JPH0415296B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing thermoplastic synthetic fibers. More specifically, the present invention relates to a method for producing fibers having high strength and excellent workability by drawing fibers made of thermoplastic synthetic polymers at high temperatures and at high magnification or heat treating them. Prior Art In recent years, demands for synthetic fibers have become more sophisticated, and in particular, various new fiber materials have been developed in response to demands for high strength and high modulus. Among them,
For example, aromatic polyamide fibers, especially British patent no.
For substantially para-oriented aromatic copolyamide fibers containing ether bonds in some of the polyamide repeating units, as described in No. 1501948,
In order to achieve this performance, a method is adopted in which the partially drawn yarn is drawn at a high temperature of 300° C. or higher to a full draw ratio of 6 times or higher. In addition, it is also possible to make high-strength fibers by drawing high-molecular-weight polyethylene fibers at extremely high magnifications at high temperatures near their softening point, and to improve fiber properties by heat-treating wholly aromatic polyester fibers at high temperatures for long periods of time. It is being done. However, when drawing or heat treatment is performed at such a high temperature, the yarn becomes significantly softened and a phenomenon of fusion between single fibers occurs. In particular, as the number of filaments in the yarn increases, the fusion increases more and more, and not only does the spinning property deteriorate, but the resulting fibers also become extremely inflexible. In order to solve this problem, a method has been proposed in which a fine inorganic powder is applied to aromatic polyamide fibers prior to drawing or heat treatment to prevent fusion and at the same time improve spinnability (US Pat. No. 4,525,384). However, this method has the disadvantage that the inorganic fine powder applied to the fibers remains even after stretching, which has an unfavorable effect on the processability of the resulting fibers. For example, there are drawbacks such as a decrease in adhesion to the matrix and a decrease in fiber cohesiveness. Purpose of the Invention As mentioned above, the main purpose of the present invention is to prevent the fusion between single fibers that occurs when fibers are drawn or heat-treated at high temperatures, thereby improving yarn-spinning properties, and improving the cohesiveness and processability of fibers. The aim is to improve the quality of fibers and produce high quality fibers. Structure of the Invention The above-mentioned object, according to the present invention, is to form a high-strength fiber by applying an inert inorganic fine powder to a thermoplastic synthetic polymer fiber, and then drawing the fiber to a high magnification at a high temperature or heat-treating the fiber. After drawing or heat treatment, the inorganic fine powder adhering to the fibers is treated with water, and then introduced into an air nozzle and removed by injecting air from the wall inside the tube, This is achieved by producing fibers with excellent cohesiveness and processability. The term "fiber made of a thermoplastic synthetic polymer" as used in the present invention generally refers to undrawn yarns, partially drawn yarns, or drawn yarns of thermoplastic synthetic fibers that can be heat-stretched or heat-treated. Such thermoplastic synthetic fibers can include various types of synthetic fibers that are stretched at high magnification or heat treated at high temperatures that cause fusion between single fibers; typical examples include: Examples include aromatic polyamide fibers that are stretched at high temperatures, polyethylene fibers with a weight average molecular weight of 100,000 or more, and fully aromatic polyester fibers that are heat treated at high temperatures. Suitable aromatic polyamide fibers in the present invention include aromatic polyamide fibers in which 80 mol% or more (preferably 90 mol% or more) of the repeating units constituting the polyamide are -NH-Ar ₁ -NHCO-Ar ₂ -CO- Fibers made of homopolyamide or aromatic copolyamide can be mentioned. [Ar ₁ and Ar ₂ are

【formula】

【formula】

[Formula] represents the same or different aromatic residues selected from However, the hydrogen atom of the aromatic residue may be substituted with a halogen atom and/or a lower alkyl group. ] Methods for producing such aromatic polyamides are described in, for example, British Patent No. 1501948, US Patent No. 3733964, and Japanese Patent Application Laid-Open No. 100322/1983. In the method of the present invention, in the aromatic polyamide, 80 mol% or more of Ar ₁ and Ar ₂ are
The following aromatic residues (A), (B), (B′) [The hydrogen atoms of these aromatic residues may be substituted with a halogen atom and/or a lower alkyl group. Particularly preferred are aromatic copolyamides in which the total molar percentage of the structural units (B) and/or (B') is from 10 to 40%. Examples of such aromatic copolyamides include:
Copolyamides composed of the following three monomer units may be mentioned.

