JPS6115091B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to aromatic polyamide solutions.

It is possible to produce molded products such as fibers, films, paper, and pressboard with excellent heat resistance from aromatic polyamide solutions.These molded products not only have excellent heat resistance, but also have flame resistance, It has excellent chemical resistance, morphological stability at high temperatures, thermal decomposition resistance, electrical properties, and mechanical properties, making it extremely valuable industrially.

However, since aromatic polyamide is originally a poorly soluble polymer, for example,
Calcium chloride described in Publication No. 16027,
In most cases, a homogeneous and stable solution is formed only in the presence of metal halides that improve the solubility of the polymer, such as lithium chloride, magnesium chloride, calcium bromide, lithium bromide, and the like. Moreover, even in the presence of these metal halides, they may gel during storage, or when producing films using a dry process, in some cases cloudiness may occur during the early stage of solvent drying, which is thought to be due to polymer precipitation. The disadvantageous phenomenon that is often observed is that only opaque films are obtained.

The present inventors have conducted extensive research in order to obtain an aromatic polyamide solution that is more stable and that can produce a transparent film without polymer precipitation during the initial stage of solvent drying even when the film is obtained by a dry method. As a result, we have arrived at the present invention.

That is, in the present invention, 15% by weight based on the polymer
An aromatic polyamide solution that dissolves the above metal halides and contains at least 10% by weight or more of a polymer, which is characterized by containing 20 to 100% water by weight based on the polymer. be.

The aromatic polyamide referred to in the present invention is a polyamide containing an aromatic diamine as an amine component and an aromatic dicarboxylic acid as an acid component. Copolyamides having a plurality of components or a plurality of both components are also included.
Aromatic diamines include m-phenylene diamine, p-phenylene diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminophenyl ether, 4,4'-diaminodiphenyl sulfone,
4,4'-diaminodiphenyl ketone, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminophenyl sulfone, 3,4'-diaminodiphenyl ether, 1,5-naphthylene diamine, 2,6
- Naphthylene diamine is a typical example, but these aromatic diamines may also have a halogen, a lower aliphatic group, or the like as a nuclear substituent. Further, typical aromatic dicarboxylic acids include isophthalic acid, terephthalic acid, 4,4'-diphenyldicarboxylic acid, 1,5-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, etc. These aromatic dicarboxylic acids may have a halogen, a lower aliphatic group, or the like as a nuclear substituent. The aromatic dicarboxylic acid is generally reacted in the form of an acid chloride with an aromatic diamine in a solvent to form an aromatic polyamide, which is also an industrially practiced method.

Examples of metal halides used in the present invention include calcium chloride, lithium chloride, and magnesium chloride, which are soluble in solvents such as those described in Japanese Patent Publication No. 35-16027 and are effective in improving the solubility of aromatic polyamides. Typical examples include calcium bromide, lithium bromide, etc.
In the present invention, it is necessary that the polymer be present dissolved in the solution in an amount of 15% by weight or more based on the polymer. When the amount of these metal halides is less than 15% by weight based on the polymer, or when they are not present at all, the presence of a large amount of water relative to the polymer as in the present invention may adversely affect the stability of the solution. The object of the present invention cannot be achieved because the properties are impaired.

Examples of aromatic polyamide solvents include dimethylformamide, dimethylacetamide, N-
Polar amide type solvents such as methylpyrrolidone, tetramethylurea, and hexamethylphosphoramide are preferably used.

In the above solvent examples, except dimethylformamide, it can be used as a polymerization solvent, and in this case, hydrochloric acid produced during the reaction after polymerization can be used as an inorganic alkali that produces the metal halide, such as calcium hydroxide, oxidized This is preferred because a solution for direct molding can be produced by neutralizing with calcium, calcium carbonate, lithium hydroxide, lithium carbonate, magnesium hydroxide, magnesium carbonate, or the like.

In addition to the method of directly producing a molding solution without isolating the polymer after polymerization, the polymer is precipitated and taken out with a non-solvent such as water, and then washed and dried with the above polar amide type solvent. Dissolving in aromatic polyamide is also an effective method for producing an aromatic polyamide solution. In the latter method, it is appropriate to dissolve the metal halide in a solvent in advance, or to make it exist in a solution by adding and dissolving it together with the polymer powder.

