KR101228128B1 - Drawn poly(ethyleneterephthalate) fiber, tire-cord and tire comprising the same - Google Patents

Abstract

The present invention is excellent in shape stability according to the external load changes, can be preferably applied to the cap ply cord of the pneumatic tire, etc., polyethylene tere that can suppress the deformation of the tire to improve the controllability or ride comfort of the vehicle It relates to phthalate stretched yarns, tire cords and tires comprising the same.

The polyethylene terephthalate stretched yarn contains 90 mol% or more of polyethylene terephthalate, and the shrinkage rate when a load of 226 g / 1000d is applied at 180 ° C. is 25% or more of the shrinkage rate when a load of 20 g / 1000d is applied at the same temperature. .

PET, stretched yarn. Code, load, shrinkage, shrinkage stress

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.

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 currently include 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 fatigue during rolling.

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. By the way, in the case of such a nylon 66 code, it can exhibit an effect of suppressing the movement of the belt by wrapping the steel belt by expressing a high shrinkage force at a curing temperature of 180 ℃, but due to its low form stability, part of the tire and car's own load There is a disadvantage that the deformation may occur, which may cause a rattling while driving.

Moreover, as the nylon 66 cord has low shape stability, when the traveling speed of the vehicle is changed so that the load applied to the nylon 66 cord is changed, the appearance shape can be easily deformed and the tire can be deformed, thereby adjusting the vehicle. You may not be able to feel your sex or ride comfort.

In comparison, PET High Modulus Low Shrinkage (HMLS) fiber, which is widely used as a general polyethylene terephthalate (PET) fiber or an industrial fiber, has better shape stability than nylon 66, but has a lower shrinkage stress and a lower cappla. It is difficult to use preferably for use code | coins. Moreover, since these general PET fibers or HMLS fibers also do not have sufficient form stability, when the vehicle's traveling speed is changed and the load applied to the cords made of these materials changes, the appearance form can be relatively easily deformed to deform the tire. . Therefore, even when a cord made of these materials is used as a wet ply cord, the appearance of the cord may be relatively easily deformed and the tire may be deformed as the running speed of the vehicle is changed and the load applied to the cord is changed. The adjustment or ride comfort of the car is not enough.

Accordingly, the present invention is to provide a polyethylene terephthalate stretched yarn that is capable of providing a tire cord showing not only excellent shape stability due to external load changes but also improved 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 including the polyethylene terephthalate tire cord, which is not easily deformed and can improve the controllability or ride comfort of the vehicle.

The present invention comprises 90 mol% or more of polyethylene terephthalate, and the polyethylene terephthalate lead having a shrinkage rate of 226 g / 1000d at 180 ° C. is 25% or more of the shrinkage rate of 20 g / 1000d at the same temperature. Provide a gentleman.

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, the present invention will be described in more detail.

The polyethylene terephthalate (hereinafter referred to as "PET") drawn yarn of the present invention is produced by melting and spinning PET to prepare undrawn yarn, and then drawing such undrawn yarn, and combining the PET drawn yarn of the present invention. It can be twisted and immersed in an adhesive to produce a tire cord in the form of a dipcode.

Therefore, the properties of the undrawn yarn produced through melt spinning of PET and the drawn yarn produced by drawing them are directly or indirectly reflected on the physical properties of the tire cord. In particular, the PET drawn yarn of the present invention is 90 mol of polyethylene terephthalate. It contains more than% and the shrinkage rate when a load of 226g / 1000d is applied at 180 ° C is 25% or more of the shrinkage rate when a load of 20g / 1000d is applied at the same temperature.

At this time, the shrinkage rate of the PET stretched yarn is a predetermined load (for example, 226g / under a predetermined temperature of 180 ℃ in the state in which the PET stretched yarn in a shrinkage behavior tester (for example, Figure 2) Can be measured by applying a load of 1000 d or 20 g / 1000 d).

