JPS6157408B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a novel method for producing aromatic polyamide fibers. More specifically, the present invention relates to an economical method for producing aromatic polyamide fibers using a small amount of solvent from a poly(m-phenylene isophthalamide) polymer. [Prior art and its problems] Aromatic polyamide polymers containing m-phenylene isophthalamide as the main repeating unit have excellent heat resistance, and their fibers have recently been used for protective clothing, industrial materials, electrical insulation, etc. It is a material that is widely used and attracts attention. Aromatic polyamide, which is a material with such excellent performance, has an extremely high melting point,
Moreover, since the melting point is close to the decomposition point, it is virtually impossible to melt-form the polymer, and in order to spin the polymer, an amide-based organic compound such as dimethylformamide, N-methyl-2-pyrrolidone, dimethylacetamide, etc. Currently, the so-called wet spinning method or dry spinning method is employed, in which the polymer solution is dissolved in a solvent and extruded from a spinning nozzle into a coagulable liquid bath or a high-temperature gas stream to remove the solvent. (Refer to Publication No. 35-13247 and Special Publication No. 17551-1982). However, in order to obtain a solution viscosity suitable for spinning, it is necessary to keep the polymer concentration below 20% by weight, so these methods require large amounts of expensive organic solvents and also require large amounts of solvent recovery. Since it requires the use of an organic solvent (extraction agent), it has drawbacks such as high production costs, and is not necessarily satisfactory from an industrial perspective. Needless to say, one possible method for solving this problem is a method of spinning from a highly concentrated solution, which reduces the amount of organic solvent used. However, aromatic polyamide polymers have the major problem of crystallization and indissolubility occurring at high concentrations and high temperatures, so it has not been possible to easily mold them at high concentrations. [Object of the Invention] The object of the present invention is to eliminate the drawbacks of the prior art, and to produce aromatic fibers of good quality with high productivity from a thermally stable spinning solution composition that uses a small amount of organic solvent. An object of the present invention is to provide a method for producing polyamide fibers. [Structure of the Invention] The above-mentioned object is to produce (a) an aromatic polyamide in which at least 75 mol % of the repeating units are m-phenylene isophthalamide in an amount of 28 to 50% by weight, and (b) an amide organic solvent 72 to 50% by weight. % by weight and (a) + (b) = 100%, and (c) at least one solubilization aid selected from lithium chloride, calcium chloride, and magnesium chloride. , y mol% shown in the following formula with respect to the aromatic polyamide (a) When 28≦x≦33.6, 60≧y≧10 (b) When 33.6<x≦50, 60≧y>2.8x−84 However, y is the mol% of the solubilization aid, and x is the weight% of the aromatic polyamide ((a)/(a)+(b)×100).
This is achieved by the method for producing aromatic polyamide fibers of the present invention, which is characterized in that the fibers are heated to 180° C., extruded through a spinneret into a gaseous medium, and then introduced into a coagulable liquid. In the method of the present invention, a polyamide in which 75 mol% or more of the repeating units is m-phenylene isophthalamide is used as the aromatic polyamide polymer. Such polymers include poly-m-phenylene isophthalamide or copolymers copolymerized with a small amount (25 mol % or less) of a third component, such as poly-m-phenylene isophthalamide.
m-phenylene isophthalamide/terephthalamide copolymer, poly-m-phenylene/p-phenylene isophthalamide copolymer, or poly(4-methyl-1,3-phenylene)isophthalamide, poly(2-methyl-1,3 -phenylene)/(4-methyl-1,3-phenylene)isophthalamide copolymer, poly-m-phenylene terephthalamide, poly-p-phenylene isophthalamide, and the like. Representative amide organic solvents used in the method of the present invention include dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea, and N-acetylpyrrolidine. However, the solvent is not limited to these, and any amide organic solvent that can dissolve the aromatic polyamide polymer can be used. On the other hand, the solubilization aid used in the method of the present invention is
These are lithium chloride, calcium chloride, and magnesium chloride. These may be used alone or in combination of two or more. The aromatic polyamide composition for spinning used in the present invention includes (a) 28 to 50% by weight of the aromatic polyamide;
(b) Amide organic solvent 72 to 50% by weight [(a) + (b)
= 100% by weight] and the solubilizing aid (c) needs to be contained in an amount shown by the following formula. When 28≦x≦33.6 60≧y≧10 When 33.6<x≦50 60≧y>2.8x−84 where y: mol% of solubilization aid x: weight% of aromatic polyamide ((a) / (a) + (b) × 100) If the wholly aromatic polyamide is less than 28% by weight, not only is it disadvantageous that the amount of amide solvent used is large;
The spinnability effects described below cannot be fully exhibited.
