Hybrid cord and manufacturing method thereof

Abstract

The present invention provides a hybrid cord and a manufacturing method thereof, wherein non-uniformity caused by the difference in fineness between two different yarns is solved by twisting a first low-modulus yarn to reduce the difference in twist index between the first low-modulus yarn and a second high-modulus yarn and thereby achieve functional uniformity, and thus the hybrid cord is more balanced functionally, and has high strength, strong adhesion to rubber, and excellent fatigue resistance properties, thus making it possible to achieve performance improvement and weight reduction in a tire.

Description

Hybrid code and its manufacturing method

[0001] The present invention relates to a hybrid cord for reinforcing tires and a method for manufacturing the same, and more particularly, to a hybrid cord having a high strength utilization ratio and suitable for application to the cap ply of high-performance tires and electric vehicle tires, and a method for manufacturing the same.

[0002] As the performance of vehicles increases, the number of vehicles traveling at high speeds exceeding 120 km / h is increasing, and tire cords that can maintain tire handling stability and durability even during high-speed driving are required.

[0003] Tire cord is a fiber cord used as a tire reinforcement material. It is classified by its location and function. A tire consists of a carcass, which supports the entire tire, a belt, which secures the contact area and serves as a rim, and a cap ply, which prevents deformation of the belt. As vehicle speeds increase, the belt deforms, leading to problems such as reduced ride quality. Consequently, the importance of the cap ply, which prevents deformation of the belt, is increasing.

[0004] Nylon cord and nylon / aramid hybrid cord are commonly used as tire cords for cap plies. Compared to nylon cord, nylon / aramid hybrid cords incorporate aramid, which has a higher modulus than nylon, resulting in improved properties such as high strength and excellent fatigue resistance. However, due to the different fineness of the aramid and nylon yarns that make up the hybrid cord, when made into a balanced cord with the same twist count, the expected properties of the hybrid cord cannot be fully achieved, resulting in a lack of uniform properties and high fatigue resistance. This means that when an external force is applied, not all yarns act simultaneously, but certain yarns resist first, lowering the final properties. Therefore, to achieve high fatigue resistance and uniform properties, it is advantageous to create tire cords with an unbalanced structure, with different twist counts depending on the material properties. Conventional unbalanced hybrid cords are produced using ring twisters. However, these cords suffer from low strength utilization due to friction caused by the anti-ballooning ring and long yarn threads.

[0005] To solve these problems, a direct cabler that can increase the strength utilization rate of the tire cord must be used. However, since the upper and lower twists are performed simultaneously in a direct cabler, the number of twists in the lower twist of each ply cannot be different during twisting, which limits the ability to create a tire cord with an unbalanced configuration.

[0006] [Prior Art Literature]

[0007] [Patent Document]

[0008] (Patent Document 1) US 09653571 A

[0009] The present invention is intended to overcome the problems of the prior art described above, and one object of the present invention is to provide a hybrid cord that can achieve high performance of a tire by having not only high strength and high modulus but also excellent fatigue resistance properties.

[0010] Another object of the present invention is to provide a method for manufacturing a hybrid cord capable of realizing high performance of a tire by having high strength and excellent fatigue resistance properties.

[0011] One aspect of the present invention for solving the above-described problem is:

[0012] The present invention relates to a hybrid cord in which a first yarn having a low pretwisted modulus and a second yarn having a higher modulus than the first yarn that is not twisted are simultaneously twisted and overtwisted with each other, wherein a ratio (K1 / K2) of a first twist index (K1) calculated by the following equation 1 and a second twist index (K2) calculated by the following equation 2 is 0.94 to 1.24, and a hybrid cord having a strong utilization rate of 70% or more.

[0013] [Formula 1]

[0014] K1=(T1+T2) / 10 ×A 0.5

[0015] T1: Number of twists in the lower part of the first yarn

[0016] T2: Number of twists in the first yarn

[0017] A: Denier of the first yarn

[0018] [Formula 2]

[0019] K2=T3 / 10×B 0.5

[0020] T3: Number of twists in the lower part of the second yarn

[0021] B: Denier of the second yarn

[0022]

[0023] The number of twists in the first yarn's leading edge may be 3 to 25% of the number of twists in the second yarn's leading edge.

[0024] The twist count of the first yarn and the second yarn during the above-described lower and upper twists may be 200 to 500 TPM.

[0025] The first yarn may have a fineness of 800 to 1700 denier, and the second yarn may have a fineness of 1000 to 2000 denier.

