JP2001347563A - Manufacturing method for aromatic polyamide film, and aromatic polyamide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretching method for an aromatic polyamide film which enables execution of stretch of a large scaling factor and has high productivity and which enables reduction of neckdown even in the stretch of a large scaling factor and attainment of the film of a high quality level with high productivity. SOLUTION: On the occasion when a polymeric sheet of an aromatic polyamide containing a solvent is stretched longitudinally to manufacture the aromatic polyamide film, the width of the polymeric sheet is made 50 cm or more and the polymeric sheet in stretching is heated to 70-250 deg.C, while a section of the stretch is made 3-200 cm and a speed of the stretch is made 50-3,000 %/sec.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyamide film having high productivity and process stability, capable of suppressing neck-down even during high-magnification stretching, and capable of obtaining a high-quality film. And a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, aromatic polyamide films have been widely used as industrial materials. In particular, due to advances in digital recording technology and the development of external memory in computers, the demand for thinner magnetic tapes and higher density recording has increased, and aromatics having excellent heat resistance, mechanical properties, and thermal stability have been developed. Polyamide films have been increasingly used as base films for magnetic tapes.
For example, in recent years, aromatic polyamide films have been rapidly developed as one of high-performance magnetic materials, particularly for digital data storage, and higher productivity and mechanical properties have been demanded with the increase in the amount of aromatic polyamide films. ing.

[0003] Aromatic polyamide is generally formed into a film by a solution casting method because its melting point is higher than its decomposition point. Specifically, a polymer solution discharged from a die onto a support such as a belt or a drum is processed by a casting machine or the like to make it into a semi-solid state, and then the solvent is extracted in a liquid tank or dried and heat-treated in an oven. Done. During this time, the film is stretched in the vertical and horizontal directions to obtain a film having a high Young's modulus in the length and width directions.

[0004] This stretching step is important for producing an aromatic polyamide film having higher productivity and mechanical properties. In particular, in the solution casting method, the size of the support on which the polymer solution is cast is limited, and a certain time is required for drying or extracting the solvent, and the casting speed is also limited. Stretching at a high magnification in the stretching step is considered to be one of the most effective means for increasing productivity. However, aromatic polyamides, especially para-based aromatic polyamides, have been considered to be difficult to achieve high stretching because of their rigidity and poor stretchability.

When the film is stretched in the longitudinal direction, the width of the film decreases in accordance with the Poisson's ratio (hereinafter, this phenomenon is referred to as neck-down). In particular, as the stretching ratio increases, the neck down increases. If the neck-down is large, not only the productivity is lowered, but also the flatness and physical properties in the width direction of the film are significantly deteriorated, and thickness unevenness occurs.

In Japanese Patent Application Laid-Open No. 62-62424, the tensile Young's modulus in the width direction is 700 kg / mm ² or more, and the tensile Young's modulus in the length direction is 1.
A three or more times magnetic recording medium is described. Further, Japanese Patent Application Laid-Open No. 62-70022 discloses that the sum of the tensile modulus in the longitudinal direction and the tensile modulus in the transverse direction is 350 in the stretched film state.
An aromatic polymer film of 0 to 11,000 kg / mm ² is described.

[0007]

However, Japanese Patent Application Laid-Open No. 62-62424 only vaguely describes that an aromatic polyamide film is cast on a mirror-polished Hastelloy belt and stretched. Nothing is disclosed about the stretching method and conditions, it is difficult to produce with high productivity (higher film forming speed and stretching sustainability), and the quality of the base film, especially in the longitudinal direction There was a problem of uneven thickness.

Japanese Patent Application Laid-Open No. 62-70022 discloses that the sum of the tensile elastic modulus in the longitudinal direction and the tensile modulus in the transverse direction of a film obtained by stretching is 3,500. １11000 kg / mm ² , and in this case, it is described that multi-stage stretching is performed at 300 ° C. to 600 ° C., but the method and conditions for longitudinal stretching are not particularly described.

Furthermore, Japanese Patent Application Laid-Open No. H11-48334 describes a method for longitudinally stretching an aromatic polyamide film, but the stretching ratio is at most 1.6 times, and it can be said that productivity is still high. Absent.

