JP2008284703A - Method for producing polyimide film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for stably producing an extremely thin and lengthy film of a polyimide film excellent in heat resistance and mechanical properties. <P>SOLUTION: In the production method for forming the polyimide film with a thickness of 7.5 μm or below, the grip of the film in both side end parts in the width direction of the film by a film end part fixing type tenter of an imidation process, both side end parts in the width direction of a polyimide precursor film are overlaid with a narrow film prepared separately, and the parts overlaid with the narrow film are stuck with pins to be fixed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for producing a polyimide film, and in particular, a tenter type used in the final heat treatment for producing a polyimide film having a thickness of 7.5 μm or less to heat the polyimide precursor film at a high temperature to form a polyimide film. (Film conveyance) The present invention relates to a method for producing a polyimide film characterized by film gripping at both end portions in the width direction of the film in a processing section.

When producing a polyimide film, a polyimide precursor film (also referred to as a green film) in which a part of the solvent remains is imidized at a high temperature. In this case, drying and heat treatment are carried out by heating while conveying the polyimide precursor film, but a film having a small amount of these solvents generally shrinks as it is dried. In such film transport / drying / heat treatment, as an apparatus for manufacturing a film by transporting the film in the stretched width direction by holding both ends in the width direction of the film with a large number of pins and clips, A film tenter type conveying device called a so-called tenter is known (see Patent Document 1).
In addition, it is also known to use a tenter type conveying device for manufacturing a polyimide film (see Patent Document 2).
Japanese Examined Patent Publication No. 39-029211. JP 09-188863 A

The film conveying apparatus has been well known for a long time to be used for drying so as not to cause wrinkles in the drying process after dyeing the cloth. In addition to drying the cloth, it is also used for drying an undried plastic film by a solvent casting method while transporting it in the drying step. By using the film conveying apparatus, it is possible to suppress shrinkage of the film in the width direction due to heat during drying and heat treatment, and to prevent wrinkles due to shrinkage from occurring in the film after drying and heat treatment.
Film shrinkage occurs not only in the width direction of the film but in all directions, but the film transport direction is said to have a restraining effect on the shrinkage because the transport tension is acting, but the film thickness is extremely When the thickness is reduced, damage to the gripping portion due to shrinkage or the like also increases in the film transport direction. Thus, when the undried film is heat-treated, it is transported using a film tenter-type transport device, thereby ensuring the strength and flatness necessary for the dried and heat-treated film.

  Among the film tenter type conveying devices, the tenter type conveying device for the film that holds the film stretched in the width direction by biting a large number of pins along both side edges of the film was arranged in parallel A large number of pins are arranged on a pin sheet supported in a row by a pair of moving chains. This film tenter type transport device is simpler in structure than the film transport device such as the clip, or can be structured to reverse the transport conveyor path in the drying chamber. On the other hand, since the fine pieces of the film generate dust when the pins are bitten into the film, it is necessary to reduce the number of pins as much as possible. Moreover, when the shrinkage force of the film becomes large, there are problems such as the holes that have pinned the film surface break into long holes in the width direction of the film.

For these improvements, a method in which a film having a large tear strength is additionally used for reinforcement in the grip portion by the pin of the film has been proposed (see Patent Document 3), but the technique has a low tear strength. When processing a polymer resin film having a thickness of 50 to 150 μm with a film end fixed type tenter, particularly when stretched in the width direction, the sheet gripping portion at the film end has a higher tear strength than the film. In addition, the method is a method of stably tentering a polymer resin film having a low tear strength, in which the film and the reinforcing film that can be attached are overlapped and attached, and the reinforcing film is subjected to a force treatment. If the film to be processed is a polyimide film, not an ultra-thin polyimide film, it has such a strength that it does not need to be reinforced by the gripping part as long as it is such a thickness. The imidization is a high temperature treatment reaching 500 ° C.
Furthermore, a tenter type conveying device has also been proposed in which the innermost pin density is increased and the outer pin arrangement density is further reduced in the arrangement of pins that can be placed on both ends of the web when the web is conveyed (patent). Reference 4). Even in these proposals for improvement, there is nothing to consider the arrangement in the conveying direction of the pins, particularly the arrangement of the pins between the pin sheets. There was a problem in the production of films that are likely to occur.
Conventional tenter type transport devices for films tend to cause production loss due to problems such as breakage in the shape of a long hole in the width direction of the film at the hole where the pin is entrapped, and generation of wrinkles. At the same time, the production efficiency was lowered, and it was not satisfactory for users.
In particular, when an extremely thin polyimide film is manufactured by a tenter type conveying method, the above-mentioned problem becomes remarkable and cannot be overcome by the conventional proposed technique.
Japanese Patent Laid-Open No. 11-254521 JP 09-073315 A

  The present invention provides an extremely thin polyimide film that is excellent in flatness and homogeneity, which is suitable as a base material and insulating material for electronic parts, and excellent in heat resistance that does not change even when subjected to high temperature treatment. When the film is gripped at both ends of the film by the transporting method and is manufactured, there is an inefficient quality due to breaking into a long hole at the portion stabbed by the pin in the width direction and the longitudinal direction of the film. It aims at providing the manufacturing method of the polyimide film for eliminating the problem which is easy to generate | occur | produce.

