JP2007069562A - Manufacturing method of polymer film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a polymer film, especially a polyimide film which has no coating streaks, that is, a surface characteristic suitable as a substrate film of an electronic component, has the surface nature free from a surface defect like a crater, and carries a mechanical characteristic and heat resistance. <P>SOLUTION: The flow casting film making type high polymer film manufacturing method comprises a process in which a polymer solution or a precursor solution of a polymer is applied on a support, dried to obtain a film which keep an atmosphere of an coated section at 15-30°C of a drying gas atmosphere having a dew point controlled in a range of ≥5°C and <15°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a polyimide benzoxazole film, in particular, a polymer film excellent in mechanical properties and low thermal expansibility, particularly a polyimide film.

As a method for producing a polymer film, a casting film forming method is known. The casting film forming method includes 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).
JP 2003-260715 A

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.
JP 09-207151 A

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.
JP 2004-338255 A

  The present inventors obtain a polyimide benzoxazole film having a benzoxazole structure in a thin polymer film excellent in mechanical properties, CTE properties, etc., particularly in a polyimide film, by a film casting film-forming polymer film manufacturing method, It is another object of the present invention to provide a production method for producing on an industrial scale.

As a result of intensive studies, the present inventors have completed the following invention. That is, this invention consists of the following structures.
1. In the casting film-forming polymer film manufacturing method including a step of applying a polymer solution or a polymer precursor solution onto a support and drying to obtain a film, the polymer solution or polymer precursor A method for producing a polymer film, wherein the atmosphere of an application part for applying a solution on a support is a dry gas atmosphere of 15 to 30 ° C controlled to a dew point of 5 ° C or higher and lower than 15 ° C.
2. The polymer precursor solution is a polyamic acid solution obtained from a diamine containing an aromatic diamine having a benzoxazole structure and a tetracarboxylic acid anhydride containing an aromatic tetracarboxylic acid anhydride. The manufacturing method of the polymer film of description.
3. 1. The temperature of the coating part is controlled to ± 2 ° C. Or 2. The manufacturing method of the polymer film in any one.
4). 1 above. ~ 3. A method for producing a polymer film, comprising subjecting a polymer precursor film obtained by any one of the production methods to a high-temperature heat treatment reaction without stretching.
5. 1 above. ~ 4. The manufacturing method of the polymer film whose polymer film obtained by the manufacturing method in any one is a polyimide benzoxazole film, and the thickness of this film is the range of 1-50 micrometers.

  In the casting film-forming polymer film manufacturing method comprising the steps of applying a polymer solution or a polymer precursor solution onto a support and drying to obtain a film of the present invention, When the application of the molecular precursor solution on the support is carried out in the application part, the application part is a dry gas atmosphere of 15 to 30 ° C. controlled at a dew point of 5 ° C. or more and less than 15 ° C. A method for producing a polymer film, in which a polymer precursor solution is obtained from a diamine containing an aromatic diamine having a benzoxazole structure and a tetracarboxylic acid anhydride containing an aromatic tetracarboxylic acid anhydride. The method for producing a polymer film, which is a solution of polyamic acid, causes roughness of the film surface (occurrence of crater-like surface irregularities) and coating streaks due to water dew on the film surface at the coating part. It is can be industrially very effective to obtain a polymer film excellent in film without surface properties.