According to the present invention, in the production of an aromatic polyamide film, high stretching can be performed and productivity is high, neck down can be suppressed even at high magnification stretching, and a high quality film can be produced with high productivity. An object of the present invention is to provide a method for stretching the obtained aromatic polyamide film.

[0011]

An object of the present invention is to provide a polymer sheet made of an aromatic polyamide containing a solvent, wherein the width of the polymer sheet is 50 cm or more when the polymer sheet is stretched in the longitudinal direction. To 70-250 ° C.,
The stretching section is 3 to 200 cm, and the stretching speed is 50
This is achieved by a method for producing an aromatic polyamide film, which is characterized in that it is set to 3000% / sec.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The aromatic polyamide used in the present invention has a repeating unit represented by the following formula (1) and / or formula (2).

Equation (1):

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Equation (2):

[0015]

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Here, the groups Ar ₁ , Ar ₂ and Ar ₃ include, for example,

[0017]

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And the group of X and Y is -O-,-
CH ₂ —, —CO—, —CO ₂ —, —S—, —SO ₂ —,
—C (CH ₃ ) ₂ — and the like.

Further, some of the hydrogen atoms on these aromatic rings may be substituted with halogen groups (particularly chlorine) such as fluorine, bromine and chlorine;
Those substituted with substituents such as nitro groups, alkyl groups (especially methyl groups) such as methyl, ethyl and propyl, and alkoxy groups such as methoxy, ethoxy and propoxy, have dimensions due to changes in humidity in order to reduce the moisture absorption. This is preferable because the change is small. Further, hydrogen in the amide bond constituting the polymer may be substituted by another substituent. In the aromatic polyamide used in the present invention, those in which the above-mentioned aromatic ring has para-orientation are 80% of the total aromatic ring.
%, More preferably 90% or more. The term "para-orientation" as used herein refers to a state in which the divalent bonds constituting the main chain on the aromatic nucleus are coaxial or parallel to each other. If the para-orientation is less than 80%, the rigidity and heat resistance of the film may be insufficient. Further, it is preferable that the aromatic polyamide contains the repeating unit represented by the formula (3) in an amount of 60 mol% or more, since the stretchability and the physical properties of the film are particularly excellent.

Equation (3):

Embedded image

The aromatic polyamide used in the present invention is
When obtained from an aromatic diacid chloride and an aromatic diamine, it is synthesized by solution polymerization in an aprotic organic polar solvent such as N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide and the like.

At this time, in order to suppress the formation of low molecular weight substances, it is necessary to avoid mixing of water and other substances that would hinder the reaction, and it is preferable to use efficient stirring means. Further, calcium chloride, magnesium chloride, lithium chloride, lithium bromide, lithium nitrate, or the like may be added as a dissolution aid.

When an aromatic diacid chloride and an aromatic diamine are used as monomers, hydrogen chloride is by-produced. When neutralizing this, cations of the Group I or Group II of the periodic table and hydroxide ions are used. And inorganic neutralizers represented by salts of anions such as carbonic acid ions, and organic neutralizers such as ethylene oxide, propylene oxide, ammonia, triethylamine, triethanolamine and diethanolamine. For the purpose of improving the humidity characteristics of the base film, benzoyl chloride, phthalic anhydride, acetic chloride, aniline, etc. are added to the polymerized system to form a polymer.
May be blocked.

In order to obtain the film of the present invention, a polymer
Has an intrinsic viscosity (measured at 30 ° C. as a 100 ml solution of 0.5 g of polymer in sulfuric acid) of 0.5 or more.

As the stock solution, the polymer solution after neutralization may be used as it is, or once the polymer is isolated,
Those re-dissolved in a solvent may be used. As the solvent,
N-methyl-2-pyrrolidone for easy handling,
Organic polar solvents such as dimethylacetamide and dimethylformamide are preferred, but strong acidic solvents such as concentrated sulfuric acid, concentrated nitric acid and polyphosphoric acid may be used. The polymer concentration in the film forming stock solution is preferably about 2 to 20% by weight.

The membrane-forming stock solution prepared as described above is
The film is formed by a dry method, a dry-wet method, a wet method, or the like, but the dry-wet method is preferable because a high-quality film is obtained.

First, the dry-wet method will be described as an example.

