KR101602387B1 - Method of manufacturing polyethyleneterephthalate tire cord with high modulus and polyethyleneterephthalate tire cord manufactured by the same method - Google Patents

Abstract

The present invention relates to a method for manufacturing polyethylene terephthalate tire cord with high modulus and to a method for manufacturing polyethylene terephthalate yarn and tire cord which changes the micro structure of the polyethylene terephthalate yarn by improving processes of weaving and drawing the polyethylene terephthalate yarn forming tire cord, and polyethylene terephthalate yarn and tire cord manufactured thereby. The present invention comprises the steps of: melting polyethylene terephthalate chips with intrinsic viscosity of 1.0-1.15 and extruding the molten chips via a nozzle with a diameter of 1.1-1.4 mm to manufacture undrawn yarn; passing the undrawn yarn through drawing rollers to perform a multi-staged drawing process and performing a winding process at a winding speed of 5800 m/min or more to manufacture yarn, formed by the winding process, of total stretch ratio of 2.14-2.22; and twisting the yarn with a twisting machine to manufacture raw cord, and manufacturing dipping-treated tire cord by weaving the raw cord, immerging the woven cord in a dipping solution, drying the cord, and heat-treating the dried cord.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a method for producing high modulus polyethylene terephthalate tire cords and high modulus polyethylene terephthalate tire cords prepared therefrom. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high modulus polyethylene terephthalate tire cord,

The present invention relates to a method for producing a high modulus polyethylene terephthalate tire cord, and more particularly, to a method for producing a high modulus polyethylene terephthalate tire cord, which comprises the steps of: preparing a polyethylene terephthalate yarn having a microstructure of polyethylene terephthalate yarn And a high modulus polyethylene terephthalate tire cord produced therefrom.

In order to increase the strength of the polyester fiber used for industrial purposes, conventionally, after melting a high-viscosity chip having an intrinsic viscosity of 1.0 dl / g or more, the molten polymer temperature is sufficiently elevated to 300 ° C. and then melted and solidified. And the unstretched warp yarn obtained by winding at a low speed of 1,000 or less was directly stretched to a stretch ratio of 5.0 or more in one or two stages and relaxed and wound.

At this time, the degree of orientation of the undrawn yarn was lowered by low-speed winding, and high-strength characteristics were obtained by giving high-degree of extension.

However, since the yarn produced by the conventional method as described above has a high shrinkage ratio, when applied to a tire cord, the dimensional stability of the tire is deteriorated and shape distortion may occur.

In addition, the conventional method as described above is characterized in that the temperature of the heating hood and the cooling wind is appropriately adjusted so that the degree of orientation of the non-drawn filament is minimized and then the filament is drawn at a high magnification.

When the stretching magnification is increased to obtain fibers of higher strength by using the conventional spinning technique, the viscosity at the time of spinning, the shrinkage rate of the yarn due to high-rate stretching and the shape stability are lowered due to the high temperature of the heating hood during spinning. A large number of pin yarns and a problem in the process of causing a lot of spinning yarns due to high-magnification stretching lead to a decrease in post-processability. In addition, there is a problem in that the viscosity of the high viscosity polyethylene terephthalate resin is lowered during spinning, the shrinkage rate of the yarn is increased by high-rate stretching, and the shape stability is lowered. In the HMLS method for overcoming the above-mentioned problems, there is a problem that when the strength is taken in terms of strength and shape stability, the morphological stability is deteriorated, and when the morphological stability is improved, desired strength is not obtained.

U.S. Patent Nos. 4,101,525 and 4,491,657 disclose industrial polyethylene terephthalate yarns having high initial modulus and low shrinkage by manufacturing yarns by high speed spinning.

However, it is known that the yarns disclosed in these patents do not satisfy the characteristics required for tire cords due to their reduced strength when used as tire cords.

In order to produce a polyethylene terephthalate yarn which can be used for a tire cord, it is advantageous to increase the strength and strength of the yarn by increasing the non-crystallization in the microstructure of the yarn by the low radiation draft and the high stretching ratio in the spinning process. However, The shrinkage ratio is high and the strength utilization ratio (strength of the treated cord / strength of the yarn) is lowered. Therefore, there is a problem that a high-strength yarn must be manufactured to compensate.

On the other hand, the tire cord using the polyethylene terephthalate yarn having the orientation and crystal structure developed with high radiation draft and low stretching ratio has excellent modulus and strength utilization, but the strength is lowered after the heat treatment.

In addition, if the spinning draft and the stretching ratio condition of the spinning process are set to the middle of the above range, the microstructure and physical properties of the yarn are moderately exhibited, which makes it difficult to obtain the high strength required for the tire cord.

