JPS58175634A - Manufacture of aromatic polyamide film - Google Patents

Abstract

PURPOSE:To obtain the titled film of improved electrical and mechanical properties and useful for an electrical insulation material, etc. industrially favorably, by stretching the aromatic polyamide film which contains a specified amount of water under a specified condition in wet steam. CONSTITUTION:The purpose film is obtained by stretching the aromatic polyamide film (e.g., a poly-m-phenylene isophthalamide film) which contains at least 40wt% of water in the wet steam above 50 deg.C by 1.1 times or more mono- or biaxially. It is desirable to use the aromatic polyamide film obtained by the wet forming method wherein the aromatic polyamide compound expressed in formula I [(a) is pts.wt. of an aromatic amide; (b) is pts.wt. of an amide solvent] and formula II [(c) is pts.wt. of a co-solubilizer] in its composition ratio is introduced in an aqueous coagulating bath.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing aromatic polyamide films with improved electrical and physical properties.

More specifically, by stretching a specific water-containing aromatic poly(7-amide) film in wet steam at 50°C or higher, it is possible to achieve industrially advantageous continuous hot stretching, while at the same time improving electrical and physical properties. The present invention relates to a technology for obtaining an aromatic polyamide film with excellent quality.

Aromatic polyamides have excellent heat resistance and mechanical properties. BACKGROUND ART Polymers such as nylene isophthalamide and m-phenylene isophthalamide are polymeric materials that have been widely used in the fields of fibers, synthetic papers, etc., and have attracted particular attention in recent years.

Fully aromatic polyamides are generally infusible or the polymer's melting temperature and decomposition temperature are close to each other, so melt molding is difficult, and it is generally molded from a dope using an amide solvent by dry molding or wet molding. Things are being manufactured.

A comparison of the processes in terms of economics, technology, and film performance when producing films by the above-mentioned wet forming method or dry forming method is as follows3.
That is, in the dry molding method, the solvent is removed in a bO heat calculation atmosphere, but the solvents used for molding wholly aromatic polyamides generally have a high Buddha point and a large latent heat of vaporization.

In particular, depending on the type of solvent, the affinity is so strong that some may form complexes with the polymer, so if dry molding is used, it may be economical to remove the solvent, such as requiring a long time at high temperatures. It is a disadvantageous purses.

If a wet molding method is adopted, the above-mentioned difficulties in film production by a dry method can be overcome. However, films obtained from conventional wet-forming processes generally have significantly poorer film performance than those from dry processes. One of the biggest technical challenges when adopting a wet method is the selection of a coagulation bath.

In other words, even if special consideration is given to the coagulation performance, coagulation time, coagulation temperature, etc. of the coagulation bath, there is still a problem in that the film remains inhomogeneous and it is difficult to produce a film with excellent mechanical and electrical performance. Ta.

Thus, high-performance films made of wholly aromatic polyamides have not yet been established on the market, and as sheet materials for electrical insulation materials, fibers and pulp made of polym-phinisophthalamide are used to make paper. Heat-resistant insulating paper obtained by However, it is very difficult for some insulating papers to maintain their insulating function in an electric field of several thousand ports.

As a result of intensive studies on coagulation properties during molding of aromatic polyamide films, the present inventors selected the polymer hardness and solubilization aid concentration in the aromatic polyamide composition, and by introducing it into an aqueous coagulation bath. have already discovered and proposed a manufacturing method that is industrially extremely advantageous.

However, aromatic polyamide films generally have low mechanical properties in an unstretched state and may not necessarily exhibit satisfactory performance.

As a method for stretching an aromatic polyamide film, 3
A method of dry heat stretching at a high temperature of around 00°C or higher or 60-8
Possible methods include swelling and stretching in an aqueous amide solvent at around 0°C. When the dry heat stretching method is applied to an aromatic polyamide film, the wet-formed film produced by the conventional technology is extremely brittle, and even if stretching conditions such as stretching humidity and processing time are varied, stretching is impossible.5- Although it is possible to stretch dry-formed films, dry-formed films contain organic solvents that pose a risk of explosion, making it difficult to stretch them stably over long periods of time. This method also requires high temperatures and is economically disadvantageous.

