TW202400399A - Method for producing film - Google Patents

Abstract

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. 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 thin film.

Conventionally, in the film manufacturing process, a tenter-type conveying device has been known, which holds both ends of the film in the width direction with a plurality of needles and clamps when the film is conveyed, dried, heat treated, etc. , and the film is conveyed while applying tension in the width direction (for example, see Patent Document 1).

There are several conveying methods for tenter-type conveying devices. Among these conveying methods, a pin-comb tenter type conveying device that holds the film by inserting both ends of the film onto a plurality of needles along the flow direction has a plurality of needles, and the plurality of needles are equipped with It is located on a needle plate held by a pair of moving chains arranged parallel to each other. Although the film is held and transported by the needle, if the tear strength of the film is low, the film may break during transportation.

In order to solve this problem, it has been proposed to overlap a film with high tear strength as a reinforcing film at the holding portion (end portion) of a film with low tear strength (for example, see Patent Document 2). [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. Sho 39-29211 [Patent Document 2] Japanese Patent Application Publication No. 11-254521

[Problem to be solved by the invention]

However, the method of Patent Document 2 involves laminating a film with high tear strength on a film with low tear strength, so there is a problem of increased waste of raw materials. In addition, when such a conveying device is used to blow hot air onto the film to carry out chemical reactions and evaporate solvents, the needle plates block the hot air at both ends of the film held by the needles, so the hot air supplied becomes stronger than the central part. Hard to reach. Therefore, even if a film with high tear strength is overlapped at both ends, an unfinished state of chemical reaction and an undried state will still occur near both ends of the film, resulting in breaks, cracks, and abnormal appearance at and near the gripping portion. . If breaks or cracks occur at both ends of the film in this way, the film being conveyed will be separated from the needle holding portion, and the film will remain in the conveying device, making it impossible to obtain the intended film. In addition, even if stagnation does not occur in such a conveying device, cracks and breaks at both ends of the film will still make it difficult to maintain the film in a properly opened state. As a result, the entire film will become wrinkled, other than at the ends, etc. Causes of quality degradation. Furthermore, if cracks or abnormal appearance occur near both ends of the film, the gripping portion must be cut closer to the center, causing production losses.

Such problems are likely to occur in systems where chemical reactions and solvent volatilization occur simultaneously during transportation, such as polyimide films obtained by heat treatment while conveying a polyimide precursor film containing a certain amount of solvent. system. In particular, for transparent and highly heat-resistant films, a molecular structure that is brittle and easy to tear may have to be selected in order to ensure its physical properties. Solving the above problems becomes a bottleneck.

The present invention was completed in view of the above-mentioned problems, and its object is to provide a method that can more effectively suppress breakage at both ends of the film and its vicinity when both ends of the film are fixed and conveyed by a tenter-type conveying device. , cracks and abnormal appearance of the film. [Means used to solve problems]

The present inventors conducted careful research to solve the aforementioned problems, and as a result completed the present invention. That is, the present invention provides the following suitable aspects.

[1] A method for manufacturing a thin film, which is a method for manufacturing a thin film, which has: Step A, placing fixing members on both ends in the width direction of one side of the film before heat treatment, and fixing the heat-treated film with the fixing members, Step B, blow hot air on both sides of the film before heat treatment, Step C, transporting the aforementioned film before heat treatment, The wind speed of the hot air blown to the surface without the fixing parts in the aforementioned step B is the same as or greater than the wind speed of the hot air blown to the surface with the fixing parts. [2] The method for manufacturing a film as described in [1], wherein the wind speed on the side where the fixing member is not provided in step B is 1.1 times or more of the wind speed on the side where the fixing member is provided. [3] The method for manufacturing a film according to [1] or [2], wherein the fixing member is a needle plate. [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 thin film manufacturing device, which is a thin film manufacturing device having: The fixing mechanism A arranges fixing members at both ends in the width direction of one side of the film before heat treatment, and fixes the heat-treated film with the fixing members, The air blowing mechanism B blows hot air to both sides of the film before heat treatment. The conveying mechanism C conveys the aforementioned film before heat treatment, The wind speed of the hot air blown by the aforementioned air blowing mechanism B to the surface without the fixing parts is the same as or greater than the wind speed of the hot air blown to the surface with the fixing parts. [7] The film manufacturing apparatus according to [6], wherein the wind speed on the side of the air blower (B) without the fixing member is 1.1 times or more of the wind speed on the side where the fixing member is provided. [8] The film manufacturing device according to [6] or [7], wherein the fixing member is a needle plate. [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. [Effects of the invention]

According to the present invention, it is possible to provide a method for producing a film in which breakage, cracks, and appearance abnormalities do not occur not only in the central portion of the film but also in the two end portions of the fixed film and the vicinity thereof.

If breaks or cracks occur at both ends of the film, the film being conveyed will be separated from the film fixing structure (for example, a needle), and the film will remain in the conveying device, making it impossible to obtain the intended film. In addition, even if stagnation does not occur in such a conveying device, cracks and breaks at both ends of the film will still make it difficult to maintain the film in a properly opened state. As a result, the entire film will become wrinkled, other than at the ends, etc. Causes of quality degradation. Furthermore, if cracks or abnormal appearance occur near both ends of the film, the fixed portion (grip portion) must be cut closer to the center, causing production losses.

On the other hand, according to the present invention, it is possible to suppress film conveyance failures caused by breaks or cracks at both ends of the film. In addition, wrinkles in the center portion caused by abnormalities at both ends can also be suppressed, and a film of stable quality can be provided. Furthermore, fractures, cracks, and abnormal appearance near both ends of the film can also be suppressed, so the cut ends can be made smaller and production losses can be reduced. Furthermore, if the method of the present invention is used, excessive heat will not be supplied to the central portion of the film, so an abnormality will not be caused in the central portion of the film, and a film of stable quality can be provided.

[Form used to implement the invention]

Hereinafter, embodiments of the present invention will be described. In addition, the scope of the present invention is not limited to the embodiment described here, and various changes can be made within the scope that does not impair the gist of the present invention.

When manufacturing a film, the film may be passed through a heating furnace before heat treatment to volatilize organic solvents or cause chemical reactions to improve various physical properties. Here, the target film to volatilize the organic solvent is the film before drying, and the target film to cause the chemical reaction is the precursor film (embryonic membrane). However, in this specification, these are collectively referred to as the film before heat treatment.