That is, this invention is based on the following structures.
1. Polyamide acid obtained by reacting aromatic tetracarboxylic acids and aromatic diamines is cast and dried to obtain a polyimide precursor film, and the polyimide precursor film is placed outside in the width direction of the pin sheet, Manufacturing to obtain a polyimide film with a thickness of 7.5 μm or less, which is stabbed and fixed at both ends in the width direction of the film with pins arranged on a pin sheet, and imidized by a method of conveying and processing with a film end fixed type tenter A thin film prepared separately at both ends in the width direction of the polyimide precursor film, with a film end fixing type tenter in the process of imidizing and holding the film at both ends in the width direction of the film A polyimide film characterized in that it is performed by piercing and fixing a portion where a thin film is overlapped with a pin with a pin The method of production.
2. The method for producing a polyimide film according to 1 above, wherein the aromatic tetracarboxylic acid is at least one selected from pyromellitic acids and biphenyltetracarboxylic acids, and the aromatic diamine is at least one selected from p-phenylenediamines and diaminodiphenyl ethers.
3. The method for producing a polyimide film according to any one of the above 1 or 2, wherein the pin sheet has a portion higher than a pin pedestal installed outside in the width direction.
4). The method for producing a polyimide film according to any one of 1 to 3, wherein the polyimide film has a width of 500 to 10,000 mm and a length of 100 to 100,000 m.
5. 1. A thin film is a polyimide precursor film, and its width is 20 to 80 mm. ~ 4. A method for producing any polyimide film.

The polyimide film manufacturing method of the present invention is a narrow width different from the film to be processed and manufactured at both end portions of the film in the tenter type processing unit (conveying device) when manufacturing a polyimide film having a thickness of 7.5 μm or less. The film is overlapped with the pin and pierced into the pin provided on the pin sheet, thereby breaking the film in the shape of a long hole in the longitudinal direction and width direction, thereby eliminating the problems that are likely to cause a decrease in yield and poor quality. As a result, the quality problem in the manufactured polyimide film can be solved.
Further, since the film is held in a state of being lifted from the pedestal of the pins, there is no fusion at the pin pedestal portion of the pin sheet, and the film can be easily removed after the heat treatment. Moreover, since the contamination of the pin sheet itself does not occur, it is effective from the viewpoint of maintenance and management of the apparatus, and contributes to the productivity of manufacturing an ultrathin polyimide film, which is extremely effective industrially.

  The polyimide film of the present invention is generally called aromatic tetracarboxylic acids (anhydride, acid, and amide-bonded derivatives are collectively referred to as classes hereinafter) and aromatic diamines (amines and amide-bonded derivatives are collectively named). A polyamic acid solution obtained by reacting the same with the following) is cast, dried and heat-treated (imidized) to form a film. Examples of the solvent used in these solutions include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide and the like.

The method for producing a polyimide film of the present invention is most preferably applied particularly when a casting film forming method using an N-methyl-2-pyrrolidone solution or N, N-dimethylacetamide solution of polyamic acid, which is a polyimide precursor, is used. obtain.
Hereinafter, the polyimide film will be described in detail, but is not limited thereto.
The reaction between an aromatic diamine for obtaining a polyimide film, which can be preferably applied to the present invention, and an aromatic tetracarboxylic acid is carried out by reacting an aromatic diamine and an aromatic tetracarboxylic acid (anhydride) in a solvent. (Polymerization) Polyaddition reaction is used to obtain a polyamic acid solution as a polyimide precursor, and then a precursor film (green film) is formed from the polyamic acid solution, followed by drying and imidization (heat treatment and dehydration). Produced by condensation).

Although the polyimide film in this invention is not specifically limited, The combination of the following aromatic diamine and aromatic tetracarboxylic acid (anhydride) is mentioned as a preferable example.
A. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
B. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
C. One or more combinations of the above AB.