PET stretched yarn of the present invention shows a shrinkage rate that does not change significantly even if the load applied to itself is greatly changed. In particular, compared to the stretch yarn made of fibers such as nylon 66, general PET, or HMLS, which has been conventionally applied to tire cords, the PET stretch yarn of the present invention not only has a small shrinkage rate but also a large change in the load itself. It has been found that the rate of change of shrinkage is small. Therefore, not only the shrinkage rate itself is large but also the change rate of the shrinkage rate according to the change of the load may be provided with the tire cord. Even if the tire cord changes the traveling speed of the vehicle so that the load applied to the tire cord changes, the deformation of the external shape is suppressed (that is, has excellent shape stability) and the tire including the tire is not easily deformed. Therefore, it is possible to provide a tire cord that can be applied to the wet ply cord or the like using the PET stretch yarn of the present invention to improve the controllability or ride comfort of the vehicle.

On the other hand, the PET stretched yarn of the present invention includes more than 90 mol% PET to exhibit suitable physical properties for the tire cord, if the PET stretcher comprises PET in an amount less than 90 mol% from the PET stretched yarn and the It is difficult for the manufactured tire cord to exhibit desirable general physical properties intended by the present invention. Hereinafter, the term PET in the present invention refers to a case in which PET is 90 mol% or more without special description.

In addition, the PET stretched yarn of the present invention can be 60% or more of the shrinkage stress when the load of 226g / 1000d at 180 ℃, the load of 20g / 1000d at the same temperature, 180 ℃ The shrinkage stress at a load of 20 g / 1000d at may be 4.0N or more, preferably 4.0 to 6.0N, and the shrinkage stress at a load of 226g / 1000d at 180 ° C. is 2.5N or more, preferably May be 2.5 to 4.0N.

At this time, the shrinkage stress of the PET stretched yarn is a predetermined load (for example, 226g) under a certain temperature of 180 ℃ in the state in which the PET stretched yarn in a shrinkage behavior tester (for example, Figure 2) / 1000d or 20g / 1000d, etc.) can be measured.

As described above, the PET stretched yarn of the present invention not only has excellent morphological stability, but also exhibits higher shrinkage stress than nylon 66 stretched yarn, and such high shrinkage stress is maintained at any load on the PET stretched yarn. Can be. Thus, the PET stretch yarn can be used to provide a tire cord that exhibits high shrinkage stress with excellent morphological stability, and this tire cord can effectively wrap the steel belt in, for example, a pneumatic tire to effectively move the belt. Since it can suppress, it can apply suitably as a code | column for cap plies.

On the other hand, the PET stretched yarn of the present invention described above may be produced by melt spinning PET to produce a non-stretched yarn, and a method of stretching the non-stretched yarn, as described above, the specific conditions or progress method of each step is PET The PET stretched yarn of the present invention having the above-described physical properties can be produced by being reflected directly or indirectly in the properties of the stretched yarn.

In particular, the polyethylene terephthalate undrawn 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. It has been found that the PET stretched yarn of the present invention having a smaller rate of change can be produced.

PET basically has a crystallized form and is 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 drawn yarns made from the PET non-drawn yarns can exhibit high shrinkage stress and modulus.

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 in the amorphous region become a relaxed structure rather than a tensioned structure, and thus, a stretched yarn made from undrawn yarn shows a low shrinkage stress with a low shrinkage rate. . However, the PET non-drawn yarn obtained under controlled melt spinning conditions contains more crosslinks per unit volume, forming a fine network structure due to the molecular chains which make it slip during the spinning process. For this reason, the PET unstretched yarn can have a strained structure of the chains in the amorphous region while the amorphous orientation index is greatly lowered, thereby showing the developed crystal structure and excellent orientation characteristics.

Therefore, it is possible to produce PET stretched yarns exhibiting both low shrinkage and high shrinkage stress by using PET non-drawn yarns exhibiting such high crystallinity and low amorphous orientation index, and furthermore, PET strands having excellent physical properties according to the present invention. It turned out to be able to offer a shrine.