[0026] The first yarn may be a nylon yarn, and the second yarn may be an aramid yarn.

[0027] Another aspect of the present invention for achieving the above-described purpose is:

[0028] The present invention relates to a tire comprising a pair of parallel bead cores, one or more radial carcass layers wound around the bead cores, a belt layer laminated on the outer circumferential side of the carcass layer, and a circumferential cap ply formed on the outer circumferential side of the belt layer, wherein the cap ply comprises the hybrid cord described above.

[0029] Another aspect of the present invention for achieving the above-described purpose is:

[0030] A step of preparing two or more types of yarns having different moduli, wherein the modulus of the first yarn is smaller than the modulus of the second yarn;

[0031] A step of twisting and drawing the first yarn;

[0032] A step of manufacturing a double-twisted yarn by simultaneously performing undertwisting and overtwisting on a first yarn with a twist and a second yarn without a twist; and

[0033] The present invention relates to a method for manufacturing a hybrid cord, comprising the steps of immersing the above-mentioned compound in an adhesive solution, drying, and heat-treating the same, and characterized in that the ratio (K1 / K2) of the first twist index (K1) calculated by the following equation 1 and the second twist index (K2) calculated by the following equation 2 is 0.94 to 1.24.

[0034] [Formula 1]

[0035] K1=(T1+T2) / 10 ХA 0.5

[0036] T1: Number of twists in the lower part of the first yarn

[0037] T2: Number of twists in the first yarn

[0038] A: Denier of the first yarn

[0039] [Formula 2]

[0040] K2=T3 / 10ХB 0.5

[0041] T3: Number of twists in the lower part of the second yarn

[0042] B: Denier of the second yarn

[0043]

[0044] In the present invention, the first yarn is twisted in a first twist direction, the first yarn is twisted in a second twist direction, and the second yarn is twisted in a third twist direction. The second twist direction and the third twist direction may be performed in the same or different directions as the first twist direction.

[0045] The above first yarn and second yarn are spun in a fourth twist direction, and the fourth twist direction can be performed in a direction opposite to the second twist direction and the third twist direction.

[0046] It is preferable that the twist count of the first yarn be 3 to 25% of the twist count of the second yarn.

[0047] The first yarn may be a nylon yarn, and the second yarn may be an aramid yarn.

[0048] According to the present invention, since the process of forming the first lower twisted yarn and the second lower twisted yarn (i.e., the lower twisting process) and the process of forming the double twisted yarn with the first lower twisted yarn and the second lower twisted yarn (i.e., the upper twisting process) are performed by a single twisting machine (e.g., a direct cabler), the productivity of the hybrid cord is improved and the manufacturing cost is reduced, while a hybrid cord with an unbalanced structure can be manufactured by a direct cabler, thereby improving the strength, adhesiveness, and high-strength utilization rate of the hybrid cord.

[0049] In the present invention, structural unevenness caused by the difference in fineness of two different yarns is resolved by pretwisting a first yarn having a low modulus, thereby reducing the difference in twist index between aramid yarn and nylon yarn, thereby obtaining a hybrid cord having higher strength and improved fatigue resistance that is more functionally balanced.

[0050] Figure 1 is a force-strain curve (SS curve) for the hybrid code obtained in Example 1 and Comparative Examples 1 and 2.

[0051] The present invention is described in more detail below.

[0052] The term "cord" in this specification may refer to a hybrid cord comprising two or more different types of fibers. The hybrid cord may refer to a dipped cord coated with a coating agent such as an adhesive.

[0053] In this specification, 'pretwist' means imparting a predetermined twist to the yarn before twisting and spinning to manufacture a hybrid cord.

[0054] In this specification, 'ply twist' means twisting yarn or filament in one direction, and 'ply yarn' can mean a single yarn, i.e., a single yarn, made by twisting yarn or filament in one direction. A first ply yarn is a yarn that is ply twisted with a first yarn that has been twisted, and a second ply yarn is a yarn that is ply twisted with a second yarn that has not been twisted.

[0055] In this specification, the 'number of twists of the first yarn' means the number of twists of the first yarn excluding the number of twists of the leading yarn.

[0056] In this specification, 'cable twist' means twisting the first and second lower yarns in one direction to create a double-twisted yarn (raw cord).

[0057] In this specification, the term 'plied yarn' means a yarn made by twisting two or more strands of plied yarn together in one direction, and is also called "raw cord".