In either case, the proportion of the polymer in the solution of the present invention must be 10% by weight or more.
When the amount of polymer is less than 10% by weight, molded products with good performance such as films and fibers cannot be made. The suitable amount of polymer varies depending on the type of polymer, but for example, in the case of (m-phenylene terephthalamide) type polymer, it is 12 to
For poly(m-phenylene isophthalamide) based polymers, a polymer concentration of 16 to 24% by weight is suitable for molding.

The amount of water contained in the solution of the present invention is 20 to 100% by weight, preferably 25 to 70% by weight based on the polymer.
It is. When the amount of water does not reach 20% by weight based on the polymer, the stability of the solution is not improved as it is no different from conventional aromatic polyamide solutions, and devitrification phenomenon is observed during film formation. Also 100% by weight
If it exceeds this, polymer precipitation will begin to occur, which is not preferable.

The method of adding water to the aromatic polyamide solution is not particularly limited. For example, when producing a molding solution directly from polymerization, it may be added together with an inorganic alkali during neutralization after polymerization, or it may be added after neutralization. can do. In either case, it is preferable to add a solution of a polar amide type solvent rather than adding water alone because it can be added without causing local precipitation of the polymer, but the formed polymer precipitation may take a long time or Since it can be dissolved by applying temperature, it is also possible to add water alone. It is also a preferred method to introduce water into the solution in the form of steam. When producing an aromatic polyamide solution by redissolving the polymer, it is easiest and preferable to add the necessary amount of water to the solvent in advance, but water may be added alone or added to the solution afterwards. It is also possible to add it in the form.

The aromatic polyamide solution of the present invention thus obtained is very stable and can be stored for a long period of time. Furthermore, the solution has greatly improved moldability, as it eliminates the phenomenon of devitrification when producing a film using a dry process.

Such a solution has already been disclosed in Japanese Patent Application Laid-open No. 46 (1973), which described the presence of water in an aromatic polyamide solution.
This could not have been imagined from the contents of Publication No. 5458 and Japanese Patent Application Laid-Open No. 51-99110.

The present invention will be explained in more detail below using Examples. Note that "parts" in the examples mean "parts by weight."

Comparative Example 1 86.4 parts of m-phenylenediamine was dissolved in 1000 parts of N-methylpyrrolidone, cooled to 0°C, and then 162 parts of terephthalic acid chloride was gradually added while stirring, stirring was continued for 40 minutes, and then 59.2 parts of m-phenylenediamine was dissolved in 1000 parts of N-methylpyrrolidone. of calcium hydroxide was added to neutralize the hydrochloric acid produced by the reaction to obtain a polymer solution. ηinh measured from a portion of this solution was 1.38.

Next, this solution was poured onto a glass plate through a 1 mm slit and immediately placed in a hot air dryer to remove the solvent at 120°C. After about 60 minutes, the thin film became devitrified. was observed. 3
After a period of time, the thin film was taken out and washed with water to remove the remaining solvent and salt, and the film obtained was completely devitrified.

The water content in the polymer solution in this example was 15.3% by weight based on the polymer, the concentration of calcium chloride was 46.6% by weight based on the polymer, and the polymer content was 14.6% of the total weight of the solution.

Example 1 The polymer solution used in Comparative Example 1 was
Stirring was carried out for an hour. The water content in the polymer solution after stirring was 25% by weight based on the polymer. This solution was cast on a glass plate through a 1 mm slit in the same manner as in Comparative Example 1, and heated to 120°C in a hot air dryer.
Solvent removal was performed. This time, unlike in Comparative Example 1, no phenomenon of devitrification of the thin film was observed even after passing for 60 minutes. The thin film taken out after 3 hours was transparent and did not become cloudy even when the remaining solvent and salt were removed by immersion in water. After the obtained film was air-dried, it was heat-treated at 340° C. for 5 minutes at a constant length, and a film with extremely excellent properties was obtained, having a thickness of 67 μm, a strength of 24.1 Kg/mm ² , and an elongation of 98%.