On the other hand, when the swelling hot stretching method is applied to a film, not only wet-formed films but also dry-formed films tend to swell and become opaque in the swelling solution. It was difficult to obtain.

As a stretching method to solve these problems, JP-A-52-
56169. 53-42263. 53-42266
, No. 53-42267 and No. 53-42268, etc., disclose a method in which an aromatic polyamide film is treated and impregnated with an aqueous solution containing an amide solvent and/or an ionic gold salt, stretched at room temperature, and then washed and dried. However, this method not only requires washing with water after stretching, but also uses amide solvents and ionic gold! This stretching method is extremely disadvantageous in terms of equipment because it requires handling a film impregnated with a highly corrosive compound 6- such as i4 salt, and cannot necessarily be said to be a satisfactory method for industrial production.

Taking these points into consideration, the present inventors investigated various methods for producing aromatic polyamide films that are advantageous for industrial production and have excellent electrical and physicochemical properties. The present invention was developed based on the new knowledge that aromatic polyamide films can be stretched extremely easily in wet steam at a temperature above a certain temperature.

That is, in the present invention, an aromatic polyamide film containing at least 40% by weight or more of water is stretched 1.1 times or more in the -axial or biaxial direction in wet steam at 50°C or higher to form an aromatic polyamide film. This is a method for producing a polyamide film. More preferably, the composition ratio of the aromatic polyamide composition is as follows:
An aromatic polyamide film with a moisture content of 40 weight tqb or more obtained by a wet molding method in which an aromatic polyamide composition represented by the formula % (1) (2) is introduced into aqueous coagulation is moistened at 50°C or higher. This is a method for producing an aromatic polyamide film by stretching the film in the -axial or biaxial direction by a factor of 1.1 times or more in steam.

The aromatic polyamide-based polymer used in the present invention is an aromatic polyamide-based polymer containing repeating structural units represented by the general formula either singly or in the form of a copolymer, and preferably contains 75 or more moles of the structural units. It is an aromatic polyamide-based polymer containing

Here, “l+Arl can be the same or different (
, has the following structural formula as a representative one.

Here, R is lower alkyl, lower alkoxy,
Gen or 2) p group, n is θ including 0 and 4
is an integer of ~4, x is one selected from the following, and Y represents hydrogen or a lower alkyl group.

When carrying out the present invention, it is necessary that the aromatic polyamide film contains at least 40% by weight of water. When the water content is less than 40% by weight and 11%, the stretchability, especially in mixed steam, is significantly reduced and the film cannot be used. It is sufficient that the amount of water contained in the aromatic polyamide film is 40% by weight or more, and more preferably 60% by weight or more. The upper limit is not particularly limited, but the water content is 250~
The film forming limit is up to 300 weight/it%.

In carrying out the present invention, it is necessary that the aromatic polyamide film contains at least 40 ft% of water, but solvents other than water, such as N,N'-dimethylacetamide, N-methyl- An amide solvent such as 2-pyrrolidone may be included if necessary.

The hydrous aromatic polyamide film is (1) Dry-wet film forming method (2) Wet film forming method It can be obtained by

Regarding the method for producing an aromatic polyamide film by a dry-wet film forming method, the aromatic polyamide amide solvent composition was cast and washed under an atmosphere of 150 to 250° C. to remove the solvent, and then washed with water. By this method, an aromatic polyamide film having a water content of 40% or more can be obtained.

As a method for providing an aromatic polyamide film having a predetermined water content used in the method of the present invention, it is particularly preferable to use the wet film forming method described below in terms of industrial production and film properties. That is, a wet film forming method in which an aromatic polyamide composition whose composition ratio is represented by the following formula % (1) (2) is introduced into an aqueous coagulation bath is used to form the film of the present invention. It is particularly preferable to obtain

The amide solvent used here is tetramethylurea, hexamethylphosphoramide, N.

N-dimethylacetamide, N-methylbiridone-2
, N-methylpiperidone-2,N,N-dimethylethyleneurea, N, N, N', N'-tetramethylmalonic acid amide, N-methylcabu-lactam, N-
Acetylbilidine, N,N-diethylacetamide, N-ethylvirridone-2,N,N-dimethylpropionic acid amide.

N, N-dimethylisobutylamide, N,
Examples include N-dimethylpropylene urea, N,N-dimethylformamide, and mixtures thereof.

