Lyocell fiber, preparation process thereof and tire cord comprising the same

Abstract

The present invention relates to a lyocell fiber comprising a cellulose-based polymer and 0.01 to 0.05 wt% of an alkyl gallate having a particle size of 200 μm to 700 μm, a method for manufacturing the same, and a tire cord comprising the same. According to the present invention, the degree of polymerization of the yarn is increased, thereby improving the strength and fatigue resistance of the tire cord.

Description

Technology Field

[0001] The present invention relates to lyocell fibers, a method for manufacturing the same, and tire cords containing the same. More specifically, the invention relates to lyocell fibers that can be preferably applied to tire cords, etc., which can improve the performance of tire reinforcing materials by increasing the degree of polymerization of lyocell fibers, which are eco-friendly materials usable as tire reinforcing materials, and a method for manufacturing the same and tire cords containing the same. Background Technology

[0003] Lyocell fibers have superior fiber characteristics such as tensile strength and tactile feel compared to conventional regenerated fibers, and do not generate pollutants during the production process. Furthermore, the amine oxide-based solvents used in the process are recyclable and biodegradable upon disposal, making them an eco-friendly fiber used in various fields.

[0004] Generally, industrial lyocell fibers are manufactured from cellulose, similar to industrial rayon fibers, but they are characterized by higher strength and modulus of elasticity and lower elongation compared to rayon fibers. Therefore, lyocell fibers are suitable as rubber reinforcement materials for applications such as tire cords, hoses, and belts, where high strength and modulus of elasticity are required.

[0005] In order to use lyocell fibers for tire cords, they must have high strength and modulus of elasticity, and for this, the degree of polymerization (DP) of the pulp or yarn must be high.

[0006] Methods used to improve the degree of polymerization of lyocell yarn include applying pulp with a high degree of polymerization, increasing the cellulose dissolution concentration, maintaining a low process temperature and residence time, or adding antioxidants. However, applying pulp with a high degree of polymerization requires lowering the cellulose dissolution concentration, and increasing the cellulose dissolution concentration requires a high process temperature and residence time, so there are limitations in manufacturing lyocell yarn with a high degree of polymerization above a certain level.

[0007] As another method to improve the degree of polymerization of lyocell yarn, Korean Patent Publication No. 2000-0068155 discloses a method for producing lyocell-type cellulose fibers by treating a cellulose spinning solution with an aqueous tertiary amine oxide. Prior art literature

[0008] U.S. Patent No. 5,584,919 U.S. Patent No. 5,094,690 U.S. Patent No. 5,421,525 The problem to be solved

[0009] The present invention is intended to solve the aforementioned problems, and one objective of the present invention is to provide a lyocell fiber and a method for manufacturing the same that can improve the strength and fatigue resistance of a lyocell tire cord by optimizing the size of the alkyl gallate powder to improve the degree of polymerization of the lyocell yarn.

[0010] Another objective of the present invention is to improve tire performance by increasing the degree of polymerization of lyocell yarn. means of solving the problem

[0012] One aspect of the present invention for solving the above-mentioned problem is,

[0013] The present invention relates to a lyocell fiber comprising a cellulose-based polymer and 0.01 to 0.05 wt% of an alkyl gallate having a particle size of 200 μm to 700 μm.

[0014] The above lyocell fiber includes soft wood pulp having a degree of polymerization of 850 or more and an α-cellulose content of 95% or more.

[0015] The above alkyl gallate may be selected from the group consisting of ethyl gallate, propyl gallate, isopropyl gallate, butyl gallate, pentyl gallate, hexyl gallate, heptyl gallate, octyl gallate, nonyl gallate, decyl gallate, and dodecyl gallate.

[0016] Another aspect of the present invention for solving the above-mentioned problem is,

[0017] The present invention relates to a tire cord comprising the aforementioned lyocell fiber, having a strength utilization rate of 80% or more and a fatigue resistance of 70% or more.

[0018] Another aspect of the present invention for solving the above-mentioned problem is,

[0019] The present invention relates to a method for manufacturing lyocell fibers from a lyocell spinning solution in aqueous tertiary amine oxide, characterized by adding 0.01 to 0.05 wt% of an alkyl gallate having a particle size of 200 μm to 700 μm to the lyocell spinning solution.

