KR950001652B1 - Method of preparing poly(ethyleneterephthalate) filament yarn - Google Patents

Abstract

The polyester, which is useful for tire cord by the high modulus of elasticity and low shrinkage properties, was manufactured with the polyester which comprised polyethylene terephthalate having more than 90 mol.% repeating unit of molecular chain and the intrinsic viscosity of it was above 0.75. The polyester polymer was spun at the spinning speed 2,500-4,000m/min to obtain the high oriented non-extension yarn and then the yarn was extened by the method of warpdraw.

Description

Manufacturing method of poly (ethylene terephthalate) filament yarn

1 is a schematic view of a transverse stretching machine installation state of the present invention.

* Explanation of symbols for main parts of the drawings

1: 1st go roller 2: 2nd go roller

3: first oven 4: third gourd roller

5: 2nd oven 6: 4th gourd roller

The present invention relates to a method for producing a low shrinkage poly (ethylene terephthalate) filament yarn by a lateral stretching method.

Polyester fiber used as a tire cord sprayer for automobiles has the advantage of being cheaper than rayon fibers, but has a high shrinkage rate at high temperatures (70-150 ° C., the temperature of tires when driving a car), making it difficult in the manufacturing process of tires. There are many disadvantages in that it deteriorates the shape stability of the tire when driving.

Due to these drawbacks, rayon fibers with high thermal stability at high temperatures are still used in automobile tires for high-speed driving.

However, the tire cord market share of polyester is still relatively high, and if only the above-mentioned disadvantages are reinforced, it will be used as the most suitable material for passenger car tire cords.

Various high modulus, low shrink poly (ethylene terephthalate) filament yarns are known and are commercially used in a variety of processes. These poly (ethylene terephthalate) filament yarns are useful for tire cords due to their high modulus and low shrinkage.

Existing high elastic modulus, low shrinkage polyester filament yarn manufacturing method has excellent morphological stability at high temperature by densifying the crystal structure formed during spinning using high-speed spinning (Japanese Patent Publication No. 61-245330, 61-289115).

When manufacturing the polyester filament yarn by high-speed spinning has a disadvantage that the noise pollution of the winding due to the high spinning speed is serious and the operability is considerably reduced. In addition, as far as is known, the dry heat shrinkage rate (150 ° C. × 30 min) that can be pursued by high-speed spinning is about 1 to 3 or 4%, which is considerably higher than rayon fiber (150 ° C. × 30 min, 1% or less).

In addition, as the spinning speed increases, the design of the spinning and stretching device becomes considerably more difficult and expensive.

To compensate for this drawback, when polyester is stretched in the direction of semi-stretched yarn (POY: Partially Oriebtde Yarn) and stretched by transverse stretching method, the dry heat shrinkage rate is 1.0% or less, which is much lower than that of continuous stretching by spinning at high speed. The industrial polyester yarn of (150 degreeCx30min) can be manufactured.

The present invention solves the problems of the conventional polyester filament yarn manufacturing method as described above, the polyester filament yarn manufacturing method of the present invention has two methods as follows.

Firstly, it is made of poly (ethylene terephthalate) of 90 mol% or more of the total repeating units of the molecular chain, and a polyester polymer having an intrinsic viscosity ([η]) of 0.75 or more is used without a heating hood. After producing POY by spinning at a spinning speed of 2,500 ~ 4,000mpm in the state, it is stretched by warpdraw method and has a strength of 6.5g / d or more and a polythermal shrinkage of 1.0% or less (150 ℃ × 30min). Ester filament yarn is prepared. At this time, the stretching uses the lateral stretching machine as shown in FIG. 1 and the stretching conditions are as follows.

Iii) The present invention is characterized in that a heating tube is not used in the manufacture of POY. In general, the use of a heating tub in the manufacture of industrial companies, but the present invention, in order to increase the orientation of the POY company does not use a heating tub.

The higher the orientation of POY yarn, the more advantageous in terms of strength and shape stability after stretching.

Ii) In the present invention, a polymer having an intrinsic viscosity of 0.75 or more is used.

