KR101231095B1 - Drawn poly(ethyleneterephthalate) fiber, tire-cord and tire comprising the same - Google Patents

Abstract

The present invention relates to a polyethylene terephthalate stretched yarn and a tire cord comprising the same, which exhibits excellent shrinkage stress and modulus, thereby enabling the provision of a tire cord which can be preferably used as a capfly cord.

The polyethylene terephthalate stretched yarn contains at least 90 mol% of polyethylene terephthalate, the crystallization degree is 53% or more after heat treatment at 230 ° C. under 20g / 1000d for one minute, and the amorphous orientation index (AOF) is 0.15. Below, the birefringence is 0.14 to 0.16.

PET, stretched yarn, tire cord, shrinkage stress, modulus

Description

Polyethylene terephthalate stretched yarn and tire cords and tires including the 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 a polyethylene terephthalate stretched yarn, tire cords and tires comprising the same, which exhibits excellent shrinkage stress and modulus together to enable the provision of tire cords which are preferably usable as capplyse cords.

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.

Currently commonly used materials for the cord include rayon, nylon, polyester, steel, and aramid, and rayon and polyester are used for body ply (also called carcass) (6 in FIG. 1), and nylon is mainly used. In the cap ply (4 in FIG. 1), and steel and aramid are mainly used for 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 capply 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.

Nylon 66 is mainly applied to the cap fly cord. 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, the nylon 66 cord has a low modulus and glass transition temperature at high temperatures, and thus a low form stability, so that partial deformation may occur due to tires and automobiles' own loads, which may cause them to rattle 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 to effectively move the steel belt. It was difficult to suppress, which made it difficult to apply as a capfly cord. Moreover, since the cords made of such general PET fibers also do not have sufficient form stability, when the driving speed of the vehicle is changed and the load applied to the cords made of these materials is changed, the appearance form can be relatively easily deformed to deform the tire. .

In addition, in the case of a cord made of PET High Modulus Low Shrinkage (HMLS) fiber, which is widely used as a fiber or an industrial fiber, it may exhibit high shrinkage stress as compared to a cord made of the general PET fiber. As modulus is lowered and morphological stability is lowered, disadvantages such as the nylon 66 cord may still occur.

Accordingly, the present invention is to provide a polyethylene terephthalate stretched yarn exhibiting excellent shrinkage stress and modulus together to enable the provision of a tire cord that can be preferably used as a cap ply cord.

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

Another object of the present invention is to provide a tire including the tire cord.

The present invention comprises at least 90 mol% polyethylene terephthalate, the crystallization degree is 53% or more after heat treatment at 230 ° C. for 1 minute under 20g / 1000d ultra load, Amorphous Orientation Factor (AOF) is 0.15 or less, It provides a polyethylene terephthalate stretched yarn having a birefringence of 0.14 to 0.16.

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

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

Hereinafter, a polyethylene terephthalate stretched yarn, a polyethylene terephthalate tire cord 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.

Additionally, unless otherwise indicated throughout this specification, "comprising" or "containing" refers to including any component (or component) without particular limitation, and refers to the addition of another component (or component). It cannot 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. Therefore, it is possible to provide a PET tire cord having excellent physical properties by providing a PET stretched yarn having predetermined characteristics.

In accordance with one embodiment of the present invention, there is provided a PET drawn yarn having a predetermined characteristic. The PET stretched yarn contains 90 mol% or more of polyethylene terephthalate, has a crystallinity of 53% or more after annealing at 230 ° C. under 20 g / 1000d of ultra-high load, and has an amorphous Orientation Factor (AOF) of 0.15 or less. And birefringence is 0.14 to 0.16.

The PET forming the stretched yarn may be added with various additives in the manufacturing step, in order to exhibit the physical properties of PET suitable for the tire cord, at least 90 mol% or more of PET polymer is preferably included. Hereinafter, the term PET refers to the case where the PET polymer is 90 mol% or more without any special explanation.

PET stretched yarn according to an embodiment of the present invention is prepared from a specific non-drawn yarn under the predetermined process conditions to be described later, to exhibit a high degree of crystallinity of 53% or more and a low amorphous orientation index of 0.15 or less after heat treatment.

