Aramid spun yarn manufacturing method

Abstract

The present invention relates to para-aramid staple fibers having improved cut resistance due to the use of high elongation yarn of 4% or more, and a method for producing aramid spun yarn using the same.

Description

[Technical Field]

[0001] <Cross-reference to related applications> This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0119851, filed September 8, 2021, and Korean Patent Application No. 10-2022-0106994, filed August 25, 2022, and all contents disclosed in the documents of said Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a para-aramid staple fiber, an aramid spun yarn, and a method for producing the same, which can improve cut resistance. [Background technology]

[0003] Aromatic polyamide fibers commonly known as aramid fibers generally include para-aramid fibers, which have a structure in which benzene rings are linearly linked via amide groups (-CONH-), and meta-aramid fibers, which do not. Para-aramid fibers have excellent properties such as high strength, high elasticity, and low shrinkage, and are so strong that a thin thread with a diameter of about 5 mm can lift a 2-ton car.

[0004] Aramid fibers have excellent heat resistance, flame retardancy, chemical resistance, and strength, and have a strong molecular structure and a dense structure with high crystallinity, so they have been widely used in firefighting suits, protective clothing, safety gloves, etc.

[0005] However, as the demand for para-aramid gloves with improved cut resistance has increased recently depending on the application, it is important to develop spun yarn for gloves with improved cut resistance.

[0006] Therefore, para-aramid staple fibers having a filament elongation of about 3.5% are generally used to produce aramid spun yarns, which are then used to produce protective gloves. The aramid staple fibers are produced by crimping a tow made by combining aramid filaments produced using multiple guide rollers, and then cutting the tow to a predetermined length.

[0007] However, the para-aramid staple fiber has low elongation, so there is still a limit to how much cut resistance can be improved. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a para-aramid staple fiber that not only maintains high spinnability and excellent strength by applying a filament having high elongation, but also has an increased breaking load, thereby significantly improving cut resistance compared to conventional fibers.

[0009] The present invention also provides an aramid spun yarn having excellent cut resistance and mechanical properties, and a method for producing the same, which is produced by using the high elongation yarn and staple fibers. [Means for solving the problem]

[0010] Provided herein is a para-aramid staple fiber having an elongation of 4.1% to 6% and a strength of 15 to 24 g / d.

[0011] The para-aramid staple fibers may include monofilaments having an elongation of 4.1% to 5.5% and a strength of 20 to 30 g / d.

[0012] The para-aramid staple fibers may have a fineness of 1.0 to 3.0 de and a fiber length of 38 to 114 mm.

[0013] The present specification also provides a method for producing an aramid spun yarn, which includes applying the para-aramid staple fiber to a ring spinning process to produce an aramid spun yarn having a single yarn of Ne16 to Ne30 and a twist number (TM) in the range of 2.0 to 4.0.

[0014] The aramid spun yarn may have a twist number of Ne20 single yarn in the range of 2.0 to 4.0.

[0015] The aramid spun yarn can satisfy the requirements of elongation of 3.5% or more and strength of 7 g / d or more.

[0016] The ring spinning process may include subjecting para-aramid staple fibers to carding, drawing, roving and spinning processes.

[0017] The aramid spun yarn thus produced can satisfy a cut resistance index of 6 to 15 as measured based on the EN388 Blade Cut Resistance version 2016 method.

[0018] The present specification also provides an aramid spun yarn containing para-aramid staple fibers having an elongation of 4.1% to 6% and a tenacity of 15 to 24 g / d.

[0019] Furthermore, the aramid spun yarn satisfies the elongation of 3.5% or more and the tenacity of 7 g / d or more. In addition, the aramid spun yarn satisfies the cut resistance index of 6 to 15 measured based on the method of EN388 Blade Cut Resistance version 2016.

[0020] The aramid spun yarn produced can also be used in protective gloves or protective clothing. [Effects of the Invention]

[0021] According to the present invention, by applying filaments (raw yarns) having a high elongation of 4% or more, which is higher than conventional ones, it is possible to provide para-aramid staple fibers having cut resistance improved by 15 to 60% or more compared to conventional ones, and a method for producing spun aramid yarns which can produce spun yarns having mechanical properties and cut resistance at the same level or higher than conventional ones.