[Formula] 10-40 mol%

[Formula] or 10-40 mol%

[Formula] 50 mol% Aromatic polyamide fibers as described above, especially fibers made of aromatic copolyamides containing ether bonds in a part of the polymer, are produced by drawing undrawn yarn to a high ratio to achieve high strength and high modulus. To make yarn, it is necessary to heat the undrawn yarn to a temperature of 300° C. or higher, preferably 350 to 550° C., and perform "flow stretching" in which the undrawn yarn is gradually stretched without causing necking. For this reason, it is necessary to lengthen the zone in which the yarn is heated to a high temperature so that the heating time until the end of stretching is 0.2 seconds or more. At this time, it has been found that since the yarn is drawn at a high temperature, the single fibers soften and fuse with each other, resulting in poor drawability and deterioration in the quality of the drawn yarn. It has also been found that when the seed fibers are stretched on the hot plate used for stretching, the threads are compressed as an aggregate to the hot plate, which further increases fusion. The same phenomenon occurs when producing high-strength polyethylene fibers. For example, polyethylene with a weight average molecular weight of 1 million is melted in decalin to make a 2% solution, this solution is spun through a spinneret with multiple holes, introduced into cold water and solidified, the solvent is extracted, and then dried.
When stretched approximately 40 times at 120℃ or higher, Young's modulus increases.
High strength fibers with a strength of 50GPa or more can be obtained. However, the single fibers of the dried fibers are stuck to each other before being stretched, and if these are stretched at 120°C or higher, they will partially fuse and lose their flexibility as multifilaments. Furthermore, when a fully aromatic polyester is melt-spun and then heat-treated at a high temperature to produce a high-strength, high-modulus fiber, there is also the problem that fusion between the fibers occurs during the heat treatment. For example, JP-A-50-43223, JP-A-50-
Publication No. 157619 discloses fibers made of various wholly aromatic polyesters. These wholly aromatic polyester fibers are produced by forming highly polymerized polyesters that produce fibers with high strength and high Young's modulus, and when attempting to melt-spun this, the spinnability is poor; After spinning, it is necessary to heat-treat at high temperature for a long period of time to increase the molecular weight and obtain fibers with desired physical properties. Since such heat treatment is carried out at high temperatures for a long time, fusion between fibers cannot be avoided if heat treatment is carried out by a normal method. In the method of the present invention, in the drawing or heat treatment of thermoplastic synthetic fibers that tend to fuse together single fibers during such drawing or heat treatment, an inert inorganic fine powder is first applied to the fiber to uniformly coat the surface of the fiber. A coating of fine inorganic powder is formed, and the fibers are subsequently drawn at high temperatures and high magnification or heat treated. By applying such an inorganic fine powder, it is possible to significantly reduce the phenomenon of fusion between single fibers that could not be avoided in the past, and it is possible to improve the fusion to a state where the fusion is virtually eliminated. The inert inorganic fine powder used in the method of the present invention is one that is chemically stable even at high temperatures during drawing or heat treatment, and that has no chemical effects (such as oxidation) on the yarn.
They are fine particles of inorganic substances that do not have any harmful effects. Regarding the size of inorganic fine powder, the smaller the particle size, the better the average particle size.
Thin fibers with a diameter of 20 microns or less, especially 10 microns or less, are suitable because they adhere uniformly to the surface of single fibers.
There are many inorganic fine powders that can be effectively used in the method of the present invention, among which aluminum silicate,
Particularly preferred are one or more inorganic substances selected from magnesium silicate, graphite, talc, silica, and mica. These fine powders may be used as a single component;
Two or more types may be mixed and used. Further, some of these fine powders become colloidal by hydration in an aqueous dispersion bath, while others are simply dispersed, and both can be used. As a method for applying these fine powders to fibers, it is preferable to prepare a dispersion bath in which the fine powders are dispersed in a dispersion medium such as water in advance, and to dry the fibers after immersing them in the dispersion bath. In addition, in order to uniformly disperse the inorganic fine powder, an organic or inorganic dispersion aid may be added to the dispersion bath, or an antistatic agent or a thickener may be used in combination to improve the cohesiveness of the threads. I don't mind. The amount of inorganic fine powder attached to fibers is 0.5 to 3%.