A particularly preferred amide solvent is N-methylpyridone-2
(hereinafter abbreviated as NMP), N,N-dimethylacetamide (hereinafter abbreviated as DMAC), and mixtures thereof.

Preferably used solubilizing aids include salts of metals of Group 1 and/or Group 1 of the periodic table and ammonium halides. Such salts exist in the polymer solution and serve to enhance the stability of the solution, as described in, for example, Japanese Patent Publication No. 35-16027.

Preferred solubilization aids include lithium chloride, calcium chloride, and magnesium chloride, with calcium chloride being particularly preferred.

In the aromatic polyamide composition used in the present invention, the aromatic polyamide (8), the amide solvent (B), and the solubilization aid (, ) must have the following relationship.

0.5≧a 10b≧0.05・・・・・・・・・・・・
(1) -≧0.1 Music... (2) The above formula (ri) In (2), a is the weight part of the aromatic polyamide,
b + $ parts by weight of amide yarn solvent, and C represents parts by weight of solubilization aid.

In the above formula (1), if --4--<6, o s, sufficient moldability is obtained for the purpose of file molding, and amide-based Since the amount of solvent used is also large, the effects of the present invention cannot be fully enjoyed. on the other hand,
-'--> o, s, the obtained composition (a) has an extremely high liquid viscosity and is often difficult to handle.

In the above formula (2)! Must be ≧0.113
− is. -! -<0.1 it is often difficult to ensure sufficient solution stability. The preferred range is 1≧0.
It is 15. In addition, as a general tendency, the state of the aromatic polyamide composition at room temperature varies depending on the type of solubilizing agent and the 1 tK used, so it is necessary to select the type and amount of the solubilizing agent preferably according to the purpose. is important. In addition, excessive use of solubilization aid 1 For example, brother>
If it is 0.6, the solution viscosity of the composition increases significantly, the hardness tends to be impaired, and in addition, heat absorption during operation becomes a problem, which is not preferable in terms of handling.

Therefore, in practice, the solubilizing agent leaf is preferably 0,1≦
1≦0.6, particularly preferably 0.15≦1≦0.5.

The method for producing the aromatic polyamide composition used in the method of the present invention is not particularly limited, but typical examples include the following: 0) Re-dissolution method (μ) Solution polymerization-neutralization method 14-.

The redissolution method is a method in which aromatic polyamide, amide solvent, and solubilization aid that have been isolated in advance are mixed in a predetermined ratio and redissolved.

A typical method is to dissolve the solubilization aid in an amide solvent and then mix the polymer with the mixture, preferably while cooling.

Depending on the type and amount of solubilization aid used, K may not be completely dissolved in the amide solvent alone, but it often dissolves uniformly when the polymer is further mixed. Alternatively, it is also possible to further mix and pulverize the solubilization aid powder and polymer powder as necessary, and then mix them thoroughly with the amide solvent under cooling.

The compositions of the present invention can also be prepared by solution polymerization-neutralization methods. It is known to prepare a polymer solution by polymerizing an aromatic diamine and an aromatic diacid halide using an amide solvent (for example, Japanese Patent Publication No. 35-1
(See Publication No. 4399). It is also known to prepare a safe polymer solution by subsequently neutralizing the hydrogen halide generated in the polymerization solution to produce the solubilization aid of the present invention (for example, as disclosed in Japanese Patent Publication No. 35-1fi027). reference).

Furthermore, as an excellent method for preparing the aromatic polyamide composition of the present invention by a solution polymerization-neutralization method, a production method using a prepolymer has been proposed (Japanese Patent Application No. 1987-467).
(See Publication No. 45). This method is preferred because it allows the composition ratio of the solubilizing aid in the stock composition to be controlled.

In addition to the above-mentioned pre-solution polymerization method, interfacial polymerization method (Japanese Patent Publication No. 35
-13247) is also used.