In the present invention, examples of the polymer film include films made of a high melting point or non-melting polymer such as polyamideimide, polyimide, cellulose acetate, polycarbonate, polyvinyl chloride, and polyaramid.
The polymer film of the present invention is produced by a so-called casting film-forming polymer film production method in which a solution containing these polymers is cast, dried and heat-treated to form a film.
Examples of the solvent used for the solution containing these polymers include N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methylene chloride, tetrahydrofuran, methanol, and metacresol.
Examples of the polymer solution preferably used in the present invention include N-methyl-2-pyrrolidone solution of polyamideimide, N, N-dimethylacetamide solution, N-methyl-2-pyrrolidone solution of polyamide acid which is a polyimide precursor, N , N-dimethylacetamide solution, N-methyl-2-pyrrolidone solution of solvent-soluble polyimide, N, N-dimethylacetamide solution, methylene chloride solution of cellulose acetate, methanol solution, methylene chloride solution of polycarbonate, metacresol solution, Examples include a tetrahydrofuran solution of polyvinyl chloride and an N-methyl-2-pyrrolidone solution of aramid.
The method for producing the polymer film of the present invention is particularly suitable for N-methyl-2-pyrrolidone solution of polyamic acid, which is a polyimide precursor, N-methyl-2-pyrrolidone solution of N, N-dimethylacetamide solution, or polyamic acid, which is a precursor of polyimide benzoxazole. The present invention can be most preferably applied in the case of a casting film forming method using a solution of methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide or the like.
Hereinafter, a polyimide film, particularly a polyimide benzoxazole film comprising a combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid will be described in detail, but the invention 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. (Ring-opening) A solution of polyamic acid as a polyimide precursor is obtained by subjecting it to a polyaddition reaction, and then a polyimide precursor film (hereinafter also referred to as a green film) is formed from this polyamic acid solution, followed by drying, heat treatment, It is produced by dehydration condensation (imidization). 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. Aromatic diamines with benzoxazole structure and aromatic tetracarboxylic acids
combination.
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 A, B and C.
Among these, A. A combination of an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid is a preferred embodiment.

<Aromatic diamines>
As aromatic diamines, aromatic diamines having a benzoxazole structure and some or all of the hydrogen atoms on the aromatic ring are substituted with halogen atoms, alkyl groups having 1 to 3 carbon atoms, alkoxyl groups, cyano groups, etc. And aromatic diamines. Here, some or all of the hydrogen atoms of the alkyl group or alkoxyl group may be substituted with a halogen atom. Aromatic diamines having a benzoxazole structure may be used alone or in combination of two or more. Specific examples of the aromatic diamine having a benzoxazole structure used in the present invention include the following.

  Among these, from the viewpoint of easy synthesis, each isomer of amino (aminophenyl) benzoxazole is preferable, and 5-amino-2- (p-aminophenyl) benzoxazole is more preferable. Here, “each isomer” refers to each isomer in which two amino groups of amino (aminophenyl) benzoxazole are determined according to the coordination position (eg, “Chemical Formula 2” to “Chemical Formula 5” above). Each compound described in the above. These diamines may be used alone or in combination of two or more.

  In this invention, if it is 30 mol% or less of all the diamines, you may use together 1 type, or 2 or more types of diamines which do not have the benzoxazole structure illustrated below. 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′-diamino Diphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-dia Nodiphenyl sulfide, 3,3′-diaminodiphenyl sulfoxide, 3,4′-diaminodiphenyl sulfoxide, 4,4′-diaminodiphenyl sulfoxide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 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-dimethyl Phenyl] propane, 2,2-bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1 , 3,3,3-hexafluoropropane, 1,4-bis (3-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) Benzene, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (4-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- Methylbenzyl] 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-biphe) Xylbenzoyl) benzene, 2,6-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzonitrile and some or all of the hydrogen atoms on the aromatic ring of the aromatic diamine are halogen atoms, An alkyl group having 1 to 3 carbon atoms, an alkoxyl group, a cyano group, or a halogenated alkyl group having 1 to 3 carbon atoms or an alkoxyl group in which some or all of the hydrogen atoms of the alkyl group or alkoxyl group are substituted with halogen atoms. Examples thereof include substituted aromatic diamines.

<Aromatic tetracarboxylic acid anhydrides>
Specific examples of the aromatic tetracarboxylic acid anhydride used in the present invention 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 they are 30 mol% or less of the total tetracarboxylic dianhydrides. 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, bisic [2.2.2] Octane-2,3,5,6-tetracarboxylic dianhydride, bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride An anhydride etc. are mentioned. These tetracarboxylic dianhydrides may be used alone or in combination of two or more.

