KR101231096B1 - Drawn poly(ethyleneterephthalate) fiber, tire-cord and tire comprising the same - Google Patents

Abstract

The present invention relates to polyethylene terephthalate stretched yarn, tire cords and tires comprising the same, which exhibits improved modulus and morphological stability with excellent shrinkage stress.

The polyethylene terephthalate stretched yarn contains 90 mol% or more of polyethylene terephthalate, and heat treated at 230 ° C. for 1 minute under tension under a super load of 0.02 g / d to 3.0E + 22 to 8.0E + 22 pieces / cm ³ . It has a crosslink density.

PET, stretched yarn, cord, shrinkage stress, crosslink density, modulus, shape stability

Description

Polyethylene terephthalate stretched yarn, tire cord and tire comprising same {DRAWN POLY (ETHYLENETEREPHTHALATE) FIBER, TIRE-CORD AND TIRE COMPRISING THE SAME}

The present invention relates to a polyethylene terephthalate stretched yarn, a tire cord and a tire comprising the same. More specifically, the present invention relates to polyethylene terephthalate stretched yarn, tire cords and tires comprising the same, which exhibits improved modulus and morphological stability with good shrinkage stress.

The tire is a composite of fiber / steel / rubber and generally has a structure as shown in FIG. 1. In other words, steel and fiber cords serve to reinforce rubber and form a basic skeletal structure in the tire. In other words, compared to the human body is a bone-like role.

The performance required for the cord as a tire reinforcement is fatigue resistance, shear strength, durability, resilience and adhesion to rubber. Therefore, a cord of appropriate material is used according to the performance required for the tire.

Commonly used materials for the cord are rayon, nylon, polyester, steel, and aramid, and rayon and polyester are used for body plies (also called carcasses) (6 in FIG. 1), and nylon is mainly a cap. In the ply (4 in FIG. 1), and steel and aramid are mainly used in the tire belt portion (5 in FIG. 1).

The following briefly illustrates the tire structure and its characteristics shown in FIG. 1.

Tread (1): This part is to be in contact with the road surface to provide the necessary frictional force for braking and driving, to have good abrasion resistance, to withstand external shocks, and to generate little heat.

Body Ply (or Carcass) (6): A layer of cord inside the tire, which must support loads, withstand impacts, and be resistant to flexing movements while driving.

Belt (5): Located between the body plies, consisting of steel wires in most cases to mitigate external shocks and maintain a wide tread ground to provide excellent driving stability.

Side Wall (3): refers to the rubber layer between the lower part of the shoulder (2) from the bead (9) and serves to protect the body ply (6) inside.

BEAD (9): A square or hexagonal wire bundle with rubber coating on the wire that rests and secures the tire to the rim.

Inner Liner (7): Located on the inside of the tire instead of the tube, this prevents air leakage and enables pneumatic tires.

CAP PLY (4): A special cord paper placed on the belt of some passenger radial tires that minimizes belt movement when driving.

APEX (8): A triangular rubber filler used to minimize the dispersion of beads, to mitigate external impacts, to protect the beads, and to prevent the ingress of air during molding.

Recently, the development of tires suitable for high-speed driving is required with the advancement of passenger cars. Accordingly, high-speed driving stability and high durability of tires are recognized as very important characteristics. In addition, in order to satisfy the characteristics, the performance of the cap ply cord material is more important than ever.

The steel belts present in the tire are generally arranged in an oblique direction, but at high speeds, such steel belts tend to move in the circumferential direction by centrifugal force. At this point, the end of the pointed steel belt breaks rubber or generates cracks. Doing so may cause separation between belt layers and deformation of tire shape. Cap fly acts to increase the high speed durability and driving stability by catching the movement of the steel belt to suppress the separation between layers and form deformation of the tire.

