JP5874184B2 - Coating die for solution casting and solution casting method - Google Patents

Description

  The present invention relates to a solution casting method for producing a polyimide film or the like, and more specifically, when casting a dope from a coating die, it prevents a resin pool from being generated at the lip tip of the coating die, thereby reducing coating defects. The present invention relates to a solution casting method for producing a non-existing film.

  As a method for producing a polymer film, a solution casting method is known. The solution casting method comprises a step of forming a coating film containing the polymer compound on a support by applying a solution (also referred to as a dope) obtained by dissolving the polymer compound in a solvent on the support; And at least a step of drying the coating film on the support. This solution casting method is widely practiced on various scales from a laboratory scale to an industrial scale (see Patent Document 1, Reference). ).

In this solution casting method, a film is obtained by continuously casting a dope from a coating die onto a casting support, followed by peeling, drying, and winding when forming a coating film.

By the way, when casting the dope from the coating die to the casting support, a resin pool due to residence of the dope may be formed at the tip of the die lip. If a resin puddle is formed at the tip of the die lip, streaks are generated from this point and the surface quality is impaired.

Therefore, conventionally, various means for preventing resin accumulation have been proposed. For example, a method of improving resin separation by supplying a solvent from the outside of both ends of the die lip (see Patent Document 2) or extrusion into a film shape. A method of uniformly applying the dope by sucking the surface of the resin solution that comes into contact with the support in a reduced-pressure chamber connected to a blower for vacuum suction through a suction duct (Patent Document 3) ) Is disclosed and proposed.
Also, an extrusion die has been proposed in which the length of the casting die on the take-up side is made shorter than that on the counter-take-up side and a step is provided so as not to cause streak-like defects (see Patent Document 4).
Controls the tensile stress applied to the ribbon-like dope at the tip of the lip of the casting die. Further, the pin angle of the ribbon-like dope to be cast (the streamline until the ribbon-like dope lands on the support and the opposite casting side) There has been proposed a film forming method that stabilizes the landing point and prevents streak-like defects by controlling the angle formed with the wall surface of the tip of the lip (see Patent Document 5).

JP 2003-260715 A Japanese Patent No. 2,687,260 Japanese Patent No. 3,827,268 Japanese Patent Laid-Open No. 9-207195 JP 2001-71338 A

However, the conventionally proposed methods for preventing resin accumulation cannot be sufficiently prevented depending on the characteristics of the dope.
Further, Patent Document 4 is a coating die limited to a thermoplastic resin, and since the properties of the resin are different from the solution film forming die of the present invention, the method described in Patent Document 4 is sufficient for the resin. It was found that stagnation could not be suppressed and a streak-like defect was generated.

  An object of the present invention is to provide a solution casting method that solves the above-described problems and prevents the dope from staying at the tip of the lip.

  Another object of the present invention is to provide a solution casting method for a film excellent in flatness and homogeneity, which is suitable as a base material or an insulating material for electronic parts by adding various additives to a polyamic acid solution. There is.

The present inventor has intensively studied the cause of the resin pool and found the cause of the resin pool. That is, the resin separation property at the tip of the coating die lip was poor, and as a result, a resin pool was generated.

The present invention has been made to solve the above problems, and the coating die for solution casting of the present invention is a coating die for solution casting in which a solution is cast by casting a solution, and has the following configuration. It is.
1. A solution-forming coating die for discharging a dope made of a solution containing at least one polymer, wherein the die lip tip is rounded (R-processed) into a circular shape, and both sides of the die A coating die for solution casting, wherein the R processing width of each lip is less than 0.0050 mm.
2. 1. A solution casting method, wherein the dope is discharged onto a support using the coating die for solution casting described in 1., and the dope solidified on the support is peeled off as a film and dried.
3. 1. The polymer is a polyamic acid solution obtained by reacting an aromatic tetracarboxylic acid and an aromatic diamine. The solution casting method described in 1.
4). 2. The aromatic diamine is an aromatic diamine having a benzoxazole structure . The solution casting method described .
5). 1. The reduced viscosity of the dope used is 3.0 dl / g or more and 5.0 dl / g or less. Or 3. The solution casting method described.

