High-elastic nylon cord and its manufacturing method

Abstract

The present invention relates to a highly elastic nylon cord and a method for producing the same, and has an object to produce a nylon cord having a high elastic modulus by reducing the moisture content of the raw cord through a drying process during cord production.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0124773 filed on September 17, 2021, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] The present invention relates to a nylon cord having a high modulus of elasticity and a method for manufacturing the same.

Background Art

[0003] The cap ply in a tire is a material reinforced on the outermost side except for the tread, and is reinforced parallel to the circumferential direction of the tire. At high temperatures, it exhibits a contraction force to suppress the size of the tire and plays a role in preventing an increase in rotational resistance. The most widely used substance as such a cap ply material is nylon 6,6, which is known to be due to the high contraction force of nylon 6,6.

[0004] Nylon, due to the characteristics of the material, has a large change in physical properties depending on whether it can absorb moisture. However, if the moisture content is high, there is a problem that the contraction of the manufactured fiber occurs and the elastic force decreases.

[0005] Conventionally, in an attempt to solve the above problems, there has been a method of producing by increasing the draw ratio, which is a factor in the raw yarn manufacturing process, to improve the modulus of elasticity of the nylon cord, or a method of manufacturing by applying high temperature and stretch in the cord manufacturing step. However, increasing the draw ratio when manufacturing a nylon cord has a close relationship with the yarn breakage rate, and there has been a problem that the processability is reduced by increasing the occurrence of yarn breaks. In addition, the application of high temperature (specifically, 250 °C or higher) and stretch in the cord manufacturing step has a limit in that it rather causes the cord to become hard and the fatigue resistance to decrease.

[0006] Therefore, there is a situation where the development of a technology for manufacturing a nylon tire cord with an improved modulus of elasticity is required.

Summary of the Invention

Problems to be Solved by the Invention

[0007] The present invention has been devised to solve the above problems, and an object thereof is to provide a nylon cord that can ensure a high elastic modulus even when manufacturing a tire cord by using nylon that is sensitive to moisture absorption, and a method for manufacturing the same.

Means for Solving the Problems

[0008] According to an embodiment of the present invention, the present invention provides a nylon cord characterized in that the load at 2% elongation (LASE 2%) is 0.6 g / d or more, the load at 4% elongation (LASE 4%) is 1.0 g / d or more, and the shrinkage rate measured at a primary load of 0.05 g / d at 177°C for 2 minutes is 6% or less.

[0009] Specifically, as an example, the nylon cord may have a load at 2% elongation (LASE 2%) of 0.6 to 1.2 g / d and a load at 4% elongation (LASE 4%) of 1.0 to 2.0 g / d.

[0010] Further, the nylon cord of the present invention is characterized in that the moisture content of the green cord is 0.5 to 3.5% based on the entire green cord before dipping in the dipping solution.

[0011] According to another embodiment of the present invention, the present invention provides a method for manufacturing a nylon cord, comprising steps of: producing an undrawn yarn by melt-spinning and cooling a polyamide polymer produced by condensation polymerization of hexamethylenediamine and adipic acid; producing a nylon raw yarn by multi-stage drawing and winding the undrawn yarn through 3 or more n godet rollers; producing a green cord by twisting the nylon raw yarn at 100 to 550 TPM; drying the green cord; and producing a dipped cord by dipping the dried green cord in a dipping solution and then drying and heat-treating it.

[0012] As a specific example, the step of drying the green cord is characterized in that the green cord is heat-treated at a temperature of 150°C or higher for 100 seconds or longer, and the drying process can be performed at 150 to 240°C for 100 to 300 seconds.

[0013] On the other hand, the moisture content of the dried green cord can be 0.5 to 3.5%.

Advantages of the Invention

[0014] The nylon cord and its manufacturing method according to the embodiments of the present invention can improve the elastic modulus of the finally manufactured tire cord by adjusting the moisture content of the green cord through the step of drying the nylon green cord.

Modes for Carrying Out the Invention

[0015] [Best Mode for Carrying Out the Invention] The present invention provides a nylon cord characterized in that the load at 2% elongation (LASE 2%) is 0.6 g / d or more, the load at 4% elongation (LASE 4%) is 1.0 g / d or more, and the shrinkage rate measured at an initial load of 0.05 g / d at 177°C for 2 minutes is 6% or less.