In general, the cap fly cord is mainly made of nylon 66. In the case of the nylon 66 cord, high shrinkage stress is expressed under a high temperature environment corresponding to the internal environment of the tire at high speed, thereby wrapping the steel belt and suppressing the movement of the belt. However, these nylon 66 cords have a low modulus and glass transition temperature at high temperatures, and thus have low morphological stability, so that partial deformation may occur due to tires and automobiles' own loads, which may cause them to stray while driving. There is this.

In order to solve these disadvantages, polyethylene terephthalate (PET) cord, which has a high modulus, has been used as a cap ply cord because of its relatively high modulus, but a cord made of general PET fiber has a low shrinkage stress, thereby effectively suppressing the movement of the steel belt. It was difficult to do so and was difficult to apply as a capfly code.

In addition, in the case of a cord made of PET High Modulus Low Shrinkage (HMLS) fiber, which is widely used as an industrial fiber, it is possible to increase the tension at the time of manufacturing the deep cord to lower the corpse and to increase the number of shrinkage stresses to some extent. In this case, the modulus is lowered, but the shape stability is lowered.

Accordingly, the present invention is to provide a polyethylene terephthalate stretched yarn that enables the provision of a tire cord exhibiting improved modulus and form stability with excellent shrinkage stress.

In addition, the present invention is to provide a polyethylene terephthalate tire cord comprising the stretched yarn.

The present invention also provides a tire comprising the polyethylene terephthalate tire cord.

The present invention comprises 90 mol% or more of polyethylene terephthalate, 3.0E + 22 ~ 8.0E + 22 pieces / cm ³ , preferably after heat treatment at 230 ° C. for 1 minute under tension under 0.02 g / d superload Provided is a polyethylene terephthalate stretched yarn having a crosslink density of 5.0E + 22 to 8.0E + 22 pieces / cm ³ .

The present invention also provides a polyethylene terephthalate tire cord comprising the stretched yarn.

The present invention also provides a pneumatic tire comprising the tire cord.

 Hereinafter, a polyethylene terephthalate stretched yarn, a tire cord, a manufacturing method thereof, and a tire including the same according to a specific embodiment of the present invention will be described in detail. It will be apparent to those skilled in the art, however, that this is not intended to limit the scope of the invention, which is set forth as an example of the invention, and that various modifications may be made to the embodiments within the scope of the invention.

In addition, throughout this specification, "comprising" or "containing ", unless specifically stated, refers to including any and all components (or components) Can not be interpreted as excluding.

Polyethylene terephthalate (hereinafter referred to as "PET") The drawn yarn is produced by melting and spinning PET to produce an undrawn yarn, and then drawing the undrawn yarn, then twisting the PET drawn yarn and immersing in an adhesive to dip It is possible to produce tire cords in the form of cords.

Therefore, the properties of the undrawn yarn produced through melt spinning of the PET and the drawn yarn produced by drawing them are directly or indirectly reflected in the physical properties of the tire cord.

Particularly, as a result of the experiments of the present inventors, as the tire cords are manufactured from PET stretched yarns having predetermined characteristics, PET tire cords that can be preferably used as cap ply cords exhibit excellent modulus and shape stability with excellent shrinkage stress. It has been found that it can be obtained.

In accordance with one embodiment of the present invention there is provided a PET drawn yarn having a predetermined characteristic. Such PET stretched yarn contains 90 mol% or more of polyethylene terephthalate, 90 mol% or more of polyethylene terephthalate, and is heat treated at 230 ° C. for 1 minute under tension under a super load of 0.02 g / d, 3.0E + 22 ~. It has a crosslink density of 8.0E + 22 pieces / cm <^3> , Preferably, 5.0E + 22-8.0E + 22 pieces / cm <^3> . In addition, such PET stretch yarn has a crosslink density of 2.0E + 22 ~ 6.0E + 22 pieces / cm ³ , preferably 2.5E + 22 ~ 6.0E + 22 pieces / cm ^{3 in} the state before heat treatment at 230 ° C. Can have

