JP5549360B2 - Method for producing polyimide film and polyimide film roll - Google Patents

Description

  The present invention relates to a polyimide film having good flatness and winding quality.

  As a method for producing a polymer film, a casting film forming method is known. The casting film forming method comprises a step of forming a coating film containing the polymer compound on the support by applying a solution obtained by dissolving the polymer compound in a solvent on the support; And a process for drying a coating film, and this casting film forming method is widely implemented on various scales from a laboratory scale to an industrial scale (see Patent Document 1).

When the casting film forming method is performed on an industrial scale, a mirror-polished metal roll or a so-called endless belt is used as a support (see Patent Document 2).
The method using a metal belt as the support is widely used in the casting film forming method because it is easy to lengthen the drying process length after coating. In order to increase the productivity of the casting film forming method, it is effective to increase the drying speed. To that end, it is conceivable to take measures such as increasing the drying temperature and increasing the amount of drying air. However, if the drying temperature is too high, the volatilization rate of the solvent at the time of drying may increase so that bubbles may be generated. Further, if the amount of drying air is excessively large, wind-like wrinkles may be generated on the surface of the coating film, and undulation of the entire coating film may be generated due to vibration caused by the wind of the support belt itself. Thus, the above-mentioned means are not necessarily effective from the viewpoint of the quality of the obtained film.

Thus, since it was difficult to improve both productivity and film quality in the casting film forming method, conventionally, when producing a high-quality film, the drying speed is reduced, in other words, I had to dry it slowly over a long period of time. In addition, acetic anhydride and an organic amine compound are added to the polyamic acid solution, and then the obtained solution is cast on a support in an extremely dry atmosphere in which the water concentration is 1 to 4000 ppm. And heated together with the support to obtain a gel-like film, and the obtained gel-like film is separated from the support and washed as necessary, and then simultaneously biaxially stretched or sequentially biaxially stretched to obtain the obtained biaxial A method for producing a polyimide film (see Patent Document 3) is proposed in which a stretched film is washed as necessary to remove the solvent and then subjected to a heat treatment to form a biaxially oriented polyimide film.

  It is known that the thickness of the film to be produced is managed using an on-line thickness gauge. Also, there are various types of sensors, and Patent Document 4 has an example in which the film thickness is measured by an infrared method. However, Patent Document 4 is limited to a polyimide containing a polyimide containing a functional group having a characteristic infrared absorption wavelength as a main component, and does not disclose a technique applicable to all polyimide films.

JP 2003-260715 A JP 09-207151 A JP 2004-338255 A WO 2006/64700

  The present invention is a polyimide film excellent in flatness and homogeneity, which is suitable as a base material or insulating material for electronic parts, and excellent in heat resistance that does not change even when subjected to high-temperature treatment, and has a variation in weight per unit area. An object of the present invention is to provide a method for producing a polyimide film that solves the problem of being large, is excellent in dimensional stability with good flatness and good winding quality, and is applicable to all polyimide films.

That is, this invention is based on the following structures.
1. Method for producing polyimide film obtained by casting dope, which is a polyamic acid solution obtained by reacting tetracarboxylic acids with aromatic diamines having a benzoxazole structure , coating film formation, drying, and heat treatment (imidization) Per unit area of the resulting polyimide film by measuring and managing the weight per unit area after coating film formation and before drying by absorption of the solvent contained therein with an infrared absorption thickness gauge The polyimide film is produced by controlling the weight of the polyimide film.
2.1. The method for producing a polyimide film according to 2.1, wherein the polyamic acid solution is measured and managed with the infrared absorption thickness meter within an infrared wavelength range of 1 μm to 5 μm. The manufacturing method of the polyimide film which controlled the weight per unit area so that it might become 0.1 g / m <2> or less and 1.0 g / m <2> or less immediately after casting.
3 . It is a film roll which wound up the polyimide film manufactured with the manufacturing method in any one of 1-2 in roll shape, Comprising: The polyimide film roll which has width 500mm or more and length 100m or more.

