KR101031550B1 - High performance radial tire - Google Patents

Abstract

The present invention relates to a radial pneumatic tire having a flatness ratio of 0.70 or less, comprising: a pair of parallel bead cords and at least one radial carcass ply wound around the bead core and a belt layer laminated on the outer periphery of the carcass; And a circumferential belt reinforcement layer formed on an outer circumferential side of the belt layer, wherein the carcass ply includes a deep cord made of polyetherylene terephthalate fiber, and the polyethylene terephthalate fiber has the following physical properties Satisfactory and at the same time stretches less than 2.5% when subjected to an initial stress of 2.0 g / d, has an initial modulus value of 80 to 120 g / d, stretches below 7.5% when subjected to a medium stress of 6.0 g / d, minimum A radial pneumatic tire, characterized in that it has a force-strain curve that extends from a tensile strength of 9.5 g / d until the yarn is cut. (1) intrinsic viscosity of 1.0 to 1.2, (2) strength of 9.5 g / d or more, (3) elongation of 12% or more, (4) birefringence of 0.20 or more, (5) density of 1.385 to 1.395, (6) 6 to 7% shrinkage

Radial Tires, Carcass, Ultra High Strength, Polyethylene Terephthalate, Fiber

Description

High performance radial tire

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high performance radial tire in which a polyetherene terephthalate cord having high temperature shape stability and high strength is applied to a carcass ply. More specifically, in a radial pneumatic tire having a flatness of 0.70 or less, A parallel bead cord of at least one radial carcass ply wound around the bead core and a belt layer laminated on the outer circumferential side of the carcass, and a circumferential belt reinforcement layer formed on the outer circumferential side of the belt layer; The carcass ply comprises a deep cord made of polyetherene terephthalate fiber which is less than 2.5% elongated when subjected to an initial stress of 2.0 g / d and an initial of 80 to 120 g / d. With a modulus value, it stretches less than 7.5% when subjected to medium stress of 6.0 g / d, until the yarn is cut from a tensile strength of 9.5 g / d. Extending, force-directed to a radial pneumatic tire, characterized in that it has a variation curve.

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

In addition, the bead wire is reinforced in the contact portion between the tire and the rim to prevent the tire from falling off the rim and to maintain stability, which also serves to fix the carcass ply.

In the first pneumatic tire, cotton canvas was used as a carcass material, and along with the development of artificial fibers, fiber cords such as rayon, nylon, and regular polyester have been used as materials for carcass plies. Cords are used.

In general, regular polyester is used as a carcass ply material of pneumatic radial tires, and more specifically, pneumatic radial tires having a flat ratio of 0.65 to 0.82. In addition, a flat ratio of less than flatness, more specifically, less than 0.70 is used. Background Art Rayon is relatively used as a carcass ply reinforcement for pneumatic radial tires.

Recently, some regular polyester is also used for low-flat ratio tires for high speed, but its application is limited because of low temperature properties and shape stability compared to rayon.

In addition, since general rayon has disadvantages in terms of production method, physical properties, and tire production process, there are many limitations in applying it to general radial tires. In general, the existing rayon is produced using an indirect substitution method, and there are many problems due to the complex manufacturing process and environmental impact. Therefore, in light of recent trends that consider the impact on the environment, there are many problems.

In addition, in terms of physical properties, the wet strength is too low to be inadequate as a tire cord, and when applied to a tire, the strength is lowered due to moisture penetration due to cracks or cuts in the tread portion, thereby deteriorating the durability of the tire.

In addition, there was a problem that the moisture content should be adjusted to less than 2% during tire production.

Due to the above problems, although the tire using the conventional rayon as a carcass has been limited in use despite its excellent shape stability and high temperature properties.

An object of the present invention is to provide a high performance radial tire in which a polyetherene terephthalate cord having excellent high temperature form stability and strength is applied to a carcass ply.

