JP3486654B2 - Method for producing aromatic polyamide film - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a lens protective film,
The present invention relates to a method for producing an aromatic polyamide film having excellent tensile strength, tensile modulus, and transparency used for recording magnetic tape and the like.

[0002]

2. Description of the Related Art Aromatic polyamides, especially all-para-substituted aromatic polyamides, are among the polymers known to date having the highest tensile modulus. The film obtained from the aromatic polyamide can be thinned to a thickness of several μm due to its very high tensile modulus, and also has excellent heat resistance due to its very high melting point or decomposition temperature. Have.

However, the aromatic polyamide is difficult to handle because it dissolves only in a highly polar special solvent such as concentrated sulfuric acid, and since it has a lyotropic liquid crystallinity, a large number of fine crystals are produced by the usual solution casting method. Only the devitrified, low-strength film contained was obtained.

As a method for producing a transparent aromatic polyamide film, JP-A-62-246719 discloses N-
An aromatic polyamide obtained by polymerizing in a solvent such as methylpyrrolidone is once separated as a polymer, and then the polymer is dissolved in concentrated sulfuric acid to obtain an optically anisotropic concentrated sulfuric acid solution, which is humidified at high temperature. It is described that the film obtained by optically isotropy, coagulation and washing is heat treated under tension at 300 to 500 ° C. However, this method has a problem in that the number of steps is large and complicated operations are required, and the facility to be used must have sulfuric acid resistance specifications, resulting in a very high cost.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a transparent, transparent, aromatic polyamide dope having high strength and high heat resistance without the step of dissolving the aromatic polyamide in concentrated sulfuric acid. An object of the present invention is to provide an inexpensive method for producing an aromatic polyamide film, which is capable of producing an aromatic polyamide film, has excellent productivity, and does not require facilities for acid resistance specifications.

[0006]

The inventors of the present invention have conducted extensive studies to solve this problem, and as a result, have found that an optically isotropic solution (hereinafter referred to as a dope) in which an aromatic polyamide is dissolved in a polar polyamide is used. A) is prepared, the dope is formed into a film, the obtained film-like dope is immersed in a low temperature polar solvent to form a film, and then the film is dried. In each step of
It was found that an aromatic polyamide film having excellent mechanical strength such as tensile strength and tensile modulus and transparency can be obtained by treating the film-like material with an isocyanate compound, and the present invention has been completed.

That is, the present invention is as described below. [1] A step of preparing an optically isotropic dope in which an aromatic polyamide is dissolved in a polar amide. [2] A step of forming the dope into a film. [3] A step of immersing a membranous dope in a polar solvent to coagulate it to form a film. [4] A step of drying the film material. The method for producing an aromatic polyamide film having excellent transparency, which comprises the step of: and treating the film-like dope or the film-like material with an isocyanate compound before the step [4].

The present invention will be described in detail below. In the present invention, examples of the aromatic polyamide include all-para-substituted aromatic polyamide. The all-para-substituted aromatic polyamide is obtained by polycondensation of a para-oriented aromatic diamine and a para-oriented aromatic dicarboxylic acid halide, and is composed of repeating units in which an amide bond is bonded at the para position of an aromatic ring. Specific examples thereof include poly (paraphenylene terephthalamide) obtained by polycondensation of paraphenylenediamine and terephthalic acid dichloride.

Specific examples include those comprising the following repeating structural units (A) and (B).

[Chemical 3]

[0010]

[Chemical 4]

In addition to the repeating structural units (A) and (B), those containing a small number of the following repeating structural units (Q) and those consisting of repeating structural units (Q) are also included.

[Chemical 5]

In the aromatic polyamide, units other than the above, such as ortho-oriented aromatic and meta-oriented aromatic,
A amide bond, an ether bond, an ester bond, a urethane bond, a urea bond or an imide bond, which has a skeleton such as a nuclear-substituted aromatic, diphenyl, diphenyl ether, diphenyl sulfone or aliphatic, etc. within a range that does not impair the effects of the present invention. May be included.

The aromatic polyamide used in the present invention preferably has an inherent viscosity of 1.0 to 2.5 dl / g. When the logarithmic viscosity number is less than 1.0 dl / g, the strength of the obtained film becomes weak, which is not preferable. On the other hand, when it exceeds 2.5 dl / g, the viscosity of the aromatic polyamide is remarkably increased or the precipitation of the aromatic polyamide is observed, which makes the dope state unstable, which is not preferable.

