Highly elastic nylon cord and method of making same

Abstract

The present invention relates to a high-elasticity nylon cord and a method for manufacturing the same, and an object of the present invention is to manufacture a nylon cord having high elasticity by reducing the moisture content of a raw cord through a drying process when the cord is manufactured.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2021-0124773, filed on September 17, 2021, the entire contents of which are incorporated herein by reference.

[0002] This invention relates to nylon cords with high elasticity and methods for preparing the same. Background Technology

[0003] The cap ply on a tire is the outermost reinforcing material besides the tread, and it reinforces the tire circumferentially. At high temperatures, it provides contractile force to control tire size and prevent increased rotational resistance. Nylon 6.6 is widely used as the material for this cap ply because of its high contractile force.

[0004] In terms of material properties, the physical properties of nylon will change greatly depending on whether it absorbs water. When the moisture content is high, the fibers will shrink, resulting in a decrease in elasticity.

[0005] Previously, to address the aforementioned issues and improve the elasticity of nylon cords, production methods included increasing the draw ratio, a factor in the raw yarn preparation process, or applying high temperatures and reverse stretching during cord fabrication. However, when manufacturing nylon cords, increasing the draw ratio is closely related to the cord breakage rate; as cord breakage increases, process degradation occurs. Furthermore, the application of high temperatures (specifically, above 250°C) and reverse stretching during cord fabrication can actually stiffen the cord, thus limiting its fatigue resistance.

[0006] Therefore, it is necessary to develop a technology for preparing nylon tire cords with improved elasticity. Summary of the Invention

[0007] Technical issues

[0008] The present invention is proposed to solve the above-mentioned problems. The purpose of the present invention is to provide the following nylon cord and its preparation method, which can ensure high elasticity when using nylon, which is sensitive to moisture absorption, to prepare tire cord.

[0009] Technical solution

[0010] According to one embodiment of the present invention, the present invention provides a nylon cord characterized in that the load under 2% tension (LASE 2%) is 0.6 g / d or more, the load under 4% tension (LASE) is 1.0 g / d or more, and the shrinkage rate measured at 177°C for 2 minutes under a primary load of 0.05 g / d is 6% or less.

[0011] As a specific example, the load of nylon cord at 2% tension (LASE 2%) can be 0.6 g / d to 1.2 g / d, and the load at 4% tension (LASE) can be 1.0 g / d to 2.0 g / d.

[0012] Furthermore, the present invention is characterized in that, for the nylon cord of the present invention, the moisture content of the original cord is 0.5% to 3.5%, based on the entire original cord before dipping in the impregnation liquid.

[0013] According to another embodiment of the present invention, the present invention provides a method for preparing nylon cord, characterized by comprising the following steps: melt spinning and cooling a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid to prepare undrawn yarn; subjecting the undrawn yarn to multi-stage stretching and winding through 3 or more guide rollers to prepare nylon precursor yarn; twisting the nylon precursor yarn up and down at 100 TPM to 550 TPM to prepare raw cord; drying the raw cord; and impregnating the dried raw cord with an impregnation solution followed by drying and heat treatment to prepare sizing cord.

[0014] As a specific example, the present invention is characterized in that, in the step of drying the original cord, heat treatment is performed at a temperature of 150°C or higher for 100 seconds or more, and the drying process can be performed at a temperature of 150°C to 240°C for 100 seconds to 300 seconds.

[0015] On the other hand, the moisture content of the dried original cord can be from 0.5% to 3.5%.

[0016] The effects of the invention

[0017] The nylon cord and its preparation method in this invention can adjust the moisture content of the original nylon cord through the process of drying the original nylon cord, thereby improving the elasticity of the final tire cord. Detailed Implementation

[0018] The present invention provides nylon cord characterized in that the load under 2% tension (LASE 2%) is 0.6 g / d or more, the load under 4% tension (LASE) is 1.0 g / d or more, and the shrinkage rate measured at 177°C for 2 minutes under primary load of 0.05 g / d is less than 6%.

[0019] This invention provides a method for preparing nylon cord, characterized by comprising the following steps: melt spinning and cooling a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid to prepare undrawn yarn; subjecting the undrawn yarn to multi-stage stretching and winding through 3 or more guide rollers to prepare nylon precursor yarn; twisting the nylon precursor yarn up and down at 100 TPM to 550 TPM to prepare raw cord; drying the raw cord; and immersing the dried raw cord in an impregnation solution followed by drying and heat treatment to prepare sizing cord, wherein in the step of drying the raw cord, the raw cord is dried at a temperature of 150°C or higher for 100 seconds or more.