When the pre-heat-treated film is passed through the heating furnace in this way, fixing members must be provided at both ends in the width direction of one side of the pre-heat-treated film, and the heat-treated film must be fixed with the fixing members (step A). The fixing method is not particularly limited. When heat treatment is performed during transportation, a tenter-type conveying device is generally used. When using a tenter-type conveyor, it is preferable to fix both ends of the film before heat treatment by inserting it into a plurality of pins of a pin-comb tenter-type conveyor. Before heat treatment, the film is preferably fixed only at the two ends. By fixing only the two end portions, the air flow in places other than the two end portions (for example, the center portion) 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 generating mechanism is often used as the heating source. The hot air generating mechanism blows hot air to the non-fastener mounting surface of the film before heat treatment (for example, the upper side surface of the film before heat treatment) and the fastener mounting surface of the film before heat treatment (for example, the lower side surface of the film before heat treatment), Heating is thereby performed (step B). By performing heat treatment, the organic solvent in the film before heat treatment is volatilized or a chemical reaction is caused, thereby improving various physical properties. The wind speed of the hot air on the surface of the film without the fasteners before heat treatment must be the same as or greater than the wind speed of the hot air on the surface where the fasteners are installed. Here, blowing hot air onto the film before heat treatment is also called heat treatment.

Next, the film before heat treatment is transported simultaneously with the aforementioned heat treatment (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. Before heat treatment, the film is transported from the back side to the front side of the paper (or from the front side to the back side). A needle plate 11 (film fixing device) is provided 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 inserted into the pins 11a (film fixing structure) provided on the upper surface of the needle plate 11 ) is used to fix (hold). Then, the film 1 before heat treatment is heat-treated in this state. The heat treatment is performed in the following manner: hot air 31 and hot air 32 are blown simultaneously from the upper and lower surfaces of the film 1 before heat treatment. The hot air 31 is provided from the hot air blowing outlet provided on the non-fixed installation surface side (upper side) of the film 1 before heat treatment. 21 is generated, and the hot air 32 is generated by the hot air blowing outlet 22 provided on the side (lower side) of the fixing member installation surface on the opposite side. At this time, the hot air 31 will blow to the pre-heat treatment film 1 without being blocked by the needle plate 11 , but a part of the hot air 32 will be blocked by the needle plate 11 and will not reach the end 1 b of the pre-heat treatment film. The hot air 32 blows the central part 1a of the film before heat treatment in the same way as the hot air 31, and it blows without being blocked. Under normal circumstances, this may cause an unfinished state of chemical reaction and an undried state of the solvent at the film end 1b before heat treatment. Furthermore, if the amount of hot air 31 (hot air not blocked by the needle plate 11) is increased to the film end portion 1b before heat treatment and the total air volume of the hot air 31 and the hot air 32 is increased, the center portion 1a of the film that becomes the product will be affected. Excessive supply of heat can cause abnormalities such as cloudiness, yellowing, and cracking caused by excessive drying. However, according to the present invention, without changing the total air volume of the hot air 31 and the hot air 32, the wind speed of the hot air 31 is made the same as or greater than the wind speed of the hot air 32, thereby reducing the hot air 32 (blocked by the needle plate 11). (hot air) increases the proportion of hot air 31 (hot air not blocked by needle plate 11), so hot air can be blown to the film end 1b more efficiently, and the aforementioned state of the film end 1b before heat treatment can be avoided. The above-mentioned abnormality will not be caused in the central portion 1a of the film that becomes the product. In FIG. 1 , the hot air blowing port 21 side of the film 1 before heat treatment is the non-fixing member installation surface, and the hot air blowing port 22 side is the fastening member setting surface.

The present invention can also be carried out by installing a pin comb tenter 11 on the upper surface of the film before heat treatment as shown in Figure 2, and inserting both ends of the film 1 before heat treatment onto the needles 11a provided on the lower surface of the needle plate 11. fixed. In this case, the wind speed of the hot air 31 on the side (lower side) of the film 1 before heat treatment where the non-fixtures are installed is made equal to the wind speed of the hot air 32 on the side (upper side) of the film 1 before heat treatment on which the fasteners are installed. , or larger than that. In FIG. 2 , the hot air blowing port 22 side of the film 1 before heat treatment is the fixing member installation surface, and the hot air blowing port 21 side is the non-fixing member setting surface.

The aforementioned pin comb tenter type conveying device generally has a plurality of needles, and the plurality of needles are arranged on a needle plate fixed (held) by a pair of moving chains arranged in parallel to each other. The needles arranged on this needle plate may be the upper surface or the lower surface of the needle plate. The arrangement of the needles is not particularly limited, and those known in the art can be used.

The temperature of the hot air blowing (blowing) to the non-fastener mounting surface and the fastener mounting surface of the film before heat treatment is preferably 80°C or more and 500°C or less in order to promote solvent volatilization and chemical reaction. When the solvent contained in the film before heat treatment is easily removed and the film before heat treatment is a precursor of polyimide (polyamide acid), imidization (thermal imidization) becomes easy. It is seen that the temperature is more preferably 120°C or higher, further preferably 150°C or higher, and particularly preferably 200°C or higher. In addition, from the viewpoint of suppressing heat-induced damage to the film, the temperature is more preferably 450°C or lower, further preferably 400°C or lower, and particularly preferably 380°C or lower. If it is within the above range, breakage and cracks of the film during transportation are suppressed, and the quality of the film becomes good. The hot air temperatures of the non-fixed part installation surface and the fixed part installation surface may be the same or different. From the viewpoint of simplicity of the device, the hot air temperatures are preferably the same temperature. The temperature change of the hot air during film conveyance is not particularly limited. It may be designed to connect a plurality of heating furnaces to change the temperature of the hot air in stages, or it may be designed to gradually increase or decrease the temperature of the hot air in the conveying direction. like design. When heat treatment is performed in a plurality of heating furnaces, the number of heating furnaces is preferably from 2 to 10, more preferably from 3 to 8, and further preferably from 4 to 6. By performing heat treatment in a plurality of heating furnaces, the film can be dried in stages or thermally imidized before heat treatment, thereby improving the quality of the film.