The polyimide benzoxazole film is obtained by first polymerizing (a) an aromatic diamine having a benzoxazole structure and an aromatic tetracarboxylic acid anhydride in a solvent to obtain a polyamic acid solution (hereinafter, step (a)). (B) Next, (b) the polyamic acid solution is coated on the support to provide self-supporting property, specifically, the condition that the residual solvent amount with respect to the total mass after drying is 40% by mass or less. A gel film having self-supporting property is obtained by drying (hereinafter, also referred to as step (b)), and then (c) the gel film is heat-treated under the conditions described later to cause an imidization reaction (hereinafter, step). (Also referred to as (c)).
The unstretched film refers to a film obtained without intentional stretching by mechanical external force such as tenter stretching, roll stretching, and inflation stretching. For example, when both ends of the gel film are fixed, shrinkage behavior may occur due to solvent evaporation, but in this case, since no mechanical external force is intentionally applied, it is treated as an unstretched film in the present invention.

<Process (a)>
The solvent used when polymerizing aromatic diamines having a benzoxazole ring and tetracarboxylic anhydrides to obtain polyamic acid should be one that dissolves both the raw material monomer and the resulting polyamic acid. Although not particularly limited, polar organic solvents are preferable, for example, 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. 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 8 to 30% 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 min to 80 hours. 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 8 to 30% by mass, and the viscosity of the solution is measured with a Brookfield viscometer (25 ° C.). And from the stability point of liquid feeding, Preferably it is 10-500 Pa.s, More preferably, it is 30-300 Pa.s.

  Vacuum defoaming during the polymerization reaction is effective for producing a high-quality polyamic acid organic solvent solution. 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. Furthermore, an organic or inorganic lubricant may be added during the polymerization reaction and after the polymerization reaction in order to improve handling properties such as imparting slipperiness to the film.

<Step (b)>
The support on which the polyamic acid solution is applied is only required to have smoothness and rigidity sufficient to form the polyamic acid solution into a film, and a drum or belt whose surface is made of metal, plastic, glass, porcelain, etc. An example of such a rotating body is illustrated. A polymer film having moderate rigidity and high smoothness can be preferably used as the support. Preferably, the surface of the support is a metal, and more preferably, it is stainless steel that hardly rusts and has excellent corrosion resistance. The surface of the support may be plated with metal such as Cr, Ni, or Sn. If necessary, the surface of the support can be mirror-finished or processed into a satin finish. Application of the polyamic acid solution to the support includes, but is not limited to, casting from a slit base, extrusion through an extruder, squeegee coating, reverse coating, die coating, applicator coating, wire bar coating, etc. Conventionally known solution coating means can be appropriately used.

  The amount of residual solvent when the polyamic acid film is dried to such an extent that self-supporting properties are obtained is preferably 20 to 50% by mass, more preferably 25 to 40% by mass. When the residual solvent amount is lower than 20% by mass, the imidization reaction proceeds undesirably, or the polyamic acid film itself tends to become brittle due to a decrease in molecular weight. Moreover, when it exceeds 50 mass%, self-supporting property becomes inadequate and conveyance of a film may become difficult. The polyamic acid film (gel film) obtained in the step (b) contains at least a polyamic acid having a benzoxazole structure, and a part of the polyamic acid may be imidized.