[0020] Forms of implementing the invention

[0021] This invention can have various modifications and forms, with specific embodiments illustrated in the figures and described in detail herein. However, this is not to limit the invention to the specific disclosed forms, but should be understood to include all modifications, equivalent technical solutions, or alternative technical solutions within the scope of the invention's ideas and technology.

[0022] In this application, terms such as "comprising" or "having" are used to specify the presence of features, numbers, steps, actions, structural elements, components, or combinations thereof described in the specification, without precluding the presence or additional possibility of one or more other features, numbers, steps, actions, structural elements, components, or combinations thereof. Furthermore, when referring to a layer, membrane, region, plate, or other portion as being "above" other portions, this includes being "directly above" other portions and the presence of other portions in between. Conversely, when referring to a layer, membrane, plate, or other portion as being "below" other portions, this includes being "directly below" other portions and the presence of other portions in between. Moreover, in this application, "arranged above" includes both the case of being arranged in the upper part and the case of being arranged in the lower part.

[0023] This invention relates to high-elasticity nylon tire cord, characterized in that the load under 2% tension (LASE 2%) is 0.6 g / d or more, the load under 4% tension (LASE) is 1.0 g / d or more, and the shrinkage rate measured at 177°C for 2 minutes under an overload of 0.05 g / d is 6% or less.

[0024] Furthermore, a method for preparing nylon cord according to an embodiment of the present invention may include the following steps: preparing undrawn yarn by melt spinning and cooling a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid; preparing nylon precursor yarn by subjecting the undrawn yarn to multi-stage stretching and winding through 3 or more n guide rollers; preparing raw cord by twisting the nylon precursor yarn up and down at 100 TPM to 550 TPM; drying the raw cord; and preparing sizing cord by impregnating the dried raw cord with an impregnation solution and then drying and heat-treating it.

[0025] Preferably, the polyamide polymer is polymer 66 (nylon 66).

[0026] Specifically, the present invention is characterized by reducing the moisture content of the original nylon cord by drying the original cord, thereby increasing the elasticity of the final prepared cord (impregnated cord).

[0027] First, the polyamide polymer used in this invention will be described.

[0028] The polyamide prepared in the cord of this invention contains a highly polar amide in its main chain and exhibits stereoregularity and symmetry, thus possessing crystallinity. Generally, polyamide refers to a general term for polymers linked by amide bonds (-CONH-), formed by the condensation polymerization of diamines and diacids. The properties of polyamides change according to the amide bonds within their molecular structure; the physical properties also change according to the proportion of amide groups. For example, when the proportion of amide groups in the molecule increases, specific gravity, melting point, water absorption, and strength will increase.

[0029] Furthermore, polyamides are widely used in clothing, tire cords, carpets, ropes, computer ribbons, parachutes, plastics, and adhesives due to their excellent corrosion resistance, abrasion resistance, chemical resistance, and insulation properties.

[0030] Polyamides are generally classified into aromatic polyamides and aliphatic polyamides, with nylon being a representative aliphatic polyamide. Nylon was originally a trademark of DuPont, but it is now the generic name.

[0031] Nylon is an absorbent polymer, and its reaction is sensitive to temperature. Representative nylons include nylon 6, nylon 66, and nylon 46.

[0032] The present invention is characterized by the use of nylon 66 (polyamide 66).

[0033] Nylon 66 is prepared by dehydration polycondensation reaction of hexamethylenediamine and adipic acid. As a polymer, Nylon 66 is also known as polyhexamethylene adipamide.

[0034]

[0035] In this invention, in order to prepare tire cords using nylon 66, a polyamide polymer formed by the condensation polymerization of hexamethylenediamine and adipic acid is first used.

[0036] Specifically, the polyhexamethylene adipamide polymer contains at least 85 molar percentage of adipamide repeating units, preferably consisting only of adipamide units.

[0037] Alternatively, any polyamide homopolymer and copolymer can be used instead of the aforementioned polyhexamethylene adipamide. This polyamide is primarily aliphatic, and widely used nylon polymers such as poly(hexamethylene adipamide) (Nylon 66), poly(e-hexamethylene adipamide) (Nylon 6), and their copolymers can be used. Most preferably, nylon 66 is used. Other nylon polymers that can be effectively used include nylon 12, nylon 46, nylon 610, and nylon 612.