is appropriate. 1.0 for good stretchability
~2.0% by weight is preferred. On the other hand, when focusing on fibers obtained by drawing or heat-treating by the above method, most of the inorganic fine powder adhering to the fibers remains, and the larger the remaining amount, the more adversely the processability is affected. Therefore, it is necessary to remove the inorganic fine powder adhering to the fibers, but during drawing or heat treatment, the fibers are heated to high temperatures and become semi-molten, so the inorganic fine powder on the fiber surface is easily removed. Will not fall off. For this purpose, in the method of the present invention, the drawn yarn or heat-treated yarn is first subjected to water application treatment. As a specific means for the water application treatment, it is preferable to immerse the fibers in water (including running them in water) or to spray them with a water shower. However, this water application treatment alone does not remove the adhering inorganic fine powder to the extent that the fiber surface is liberated. Therefore,
In the method of the present invention, it is important to further inject an air stream onto the fibers that have been subjected to the water application treatment to blow away the inorganic fine powder liberated by the water application treatment together with the water. The amount of inorganic fine powder produced is effectively reduced. If this residual amount is less than 1.0% by weight, there will be no practical problems in processability. In addition, the effect of this water application treatment and air jet treatment is not only to simply remove inorganic fine powder, but also to moisten the fibers, making it easier to apply finishing oil uniformly, as well as The convergence is significantly improved, and weavability is further improved. As a specific means for the above-mentioned air jet injection treatment, the running yarn is introduced into a tubular part generally called an air nozzle, which has a diameter of 1 to 3 mm and a length of 0.5 to 3 cm, and air is injected from the wall surface inside the pipe. The method has practical advantages. The water application and air jetting treatments may be performed in a separate process after the fiber is once wound up, or may be performed continuously within the process immediately after drawing. Further, if the water application treatment and the air jet treatment are performed in two stages or repeatedly, the effect of removing inorganic fine powder is further enhanced. Effects of the Invention According to the method of the present invention, first, an inert inorganic fine powder is applied to the fibers, and the surface of the single fibers is thinly coated with the inorganic fine powder, thereby suppressing the occurrence of fusion between the single fibers, and By applying both water application treatment and air jet treatment in this order to the fibers that have been drawn or heat treated at high temperature and high magnification, there is almost no fusion between single fibers, resulting in high strength and high strength. It is possible to obtain high-quality fibers that are modulus, have excellent cohesiveness, have good weavability, are free from problems such as scum generation, and have excellent adhesive properties. The resulting fibers can be used in a wide variety of applications, including woven fabrics and reinforcing materials for rubber and resin. Examples Hereinafter, the method of the present invention will be explained in more detail with reference to Examples. Note that the main characteristic values used in the following examples are values measured as follows. (1) Intrinsic viscosity of the polymer (IV) Using an Ostwald viscosity tube, the flow time of the solvent alone is to (seconds), the flow time of the dilute polymer solution is t (seconds), and the polymer concentration in the dilute solution is c.
(g/dl), it is expressed as IV=In(t/to)/c. Unless otherwise specified, solvents are 97.5
% sulfuric acid, c = 0.5 g/dl, and measured at 30°C. (2) Degree of fusion Among the total number of filaments (N) of the drawn or heat-treated yarn, count the number (n) of filaments that are not fused and can be separated one by one, and calculate the degree of fusion using the following formula. . Degree of fusion={(N-n)/2N}×100(%) This measurement is performed five times and the average value is taken. (3) Amount of attached and remaining amount of fine inorganic powder The amount of attached and remaining amount of fine inorganic powder is measured as follows. Prepare fibers that are not coated with finishing oil in advance, and add about 3g of them.
sample. Next, dry at 120°C for 1 hour and weigh. Let this be A(g). This sample is completely incinerated in an incinerator at 800°C. The ash weight after ashing is measured and calculated as B (g) using the following formula. Adhesion amount (or residual amount) = {B/(A-B)}×100(%) Example 1 The following monomer units,

