KR20090072469A - High-strength polyethyleneterephthalate fiber and its manufacturing method - Google Patents

Abstract

High intensity polyethylene terephthalate fiber and a manufacturing method thereof are provided to improve intensity of the fiber by enhancing a draw ratio and spinning polyethylene terephthalate chips and a copolymer of low molecular weight. Industrial high intensity polyethylene terephthalate fiber includes the number average molecular weight of 25,000 or greater and average molecular weight of 50,000 or greater. A manufacturing method of industrial high intensity polyethylene terephthalate fiber includes the following steps of: mixing a copolymer of the low molecular weight in a polyethylene terephthalate chip; spinning the copolymer through a spinneret after extruding the copolymer with an extruder(1); producing an undrafted yarn with a hood heater(4,5,6) of which temperature is 350- 450°C; and drafting the undrafted yarn to 6.5 -7.5 times.

Description

High-strength Polyethyleneterephthalate fiber and its manufacturing method

The present invention relates to an industrial high strength polyethylene terephthalate fiber and a method of manufacturing the same, and more specifically, having a high strength characteristics, high modulus, low elongation, low shrinkage characteristics, such as civil geogrid products, industrial webbing belts, etc. It relates to an industrial high strength polyethylene terephthalate fiber and a method for producing the same.

In the conventional method for increasing the strength of polyethylene terephthalate fiber, after melting a high viscosity chip, the molten polymer temperature is raised to 310 ° C. and melted sufficiently, and then filtered through a filter layer of 400 mesh or less, and then the hood length is 280 mm, even after Set the temperature to 340 ° C. and solidify the polymer with rapid cooling air. Subsequently, the unstretched yarn obtained by winding at a low speed roller was stretched directly to a draw ratio 6.0 in one and two stages, and then relaxed and wound. At this time, the orientation degree at the time of unstretching was lowered by low speed winding, the high magnification of stretching was given, and the fiber of high strength was obtained. The physical properties of polyethylene terephthalate, which is widely used in products such as the existing industrial webbing belt manufactured by the above method, the modulus of 60g / d ~ 80g / d, the strength of 9.5g / d or less, elongation 14 ~ 18%.

In order to obtain higher strength by using a conventional spinning technique, when the stretching ratio is increased than the conventional stretching ratio, process problems and quality problems that cause many yarns are generated, resulting in poor post-processability. In addition, attempts have been made to increase the stretchability by adding alcohols to the polyethylene terephthalate chip, but there is a limit in obtaining the high strength yarn by increasing the stretchability by a partial crosslinking reaction. Therefore, it is difficult to obtain high-strength yarn with the existing technology due to the increase of manufacturing cost and the deterioration of product quality.

The present invention, in view of the problems when performing the high stretching of the prior art as described above, after mixing the high viscosity polyethylene terephthalate chip and a small amount of low molecular weight ethylene-based copolymer after melt spinning to increase the draw ratio of high strength The technical task is to enable the production of polyethylene terephthalate industrial yarns with fiber strength of 10.0g / d or more, elongation of 10% or more and shrinkage of 10% or less.

The present invention provides an industrial high strength polyethylene terephthalate fiber comprising a low molecular weight ethylene-based copolymer having the structural formula 1 0.5 to 2.0% by weight.

[Formula 1]

In addition, the low molecular weight ethylene-based copolymer of the present invention preferably has an IC of 5 or less.

In addition, in the present invention, the low molecular weight ethylene-based copolymer of Structural Formula 1 is mixed with a polyethylene terephthalate chip having a number average molecular weight of 25,000 or more and a weight average molecular weight of 50,000 or more after mixing 0.5 to 2.0% by weight of the polyethylene terephthalate chip. After melt extrusion into the expander to spin through the nozzle of the spinneret, after the unheated yarn is produced by the hood heater temperature below the spinning nozzle to 350 to 450 ℃, the unstretched yarn is stretched by 6.5 to 7.5 times It provides a method for producing industrial high strength polyethylene terephthalate fiber.

Industrial Applicability The present invention is useful for industrial ropes, webbing, seat belts, and the like with high strength, low shrinkage, and low wettability by increasing the draw ratio by melting and spinning a polyethylene terephthalate chip and a low molecular weight ethylene-based copolymer. As ester yarns, it can be usefully used for industrial yarns requiring ultra high strength.

Hereinafter, the present invention will be described in more detail.

According to the present invention, in the production of polyethylene terephthalate, a small amount of ethylene-based copolymer penetrates the rigid molecular chain of high viscosity polyethylene terephthalate to increase the fluidity of the chain to achieve high strength. By providing a draw ratio to increase the linearity of the chain to increase the strength and provides a high strength polyethylene terephthalate yarn.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

After mixing a polyethylene terephthalate chip having a number average molecular weight of 25,000 or more and a weight average molecular weight of 50,000 or more and a trace amount of an ethylene copolymer chip, it is melted in an extruder 1, and then passed through a gear pump 2, The filter is filtered with a mesh size of 30 μm. At this time, when the number average molecular weight is less than 25,000, and the weight average molecular weight is less than 50,000, the strength of the yarn decreases rapidly.

The temperature of the hood heaters I (4), II (5), and III (6) is set at 350 to 450 ° C., and rapid cooling air is intaked (7) and exhausted (8) so that the radiated polymer can solidify. At this time, if the heater hood temperature is less than 350 ℃ unstretched yarn is not stretched, if it exceeds 450 ℃ unstretched yarn damage to heat occurs workability is poor.