[0058] In this specification, "cord" refers to a plied yarn containing an adhesive that can be directly applied to rubber products, also called a "dipped cord." Fabric containing an adhesive, obtained by weaving plied yarn into a fabric and then dipping the fabric in an adhesive solution, is also included in the term "cord."

[0059] In this specification, "twist number" means the number of twists per meter, and its unit may be TPM (Twist Per Meter). In the present invention, the twist number may be measured using a method specified in ASTM D-885, for example, using a D314 device manufactured by Zweigle.

[0060] One aspect of the present invention for solving the above-described problem is:

[0061] The present invention relates to a hybrid cord comprising two or more yarns having different moduli, wherein a first yarn having a lower modulus that is pretwisted and a second yarn having a higher modulus than the first yarn are simultaneously twisted and have an unbalanced structure.

[0062] The present invention overcomes the functional disadvantages caused by the difference in denier between two different yarns with different moduli by imparting a twist to the nylon yarn, thereby improving the strength, fatigue resistance, and adhesive strength of the cord. Furthermore, the present invention improves the strength utilization of the hybrid cord by pre-twisting (pre-twisting) the first yarn (e.g., nylon yarn) and then twisting it to create an unbalanced structure using a direct cabler capable of increasing the strength utilization.

[0063] In the present invention, the first yarn and the second yarn have different moduli, and the first yarn has a modulus lower than the modulus of the second yarn.

[0064] The first yarn having a low modulus may be a nylon yarn. The usable nylon filament may be one selected from the group consisting of conventional nylon 6, nylon 66, and nylon 6.10, nylon 5.6, and nylon 4.10, and nylon 66 is preferably used.

[0065] The second yarn having a relatively high modulus may be selected from the group consisting of aramid, aromatic polyamide, wholly aromatic polyester, and mixtures thereof. According to a preferred embodiment of the present invention, the second yarn is poly(p-phenylene terephthalamide). High-modulus aramid yarn is an advantageous material for suppressing the flat spot phenomenon that causes tire deformation because the modulus change is small at both room temperature and high temperature.

[0066] In one embodiment, the first yarn may be a nylon yarn having a fineness of 800 to 1700 denier, and the second yarn may be an aramid yarn having a fineness of 1000 to 2000 denier. For example, the fineness of the aramid yarn used in the twisting yarn may be 1000 denier, 1500 denier, or 2000 denier, and the fineness of the nylon yarn may be 840 denier, 1260 denier, or 1680 denier.

[0067] In one embodiment, the hybrid cord according to the present invention is a hybrid type of a first yarn and a second yarn, wherein a twisted first yarn and a non-twisted second yarn are simultaneously twisted by a single twisting machine (e.g., Direct Cabler) to form a first twisted yarn and a second twisted yarn, and almost simultaneously (i.e., continuously) the first twisted yarn and the second twisted yarn are spun together to form a plied yarn (raw cord).

[0068] In the present invention, the twist count refers to the twist count at a given stage, regardless of the twist direction. Since the first undertwisted yarn is a yarn that is undertwisted again after being first twisted, the twist counts of the first undertwisted yarn obtained at the undertwisting stage and the first undertwisted yarn are not the same depending on the twist direction. However, if we limit it to the undertwisting stage, the twist count of the first yarn and the twist count of the second yarn can be made the same.

[0069] The twist direction of the first yarn and the twist direction of the first and second lower yarns may be the same or different. The first lower yarn and the second lower yarn may have the same twist direction, and the twist direction may be opposite to the twist directions of the first and second lower yarns.

[0070] The first twist index (K1) of the first lower yarn is calculated by the following equation 1, and the second twist index (K2) of the second lower yarn is calculated by the following equation 2. The ratio of the first twist index (K1) to the second twist index (K2) (K1 / K2) can be within the range of 0.94 to 1.24. If the ratio of the first twist index (K1) to the second twist index (K2) (K1 / K2) is less than 0.94, a functional imbalance occurs in the cord, making it difficult to achieve the purpose of the present invention, and if the ratio of the first twist index (K1) to the second twist index (K2) (K1 / K2) exceeds 1.24, the degree of unevenness of the two yarns in the twisting stage may increase, which may deteriorate workability. In one embodiment, the first twist index (K1) calculated by the following Equation 1 of the first lower yarn and the second twist index (K2) calculated by the following Equation 2 of the second lower yarn may be 1070-1450, respectively.