[Formula] 25 mol%

[Formula] 25 mol%

[Formula] A polymer solution prepared by dissolving 6% by weight of an aromatic copolyamide with IV=3.1 composed of 50% by weight in N-methyl-2-pyrrolidone (NMP) containing calcium chloride (CaCl ₂ ), It was extruded from a spinneret with a hole diameter of 0.3 mm and a number of holes of 250 at a discharge rate of 83 g/min. After running about 10 mm in the air, 50℃ NMP/water/
(30/70% by weight) coagulated in a coagulation bath and pulled up at a speed of 11 m/min. Next, the obtained coagulated thread is
While washing in a water bath at 50°C, it was pre-stretched stepwise to 1.3 times, passed through a squeezing roller to remove water adhering to the surface, and then placed in a bath of an inorganic fine powder dispersion having the composition shown in Table 1. The yarn was immersed in a Nelson roller for 5 seconds, and then passed through a squeezing roller to obtain a water-washed yarn (pre-drawn yarn) to which the inorganic fine powder liquid was attached. Subsequently, the washed yarn was passed through a pair of a drying roller with a diameter of 20 cm and a separate roller with a diameter of 3 cm with a surface temperature of 120°C, and a set with a drying roller with a diameter of 1.5 cm and a separate roller with a diameter of 1.5 cm with a surface temperature of 250°C for 10 turns each. The yarn was wound for 5 turns and dried to form a nearly dry yarn, which was stretched and wound at a total stretching ratio of 11.0 times while contacting a hot plate with a surface temperature of 500°C and a length of 1 m. . The obtained drawn yarn is unwound at a speed of 50 m/min to determine the length.
The inorganic fine powder was removed by immersing it in a 1 m water washing bath, pulling it up, and spraying an air stream through an air nozzle. The air nozzle has an inner diameter of 1.5 mm and has a slit for introducing the running yarn. One 1.0 mm air injection hole is provided on the inner wall of the air nozzle.
When the running yarn passes through the air nozzle, the airflow collides with the running yarn, and the attached inorganic fine powder is blown off along with the water content. Air flow usage was 100 l/min. The thus treated drawn yarn was coated with 2% finishing oil and wound at 50 m/min. For comparison, experiments were also conducted in cases where no inorganic fine powder was used and where all or part of the fine powder removal process of the present invention was omitted. These results are shown in Table 1 below. Comparative Example Regarding Experiment No. 5 of Example 1 As in Reference 3, unidirectional air injection was performed using an air nozzle at an air flow rate of 100 l/min. The quality of the obtained fibers was as follows. Remaining amount of inorganic fine powder: 1.2% Total weave: 370 denier Strength: 27.2 g/d Elongation: 4.5% Young's modulus: 650 g/d Degree of fusion: 0.15% Convergence: Class 3 Without introducing the fiber into the air nozzle Maybe because of it,
The cohesiveness of the fibers obtained due to insufficient removal of the inorganic fine powder was not much different from the case in which the air nozzle of the present invention was not used.

[Table] As shown in Table 1, when no inorganic fine powder was used (Experiment No. 1), there was a lot of fiber fusion and the strength was low. When inorganic fine powder consisting of talc/osmos is applied, fusion becomes almost zero, but if no inorganic fine powder removal treatment is performed (Experiment No. 2), the convergence is poor. When the water immersion treatment was performed (Experiment No. 3), a considerable amount of inorganic fine powder was removed, but it was still not sufficient and the focusing property was not improved much. When only air jet was performed using an air nozzle (Experiment No. 4), there was almost no effect. When water immersion is followed by air jet injection as in the present invention (Experiment No. 5), the combination of the two effectively removes the inorganic fine powder and significantly improves the convergence. Example 2 The same aromatic polyamide solution as in Example 1 was
After extruding from a 0.25 mm, 667-hole spinneret at a discharge rate of 740 g/min and traveling 7 mm in air, the temperature
It was coagulated in a coagulation bath of an NMP aqueous solution with a concentration of 30% by weight at 50°C and pulled up at a speed of 38.5 m/min. Subsequently, the obtained coagulated thread was washed in a water bath at 50°C and stretched stepwise to 1.3 times, passed through a squeezing roller to remove water adhering to the surface, and a concentration of 2 weight with the composition shown in Table 2 was obtained. % in an aqueous dispersion bath of inorganic fine powder.
The yarn was immersed for seconds and passed through a squeezing roller to obtain a water-washed yarn (pre-drawn yarn) to which inorganic fine powder was attached.

