KR20180000526A - Hybrid cord and Tire comprising hybrid cord - Google Patents

Abstract

The present invention provides a hybrid cord and a tire comprising the same. The hybrid cord includes a first primary twisted yarn and a second primary twisted yarn which are simultaneously twisted, in which the hybrid cord has an elastic modulus of 40-110g/D in an elongation region of 2-4%, and a ratio of an elastic modulus at a 4% elongation with respect to an elastic modulus at a 2% elongation is 1.0-4.0. An object of the present invention is to provide a hybrid cord having new physical properties.

Description

TECHNICAL FIELD [0001] The present invention relates to a hybrid cord and a tire including the same,

A hybrid code and a tire including the same.

As vehicles become more sophisticated, the number of vehicles traveling at a high speed exceeding 120 km / h is increasing, and a tire cord capable of maintaining the steering stability and durability of the tire at high speeds is required.

The tire cord is divided into a carcass portion that supports the tire as a whole, a belt portion that supports the load at the time of high-speed traveling, and a cap fly portion that prevents deformation of the belt portion. There is a problem that the belt portion of the tire is deformed and the ride feeling is lowered as the running speed of the automobile increases, and the importance of the cap fly for preventing deformation of the belt portion is increasing.

Nylon and aramid are mainly used as the material of the cap-fly tire cord (refer to Korean Patent Laid-Open Publication No. 2009-0164609)

Nylon is easy to mold, low price compared to other materials, excellent adhesion and endothelial properties, so it is applied to most tires. However, since nylon has a low modulus and a large change in shape due to temperature change, the stability and durability of the tire may be deteriorated due to high tire growth rate due to heat and centrifugal force at high speed.

The aramid has a high modulus, and modulus change at room temperature and high temperature is small, thus improving steering stability at high speeds. However, the aramid has poor moldability due to high modulus, poor appearance of the tire, low elongation at break, and low endothelial property and durability. Also, the feeling of ride is reduced.

One aspect is to provide a hybrid code of new properties.

Another aspect is to provide a tire comprising a hybrid code.

According to one aspect,

And a first underside yarn and a second underside yarn simultaneously stacked,

The elastic modulus is 40 g / d to 110 g / d in the elongation period of 2% to 4%

A ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation is 1.00 to 1.40.

According to another aspect,

There is provided a tire having a cap ply including the above-described hybrid cord.

According to one aspect, the steering stability and high-speed durability of the tire can be improved by including the hybrid cord having a limited elastic modulus.

1 is a view schematically showing the structure of a tire according to one embodiment.

A tire having a cap ply including a hybrid code and a hybrid code will be described in more detail below in an exemplary embodiment.

The inventive concepts disclosed herein are capable of various modifications and various implementations, and specific implementations are described in detail in the detailed description and, where necessary, specific implementations are illustrated in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS The effect and features of the inventive concepts herein, and how to accomplish them, will become apparent with reference to the embodiments described in detail below with reference to the drawings. However, the inventive concept of the present invention is not limited to the embodiments described below, but may be implemented in various forms.

If one embodiment is otherwise feasible, the particular process sequence may be performed differently from the sequence described. For example, two processes that are described in succession may be performed substantially concurrently, and may be performed in the reverse order of the order described.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. .

In the drawings, components may be exaggerated or reduced in size for convenience of explanation. For example, the sizes and thicknesses of the individual components shown in the drawings are arbitrarily shown for convenience of explanation, and therefore, the inventive concepts disclosed in this specification are not necessarily limited to those shown in the drawings.

In this specification, terms such as " first ", "second ", and the like are used for the purpose of distinguishing one element from another element.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

The use of terms such as " comprises "or" having " in this specification is intended to mean that a feature or element described in the specification is present and does not preclude the possibility that one or more other features or components may be added .

In the present specification, the term " primary twisted yarn "is a single yarn formed by twisting one filament yarn in one direction.

As used herein, the term " plied yarn " means a yarn formed by twisting together two or more strands of yarn in either direction, otherwise it is referred to as a " raw cord ".

As used herein, the term " tire cord "includes not only the" cord "but also a" dip cord ", which means a composite yarn containing an adhesive so that it can be directly applied to a rubber product.