Here, the logarithmic viscosity number (η) is 0.5 g /
The flowing time at 30 ° C. was measured with an Ubbelohde viscometer for the concentrated sulfuric acid solution of aromatic polyamide adjusted to dl and the same concentrated sulfuric acid used for the aromatic polyamide solution, and calculated from the ratio of the calculated flowing times according to the following formula. To be done. η = [ln (T / To)] / C (unit: dl /
g) T: Flow time of a concentrated sulfuric acid solution of aromatic polyamide. To: Flow time of concentrated sulfuric acid. C: Concentration of aromatic polyamide in concentrated sulfuric acid solution (g / d
l). The concentrated sulfuric acid used here is 97% or more.

As a method for obtaining an optically isotropic aromatic polyamide dope, an aromatic diamine and an aromatic dicarboxylic acid halide are polymerized in a polar amide solution in which a chloride of an alkali metal or an alkaline earth metal is dissolved. And a method of diluting the polymerization solution.

Examples of the polar amide include N-methylpyrrolidone (hereinafter sometimes referred to as NMP), N,
Examples include N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea and the like.

The aromatic polyamide concentration in the aromatic polyamide dope is preferably 1.0 wt% or more and 4.5 wt% or less. If the concentration of the aromatic polyamide in the aromatic polyamide dope is less than 1.0 wt%, the film strength before drying is weak, which is not preferable. If the aromatic polyamide concentration exceeds 4.5 wt%,
The dope becomes a liquid crystal phase, and the film-like material after solidification becomes opaque, which is not preferable.

Examples of the isocyanate compound in the present invention include aromatic or aliphatic polyisocyanates containing two or more isocyanate groups, or adducts thereof, allophanate modified products, burette modified products or isocyanurate modified products thereof.

Further, as the isocyanate compound in the present invention, an aromatic or aliphatic polyisocyanate containing two or more isocyanate groups, or an adduct thereof, an allophanate modified product, a buret modified product or an isocyanurate modified product thereof is a phenol compound. Class, β
Mention may be made of blocked isocyanates blocked with ketones, malonic esters or lactams. Examples of phenols include phenol and m
-Cresol, p-cresol and the like. β-
Examples of the ketones include 3,5-octadione. Examples of malonates include diethyl malonate and the like. As lactams,
For example, ε-caprolactam and the like can be mentioned.

Specific examples of the polyisocyanate include tolylene diisocyanate (TDI), methylenedi (p-phenylene) diisocyanate (MDI),
Crude MDI (Polymeric MDI), Xylylene Diisocyanate (XDI),

Dianisidine diisocyanate (DAD
I), diphenyl ether diisocyanate (PED
I), o-tolidine diisocyanate (TODI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI),

2,2,4 (or 2,4,4) -trimethylhexamethylene diisocyanate (TMDI), dicyclohexylmethane diisocyanate (hydrogenated MDI)
Diisocyanates, such as

Triphenylmethane triisocyanate,
Triisocyanate Phenyltriisocyanate, 1,
Triisocyanates such as 6,11-undecatriisocyanate may be mentioned.

Further, an adduct, an allophanate modified product, a burette modified product or an isocyanurate modified product of these polyisocyanates can be mentioned.

Examples of the blocked isocyanates include the polyisocyanates specifically exemplified above, which are blocked with the above-mentioned phenols, β-ketones, malonic acid esters or lactams.

Specifically, for example, the following structure (C),
(D), (E), (F), (G), (H) or (I)
The blocked isocyanate represented by

[0027]

[Chemical 6]

[0028]

[Chemical 7]

[0029]

[Chemical 8]

[0030]

[Chemical 9]

[0031]

[Chemical 10]

[0032]

[Chemical 11]

[0033]

[Chemical 12] [However, R ₁ is selected from an alkylene group having 1 to 13 carbon atoms, or the following structures (J), (K), (L), (M) or (R).

[0034]

[Chemical 13]

[0035]

[Chemical 14]

[0036]

[Chemical 15]

[0037]

[Chemical 16]

[0038]

[Chemical 17]

Here, R ₂ , R ₃ , R ₄ , R ₅ , R ₆ ,
R ₇ , R ₈ and R ₉ represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group or a halogen atom, and Y
Represents a sulfur atom, an oxygen atom or SO ₂ . X represents the following structure (N), (O) or (P).

