KR102001061B1 - Polyethyleneterephthalate tire cord having good creep resistance - Google Patents

Abstract

The present invention relates to a polyethylene terephthalate (PET) cord and a manufacturing method thereof. The PET tire cord with a low creep ratio is provided by inducing crystallization directly under a nozzle by increasing spin draft, and increasing time and temperature for heat set at a high temperature in a godet roller.

Description

[0001] Description [0002] Polyethylene terephthalate tire cord having good creep resistance [0001]

The present invention relates to a polyethylene terephthalate tire cord excellent in thermal stability by adjusting spinning conditions.

In order to increase the strength of the polyester fiber used for industrial purposes, conventionally, a high-viscosity chip having an intrinsic viscosity of 1.0 dl / g or more is melted, the melt polymer temperature is sufficiently raised to 300 ° C. and then melted and solidified. Or less, and the unstretched yarn obtained by direct winding at a draw ratio of 5.0 or more in a first stage and a second stage was wound in a rack rack. 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.

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 unstretched fiber is minimized and then the high degree of stretching is performed.

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.

 In the case of conventional crystallization on the Godet roller by the conventional multi-stage stretching, the strength of the cord can be improved by the yarn, but it is vulnerable to thermal deformation when the tire is reinforced due to a large change due to heat.

The object of the present invention is to provide a tire cord having a low creep rate by raising the spin draft, inducing crystallization directly below the nozzle, and increasing the temperature and temperature for heat setting at a high temperature in a Godet roller.

In order to solve the above problems,

Melting a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 dl / g or more and extruding it through a nozzle having a diameter of 1.0 to 1.5 mm to prepare a discharged yarn;

Spinning the spinning yarn at a spin draft of 1500 to 2800 to produce an unstretched yarn;

Stretching the undrawn yarn to a stretching ratio of 1.4 to 2.0 using a stretching roller at a temperature of 250 DEG C or less; And

Twisting and dipping the yarn to produce a cord;

The present invention also provides a method of producing a polyethylene terephthalate tire cord.

According to a preferred embodiment of the present invention, the polyethylene terephthalate tire cord is characterized in that the creep ratio measured after vulcanization at a temperature of 170 캜 for 20 minutes under a load of 0.05 g / d is 6.0% or less.

In the present invention, the creep ratio measured at 80 占 폚, 1800 sec, 0.01 N / g (before vulcanization or simulated cure) is 3.0% or less, preferably 2.5% or less, more preferably 2.0 to 2.5% .

The creep rate measured after curing at 170 ° C for 20 minutes under a load of 0.05 g / d (after simulated curing) is 6.0% or less, preferably 5.0% or less, more preferably 4.5 to 5.0%.

 According to another preferred embodiment of the present invention, the polyethylene terephthalate tire cord is characterized by having a strength of 20 kgf or more and an E-S 6.0 or less based on 1500 d / 2ply.

According to another preferred embodiment of the present invention, there is provided a polyethylene terephthalate tire cord produced by the method for producing the polyethylene terephthalate tire cord.

In accordance with another preferred embodiment of the present invention, there is provided a belt comprising: a pair of parallel bead cores; at least one radial carcass layer wound around the bead cores; a belt layer laminated on the outer circumferential side of the carcass layer; And a belt reinforcing layer in the circumferential direction formed on the side of the tire, wherein the tire comprises the polyethylene terephthalate tire cord.

        The present invention facilitates the strength and high modulus of the yarn through the control of the spinning conditions and the simulation cure, and the durability of the yarn is greatly improved and the processability is superior to that of the existing tire cord.

Further, a tire having excellent thermal stability can be produced by using the above-mentioned dip cord.

Fig. 1 schematically shows a spinning and drawing process of a PET yarn according to the present invention.
FIG. 2 is an example schematically showing a dipping and heat-treating process of the PET cord according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.

The present invention is not limited to the scope of the present invention, but is merely an example, and various modifications can be made without departing from the technical spirit of the present invention.

The method for producing the polyethylene terephthalate 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 dl / g is melted and extruded while passing through a nozzle to produce a discharged yarn.

Here, the polyethylene terephthalate polymer may contain at least 90 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 dl / g at 240 to 260 ° C and under vacuum.