The PET fibers constituting the PET stretched yarn are partially crystallized, and are composed of crystalline regions and amorphous regions including amorphous chains. However, PET stretched yarn according to an embodiment of the present invention has more crosslinks formed in the amorphous region, and has a higher crosslink density per unit volume than the stretched yarn made of general PET fibers or HMLS fibers. Since the PET stretched yarn contains a large number of crosslinks per unit volume, the alignment of the amorphous chains included in the amorphous region of the PET fiber has a low degree of ruggedness and a high degree of tension. Therefore, the PET stretched yarn has very developed crystal structure and excellent orientation characteristics, and thus exhibits excellent shrinkage stress equivalent to that of the stretched yarn made of HMLS fiber or nylon 66 fiber, but is significantly larger than those of the HMLS drawn yarn or nylon 66 drawn yarn. Low shrinkage. Therefore, tire cords made of such PET stretched yarns can also be more suitably applied as cap ply cords for tires because they can exhibit improved modulus and morphological stability due to low shrinkage with excellent shrinkage stress.

On the other hand, PET stretched yarn according to an embodiment of the present invention includes more than 90 mol% PET in order to exhibit suitable physical properties for the tire cord, if the PET stretcher contains less than 90 mol% PET PET Gentleman and tire cords produced therefrom are difficult to exhibit desirable overall physical properties. Hereinafter, the term PET refers to a case in which PET is 90 mol% or more without special description.

In addition, PET drawn yarn according to an embodiment of the present invention after heat treatment at 230 ° C. for 1 minute under tension under a super load of 0.02 g / d 3.0E + 22 ~ 8.0E + 22 pieces / cm ³ , preferably 5.0 E + 22 ~ 8.0E + 22 pieces / cm ³ crosslink density, 2.0E + 22 ~ 6.0E + 22 pieces / cm ³ , preferably 2.5E + 22 ~ 6.0E + 22 in the state before such heat treatment It may have a crosslink density of dog / cm ³ , this crosslink density can be calculated from the following equation (1).

[Equation 1]

N = σ / kT (λ ² -1 / λ)

In Equation 1, N represents the number of crosslinks per unit volume, that is, the crosslink density, λ represents an expansion ratio defined by 1 / (shrinkage of 1-PET stretched yarn), k represents a Boltzmann constant, T is Represents absolute temperature, and σ represents shrinkage stress per unit area of PET stretched yarn.

On the other hand, PET stretched yarn according to an embodiment of the present invention as described above may be produced by melt spinning PET to produce a non-drawn yarn, a method of stretching the non-drawn yarn, as described above, the specifics of each step Conditions or a method of proceeding may be directly or indirectly reflected on the physical properties of the PET stretched yarn can be produced PET stretched yarn having the above-described properties.

In particular, the polyethylene terephthalate non-drawn yarn having a crystallization degree of 25% or more and an amorphous orientation index (AOF) of 0.15 or less is obtained by adjusting the melt spinning condition of the PET, and by using the same, the tension under a predetermined load It has been found that PET stretched yarn according to one embodiment of the invention having a higher crosslink density after heat treatment or even before such heat treatment.

When manufacturing such a PET stretched yarn, one of the predicted principles is described as non-limiting as follows.

As described above, the PET fibers basically have a crystallized form, and are composed of a crystalline region and an amorphous region. However, the PET non-drawn yarn obtained under controlled melt spinning conditions has a higher degree of crystallization than previously known PET non-drawn yarn due to the orientation crystallization phenomenon, and thus exhibits a high degree of crystallinity of 25% or more, preferably 25 to 40%. Due to this high degree of crystallinity, PET stretched yarns produced from the PET non-stretched yarns also have a more advanced crystal structure.

