JPS621976B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel solution compositions of aromatic polyamides. More specifically, the present invention provides a novel aromatic polyamide composition that is economically advantageous and can be molded for multiple purposes using a halogenated hydrocarbon, a general-purpose solvent that is inexpensive, has a low boiling point, and is highly safe. Aromatic polyamide has excellent heat resistance and can be molded into fibers, films, resins, paper, etc., and is used for clothing,
It is a material that has been widely used in recent years for materials, electrical insulation, etc. On the other hand, aromatic polyamide, which is a material with such excellent performance, has an extremely high melting point, and a melting point close to the decomposition point, so it is virtually impossible to melt and mold it, and it is difficult to make into fibers, films, or paper. To mold, the polymer is once dissolved in a polar organic solvent such as dimethylformamide, N-methyl-2-pyrrolidone, or dimethylacetamide, and the polymer solution is extruded through a nozzle, die, or orifice into a liquid bath or gas stream. At present, so-called wet or dry molding methods are used to remove the solvent. However, these methods have drawbacks such as requiring large amounts of expensive organic solvents and requiring the use of large amounts of organic solvents for solvent recovery, resulting in large costs, and are not necessarily satisfactory. do not have. Needless to say, one possible method for solving this drawback is a high-concentration molding method that reduces the amount of the expensive organic solvent used. However, aromatic polyamides mainly composed of m-phenylene isophthalamide, which is one of the representative aromatic polyamides, are different from general polymers.
At the current state of the art, high concentration molding cannot be easily achieved due to the major obstacle of crystallization and indissolution occurring at high concentrations and high temperatures. One way to solve this problem is to mix an aromatic polyamide polymer mainly composed of m-phenylene isophthalamide with a large excess of N-methyl-2-pyrrolidone, hexamethylphosphoramide, 2-pyrrolidone and ε- JP-A No. 52-13545, 52-15675, 52-53068, 52-
98764 and Japanese Unexamined Patent Publication No. 101298/1984. However, when synthesizing a crystalline complex, this method requires the use of a larger amount of expensive polar organic solvent than conventional methods, which may not only defeat the original purpose of reducing the amount of expensive organic solvent used. However, the method of removing high boiling point organic solvents under reduced pressure is extremely disadvantageous from an industrial and energy standpoint. In addition, the obtained crystalline complex can be melt-molded at relatively low temperatures and for a short period of time, but the thermal stability of the crystalline complex is not necessarily sufficient and there are major problems in applying it to industrial processes. It is considered to be left behind. In view of this background, the present inventors conducted extensive research to obtain an aromatic polyamide solution composition that requires essentially a small amount of expensive organic solvent, is thermally stable, and can be molded for multiple purposes. Halogenated hydrocarbons, which are versatile solvents with low boiling point and safety, - Amide solvents - Aromatic compounds containing alkali or alkaline earth metal salts of bromine or chlorine or ammonium halide salts within a specific range The polyamide solution composition is thermally stable, uses an essentially small amount of expensive amide solvent, and contains low boiling point halogenated hydrocarbons. The present invention was achieved by discovering the fact that it is possible to provide a multi-purpose aromatic polyamide composition for molding, which can be processed into various molded products since it can be contained homogeneously. That is, the present invention consists of an aromatic polyamide (P) in which 75 mol% or more of the repeating structural units are m-phenylene isophthalamide, an amide solvent (S), and a halogenated hydrocarbon (H), and each composition ratio is Within the range of rectangle ACDF in the triangular coordinates of Figure 1, and one or more alkali or alkaline earth metal salts of bromine or chlorine are blended in a range of 5 to 60% by weight based on the aromatic polyamide. The basic idea is to provide an aromatic polyamide composition consisting of: The aromatic polyamide that is the object of the present invention is obtained by reacting m-phenylenediamine with an isophthalic acid halide such as isophthalic acid chloride by a method such as solution polymerization or interfacial polymerization, in which at least 75 mol% of the repeating structural units are obtained. m-phenylene isophthalamide, and the component to be copolymerized as necessary is p-phenylenediamine as an amine component,
Examples include benzidine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, xylylene diamine, toluenediamine, 4,4'-diaminodiphenyl sulfone, and terephthalic acid as the acid component. Chloride, 1,4-naphthalene dicarboxylic acid chloride, 2,6-naphthalene dicarboxylic acid chloride, diphenylsulfone-4,4'-dicarboxylic acid chloride, 4,
