts by mass), a dispersion of colloidal silica (lubricant) dispersed in dimethylacetamide (Snowtex (registered trademark) DMAC-ST-ZL, manufactured by Nissan Chemical Industries), colloidal silica (lubricant) dispersed in polyamic acid solution Polyamic acid solution B (PAA-B) (TFMB//PMDA/BPDA) was obtained by adding it to 0.15% by mass based on the total polymer solid content and stirring at 25°C for 24 hours. Ta.

Example 1
The obtained polyamic acid solution A was applied onto the non-slip surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) using a comma coater so that the final film thickness was 20 μm. This was dried at 90°C for 15 minutes. The polyamic acid film that had obtained self-supporting properties after drying was peeled off from the A4100 film used as a support to obtain a polyamic acid film (film before heat treatment). Next, a pin tenter 11 (film fixing device) was installed at the end of the lower surface of the film before heat treatment so that the pin 11a (film fixing structure) faced upward, and the end of the film before heat treatment was fixed by inserting it into the pin. . Next, the pin sheet interval was adjusted so that the film before heat treatment would not break, and the film was conveyed at 250°C for 3 minutes from the upper air outlet to the surface where the fixture was not installed, and from the lower air outlet to the surface where the fixture was installed. , 3 minutes at 290° C., 3 minutes at 340° C., and 3 minutes at 350° C. by blowing hot air to advance the imidization reaction. At this time, a hot air outlet was installed at a location 175 mm above and below the passing position of the film before heat treatment in each temperature zone, and the air velocity was 3.8 m/min from this upper outlet (in the direction of the surface where the film fixing device was not installed). Hot air at a velocity of 3.6 m/sec was supplied from the lower outlet (in the direction of the film fixture installation surface). Thereafter, the film was cooled to room temperature for 2 minutes, and portions with poor flatness at both ends of the film were cut off using a slitter, and rolled up into a roll to obtain 100 m of polyimide film with a width of 500 mm.

Examples 2-4
The resins used and the manufacturing conditions were as shown in Table 1, and the same procedures as in Example 1 were performed to obtain polyimide films.

Comparative examples 1-2
The resins used and the manufacturing conditions were as shown in Table 1, and the same procedures as in Example 1 were performed to obtain polyimide films.

<Outlet wind speed measurement>
A heat treatment furnace at room temperature was set to send air at room temperature, and measurement was performed using an anemometer (ANEMOMASTER: MODEL 6003) at the hot air outlet.

<Film appearance (edge)>
The state of the film before heat treatment during transport in the furnace and the state of the end portion (fixed portion) of the film after heat treatment were visually checked and evaluated. Evaluation was performed in the following three stages.
〇: There is no problem with film transport, and the film can be maintained properly stretched. △: There is no problem with film transport, but the film cannot be maintained properly stretched. ×: Separated or hanging due to breakage or tearing. The film comes into contact with the inner wall of the furnace and cannot be transported.

<Film appearance (center)>
The entire remaining portion after cutting the fixed portion was visually evaluated for abnormalities such as breaks, tears, and wrinkles. The evaluation was performed in the following two stages.
〇: There is no abnormality such as breakage, tearing, wrinkles, etc. in any part other than the film end (fixed part) ×: There is no abnormality such as breakage, tear, wrinkle, etc. in any part other than the film end (fixed part) can be seen

<Total light transmittance>
The total light transmittance (TT) of the film was measured using HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). A D65 lamp was used as a light source. The arithmetic mean value of the five measured values obtained by unwinding a roll of film by 2 m, cutting out five 50 mm square films, and performing one measurement on each film was used.

<Film thickness>
The thickness of the film was measured using a film thickness measuring device HKT-1216 (manufactured by Marl Corporation). The film was rolled up into a roll, and the film was unwound by 2.5 m, and the full width was measured at 2 cm intervals inward from any one end of the film, and the average of the measurements was taken as the thickness of the film.