The PET fibers constituting the PET stretched yarn have a crystallized form, and are composed of a crystalline region and an amorphous region including amorphous chains. However, PET stretched yarn according to an embodiment of the present invention has a higher degree of crystallinity than previously known PET stretched yarn due to the orientation crystallization phenomenon in the manufacturing process, 53% or more after heat treatment at 230 ° C. for 1 minute under 20g / 1000d ultra load. Preferably a high degree of crystallinity of 53 to 60%. It has been found that this high degree of crystallinity can result in high shrinkage stress and modulus of the PET drawn yarn and tire cords prepared therefrom.

At the same time, the PET stretched yarn exhibits an amorphous orientation index of 0.15 or less, preferably 0.01 to 0.10, which is significantly lower than previously known PET stretched yarn after heat treatment under the above-described conditions. In this case, the amorphous orientation index indicates the degree of orientation of the chains included in the amorphous region, and has a lower value as the matting of the chains of the amorphous region increases. In general, when the amorphous orientation index is lowered, the disorder is increased so that the chains in the amorphous regions become a relaxed structure rather than a strained structure, so that the drawn yarn and the tire cords produced therefrom exhibit low shrinkage stress with low shrinkage. . However, PET stretched yarn according to an embodiment of the present invention includes a large number of crosslinks while forming a fine network structure due to the sliding of the molecular chains forming it during the spinning process. For this reason, the PET stretched 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, the PET drawn yarn according to the embodiment of the present invention may exhibit low shrinkage and excellent modulus while exhibiting excellent shrinkage stress due to the developed crystal structure and excellent orientation properties. Therefore, tire cords made of such PET stretched yarn may also exhibit excellent shrinkage stress, excellent modulus, and thus high form stability, and thus may be suitably applied as a cap ply cord of a tire.

In particular, in the process of manufacturing a tire cord using PET stretched yarn, the process of heat-treating the PET stretched yarn at a temperature of about 200 ℃ or more, for example, 230 ℃ for curing the adhesive. Therefore, the physical properties of the PET stretch yarn after the heat treatment at 230 ℃ is directly connected to the physical properties of the tire cord prepared therefrom, PET stretch yarn according to an embodiment of the present invention high crystallinity and low amorphous orientation index even after such high temperature heat treatment Since it has a very advanced crystal structure and orientation structure as having, etc., tire cords prepared therefrom may also exhibit excellent physical properties corresponding thereto. Therefore, PET drawn yarn according to one embodiment of the present invention exhibits excellent modulus with excellent shrinkage stress, thereby enabling the provision of a tire cord which can be preferably used as a capfly code.

PET drawn yarn according to one embodiment of the present invention after the heat treatment for 1 minute at 230 ℃ (010) plane spacing of the crystal calculated from the XRD measurement peak is 58 to 65 Å, (110) plane spacing is 46 to 54 Å , (100) The surface spacing is preferably 44 to 52 mm 3. As such, the PET stretched yarn may have a highly developed crystal structure, and thus the stretched yarn and the tire cords prepared therefrom exhibit higher shrinkage stress and modulus, and thus may be more preferably used for capfly cords and the like.

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

In particular, the polyethylene terephthalate undrawn yarn having a crystallization degree of 25% or more and an amorphous Orientation Factor (AOF) of 0.15 or less by adjusting the melt spinning condition of the PET is obtained, and stretching the same, the invention as described above It has been found that PET stretched yarn according to one embodiment of the present invention can be prepared.

PET non-drawn yarn used in this manufacturing process is manufactured under the controlled melt spinning conditions described below to have a higher degree of crystallization than previously known PET non-drawn yarn, and has a crystallinity of 25% or more, preferably 25 to 40%. Indicates.

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.