[0016] The present invention includes the steps of producing an undrawn yarn by melt-spinning and cooling a polyamide polymer produced by condensation polymerization of hexamethylenediamine and adipic acid, producing a nylon raw yarn by multi-stage stretching and winding the undrawn yarn through 3 or more n godet rollers, producing a green cord by twisting the nylon raw yarn at 100 to 550 TPM, drying the green cord, and producing a dipped cord by immersing the dried green cord in a dipping solution and then drying and heat-treating it. The step of drying the green cord is characterized in that the green cord is dried at a temperature of 150°C or higher for 100 seconds or longer. A method for manufacturing a nylon cord is provided.

[0017] [Modes for Carrying Out the Invention] Since the present invention can be subjected to various modifications and can have various forms, specific embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood to include all modifications, equivalents, and alternatives included in the spirit and technical scope of the present invention.

[0018] In the present application, terms such as "comprising" or "having" are intended to specify that there are features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and it should be understood that they do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. Also, when a part such as a layer, film, region, or plate is "on" another part, this includes not only the case where it is directly on the other part but also the case where there are other parts in between. Conversely, when a part such as a layer, film, region, or plate is "under" another part, this includes not only the case where it is directly under the other part but also the case where there are other parts in between. Also, in the present application, "disposed on" includes not only the case of being disposed on the upper part but also the case of being disposed on the lower part.

[0019] The present invention relates to a highly elastic nylon cord, characterized in that the load at 2% elongation (LASE 2%) is 0.6 g / d or more, the load at 4% elongation (LASE 4%) is 1.0 g / d or more, and the shrinkage rate measured at an initial load of 0.05 g / d at 177°C for 2 minutes is 6% or less.

[0020] Moreover, the method for manufacturing a nylon cord according to an embodiment of the present invention may include steps of: producing an undrawn yarn by melt-spinning and cooling a polyamide polymer produced by condensation polymerization of hexamethylenediamine and adipic acid; producing a nylon raw yarn by multi-stage drawing and winding the undrawn yarn through three or more n godet rollers; producing a green cord by twisting the nylon raw yarn at 100 to 550 TPM; drying the green cord; and producing a dipped cord by dipping the dried green cord in a dipping solution and then drying and heat-treating it.

[0021] The polyamide polymer is preferably polyamide 66 (nylon 66).

[0022] Specifically, the present invention is characterized by improving the elastic modulus of the finally produced cord (dipped cord) by adjusting the moisture content of the green cord to a low level in the step of drying the nylon green cord.

[0023] First, the polyamide polymer used in the present invention will be described.

[0024] The polyamide produced for the cord of the present invention contains an amide group having a strong polarity in the main chain, has stereoregularity and symmetry, and has crystallinity. Generally, polyamide means a general term for polymers linked by amide bonds (-CONH-), and is obtained by condensation polymerization of diamine and dibasic acid. Polyamides are characterized by amide bonds in the molecular structure and vary in physical properties depending on the proportion of amide groups. For example, when the proportion of amide groups in the molecule increases, properties such as specific gravity, melting point, absorbency, and rigidity increase.

[0025] In addition, polyamide is a material with excellent corrosion resistance, abrasion resistance, chemical resistance, and insulation properties, and is applied in a wide range of fields such as clothing, tire cords, carpets, ropes, computer ribbons, parachutes, plastics, adhesives, etc.

[0026] Generally, polyamides are classified into aromatic polyamides and aliphatic polyamides. A typical aliphatic polyamide is nylon. Nylon was originally a trademark of DuPont in the United States, but now it is used as a common name.

[0027] Nylon is an absorbent polymer and reacts sensitively to temperature. Typical nylons include nylon 6, nylon 66, and nylon 46.

[0028] The present invention is characterized by using nylon 66 (polyamide 66).

[0029] Nylon 66 is produced by a dehydration condensation polymerization reaction of hexamethylenediamine and adipic acid. The polymer nylon 66 is also called polyhexamethylene adipamide.

[0030]

Chemical formula

[0031] In the present invention, in order to produce a tire cord using nylon 66, first, a polyamide polymer produced by condensation polymerization of hexamethylenediamine and adipic acid is used.

[0032] Specifically, the polyhexamethylene adipamide polymer contains at least 85 mol% of hexamethylene adipamide repeating units, and preferably is composed only of hexamethylene adipamide units.