Hereinafter, the manufacturing method of the PET stretched yarn of the present invention will be described in more detail in 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 1.2 g / d. In addition, for example, the rate of melt spinning the PET can be adjusted to 3800 to 5000 m / min, preferably 4000 to 4500 m / min can be adjusted.

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 the manufacturing process of such PET non-stretched yarn, chips having an intrinsic viscosity of 0.8 to 1.3 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, conditions of higher spinning tension and optionally high spinning speed can be imparted. In order to proceed the spinning step under these conditions, the intrinsic viscosity of the chip Is preferably 0.8 or more. However, the intrinsic viscosity is preferably 1.3 or less in order to prevent the molecular chain cutting and the pressure increase due to the discharge amount from the spinning 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. Thereby, PET stretched yarn which shows the general physical property of this invention can be manufactured 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, so that the PET drawn yarn produced through the above-described manufacturing method also hardly exhibits 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.

PET stretched yarn prepared by the above-described manufacturing method may exhibit excellent physical properties according to the present invention, that is, excellent physical properties such as a lower rate of change in shrinkage rate by load, a low rate of change in shrinkage stress or high shrinkage stress.

On the other hand, the present invention also provides a PET tire cord comprising the PET stretch yarn described above.

That is, the tire cord of the present invention includes a PET stretch yarn of the present invention which exhibits not only a low rate of change in shrinkage rate and a high shape stability, but also a high rate of shrinkage and a low rate of change in stress. Therefore, since the tire cord of the present invention can also exhibit high form stability, even if the traveling speed of the vehicle is changed and the load applied to the tire cord is changed, the deformation of the appearance form is suppressed (that is, has excellent shape stability). Including tires are not easily deformed. Therefore, by applying the tire cord of the present invention as a cap ply cord or the like, it is possible to improve the controllability or ride comfort of the vehicle.

In addition, since the tire cord including the PET stretched yarn of the present invention exhibits high shrinkage stress, for example, it is possible to effectively wrap the steel belt in the pneumatic tire to effectively suppress the movement of the belt. It can be preferably applied as a use code.

On the other hand, the tire cord of the present invention is not particularly limited in form, it may have a form equivalent to the conventional cap fly code. More specifically, the tire cord of the present invention has a total fineness of 1000 to 5000 denier (d) per cord, the number of plies is 1 to 3, and the number of twists is 200 to 500 TPM according to the form of a conventional cap ply cord. It may have the form of a dipcode.

In addition, the tire cord of the present invention has an elongation of 5 to 8 g / d, preferably 5.5 to 7 g / d, an elongation of 1.5 to 5.0%, preferably 2.0 to 3.5% (measured at 4.5 kg load) and 10 From 25% to 25%, preferably from 15 to 25%. As the tire cord exhibits various physical properties such as strength or elongation in this range, it can be preferably applied as a capfly cord.

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 has a different driving speed, so that the load applied to the cap ply cord is largely changed, but the appearance of the cap ply cord is not easily deformed and the tire itself is not easily deformed. Therefore, the tire can improve the controllability 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.

In the above description, the tire cord of the present invention is mainly assumed to be used as a cap ply cord, but the use of the tire cord of the present invention is not limited thereto and may be used for other purposes such as body ply cord. Of course it can.

On the other hand, the tire cord of the present invention can be manufactured in the form of a deep cord by immersing in the adhesive after the twisted yarn PET stretched yarn of the present invention, according to a conventional method for producing a 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 may exhibit a lower rate of change in shrinkage rate, higher shrinkage stress, higher strength, and the like.

As described above, the PET stretched yarn of the present invention not only exhibits high shrinkage stress of nylon 66 stretched yarn or more, but also exhibits excellent morphological stability due to a small change in shrinkage due to a change in load applied to itself. Therefore, a tire cord that can be preferably applied to the cap ply cord of the pneumatic tire using the PET stretched yarn can be provided.

In addition, even if the tire to which the cap ply cord is applied has a different driving speed, the load applied to the cap ply cord is greatly changed, the appearance of the cap ply cord is not deformed well, and thus the tire itself is not easily deformed. . Therefore, 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  One

A PET polymer having an intrinsic viscosity of 1.05 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. PET stretch yarn of Example 1 was prepared by stretching, heat setting and winding at a draw ratio of.