At the same time, the PET non-drawn yarn exhibits an amorphous orientation index of 0.15 or less, preferably 0.08 to 0.15, which is significantly lower than previously known PET non-drawn yarn. At this time, the amorphous orientation index indicates the degree of orientation of the chains included in the amorphous region in the unstretched yarn, and has a lower value as the matting of the chains in the amorphous region increases. That is, in general, when the amorphous orientation index is lowered, the disorder is increased so that the chains of the amorphous region are not relaxed structures but relaxed structures. However, the PET non-drawn yarn obtained under controlled melt spinning conditions forms a fine network structure due to the molecular chains that make up it slip during the spinning process. For this reason, the PET unstretched yarn can be in a strained structure of the chain of the amorphous region while the amorphous orientation index is significantly lowered, thereby exhibiting a highly developed crystal structure and excellent orientation characteristics.

Due to the advanced crystal structure and excellent orientation properties of the PET non-drawn yarn, from the PET non-drawn yarn showing the high crystallinity and low amorphous orientation index, it is possible to provide a PET drawn yarn with a high crosslink density according to one embodiment of the invention. It turned out to be possible.

Hereinafter, the manufacturing method of the PET stretcher in more detail for each step as follows.

In the method for producing PET stretched yarn, first, PET unstretched yarn is produced by melt spinning PET, which exhibits the above-described high crystallinity and low amorphous orientation index.

In this case, the melt spinning process may be performed under a higher spinning tension to obtain PET non-drawn yarn that satisfies such crystallinity and amorphous orientation index. For example, the melt spinning process may proceed under a spin tension of at least 0.85 g / d, preferably 0.85 to 1.25 g / d. In addition, in order to obtain such a high spinning tension, for example, the rate of melt spinning the PET can be adjusted to 3800 to 5000 m / min, preferably to 4000 to 4500 m / min.

As a result of the melt spinning process of PET under such a high spinning tension and optionally high spinning speed, the crystallization degree is increased with the orientation crystallization phenomenon of PET, and the molecular chains forming the PET slide during the spinning process to form a fine network structure. It has been found that PET non-drawn yarns can be obtained that satisfy the crystallinity and amorphous orientation index described above. However, adjusting the spinning speed to 5000 m / min or more is difficult to realize in reality and it is difficult to proceed with the cooling process due to excessive spinning speed.

In addition, in the manufacturing process of such PET non-stretched yarns, chips having an intrinsic viscosity of 0.8 to 1.3 dl / g and containing 90 mol% or more of polyethylene terephthalate can be melt spun as the PET.

As described above, in the manufacturing process of the PET non-stretched yarn, it is possible to impose conditions of higher spinning tension and optionally high spinning speed. It is preferable that it is 0.8 dl / g or more. However, it is preferable that the intrinsic viscosity is 1.3 dl / g or less in order to prevent the molecular chain cutting and the pressure increase due to the amount of discharge from the spin pack due to the rise of the melting temperature of the chip.

In addition, the chip is preferably spun through a mold designed so that the fineness of the monofilament is 2.0 to 4.0 denier, preferably 2.5 to 3.0 denier. That is, in order to reduce the possibility of trimming due to interference between each other during the generation of trimming and cooling during spinning, the denier of the monofilament should be 2.0 denier or more, and the fineness of the monofilament in order to give a high spinning tension by increasing the radiation draft Is preferably 4.0 denier or less.

Further, after the PET is melt-spun, the PET non-drawn filament can be produced by adding a cooling step. It is preferable to proceed with such a cooling process by the method of adding the cooling wind of 15-60 degreeC, and it is preferable to adjust the cooling air quantity to 0.4-1.5 m / s in each cooling wind temperature conditions. As a result, PET non-drawn yarn that satisfies the above-mentioned crystallinity and amorphous orientation index can be produced more easily.