In the present specification, the term "twist number" means the number of twists per meter, and the unit is a twist per meter (TPM).

The hybrid cord according to an embodiment includes first and second lower strands that are simultaneously stretched, having an elastic modulus of 40 g / d to 110 g / d at a stretch interval of 2% to 4%, a 2% elongation The ratio of the modulus of elasticity at the 4% elongation to the modulus of elasticity in the range of 1.00 to 1.40. When the hybrid code satisfies the above conditions, the steering stability, the high-speed running durability and the flat spot of the tire including the hybrid code are improved and the rolling resistance is reduced, thereby improving the tire performance as a whole.

For example, the elastic modulus can be 40 g / d to 100 g / d in the elongation period of 2% to 4% in the hybrid cord. For example, the modulus of elasticity may range from 40 g / d to 90 g / d in the elongation period of 2% to 4% in the hybrid cord. For example, the modulus of elasticity may be 40 g / d to 80 g / d in the elongation period of 2% to 4% in the hybrid cord. For example, the modulus of elasticity may be from 40 g / d to 70 g / d in the elongation period of 2% to 4% in the hybrid cord. The tire performance can be further improved in the elastic modulus range.

For example, the ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation in the hybrid cord may be between 1.00 and 1.40. For example, the ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation in the hybrid cord may be from 1.00 to 1.30. For example, the ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation in the hybrid cord may be between 1.00 and 1.20. For example, the ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation in the hybrid cord may be between 1.00 and 1.10. The tire performance can be further improved in the elastic modulus ratio range.

If the elastic modulus is less than 40 g / d in the elongation period of 2% to 4% of the hybrid cord, the modulus of elasticity is too low to suppress the growth of the tire at high speed. If the elastic modulus exceeds 110 g / d in the elongation period of 2% to 4% of the hybrid cord, the modulus of elasticity is excessively high, so that the growth and deformation of the tire side portion at the time of high-speed traveling increase and the balance of the tire decreases, The resistance may increase and the flat spot may deteriorate.

When the ratio of the elastic modulus at the 4% elongation to the elastic modulus at the 2% elongation in the hybrid cord is less than 1.0, it may be difficult to suppress the growth of the tire at high speed. When the ratio of the elastic modulus at the 4% elongation to the elastic modulus at the 2% elongation in the hybrid cord is too high, the elastic modulus is excessively high, so that the growth and deformation of the tire side portion at the time of high-speed driving increase, and the balance of the tire decreases. As a result, And flat spots may be degraded.

Also, the hybrid cord may have a ratio of strength at 4% elongation to a stress at 2% elongation of 1.6 to 2.4. For example, the hybrid cord may have a ratio of strength at 4% elongation to a stress at 2% elongation of 1.7 to 2.3. The hybrid cord may have a ratio of strength at 4% elongation to a stress at 2% elongation of 1.8 to 2.2. The hybrid cord may have a ratio of strength at 4% elongation to a stress at 2% elongation of 1.9 to 2.2. The performance of the tire can be further improved by the hybrid cord having the intensity ratio within the above range.

In the hybrid cord, the first underfire yarn is a yarn having a high elastic modulus and the second yarn is a low elastic modulus yarn. Since the hybrid cord includes both the high modulus low modulus and the low modulus low modulus, the low modulus low modulus is applied to the low modulus low modulus to maintain the ride feeling unchanged and reduce the traveling noise. In the large deformation, the high elastic modulus underlay is applied to suppress the expansion of the tire, thereby improving durability and steering stability.

The high modulus of elasticity of the underlayers is lower than that of polyketone, aramid, poly (p-phenylene-2,6-benzobisoxazole) (PBO) , Carbon fiber underfire yarn, glass fiber underfire yarn, and the like, but not always limited thereto, and any material that can be used in the art as a high elastic modulus undergarment is all possible.

The low modulus low modulus can be a nylon lower modulus but is not necessarily limited thereto and can be used as low modulus low modulus in the art.

The hybrid cord may additionally include a moderate modulus yarn as the third yarn yarn in addition to the high modulus yarn and the low modulus yarn yarn. Modulus of elasticity modulus The modulus of elasticity is lower than the modulus of elasticity, and the modulus of elasticity is lower than that of modulus of elasticity.

