KR20050012445A - High performance radial tire using polyethylene-2,6-naphthalate fiber - Google Patents

Abstract

PURPOSE: Provided is a high-performance radial tire applying high-strength polyethylene naphthalate fiber to a tire cap ply, which is characterized by improving fatigue resistance and shape stability. CONSTITUTION: A dip cord for a high-performance radial tire is produced by a process comprising the steps of: a) melt-spinning solid-phase polymerized polyethylene-2,6-naphthalate chips(having more than 85 mol% of ethylene-2,6-naphathalate units and 0.80-1.20 of specific viscosity) in 20-200 of spinning draft to obtain molten yarn; b) passing the molten yarn in a delayed quenching zone and a quenching zone to be solidified; c) drawing off yarn in spinning velocity that undrawn yarn has less than 0.015 of birefringence and less than 1 deg.C of rising of melting point, and continually drawing the yarn in multi-steps in more than 4.0 of total drawing ratio to be wound. The dip cord is characterized by: 1) 0.6-1.0 of specific viscosity; 2) more than 8.5g/d of strength; 3) more than 6% of elongation; 4) more than 0.35 of birefringence; 5) 1.355-1.375 of density; 6) 270-285 deg.C of melting point; and 7) 1-4% of shrinkage.

Description

High performance radial tire using polyethylene-2,6-naphthalate fiber

The present invention relates to a high performance radial tire in which a polyethylene naphthalate (PEN) cord having excellent high temperature form stability and strength is applied to a belt reinforcing layer portion (cap ply), and more specifically, a polyethylene naphthalate which satisfies the following physical properties for a high performance radial tire The present invention relates to a high-performance radial tire that is applied to a deep cord made of fiber to improve tire fatigue performance and shape stability.

(1) intrinsic viscosity of 0.6 to 1.0, (2) strength of 8.5 g / d or more, (3) elongation of 6% or more, (4) birefringence of 0.35 or more, (5) density of 1.355 to 1.375, (6) 270 to Melting point of 285 ° C., and (7) shrinkage of 1 to 4%

Conventional radial tires consist of a carcass ply reinforced with rubber with fiber cords such as polyester, rayon or aramid, a belt structure and a belt reinforcement layer reinforced with rubber with steel cords.

The belt reinforcement layer (cap fly) of the tire is a reinforcement to prevent the growth of the tire form at high temperatures, and particularly focuses on preventing the expansion of the tire due to the increase in air pressure inside the tire due to the shrinkage at high temperatures. . As a material of such a tire cap ply, it has conventionally been used a polyamide 66 material having a high shrinkage and shrinkage force at a high temperature and a relatively low physical property degradation due to heat.

Recently, efforts have been made to apply PEN fibers to cap plies in order to reduce tire weight and improve cornering performance. For example, the invention using the PEN code as a cap ply material is disclosed in US Pat. No. 5,931,211. When the cord is used as a cap fly material, it has been shown that high speed durability and steering stability can be improved and noise can be reduced. However, the PEN code has a problem of low fatigue resistance and high utilization rate.

Due to the above problems, in the case of the tire using a conventional PEN code as a cap ply, it has been limited in use despite the possibility of improving the high speed durability and steering stability and reducing the noise.

The present invention is to replace the cord used as the material of the belt reinforcement layer of the pneumatic radial tire with polyethylene naphthalate fiber that satisfies the following properties excellent in high temperature properties, shape stability and strength, thereby improving the shape stability and fatigue performance and flatness ratio is 0.6 The technical problem is to provide the following high performance pneumatic radial tires.

(1) intrinsic viscosity of 0.6 to 1.0, (2) strength of 8.5 g / d or more, (3) elongation of 6% or more, (4) birefringence of 0.35 or more, (5) density of 1.355 to 1.375, (6) 270 to Melting point of 285 ° C., and (7) shrinkage of 1 to 4%

1 is a schematic representation of a spinning process according to the invention.

Figure 2 is a schematic diagram showing the structure of a tire for a passenger car manufactured using a high strength polyethylene naphthalate deep cord according to the present invention.

※ Brief description of the main symbols in the drawing

11: tire 12: carcass layer

13: code for reinforcing the carcass layer 14: fly turn-up

15: bead area 16: bead core

17: Bead filler 18: Belt structure

19: cap fly 20: belt fly

21, 22: belt code 23: tread

24: edge fly 25: cap fly code

The present invention applies polyethylene naphthalate fiber having excellent high temperature shape stability and strength to the reinforcing tire cord 25 in the belt reinforcing layer 19 of the tire 11 as shown in FIG.