The wind speed of the hot air blown to the non-fixed part installation surface of the film before heat treatment is preferably 0.5m/second or more and 15m/second or less. When the hot air reaches the pre-heat treatment film sufficiently, the solvent contained in the pre-heat treatment film is easily removed, and the pre-heat treatment film is a precursor of polyimide (polyamide acid), the imidization becomes easier ( In terms of thermal imidization), it is more preferably 1 m/second or more, further preferably 1.5 m/second or more, still more preferably 2 m/second or more, and particularly preferably 3 m/second or more. In addition, from the viewpoint of suppressing breakage, cracks, needle detachment, etc. caused by vibration of the film before heat treatment, it is preferably 13 m/second or less, more preferably 12 m/second or less, and still more preferably 10 m/second or less.

The wind speed of the hot air blowing from the mounting surface of the film before heat treatment is preferably 0.4m/second or more and 14m/second or less. When the solvent contained in the film before heat treatment is easily removed and the film before heat treatment is a precursor of polyimide (polyamide acid), imidization (thermal imidization) becomes easy. It is seen that it is more preferably 0.9 m/second or more, further preferably 1.4 m/second or more, and still more preferably 1.9 m/second or more. In addition, from the viewpoint of suppressing breakage, cracks, needle detachment, etc. caused by vibration of the film before heat treatment, it is preferably 12 m/second or less, more preferably 11 m/second or less, and still more preferably 9 m/second or less.

The wind speed of the hot air blown to the non-fastener mounting surface of the film before heat treatment must be the same as or greater than the wind speed of the hot air blown to the fastener mounting surface. The ratio of the wind speed between the non-fixed element installation surface and the fixed element installation surface (non-fixed element installation surface/fixed element installation surface) is preferably greater than 1.0. It is preferably 1.05 or more from the viewpoint of suppressing the ratio of hot air blocked by the fixing member (needle plate 11), sufficient hot air reaching both ends of the film before heat treatment, drying of both ends of the film before heat treatment, and easy completion of chemical reactions. , preferably 1.1 or above. In addition, from the viewpoint of suppressing the temperature drop of the space on the fixing member installation surface side and the temperature drop of the film itself accompanying the aforementioned temperature drop, and making it easier to complete the drying of the entire film before heat treatment and the chemical reaction, it is preferably 10 or less, and more preferably It is preferably 5 or less, and further preferably 3 or less.

If the wind speed of the hot air blown to the non-fixed part setting surface of the film before heat treatment is smaller than the hot air blowing to the fixed part setting surface, the ratio of the hot air blocked by the film fixing part will increase, which will affect the end of the film before heat treatment. The hot air blowing from the part will be reduced. Therefore, it takes more time for drying and completion of chemical reaction in the film end portion before heat treatment than in the center portion of the film before heat treatment. If only the ends of the film are dry and the chemical reaction is not completed, sufficient strength cannot be obtained at the ends of the film, and appearance abnormalities such as cracks and elongation starting from the film fixing structure (needle 11a) may occur. If this abnormality occurs significantly, the broken film may become stuck in the furnace outlet, etc., and the film transportation itself may become difficult. In addition, such appearance abnormalities starting from the ends of the film may not stop at the ends but extend to the vicinity of the center of the film, causing quality degradation and production losses.

The residual solvent contained in the dried film after heat treatment is preferably 500 ppm or less, more preferably 200 ppm or less, and further preferably 100 ppm or less. The smaller the amount of residual solvent, the better, but industrially it can be 1 ppm or more, and it does not matter if it is 10 ppm or more.

The film of the present invention is preferably produced by winding a long film with a width of 300 mm or more and a length of 10 m or more. In addition, the method of fixing both ends in the width direction of one side of the film before heat treatment is not particularly limited. The film may be held by inserting it into the pins of a pin comb tenter type conveyor, or may be tentered with a clip. Clamp the machine-type conveyor to hold it.

The width of both ends (width of each end) is not particularly limited as long as it is a width that can be fixed using a conventionally known tenter-type conveyor device. Specifically, the lower limit is preferably 5 mm or more, and 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 further preferably 1% or more. Moreover, 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 50% or less of the total width of the film, more preferably 30% or less, and still more preferably 10% or less.

When the total width of the film before heat treatment is 100%, the center part of the film in the width direction before heat treatment is preferably 30 to 70% away from one end, more preferably 40 to 60% away from one end, and further preferably The best position is 45 to 55% apart.

The conveying speed of the film before heat treatment can be appropriately set according to the heat treatment conditions (hot air temperature, wind speed, etc.). The appropriate conveying speed depends on the furnace length of the heat treatment furnace, so it is difficult to determine strictly. However, if it is slow, productivity may decrease. It is preferably 0.05m/min or more, more preferably 0.1m/min or more.

＜Film＞ Examples of the film (heat-treated film) of the present invention include polyimide-based resins such as polyamideimide, polyamideimide, polyetherimide, and fluorinated polyimide (for example, Aromatic polyimide resin, alicyclic polyimide resin); polyolefin resins such as polyethylene and polypropylene; polyethylene terephthalate, polybutylene terephthalate, poly2, Copolymerized polyesters such as 6-ethylene naphthalate (for example, fully aromatic polyester, semi-aromatic polyester); (meth)acrylate copolymers represented by polymethyl methacrylate; polycarbonate Ester; polyamide; polyester; polyether ketone; polyetherketone; cellulose acetate; cellulose nitrate; aromatic polyamide; polyvinyl chloride; polyphenol; polyarylate; polyphenylene sulfide; polyphenylene sulfide Ether; polystyrene and other films.

It is a premise that the above-mentioned film can be suitably used in a process involving a heat treatment of 250° C. or higher. Therefore, those of the exemplified polymer films that can be actually used are limited. Among the aforementioned films, films using so-called super engineering plastics are preferred. More specifically, polyamide-based resins, polyamide-based resins, polyamide-imide-based resins, and azole-based plastics are preferred. resin. Particularly preferred examples include aromatic polyimide films, aromatic amide films, aromatic amide imide films, aromatic benzothiazole films, aromatic benzothiazole films, aromatic Benzimidazole film, etc.

Examples of the film before heat treatment of the present invention include: a film containing an organic solvent (film before drying), a film before chemical reaction (precursor film), or a precursor film containing an organic solvent (precursor film before drying). wait. The organic solvent content of the film before heat treatment is preferably 50 mass % or less, more preferably 45 mass % or less, and still more preferably 40 mass % from the viewpoint of being able to fix (hold) both ends of the film before heat treatment for transportation. %the following. Moreover, from the viewpoint of manufacturing efficiency and cost, it is preferably 10 mass% or more, more preferably 15 mass% or more, and further preferably 20 mass% or more.