If the intrinsic viscosity of the raw chips is less than 1.0 dl / g, the intrinsic viscosity of the final stretch yarn is lowered and the processed cord after heat treatment can not exhibit high strength. If the intrinsic viscosity of the chips exceeds 1.15 dl / g, The cross-section of the discharge yarn becomes uneven and a large number of filament cuts occur during drawing, resulting in poor workability in drawing.

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. When the residual amount is less than 180 ppm, the polymerization reaction rate is slow and the low polymerization efficiency is lowered. When the residual amount exceeds 300 ppm, unnecessary antimony metal acts as a foreign substance and the radiation-drawing workability may be deteriorated.

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 1.0 to 1.5 mm. More preferably, the nozzle is 1.2 to 1.5 mm.

If the diameter of the nozzle is less than 1.0 mm, adhesion may occur before the discharged solution coagulates. If the diameter of the nozzle is more than 1.5 mm, the coagulation speed of the solution in the coagulation bath after spinning is slowed down.

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. At this time, the spin draft (spin draft) is 1500 to 2800, preferably 1700 to 2600, and more preferably 1800 to 2500. If the radiation draft is less than 1,500, the shrinkage rate is high. If the radiation draft is more than 2,800, the strength drops.

The spinning speed is preferably from 2,700 to 3,500 m / min. When spinning at the spinning draft and spinning speed within the above range, the yarn strength and high modulus can be secured even at a low stretching ratio. If the spinning speed is less than 2,700 m / min, the productivity and mechanical properties may be deteriorated. If the spinning speed is more than 3,500 m / min, workability, strength and modulus of the yarn may be lowered.

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

The stretching roller of the present invention consists of five Godet rollers. At this time, the GR 4 turn number is 10 to 18, preferably 12 to 16, and more preferably 13 to 15. If the GR 4 turn number is less than 10, the shrinkage rate is high. If it exceeds 18, the workability is degraded.

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 can be multi-filament drawn, and the temperature of each of the drawn filaments is 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, Is preferably 230 to 240 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 to 6,200 m / min or more. If the winding speed is less than 5,800 m / min, the productivity may be deteriorated. If the winding speed is more than 6,200 m / min, trimming occurs during winding, resulting in deterioration in workability.

Further, it is preferable that the total stretching ratio of the yarn formed by winding as described above is 1.4 to 2.0. When the stretching ratio is less than 1.4, the strength is not sufficient. When the stretching ratio is more than 2.0, the workability is decreased.

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

First, the prepared polyethylene terephthalate yarn is stretched by 300 to 500 twist / meter to be woven, but the present invention is not limited thereto.

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 softening time of the polyethylene terephthalate dip cords is set to 300/300 TPM to 500/500 TPM at the same value of the upper / lower temperature. 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.

The produced 'Raw Cord' is woven using a weaving machine, and the resultant fabric is dipped in the dipping solution and then cured to obtain a tire cord having a resin layer on the 'raw cord' surface 'Dip Cord' is manufactured.

Dipping is accomplished by impregnating the surface of the fiber with a resin layer called RFL (Resorcinol-Formaline-Latex), which improves the disadvantages of the fiber for tire cords, .

As one embodiment of the adhesive liquid for bonding the tire cord and the rubber, they may be prepared by using the following method. It is to be understood that the following examples are intended only for a better understanding of the present invention and are not intended to limit the scope of the present invention.

45.6 parts by weight of 29.4% by weight of resorcinol, 255.5 parts by weight of pure water, 20 parts by weight of 37% formalin and 3.8 parts by weight of 10% by weight sodium hydroxide. After the reaction solution was prepared and reacted with stirring at 25 ° C for 5 hours, . 300 parts by weight of 40 wt% VP-latex, 129 parts by weight of pure water, 23.8 parts by weight of 28% ammonia water, and aged at 25 캜 for 20 hours after the addition of the above components to maintain a solid concentration of 19.05%.

First, the cord yarn is immersed in an epoxy resin and a Pexul adhesive solution and dried.

The adhesive liquid is applied after drying. In order to control the adhesion amount of the adhesive liquid, 0 to 3% of stretch is preferably applied, more preferably 1 to 2% of stretch is required. If the stretch is too high, the adhesion amount (DPU) of the bonding liquid can be adjusted, but the result is a decrease in the resultant fatigue resistance. If the stretch is too low, for example, lower than 0% It becomes impossible to control the DPU by penetrating the deep liquid into the raw cord.