[0033] Optionally, any polyamide homopolymer and copolymer may be used instead of the polyhexamethylene adipamide. Such polyamides are mainly aliphatic, and poly(hexamethylene adipamide) (nylon 66); poly(e-caprolactam) (nylon 6); and widely used nylon polymers such as their copolymers may be used, but it is most preferable to use nylon 66. Also, other nylon polymers that can be advantageously used include nylon 12, nylon 46, nylon 610, and nylon 612.

[0034] Polyhexamethylene adipamide chips can be added in an amount such that the remaining amount of copper metal in the final polymer is 50 to 80 ppm in order to improve thermal stability. If this amount is less than 50 ppm, the thermal stability during spinning will decrease and thermal decomposition will occur. If it is more than 80 ppm, the excessive copper metal will act as a foreign substance and cause problems during spinning.

[0035] Next, the polyhexamethylene adipamide chips are melt-spun at a low temperature through a pack and a nozzle, preferably at a spinning temperature of 270 to 310 °C and a spinning draft ratio (linear velocity on the first take-up roller / linear velocity at the nozzle) of preferably 20 to 200, so as to prevent a decrease in the viscosity of the polymer due to thermal decomposition. If the spinning draft ratio is less than 20, the cross-sectional uniformity of the filament will deteriorate and the draw workability will be significantly reduced. If it exceeds 200, filament breakage will occur during spinning and it will be difficult to produce a normal raw yarn.

[0036] Also, in the spinning nozzle, it is preferable to set the L / D (length / diameter) value of the extruder screw to 2.0 to 6.0. At this time, if the L / D value of the screw is less than 2.0, the coefficient of variation of the cross-section of the monofilament denier will increase and the fiber strength utilization rate will decrease. If the L / D value exceeds 6.0, problems such as a decrease in processability due to an increase in the pressure of the pack will occur.

[0037] Next, the melt-extruded yarn is passed through a cooling zone and rapidly cooled and solidified. In the cooling zone, methods such as open quenching, circular closed quenching, and radial outflow quenching can be applied by blowing cooling air, but the open quenching method is preferred. Next, while passing through the cooling zone, the solidified extruded yarn can be oiled at 0.5 to 1.0% with respect to the extruded yarn by an emulsion application device that applies an emulsion excellent in reducing the friction coefficient, stretchability, and thermal efficiency in a short time. The undrawn yarn is manufactured by the method as described above.

[0038] Next, the undrawn yarn is passed through n godet rollers of 3 or more to be multi-stage drawn and wound up to produce nylon raw yarn. At this time, it is preferable to pass through 5 godet rollers.

[0039] Specifically, while passing the yarn that has passed through the first godet roller through the second to fifth godet rollers by the spin draw method, the final drawn yarn is obtained by drawing at a total draw ratio of 4.0 times or more, preferably 4.5 to 6.2, more preferably 4.8 to 6.0. If the draw ratio is less than 4.0, the strength of the raw yarn and cord will decrease. If the draw ratio exceeds 6.2, the draw workability and productivity will decrease, and the strength utilization rate of the raw yarn may decrease, which is not preferable.

[0040] At this time, the temperature of the first godet roller is room temperature, the temperature of the second godet roller is room temperature to 90 °C, the temperature of the third godet roller is 120 to 230 °C, the temperature of the fourth godet roller is 180 to 250 °C, and the temperature of the fifth godet roller is preferably room temperature to 150 °C.

[0041] Also, the stretching speed (spinning speed) of the first godet roller is 550 m / min or more, preferably 550 to 900 m / min. The stretching speed (winding speed) of the (n - 1)th godet roller, preferably the fourth godet roller, is 3,000 m / min or more, preferably 3000 to 4000 m / min. In this case, the total draw ratio, which is the speed of the fourth godet roller / the speed of the first godet roller, can be 4.8 to 6.4.

[0042] On the other hand, in the step of multi-stage stretching and winding, a relaxation rate of 12% or less can be imparted to the raw yarn. At this time, the relaxation rate can be the stretching speed of the (n - 1)th godet roller / the stretching speed of the nth godet roller, preferably the stretching speed of the fourth godet roller / the stretching speed of the fifth godet roller.

[0043] Next, two nylon raw yarns produced are first twisted respectively and then combined and twisted to produce a nylon green cord. Specifically, the green cord can be produced by imparting a twist of 100 to 550 TPM to each of the two nylon raw yarns to produce lower twisted yarns, combining the lower twisted yarns, and then imparting a twist of 100 to 550 TPM for upper twisting.