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.

Example  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 Same as Example 1 Same as Example 1 1.54 1.16 Intrinsic viscosity 0.9 1.2 Same as Example 1 Same as Example 1

Comparative Example 1 (Preparation of Drawn Yarn Using High Elasticity Low Shrinkage (HMLS) Fiber)

PET polymer with an intrinsic viscosity of 1.05 for the production of undrawn yarn was melt-spun at a spinning speed of 3000 m / min under a radial tension of 0.52 g / d, and an undrawn yarn was drawn at a draw ratio of 1.8 to produce a drawn yarn. The stretched yarn of Comparative Example 1 was prepared in the same manner as in Example 1.

Comparative Example 2 (Preparation of Drawn Yarn Using Nylon 66 Fiber)

According to a conventional manufacturing method, nylon 66 polymer having a relative viscosity of 3.3 is melt-spun and cooled at a spinning speed of 600 m / min to prepare an undrawn yarn, and the undrawn yarn is drawn, heat-set and wound at a draw ratio of 5.5 to nylon 66 fibers. The drawn yarn of Comparative Example 2 was prepared.

First, the crystallinity and amorphous orientation index (AOF) of PET undrawn yarn obtained in Examples 1 to 6 and Comparative Example 1 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 Crystallinity (%) 36 30 34 36 28 38 9 AOF 0.009 0.093 0.015 0.012 0.120 0.002 0.245

Subsequently, the shrinkage stress and the shrinkage ratio of the stretched yarns prepared according to Examples 1 to 6 and Comparative Examples 1 and 2 were measured by the following method using a shrinkage behavior tester (TestKite Corporation MK-V) as shown in FIG. 2. , The change in shrinkage stress according to the load change on the stretched yarn is shown in Tables 3 and 4, and the change in shrinkage rate is shown in Tables 5 and 6.

Shrinkage stress (g / d): 20 g / 1000d of the super load applied to each of the drawn yarns while the drawn yarns prepared in Examples 1 to 6 and Comparative Examples 1 and 2 were respectively loaded in the shrinkage behavior tester. , 60g / 1000d, 113g / 1000d, 160g / 1000d and 226g / 1000d. Each time the initial load changed, the shrinkage stress was measured under a constant temperature of 180 ° C. in the fixed state.

[Table 3]

weight
(g / 1000d) Example 1
(Shrinkage stress; N) Example 2
(Shrinkage stress; N) Example 3
(Shrinkage stress; N) Example 4
(Shrinkage stress; N) 20 4.52 4.45 4.50 4.53 60 4.31 4.28 4.33 4.33 113 3.95 3.83 3.95 3.97 160 3.67 3.50 3.60 3.77 226 3.54 3.08 3.40 3.60

[Table 4]

weight
(g / 1000d) Example 5
(Shrinkage stress; N) Example 6
(Shrinkage stress; N) Comparative Example 1
(Shrinkage stress; N) Comparative Example 2
(Shrinkage stress; N) 20 4.46 4.90 3.58 3.17 60 4.30 4.42 3.36 2.93 113 3.89 4.10 2.89 2.44 160 3.62 3.92 2.55 2.13 226 3.48 3.80 2.02 1.66

Shrinkage rate (%): Under a constant temperature of 180 ° C., the super-load applied to each of the stretched yarns in the state in which the stretched yarns prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were respectively applied to the shrinkage behavior tester. Were given at 20 g / 1000d, 60 g / 1000d, 113 g / 1000d, 160 g / 1000d and 226 g / 1000d. Each time the initial load changed, the shrinkage was measured.

