KR101360985B1 - Aromatic polyamide monofilament having high-elongation and process for preparing the same - Google Patents

Abstract

The present invention relates to a method for preparing an aromatic polyamide filament and an aramid fiber consisting of a high-elongation monofilament, wherein the high-elongation monofilament is prepared by, when a spinning solution passing through a nozzle passes through a coagulation bath and then is wound on a winding roller, adjusting the tension applied to a portion of a yarn, which is within a distance of 7 m from a point at which the yarn traveling in a vertical direction from the nozzle turns to a horizontal direction. Provided is an aromatic polyamide monofilament having a stress-strain curve in which the aromatic polyamide monofilament is: elongated by less than 1.0% when subjected to an initial stress of 6.0 g/d; elongated by 1.7% or less during a stress section from 6.0-18.0 g/d; and elongated by at least 1.1% from a tensile strength of 18.0 g/d until the yarn is cut.

Description

Aromatic polyamide monofilament having high-elongation and process for preparing the same

The present invention is directed to adjusting the force-strain curve of aromatic polyamide monofilaments to (a) stretching aromatic polyamide monofilaments to less than 1.0% when subjected to an initial stress of 6.0 g / d; (b) stretches no more than 1.7% in a stress interval of 6.0 g / d to 18.0 g / d; (c) aromatic polyamide monofilaments having a force-strain curve elongating at least 1.1% until the yarn is cut from a tensile strength of 18.0 g / d, wherein the aramid fibers using the monofilaments of the present invention are It is possible to produce high-strength aramid fibers which is significantly improved compared to the elongation of the produced aramid monofilament.

The wholly aromatic polyamide filaments are prepared by polymerizing aromatic diamine and aromatic dieside chloride in a polymerization solvent containing N-methyl-2-pyrrolidone, as disclosed in US Pat. Nos. 3,869,492 and 3,869,430. Preparing an aromatic polyamide polymer; dissolving the polymer in a concentrated sulfuric acid solvent to produce a spinning stock solution; spinning the spinning stock solution from a spinneret and spinning the spinning material into a coagulant bath through a non-coagulating fluid layer. It is manufactured through a process of forming a filament by passing through, and a process of washing, drying and heat treating the filament.

A conventional technique related to the solidifying method is a method of producing a para-aramid filament of high strength by extruding a para-aramid solution through a micro capillary and drying the filament produced under a high tension in Korean Patent Publication No. 2000-52793 I am suggesting. Japanese Patent Laid-Open No. 11-189916 also proposes a method of producing high strength, high-resilience aramid fibers by controlling the amount of coagulated liquid relative to the passing filament mass. U.S. Patent No. 4,965,033 and U.S. Patent No. 11-189916, which are patents relating to coagulating mass / velocity, describe the ratio of the coagulating liquid mass to the filament mass, the ratio of the filament speed to the coagulating liquid velocity in the spinning tube, And the like. U.S. Patent No. 5,330,698 suggests a method of obtaining a high elongation by keeping the coagulating liquid temperature at 40 to 80 ° C. Korean Patent Laid-Open Publication No. 2008-22832 discloses that since the radiation is gradually cooled in the coagulating solution at room temperature, the final filament has a problem that the skin layer (S) is thinly formed to a level of 1 μm or less and its strength is low , And a method of using a coagulation bath at -5 DEG C to provide a thick skin layer.

Japanese Patent Laid-Open Nos. 02-242914, 02-242913, 5,173,236 and 5,853,640 disclose that a certain tension is applied to the fiber during washing and drying.

However, research has yet to be conducted on the process factors that affect the properties of the filament and fatigue resistance due to the tension between the coagulation bath and the feed roller.

It is an object of the present invention that the aromatic polyamide monofilament (a) stretches below 1.0% when subjected to an initial stress of 6.0 g / d; (b) stretches no more than 1.7% in a stress interval of 6.0 g / d to 18.0 g / d; (c) to provide an aromatic polyamide monofilament having a force-strain curve that elongates at least 1.1% or more until the yarn is cut from a tensile strength of 18.0 g / d.