[0022] In addition, the para-aramid staple fiber and spun yarn of the present invention have relatively high strength and excellent spinnability compared to existing fibers, and can satisfy the basic mechanical properties required by the industry. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, the method for producing para-aramid staple fiber and aramid spun yarn according to the embodiment of the present invention will be described in more detail.

[0024] According to one embodiment of the invention, there is provided a para-aramid staple fiber having an elongation of 4.1% to 6% and a strength of 15 to 24 g / d.

[0025] In response to the recent increasing demand for para-aramid gloves with improved cut resistance depending on the application, the present inventors have been conducting research to develop a glove spun yarn with improved cut resistance compared to existing para-aramid spun yarns. As a result, they have confirmed through experiments that when a para-aramid staple fiber is used with a raw yarn having a higher elongation than existing ones, by at least 4%, when a spun yarn with the same standard twist is provided, cut resistance can be significantly improved compared to existing ones, and have completed the invention.

[0026] Furthermore, the high elongation yarn and staple fiber of the present invention can exhibit uniform fineness and spinnability at levels equal to or higher than those of existing yarns.

[0027] <Para-aramid staple fiber> Hereinafter, filaments or staple fibers made of para-aramid having high elongation will be described.

[0028] The para-aramid spun yarn can be applied to protective gloves. For example, the para-aramid spun yarn used for the 7 gauge (7G) protective gloves generally has a count of 20 (Ne20) or more, and gloves are provided by knitting two of these yarns together to form a ply yarn.

[0029] However, the elongation of the para-aramid spun yarn is low, at 4% or less, and there is a limit to significantly improving the cut resistance.

[0030] Therefore, the present specification provides staple fibers using para-aramid filaments with an elongation of at least 4%, or 4.1% to 6%, or 4.5% to 6%, which can exhibit excellent cut resistance improvement effects compared to conventional spun yarns, even when the twist number of the spun yarn is the same or lower. In other words, increasing the elongation of the para-aramid filaments and staple fibers increases flexibility, making it possible to produce an aramid spun yarn that has improved cut resistance while maintaining excellent mechanical properties, even when the twist number is the same or lower than conventional spun yarns. In other words, even when the elongation of the para-aramid spun yarn is 4% or less, adjusting the elongation of the para-aramid filaments to a specific range of 4% or more can improve the cut resistance index compared to conventional spun yarns. Specifically, when the elongation of the para-aramid filaments is 4.5 to 6%, the toughness increases, further improving the cut resistance of the spun yarn. The para-aramid staple fibers may have an elongation of 4.1% to 6% or a tenacity of 15 to 24 g / d.

[0031] The para-aramid staple fiber may contain monofilaments having an elongation of 4.1% to 5.5% and a strength of 20 to 30 g / d. More specifically, when the para-aramid staple fiber contains monofilaments having an elongation of 4.2% to 5.5%, or 4.5 to 5.5%, or 4.6 to 6%, and a strength of 20 to 30 g / d, a spun yarn having better cut resistance can be provided.

[0032] The para-aramid staple fiber may include a filament bundle having an elongation of 3.5% to 5.5% and a tenacity of 15 to 24 g / d. When the elongation of the filament bundle is 4.2 to 5.5%, 4.5 to 5.5%, or 4.6 to 6%, the filament bundle can provide better cut resistance to the spun yarn.

[0033] If the elongation of the para-aramid staple fiber is 4.1% or less, the cut resistance cannot be improved, and if it exceeds 6%, problems occur during the filament production process, making it impossible to produce filaments.

[0034] More preferably, when a spun yarn is produced from the staple fiber using the high elongation yarn and then used to make gloves, the cut resistance (based on the EN388 Blade Cut Resistance index) can be improved by about 15 to 60% as the cutting load increases.