As a drying condition for obtaining the polyamic acid film as described above, a treatment at less than 150 ° C. may be mentioned. For example, the drying temperature when N, N-dimethylformamide is used as a solvent is preferably 100 to 130 ° C, more preferably 105 to 125 ° C, and still more preferably 110 to 120 ° C. When the drying temperature is higher than 130 ° C., the molecular weight is lowered, and the polyamic acid film tends to be brittle. Moreover, imidation progresses partially at the time of polyamic-acid film manufacture, and it becomes difficult to obtain a desired physical property at the time of an imidation process. On the other hand, when the temperature is lower than 90 ° C., the drying time becomes long, the molecular weight tends to decrease, and the handling property tends to be poor due to insufficient drying. The drying time is preferably 10 to 90 minutes, more preferably 15 to 80 minutes, although it depends on the drying temperature. When the drying time is longer than 90 minutes, the film tends to become brittle due to a decrease in molecular weight, and when it is lower than 10 minutes, the drying property is insufficient and the handling property tends to be poor. Further, in order to improve the drying efficiency or suppress the generation of bubbles during drying, the temperature may be raised stepwise in the range of 100 to 130 ° C. for drying.
A conventionally known drying apparatus that satisfies such conditions can be applied, and examples thereof include hot air, hot nitrogen, far infrared rays, and high frequency induction heating.

When applying the polyamic acid to the support, it is essential that the atmosphere of the application part is a dry gas of 15 to 30 ° C. with a dew point controlled to be less than 5 to 15 ° C. When the dew point is 15 ° C. or higher, the applied polyamic acid solution sucks moisture in the environment, and unevenness like craters is seen on the coated surface, which tends to increase the thickness unevenness. Although it is theoretically possible to set the dew point to 5 degrees or less, it is practically difficult to control the dew point below this as a practical problem.
Further, when the temperature is 30 ° C. or higher, the molecular weight tends to decrease. Although it is theoretically possible to control the temperature below 15 ° C., it is difficult to control below this as a practical problem.
By setting the atmospheric temperature to ± 2 ° C., a film having excellent uniform surface properties can be obtained.
Therefore, a preferable aspect is to control the atmosphere of the application part by sending air having a dew point of 5 ° C. to less than 15 ° C. to a predetermined temperature ± 2 ° C. of a temperature of 15 ° C. or more and 30 ° C. Preferably, the dew point is + 3 ° C., more preferably the dew point is 5 ° C. or more and 15 ° C. or more and less than 30 ° C. The temperature is controlled to ± 2 ° C., which is a predetermined temperature. In this method, a polyamic acid solution (polymer solution or polymer precursor solution) is cast and dried to produce a green film (polymer precursor film).
Adjustment of the dew point was carried out by passing the air conditioner set to a predetermined temperature for a sufficient period of time to obtain dew point air at the set temperature, and measuring and checking with a temperature and humidity meter.

<Step (c)>
A polyimide benzoxazole film is obtained by imidizing the polyamic acid which comprises the polyamic acid film obtained at the process (b). As a specific method thereof, a conventionally known imidation reaction can be appropriately used. For example, using a polyamic acid solution that does not contain a ring-closing catalyst or a dehydrating agent, the imidization reaction proceeds by subjecting it to a heat treatment (so-called thermal ring-closing method), or the polyamic acid solution contains a ring-closing catalyst and a dehydrating agent. In particular, a chemical ring closing method in which an imidization reaction is performed by the action of the above ring closing catalyst and a dehydrating agent can be given.
In order to control the thickness of the polyimide having a benzoxazole structure, the coating amount when the polyamic acid solution is applied to the support and the concentration of the polyamic acid solution can be appropriately adjusted.

In the case of the thermal ring closure method, the maximum temperature at which the film should be heated is preferably 250 to 550 ° C. By making it within the above range, it is possible to achieve both the sufficient progress of the ring-closing reaction and the suppression of deterioration.
Whether it is a thermal cyclization reaction or a chemical cyclization method, the polyimide benzoxazole film precursor (polyamic acid film) formed on the support may be peeled off from the support before it is completely imidized. Then, it may be peeled off after imidization.
The thickness of the film in the present invention is preferably in the range of 1 to 50 μm.