  The step of storing the polyimide precursor solution (polyamic acid solution) of the present invention in a supply tank, the step of feeding until it is cast and applied on a support through piping, the step of casting, applying and drying on a support In the casting film-forming polyimide film manufacturing method having at least, a polyimide film in which the weight per unit area of the coating film is controlled to 0.1 g / m 2 or more and 0.5 g / m 2 or less, the thickness of the coating film is included therein It is a polyimide film manufacturing method characterized by controlling the thickness of the obtained polyimide film by measuring and managing the absorption of the solvent contained in the infrared absorption type thickness meter, and depending on the thickness unevenness It is possible to eliminate the problems that are likely to cause poor quality such as a decrease in yield and sagging. As a result, the polyimide film produced and the polyimide with excellent dimensional stability are obtained. A film is obtained, and this polyimide film is a film with excellent stability at high temperatures, particularly dimensional stability, and good flatness and winding quality. Therefore, it is dimensional even when manufacturing electronic components at high temperatures and when electronic components are used at high temperatures. It can contribute to the lightness and thinness of electronic parts and the like, and has great industrial significance.

The polyimide film of the present invention includes tetracarboxylic acids (anhydrides, acids, and amide bond derivatives generically referred to as classes below) and diamines (amines and amide bond derivatives generically referred to as classes below). It is a polyimide film obtained by a method of casting, drying and heat treatment (imidization) 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.

The polyimide film in the present invention is not particularly limited, but a combination of aromatic tetracarboxylic acids and aromatic diamines is preferable, and the following aromatic diamines and aromatic tetracarboxylic acids (anhydrides) Is a more preferred example.
A. A combination of an aromatic diamine having a benzoxazol skeleton and an aromatic tetracarboxylic acid.
B. A combination of an aromatic diamine having a diaminodiphenyl ether skeleton and an aromatic tetracarboxylic acid having a pyromellitic acid skeleton.
C. A combination of an aromatic diamine having a phenylenediamine skeleton and an aromatic tetracarboxylic acid having a biphenyltetracarboxylic acid skeleton.
D. A combination of one or more of the above ABCs.
Of these, the combination of A. is preferable.

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. Examples of the diamine having a benzoxazol skeleton in the present invention include the following. Although the diamine shown by a specific example is mentioned, It is preferable to use these diamines 70 mol% or more of all the diamines, More preferably, 80 mol% or more.
Specific examples of aromatic diamines having a benzoxazole structure include the following.

これらの中でも、合成のし易さの観点から、アミノ（アミノフェニル）ベンゾオキサゾールの各異性体が好ましい。ここで、「各異性体」とは、アミノ（アミノフェニル）ベンゾオキサゾールが有する２つアミノ基が配位位置に応じて定められる各異性体である（例；上記「化１」〜「化４」に記載の各化合物）。
また、上記以外の芳香族ジアミン類としては、下記の芳香族ジアミン類が本発明において全アミンの３０モル％未満、より好ましくは２０モル％未満であれば使用できる。

Among these, amino (aminophenyl) benzoxazole isomers are preferable from the viewpoint of ease of synthesis. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, the above “formula 1” to “formula 4”). Each compound described in the above.
Moreover, as aromatic diamines other than the above, the following aromatic diamines can be used if they are less than 30 mol%, more preferably less than 20 mol% of all amines in the present invention.

4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-amino Phenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3 , 3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,3′-di Mino diphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone.

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-aminopheno) Cis) phenyl] butane, 1,3-bis [4- (4-aminophenoxy) phenyl] butane, 1,4-bis [4- (4-aminophenoxy) phenyl] butane, 2,2-bis [4- (4-Aminophenoxy) phenyl] butane, 2,3-bis [4- (4-aminophenoxy) phenyl] butane, 2- [4- (4-aminophenoxy) phenyl] -2- [4- (4- Aminophenoxy) -3-methylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3-methylphenyl] propane, 2- [4- (4-aminophenoxy) phenyl] -2- [ 4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- 4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane.

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 Sulfoxides, 4,4'-bis [3- (4-aminophenoxy) benzoyl] diphenylether, 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'-diamino-5,5'-diphenoxybenzophenone, 3,4'-diamino-4,5'- Diphenoxybenzophenone, 3,3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'- Phenoxybenzophenone, 3,3′-diamino-4,4′-dibiphenoxybenzophenone, 4,4′-diamino-5,5′-dibiphenoxyben Phenone, 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-biphenoxy) Benzoyl) 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, aromatic diamines having a benzoxazole structure, and fragrances of the above aromatic diamines Some or all of the hydrogen atoms on the ring are substituted with halogen atoms, or some or all of the hydrogen atoms of the alkyl group or alkoxy group having 1 to 3 carbon atoms, cyano group, or alkyl group or alkoxy group are substituted with halogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms or an alkoxy group.
These aromatic diamines may be used alone or in combination of two or more.

