KR102166025B1 - Process for manufacturing high modulus low shrinkage polyethylene terephthalate fiber and the polyethylene terephthalate fiber manufactured thereby - Google Patents

Abstract

The present invention relates to a method of manufacturing a high-strength low-shrink polyethylene terephthalate yarn, and to a polyethylene terephthalate yarn and tire cord manufactured through the same, and more particularly, to a six-stage Godet roller for stretching polyethylene terephthalate chips after melt spinning them. The method for producing polyethylene terephthalate yarns with high strength and low shrinkage even at low draw ratios by drawing so that the total draw ratio is 1.8 or less and controlling the single yarn fineness (DPF) of the fibers, the nozzle hole diameter, and the temperature and speed of the godet roller during spinning. It relates to PET yarn.

Description

Manufacturing method of high-strength low-shrink polyethylene terephthalate yarn, and polyethylene terephthalate yarn manufactured through it

The present invention relates to a method for producing a high-strength low-shrink polyethylene terephthalate yarn and a polyethylene terephthalate yarn produced through the same. More specifically, after melt spinning the polyethylene terephthalate chip, it is stretched to a total draw ratio of 1.8 or less using a six-stage stretching godet roller facility, and the single yarn fineness (DPF) of the fiber, nozzle hole diameter, and godet roller during spinning. The present invention relates to a method for producing a polyethylene terephthalate yarn having a high strength and a low shrinkage even at a low draw ratio by controlling the temperature and speed of, and a PET yarn produced thereby.

Tires are a composite of fiber/steel/rubber. In other words, steel and fiber cords reinforce rubber and form a basic skeleton structure within the tire. In other words, compared to the human body, it is like a bone.

The performance required for the cord as a tire reinforcement material is fatigue resistance, shear strength, durability, rebound elasticity, and adhesion to rubber. Therefore, a cord made of an appropriate material is used according to the performance required for the tire. Currently commonly used materials for cords include rayon, nylon, polyester, steel, and aramid. Rayon and polyester are used for body ply (or carcass), nylon is mainly used for cap ply, and steel. And aramid are mainly used for tire belts.

Tread is a part in contact with the road surface, provides frictional force necessary for braking and driving, has good wear resistance, must be able to withstand external shocks, and must have low heat generation. Body Ply (or Carcass) is a layer of cord inside the tire, which supports loads, withstands impacts, and must be resistant to flexion during driving. The belt is located between the body fly, and in most cases, it is composed of a steel wire. It not only alleviates external impacts, but also maintains a wide tread tread to provide excellent driving stability. Side Wall refers to the rubber layer between the bead from the bottom of the shoulder and protects the inner body fly. BACKGROUND ART In recent years, the development of tires suitable for high-speed driving is required according to the high-end of passenger cars, and 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 becoming more important than anything else. Steel belts existing in tires are generally arranged in a diagonal direction, but during high-speed driving, these steel belts tend to move in the circumferential direction by centrifugal force, and at this time, the tip of the sharp steel belt breaks the rubber or causes cracks. There is a risk of separation between belt layers and deformation of tire shape. Cap fly acts to improve high-speed durability and driving stability by catching the movement of the steel belt and suppressing the separation between layers and deformation of the tire shape.

Polyethylene terephthalate (PET) fibers have been applied to general capply cords for high strength and high strength. However, in the case of the PET fiber as described above, the draw ratio was set high to develop high strength and spun. That is, the existing high strength polyethylene terephthalate (PET) multifilament was able to achieve high strength and strength by maximizing the orientation of the polymer chain by maximizing the stretching ratio during PET spinning, but had a disadvantage of increasing the shrinkage rate. In addition, in the case of the low-shrink PET fiber, although the draw ratio was reduced and the spin draft was raised to induce a large amount of crystal structure, there was a disadvantage in that the strength value was lowered. A high shrinkage rate causes a problem that leads to a decrease in driving stability and ride comfort.

Korean Patent No. 1,746,029 Korean Patent Publication No. 10-2001-0011919 Korean Patent Registration No. 448,008 Japanese Laid-Open Patent No. 2002-105751

The present invention was devised to solve the above-described problems, and despite being stretched under a low draw ratio condition, the final fabricated yarn enables high strength expression and decreases the shrinkage rate of the yarn by increasing the crystallinity on the microstructure. Through spinning technology, it is intended to finally provide a method of manufacturing a high-strength low-shrink polyethylene terephthalate yarn.