[0038] The amount of polyhexamethylene adipamide chips added can make the residual amount of copper metal in the final polymer 50 to 80 ppm, so as to improve thermal stability. When the amount is less than 50 ppm, the thermal stability during spinning decreases, thereby causing thermal decomposition. When it is greater than 80 ppm, the copper metal above the required amount will act as a foreign object, thus causing problems during spinning.

[0039] Subsequently, the polyhexamethylene adipamide chips are packaged and spun at a spinning temperature of 270 to 310°C, preferably at a spinning draw ratio of 20 to 200 (linear speed on the initial winding roller / linear speed on the nozzle), via low-temperature melt spinning. This prevents a decrease in polymer viscosity due to thermal decomposition. When the spinning draw ratio is less than 20, the filament cross-sectional uniformity deteriorates, resulting in a significant reduction in stretchability. When it is greater than 200, filament breakage occurs during spinning, making it difficult to produce normal raw yarn.

[0040] Furthermore, for the spinning head, it is preferable to set the L / D (length / diameter) of the compressor screw to between 2.0 and 6.0. In this case, when the L / D value of the screw is less than 2.0, the rate of change of the denier profile of the monofilament will increase, thereby reducing the utilization rate of fiber strength. When the L / D value is greater than 6.0, the process performance will be reduced due to the increase in packaging pressure.

[0041] Subsequently, the melt-spun yarn is rapidly cooled and solidified by passing it through a cooling zone. Within the cooling zone, depending on the method of blowing cooling air, open quenching, circular closed quenching, and radial outflow quenching methods can be used; preferably, open quenching is employed. For the discharged yarn that has passed through the cooling zone and solidified, 0.5% to 1.0% oil is applied to the discharged yarn using an emulsion coating device that reduces the coefficient of friction between filaments and utilizes an emulsion with excellent stretchability and thermal efficiency. Unstretched yarn is prepared using the above method.

[0042] Next, the unstretched yarn is passed through 3 or more stretching guide rollers for multi-stage stretching and then wound to prepare nylon precursor yarn. In this case, it is preferable to pass it through 5 guide rollers.

[0043] Specifically, the yarn passing through the first guide roller is stretched to a total draw ratio of 4.0 or more, preferably 4.5 to 6.2, and more preferably 4.8 to 6.0, by using a spin-draw process to extend the yarn through the second to fifth guide rollers. This yields the final drawn yarn. When the draw ratio is less than 4.0, the strength of the raw yarn and the cord will decrease. When the draw ratio is greater than 6.2, the workability and productivity of the stretching process will decrease, and the utilization of the raw yarn's strength may be reduced, which is not preferable.

[0044] In this case, preferably, the temperature of the first guide roller is room temperature, the temperature of the second guide roller is room temperature to 90°C, the temperature of the third guide roller is 120°C to 230°C, the temperature of the fourth guide roller is 180°C to 250°C, and the temperature of the fifth guide roller is room temperature to 150°C.

[0045] Furthermore, the stretching speed (spinning speed) of the first guide roller can be 550 m / min or more, preferably 550 to 900 m / min. The stretching speed (winding speed) of the (n-1)th guide roller, preferably the fourth guide roller, can be 3000 m / min or more, preferably 3000 to 4000 m / min. In this case, the total stretching ratio of the speed of the fourth guide roller to the speed of the first guide roller can be 4.8 to 6.4.

[0046] On the other hand, in the above-described multi-stage stretching and winding steps, the relaxation rate imparted to the raw yarn can be 12% or less. In this case, the relaxation rate can be the stretching speed of the (n-1)th guide roller / the stretching speed of the nth guide roller, preferably the speed of the fourth guide roller / the speed of the fifth guide tube.

[0047] Next, the two prepared nylon filaments are twisted and connected together to prepare nylon cord. Specifically, the cord is prepared by applying a twist of 100 TPM to 550 TPM to the two nylon filaments to prepare down-twisted yarns, then twisting the down-twisted yarns together and applying a twist of 100 TPM to 550 TPM to prepare the nylon cord.

[0048] Generally, higher twist results in decreased strength and increased intermediate elongation and elongation at break. Furthermore, fatigue resistance tends to increase with increasing twist. For the nylon cord prepared in this invention, the top and bottom twists are simultaneously prepared from 100 TPM to 550 TPM (twist per meter). A preferred twist range is 200 TPM to 500 TPM, more preferably 300 TPM to 440 TPM. In this case, when the twist is less than 100 / 100 TPM, the elongation at break of the original cord will decrease, and fatigue resistance is easily reduced; when it is greater than 550 / 550 TPM, the strength will significantly decrease, making it unsuitable for tire cords.