  The aromatic tetracarboxylic acids used in the present invention are preferably aromatic tetracarboxylic anhydrides, and the following chemical formulas 14 and 15 are preferably used in an amount of 70 mol% or more of the total acid component, and 80 mol%. More preferably used. Specific examples of those that can be used in addition to these include the following, but these are used in an amount of less than 30 mol%, more preferably less than 20 mol% of the total acid component.

これらの芳香族テトラカルボン酸無水物類は単独でも二種以上を用いることも可能である。

These aromatic tetracarboxylic anhydrides can be used alone or in combination of two or more.

In the present invention, the non-aromatic tetracarboxylic dianhydrides exemplified below may be used alone or in combination of two or more if less than 30 mol%, preferably less than 10 mol% of the total tetracarboxylic acid. I do not care. Examples of the non-aromatic tetracarboxylic dianhydrides used include butane-1,2,3,4-tetracarboxylic dianhydride and pentane-1,2,4,5-tetracarboxylic dianhydride. , Cyclobutanetetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, cyclohex-1-ene- 2,3,5,6-tetracarboxylic dianhydride, 3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3- Ethylcyclohexane-3- (1,2), 5,6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohex-1-ene-3- (1,2), 5,6-tetracarboxylic Acid dianhydride, 1-ethylsic Hexane-1- (1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-di Propylcyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2 .1] Heptane-2,3,5,6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropyl Cyclohexane-1- (2,3), 3- (2,3) -tetracarboxylic dianhydride, dicyclohexyl-3,4,3 ′, 4′-tetracarboxylic dianhydride, bicyclo [2.2. 1] Heptane-2,3,5,6-tetracarboxylic Dianhydride, bicyclo [2.2.2] octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6 -Tetracarboxylic dianhydrides and the like. These non-aromatic tetracarboxylic dianhydrides can be used alone or in combination of two or more.

  The solvent used when polyamic acid is obtained by polymerizing aromatic diamines and aromatic tetracarboxylic acid anhydrides is particularly limited as long as it dissolves both the raw material monomer and the polyamic acid to be produced. 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, etc., among which N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide 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 weight 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 weight 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. 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 closure method in which a dehydrating agent is contained and 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 performed at 150 to 250 ° C. for 3 to 20 minutes and then heat treatment at 350 to 500 ° 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, film) formed on the support may be peeled off from the support before it is completely imidized. The film may be peeled after imidization.

Although the thickness of the polyimide film in this invention is not specifically limited, Preferably they are 3 micrometers or more and 100 micrometers or less.
It is difficult to industrially produce a long film of a polyimide film, and these obtained polyimide films have extremely large thickness unevenness, for example, the thickness of a commercially available 7.5 μm polyimide film. The unevenness is about 25%, and there is a problem in quality in electronic parts and the like that require dimensional accuracy. The present invention intends to solve these problems.
The thickness of the polyimide film can be easily controlled by the amount of the polyamic acid solution applied to the support and the concentration of the polyamic acid solution. In particular, the spots tend to increase as the film thickness decreases.
The polyimide film of the present invention is preferably provided with a lubricant in the polyimide to give fine irregularities on the film surface to improve the slipping property of the film.
As the lubricant, inorganic or organic fine particles having an average particle diameter of about 0.03 μm 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, these polyimide films are obtained by the following methods: aromatic tetracarboxylic acids (anhydrides, acids, and amide bond derivatives are collectively referred to as the following) and aromatic diamines (amine and amide bonds). A polyimide film obtained by casting, coating film formation, drying, heat treatment (imidization) of a dope which is a polyamic acid solution obtained by reacting all of the functional derivatives generically referred to hereinafter as the same), In the infrared wavelength range of 1 μm or more and 5 μm or less, immediately after casting the polyamic acid solution, 0.1 g / m ² or more and 1.0 g / m ² or less, more preferably 0.1 g / m ² or more. a polyimide film with a controlled weight per unit area so that 0.5 g / m ^2, an infrared absorbing absorption of solvents contained a weight per unit area of the coating film therein Per unit area of the polyimide film obtained by measuring and managing with a thickness gauge of the formula (made by Kurabo Industries, trade name RX-100 (transmission type) or RX-200 (reflection type), measurement area 7 × 13 mm)) It is a polyimide film characterized by controlling the weight, and the coating film is obtained by extruding a dope, which is a polyamic acid solution, from a die or the like. Conventionally, the amount of the polyimide is checked by checking the absorption of the polyimide in the dope. In the present invention, by detecting the absorption of the solvent in the dope (infrared absorption method), it has been detected more accurately and accurately. it can. Since this does not consider the absorption of the polymer itself, the same measurement is possible even if other materials are used in the same solvent, and there is an advantage that it can be used in a wide range. Moreover, since the amount of the solvent is larger than that of the polymer, the detection sensitivity is good and the measurement accuracy is high.
Note that the above “measurement / management” means, for example, that the thickness immediately after resin application is measured using an on-line thickness meter, and if it is deviated from a predetermined target value This means that the thickness is controlled by applying correction and adjusting to the target value.