The stock solution is extruded from a die onto a support such as a drum or an endless belt to form a thin film, and then the solvent is scattered from the thin film layer to obtain a polymer sheet which can be peeled from the support. Here, the polymer sheet refers to a self-supporting film or sheet containing a solvent and a dissolution aid in addition to the polymer.

The drying temperature at this time is preferably from 80 to 200 ° C. because the smoothness of the film surface is improved.

The width of the polymer sheet is required to be 50 cm or more from the viewpoint of film productivity, and the width of the sheet is determined when the stock solution is extruded from the die, that is, cast on a support. It is adjusted according to the casting width.

The solvent content of the polymer sheet is from 20 to
Preferably, it is 70% by weight. If the solvent content exceeds 70% by weight, the self-supporting property of the polymer sheet is insufficient, and the stretchability tends to be uneven. If the solvent content is less than 20% by weight, the polymer is partially precipitated and the stretchability tends to be uneven. Or the elongation of the film may be reduced. Such unevenness in stretchability is not preferred because unevenness is likely to occur in the thickness and physical properties of the film. The solvent content of the polymer sheet is more preferably from 30 to 70% by weight, and still more preferably from 30 to 60% by weight, because the thickness and physical properties of the film become more uniform.

The composition of the solvent contained in the polymer sheet is preferably such that when the organic polar solvent and / or the strongly acidic solvent is contained in an amount of 10% by weight or more, the film is not easily broken even when stretched at a high magnification. .

The polymer sheet made of the aromatic polyamide containing the solvent thus peeled off from the support is heated to 70 to 250 ° C. and stretched in the longitudinal direction. Examples of the method for heating the polymer sheet include a method of blowing hot air, a method of directly heating with a roll, and a method of heating with IR. When the temperature of the polymer sheet during stretching is less than 70 ° C., the polymer sheet may not be sufficiently softened, and the polymer sheet may be broken at a low magnification. Since the evaporation proceeds, the polymer sheet may be broken at a low magnification. Since the stretching limit is further improved, the stretching temperature is more preferably 70 to 200 ° C., and 90 to 1 ° C.
More preferably, the temperature is 80 ° C.

The stretching ratio at this time is preferably 1.5 to 5 times. If the ratio is less than 1.5 times, the productivity may be low, or the Young's modulus of the film may not be sufficient. If the ratio exceeds 5 times, the film may be too easily oriented due to excessive orientation of the molecular chains. Since the balance between Young's modulus and elongation of the film is better, the stretching ratio is more preferably 1.5 to 4 times.
5 to 3 times is more preferred.

The stretching section needs to be 3 to 200 cm. It is not preferable to set the stretching section to less than 3 cm because the apparatus is difficult or the stretching property may decrease. If it exceeds 200 cm, the neck-down becomes large, and the physical properties may be uneven, or the flatness may be deteriorated, which is not preferable. The stretching section is more preferably from 4 to 150 cm, and still more preferably from 5 to 100 cm, since the flatness and the physical properties in the width direction are improved. The stretching section referred to here indicates the distance from the contact point to the contact point of the polymer sheet and the roll to be stretched in the section where the stretching temperature of the polymer sheet is maintained when the stretching is performed by a roll. In the case, it indicates the distance between the centers of the chucks.

Further, the stretching speed needs to be 50 to 3000% / sec. If the stretching speed is less than 50% / sec, the drying of the polymer sheet proceeds too much, and the stretching ratio may be undesirably reduced. 3000% /
If the time is longer than seconds, the film surface may be damaged or the film may be broken, which is not preferable. The stretching speed is more preferably 50 to 2800, since the stretchability becomes better.
% / Sec, more preferably 100 to 2500% / sec.

The stress at the time of stretching of 5% is 0.1 to 20.
It is preferably MPa. If it is less than 0.1 MPa, the film is too soft, and thickness unevenness is likely to occur. On the other hand, if the pressure is higher than 20 MPa, the load on the device increases, which is not practical. Since the thickness unevenness of the film becomes better, the stress at the time of stretching of 5% is more preferably 0.5 to 15 MPa, and still more preferably 1 to 10 MPa.
a.