According to a preferred embodiment of the present invention, the method comprises the steps of preparing a spinning dope by dissolving a polymer of intrinsic viscosity (I.V.) 6.3 prepared by low-temperature polycondensation of aromatic diamine and aromatic dicarboxylic acid halide in sulfuric acid; After spinning the spinning dope through a spinning nozzle, passing through an air layer and passing through a coagulation bath and a feed roller; It includes, and the tension between the roller within a distance of 7m from the point where the yarn traveling in the vertical direction from the spinning nozzle in the horizontal direction (0.5) in the section (a) 0.5 to 0.6 g / d, (b) in the 0.4 to The 0.5 g / d and (c) section provides a method for producing an aromatic polyamide monofilament, characterized in that adjusted to 0.3 to 0.4 g / d.

According to another suitable embodiment of the present invention, it is prepared by the same method as described above, wherein (a) the aromatic polyamide monofilament is elongated by less than 1.0% when subjected to an initial stress of 6.0 g / d; (b) stretches no more than 1.7% in a stress interval of 6.0 g / d to 18.0 g / d; (c) providing an aromatic polyamide monofilament having a force-strain curve that elongates at least 1.1% or more from the tensile strength of 18.0 g / d until the yarn is cut.

In addition, the elongation at break of the aromatic polyamide monofilament is characterized by 4.75% or more.

The aromatic polyamide monofilament of the present invention can produce aramid fibers composed of high-strength monofilaments expressing a similar level of strength and elongation at least about 1.0% compared to aramid monofilaments produced in the prior art. Due to such physical properties, it can be usefully used for bulletproof and shielding materials, optical fiber reinforcing materials, various composites, rubber reinforcing materials and other industrial applications.

1 is a schematic view of the aromatic polyamide wet-wetting spinning method of the present invention.

The present invention relates to a process for preparing a radiation dope by dissolving a polymer of an intrinsic viscosity (IV) 6.3 prepared by low temperature polycondensation of an aromatic diamine and an aromatic dicarboxylic acid halide in sulfuric acid; After spinning the spinning dope through a spinning nozzle, passing through an air layer and passing through a coagulation bath and a feed roller; It includes, and the tension between the roller within a distance of 7m from the point where the yarn traveling in the vertical direction from the spinning nozzle in the horizontal direction (0.5) in the section (a) 0.5 to 0.6 g / d, (b) in the 0.4 to The 0.5 g / d and (c) section provides a method for producing an aromatic polyamide monofilament, characterized in that adjusted to 0.3 to 0.4 g / d.

In addition, the present invention is prepared by the above production method, (a) when the aromatic polyamide monofilament is subjected to an initial stress of 6.0 g / d elongation is less than 1.0%; (b) stretches no more than 1.7% in a stress interval of 6.0 g / d to 18.0 g / d; (c) providing an aromatic polyamide monofilament having a force-strain curve that elongates at least 1.1% or more from the tensile strength of 18.0 g / d until the yarn is cut.

The elongation at break of the aromatic polyamide monofilament is characterized by 4.75% or more.

According to the present invention, the force-strain curve of the aromatic polyamide monofilament is adjusted in such a way as to minimize the initial deformation to the impact initially generated by external forces, especially for high strength aromatic polyamide yarns used for tire cords. do. The force-strain curve of the aromatic polyamide monofilament measured at room temperature is less than 1.0% when the monofilament is subjected to (a) an initial stress of 6.0 g / d; (b) stretches no more than 1.7% in a stress interval of 6.0 g / d to 18.0 g / d; (c) It is desirable to have a force-strain curve that extends at least 1.1% or more from the tensile strength of 18.0 g / d until the yarn is cut.

High initial modulus of aromatic polyamide monofilaments is required to maintain high morphological stability in the vulcanization process when manufacturing tires, especially for industrial use, especially for tire cords. For this reason, when the aromatic polyamide monofilament of the present invention is subjected to an initial stress of 6.0 g / d, it is preferable to elongate less than 1.0%, if the aromatic polyamide monofilament is 1.0% at an initial stress of 6.0 g / d. The abnormal elongation results in low form stability after tire production and low resistance due to external deformation, resulting in rapid deformation of the tire, resulting in deterioration of ride comfort and steering performance.