[0071] [Formula 1]

[0072] K1=(T1+T2) / 10 ХA 0.5

[0073] T1: Number of twists in the lower part of the first yarn

[0074] T2: Number of twists in the first yarn

[0075] A: Denier of the first yarn

[0076] [Formula 2]

[0077] K2=T3 / 10 ХB 0.5

[0078] T3: Number of twists in the lower part of the second yarn

[0079] B: Denier of the second yarn

[0080] The twist count of the first yarn may be 3 to 25% of the twist count of the second yarn. The twist directions of the first and second yarns may be the same, but are not limited thereto, and may be different. For example, if a twist of 50 TPM is applied to the first yarn (e.g., nylon yarn) in the Z direction, and then the twisted nylon yarn is placed on the creel of a direct cabler and an aramid yarn is put into the POT and twisted at 300 TPM, a hybrid raw cord composed of nylon yarn and aramid yarn with different total twist counts of 300 TPM for the top twist, 300 TPM for the bottom twist aramid, and 350 TPM for the bottom twist nylon (the sum of the twist counts of the first twist and the twist counts of the bottom twist) can be manufactured.

[0081] For example, the first yarn may include nylon fibers (filaments) having a fineness of 800 to 1700 denier (de). For example, the lower limit of the fineness of the first yarn may be 800 denier or more, 900 denier or more, 1000 denier or more, 1050 denier or more, 1100 denier or more, 1150 denier or more, 1200 denier or more, 1250 denier or more, 1300 denier or more, 1350 denier or more, or 1400 denier or 1500 denier or more. And, the upper limit of the fineness of the first yarn can be, for example, 1700 denier or less, 1650 denier or less, 1600 denier or less, 1550 denier or less, 1500 denier or less, 1450 denier or less, 1400 denier or less, 1350 denier or less, 1300 denier or less, 1250 denier or less, 1200 denier or less, 1150 denier or less, 1100 denier or less, or 1050 denier or less, 1000 denier or less, or 900 denier or less. In a preferred embodiment, the fineness of the first yarn can be 840 denier, 1260 denier, or 1680 denier.

[0082] The second yarn may include fibers (filaments) having a fineness of 1000 to 2000 denier. For example, the lower limit of the fineness of the second yarn may be 1000 denier or more, 1100 denier or more, 1200 denier or more, 1300 denier or more, 1400 denier or more, 1450 denier or more, 1500 denier or more, 1550 denier or more, 1600 denier or more, or 1650 denier or more, 1700 denier or more, 1750 denier or more, 1800 denier or more, or 1900 denier or more. And, the upper limit of the fineness of the second yarn can be, for example, 2000 denier or less, 1900 denier or less, 1800 denier or less, 1700 denier or less, 1650 denier or less, 1600 denier or less, 1550 denier or less, 1500 denier or less, or 1450 denier or less. In a preferred embodiment, the fineness of the second yarn can be 1000 denier, 1500 denier, or 2000 denier.

[0083] According to the present invention, since the aramid yarn and the nylon yarn have substantially the same twist index and length within the final tire cord, the yarns exhibit similar behavior in terms of strength and fatigue performance.

[0084] Specifically, the twist number of the first filament yarn including the nylon yarn may be 200 to 500 TPM. According to the present invention, when performing the lower twist and upper twist for manufacturing the above-mentioned plied yarn (raw cord), the same twist number is applied within the range of 200 to 500 TPM. However, when performing the subsequent dipping, drying, and heat treatment processes for adhesive application sequentially, unintended untwist may occur, resulting in a difference of up to 15% compared to the initially set twist number in the lower twist and upper twist. In general, when the twist number of the filament yarn is high, the strength decreases but the fatigue performance increases. On the other hand, when the twist number of the filament yarn is low, the strength increases but the fatigue performance decreases.

[0085] In the present invention, the number of twists of the nylon yarn (excluding the number of twists of the lead yarn) and the number of twists of the aramid yarn are respectively 200 TPM or more, 210 TPM or more, 220 TPM or more, 230 TPM or more, 240 TPM or more, 250 TPM or more, 260 TPM or more, 270 TPM or more, 280 TPM or more, 290 TPM or more, 300 TPM or more, 310 TPM or more, 320 TPM or more, 330 TPM or more, 340 TPM or more, 350 TPM or more, 360 TPM or more, 370 TPM or more, 380 TPM or more, 390 TPM or more, 400 TPM or more, 410 TPM or more, 420 TPM or more, 430 TPM or more, 440 TPM or more, 450 TPM or more, 460 TPM It can be 470 TPM or more, 480 TPM or more, or 490 TPM or more.