In order to solve the above problems, according to a preferred embodiment of the present invention, in a radial pneumatic tire having a flatness ratio of 0.70 or less, a pair of parallel bead cords and one or more radial cars wound around the bead core A cas ply includes a belt layer laminated on the outer circumferential side of the carcass and a circumferential belt reinforcement layer formed on the outer circumferential side of the belt layer, wherein the carcass ply includes a deep cord made of polyetherene terephthalate fiber. Wherein the polyetherene terephthalate fiber has the following physical properties and at the same time is less than 2.5% when subjected to an initial stress of 2.0 g / d, and has an initial modulus of 80 to 120 g / d, of 6.0 g / d. Radial characterized by having a force-strain curve that elongates less than 7.5% when subjected to medium stress and extends from the tensile strength of 9.5 g / d until the yarn is cut It is an object to provide a pneumatic tire.

(1) intrinsic viscosity of 1.0 to 1.2, (2) strength of 9.5 g / d or more, (3) elongation of 12% or more, (4) birefringence of 0.20 or more, (5) density of 1.385 to 1.395, (6) 6 to 7% shrinkage

According to another suitable embodiment of the present invention, there is provided a radial pneumatic tire, wherein the carcass ply is used in one or two layers.

According to another suitable embodiment of the present invention, there is provided a radial pneumatic tire, characterized in that the deep cord reinforcement density in the carcass ply is 15 to 35 EPI.

According to another suitable embodiment of the present invention, the deep cord provides a radial pneumatic tire, characterized in that the twist number 300 to 500 TPM.

According to another suitable embodiment of the present invention, the deep cord provides a radial pneumatic tire, characterized in that E ^2.25 (elongation at ^2.25 g / d) + FS (free shrinkage) of 6.5% or less.

The present invention can improve the stretchability in the stretching step by adjusting the force-strain curve and the microstructure of the unstretched yarn to produce a very high strength polyetherene terephthalate fiber, the processing cord formed from the yarn has a dimensional stability and strength It is excellent and can be usefully used as a reinforcement for rubber products such as tires and belts or for other industrial uses. In addition, by applying the ultra-high strength polyetherene terephthalate cord of the present invention to a carcass ply of a high-performance radial tire, satisfactory results regarding tire durability, ride comfort, and steering stability can be obtained. In addition, it is possible to provide a lighter tire by applying ultra-high strength polyetherene terephthalate fibers.

The present invention is applied to the carcass ply reinforcement tire cord 13 in the carcass ply 12 of the tire 11 as shown in FIG. 4 by applying a polyetherene terephthalate deep cord having excellent high temperature stability and strength. will be.

As a preliminary step for preparing the polyetherene terephthalate deep cord applied to the carcass ply in the present invention, the preparation of high strength polyetherene terephthalate fiber is prepared using the following process.

(A) extruding a discharge yarn containing at least 85 mol% of ethylene terephthalate units and having an intrinsic viscosity in the range of 1.20 to 1.4 at a temperature of 280 to 305 ° C, and (B) passing the melt discharge yarn through a delayed cooling zone. Quench-solidified and (C) polyester long-fiber partially stretched yarn (hereinafter referred to as "POY yarn") stretches less than 6% when subjected to an initial stress of 0.5 g / d, 20 to 100 g / winding yarns at a radial velocity with a birefringence of 0.02 to 0.04 with an initial modulus of d, with a force-strain curve extending at least 150% when subjected to 3.5 g / d, and (D) A polyethylene terephthalate multifilament yarn is prepared, including the step of multi-stretching the wound yarn to a total draw ratio of 3.0 times or less.

In addition, the present invention satisfies the following physical properties and at the same time less than 2.5% when subjected to an initial stress of 2.0 g / d, having an initial modulus value of 80 to 120 g / d, and subjected to a medium stress of 6.0 g / d When stretching to less than 7.5% and stretching from a tensile strength of 9.5 g / d until the yarn is cut, a polyethylene terephthalate soft gentleman with a force-strain curve.