Next, the polymer sheet that has been subjected to the longitudinal stretching step is introduced into a wet process, and is subjected to desalting, solvent removal, and the like. If the heat treatment is performed without passing through the wet process, the surface may be greatly roughened or curl may be generated, which is not preferable.

The film having undergone the wet process is subjected to drying of moisture, stretching in the width direction, and heat treatment. Heat treatment temperature is 20
It is preferably in the range of 0 to 400 ° C. More preferably, it is 240 to 320 ° C. Heat treatment temperature is 200 ℃
If the temperature is less than 400 ° C., the Young's modulus of the film may be reduced. If the temperature exceeds 400 ° C., the crystallization of the film may proceed too much to form a hard and brittle film, which is not preferable.

In the heat treatment, the film may be stretched in the longitudinal or width direction again. Stretching temperature is 200
To 400 ° C, more preferably 240 to 320 ° C. If the stretching temperature is lower than this range, the film is easily broken at the time of stretching, and if it is too high, the molecules are less likely to be oriented and the Young's modulus may be insufficient, which is not preferable.

It is effective to gradually cool the film after stretching or heat treatment, and it is effective to cool the film at a rate of 50 ° C./sec or less.

The dry method is a film forming method in which the wet process is omitted from the dry-wet method, and the other steps need to satisfy the same requirements as the dry-wet method. However, inorganic salts and the like that cannot be removed in the drying step because there is no wet step must be removed from the stock solution for film formation in advance.

Next, the wet method will be described.

The stock solution is extruded from a die onto a support such as a drum or an endless belt to form a thin film, and introduced into a coagulation bath to remove additives such as a solvent and a solubilizing agent. At this time, the coagulation bath is
It is preferable to use a mixed solvent of a good solvent such as a polymerization solvent and a poor solvent such as water. Further, a bath prepared by adding an inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, lithium bromide, and lithium nitrate to a poor solvent may be used.
The polymer sheet from which the solvent has been extracted is peeled off from the support, and is then formed into a film by a method similar to the dry-wet method. The Young's modulus and stretching conditions of the polymer sheet at the time of peeling must satisfy the same requirements as in the case of the dry-wet method. Further, in the wet method, a poor solvent is contained in the solvent in the polymer sheet. However, it is more preferable to contain 10% by weight or more of a good organic solvent such as an organic polar solvent or a strongly acidic solvent because the stretching limit becomes high.

The film of the present invention may be a laminated film. For example, in the case of two layers, the polymerized aromatic polyamide solution is divided into two, and different particles are added, and then laminated. The same applies to the case of three or more layers. As a method of these laminations, known methods, for example,
There are a method of laminating in a die, a method of laminating in a composite pipe, and a method of forming one layer once and forming another layer thereon.

Next, the aromatic polyamide film obtained by the production method of the present invention will be described.

The aromatic polyamide film obtained by the production method of the present invention preferably has a tensile Young's modulus of at least 9.8 GPa in at least one direction and an elongation of at least 5%. If the Young's modulus is less than 9.8 GPa, it may not be possible to withstand high tension and fluctuation in tension at the time of winding during processing or when being formed into a tape and used. Further, when the elongation is less than 5%, the film may be brittle and easily cut. The aromatic polyamide film of the present invention has a Young's modulus in at least one direction of preferably 11.7 GPa or more, and more preferably 12.7 GPa.
A pressure of Pa or more is preferable because it is suitable for thinning a film. Further, it is more preferable that the Young's modulus in all directions is 9.8 GPa or more. Further, the elongation of the aromatic polyamide film of the present invention is more preferably 10% or more, and still more preferably 20% or more, since it has appropriate flexibility when processed into tape.

When the aromatic polyamide film obtained by the production method of the present invention has a moisture absorption of 5% or less, more preferably 3% or less, and still more preferably 2% or less, a dimensional change due to a humidity change can be suppressed. It is preferable because it is possible.

The thermal shrinkage of the aromatic polyamide film obtained by the production method of the present invention at 200 ° C. for 10 minutes is preferably 0.5% or less, and more preferably 0.3% or less. This is preferable because the dimensional change of the loop is small.

The aromatic polyamide film is particularly useful as a base film for a magnetic recording medium, and is also useful for various other uses.