[0086] And, the upper limit of the twist number of the lower yarn of the nylon yarn (excluding the twist number of the lead yarn) and the aramid yarn is, for example, 500 TPM or less, 490 TPM or less, 480 TPM or less, 470 TPM or less, 460 TPM or less, 450 TPM or less, 440 TPM or less, 430 TPM or less, 420 TPM or less, 410 TPM or less, 400 TPM or less, 390 TPM or less, 380 TPM or less, 370 TPM or less, 360 TPM or less, 350 TPM or less, 340 TPM or less, 330 TPM or less, 320 TPM or less, 310 TPM or less, 300 TPM or less, 290 TPM or less, 280 TPM or less, 270 TPM or less, 260 TPM or 250 TPM or less, 240 It can be less than TPM, or less than 230 TPM.

[0087] As described above, the hybrid cord of the present invention includes a first undertwisted yarn and a second undertwisted yarn that are twisted together and have a predetermined number of twists, and is formed by twisting the first undertwisted yarn and the second undertwisted yarn together. At this time, since the first yarn for forming the first undertwisted yarn and the second yarn for forming the second undertwisted yarn are simultaneously undertwisted by a direct cabler to form the first undertwisted yarn and the second undertwisted yarn, the twist direction of the first undertwisted yarn (the second twist direction) and the twist direction of the second undertwisted yarn (the third twist direction) may be the same. In addition, when a direct cabler twisting machine (for example, a direct cabler) is used, the first twist may be performed simultaneously with the second twist following the first twist, and the twist direction of the first twist (i.e., the fourth twist direction) may be opposite to the second twist direction (or the third twist direction).

[0088] According to one embodiment of the present invention, a hybrid cord may further include an adhesive coated on the nylon under-twisted yarn and the aramid under-twisted yarn to enhance adhesion to the tire. This coating layer may be formed on at least a portion of the above-described under-twisted yarn. The method for forming the coating layer is not particularly limited, and for example, the coating layer may be formed using a known dipping or spraying method.

[0089] The coating layer may be formed from an adhesive composition. For example, the coating layer may include or be formed from a resorcinol-formaldehyde-latex (RFL) adhesive, an epoxy adhesive, or a urethane adhesive.

[0090] The hybrid cord of the present invention has a dry heat shrinkage rate of 1.0 to 3.0%. If the dry heat shrinkage rate exceeds the above range, the cord may shrink significantly due to an increase in the temperature inside the tire during high-speed driving, thereby reducing the dimensional stability of the cord and degrading tire performance.

[0091] The dry heat shrinkage rate of the hybrid cord of the present invention may be 1.0% or more. For example, the dry heat shrinkage rate may be 1.1% or more, 1.2% or more, 1.3% or more, 1.4% or more, 1.5% or more, 1.6% or more, 1.7% or more, 1.8% or more, 1.9% or more, or 2.0% or more. The dry heat shrinkage rate of the hybrid cord may be 3.0% or less. For example, the dry heat shrinkage rate may be 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, or 2.2% or less.

[0092] The strength of the hybrid cord of the present invention may be 35 kgf or more. Specifically, the strength may be, for example, 35 kgf or more, 36 kgf or more, 37 kgf or more, 38 kgf or more, 39 kgf or more, or 40 kgf or more.

[0093] In the present invention, the strength utilization ratio of the hybrid plied yarn (raw cord) is 70% or more, and more preferably 75% or more. The strength utilization ratio of the hybrid cord may be 70% or more. For example, the strength utilization ratio may be 71.0% or more, 72.0% or more, 73.0% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, or 80% or more.

[0094] Below, the manufacturing method of the hybrid code of the present invention is described in more detail.

[0095] When manufacturing a hybrid cord according to the present invention, two or more types of yarns having different moduli, where the modulus of the first yarn is lower than that of the second yarn, are prepared. Next, the first yarn is twisted and spun, and then the twisted first yarn and the untwisted second yarn are simultaneously subjected to undertwisting and top twisting to manufacture a plied yarn. Optionally, the step of immersing the plied yarn in an adhesive solution and performing drying and heat treatment may be further included.

[0096] In the method of the present invention, the ratio (K1 / K2) of the first twist index (K1) calculated by the following equation 1 and the second twist index (K2) calculated by the following equation 2 can be 0.94 to 1.24.

[0097] [Formula 1]

[0098] K1=(T1+T2) / 10 ХA 0.5

[0099] T1: Number of twists in the lower part of the first yarn

[0100] T2: Number of twists in the first yarn

[0101] A: Denier of the first yarn

[0102] [Formula 2]

[0103] K2=T3 / 10ХB 0.5

[0104] T3: Number of twists in the lower part of the second yarn

[0105] B: Denier of the second yarn

[0106] The first yarn may be a nylon yarn, and the second yarn may be an aramid yarn.