[0049] Then, a drying step is performed before the above-mentioned nylon raw cord is impregnated with the impregnation liquid.

[0050] In this invention, the elastic modulus of the final nylon cord can be improved by performing a step of drying the original cord.

[0051] Specifically, in the past, when manufacturing nylon cords, the raw cord was first prepared, and then impregnated in an impregnation solution without a drying process to produce sizing cords. However, as mentioned above, the material properties of nylon change significantly upon absorbing moisture. Therefore, at high moisture content, fiber shrinkage occurs, leading to a decrease in elasticity. Previously, nylon with high moisture content was used, and the draw ratio was increased during the preparation of the raw yarn to improve elasticity. This resulted in increased cord breakage, reduced processability, and lower quality. Furthermore, stretching was performed at temperatures above 250°C during cord preparation. While this improved elasticity, it reduced fatigue resistance, making it unsuitable for use as cords.

[0052] The inventors of this invention recognized the problems with existing methods for improving the elasticity of nylon cords. Through in-depth research, they discovered that by adding a drying process to the original nylon cord to reduce the moisture content within the cord, the elasticity can be improved while maintaining a level equivalent to existing tensile properties. This led to the completion of this invention.

[0053] The present invention is characterized in that the nylon raw cord is dried before being immersed in the impregnation liquid. Specifically, the drying is characterized by performing a heat treatment at a temperature of 150°C or higher for 100 seconds or more. Preferably, the drying conditions are set at a temperature of 150°C to 240°C, more preferably at 170°C to 240°C, and the drying time is maintained at 100 seconds to 300 seconds, more preferably 130 seconds to 200 seconds.

[0054] When the drying temperature is below 150°C, the moisture content of the original cord cannot be sufficiently reduced, resulting in a decrease in elasticity. When the temperature is above 240°C, excessive heat treatment can lead to a decrease in the strength or elongation at break of the prepared cord, or a change in color, resulting in a decrease in marketability.

[0055] Furthermore, when the drying time is less than 100 seconds, the moisture reduction effect is not sufficient, and when it is greater than 300 seconds, the strength or elongation at break of the cord will decrease.

[0056] As mentioned above, it is important to set the moisture content of the dried nylon cord to between 0.5% and 3.5%. When the moisture content of the cord is below 0.5%, excessive heat and heat treatment time can lead to cord breakage, resulting in a decrease in the physical properties of the final tire cord, compared to the high elasticity achieved by reducing the moisture content. Furthermore, when the moisture content is greater than 3.5%, the moisture content is not sufficiently reduced, thus failing to achieve the desired effect of improving elasticity.

[0057] Next, the aforementioned raw nylon cord (dried raw cord) is impregnated in an impregnation solution, followed by drying and heat treatment to prepare dip-cord cord. Typically, the raw cord is woven using a weaving machine, and the resulting fabric is impregnated in an impregnation solution and cured to produce dip-cord cord for tires with a resin layer attached to the surface of the raw cord. In other words, dip-cord cord for tires with a resin layer attached to the surface of the raw cord is prepared. The impregnation process is generally referred to as the impregnation process. Impregnation refers to impregnating the fiber surface with a resin layer called resorcinol-formaline-latex (RFL), which imparts adhesion between the tire cord fibers and rubber through the impregnation process.

[0058] For typical nylon fibers, a single-bath impregnation is generally performed, but a two-bath impregnation can also be carried out.

[0059] Typically, the impregnation solution used to bond cords and rubber can react with a solution containing resorcinol, formalin, sodium hydroxide, etc., and latex is added to it and then allowed to mature before it is used.

[0060] The impregnation solution is applied after the cord is dried. A stretch of 0% to 3% is required to adjust the amount of impregnation solution adhering; preferably, a stretch of 1% to 2% can be performed. When the stretch ratio is too high, the amount of impregnation solution adhering can be adjusted, but the elongation at break will decrease, resulting in reduced fatigue resistance. On the other hand, when the stretch ratio is too low, for example, when it is reduced to less than 0%, the impregnation solution will penetrate into the cord, and the physical properties of the cord will actually decrease.