The high strength polyethylene naphthalate fiber in the belt reinforcing layer portion used in the present invention is produced as follows.

(a) melt-spun solid polymerized polyethylene-2,6-naphthalate chips containing at least 85 mol% of ethylene-2,6-naphthalate units and having an intrinsic viscosity in the range of 0.80 to 1.20 at a spinning draft ratio of 20 to 200; Generating the discharge yarn, (b) solidifying the melt discharged yarn through the delayed cooling zone and the cooling zone, and (c) spinning such that the birefringence of the non-drawn yarn is 0.015 or less and the melting point rise is 1 ° C or less. After pulling the yarn at a speed, the polyethylene naphthalate fiber excellent in high temperature morphological stability and strength is produced by continuously stretching the yarn to 4.0 or more in total draw ratio and winding the yarn.

The physical properties of the polyethylene naphthalate fiber produced by the above method is as follows.

(1) intrinsic viscosity of 0.6 to 1.0, (2) strength of 8.5 g / d or more, (3) elongation of 6% or more, (4) birefringence of 0.35 or more, (5) density of 1.355 to 1.375, (6) 270 to Melting point of 285 ° C., and (7) shrinkage of 1 to 4%

Hereinafter, the manufacturing process of polyethylene naphthalate fiber having excellent high temperature shape stability and strength in the present invention will be described in more detail.

The polyethylene naphthalate chip used in the present invention contains at least 85 mol% of ethylene-2,6-naphthalate units and preferably consists only of ethylene-2,6-naphthalate units.

Optionally, the polyethylene-2,6-naphthalate may incorporate as a copolymer unit a small amount of units derived from one or more ester-forming components other than ethylene glycol and 2,6-naphthalene dicarboxylic acid or derivatives thereof. Can be. Examples of other ester forming components copolymerizable with polyethylene naphthalate units include glycols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and the like, terephthalic acid, isophthalic acid, hexahydroterephthalic acid, stilbene Dicarboxylic acids such as dicarboxylic acid, dibenzoic acid, adipic acid, sebacic acid, azelaic acid.

The polyethylene naphthalate chip according to the present invention preferably melt-mixes naphthalene-2,6-dimethylcarboxylate (NDC) and ethylene glycol raw materials at 190 ° C. at a ratio of 2.0 to 2.3 and transesterifies the melted mixture. Reaction (for about 2 to 3 hours at 220 to 230 ° C.) and condensation polymerization (about 2 to 3 hours at 280 to 290 ° C.) to produce raw chips having an intrinsic viscosity of 0.42 to 0.50, followed by 240 Solid phase polymerized to have an intrinsic viscosity of 0.80 to 1.20 and a moisture content of 30 ppm or less under a temperature of from 260 ° C to vacuo.

In the transesterification reaction, as a transesterification catalyst, a manganese compound, preferably manganese acetate, may be added in an amount such that the amount remaining as a manganese metal in the final polymer is 10 to 90 ppm. If the exchange reaction rate is too slow, and more than 90 ppm, more manganese metal than necessary to act as a foreign matter and becomes a problem during solid state polymerization and spinning.

In the polycondensation reaction, as the polymerization catalyst, an antimony compound, preferably antimony trioxide, may be added in an amount such that the amount remaining as an antimony metal in the final polymer is from 100 to 900 ppm. When the polymerization efficiency is lowered, the polymerization efficiency is lowered, and when it is more than 900 ppm, more than necessary antimony metal acts as a foreign material, which degrades radio-stretching workability. At this time, a phosphorus heat stabilizer, preferably trimethyl phosphate, may be added in an amount such that the amount remaining as a phosphorus element in the final polymer is 10 to 95 ppm, and the manganese / phosphorus content ratio is 2.0 or less. When the manganese / phosphorus content ratio is higher than 2.0, the oxidation is promoted during the solid phase polymerization, so that normal physical properties cannot be obtained during spinning.

The polyethylene naphthalate chip thus produced is fiberized according to the method of the present invention, and FIG. 1 schematically shows a manufacturing process according to one embodiment of this invention.