[0035] Meanwhile, the para-aramid staple fiber having high elongation can be produced as an aramid staple fiber having an elongation of 4.1% to 6% and a strength of 15 to 24 g / d, which includes a filament bundle having an elongation of 3.5 to 5.5% and a strength of 20 to 30 g / d, using the monofilament, by synthesizing a para-aramid polymer using polyparaphenylene terephthalamide (PPTA) particles having an intrinsic viscosity of 5.0 to 10.0 dl / g, and subjecting the obtained para-aramid polymer to a uniform extrusion step of a spinning dope.

[0036] Specifically, the para-aramid staple fiber having an elongation of 4% or more can be produced by adjusting the elongation by the following method.

[0037] 1) A mixed solution is prepared by dissolving an aromatic diamine in an organic solvent, 2) an aromatic diamine halide is initially added to the mixed solution and reacted to prepare a prepolymer, 3) an aromatic diamine halide is secondarily added to the mixed solution and reacted to prepare a para-aramid polymer, 4) only para-aramid polymers having a diameter of 50 to 5,000 μm are selected from the prepared para-aramid polymers and dissolved in sulfuric acid to prepare a spinning dope, and 5) the prepared spinning dope is spun into a fiber, which is coagulated, washed with water, and dried to prepare an aramid filament.

[0038] 6) After combining the aramid filaments to produce a bundled tow, the tow is washed with a spinning oil (for example, under conditions of 50 to 90°C and 1500 to 5500 liters / hr), squeezed at the end of the washing (for example, squeeze roll pressure: 1.0 to 5.0 bar), applied with a primary spinning oil (for example, applied with a spinning oil having a concentration of 1 to 8% by weight at a temperature of 30 to 70°C), squeezed at the end of the primary spinning oil (for example, squeeze roll pressure: 1.0 to 5.0 bar), annealed with steam, and then crimped (for example, under a roll pressure of 1.5 to 3.5 bar and a stuffer box pressure of 0.3 to 1.8 bar). After crimping under pressure of a crimping box, the fibers are given a crimp of 5 to 10 crimps per inch, and then a secondary spinning oil is applied (for example, a secondary spinning oil with a concentration of 1 to 8% by weight at a rate of 150 to 300 g / min), followed by a drying process (for example, at 75 to 105°C and 2 to 6 mpm), a cutting process (for example, at a draw ratio of 3 to 15% and 50 to 100 mpm), and a baler (for example, at 30 to 60 Hz) to produce para-aramid staple fibers.

[0039] The para-aramid polymer for producing the para-aramid staple fiber can be produced by using aromatic diamine and aromatic diacid or its derivative as monomers in a polar solvent with an inorganic salt as a catalyst at a temperature of -10 to 50°C and by vigorous stirring.

[0040] The aromatic diamine may be para-phenylenediamine, 4,4'-diaminobiphenyl, 2,6-naphthalenediamine, 1,5-naphthalenediamine, 4,4'-diaminobenzanilide, or the like.

[0041] The aromatic diacid or its derivative includes aromatic diacid halides, and examples of the aromatic diacid halides that can be used include terephthaloyl dichloride, 4,4'-benzoyl dichloride, 2,6-naphthalenedicarboxylic acid dichloride, and 1,5-naphthalenedicarboxylic acid dichloride.

[0042] The organic solvent may be N-methyl-2-pyrrolidone (NMP), N,N'-dimethylacetamide (DMAc), hexamethylphosphoramide (HMPA), N,N,N',N'-tetramethylurea (TMU), N,N-dimethylformamide (DMF), or a mixture thereof.

[0043] The inorganic salts that can be used include CaCl2, LiCl, NaCl, KCl, LiBr, and KBr.

[0044] The aromatic diamine may be para-phenylenediamine, 4,4'-diaminobiphenyl, 2,6-naphthalenediamine, 1,5-naphthalenediamine, 4,4'-diaminobenzanilide, or the like.

[0045] The aromatic diacid halide may be terephthaloyl dichloride, 4,4'-benzoyl dichloride, 2,6-naphthalenedicarboxylic acid dichloride, 1,5-naphthalenedicarboxylic acid dichloride, or the like.

[0046] In this case, the prepolymer may be subjected to aging treatment for 0 to 48 hours, or the content of the inorganic salt in the polymerization solvent may be adjusted to 40 to 60% by weight based on the content of the monomer.