[0020] The above method comprises the step of preparing a spinning dope by dissolving a cellulose-based polymer and an alkyl gallate having a particle size of 200 μm to 700 μm in an aqueous solution of tertiary amine oxide at a content of 0.01 to 0.05 wt% relative to the total weight of the spinning dope;

[0021] A step of extruding and solidifying the above-mentioned spinning dope through a spinning nozzle; and

[0022] The above solidified product includes the step of washing and drying.

[0023] In the method of the present invention, an air gap may be provided between the outlet of the spinning nozzle and the surface of the coagulation bath. Effects of the invention

[0025] According to the present invention, in order to improve the strength, which is an important physical property of a tire cord, the degree of polymerization of the yarn is increased by adjusting the amount of alkyl gallate acting as an antioxidant and the powder size of the alkyl gallate, without changing other process factors such as applying pulp having a high degree of polymerization, increasing the dissolution concentration of the pulp, or lowering the process temperature, thereby providing a lyocell fiber exhibiting excellent overall physical properties in terms of strength, strength, and elongation, and a method for manufacturing the same.

[0026] According to the present invention, the strength and fatigue resistance of the dip cord can be improved, thereby improving the durability performance and lifespan of the tire. Brief explanation of the drawing

[0028] FIG. 1 is a schematic diagram of a lyocell fiber manufacturing apparatus for manufacturing lyocell fibers according to the present invention. Specific details for implementing the invention

[0029] Hereinafter, the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the invention.

[0030] Prior to that, unless explicitly stated otherwise in this specification, technical terms are used merely to refer to specific embodiments and are not intended to limit the invention.

[0031] The singular forms used in this specification include plural forms unless the phrases clearly indicate otherwise.

[0032] As used herein, the meaning of "include" is to limit specific characteristics, regions, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other specific characteristics, regions, integers, steps, actions, elements, and / or components.

[0033] In this specification, the terms 'at least one' or "one or more types" should be understood to include all combinations that can be presented from one or more related items.

[0034] In the present invention, a filament bundle comprising a plurality of filament fibers is called a 'multifilament,' a raw cord produced by twisting the multifilament upward and downward is called a 'ply yarn,' and a dip cord treated with a tire cord adhesive on the ply yarn is called a 'tire cord' or 'cord.'

[0035] One aspect of the present invention relates to a lyocell fiber comprising a cellulose-based polymer and 0.01 to 0.05 wt% of an alkyl gallate having a particle size of 200 μm to 700 μm.

[0036] In the present invention, a small amount of alkyl gallate is added to ensure the safety of the cellulose solution. A physical force, such as shear force, is required to dissolve cellulose in tertiary amine oxide, and in the present invention, cellulose can be dissolved through a twin-screw extruder.

[0037] The above alkyl gallate refers to an alkyl ester compound of gallic acid. Gallic acid is 3,4,5-trihydroxybenzoic acid. In alkyl gallate, the term "alkyl" refers to a fully saturated branched or unbranched (or straight-chain or linear) hydrocarbon. The above alkyl may be a C2 to C18, C2 to C16, C2 to C14, C2 to C12, C2 to C10, C2 to C8, C2 to C6, C2 to C4, or C2 to C3 alkyl group.

[0038] In the present invention, the alkyl gallate may be a C2 to C18 alkyl gallate. Examples of the alkyl gallate include ethyl gallate, propyl gallate, isopropyl gallate, butyl gallate, pentyl gallate, hexyl gallate, heptyl gallate, octyl gallate, nonyl gallate, decyl gallate, and dodecyl gallate. Most preferably, 3,4,5-trihydroxybenzoic acid propyl ester, i.e., propyl gallate, may be used.

[0039] Alkyl gallate is a powdered reagent dispersed in a tertiary amine oxide solvent and introduced into the lyocell manufacturing process. At this time, the degree of polymerization of the yarn can be determined by the amount of alkyl gallate added and the size of the alkyl gallate powder.

[0040] In the present invention, the amount of alkyl gallate added may be 0.01 wt% to 0.05 wt% relative to the total weight of the spinning dope. If the amount of alkyl gallate added is less than 0.01 wt% relative to the total weight of the spinning dope, the function as an antioxidant is insufficient, and conversely, if the amount of alkyl gallate added exceeds 0.05 wt% relative to the total weight of the spinning dope, the degree of polymerization of the lyocell yarn does not increase further and converges, which may increase manufacturing costs and cause problems such as process filter blocking.