Examples of the aromatic diamine having a diaminodiphenyl ether skeleton in the present invention include 4,4′-diaminodiphenyl ether (DADE), 3,3′-diaminodiphenyl ether, and 3,4′-diaminodiphenyl ether and derivatives thereof. Examples of the aromatic diamine having a phenylenediamine skeleton in the invention include p-phenylenediamine, m-phenylenediamine, o-phenylenediamine and derivatives thereof, and these diamines are used in an amount of 70 mol% or more of the total diamine. It is preferable.
In the polyimide film of the present invention, the following aromatic diamines not limited to the above may be used in an amount of less than 30 mol% based on the total diamines.

For example, 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-aminobenzylamine, p-aminobenzylamine,
3,3′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 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-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) 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-dimethylphen Le] 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-aminophenoxy) 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-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-cyanophenoxy) -α, α-dimethylbenzyl] benzene,

3,3′-diamino-4,4′-diphenoxybenzophenone, 4,4′-diamino5,
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 and a part of hydrogen atoms on the aromatic ring in the aromatic diamine Or a halogen atom having 1 to 3 carbon atoms in which all or some of the hydrogen atoms of the halogen atom, alkyl group or alkoxyl group having 1 to 3 carbon atoms, cyano group, alkyl group or alkoxyl group are substituted with halogen atoms And aromatic diamines substituted with an alkyl group or an alkoxyl group.

As aromatic tetracarboxylic acids that can be preferably used in the polyimide film of the present invention, aromatic tetracarboxylic acids having a pyromellitic acid skeleton, that is, pyromellitic acid and anhydrides or halides thereof, and aromatic tetracarboxylic acids having a biphenyltetracarboxylic acid skeleton are used. Examples thereof include carboxylic acids, that is, biphenyltetracarboxylic acid and anhydrides or halides thereof, and these are preferably used in an amount of 70 mol% or more of the total acids.
Without being limited thereto, the following aromatic tetracarboxylic acid may be used if it is less than 30 mol% of the total acids.

これらのテトラカルボン酸は単独で用いてもよいし、二種以上を併用してもよい。

These tetracarboxylic acids may be used alone or in combination of two or more.

  The solvent used when polymerizing aromatic diamines and aromatic tetracarboxylic anhydrides to obtain polyamic acid is particularly limited as long as it dissolves both the raw material monomer and the produced polyamic acid. Although not preferred, polar organic solvents are preferred, such as N-methyl-2-pyrrolidone, N-acetyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide Hexamethylphosphoric amide, ethyl cellosolve acetate, diethylene glycol dimethyl ether, sulfolane, halogenated phenols and the like, among which N-methyl-2-pyrrolidone and N, N-dimethylacetamide are preferably applied. These solvents can be used alone or in combination. The amount of the solvent used may be an amount sufficient to dissolve the monomer as a raw material. As a specific amount used, the mass of the monomer in the solution in which the monomer is dissolved is usually 5 to 40% by mass, The amount is preferably 10 to 20% by mass.

Conventionally known conditions may be applied for the polymerization reaction for obtaining the polyamic acid (hereinafter also simply referred to as “polymerization reaction”). As a specific example, in a temperature range of 0 to 80 ° C., 10 Stirring and / or mixing continuously for 30 minutes. If necessary, the polymerization reaction may be divided or the temperature may be increased or decreased. In this case, the order of adding both monomers is not particularly limited, but it is preferable to add aromatic tetracarboxylic acid anhydrides to the solution of aromatic diamines. The mass of the polyamic acid in the polyamic acid solution obtained by the polymerization reaction is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). From the viewpoint of the stability of liquid feeding, it is preferably 10 to 2000 Pa · s, and more preferably 100 to 1000 Pa · s.
The reduced viscosity (ηsp / C) of the polyamic acid in the present invention is not particularly limited, but is preferably 1.5 or more, more preferably 2.0 or more, still more preferably 2.5 or more.
Moreover, you may perform superposition | polymerization by adding a small amount of terminal blockers to aromatic diamines before a polymerization reaction. Examples of the end capping agent include compounds having a carbon-carbon double bond such as maleic anhydride. The amount of maleic anhydride used is preferably 0.001 to 1.0 mol per mol of aromatic diamine.
Vacuum degassing during the polymerization reaction is effective in producing a good quality polyamic acid solution.
Furthermore, in order to obtain the polyimide film of the present invention, it is possible to remove bubbles and dissolved gas in the solution in advance by treatment such as decompression when casting and applying a polyamic acid solution described below onto the support. This is an effective process.