In step (a), the polyethylene naphthalate chip is passed through a pack (1) and a nozzle (2) at a spinning draft ratio of 20 to 200 at a temperature of 300 to 318 ° C. (linear velocity on the first winding roller / linear velocity at the nozzle) By low-temperature melt spinning with), a decrease in the viscosity of the polymer due to thermal decomposition and hydrolysis can be prevented. If the spinning draft ratio is less than 20, the uniformity of the filament cross section worsens, and the drawing workability is significantly lowered. If it exceeds 200, the filament breakage occurs during spinning, making it difficult to produce a normal yarn.

In step (b), the melt-discharge yarn 4 produced in step (a) is solidified by passing through the cooling zone 3, if necessary, the distance from directly below the nozzle 2 to the starting point of the cooling zone 3. That is, the heating device can be installed in the hood length (L). This zone is called a delayed cooling zone or a heating zone and may have a length of 100 to 900 mm and a temperature of 300 to 450 ° C. In the cooling zone 3, an open quenching method, a circular closed quenching method, and a radial outflow quenching method may be applied depending on a method of blowing cooling air. It is not limited to. Subsequently, the discharged yarn 4 solidified while passing through the cooling zone 3 can be oiled by the emulsion applying device 5 to 0.5 to 1.0%.

In step (c), the feed roller 6 is wound at a spinning speed such that the birefringence of the undrawn yarn is 0.015 or less and the melting point rise is 1 ° C. or less, and the preferred spinning speed is 300-1500 m / min.

In the present invention, the birefringence of the undrawn yarn and the rise of the melting point of the undrawn yarn are used as factors for controlling the microstructure of the undrawn yarn.

The core technology of the present invention is the intrinsic viscosity, spinning temperature, orifice length / diameter, delay cooling condition, cooling condition, spinning speed, etc. of the solid-phase polymerized chip so that the birefringence and melting point rise of undrawn yarn are 0.015 or less and 1 ° C or less, respectively. The same spinning process factor is properly adjusted. In general, in order to manufacture high strength yarns, the drawability of undrawn yarn should be excellent. If the birefringence of the unstretched yarn exceeds 0.015, crystallization progresses so rapidly during stretching that it is difficult to produce high strength yarn because of its low stretchability.

In addition, in the present invention, the melting point increase for the non-twisted yarn that appears on the thermal analyzer is used as a factor for controlling the microstructure of the unstretched yarn. Here, the melting point rise of the non-drawn yarn (ΔTm) is calculated by ΔTm = Tm'-Tm "(where Tm 'is the melting point of the non-drawn yarn, and Tm" is the non-drawn yarn in the differential thermal analyzer (DSC)). Melting point of the yarn measured by quenching after melting at 300 ℃ for 3 minutes to remove the heat history.)

The melting | fusing point rise of the unstretched yarn preferable in this invention is 1 degrees C or less. Because the unstretched melting point value is related to the unstretched crystallization rate. As the crystallization rate of the non-drawn yarn increases, the melting point rises proportionally.The faster the crystallization rate of the undrawn yarn sample, the faster the crystallization proceeds during the temperature increase (20 ° C / min) on the DSC (differential thermal analyzer). To be larger. In the present invention, the lower the melting point rise value of the undrawn yarn, the more the final draw ratio is improved by suppressing the crystallization of the undrawn yarn in the initial stage of the stretching process, and the melting point rise of the undrawn yarn is 1 ℃ or less. If the melting point rise of the undrawn yarn exceeds 1 ° C, crystallization of the undrawn yarn proceeds rapidly at the beginning of the drawing process, resulting in poor stretchability.

As described above, in the present invention, by adjusting the intrinsic viscosity, spinning temperature,, orifice length / diameter, delay cooling condition, cooling condition, spinning speed, etc. of the solid-phase polymerized chip, the birefringence of undrawn yarn is 0.015 or less, undrawn yarn. By increasing the melting point of less than 1 ℃ to ensure maximum stretch in the stretching process can be produced a high strength polyethylene naphthalate fiber.

In addition, in step (c) of the present invention, the yarn that has passed through the feed roller 6 is once wound and then subjected to a series of stretching rollers by using a separate stretching process, or preferably by a spin draw method. 7, 8, 9 and 10) to obtain the final stretched yarn (11) by multistage stretching while passing, the temperature of the second stage stretching is adjusted to 150 to 180 ℃. More specifically, first 0.5 to 3% of free draw (free draw), and then the first stage stretching at 5 to 7 times at 150 to 180 ℃, the second stage stretching at 1.2 to 2.0 times at 160 to 200 ℃ In order to increase the uniformity of high magnification stretching during the first stage stretching, the steam jet method may be applied. Then, according to a conventional method, the drawn yarn can be heat set to a temperature of 220 to 250 ° C (relaxing) to 0 to 3%.