(1) intrinsic viscosity of 1.0 to 1.2, (2) strength of 9.5 g / d or more, (3) elongation of 12% or more, (4) birefringence of 0.20 or more, (5) density of 1.385 to 1.395, (6) 6 to 7% shrinkage

The polyethylene terephthalate polymer used in the present invention contains at least 85 mol% of ethylene terephthalate units, and preferably consists only of ethylene terephthalate units.

Optionally, the polyethylene terephthalate can incorporate small units derived from one or more ester-forming components other than ethylene glycol and terephthalene dicarboxylic acid or derivatives thereof as copolymer units. Examples of other ester forming components copolymerizable with polyethylene terephthalate 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, bibenzoic acid, adipic acid, sebacic acid, azelaic acid.

The polyethylene terephthalate chip according to the present invention preferably melt-mixes terephthalic acid (TPA) and ethylene glycol raw materials at a ratio of 1.1 to 2.0, and the melt mixture is subjected to transesterification and condensation polymerization to intrinsic viscosity of 0.60 to 0.70. After making a raw chip, the solid phase is polymerized to have an intrinsic viscosity of 1.20 to 1.40 and a moisture content of 30 ppm or less under a temperature of 235 to 245 ° C and a vacuum.

If the intrinsic viscosity of the chip is lower than 1.20, the intrinsic viscosity of the final stretched yarn is lowered, so that super high strength can not be exerted as a treatment cord after heat treatment. Melt spinning becomes impossible. If the moisture content of the chip exceeds 30ppm, hydrolysis occurs during melt spinning.

In the present invention, optionally, during the polycondensation reaction, as a 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 180 to 300 ppm. When less, the polymerization reaction rate is lowered and the polymerization efficiency is lowered. When the amount is higher than 300 ppm, more than necessary antimony metal acts as a foreign material, which degrades radio-stretching workability.

The polyethylene terephthalate chip thus prepared 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 terephthalate chip is passed through the pack 1 and the nozzle 2 at a spinning temperature of preferably 280 to 305 ° C., preferably of 100 to 500 spinning draft ratio (on the first winding roller). Low-temperature melt spinning at a linear velocity / linear velocity) can prevent a decrease in the viscosity of the polymer due to thermal decomposition and hydrolysis. If the draft ratio is less than 100, the uniformity of the cross section of the filament is poor, the drawing workability is significantly lowered. If the draft ratio exceeds 500, the filament breakage occurs during spinning, making it difficult to produce a normal yarn.

In step (B), the melt-discharged yarn (4) of step (A) is passed through a cooling zone (3) to quench and solidify, if necessary, directly from the nozzle (2) to the start point of the cooling zone (3). Install a heating device of a certain length in the distance, that is, the length (L) of the hood.

This zone is called delayed cooling zone or heating zone, which has a length of 260 to 450 mm and a temperature of 320 to 400 ° C. (air contact surface temperature).

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), POY stretches less than 6% when subjected to an initial stress of 0.5 g / d, with an initial modulus of 20 to 100 g / d, and further elongates at least 150% when subjected to 3.5 g / d. It has a force-strain curve and winds the yarn at a spinning speed such that the birefringence is 0.02 to 0.04, with a preferred spinning speed being 1500 to 2500 m / min.

In the present invention, POY's force-strain curve and birefringence are used as factors for controlling the microstructure of the POY yarn.

In particular, in the present invention, when POY yarn is subjected to an initial stress of 0.5 g / d, it is stretched to less than 6%, has an initial modulus of 20 to 100 g / d, and further elongates at least 150% when subjected to 3.5 g / d, It is characterized by having a force-strain curve.

POY having the force deformation curve can be maximized in the stretching process in a subsequent stretching process.

In addition, in the present invention, birefringence of POY is used as a factor for controlling the microstructure of the unstretched phase together with the force-strain curve.