In addition, it is preferable that the aromatic polyamide monofilament used in the production of such a material is elongated by 1.7% or less in a stress section from 6.0 g / d to 18.0 g / d. If the elongation exceeds 1.7%, the morphological stability is deteriorated and the resistance due to external deformation is lowered, which may cause deformation of the tire.

In addition, it is desirable to minimize the weight of the tire in order to design an energy-saving vehicle, which requires a high strength aromatic polyamide monofilament. The aromatic polyamide monofilaments of the present invention preferably have a force-strain curve that extends at least 1.1% or more from the tensile strength of 18.0 g / d until the yarn is cut, which when cut at a tensile strength of 18.0 g / d If the elongation is less than 1.1%, it is difficult to reduce the weight of the cord paper per tire due to the lack of the maximum tensile load absorption of the manufactured heat treatment cord.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the structure and operation of the present invention will be described in detail.

According to the present invention, in order to increase the solubility of the polyamide polymer, calcium chloride is added to N-methyl-2-pyrrolidone (NMP) to make a polymerization solvent, and aromatic diamine and aromatic dicarboxylic acid halide is added to the polymerization solvent. A para polyamide polymer having improved physical properties such as intrinsic viscosity can be prepared by adding a polymer in a molar ratio of 1: 1.

Aromatic diamines that can be used in the present invention are para-phenylenediamine, 4,4'-diaminobiphenyl, 2-methyl-paraphenylenediamine, 2-chloro-paraphenylenediamine, 2,6-naphthalenediamine, 1,5-naphthalenediamine, 4,4'- diaminobenzanilide, etc. are mentioned, It is preferable to use para-phenylenediamine.

Aromatic dicarboxylic acid halides that can be used in the present invention include terephthaloyl chloride (TPC), 4,4'-benzoyl chloride, 2-chloroterephthaloyl chloride, 2,5-dichloroterephthaloyl chloride, 2-methyl Terephthaloyl chloride, 2,6-naphthalenecarboxylic acid chloride, 1,5-naphthalenecarboxylic acid chloride, and the like, but it is preferable to use terephthaloyl chloride.

In the present invention, para-phenylenediamine is added to the mixed solvent of NMP and calcium chloride, and then terephthaloyl chloride is added to polymerize to obtain a para-polyamide polymerization solution. Intrinsic viscosity of the polyamide in the present invention is preferably 5.5 to 7.0. If it is less than 5.5, the strength of the fiber decreases. If it exceeds 7.0, the solubility decreases.

Spinning may be wet, dry, or wet or the like, but in particular, it is possible to manufacture a high-strength fiber because it is possible to produce an aromatic polyamide fiber having a uniform structure in a wet and dry spinning method.

The dry wet spinning process according to the present invention will be described in detail. When the aromatic polyamide solution is quantitatively supplied from the gear pump, the spinning stock solution discharged through the spinning nozzle passes through the air layer in the vertical direction and reaches the interface of the coagulating solution . The shape of the spinning nozzle used is usually circular. Considering the tire cord and industrial use in terms of application, considering the nozzle spacing for uniform cooling of the solution, the number of nozzles is preferably 200 to 1,500.

In the present invention, the hole interval of the spinneret is preferably 1.1 to 1.4 mm, more preferably 1.3 to 1.4 mm. If the hole spacing is less than 1.1 mm, the filaments are closely adhered to each other during high-speed spinning to deteriorate the physical properties. If the hole spacing is more than 1.4 mm, the diameter of the spinneret increases.

In the present invention, the spinning speed is preferably 1000 to 1500 m / min. If the spinning speed is less than 1000 m / min, the productivity deteriorates. If the spinning speed exceeds 1500 m / min, the properties of the filament deteriorate sharply.