The polyimide benzoxazole film, which is a more preferred embodiment of the present invention, preferably has a range of 1 to 50 μm, more preferably the tensile modulus in the longitudinal direction and the width direction of the film is 7000 MPa or more, and the longitudinal direction of the film and The tensile elongation at break in the width direction is 20% or more, and the linear expansion coefficients in the longitudinal direction and the width direction of the film are both 10 ppm / ° C. or less.
Here, the longitudinal direction and the width direction of the film refer to the longitudinal direction and the width direction of the film having a long strip shape.
If the tensile modulus of the polyimide benzoxazole film is less than 7000 MPa, there is a problem that the rigidity is insufficient and the handling becomes difficult. The tensile elastic modulus in the longitudinal direction and the width direction of the film is preferably 7000 to 12000 MPa, more preferably 7000 to 10000 MPa. If the tensile modulus in the longitudinal direction and the width direction of the film are both within the above preferred ranges, there is an advantage that the film can be handled easily even if it is thinned.
As a means for improving the tensile elastic modulus of the polyimide benzoxazole film, it is important to apply the above film forming conditions, but it is also effective to further increase the molecular weight of the polyamic acid. The reduced viscosity of the polyamic acid is preferably 2.0 to 7.0 dl / g, particularly preferably 3.0 to 5.0 dl / g. If the reduced viscosity is too high, the viscosity of the polyamic acid solution may be too high to form a film.

If the tensile elongation at break of the polyimide benzoxazole film is less than 20%, the film tends to break at the time of film winding or processing. The tensile rupture elongation in the longitudinal direction and the width direction of the polyimide benzoxazole film is preferably 20 to 80%, more preferably 25 to 60%.
As a means for improving the tensile elongation at break of the polyimide film, it is important to apply the above film forming conditions as in the case of improving the tensile elastic modulus, but it is also effective to increase the molecular weight of the polyamic acid. The reduced viscosity of the polyamic acid is preferably 2.0 to 7.0 dl / g, particularly preferably 3.0 to 5.0 dl / g. If the reduced viscosity is too high, the viscosity of the polyamic acid solution may be too high to form a film.

When the linear expansion coefficient of the polyimide benzoxazole film exceeds 10 ppm / ° C., there is a problem that a dimensional change due to a temperature change is large and a residual stress is easily generated when used as a substrate for an electronic component, thereby causing a failure. The linear expansion coefficient in the longitudinal direction and the width direction of the film is preferably −2.0 to 10.0 ppm / ° C., more preferably 0 to 5 ppm / ° C. If the linear expansion coefficients in the longitudinal direction and the width direction of the film are both within the above preferable ranges, there is an advantage that the dimensional change is small and the reliability is improved when used as a substrate for an electronic component. As a means for reducing the linear expansion coefficient of the polyimide benzoxazole film, the above-described heat treatment may be performed during imidization.
Although it will not specifically limit if the thickness of the polyimide benzoxazole film of this invention is 50 micrometers or less, For example, when considering using it for the base substrate for printed wiring boards, it is 1-38 micrometers normally, Preferably it is 1-7 micrometers. This thickness can be easily controlled by the amount of the polyamic acid solution applied to the support and the concentration of the polyamic acid solution.
There is no particular limitation on the size of the polyimide benzoxazole film of the present invention. According to the manufacturing method using the tunnel furnace described above, for example, a long film having a width of 500 mm or more and an area of 90 m ² or more can be manufactured.