[0041] Meanwhile, since alkyl gallate is introduced into the process in a dispersed state rather than a dissolved state, the powder size of the alkyl gallate is also an important process factor. Although a smaller powder size of the alkyl gallate is advantageous for the degree of polymerization of the yarn, a smaller particle size of the alkyl gallate powder is advantageous for the expression of effects, if the particle size is less than 200 μm, it becomes difficult to manufacture, which may lead to problems such as increased manufacturing costs and sales prices. Conversely, if the size of the alkyl gallate powder exceeds 700 μm, it may cause a decrease in processability and defects due to increased filter and nozzle pressure, which may result in a deterioration of the physical properties of the lyocell fiber.

[0042] In the present invention, the degree of polymerization (DP) of the cellulose may be 800 to 1,600. In this way, by using cellulose molecules with a high degree of polymerization to form a highly oriented structure and highly crystallized lyocell fibers, the various physical properties of the lyocell fibers, such as strength and initial modulus, can be further improved.

[0043] The lyocell fiber of the present invention may include soft wood pulp having a degree of polymerization of 850 or higher and an α-cellulose content of 95 weight% or higher. Additionally, the pulp included in the spinning dope may contain α-cellulose in a high content, for example, 95 weight% or higher. In the present invention, the pulp may contain α-cellulose in an amount of 96 weight% or higher, preferably 97 weight% or higher, more preferably 98 weight% or higher, and even more preferably 99 weight% or higher, thereby making it possible to provide a lyocell fiber exhibiting excellent overall physical properties along with a low degree of fibrillation.

[0044] The degree of polymerization of the lyocell fiber of the present invention is 850 or higher and 1200 or lower, preferably 900 to 1150, and more preferably 950 to 1100.

[0045] In the present invention, a tertiary amine oxide, known as a solvent with excellent solubility for cellulose and non-toxicity, is used as a solvent.

[0046] In the present invention, the aqueous tertiary amine oxide may be an amine oxide of the following chemical formula 1.

[0047]

[0048] In the above formula, R1 and R2 are alkyl groups having 1 to 4 carbon atoms, R3 is hydrogen or a hydroxyl group, and m and n are integers satisfying the conditions 1≤m≤8 and 0≤n≤4, respectively.

[0049] A preferred example of the tertiary amine oxide of Chemical Formula 1 above is the compound of Chemical Formula 2 below.

[0050]

[0051] The spinning dope for spinning lyocell fibers may contain 80 to 95 weight percent of an aqueous solution of N-methylmorpholine-N-oxide as a solvent component. If the content of the aqueous solution of N-methylmorpholine-N-oxide is less than 80 weight percent or more than 95 weight percent, it cannot dissolve cellulose.

[0052] Another aspect of the present invention relates to a tire cord comprising the lyocell fibers described above, having a strength utilization rate of 80% or more and a fatigue resistance of 70% or more. When the tire cord of the present invention is subjected to a fatigue test by the method below, the fatigue resistance may be 70% or more, preferably 80% or more, and more preferably 85 to 95%.

[0053] In the present invention, the fatigue resistance of the cord is calculated according to Formula 1 below by measuring the fatigue strength after a fatigue test using a belt fatigue tester, which is commonly used for fatigue testing of tire cords. The fatigue test conditions are as follows: a load of 40 kg is applied to the specimen in the belt fatigue tester, attached to a 0.5-inch spindle roller, and repeated 15,000 times at 180 rpm at 40°C; after the fatigue test, the rubber and cord are separated to measure the fatigue strength. The fatigue strength is measured using a conventional tensile strength tester after drying at 107°C for 2 hours.

[0054] [Formula 1]

[0055] Fatigue Resistance (%) = (Cord Fatigue Resistance / Cord Strength Before Fatigue Test) × 100

[0056] The tire cord of the present invention has excellent shape stability and durability, so it can be applied for purposes such as the body ply or cap ply of pneumatic tires. In addition, a tire incorporating the tire cord of the present invention exhibits minimal shape deformation and can demonstrate stable high-speed driving performance.

[0057] Normally, tire temperatures rise due to friction while driving. Particularly during high-speed driving, high temperature and high pressure conditions are maintained for extended periods, exposing tire cords to repetitive fatigue conditions. In such cases, if the tire cords have low fatigue resistance, their physical properties deteriorate rapidly due to repeated tension and contraction. This can significantly reduce the tire's driving performance and, in severe cases, poses a risk of the cords rupturing while driving.