After applying the proper amount of oil to the solidified yarn in the oil ring roller (9), it is preliminarily stretched in the high feed rollers GR 2 (10) and GR 3 (11), and then the high feed rollers GR 3 (11) and GR 4 (12). The second high ratio drawing is carried out in the), and is relaxed on the high rollers GR 4 (12) and GR 5 (13) and wound up. Polyethylene terephthalate manufactured in such a process can be useful for industrial webbing products because the yarn quality is excellent and the strength is very high and the elongation at break is higher than the conventional invention yarn obtained even in high elongation is good spinning workability.

The polyethylene terephthalate yarn of the present invention has excellent workability at higher draw ratios of 6.5 to 7.5 times higher than conventional draw ratios. Such high elongation can be achieved by various factors. The ductility of the present invention is determined by organic bonding of various factors such as low molecular weight ethylene-based copolymer, heater hood temperature and the like.

In the present invention, a low molecular weight ethylene-based copolymer as described below is preferably added in an amount of 0.5 to 2.0 wt% based on the weight of the polyethylene terephthalate chip. When it exceeds 2.0% by weight, the workability of forming yarns during the spinning process is poor, and the spinning workability is not good, and when it is less than 0.5% by weight, it is difficult to manufacture high-strength yarns due to poor elongation of undrawn yarn.

[Formula 1]

The M-value of the low molecular weight ethylene-based copolymer is preferably 5 or less, and when it exceeds 5, it is difficult to uniformly disperse the inside of the molten extruder, making it difficult to secure spinning workability.

The method of performing the physical property evaluation in the Example and the comparative example was done as follows.

1) Measuring modulus and elongation of yarn

After leaving the yarn in a standard condition, that is, a constant temperature and humidity chamber at a temperature of 25 ° C. and a relative humidity of 65% for 24 hours, the sample is measured by a tensile tester using the ASTM 2256 method.

2) Shrinkage Measurement Method

The yarn is left for 24 hours in a standard condition, that is, a constant temperature and humidity room with a temperature of 25 ° C. and a relative humidity of 65%. It is left to stand in 150 degreeC oven for 30 minutes. The yarn is left for 24 hours in the standard condition. Measure the reduced elongation of the yarn. (L ₀ : Length measured under super load (0.01 g / d) after leaving the sample at standard condition for 24 hours, L ₁ : Length of sample reduced under super load (0.01 g / d) after applying heat for a certain time)

3) pin shooter

Using a Pilot Warper tester, the yarn length is measured at 30,000 meters at a speed of 300 to 500 m / min and a sensitivity of 2.5 to 4.5 levels (relative value).

4) Workability

Observe for 24 hours in one position to determine the number of trimmings that occur purely on the high pitch roller.

5) Elongation load rate (%)

It is expressed as the ratio between the draw ratio (A) in which the physical property of strength 10.0 g / d is expressed and the total draw ratio (B) increased until the trimming during spinning (high draw load ratio is not good).

5) MI or Melt Flow Index

Melt at 190 ° C (2.16kg Load) by ASTM 1238 to measure the weight (g) flowing for 10 min ..

Examples 1-8 and Comparative Examples 1-6;

A polyethylene terephthalate chip having a number average molecular weight of 33,500 and a weight average molecular weight of 62,300 and a small amount of low molecular weight ethylene-based copolymer chip (additive) were extruded through the nozzle to melt polymer, and the hood heater temperature was 400 ° C. After cooling with cooling air, it was concentrated, oiled and spun at 1500 m / s at a draw ratio of 6.2 magnification at a speed of 2500 m / min.

TABLE 1

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Additive Content (wt%) 0.5 1.0 1.5 0 2.0 1.0 Additives MI 2 2 2 - 2 8 Stretch Load Rate (%) 88 85 89 93 92 88 Total draw ratio 7.05 7.29 6.97 6.67 6.74 7.05 Denier 1515 1523 1512 1516 1515 1512 Modulus (g / d) 128 124 121 110 104 88 Strength (g / d) 9.95 10.15 10.02 9.65 9.87 9.45 Body cut (%) 13.2 13.8 14.1 13.6 14.8 15.4 Shrinkage (%) 9.2 8.8 8.5 10.3 8.6 8.3 Pin Shooter (ea / 10 ⁸ m) 190 150 210 650 1600 3700 Workability (count / day) 0.9 0.8 1.1 2.5 4.8 7.2

1 is a manufacturing process schematic diagram of the present invention

<Description of Symbols for Major Parts of Drawings>

1: Extrude 2: Gear Pump

3: filter 4, 5, 6: hood heater,

7: intake 8: exhaust

9: oil ring roller 10, 11, 12, 13: high speed roller

14: winder

Claims (3)

Industrial high strength polyethylene terephthalate fiber comprising a low molecular weight ethylene-based copolymer having the structural formula 1 0.5 to 2.0% by weight. [Formula 1]

The method of claim 1, The low molecular weight ethylene-based copolymer is MI high strength polyethylene terephthalate fiber, characterized in that less than 5. The low molecular weight ethylene-based copolymer of Structural Formula [1] was mixed with a polyethylene terephthalate chip having a number average molecular weight of 25,000 or more and a weight average molecular weight of 50,000 or more, and then mixed with 0.5 to 2.0% by weight of the polyethylene terephthalate chip. After melt extrusion to further spin through the nozzle of the spinneret, to produce a non-drawn yarn at a hood heater temperature of 350 to 450 ℃ under the spinning nozzle, and stretching the undrawn yarn by 6.5 to 7.5 times Method for producing polyethylene terephthalate fiber.

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