KR101307936B1 - Aromatic polyamide monofilament having high-strength and process for preparing the same - Google Patents

Abstract

PURPOSE: A high strength aromatic polyamide mono filament and a manufacturing method thereof are provided to produce an aramid fiber composed of a mono filament with a high intensity which is substantially improved compare to the intensity of a previous aramid mono filament. CONSTITUTION: An aromatic polyamide mono filament is extended by less than 1.0 percent when the aromatic polyamide monofilament is placed in an initial stress of 6.0g/d and is extended by less or the same amount as 1.7 percent in a stress section ranged from 6.0g/d to 18.0g/d. The aromatic polyamide mono filament has a force-deformation curve which is extended more or the same amount as 1.1 percent until a filament is cut from a tensile stress state of 18.0g/d.

Description

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

By adjusting the force-strain curve of the aromatic polyamide monofilament, the present invention (a) the aromatic polyamide monofilament stretches less than 1.0% when subjected to an initial stress of 6.0 g / d; (b) elongation to less than 1.7% in the stress range from 6.0 g / d to 18.0 g / d; (c) relates to an aromatic polyamide monofilament 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 monofilament of the present invention are It is possible to produce high strength aramid fibers which is significantly improved compared to the strength of the produced aramid monofilament.

The wholly aromatic polyamide filaments are prepared by polymerizing an aromatic diamine and an aromatic diacid chloride in a polymerization solvent containing N-methyl-2-pyrrolidone as disclosed in U.S. Patent No. 3,869,492 and U.S. Patent No. 3,869,430, A method for producing an aromatic polyamide polymer, comprising the steps of: preparing an aromatic polyamide polymer; dissolving the polymer in a concentrated sulfuric acid solvent to prepare a spinning solution; spinning the spinning solution through a spinneret and spinning the spinning solution through a non- To form a filament, and a step 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 Unexamined Patent Publication No. 2008-22832 discloses that the conventional method has a problem that since the radiation is slowly cooled in the coagulating solution at room temperature, the filament finally formed has a thin skin layer (S) And a method of using a coagulation bath at -5 DEG C to provide a thick skin layer is proposed.

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 elongates less than 1.0% when (a) the aromatic polyamide monofilament is subjected to an initial stress of 6.0 g / d; (b) elongation to less than 1.7% in the stress range from 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, (a) the aromatic polyamide monofilament stretches 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.

According to another suitable embodiment of the present invention, the fineness of the aromatic polyamide monofilament is 2.0 denier or less.

In addition, the aromatic polyamide monofilament is characterized in that it has a strength of 30g / d or more.

In addition, the aromatic polyamide monofilament has an elongation at break of 3.95% or more and a modulus of 700 g / d or more.

The aromatic polyamide monofilaments of the present invention can produce aramid fibers composed of high strength monofilaments that are significantly improved over the strength of aramid monofilaments produced in the prior art. Due to these properties, it can be usefully used as anti-ballistic and protective materials, optical fiber reinforcement materials, various composite materials, rubber reinforcement materials and other industrial uses.

1 is a schematic diagram of an aromatic polyamide wet-wet spinning method.

The present invention (a) the aromatic polyamide monofilament stretches 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 aromatic polyamide monofilament has a fineness of 2.0 denier or less, strength of 30 g / d or more, elongation at break of 3.95% or more, and modulus of 700 g / d or more.

According to the present invention, in the case of high-strength aromatic polyamide yarns used for industrial use, in particular for tire cords, the force-strain curve of aromatic polyamide monofilaments as a method for minimizing the initial deformation to the initial impact caused by external forces This is regulated. The force-strain curve of the aromatic polyamide monofilament measured at room temperature shows that the monofilament elongates less than 1.0% when (a) the aromatic polyamide monofilament is 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) 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, it is preferable that the aromatic polyamide monofilament of the present invention be less than 1.0% when subjected to an initial stress of 6.0 g / d, if the aromatic polyamide monofilament is at least 1.0% at an initial stress of 6.0 g / d. When stretched, the shape stability after manufacture of the tire is low, and the resistance due to external deformation is lowered, which causes 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, a high strength aromatic polyamide monofilament is required to realize this. The aromatic polyamide monofilaments of the present invention preferably have a force-strain curve that extends at least 1.1% until the yarn is cut from a tensile strength of 18.0 g / d, which is 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.

Hereinafter, the configuration and operation of the embodiment according to the present invention will be described in detail.

According to the present invention, an aromatic polyamide polymer can be prepared by polymerizing an aromatic diamine and a dicarboxylic acid halide.