Typical examples include dicarboxylic acid halides such as 4'-diphenyldicarboxylic acid chloride. The amide organic solvents used in the present invention include dimethylformamide, dimethylacetamide,
Representative examples thereof include N-methyl-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea, N-acetylpyrrolidine, etc., but are not limited to these. Any amide-based organic solvent that can be dissolved can be used. The present invention uses halogenated carbon, which is a low-cost, highly safe, general-purpose solvent, in the composition to produce a stable aromatic polyamide that essentially reduces the amount of expensive and high-boiling amide-based organic solvents used. One major feature of the present invention is that it can provide a solution composition. It is a well-known fact that halogenated hydrocarbons are generally poor solvents for aromatic polyamides, coagulants and gelation promoters for the aromatic polyamide-amide solution compositions. . Therefore, it has been common knowledge that it is extremely difficult to obtain a moldable stable aromatic polyamide solution composition containing a halogenated hydrocarbon. The metal salt is blended in a range of 5 to 60% by weight based on the aromatic polyamide, and the rectangle in the triangular coordinates in Figure 1 is
When the mixing ratio of the aromatic polyamide, amide solvent, and halogenated hydrocarbon is set within the range of ACDF, surprisingly, a technique has been discovered to obtain an extremely homogeneous and stable solution composition. That is, the mixing ratio of halogenated hydrocarbons is limited within the range of the rectangle ACDF in the triangular coordinates.
Depending on the purpose, the viscosity of the composition is relatively low and it is advantageous for molding.
It is more preferable that it be within the range of ABEF. Of course, as mentioned above, the composition does not consist only of the aromatic polyamide, amide solvent, and halogenated hydrocarbon. A long-term stable solution composition cannot be obtained using only the above three components, and gelation or coagulation/separation of the polymer occurs when left for a long time. In order to obtain a stable composition according to the method of the present invention, the alkali or alkaline earth metal halide salt must be blended in an amount of 5 to 60% by weight, more preferably 10 to 50% by weight, based on the aromatic polyamide. If the halogenated metal salt is less than 5% by weight based on the aromatic polyamide, the composition will be unstable and cannot be used. On the other hand, if it exceeds 60% by weight, the solution viscosity of the resulting composition will be low. The concentration is extremely high compared to the polymer concentration, which is not preferable. Representative examples of such metal salts or ammonium salts include lithium chloride, calcium chloride, magnesium chloride, lithium bromide, calcium bromide, and ammonium bromide, and one or more of these may be used alone or as a mixture. used. It is a well-known fact that the addition of metal salts such as lithium chloride and calcium chloride improves the solubility and solution stability of aromatic polyamides mainly composed of m-phenylene isophthalamide in amide solvents. In this case, it is limited to a polymer solution of the polymer and an amide solvent,
Furthermore, there is only knowledge about the behavior of solution compositions with a polymer concentration of 25% by weight or less. In fact, the behavior of the composition in the method of the present invention, which contains a large amount of halogenated hydrocarbon, which is considered to be a poor solvent for the polymer and a gelling agent for the solution composition, and has a high polymer concentration is Not only is this a completely unknown area, but it has also been said that it is difficult for aromatic polyamide compositions containing halogenated hydrocarbons to exist stably, but within the specific scope of the present invention, it is possible to The fact that it can work effectively is an extremely new fact and a phenomenon that deserves special mention. That is, in the area outside the range of the rectangular ACDF in the triangular coordinates defined in FIG. It is impossible to use it as a molding composition. The halogenated hydrocarbons used in the method of the present invention are monochloromethane, dichloromethane, chloroform, 1,1 dichloroethane, 1,2 dichloroethane, 1,1,2 trichloroethane, 1,1,2,
Representative examples include chlorinated hydrocarbons such as 2-tetrachloroethane, brominated hydrocarbons such as monobromomethane and dibromoethane, and fluorinated chlorinated hydrocarbons such as trichlorotrifluoroethane. It is also possible to use a mixture of one or more species. However, from the viewpoint of versatility and low price, dichloromethane, 1,2 dichloroethane, 1,1,2 trichloroethane, 1,1,2,