[Table] Next, the washed yarn was placed on a drying roller at 120°C.
After winding the yarn 30 times and drying it, the dried yarn was loosened between a pair of gear rolls having triangular teeth. Each gear roll has a diameter of 84 mm and has 40 triangular teeth on its circumference, and the tips of the triangular teeth are rounded with a radius of curvature of 1 mm. The gear rolls are engaged with each other to a certain depth, and the degree of kneading changes depending on the depth of this engagement. The depth of engagement was 0.6 mm.
This massaging makes it easier to open the fibers during stretching at 400°C or higher and reduces fusion. After kneading and loosening, the dried yarn is heated at a temperature of 360℃.
Stretch it twice on a 2m long hot plate and finally heat it to 500℃.
℃ and stretched 4 times on a 3 m long hot plate. (Thus, the total stretching ratio is 10.4 times.) The thus obtained drawn yarn was continuously treated to remove inorganic fine powder by the method described below without being wound up. First, a water shower is sprayed onto the running drawn yarn. The water flow rate of the shower is 10l/min. The drawn yarn is sufficiently wetted by this water shower. Then, it is introduced into an air nozzle with an inner diameter of 2.5 mm and a length of 10 mm. The inner wall of the air nozzle has an air injection hole with a diameter of 1.7 mm, and through this hole, an air flow of 200 l/min collides with the running wet drawn fibers, blowing away inorganic fine powder adhering to the fibers together with water. After this, once again,
Repeat the water shower and air jet processes under the same conditions. A finishing oil of 1.8% was applied to the drawn yarn thus treated, and the yarn was wound at a speed of 400 m/min. The fineness of the obtained fiber was 1030 denier. For comparison, a drawn yarn without inorganic fine powder removal treatment was similarly oiled and wound. A high-density fabric weaving test was conducted using these drawn yarns. The weave density was 32 threads per inch. The results of the above tests are shown in Table 3 below.

[Table] As can be seen from Table 3, when the inorganic fine powder removal treatment was performed, the yarn quality was excellent and the weavability was also good. On the other hand, if inorganic fine powder was not used, the textile machine often stopped due to poor fiber convergence, and scum was also observed on the guides. Example 3 Polyethylene having a weight average molecular weight of 1 million was dissolved in decalin to make a 2% solution, which was spun from a 200-hole spinneret at a spinning temperature of 135°C, and then introduced into cold water at 5°C to solidify. Decalin was extracted from this coagulated fiber in a methanol bath. This fiber was immersed in a dispersion bath of inorganic fine powder (talc concentration 1.5%) having the composition shown in Table 4 according to the method of the present invention, and then passed through a squeezing roll.
It was dried on a drying roll at 50°C. This dry fiber
After stretching 40 times on a hot plate at 140°C, the fine talc powder was removed by passing it through a 1 m long water bath, using the same air nozzle as in Example 1, and finishing oil was applied at 1.0% to give a height of 1000 denier/200 filament. A strong polyethylene fiber was obtained. On the other hand, as a comparative experiment, the film was dried without applying fine talc powder, stretched under the same conditions as above, and then 1.0% oil was applied and wound.

[Table] The results of these experiments are summarized in Table 5 below.