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

In addition, the aromatic dicarboxylic acid halides include terephthaloyl chloride (TPC), 4,4'-benzoyl chloride, 2-chloroterephthaloyl chloride, 2,5-dichloroterephthaloyl chloride, 2-methylterephthaloyl 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, an aromatic polyamide polymer having an intrinsic viscosity (IV) of 5.5 to 7.0, which is prepared by low-temperature polycondensation of p-phenylenediamine and terephthaloyl chloride, is used. The solubility is lowered.

Wet, dry, dry and wet spinning can be used, but it is possible to manufacture aromatic polyamide fibers with a uniform structure in dry-wet spinning, so that it is possible to manufacture high strength fibers.

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 spacing of the spinneret is preferably 1.1 to 1.4 mm, more preferably 1.3 to 1.4 mm. At this time, if the hole spacing is less than 1.1mm, the close contact between the filament occurs during high-speed spinning, the physical properties are lowered.

In the present invention, the spinning speed is preferably 300 to 1,200 m / min. If the spinning speed is less than 300 m / min, the productivity deteriorates. If the spinning speed exceeds 1,200 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, when the aromatic polyamide solution is spun, even if the same discharge amount is maintained, a fiber having a smaller diameter can be obtained in the coagulating solution by keeping 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 to the impact that the industrial high strength yarn is initially generated by external forces. The aromatic polyamide monofilament measured at room temperature of the present invention is elongated less than 1.0% when subjected to an initial stress of 6.0 g / d, elongated less than 1.7% 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 0.8, 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. Process factors affecting the crystal orientation include the concentration of aromatic polyamide to the solvent, the length / diameter ratio of the orifice, the cooling conditions and the solidification bath temperature, the stretching temperature, the stretching ratio, and the like. 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 1.5 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 the 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, a force-strain curve of the preferred 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 properties of Examples and Comparative Examples were 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 the sample length was measured at 20 mm and tensile strength 20 mm / min. The monofilament properties were measured with the remaining 22 average values except one of the maximum and the minimum of 24 measured values. 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  One

A polymer of intrinsic viscosity (IV) 6.3, prepared by homopolymerization of p-phenylenediamine and terephthaloyl chloride in an equimolar amount, was dissolved in 100.1% concentrated sulfuric acid in a twin screw extruder at a solids content of 19.5% .

The spinning dope prepared as described above was spun through a 1000 mm spinneret having a hole diameter of 64 microns, and passed through an air layer of 6 mm, and then wound through a coagulation bath and a feed roller of 5% sulfuric acid concentration of 7%. It was. At this time, Table 1 shows the tension between the rollers 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 in the horizontal direction.

Comparative example  1 to 3

It carried out in the same manner as in Example 1, was prepared by changing the tension between the rollers.

division Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 1 section tension
(g / d) 0.6 0.5 0.3 0.8 0.6 0.6 2 section tension
(g / d) 0.7 0.5 0.4 0.7 0.7 0.7 3-section tension
(g / d) 0.8 0.5 0.5 0.6 0.8 0.8 Contact area
(Mm2) 7500 7500 7500 7500 5600 3700 Fineness
(denier) 1.32 1.61 1.45 1.45 1.47 1.47 Strength (g / d) 31.51 23.84 27 24.22 27.89 26.65 Shinto (%) 4.0 3.8 3.9 3.55 3.8 3.8 Modulus
(g / d) 715 516 550 650 709 702 % Elongation up to 6.0 g / d 0.9 1.2 1.05 1.1 0.9 0.9 Elongation at stress range from 6.0 g / d to 18.0 g / d (%) 1.45 1.91 1.75 1.8 1.57 1.64 Elongation (%) from tensile strength of 18.0 g / d to cutting 1.45 0.9 1.09 1.02 1.32 1.21

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 (5)

(a) the aromatic polyamide monofilament elongates less than 1.0% when subjected to an initial stress of 6.0 g / d;
(b) elongation to less than 1.7% in the stress range from 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 of claim 1,
The fineness of the aromatic polyamide monofilament is 2.0 denier or less aromatic polyamide monofilament.
The method of claim 1,
The aromatic polyamide monofilament has an intensity of 30 g / d or more aromatic polyamide monofilament.
The method according to claim 1,
The aromatic polyamide monofilament is an aromatic polyamide monofilament, characterized in that the elongation at break of 3.95% or more.
The method according to claim 1,
The aromatic polyamide monofilament is an aromatic polyamide monofilament, characterized in that the modulus is 700g / d or more.

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