In addition, it is an object of the present invention to provide a high-strength low-shrink polyethylene terephthalate yarn manufactured by the manufacturing method of the present invention and a tire cord comprising the same.

In order to achieve the above object, the present invention comprises the steps of melting polyethylene terephthalate chips having an intrinsic viscosity of 1.05 to 1.10 dL/g and spinning them through a nozzle to prepare undrawn yarn; And preparing a polyethylene terephthalate yarn by stretching the undrawn yarn with a facility to which 6 stages of a drawn godet roller are applied, and stretching and winding so that the total draw ratio is 1.8 or less, wherein the number of holes in the nozzle is a single yarn fineness ( DPF) is set to be 3.0 to 4.5, and the hole diameter of the nozzle is 0.8 to 1.6 mm, and the temperature at the fourth and fifth stages of the stretching godet roller is 240 to 250°C. It provides a method of manufacturing phthalate yarn.

It is preferable to wind up in the range of 3500 to 4200 m/min in the first step of the stretching godet rollers, and in the range of 6500 to 6900 m/min in the fourth and fifth steps of the stretching godet rollers.

The high-strength low-shrink polyethylene terephthalate yarn has a strength of 7.2 g/d or more, and a shrinkage rate of 3.0% or less, measured under the condition of applying a load of 0.05 g/d for 2 minutes at 177°C, and the number of fluffs generated per 5000 m It is characterized by three or less.

The present invention also provides a high-strength low-shrink polyethylene terephthalate yarn manufactured by the above manufacturing method.

In addition, the present invention includes the high-strength low-shrink polyethylene terephthalate yarn, the strength of the 1500d/2 dip cord is 6.3g/d or more, and the shrinkage rate under the condition of applying a 0.05g/d load for 2 minutes at 177°C is 2.0%. It provides a tire cord characterized in that the following.

The manufacturing method of the yarn of the present invention can produce a high-strength PET yarn even under conditions of a low draw ratio, and at the same time provides a PET yarn with a low shrinkage, so the manufactured PET yarn and a tire cord including the same have high strength and low shrinkage. At the same time, there is an advantage of obtaining satisfactory mechanical properties.

1 schematically shows the manufacturing process of the polyethylene terephthalate yarn of the present invention.
2 schematically shows a dipping process of the dip code of the present invention.

Hereinafter, the present invention will be described in detail.

Conventionally, in order to manufacture high-strength polyester yarns, undrawn yarn obtained by melt spinning PET chips of high viscosity has been manufactured by applying a high draw ratio. The most important physical property in a tire cord manufactured using high-strength polyester yarn is high strength, but in recent years, the necessity of developing a tire cord having a low shrinkage has increased in order to improve driving stability and ride comfort.

As before, in order to develop the high strength of the tire cord, a method of setting a high draw ratio in the spinning process was selected, but increasing the draw ratio increased the strength value, but at the same time, there was a problem of increasing the shrinkage rate. In order to lower the shrinkage rate, it was necessary to increase the degree of crystallinity on the microstructure of the yarn.

Therefore, in the related art, there has been a need for a study of differentiated spinning technology to manufacture PET yarns having high strength and low shrinkage properties.

Accordingly, the present invention provides heat at a high temperature in the stretched godet roller 4 (GR4) and the stretched godet roller 5 (GR5), which are the maximum stretching sections, in order to produce PET (polyethylene terephthalate) yarns that exhibit high strength and reduce shrinkage. It was found that the crystallinity of PET yarn can be increased. In addition, a manufacturing method was developed to maximize the spinning draft to reduce the shrinkage rate and create a microstructure capable of expressing high strength. According to the present invention, an ultra-high-speed spinning technology is introduced to provide a method for manufacturing PET yarns that exhibit high strength despite a reduction in draw ratio.

The present invention comprises the steps of melting polyethylene terephthalate chips having an intrinsic viscosity of 1.05 to 1.10 dL/g and spinning them through a nozzle to prepare undrawn yarn; And preparing a polyethylene terephthalate yarn by stretching the undrawn yarn with a facility to which 6 stages of a drawn godet roller are applied, and stretching and winding so that the total draw ratio is 1.8 or less, wherein the number of holes in the nozzle is a single yarn fineness ( DPF) is set to be 3.0 to 4.5, and the hole diameter of the nozzle is 0.8 to 1.6 mm, and the temperature at the fourth and fifth stages of the stretching godet roller is 240 to 250° C. High strength low shrinkage (HMLS) It provides a method for producing polyethylene terephthalate yarn.