[0051]

EXAMPLES The method for measuring physical properties and the method for evaluating effects in the present invention were carried out according to the following methods. (1) Solvent content of polymer sheet The polymer content is calculated from the weight of the peeled polymer sheet and the weight of the final film. The value obtained by subtracting the weight of the product was taken as the content of the solvent, and the ratio of the solvent to the weight of the polymer sheet was calculated. (2) Measurement of Stretching Speed of Polymer Sheet The polymer sheet was marked, the time required to pass through the stretching section was measured, and the stretching speed was calculated from the stretching ratio during this time. (3) Measurement of stretching stress of polymer sheet It was measured at a relative humidity of 60% using Robot Tensilon RTA (manufactured by Orientec). After peeling the polymer sheet from the support, wrap it with polypropylene film from both sides and sample it to a width of 10 mm and a length of 50 mm without absorbing moisture, set it on Tensilon, peel off the polypropylene film, set the pulling speed and heating temperature to the respective stretching conditions. Was set, and the stress at the time of 5% stretching in the longitudinal direction was measured. As the film thickness, the thickness of the polymer sheet was used.

(4) Neck down ratio After stretching the polymer sheet peeled from the support, the length in the width direction of the film was measured, and the shrinkage ratio calculated by the following equation was defined as the neck down ratio (%). .

(Equation 1) ○, when the neck down rate is 20% or less, 20% to 30%
% Was evaluated as Δ, and 30% or more as X.

(5) Young's modulus and elongation Measured at 20 ° C. and 60% relative humidity using a robot Tensilon RTA (manufactured by Orientec). The test piece is 10mm wide, 50mm long and the pulling speed is 300m
m / min. (6) Thickness unevenness The part held by the chuck in the tenter was omitted by using an Anritsu electronic micro thickness gauge, the film thickness was measured at 10 cm intervals in the width direction, and the value obtained by subtracting the minimum value from the maximum value of the thickness was obtained. . This was measured 10 times continuously at 1 m intervals in the longitudinal direction, and the average value was determined.

Hereinafter, the present invention will be described in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these.

Example 1 Dehydrated N-methyl-2-pyrrolidone was mixed with 80 mol% of 2-chloroparaphenylenediamine and 20 mol% of 4,4'-diaminodiphenyl ether. Dissolve and add 98.5
2-Chloroterephthalic acid chloride was added in an amount of 2 mol%, and the mixture was polymerized by stirring for 2 hours and neutralized with lithium carbonate to obtain an aromatic polyamide solution having a polymer concentration of 11% by weight.

The above aromatic polyamide solution was supplied to a die with an extruder, and was cast on a mirror-like stainless steel belt at a casting speed of 10 m / min. The cast polymer solution was first heated with hot air at 160 ° C. and then at 180 ° C. for 1 minute each to evaporate the solvent and peel off. The peeled polymer sheet had a width of 80 cm, a solvent content of 40% by weight, and a stretching stress of 2.8 MPa. This polymer sheet was heated to 120 ° C. and stretched in the longitudinal direction by using a heated roll and changing the rotation speed between the rolls. The stretching conditions are a stretching section of 20 cm and a stretching speed of 120% /
The film was stretched 1.8 times in the longitudinal direction of the film in seconds. Next, the film was passed through a water tank for 2 minutes to perform water extraction of the residual solvent and the inorganic salt generated by the neutralization. Thereafter, the film was stretched 2.3 times in the width direction of the film and heat-treated in a tenter under hot air at a temperature of 280 ° C. and a wind speed of 5 m / sec. Thus, an aromatic polyamide film having a thickness of 4.4 μm was obtained. Table 1 shows the physical properties of the final film.

[Example 2] In Example 1, the film was cast at a casting speed of 15 m / min, the heating temperature was 100 ° C, and the stretching section 5c.
m, and the stretching ratio in the longitudinal direction at a stretching speed of 595% / sec.
A film was formed in the same manner as in Example 1, except that the stretching ratio in the width direction was 7 times and the stretching ratio in the width direction was 2.2 times. The film was excellent in both neck-down ratio and thickness unevenness. Table 1 shows the physical properties of the final film.