PET micro-stretched, which exhibits such high crystallinity and low amorphous orientation index, shows an advanced crystal structure, while at the same time, the molecular chains in the amorphous region are slid during the spinning process to form a fine network structure, thereby forming a large number of crosslinks per unit volume. Include. Therefore, the PET unstretched yarn has an advanced crystal structure, but has a high degree of matted chains of amorphous regions and a strained structure due to a large number of crosslinks. Therefore, PET drawn yarn and tire cords made from such PET non-drawn yarn can exhibit high shrinkage stress and modulus and low shrinkage simultaneously. In particular, by using such non-stretched PET, PET stretched yarn according to an embodiment of the present invention exhibiting the above-described physical properties (for example, high crystallinity and low amorphous orientation index after heat treatment) can be prepared.

Hereinafter, the manufacturing method of such PET stretch yarn will be described in more detail in each step.

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, 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 experiment, as the melt spinning process of PET is performed under such high spinning tension and optionally high spinning speed, higher energy is applied in the process of manufacturing the non-stretched PET yarn. It has been found that crosslinking of can be formed, and because of this, PET unstretched yarns with developed crystal structure and good orientation properties can be formed. That is, under such 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 fibers are slid during the spinning process to form a fine network structure, and thus the crystallinity and amorphous orientation described above. PET non-drawn yarn that satisfies the index can be obtained. 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, conditions of higher spinning speed and spinning tension can be given. In order to proceed the spinning step under these conditions, the intrinsic viscosity of the chip is 0.8 dl. It is preferable that it is / 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 discharge amount 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 (d), preferably 2.5 to 3.0 denier (d). That is, in order to reduce the possibility of trimming due to the interference between each other during the generation and trimming during spinning, the denier of monofilament should be 2.0 denier (d) or more. It is preferable that the fineness of a filament is 4.0 denier (d) 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. This makes it easier to produce PET non-drawn yarns exhibiting the above high crystallinity and low amorphous orientation index.

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 non-drawn yarn has advanced crystal regions, and the chains of the 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 drawing process is performed under a relatively low draw ratio, the strength of the PET drawn 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.

In the stretching process, the undrawn yarn may be heat treated at a temperature of about 160 ° C. or more and less than 240 ° C., and preferably, the unstretched yarn may be heat treated at a temperature of 200 ° C. or less for proper progress of the stretching process. have.

PET stretched yarn manufactured by the above-described manufacturing method may exhibit various physical properties according to one embodiment of the present invention, that is, for example, physical properties such as high crystallinity and low amorphous orientation index after heat treatment.

On the other hand, according to another embodiment of the invention there is provided a PET tire cord comprising the PET stretch yarn described above. Since the tire cord includes the PET stretched yarn having the above-described excellent physical properties, it exhibits excellent shrinkage stress and modulus and the like, and can be preferably used as, for example, a cap ply cord in a pneumatic tire.

In addition, the PET tire cord according to another embodiment of the present invention is preferably L / S value of 70g / d to 150g / d is defined in the following formula 1 in terms of form stability.

[Equation 1]

L / S = LASE / Shrinkage (%)

In the above formula, LASE is a value defined as a load at a specific elongation (Load At Specific Elongation), in particular, in the above formula 1 is defined as a load at 3% elongation measured at 100 ℃. This is because the initial modulus of the PET tire cord is of great importance.

In addition, in order to satisfy the above L / S value, the PET tire cord has a lase defined as a load at 3% elongation of 1.7 to 1.7 when subjected to a tensile test under a supertension of 0.05 g / d and a temperature of 100 ° C. 3.0 g / d.

In Equation 1, the L / S value is a shape stability index indicating how stably the tire cord can be maintained despite the external heat or force. That is, as the L / S value is higher, the tire cord may be stably maintained without being deformed in spite of external heat or force. By the way, according to another embodiment of the PET tire cord is made of PET stretched yarn having a high shrinkage stress and modulus, very high L / S value, for example, L / S of 70 g / d to 150 g / d Since it has a value, it is possible to effectively suppress the movement of the belt by wrapping the steel belt in the tire without being deformed well despite external heat or force. In addition, the PET tire cord can also effectively suppress the partial deformation and the noise caused by the tire and the vehicle's own load.

As described above, the PET tire cord according to another embodiment of the present invention is not particularly limited in form, and may have a form equivalent to a conventional cap fly cord. More specifically, this 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 depending on the form of a conventional cap ply cord. It may have a form.