The details of a polyimide-based resin film (sometimes also referred to as a polyimide film), which is an example of the film, will be described below. Generally speaking, a polyamide-based resin film is obtained by coating a polyamide acid (polyamide precursor) solution obtained by reacting diamines and tetracarboxylic acids in a solvent on a polyamide resin film. On a support for producing a polyimide film and drying it to form an embryonic membrane (hereinafter also referred to as a "polyamide film"), it is further placed on a support for producing a polyimide film or after being peeled off from the support. The embryonic membrane is heat treated at high temperature to perform dehydration and closed-loop reaction. This polyamide film is the precursor film of polyimide.

The polyamide acid (which is a polyimide precursor, and is also referred to as polyamide acid below) solution can be coated by, for example, spin coating, a doctor blade, a coater, a notch wheel coater, a screen printing method, or a narrow-frame printing method. Conventionally known solution coating methods such as slot coating, reverse coating, dip coating, curtain coating, and slot die coating are used.

The diamines constituting the polyamide are not particularly limited, and generally used aromatic diamines, aliphatic diamines, alicyclic diamines, etc. can be synthesized using polyimide. From the viewpoint of heat resistance, aromatic diamines are preferred. The diamines may be used alone or in combination of two or more types.

The diamines are not particularly limited, and examples thereof include oxydiphenylamine (bis(4-aminophenyl)ether), p-phenylenediamine (1,4-phenylenediamine), and the like.

As for the tetracarboxylic acids constituting the polyamide acid, commonly used aromatic tetracarboxylic acids (including their acid anhydrides), aliphatic tetracarboxylic acids (including their acid anhydrides), and alicyclic tetracarboxylic acids (including their acid anhydrides) can be synthesized using polyimide. Acids (including their anhydrides). When these are acid anhydrides, there may be one or two anhydride structures in the molecule, and those having two anhydride structures (dianhydrides) are preferred. Tetracarboxylic acids may be used alone, or two or more types may be used in combination.

The tetracarboxylic acid is not particularly limited, and examples thereof include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and the like.

The aforementioned polyimide film may also be a transparent polyimide film.

Colorless and transparent polyimide, which is an example of the aforementioned film, will be described. In order to avoid complexity below, it will also be simply described as transparent polyimide. In terms of the transparency of the transparent polyimide, a total light transmittance of 75% or more is preferred. More preferably, it is 80% or more, still more preferably, it is 83% or more, still more preferably, it is 84% or more, and particularly preferably, it is 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, and more preferably 97% or less. The colorless and transparent polyimide of the present invention is preferably a polyimide with a total light transmittance of more than 75%.

Examples of aromatic tetracarboxylic acids used to obtain colorless and highly transparent polyimide include: 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid, 4, 4'-Oxydiphthalic acid, bis(1,3-bisoxy-1,3-dihydro-2-benzofuran-5-carboxylic acid) 1,4-phenylene, bis(1 ,3-Dihydro-1,3-dihydro-2-benzofuran-5-yl)benzene-1,4-dicarboxylate, 4,4'-[4,4'-(3- Pendant oxy-1,3-dihydro-2-benzofuran-1,1-diyl)bis(benzene-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3, 3',4,4'-diphenylketotetracarboxylic acid, 4,4'-[(3-side oxy-1,3-dihydro-2-benzofuran-1,1-diyl)bis( Toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[(3-side oxy-1,3-dihydro-2-benzofuran-1, 1-Diyl)bis(1,4-dimethylbenzene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3-side oxygen 1,3-Dihydro-2-benzofuran-1,1-diyl)bis(4-isopropyl-toluene-2,5-diyloxy)]diphenyl-1,2-di Formic acid, 4,4'-[4,4'-(3-side oxy-1,3-dihydro-2-benzofuran-1,1-diyl)bis(naphthalene-1,4-diyl) Oxygen)] diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzothiol)-1,1-dioxo-3 ,3-Diyl)bis(phenyl-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-diphenylketotetracarboxylic acid, 4,4'-[(3H -2,1-Benzethanethiol-1,1-dioxo-3,3-diyl)bis(toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[(3H-2,1-benzoethanethiol-1,1-dioxo-3,3-diyl)bis(1,4-xylene-2,5-diyloxy base)] diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1-benzoethanethiol-1,1-dioxo-3,3-di base)bis(4-isopropyl-toluene-2,5-diyloxy)]diphenyl-1,2-dicarboxylic acid, 4,4'-[4,4'-(3H-2,1- Benzethanethiol-1,1-dioxo-3,3-diyl)bis(naphthalene-1,4-diyloxy)]diphenyl-1,2-dicarboxylic acid, 3,3', 4,4'-diphenylketotetracarboxylic acid, 3,3',4,4'-diphenylketotetracarboxylic acid, 3,3',4,4'-diphenyltetracarboxylic acid, 3,3',4,4'-biphenyltetracarboxylic acid, 2,3,3',4'-biphenyltetracarboxylic acid, pyromellitic acid, 4,4'-[spiro(𠮿 -9,9'-茀)-2,6-diylbis(oxycarbonyl)]diphthalic acid, 4,4'-[spiro(𠮿 Tetracarboxylic acids such as -9,9'-fluorine)-3,6-diylbis(oxycarbonyl)]diphthalic acid and their anhydrides. Among these, dianhydrides having two acid anhydride structures are suitable, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic anhydride and 4,4'- Oxydiphthalic anhydride. In addition, aromatic tetracarboxylic acids may be used alone, or two or more types may be used in combination. When attaching importance to heat resistance, the copolymerization amount of aromatic tetracarboxylic acids is, for example, preferably 50 mass% or more of all tetracarboxylic acids, more preferably 60 mass% or more, further preferably 70 mass% or more, and still more preferably Preferably, it is 80 mass % or more, and particularly preferably, it is 90 mass % or more, and 100 mass % may also be sufficient.