It goes without saying that any aromatic polyamide can be used as long as it has the above-mentioned structural units, but it is particularly preferably used in the present invention, and provides essential effects. The aromatic polyamide is a poly-m-polyamide in which at least 75 molar units of retardation units are obtained by reacting m-phenylenediamine with an isophthalic acid halide such as isophthalic acid ρ-ride by a method such as solution polymerization or interfacial polymerization. Phenylene isophthalamide, and the components to be copolymerized as necessary include P-phenylenediamine, benzidine, 4.4'-diaminodiphenyl ether, 3.4'-diaminodiphenyl ether, gysylylene diamine, toluene diamine,
4.4'-diaminodiphenylsulfone etc.,
In addition, acid components include terephthalic acid p-ride, l,4-naphthalenedicarboxylic acid p-lide, 2,6-naphthalenedicarboxylic acid p-lide, diphenylsulfone-4,4
Typical examples include dicarboxylic acid hydrides such as '-dicarboxylic acid chloride and 4,4'-diphenyldicarboxylic acid chloride.

A suitable stock solution composition when such a polymer is used in the present invention will be described below.

When 0,25≦a -1-b≦0,336 17- 0.1≦ - When 0,336□≦0.5, a + b O,028 -X a -0,84 (- a+b above A stock solution composition satisfying the following composition exhibits high thermal stability and appropriate solution viscosity and can be preferably used in the present invention. When using polyamide for this type of fragrance, the preferred polymer concentration is 0.3≦□ ≦0.5,
More preferably a+b O, 336 (intoxication≦0.45).

In the method of the present invention, the wholly aromatic polyamide composition prepared as described above may contain additives, modifiers, etc. exemplified in Section F, if necessary: light stabilizers, Heat stabilizers, antioxidants, crosslinking agents, combustion agents, ultraviolet light shielding agents, antistatic agents, matting agents, color removal of dyes and pigments, various organic and inorganic fillers or reinforcing materials, and many more. plasticizers, solution viscosity modifiers, etc.

18- The composition used in the present invention is usually in the form of a viscous liquid or semi-solid at room temperature.

However, as shown in the examples, even if it is semi-solid at room temperature, it should flow easily at temperatures of 80°C or higher, ensuring appropriate fluidity in the temperature range up to the boiling point of the solvent used. The solution has good thermal stability. Therefore, film forming using not only the conventional wet forming method but also a melt forming machine is possible.

The molding height depends on the composition ratio of the aromatic polyamide composition used,
Although it varies depending on the applied molding method, it is preferably selected from the range of 60 to 180°C. When the molding temperature is lower than 60°C, the solution viscosity of the composition is high, making it difficult to obtain a homogeneous film, and sufficient productivity may not be obtained. On the other hand 1
If the temperature is 80° C. or higher, coloring of the molded product and foaming due to moisture in the composition may occur, which may cause operational problems.

The aromatic polyamide composition of the present invention can be molded by a wet method or a wet air discharge method. Slit nozzle or T
The composition extruded through a die or the like is formed into a film by a wet method.

The f8 type molding method applied to the present invention is the following two methods.

Hemorrhoidal molding method - A method in which the stock solution composition is directly introduced into a coagulation bath and molded. Vacuum [P discharge] - Wet molding method The stock solution composition is once placed in a coagulation bath via a gas such as air, water vapor, V element, etc. How to introduce it inside.

In the present invention, aromatic poly(γ) which generally has low solution viscosity is used.
When using a mid-composition, wet molding method is used,
When the solution viscosity is relatively high, the air discharge-wet molding method is often applied, but it is not necessarily limited to this method, and it depends on the purpose of film production and the physical properties of the stock solution composition. , a more preferable molding method can be selected.

In the present invention, the air discharge-wet molding method is capable of molding with a very high polymer concentration, which has extremely significant effects compared to conventionally known molding methods in the following points. Therefore, the amount of expensive amide solvent used is small.

A molding method similar to melt molding can be applied, and the extrusion speed can be improved.It can provide an extremely productive molding method.A homogeneous, highly transparent film can be produced stably up to a relatively large thickness. Can be manufactured.

Energy costs of manufacturing are reduced.

When dry molding is performed from a stock composition containing a solubilizing aid, a wet washing step is required and the process is complicated. In contrast, the method of the present invention basically consists of only a wet cleaning step, and the process is simple.

As the coagulating bath, at least one bath having the following composition is preferably used for forming the aromatic polyamide film of the present invention.