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 the 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.
The absorption peak to be detected is not particularly limited as long as it is an absorption band specific to any solvent in the infrared wavelength region, but for this measurement, an absorption band specific to the solvent in the near infrared region was selected.
In addition, the measurement environment is not particularly limited, but the solvent group used is very hygroscopic, so there is a problem if the temperature and humidity can be controlled to some extent in an environment equipped with air conditioning equipment. There is no. Specifically, the temperature is 10 ° C. or higher and 40 ° C. or lower, preferably 20 ° C. or higher and 30 ° C. or lower. The humidity is 5% Rh to 95% Rh, preferably 25% Rh to 65% Rh.
Also, in the solution casting method with reaction, the film thickness is controlled by measuring the thickness at the final stage and applying feedback during casting or the thickness of the intermediate (dried precursor film). Although the method of measuring and giving feedback at the time of casting was adopted, accurate values cannot be expected due to differences in the dry state. These methods are difficult online and often result in reduced productivity. By measuring the thickness using solvent absorption instead of polyimide in the infrared absorption method, it is possible to control the thickness immediately after coating in the solution film formation method with reaction, speeding up feedback and reducing loss. Less efficient film formation is possible.

In the present invention, the above method is indispensable. In this method, (1) film end gripping at both side end portions in the width direction of the film is sandwiched between a number of clips or provided on a pin sheet. It is made by piercing with a large number of pins, and imidized by a tenter method in which the film is conveyed in a state of being stretched in the width direction and / or the conveying direction to obtain a polyimide film.

Moreover, in the present invention, when casting a polyamic acid solution on a support, by using a backup roll having a high roundness, the thickness unevenness at the time of coating is reduced, particularly the thickness unevenness in the MD direction is reduced. The roundness of the backup roll that can be expressed is expressed by the amount of eccentricity of the roll described below, and the amount of eccentricity (μm) is preferably 3 or less, and particularly preferably 2 or less.
The effect of reducing thickness unevenness on the film by reinforcing the pin portion is effective in suppressing thickness unevenness in the TD direction.
In these methods, a method of controlling the eccentricity of the backup roll of the coater to 3 (μm) or less, preferably 2 (μm) or less is preferable. The measurement of the eccentric amount of the backup roll is a value obtained by abutting a dial gauge on the end surface of the backup roll and measuring the displacement amount of the gauge at the left end surface, the right end surface, and the center portion of the backup roll.
More specifically, the dial gauge uses a capacitance type dial gauge (manufactured by Ozaki Seisakusho, trade name PEACOCK, model DG-205, measurement range 25 mm, minimum display amount 0.001 mm, accuracy 0.003 mm).
The dial gauge is fixed to the roll frame with a magnetic chuck. Eccentricity measurement is repeated 6 times for each portion divided into 8 in the circumferential direction. The measurement should be performed in an environment where temperature and humidity are stable and there is no vibration. The roll driving speed is 1 m / min.
Measurement is performed both with and without film. When there is a film, the film tension is about 100N.
Control of the eccentric amount of the backup roll is performed by removing the plating of the backup roll when the eccentric amount is large, and performing the control of the eccentric amount through at least the processes of cutting and polishing, and polishing the backup roll when the eccentric amount is small. Perform machining to control the amount of eccentricity.
The material of the backup roll is preferably carbon steel for mechanical structure (STKM, S45C).
The surface treatment of the backup roll is preferably hard chrome plating. The diameter of the roll is preferably about φ200 to 400. It is preferable to use a bearing having a dimensional accuracy and a rotational accuracy of a grade 4 or higher of the accuracy grade specified in JIS B1514.