In order to solve the above-mentioned problems, the present invention provides a high modulus polyethylene terephthalate tire cord having a high tensile strength, And to provide a high modulus polyethylene terephthalate tire cord produced therefrom.

In order to achieve the above-mentioned object, the present invention provides a method for producing a non-drawn filament yarn, comprising melting a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 to 1.15 and extruding through a nozzle having a diameter of 1.1 to 1.4 mm to produce an undrawn filament; The unstretched yarn is passed through a stretching roller to be multi-step stretched, and wound up at a take-up speed of at least 5800 m / min to produce a yarn having a total m / m ratio of 2.14 to 2.22 of the wound yarn; And a step of preparing a raw cord by spinning the yarn with a twisted yarn, and then dipping the yarn into a dipping solution to prepare a dipped tire cord to be dried and heat-treated. [5] The high modulus polyethylene terephthalate tire cord Of the present invention.

Here, the tire cord preferably has a strength of 16 kgf or more, a morphology stability index (modulus of elongation + dry heat shrinkage) of 6.0% or less, a storage modulus of 9500 MPa or more, a creep (@ 80 ° C, 1800 sec) Or less.

The present invention can easily secure the strength of yarn by adjusting the spinning conditions, and the durability of the yarn is improved by using the yarn, and the property is significantly improved and the processability is superior to that of the conventional tire cord.

Further, the tire cord according to the present invention is excellent in strength and shape stability, so that even when a small amount of tire cord is used in manufacturing a tire, the tire cord can exhibit the same strong effect as the conventional tire, thereby reducing the weight of the tire.

In addition, the tire cord according to the present invention can exhibit higher stability than a conventional tire cord at high speed traveling due to its high storage elastic modulus and low creep characteristics.

1 is a view showing the spinning and stretching process in the production of the polyethylene terephthalate yarn of the present invention.
2 is a view showing the dipping process, the drying process and the heat setting process in the production of the polyethylene terephthalate tire cord of the present invention.
3 is a graph showing changes in storage elastic modulus of the polyethylene terephthalate tire cord of the present invention with temperature.
4 is a graph showing the creep change according to temperature of the polyethylene terephthalate tire cord of the present invention.

Hereinafter, the present invention will be described in detail.

The present invention relates to a process for producing a non-drawn filament yarn by melting a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 to 1.15 and extruding it through a nozzle having a diameter of 1.1 to 1.4 mm; The unstretched yarn is passed through a stretching roller to be multi-step stretched, and wound up at a take-up speed of at least 5800 m / min to produce a yarn having a total m / m ratio of 2.14 to 2.22 of the wound yarn; And a step of preparing a raw cord by spinning the yarn with a twisted yarn, and weaving the raw cord to produce a dipped tire cord, which is dipped in a dipping solution, followed by drying and heat treatment. to provide.

The method for producing a polyethylene terephthalate tire cord according to the present invention will be described in detail as follows.

First, a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 to 1.15 is melted and extruded while passing through a nozzle to produce a discharged yarn.

Here, the polyethylene terephthalate polymer may contain at least 85 mol% of ethylene terephthalate units, but may optionally contain only ethylene terephthalate units.

Optionally, the polyethylene terephthalate may comprise small amounts of units derived from ethylene glycol and terephthalenedicarboxylic acid or derivatives thereof and one or more ester-forming components in copolymer units. Examples of other ester forming components copolymerizable with the polyethylene terephthalate unit include glycols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and the like, and glycols such as terephthalic acid, isophthalic acid, hexahydroterephthalic acid, Dicarboxylic acids such as dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, dicarboxylic acid, dicarboxylic acid,

The terephthalic acid (TPA) and the ethylene glycol raw material are melt-mixed at a ratio of 2.0 to 2.3 to the polyethylene terephthalate chip thus prepared, and the molten mixture is transesterified and condensed to form a raw chip. Then, the low chip is subjected to solid phase polymerization so as to have an intrinsic viscosity of 1.0 to 1.15 at a temperature of 240 to 260 DEG C and a vacuum.

If the intrinsic viscosity of the raw chips is less than 1.0, the intrinsic viscosity of the final drawn yarn is lowered and the treated cord after heat treatment can not exhibit high strength. If the intrinsic viscosity of the chips exceeds 1.15, the radiation tension is excessively increased, The cross section becomes nonuniform, and many filament cuts occur during stretching, resulting in poor workability in stretching.