<YI>
Using a color meter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source, the tristimulus XYZ values of the film were measured according to ASTM D1925, and the yellowness index (YI) was calculated using the following formula. The arithmetic mean value of the five measured values obtained by unwinding a roll of film by 3 m, cutting out five 50 mm square films, and performing one measurement on each film was used.
YI=100×(1.28X-1.06Z)/Y

<Tg (glass transition temperature)>
The glass transition temperature was determined by cutting out a sheet of 5 mm x 20 mm from the center of the width of a 3.5 m roll of film, and using a dynamic viscoelasticity measuring device (DMA Q800 manufactured by TA Instruments). ), measurement was performed from 30° C. to 450° C. at a heating rate of 5° C./min and a frequency of 10 Hz, and the temperature at which the change in elastic modulus (mechanical tan δ) was maximum was defined as the glass transition temperature. Detailed measurement conditions are as follows.
Measurement mode: DMA Multi-Frequency-strain Tenshio
n film/Rectangular
Strain: 0.1%
Preload force: 0.02N
Force track: 125%
Poisson's ratio: 0.440

<CTE (coefficient of linear thermal expansion)>
One film of size 20mm x 2mm with the long side in the flow direction (MD direction) at the time of coating and one film in the width direction (TD direction) from the center part in the width direction after unwinding 4m from the rolled film. Cut out one piece of film with a size of 20 mm x 2 mm as the long side, and measure the expansion and contraction rate of each film under the following conditions. Measure the expansion/contraction rate/temperature, perform this measurement up to 300°C, calculate the average value of all measured values as CTE, and further compare the calculation results for the film whose long side is in the MD direction and the calculation result for the film whose long side is in the TD direction. The average value of the calculation results was determined.
Equipment name: TMA4000S manufactured by MAC Science
Sample length: 20mm
Sample width: 2mm
Heating start temperature: 25℃
Heating end temperature: 300℃
Temperature increase rate: 5℃/min
Atmosphere: argon

The films obtained in the above Examples and Comparative Examples were evaluated in terms of film appearance (center and edges), YI, Tg, and CTE, and the results are shown in Table 1 below.

INDUSTRIAL APPLICABILITY The present invention can provide a film that does not cause breakage, tearing, or abnormal appearance not only at the center of the film but also at and around both ends where the film is fixed, and is suitable for, for example, flexible electronic devices. Applicable.

1 Film (film before heat treatment)
1a Film center part 1b Film end part 11 Pin sheet (film fixing tool)
11a Pin (film fixing structure)
21 Hot air outlet on the side where the film fixing device is not installed 22 Hot air outlet on the side where the film fixing device is installed 31 Hot air blowing on the side where the film fixing device is not installed 32 Hot air outlet on the side where the film fixing device is installed Hot air blowing on the surface where it is installed

Claims

A method for producing a film, the method comprising:
Step A of installing fixtures at both ends in the width direction of one side of the film before heat treatment, and fixing the heat treated film with the fixtures;
Step B of blowing hot air onto both sides of the film before heat treatment
Step C of conveying the film before heat treatment
has
The process B is characterized in that the speed of the hot air blown to the surface where the fixing device is not installed is the same as or higher than the speed of the hot air blown to the surface where the fixing device is installed. Production method.
The method for producing a film according to claim 1, wherein in the step B, the wind speed on the surface where the fixing device is not installed is more than 1.0 times the wind speed on the surface where the fixing device is installed.
The method for producing a film according to claim 1 or 2, wherein the fixture is a pin sheet.
The method for producing a film according to claim 1 or 2, wherein the film is a polyimide film.
The method for producing a film according to claim 4, wherein the polyimide film is a transparent polyimide film.
A film manufacturing device,
A fixing mechanism A in which fixing tools are installed at both ends in the width direction of one surface of the film before heat treatment, and the heat treated film is fixed with the fixing tools.
Blowing mechanism B blowing hot air to both sides of the film before heat treatment
Conveyance mechanism C that conveys the film before heat treatment
has
The blowing mechanism B is a film characterized in that the speed of the hot air blown to the surface where the fixing device is not installed is the same as or higher than the speed of the hot air blown to the surface where the fixing device is installed. manufacturing equipment.