In the polyimide benzoxazole film which is a preferred embodiment of the present invention, a lubricant may be added in order to form fine protrusions on the film surface and to exhibit slipperiness. As the lubricant, known organic and inorganic fine particles can be used. The material of the organic particles and inorganic particles is not particularly limited, and a material usually used as a filler may be used. Specifically, heat-resistant resin fine particles such as benzoguanamine particles and polyimide particles, and metal oxides such as SiO ₂ , TiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , Sb ₂ O ₃ , BeO, MgO, CaO, and SrO. , Metal nitrides such as AlN, orthophosphate compounds of Group IIa alkaline earth metals (Be, Mg, Ca, Sr, Ra), carbonates of Group IIa alkaline earth metals, Al, TiV, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ta, W, Pt, Au, Pb, Bi, C, Si, etc. Metals, metalloid fine powders, alloy powders and composite powders containing the above metals, and other minerals can be used. The average particle diameter of such a lubricant is preferably in the range of 0.05 to 2.5 μm. The amount of lubricant added relative to the total mass of the film is preferably 0.003 to 2.0 mass%. The lubricant particles are preferably spherical.

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, N-dimethylacetamide so that the polymer concentration was 0.2 g / dl was measured at 30 ° C. with an Ubbelohde type viscosity tube.
2. Film thickness The film thickness was measured using a micrometer (Finereuf, Millitron (registered trademark) 1254D).
3. Tensile modulus, tensile breaking strength and tensile breaking elongation of the film The test piece was obtained by cutting the dried film into strips of length 100 mm and width 10 mm in the longitudinal direction (MD direction) and width direction (TD direction), respectively. It was. About this test piece, using a tensile tester (manufactured by Shimadzu Autograph (registered trademark) model name AG-5000A) at a tensile speed of 50 mm / min and a distance between chucks of 40 mm, the tensile elastic modulus, tensile strength, and tensile breaking elongation. I asked for a degree.

4). Film linear expansion coefficient (hereinafter also referred to as CTE)
About the film of a measuring object, the expansion-contraction rate of a longitudinal direction (MD) and the width direction (TD) is measured on condition of the following, and 30 degreeC-45 degreeC, 45 degreeC-60 degreeC, ..., ..., and 15 degreeC. The stretch rate / temperature at intervals was measured, this measurement was performed up to 300 ° C., and the average value of all measured values in each direction was calculated as CTE.
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

5. A polyimide having a density benzoxazole structure of the film was cut into a size of 5 mm × 5 mm and subjected to density measurement. This cut sample was put into a density gradient tube prepared with an aqueous calcium nitrate solution, and the density was measured from the standard float position and density calibration curve with a known density and the sample position after 5 hours. The liquid temperature of the density gradient tube is 30 ° C.

6). Atmospheric temperature and humidity of application area (dew point)
The temperature and dew point were measured with a thermohygrometer at the application part where the polyamic acid solution was applied to the support.

7). Film Flatness Regarding the film flatness, both the polyamic acid film and the polyimide benzoxazole film were visually confirmed.

[Example 1]
(Preparation of polyamic acid solution)
After the inside of a reaction vessel equipped with a nitrogen introduction tube, a thermometer, and a stirring rod was purged with nitrogen, 500 parts by mass of 5-amino-2- (p-aminophenyl) benzoxazole was added. Next, 8000 parts by mass of N, N-dimethylacetamide was added and completely dissolved, 480 parts by mass of pyromellitic dianhydride was added, and then Snowtex DMAC- in which colloidal silica was dispersed in dimethylacetamide. When ST30 (manufactured by Nissan Chemical Industries, Ltd.) 15 parts by mass (including 3 parts by mass of silica) was added and stirred at 25 ° C. for 40 hours, a brown viscous polyamic acid solution (PAA1) was obtained. The reduced viscosity (ηsp / C) was 4.0 dl / g.

(Manufacture of polyamic acid film)
The polyamic acid solution was coated on a stainless steel belt as a support while controlling the temperature and humidity of the coating part atmosphere as shown in Table 1. In the coating, a comma coater was used, and the gap between the comma coater and the belt was adjusted to 20 to 1000 μm. Thereafter, the coated material was conveyed in a hot air dryer having four compartments. All four zones were set to 110 ° C. and transported at such a speed as to exist in each zone for about 4 minutes. That is, drying at 110 ° C. for about 4 minutes was performed four times in succession. In other words, it is equivalent to drying at 110 ° C. for about 16 minutes. Polyamic acid film (also indicated as GF) by the above method
Got.

