KR20140089157A - Process for preparing polyester multifilament having excellent strength and chemical resistance for tire cord - Google Patents

Abstract

In order to solve the above problems, the present invention relates to a method for preparing a polyester multifilament for a tire cord, wherein the temperature gradation of quenching air is provided to decrease the difference in the degree of orientation between an inside and an outside of the filament and increase the degree of orientation of an external surface layer, thereby improving heat resistance and chemical resistance of a dip cord. In preparing a polyester multifilament having excellent dimensional stability, heat resistance, and chemical resistance for a tire cord, provided is a method for preparing a polyester multifilament for a tire cord, comprising the steps of: extrusion-melting a solid-phase polymerization polyester chip containing an ethylene terephthalate unit at a temperature of 290-300°C to prepare a spin-out yarn; delay-cooling the spin-out yarn at a temperature of 60-100°C; quenching the cool air temperature to 20-25°C immediately after hot air, followed by solidification; winding a yarn at a spinning rate at which the birefringence and density of the undrawn yarn are controlled; and multi-stage drawing the wound yarn. According to the present invention, a high-strength, low-shrinkage polyester multifilament can be obtained by decreasing the difference in the degree of orientation between the inside and the outside of the filament and increasing the degree of orientation of the external surface layer, and can improve chemical resistance stability and heat resistance due to the increase in the degree of orientation in the surface, thereby being applicable as a tire cord.

Description

Technical Field [0001] The present invention relates to a polyester multifilament having excellent strength and chemical resistance for a tire cord,

The present invention relates to a process for producing a polyester multifilament yarn for a tire cord, and more particularly, to a process for producing polyester multifilament yarn for a tire cord by adjusting a temperature gradient of cooling air in order to improve heat resistant strength and chemical resistance of a polyester multifilament yarn, To a method of producing a polyester multifilament yarn having excellent physical properties which can be used as a material for a tire cord.

High strength polyester fibers are widely used in industrial applications including tire cord for rubber reinforcement, seat belts, conveyor belts, V-belts and hoses, and particularly for application as a fiber reinforcing material for tires In the case of converting into a treated cord by latex treatment and heat treatment, more excellent form stability and strength are required.

In the high intrinsic viscosity (IV), the spinning speed is fast if the spinning temperature of the polymerized material is the same and the strength is the same within the high spinning speed range of the intrinsic viscosity (IV) 0.9-1.2 to 2,000-3,200 m / min. It is well known in the art of industrial polyester manufacture that the dimensional stability of the treated cord and the tendency of the strength utilization of the yarn to further improve.

Theoretically, theoretically, when manufacturing industrial polyester yarns, it is necessary to increase the radiation tension to increase the formation of the tie chain which connects the orientation of the undrawn yarn and the crystal to the crystal, And the uniformity of the degree of fineness and the degree of orientation between the filaments of the non-drawn filaments should be further improved so as to enable high-magnification drawing with such high-orientation non-drawn filament yarns in order to obtain higher-

U.S. Patent No. 4,101,525 and U.S. Patent No. 4,491,657 disclose industrial polyester multifilament yarns having high initial modulus and low shrinkage. However, the yarns disclosed in the above patents have a disadvantage in that when they are converted into processed codes, their strength decreases and they do not have the necessary characteristics of the tire cord.

In order to solve such a problem, US Pat. No. 4,690,866 discloses a method of increasing the strength of a multifilament polyester fiber by using a polyester chip having a high intrinsic viscosity (I.V.) of 1.2 or more. When the viscosity of the chip is increased, the spinning strength is increased to increase the formation of the tie chain which connects the orientation of the undrawn yarn and the crystal to the crystal so as to exhibit excellent strength when converted to the treated cord.

However, the polyester having a high intrinsic viscosity used in the above method has a problem in that when the intrinsic viscosity difference between the surface and the center portion in the solid phase polymerization is deeply melt-radiated, the spinnability is lowered due to the unevenness in viscosity and the filament cut occurs, But also pyrolysis and hydrolysis are generated due to melt-spinning at a high temperature. Thus, there is a problem in that the actually spun fibers do not have a viscosity as high as that of a chip.

In order to solve the above-mentioned problems, it is an object of the present invention to provide a temperature gradient of cooling air (quenching air) to reduce the difference in the degree of orientation between the inside and the outside of the filament and increase the degree of orientation of the external surface layer, And to provide a method for producing a polyester multifilament yarn for a tire cord which improves chemical resistance.