In addition, the PET tire cord has a strength of 5 to 8 g / d, 1.5 to 5.0%, preferably 2.0 to 5.0% of the core (elongation at 4.5kgf load), 10 to 25% of the elongation and 0.5 to 5.0%, Preferably it may exhibit a shrinkage (177 ℃, 30g, 2min) of 2.0 to 5.0%. 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.

And, the above-described PET tire cord can be applied as a cap ply cord of the pneumatic tire. The tire to which the PET tire cord is applied is not easily deformed due to its excellent shape stability of the cap ply cord, so that the tire itself is not easily deformed. Therefore, the tire can improve the controllability or ride comfort of the vehicle. In addition, since the PET tire cord effectively suppresses the movement of the steel belt and has various physical properties that 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 mainly assumes a case where the PET tire cord according to another embodiment of the present invention is used as a cap ply cord, but the use of the PET tire cord is not limited thereto. Of course, it can also be used for other purposes, such as a cord.

 Meanwhile, the PET tire cord may be manufactured in the form of a dip cord by immersing the PET stretched yarn according to one embodiment of the present invention, the woven twisted PET stretched yarn according to an embodiment of the present invention and then immersed in an adhesive. 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.

Unlike conventional PET drawn yarns, the PET drawn yarn of the present invention has a very advanced crystal structure and orientation structure produced during spinning, and has excellent shrinkage stress and modulus due to the fine network generated by such crystal structure and orientation structure. As shown, there is an advantage that can be preferably used as a yarn of the tire cord for cap ply.

In particular, the PET stretched yarn has a crystal structure and an orientation structure thus developed after heat treatment at 230 ℃, the physical properties of the PET stretched yarn is directly connected to the physical properties of the tire cord made from the PET stretched yarn. Therefore, it is apparent that the tire cords prepared from the PET stretched yarns can exhibit excellent shrinkage stress and modulus, and thus can be preferably used as the capfly cord.

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.

Examples 1 to 6 (Preparation of PET Unstretched)

PET unstretched yarns of Examples 1 to 6 were prepared by melt spinning and cooling a PET polymer having a predetermined intrinsic viscosity. At this time, the intrinsic viscosity of the PET polymer, the spinning speed and the spinning tension conditions in the melt spinning process are as shown in Table 1, the remaining conditions were in accordance with conventional conditions for the production of PET non-drawn yarn.

[Table 1]

Example One 2 3 4 5 6 Intrinsic Viscosity (dl / g) 0.85 1.05 1.05 1.05 1.05 1.20 Spinning speed (m / min) 4200 3800 4000 4200 4500 4200 Radial tension (g / d) 0.93 0.86 0.92 1.03 1.15 1.08

Comparative Examples 1 to 6 (manufactured by PET undrawn)

PET undrawn yarns of Comparative Examples 1 to 6 were prepared according to the same method as Examples 1 to 6 except for the conditions described in Table 2 below.

[Table 2]

Comparative example One 2 3 4 5 6 Intrinsic Viscosity (dl / g) 0.75 1.05 1.05 1.05 1.05 1.30 Spinning speed (m / min) 4200 3000 3500 3800 5000 4200 Radial tension (g / d) 0.81 0.52 0.63 0.72 Cannot be sacrificed Cannot be sacrificed

The crystallization degree and amorphous orientation index (AOF) of the non-drawn yarns prepared according to Examples 1 to 6 and Comparative Examples 1 to 6 were measured by the following method, and the measured physical properties are summarized in Tables 3 and 4 below (but In the comparative examples, the physical properties of the non-stretched yarns except for the non-ritable comparative examples 5 and 6 were measured and arranged.).

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 (%) =

(In this case, 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 3]

Example One 2 3 4 5 6 Crystallinity (%) 32 28 30 33 36 33 AOF 0.074 0.120 0.093 0.054 0.009 0.061

[Table 4]

Example One 2 3 4 Crystallinity (%) 24 9 12 22 AOF 0.157 0.245 0.255 0.168

Referring to Tables 3 and 4 above, the unstretched yarns of Examples 1 to 6 prepared under high spinning tension and spinning speed have high crystallinity and low amorphous orientation index, and show advanced crystal structure and excellent orientation characteristics. It was confirmed that the non-drawn yarns of Examples 1 to 4 did not satisfy these characteristics.