Alternatively, an antimony compound, preferably antimony trioxide, may be added as a polymerization catalyst in the course of the condensation polymerization reaction so that the residual amount of antimony metal in the final polymer is 180 to 300 ppm. If the residual amount is less than 180 ppm, the polymerization reaction rate is slowed to lower the polymerization efficiency. If the residual amount exceeds 300 ppm, unnecessary antimony metal acts as a foreign substance and the radiation-drawing workability may be lowered.

The polyethylene terephthalate chip is melted and extruded while passing through a nozzle to produce a discharged yarn.

At this time, the diameter of the nozzle is preferably 1.1 to 1.4 mm.

Thereafter, the discharged yarn is quenched and solidified by passing through a cooling zone. At this time, if necessary, a heating device of a certain length is provided in a distance from the nozzle to the starting point of the cooling zone, that is, the length (L) of the hood.

This zone is referred to as the delayed cooling zone or heating zone, which has a length of 50 to 250 mm and a temperature of 250 to 400 ° C (air contact surface temperature).

In the cooling zone, an open quenching method, a circular closed quenching method, a radial outflow quenching method, and a radial in flow quenching ) Method, but the present invention is not limited thereto.

At this time, the temperature of the cooling air injected for quenching in the cooling zone is adjusted to 20 to 50 캜. Such quenching using the sudden temperature difference between the hood and the cooling zone is intended to increase the solidification point and the radiation tension of the radiated polymer to increase the orientation of the undrawn yarn and the formation of the connection chain between the crystal and the crystal.

Thereafter, the solidified yarn passing through the cooling zone can be oiled at 0.5 to 1.2% by weight with respect to the discharged yarn by reducing the coefficient of friction between the tweezers and applying an emulsion applying apparatus having excellent stretchability and thermal efficiency.

And the oiled discharged yarn is radiated to form an unstretched yarn. In this case, the spinning draft is preferably 1500 to 1800, and the spinning speed is preferably 3,000 to 3,200 m / min. When spinning at the spinning draft and spinning speed in the above range, excellent strength of the yarn can be secured even at a low stretching ratio.

If the radiation draft is less than 1,500 or the spinning speed is less than 3,000 m / min, the uniformity of the cross section of the yarn is deteriorated to deteriorate the drawing workability and the degree of orientation of the unstretched yarn is decreased to degrade the crystallization degree. , The thermal stability is lowered, the strength of the tire cord is lowered, and the shape stability may be lowered when the high stretching is performed to improve the strength and modulus. When the breaking strength is higher than 3,200 m / min, The strength and elongation workability are deteriorated.

If the degree of orientation of the undrawn yarn is less than 0.06, the crystallinity and the denseness of the crystal can not be increased in the microstructure of the yarn. If the degree of orientation is less than 0.80, the drawability is deteriorated.

Thereafter, the non-drawn yarn is passed through a stretching roller to be multi-step stretched to produce a yarn.

The yarn passed through the first stretching roller is stretched while passing through a series of stretching rollers by a spin draw method to form a yarn.

In the drawing step, the non-drawn filaments may be multi-filament drawn, and the temperature of each of the drawn filaments is preferably higher than the glass transition temperature of the unstretched filament and lower than 95 캜, but the final filament roller temperature is preferably 200 to 250 캜.

If the temperature of the last stretching roller is lower than 200 ° C, the crystallinity and the size of crystals do not increase in the stretching process, and the strength and thermal stability of the yarn are not exhibited, so that the morphological stability is deteriorated at high temperature. There is a problem that the microstructure of the yarn becomes uneven and the strength of the yarn is lowered.

At this time, the winding speed of the drawn yarn is preferably 5,800 m / min or more. If the winding speed is less than 5,800 m / min, the productivity may be deteriorated.

Further, it is preferable that the total yarn m of the yarn formed by winding as described above is 2.14 to 2.22. When the stretching ratio is less than 2.14, the productivity is lowered and the strength of the yarn and the cord is lowered. When the stretching ratio exceeds 2.22, crystallization of the oriented non-gelling portion is increased, It is not preferable because the molecular chain of the noncrystalline chain is broken and the uniformity of the molecular chain is lowered and the strength utilization ratio may be lowered.

Thereafter, the produced polyethylene terephthalate yarn is used for twisting, weaving and dipping to produce a dipped cord.

First, the polyethylene terephthalate yarn is twisted with a direct twisted yarn in which twisting and twisting are simultaneously performed to produce a raw cord for a tire cord.

The twist yarns are produced by applying ply twist to a polyethylene terephthalate yarn followed by joining by applying a cable twist. Generally, the upper and lower yarns are subjected to the same softening (level of twist) or other softening as required .