According to a preferred embodiment of the present invention, in producing a polyester multifilament yarn for tire cord excellent in dimensional stability, heat resistance, and chemical resistance, a solid phase-polymerized polyester chip containing ethylene terephthalate units is melt- Extruding and melting at a temperature to produce a discharged yarn; Retarding the discharged yarn by delaying the hot air temperature to 60 to 100 ° C; Rapid cooling and solidifying the Coll Air temperature immediately after hot from 20 to 25 ° C; Winding the yarn at a spinning speed to adjust the birefringence and density of the undrawn yarn; And a step of stretching the wound yarn in a multi-stage fashion. The present invention also provides a method for producing a polyester multifilament yarn for a tire cord.

According to another preferred embodiment of the present invention, it is characterized in that the length of the hot air portion and the cool air portion is in the range of 1: 1 to 7: 3.

According to another preferred embodiment of the present invention, the outlet length of the quenching air is 30 to 60 cm, and the cooling air is injected at a rate of 0.3 to 0.8 m / s.

The present invention having such a constitution as described above can reduce the difference in the degree of orientation between the inside and the outside of the filament and increase the degree of orientation of the outer surface layer to thereby obtain a polyester multifilament yarn of high strength and low shrinkage, The chemical resistance and heat resistance of the tire can be improved and the tire can be applied to a tire cord.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a spinning device used in a process for producing a polyester multifilament yarn for a tire cord according to the present invention.
Fig. 2 shows a part of a spinning device used in a process for producing a polyester multifilament yarn for a tire cord according to the present invention.
FIG. 3 shows the difference in orientation between the inside and the outside of the multifilament yarn according to the temperature gradient in the production process of the polyester multifilament yarn for a tire cord according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 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 polyester used as the main material of the tire cord of the present invention may contain a small amount of units derived from ethylene glycol and terephthalenedicarboxylic acid or derivatives thereof and one or more ester-forming components as a copolymer unit.

Examples of other ester forming components that can be copolymerized 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, And dicarboxylic acids such as dicarboxylic acid, bibenzoic acid, adipic acid, sebacic acid, and azelaic acid.

A method for producing a polyester multifilament yarn according to the present invention comprises the steps of extruding and melting a polyester chip having an intrinsic viscosity of 1.0 to 1.2 or more at a temperature of 290 to 300 占 폚 and then lagging and cooling at 80 占 폚, Followed by an evolving step at a spinning speed of 3000 m / min.

The polyester multifilament yarn thus produced has a strength of 8.6 g / d or more, a fineness of 1500 d or more, and a morphological stability index of 6.0 or less, which are excellent in physical properties and processability. At this time, if the shape stability index exceeds 6.0, it is inappropriate for tire cord.

1, a PET chip is melt-spun at a low temperature of 290 to 310 占 폚 through an extruder 1, a gear pump, a nozzle 2 and a heating device 3 to produce a polymer by pyrolysis and hydrolysis Is prevented from being lowered.

The produced melt release yarn is quenched and solidified through a delayed cooling zone and a Cool Air 5 with a hot air 4 and is cooled and cooled as needed in the cooling zone 4 immediately below the nozzle 2 , 5) a short heating device 3 can be installed in the section of the distance L to the starting point, that is, the length L of the hood.

The length (L) section of the hood becomes a delayed cooling zone or heating zone and has a length of 50 to 250 mm and a temperature of 250 to 400 ° C (air contact surface temperature).

The method of blowing cooling air in the cooling zones (4, 5) is radial inflow quenching.

The solidified release yarn passing through the cooling zones (4,5) is oiled to 0.5-1.0% by the emulsion feeder (6) to become undrawn.

The unstretched yarn is drawn by a spin draw method via a stretching roller 7-11 and is obtained as a final stretching yarn 12 on a take-up roller.

In the process of going from the stretching roller 7-11 to the take-up roller 12, an air entanglement process is performed in the interlace nozzle.

Referring to FIG. 2, a polyester chip containing ethylene terephthalate units is extruded and melted, and the resulting yarn is subjected to a quenching and solidifying step, followed by spinning to produce a final yarn. The final yarn is manufactured by a method of retarding the discharged yarn by hot air and a step of cooling the yarn by cooling the yarn.

Referring to FIG. 3, the final yarn produced by applying the temperature gradient reduces the difference in the degree of inner / outer orientation as compared with the polyester filament yarn prepared by the conventional method, and the degree of orientation of the outer surface layer is increased, .