Stretched polyethylene naphthalate fibers produced according to the process of the present invention have an intrinsic viscosity of 0.73 to 0.80, a strength of at least 8.5 g / d, an elongation of at least 6.0%, a birefringence of at least 0.35, a density of 1.355 to 1.375, a melting point of 270 to 285 ° C. And shrinkage of 1 to 4%.

In the present invention, a high-strength polyethylene naphthalate fiber satisfying the above properties is twisted with a twisting machine to produce a raw cord, and then weaved to immerse it in a dipping liquid to provide a polyethylene naphthalate deep cord.

Hereinafter, the twist, weaving and dipping process of the present invention will be described in more detail.

When explaining the twisting process of the present invention in more detail, the polyethylene naphthalate stretched yarn produced by the above method by twisting the two wound yarns with a direct twisting machine in which the twisting and joining proceeds simultaneously 'raw cord (Raw Cord) for the tire cord Manufacture. Raw cords are manufactured by adding Ply Twist to a polyethylene naphthalate yarn for tire cords and then adding them together with Cable Twist. In general, the upper and lower ends are applied with the same or different years as needed.

An important result of the present invention is that the physical properties of the cord, such as elongation, mesophilic, fatigue resistance, depending on the level of twisting (years) imparted to polyethylene naphthalate. In general, at high kinks, the strength decreases, and the trunk and the trunk tend to increase. The fatigue fatigue tends to improve with the increase of twist. The soft water of the polyethylene naphthalate tire cord manufactured in the present invention was manufactured at 250/250 TPM to 500/500 TPM at the same time as the upper and lower edges, and the upper and lower edges were given the same value. It is to maximize the physical properties by making it easy to maintain a straight line without showing. At this time, if less than 250/250 TPM, the extension of the raw cord is reduced, fatigue fatigue is easy to fall, and if it exceeds 500/500 TPM, the strong degradation is large, it is not suitable for the tire cord.

In the present invention, if the number of years of upper / lower smoke may be given differently, the upper edge is adjusted to 350TPM to 550TPM, and the lower edge is adjusted to 300TPM to 550TPM to produce a live cord with different numbers of upper and lower edges, respectively. The production of upper and lower stations is different because the lower the number of stations within the optimum properties of the raw cord, the lower the cost of speakers and the economic benefit. A "twist constant" has been proposed as a constant for evaluating such kinks.

Raw cord is manufactured by using a weaving machine, and the obtained fabric is immersed in a dipping solution, and then cured to produce a tire cord having a resin layer attached to the surface of the raw cord. Make a 'Dip Cord'.

In more detail, the dipping process of the present invention, dipping is achieved by impregnating a surface of the fiber with a resin layer called RFL (Resorcinol-Formaline-Latex), which is a disadvantage of the fibers for tire cords that are inherently poor in adhesion to rubber. Is carried out to improve. In general, rayon fiber or nylon is subjected to one bath dipping, and in the case of using PET fiber, since the reactor on the surface of PET fiber is less than that of rayon fiber or nylon fiber, the surface of the PET is activated first and then the adhesive treatment is performed. (2 bath dipping). The polyethylene naphthalate company according to the invention uses two bath dipping. The dipping bath uses a known dipping bath for the tire cord.

The deep cord manufactured according to the above-described method has a total denier of 3000 to 6000 days, a twisting constant of 0.50 to 0.85, and a cutting load of 14.0 to 35.0 kg, and may be advantageously used as a tire cord for a passenger car. .

The present invention manufactures the cord used as the material of the belt reinforcing layer (cap ply) of the pneumatic radial tire by the above-described method, and by replacing the polyethylene naphthalate fiber with excellent high temperature properties, shape stability and strength, The technical challenge is to provide high performance pneumatic radial tires with improved fatigue performance and flatness of less than 0.6.

