KR101968993B1 - Dimensionally stable polyethyleneterephthalate tire cord, method of manufacturing the same and tire including the same - Google Patents

Abstract

The present invention relates to a polyethylene terephthalate (PET) cord and a method for manufacturing the same. The crystallization is induced at a direct bottom of a nozzle by raising a spin draft, and heat set of a Godet roller is set to a high temperature, thereby providing a PET cord having low elongation change rate and having a low strength change rate after a high temperature tensile test.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyethylene terephthalate tire cord having excellent shape stability, a method for producing the tire cord, and a tire comprising the tire cord. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

TECHNICAL FIELD The present invention relates to a polyethylene terephthalate tire cord having excellent shape stability by controlling spinning conditions, a method for producing the tire cord, and a tire including the same.

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

The present invention aims at inducing crystallization directly below a nozzle by raising the spin draft and heat setting it at a high temperature in a Godet roller to produce a cord with a low thermal deformation to minimize the change of the cord caused by heat.

In order to achieve the above-mentioned object, the present invention provides a method of producing a polyethylene terephthalate tire cord by a melt spinning process, comprising melting a polyethylene terephthalate chip having an intrinsic viscosity of 1.0 dl / g or more, To produce a discharge yarn;

Spinning the spinning yarn at a spin draft of 1000 to 2500 to produce an unstretched yarn;

Stretching the undrawn yarn so as to have a stretching ratio of 1.4 to 2.0 using a stretching roller at a temperature of 240 DEG C or more; And

Wherein the polyethylene terephthalate tire cord has a tensile strength change rate of 30 to 60% under a tensile strength condition of 0.05 g / d for 20 minutes at a temperature of 170 DEG C In addition,

When the polyethylene terephthalate tire cord is subjected to a high temperature tensile test at 100 占 폚, the tensile strength of the polyethylene terephthalate tire cord is 10 to 30% of the tensile test result at room temperature.

According to another 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; Wherein the carcass layer comprises a polyethylene terephthalate tire cord provided by the method of manufacture. ≪ RTI ID = 0.0 > A < / RTI >

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 shape stability can be manufactured by using the above-mentioned dip cord.

Fig. 1 schematically shows a structure of a tire for a passenger car manufactured using a PET cord according to the present invention.
Fig. 2 schematically shows a spinning and drawing process of a PET yarn according to the present invention.
FIG. 3 schematically illustrates 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 solidifies. If the diameter of the nozzle exceeds 1.5 mm, the solidification rate 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. In this case, the radiation draft is 1000 to 2500, preferably 1500 to 2300, and more preferably 1800 to 2100. The spinning speed is preferably 3,000 to 3,200 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 3,000 m / min, productivity and mechanical properties may be deteriorated. If the spinning speed is more than 3,200 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 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 stretching process, the unstretched yarn can be multi-step stretched, and each of the stretching roller temperatures is higher than the glass transition temperature of the non-stretched yarn. In the present invention, the temperature of the godet roller GR4 is preferably 200 to 250 ° C. The temperature of the godet roller is preferably 240 ° C or higher, and more preferably 240 ° C to 250 ° C.

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 yarn ratio of the yarn formed by winding as described above is 1.4 to 2.0.

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 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.

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 an embodiment of the adhesive liquid for bonding the tire cord and the rubber, it can be prepared and used 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%.

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 the intermediate elongation (E) in the present invention, where the load means 6.8 kg. 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 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

Examples 1 to 2 and Comparative Examples 1 to 2

A 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 irradiated under the conditions of Table 1 using a radial-in-flow (RIF) To prepare a final drawn yarn (yarn) of 1545 to 1598 denier.

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, 2 and Comparative Examples 1 and 2 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, 2 and Comparative Examples 1 and 2 were vulcanized at 170 DEG C for 20 minutes, and physical properties (strength, modulus of elongation) were evaluated by the above methods.

In Example 1, the spin draft was set to 2093, the GR4 temperature was set to 250 ° C, the spin-draft to Example 2 was set to 1822, and the GR4 temperature to 245 ° C.

In Comparative Example 1, the spin draft was set to 764, the GR4 temperature was set to 230 ° C, the spin draft of Comparative Example 2 was set to 765, and the GR4 temperature was set to 235 ° C.

division Comparative Example 1 Comparative Example 2 Example 1 Example 2 Radiation condition Diameter (mm) of nozzle * number (number) 0.9 * 384 0.8 * 440 1.3 * 384 1.2 * 515 spin draft 764 765 2093 1822 Draw ratio 2.26 2.00 1.59 1.90 GR4 Temperature (℃) 230 235 250 245 Yarn Properties Denier (d) 1545 1580 1598 1557 Strong (Kgf) 13.5 11.7 10.7 11.9 Strength (g / d) 8.7 7.4 6.7 7.6 Chinese (%@6.8Kgf) 5.8 5.8 5.8 7.5 Doubt (%) 12.0 13.5 19.0 13.4 Shrinkage (%,
testrite 177 C, 2 min, 0.05 g / d) 6.6 5.9 2.0 3.2 E-S 12.4 11.7 7.8 10.7 D / C Properties Strength (S1) (Kgf) 23.5 22.9 20.1 22.7 (E1) (% @ 6.8Kgf) 5.1 3.7 3.4 3.6 Doubt (%) 15.7 16.3 22.9 15.8 After D / C curing
(170 DEG C, 20 min, 0.05 g / d) Strong (Kgf) 23.1 22.2 20.0 22.5 (E2) (% @ 6.8Kgf) 9.5 6.1 5.2 5.5 Doubt (%) 20.7 18 26.7 17.5 (E2-E1) / E1 86.3% 64.9% 52.9% 52.8% D / C high temperature seal
(100 DEG C) Strength (S2) (Kgf) 15.9 14.4 15.4 16.1 (E3) (% @ 6.8Kgf) 7.7 6.7 5.7 6.3 Doubt (%) 17.2 18.0 26.1 17.1 Strong change rate (S2-S1) / S1 -32.3% -37.1% -23.4% -29.1%

As can be seen from Table 1, the tire cord manufactured in Examples 1 and 2 of the present invention and the tire cord prepared in Comparative Examples 1 and 2 were compared with each other, In Examples 1 and 2, the yarn shrinkage ratio and the tire dipped cord were found to be less than those of the comparative examples, and the tensile strength of the deep cord was much lower than that of Comparative Examples.

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 (5)

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 discharged yarn with a spin draft of 1800 to 2100 to produce an unstretched yarn;
Stretching the undrawn yarn so as to have a stretching ratio of 1.4 to 2.0 using a stretching roller at a temperature of 240 DEG C or more; And
And twisting and dipping the yarn to produce a polyethylene terephthalate tire cord,
Wherein the polyethylene terephthalate tire cord has a tensile strength of 0.05 g / d at a temperature of 170 캜 for 20 minutes under a tensile strength of 30 to 60%. delete The method according to claim 1,
Wherein said polyethylene terephthalate tire cord has a tensile strength lowered by 10 to 30% of a tensile test at room temperature when subjected to a high temperature tensile test at 100 占 폚. A polyethylene terephthalate tire 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 cord according to claim 4.

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