When a polymer having an intrinsic viscosity of less than 0.75 is used in terms of morphological stability, it is not preferable because of its low strength and toughness.

Iii) In the present invention, the spinning speed should be 2,500 to 4,000mom when the yarn is partially orientated.

When the spinning speed is less than 2,500mpm, it is advantageous in terms of strength, but it is disadvantageous in terms of form stability, and when it is larger than 4,000mpm, the strength is severely lowered after stretching, which is not preferable for high strength industrial yarns.

Iii) In the present invention, the stretching should be performed in a transverse stretching manner.

It is difficult to manufacture a low shrinkage polyester filament yarn having a dry heat shrinkage (150 ° C. × 30 min) of 1% or less by a general drawing method. That is, in the conventional drawing method, since the amount of heat to be heated in the relaxation step is not sufficient, it is difficult to produce a low shrinkage polyester filament yarn having a dry heat shrinkage (150 ° C. × 30 min) of 1% or less.

Iii) In the present invention, the first draw ratio should be 2-3 times higher than the second draw ratio.

When POY yarn is drawn sufficiently in one step drawing, the filament yarn is well oriented so that when crystallization proceeds in the two step drawing and heat treatment process, the number of tie chains between the crystals increases, which is sufficient for industrial use.

I) In the present invention, the stretching temperature should be as follows.

1st stage drawing temperature: 80 ℃ ~ 120 ℃

2-stage stretching temperature: 100 ℃ ~ 160 ℃

If the one-stage stretching temperature is less than 80 ° C, cutting occurs during the one-stage stretching of the POY. In other words, if the fluidity of POY is insufficient, the stretching tension increases and ultimately, cutting occurs.

In addition, when the temperature of the first high roller is greater than 120 ° C., the crystallization proceeds rapidly during the first stage stretching, so that the second stage stretching is impossible.

If the two-stage stretching temperature is less than 100 ° C., the strength decreases severely, which is not preferable. If the two-stage stretching temperature is less than 160 ° C., crystallization proceeds rapidly during two-stage stretching to cause cutting in the first oven.

In the present invention, when the polyester filament yarn for tire cord or tarpaulin can be produced by spinning polyester in the POY state and stretched in the transverse stretching method, the dry heat shrinkage is 1.0% or less (150 ° C. × 30 min) and the strength is high. High strength industrial polyester yarns of 6.5 g / d or more can be produced.

Secondly, poly (ethylene terephthalate) containing 90 mol% or more of the total repeating units of the molecular chain, and a thermoplastic polymer having the following structural formula excellent in thermal stability and excellent mechanical properties in a polyester polymer having an intrinsic viscosity of 0.75 or more. Is added to 1 to 8wt% spinning spinning POY at a spinning speed of 2,500 to 4,000mpm, and the POY yarn is stretched and heat-treated in multiple stages under the same conditions as the first method by the lateral stretching method to produce a polyester filament yarn.

[Formula 1]

I) In the present invention, a polymer having an intrinsic viscosity of 0.75 or more is used.

When the polymer having an intrinsic viscosity of less than 0.75 is used, it is good in terms of morphological stability, but it is not preferable because of its low strength and toughness.

Ii) In the present invention, it should be added to the polyester polymer in order to reduce the shear rate during spinning.

If less than 1% by weight of the liquid crystal polymer is added, the thermotropic liquid crystal polymer in the polyester matrix is not sufficient to improve the orientation of the POY yarn, and even if more than 8% by weight of the thermotropic liquid crystal polymer is added, the orientation of the POY yarn is no longer Since it does not increase, there is no need to put a lot of relatively expensive thermotropic liquid crystal polymer.

Iii) In the present invention, the filament yarn should be manufactured by stretching and heat-treating at a high speed spinning speed of 2,500 ~ 4,000mpm.

If the spinning speed is less than 2,500mpm, the orientation of the POY yarn formed during spinning is not sufficient, and if the spinning speed is greater than 4,000mpm, the stretching process is impossible due to plural crystallization during spinning.