(1) Inorganic salt aqueous solution (11) Organic solvent aqueous solution 2 l- (iii) Mixed aqueous solution of (D, (ii)) Of course, for the purpose of facilitating the stretching process of the method of the present invention and producing a transparent and tough film, % is an important factor in coagulation, and by combining the above-mentioned aromatic polyamide composition and the above-mentioned coagulation bath, the following stretching becomes possible and a high-performance film can be obtained.

Typical compounds contained in the aqueous solution are CaC4, BaC411ZnC4+MgCt1+Na
CtIKCL I Azc4 + 8 nC4I N
I C1s + S rczl + L I CtHC
OB r* ILIBrCa(Now )m, Z
n(Not) +A4(NOs)4 +C
Examples include e(SCN)* +KSCN, Na8CN, and the like. Preferred inorganic salt is CaC1*
lMgC11, ZnC1- can be mentioned, and (
K is preferably LICL@, CaCtH. Also,
It is generally advantageous for the solubilization aid in the aromatic polyamide composition and the inorganic salt in the solid bath to be the same compound.

Although the preferred inorganic salt concentration varies depending on the type of inorganic salt, the composition or composition ratio of the aromatic polyamide composition, molding conditions, etc., an aqueous solution containing 20% by weight or more of the above-mentioned inorganic salt is preferred. When such a coagulation bath is used, it is possible to produce a film with excellent mechanical performance and transparency. Furthermore, 1w of the target film
Although the coagulation bath composition, temperature, and immersion time are not constant depending on the transparency, the preferred coagulation bath temperature when using an inorganic salt aqueous solution is 40 to 110°C.

An organic solvent aqueous solution can also be used as the coagulation bath. Various alcohols and amide solvents can also be used as the organic solvent. Among various alcohols, alkytone glycol is one of the organic solvents that are preferably selected.

Typical alkyne glycols that can be used include ethylene glycol, propylene glycol, polyethylene glycol, and polyethylene glycol. The concentration of the polyfulquin glycol or glycerin aqueous solution varies depending on the composition or composition ratio of the aromatic polyamide composition, and the molding method or conditions, but generally an aqueous solution of 30% by weight and 11% or more can be used. Suitable temperature conditions vary depending on other factors, but are selected from a range of 30° C. to the boiling point of the coagulation bath.

As a preferred embodiment of the invention, multi-stage coagulation baths are often used. As a multi-stage coagulation bath, it is possible to use it depending on the need, such as the density of the inorganic salt aqueous solution, the different wet and dusty systems, and the completely different coagulation composition. A multi-stage coagulation bath combining coagulation systems is preferred.

After the organic solvent and salt are removed in a water washing step, a homogeneous transparent film having a water content of 40% by weight or more, usually 80% by weight to 200% by weight, can be obtained from the film thus obtained.

In the conventional state of the art, it was believed that it was impossible to stretch a film produced by a mixed molding method in a wet steam bath, but in the wet steam of the method of the present invention, an aromatic polyamide film with a water content of 40% by weight or more can be stretched. is easily stretched at temperatures above 50°C.

(The method of the present invention involves stretching in moist steam at a temperature of 50°C or higher. The wet steam in the method of the present invention refers to an atmosphere with a relative immersion of 80 degrees or higher, and the temperature of the wet steam is preferably 50°C or higher. is preferably 80°C or higher.

If the temperature of the wet steam is less than about 50° C., the stretchability decreases, the stress required for stretching becomes extremely large (not only does it make it difficult to obtain a large stretching ratio, but the final film performance is undesirable).

Furthermore, the stretching ratio is 1.1 times or more, preferably 1.3
In view of the performance of the obtained film, it is necessary to perform two-fold or more biaxial, sequential biaxial, or simultaneous biaxial processing. Stretching ratio is approximately 1.1
If it is less than twice that, the mechanical properties are low, especially the elongation is low and unstable.

From the viewpoint of film homogeneity, etc., the stretching ratio is 1.
．． It is preferably 3 times or more, and preferably 2.3 times or less.

Of course, it is possible to stretch 2.5 times or more depending on the purpose, but from the viewpoint of long-term stability of continuous stretching and balance of mechanical properties of the obtained film, the preferred range of the stretching ratio is 1.3. It can be said that it is ~2.5 times.