In particular, in the present invention, as described above, only the POY yarn strain curve and the birefringence satisfy the above-described range, thereby obtaining excellent stretchability in the stretching process. This is because if the birefringence of POY is less than 0.02, the crystallization rate is too slow in the drawing step to induce the formation of tie chains between the crystals. If the birefringence exceeds 0.04, the crystallization progresses too rapidly during stretching. It is difficult to manufacture ultra high strength yarn because of its low elongation.

In step (D), the yarn having passed through the first drawing roller 6 is passed through a series of drawing rollers 7, 8, 9 and 10 by spin draw method while the total draw ratio is 3.5 times or less, preferably The final stretched yarn 11 is obtained by stretching at 2.0 to 3.0 times.

In addition, in the present invention, the POY yarn is drawn in three stages, and each drawing temperature is 95 ° C. or less than the POY yarn glass transition temperature, which is lowered when the drawing temperature is lower than the glass transition temperature. If it exceeds C, crystallization during the stretching proceeds rapidly, making it difficult to stretch in three steps.

While narrowing the distance between the nozzle and the top of the cooling section as possible during spinning, it is advantageous to have high strength in the final stretched yarn.However, for spinning with high viscosity, if the distance from the nozzle to the bottom of the heating device is less than 420 mm during spinning, Since there is a radial block of about 20mm in length directly under the nozzle, when using a 400mm length heater, the distance from the bottom of the nozzle to the bottom of the heater becomes 420mm), and the distance between the bottom of the heater and the top of the chiller is 260 ~ 420mm. If off, POY's non-uniformity will be generated to a large extent, and it will not be possible to extend the normal properties.

Stretched polyethylene terephthalate fibers prepared according to the method of the present invention satisfy the following physical properties and at the same time stretch under 2.5% when subjected to an initial stress of 2.0 g / d, and have an initial modulus value of 80 to 120 g / d, It has a force-strain curve that elongates less than 7.5% when subjected to medium stress of 6.0 g / d and elongates from a minimum tensile strength of 9.5 g / d until the yarn is cut.

(1) intrinsic viscosity of 1.0 to 1.2, (2) strength of 9.5 g / d or more, (3) elongation of 12% or more, (4) birefringence of 0.20 or more, (5) density of 1.385 to 1.395, (6) 6 to 7% shrinkage

In the present invention, the ultra-high strength polyetherene terephthalate fiber that satisfies the above properties are twisted with a twisting machine to produce a raw cord, and then weaved and immersed in a dipping solution to provide a polyetherene terephthalate 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 polyetherene terephthalate stretched yarn produced by the above method by twisting two wound yarns with a direct twisting machine in which the twisting and joining is carried out at the same time 'raw cord (Raw) Cord) '. Raw cords are manufactured by adding Ply Twist to the polyetherene terephthalate 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, elongation, central body, fatigue resistance, etc. change depending on the level of twisting (years) imparted to the polyetherene terephthalate. In general, when the kink is high, strength tends to decrease, and corpse and body tend to increase. The fatigue fatigue tends to improve with the increase of twist. The soft water of the polyetherene terephthalate tire cord manufactured in the present invention was produced at 300/300 TPM to 500/500 TPM at the same time as the upper and lower edges. It is easy to maintain a straight line without showing twisting etc., and maximizes the physical expression. At this time, if less than 300/300 TPM, the extension of the raw cord is reduced and fatigue fatigue is easy to fall, and if it exceeds 500/500 TPM, the strength is largely unsuitable for the tire cord.

In the present invention, if the number of years of the upper / lower edge is selectively given differently, the upper edge is adjusted to 350TPM to 450TPM, the lower edge is adjusted to 300TPM to 450TPM to produce a live cord with different stations. The reason why the upper and lower stations are differently produced is that the lower the number of stations within the optimum properties of the raw cord, the lower the cost of the yarn and the more the economic benefits. 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 of the PET fiber surface 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 ultra high strength polyetherene terephthalate company according to the invention uses two bath dipping. The dipping bath uses a known dipping bath for the tire cord.