On the other hand, after producing the PET non-drawn yarn that satisfies the above-described crystallinity and amorphous orientation index through this spinning step, the non-drawn yarn is drawn to prepare a drawn yarn. At this time, the stretching step may proceed under a draw ratio condition of 1.0 ~ 1.55. The PET unstretched yarn has advanced crystal regions, and chains of amorphous regions also have a low degree of orientation and form fine networks. Therefore, when the drawing process is carried out under a high draw ratio condition of more than 1.55, cutting or mousse may occur in the drawn yarn, and thus, PET drawn yarn manufactured through the above-described manufacturing method is also difficult to exhibit desirable physical properties. In addition, when the stretching process is performed under a relatively low stretching ratio, the strength of the PET stretched yarn and tire cord manufactured therefrom may be partially lowered. However, under an elongation ratio of 1.0 or more, for example, since it is possible to manufacture a PET tire cord having a strength of 6 g / d or more suitable for application to a capply cord or the like, the stretching process may be preferably performed under an elongation ratio of 1.0 to 1.55. Can be.

As PET stretched yarn prepared by the above-described manufacturing method is manufactured using PET non-stretched yarn which exhibits highly developed crystal structure and excellent orientation characteristics, excellent crosslinking properties before or after heat treatment are excellent in general physical properties according to an embodiment of the present invention. It can exhibit excellent properties such as density and thus high shrinkage stress and low shrinkage.

Meanwhile, according to another embodiment of the present invention, a PET tire cord including PET stretched yarn is provided.

The PET tire cord includes a PET stretch yarn according to one embodiment of the invention having high shrinkage stress and low shrinkage rate due to high crosslink density. Therefore, PET tire cord according to another embodiment of the present invention may also exhibit excellent modulus and shape stability due to high shrinkage rate, along with excellent shrinkage stress. Therefore, the PET tire cord can, for example, effectively wrap the steel belt in the pneumatic tire and effectively suppress its movement, while reducing the risk of deformation caused by the tire and the vehicle's own load, thereby reducing the risk of driving the vehicle. The rattling disadvantages can be suppressed. As a result, the tire cord may be applied as a cap ply cord or the like to improve the controllability or ride comfort of the vehicle.

The PET tire cord is not particularly limited in form, and may have a form equivalent to that of a conventional cap fly cord. More specifically, the PET tire cord is a deep cord having a total fineness of 1000 to 5000 denier (d) per cord, a number of plies of 1 to 3, and a twist number of 200 to 500 TPM according to the form of a conventional cap ply cord. It may have a form.

In addition, the PET tire cord is 5 to 8 g / d, preferably 5.5 to 7 g / d strength, 1.5 to 5.0%, preferably 2.0 to 3.5% of the core (elongation at 4.5 kgf load), 10 to A stretch of 25%, preferably 15-25%, and a shrinkage (177 ° C., 30 g, 2 min) of 0.5 to 5.0%, preferably 2.0 to 5.0%. As the tire cord exhibits various physical properties such as strength or elongation in this range, the tire cord can be suitably applied as a capfly cord or the like.

The tire cord may be applied as a cap ply cord of the pneumatic tire. The tire to which the cap ply cord is applied is suppressed by the partial deformation of the cap ply cord and the deformation of the tire accordingly, thereby reducing the flaw of driving during the driving of the vehicle and improving the control or ride comfort of the vehicle. In addition, since the tire cord has various physical properties such as high shrinkage stress, strength, or elongation, which can be preferably used as a capfly cord, the tire to which the capfly cord is applied can exhibit stable high-speed driving performance.

However, the above description has been mainly assumed a case where the PET tire cord according to another embodiment of the invention is used as a cap ply cord, but the use of such a PET tire cord is not limited thereto, and other body ply cords and the like. Of course, it can also be used for purposes.

On the other hand, the PET tire cord may be manufactured in the form of a dip code by immersing in the adhesive after the twisted yarn PET stretched yarn according to an embodiment of the invention, according to the manufacturing method of a conventional tire cord. Such a twisted yarn weaving process and a dipping process are in accordance with conventional tire cord manufacturing process conditions and methods.

As described above, the tire cords thus prepared may have a form having a total fineness of 1000 to 5000 denier, plies of 1 to 3, and a twist of 200 to 500 TPM, and excellent physical properties as described above. For example, it can exhibit high shrinkage stress, high modulus and good shape stability.