[0044] Generally, if the twist is high, the strength decreases, and the medium elongation (intermediate elongation) and cut elongation (breaking elongation) tend to increase. Also, the fatigue resistance tends to be improved as the twist increases. The twist number of the nylon cord produced in the present invention is produced at 100 to 550 TPM (twist per meter) for both upper and lower twisting. The preferred range of the twist number is 200 to 500 TPM, more preferably 300 to 440 TPM. At this time, if the twist number is less than 100 / 100 TPM, the cut elongation of the green cord decreases and the fatigue resistance is likely to decrease. If it exceeds 550 / 550 TPM, the decrease in strength is large and it is not suitable as a tire cord.

[0045] Next, a step of drying is performed before dipping the nylon green cord in the dipping solution.

[0046] In the present invention, by performing the step of drying the green cord, the elastic modulus of the finally manufactured nylon cord can be improved.

[0047] Specifically, conventionally, when manufacturing a nylon cord, after manufacturing the green cord, the dipping liquid was immersed without performing a drying process to manufacture a dipped cord. However, as described above, nylon has a large change in physical properties due to water absorption due to the characteristics of the material, so if the moisture content is high, fiber shrinkage occurs, and there is a problem that the elastic modulus decreases. Conventionally, in order to increase the elastic modulus while using nylon with a high moisture content, the draw ratio was increased during the production of the raw yarn, but there was a problem that the number of thread breaks increased, resulting in a decrease in processability and a decrease in quality. In addition, there was also an attempt to stretch at a temperature higher than 250 ° C when manufacturing the cord, but in this case, although the elastic modulus could be increased, there was a problem that it was not suitable for use as a cord due to the problem of low fatigue resistance.

[0048] The inventors of the present invention recognized the problems of the conventional methods for increasing the elastic modulus of nylon cords, and through in-depth research, they found that by adding a step of drying the nylon green cord, if the moisture content in the green cord can be reduced, it is possible to maintain the same level as the conventional in terms of tensile physical properties while increasing the elastic modulus, and thus the present invention was made.

[0049] Therefore, the present invention is characterized in that the nylon green cord is dried before being immersed in the dipping liquid. Specifically, the drying is characterized by performing heat treatment at a temperature condition of 150 ° C or higher for 100 seconds or more. Preferably, the drying conditions are set at a temperature of 150 to 240 ° C, more preferably 170 to 240 ° C, and the drying time is maintained at 100 to 300 seconds, more preferably 130 to 200 seconds.

[0050] If the drying temperature is less than 150°C, there is a problem that the moisture content of the green cord cannot be sufficiently reduced and the modulus of elasticity decreases. If it exceeds 240°C, due to excessive heat treatment, there will be problems such as a decrease in physical properties such as strength or elongation at break of the cord produced, or discoloration, resulting in a decrease in commercial value.

[0051] Also, if the drying time is less than 100 seconds, the effect of reducing the moisture content is not sufficient. If it exceeds 300 seconds, there will be problems such as a decrease in cord physical properties such as strength or elongation at break.

[0052] As described above, it is important to set the moisture content in the dried green cord to 0.5 to 3.5% by drying the nylon green cord. If the moisture content in the green cord is 0.5% or less, due to excessive heat and heat treatment time compared to the effect of high elasticity that can be achieved by reducing the moisture content, the cord will be damaged and the physical properties of the finally produced tire cord will instead decrease. Also, if the moisture content exceeds 3.5%, there is a problem that the effect of improving the modulus of elasticity cannot be exerted because sufficient reduction of the moisture content has not been achieved.

[0053] Next, after immersing the nylon green cord (dried green cord) in the dipping solution, it is dried and heat-treated to produce a dipped cord. Usually, "raw cord" is woven using a weaving machine, and the obtained fabric is immersed and cured in the dipping solution to produce a "dip cord" for tire cords with a resin layer attached to the surface of the "raw cord". That is, a dip cord for tire cords with a resin layer attached to the surface of the raw cord is produced. The process of immersing in the dipping solution is generally called the dipping process. Dipping means impregnating the surface of the fiber with a resin layer called RFL (Resorcinol - Formaline - Latex), and the dipping process can impart adhesiveness between the tire cord fiber and the rubber.

[0054] Ordinary nylon fibers usually undergo one-bath dipping, but two-bath dipping may also be performed.

[0055] Generally, the dipping solution for adhering cord and rubber can be obtained by reacting a solution containing resorcinol, formalin, sodium hydroxide, etc., and further adding latex thereto and aging it.