In the present invention, the softener of polyethylene terephthalate dip cords has a value of 300/300 TPM (Twist Per Meter) to 500 TPM / 500 TPM in the same value. When the upper and lower edges are made to have the same numerical value, the manufactured dipped cords do not show any rotation or twist, and are easily maintained in a straight line, thereby maximizing physical property development. In this case, when the number of years of the upper / lower ends is less than 300/300 TPM, the yield of the cord is decreased and the fatigue resistance tends to be lowered.

Thereafter, the woven yarn is loaded on a dipping solution, dried, stretched and heat-set, then immersed again in the dipping solution, dried and heat-set to produce a dipped cord.

The dipping solution is not particularly limited, but it is preferably epoxy resin, para-chlorophenol resorcinol / formalin mixed resin (Pexul).

At this time, the drying should be avoided at a high temperature, and the drying is preferably performed at 90 to 180 ° C for 180 to 220 seconds. If the drying temperature is lower than 90 ° C, drying may not be sufficiently performed, and gelation may occur due to the dipping resin when dried and heat treated. When the drying temperature is higher than 180 ° C, Uneven adhesion of the cord and the deep liquid resin may occur.

The hot fixation is performed so that the cord impregnated in the deep liquid resin has an appropriate adhesive strength with the tire rubber, and the heat fixation temperature is preferably from 220 to 250 DEG C for 50 to 90 seconds. When the heat fixation is performed in less than 50 seconds, the adhesive force is insufficient due to the short reaction time of the adhesive solution, and when the heat fixation is performed for 90 seconds or more, the hardness of the adhesive solution becomes low and the fatigue resistance of the cord may be reduced.

The tire cord manufactured as described above had a strength of 16 kgf or more, a morphology stability index (modulus of elongation + dry heat shrinkage) of 6.0% or less, a storage elastic modulus of 9500 MPa or more, and creep (@ 80 ° C, 1800 seconds) 2.0% or less.

Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrating the present invention specifically, and the scope of the present invention is not limited to these examples.

Examples 1 to 2 and Comparative Examples 1 to 4

A solid phase polymerized polyethylene terephthalate chip having an intrinsic viscosity (I.V.) of 1.10 and a water content of 10 ppm containing 220 ppm of antimony metal was prepared.

The prepared chip was passed through a spinning nozzle as shown in Table 1 at a temperature of 290 ° C using an extruder to form a discharged yarn. Thereafter, the blast furnace yarn was solidified by passing through a heating zone (atmosphere temperature 340 ° C) with a direct nozzle length of 60 nm and a cooling zone (blowing with cooling air having an air velocity of 0.5 m / s at 20 ° C) having a length of 500 mm, (Containing 70% paraffin oil component). The untreated yarn was wound up at the draw ratio and the speed shown in Table 1 to produce the final yarn.

The prepared cord yarn was wound up and down with 470 twist / meter to prepare a cord yarn. The cord yarn was immersed in an adhesive solution of epoxy resin and Pexul in a dipping tank, and then dipped in a drying zone at 170 ° C under 4.0% Dried and heat-set at 245 ° C in a hot stretching zone at 150 ° C for 150 seconds, immersed again in resorcinol formalin latex (RFL), dried at 170 ° C for 100 seconds, and heated at 245 ° C for 4 seconds under 40% And heat-set the tire cord to produce a dipped tire cord.

Evaluation example 1

The properties of the tire cords prepared in Examples 1 and 2 and Comparative Examples 1 to 4 were evaluated by the following methods. The results are shown in Table 1 below.

(1) Strength (kgf), medium elongation (%)

After standing at 25 ° C and 65% RH for 24 hours, a low tensile tensile tester of Instrong Co. was used. The tire cord was twisted at 80 TPM (Twist Per Meter) Measured at a speed of 300 m / min.

The applied elongation at this time represents the elongation at the point of load of 4.5 g / d.

(2) Dry Heat Shrinkage (%, Shrinkage)

(L0) measured at a constant load of 0.05 g / d and a ratio of the length (L1) after treatment at a constant load of 0.05 g / d for 2 minutes at 177 ° C, after being left at 25 ° C and 65% RH for 24 hours And shows the dry heat shrinkage ratio.

S (%) = (L0 - L1) / L0 100

(3) E-S

The elongation under a constant load is referred to as intermediate elongation (E) in the present invention, and the load at this time is 4.5 g / d. The term (S) means the dry heat shrinkage rate in the above (2), and the sum of the elongation modulus (E) and dry heat shrinkage rate (S) is referred to as E-S in the present invention.