As described above, the PET stretched yarn of the present invention can exhibit low shrinkage as well as excellent shrinkage stress due to high crosslink density. Thus, such PET stretched yarns can be used to provide tire cords that exhibit high modulus and excellent morphological stability due to low shrinkage with good shrinkage stress.

Such tire cords are preferably used as cap ply cords of pneumatic tires, and can effectively suppress the movement of the steel belt to enable high-speed driving and reduce the possibility of partial deformation caused by tires and automobiles' own load. The disadvantage of rattling while driving the vehicle can be suppressed.

Therefore, using the tire cord and the tire including the tire can improve the controllability or ride comfort of the vehicle.

Hereinafter, the configuration and operation of the invention through the preferred embodiments of the invention will be described in more detail. However, the scope of the invention is not limited by these embodiments, which are merely presented as an example.

Example 1

A PET polymer having an intrinsic viscosity of 1.05 dl / g was used, and a non-drawn yarn was prepared by melt spinning and cooling the PET polymer according to a conventional manufacturing method at a spinning speed of 4500 m / min under a spinning tension of 1.15 g / d. The gentleman was drawn, heat-set and wound at a draw ratio of 1.30 to prepare a PET drawn yarn of Example 1.

Example 2

During the manufacturing process of PET stretched yarn, unstretched yarn is prepared by melt spinning and cooling the PET polymer at a spinning speed of 4000 m / min under a spin tension of 0.92 g / d, and stretching, heat setting and winding the undrawn yarn at a draw ratio of 1.46. PET stretched yarn of Example 2 was prepared in the same manner as in Example 1 except that the PET stretched yarn was prepared.

Examples 3-6

During the manufacturing process of PET stretched yarn, the PET stretched yarns of Examples 3 to 6 were respectively manufactured in the same manner as in Example 1 except that the spinning speed, the radial tension, the draw ratio or the intrinsic viscosity conditions were changed as shown in Table 1 below. Prepared.

[Table 1]

Condition Example 3 Example 4 Example 5 Example 6 Spinning speed (m / min) Same as Example 1 Same as Example 1 3800 4800 Radial tension (g / d) 0.98 1.23 0.86 1.19 Stretching cost 1.24 1.24 1.54 1.16 Intrinsic viscosity
(dl / g) 0.9 1.2 Same as Example 1 Same as Example 1

Comparative example  One

Melt-spun PET polymer with an intrinsic viscosity of 1.05 dl / g at a spinning rate of 3000 m / min under a radial tension of 0.52 g / d for the production of undrawn yarn, except that undrawn yarn was drawn at a draw ratio of 1.8 for the production of drawn yarn. Then, the drawn yarn of Comparative Example 1 was prepared in the same manner as in Example 1.

Comparative Example 2

Melt-spun PET polymer with an intrinsic viscosity of 1.05 dl / g for spinning production at a spinning speed of 2700 m / min under a spinning tension of 0.45 g / d, except for drawing non-stretching yarn with a draw ratio of 2.0 for the production of stretched yarn. Then, the drawn yarn of Comparative Example 2 was prepared in the same manner as in Example 1.

First, the crystallinity and amorphous orientation index (AOF) of PET undrawn yarn obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were measured by the following method, and the measurement results are summarized in Table 2 below:

Crystallinity: After preparing a density gradient tube using CI ₄ , n-heptane, the density was measured and the crystallinity was measured using the following formula.

PET crystallinity (%) =

(At this time, PET is a constant of ρ _a = 1.336 and ρ _c = 1.457.)

-AOF: AOF was calculated by the following equation using the birefringence measured using a polarizing microscope and the crystal orientation index (COF) measured from XRD.