The support on which the polyamic acid solution is cast (applied) only needs to have smoothness and rigidity sufficient to form the polyamic acid solution into a film, and the surface is made of metal, plastic, glass, porcelain, etc. A certain drum or a belt-like rotating body may be used. A method using a polyimide film having moderate rigidity and high smoothness is also a preferred embodiment. Among them, the surface of the support is preferably a metal, more preferably stainless steel that does not rust and has excellent corrosion resistance. The surface of the support may be plated with metal such as Cr, Ni, or Sn. The surface of the support can be mirror-finished or processed into a satin finish as required. The air volume and temperature in drying may be appropriately selected and adopted depending on the difference in the support, and the polyamic acid solution can be applied to the support by casting from a nozzle with a slit, extrusion by an extruder, squeegee coating, reverse coating, die Including, but not limited to, coating, applicator coating, wire bar coating and the like, conventionally known solution application means can be used as appropriate.
In the imidization step, a ring closure (imidation) catalyst or a polyamic acid solution that does not contain a dehydrating agent is used for heat treatment to advance the imidization reaction (so-called thermal ring closure method) or a ring closure catalyst in the polyamic acid solution. And a chemical ring closing method in which an imidization reaction is performed by the action of the ring closing catalyst and the dehydrating agent.
The heat treatment temperature of the thermal ring closure method is preferably 150 to 500 ° C. If the heat treatment temperature is lower than this range, it is difficult to sufficiently close the ring, and if it is higher than this range, the deterioration proceeds and the film tends to become brittle. A more preferable embodiment includes a two-stage heat treatment step having an initial stage heat treatment and a subsequent stage heat treatment in which a heat treatment is carried out at 350 to 500 ° C. for 3 to 20 minutes after treatment at 150 to 250 ° C. for 3 to 20 minutes.
The timing for adding the ring-closing catalyst to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the ring-closing catalyst include aliphatic tertiary amines such as trimethylamine and triethylamine, and heterocyclic tertiary amines such as isoquinoline, pyridine, and betapicoline. Among them, heterocyclic tertiary amines are mentioned. At least one amine selected from is preferred. Although the usage-amount of a ring-closing catalyst with respect to 1 mol of polyamic acids does not have limitation in particular, Preferably it is 0.5-8 mol.
The timing of adding the dehydrating agent to the polyamic acid solution is not particularly limited, and may be added in advance before the polymerization reaction for obtaining the polyamic acid. Specific examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride. Among them, acetic anhydride, benzoic anhydride, etc. Acids or mixtures thereof are preferred. Moreover, the usage-amount of the dehydrating agent with respect to 1 mol of polyamic acids is not particularly limited, but is preferably 0.1 to 4 mol. When a dehydrating agent is used, a gelation retarder such as acetylacetone may be used in combination.

    Whether it is a thermal cyclization reaction or a chemical cyclization method, the polyimide film precursor (green sheet) formed on the support may be peeled off from the support before it is completely imidized. You may peel after conversion.

The thickness of the polyimide film in this invention is 7.5 micrometers or less, More preferably, it is 5 micrometers or less.
Conventionally, it has been difficult to industrially stably produce a long film of a polyamide film of 7.5 μm or less, particularly 5 μm or less, but the method for producing a polyimide film of the present invention does not solve this problem. It is. The thickness of the polyimide film can be easily controlled by the amount applied when the polyamic acid solution is applied to the support and the concentration of the polyamic acid solution.
The width | variety of the polyimide film in this invention is 500-10000 mm, for example, and length is 100-100000 m, and can be utilized also for continuous production of the component of an electronic device, a machine part, etc. .

In the polyimide film of the present invention, it is preferable to improve the slipping property of the film by adding fine lubricant to the surface of the film by adding a lubricant to the polyimide.
As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 to 1 μm can be used. Specific examples include titanium oxide, alumina, silica, calcium carbonate, calcium phosphate, calcium hydrogen phosphate, calcium pyrophosphate, Examples include magnesium oxide, calcium oxide, and clay minerals.

In the present invention, when the polyimide precursor film is imidized by a film end fixed tenter, the film end gripping at both ends in the width direction of the film is a large number of pin sheets and individual pin sheets. A tenter type processing section that transports the film in a state of being stretched in the width direction and / or the transport direction. In the polyimide film manufacturing method, at the part where the both sides of the film are gripped by piercing with a pin, the pin is pierced in a state of being overlapped with a thin film prepared separately from the polyimide precursor film to be processed. Required.
Moreover, the pin sheet | seat in which the pin is installed has a site | part higher than the pin base installed preferably in the outer side in the width direction.