[0040]

[Chemical 18]

[0041]

[Chemical 19]

[0042]

[Chemical 20]

Here, n represents an integer of 2 to 11,
R ₁₀ , R ₁₁ and R ₁₂ represent an alkyl group having 1 to 11 carbon atoms, an alkoxy group, a phenyl group or a phenoxy group. ]

Specific examples of R ₁ include the following groups.

[Chemical 21]

[0045]

[Chemical formula 22]

[0046]

[Chemical formula 23]

[0047]

[Chemical formula 24]

[0048]

[Chemical 25]

[0049]

[Chemical formula 26] Examples of X include the groups shown below.

[0050]

[Chemical 27]

In the method of the present invention, the method for forming a film of an optically isotropic dope in which an aromatic polyamide is dissolved in a polar amide is not particularly limited, and examples thereof include bar coaters and
Examples include a method of casting on a support having a smooth surface using a roll coater or a coater such as a doctor blade, or a method of extruding the dope through a slit.

As the support, a band, a film or a drum having at least its surface formed of metal such as steel or stainless steel, polyester, plastic such as fluororesin or engineering plastic, or release paper can be used.

When the support side is fixed and the coater side is moved to cast the dope, a glass plate can be used in addition to the metal plate and the resin plate.

Then, the obtained film-shaped dope of aromatic polyamide is immersed in a polar solvent kept at -20 ° C or lower. The film-like dope is coagulated in the polar solvent without losing optical isotropy to form a film-like material.

The temperature maintained by the polar solvent is -20 ° C or lower, preferably -30 ° C or lower, and more preferably -40.
It is below ℃. If the temperature exceeds -20 ° C, the aromatic polyamide loses its optical isotropy during immersion in the polar solvent and only a devitrified film is obtained, which is not preferable. Further, a temperature of -100 ° C or higher is preferable because it is easier to set and industrially advantageous.

The polar solvent in the present invention is for solidifying the dope, and the freezing point of the polar solvent is preferably −25 ° C. or lower, more preferably −35 ° C. or lower, still more preferably −45 ° C. The temperature is particularly preferably below -100 ° C.

The dielectric constant of the polar solvent at 25 ° C. is preferably 10 or more, more preferably 20 or more,
Particularly preferably, it is 30 or more.

Examples of the polar solvent include alcohols such as methanol, ethanol, 1-propanol or 1,3-propanediol, or the alcohols containing the alcohols as a main component and N-methylpyrrolidone and / or Examples thereof include a mixture with water.

Cleaning may be performed subsequent to the coagulation step. The washing step is performed by treating the coagulated aromatic polyamide film with at least one washing solvent selected from methanol, acetone or water. Since the removal of the polar amide solvent and salts from the aromatic polyamide can be achieved to some extent in the coagulation step, the washing step can be substituted by the coagulation step.

Examples of the method of treating the film-like dope with the isocyanate compound include a method of spraying the film-like dope with the isocyanate compound.

As a method of spraying the isocyanate compound on the film-like dope, the isocyanate compound may be directly sprayed on the film-like dope, or a solution in which the isocyanate compound is dissolved may be sprayed. In the case of spraying a solution in which an isocyanate compound is dissolved, it is preferable to use the polar amide used for the preparation of the dope as a solvent in order to prevent the polymer from precipitating from the film-like dope.

As a method for treating a film-like material obtained by solidifying a film-like dope with an isocyanate compound, a method of spraying an isocyanate compound on the film-like material or a method of immersing the film-like material in an isocyanate compound is used. Can be mentioned.

As a method of spraying the isocyanate compound on the film material, the isocyanate compound may be directly sprayed on the film material, or a solution in which the isocyanate compound is dissolved may be sprayed. This spraying step is preferably performed after the washing step.

Examples of the method of immersing the film-like material in the isocyanate compound include a method of immersing the film-like material in a solution in which the isocyanate compound is dissolved.

When immersed in a solution in which an isocyanate compound is dissolved, the solution in which the isocyanate compound is dissolved can be replaced with a coagulating solvent or a washing solvent. That is, instead of the polar solvent, a solution prepared by dissolving the isocyanate compound in the polar solvent may be used.