When the fiber stock solution passing through the spinning nozzle coagulates in the coagulating solution, the larger the diameter of the fluid becomes, the greater the difference in the coagulation speed between the surface and the inside becomes, so that it becomes difficult to obtain a dense and uniform tissue fiber. Therefore, even when the aromatic polyamide solution is spun, even the same discharge amount can be obtained into the coagulating solution with a thinner diameter by maintaining an appropriate air layer. It is difficult to increase the spinning speed because the too short air layer distance increases the micropore generation rate due to the rapid surface layer coagulation and desolvation process, and it is difficult to increase the spinning speed. On the other hand, the too long air layer distance is affected by the adhesion of the filament, It is difficult to maintain process safety by receiving large amounts. The air layer is preferably 3 to 20 mm.

According to the present invention, the force-strain curve of the aromatic polyamide monofilament can be adjusted to minimize the initial deformation in the impact initially generated by external high strength yarns by external forces. The aromatic polyamide monofilament measured at room temperature of the present invention is elongated by less than 1.0% when subjected to an initial stress of 6.0 g / d, elongated by 1.7% or less in a stress section from 6.0 g / d to 18.0 g / d, It is desirable to have a force-strain curve that stretches at least 1.1% or more from the tensile strength of 18.0 g / d until the yarn is cut.

A factor influencing the force-strain curve of the present invention is the crystal orientation of the monofilament. The crystal orientation degree is preferably 0.80 or more, and more preferably 0.90 or more. If the crystal orientation is less than 0.80, it is impossible to have a force-strain curve that extends by 1.1% or more until the yarn is cut from a tensile strength of 18.0 g / d due to insufficient molecular chain orientation due to the strong decrease in monofilament. The process parameters affecting the degree of crystal orientation include the concentration of the aromatic polyamide in the solvent, the length / diameter ratio of the orifice, the cooling conditions and the coagulating bath temperature, the drawing temperature, and the draw ratio. By appropriately adjusting these various process factors, the crystal orientation of the monofilament can be adjusted to 0.80 or more.

Another factor influencing the force-strain curve of the present invention is the density of the monofilament. The density of the monofilament is preferably 1.35 to 1.50 g / cm 3, more preferably 1.40 to 1.47 g / cm 3. If there are many voids in the monofilament, or excessively developed into the skin core structure, the density of the monofilament is less than 1.35 g / cm 3 and thus lacks compactness and strength and thus does not have the force-strain curve of the present invention. In particular, the process factors affecting the density of the monofilament include the concentration of the aromatic polyamide with respect to the solvent, the diameter / length ratio of the nozzle, the air layer length, the cooling conditions, the coagulation bath composition ratio, and the coagulation bath temperature. By appropriately adjusting these various process factors, the density of the monofilament can be adjusted to the above preferred range.

A factor that greatly affects the force-strain curve of the present invention is the contact area of yarns discharged from the nozzles and contacting the rollers within a distance of 7 m from the point where the yarns passing through the coagulating liquid in the vertical direction are converted to the horizontal direction.

By adjusting the contact area, the force-strain curve of the monofilament of the present invention is obtained. The multifilament introduced into the coagulation bath has a contact area of a constant width with the roller installed inside the coagulation bath. It is preferable that the area which a multifilament yarn contacts a roller surface is 3,000-8,000 mm <2>. If the area where the multifilament yarn contacts the surface of the roller is smaller than 3,000 mm 2, the fraction of the fine pores generated during the desolvation of the solvent present in the multifilament is excessively increased and the density of the monofilament is too low, making the calculation difficult. On the contrary, if the area of the multifilament yarns in contact with the roller surface is larger than 8,000 mm2, problems such as pin yarns caused by the contact between the rollers and the filaments occur, resulting in poor process stability. Therefore, the monofilament must be properly adjusted to obtain the maximum stretchability by having an appropriate contact area.

The factor given to the width of the multifilament yarns in contact with the roller surface can be adjusted by applying a constant shape guide to keep the spread of the yarns on the rollers constant. For example, in the form of a narrow V-shaped guide, the width of the yarn decreases, resulting in a decrease in contact area, and in the case of a flat guide, the width of the guide increases, resulting in an increase in contact area. Another factor that controls the contact area is the stretching tension of the roller, the stretching temperature and the amount of emulsion.