[0047] Next, the produced para-aramid polymer is dissolved in sulfuric acid to produce a spinning dope, and the spinning dope is spun into fibers through a spinneret, and the spun fibers are coagulated by passing through a coagulation bath and a coagulation tube, and the spun fibers are washed and dried by passing through a water washing roller and a drying roller in sequence, and then wound around a take-up roller to produce para-aramid fibers.

[0048] As used herein, "staple fiber" has a length cut from a monofilament.

[0049] Therefore, the para-aramid staple fiber produced by the above method can have a fineness of 0.5 to 3.0 de and a fiber length of 20 to 130 mm.

[0050] The fineness is measured using a FAVIMAT device, and the fiber length is measured by visual measurement using a ruler.

[0051] <Method for producing aramid spun yarn and aramid spun yarn> Meanwhile, according to another embodiment of the present invention, there is provided a method for producing an aramid spun yarn, which includes a step of applying the para-aramid staple fiber to a ring spinning process to produce an aramid spun yarn having a single yarn of Ne16 to Ne30 and a twist number (TM) in the range of 2.0 to 4.0.

[0052] In this specification, "Ne" refers to the English cotton count (Ne) used to indicate the count (thickness) of spun yarn. The yarn count refers to the length ('s) per unit weight when a yarn having a length of 840 yards (yds) is made from 1 pound (lb) of cotton.

[0053] According to this specification, an aramid spun yarn having excellent cut resistance can be provided by using filaments or staples made of para-aramid having high elongation, which will be explained in more detail below.

[0054] As described above, the para-aramid staple fiber is characterized by having an elongation of 4.1% to 6%, which is higher than existing fibers, and a strength of 15 to 24 g / d.

[0055] Such para-aramid staple fibers can be applied to relatively high carding speeds, for example, even when carded at a speed of 30 kg / hr or more, they can have high uniformity and excellent mechanical properties, thereby achieving high spinnability and excellent spinning yield.

[0056] The present invention can significantly improve the cut resistance of aramid spun yarns when the same twist number as that of conventional spun yarns is applied. That is, when producing spun yarns, the cut resistance of the aramid spun yarns can be improved by using filaments or staple fibers made of para-aramid having high elongation and setting the twist number within a certain range.

[0057] Specifically, the aramid spun yarn is produced by applying para-aramid staple fibers having the above-described characteristics to a ring spinning process to produce a single yarn having a count of Ne16 to Ne30, and doubling the single yarn by adjusting the twist number (TM) of the single yarn to a range of 2.0 to 4.0. Therefore, when the twist number within the above range is applied within the single yarn count, the aramid spun yarn can have improved cut resistance compared to conventional aramid spun yarns. Furthermore, even if the twist number within the single yarn count is the same as conventional aramid spun yarns, the cut resistance of the doubling aramid spun yarn can be further improved by using para-aramid staple fibers having specific physical properties.

[0058] More specifically, the aramid spun yarn may have a single yarn twist number (TM) of 2.0 to 4.0, 2.0 to 3.5, 2.0 to 3.0, or 2.0 to 2.5 for a count Ne20. The aramid spun yarn may also satisfy the following requirements for the spun yarn elongation of 3.5% or more and the tenacity of 7 g / d or more for a doubling. When the count of the aramid spun yarn is Ne20, if the single yarn twist number (TM) of the Ne20 is 2.0 or less, the twist number is too small, causing the single fiber to unravel, making it difficult to manufacture the spun yarn. If the single yarn twist number (TM) of the Ne20 is 4.0 or more, the excessive twist makes the spun yarn stiff, resulting in a poor wearing comfort and causing the glove to be twisted.

[0059] In this case, gloves made using the spun yarn can achieve 15 to 60% improved cut resistance compared to existing gloves.

[0060] According to a preferred embodiment, the produced aramid spun yarn can satisfy a cut resistance index of 12 to 18, measured based on the method of EN388 Blade Cut Resistance version 2016. More specifically, the cut resistance index may be 12 to 17 or 12.3 to 16.7.