Example 3 Dehydrated N-methyl-2-pyrrolidone was combined with 2-chloroparaphenylenediamine corresponding to 40 mol% and 3,4′-diaminodiphenyl ether corresponding to 60 mol%. Dissolve and add 98.5
2-Chloroterephthalic acid chloride was added in an amount of 2 mol%, and the mixture was polymerized by stirring for 2 hours and neutralized with lithium carbonate to obtain an aromatic polyamide solution having a polymer concentration of 11% by weight.

The aromatic polyamide solution was supplied to a die with an extruder, and was cast on a mirror-like stainless steel belt at a casting speed of 26 m / min. The cast polymer solution was heated with hot air at 170 ° C. and then at 180 ° C. for 1 minute each to evaporate the solvent and peel off. The peeled polymer sheet had a width of 80 cm, a solvent content of 35% by weight, and a stretching stress of 12.8 MPa. This polymer sheet was heated to 70 ° C. and stretched for 10 cm at a stretching speed of 1 cm.
The film was stretched 2.6 times in the longitudinal direction of the film at 800% / sec. Next, the film was passed through a water tank for 2 minutes to perform water extraction of the residual solvent and the inorganic salt generated by the neutralization. Thereafter, in a tenter, under hot air at a temperature of 280 ° C. and a wind speed of 5 m / sec,
The film was stretched 2.8 times in the width direction and heat-treated. Thus, an aromatic polyamide film having a total thickness of 4.4 μm was obtained. Table 1 shows the physical properties of the final film.

Example 4 The aromatic polyamide solution of Example 3 was introduced into a mixer together with pure water to precipitate and pulverize the polymer. After washing this polymer with pure water and drying,
The polymer was dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 15% by weight and lithium chloride was 35% by weight based on the polymer. This solution was supplied to a die with an extruder, and a casting speed of 2 was placed on a mirror-like stainless steel belt.
It was cast at 2.1 m / min. The cast polymer solution was heated with hot air at 130 ° C. for 2 minutes to evaporate the solvent and peel off. The peeled polymer sheet had a width of 80 cm, a solvent content of 73% by weight, and a stretching stress of 0.07 MPa.
This polymer sheet is heated to 180 ° C.
The film was stretched 3.4 times in the machine direction at a stretching speed of 250% / sec. Next, the film was passed through a water tank for 2 minutes to perform water extraction of the residual solvent and the inorganic salt generated by the neutralization. Thereafter, in a tenter, the temperature is 280 ° C. and the wind speed is 5 m.
The film was stretched 3.2 times and heat-treated in the width direction of the film under hot air at a rate of / sec. Thus, an aromatic polyamide film having a total thickness of 4.4 μm was obtained. Both the neck down rate and thickness unevenness were slightly larger. Table 1 shows the physical properties of the final film.

Example 5 The aromatic polyamide solution of Example 1 was introduced into a mixer together with pure water to precipitate and pulverize the polymer. After washing this polymer with pure water and drying,
The polymer was dissolved in N-methyl-2-pyrrolidone so that the polymer concentration became 15% by weight.

This solution was supplied to a die with an extruder, and the casting speed was 29.2 on a stainless steel belt having a mirror-like surface.
It was cast at m / min. The cast polymer solution was added to 11
The mixture was heated with hot air at 0 ° C. for 2 minutes to evaporate the solvent and peel off.
The peeled polymer sheet has a width of 80 cm and a solvent content of 1
At 5% by weight, the stretching stress was 25.4 MPa. This polymer sheet was heated to 120 ° C. and stretched 1.6 times in the longitudinal direction of the film at a stretching section of 20 cm and a stretching speed of 350% / sec. Next, the film was passed through a water tank for 2 minutes to extract the remaining solvent with water. Thereafter, the film was stretched 2.0 times in the width direction of the film and heat-treated in a tenter under hot air at a temperature of 280 ° C. and a wind speed of 5 m / sec. Thus, an aromatic polyamide film having a total thickness of 4.4 μm was obtained. Table 1 shows the physical properties of the final film. The elongation was lower than that of Example 1.