[0107] When a low-modulus first yarn (e.g., nylon yarn) is twisted, the twist direction can be in the S direction or the Z direction. The twist number of the first yarn can be 3 to 25% of the twist number of the second lower yarn (e.g., aramid yarn).

[0108] For example, first, a first yarn having a low modulus is twisted at a level of 3 to 25% of the twist number of the second lower twisted yarn. Next, the first yarn having a denier of 800 to 1700 and the second yarn having a denier of 1000 to 2000 are fed into a cable cord twisting machine (Direct Cabler) that performs both lower twisting and upper twisting. In the cable cord twisting machine, the step of lower twisting the first yarn to obtain a first lower twisted yarn and the step of lower twisting the second yarn to obtain a second lower twisted yarn are performed simultaneously, and the step of upper twisting the first lower twisted yarn and the second lower twisted yarn together to form a plied yarn is performed almost simultaneously (continuously) with the lower twisting steps of the first and second yarns. The twist direction of the upper twist is opposite to the twist direction of the lower twist, and when the lower twist and upper twist are performed simultaneously, the same twist number can be applied within the range of 200 to 500 TPM.

[0109] In the present invention, after manufacturing a plied yarn (raw cord), a hybrid cord can be manufactured by further performing steps of immersing the plied yarn in an adhesive solution, followed by drying and heat treatment. The hybrid cord (i.e., deep cord) of the present invention can be manufactured by immersing the plied yarn in an adhesive solution, drying the plied yarn impregnated with the adhesive solution, and then heat-treating the dried plied yarn. At this time, an RFL solution (Resorcinol Formaldehyde Latex) or an epoxy-based adhesive composition solution can be used as the adhesive solution.

[0110] The temperature and time of the above drying process may vary depending on the composition of the adhesive solution, but the drying process is typically performed at 70 to 200°C for 30 to 120 seconds. The heat treatment process may be performed at 200 to 250°C for 30 to 120 seconds. Through the above processes, the adhesive component of the adhesive solution is coated on the surface of the plywood, thereby increasing the adhesion between the hybrid cord of the present invention and other components of the tire.

[0111] Meanwhile, although the twisting machine is set to perform the lower and upper twists with the same number of twists, the twisting phenomenon may occur during the process of the double-twisted yarn manufactured by the twisting machine being immersed in the adhesive solution and then dried and heat-treated. To minimize this twisting phenomenon and prevent excessive shrinkage of the nylon yarn, the tension applied to the double-twisted yarn during the sequential immersion, drying, and heat-treatment steps is preferably 0.4 kg / cord or more.

[0112] Another aspect of the present invention relates to a tire comprising the hybrid cord (deep cord) described above. For example, the hybrid cord of the present invention can be used to manufacture a cap ply layer of a tire.

[0113] Hereinafter, the present invention will be described in more detail with examples. However, the following examples are provided solely to aid understanding of the present invention and do not limit the scope of the present invention.

[0114]

[0115] Example

[0116] Example 1

[0117] Before performing the down-twist and up-twist of the hybrid cord, the 1260d nylon yarn was pretwisted in the Z direction at 30 TPM. Then, the 1500d aramid yarn and the 1260d pretwisted nylon yarn were fed into a cable cord twisting machine (Direct Cabler from Allma) and down-twisted and up-twisted simultaneously to produce a plied yarn. At this time, the down-twisting direction of the nylon yarn and the aramid yarn was the same in the Z direction, and the number of twists was the same at 300 TPM, while the up-twisting direction was in the S direction, and the number of twists was 300 TPM.

[0118] Next, the above-mentioned filament was immersed in a resorcinol-formaldehyde-latex (RFL) adhesive solution. The filament impregnated with the RFL adhesive solution was dried at 160°C for 100 seconds and heat-treated at 240°C for 100 seconds to produce a hybrid cord.

[0119]

[0120] Examples 2-3

[0121] A hybrid cord was manufactured in the same manner as in Example 1, except that the nylon yarn was pre-twisted (pre-twisted) before performing the lower and upper twists, and the twist count of the pre-twist (10 TPM, 50 TPM), the lower twist count of the nylon lower twist yarn, or the ratio of the twist index of the aramid yarn to the twist index of the nylon yarn were changed as shown in Table 1 below.