[0058] In addition, the inherent strength of the tire cord is just as important as the fatigue resistance mentioned above, and in order to exhibit physical properties suitable for a tire cord, the tire cord of the present invention may have a breaking strength of 4 to 8 g / d. Even if the fatigue resistance of the cord is excellent, if the inherent strength is low, it is difficult to exhibit physical properties suitable for a tire cord, and if the elongation is low, the durability against fatigue is poor.

[0059] Next, the method for manufacturing the lyocell fiber of the present invention will be described.

[0060] A method of one embodiment of the present invention is a method for producing lyocell fibers from a lyocell spinning dope in an aqueous tertiary amine oxide, characterized by adding 0.01 to 0.05 wt% of an alkyl gallate having a particle size of 200 μm to 700 μm to the lyocell spinning dope.

[0061] The above method comprises the step of preparing a spinning dope by dissolving a cellulose-based polymer and an alkyl gallate having a particle size of 200 μm to 700 μm in an aqueous solution of tertiary amine oxide at a content of 0.01 to 0.05 wt% relative to the total weight of the spinning dope;

[0062] A step of extruding and solidifying the above-mentioned spinning dope through a spinning nozzle; and

[0063] The above solidified product includes the step of washing and drying.

[0064] To explain each step in more detail, first, a cellulose solution is prepared by mixing, swelling, and dissolving cellulose powder. Here, the cellulose powder is not particularly limited as long as it is a cellulose material, but examples of suitable raw cellulose include, but are not limited to, fibrous cellulose, hemicellulose, wood pulp, paper, linter, cotton, etc.

[0065] FIG. 1 is a simplified schematic diagram illustrating an example of a spinning apparatus for manufacturing lyocell fibers according to an embodiment of the present invention. Referring to FIG. 1, the lyocell fiber manufacturing apparatus of the present invention comprises a spinning nozzle (1) for spinning a spinning dope into the form of a fiber, and a coagulation bath (2) for coagulating an uncoagulated filament fiber discharged from the spinning nozzle.

[0066] In the present invention, the cellulose powder has an α-cellulose content of 95 weight% or more, and more preferably, an α-cellulose content of 95 to 98%. Raw material α-cellulose is a factor that significantly affects the physical properties of cellulose fibers, and the higher the α-cellulose content, the more favorable the expression of physical properties of the cellulose fibers becomes.

[0067] In order to dissolve cellulose in NMMO, a physical force such as shear force is required, and in the present invention, cellulose can be dissolved through a twin-screw extruder. The above-mentioned cellulose solution is extruded through a spinning nozzle having an orifice diameter of 100 to 200 μm and an orifice length of 200 to 1,600 μm, with a ratio of orifice diameter to length of approximately 2 to 8 times.

[0068] The solution extruded from the spinning nozzle (1) passes through an air gap in a vertical direction and solidifies in a coagulation bath (2). The air gap is appropriately 10 to 300 mm in length to obtain dense and uniform fibers and to provide a smooth cooling effect. The air gap serves to pre-quench the liquid dope by supplying air to the dope discharged from the spinning nozzle. At this time, for the smooth progress of the spinning process, the temperature of the supplied air may be 10 to 30°C.

[0069] The dope that has passed through the air gap is coagulated in the coagulation bath (2) to form a filament shape, and the filament that has passed through the coagulation bath (2) passes through the washing tank (3). In the washing tank, N-methylmorpholine-N-oxide (NMMO) and other impurities remaining in the filament can be removed.

[0070] The temperature of the coagulation bath (2) and the washing bath (3) is preferably set to 10 to 25°C to prevent a decrease in physical properties caused by the formation of pores within the fiber tissue due to rapid desolvation. The fibers that have passed through the washing bath (3) pass through a squeezing roller (4) to remove moisture, and then pass through a primary lubricant treatment device (5). A lubricant is applied to the surface of the filament to reduce friction applied to the filament. At this time, the type of lubricant that can be used is not particularly limited, and any known lubricant known in the relevant technical field may be used. After lubricant treatment, the surface lubricant of the filament can be removed using a roller, etc., located before and / or after the lubricant treatment step so that the amount of lubricant applied to the multifilament is constant.