Chlorinated hydrocarbons such as 2-tetrachloroethane are particularly preferably used. There are no particular limitations on the method for obtaining the composition of the present invention, and any method may be used as long as a composition of a predetermined proportion is obtained. It can be easily obtained by thoroughly mixing the pulverized metal salt and the aromatic polyamide powder in advance, and then adding a mixed solvent of an amide solvent and a halogenated hydrocarbon in a predetermined ratio while cooling, and uniformly dissolving the mixture. Generally, when obtaining a solution composition by dissolving an aromatic polyamide mainly composed of m-phenylene isophthalamide in an amide solvent, the aromatic polyamide mainly composed of m-phenylene isophthalamide-amide solvent is cooled under deep cooling. It is said that an excellent method for obtaining a homogeneous and stable polymer solution is to employ the so-called slurry dissolution method in which the mixture is first made into a slurry (at a temperature below -20°C) and then dissolved by heating. Although the slurry dissolution method is certainly an excellent method for obtaining a homogeneous solution composition,
There were also some points that it was difficult to say that this method was necessarily advantageous in terms of energy, such as requiring the following cooling. However, when a mixed solvent of an amide solvent and a halogenated hydrocarbon is used, which is one of the typical formulations of the method of the present invention, it becomes extremely easy to form a slurry, and depending on the type of composition, it is possible to form a slurry at room temperature. is possible,
Another feature of the present invention is that it can be easily made into a slurry by cooling with cold water at a temperature of at most 10°C or less. Of course, as mentioned above, the method for obtaining the composition of the present invention is not limited to the above method, but may include a method in which a metal salt is dissolved in an amide solvent in advance, or a method in which an amide solvent and a halogenated hydrocarbon are used separately. You may use any method of mixing.
Furthermore, it is also possible to obtain the composition of the present invention by adding a halogenated hydrocarbon to a solution composition of an aromatic polyamide-amide solvent-metal salt system while stirring. As mentioned above, the feature of the method of the present invention is that a large amount of inexpensive and highly safe halogenated hydrocarbon can be mixed into the aromatic polyamide-amide solution composition. Based on the novel invention, the high-value solvent can exhibit a dissolving power almost equivalent to that of a good solvent for the aromatic polyamide in the presence of the metal halide salt by being mixed with a highly polar amide solvent. Thus, we have been able to provide a composition that can essentially reduce the amount of amide-based solvents. That is, as clarified in the Examples, solutions of the polymer composition can be prepared by sequentially adding a halogenated hydrocarbon to a polymer composition in a certain aromatic polyamide-amide solvent by various methods. Another excellent feature of the present invention is that the viscosity is significantly reduced, which is not only advantageous in terms of molding, but also provides extremely excellent moldability such as stringiness. The aromatic polyamide composition provided by the method of the present invention is a viscous solution composition that is fluid at room temperature, and can be used to produce fibers, films, sheets, etc. by dry, wet, or semi-dry/semi-wet methods. It can be easily formed into fibrils, etc. When the composition of the present invention method using a halogenated hydrocarbon with a low boiling point such as dichloromethane or dichloroethane is used, not only the amount of expensive amide organic solvent used is reduced, but also the solvent can be removed at low temperature. , suitable for dry molding of the composition. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but it goes without saying that the present invention is not limited to these Examples. In addition, all parts in the examples indicate parts by weight. Example 1 A m-phenylene isophthalamide polymer containing 3 mol% of terephthalic acid units (in N-methylpyrrolidone, the intrinsic viscosity measured at a polymer concentration of 0.5% was
1.36) 10 parts of powder and 2 parts of finely ground calcium chloride of 200 mesh under are mixed thoroughly and mixed with 18.6 parts of dimethylacetamide and dichloromethane.
Add 10 parts of the solvent mixture while cooling with ice water. Mix thoroughly to obtain a pasty mixture. When this was allowed to stand at room temperature, a transparent aromatic polyamide solution composition was obtained. The composition of this mixture was 25.9% by weight of polymer (P);
The amide solvent (S) was 48.2% by weight, the halogenated hydrocarbon (H) was 25.9% by weight, and the halogenated metal salt concentration was 20% by weight based on the polymer. The viscosity of this mixture was measured with a flow tester using a nozzle with a hole diameter of 0.5 mm and L/D = 8.
It exhibited the viscosity shown in Table 1 at a shear stress of 3.0×10 ⁵ dyn/cm ² and was found to have suitable fluidity as a molding composition. By removing the solvent and desalting the composition in a conventional manner, tough fibers and films were obtained. still,
The viscosity of a composition consisting only of a polymer, dimethylacetamide, and calcium chloride without using dichloromethane was extremely high as shown in Table 1, and the effects of the present invention are clear.