Examples 7 to 12 (Preparation of PET Stretch Yarn)

PET stretch yarns of Examples 10 to 15 were prepared by stretching the non-drawn yarns prepared according to Examples 1 to 6 at a draw ratio as shown in Table 5 and then heat treatment at 180 ° C.

Comparative Examples 7 to 10 (manufacture of PET stretcher)

PET stretched yarns of Comparative Examples 7 to 10 were prepared in the same manner as in Examples 7 to 12, except that non-drawn yarns prepared according to Comparative Examples 1 to 4 were used and draw ratios as shown in Table 6 were applied.

After the PET stretched yarns of Examples 7 to 12 and Comparative Examples 7 to 10 were heat treated at 230 ° C. for about 1 minute while being fixed under an ultraload of 20 g / 1000 d, the physical properties thereof were measured by the following methods, and the results were shown in Tables 5 and 6 below. Respectively.

Crystallinity and AOF: The crystallinity and AOF of PET stretched yarn were measured and calculated in the same manner as for PET non-drawn yarn.

Birefringence: The birefringence was measured using a polarizing microscope.

-Dry heat shrinkage: The dry heat shrinkage was measured for 2 minutes at 180 ° C. temperature and ultra high tension (30 g) using Testrite MK-V of Testrite of England.

Strength, Strength at 1% Elongation, LASE Value, and Body Weight: The strength, strength at 1% elongation, LASE, and body weight were measured using a universal tensile tester according to ASTM D885 criteria.

Melting point and specific heat of crystallinity (ΔH): The DSC-7 instrument was applied, and the melting point and the specific heat of crystallization were measured by chopping the yarn (drawn yarn) with a sample of about 2 mg. At this time, the temperature was applied to a temperature increase rate of 20 ℃ / min.

Plane spacing: Plane spacing was measured using XRD.

[Table 5]

Example 7 8 9 10 11 12 Unpainted Shrine Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Stretching cost 1.39 1.54 1.46 1.39 1.30 1.39 Crystallinity (%) 55 53 54 55 56 54 Birefringence 0.145 0.153 0.149 0.144 0.143 0.144 AOF 0.06 0.15 0.12 0.05 0.02 0.05 Strength (g / d) 6.0 7.0 6.7 6.3 6.0 6.4 Dry heat shrinkage (%) 6.5 8.3 8.0 6.3 5.8 7.4 Strength at 1% Elongation (g / d) 0.92 0.82 0.90 0.98 1.03 0.93 Majority (%) 5.3 5.0 5.2 5.5 5.7 5.4 010 face spacing 60 58 60 60 61 59 110 spaces 49 46 48 49 50 48 100 face spacing 47 44 46 48 50 46

 TABLE 6

Comparative example 7 8 9 10 Unpainted Shrine Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Stretching cost 1.39 1.8 1.57 1.50 Crystallinity (%) 52 49 50 51 Birefringence 0.175 0.189 0.184 0.179 AOF 0.38 0.54 0.50 0.43 Strength (g / d) 5.4 7.8 7.6 7.2 Dry heat shrinkage (%) 9.2 12.5 11.7 10.2 Strength at 1% Elongation (g / d) 0.545 0.442 0.473 0.523 Majority (%) 7.4 5.4 5.5 5.9 010 face spacing 55 54 54 55 110 spaces 42 43 42 42 100 face spacing 45 40 41 44

As shown in Tables 5 and 6, PET stretched yarns according to Examples 7 to 12 obtained from the non-stretched yarns of Examples 1 to 6 have a high degree of crystallinity and birefringence after heat treatment under predetermined conditions, and have low AOF. It was confirmed that the dry heat shrinkage was low and the strength at 1% elongation was high. In contrast, it was confirmed that the PET stretched yarns of Comparative Examples 7 to 10 obtained from the non-stretched yarns of Comparative Examples 1 to 4 did not satisfy these characteristics.