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

≪ Method for measuring physical properties &

1)

Under the conditions of a sample length of 250 mm, a tensile rate of 300 mm / min, and 80 turns / m under standard conditions (20, 65% relative humidity) according to ASTM D 885 using an Instron 5565 (Instron, USA).

2)

The elongation at the load corresponding to 4.5 g / d was measured and the elongation at the load of 2.25 g / d was measured on the SS curve.

3) Shrinkage

The sample was allowed to stand for at least 24 hours under standard conditions of relative humidity of 20, 65%, and the length (L ₀ ) was measured by weighing 0.05 g / d and treated for 30 minutes at 150 under a dry oven And then left for more than 4 hours. Then, a load corresponding to 0.05 g / d was applied to measure the length (L), and the shrinkage ratio was calculated by the following equation (4).

Equation 1

S (%) = (L ₀ - L) / L ₀ 100

4) E-S (dimensional stability)

The dimensional stability of the treated cords is defined by the high modulus at a given shrinkage as the properties related to tire side wall indentation (SWI) and handling and is defined as E2.25 (elongation at 2.25 g / d) + FS Shrinkage) is useful as a measure of dimensional stability for treated cords subjected to different heat treatments, and exhibits better dimensional stability at lower temperatures.

Example 1

The solid phase-polymerized polyester chips containing the ethylene terephthalate unit of the present invention were extruded and melted at a temperature of 290 to 300 DEG C, and the discharged yarn was delayed and cooled at a temperature of 60 DEG C with a hot- Cooled and solidified at a temperature of 20 캜 at a discharge length of 30 cm. This stretched yarn was wound at 2900 m / min to produce a final yarn of 1538 denier.

Example 2

The solid phase-polymerized polyester chips containing the ethylene terephthalate unit of the present invention were extruded and melted at a temperature of 290 to 300 DEG C, and the discharged yarn was delayed and cooled at a temperature of 60 DEG C with a hot- It was prepared by quenching and solidifying at a temperature of 25 캜 with a fisher discharge length of 30 cm. This stretched yarn was wound at 2900 m / min to produce an end yarn of 1539 denier.

Example 3

The solid phase-polymerized polyester chips containing the ethylene terephthalate unit of the present invention were extruded and melted at a temperature of 290 to 300 DEG C, and the discharged yarn was delayed and cooled at a temperature of 80 DEG C with a hot- It was prepared by quenching and solidifying under the condition of 20 cm. The drawn yarn was wound at 3000 m / min to produce an end yarn of 1540 denier.

Example 4

The solid phase-polymerized polyester chips containing the ethylene terephthalate unit of the present invention were extruded and melted at a temperature of 290 to 300 DEG C, and the discharged yarn was delayed and cooled at a temperature of 80 DEG C with a hot- It was prepared by quenching and solidifying at a temperature of 25 캜 at a discharge length of 40 cm. This stretched yarn was wound at 2980 m / min to produce an end yarn of 1542 denier.

Comparative Example 1

The solid phase-polymerized polyester chip containing the ethylene terephthalate unit of the present invention is extruded and melted at a temperature of 290 to 300 ° C, and the discharged yarn is rapidly cooled and solidified at a temperature of 20 ° C, Respectively. This stretched yarn was wound at 2800 m / min to produce a final yarn of 1541 denier.

Comparative Example 2

The solid phase-polymerized polyester chip containing the ethylene terephthalate unit of the present invention is extruded and melted at a temperature of 290 to 300 ° C, and the discharged yarn is rapidly cooled and solidified at a temperature of 25 ° C, Respectively. This stretched yarn was wound at 2850 m / min to produce an end yarn of 1540 denier.

Examples 1 to 4 and Comparative Examples 1 and 2 were conducted under the spinning conditions as shown in Table 1 to prepare final yarns.

division Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Q / A condition Denier / fila 1500d / 384f Hot Air Temperature (℃)
-
- 60 60 80 80 Discharge length
(cm) 30 30 60 60 Air volume (m / s) 0.6 0.6 0.6 0.6 Cool Air Temperature (℃) 20 25 20 25 20 25 Discharge length
(cm) 60 60 30 30 40 40 Air volume (m / s) 0.6 0.6 0.6 0.6 0.6 0.6 Winding speed GR1 (m / min) 2800 2850 2900 2900 3000 2980 GR4 (m / min) 6000 6000 6000 6000 6000 6000 DRt 2.14 2.11 2.07 2.07 2.00 2.01