25- Furthermore, the so-called steam stretching in submerged steam is characterized by continuous tenter stretching. In other words, regarding axial stretching (stretching in hot water or organic solvent-water baths is fully possible for industrial production, but biaxial stretching in the direction perpendicular to this is usually carried out using a tenter system, Stretching in a bath is difficult due to the equipment involved.Therefore, a substantial wet stretching method has been achieved for the first time by the method of the present invention, and its significance is extremely important.

Therefore, in the uniaxial direction, micrometer stretching is carried out in hot water, and in the biaxial direction, sequential biaxial stretching is carried out in the method of the present invention, such as stretching in wet steam, or simultaneous biaxial stretching is carried out in wet steam according to the method of the present invention. This is a preferred embodiment.

By drying the stretched film obtained as described above under a fixed length, an aromatic polyamide with excellent electrical properties and mechanical properties can be obtained. It can be made into a film with desired strength, elongation, and insulation properties.

26- According to the method of the present invention, a film with excellent transparency, toughness, heat resistance, and electrical insulation can be economically and continuously manufactured.

Although the method of the present invention is effective in the conventionally known methods for producing aromatic polyamide films, it is particularly effective in producing aromatic polyamide films based on m-phenylene isophthalamide polymers. That is,
As a method for forming an aromatic polyamide film mainly made of m-7 enylene isophthalamide polymer, a solution composition consisting of an amide solvent and an aromatic polyamide is generally cast onto a steel belt in the form of a film, and then A method has been proposed in which most of the solvent is evaporated in a hot air dryer and then introduced into water to remove the solubilizing agent and the solvent (Tokkai No. 52-42561, No. 52-52).
No. 57253, No. 52-152973, etc.). However, as described above, these methods require a large amount of heat and high energy cost because it is necessary to remove the high boiling point organic solvent with heat.

Furthermore, after the above-mentioned thermal evaporation, water washing is performed and finally the desolubilization aid and solvent are removed, so the process constitutes a two-stage dry-wet process. .

Furthermore, in film formation by this method, as mentioned above, it is suggested that it is necessary to pre-treat the film in water MN containing an amide solvent and/or an ionic metal salt before stretching. When such stretching is carried out, not only is there a disadvantage that an additional process such as washing with water is required after stretching, but there is also a delay in corrosion of the equipment.

However, if the method of the present invention is employed, the amount of the 7-amide organic solvent used relative to the polymer is small because the aromatic polyamide composition is highly concentrated. In addition, since the film can basically be produced only by a wet method, energy costs are reduced and the process is simplified.

It is no exaggeration to say that the ability to produce a high-performance aromatic polyamide film as described above by the method of the present invention is based on the exquisite balance between the composition of the aromatic polyamide stock solution and the composition of the coagulation bath. isn't it.

Japanese Patent Publication No. 47-41743 proposes a method for forming transparent fibers, tapes, etc. by introducing a solution composition consisting of an aromatic polyamide and an amide solvent into a coagulation bath consisting of an aqueous calcium chloride solution. There is. However, it is stated that if 3% or more of a solubilizing agent such as calcium chloride is contained in this stock solution composition, the performance of the molded product will deteriorate rapidly.

On the other hand, in the method of the present invention, the composition ratio of the polymer and the solubilizing aid such as calcium chloride in the aromatic polyamide composition is specified and made compatible with the coagulation bath, thereby substantially affecting the coagulation property during molding. It does not have any adverse effects, or rather has the effect of significantly improving coagulation properties, making it possible to form transparent and dense films. In particular, the excellent coagulation property ensured by the stock solution composition and coagulation bath composition of the present invention makes the structure of the formed film dense and strong, and also provides high transparency. As a result, it is possible to perform wet stretching, which has been considered difficult with conventionally known wet-formed films, and to provide a film that can be easily stretched in wet steam and exhibits excellent performance.

In other words, for polymers containing poly-m-phenylene isophthalamide with a repeating unit of 75 moles or more, using wet molding would only yield a stretched film with a thickness of about 20 μm at most, which would be of practical use. In contrast, with the method of the present invention, high-performance films of 25μ or more can be easily produced in KW.

In particular, the fact that stretched films of 50μ or more can be stably produced greatly exceeds the technical level of conventional wet film forming, and is worthy of special mention.

The aromatic polyamide film obtained by the method of the present invention has a wide range of uses in industrial materials, insulation materials, FFI structural materials, etc.