[Table] As shown in Table 5 above, the method of the present invention dramatically reduces fusion and significantly improves the cohesiveness of the final fiber. Example 4 1350 parts p-acetoxybenzoic acid, terephthalic acid
311 parts of isophthalic acid, 104 parts of isophthalic acid, and 675 parts of 4,4'-diacetoxydiphenyl were charged into a reactor equipped with a stirrer and a distiller, and the acetic acid produced by the reaction under a nitrogen gas stream was distilled off. 3 hours at 330℃, then
The reaction was carried out at 330°C for 5 hours. After cooling, the produced polymer was crushed and crushed under reduced pressure of about 0.2 mmHg absolute pressure.
Solid phase polymerization was carried out for 3 hours while increasing the temperature to ~280°C, and then for 3 hours at 280°C. The wholly aromatic polyester thus obtained was extruded at 360° C. through a circular nozzle with 12 holes and a diameter of 0.2 mm, immersed in the same inorganic powder dispersion bath as in Example 2, dried, and wound up. The strength of this fiber is 6.5g/de,
The Young's modulus was 480 g/de and the elongation was 1.3%. Next, the fiber was heated in a nitrogen stream from 200°C to 330°C over 2 hours, and then heat-treated at 330°C for 5 hours.
The fibers were passed through a 1 m long water bath and then passed through the same air nozzle as in Example 2 before being coated with finishing oil and wound up. This fiber had a strength of 24.7 g/de, Young's modulus of 890 g/de, and elongation of 2.7%, and was flexible with no fusion between single fibers. On the other hand, for comparison, when yarn was spun in the same manner, but no inorganic powder was applied and no water bath treatment or air nozzle treatment was performed, a yarn with a strength of 24.7 g/de was obtained, but the single fibers were fused during heat treatment. It became a hard fiber.

Claims (1)

[Scope of Claims] 1. A method for producing high-strength fibers by coating fibers made of a thermoplastic synthetic polymer with inert inorganic fine powder and stretching or heat-treating the fibers at high temperatures, After the heat treatment, the fibers are subjected to water application treatment, introduced into an air nozzle, and subjected to an air jet treatment by injecting air from the wall surface of the tube to remove the inorganic fine powder adhering to the fibers. An excellent method for producing thermoplastic synthetic fibers characterized by removing the fibers. 2. A patent claim in which the thermoplastic synthetic polymer is a rigid polymer consisting of aromatic residues or heterocyclic residues, and in which fusion occurs between single fibers when the fibers are stretched or heat treated at high temperatures. The manufacturing method according to scope 1. 3 The thermoplastic synthetic polymer is such that 80 mol% or more of the repeating units of the polymer are the following repeating units: (-NH-Ar ₁ -NHCO-Ar ₂ -CO)- [where Ar ₁ and Ar ₂ are selected from the following indicates at least one aromatic residue. [Formula] [Formula] [Formula] However, the hydrogen atom of the aromatic residue may be substituted with a halogen atom and/or a lower alkyl group. ] The manufacturing method according to claim 1 or 2, wherein the aromatic polyamide is composed of: 4 More than 80 mol% of Ar ₁ and Ar ₂ are aromatic residues listed below.
(A) or (B), [However, the hydrogen atoms of these aromatic residues may be substituted with halogen atoms and/or lower alkyl groups. ] The manufacturing method according to claim 3, wherein the mol% of said (B) is 10 to 40%. 5 80 mol% or more of Ar ₁ and Ar ₂ is the following aromatic residue (A) or (B′), [However, the hydrogen atoms of these aromatic residues may be substituted with halogen atoms and/or lower alkyl groups. ] The manufacturing method according to claim 3, wherein the mol% of said (B') is 10 to 40%. 6. The thermoplastic synthetic polymer according to claim 1 or 2, wherein the thermoplastic synthetic polymer is a homopolymer of wholly aromatic residue polyester, wholly aromatic polyether, or wholly aromatic polyketone, or a copolymer or mixture thereof. Production method. 7 Claim 1 in which the thermoplastic synthetic polymer is a polyolefin with a weight average molecular weight of 100,000 or more
Manufacturing method described in section. 8. The manufacturing method according to claim 1, wherein the inorganic fine powder is a fine powder with an average particle size of 20 microns or less. 9. Claim 1 or 8, wherein the inorganic fine powder is a fine powder of at least one inorganic substance selected from the group consisting of aluminum silicate, magnesium silicate, graphite, talc, silica, and mica.
Manufacturing method described in section. 10. The manufacturing method according to claim 1 or 9, wherein the water application treatment is carried out by immersing and running the fibers in water. 11. The manufacturing method according to claim 1 or 9, wherein the water application treatment is performed by jetting water onto the running fibers.