[0071] Afterward, the filament that has passed through the first emulsion treatment device (5) is dried by passing through the drying device (6). At this time, the drying temperature, drying method, and drying tension have a significant effect on the subsequent processing and physical properties of the filament. In the present invention, the drying temperature is adjusted so that the process moisture content can be 7 to 13%.

[0072] The filament that has passed through the drying device (6) passes through the second lubricant treatment device (7) and is finally wound on the winder (8). The second lubricant treatment can be performed to prevent static electricity from being generated in the tow and to give flexibility to the tow. The second lubricant treatment can be performed in the same way as or in a manner similar to the first lubricant treatment step.

[0073] The fineness of the lyocell fiber wound on the winder (8) is not particularly limited, but the single filament fineness is preferably 0.01 to 10 denier. In order to maintain the high strength characteristics of the lyocell fiber, the single filament fineness is preferably 0.5 to 10 denier, more preferably 0.7 to 3 denier, and most preferably 0.7 to 2 denier. In addition, the total fineness is not particularly limited, but can typically be 1000 to 5000 denier.

[0074] The tire cord of the present invention can be manufactured by twisting the lyocell fibers to produce a lyocell yarn, then plying the 2 to 3 ply lyocell yarns together again, treating with an adhesive solution for tire cords according to a conventional dipping method, and drying and heat treating the same.

[0075] As the adhesive solution, a conventional impregnation solution for tire cords may be used, and preferably, a resorcinol-formaldehyde-latex (RFL) adhesive solution may be used. The cord that has passed through the adhesive solution is manufactured into a dip cord through a drying process and a heat treatment process.

[0076] The present invention will be described in more detail below with reference to specific embodiments, but these embodiments are intended merely to provide a clearer understanding of the invention and are not intended to limit the scope of the invention.

[0077] Examples

[0078] Example 1

[0079] A cellulose solution was prepared by adding 0.011 wt% of soft wood pulp with a degree of polymerization (DP) of 1200 (α-cellulose content: 95%), NMMO1H2O, and propyl gallate with a powder size of 519 μm relative to the solution. The cellulose concentration was set to 9–14%, and the solution was extruded through a spinning nozzle with an orifice diameter of 100–200 μm and an orifice length of 200–1,600 μm, with an orifice diameter-to-length ratio (L / D) of 2 to 8. Subsequently, the solution extruded from the spinning nozzle passed through an air gap with a vertical length of 30–100 mm and solidified in a coagulation bath. The filament exiting the coagulation bath had residual NMMO removed through a washing process, was dried after a first lubrication treatment device, and then wound after a second lubrication treatment. Radiation conditions and variables are shown in Table 1.

[0080] Two strands of lyocell yarn were each given a twist of 420 TPM, and then combined to give a twist of 400 TPM to produce a raw cord. The obtained raw cord was dried at 100°C for 200 seconds, and then passed through an adhesive solution prepared by the following method to apply the adhesive solution.

[0081] A solution comprising 50 parts by weight of 29.4 wt% resorcinol; 200 parts by weight of distilled water; 30 parts by weight of 37% formalin; and 15 parts by weight of 10 wt% sodium hydroxide was prepared, reacted at 25°C for 4 hours while stirring, and then the following component was added:

[0082] 300 parts by weight of 40wt% VP-latex, 90 parts by weight of NR-latex, and 300 parts by weight of distilled water were added, and the mixture was aged at 25℃ for 18 hours to maintain a solid content concentration of 20.6%.

[0083] After applying the adhesive solution and drying at 160°C for 120 seconds, the adhesive treatment was completed by heat treatment at 160°C for 60 seconds. The physical properties of the dip code prepared in this way were evaluated and are shown in Tables 1 and 2.

[0085] Examples 2–4 and Comparative Examples 1–2

[0086] Lyocell fibers were manufactured in the same manner as Example 1, except that the amount of alkyl gallate added to the spinning dope was varied as shown in Table 1 below, and the physical properties of the yarn and dip cord were evaluated in the same manner as in Example 1, and the results are shown in Table 1 below.

[0088] Examples 5–6 and Comparative Examples 3–4

[0089] Lyocell fibers were manufactured in the same manner as in Example 1, except that the particle size of the alkyl gallate added to the spinning dope was varied as shown in Table 2 below, and the physical properties of the yarn and dip cord were evaluated in the same manner as in Example 1, and the results are shown in Table 2 below.