AOF = (birefringence-crystallinity (%) * 0.01 * crystal orientation index (COF) * 0.275) / ((1-crystallinity (%) * 0.01) * 0.22)

[Table 2]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Crystallinity
(%) 36 30 34 36 28 38 9 9 AOF 0.009 0.093 0.015 0.012 0.120 0.002 0.245 0.218

For the stretched yarns prepared according to Examples 1 to 6 and Comparative Examples 1 and 2, shrinkage stress and shrinkage were measured by the following method using a shrinkage behavior tester (manufactured by TestRite, MK-V) as shown in FIG. 2. The crosslink density was calculated from the measured shrinkage stress and shrinkage rate (see Equation 1 below).

Shrinkage stress (N): After the drawn yarns were fixed under a constant load of 0.005 g / d using the shrinkage behavior tester, shrinkage stress was measured under a constant temperature of 180 ° C. At this time, the above shrinkage stress is measured for the stretched yarns themselves of Examples 1 to 6 and Comparative Examples 1 and 2, and heat-treated at 230 ° C. for 1 minute in the stretched state under a super load of 0.02 g / d. Measurement was also made.

Shrinkage (%): The shrinkage rate of the stretched yarn was measured using the above shrinkage behavior tester while maintaining a constant temperature of 180 ° C. under a constant load of 0.005 g / d. At this time, the above shrinkage stress is measured for the stretched yarns themselves of Examples 1 to 6 and Comparative Examples 1 and 2, and heat-treated at 230 ° C. for 1 minute in the stretched state under a super load of 0.02 g / d. Measurement was also made.

[Equation 1]

N = σ / kT (λ ² -1 / λ)

In Equation 1, N represents the number of crosslinks per unit volume, that is, the crosslink density, λ represents an expansion ratio defined by 1 / (shrinkage of 1-PET stretched yarn), k represents a Boltzmann constant, T is Represents absolute temperature, and σ represents shrinkage stress per unit area of PET stretched yarn.

The measurement results of the shrinkage rate and shrinkage stress for the stretched yarn before the heat treatment and the calculation results of the crosslink density are shown in Table 3, and after the stretched yarn was heat treated at 230 ° C. under a taut under a super load of 0.02 g / d. Table 4 shows the measurement results of the shrinkage rate and the shrinkage stress and the calculation results of the crosslink density.

[Table 3]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Shrinkage (%) 7.50 7.60 7.70 7.80 9.00 7.30 13.80 11.70 Shrinkage stress (N) 6.40 6.29 5.92 6.72 5.60 7.02 3.19 3.90 Shrinkage stress per unit area (N / cm ² ) 5760.58 5661.57 5328.53 6048.60 5040.50 6318.63 2871.29 3510.35 Expansion ratio (λ) 1.0810811 1.08225108 1.0834236 1.0845987 1.0989011 1.0787487 1.1600928 1.1325028 Crosslink density
(Dog / cm ³⁾ 3.78E + 22 3.66E + 22 3.40E + 22 3.80E + 22 2.71E + 22 4.27E + 22 9.49E + 21 1.41E + 22

[Table 4]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Shrinkage (%) 2.10 2.15 2.40 2.00 2.80 2.11 4.85 5.00 Shrinkage stress (N) 2.90 2.76 3.10 2.90 2.76 3.13 3.10 2.70 Shrinkage stress per unit area (N / cm ² ) 2610.26 2484.25 2790.28 2610.26 2484.25 2819.08 2790.28 2430.24 Expansion ratio (λ) 1.0214505 1.0219724 1.0245902 1.0204082 1.0288066 1.0215548 1.0509721 1.0526316 Crosslink density
(Dog / cm ³⁾ 6.49E + 22 6.03E + 22 6.05E + 22 6.82E + 22 4.60E + 22 6.97E + 22 2.92E + 22 2.46E + 22

Referring to Tables 3 and 4, the drawn yarns of Examples 1 to 6, compared with the drawn yarns of Comparative Examples 1 and 2, have a significantly higher crosslink density, and a low shrinkage rate, Comparative Example 1 and the general HMLS fibers It is confirmed to exhibit good shrinkage stress equivalent to or greater than 2.