The properties of the polyester multifilament yarn thus produced were evaluated and are shown in Table 2 below.

division Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Example 4 Hot Air Temperature() - - 60 60 80 80 Discharge length
(cm) 30 30 60 60 Air volume (m / s) 0.6 0.6 0.6 0.6 Cool Air Temperature() 20 25 20 25 20 25 Discharge length
(cm) 60 60 30 30 40 40 Air volume (m / s) 0.6 0.6 0.6 0.6 0.6 0.6 GR1 (m / min) 2800 2850 2900 2900 3000 2980 GR4 (m / min) 6000 6000 6000 6000 6000 6000 Denier 1541 1540 1538 1539 1540 1542 Power (kg) 13.25 13.15 13.38 13.40 13.65 13.64 Strength (g / d) 8.6 8.5 8.7 8.7 8.9 8.8 Chinese (%, @ 6.8kg) 5.0 5.2 5.3 5.4 5.5 5.5 Doubt (%) 10.9 11.4 11.8 12.0 12.4 12.3 Shrinkage (%) 7.4 7.0 6.5 6.4 5.6 5.6 E-S (%) 12.4 12.2 11.8 11.8 11.1 11.1

The physical properties of Comparative Example 1 prepared under the condition of no temperature gradient and Example 3 prepared by applying the temperature gradient are shown in Table 3 below.

Normal Item unit Comparative Example 1 Example 3


Yarn

Denier - 1541 1540 strong kg 13.3 13.7 burglar g / d 8.6 8.9 Chinese %, @ 6.8kg 5.0 5.5 Omission % 10.9 12.4 Contraction ratio %, 150 ° C × 30 ' 7.4 5.6 E-S % 12.4 11.1


D / C Properties


strong kg 23.1 24.4 Chinese %, @ 6.8kg 3.6 4.0 Omission % 11.2 12.7 Contraction ratio %, 150 ° C × 30 ' 2.2 1.5 E-S % 5.8 5.5 Strong Utilization
%, R / C? D / C 97.5 99.2 %, Yarn → D / C 87.2 89.4 Heat treatment condition Stretch: 3.5 / 2.5 / 0.0 / -5.5 = 0.5%, Temp. : 160/242/160/242 D / C heat resistance
Strong after curing kg 17.3 19.3 Strong retention % 74.9 79.1 Endothelium
Endophyrotrophile kg 20.3 21.9 My Fatigue % 87.9 89.8

The physical properties of the polyester multifilament yarn produced by the above method were 89.4% in terms of strength utilization (YarnD / C), 79.1% in strength retention and 89.8% in fatigue strength after vulcanization, respectively, as compared with Comparative Example 1. In addition, the shrinkage ratio of the final dipped cord (D / C) of Example 3 was 1.5%, and the shrinkage ratio of the final dipped cord (D / C) of Comparative Example 1 was more improved than 2.2%. As a result, it was shown that the final product manufactured by applying a delayed cooling process to the hot air and a temperature gradient to cool and cool the product to aero-grade level had a low shrinkage effect.

Although the present invention has been described in detail with reference to the embodiments thereof, it is to be understood by those skilled in the art that the disclosed embodiments are illustrative and that the scope of the present invention is not limited by the modification and the modification of the embodiments. The scope of the present invention is limited only by the following claims.

1: Extruder 2: Nozzle
3: Heating device 4: Delayed cooling zone
5: Rapid cooling zone 6: Emulsion feeder
7, 8, 9, 10, 11: stretching roller 12:

Claims (3)

In producing a polyester multifilament yarn for tire cord excellent in dimensional stability, heat resistance strength and chemical resistance,
Extruding and melting a solid-phase-polymerized polyester chip containing ethylene terephthalate units at a temperature of 290 to 300 캜 to prepare a discharged yarn;
Retarding the discharged yarn by delaying the hot air temperature to 60 to 100 ° C;
Rapidly cooling and solidifying the Coll Air temperature to 20 to 25 ° C immediately after hot air;
Winding the yarn at a spinning speed to adjust the birefringence and density of the undrawn yarn;
And stretching the wound yarn in a multi-stage manner.
The method according to claim 1,
Characterized in that the length of the hot air portion and the cool air portion is in the range of 1: 1 to 7: 3.
The method according to claim 1,
Wherein the outlet length of the quenching air is 30 to 60 cm and the cooling air is injected at a rate of 0.3 to 0.8 m / s.

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