[0061] Preferably, based on the solid content, the amount of impregnating liquid adhering to the fiber is 4% to 6% relative to the fiber weight. After passing through the impregnating liquid, the impregnated cord is dried at a temperature of 120°C to 150°C. Drying takes 180 to 220 seconds, and it is beneficial for the impregnated cord to be stretched by about 1% to 2% during the drying process. When the stretching ratio is low, the intermediate elongation and breaking elongation of the cord will increase, resulting in properties that are difficult to apply as tire cords. On the other hand, when the stretching ratio is greater than 3%, the intermediate elongation is more suitable, but the breaking elongation becomes too small, which may reduce fatigue resistance.

[0062] After drying, heat treatment is performed in a temperature range of 130°C to 240°C. During heat treatment, the stretching ratio is maintained between -1% and 0%, and the appropriate heat treatment time is 50 to 90 seconds.

[0063] As described above, by drying the raw cord, the moisture content of the raw cord is reduced based on the entire raw cord. This increases the load under specific tension (LASE) and reduces the shrinkage rate of the cord, resulting in an increase in the elasticity of the nylon tire cord. Specifically, the nylon tire cord has a load (LASE 2%) of 0.6 g / d or more under 2% tension, a load (LASE 4%) of 1.0 g / d or more under 4% tension, and a shrinkage rate of less than 6% measured for 2 minutes at 177°C under an overload of 0.05 g / d. Preferably, the nylon tire cord of the present invention has a load (LASE 2%) of 0.6 g / d to 1.2 g / d under 2% tension, a load (LASE 4%) of 1.0 g / d to 2.0 g / d under 4% tension, and a shrinkage rate of 2% to 6%.

[0064] Furthermore, even without increasing the draw ratio of the raw yarn or applying high temperature and stretching conditions during the preparation of the cord, the nylon cord prepared as described above can still produce high elasticity nylon tire cord, satisfying the physical properties of high elasticity. The tensile physical properties such as strength and elongation at break will not decrease and can be maintained at the same level as before.

[0065] The embodiments of the present invention will be described in detail below. However, the following embodiments are merely illustrative of the present invention, and the present invention is not limited to the following embodiments.

[0066] [Example 1]

[0067] Using a compressor, polyhexamethylene adipamide chips with a relative viscosity (RV) of 3.4, formed by the condensation polymerization of hexamethylenediamine and adipic acid, were melt-spun at a temperature of 296°C. The spun yarn was then passed through a 600 mm long cooling zone for curing and subsequently oiled with a spinning emulsion. The undrawn yarn was then subjected to two-stage drawing and wound to prepare 420 denier nylon precursor. In this case, the draw ratio was 4.8.

[0068] Subsequently, the two strands of nylon filament were twisted together at 420 TPM to prepare the original cord.

[0069] The prepared raw cord was heat-treated at 240°C for 100 seconds to perform a drying process. Under these conditions, the moisture content of the raw cord was 0.5% based on the whole raw cord.

[0070] Next, the woven raw cord, after drying, is braided and then impregnated with an impregnation solution containing RFL. Afterward, it is dried at 130°C for 180 seconds with 1% stretch, and then heat-treated at 150°C for 50 seconds with 0% stretch to prepare the nylon cord (impregnated cord).

[0071] [Examples 2 to 3]

[0072] Except for adjusting the drying conditions and moisture content of the original cord as shown in Table 1 below, nylon cords were prepared using the same process as in Example 1.

[0073] [Comparative Example 1]

[0074] Nylon cords were prepared using the same process as in Example 1, except that the process of drying the original cords was not performed.

[0075] [Compare Examples 2 and 3]

[0076] Except for adjusting the drying conditions and moisture content of the original cord as shown in Table 1 below, nylon cords were prepared using the same process as in Example 1.

[0077] [Experimental Example]

[0078] The moisture content and physical properties of the original cords and impregnated cords prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated using the following methods, and the results are presented in Table 1 below.

[0079] 1) Moisture content of the original cord (based on the overall original cord)

[0080] The moisture content of the original cord was determined using a hot air circulating oven equipped with an automatic temperature control. After drying at an oven temperature of 125±3℃ for 30±0.5 minutes, it was placed in a desiccator and cooled for 15 minutes before being weighed. The moisture content was calculated using the following formula.

[0081] Moisture content (%) = (Weight before drying - Weight after drying) / Weight after drying × 100

[0082] 2) Strength and elongation at break of the PVC-impregnated cord

[0083] After the specimens were placed in a constant temperature and humidity chamber at 25°C and 65% RH for 24 hours, the specimens were tested by tensile testing machine according to the ASTM D-885 method.