The present invention is a material of the carcass ply of a pneumatic radial tire, which is a polyetherene terephthalate dip having excellent high temperature properties, shape stability, and strength produced from the ultra high strength polyetherene terephthalate fiber produced by the above-described method. By replacing cords, the technical challenge is to provide high performance pneumatic radial tires with improved shape stability and fatigue performance and flatness of 0.70 or less.

Particularly, according to the present invention, the polyetherene terephthalate fiber used for the carcass ply has to have elongation of less than 2.5% when the stress is less than 2.0 g / d. If the elongation is more than 2.5%, the severe deformation of the carcass ply The steering stability is greatly reduced. In addition, in the present invention, it is necessary to have a force-strain curve that stretches less than 7.5% when subjected to a stress of 6.0 g / d. If the stretch rate exceeds 7.5%, carcass deformation is easily generated, and the pressure bearing capacity as a pressure vessel is increased. Falls.

Specifically, a tire as shown in FIG. 4 is manufactured. More specifically, the carcass ply reinforcement cord 13 using the ultra high strength polyetherene terephthalate deep cord manufactured according to the present invention has a total denier of 2,000 d to 8,000 d. The carcass ply 12 comprises at least one layer of carcass ply reinforcement tire cords 13. In the carcass ply 12, it is preferable that the deep cord reinforcement density is 15 to 35 EPI because the mechanical properties of the carcass ply are sharply deteriorated when the reinforcement density is less than 15 EPI, and when it exceeds 35 EPI, it is economically disadvantageous. to be.

The carcass ply 12 having the radially outer fly turnup 14 preferably comprises one to two layers of carcass cord. The carcass ply reinforcement 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 carcass ply reinforcement cords 13 are 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.

4 will be described below in more detail.

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 a particular embodiment of the 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 of 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 face 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 center surface. However, the belt structure 18 may comprise any number of plies, and may preferably be arranged in the range of 16 ° to 24 °. The belt structure 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 belt cords 21 and 22 of the belt structure 18 are made of steel cords and have a 2 + 2 structure, but can be produced in any structure. The cap ply 19 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 to the circumferential direction of the tire, thereby increasing the speed 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 24 may be used, but preferably, 1-2 layers of cap ply and also one or two layers of edge plies are reinforced.

Hereinafter, the configuration and effects 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.

(1) Intrinsic viscosity (I.V.)

After dissolving 0.1 g of the sample in a reagent (90 ° C.) mixed with phenol and 1,1,2,3-tetrachloroethanol at a weight ratio of 6: 4 for 90 minutes to obtain a concentration of 0.4 g / 100 ml, Ubbelohde ) The solution was transferred to a viscometer, held for 10 minutes in a 30 ° C thermostatic bath, and the number of seconds of the drop of the solution was determined using a viscometer and an aspirator. The falling seconds of the solvent was also determined in the same manner, and then the R.V. and I.V. values were calculated by the following equations (1) and (2).

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

After leaving for 24 hours at 25 ° C and 65% RH, Instron's slow extension type tensile tester was used. After twisting 80 TPM (80 twist / m), the sample was measured at 250 mm and tensile speed of 300 m / min. do. The elongation at specific load imposed here represents the elongation at the point of 4.5 kg load.

(3) 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

(4) E-S

Elongation under constant load is referred to as intermediate elongation (E) in the present invention, where the load means 4.5 kg. The reason for evaluating elongation at 4.5kg is because it considers the maximum load per tire cord. And 'S' means the dry heat shrinkage of the above (d), 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 median shrinkage of the cord changes. 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, the force generation due to the deformation of the tire is large, so it is easier to maneuver, and on the contrary, it is possible to use the smaller deformation to produce the same tension. Can be. Therefore, the value of 'E-S' is used as a physical property value to determine the superiority of the code 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 4.5kg + Shrinkage

(5) 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).