  Here, the thin film prepared separately is not particularly limited, but preferably has the same quality as the polyimide precursor film to be processed, and the same polyamic acid solution is used separately from the polyimide film to be manufactured. Another polyimide precursor film is prepared by casting and drying, and is prepared by slitting in advance to a narrow width. The width of the narrow film is preferably 20 to 200 mm, particularly preferably 20 to 60 mm. The thickness of the thin film prepared separately from the polyimide precursor film to be treated is not particularly limited, but preferably the same thickness as the polyimide precursor film to be produced as a polyimide film. Preferably, it is 0.5 to 4 times the thickness of the polyimide precursor film, for example 5 to 20 μm, particularly preferably 5 to 13 μm. When the thickness is thin and less than 5 μm, the reinforcement effect of the overlay tends to be reduced, and when it is too thick and exceeds 20 μm, the overlay reinforcement effect may vary.

  The shape of the part higher than the pin pedestal installed outside the width direction of the pin sheet is not particularly limited, and the position is higher than the pin pedestal that is the surface where the pin is implanted, so that the film contacts the pin pedestal. For example, even if it is a table that is high only on the outer side in the width direction of the pin sheet (outer position in the width direction where the pins are not implanted) and is in contact with the film only at that position. Alternatively, the pin base may be a pin sheet inclined outward in the width direction. For example, in the case of a base, the shape and size of the base are preferably (1) the height of the base is the tip of the pin. If the height of the base is lower than 3 mm from the tip of the pin, it is more difficult to project both ends of the film. When the depth of the pin inserted is shallow and the frequency of the film coming off from the pin in the subsequent heat treatment process becomes high, and the height of the base is lower than 8 mm from the tip of the pin, the film is removed from the pin sheet after the heat treatment. When it removes, it becomes a big resistance and it leads to tearing both ends of the worst film, which is not preferable. (2) The height of the base is higher than the pedestal on which the pin is installed in the range of 0.5 mm to 5 mm, more preferably higher in the range of 2 mm to 3 mm. When the film is gripped, the pin insertion depth of the film by the pressing brush roll is stably determined, and the direct heat transfer suppression effect from the pin sheet to the film gripping portion is expressed. As a result, the film center portion and the gripping portion The difference in temperature of the film becomes smaller, and the difference in breaking strength during film conveyance becomes smaller. As a result, troubles such as film breakage in the tenter and when the film is peeled off from the pin sheet after heat treatment in the tenter can be reduced. . On the other hand, if the height of the base is less than 1 mm from the pedestal on which the pins are installed, the direct heat transfer suppression effect from the pin sheet to the film gripping portion is reduced. The temperature difference with the gripping part becomes large, and the difference in breaking strength during film conveyance becomes large, resulting in troubles such as film breakage in the tenter, which is not preferable. If it is higher than 5 mm than the pedestal, it is not preferable because it promotes contamination of the pin sheet itself in the heat treatment step. Further, (3) it is preferable that the periphery of the table is chamfered, and if the chamfering is not performed, the film in contact with the periphery of the table is not preferable. Also, (4) providing a cavity in the pedestal on which the pins are installed has a direct heat transfer suppression effect from the pin sheet to the film gripping part, resulting in a temperature difference between the film center part and the gripping part. Is reduced, and the difference in breaking strength during film conveyance is reduced, resulting in prevention of troubles such as film breakage in the tenter.

In a polyimide film manufacturing apparatus in which a base is installed on the outer side with respect to the width direction of the pin sheet, the pin is made of a material having a melting point or a softening point of 150 ° C. or more and an elastic modulus of 4 GPa or more when the pins pierce both side ends. It is also a preferred embodiment to use means for piercing the film end into the pin with a member provided with a brush made of bristle material.
Further, in this presser brush roll, the member of the presser brush roll that comes into contact with a portion higher than the pin base installed outside in the width direction is higher in rigidity than the member in the inner part in the width direction, Specifically, it is more preferable that the member installed on the outer side in the width direction of the pressing brush roll is a metal wire brush-shaped member or a metal cylindrical member.
Although it does not specifically limit as a member provided with the brush which consists of a bristle material which has melting | fusing point or a softening point 150 degreeC or more and whose tensile elasticity modulus is 4 GPa or more, The brush roll provided with the brush on the cylindrical plane periphery can use preferably. .
A brush made of a bristle material having a melting point or softening point of 150 ° C. or more and an elastic modulus of 4 GPa or more has the properties so that the film can be pierced uniformly and its function is deteriorated even after long-term use. The amount is extremely small, and when the one having no physical properties is used, the above two points cannot be satisfied at the same time.
A brush made of a bristle material having a melting point or softening point of 150 ° C. or higher and a tensile elastic modulus of 4 GPa or higher is not particularly limited as long as it has this physical property. For example, a high modulus polymer fiber Carbon fiber, glass fiber, and the like, more preferably polymer materials such as polymer fibers, and aromatic polyamides such as Cornex (manufactured by Teijin).

