KR101775142B1 - A polyethylene multifilament fiber with high tenacity and its manufacturing process - Google Patents

Abstract

Melt-spinning a high-density polyethylene resin (HDPE) having a melt index of 0.5 to 5 g / 10 min and cooling and solidifying to form an undrawn filament; And a step of subjecting the undrawn yarn to a stretching-heat fixing-relaxation-winding process using a multi-stage stretching roller, and a method of producing high-strength polyethylene multifilament fibers.

Description

[0001] The present invention relates to a high strength polyethylene multifilament fiber and a manufacturing method thereof,

The present invention relates to a polyethylene multifilament fiber having a multifilament characteristic while maintaining a high strength higher than that of a conventional industrial polyethylene filament yarn and a method for producing the same. More specifically, Strength polyethylenic multifilament fiber produced by optimizing spinning conditions and winding conditions so as to produce a yarn exhibiting high strength properties, and a method for producing the same.

Polyethylene multifilament fibers, which are currently used in the market, are very strong in strength, but they are manufactured in a low-speed two-stage production system system, and are only partially used in safety gloves and bulletproof materials due to high product prices. On the other hand, film or monosan produced by cutting a film is widely used in tarpaulins or fish nettings, but has a limited range of use because it is not suitable for high quality industrial products because of its low strength and lack of flexibility.

Therefore, there is a demand in the market for the development of economical high strength industrial polyethylene multifilament.

Methods that can produce high strength polyethylene yarns are divided into solution (gel) spinning and melt spinning.

In the solution (gel) spinning method, millions of ultra high molecular weight polyethylene can be used as a raw material, so that strength comparable to that of carbon fiber or aramid can be developed. However, a large-scale additional equipment for recovering and refining the solvent is required The manufacturing cost is very high, which is uneconomical. The melt spinning process is widely used as a method for producing thermoplastic polymers. However, when the molecular weight is increased in order to increase the strength of the polyethylene, melt fracture occurs in the nozzle during the spinning process, and the spinning itself becomes impossible. In the case of a currently commercially produced polyethylene film, there is a limitation in lowering the mono fineness by dividing the drawn film by stretching. The monofilament yarn is cooled in a water tank, and most of them are produced at a low speed of less than 200M per minute because of the use of large horizontal rollers and hot air ovens.

Currently, the only manufacturing method for melt spinning multifilament is limited to the use of expensive safety products such as a low-speed production system of less than 300 m per minute in a two-stage system in which radiation and drawing are separated. Therefore, in the present invention, the melt index and the production conditions (spinning and winding conditions) of the polyethylene resin are optimized by using a spin-draw high-speed production method, thereby exhibiting high strength properties while maintaining excellent processability.

Some of the technologies that have already been released include:

US Pat. Nos. 4,413,110 and 6,448,359 disclose a method for producing high strength polyethylene of 3 GPa or more by gel spinning, but there is a problem of solvent recovery due to solution spinning and low productivity as a two-step production method.

US Pat. No. 4,228,118 discloses a technique for producing high strength yarn of 12 g / d or more using HDPE having a molecular weight of 120,000, but the spinning speed of the two-step production system is 44 m / min and the drawing speed is 86 m / min.

Korean Patent No. 2013-0135880 discloses a method for producing films and fibers by extruding over 2 million ultra high molecular weight polyethylene at high pressure, but it is not suitable for high-speed production methods of more than 1500 m per minute.

In Korean Patent No. 2014-0075842, a high strength multifilament fiber of 15 g / d or more is manufactured using HDPE resin in which the gel and molecular weight distribution ratio are controlled within a predetermined range, but there is a problem in economical efficiency because the production method is two steps and low speed production .

Korean Patent Publication No. 2003-0083352 discloses a method of producing a flat yarn having a strength of 4 to 5 g / d by adding polypropylene. However, since it is low in strength, requires separate equipment for adding additives, and has a low production rate, low.