The physical property evaluation in an Example and a comparison was measured or evaluated as follows.

1) Strength (g / d), elongation (%) and modulus (g / d) of monofilament

After extracting 24 monofilaments from a yarn (multifilament) that was left for 24 hours at a temperature of 25 ° C. and a relative humidity of 55 RH%, the dendritic load was defined by the denier in Vibrojet using Vibrojet 2000's monofilament tensile tester. About monodenier x 50 (mg)) was added and measured at 20 mm / min in sample length and 20 mm / min in tensile strength. The monofilament properties were measured with the remaining 22 average values except one of the maximum and the minimum of 24 measured values. The initial modulus represents the slope of the graph before the yield point.

2) Contact area of yarn on roller surface

Measure the width of the first turn point by photo measurement, measure the width of the last turn point in the same way, and find the average of the two values. Therefore, it is calculated as the contact area = the average square width × the number of turns × the high roller radius × 2π (high roller pair configuration).

Example 1

Spin-doped polymers of intrinsic viscosity (IV) 6.3 prepared by equimolar-temperature low-temperature condensation of para-phenylenediamine and terephthaloyl chloride were dissolved at 85 ° C. in a twin screw extruder at a solid content of 19.5% in 100.1% concentrated sulfuric acid. Was prepared.

The spinning dope prepared as described above was spun through a 1000 mm spinneret having a hole diameter of 64 microns, and then passed through a 6 mm air layer. . At this time, the tension between the roller and the physical properties of the filament within a distance of 7m from the point where the yarn traveling in the vertical direction from the nozzle is converted to the horizontal direction is shown in Table 1 below.

Comparative Example 1

It carried out in the same manner as in Example 1, was prepared by changing the tension between the rollers. Table 1 shows the tension between the rollers and the physical properties of the filaments within a distance of 7 m from the point where the yarn traveling in the vertical direction from the nozzle is converted in the horizontal direction.

Example 1 Comparative Example 1 (a) Section tension (g / d) 0.5 0.5 (b) Section tension (g / d) 0.4 0.5 (c) Section tension (g / d) 0.3 0.5 Contact area (mm2) 7500 7500 Denier 1.68 1.61 Strength (g / d) 24.11 38.38 Shinto (%) 4.80 3.80 Modulus (g / d) 414 516 % Elongation up to 6.0 g / d 0.9 1.2 Elongation at stress range from 6.0 g / d to 18.0 g / d (%) 1.45 1.91 Elongation from tensile strength of 18.0 g / d to cutting (%) 1.45 0.9

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. It will be understood by those skilled in the art that the foregoing embodiments are susceptible to modifications and variations that do not depart from the spirit and scope of the invention.

Claims (3)

In the method for producing an aromatic polyamide monofilament,
Dissolving a polymer of intrinsic viscosity (IV) 6.3 prepared by low-temperature polycondensation of aromatic diamine and aromatic dicarboxylic acid halide in sulfuric acid to prepare a spinning dope;
After spinning the spinning dope through a spinning nozzle, passing through an air layer and passing through a coagulation bath and a feed roller; Lt; / RTI &gt;
The method of producing an aromatic polyamide monofilament, characterized in that for adjusting the tension between the rollers within a distance of 7m from the point where the yarn traveling in the vertical direction from the spinning nozzle in the horizontal direction as follows.
(a) section: 0.5 to 0.6 g / d
(b) section: 0.4 to 0.5 g / d
(c) section: 0.3 to 0.4 g / d
Prepared by the method of claim 1,
(a) the aromatic polyamide monofilament elongates less than 1.0% when subjected to an initial stress of 6.0 g / d;
(b) stretches no more than 1.7% in a stress interval of 6.0 g / d to 18.0 g / d;
(c) aromatic polyamide monofilaments having a force-strain curve elongating at least 1.1% until the yarn is cut from a tensile strength of 18.0 g / d.
The method according to claim 2,
The aromatic polyamide monofilament is an aromatic polyamide monofilament, characterized in that the elongation at break of 4.75% or more.

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