Specifically, a cord as shown in FIG. 2 is produced. More specifically, the capfly cord 25 using the polyethylene naphthalate deep cord manufactured according to the present invention has a total denier of 3,000 d to 6,000 d. The carcass ply 12 includes at least one carcass ply reinforcement tire cord 13. The carcass ply 12 with radially outer fly turnup 14 preferably comprises a carcass cord of one layer to two layers. The reinforcing carcass cord 13 is oriented at an angle of 85 ° -90 ° with respect to the circumferential intermediate surface of the tire 11. In the particular embodiment shown, the reinforcing carcass cord 13 is arranged at 90 ° with respect to the circumferential intermediate plane. For fly turnup 14, it is preferred to have a height of 40-80% relative to the tire maximum cross-sectional height. If the fly turn-up is less than 40%, the stiffness complementary effect of the tire sidewall is too low, and if it is 80% or more, the tire sidewall stiffness is too high, which adversely affects the riding comfort.

Hereinafter, FIG. 2 will be described in more detail as follows.

The bead regions 15 of the tire 11 each have an annular bead core 16 that is inextensible. The bead core is preferably made of a single or single filament steel wire wound continuously. In a preferred embodiment, high strength steel wires of 0.95 mm-1.00 mm diameter form a 4x4 structure, and it is also possible to form a 4x5 structure.

In certain embodiments of the present invention, the bead region also has a bead filler 17, in the case of the bead filler, it is necessary to have a hardness of at least a certain level, preferably Shore A hardness of 40 or more is preferred.

In the present invention, the tire 11 is reinforced by the crown portion by the belt 18 and the cap ply 19 structure. The belt structure 18 comprises two cutting belt plies 20 and the cords 21 of the belt plies are oriented at an angle of about 20 degrees with respect to the circumferential central surface of the tire. The cord ply 21 of the belt ply is arranged opposite to the direction of the cord 22 of the other belt ply in a direction opposite to the circumferential central plane. However, the belt 18 may comprise any number of plies and may preferably be arranged in the range of 16-24 °. The belt 18 serves to provide lateral rigidity to minimize the rise of the tread 23 from the road surface during operation of the tire 11. The cords 21 and 22 of the belt 18 are made of steel cords and have a 2 + 2 structure, but can be produced in any structure. The cap ply 21 and the edge ply 24 are reinforced on the upper part of the belt 18. The cap ply cord 25 in the cap ply 19 is reinforced in parallel with the circumferential direction of the tire, resulting in high speed rotation of the tire. It serves to suppress the change in the size of the circumferential direction, and a cap fly cord 25 having a large heat shrinkage stress at a high temperature is used. One layer of cap ply 19 and one layer of edge ply 21 may be used, but preferably, 1-2 layers of cap ply and also 1-2 layers of edge ply are reinforced.

EXAMPLE

Hereinafter, the structure and effect of the present invention will be described in more detail with specific examples and comparative examples, but these examples are only intended to more clearly understand the present invention, and are not intended to limit the scope of the present invention. In Examples and Comparative Examples, properties of the tire cord and the like were evaluated in the following manner.

(a) Tire cord strength (kgf) and middle elongation (%)

After drying at 107 ° C. for 2 hours, Instron's low-strength tensile tester was used. After twisting with 20 Tpm (20 twists / m), the sample was measured at 250 mm and a tensile speed of 300 m / min. The elongation at specific load imposed here represents the elongation at the point of 6.8 kg load.

(b) Dry heat shrinkage (%, Shrinkage)

After drying for 24 hours at 25 ° C and 65% RH, dry heat shrinkage was determined using the ratio of the length (L ₀ ) measured at 20g stop and the length (L ₁ ) after treatment at 20g static load for 30 minutes at 150 ° C. Indicates.

S (%) = (L ₀ -L ₁ ) / L ₀ × 100

(c) E-S

Elongation under constant load is referred to as the middle elongation (E) in the present invention, where the load means 6.8 kg. The reason for evaluating elongation at 6.8kg is that it is considering the maximum load per tire cord. And 'S' means the dry heat shrinkage of the above (b), the sum of the median elongation (E) and dry heat shrinkage (S) is referred to in the present invention as 'E-S'. In general, once the tire is vulcanized, the shrinkage and intermediate elongation of the cord change. The sum of shrinkage and median elongation is similar to the concept of modulus in the cord after the tire is fully manufactured. In other words, if the value of 'E-S' is low, the modulus increases. If the modulus is high, it is easier to control due to the large force generation due to the deformation of the tire, and on the contrary, it is possible to use less deformation in order to create the same degree of tension. Can be. Therefore, the value of 'E-S' is utilized to determine the superiority of cord performance in tire manufacturing. In addition, when the tire is manufactured, the tire having a low E-S value has an effect of improving the uniformity of the tire since the amount of deformation due to heat is small, thereby improving the uniformity of the entire tire. Therefore, in the case of a tire using a cord having a low E-S value, since tire uniformity is more effective than a tire using a high cord, it is possible to improve tire performance.