The solvent of the solution in which the isocyanate compound is dissolved is not particularly limited as long as it is a solvent in which the isocyanate compound is well dissolved, but from the viewpoint of stability with respect to the isocyanate compound and ease of removal of the solvent after the isocyanate compound treatment. , Acetone, methylene chloride and the like.

The amount of the isocyanate compound added to the solution in which the isocyanate compound is dissolved is 0.1 part by weight or more and 10 parts by weight or less, preferably 0.5 part by weight or more and 5 parts by weight or less, more preferably 100 parts by weight of the solvent. Is 1.0 part by weight or more and 3.0 parts by weight or less. The amount of the isocyanate compound added is 0.1 with respect to 100 parts by weight of the solvent.
If it is less than 10 parts by weight, the mechanical strength of the obtained aromatic polyamide film is insufficient, and if it exceeds 10 parts by weight, the mechanical strength of the aromatic polyamide film is saturated, which is not preferable.

Then, the aromatic polyamide film-like product obtained by sufficiently coagulating and washing was stainless steel,
It is fixed with a frame made of a sturdy material that is not attacked by solvent such as wood or resin, or with a grip, and dried while preventing shrinkage.

The drying may be carried out by air drying or hot air circulation drying, but in order to make the isocyanate compound react more effectively, it is preferable to carry out heat drying at a temperature of 100 ° C. or higher.

[0070]

EXAMPLES The present invention will now be specifically described with reference to examples, but these do not limit the present invention.

The methods for measuring various physical properties in the examples are shown below. (1) Logarithmic Viscosity Number The logarithmic viscosity number in the present invention was adjusted to 0.50 g / dl with concentrated sulfuric acid solution of aromatic polyamide and the same concentrated sulfuric acid as used in the aromatic polyamide solution at 30 ° C. by an Ubbelohde viscometer. The flow-down time is measured and calculated from the ratio of the calculated flow-down times according to the following formula. η = [ln (T / To)] / C (unit: dl /
g) T: Flow time of a concentrated sulfuric acid solution of aromatic polyamide. To: Flow time of concentrated sulfuric acid. C: Concentration of aromatic polyamide in concentrated sulfuric acid solution (g / d
l). The concentrated sulfuric acid used here was 97% or more.

(2) Tensile test From the obtained film, dumbbell cutter S manufactured by Dumbbell Co., Ltd.
A test piece was punched out with DMK-1223, and an Instron universal tensile tester model manufactured by Instron Japan Co., Ltd.
Using 4301, the tensile strength and the tensile elastic modulus were determined according to JIS K-7127.

The isocyanate compounds BI-5 to BI-7 used in this example were prepared as follows. BI-5: 300 ml three-necked flask equipped with a mechanical stirrer, dropping funnel, jim funnel and three-way cock, Sumidu manufactured by Sumitomo Bayer Urethane Co., Ltd.
r N3500 (HDT-derived isocyanurate) 1
04 g (0.206 mol), CLM 70 g (0.6
2 mol) was added, and the mixture was heated with stirring at 150 ° C. for 5 hours. The reaction product thus obtained was poured into a large amount of methanol to recover the blocked isocyanate BI-5.

BI-6: A 300 ml three-necked flask was equipped with a mechanical stirrer, a dropping funnel, a Dimroth and a three-way cock, and 3,5-octadione 10
g (0.070 mol), sodium 1.61 g
(0.070 mol) and 100 ml of THF were charged, and the reaction was stirred for 4 hours until sodium disappeared. Into the reaction solution thus obtained, 11.78 g (0.70 g) of Sumidur N3500 manufactured by Sumitomo Bayer Urethane Co., Ltd.
(023 mol) was added in 3 portions, and the mixture was reacted at room temperature for 2 hours. From this reaction solution, THF was distilled off under reduced pressure, acetic acid was added until it became weakly acidic, and the separated oil layer was allowed to flow down in a large amount of methanol to recover blocked isocyanate BI-6. The reagents used for the preparation of BI-5 and BI-6 were purified by a conventional method, weighed in a dry box, and charged and reacted under a stream of dry nitrogen.