Hereinafter, specific examples of the present invention will be illustrated by way of Examples.

30- Also, the excellent solubility of the aromatic polyamide obtained by the method of the present invention and the excellent mechanical properties of the rut obtained therefrom are shown together with comparative examples. In Examples and Comparative Examples, ηlnh refers to the logarithmic viscosity at 30° C. of a solution obtained by dissolving 0.59% of the polymer in 100ml of concentrated sulfuric acid [7].

Example 1 An aromatic polyamide composition having the following composition was prepared using poly-m-phenylene isophthalamide as the aromatic polyamide, N-methyl-2-pyrrolidone as the amide solvent, and CaClt as the solubilization aid. Prepared.

,, -=0.33 -=0.20 a+b The above composition was 0.1.
.

The sample was extruded from a T-die with a width of 400 ms at 110°C using a casting roller upwardly tilted and introduced into a 43% by weight calcium chloride aqueous solution at 0°C.

Subsequently, it was washed in cold water at 10°C or lower, and then subjected to 1.5 times machine direction (MD) Ic Gff-to-color elongation in hot water at 95°C.

This film contained 130% water by weight.

Hold this film at both ends with clips in an atmosphere of 95°C and relative humidity of 100°C.
Stretched 1.7 times in the transverse direction (TD) at a speed of +/m and held at a constant length with Inc clips at 150°C, 2Q
It was dried in hot air drying at 0°C to obtain a 25p film. The mechanical properties of the obtained film were as follows: strength MD force direction 7.4 Kp/aJ, TDD direction 1
6.4Kg/, j Elongation MD direction 120%, TD direction 110 Initial Young's modulus MD direction 364h/d, TDD direction 3
It was strong and well-balanced with 79Kf/d.

Examples 2 to 4 Example 1 Using hot water-axial roller stretched films with different water contents by varying the coagulation conditions and water washing conditions in the number of layers
Stretching and drying in continuous submerged steam were carried out in the same manner as in .

The results obtained are shown in Table 1.

Table 1 Example 5 The film obtained in Example 1 and having a water content of 130% by weight was stretched in various types of wet steam to determine the maximum stretching ratio.

The results are shown in Table 2.

33- Table 2 Example 10 Poly-m-phenylene inphthalamide as aromatic polyamide, N-methyl-2-hyql as amide solvent
), an aromatic polyamide composition having the following composition was prepared using Ca C4 as a solubilization aid.

Erosion=0.2, -! -20.2 The above composition was cast onto a glass plate with a doctor knife, and 1
After partially evaporating and removing N-methyl-2-pyrrolidone in a 501: hot air dryer for 20 minutes, the sample was immersed in water. Naturally peeled off from a glass plate = 34- A film containing 190 weight of water was heated 9 times in a saturated steam atmosphere at 90°C -i! II] Sequential stretching was carried out. After stretching, it was dried under constant length to obtain a 30μ film. The mechanical properties of the obtained film were excellent, with a strength of 17.8 Kty/J, an elongation of 78%, and a Young's modulus of a75 Ky/-.

Examples 11 to 16 In Example 10, various aromatic polyamides were used and various compositions were adjusted to obtain hydrated aromatic polyamide films.

These films were stretched at the same temperature at 90° C. in a saturated steam atmosphere, and dried under a fixed length to obtain various films. The resulting film was as good as the third coat.

Table 3 Patent applicant Teijin Ltd. Agent Patent Attorney Former 1) Jun Hiroshi 37-

Claims (1)

[Claims] 1. An aromatic polyamide film containing at least 40% water by weight in humid steam at 50°C or higher.
1. A method for producing an aromatic polyamide film, which comprises stretching in the axial or biaxial direction by more than 2 times. 2. An aromatic polyamide film containing at least 40% by weight of water is obtained by introducing an aromatic polyamide composition whose composition ratio is represented by the following formula: % formula % (1) (2) into an aqueous coagulation bath. A method for producing an aromatic polyamide film according to claim 1, which is obtained by a wet molding method. 3. The method for producing an aromatic polyamide film according to claim 1 or 2, wherein the aromatic polyamide is a polymer in which at least 75 moles of the structural units are m-phenylene isophthalamide.