[0056] After the cord is dried, the dipping solution (adhesive solution) is applied. An elongation of 0 to 3% is required to adjust the amount of the dipping solution attached, but preferably an elongation of 1 to 2% can be performed. If the elongation ratio is too high, the amount of the dipping solution attached can be adjusted, but the cut elongation decreases, and as a result, the fatigue resistance decreases. On the other hand, if the elongation ratio is too low, for example, when it is lowered below 0%, the dipping solution may penetrate into the cord and the physical properties of the cord may instead deteriorate.

[0057] The amount of the dipping solution attached is preferably 4 to 6% based on the solid content with respect to the weight of the fiber. After passing through the dipping solution, the dip cord is dried at 120 to 150°C. It is dried for 180 to 220 seconds, and it is advantageous that the dip cord is dried in a state where it is elongated by about 1 to 2% during the drying process. If the elongation ratio is low, the internal elongation and cut elongation of the cord increase, and the physical properties that are difficult to be applied as a tire cord are shown. On the other hand, if the elongation ratio exceeds 3%, the level of internal elongation is appropriate, but the cut elongation is too small and the fatigue resistance may decrease.

[0058] After drying, it is heat-treated in a temperature range of 130 to 240°C. During the heat treatment, the elongation ratio is maintained between -1 and 0%, and the heat treatment time is appropriately 50 to 90 seconds.

[0059] In this way, by adjusting the moisture content of the green yarn to a low level based on the entire green yarn through the process of drying the green yarn, the load at a specific elongation (LASE) increases, and by reducing the shrinkage rate of the yarn, the elastic modulus of the nylon tire cord can be increased as a result. Specifically, for the nylon tire cord, the load at 2% elongation (LASE 2%) is 0.6 g / d or more, the load at 4% elongation (LASE 4%) is 1.0 g / d or more, and the shrinkage rate measured at an initial load of 0.05 g / d at 177°C for 2 minutes can be 6% or less. The nylon tire cord of the present invention preferably has a load at 2% elongation (LASE 2%) of 0.6 to 1.2 g / d, a load at 4% elongation (LASE 4%) of 1.0 to 2.0 g / d or more, and a shrinkage rate of 2 to 6% or less.

[0060] In addition, the nylon cord manufactured as described above can produce a high elastic modulus nylon tire cord without increasing the draw ratio of the raw yarn as in the conventional method or applying high temperature and stretch conditions during cord manufacturing. It exhibits the effect of maintaining the same level as the conventional method without reducing the tensile physical properties such as strength and cut elongation while satisfying the physical properties of high elastic modulus.

[0061] Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited by the following examples.

[0062] [Example 1] Polyhexamethylene adipamide chips with a relative viscosity (RV) of 3.4, manufactured by condensation polymerization of hexamethylenediamine and adipic acid, were melt-spun at a temperature of 296°C using an extruder. Next, the extruded yarn was passed through a cooling zone with a length of 600 mm to solidify, and then oiled with a radiation emulsion. Next, the undrawn yarn was drawn in two stages and wound up to produce 420-denier nylon raw yarn. At this time, the draw ratio was 4.8.

[0063] Next, two pieces of the manufactured nylon raw yarn were twisted up and down at 420 TPM to produce a green cord.

[0064] The produced green cord was dried by heat treatment at 240°C for 100 seconds. At this time, it was confirmed that the moisture content of the green cord was 0.5% based on the whole of the green cord.

[0065] Next, the green cord that has undergone the drying process is woven, and the woven green cord is immersed in a dipping solution containing RFL. Next, it is dried at 130°C for 180 seconds in a state of 1% elongation, and heat treatment is performed at 150°C for 50 seconds in a state of 0% elongation ratio to produce a nylon cord (dip cord).

[0066] [Examples 2 to 3] Nylon cords were produced by the same process as in Example 1, except that the drying conditions and moisture content of the green cord were adjusted as described in Table 1 below.

[0067] [Comparative Example 1] A nylon cord was produced by the same process as in Example 1, except that the process of drying the green cord was not performed.

[0068] [Comparative Examples 2 and 3] Nylon cords were produced by the same process as in Example 1, except that the drying conditions and moisture content of the green cord were adjusted as described in Table 1 below.

[0069] [Experimental Example] The moisture content of the green cords produced in Examples 1 to 3 and Comparative Examples 1 to 3, and the physical properties of the dip cords were evaluated using the following methods, and the results are shown in Table 1 below.