BI-7: Desmodur CT staple, which is a blocked isocyanate derived from tolylene diisocyanate (hereinafter sometimes abbreviated as TDI) manufactured by Sumitomo Bayer Urethane Co., Ltd., was used as it was.

The aromatic polyamide dope used in this example and the comparative example was prepared as follows. Fifty
A 0 ml separable flask was equipped with an icari type stirring blade, a Dimroth condenser, and a three-way cock, and the atmosphere was sufficiently replaced with nitrogen. Into this, 31.90 g of CaCl ₂ previously vacuum-dried at 200 ° C. for 2 hours or more and 463.5 g of N-methyl-2-pyrrolidone (NMP) with sufficient water removed were charged.
The mixture was heated and stirred in an oil bath at 100 ° C for 1 hour.

After confirming that CaCl ₂ was sufficiently dissolved in NMP, it was allowed to cool to room temperature. 14.62 g (0.1% of PPD) of this NMP solution weighed in a dry box (hereinafter sometimes abbreviated as PPD).
35 mol) was added and dissolved by stirring. PPD is enough N
After confirming that it was dissolved in MP, it was cooled with ice water.

Next, 26.53 g (0.131 mol) of terephthalic acid dichloride (hereinafter sometimes abbreviated as TPC) weighed in a dry box was added to this NMP.
Added to the solution. The addition of TPC was divided into several times under a nitrogen stream, and was carried out for 20 minutes while maintaining the internal temperature at 0 to 10 ° C.

After the addition of the TPC NMP solution was completed, the internal temperature was set to 0.
Stirring was continued for 2 hours while maintaining ~ 5 ° C. After that, the pressure in the system was further reduced by a vacuum pump for 30 minutes to remove low boiling point compounds, and then nitrogen was flowed to return the system to normal pressure to complete the polymerization. All of the above-mentioned aromatic polyamide synthesis was carried out under a dry nitrogen atmosphere to prevent the entry of outside air, especially water, into the system as much as possible. Thus, an optically anisotropic aromatic polyamide dope was obtained. The aromatic polyamide concentration in this dope was 6 wt%, and the logarithmic viscosity number of this aromatic polyamide was 1.72 dl / g.

Examples 1 to 6 First, the optically isotropic aromatic polyamide dope obtained above was diluted 2-fold with NMP to prepare an optically isotropic aromatic polyamide dope. The aromatic polyamide concentration in this dope was 3 wt%. The optically isotropic aromatic polyamide dope thus prepared was flown down onto a well-polished glass plate, and an automatic coating device P manufactured by Tester Sangyo Co., Ltd.
I-1210 and a wedge bar manufactured by Matsuo Sangyo Co., Ltd. were used to form a film having a thickness of 0.6 mm.

Next, the film-shaped aromatic polyamide dope was immersed in methanol kept at -70 ° C or lower for 30 minutes using dry ice, and cooled and coagulated to obtain a film-shaped product. Then, this aromatic polyamide film-like material was immersed in an acetone solution of an isocyanate compound shown in Table 1 for 30 minutes at room temperature to carry out washing and isocyanate treatment.

Then, the aromatic polyamide solidified into a film was made of Teflon, having an inner diameter of 10 cm, an outer diameter of 15 cm, and a thickness of 5 mm.
It was sandwiched between two annular frames and fixed with clips. In addition,
A filter paper was inserted between the Teflon frame and the aromatic polyamide coagulation film to accelerate the drying of the part sandwiched by the frame.

The aromatic polyamide coagulated film fixed to this frame was air-dried at room temperature and then dried at 100 ° C. for 2 hours and 200 ° C. for 1 hour to obtain a transparent aromatic polyamide film. Table 1 shows the results of a tensile test performed on the transparent aromatic polyamide film thus obtained.

Example 7 After cooling and coagulation, the film-like substance of the aromatic polyamide coagulated into a film was washed with methanol at room temperature and sprayed with a 1.0 wt% acetone solution of the isocyanate compound shown in Table 1. A transparent aromatic polyamide film was obtained in the same manner as in Example 1 except that the transparent aromatic polyamide film was sprayed. Table 1 shows the results of a tensile test performed on the transparent aromatic polyamide film thus obtained.

Comparative Example 1 A transparent aromatic polyamide film was obtained in the same manner as in Example 1, except that methanol at room temperature was used in the washing step and no isocyanate treatment was performed. Table 1 shows the results of a tensile test performed on the transparent aromatic polyamide film thus obtained.