The pin tenter gripping portion in the present invention is composed of a large number of pins arranged on individual pin sheets, for example as shown in FIG. 1, for example, and a large number of these individual pin sheets are arranged to convey the film. Also, as shown in FIG. 3, before the polyimide precursor film to be processed is stabbed into the pin of the pin sheet, it is overlapped with a thin film prepared separately at both ends, and pinned with a pressing brush roll or the like. Can be stabbed into.
In the present invention, as a preferred embodiment, a cooling means is provided at a position immediately before the film heat treatment is finished and the pin or pin sheet turns and returns to the position where film gripping is started. When the film is sufficiently cooled and the both ends of the film are pierced by the pins, the film holding uniformity is maintained, and the holes expand and break in the width direction or the conveying direction of the film at the holes where the pins are entrapped. Is suppressed. As the cooling means, either air cooling or water cooling may be used, and a refrigerant other than air or water may be used. From the viewpoint of cooling efficiency, it is preferable to use a liquid refrigerant. Further, considering that the tenter itself is heated above the ignition point of a general organic solvent, it is most preferable to use a cooling means based on water cooling specifications.
By providing this cooling means, when the pins and the pin sheet start gripping both ends of the film and start conveyance, the pins etc. are kept at a high temperature when they are heated to a high temperature such as one end heat treatment temperature such as 450 ° C. and there is no cooling means. In the piercing of both ends of the film with this high-temperature pin, it is difficult to maintain the uniformity of film gripping, and the hole expands or breaks in the film width direction or the conveyance direction at the hole where the pin is bitten. Can easily occur, and problems such as an increase in distortion in the entire film and an increase in film thickness unevenness can be solved to some extent.
Furthermore, in the present invention, as a preferred embodiment, in the pin arrangement of the pin tenter, the individual pins arranged on the innermost side in the film width direction during film conveyance are mutually different from each other in the individual pin sheet in the film conveyance direction. It is preferable that the pin sheets are all arranged at equal intervals.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, this invention is not limited by a following example. In addition, the evaluation method of the physical property in the following examples is as follows.
1. Reduced viscosity of polyamic acid (ηsp / C)
A solution dissolved in N-methyl-2-pyrrolidone (or N, N-dimethylacetamide) so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube. (When the solvent used for preparing the polyamic acid solution was N, N-dimethylacetamide, the polymer was dissolved using N, N-dimethylacetamide and measured.)

2. The thickness of the polyimide film The thickness was measured using a micrometer (Millitron 1254D manufactured by Fine Reef).

3. Test specimens obtained by cutting a polyimide film to be measured into strips of 100 mm × 10 mm in the flow direction (MD direction) and the width direction (TD direction), respectively. It was. Using a tensile tester (manufactured by Shimadzu Corporation, Autograph (trade name), model name AG-5000A) under the conditions of a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile modulus of elasticity in each of the MD direction and TD direction, Tensile rupture strength and tensile rupture elongation were measured.

4). Film linear expansion coefficient (CTE)
The expansion / contraction rate was measured under the following conditions, and the range from 30 to 300 ° C. was divided at 15 ° C. intervals and obtained from the average value of the expansion / contraction rate / temperature of each divided range. The meanings of the MD direction and the TD direction are the same as described above.
Device name: TMA4000S manufactured by MAC Science
Sample length; 20mm
Sample width: 2 mm
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

[Reference Example 1]
(Preliminary dispersion of inorganic particles)
7.6 parts by weight of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 390 parts by weight of N-methyl-2-pyrrolidone, the liquid contact part of the container, and the infusion pipe are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
Nitrogen introduction pipe, thermometer, liquid contact part of vessel equipped with stirring rod, and infusion pipe were replaced with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 200 parts by mass of 4,4′-diaminodiphenyl ether Put. Next, after 3800 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 390 parts by mass and 217 parts by mass of pyromellitic dianhydride were added to the preliminary dispersion obtained above. When stirred for 5 hours at 0 ° C., a brown viscous polyamic acid solution A was obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g.

[Reference Example 2]
(Preliminary dispersion of inorganic particles)
Amorphous silica spherical particle Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 3.7 parts by mass, N-methyl-2-pyrrolidone, 420 parts by mass, the container wetted part, and the infusion pipe are austenitic stainless steel SUS316L And stirred for 1 minute at a rotation speed of 1000 rpm with a homogenizer T-25 basic (manufactured by IKA Labortechnik) to obtain a preliminary dispersion.
(Preparation of polyamic acid solution)
The wetted part of the vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod, and the infusion pipe were purged with nitrogen in the reaction vessel made of austenitic stainless steel SUS316L, and then 108 parts by mass of p-phenylenediamine was added. . Next, after 3600 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, 420 parts by mass and 292.5 parts by mass of 3,3 ′, 4,4 ′ -Diphenyltetracarboxylic dianhydride was added and stirred at 25 ° C for 12 hours to obtain a brown viscous polyamic acid solution B. The reduced viscosity (ηsp / C) was 4.5 dl / g.