[0070] 1) Moisture content of the green cord (based on the whole of the green cord) To measure the moisture content of the green cord, a hot air circulation oven equipped with an automatic temperature device is used. After drying at the oven temperature of 125 ± 3°C for 30 ± 0.5 minutes, it is placed in a desiccator and cooled for 15 minutes, and then the weight is measured. The moisture content is calculated by the following formula.

[0071] Moisture content (%) = (Weight before drying - Weight after drying) / Weight after drying × 100 2) Strength and elongation of the dip cord The sample was left in a thermo-hygrostat chamber at standard conditions, i.e., a temperature of 25°C and a relative humidity of 65% RH, for 24 hours, and then measured with a tensile testing machine according to the method of ASTM D - 885.

[0072] 3) LASE (Load At Specified Elongation) of the dip cord The loads at specific elongations (2%, 4%) were taken from the elongation-load curve obtained by the measurement method of JIS L1017. The sample before measurement was left in an atmosphere of 20°C and 65% RH for 24 hours and then measured.

[0073] Specifically, LASE (g / d, 2%) is calculated by dividing the weighted value at 2% elongation by the denier, and LASE (g / d, 4%) is calculated by dividing the weighted value at 4% elongation by the denier.

[0074] 4) Shrinkage rate of the dip cord The sample is measured after being exposed for 2 minutes under a pretension of 177°C and an initial load of 0.05 g / d. The measuring mechanism uses a Testrite thermal shrinkage tester. Specifically, the shrinkage rate of the dip cord is automatically measured by Testrite. After placing a cord sample with an initial load of 0.05 g / d applied in a chamber heated to 177°C, the shrinkage rate is automatically shown via a display window 2 minutes later, enabling the measurement.

[0075]

Table 1

[0076] Referring to Table 1, for the nylon cords manufactured according to the examples, after manufacturing the green cords, the moisture content of the green cords is set within the optimal range by performing a drying process at the optimal drying temperature and drying duration. As a result, it can be seen that, compared with Comparative Example 1 where the drying process was not performed, while maintaining the same level of strength and elongation at break of the dipped cords, the LASE value is even higher and the shrinkage rate is even lower.

[0077] On the other hand, in the case of Comparative Example 2 where the drying process was performed on the green cords but the drying temperature was set even lower than the range of the present invention, the moisture content in the green cords increased, and finally the LASE value of the dipped cords became even higher, and there was a problem that the shrinkage rate decreased while showing physical properties at the same level as those of Comparative Example 1 where the drying process was performed. On the other hand, in the case of Comparative Example 3 where the drying temperature was set excessively high, it can be seen that drying was performed at a temperature higher than the melting point of the nylon cord, which caused carbonization and the like in the fibers, and finally the physical properties of the cord deteriorated.

[0078] In summary, it can be seen that the nylon cords manufactured in the examples have excellent tensile physical properties of the cords without changing processes such as increasing the draw ratio or the heat treatment temperature when manufacturing the cords as in the prior art by adjusting the moisture content of the green cords, and at the same time, the target elastic modulus is excellent.

[0079] The above description is only an illustrative explanation of the technical idea of the present invention, and those with ordinary knowledge in the technical field to which the present invention pertains should be able to make various modifications and deformations without departing from the essential characteristics of the present invention. The protection scope of the present invention should be analyzed according to the following claims, and all technical ideas within the equivalent scope should be construed as being included in the scope of rights of the present invention.

[0080] [Industrial Applicability] The present invention is an optimal invention capable of improving the elastic modulus of the finally manufactured tire cord by adjusting the moisture content of the green cord through a process of drying the nylon green cord.

Claims

1. A step of producing an undrawn yarn by melt spinning and cooling a polyamide polymer produced by condensation polymerization of hexamethylenediamine and adipic acid; A step of producing a nylon raw yarn by passing the undrawn yarn through three or more godet rollers for multi-stage drawing and winding; A step of producing a green cord by twisting the nylon raw yarn at 100 to 550 TPM; A step of drying the green cord; A step of producing a dipped cord by immersing the dried green cord in a dipping solution containing resorcinol-formaline-latex, followed by drying and heat treatment; The step of drying the green cord includes drying the green cord at a temperature of 150°C or higher for 100 seconds or more; A method for producing a nylon cord, wherein the moisture content of the dried green cord is 0.5 to 3.5%.

2. The method for producing a nylon cord according to claim 1, wherein the step of drying the green cord is characterized by drying at 150 to 240°C for 100 to 300 seconds.

Images