A detailed description of the manufacturing method of high-strength low-shrink polyethylene terephthalate (PET) yarn according to the present invention is as follows.

First, a polyethylene terephthalate chip is melted and extruded while passing through a nozzle to produce a discharge 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 include a small amount of units derived from ethylene glycol and terephthalene dicarboxylic acid or derivatives thereof and one or more ester-forming components as a copolymer unit. Examples of other ester-forming components copolymerizable with polyethylene terephthalate units include glycols such as 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, terephthalic acid, isophthalic acid, hexahydroterephthalic acid, and stilbene dica. Dicarboxylic acids such as carboxylic acid, bibenzoic acid, adipic acid, sebacic acid, and azelaic acid.

Terephthalic acid (TPA) and ethylene glycol raw materials are melt-mixed in a ratio of 2.0 to 2.3 in the prepared polyethylene terephthalate chips, and the melt mixture undergoes transesterification and condensation-polymerization to form raw chips. Thereafter, the low chip is subjected to solid phase polymerization to have an intrinsic viscosity of 1.05 to 1.10 dl/g under a temperature of 240° C. to 260° C. and vacuum. The intrinsic viscosity of a preferred raw chip in the present invention is 1.055 to 1.095 dl/g.

At this time, if the intrinsic viscosity of the low chip is less than 1.05dl/g, the intrinsic viscosity of the final drawn yarn is lowered, so that the high strength cannot be exhibited as a treated cord after heat treatment. This excessively increases and the cross section of the discharged yarn becomes uneven, resulting in many filament cuts during stretching, resulting in poor stretching workability.

In addition, optionally, an antimony compound, preferably antimony trioxide, may be added as a polymerization catalyst during the condensation polymerization reaction so that the remaining 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 slowed and the polymerization efficiency decreases, and when the residual amount exceeds 300 ppm, more than necessary antimony metal acts as a foreign material, and the spinning and drawing workability may be deteriorated.

The polyethylene terephthalate chip as described above is melted and extruded while passing through a nozzle to produce a discharge yarn.

Thereafter, the discharged sand is rapidly cooled and solidified by passing through the cooling zone. At this time, if necessary, a heating device of a certain length is installed in the distance from directly under the nozzle to the starting point of the cooling zone, that is, in the length (L) section of the hood.

This zone is referred to as a 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 are performed according to the method of blowing cooling air. ) Method may be applied, but is not limited thereto.

At this time, the temperature of the cooling air injected for rapid cooling in the cooling zone is adjusted to 20 to 50°C. The rapid cooling using such a rapid temperature difference between the hood and the cooling zone is to increase the solidification point and spinning tension of the spun polymer to increase the orientation of the undrawn yarn and the formation of a linking chain between the crystal and the crystal.

Meanwhile, in the present invention, the number of holes of the nozzle is set so that the single yarn fineness (DPF) is 3.0 to 4.5, and the hole diameter of the nozzle is 0.8 to 1.6 mm. Specifically, the single yarn fineness is preferably 3.0 to 4.1, and the hole diameter of the nozzle is preferably 0.8 to 1.4 mm, more preferably 1.0 to 1.4 mm. If the single yarn fineness is less than 3.0, the non-uniformity of the undrawn yarn is severe during spinning, causing a lot of filament cuts, resulting in poor drawing workability and yarn appearance. A problem of lowering stability occurs. In addition, when the nozzle hole diameter is less than 0.8mm, as the spin-draft is lowered, the degree of orientation of the undrawn yarn is lowered, thereby increasing the load in the stretching section and lowering the orientation of the final drawn yarn, making it difficult to express high strength. In addition, when the nozzle hole diameter exceeds 1.6 mm, the distance between the holes becomes too narrow, resulting in a decrease in cooling efficiency and a decrease in drawing workability due to cooling unevenness.

Thereafter, the discharged yarn, which has been solidified while passing through the cooling zone, can be oiled to the discharged yarn by reducing the coefficient of friction between the single yarns and applying an emulsion having excellent stretchability and thermal efficiency.

The undrawn yarn is formed by spinning the oiled discharged yarn.

Thereafter, the undrawn yarn is passed through a stretching godet roller and multi-stage stretching is performed to manufacture a yarn.