[0091] Test example

[0092] For the lyocell yarn and tire cord prepared in the above examples and comparative examples, strength, strength, elongation, degree of polymerization, strength retention rate, fatigue strength, and fatigue resistance were measured as follows, and the results are shown in Tables 1 and 2 below.

[0093] (a) Input amount of alkyl gallate and powder size energy

[0094] The amount of alkyl gallate added was based on the weight of the dope dissolved in the NMMO solvent, and the powder size of the alkyl gallate was determined by measuring the powder size value while falling for 10 seconds using Particle Size Analysis, with 5 measurements taken for each sample and the average value obtained.

[0095] (b) Tensile properties of yarn

[0096] Tensile properties were measured by leaving the sample in a constant temperature and humidity (20~24℃, 55~65% relative humidity) for 24 hours before measurement, then oven drying it at 107℃ for 2 hours, and then measuring it using the ASTM D-885 method.

[0097] (c) Degree of yarn polymerization (%)

[0098] The intrinsic viscosity [IV] of the dissolved cellulose was measured using a Uwe Roed viscometer with a 0.5 M cupriethylenediamine hydroxide solution prepared according to ASTM D539-51T at 25°C in a concentration range of 0.1 to 0.6 g / dl. The intrinsic viscosity is obtained by extrapolating the specific viscosity according to concentration and substituting it into the Mark-Howinck equation to obtain the degree of polymerization.

[0099] [IV] = 0.98X10 -2 DPw 0.9

[0100] DP(D of pulp o Measure the degree of polymerization and measure the DP (D1) of the yarn, and calculate the degree of polymerization retention rate according to Formula 2 below.

[0101] [Equation 2]

[0102] Polymerization degree retention rate (%) = (D o - D1) / D o Х100

[0103] (d) Tire cord strength (kgf)

[0104] After drying at 107℃ for 2 hours, the sample was measured using an Instron low-speed elongation tensile testing machine with a sample length of 250 mm and a tensile speed of 300 m / min.

[0105] (d) Strong utilization rate

[0106] The strength of the filament yarn, measured using an Instron low-speed elongation tensile testing machine with a sample length of 250 mm and a tensile speed of 300 m / min after drying at 107°C for 2 hours, was expressed as the ratio of the strength of a raw cord formed by twisting two strands of filament yarn (A, B). The strength utilization rate was calculated using the following Equation 3.

[0107] [Equation 3]

[0108] Strength Utilization Rate (%) = Deep Code Strength / (Yarn A Strength + Yarn B Strength) × 100

[0109] (e) Endo-fatigue

[0110] A belt fatigue tester was used to evaluate fatigue resistance. The belt fatigue tester is a device that evaluates the fatigue resistance of a dip cord by repeatedly applying bending deformation. Fatigue resistance was compared by measuring the residual strength after the fatigue test according to Equation 1 below. The fatigue test conditions involved applying a load of 40 kg at 180 RPM and a spindle of 0.5 inch to a specimen vulcanized with a cord sandwiched between rubber, and repeating the test 15,000 times at 40°C. After the fatigue test, the rubber and cord were separated to measure the residual strength (fatigue resistance). The residual strength was measured using a conventional tensile strength tester after drying at 107°C for 2 hours.

[0111] [Formula 1]

[0112] Fatigue Resistance (%) = (Fatigue Resistance / Code Strength Before Fatigue Test) × 100

[0113] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Degree of pulp polymerization 1200 1200 1200 1200 1200 1200 Profile gallate Size (㎛) 519 519 519 519 519 519 Input amount (dope wt%) 0.011 0.021 0.031 0.041 0.009 0.051 yarn Denier 1583 1583 1581 1585 1583 1588 Strength (kg) 11.3 11.7 11.8 11.9 11.0 11.8 Strength (g / d) 7.1 7.4 7.4 7.5 6.9 7.4 Desperation (%) 6.5 6.5 6.5 6.5 6.2 6.2 Degree of polymerization 910 950 998 1016 840 1010 Polymerization degree retention rate (%) 76 79 83 85 70 84 Deep Code (1650d / 2,420TPM) Strength (kg) 18.3 18.7 19.1 19.3 16.3 19.0 Desperation (%) 7.8 8.2 8.6 8.6 7.3 8.5 Strength retention rate (%) 81 80 81 81 74 81 Strong inner skin (kg) 11.4 12.5 14.3 14.5 9.4 14.0 Fatigue resistance (%) 63 67 74 75 58 74