The modulus of elasticity modulus may be, but is not necessarily limited to, polyester undercoat, polyvinyl alcohol (PVA) undercoat, rayon undercoat, lyocell undercoat, polyethylene naphthalate (PEN) It is possible to use it as long as it can be used as a moderate modulus low modulus.

The performance of the tire can further be improved by the hybrid code additionally including the third underside. For example, in the case where the hybrid cord additionally includes a low elastic modulus yarn in addition to a high elastic modulus yarn and a low elastic modulus yarn, the low elastic modulus primary yarn is mainly stressed at low speed driving, Stress is applied, and the modulus of elastic modulus is mainly stressed at medium speed. Therefore, when the vehicle suddenly accelerates from low speed to high speed, it is possible to compensate for a decrease in handling performance in a medium speed range due to sudden stress switching.

For example, the hybrid cord may comprise a first undersurface, a second undersurface, and a third undersurface staked concurrently and having an elastic modulus in the range of 2% to 4% in the range of 50 g / d to 130 g / d , And the ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation may be 1.10 to 1.50.

The ratio of the strength at 4% elongation to the stress at 2% elongation of the first lower strand in the hybrid cord is 1.5 to 3.5 and the ratio of the strength at 4% elongation to the strength at 2% The ratio of strength can be 0.5 to 2.5.

The performance of a tire with a cap ply including a hybrid cord can be improved by the fact that the strength ratio of the first underfill in the hybrid cord is in the range of 1.5 to 3.5 and the strength ratio of the second underfill is in the range of 0.5 to 2.5.

When the strength ratio of the first underlayer is less than 1.5, the effect of expressing the performance of the high modulus cord is low and it may be difficult to suppress the growth of the tire at high speed. If the strength ratio is more than 3.5, The tire is not inflated and the appearance of the inner liner part of the tire may become uneven. have.

If the strength ratio of the second under-warp yarn is less than 0.5, the difference in elastic modulus between the first under-strand yarn and the first under-strand yarn becomes large, so that the first under-strand is subjected to stress first during tire forming and vulcanization, resulting in defective tire appearance during tire production, If the strength ratio is more than 2.5, the modulus of elasticity of the hybrid cord becomes excessively high, which may also cause a bad appearance in tire manufacture.

The strength ratio of the first lower warp yarn may be higher than that of the second lower warp yarn. Since the strength ratio on the first lower side is higher than that on the second lower side, the second lower side warp is first subjected to stress during tire forming and vulcanization, so that the cap ply including the hybrid cord can be appropriately expanded. In addition, when the vehicle travels at a high speed, the first undercarriage is mainly subjected to stress, so that the growth of the tire can be suppressed and the high-speed driving performance can be improved.

For example, in the hybrid code, the first underframe may be under the aramid underlay and the second underfill may be under the nylon underlay.

Nylon contains an amide group having strong polarity in the main chain and has a stereoregularity and symmetry, and is crystalline. The nylon may be, for example, conventional nylon 6, nylon 66, or nylon 6.10. In particular, nylon may be nylon 66.

The nylon yarn used in the hybrid cord is not particularly limited, but may have a linear density of 500 to 2000 denier (D), a tensile strength of 7 g / d or more, and a cut elongation of 15% or more. If the tensile strength of the lower nylon yarn is less than 7 g / d, the movement of the belt may not be sufficiently prevented when the vehicle is traveling. If the cut elongation of the nylon filament yarn is less than 15%, the endothelial characteristics of the tire cord may be poor.

The aramid contains a phenyl ring in addition to the amide group in the main chain and has a modulus of 10 times or more higher than that of nylon. The aramid has a para-form (p-) and a meta-form (m-) depending on the linkage state of the phenyl ring. For example, the aramid may be a poly (p-phenylene terephthalamide) phenylene terephthalate).

≪ Formula 1 >

In the above formula, n is determined depending on the molecular weight of the aramid, and is not particularly limited.

The aramid underlayer may have a linear density of from 400 to 3000 D, a tensile strength of at least 18 g / d, and a cut elongation of at least 4%. If the tensile strength of the aramid lower yarn is less than 18 g / d, the low strength of the lower nylon yarn can not be compensated sufficiently, which may lead to tire deformation at high speed.