Furthermore, when the aromatic polyamide content exceeds 50%, the solution viscosity of the resulting composition becomes extremely high, and it is often difficult to handle it. A particularly preferred aromatic polyamide concentration range is 30 to 45% by weight. Furthermore, if the content of the solubilizing aid is less than the amount shown by the above formula, it is often difficult to ensure sufficient solution stability. When the amount of solubilizing aid used increases and y>60, the solution viscosity of the composition increases significantly, and moisture absorption during operation becomes a problem, which is unfavorable in terms of handling. Although the method of preparing the aromatic polyamide composition for spinning in the method of the present invention is not particularly limited, the following methods are generally employed. (a) Re-dissolution method The re-dissolution method is a method in which the aromatic polyamide, the Amdo solvent, and the solubilization aid, which have been produced and isolated in advance, are mixed in a predetermined proportion 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, the entire amount may not be 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 the polymer powder as necessary, and then mix the amide solvent while cooling after thorough mixing. (b) Solution polymerization-neutralization method The spinning composition of the method of the present invention can also be prepared by a solution polymerization-neutralization method. It is known to polymerize an aromatic diacid halide using an amide solvent to prepare a polymer solution (see, for example, Japanese Patent Publication No. 14399/1983). It is also known to prepare a stable polymer solution by subsequently neutralizing the hydrogen halide produced in the polymerization solution and producing the solubilization aid specified in the present invention (for example, Japanese Patent Publication No. 35-16027 (see publication). Furthermore, as an excellent method for preparing aromatic polyamide compositions by solution polymerization-neutralization, we have proposed a production method via a prepolymer (see Japanese Patent Application No. 46745/1983). This method is preferred because the composition ratio of the solubilizing aid in the stock composition can be controlled. In the method of the present invention, regardless of which method (a) or (b) is adopted, the final composition is adjusted so that the amounts of the polymer, amide solvent, and solubilizing agent are within the above ranges. If necessary, for example, a separately prepared polymer may be added to the polymer composition obtained by solution polymerization. In the method of the present invention, the aromatic polyamide solution composition for spinning prepared as described above may optionally contain a light stabilizer, a heat stabilizer, an antioxidant, a crosslinking agent, a flame retardant, a UV blocker, Antistatic agents, matting agents, coloring agents such as dyes and pigments, various organic and inorganic fillers, various other plasticizers, solution viscosity regulators, etc. can be added. The spinning composition used in the method of the present invention is usually a highly viscous liquid or semisolid at room temperature. However, even if it is semi-solid at room temperature, it flows easily at temperatures above 80°C, and proper fluidity can be ensured in the temperature range up to the boiling point of the solvent used, and the thermal stability of the solution also increases. In good condition. Therefore, the preferred discharge (spinning) temperature is selected to be in the range of 80 to 180°C, although it varies depending on the composition ratio of the aromatic polyamide composition used. The spinning temperature is
If the composition is lower than 80°C, the solution viscosity of the composition is high, making it difficult to obtain good discharge, and sufficient productivity may not be obtained. On the other hand, at temperatures above 180° C., the molded product may be colored and foaming may occur due to moisture in the composition, which poses operational problems. The above-mentioned spinning composition, as mentioned above, has a molecular weight of 80 to 180
extruded into a gaseous medium at °C. The extruded filament is passed through a gaseous medium and then immersed in a coagulable liquid (liquid that has coagulability with respect to the composition). The coagulable liquid used in the method of the present invention may be water at room temperature or cold water, but more homogeneous filaments can often be obtained by using the following liquids. (i) Inorganic salt aqueous solution Typical compounds contained in an inorganic salt aqueous solution are CaCl ₂ , BaCl ₂ , ZaCl ₂ , MgCl ₂ ,
NaCl, KCl, _AlCl3 , _SnCl2 , NiCl, _SrCl2 ,
LiCl, _CaBr2 , LiBr, Ca( _NO3 ) ₂ , Zn
( _NO3 ) ₂ , Al( _NO3 ) ₃ , Ca(SCN) ₂ , KSCN,
Examples include NaSCN. Preferred inorganic salts include CaCl ₂ , LiCl, MgCl ₂ and ZnCl ₂ , particularly preferably LiCl,