  According to the present invention, since the casting dope does not adhere to the tip of the die lip, it is possible to prevent the resin pool from being formed. As a result, product failure due to cleaning of the apparatus and resin adhesion does not occur, so that a film with good flatness can be produced efficiently. Because it is a film with good flatness and winding quality, there is no deviation in dimensions even when manufacturing electronic components at high temperatures and when electronic components are used at high temperatures, and it can contribute to lightness and thinness of electronic components etc. Industrial significance is great.

It is a cross-sectional schematic diagram of the coating die used for this invention.

The polymer used in the present invention includes aromatic tetracarboxylic acids (anhydrides, acids, and amide-bonded derivatives are collectively referred to as classes below) and aromatic diamines (amines and amide-bonded derivatives are collectively referred to as classes). It is particularly preferable to use a polyamic acid solution obtained by reacting the same as the above).

The polyamic acid solution in the present invention is not particularly limited as long as it is a polyimide acid solution obtained by polycondensation of aromatic diamines and aromatic tetracarboxylic acids, but preferably the following aromatic diamines: A preferred example is a combination of styrene and aromatic tetracarboxylic acids (anhydrides).
A. A combination of an aromatic diamine having a benzoxazole structure 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.

In particular, A. A combination for producing a polyamic acid solution having an aromatic diamine residue having a benzoxazole structure is preferred.
Benzene used in polyimide benzoxazole mainly composed of polyimide benzoxazole obtained by reacting aromatic diamines having a benzoxazole structure and aromatic tetracarboxylic anhydrides that can be particularly preferably used in the present invention. Examples of aromatic diamines having an oxazole structure include the following compounds.

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. These diamines may be used alone or in combination of two or more.
In the present invention, the aromatic diamine having the benzoxazole structure is preferably used in an amount of 70 mol% or more of the wholly aromatic diamine.

In the present invention, the following aromatic diamines may be used, but preferably one or two diamines having no benzoxazole structure exemplified below as long as they are less than 30 mol% of the total aromatic diamines. The polyamic acid or polyimide precursor powder used in combination is as described above.
Examples of such diamines include 4,4′-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, and bis [4- (3-aminophenoxy) phenyl]. Sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine.

3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl 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-Bi [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′-diamino-5,5′-diphenoxybenzophenone, 3,4′-diamino-4,5′-diphenoxybenzophenone, 3, 3'-diamino-4-phenoxybenzophenone, 4,4'-diamino-5-phenoxybenzophenone, 3,4'-diamino-4-phenoxybenzophenone, 3,4'-diamino-5'-phenoxybenzophenone, 3,3 '-Diamino-4,4'-dibiphenoxybenzophenone, 4,4'-diamino-5,5'-dibiphenoxybenzophenone, 3,4'-diamino-4,5'-dibiphenoxybenzophenone, 3,3'- Diamino-4-biphenoxybenzophenone, 4,4′-diamino-5-biphenoxybenzophenone, 3,4 -Diamino-4-biphenoxybenzophenone, 3,4'-diamino-5'-biphenoxybenzophenone, 1,3-bis (3-amino-4-phenoxybenzoyl) benzene, 1,4-bis (3-amino- 4-phenoxybenzoyl) benzene, 1,3-bis (4-amino-5-phenoxybenzoyl) benzene, 1,4-bis (4-amino-5-phenoxybenzoyl) benzene, 1,3-bis (3-amino) -4-biphenoxybenzoyl) benzene, 1,4-bis (3-amino-4-biphenoxybenzoyl) benzene, 1,3-bis (4-amino-5-biphenoxybenzoyl) benzene, 1,4-bis (4-Amino-5-biphenoxybenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) pheno Si] benzonitrile and some or all of the hydrogen atoms on the aromatic ring in the aromatic diamine are halogen atoms, alkyl groups having 1 to 3 carbon atoms or alkoxyl groups, cyano groups, or alkyl groups or alkoxyl group hydrogen atoms. Examples thereof include aromatic diamines substituted with a halogenated alkyl group having 1 to 3 carbon atoms partially or wholly substituted with a halogen atom or an alkoxyl group.

  The aromatic tetracarboxylic acids used in the present invention are preferably aromatic tetracarboxylic anhydrides. Specific examples of the aromatic tetracarboxylic acid anhydrides include the following.