In the hybrid cord, the weight ratio of the first and second lower strands may be 50:50 to 70:30. The running performance of the tire having the cap ply including the hybrid code in the weight ratio range can be improved.

The linear density of the hybrid code may be between 1700D and 5000D. For example, the linear density of the hybrid code may be between 1700D and 4000D. For example, the linear density of the hybrid code may be between 1700D and 3000D. For example, the linear density of the hybrid code may be between 1700D and 2000D. For example, the linear density of the hybrid code may be between 1700D and 1900D. The running performance of the tire having the cap ply including the hybrid code in the linear density range of the hybrid code can be improved.

For example, the hybrid cord may include concurrent polyketone bottom yarns and nylon 66 bottom yarns.

For example, the hybrid cord may include a concurrently laminated aramid yarn, a nylon 66 laminated yarn, and a polyester laminated yarn. For example, the hybrid cord may include concurrent polyketone bottom yarns, nylon 66 bottom yarns, and polyester bottom yarns. For example, the hybrid cord may include a concurrently laminated aramid yarn, a nylon 66 yarn, and a rayon bottom yarn. For example, the hybrid cord may include concurrent polyketone bottom yarns, nylon 66 bottom yarns, and rayon bottom yarns.

In the hybrid cord, the number of twists of the first lower warp yarn may be smaller than the number of twists of the second lower warp yarn. The lowering of the strength of the first lower warp yarn can be suppressed by the fact that the twist number of the first lower warp yarn is smaller than the twist number of the second lower warp yarn. That is, since the first lower back yarn maintains a high strength, the deformation of the tire can be effectively suppressed at the time of high-speed traveling.

For example, in a hybrid cord, the twist of the first primary sheath may be 97% to 99.9% of the twist of the second secondary sheath. That is, the number of twists of the first lower warp yarn may be 970 to 999 with respect to 1000 twists of the second lower warp yarn. For example, in a hybrid cord, the twist of the first primary sheath may be 98% to 99.9% of the twist of the second secondary sheath. In the hybrid cord, the number of twists of the first backing yarn may be 99% to 99.9% of the number of twists of the second backing yarn. It is possible to more effectively suppress deformation of the tire at the time of high-speed high-speed running in the twist number range. If the twist number of the first lower twist yarn is less than 97% of the twist number of the second lower twist yarn, the strength of the hybrid cord excessively increases, resulting in incomplete expansion of the tire during tire formation, resulting in appearance failure. If the twist angle of the first lower twist yarn is 99.9% or more of the twist angle of the second lower twist yarn, the strength of the first lower twist yarn is lowered, and the effect of suppressing tire deformation at high speed traveling can be reduced.

The twist direction of the first lower warp yarn and the twist direction of the second lower warp yarn in the hybrid cord may be equal to each other. The lowering of the tensile strength can be reduced and the fatigue performance can be improved by lowering the first and second lower warp yarns in the same direction.

The twist direction in which the first and second lower strands are superimposed on each other in the hybrid cord may be different from the twist direction of the first down yarn and the second lower twist yarn. That is, since the direction in which the first lower and the second lower strands are stacked together is opposite to the lower direction of the first lower strand and the second lower strand, the filaments of the first lower strand and the second lower strand are arranged in the direction in which the hybrid cord is stretched The tensile strength can be maximized.

According to another embodiment, the tire comprises a cap ply comprising the hybrid code described above. The provision of the cap ply including the hybrid cord of the tire improves the steering stability of the tire, the high-speed running durability, and the flat spot and the rolling resistance is reduced, thereby improving the tire performance as a whole.

Referring to FIG. 1, a tire 10 includes a tread portion 100, a sidewall portion 200, and a bead portion 300.

The tread portion 100 is a portion in contact with the ground in a sectional view, and serves to protect the tire from impacts and trauma from road surfaces and the like. A plurality of blocks partitioned by grooves may be formed on the surface of the tread portion in order to drain the tire.

The sidewall 200 and the bead 300 are sequentially positioned on both sides of the tread portion 100 along the width direction of the tire.

The sidewall 200 is a portion extending from both ends of the tread portion 100 to form a side surface of the tire. The sidewall 200 abuts against the carcass layer 400 located on the inner side, withstanding repeated shrinkage and expansion during traveling. .