E-S = Elongation at 6.8kg + Shrinkage

(d) Twisting constant (R)

The twist constant (R) is obtained by the following equation. Cords with the same twist constant mean that the joined single yarn is reinforced at the same angle relative to the length of the cord:

(Wherein R is the twist constant, N is the twist number D per 10 cm, and den is the total denier).

(e) Even with fatigue

The fatigue strength was compared by measuring the residual strength after the fatigue test using the Goodrich Disc Factigue Tester which is commonly used for fatigue testing of tire cords. Fatigue test conditions were 120 ℃, 2500RPM, compression 10% and 18% conditions, and after the fatigue test was swelled in a tetra cholore ethylene solution for 24 hours to swell the rubber and the rubber and cord was separated to measure the remaining strength. The residual strength was measured after drying at 107 degrees for 2 hours using a conventional tensile strength tester according to the method (a) above.

(f) adhesion

Adhesion was measured by the H-test method based on ASTM D4776-98 method.

Example 1

A solid-state polymerized polyethylene naphthalate chip having an intrinsic viscosity (I.V.) of 0.90, manganese / phosphorus content ratio of 1.8 and a water content of 20 ppm containing 40 and 220 ppm of manganese and antimony metal, respectively, was prepared. The produced chips were melt spun using an extruder at a discharge rate of 440 g / min and a spinning draft ratio of 550 at a temperature of 316 ° C. At this time, a static mixer having five units was installed in the polymer conduit of the pack to evenly mix the melt-spun polymer. Subsequently, the discharged yarn is solidified through a 40 cm long heating zone (atmosphere temperature 370 ° C.) and a 530 mm long cooling zone (20 ° C., cooling air blowing with a wind speed of 0.5 m / sec), followed by oiling with a spinning emulsion. It was. This undrawn yarn was wound at a spinning speed of 470 m / min, gave 2% free draw, and then stretched in two stages. The first stage stretching is 6.0 times at 158 ℃, the second stage stretching is performed at 1.1 times at 163 ℃, heat-fixed at 230 ℃ and relaxed 1% and then wound to prepare a final stretched yarn (yarn) of 1500 denier.

After two strands of yarn were rolled up and down at 390 turns / m to prepare cord yarns, the cord yarns were immersed in the adhesive solution of (PCP resin + RFL) in a dipping tank and then stretched 1.0% at 170 ° C. in a drying area. After drying for 150 seconds and heat-setting to 240 ° C. for 150 seconds in a high-temperature stretching region, it was again immersed in RFL, dried at 170 ° C. for 100 seconds, and heat-set to 240 ° C. under -1% stretching for 40 seconds to prepare a deep cord.

The physical properties of the drawn yarn and the dip cord thus prepared are shown in Table 1 below.

[Examples 2 to 5 and Comparative Examples 1 to 7]

Experiment in the same manner as in Example 1 while changing the intrinsic viscosity of the chip, the manganese / phosphorus content ratio, the spinning temperature, the spinning draft ratio, the length or temperature of the heating zone, or the birefringence of the undrawn yarn as shown in Table 1 below The stretched yarn and the treatment cord were manufactured by following the steps.

The physical properties of the drawn yarn and the dip cord thus prepared are shown in Table 1 below.

TABLE 1

Example 6

The radial tire manufactured by using the polyethylene naphthalate deep cord prepared according to Example 5 of the present invention has a cap fly layer, and the cap fly layer includes one or more polyethylene naphthalate deep cords prepared according to Example 5. It was installed to include the second floor. At this time, the specifications of the carcass cord and the cap ply are shown in Table 2 below, and the belt 8 is formed by a belt reinforcement layer having a cap ply 9 on the top and an edge ply 14 on the first layer. It was reinforced and placed so that the capply cord in the capply 9 was parallel to the circumferential direction of the tire.