(Production of polyimide benzoxazole film)
The polyamic acid film was peeled from the stainless steel belt and wound on a cigarette. The obtained polyamic acid film had a width of 700 mm, a length of 360 m, and a thickness of 4.5 μm. The obtained polyamic acid film 1 was passed through a continuous heat treatment furnace having four zones. The first zone was set to 200 ° C, the second zone was set to 225 ° C, and the third and fourth zones were set to 500 ° C. The film was conveyed so as to pass through each zone for 3 minutes. After leaving the fourth zone, it was naturally cooled to room temperature and wound up with a winder to obtain a brown polyimide benzoxazole film having a thickness of 3 μm. The results of measurement and evaluation of the obtained polyimide benzoxazole film are shown in Table 1.

[Examples 2 and 3]
A polyimide benzoxazole film was obtained in the same manner as in Example 1 except that the thickness was changed as shown in Table 1. The results of measurement and evaluation of the obtained polyimide benzoxazole film are shown in Table 1.

Example 4
A polyimide film was prepared in the same manner as in Example 1 except that the polyamic acid prepared below and PAA2 were used and the conditions described in Table 1 were used. Table 1 shows the results of measurement and evaluation of the obtained polyimide film.

[Comparative Examples 1, 2, 3, 4]
Using the polyamic acid PAA1 produced in Example 1 and the polyamic acid PAA2 produced below, a polyimide film was produced in the same manner as in Example 1 except for the conditions described in Table 1. Table 1 shows the results of measurement and evaluation of the obtained polyimide benzoxazole film and polyimide film. The film obtained compared with the Example was inferior in thickness spots and flatness.

(Preparation of polyamic acid solution (PAA2))
545 parts by weight of pyromellitic anhydride and 500 parts by weight of 4,4′diaminodiphenyl ether were dissolved in 5000 parts by weight of N, N-dimethylacetamide and reacted in the same manner while maintaining the temperature at 20 ° C. or lower to obtain a polyamic acid solution ( PAA2) was obtained. The solution obtained had a ηsp / C of 2.2 dl / g.

表中、ＣＴＥは線膨張係数を示す。

In the table, CTE represents a linear expansion coefficient.

  The polymer film produced by the production method of the present invention, particularly the polyimide film having a benzoxazole structure among the polyimide films, is suitable for a substrate film of electronic parts, that is, has no coating streaks and crater-like surface defects. Such as copper-clad substrates for flexible printed wiring (FPC) and tape automated bonding (TAB) carrier tapes, etc. It is suitably used as a substrate film used for production.

Claims (5)

  In the casting film-forming polymer film manufacturing method including a step of applying a polymer solution or a polymer precursor solution onto a support and drying to obtain a film, the polymer solution or polymer precursor A method for producing a polymer film, wherein the atmosphere of an application part for applying a solution on a support is a dry gas atmosphere of 15 to 30 ° C controlled to a dew point of 5 ° C or higher and lower than 15 ° C.   2. The polymer precursor solution is a polyamic acid solution obtained from a diamine containing an aromatic diamine having a benzoxazole structure and a tetracarboxylic acid anhydride containing an aromatic tetracarboxylic acid anhydride. The manufacturing method of the polymer film of description.   The method for producing a polymer film according to claim 1 or 2, wherein the temperature of the atmosphere of the coating part is controlled to ± 2 ° C.   A method for producing a polymer film, comprising subjecting the polymer precursor film obtained by the production method according to claim 1 to a high-temperature heat treatment reaction without stretching.   The manufacturing method of the polymer film whose polymer film obtained by the manufacturing method in any one of Claims 1-4 is a polyimide benzoxazole film, and the thickness of this film is the range of 1-50 micrometers.