[0061] The ring spinning process can be performed by a method well known in the art. For example, the ring spinning process can provide a spun yarn having the above single yarn range and twist number by subjecting para-aramid staple fibers to carding, drawing, and spinning processes. A blowing process can be further included before the carding process. After the drawing process, a roving process can be further included to further increase the sliver and provide minimal twist.

[0062] More specifically, the step of carding the para-aramid staple fiber at a speed of 30 kg / hr or more may be performed by applying a card density of the internal fixed carding bar of the carding machine of 200 to 700 PPSI at the upper end of the doffer and 10 to 400 PPSI at the upper end of the licker-in, and a cylinder speed of 200 to 500 rpm.

[0063] The aramid spun yarn thus produced can satisfy the requirements that the elongation of the single yarn and doubled yarn of Ne16 to Ne30 is 3.5% or more and the strength is 7 g / d or more.

[0064] The method for producing the aramid spun yarn may include the steps of thinning a sliver or roving, which is a continuous fiber bundle, and bundling the fiber bundle to impart twist.

[0065] In addition, the method for producing aramid spun yarn may further include drawing and spinning the sub-slivers obtained after the carding step.

[0066] The aramid filaments are combined together using a plurality of guide rollers to produce a bundled tow, and the tow is then washed with spinning oil, the washed ends are squeezed, a primary spinning oil is applied, the ends are squeezed with the primary spinning oil, annealed with steam, and then crimped, and then 5 to 10 crimps per inch are imparted, and the tow is subjected to a secondary spinning oil application, a drying process, a cutting process, and a baler to produce aramid staple fibers.

[0067] The produced aramid staple fibers can be subjected to a carding process to produce a plurality of sub-slivers, that is, a sub-sliver, which is a fiber aggregate, can be obtained by arranging the aramid single fibers in parallel through the carding process.

[0068] Then, after combining the sub-slivers, a minimum twist is imparted to the slivers in a drawing process to maintain strength, and then the slivers are drawn and twisted at the same time in a spinning process to produce aramid spun yarn.

[0069] Therefore, according to another embodiment of the invention, there is provided an aramid spun yarn comprising para-aramid staple fibers having an elongation of 4.1% to 6% and a tenacity of 15 to 24 g / d.

[0070] Therefore, as mentioned above, the aramid spun yarn according to this specification may have a single yarn count of Ne16 to Ne30 and a twist number (TM) of 2.0 to 4.0.

[0071] The aramid spun yarn satisfies the elongation of the spun yarn of the doubling yarn of 3.5% or more and the tenacity of 7 g / d or more. Additionally, the aramid spun yarn satisfies the cut resistance index of 6 to 15 measured based on the method of EN388 Blade Cut Resistance version 2016.

[0072] At this time, the strength and elongation of the para-aramid monofilament, para-aramid staple fiber, and para-aramid spun yarn according to the present specification can be evaluated based on the test method of KS K ISO 2062. In addition, the setting conditions of gauge length and test speed can be measured according to the contents of the manual.

[0073] The cut resistance index of the spun yarn can be evaluated based on the method of EN388 Blade Cut Resistance version 2016. Therefore, the aramid spun yarn has excellent cut resistance and can be applied to products including protective gloves or protective clothing, more preferably protective gloves. The protective gloves include 7-gauge protective gloves, and the protective clothing includes firefighting clothing, welding clothing, and boat racing clothing. The product may be a knitted or woven fabric including the aramid spun yarn. Most preferably, the product may be a 7-gauge protective glove including a knitted fabric of the aramid spun yarn. The knitted or woven fabric is woven as is well known in the art.

[0074] As described above, the present invention can provide the effect of improving cut resistance even when high elongation yarn / staple is used and the number of twists (TM) is reduced, and when applied to protective gloves (e.g., 7-gauge gloves) or protective clothing, it can reduce the risk of injury to workers and improve stability.

[0075] The present invention will be described in more detail in the following examples, but the following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention.

[0076] [Examples and Comparative Examples: Production of Aramid Staple Fiber and Aramid Spun Yarn] As shown in Tables 1 and 2, para-aramid staple fibers and aramid spun yarns were produced by changing the properties of the raw yarn and the spinning conditions.