(6) even with fatigue

The fatigue strength of the tire cord was measured by using a Goodrich Disc Factigue Tester which is commonly used for fatigue testing of tire cords. The fatigue test conditions were 120 ° C, 2500 RPM, 12% compression, and 6% elongation. After the fatigue test, the rubber was swelled by immersion in tetra chloro ethylene solution for 24 hours, and the rubber and cord were separated. Was measured. The residual strength was measured according to the method (3) above using a conventional tensile strength tester.

(7) adhesion

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

(8) birefringence

It is measured by the following method using a polarizing microscope equipped with a Berek compensator.

Place the polarizer and analyzer in a vertical position (→ orthogonal polarization).

Insert the compensator at 45 ° angle (45 ° to the microscope N-S direction) with the analyzer.

Place the sample on the stage and place it in the diagonal position (nγ-direction: 45 ° angle with the polarizer) (the black compensation band appears at this position).

• Rotate the micrometer screw on the compensator to the right and read the scale at the darkest point of the sample.

· Rotate in the opposite direction again and read the scale at the darkest point.

• Divide the difference between the readings above by 2 and find the retardation (γ, nm) by referring to the table made by the manufacturer.

Remove the compensator and analyzer and measure the thickness of the sample (d, nm) using an eyefilar micrometer.

Obtain the birefringence (Δn) of the sample by substituting the measured retardation and thickness into the following equation.

 Δn = γ / d

Example 1

A solid-state polymerized polyethylene terephthalate chip having an intrinsic viscosity (I.V.) of 1.25 and a moisture content of 10 ppm containing 220 ppm of antimony metal was prepared. The prepared chips were melt spun using an extruder at a discharge rate of 600 g / min and a spinning draft ratio of 250 at a temperature of 288 ° C. Subsequently, the discharged yarns are solidified by passing a heating zone (ambient temperature 380 ° C.) and a 500 mm long cooling zone (20 ° C., cooling air blowing with a wind speed of 0.5 m / sec) directly below the nozzle and then oiled with a spinning emulsion. Ring. The POY was wound at a spinning speed of 1800 m / min, the first stage stretching was 1.9 times at 60 ° C, the second stage stretching was 1.2 times at 60 ° C, and the third stage stretching was 1.3 times at 75 ° C, 230 It was heat set at 占 폚, 2.5% relaxed, and then wound to prepare a final drawn yarn (yarn) of 1000 denier.

After two strands of yarn were rolled up and down at 430 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 2.0% at 170 ° C. in a drying area. After drying for 150 seconds and heat setting for 150 seconds under 6.0% stretching at 240 ° C. in a high temperature stretching area, immersing in RFL again, drying for 100 seconds at 170 ° C. and heat setting for 40 seconds under 240 ° C. Was prepared.

The physical properties of the drawn yarn and the dip cord thus prepared are shown in Tables 2 and 3 below.

[Examples 2-3 and Comparative Examples 1-3]

The stretched yarn and the deep cord were manufactured by performing experiments in the same manner as in Example 1 while changing the intrinsic viscosity of the chip, the spinning temperature, the length or temperature of the heating zone, or the birefringence of the POY yarn as shown in Table 1 below. .

The physical properties of the drawn yarn and the dip cord thus prepared are shown in Table 2 below.

 ■: Poor appearance, ■■: Poor appearance, no manufacturing code.

Example 4

Radial tires made using the ultra-high strength polyetherene terephthalate deep cords produced by Example 1 of the present invention have a carcass ply with radially outer fly turn-up, and the carcass ply is The prepared ultra high strength polyetherene terephthalate deep cord was installed to include 1 to 2 layers. At this time, the specifications of the carcass cord were as shown in Table 4 below, and were oriented at a 90 degree angle with respect to the circumferential intermediate surface of the tire. The fly turn up 4 has a height of 40 to 80% with respect to the maximum tire cross-sectional height. The bead part 5 had a bead core 6 having a high strength steel wire having a diameter of 0.95 to 1.00 mm 4 × 4 and a bead filler 7 having a shore A hardness of 40 or more. The belt 8 is reinforced by a belt reinforcement layer with a top layer of cap ply 9 and a first layer of edge ply 14 so that the cap fly cord in the cap ply 9 is parallel to the circumferential direction of the tire. Placed.