[0086]

[Table 1] ─────────────────────────────────── Isocyanate compound Tensile test Type Tensile strength to acetone Tensile strength Elastic modulus Additive amount (phr) (kgf / mm ² ) (kgf / mm ² ) ──────────────────────────────── Example 1 BI-5 1.0 26.4 1320 Example 2 BI-5 3.0 28.8 1310 Example 3 BI-5 6.0 23.6 1130 Example 4 BI-6 3 0 25.5 1410 Example 5 BI-7 1.0 23.9 1260 Example 6 N3500 3.0 23.0 1090 Example 7 BI-5 1.0 25.4 1340 Comparative Example 1 (Methanol wash only ) 18.4 970 ─────────────────────────────────── N3500: S midur N3500

The aromatic polyamide film having excellent transparency obtained by the method of the present invention takes advantage of its excellent heat resistance, chemical resistance, abrasion resistance and electric insulation, and is used as a protective film for lenses, automobiles, trains, It can be used for windshield protective coatings for aircraft, boiler peep window protective coatings, electric wires, optical fiber coating tapes, flexible printed circuit boards, and magnetic recording tapes.

[0088]

According to the method for producing an aromatic polyamide film of the present invention, the tensile strength can be directly obtained from the polymerization solution (dope) of the aromatic polyamide without the step of dissolving the aromatic polyamide in concentrated sulfuric acid. It is possible to produce a transparent aromatic polyamide film having excellent mechanical strength such as and tensile modulus and high heat resistance. The production method of the present invention has a small number of steps, is excellent in productivity, and does not require equipment with acid resistance specifications, and is industrially very advantageous.

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-913 (JP, A) JP-A-62-172037 (JP, A) JP-B-43-8618 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) C08J 5/00-5/24 C08J 7/00-7/02 C08J 7/12-7/18 B29C 71/00-71/04 C08G 69/00-69 / 50 C08L 1/00-101/14

Claims (9)

(57) [Claims] 1. A step of preparing an optically isotropic dope in which [1] an aromatic polyamide is dissolved in a polar amide. [2] A step of forming the dope into a film. [3] A step of immersing a membranous dope in a polar solvent to coagulate it to form a film. [4] A step of drying the film material. The method for producing an aromatic polyamide film having excellent transparency, which comprises the step of: and treating the film-like dope or the film-like material with an isocyanate compound before the step [4]. 2. The method for producing an aromatic polyamide film according to claim 1, wherein the aromatic polyamide comprises the following repeating structural units (A) and (B). [Chemical 1] [Chemical 2] 3. A solution obtained by polymerizing an aromatic diamine and an aromatic dicarboxylic acid halide in a polar amide solution in which a chloride of an alkali metal or an alkaline earth metal is dissolved, or a diluted solution thereof. The method for producing an aromatic polyamide film according to claim 1. 4. As the polar solvent, at least one alcohol selected from the group consisting of methanol, ethanol, 1-propanol and 1,3-propanediol, which is kept at -20 ° C. or lower, or contains the alcohol as a main component. The method for producing an aromatic polyamide film according to claim 1, wherein a polar solvent selected from a mixture of the alcohol and N-methylpyrrolidone and / or water is used. 5. The method for producing an aromatic polyamide film according to claim 1, wherein the film-like material is washed with at least one washing solvent selected from methanol, acetone or water and then dried by heating. 6. The production of an aromatic polyamide film according to claim 1, wherein the isocyanate compound is an aromatic or aliphatic polyisocyanate, or an adduct thereof, an allophanate modified product, a buret modified product or an isocyanurate modified product thereof. Method. 7. The isocyanate compound is an aromatic or aliphatic polyisocyanate, or an adduct thereof, an allophanate modified product, a buret modified product or an isocyanurate modified product thereof is phenols, β-ketones, malonic acid esters. The method for producing an aromatic polyamide film according to claim 1, which is a blocked isocyanate blocked with a lactam. 8. The method for producing an aromatic polyamide film according to claim 1, wherein the film-like dope is treated with the isocyanate compound. 9. The method for producing an aromatic polyamide film according to claim 1, wherein the film-like material is treated with the isocyanate compound.