(Production of narrow film)
The polyamic acid solution obtained in Reference Examples 1 and 2 was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (coating width 1240 mm), and 90 ° C. For 60 minutes. The polyamic acid film which became self-supporting after drying was peeled off from the support and cut at both ends to obtain green film A and green film B having a thickness of 8 μm and a width of 1200 mm, respectively.
Each of the green film A and the green film B was slit to prepare a narrow long slit film A and a narrow long slit film B having a width of 30 mm.

(Manufacture of polyimide film)
<Example 1>
Separately from the above, the polyamic acid solution A obtained in Reference Example 1 was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (coating width 1240 mm). ), And dried at 90 ° C. for 60 minutes. The polyamic acid film that became self-supporting after drying was peeled from the support and cut at both ends to obtain a green film having a thickness of 8 μm and a width of 1200 mm. The thin green slit film A having a width of 35 mm is superposed on both end portions of the obtained green film, and the apparatus shown in FIGS. 1 and 3 is used for pin sheets, brush rolls, pressers as shown in parentheses below. Both ends were held with a pin tenter under the conditions of a roll and a supporting jig, and heat treatment was performed. The pins are arranged so that the pin interval is constant when the pin sheets are arranged, the pin height from the pin base is 8 mm, the pin sheet interval is 1140 mm, and the length of the pin sheet in the longitudinal direction is The length in the width direction is 95 mm, the length in the longitudinal direction of the table set outside the pin sheet in the width direction is 95 mm, the length in the width direction is 15 mm, and the periphery of the table is chamfered. did. In addition, the brush roll has a two-layer structure using two kinds of materials in the width direction, made of Conex with a strand diameter of 0.3 mm, and on the outside a metal element with a strand diameter of 0.5 mm. A line was placed.
(The pin sheet has a flat plate shape, the distance between the press roll and the film grip start portion is 150 mm, the support jig uses a Teflon (registered trademark) bar, and the distance between the support jig and the film grip start portion is 170 mm).
The heat treatment settings for the tenter are as follows. The first stage was heated at 180 ° C. for 5 minutes and the heating rate was 4 ° C./second, and the second stage was heated at 460 ° C. for 5 minutes for 2 minutes to proceed the imidization reaction. Then, it cooled to room temperature in 5 minutes, the part with which the narrow film of the both ends of a film overlapped was cut off with the slitter, it rolled up in roll shape, and the polyimide film A which exhibits brown was obtained. Table 1 shows the measurement results such as the conveyance state during the heat treatment and the characteristics of the obtained polyimide film.

The flatness and effective width of the film were defined as follows.
First, the obtained film was spread on a surface plate having a clean surface, and a portion where a space was left between the surface plate due to undulation at the end of the film was regarded as a portion having poor flatness. The ends of the film were not lifted from the surface of the platen, and both ends of the film were cut until the entire film was in close contact with the platen, and the film width at that time was defined as the effective width.
Also, for pin tearing, the film tearing in the width direction and the vertical direction at the pin part is visually judged at a portion about 10 m from the top of the film, and pin holes (500 in total) adjacent to each other in the vertical direction. Those having 10 or more connected pieces were rated as x, those having about 10 to 3 pieces were evaluated as Δ, and those having two or less connected as ◯.
The peelability from the pin sheet was evaluated by visual evaluation of the state when the heat treatment was completed and the film was peeled off and peeled off from the pin sheet, and the smooth peeling was good, but the film was caught slightly on the pin. In the case where the film tears in the flow direction due to catching, it was regarded as defective.

<Example 2>
A polyimide film B was obtained in the same manner as in Example 1 except that the polyamic acid solution B obtained in Reference Example 2 was used and the narrow slit film B was overlapped on both side ends.
The evaluation was made in the same manner. The results are shown in Table 1.

<Comparative Example 1>
A polyimide film is produced in the same manner as in Example 1 except that the narrow-width long slit film A is processed using a green film having a thickness of 8 μm and a width of 1200 mm as it is without being overlapped on both ends. However, a long polyimide film that could be continuously evaluated could not be obtained.

<Comparative example 2>
A polyimide film is produced in the same manner as in Example 2, except that the narrow and long slit film B is processed by using a green film having a thickness of 8 μm and a width of 1200 mm as it is without being overlapped on both ends. However, a long polyimide film that could be continuously evaluated could not be obtained.