[0122]

[0123] Comparative Example 1

[0124] A hybrid cord was manufactured using the same method as Example 1, except that 1260d nylon yarn without pre-weaving was used.

[0125]

[0126] Comparative Example 2

[0127] A hybrid cord was manufactured in the same manner as in Example 1, except that 1500d aramid yarn and 1260d nylon yarn were fed into a ring twister and subjected to lower twisting (300 TPM / 330 TPM) and then to upper twisting (300 TPM).

[0128]

[0129] Comparative Example 3

[0130] A hybrid cord was manufactured in the same manner as Example 1, except that the nylon yarn was twisted in advance (pre-twisted) before performing the pre-twisting and the pre-twisting, and the number of twists in the pre-twisting was set to 110 TPM.

[0131]

[0132] Exam example

[0133] In order to evaluate whether the properties of the hybrid codes obtained by the above examples and comparative examples are suitable for cap fly use, the strength, fatigue resistance and strength utilization of the codes were measured by the following methods, and the results are shown in Table 1 below.

[0134] * Strength (kgf): Ten 250 mm-long samples were prepared for each hybrid code. Next, the strength of each sample was measured using an Instron testing machine (Instron Engineering Corp., Canton, Mass) at a tensile speed of 300 m / min, according to the ASTM D885 / D885M-10a (2014) test method (stored in a constant temperature and humidity chamber at 25°C and 65%RH for 24 hours). The strength was calculated as the average of the strengths of the 10 samples.

[0135] * Fatigue Resistance (%): The residual strength was measured and compared after fatigue testing using a Belt Fatigue Tester, which is commonly used for tire cord fatigue testing. The fatigue test conditions were RT, 80 kg load, and 37,500 rotations. After the fatigue test, the rubber and cord were separated and the residual strength was measured. The residual strength was measured using a conventional tensile strength tester.

[0136] * High-power utilization rate (%):

[0137] - Strength utilization rate of the plied yarn (raw cord) (%) = Strength of raw cord / (Strength of the first yarn + Strength of the second yarn) Х 100

[0138] - Strength utilization rate of code (deep code) (%) = Strength of deep code / (Strength of first yarn + Strength of second yarn) Х 100

[0139] Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Example 3 Twisted Cable Cord Twisted Ring Twisted Cable Cord Twisted Cable Cord Twisted Cable Cord Twisted Cable Cord Twisted Aramid Yarn Tenacity (kgf) 37.5 37.5 37.5 37.5 37.5 37.5 Nylon Yarn Tenacity (kgf) 12.5 12.5 12.5 12.5 12.5 12.5 Nylon Pre-Tension (TPM) 0 1 1 0 3 0 1 0 5 0 Nylon Lower Tension (TPM) 300 330 300 300 300 300 Aramid Lower Tension (TPM) 300 300 300 300 300 Top Tension (TPM) 300 300 300 300 300 Nylon Twist Index (K1) 106511711455117111001242 Aramid Twist Index (K2) 116211621162116211621162 Twist Index Ratio (K1 / K2) 0.921.011.251.010.951.07 Raw Cord Strength (kgf) 42.038.741.342.642.342.1 Raw Cord Strength Utilization Rate (%) 84.077.482.685.284.684.2 Deep Cord Strength (kgf) 37.133.736.338.137.837.3 Deep Cord Strength Utilization Rate (%) 74.267.472.676.275.674.6 Fatigue Resistance (%)889186949290

[0140] As shown in the test results in Table 1 above, in the case of the present invention in which nylon yarn is twisted to have a certain range of twists, and the twisted nylon yarn and the non-twisted aramid yarn are simultaneously twisted and made into a raw cord using a direct cabler (Examples 1-4), it can be confirmed that the strength, strength utilization rate, and fatigue resistance of the hybrid cord are superior to those of the comparative examples. In particular, compared to Comparative Example 1 in which the nylon yarn is not twisted, the examples have superior fatigue resistance, and compared to Comparative Example 2 in which a ring twister is used instead of a cable cord twister (direct cabler), the examples have superior strength utilization rate.

[0141]

[0142] Test Example 2

[0143] The 205 / 65 R15 V tires manufactured by applying the hybrid code manufactured in the above examples and comparative examples as a cap ply were mounted on a 2000 cc passenger car. The handling stability and ride comfort were evaluated on a 5-point scale out of 100 by an experienced driver driving the test course, and the results are shown in Table 2 below. The durability was measured according to the P-metric tire endurance test method of FMVSS 109. When the temperature was 38℃, the tire was driven at 85, 90, and 100% of the tire's marked load, and the driving speed was 80 km / h for a total of 34 hours, and no traces of bead separation, cord cuts, or belt separation were found in any part of the tread, sidewall, carcass cord, inner liner, or bead, the tire was judged to be OK. And, uniformity was tested using a high-speed uniformity tester (HISUM (HOFMANN RGM-LT3): high speed uniformity machine) at 300 to 1300 (rpm) while maintaining a constant air pressure (30 psi).