In the present invention, the stretching proceeds using a facility in which the stretching godet roller is applied in six stages.

The yarn that has passed through the first stretched godet roller is stretched while passing through a series of stretched godet rollers using a spin draw method to form a yarn.

In the present invention, in the drawing godet roller 1 (GR1), the speed is set in the range of 3500 to 4200 m/min, preferably 3600 to 4150 m/min, more preferably 3800 to 4150 m/min, and drawing godet rollers 4 and 5 ( GR4 and GR5) is characterized by winding at 6500 to 6900 m/min, preferably 6700 to 6900 m/min. Here, it is difficult to obtain the desired physical properties of the present invention if the values of the upper and lower limits are deviated.

In addition, the temperature of the stretching godet rollers 4 (GR4) and 5 (GR5) in the stretching step is preferably 240 to 250 °C. If the temperature of the GR4 and GR5 is less than 240° C., the crystallinity and the size of the crystal cannot be increased in the stretching process, and thus the strength and thermal stability of the yarn cannot be expressed, resulting in a decrease in shape stability at a high temperature, thereby increasing the shrinkage rate. When the temperature of GR5 exceeds 250°C, there is a problem in that the strength of the yarn may be deteriorated due to non-uniform microstructure of the yarn such as crystal decomposition because it is too close to the melting point.

In addition, the total draw ratio of the yarn wound as described above is preferably 1.8 or less, preferably 1.76 or less, more preferably 1.70 or less. When the total draw ratio exceeds 1.8, crystallization of the oriented amorphous portion increases, resulting in a decrease in drawing workability, poor appearance, and a high shrinkage due to a high draw ratio. In addition, the molecular chain of the amorphous part in the microstructure of the yarn is broken, resulting in a decrease in the uniformity of the molecular chain, which is not preferable because the strength may be reduced.

The polyethylene terephthalate (PET) yarn prepared as described above has a strength of 7.2 g/d or more, preferably 7.3 g/d or more, and a shrinkage rate of 3.0% or less under the condition of applying a 0.05 g/d load for 2 minutes at 177°C. , Preferably 2.6% or less, more preferably 2.4% or less, and the number of fluffs generated per 5000 m is 3 or less, preferably 2 or less, thus satisfying the physical properties of high strength and low shrinkage at the same time. I can.

After the PET yarn is manufactured as described above, the PET dip cord is manufactured through twisting, weaving, and dipping processes, and the resulting PET dip cord is applied to the carcass layer or the belt reinforcement layer, so that the radial air blowing with excellent high heat resistance It is also possible to provide tires.

Hereinafter, the twisting, weaving, and dipping processes of the present invention will be described in more detail.

When explaining the twisting process of the present invention in more detail, the polyetherene terephthalate yarn produced by the above manufacturing method is twisted with a direct twisting machine in which false twisting and plying are performed simultaneously, and the'raw cord ( Raw Cord)'. Raw cords are manufactured by applying a ply twist to the polyetherene terephthalate yarn for tire cords, then applying a cable twist, and kneading them.In general, the upper and lower edges are made to have the same number of threads or different threads as needed. do.

An important result of the present invention is that physical properties such as strength, elongation, and fatigue resistance of the cord change according to the level of twist (number of years) imparted to the polyetherene terephthalate yarn. In general, when the twist is high, the strength decreases, and the mid-body and ambition tend to increase. Fatigue resistance tends to improve as the twist increases. The softness of the polyetherene terephthalate tire cord prepared in the present invention was manufactured at 300/300 TPM to 500/500 TPM at the same time as the upper/lower edges, but giving the upper and lower edges to the same value means that the manufactured tire cord rotates or It is to maximize the expression of physical properties by making it easy to maintain a straight line without showing twisting. At this time, if it is less than 300/300 TPM, it is easy to reduce the fatigue resistance due to the decrease in the cutting of the raw cord, and if it exceeds 500/500 TPM, it is not suitable for tire cord because of the strong decrease.

In the present invention, there are cases in which the upper/lower edges are selectively given different number of years, and the upper/lower edges were adjusted to 350 TPM to 450 TPM, and the lower edge was adjusted to 300 TPM to 450 TPM to produce a raw cord with different upper/lower edges. The reason why the upper/lower training is different is because the training cost decreases as the number of training decreases within the range of the optimum physical properties of the raw cord, which is economically profitable. As a constant for evaluating such twist, a "twist constant" has been proposed.