The bead portion 300 is provided at both ends of the sidewall 200 to surround the end portion of the cord paper. The bead portion 300 includes a bead core 500 including a ring-shaped steel wire rod.

A carcass layer 400 is positioned between the pair of right and left bead parts 300 and is joined to a tire rubber sheet inside the tire to form a skeleton of the tire. The carcass layer 400 is bonded to the bead core 500 ) From the inside of the tire to the outside.

An inner liner (not shown) may be positioned on one inner surface of the carcass layer 400 to prevent the air inside the tire from escaping to the outside.

The belt layer 600 may be positioned on the outer surface of the carcass layer 400 located in the tread portion 100 as a reinforcing layer that enhances the elasticity of the tread and provides steering and stability.

A cap ply 800 including a hybrid cord may be disposed between the belt layer 600 and the tread portion 100. The cap ply 800 can suppress the flow of the belt layer 600 when traveling and can maintain the performance of the tire.

Fig. 1 exemplifies the tire for a passenger car, but the present invention is not limited to this, and a tire used for various vehicles such as passenger cars, trucks, buses, heavy vehicles, etc. is provided.

The present invention will be described in more detail by way of the following examples and comparative examples. However, the examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

(Hybrid code)

Example 1 (A1000D / 1P + N66 840D / 1P)

375 TPM in the S direction and a linear density of 1000 Ddenier (hereinafter denoted as D)

A hybrid cord of 370 TPM was prepared having the number of twisted turns of 380 TPM in the S direction and a nylon 66 down yarn of a linear density of 840 D,

The weight ratio of aramid yarn yarn to nylon 66 yarn was 54:46.

The elastic modulus of the hybrid cord at 2% elongation was 59 g / d, and the elastic modulus at 4% elongation was 62 g / d. The ratio of the modulus at 4% elongation to the modulus at 2% elongation was 1.05.

The strength of the aramid lower yarn at a 2% elongation was 5.4 and the strength at a 4% elongation was 13. The nylon lower yarn had a strength of 1.1 at a 2% elongation and a 1.6 at a 4% elongation.

Therefore, the ratio of the strength at 4% elongation to the strength at 2% elongation of aramid yarn was 2.5, and the ratio of the strength at 4% elongation to the strength at 2% elongation of nylon 66 lower yarn was 1.5.

Example 2 (A1500D / 1P + N66 1260D / 1P)

A 315TPM twisted yarn in the S direction and an aramid yarn with a linear density of 1500D; and

A hybrid cord of 310 TPM twisted in the Z direction, including the number of twisted strands 320 TPM in the S direction and a nylon 66 undersurface with a linear density of 1260 D, was prepared.

The weight ratio of aramid yarn yarn to nylon 66 yarn was 54:46.

The elastic modulus of the hybrid cord at 2% elongation was 49 g / d, and the elastic modulus at 4% elongation was 51 g / d. The ratio of the elastic modulus at the 4% elongation to the elastic modulus at the 2% elongation was 1.04.

Comparative Example 1 (A1000D / 2P)

A twisted 450 TPM cord in the S direction and a twisted 450 TPM cord stranded in the Z direction together with two aramid yarns with a linear density of 1000D were prepared.

The elastic modulus at 2% elongation of the aramid cord was 260 g / d, and the elastic modulus at 4% elongation was 322 g / d. The ratio of the modulus at 4% elongation to the modulus at 2% elongation was 1.24.

Comparative Example 2 (N66 840D / 2P)

Two twisted nylon yarns with a twisted number of 310 TPM in the S direction and a linear density of 840 D were prepared with a twisted 300 TPM cord in the Z direction.

The elastic modulus of the nylon cord at 2% elongation was 51 g / d, and the elastic modulus at 4% elongation was 39 g / d. The ratio of the modulus at 4% elongation to the modulus at 2% elongation was 0.76.

Comparative Example 3 (A1000D / 1P + N66 840D / 1P)

440 TPM of twisted yarn in the S direction and an aramid yarn with a linear density of 1000

A 295 TPM number of twisted yarns in the S direction and a nylon 66 undersurface of a linear density of 840. The twisted yarns of the twisted yarns together in the Z direction were prepared with a 390 TPM hybrid cord.