[Comparative Example 8-9]

A tire was manufactured in the same manner as in the example except that the cord material and specifications for manufacturing the tire were changed as shown in Table 2.

Table 1

Example 6 Comparative Example 8 Comparative Example 9 Carcass Material PET PET Rayon Specification (d / ply twisted yarn) 1500d / 2 1500d / 2 1650d / 3 EPI (ends / in) 25 25 25 Strong (Kg) 22 22 26 Modulus of elasticity (g / d) 120 75 60 Cap fly Material PEN nylon nylon Specification (d / ply twisted yarn) 1500d / 2 1260d / 2 1260d / 2 Strong (Kg) 23 24 24 Modulus of elasticity (g / d) 90 30 30 tire Flat ratio 0.60 0.60 0.60 Carcass floors One One One Cap fly floor One One One

The 215/60 R15 V tires manufactured according to Example 6 and Comparative Example 8-9 were mounted on a 2000cc class passenger car, and the noise generated in the vehicle was measured while driving at a speed of 60 km / h, thereby reducing noise in the audible frequency range. dB), and the steering stability and riding comfort were evaluated by a trained driver who traveled the test course in units of 5 out of 100 points, and the results are shown in Table 2 below. Durability is based on FMVSS 109's P-metric tire endurance test method, measuring 38 degrees Celsius (± 3 degrees) and 85, 90, 100% of the tire's nominal load. A total of 34 hours was used to determine the pass (OK) when no trace of bead separation, cord cutting, belt separation, etc. was found in any part of the tread, sidewall, carcass cord, inner liner, or bead. .

[Table 2]

division Example 6 Comparative Example 8 Comparative Example 9 Tire weight (kg) 9.45 9.98 10.12 Ride 100 90 95 Steering stability 100 95 95 durability OK OK OK Uniformity 100 95 97 Noise (dB) 61.4 64.5 63.2

As a result of the test of Table 2, the tire according to the present invention (Example 6) can be seen that the weight of the tire is definitely reduced compared to the case where nylon 66 is applied to the conventional cap ply (Comparative Examples 8 and 9). Therefore, it can be seen that the rotational resistance can be reduced. In addition, in the case of the present invention using the PEN code produced by the present invention in the cap fly in terms of performance, it was excellent in the riding comfort, steering stability and noise reduction aspects, it can be seen that the uniformity of the tire is also improved.

In the present invention, by adjusting the birefringence index and melting point rise of the undrawn yarn, it is possible to produce a high strength polyethylene naphthalate fiber, the treatment cord formed from this yarn is excellent in dimensional stability and strength of rubber products such as tires and belts It can be usefully used as a reinforcing material or for other industrial uses.

According to the present invention, by applying the high-strength PEN code of the present invention to a belt reinforcing layer (cap ply) of a high-performance radial tire, satisfactory results for durability, ride comfort and steering stability of the tire can be obtained.

In addition, by applying high strength PEN fibers, it is possible to provide a lighter tire.

While the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims. .

Claims (4)

(a) melt-spun solid polymerized polyethylene-2,6-naphthalate chips containing at least 85 mol% of ethylene-2,6-naphthalate units and having an intrinsic viscosity in the range of 0.80 to 1.20 at a spinning draft ratio of 20 to 200; Generating emitters, (b) solidifying the melt-discharged yarn through the delayed cooling zone and the cooling zone, and (c) pulling the yarn at a spinning speed such that the birefringence of the non-drawn yarn is 0.015 or less and the melting point rise is 1 ° C or less. , A deep cord made of polyethylene naphthalate fibers having the following physical properties is applied to the belt reinforcing layer portion, which is produced by a method comprising the steps of winding the yarn by multi-stretching the total draw ratio to 4.0 or more continuously. High-performance radial tire made with. (1) intrinsic viscosity of 0.6 to 1.0, (2) strength of 8.5 g / d or more, (3) elongation of 6% or more, (4) birefringence of 0.35 or more, (5) density of 1.355 to 1.375, (6) 270 to Melting point of 285 ° C., and (7) shrinkage of 1 to 4% The method of claim 1, The deep cord is a high-performance radial tire, characterized in that the total denier 3000d to 5500d, twist number 250 to 500TPM, reinforcement density 15 to 30EPI. The method according to claim 1 or 2, And said belt reinforcement layer is one layer. The method of claim 1, High-performance radial tires, characterized by a flat ratio of 0.6 or less.