[0084] 3) Load at Specified Elongation (LASE) of the impregnated cord

[0085] The tensile load curves obtained by the JIS L1O17 method were obtained using loads at specific elongation rates (2%, 4%). The samples were placed at 20°C and 65% RH for 24 hours before the measurement.

[0086] Specifically, the load at a specified elongation rate (g / d, 2%) is obtained by dividing the load value at 2% elongation by denier, and the load at a specified elongation rate (g / d, 4%) is obtained by dividing the load value at 4% elongation by denier.

[0087] 4) Shrinkage rate of PVC-impregnated cord

[0088] The samples were exposed at 177°C and under a preset tension of 0.05 g / d overload for 2 minutes before measurement. The Testrite heat shrinkage tester was used for the measurement. Specifically, the shrinkage rate of the dipped cord was automatically measured in the Testrite. A cord sample with an overload of 0.05 g / d was placed in a chamber heated to 177°C, and the shrinkage rate was automatically displayed in the window after 2 minutes, allowing for measurement.

[0089] [Table 1]

[0090]

[0091] Referring to Table 1, for the nylon cord prepared according to the examples, after the original cord was prepared, a drying process based on the optimal drying temperature and drying time was performed, thereby setting the moisture content of the original cord within the optimal range. As a result, compared with Comparative Example 1, which did not perform the drying process, the strength and elongation at break of the impregnated cord remained at the same level, the LASE value was higher, and the shrinkage rate was lower. On the other hand, although a drying process was performed on the original cord, in Comparative Example 2, where the drying temperature was lower than the range of the present invention, the moisture content of the original cord increased, and ultimately, the LASE value of the impregnated cord became higher, exhibiting physical properties at the same level as Comparative Example 1, which performed the drying process, resulting in a decrease in shrinkage rate. On the other hand, in Comparative Example 3, where the set drying temperature was too high, as drying was carried out at a temperature higher than the melting point of the nylon cord, phenomena such as fiber carbonization occurred, which could ultimately lead to a decrease in the physical properties of the cord.

[0092] In summary, the nylon cord prepared in the embodiments can adjust the moisture content of the original cord. Thus, as in the past, even without changing the draw ratio or increasing the heat treatment temperature during cord preparation, the cord exhibits excellent tensile properties and a good target elastic modulus.

[0093] The above description is merely illustrative of the technical concept of the present invention. Those skilled in the art can make various modifications and variations without departing from the essential characteristics of the present invention. The scope of protection of the present invention is explained by the following claims; all technical concepts within this equivalent scope fall within the scope of protection of the present invention.

[0094] Industrial availability

[0095] This invention is the best invention for improving the elasticity of the final tire cord by adjusting the moisture content of the original nylon cord through the process of drying the original nylon cord.

Claims

1. A method for preparing nylon cord, characterized in that, Includes the following steps: Undrawn yarns were prepared by melt spinning and cooling of a polyamide polymer synthesized from hexamethylenediamine and adipic acid. Nylon precursor yarn is prepared by passing the unstretched yarn through 3 or more n guide rollers for multi-stage stretching and winding. The original cord is prepared by twisting the above-mentioned nylon filaments up and down at 100TPM to 550TPM. Dry the original cords mentioned above; and The dried original cord is impregnated with an impregnation solution followed by drying and heat treatment to prepare a resin-impregnated cord, wherein the impregnation solution contains resorcinol-formaldehyde-latex. In the step of drying the original cord, the original cord is dried at a temperature of 150°C or higher for 100 seconds or more to obtain a dried original cord with a moisture content of 0.5% to 3.5%.

2. The method for preparing nylon cord according to claim 1, characterized in that, In the step of drying the original cord described above, the cord is dried at a temperature of 150°C to 240°C for 100 to 300 seconds.

3. The nylon cord prepared by the method of claim 1, characterized in that, The load at 2% stretch is ≥0.6 g / d, and the load at 4% stretch is ≥1.0 g / d. At 177°C, the shrinkage rate was less than 6% after 2 minutes under an overload of 0.05 g / d. Furthermore, based on the entire original cord before it was impregnated with the impregnation liquid, the moisture content of the aforementioned nylon cord was 0.5% to 3.5%.

4. The nylon cord according to claim 3, characterized in that, The load of the aforementioned nylon cord is 0.6 g / d to 1.2 g / d at 2% tension and 1.0 g / d to 2.0 g / d at 4% tension.

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