As for alicyclic tetracarboxylic acids, examples include: 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 1,2,3,4-cyclobutanetetracarboxylic acid Hexanetetracarboxylic 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]octane-7-ene-2,3,5,6- Tetracarboxylic acid, tetrahydroanthracene-2,3,6,7-tetracarboxylic acid, tetrahydroanthracene-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic acid Formic 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-methanonaphthalene-2,3,6,7-tetracarboxylic acid ), norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic 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 Formic acid, norbornane-2-spiro-α-cyclodecanone-α'-spiro-2”-norbornane-5,5”,6,6”-tetracarboxylic acid, norbornane-2-spiro-α -Cyclundecanone-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-cyclotridecone-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-5,5", 6,6"-tetracarboxylic acid and other tetracarboxylic acids and their anhydrides. Among these, dianhydrides having two acid anhydride structures are suitable, and 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 1,2,3,4-cyclohexanetetracarboxylic dianhydride are particularly preferred. Formic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, more preferably 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexane Tetracarboxylic dianhydride, more preferably 1,2,3,4-cyclobutane tetracarboxylic dianhydride. In addition, these may be used individually or in combination of 2 or more types. When transparency is important, the copolymerization amount of alicyclic tetracarboxylic acids is, for example, preferably 50 mass% or more of all tetracarboxylic acids, more preferably 60 mass% or more, further preferably 70 mass% or more, and further still It is preferably 80 mass% or more, particularly preferably 90 mass% or more, and 100 mass% may also be used.

Examples of tricarboxylic acids include trimellitic acid, 1,2,5-naphthalenetricarboxylic acid, diphenylether-3,3',4'-tricarboxylic acid, and diphenyltricarboxylic acid. Aromatic tricarboxylic acids such as 3,3',4'-tricarboxylic acid, or hydrides of the above aromatic tricarboxylic acids such as hexahydrotrimellitic acid, ethylene glycol bis-trimellitate, propylene glycol bis-trimellitic acid Acid esters, alkylene glycol bis-trimellitic acid esters such as 1,4-butanediol bis-trimellitate, polyethylene glycol bis-trimellitate, and their monoanhydrides and esterified products. Among these, an anhydride having one acid anhydride structure is suitable, and trimellitic anhydride and hexahydrotriellitic anhydride are particularly preferred. In addition, these can be used individually or in combination of multiple types.

Examples of dicarboxylic acids include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, and 4,4'-oxydibenzoic acid, or 1,6 -Hydrogenates of the above aromatic dicarboxylic acids such as cyclohexanedicarboxylic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecane Diacid, dodecanedioic acid, 2-methylsuccinic acid, and their chloride or esterified products, etc. Among these, aromatic dicarboxylic acids and their hydrogenates are suitable, and terephthalic acid, 1,6-cyclohexanedicarboxylic acid, and 4,4'-oxydibenzoic acid are particularly preferred. In addition, dicarboxylic acids can be used alone or in combination of plural types.

The diamines or isocyanates used to obtain a colorless and highly transparent polyamide imide are not particularly limited and can be used: usually used in polyamide imine synthesis, polyamide imine synthesis, and polyamide imine synthesis. Synthetic aromatic diamines, aliphatic diamines, alicyclic diamines, aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. From the viewpoint of heat resistance, aromatic diamines are preferred, and from the viewpoint of transparency, alicyclic diamines are preferred. Furthermore, when aromatic diamines having a benzoethazole structure are used, it becomes possible to exhibit high heat resistance, high elastic modulus, low thermal shrinkage, and low linear expansion coefficient. Diamines and isocyanates may be used alone or two or more types may be used in combination.

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-aminobenzene) Oxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]terine, 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'-diaminodiphenyl sulfide, 4,4'-diaminobis Phenyl sulfide, 3,3'-diaminodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfoxide, 3,3 '-Diaminodiphenyl terine, 3,4'-diaminodiphenyl terine, 4,4'-diaminodiphenyl terine, 3,3'-diamino diphenyl ketone, 3 ,4'-Diaminodiphenylketone, 4,4'-Diaminodiphenylketone, 3,3'-Diaminodiphenylmethane, 3,4'-Diaminodiphenylmethane , 4,4'-diaminodiphenylmethane, bis[4-(4-aminophenoxy)phenyl]methane, 1,1-bis[4-(4-aminophenoxy)benzene 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-aminophenoxy)phenyl]butane, 1,3-bis[4-(4- Aminophenoxy)phenyl]butane, 1,4-bis[4-(4-aminophenoxy)phenyl]butane, 2,2-bis[4-(4-aminophenoxy) base)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]one, bis[4- (4-Aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfoxide, bis[4-(4-aminophenoxy)phenyl] Bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 1,3-bis[4-(4-amine) phenoxy)benzyl]benzene, 1,3-bis[4-(3-aminophenoxy)benzyl]benzene, 1,4-bis[4-(3-aminobenzene) Oxy)benzyl]benzene, 4,4'-bis[(3-aminophenoxy)benzyl]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-amine phenoxy)phenyl]terine, 4,4'-bis[3-(4-aminophenoxy)benzyl]diphenyl ether, 4,4'-bis[3-(3 -Aminophenoxy)benzoyl]diphenyl ether, 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylketone , 4,4'-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]diphenylsine, bis[4-{4-(4-aminophenoxy) )phenoxy}phenyl]benzene, 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-trifluoromethylphenoxy) -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-cyano) Phenoxy)-α,α-dimethylbenzyl]benzene, 3,3'-diamino-4,4'-diphenoxydiphenylketone, 4,4'-diamino-5 ,5'-diphenoxydiphenyl ketone, 3,4'-diamino-4,5'-diphenoxydiphenyl ketone, 3,3'-diamino-4-phenoxy Diphenyl ketone, 4,4'-diamino-5-phenoxydiphenyl ketone, 3,4'-diamino-4-phenoxydiphenyl ketone, 3,4'-diamine -5'-phenoxydiphenyl ketone, 3,3'-diamino-4,4'-diphenoxydiphenyl ketone, 4,4'-diamino-5,5' -Diphenoxydiphenyl ketone, 3,4'-diamino-4,5'-diphenoxydiphenyl ketone, 3,3'-diamino-4-diphenyloxy Diphenyl ketone, 4,4'-diamino-5-biphenyloxydiphenyl ketone, 3,4'-diamino-4-biphenyloxydiphenyl ketone, 3,4'- Diamino-5'-biphenoxydiphenyl ketone, 1,3-bis(3-amino-4-phenoxybenzoyl)benzene, 1,4-bis(3-amino- 4-phenoxybenzyl)benzene, 1,3-bis(4-amino-5-phenoxybenzyl)benzene, 1,4-bis(4-amino-5-phenoxy) benzene, 1,3-bis(3-amino-4-biphenyloxybenzyl)benzene, 1,4-bis(3-amino-4-biphenyloxybenzene) Formyl)benzene, 1,3-bis(4-amino-5-biphenyloxybenzyl)benzene, 1,4-bis(4-amino-5-biphenyloxybenzyl)benzene benzene, 2,6-bis[4-(4-amino-α,α-dimethylbenzyl)phenoxy]benzonitrile, 4,4'-[9H-fluorine-9,9- Diyl]bisaniline (also known as "9,9-bis(4-aminophenyl)benzene"), spiro(𠮿 -9,9'-茀)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(𠮿 -9,9'-茀)-2,6-diylbis(oxycarbonyl)]bisaniline, 4,4'-[spiro(𠮿 -9,9'-fluoro)-3,6-diylbis(oxycarbonyl)]bisaniline, etc. In addition, part or all of the hydrogen atoms on the aromatic ring of the above-mentioned aromatic diamine may be substituted by a halogen atom, an alkyl group or an alkoxy group having 1 to 3 carbon atoms, or a cyano group. Furthermore, the above-mentioned alkyl group having 1 to 3 carbon atoms may be substituted. Part or all of the hydrogen atoms of the alkyl group or alkoxy group of ~3 may be substituted by halogen atoms. In addition, the aromatic diamines having a benzoethazole structure are not particularly limited, and examples include: 5-amino-2-(p-aminophenyl)benzoethazole, 6-amine 2-(p-aminophenyl)benzoethazole, 5-amino-2-(m-aminophenyl)benzoethazole, 6-amino-2-(m-aminophenyl)benzoyl Trioxazole, 2,2'-p-phenylenebis(5-aminobenzoethazole), 2,2'-p-phenylenebis(6-aminobenzoethazole), 1-(5 -Aminobenzoethazole)-4-(6-aminobenzoethazole)benzene, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:5 ,4-d']bisethazole, 2,6-(4,4'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisethazole, 2,6 -(3,4'-Diaminodiphenyl)benzo[1,2-d:5,4-d']bisethazole, 2,6-(3,4'-diaminodiphenyl )benzo[1,2-d:4,5-d']bisethazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:5,4 -d']bisethazole, 2,6-(3,3'-diaminodiphenyl)benzo[1,2-d:4,5-d']bisethazole, etc. Among these, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl and 4-amino-N-(4-aminophenyl)benzene are particularly preferred. Formamide, 4,4'-diaminodiphenyl ketone, 3,3'-diaminodiphenyl ketone. In addition, aromatic diamines can be used individually or in combination of multiple types.