_CaCl2 . Furthermore, it is generally advantageous that the solubilizing aid in the aromatic polyamide composition and the inorganic salt in the coagulation solution described below are the same compound. Although a suitable inorganic salt concentration varies depending on the type of inorganic salt, composition or composition ratio of the composition, spinning conditions, etc., an aqueous solution containing 20% by weight or more of the above-mentioned inorganic salt is preferable. Further, when using an aqueous inorganic salt solution, a suitable temperature is 40 to 110°C. (ii) Aqueous solution of organic solvent Various alcohols and amide solvents can be used as the organic solvent of the aqueous organic solvent solution. Among various alcohols, alkylene glycol is one of the organic solvents that can be preferably selected. Typical alkylene glycols that can be used include ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol. The concentration of the polyalkylene glycol or glycerin aqueous solution varies depending on the composition or composition ratio of the aromatic polyamide composition and spinning conditions, but generally an aqueous solution of 30% by weight 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. (iii) Halogenated hydrocarbon A halogenated hydrocarbon bath can also be used as the coagulation bath. As the halogenated hydrocarbon, various aliphatic and alicyclic halogenated hydrocarbons such as methylene chloride, dichloroethane, tetrachloroethane, dichloroethylene, tetrachloroethylene, chloroform, carbon tetrachloride, chlorocyclohexane, and chlorobenzene are used. be able to. Practically preferred are methylene chloride, dichloroethane, chloroform, carbon tetrachloride, and chlorobenzene, and particularly preferred are methylene chloride and dichloroethane. (iv) Alcohols Also, isopropyl alcohol as a coagulating liquid,
Alcohols such as butyl alcohol, benzyl alcohol, alkylene glycols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol can also be used. In the method of the present invention, each coagulation bath can be configured alone or in combination with two or more types of coagulation baths. For example, when water at room temperature is used as the first bath, the filament may devitrify, especially if the polymer concentration in the aromatic polyamide composition is low.
70 containing 30-50% calcium chloride as a second bath
By using an aqueous solution at ~110°C, devitrification can be recovered and a yarn with more uniform gloss can be obtained. The yarn obtained as described above can be wound once and further subjected to washing and drawing steps to obtain the final yarn, or it can be continuously subjected to washing and drawing steps. As the stretching method, it is preferable to perform primary stretching such as in-air hot pin stretching, hot water stretching, or steam stretching in a state containing a solvent, and then drying and hot stretching after thoroughly washing and removing a bathing agent. It will be done. [Effects of the Invention] As described above, the method of the present invention can greatly reduce the amount of solvent used compared to conventional wet or dry spinning methods, and can also reduce the amount of solvent used in large amounts and high boiling point solvents, unlike dry spinning methods. Not only does it not only make it possible to produce aromatic polyamide fiber economically, as it does not require energy to dry-remove it and is simple in terms of equipment, it also allows for faster spinning, resulting in high productivity. A spinning method is provided. Furthermore, the method of the present invention has the advantage that thick tenier yarn (single yarn 20 de to 1000 de) with excellent homogeneity and mechanical properties can be spun with high productivity, which is considered impossible with conventional wet or dry methods. It is something. [Examples] The method of the present invention will be explained in more detail with reference to Examples below, but it goes without saying that the present invention is not limited to these Examples. Example 1 Poly-m-phenylene isophthalamide polymer powder (polymer concentration in N-methyl-2-pyrrolidone
The intrinsic viscosity measured at 30°C for a 0.5% solution is
1.32), 63.5 parts of dimethylacetamide, and 3.8 parts of powdered lithium chloride were mixed under ice cooling to obtain a paste-like mixture (x=37.5, y=28.5). This mixture was supplied to a screw type extruder, metered with a gear pump, and then extruded into air at 140° C. through a spinneret with a hole diameter of 0.5 mm and a number of holes of 5 at a rate of 40 g/min.
After passing through the air for about 2 m, it was wound around a roller immersed in 25°C water at a circumferential speed of 80 m/min, and then wound into a winder. The spinning condition was good, and the obtained yarn was a homogeneous yarn with little devitrification. This yarn was stretched 2.3 times on a hot pin with a surface temperature of 120°C, and after washing and drying, it was stretched 1.3 times on a hot plate at 340°C. The obtained yarn was glossy and homogeneous, and the yarn quality was also good as shown below. Single yarn fineness 110 de Strength 4.1 g/de Elongation 21% Initial Young's modulus 95 g/de Example 2 Poly-m-phenylene isophthalamide polymer powder (solid viscosity 1.35) 30 parts, N-methyl-2-pyrrolidone 70 parts of calcium chloride and 6 parts of calcium chloride were mixed and stirred under ice cooling, and further heated to 80°C to obtain a homogeneous solution (x=30, y=21.5). The pore size is 0.2 at 140℃.
mm, extruded into air at a speed of 9.5 g/min from a spinneret with 5 holes, passed through the air for about 10 mm, introduced into a coagulation bath consisting of water at room temperature, and passed through a roller at a circumferential speed of 30 m/min. I adopted it. The obtained thread was glossy and uniform. Subsequently, after washing in a water bath, soak in hot water at 90°C.