The adhesion amount of the adhesive is preferably 2 to 7% based on the weight of the fibers on a solid basis. After passing through the adhesive solution, it is dried at 120 to 230 ° C. At this time, it is important to perform drying for 180 to 220 seconds, and to dry the cord while applying a stretch of about -2 to 3% to the cord. If the stretch is insufficient, the cord length and turn-off of the cord increase, and the stretch characteristic is insufficient to apply to the tire cord. If the stretch exceeds 3%, the level of the chain is appropriate but the turn- .

After drying, heat treatment is performed in a temperature range of 130 to 250 ° C. Stretch during heat treatment is maintained between 0 and 2%, and heat treatment time is suitably between 50 and 90 seconds. When the heat treatment is performed for less than 50 seconds, the reaction time of the adhesive solution is insufficient and the adhesive force is lowered. When the heat treatment is performed for more than 90 seconds, the hardness of the adhesive solution is increased and the fatigue resistance of the cord is decreased Results will be obtained.

The present invention mainly describes the case of performing dipping using a two-bath dipping machine, but it is also possible to perform heat treatment under the same conditions using a single-bath dipping machine as long as a person skilled in the art is familiar.

In the present invention, a tire for a passenger car is manufactured by using the tire cord manufactured above as a carcass ply.

Hereinafter, the constitution and effects of the present invention will be described in more detail with reference to specific examples and comparative examples. However, these examples are merely for better understanding of the present invention and are not intended to limit the scope of the present invention. Properties of the tire cord and the like in Examples and Comparative Examples were evaluated by the following methods.

(a) Tire cord strength (kgf)

Dried at 107 DEG C for 2 hours, and then measured at a sample length of 250 mm and a tensile speed of 300 m / min using a low-speed stretching type tester manufactured by Instron.

(b) Intermediate elongation (%)

Means elongation at a load of 6.8 kg on the elongation load curve obtained by using a low speed elongation type tensile tester manufactured by INSTRONG under the JIS-L1017 method.

(c) modulus and strength

The yarn is allowed to stand in a standard temperature condition, that is, in a constant temperature and humidity room at a temperature of 25 ° C and a relative humidity of 65% for 24 hours, and then the sample is measured by a tensile tester by ASTM2256 method.

(d) 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. (S) represents the dry heat shrinkage ratio, and the sum of the elongation modulus (E) and dry heat shrinkage ratio (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 by the deformation of the tire. On the other hand, since it is possible to make the same amount of tension to produce the same tensile force, can do. 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.

E-S = elongation at specific load + dry heat shrinkage

(e) creep rate

Creep rates were measured with an Eplexor 500N instrument from GABO QUALITMETER. Hold the dip cord 3 cm up and down in the chamber where the temperature is kept constant, and measure. Simulated cure The dure cord was simulated by cure at 170 ℃, 20min, and 0.05g / d under load of 80N and 0.01N / g, The stretched length was measured at 18O < 0 > C under a load of 0.01 N / g constantly for 1800 seconds. And the term "creep ratio" is used in the present invention.

Creep ratio = ((length after cm2 cm 3 cm after 0.01 N / g load is applied for 1800 seconds) / 3 cm)) * 100%

Examples 1 and 2 and Comparative Examples 1 to 3

The polyethylene terephthalate polymer having a terephthalate unit content of 90 mol% or more and an intrinsic viscosity of 1.08 dl / g as measured by phenol / tetrachloroethane was radiated under the conditions shown in Table 1 using a radial-in-flow (RIF) A final drawn yarn (yarn) of 1540 to 1565 denier was prepared.

The prepared cord yarn was wound up and down with 370 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 for 150 seconds under a 3.0% stretch, then immersed in resorcinol formalin latex (RFL), dried at 170 ° C. for 100 seconds, and heated at 245 ° C. for 40 seconds under 4.5% Thereby preparing a tire cord.

The properties of the yarns prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were measured and evaluated in the same manner as described above, and the results are shown in Table 1 below.