[0077] Example 1 Under a nitrogen atmosphere, a mixed solvent of NMP as an organic solvent and CaCl2 as an inorganic salt in a weight ratio of 92:8 was placed in a reactor, and p-phenylene diamine (PPD) was added so that the concentration of PPD in the slurry was 5 wt% to prepare a slurry.

[0078] Next, terephthaloyl chloride (TPC) equivalent to 40 mol % of the number of moles of PPD was added to the slurry, and then reacted to produce a para-aramid prepolymer.

[0079] Thereafter, TPC equivalent to 60 mol % of the number of moles of PPD was secondarily added to the prepared para-aramid prepolymer, and then reacted to prepare a para-aramid polymer.

[0080] The para-aramid polymer obtained above was dissolved in 99.8 wt% sulfuric acid at a concentration of 19 wt% based on the total weight of the spinning dope to prepare a spinning dope. The dope was spun into fibers through a spinneret, and the spun fibers were coagulated by sequentially passing through a coagulation bath and a coagulation tube. The fibers were washed and dried by sequentially passing through a water-washing roller and a drying roller, and then wound around a take-up roller to produce para-aramid filaments with a single fiber fineness of 1.5 denier and an elongation of 4.9%. The elongation of the para-aramid filament bundle was 4.5%.

[0081] Next, the para-aramid filaments were combined using a plurality of guide rollers to produce a bundled tow, and the tow was then washed with spinning oil, squeezed at the end of the washed tow, applied with a primary spinning oil, squeezed at the end of the primary spinning oil, annealed with steam, and then crimped. Thereafter, the tow was given 5 to 10 crimps per inch, applied with a secondary spinning oil, dried, and cut to a length of 20 to 130 mm, and then passed through a baler to produce para-aramid staple fibers.

[0082] Then, the para-aramid staple fiber was subjected to a ring spinning process to produce aramid spun yarn.

[0083] Specifically, para-aramid staple fiber was produced into multiple sub-slivers by a high-speed carding process of 30 kg / hr or more under the following conditions: the cloth density of the internal fixed carding bar in the carding machine was 200-700 PPSI at the top of the doffer, 10-400 PPSI at the top of the licker-in, and a cylinder speed of 200-500 rpm. The individual sub-slivers were then combined and twisted to the levels shown in Table 1 in a drawing process to maintain strength. The slivers were then drawn and twisted simultaneously in a roving and fine spinning process to produce a single yarn with a count of 20 (Ne20) and a twist multiplier (TM) of 2.3 TM. Two single yarns were combined to produce a two-ply aramid spun yarn (final product count of spun yarn: 20 / 2).

[0084] <Example 2> As shown in Table 1, para-aramid staple fibers and aramid spun yarns were produced in the same manner as in Example 1, except that the twist number of a single yarn having a count of 20 (Ne20) was set to TM2.9 when producing the spun yarn.

[0085] Example 3 As shown in Table 1, para-aramid staple fibers and aramid spun yarns were produced in the same manner as in Example 1, except that the twist number of a single yarn having a count of 20 (Ne20) was set to TM3.5 when producing the spun yarn.

[0086] Example 4 As shown in Table 1, para-aramid staple fibers and aramid spun yarns were produced in the same manner as in Example 1, except that the para-aramid monofilaments and para-aramid staple fibers used had an elongation of 4.1%.

[0087] <Comparative Example 1> As shown in Table 2, an aramid spun yarn was produced in the same manner as in Example 1, except that a commonly used para-aramid staple fiber according to the conditions in Table 1, having an elongation of 4.0% and a tenacity of 20 g / d, was used.

[0088] <Comparative Example 2> As shown in Table 2, an aramid spun yarn was produced in the same manner as in Example 2, except that a commonly used para-aramid staple fiber according to the conditions in Table 1, having an elongation of 4.0% and a tenacity of 20 g / d, was used.