These tetracarboxylic dianhydrides may be used alone or in combination of two or more.
In the present invention, one or two or more non-aromatic tetracarboxylic dianhydrides exemplified below may be used in combination as long as the total aromatic tetracarboxylic acids are less than 30 mol%. Examples of such tetracarboxylic acid anhydrides include butane-1,2,3,4-tetracarboxylic dianhydride, pentane-1,2,4,5-tetracarboxylic dianhydride, and cyclobutanetetracarboxylic acid. Acid 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 dianhydride 1-ethylcyclohexane -(1,2), 3,4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2,3), 3,4-tetracarboxylic dianhydride, 1,3-dipropylcyclohexane- 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-Dipropylcyclohexane-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 dianhydride and the like. These tetracarboxylic dianhydrides may 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 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 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 2.0 or more, more preferably 2.5 or more, and still more preferably 3.0 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.

The polyamic acid is applied to the support by being extruded from the coating die, cast on the traveling support, dried during traveling, peeled off, and sent to a tenter stretching machine.

This coating die is used when a single-layer film is formed, and this coating die has a single manifold. In this coating die, a T die is used. However, the present invention is not limited to this, and a die having another shape such as a coat hanger die may be used.

The die lip clearance in the solution casting method is usually set in the range of 0.05 mm to 3 mm, preferably in the range of 0.1 mm to 0.5 mm, but is not limited thereto.

The distance between the coating die and the support is usually set in the range of 1 mm to 10 mm, preferably in the range of 1.5 mm to 5 mm, but is not limited thereto.

The present invention is characterized by the shape of the tip of the die lip. That is, conventionally, the accuracy of the edge R width at the tip of the lip has not been specified. In the present invention, the leading edge R width is preferably R = 0.050 mm or less. Preferably, R is 0.0030 mm or less, and more preferably R is 0.0015 mm or less. The lower limit is not limited, but is actually about 0.0005 mm.
The R processing method is not particularly limited as long as it is a method capable of achieving the above accuracy, and polishing by mechanical processing, handling, etc. can be applied according to a conventional method.

The casting speed v is usually set in the range of 0.1 m / min to 5.0 m / min, preferably in the range of 0.5 m / min to 2.0 m / min, but is not limited thereto. Is not to be done.

The width of the die can be appropriately selected according to the product width and is not particularly limited, but is preferably 300 mm or more and 2000 mm or less.

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.

  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.

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.)

<Example 1>
(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.

Using the polyamic acid solution A, the edge R width of the leading end of the take-up side lip is R = 0.0013 mm on the non-slip surface of the polyethylene terephthalate film A-4100 (manufactured by Toyobo Co., Ltd.). 0.0012 mm) was cast as a single layer (using a coating width of 1240 mm and a backup roll with a roundness of 2 (μm)). As a result, no resin pool was seen, and it was possible to form a coating film with good coating quality. The results are shown in Table 1.

<Example 2>
Example 1 except that the polyamic acid solution A was used to cast a single layer using a coating die in which the edge R width at the tip of the take-up side lip was R = 0.828 mm (counter take-off side: 0.0029 mm) In the same manner as above, a cast film was formed. As a result, no resin pool was seen, and it was possible to form a coating film with good coating quality. The results are shown in Table 1.

<Example 3>
Example 1 except that the polyamic acid solution A was used to cast a single layer using a coating die in which the edge R width at the tip of the take-up side lip was R = 0.445 mm (counter take-off side: 0.0043 mm) In the same manner as above, a cast film was formed. As a result, no resin pool was seen, and it was possible to form a coating film with good coating quality. The results are shown in Table 1.

<Example 4>
(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.

A cast film was formed in the same manner as in Example 1 except that the polyamic acid solution B was used. As a result, no resin pool was seen, and it was possible to form a coating film with good coating quality. The results are shown in Table 1.

<Example 5>
(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.

A cast film was formed in the same manner as in Example 1 except that the polyamic acid solution C was used. As a result, no resin pool was seen, and it was possible to form a coating film with good coating quality. The results are shown in Table 1.