[Table] Examples 2 to 4 In the same manner as in Example 1, the compositions of the m-phenylene isophthalamide polymer, dimethylacetamide, and dichloromethane were varied and their fluidity was examined. As shown in Table 2, the results were low viscosity and excellent solution stability.

[Table] Calcium chloride is calculated for each polymer.
Contains 20% by weight. Examples 5 to 8 In Example 1, the compositions of the m-phenylene isophthalamide polymer, dimethylacetamide, dichloromethane, and calcium chloride were variously changed, and the viscosity at 35°C is shown in Table 3. The stability of the composition was excellent.

[Table] Examples 9 to 24 In Example 1, instead of dichloromethane,
Various compositions of polymer, dimethylacetamide, 1,2 dichloroethane and calcium chloride were prepared using 1,2 dichloroethane, and their viscosities were measured in the same manner as in Example 1. Each composition was a stable solution composition, and the results are shown in Table 4.

【table】

[Table] Examples 25 to 33 Various compositions were prepared using N-methyl-2-pyrrolidone in place of dimethylacetamide in Example 1. Each composition was a long-term stable clear viscous liquid, and in some cases was semi-solid (at room temperature). The viscosity of each composition was measured in the same manner as in Example 1 and is shown in Table 5.

[Table] Examples 34 to 38 Various compositions were prepared in Example 1 using lithium chloride instead of calcium chloride and dimethylformamide instead of dimethylacetamide.
The resulting composition was a slightly milky homogeneous viscous mixture and had excellent fluidity. As shown in Table 6, the viscosity of the composition was low enough to be suitable for various moldings.

[Table] Example 39 m-phenylene isophthalamide polymer containing 3 mol% of terephthalic acid units (intrinsic viscosity measured at 0.5% polymer concentration in N-methylpyrrolidone: 1.36)
35 parts of the powder and 7 parts of finely powdered calcium chloride of 200 mesh under were thoroughly mixed, and 65 parts of dimethylacetamide was added thereto under cooling with ice water to obtain a polymer solution. Similarly, to prepare the polymer solution, add 17.5 parts of dichloromethane, 35 parts of dichloromethane,
52.5 parts and 70 parts were further added, respectively, to obtain various polymer compositions. The resulting composition has a pore size of 0.5
When the viscosity was measured with a flow tester using a nozzle with mmL/D=8, the shear stress was 3.0×10 ⁵ dyn/cm ² The viscosity shown in Table 7 was shown, and a significant decrease in viscosity was observed as the dichloromethane content increased. .

【table】

[Table] Comparative Examples 1 to 10 Various compositions outside the scope of the present invention were prepared, and the stability and fluidity of the compositions were examined. The results are shown in Table 8, and in any case, the composition was unstable.

【table】

【table】 [Brief explanation of the drawing]

Figure 1 shows triangular coordinates showing the respective compositions of an aromatic polyamide (P) in which at least 75 mol% of the repeating structural units are m-phenylene isophthalamide, an amide solvent (S), and a halogenated hydrocarbon (H). and P+S+H=100.

【table】

【table】 It is.

Claims (1)

[Claims] 1 Consisting of an aromatic polyamide (P) in which at least 75 mol% of the repeating structural units are m-phenylene isophthalamide, an amide solvent (S), and a halogenated hydrocarbon (H), each composition ratio being as shown in Figure 1. In the range of the rectangle ACDF in the triangular coordinates of
An aromatic polyamide composition characterized in that one or more of alkali or alkaline earth metal halides and ammonium salts are blended in an amount of 5 to 60% by weight based on the aromatic polyamide.