[0089] <Comparative Example 3> As shown in Table 2, an aramid spun yarn was produced in the same manner as in Example 3, except that a commonly used para-aramid staple fiber according to the conditions in Table 1, having an elongation of 4.0% and a tenacity of 20 g / d, was used.

[0090] [Experimental Example] The properties of the para-aramid fibers and spun yarns of the above Examples and Comparative Examples were evaluated by the following methods, and the results are shown in Tables 1 and 2.

[0091] (1) Measurement of strength and elongation of monofilaments, staple fibers, and spun yarns The spun yarn was evaluated using a USTER device according to the KS K ISO 2062 test method, and the gauge length and test speed were measured according to the manual.

[0092] (2) Cut resistance measurement The cut resistance of the Examples and Comparative Examples was evaluated based on the method of EN388 Blade Cut Resistance version 2016. The cut resistance was evaluated by producing knitted gloves using the para-aramid spun yarns of the Examples and Comparative Examples by knitting them on a glove knitting machine of a size used for 7 gauge protective gloves (produced using 100% para-aramid spun yarn, 20 count, two-ply, five strands).

[0093] [Table 1]

[0094] [Table 2]

[0095] As shown in Tables 1 and 2, the aramid spun yarns of Examples 1 to 4, using para-aramid staple fibers having elongations in the range of 4.1% to 6% and tenacities of 15 to 24 g / d, exhibited significantly improved cut resistance compared to Comparative Examples 1 to 3 when the twist number of the spun yarn was equivalent to that of conventional spun yarns (20 count (Ne20) with a single yarn twist number TM of 2.3 to 3.5). In particular, the present invention exhibited significantly improved cut resistance compared to Comparative Examples 1 to 3 when the TM was reduced to about 2.3 by using high-elongation raw yarns and staple fibers. In other words, it was confirmed that Examples 1 to 3 could further improve the cut resistance of the spun yarn by using para-aramid staple fibers containing a filament bundle having a tenacity of 22.7 g / d and a high elongation of 4.5%. In particular, Example 1 exhibited the highest cut resistance even at a low twist number, making it possible to provide protective gloves that are excellent in both quality and stability. Moreover, Example 4, which used a raw yarn with an elongation of 4.1%, had improved cut resistance compared to Comparative Example 1, which used a raw yarn with an elongation of 4.0%.

[0096] In contrast, Comparative Examples 1 to 3 use existing staple fibers with an elongation of 4.0%, which is a generally applied level, and the elongation of the filament bundle contained in the para-aramid staple fiber is 3.5% and the strength is 21.5 g / d. Therefore, when the same twist number conditions as in Examples 1 to 3 (twist number of single yarn with count 20 (Ne20); TM 2.3 to 3.5) are applied, it can be seen that the cut resistance is relatively lower than that of the Examples.

Claims

1. Para-aramid staple fibers are subjected to a ring spinning process including a carding process at a carding speed of 30 kg / hr or more, producing a single yarn having a Ne of 16 to 30 and a twist multiplier (TM) of 2.0 to 4.0; The para-aramid staple fiber has an elongation of 4.1% to 6% and a strength of 15 to 24 g / d.

2. The method for producing an aramid spun yarn according to claim 1, wherein the aramid spun yarn has a twist coefficient of Ne20 single yarn in the range of 2.0 to 4.

0.

3. 2. The method for producing an aramid spun yarn according to claim 1, wherein the aramid spun yarn satisfies an elongation of 3.5% or more and a strength of 7 g / d or more.

4. The ring spinning process includes a step of subjecting para-aramid staple fibers to a carding process at a speed of 30 kg / hr or more, a drawing process, a roving process, and a spinning process; The carding step of carding the para-aramid staple fibers at a speed of 30 kg / hr or more includes:

2. The method for producing aramid spun yarn according to claim 1, wherein the carding machine has an internal fixed carding bar with a carding density of 200 to 700 PPSI at the doffer upper end and 10 to 400 PPSI at the licker-in upper end, and a cylinder speed of 200 to 500 rpm.

5. The method for producing an aramid spun yarn according to claim 1, wherein the cut resistance index measured based on the method of EN388 Blade Cut Resistance version 2016 satisfies 12 to 18.

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