[0114] Example 5 Example 6 Comparative Example 3 Degree of pulp polymerization 1200 1200 1200 Profile gallate Size (㎛) 322 519 736 Input amount (dope wt%) 0.031 0.031 0.031 yarn Denier 1586 1581 1583 Strength (kg) 11.9 11.8 11.5 Strength (g / d) 7.5 7.4 7.3 Desperation (%) 6.6 6.5 6.1 Degree of polymerization 1003 998 941 Polymerization degree retention rate (%) 85 85 80 Deep Code (1650 d / 2,420 TPM) Strength (kg) 19.1 19.1 18.5 Desperation (%) 8.8 8.6 8.0 Strong retention rate (%) 80 81 80 Strong inner skin (kg) 14.5 14.3 11.9 Fatigue resistance (%) 76 74 64 Nozzle pack replacement cycle 100% 90% 66%

[0116] As shown in Tables 1 and 2 above, it can be seen that the tire cords according to Examples 1 to 6 of the present invention have excellent strength characteristics, and in particular, excellent fatigue resistance. In addition, in the comparative example, it can be confirmed that the strength retention rate after fatigue is low, and the residual strength is low. The tire cords of the present invention have excellent fatigue resistance characteristics, exhibit high-speed driving performance, and can be used in the manufacture of tires with excellent durability. When the size is large, the pressure of the nozzle pack (1) rises faster and must be changed more frequently.

[0117] Although the present invention has been described in detail above, the above description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art will understand that various modifications and variations are possible within the scope of the essential characteristics of the present invention. The true scope of protection of the present invention should be interpreted by the claims, and all technical concepts within the equivalent scope should be interpreted as being included within the scope of rights of the present invention. Explanation of the symbols

[0119] 1: Nozzle Pack 2: Coagulation 3: Defense 4: Squeezing Roller 5: 1st emulsion 6: Drying 7: 2nd Emulsion 8: Winder

Claims

Claim 1 Lyocell fiber comprising a cellulose-based polymer and 0.01 to 0.05 wt% of alkyl gallate having a particle size of 200 μm to 700 μm. Claim 2 The lyocell fiber according to claim 1, characterized in that the lyocell fiber comprises soft wood pulp having a degree of polymerization of 850 or more and an α-cellulose content of 95% or more. Claim 3 A lyocell fiber according to claim 1, characterized in that the alkyl gallate is selected from the group consisting of ethyl gallate, propyl gallate, isopropyl gallate, butyl gallate, pentyl gallate, hexyl gallate, heptyl gallate, octyl gallate, nonyl gallate, decyl gallate, and dodecyl gallate. Claim 4 A tire cord comprising lyocell fibers according to any one of claims 1 to 3, having a strength utilization rate of 80% or more and a fatigue resistance of 70% or more. Claim 5 A method for manufacturing lyocell fibers from a lyocell spinning dope in aqueous tertiary amine oxide, characterized by adding 0.01 to 0.05 wt% of an alkyl gallate having a particle size of 200 μm to 700 μm to the lyocell spinning dope. Claim 6 In paragraph 5, the above method A step of preparing a spinning dope by dissolving a cellulose-based polymer and an alkyl gallate having a particle size of 200 μm to 700 μm in an aqueous solution of tertiary amine oxide at a content of 0.01 to 0.05 wt% relative to the total weight of the spinning dope; A step of extruding and solidifying the above-mentioned spinning dope through a spinning nozzle; and A method for manufacturing lyocell fibers comprising the step of washing and drying the above-mentioned coagulated product. Claim 7 A method for manufacturing lyocell fibers according to claim 6, characterized in that N-methylmorpholine-N-oxide (NMMO) is used as the tertiary amine oxide. Claim 8 A method for manufacturing a lyocell fiber according to claim 5, characterized in that the alkyl gallate is selected from the group consisting of ethyl gallate, propyl gallate, isopropyl gallate, butyl gallate, pentyl gallate, hexyl gallate, heptyl gallate, octyl gallate, nonyl gallate, decyl gallate, and dodecyl gallate. Claim 9 A method for manufacturing lyocell fibers, characterized in that, in any one of claims 5 to 8, an air gap is provided between the spinning nozzle outlet and the surface of the coagulation bath.

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