Example 2 89.6 parts of m-phenylenediamine was dissolved in 1000 parts of N-methylpyrrolidone, and after cooling to -5°C, 168 parts of terephthalic acid chloride was gradually added with stirring, and after the addition was completed, the mixture was further stirred for 1 hour. I went to After 1 hour, 61.4 parts of calcium hydroxide was added to neutralize the generated hydrochloric acid to obtain a clear solution.
Next, the entire amount of a solution prepared by dissolving 49 parts of water in 250 parts of N-methylpyrrolidone was added to this solution, and the mixture was further stirred for 2 hours. The resulting solution contained 40% water by weight relative to the polymer, calcium chloride 46.6% by weight relative to the polymer, and relative to the total weight of the solution.
12.2% polymer was present.

Pour this solution onto a mirror-finished stainless steel plate.
Casting was carried out through a 15 mm slit, followed by desolvation in a hot air dryer at 120° C. for 4 hours. After 4 hours, the stainless steel plate was taken out and immersed in water at 0°C, and the film was peeled off from the stainless steel plate. The peeled film was completely transparent.
After thoroughly washing and removing the solvent and salt remaining on the film in water, the film was hung on a frame and air-dried.
Heat treatment was performed at 340°C for 5 minutes. The obtained film had a thickness of 120μ, a strength of 23.4Kg/mm ² , and an elongation of 2%, exhibiting excellent mechanical properties.

Example 3 The storage stability of the aromatic polyamide solution of the present invention obtained in Example 2 and the conventional aromatic polyamide solution obtained in Comparative Example 1 at each temperature of 0.40 and 80°C was observed for 30 days. did. 40 and
At a temperature of 80°C, all solutions remained stable without any change, but at 0°C, the solution of Comparative Example 1 started to become cloudy on the third day and completely solidified on the seventh day. In contrast, the solution of the present invention in Example 2 showed no change even after 30 days, indicating that it was a stable solution even at low temperatures.

Example 4 43.2 parts of p-phenylenediamine and 20 parts of 4,4'-diaminophenyl ether were dissolved in a mixed solvent of 650 parts of hexamethylphosphoramide and 350 parts of N-methylpyrrolidone, and the solution was dissolved in an ice bath. 101.5 parts of terephthalic acid chloride was gradually added while stirring while cooling from the outside, followed by stirring for 15 minutes, and then stirring at room temperature for 1 hour after removing the ice bath. After stirring, the viscous solution was poured into a large amount of water stirred under high-speed shearing to precipitate the polymer, and then the precipitated polymer was washed with water and dried to obtain a copolyamide. The obtained copolyamide had a ηinh of 1.88.

11 parts of this copolyamide were added to 89 parts of N-methylpyrrolidone containing 5% by weight of lithium chloride and 3% by weight of water and stirred to obtain a clear solution. This solution was left at room temperature for 5 days, but the solution remained fluid. When a film was prepared using this solution in the same manner as in Example 2, the film peeled off from the stainless steel plate was completely transparent.

The water content in the polymer solution in this example was 24.2% by weight based on the polymer, the concentration of lithium chloride was 40.5% by weight based on the polymer, and the polymer content was 11.0% of the total weight of the solution.

Comparative Example 2 11 parts of the copolyamide used in Example 4 were added to 89 parts of N-methylpyrrolidone containing 5% by weight of lithium chloride and 0.5% by weight of water and stirred, but the resulting solution was unstable. When it was left at room temperature overnight, it lost its transparency, and after 5 days it had become gel-like and had no fluidity.

The water content in the polymer solution in this example was 4.1% by weight based on the polymer, the concentration of lithium chloride was 40.5% by weight based on the polymer, and the polymer content was 11.0% of the total weight of the solution.

Claims (1)

[Scope of Claims] 1. In an aromatic polyamide solution containing at least 10% by weight or more of a polymer and in which 15% by weight or more of a metal halide is dissolved in the polymer,
An aromatic polyamide solution containing 20 to 100% water by weight based on the polymer. 2. The solution according to claim 1, which contains 25 to 70% water by weight based on the polymer.