Examples of alicyclic diamines include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, and 1,4-diamino-2 -Ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2- n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-butylcyclohexane, 1,4-diamino- 2-tert-butylcyclohexane, 4,4'-methylenebis(2,6-dimethylcyclohexylamine), etc. Among these, 1,4-diaminocyclohexane and 1,4-diamino-2-methylcyclohexane are particularly preferred, and 1,4-diaminocyclohexane is more preferred. . In addition, alicyclic diamines can be used individually or in combination of multiple types.

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'-dimethoxy diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-3,3'-diisocyanate, diphenylmethane-3,4'- Diisocyanate, diphenyl ether-4,4'-diisocyanate, diphenyl ketone-4,4'-diisocyanate, diphenyl tereine-4,4'-diisocyanate, toxylene-2,4 -Diisocyanates, tolylene-2,6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-(2,2 Bis(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-4,4'-diisocyanate, 3,3'-diethoxybiphenyl-4,4 Aromatic diisocyanates such as '-diisocyanate, and diisocyanates obtained by hydrogenating any of these (for example, isophorone diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate), etc. Among these, diphenylmethane-4,4'-diisocyanate and tolynylene-2,4-diisocyanate are preferred from the viewpoints of low hygroscopicity, dimensional stability, price, and polymerizability. Isocyanate, tolylene-2,6-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, naphthalene-2,6-diisocyanate, 4,4'-dicyclohexyl Methane diisocyanate, 1,4-cyclohexane diisocyanate. In addition, diisocyanates can be used individually or in combination of multiple types.

The solvent may be any solvent that can dissolve polyimide or a precursor of polyimide, and an aprotic polar solvent or the like can be used appropriately. Examples include: N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylmethoxyacetamide Etc. N,N-dilower alkylcarboxamides, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, dimethylsulfoxide, 1,3 -Dimethyl-2-imidazolinone, γ-butyrolactone, diglyme, m-cresol, hexamethylphosphatidamide, N-acetyl-2-pyrrolidone, hexagonal Methylphosphonamide, ethylthiosulfate acetate, diethylene glycol dimethyl ether, cyclotenine, p-chlorophenol, etc. In addition, the solvent may be a mixture of two or more types.

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

When the aforementioned film is a transparent polyimide film, its yellow index (hereinafter also referred to as "Yellow Index" or "YI") is preferably 10 or less, more preferably 7 or less, further preferably 5 or less, and still more preferably The best value is 3 or less. The lower limit of the yellow index of the transparent polyimide is not particularly limited, but for use 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.

The aforementioned film is preferably obtained in the form of a long film with a width of 300 mm or more and a length of 10 m or more during its production, and is more preferably in the form of a roll film wound on a winding core. good. If the film is rolled into a roll, transportation in the form of the film rolled into a roll becomes easy.

In order to ensure handleability and productivity, about 0.03 to 3% by mass of lubricant (particles) with a particle size of about 10 to 1000 nm is added/contained in the film to provide fine unevenness on the surface of the film to ensure The sliding properties are better. The particle size of the lubricant is preferably 20 to 500 nm, more preferably 30 to 300 nm, further preferably 50 to 200 nm. By setting the particle size of the lubricant to 10 nm or more, sufficient sliding properties relative to the added amount can be achieved. In addition, by setting the particle size of the lubricant to 1000 nm or less, problems such as a decrease in mechanical strength and cloudiness of the film can be reduced.

The film manufacturing device of the present invention has: The fixing mechanism A arranges fixing members at both ends in the width direction of one side of the film before heat treatment, and fixes the heat-treated film with the fixing members, The air blowing mechanism B blows hot air to both sides of the film before heat treatment. The conveying mechanism C conveys the aforementioned film before heat treatment, The wind speed of the hot air blown by the aforementioned air blowing mechanism B to the surface without the fixing parts is the same as or greater than the wind speed of the hot air blown to the surface with the fixing parts. The film and mechanisms A to C in the aforementioned manufacturing device are synonymous with those described in the film manufacturing method. [Example]

Hereinafter, the present invention will be described in detail using examples. However, the present invention is not limited to the following examples as long as the gist is not exceeded.