The thickness unevenness of the polyimide film in the present invention is preferably 10% or less, more preferably 5% or less, and still more preferably 3% or less. When this thickness unevenness exceeds 10%, when this film is used as a heat-resistant insulating material for an electronic component, it causes a defect in the dimensional accuracy of the electronic component, and further has many problems in the electrical quality of the electronic component. .
The measurement of thickness spots in the present invention is as follows.
Thickness unevenness (%) = ((maximum value−minimum value) / average thickness) × 100
About the measurement, it measured to the width direction and the longitudinal direction.
For the width direction (TD), the entire width was measured at intervals of 1 cm in the width direction, and the average, maximum value, and minimum value were calculated and calculated using the above formula.
About the longitudinal direction (MD), it measured for 5 m at intervals of 5 cm in the longitudinal direction, and the average, maximum value, and minimum value were calculated and calculated using the above formula.

  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. Specimen obtained by cutting a polyimide film to be measured into a strip 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 Corp., Autograph (registered trademark), 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, 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
Initial load: 34.5 g / mm ²
Temperature rise start temperature: 25 ° C
Temperature rising end temperature: 400 ° C
Temperature increase rate: 5 ° C / min
Atmosphere: Argon

(Preliminary dispersion of inorganic particles)
1.22 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by mass of N-methyl-2-pyrrolidone, the wetted part of the container, and the infusion pipe are austenitic stainless steel The mixture was placed in a container of SUS316L and stirred with a homogenizer T-25 basic (manufactured by IKA Labortechnik) at a rotation speed of 1000 rpm for 1 minute to obtain a preliminary dispersion. The average particle size in the preliminary dispersion was 0.11 μm.
(Preparation of polyamic acid solution)
A nitrogen inlet tube, a thermometer, a liquid contact part of a container equipped with a stirring rod, and a pipe for infusion were substituted with nitrogen in the reaction container made of austenitic stainless steel SUS316L, and then 223 parts by mass of 5-amino-2- ( p-Aminophenyl) benzoxazole was added. Next, 4000 parts by mass of N-methyl-2-pyrrolidone was added and completely dissolved, and then the preliminary dispersion obtained above was added with 420 parts by mass and 217 parts by mass of pyromellitic dianhydride. When the mixture was stirred at ° C. for 24 hours, a brown viscous polyamic acid solution A was obtained. The reduced viscosity (ηsp / C) was 3.8 dl / g.

<Example 1>
The polyamic acid solution A was coated on a non-slip surface of a polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.) using a comma coater (coating width 1240 mm, backup roll roundness of 2 ( μm)).
Infrared absorption thickness gauge (made by Kurabo Industries, product name RX-100 (transmission type) or RX-200 (reflection type)) installed between the comma coater and the dryer (before the coating film enters the dryer) , Measurement area 7 × 13 mm) was used to measure the weight per unit area online, and the difference between the target weight and the obtained weight was calculated.
The coating film that entered the dryer was dried at 90 ° C. for 7.5 minutes. The polyamic acid film which became self-supporting after drying was peeled off from the support and cut at both ends to obtain a green film having a thickness of 8.2 μm and a width of 1200 mm. A pin sheet, a brush roll, a pressing roll, a support jig, and the like, while a 35 mm wide narrow slit film A (adhesive narrow slit film A) is superimposed on both side ends of the obtained green film. Under the conditions, both ends were held with a pin tenter 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 weight difference per unit area shown in Table 1 is the difference between the measured weight and the target weight per square meter (set from experience values).
The flatness, winding quality 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.
A unit having a space that is not vacant per unit area to ¼, ¼, ¼ to ½, and ½ or more, x.
The state of the product roll, in which no wrinkles enter the wound roll and no streak or end face deviation occurs, is defined as a good winding quality state.
The roll surface and the end surface are visually observed. The case where there is no wrinkle and there is no end shift is ○, the wrinkle is 1 to 2, the shift is within 1 mm and the total is less than 20%, and the wrinkle is 3 As described above, the case where the deviation amount is 1 mm or more and 20% or more of the whole is taken as x.
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. 10 or more connected items x × 10 to 3 items △ 2 or less items ○

<Examples 2-3>
Polyamide acid solution A was used, and polyimide film B and polyimide film C were obtained in the same manner as in Example 1 except for the coating thickness.
The evaluation was made in the same manner. The results are shown in Table 1.