Manufactured'Raw Cord' is for tire cords with a resin layer attached to the'Raw Cord' surface by weaving using a weaving machine, dipping the obtained fabric in a dipping solution, and curing it. We manufacture'Dip Cord'.

That is, a raw cord woven into a fabric and applied tension is immersed in a dipping solution, and then the fabric is cured to produce a'dip cord' for tire cord with a resin layer attached to the surface of the raw cord.

In the above process, dipping refers to impregnating a resin layer called RFL (Resorcinol Formaline Latex) on the surface of the fiber. This is done in order to improve the disadvantages of the tire cord fiber, which has poor adhesiveness with the original rubber.

In the present invention, the adhesive solution for bonding the cord and the rubber may be prepared using the following method.

<Method of manufacturing adhesive solution>

29.4 wt% resorcinol 45.6 parts by weight;

255.5 parts by weight of distilled water;

20 parts by weight of 37% formalin; And

3.8 parts by weight of 10 wt% sodium hydroxide;

After preparing a solution containing and reacting with stirring at 25° C. for 5 hours, the following components are added.

40wt% VP-latex 300 parts by weight;

129 parts by weight of distilled water;

After adding 23.8 parts by weight of 28% aqueous ammonia, it is aged at 25° C. for 20 hours to maintain a solid content of 19.05%.

After drying the cord, an adhesive solution is applied. In order to control the adhesion amount of the adhesive solution, 0 to 4% of stretch is required, and preferably 1 to 2% of stretch may be achieved. If the elongation ratio is too high, the amount of adhesion of the adhesive liquid can be adjusted, but the excision is reduced, resulting in reduced fatigue resistance.

The adhesion amount is preferably 1.5 to 3.5% based on the weight of the fiber based on the solid content. After passing through the adhesive solution, the dip cord is dried at 120 to 170°C. The drying time may be 180 seconds to 220 seconds, and the dip cord during the drying process may be stretched to about 1 to 2%. When the elongation ratio is low, the center and cut length of the cord increase, which may exhibit physical properties that are difficult to apply as a tire cord. On the other hand, if the elongation ratio exceeds 3%, the central body level is appropriate, but the body body is too small, which may reduce fatigue resistance.

After drying, heat treatment is performed at a temperature range of 130 to 240°C. During heat treatment, the elongation ratio is maintained between -2 and 2.0%, and the heat treatment time is appropriate between 50 seconds and 90 seconds. If heat treatment is performed for less than 50 seconds, the reaction time of the adhesive solution is insufficient, resulting in a decrease in adhesive strength, and if the heat treatment is performed for 90 seconds or more, the hardness of the adhesive solution increases and the fatigue resistance of the cord may decrease. .

The polyethylene terephthalate dip cord prepared according to the above method has a fineness of 1000 to 6000 denier, and the strength of the 1500d/2 dip cord is 6.3 g/d or more, preferably 6.5 g/d or more, and 2 at 177°C. The shrinkage rate under the condition of applying a load of 0.05 g/d for a minute is 2.0% or less, preferably 1.9% or less, and more preferably 1.8% or less, which can be advantageously used as a tire cord satisfying high strength and shrinkage resistance.

The present invention mainly describes the case of dipping using a two-bath dipping machine, as shown in FIG. 2, but those of ordinary skill in the art perform heat treatment under the same conditions using a one-bath dipping machine. It would also be possible.

Hereinafter, the present invention will be described in detail by examples. However, these examples are intended to specifically illustrate the present invention, and the scope of the present invention is not limited to these examples.

The evaluation of physical properties of Examples and Comparative Examples was measured or evaluated as follows.

1) Intrinsic viscosity (I.V.)

Dissolve 0.1g of a sample for 90 minutes in a reagent (90℃) mixed with phenol and 1,1,2,2-tetrachloroethanol 6:4 (weight ratio) for 90 minutes, then transfer it to an Ubbelohde viscometer and put it in a 30℃ thermostat Hold for 10 minutes, and calculate the number of seconds to fall of the solution using a viscometer and an aspirator. The number of falling seconds of the solvent is also calculated using the following equation, which is obtained by the same method as above. Value and I.V. The value was calculated.

R.V. = Number of seconds to fall of sample/number of seconds to fall of solvent

I.V. = 1/4 ×(R.V.-1)/concentration + 3/4 ×(In R.V./concentration)

2) Strength of yarn and deep cord (kgf)

The sample length was measured at 250 mm and a tensile speed of 300 m/min using an Instron's low-speed elongation type tensile tester.