Stretched to 2.0 times and dried at 340℃ with a drying roller.
It was stretched 1.9 times on a hot plate and wound at 115 m/min. The obtained yarn was rich in luster and had good quality as shown below. Single yarn fineness 44 de Strength 5.1 g/de Elongation 18.5% Initial modulus 112 g/de Example 3 Poly-m phenylene isophthalamide polymer powder (solid viscosity 1.22) 28 parts, N-methyl-2-pyrrolidone 72 1 part and 4.2 parts of calcium chloride were mixed and dissolved to obtain a transparent and uniform solution. (x=28, y=
16.1) This was extruded into air at a discharge rate of 1.3 g/min from a spinneret with a hole diameter of 0.08 mmφ and 5 holes held at 160°C, and after passing about 10 mm through the air, 18
After immersion in the first coagulation bath consisting of water at 95°C
Peripheral speed 40 immersed in 40% calcium chloride aqueous solution
m/min onto rollers. Subsequently, the film was washed in a water washing bath, stretched to 1.6 times in a hot water bath at 95°C, further dried with a drying roller, and then stretched to 2.8 times on a hot plate at 340°C. The obtained yarn was glossy and uniform, and its quality was good as shown below. Single yarn fineness 3.4 g/de Strength 4.8 g/de Elongation 22% Initial modulus 98 g/de Example 4 Poly-m-phenylene isophthalamide, N-
Methyl-2-pyrrolidone, calcium chloride x=
37, an aromatic polyamide composition adjusted to a ratio of y = 32.2 was discharged into the air at a speed of 8 m/min from a spinneret with a pore diameter of 0.3 mm and a number of holes of 5 set at 160°C, and then 1 cm from the spinneret. It was introduced into a coagulation bath consisting of a 40% aqueous calcium chloride solution at 90°C. Further, the film was thoroughly washed in a water washing bath, stretched 2.5 times in hot water at 95°C, and dried with a drying roller at 120°C. followed by 350℃
The film was stretched 1.2 times on a hot plate set at The single yarn denier of the obtained fiber is 95de,
It had excellent filamentous bristles with a strength of 4.2 g/de, an elongation of 26%, and a Young's modulus of 101 g/de. Examples 5 to 7 In Example 4, compositions with various polymer concentrations were prepared, and aromatic polyamide fibers were obtained under various spinning conditions. As shown in the table, the results showed excellent thread quality. In addition, the coagulation bath contains 43% calcium chloride aqueous solution at 90%
The temperature was set at ℃. In addition, in Example 5
The stretching ratio in 95°C hot water was 2.3 times, and the stretching ratio on a 350°C hot plate was 1.1 times. In Examples 6 and 7, the stretching ratio in 95°C hot water was 2.5 times, and the stretching ratio on a 350°C hot plate was The stretching ratio was set to 1.3 times. 【table】

Claims (1)

[Claims] 1 (a) At least 75 mol% or more of the repeating units are m-
It consists of 28 to 50% by weight of an aromatic polyamide that is phenylene isophthalamide and (b) 72 to 50% by weight of an amide organic solvent (however, (a) + (b) = 100%), and (c)
A solubilizing agent consisting of one or more of lithium chloride, calcium chloride, and magnesium chloride is added to the aromatic polyamide in y mol% as shown in the following formula (a) When 28≦x≦33.6, 60≧ y≧10 (b) When 33.6<x≦50 60≧y>2.8x−84 Where, y is mol% of solubilization aid x is weight% of aromatic polyamide ((a)/(a)+( b) x 100)).
A method for producing aromatic polyamide fibers, which comprises heating the fibers to 180°C, extruding them into a gas medium through a spinneret, and subsequently introducing the fibers into a coagulable liquid. 2. The manufacturing method according to claim 1, wherein the amide solvent is N-methyl-2-pyrrolidone. 3. The manufacturing method according to claim 1, wherein the coagulable liquid is water. 4. The manufacturing method according to claim 1, wherein the coagulable liquid is an aqueous inorganic salt solution.