[Table 5]

weight
(g / 1000d) Example 1
(Shrinkage;%) Example 2
(Shrinkage;%) Example 3
(Shrinkage;%) Example 4
(Shrinkage;%) 20 5.70 6.20 5.70 6.00 60 4.20 4.50 4.30 4.40 113 2.80 3.20 2.80 3.20 160 2.40 2.60 2.40 2.70 226 1.70 1.90 1.70 2.00

TABLE 6

weight
(g / 1000d) Example 5
(Shrinkage;%) Example 6
(Shrinkage;%) Comparative Example 1
(Shrinkage;%) Comparative Example 2
(Shrinkage;%) 20 6.30 5.50 9.7 8.4 60 4.50 4.00 6.6 6.7 113 3.30 2.70 4.2 5.0 160 2.70 2.30 3.0 3.8 226 2.10 1.50 1.9 2.7

Referring to Tables 3 and 4, the PET drawn yarns of Examples 1 to 6 prepared from PET non-drawn yarns exhibiting high crystallinity and low amorphous orientation index are generally not only HMLS drawn yarn of Comparative Example 1 but also nylon 66 lead of Comparative Example 2. It is confirmed that high shrinkage stress is also exhibited compared to the gentleman.

In addition, the PET drawn yarns of Examples 1 to 6 maintain high shrinkage stress no matter what load is applied to itself, whereas the drawn yarns of Comparative Examples 1 and 2 have relatively high shrinkage stresses as the load applied to them changes. It is confirmed that the lowering significantly.

Thus, the tire cords made from the PET stretched yarns of Examples 1 to 6 also exhibit high shrinkage stresses as well as such high shrinkage stresses can be maintained at any load, for example, by well wrapping the steel belts in pneumatic tires It is confirmed that the movement of the belt can be effectively suppressed and can be preferably applied as a capfly code.

In addition, referring to Tables 5 and 6, the PET stretched yarns of Examples 1 to 6 are not only relatively low in terms of basic shrinkage compared to the stretched yarns of Comparative Examples 1 and 2, but the degree of change in shrinkage rate even if the load applied to itself is largely changed. Is not so large.

That is, considering Tables 3 to 6, the PET stretched yarns of Examples 1 to 6 had a high shrinkage while having a lower shrinkage rate compared to HMLS stretched yarn of Comparative Example 1 and nylon 66 stretched yarn of Comparative Example 2, under all load conditions. In addition to showing stresses, it is confirmed that their rate of change by load is not large.

Therefore, the tire cords prepared from the PET stretched yarns of Examples 1 to 6 exhibit high morphological stability, and can effectively suppress the movement of the steel belt in the tire due to the high shrinkage stress, so that the tire cords are preferably applied as a cap ply cord or the like. Seems to be able to.

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 (10)

Polyethylene terephthalate stretched yarn containing 90 mol% or more of polyethylene terephthalates, and the shrinkage rate at the time of applying the load of 226g / 1000d at 180 degreeC is 25% or more of the shrinkage rate when the load of 20g / 1000d is applied at the same temperature. The method of claim 1, Polyethylene terephthalate stretched yarn in which the shrinkage stress when a load of 226 g / 1000d is applied at 180 ° C. is 60% or more of the shrinkage stress when a load of 20 g / 1000d is applied at the same temperature. The method of claim 2, Polyethylene terephthalate stretched yarn having a shrinkage stress of 4.0 N or more when a load of 20 g / 1000 d is applied at 180 ° C. The method of claim 2, Polyethylene terephthalate stretched yarn having a shrinkage stress of 2.5 N or more when a load of 226 g / 1000 d is applied at 180 ° C. Polyethylene terephthalate tire cord comprising the stretched yarn according to any one of claims 1 to 4. 6. The method of claim 5, Polyethylene terephthalate tire cord showing strength of 5 to 8 g / d, a torso of 1.5 to 5.0% (@ 4.5 kg) and a stretch of 10 to 25%. 6. The method of claim 5, Polyethylene terephthalate tire cord having a total fineness of 1000 to 5000 denier, 1 to 3 plies, and 200 to 500 TPM. 6. The method of claim 5, Polyethylene terephthalate tire cord as a capfly cord. A pneumatic tire comprising the tire cord according to claim 5. The method of claim 9, Air-injected tire applying the cord to the cap ply.

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