3) Strength of yarn and dip cord (tensile strength) (g/d)

The yarn was left in a constant temperature and humidity room at a standard condition, that is, a temperature of 25°C and a relative humidity of 65% for 24 hours, and then measured by a tensile tester according to ASTM D-885.

4) Measurement of cutting length (%) at the breaking strength of yarn

According to the ASTM D885 standard, cutting elongation at the breaking strength of PET yarn was measured using a universal tensile tester.

5) Measurement of shrinkage (%, Shrinkage) of yarn and dip cord

After leaving for 24 hours at 25℃65% RH, the ratio of the length (L0) measured at a static load of 0.05g/d and the length after treatment at 177℃ at a static load of 0.05g/d for 2 minutes (L1) is used. Then, the shrinkage rate was measured. The shrinkage rate (S) can be expressed as follows.

S(%) = [(L0 ―L1)/L0] × 100

6) fluff

The number of wool found when 5km long yarn was fired was measured.

Examples 1-6

Polyethylene terephthalate polymers containing 90 mol% or more of terephthalate units and having an intrinsic viscosity measured with phenol/tetrachloroethane as shown in Table 1 were used with Radial-in Flow (RIF) Quenching equipment, and spinning as shown in Table 1 below. A final drawn yarn (yarn) was prepared while spinning under conditions. The strength, strength, cutting, shrinkage, and number of fluffs of the thus prepared yarn were measured and shown in Table 1.

A lower edge of 200TPM was added to the PET yarn 1500D prepared as described above, and then 200TPM of the upper edge was added again, and then combined to prepare a raw cord. The obtained raw cord was dried at 160° C. for 130 seconds by a two-bath dipping method, and then passed through an adhesive solution prepared by the following method while applying a tension of 5 kgf to give an adhesive solution. When drying, 2% of stretch was applied to control so as not to cause unevenness of the raw cord due to heat shrinkage.

29.4 wt% resorcinol 45.6 parts by weight; 255.5 parts by weight of distilled water; 20 parts by weight of 37% formalin; And after preparing a solution containing 3.8 parts by weight of 10 wt% sodium hydroxide, it was reacted with stirring at 25° C. for 5 hours, and the following components were added:

40wt% VP-latex 300 parts by weight, distilled water 129 parts by weight, 28% ammonia water, 23.8 parts by weight

After the ingredients were added, they were aged at 25° C. for 20 hours to maintain a solid content of 19.05%.

The adhesive solution was applied and dried at 160° C. for 2 minutes, followed by dipping heat treatment in two baths at 240° C. for 60 seconds to complete the adhesive treatment. The strength, strength, and shrinkage properties of the dip cord thus prepared were evaluated and shown in Table 1.

Comparative Examples 1-6

Yarn and dip cord were prepared in the same manner as in Examples 1 to 6, except for spinning under the intrinsic viscosity and spinning conditions of Table 2. Table 2 shows the physical properties of PET yarns and dip cords prepared by the manufacturing method of Comparative Examples 1 to 6.

The physical properties of the yarns and dip cords prepared in Examples 1 to 6 and Comparative Examples 1 to 6, respectively, were evaluated in the following manner, and the results are shown in Tables 1 and 2 below.

Item Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Polymer Intrinsic viscosity dl/g 1.055 1.065 1.085 1.095 1.085 1.070 Nozzle Hole diameter mm 0.8 0.8 1.0 1.2 1.2 1.4 Number of holes dog 515 440 440 384 440 515 DPF - 3.0 3.6 3.6 4.1 3.6 3.0 Radiation condition GR1 speed m/min 3600 3800 4000 4100 4000 4150 GR4 speed m/min 6500 6700 6700 6800 6800 6900 GR5 speed m/min 6500 6700 6700 6800 6800 6900 GR4 temperature ℃ 240 250 250 245 240 250 GR5 temperature ℃ 240 250 250 245 240 250 Draw ratio - 1.80 1.76 1.67 1.65 1.70 1.66 Yarn properties Denier D 1578 1582 1579 1586 1576 1580 strong Kg 11.6 11.8 11.6 11.7 11.9 11.7 burglar g/d 7.3 7.4 7.3 7.3 7.4 7.3 Desperate % 13.8 14.1 14.4 13.9 13.6 14.3 Shrinkage rate % 2.6 2.4 2.3 2.4 2.3 2.4 Fluff Dog/5km 2 2 One 0 2 One Code properties strong Kg 21.7 21.9 21.6 21.9 22.1 21.7 burglar g/d 6.6 6.6 6.5 6.6 6.7 6.6 Shrinkage rate % 1.9 1.8 1.7 1.8 1.7 1.7