<Synthesis Example 1 (Preparation of Polyamide Solution A)> After replacing nitrogen in a reaction vessel equipped with a nitrogen inlet pipe, a reflux pipe, and a stirring rod, 33.36 parts by mass of silicon dioxide was added so that the total polymer solid content of silicon dioxide in the polyamide solution became 0.15 mass%. 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), 270.37 parts by mass of N,N-dimethylacetamide (DMAc) and colloidal silica dispersed The dispersion ("SNOWTEX (registered trademark) DMAC-ST" manufactured by Nissan Chemical Industry) in dimethylacetamide was completely dissolved, and then 9.81 parts by mass of 1,2 was added in portions as a solid. , 3,4-cyclobutanetetracarboxylic dianhydride (CBDA), 11.34 parts by mass of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 4.85 parts by mass of 4,4'-oxygen After adding diphthalic dianhydride (ODPA), the mixture was stirred at room temperature for 24 hours. Thereafter, 165.7 parts by mass of DMAc was added and diluted to obtain a polyamide solution A (PAA-A) with a solid content of 18 mass % and a reduced viscosity of 2.7 dl/g (molar ratio of TFMB//CBDA/BPDA/ODPA = 1.00// 0.48/0.37/0.15).

<Synthesis Example 2 (Preparation of Polyamide Solution B)> While passing nitrogen gas through a reactor equipped with a nitrogen inlet pipe and a stirring blade, 3.16 parts by mass of pyromellitic dianhydride (PMDA) and 2.84 parts by mass of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (PMDA) were added. anhydride (BPDA), 7.73 mass of 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), and so that colloidal silica (lubricant) is relatively N,N-dimethylacetamide (DMAc, 77.8 parts by mass) and colloidal silica (lubricant) were added and dispersed in dimethylacetamide so that the total polymer solid content in the amine acid solution became 0.15% by mass. A dispersion made of amide ("SNOWTEX (registered trademark) DMAC-ST-ZL" manufactured by Nissan Chemical Industry) was stirred at 25°C for 24 hours to obtain polyamide solution B (PAA-B) (TFMB //PMDA/BPDA).

Example 1 Using a notch wheel coater, the obtained polyamide solution A was applied to the non-lubricant surface of polyethylene terephthalate film A4100 (manufactured by Toyobo Co., Ltd.) so that the final film thickness became 20 μm. superior. Dry it at 90°C for 15 minutes. After drying, the self-supporting polyamide film is peeled off from the A4100 film as a support to obtain a polyamide film (film before heat treatment). Next, the pin comb tenter 11 (film fixing member) is placed at the end of the lower surface of the film before heat treatment with the pins 11a (film fixing structure) facing upward, and the end of the film before heat treatment is inserted into the pins. Come up and fix it. Next, the distance between the needle plates is adjusted so that the film will not break before heat treatment, and the needle plate is conveyed, and the non-fixed needle plates are separated from the upper blowout port at 250°C for 3 minutes, 290°C for 3 minutes, 340°C for 3 minutes, and 350°C for 3 minutes. Hot air is blown onto the mounting surface of the fixture and the fixing fixture mounting surface from the lower blowout port to heat it, so that the imidization reaction proceeds. At this time, in each temperature zone, a hot air blowing outlet is provided at a distance of 175 mm up and down from the passing position of the film before heat treatment, and hot air with a wind speed of 3.8 m/s is supplied from the upper blowing outlet (direction of the non-fixed member installation surface of the film) , hot air with a wind speed of 3.6m/sec is supplied from the lower blower outlet (direction of the film fixing installation surface). Thereafter, the film was cooled to room temperature over 2 minutes, and the parts with poor flatness at both ends of the film were cut off using a cutting machine, and rolled into a roll to obtain a 100-meter polyimide film with a width of 500 mm.

Examples 2 to 4 The resin and production conditions used were set as shown in Table 1, and the same operations were performed as in Example 1 to obtain polyimide films.

Comparative examples 1 to 2 The resin and production conditions used were set as shown in Table 1, and the same operations were performed as in Example 1 to obtain polyimide films.

＜Measurement of blower outlet wind speed＞ The heat treatment furnace at room temperature is set to a state where air at room temperature is sent, and an anemometer (Kanomax: ANEMOMASTER: MODEL6003) is used for measurement at the hot air outlet.

＜Film appearance (end)＞ The state of the film before heat treatment during transportation in the furnace and the state of the end portion (fixed portion) of the film after heat treatment were visually confirmed and evaluated. The evaluation is carried out in the following three stages. ○: There is no problem with film transportation and the film can be maintained in a properly opened state. △: There is no problem with film transportation, but the film cannot be maintained in a properly opened state. ×: The film separated due to breakage, cracks or sagging comes into contact with the furnace wall, etc., and cannot be transported.

＜Film appearance (center part)＞ Visually evaluate whether there are any abnormalities such as breaks, cracks, wrinkles, etc. in the remaining cut portion of the fixed part. The evaluation is carried out in the following two stages. ○: There are no abnormalities such as breaks, cracks, or wrinkles except for the ends of the film (fixed portion). ×: Except for the film end (fixed portion), abnormalities such as breaks, cracks, and wrinkles were observed

＜Total light transmittance＞ The total light transmittance (TT) of the film was measured using HAZEMETER (NDH5000, manufactured by Nippon Denshoku Co., Ltd.). As far as the light source is concerned, a D65 lamp is used. The film rolled into a roll was rolled out by 2 m and cut into five pieces of 50 mm square film. Each film was measured once, and the arithmetic mean of the total five measured values obtained was used.

＜Film thickness＞ The film thickness of the film was measured using a film thickness measuring instrument HKT-1216 (manufactured by Mahr Corporation). Roll out the film 2.5m from the roll, measure the total width from either end of the film inward at 2cm intervals, and average the thickness as the film thickness.