On the other hand, using the drawn yarns of Examples 1 to 6 and Comparative Examples 1 and 2, respectively, tire cords were manufactured by the following method.

First, the twisted yarns of the total fineness 1000 denier prepared in each of Examples 1 to 6 and Comparative Examples 1 and 2 were twisted and combined with two strands of the lower twisted yarn Z-bonded to 430 TPM with the same twisted number of S-strands. After immersing and passing through the RFL adhesive solution, it was dried and heat-treated to prepare a tire cord in the form of a deep cord.

The composition and drying and heat treatment conditions of the RFL adhesive solution were the same as those of the conventional PET tire cord.

The physical properties of each tire cord thus manufactured were measured as follows, and the measurement results are shown in Table 5.

Shrinkage stress: The shrinkage stress of each tire cord was measured for 2 minutes at a temperature of 0.0565 g / d and 180 ° C. under superload using a Testrite MK-V instrument from Testrite, UK having the schematic configuration shown in FIG. 2.

LASE value at 3% (or 5%) elongation: LASE value at 3% (or 5%) elongation (load at 3% or 5% elongation) using a universal tensile tester at room temperature, based on ASTM D885 Value).

[Table 5] Tire Cord Properties

Used drawer Shrinkage stress (N) LASE (g / d) at the time of 3% height LASE (g / d) at the time of 5% height Example 1 6.080 2.36 3.25 Example 2 5.560 2.00 3.05 Example 3 5.020 2.13 3.06 Example 4 6.440 2.43 3.12 Example 5 4.800 1.75 2.43 Example 6 6.430 2.55 3.36 Comparative Example 1 1.210 1.63 2.39 Comparative Example 2 1.420 1.72 2.45

Referring to Table 5, the tire cords made of the drawn yarns of Examples 1 to 6 having a high crosslink density exhibited excellent shrinkage stress, compared to the tire cords made of the drawn yarns of Comparative Examples 1 and 2, but with 3%. And a high load value at 5% elongation was found to exhibit excellent modulus characteristics.

Therefore, it is confirmed that the tire cords prepared from the drawn yarns of Examples 1 to 6 exhibit more improved modulus characteristics with excellent shrinkage stress, and thus can be preferably applied to capply cords of pneumatic tires and the like.

1 is a partial cutaway perspective view showing a configuration of a general tire.

Figure 2 is a schematic diagram of the configuration of the shrinkage behavior tester used for the measurement of shrinkage and shrinkage stress.

Claims (9)

Polyethylene terephthalate containing 90 mol% or more, the polyethylene having a crosslink density of 3.0E + 22 ~ 8.0E + 22 pieces / cm ³ after heat treatment at 230 ° C. for 1 minute under tension under 0.02 g / d ultra load Terephthalate drawn yarn. The method of claim 1, Polyethylene containing 90 mol% or more of polyethylene terephthalate and having a crosslink density of 5.0E + 22 to 8.0E + 22 pieces / cm ³ after heat treatment at 230 ° C. for 1 minute under tension under 0.02 g / d superload. Terephthalate drawn yarn. The method of claim 1, Polyethylene terephthalate drawn yarn having a crosslink density of 2.0E + 22 ~ 6.0E + 22 pieces / cm ³ before the heat treatment. Polyethylene terephthalate tire cord comprising the stretched yarn according to any one of claims 1 to 3. 5. The method of claim 4, Polyethylene terephthalate tire cord showing strength of 5 to 8 g / d, heavy toxins (@ 4.5 kgf) and stretch to 10 to 25%. 5. The method of claim 4, Polyethylene terephthalate tire cord having a total fineness of 1000 to 5000 denier, 1 to 3 plies, and 200 to 500 TPM. 5. The method of claim 4, Polyethylene terephthalate tire cord as a capfly cord. A pneumatic tire comprising the tire cord according to claim 4. 9. The method of claim 8, Air-injected tire applying the cord to the cap ply.

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