<Comparative Example 1>
Example except that the polyamic acid solution A was used to cast a single layer using a coating die having an edge R width at the tip of the take-up side lip of R = 0.0081 mm (counter take-off side: 0.0083 mm) In the same manner as in No. 1, a cast film was formed. As a result, it was found that a resin pool was found on the entire lip and formed a coating film with poor coating quality in which many coating streaks were generated. The results are shown in Table 1.

<Comparative Example 2>
A cast film was formed in the same manner as in Example 1 except that the polyamic acid solution B was used and a single-layer cast was performed using a coating die having an edge R width at the lip tip of R = 0.0081 mm. . As a result, it was found that a resin pool was found on the entire lip and formed a coating film with poor coating quality in which many coating streaks were generated. The results are shown in Table 1.

<Comparative Example 3>
A cast film was formed in the same manner as in Example 1 except that the polyamic acid solution C was used and a single layer was cast using a coating die having an edge R width at the lip tip of R = 0.0081 mm. . As a result, it was found that a resin pool was found on the entire lip and formed a coating film with poor coating quality in which many coating streaks were generated. The results are shown in Table 1.

The evaluation methods of physical properties in the examples for the following polyimide film creation are as follows.
1. Thickness and thickness variation of polyimide film The thickness in the flow direction (MD direction) and the width direction (TD direction) was measured using a micrometer (Millitron 1254D, manufactured by Finelfu). The MD direction was 1000 mm at intervals of 50 mm, and the full width was evaluated at intervals of 10 mm in the TD direction.
The measurement of thickness spots in the present invention is based on the following formula.
Thickness unevenness (%) = ((maximum value−minimum value) / average thickness) × 100

2. 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.

3. 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 Measurement load; (Film thickness (μm)) / 25.1 × 1.73 g
4). For the measurement of the die lip tip (edge) R processing width edge R width of the coating die, the line width of the edge R at the tip is measured using a KEYENCE microscope (VW-6000). The edge R width was calculated.
(Edge R width) = (Bright line width) / √2 (Formula 1)

<Example 6>
The cast film obtained under the casting conditions performed in Example 1 was dried at 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 a green film having a thickness of 18 μm and a width of 1200 mm. Both ends were gripped with a pin tenter under the conditions of a pin sheet, brush roll, presser roll, and support 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 both ends of the film were cut off with the slitter, and it rolled up in roll shape, and obtained the polyimide film A which exhibits brown. Table 2 shows the measurement results such as the conveyance state during the heat treatment and the characteristics of the obtained polyimide film.

<Example 7>
A polyimide film B was obtained in the same manner as in Example 5 except that the cast film obtained under the casting conditions performed in Example 2 was used.
The evaluation was made in the same manner. The results are shown in Table 2.

<Example 8>
A polyimide film C was obtained in the same manner as in Example 5 except that the cast film obtained under the casting conditions performed in Example 3 was used.
The evaluation was made in the same manner. The results are shown in Table 2.

A solution-forming coating die for discharging a dope made of a solution containing at least one polymer, wherein the die lip tip is rounded into a circular shape (R processing), the R processing width By performing solution casting using a coating die for solution casting characterized by a thickness of less than 0.0050 mm, stable production becomes possible, and the resulting film has poor quality and poor quality. The easy problem can be solved, and it can contribute to the improvement of dimensional accuracy and quality of electronic parts such as a flexible circuit using a film obtained by adopting this method.

Claims (5)

A solution-forming coating die for discharging a dope made of a solution containing at least one polymer, wherein the die lip tip is rounded (R-processed) into a circular shape, and both sides of the die A coating die for solution casting, wherein the R processing width of each lip is less than 0.0050 mm. Using the coating die for solution casting according to claim 1, the dope is discharged onto a support, and the dope solidified on the support is peeled off as a film and dried. Membrane method. The solution casting method according to claim 2, wherein the polymer is a polyamic acid solution obtained by reacting an aromatic tetracarboxylic acid with an aromatic diamine. 4. The solution film-forming method according to claim 3 , wherein the aromatic diamine is an aromatic diamine having a benzoxazole structure. 4. The solution casting method according to claim 2, wherein the dope used has a reduced viscosity of 3.0 dl / g or more and 5.0 dl / g or less.