Generally, when the tire is vulcanized, the shrinkage rate and modulus of elongation of the cord are changed. The sum of shrinkage and modulus of elongation is similar to the modulus concept of the code after the tire is fully fabricated.

That is, when the E-S value is low, a correlation is formed in which the modulus becomes high. If the modulus is high, it is easier to steer because of the large amount of force generated due to the deformation of the tire. On the other hand, it is possible to make a small deformation to produce the same tensile force. . Therefore, the E-S value is utilized as a property value for judging the superiority of the code performance in tire manufacturing.

In addition, since a deformation amount due to heat is small in a tire having a low E-S value in the manufacture of a tire, the uniformity of the tire is improved, thereby improving the uniformity of the tire as a whole. Therefore, in the case of a tire using a code having a low E-S value, it is possible to improve the tire performance because the uniformity of the tire is higher than that of a tire using a high code.

ES = elongation at specific load + dry heat shrinkage

(4) Storage modulus

For storage elastic modulus measurement, DMTS (Dynamic Mechanical Tensile Spectroscope) was used.

The DMTS condition was a temperature range of 20 to 180 ° C, a rate of temperature increase of 3 / min, a static load of 0.01 N / d (1000 dPulse to 20 N), a dynamic load of 5 N, mm, and the storage elastic modulus was calculated by the following equation. The results are shown in Table 1 and FIG. 3 below.

(In the above formula, F denotes a load acting on,? A0 denotes a cross-sectional area,? 1 denotes a length variation of the material, and 10 denotes an original length of the material.

(5) Creep

The creep of the cord was measured for 1800 seconds while maintaining a static load of 0.01 N / d (1000 d 2ply to 20 N) and a dynamic load of 5 N at 80 ° C. The results are shown in Tables 1 and 4 Respectively.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Radiation condition Diameter of nozzle (mm) * number (pieces) 1.3 * 249 1.3 * 249 0.8 * 249 0.8 * 249 0.8 * 328 1.0 * 249 GR1 (m / min) 2680 2680 2650 2510 2950 2740 GR4 (m / min) 5800 5850 5650 5600 5700 5800 Stretching cost 2.16 2.18 2.13 2.23 1.93 2.12 Temperature of GR4 (℃) 220 230 210 210 210 220 Code property Denier 1000d / 2ply (470 TPM) Strong (kgf) 16.4 16.5 15.5 15.9 15.2 16.1 Strength (g / d) 8.2 8.3 7.8 8.0 7.6 8.1 Chinese (%) 4.0 3.9 4.2 4.2 4.1 4.1 Doubt (%) 14.9 14.4 14.2 14.3 15.3 14.7 Shrinkage (%) 1.8 1.8 1.8 1.8 1.8 1.8 E-S 5.8 5.7 6.0 6.0 5.9 5.9 Storage modulus (MPa) 10,100 10,300 9,310 9,440 9,360 9,820 creep (%) 1.97 1.74 2.85 3.10 3.04 2.07

As can be seen from the above Table 1, the dip codes prepared in Examples 1 and 2 of the present invention are superior in the shape stability index (ES) value and the intermediate elongation value as compared with the dip codes prepared in the Comparative Example, 1 and 2, it was confirmed that the dipped cords produced by the present invention had a high storage elastic modulus and a low creep property and thus were excellent in form stability.

1: Extruder 2: Gear pump
3: Nozzle 4: Heating device
5: cooling zone 6: drawn godet roller GR1
7: Drawing godet roller GR2 8: Drawing godet roller GR3
9: Drawing godet roller GR4 10: Drawing godet roller GR5
11: Winding roller 12: Emulsion feeder
13: Bobbin 14: Primary immersion zone
15: Primary drying zone 16: Primary heat-setting zone
17: Second immersion zone 18: Secondary drying zone
19: secondary heat fixing zone 20: winder

Claims (3)

Melting a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 to 1.15 and extruding through a nozzle having a diameter of 1.1 to 1.4 mm to produce an unstretched fiber;
The unstretched yarn is passed through a stretching roller to be multi-step stretched, and wound up at a take-up speed of at least 5800 m / min to produce a yarn having a total m / m ratio of 2.14 to 2.22 of the wound yarn; And
And a step of preparing a raw cord by spinning the yarn with a twisted yarn, and then dipping the yarn into a dipping liquid to dry and heat-treat the dipped tire cord,
The tire cord preferably has a strength of 16 kgf or more, a morphology stability index (modulus of elongation + dry heat shrinkage) of 6.0% or less, a storage modulus of 9500 MPa or more, and a creep (80 ° C, 1800 sec) Characterized in that the high modulus polyethylene terephthalate tire cord is produced. delete delete

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