Item Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Polymer Intrinsic viscosity dl/g 0.980 1.020 1.035 1.045 1.035 1.055 Nozzle Hole diameter mm 0.6 0.7 0.8 0.8 1.0 1.0 Number of holes dog 515 440 440 384 440 328 DPF - 3.0 3.6 3.6 4.1 3.6 4.8 Radiation condition GR1 speed m/min 3550 4000 3550 4000 4000 4000 GR4 speed m/min 6400 6700 6400 6700 6700 6700 GR5 speed m/min 6400 6700 6400 6700 6700 6700 GR4 temperature ℃ 220 230 240 230 230 250 GR5 temperature ℃ 220 230 240 230 230 250 Draw ratio - 1.80 1.67 1.80 1.67 1.67 1.67 Yarn properties Denier D 1577 1580 1579 1583 1575 1585 strong Kg 11.7 11.3 11.4 11.4 11.7 11.1 burglar g/d 7.3 7.1 7.2 7.2 7.3 6.9 Desperate % 12.8 13.1 13.3 13.4 13.0 13.8 Shrinkage rate % 3.1 3.3 3.1 3.0 3.5 2.9 Fluff Dog/5km 4 7 8 13 4 12 Code properties strong Kg 21.5 20.9 21.1 21.2 21.6 20.7 burglar g/d 6.5 6.3 6.3 6.3 6.5 6.2 Shrinkage rate % 2.2 2.3 2.3 2.2 2.4 2.0

As can be seen by comparing Tables 1 and 2, the yarns and dip cords produced in Examples 1 to 6 of the present invention are within the same strength range as compared to the yarns and dip cords produced by Comparative Examples 1 to 6 It could be confirmed that it shows a better shrinkage rate (lower shrinkage rate).

Through this, in the present invention, a differentiated spinning technology that exhibits high strength while having a low shrinkage rate was invented, and through this, it can be expected that the high strength low shrinkage PET yarn and tire cord can improve driving stability and ride comfort.

1: Extruder 2: Gear pump
3: heating device 4: cooling zone
5: emulsion supply device 6: stretch godet roller GR1
7: stretching godet roller GR2 8: stretching godet roller GR3
9: stretching godet roller GR4 10: stretching godet roller GR5
11: drawing godet roller GR6 12: take-up roller
13: Bobbin 14: 1st dip
15: 1st drying zone 16: 1st heat set zone
17: 2nd dip 18: 2nd drying zone
19: 2nd heat set zone 20: winder

Claims (5)

Melting polyethylene terephthalate chips having an intrinsic viscosity of 1.05 to 1.10 dL/g and spinning them through a nozzle to prepare undrawn yarn; And
Including; and the steps of drawing the undrawn yarn with a facility to which six stages of draw godet rollers are applied, and drawing and winding so that the total draw ratio is 1.8 or less to produce polyethylene terephthalate yarn; and
The number of holes of the nozzle is set so that the single yarn fineness (DPF) is 3.0 to 4.5, and the hole diameter of the nozzle is 0.8 to 1.6 mm,
The temperature at the 4th and 5th stages of the stretching godet roller is 240 to 250°C,
High strength low shrinkage ( HMLS) Method for producing polyethylene terephthalate yarn. delete The method of claim 1,
The polyethylene terephthalate yarn has a strength of 7.2 g/d or more, a shrinkage rate of 2.6% or less under a condition of applying a 0.05 g/d load for 2 minutes at 177°C, and the number of fluffs generated per 5000 m is 3 or less. High strength low shrinkage (HMLS) polyethylene terephthalate yarn manufacturing method. High-strength low-shrink (HMLS) polyethylene terephthalate yarn manufactured by the manufacturing method of claim 1. A tire cord comprising the high-strength low-shrink polyethylene terephthalate yarn of claim 4,
A tire cord, characterized in that the strength of the 1500d/2 dip cord is 6.3g/d or more, and the shrinkage rate under the condition of applying a 0.05g/d load for 2 minutes at 177°C is 2.0% or less.

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