The tire cords prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were vulcanized at 170 DEG C for 20 minutes, and physical properties (strength, modulus elongation, creep ratio) were evaluated by the above methods.

In Examples 1 and 2, the spin draft was set at 1822, 2500, and the stretching ratio and the GR4 temperature were set as shown in Table 1. In Comparative Examples 1 to 3, the spin draft was set at 531, 764, and 1470, The GR4 temperature was set as shown in Table 1.

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Example 1 Example 2 Condition Spin Draft 531 764 1470 1822 2500 GR 4 temperature 210 210 220 230 240 GR 4 turn number 7 7 7 14 14 Drt 2.09 2.26 2.12 1.90 1.66 Yarn properties Test 1540 1545 1560 1565 1560 Strong (Kg) 11.9 13.5 13.6 11.9 11.7 Doubt (%) 13.0 12.0 12.0 13.4 13.3 Shrinkage (Testlite) 8.0 7.0 5.5 3.2 2.9 Bottom
Properties Strong (Kg) 22.4 24.2 25.5 22.7 21.8 Chinese (%, @ 6.8kg) 5.0 4.6 3.7 3.7 3.4 Doubt (%) 17.6 15.7 13.5 15.8 17.7 Shrinkage (%) 2.1 2.0 2.1 1.8 1.8 E-S (%) 7.1 6.6 5.8 5.5 5.2 Creep (80) Before vulcanization (%) 3.5 3.2 3.3 2.5 2.0 Creep (80) after curing (%) 7.2 6.7 6.4 5.0 4.5

As can be seen from Table 1, the tire cords manufactured in Examples 1 and 2 and the tire cords prepared in Comparative Examples 1 to 3 were compared in terms of creep ratios before and after code simulation under the above conditions, It is possible to provide a polyethylene terephthalate cord having a lower value than those of Comparative Examples 1 to 3 and minimizing the creep property before and after the simulation cure of the deep cords, thereby enhancing the tire manufacturing process and the thermal stability occurring when the tire is used.

1: Extruder 2: Gear pump
3: Nozzle 4: Heating device
5: cooling zone 6: first godet roller (GR1)
7: second godet roller (GR2) 8: third godet roller (GR3)
9: fourth godet roller (GR4) 10: fifth godet roller (GR5)
11: Winding roller 12: Emulsion feeder
13: Bobbin 14: 1-dip
15: 1- Drying zone 16: 1- Heating zone
17: 2- Dip 18: 2- Drying zone
19: 2-heating zone 20: winder
31: Tire 32: Carcass layer
33: Carcass layer reinforcement cord 34: Fly turn-up
35: bead region 36: bead core
37: bead filler 38: belt structure
39: cap fly 40: belt fly
41, 42: belt cord 43: tread
44: edge fly 45: cap fly cord

Claims (6)

Melting a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 dl / g or more and extruding it through a nozzle having a diameter of 1.0 to 1.5 mm to prepare a discharged yarn;
Spinning the yarn out of the yarn with a spin draft of 1822 to 2500 to produce an unstretched yarn;
Stretching the undrawn yarn to a stretching ratio of 1.4 to 2.0 using a stretching roller at a temperature of 250 DEG C or less; And
Twisting and dipping the yarn to produce a cord;
Lt; / RTI >
Wherein the stretching roller in the stretching step is composed of five Godet rollers and the GR 4 turn number is in the range of 10 to 18. The polyethylene terephthalate tire dipped cord of claim 1, delete The method according to claim 1,
Wherein the polyethylene terephthalate tire dipped cord has a creep ratio of 6.0% or less measured after vulcanization at a temperature of 170 캜 for 20 minutes under a load of 0.05 g / d. The method according to claim 1,
Wherein the polyethylene terephthalate tire dipped cord has a strength of 20 kgf or more and ES 6.0 or less based on 1500 d / 2ply. A polyethylene terephthalate tire dip cord produced by the method of claim 1. A pair of parallel bead cores and at least one radial carcass layer wound around the bead cores, a belt layer laminated on the outer circumferential side of the carcass layer, and a radial air layer including a circumferential belt reinforcing layer formed on the outer circumferential side of the belt layer In the mouth tires,
Characterized in that the carcass layer comprises the polyethylene terephthalate tire dipped cord according to claim 5.

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