In the present invention, POY yarn having a higher orientation than POY yarn produced when using pure polyester filament yarn is produced by mixing and spinning a small amount of thermotropic liquid crystal polymer as a shoe manufacturing method for a tire cord polyester filament yarn. Characterized in making.

In addition, the conventional method can not produce a polyester in which the dry heat shrinkage is close to the rayon fiber, but in the present invention, since the shape stability is the same as that of the rayon fiber, the polyester filament yarn for tire cords can be manufactured. It is most suitable as a method of manufacturing tire cords of better physical properties.

[Examples 1-3 and Comparative Examples 1-3]

The poly (ethylene terephthalate) polymer was extruded at spin temperature of 295 ° C. with spinneret having 200 detention holes having a diameter of 0.5 mm and L / D 2.0.

It was set as 21 degreeC cooling wind atmosphere, without the heating hood installed in the lower part of detention.

POY yarns were spun at 2,500 to 4,000mpm for two-stage stretching and heat treatment in a transverse stretching manner, and the spinning speeds, stretching ratios, and heat treatment temperatures were specified in Table 1.

The discharge amount of the final stretched yarn was adjusted to be 1,000 denier.

[Examples 4-6, Comparative Examples 4-6]

A small amount of thermotropic frame polymer was added to the poly (ethylene terephthalate) polymer to extrude the spinneret having 250 detention holes having a diameter of 0.3 mm and 2.0 of L / D2.0 with varying spinning temperatures. Under the prison, a heating tube having a length of 300 mm and a temperature of 320 ° C. was installed, and under the heating tube was a 30 ° C. cooling air atmosphere.

Yarn was spun at 2,500 ~ 4,000mpm to prepare POY yarn, stretched and heat treated in multiple stages, and the amount of the thermotropic liquid crystal polymer and the spinning temperature are specified in <Table 1>.

The discharge amount was adjusted so that the final yarn had a fineness of 1,000 denier.

As shown in Table 1, in the present invention, the POY yarn is stretched in a lateral stretching manner, and thus, as in Examples 1 and 2, the strength is 7.0 g / d or more and the dry heat shrinkage (150 ° C. × 30 min) is 1% or less. Low shrink polyester stretched yarn can be produced.

Comparing Example 1 and Vegyo 3 shows that even when spinning the POY yarn using a polyester polymer of the same molecular weight, physical properties of the stretched yarn is significantly reduced according to the spinning speed. That is, when the POY yarn is manufactured at a spinning speed of 5,000 mpm as in Comparative Example 1, the strength of the stretched yarn is significantly reduced, which is not preferable as an industrial yarn.

Also in Comparative Example 2, when the molecular weight of the polymer is lowered to 0.75 or less, a significant decrease in strength is caused.

In Comparative Example 1, when the one-stage stretching temperature is too high (150 ° C) than the glass transition temperature of the polyester (150 ° C), crystallization proceeds before the POY yarn is fully oriented in one-stage stretching, so the crystals generated at this time are not very irregular. Rather, it acts as a crystal when drawn in a two-stage stretching process, causing cuts.

Claims (2)

The total repeating unit of the molecular chain is made of polyethylene terephthalate of 90 mol% or more, and a polyester polymer having an intrinsic viscosity of 0.75 or more is spun at a spinning speed of 2,500 to 4,000 m / min to prepare a highly oriented unstretched yarn, and then transversely stretched it. It is produced by heat treatment after stretching at a one-stage stretching temperature of 8 to 120 ° C, a stretching ratio of 1.5 to 2.0 times, a two-stage stretching temperature of 100 to 160 ° C, and a stretching ratio of 1.1 to 1.5 times by a wrap draw method. (Ethylene terephthalate) A method for producing a filament yarn. The polyester polymer having an intrinsic viscosity of 0.75 or more, wherein all the repeating units of the molecular chain are 90 mol% or more, and one or two or more of the following federalized liquid crystal polymers. 1-8 weight% of these are contained, The manufacturing method of the poly (ethylene terephthalate) filament characterized by the above-mentioned. [Formula 1]