Examples 13-18 (Preparation of Tire Cords)

In order to manufacture the tire cord with the drawn yarn prepared according to Examples 7 to 12, the twisted yarns are blended under the conditions of the upper edge 430 TPM and the lower edge 430 TPM, and then immersed in the RFL adhesive solution, and then dried and heat-treated. Was prepared. At this time, the drawing yarn is a 1000 denier (d) yarn was given 430TPM based on this.

Comparative Examples 11 to 14 (Production of Tire Cords)

To produce a tire cord with the drawn yarns prepared according to Comparative Examples 7 to 10, the twisted yarns were blended under conditions of upper and lower 430 TPM and lower and lower 430 TPM, immersed in an RFL adhesive solution, and then dried and heat-treated to obtain a dip ply cord. Was prepared.

The L / S values of the tire cords prepared according to Examples 13 to 18 and Comparative Examples 11 to 14 and LASE values at 3% elongation measured at 100 ° C. under supertension of 0.05 g / d are shown in Table 7 below. .

[Table 7]

Used drawer L / S (g / d) 3% elongation LASE (g / d) Example 13 Example 7 84 1.80 Example 14 Example 8 71 1.95 Example 15 Example 9 70 1.90 Example 16 Example 10 81 1.85 Example 17 Example 11 94 2.10 Example 18 Example 12 73 1.90 Comparative Example 11 Comparative Example 7 68 1.60 Comparative Example 12 Comparative Example 8 55 1.30 Comparative Example 13 Comparative Example 9 64 1.45 Comparative Example 14 Comparative Example 10 67 1.50

As shown in Table 7, the tire cords of Examples 13 to 18 manufactured from drawn yarns having high crystallinity and the like after heat treatment have L / S values of 70 to 150 g / d, and an environment in which tires are actually used. Since the LASE value was 1.7 to 3.0 g / d even at 100 ° C., it was found to be excellent in form stability and to be used as a tire cord for cap ply. In contrast, it was confirmed that the tire cords of Comparative Examples 11 to 14 did not satisfy these characteristics.

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

Claims (11)

At least 90 mol% of polyethylene terephthalate, the crystallization degree is 53% or more after heat treatment at 230 ° C. for 1 minute under 20g / 1000d of ultra-high load, the amorphous Orientation Factor (AOF) is 0.15 or less, and the birefringence is Polyethylene terephthalate stretched yarn of 0.14 to 0.16. The polyethylene terephthalate stretched yarn according to claim 1, wherein the amorphous orientation index is 0.01 to 0.10. The (010) plane spacing of the crystal of the crystal calculated from the XRD measurement peak after heat treatment at 230 ° C. for 1 minute is 58 to 65 Å, the (110) plane spacing is 46 to 54 ,, and (100 ) Polyethylene terephthalate stretched yarn having a plane spacing of 44 to 52 mm 3. Polyethylene terephthalate tire cord comprising the stretched yarn according to any one of claims 1 to 3. The polyethylene terephthalate tire cord of claim 4 wherein the L / S value defined by Formula 1 below is between 70 g / d and 150 g / d: [Equation 1] L / S = LASE / Shrinkage (%) In the above formula, LASE is defined as Load At Specific Elongation at 100 ° C. The polyethylene terephthalate tire cord according to claim 4, wherein LASE is defined as a load at 3% elongation of 1.7 to 3.0 g / d when subjected to a tensile test under a supertension of 0.05 g / d and a temperature of 100 ° C. The polyethylene terephthalate tire cord according to claim 4, wherein the total fineness is 1000 to 5000 deniers (d), 1 to 3 plies and 200 to 500 TPM. The polyethylene terephthalate tire cord of claim 4, wherein the polyethylene terephthalate tire cord exhibits a strength of 5 to 8 g / d, a torsion of 1.5 to 5.0% (@ 4.5 kgf), and a stretch of 10 to 25%. The polyethylene terephthalate tire cord according to claim 4, which is a capfly cord. A pneumatic tire comprising the tire cord according to claim 4. The pneumatic tire according to claim 10, wherein the cord is applied to a cap ply.

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