Comparative Example 1 In Example 1, the heating temperature during stretching was set to 30 ° C., and stretching in the longitudinal direction was attempted twice or more. However, since the film was broken, the stretching ratio in the longitudinal direction was 1.
A film was formed in the same manner as in Example 1 except that the stretching ratio in the width direction was 3 times and the stretching ratio in the width direction was 1.6 times. Table 1 shows the physical properties of the final film. Compared with Example 1, the elongation was significantly reduced.

[Comparative Example 2] In Example 1, the heating temperature at the time of stretching was 280 ° C, and stretching in the longitudinal direction was attempted twice or more. However, since the film was broken, the stretching ratio in the longitudinal direction was 1.3 times. A film was formed in the same manner as in Example 1 except that the stretching ratio in the width direction was 1.6 times. Table 1 shows the physical properties of the final film.

[Comparative Example 3] In Example 3, the film was cast at a casting speed of 6.4 m / min.
The solvent was evaporated and peeled off by heating with hot air for 1 minute each, and the stretching section was 180 cm, the stretching speed was 30% / sec, the stretching ratio in the longitudinal direction was 2.6 times, and the stretching ratio in the width direction was 1.8.
A film was formed in the same manner as in Example 3 except that the film was doubled. Table 1 shows the physical properties of the final film.

[Comparative Example 4] In Example 5, the film was cast at a casting speed of 69.3 m / min, and heated with hot air at 180 ° C for 2 minutes to evaporate the solvent and peeled off.
C., a stretching section of 250 cm, a stretching speed of 60% / sec, a stretching ratio in the longitudinal direction of 1.7 times, and a stretching ratio in the width direction of 1.8 times. Table 1 shows the physical properties of the final film. A film with a large neck down and large thickness unevenness was obtained.

[Comparative Example 5] In Example 4, the film was cast at a casting speed of 2.1 m / min, heated with hot air at 110 ° C for 2 minutes to evaporate the solvent, and peeled off.
The film was stretched 5.2 times in the longitudinal direction at 800% / sec, but the film was broken and a long film could not be obtained.

[0068]

[Table 1]

[0069]

According to the method of the present invention, it is possible to stretch at a high magnification during the production of an aromatic polyamide film, and it is possible to suppress neck down even when stretching at a high magnification, thereby reducing thickness unevenness and increasing the thickness. Since the high Young's modulus characteristic of the aromatic polyamide can be exhibited by the stretching, the productivity of the aromatic polyamide film can be improved and the cost can be reduced.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) C08L 77:10 C08L 77:10 F term (reference) 4F071 AA56 AF13 AF15 AF21 AH14 BA02 BB02 BB07 BB08 BC01 BC10 4F210 AA30 AG01 AR01 AR06 AR08 AR12 QC02 QC06 QD01 QD06 QG01 QG18 5D006 CB03

Claims (8)

[Claims] When a polymer sheet made of an aromatic polyamide containing a solvent is stretched in a longitudinal direction, the width of the polymer sheet is 50 cm or more, and the polymer sheet at the time of stretching is 7 cm.
A method for producing an aromatic polyamide film, characterized in that the film is heated to 0 to 250 ° C., the stretching section is 3 to 200 cm, and the stretching speed is 50 to 3000% / sec. 2. The method for producing an aromatic polyamide film according to claim 1, wherein the stretching ratio in the longitudinal direction is 1.5 to 5 times. 3. The method according to claim 1, wherein the stress at 5% elongation of the polymer sheet is 0.5%.
The method for producing an aromatic polyamide film according to claim 1 or 2, wherein the pressure is 1 MPa to 20 MPa. 4. The solvent content of the polymer sheet is from 20 to 70.
The method for producing an aromatic polyamide film according to any one of claims 1 to 3, which is in terms of% by weight. 5. The production of an aromatic polyamide film according to claim 1, wherein 10% by weight or more of the solvent contained in the polymer sheet before stretching is an organic polar solvent and / or a strongly acidic solvent. Method. 6. The aromatic ring 8 constituting the aromatic polyamide
The method for producing an aromatic polyamide film according to any one of claims 1 to 5, wherein 0 mol% or more is an aromatic ring having para-orientation. 7. The method for producing an aromatic polyamide film according to claim 6, wherein the aromatic polyamide contains at least 60 mol% of a repeating unit represented by the formula (3). Formula (3): 8. An aromatic polyamide film obtained by forming a film by the production method according to claim 1.