[0144] Tire Comparison Example 1 Comparison Example 2 Comparison Example 3 Example 1 Example 2 Example 3 Ride comfort 90909010010095 Steering stability 90858510010095 Durability Pass Fail Pass Pass Pass Pass Pass Uniformity 9080951009895

[0145] As confirmed through the results of Table 2 above, the tires of Examples 1 to 3, which applied the hybrid code according to the present invention to the cap fly, were superior in terms of ride comfort, durability, and steering stability compared to Comparative Examples 1 to 3, which applied the conventional hybrid code, and it can be seen that the uniformity of the tire was also improved.

Claims

1. A hybrid cord in which a first yarn having a low modulus and a second yarn having a higher modulus than the first yarn that is not twisted are twisted together by being twisted simultaneously, wherein the ratio (K1 / K2) of the first twist index (K1) calculated by the following equation 1 and the second twist index (K2) calculated by the following equation 2 is 0.94 to 1.24, and the hybrid cord is characterized in that the strength utilization rate of the hybrid cord is 70% or more. [Formula 1] K1=(T1+T2) / 10 ×A 0.5 T1: Number of twists in the lower part of the first yarn T2: Number of twists in the first yarn A: Denier of the first yarn [Formula 2] K2=T3 / 10×B 0.5 T3: Number of twists in the lower part of the second yarn B: Denier of the second yarn 2. A hybrid cord characterized in that the twist number of the first yarn in the first paragraph is 3 to 25% of the twist number of the second yarn in the second paragraph.

3. A hybrid cord according to claim 1, characterized in that the number of twists during the first and second yarns is 200 to 500 TPM.

4. A hybrid cord characterized in that, in the first paragraph, the first yarn has a fineness of 800 to 1700 denier, and the second yarn has a fineness of 1000 to 2000 denier.

5. A hybrid cord according to claim 1, characterized in that the first yarn is a nylon yarn and the second yarn is an aramid yarn.

6. A tire comprising a pair of parallel bead cores, one or more radial carcass layers wound around the bead cores, a belt layer laminated on the outer circumference side of the carcass layer, and a circumferential cap ply formed on the outer circumference side of the belt layer, wherein the cap ply comprises a hybrid cord according to any one of claims 1 to 5.

7. A step of preparing two or more types of yarns with different moduli, wherein the modulus of the first yarn is smaller than the modulus of the second yarn; A step of twisting and drawing the first yarn; A step of manufacturing a double-twisted yarn by simultaneously performing undertwisting and overtwisting on a first yarn with a twist and a second yarn without a twist; and A method for manufacturing a hybrid cord, comprising the steps of immersing the above-mentioned compound in an adhesive solution, drying, and heat-treating the same, wherein the ratio (K1 / K2) of the first twist index (K1) calculated by the following formula 1 and the second twist index (K2) calculated by the following formula 2 is 0.94 to 1.24: [Formula 1] K1=(T1+T2) / 10 XA 0.5 T1: Number of twists in the lower part of the first yarn T2: Number of twists in the first yarn A: Denier of the first yarn [Formula 2] K2=T3 / 10XB 0.5 T3: Number of twists in the lower part of the second yarn B: Denier of the second yarn 8. A method for manufacturing a hybrid cord, characterized in that in the 7th paragraph, the first yarn's leading edge is performed in a first twist direction, the first yarn's lower edge is performed in a second twist direction, the second yarn's lower edge is performed in a third twist direction, and the second twist direction and the third twist direction are performed in the same or different directions as the first twist direction.

9. In the 8th paragraph, the first yarn and the second yarn are twisted in the fourth twist direction, A method for manufacturing a hybrid cord, characterized in that the fourth twisting direction is performed in the opposite direction to the second twisting direction and the third twisting direction.

10. A method for manufacturing a hybrid cord, characterized in that in the 8th paragraph, the twist number of the first yarn is 3 to 25% of the twist number of the second yarn.

11. A method for manufacturing a hybrid cord, characterized in that in paragraph 8, the first yarn is a nylon yarn and the second yarn is an aramid yarn.

Images