＜YI＞ Using a colorimeter (ZE6000, manufactured by Nippon Denshoku Co., Ltd.) and a C2 light source, the tristimulus XYZ values of the film were measured based on ASTM D1925, and the yellowness index (YI) was calculated using the following formula. The film rolled into a roll was rolled out by 3 meters, and five pieces of 50 mm square film were cut out. Each film was measured once, and the arithmetic mean of the total five measured values obtained was used. YI=100×(1.28X-1.06Z)/Y

＜Tg (glass transition temperature)＞ The glass transition temperature is measured by cutting out a 5 mm × 20 mm film from the center part in the width direction of the roll-shaped film at a position of 3.5 m, and using a dynamic viscoelasticity measuring device (DMA Q800 manufactured by TA Instruments Co., Ltd. ), measured from 30°C to 450°C at a heating rate of 5°C/min and a frequency of 10Hz, and the temperature at which the change in elastic modulus (mechanical tan δ) reaches the maximum is regarded as the glass transition temperature. Detailed measurement conditions are as follows. Measurement mode: DMA Multi-Frequency-strain Tenshion film/Rectangular strain：0.1% Preload force：0.02N Force track: 125% Poisson’s ratio: 0.440

＜CTE (coefficient of linear thermal expansion)＞ From the center part of the width direction where the film is rolled out 4 m, cut out a piece of film with a size of 20 mm (TD direction) As a film with a size of 20 mm × 2 mm on the long side, the expansion ratio is measured under the following conditions, and the expansion ratio/temperature at intervals of 15°C is measured such as 30°C to 45°C and 45°C to 60°C. The measurement was carried out up to 300°C, and the average of all measured values was calculated as CTE. Furthermore, the calculated results of the film with the MD direction as the long side and the calculated results of the film with the TD direction as the long side were calculated. Machine name: TMA4000S made by MAC Science Sample length; 20mm Sample width; 2mm Heating starting temperature; 25℃ End temperature of heating up; 300℃ Heating rate: 5℃/min environment; argon

Table 1 below shows the results of evaluation of film appearance (center part and end parts), YI, Tg, and CTE of the films obtained in the above Examples and Comparative Examples.

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative example 1 Comparative example 2 manufacturing conditions Coating conditions Resin Synthesis example 1 Synthesis example 1 Synthesis example 2 Synthesis example 2 Synthesis example 1 Synthesis example 2 PAA-A PAA-A PAA-B PAA-B PAA-A PAA-B Lubricant amount ppm 1500 1500 1500 1500 1500 1500 Solvent type DMAc DMAc DMAc DMAc DMAc DMAc Initial drying conditions Drying temperature ℃ 90 90 90 90 90 90 Drying time minute 15 15 15 15 15 15 Film before heat treatment Solvent content % 33 33 34 34 33 34 Heat treatment conditions Temperature zone 1 Blowing outlet temperature ℃ 250 250 250 250 250 250 processing time minute 3 3 3 3 3 3 Temperature zone 2 Blowing outlet temperature ℃ 290 290 290 290 290 290 processing time minute 3 3 3 3 3 3 Temperature zone 3 Blowing outlet temperature ℃ 340 340 340 340 340 340 processing time minute 3 3 3 3 3 3 Temperature zone 4 Blowing outlet temperature ℃ 350 350 350 350 350 350 processing time minute 3 3 3 3 3 3 Air outlet wind speed A (non-fixed installation surface) m/second 3.8 4.5 3.8 4.5 3.1 3.1 Blower outlet wind speed B (fixture installation surface) m/second 3.6 3.1 3.6 3.1 4.6 4.6 Wind speed A/wind speed B 1.1 1.5 1.1 1.5 0.7 0.7 physical properties Film appearance Central Department ○ ○ ○ ○ × × Ends ○ ○ ○ ○ △ △ Film thickness μm 20 20 20 20 20 20 total light transmittance % 88.6 88.5 85.8 85.5 88.5 85.7 YI(yellow) 7.2 7.1 10.3 10.5 7.2 10.3 Tg (glass transition temperature) ℃ 381 381 418 418 381 418 CTE (coefficient of linear expansion) MD direction ppm/℃ 45 44 9 11 52 25 TD direction ppm/℃ 43 43 8 9 53 28 [Possibility of industrial application]

In the production of a film, the present invention can provide a film that does not have breakage, cracks, or abnormal appearance not only in the central portion of the film but also at both ends of the fixed film and in the vicinity thereof, and can be favorably applied to, for example, flexible electronic devices. .

1: Film (film before heat treatment) 1a: Center part of film 1b: Film end 11: Needle plate (film fixing piece) 11a: Needle (film fixed structure) 21: There is no hot air blowing outlet on the side of the film fixing part. 22: Set up the hot air blowing outlet on the side of the film fixing piece 31: Blow hot air to the side without film fixing device 32: Blow hot air to the side where the film fixing device is installed

FIG. 1 is an explanatory diagram schematically showing the state of a film being conveyed according to the present invention. FIG. 2 is an explanatory diagram schematically showing another state of the film being conveyed according to the present invention. In addition, in FIGS. 1 and 2 , the hot air is not blown out from three points at the top and bottom, but is blown out uniformly from the entire width direction of the blower outlet. Moreover, a plurality of blowing outlets are arranged in the conveyance direction of the film.

without.

Claims (6)

A method for manufacturing a thin film, which is a method for manufacturing a thin film, and has the following features: Step A, disposing fixing members at both ends in the width direction of one side of the film before heat treatment, and fixing the heat-treated film with the fixing members, Step B, blow hot air on both sides of the film before heat treatment, Step C, transporting the film before heat treatment, In step B, the wind speed of the hot air blown to the surface without the fixing piece is the same as or greater than the wind speed of the hot air blown to the side with the fixing piece. The method for manufacturing a film according to claim 1, wherein the wind speed on the side without the fixing member in step B is greater than 1.0 times the wind speed on the side with the fixing member. The method of manufacturing a film according to claim 1 or 2, wherein the fixing member is a needle plate. The method for manufacturing a film according to claim 1 or 2, wherein the film is a polyimide film. The method for manufacturing a film according to claim 4, wherein the polyimide film is a transparent polyimide film. A film manufacturing device, which is a film manufacturing device and has: The fixing mechanism A arranges fixing members at both ends in the width direction of one side of the film before heat treatment, and fixes the heat-treated film with the fixing members, Air blower B blows hot air to both sides of the film before heat treatment. The conveying mechanism C conveys the film before heat treatment, The wind speed of the hot air blown by the air blowing mechanism B to the surface without the fixing parts is the same as or greater than the wind speed of the hot air blown to the surface with the fixing parts.