<Example 3>
The polyamic acid solution A was coated on the non-lubricant surface of polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (coating width 1240 mm), and dried at 90 ° C. for 60 minutes. While obtaining a green film having a thickness of 11.0 μm and a width of 1200 mm, the thin green slit film A having a width of 35 mm was superposed on both side ends on the obtained green film, with the apparatus shown in FIGS. Hereinafter, as shown in parentheses, both ends were gripped with a pin tenter under the conditions of a pin sheet, a brush roll, a pressing roll, and a support jig, and heat treatment was performed, and a polyimide film was obtained in the same manner as in the examples. The evaluation was made in the same manner. The results are shown in Table 1.

<Example 4>
A polyimide film was obtained in the same manner as in Example 3 except that the polyamic acid solution B was used and the narrow slit film B was superposed on both side ends.
The evaluation was made in the same manner. The results are shown in Table 1.

<Example 5>
A polyimide film was obtained in the same manner as in Example 1 except that the polyamic acid solution A was used and the coating thickness of the comma coater was changed.
The evaluation was made in the same manner. The results are shown in Table 1.

<Example 6>
A polyimide film was obtained in the same manner as in Example 1 except that the polyamide acid solution B was used and the coating thickness of the comma coater was changed.
The evaluation was made in the same manner. The results are shown in Table 1.

<Comparative Example 3>
A polyimide film in the same manner as in Example 3 except that the thin long slit film A is processed by using a green film having a thickness of 11.0 μm and a width of 1200 mm as it is without being overlapped on both ends. However, a long polyimide film that could be continuously evaluated could not be obtained.

<Comparative Example 4>
A polyimide film in the same manner as in Example 4 except that a thin film having a thickness of 11.0 μm and a width of 1200 mm is used as it is without superimposing the narrow slit film B on both ends. Manufactured. The evaluation was performed in the same manner as in the Examples. The results are shown in Table 1.

  As described above, the film gripping at both side edges in the width direction of the film in the film end fixing type tenter in the imidizing step of the present invention is a polyamic acid film to be imidized and another narrow film. By pinning and fixing with a pin, the problem that the pin hole breaks into a long hole in the longitudinal direction and width direction of the film, the problem of the occurrence of curl, the occurrence of defects due to wrinkles and distortion, etc. is solved Therefore, it is possible to stably produce a long ultrathin polyimide film having a thickness of 7.5 μm or less. A long ultrathin polyimide film having a thickness of 7.5 μm or less can be used as a part of an electronic device or a machine part.

The outline of the pin sheet | seat which provided the stand in the width direction outer side of the pin which touches the film in the tenter type film processing machine which is one of the preferable aspects in this invention is shown. (A) is a front view, (b) is a side view. The outline of the pin sheet which contacts the film in the conventional tenter type film processing machine is shown. (A) is a front view, (b) is a side view. The outline of the pin insertion part of the film in the tenter type film processing machine which is one of the preferable embodiments in the present invention is shown.

Explanation of symbols

1: Brush roll 2: Pin 3: Pin base 4: Base 5; Support jig 6: Pressing roll 7: Polyimide precursor film

Claims (5)

  Polyamide acid obtained by reacting aromatic tetracarboxylic acids and aromatic diamines is cast and dried to obtain a polyimide precursor film, and the polyimide precursor film is placed outside in the width direction of the pin sheet, Manufacturing to obtain a polyimide film with a thickness of 7.5 μm or less, which is stabbed and fixed at both ends in the width direction of the film with pins arranged on a pin sheet, and imidized by a method of conveying and processing with a film end fixed type tenter A thin film prepared separately at both ends in the width direction of the polyimide precursor film, with a film end fixing type tenter in the process of imidizing and holding the film at both ends in the width direction of the film A polyimide film characterized in that it is performed by piercing and fixing a portion where a thin film is overlapped with a pin with a pin The method of production.   The production of a polyimide film according to claim 1, wherein the aromatic tetracarboxylic acid is at least one selected from pyromellitic acids and biphenyltetracarboxylic acids, and the aromatic diamine is at least one selected from p-phenylenediamines and diaminodiphenyl ethers. Method.   3. The method for producing a polyimide film according to claim 1, wherein the pin sheet on which the pins are installed has a portion higher than the pin base installed on the outside in the width direction.   The width | variety of a polyimide film is 500-10000 mm, and length is 100-100000 m, The manufacturing method of the polyimide film in any one of Claims 1-3.   The method for producing a polyimide film according to any one of claims 1 to 4, wherein the narrow film is a polyimide precursor film, and the width thereof is 20 to 80 mm.

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