[Comparative Example 4]

A tire was manufactured in the same manner as in Example 4, except that a cord material for manufacturing a tire was used for the polyetherene terephthalate deep cord prepared in Comparative Example 3.

[Comparative Example 5]

A tire was manufactured in the same manner as in Example 4, except that rayon was used as a cord material for manufacturing a tire.

The 225/60 R15 V tire manufactured according to Example 4 and Comparative Example 4-5 was 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 preventing noise in the audible frequency range. (dB), and the steering stability and riding comfort were evaluated by the experienced driver in the course of 5 points out of 100 points on the test course, and the results are shown in Table 5 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. .

division Example 4 Comparative Example 4 Comparative Example 5 Tire weight (kg) 9.85 9.89 10.12 Ride 100 94 95 Steering stability 100 95 95 durability OK OK OK Uniformity 100 93 97 Noise (dB) 61.4 63.2 63.2

As a result of the test results of Table 5, the tire according to the present invention (Example 4) can be seen that the weight of the tire is reduced compared to the case of applying a rayon cord to the carcass (Comparative Example 5), and thus the rolling resistance It can be seen that reduction is possible. In addition, in terms of performance, in the case of the present invention using the ultra-high polyetherene terephthalate cord produced by the present invention for carcass, the effect was excellent in terms of riding comfort, steering stability and noise reduction, and also the tire uniformity It can be seen that the improvement.

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. .

1 is a schematic diagram illustrating a spinning process of a polyetherene terephthalate fiber according to the present invention.

Figure 2 is an example of the force-strain curve of the polyetherene terephthalate POY company of the present invention.

3 is an example of a force-strain curve of the polyetherene terephthalate stretched yarn of the present invention.

Figure 4 is a schematic diagram showing the structure of a tire for a passenger car manufactured using the high strength polyetherene terephthalate deep cord according to the present invention.

※ Brief description of the main symbols in the drawing

11: tires 12: carcass fly

13: carcass fly reinforcement cord 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

Claims (5)

In the radial pneumatic tire having a flatness ratio of 0 to 0.70, A pair of parallel bead cores and at least one radial carcass ply wound around the bead core, a belt layer laminated on the outer circumferential side of the carcass, and a circumferential belt reinforcement layer formed on the outer circumferential side of the belt layer; The carcass ply includes a deep cord made of polyetherene terephthalate fiber, The polyethylene terephthalate fiber meets the following physical properties and simultaneously stretches from 0 to less than 2.5% when subjected to an initial stress of 2.0 g / d, has an initial modulus of 80 to 120 g / d, and has a medium term of 6.0 g / d. A radial pneumatic tire, characterized by having a force-strain curve that stretches from 0 to less than 7.5% when subjected to stress and extends from the tensile strength of 9.5 g / d until the yarn is cut. (1) intrinsic viscosity of 1.0 to 1.2, (2) strength of 9.5 g / d or more and 10.5 g / d or less, (3) elongation of 12% or more, (4) birefringence of 0.20 or more, (5) density of 1.385 to 1.395 , (6) shrinkage of 6-7% 2. The radial pneumatic tire according to claim 1, wherein the carcass ply is used in one or two layers. The radial pneumatic tire according to claim 1, wherein the deep cord reinforcement density in the carcass ply is 15 to 35 EPI. The radial pneumatic tire according to claim 1, wherein the dip cord has a twist number of 300 to 500 TPM. The radial pneumatic tire according to claim 1, wherein the deep cord is E2.25 (expansion rate at 2.25 g / d) + FS (free shrinkage rate) of 0 to 6.5%.

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