<Comparative Example 1>
Except for measuring the film thickness by measuring the thickness of the dried intermediate (dried precursor film) with an infrared absorption thickness gauge and applying feedback during casting,
A polyimide film D was obtained in the same manner as Example 1. The evaluation was made in the same manner. The results are shown in Table 2.

<Comparative example 2>
Except that the film thickness was controlled by measuring the thickness after the imidization reaction with an infrared absorption type thickness meter and applying feedback at the next casting,
A polyimide film E was obtained in the same manner as in Example 1. The evaluation was made in the same manner. The results are shown in Table 2.

<Comparative Example 3>
Except that the film thickness was controlled by peeling off the dried intermediate (dried precursor film), measuring it offline with a contact-type thickness meter, and applying feedback during casting.
A polyimide film F was obtained in the same manner as in Example 1. The evaluation was made in the same manner. The results are shown in Table 2.

<Comparative Example 4>
Except that the film thickness was controlled by a method in which the thickness after the imidization reaction was measured off-line with a contact-type thickness meter and feedback was applied at the next casting,
A polyimide film G was obtained in the same manner as in Example 1. The evaluation was made in the same manner. The results are shown in Table 2.

<Comparative Example 5>
(Preliminary dispersion of inorganic particles)
7.6 parts by weight of amorphous silica spherical particle 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, wetted part of container equipped with stirring rod, and infusion pipe were replaced with nitrogen in a 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 the mixture was stirred at 5 ° C. for 5 hours, a brown viscous polyamic acid solution B was obtained. The reduced viscosity (ηsp / C) was 3.7 dl / g. Using the polyamic acid solution B, a polyimide film H was obtained in the same manner as in Example 1. The evaluation was made in the same manner. The results are shown in Table 2.

<Comparative Example 6>
(Preliminary dispersion of inorganic particles)
3.7 parts by mass of amorphous silica spherical particles Seahoster KE-P10 (manufactured by Nippon Shokubai Co., Ltd.), 420 parts by mass of N-methyl-2-pyrrolidone, and the infusion part 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, 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 C. The reduced viscosity (ηsp / C) was 4.5 dl / g. Using the polyamic acid solution C, a polyimide film I was obtained in the same manner as in Example 1. The evaluation was made in the same manner. The results are shown in Table 2.

(Feedback time)
If the thickness of the film being produced exceeds the control width, it will be necessary to adjust the thickness so that it falls within the control width. Time is defined as feedback time. The shorter this time, the less loss.

Aromatic tetracarboxylic acids of the present invention (anhydrides, acids, and amide bond derivatives are collectively referred to as classes below) and aromatic diamines (amines and amide bond derivatives are collectively referred to as classes below) A polyimide film obtained by casting, coating film formation, drying, heat treatment (imidization) of a dope, which is a polyamic acid solution obtained by reacting with the same), and having an infrared wavelength region of 1 μm to 5 μm Within the range, immediately after casting the polyamic acid solution, a polyimide film in which the weight per unit area is controlled to be 0.1 g / m 2 or more and 0.5 g / m 2 or less can be stably produced and obtained. The polyimide film has excellent uniformity with few thickness spots, and can solve the problems that are likely to cause quality defects due to wrinkles and distortions. This method can contribute to improvement in dimensional accuracy and quality of electronic parts such as flexible circuits using a polyimide film obtained.

Claims (3)

Method for producing polyimide film obtained by casting dope, which is a polyamic acid solution obtained by reacting tetracarboxylic acids with aromatic diamines having a benzoxazole structure , coating film formation, drying, and heat treatment (imidization) Per unit area of the resulting polyimide film by measuring and managing the weight per unit area after coating film formation and before drying by absorption of the solvent contained therein with an infrared absorption thickness gauge The polyimide film is produced by controlling the weight of the polyimide film. 2. The method for producing a polyimide film according to claim 1, wherein the polyamic acid solution is measured and controlled with the thickness meter of the infrared absorption method within an infrared wavelength range of 1 μm to 5 μm. The manufacturing method of the polyimide film which controlled the weight per unit area so that it might become 0.1 g / m <2> or less and 1.0 g / m <2> or less immediately after casting. It is a film roll which wound up the polyimide film manufactured with the manufacturing method in any one of Claims 1-2 in roll shape, Comprising: The polyimide film roll which has width 500mm or more and length 100m or more.