The weight ratio of aramid yarn yarn to nylon 66 yarn was 54:46.

The elastic modulus of the hybrid cord at 2% elongation was 79 g / d, and the elastic modulus at 4% elongation was 114 g / d. The ratio of the modulus at 4% elongation to the modulus at 2% elongation was 1.44.

Comparative Example 4 (A1500D / 1P + N66 1260D / 1P)

A 295TPM twisted yarn in the S direction and a linear density of 1500 denier (denoted as D)

A hybrid cord having a twist number of 185 TPM lowered in the S direction and a nylon 66 lower yarn having a linear density of 1260 D, and the twisted yarns of the twisted yarns in the Z direction together with 280 TPM were prepared.

The weight ratio of aramid yarn yarn to nylon 66 yarn was 54:46.

The elastic modulus of the hybrid cord at 2% elongation was 87 g / d, and the elastic modulus at 4% elongation was 146 g / d. The ratio of the modulus at 4% elongation to the modulus at 2% elongation was 1.68.

Hybrid cord twist

The twist direction and twist number of the hybrid cord prepared in Examples 1 to 2 and Comparative Examples 1 to 4 are summarized in Table 1 below.

1st undersurface twist number
[TPM] 2nd under twist twist
[TPM] Number of kinks
[TPM] The first underside twist number /
2nd under twist twist Example 1 S 375 S 380 Z 370 0.99 Example 2 S 315 S 320 Z 310 0.98 Comparative Example 1 S 450 - Z 450 - Comparative Example 2 - S 310 Z 300 - Comparative Example 3 S 440 S 295 Z 390 1.49 Comparative Example 4 S 295 S 185 Z 280 1.59

Hybrid cord property measurement

The hybrid cord prepared in Examples 1 to 2 and Comparative Examples 1 to 4 and the strength and modulus of elasticity according to the elongation of the lower cord used in the hybrid cord were measured according to the ASTM D-885 method, Respectively.

The stress ratios according to the elongation ratios of the lower strands were described in Examples 1 to 2 and Comparative Examples 1 to 4, respectively.

2% elastic modulus [g / d] 4% Elasticity [g / d] 4% modulus /
2% modulus 2% Strength [g / d] 4% strength [g / d] 4% strength /
2% strength Example 1 59 62 1.05 1.3 2.5 1.9 Example 2 49 51 1.04 1.0 2.1 2.1 Comparative Example 1 260 322 1.24 5.3 13 2.5 Comparative Example 2 51 39 0.76 1.1 1.6 1.5 Comparative Example 3 79 114 1.44 1.6 4.7 2.9 Comparative Example 4 87 146 1.68 1.8 5.9 3.3

In Table 2, the 2% elastic modulus is an elastic modulus at elongation of 2%, the 4% elastic modulus is an elastic modulus at an elongation of 4%, the 2% strength is a stress at an elongation of 2% The 4% strength is the strength at 4% elongation.

(Tire manufacturing)

Example 3

A tire having a cap ply including the cord of Example 1 was produced. The dimensions of the manufactured tires were 225 / 45ZR17 94Y, the number of cap ply was one, the cap ply was full cover, and the cord arrangement density was 28 (ends / inch).

Example 4 and Comparative Examples 5 to 8

Tires were prepared in the same manner as in Example 3, except that the cap ply including the cord of Example 2 and Comparative Examples 1 to 4 was used instead of the cord of Example 1, respectively.

Steering stability evaluation

A professional test driver drives a vehicle equipped with an evaluation tire to evaluate the responsiveness of cornering or lane change. The evaluation tires were run for 30 minutes at a speed of 80 to 120 km / hr to evaluate steering stability. The results are shown in Table 3 below.

The value of Comparative Example 6 is set to 100, and the handling stability of Examples 3 to 4 and Comparative Examples 7 to 8 is represented by a relative value. The higher the value, the better the steering stability.

High-speed running durability evaluation

The durability of the tires at high speed was evaluated under the conditions of air pressure of 3.65 kgf / cm 2 and load of 456 kg according to ECE-R30, and the results are shown in Table 3 below. The value of Comparative Example 6 is set to 100, and the fast running durability of Examples 3 to 4 and Comparative Examples 7 to 8 is represented by a relative value. The higher the value, the better the durability at high speed.

Evaluation of high-speed rolling resistance

The pneumatic tires manufactured in accordance with the ISO 28580 test conditions were mounted on a regular rim, filled with a specified internal pressure of 250 kPa, and the rolling resistance was measured at a speed of 80 km / h and a load of 536 kg using a rolling resistance tester. Are shown in Table 3 below.

For the rolling resistance coefficient (RRC) obtained by dividing the measured value of the rolling resistance by the load, the value of Comparative Example 6 is taken as 100, and the rolling resistance of Examples 3 to 4 and Comparative Examples 7 to 8 is shown as a relative value. The smaller the value, the smaller the rolling resistance and the better the performance.

Flat spot rating

The flat spots of the tires were evaluated according to the flat spot evaluation criteria of the tires which specified the restoration time and restoration degree of the tire shape deformation under a specific load, temperature and time, and the results are shown in Table 3 below. The value of Comparative Example 6 is set to 100, and the fast running durability of Examples 3 to 4 and Comparative Examples 7 to 8 is represented by a relative value. The higher the value, the better the flat spot.

Steering stability High speed durability High-speed rolling resistance Flat spot Example 3 109 115 96 103 Example 4 112 121 95 104 Comparative Example 5 Not measurable Not measurable Not measurable Not measurable Comparative Example 6 100 100 100 100 Comparative Example 7 103 108 103 101 Comparative Example 8 106 110 104 103

As shown in Table 3, the tires of Examples 5 to 8 improved the steering stability, the high-speed running durability, and the flat spot, and the rolling resistance was reduced and the tire performance was improved overall as compared with the tires of Comparative Examples 6 to 8.

The tires of Examples 3 to 4 were determined to have improved fuel economy and flat spot due to reduced rolling resistance and improved driving performance by reducing tire growth and deformation at high speeds.

Tires employing the cap ply including the aramid cords of Comparative Example 1 could not be manufactured and the properties could not be measured.

In the tires of Comparative Examples 6 to 8, it was judged that the growth and deformation in the circumferential direction in the circumferential direction at the high speed running were reduced, but the growth and deformation of the side portion were rapidly increased, so that the balance of the tire was decreased and the rolling resistance was increased and the flat spot was decreased.

10: Tire 100: Tread
200: side wall portion 300: bead portion
400: carcass layer 500: bead core
600: belt layer 700: inner liner
800: cap fly

Claims (12)

And a first underside yarn and a second underside yarn simultaneously stacked,
The elastic modulus is 40 g / d to 110 g / d in the elongation period of 2% to 4%
Wherein the ratio of the modulus of elasticity at 4% elongation to the modulus at 2% elongation is 1.0 to 1.40. The hybrid cord of claim 1, wherein the ratio of the strength at 4% elongation to the stress at 2% elongation is 1.6 to 2.4. The hybrid cord according to claim 1, wherein the first lower unstretched yarn is a yarn having a high modulus of elasticity and the second lower yarn is a yarn having a low elastic modulus. The method according to claim 1, wherein the ratio of the strength at 4% elongation to the stress at 2% elongation of said first underlay is 1.5 to 3.5 and the ratio of strength at 2% elongation And the ratio of the strength at the percent elongation is 0.5 to 2.5. The hybrid cord according to claim 1, wherein the first lower warp yarns are aramid yarns and the second lower yarn yarns are nylon yarns. The hybrid cord according to claim 1, wherein the weight ratio of the first lower warp yarn to the second lower warp yarn is 50:50 to 70:30. The hybrid code according to claim 1, wherein the linear density is 1700D to 5000D. The hybrid code according to claim 1, wherein the twist of the first lower warp yarn is smaller than the twist number of the second lower warp yarn. The hybrid cord according to claim 1, wherein the twist of the first lower warp yarn is 97% to 99.9% of the twist of the second lower warp yarn. The hybrid code according to claim 1, wherein the twist direction of the first lower warp yarn is the same as the twist direction of the second lower warp yarn. The hybrid cord according to claim 1, wherein the twist direction in which the first and second lower warp yarns overlap is different from the twist direction of the first down yarn and the second lower warp yarn. A tire having a cap fly comprising the hybrid cord of any one of claims 1 to 11.

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