US Pat. No. 8,057,897 discloses a manufacturing method in which an HDPE resin is appropriately added to an ultrahigh molecular weight polyethylene resin (UHMWPE) and melt-spun to express a high strength of 20 g / d or more. However, since the spinning and drawing are separately separated into two separate low- There is a problem with.

An object of the present invention is to solve the problems and disadvantages of the prior art mentioned above by selecting appropriate resins without using equipment modification, resin modification or additives, and then optimizing spinning conditions and winding conditions, It is another object of the present invention to provide a method for manufacturing a polyethylene multifilament fiber which exhibits a higher strength than a polyethylene filament yarn at a high speed.

To solve these problems, according to one aspect of the present invention,

Melt-spinning a high-density polyethylene resin (HDPE) having a melt index of 0.5 to 5 g / 10 min and cooling and solidifying to form an undrawn filament; And

And a step of subjecting the undrawn yarn to a stretching-heat fixing-relaxation-winding step using a multi-stage stretching roller, is provided.

In the step of forming the undrawn yarn, the spinning temperature of the spinning machine for melt spinning the high-density polyethylene resin is adjusted to 220 to 270 ° C.

The stretching step is carried out at a stretching ratio of 6.0 to 7.0 and a stretching temperature of 120 to 130 占 폚, and the winding step may be carried out at a winding speed of 1,500 m / min or more.

According to another aspect of the present invention,

High-strength polyethylene multifilament fibers produced by the above-described method can be provided.

The polyethylene multifilament fiber may have a fineness of 100 to 2,000 denier, a mono-fineness of 1 to 20 denier, an intensity of 7.0 to 12.0 g / d, and an elongation of 10 to 35%.

According to an embodiment of the present invention, a polyethylene fiber having a high strength of 7.0 g / d or more is spin-drawn at a high speed, unlike a conventional low-speed two-step polyethylene fiber. More specifically, it is possible to determine a melt index of a high-density polyethylene (HDPE) resin suitable for exhibiting physical properties and good processability, and at the same time, appropriate spinning conditions and winding conditions are optimized, The filament yarn can be produced at a high speed.

The high strength polyethylene multifilament fiber thus produced can be effectively used as a material for a wide range of industrial textile fields such as rope, webbing, tarpaulin, truck cover paper, billboard, and leisure goods, which are required to be lightweight and recycled.

Fig. 1 is a schematic view of an apparatus for producing a polyethylene multifilament fiber used in the production method of the present invention.

Hereinafter, the method for producing the polyethylene multifilament fiber of the present invention will be described in detail. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concepts of the terms appropriately Should be construed in accordance with the principles of the present invention,

The present invention relates to a process for producing a high strength polyethylene multifilament fiber excellent in workability without modification of equipment or modification of a polymeric material or an additive by high speed winding and selecting a suitable level of resin melt index capable of exhibiting high strength properties, , And then cooled and solidified polyethylene filaments of non-heat-shrinkable filaments are subjected to a conventional radial emulsion (Kiss Roller or Jet Oiler) prior to a high-defect roller, followed by stretching, heat fixing, relaxation, Process.

The present invention is characterized in that a polyethylene chip having a melt index of 0.5 to 5 g / 10 min is melted and melt-spinned at a temperature of 220 to 270 ° C, followed by emulsion application, multi-stage stretching, heat fixing and relaxation.

In addition, in the present invention, in order to produce a yarn satisfying the high strength characteristics of 7.0 g / d or more superior to the conventional industrial polyethylene film yarns, the polyethylene undrawn yarn is stretched at a stretching ratio of 6.0 to 7.0 and a stretching temperature of 120 to 130 DEG C .

The present invention achieves a method capable of producing a polyethylene fiber having a high workability and high strength and low shrinkage property at a winding speed of 1,500 m / min or more by a direct radiation drawing process.

Hereinafter, the present invention will be described in detail.

According to one embodiment of the present invention, the polyethylene melt which melts a high density polyethylene (HDPE) resin having a melt index of 0.5 to 5 g / 10 min and is discharged through the spinneret is in a state of the polyethylene unstirred state cooled before the first goethite roller.

The polyethylene undrawn yarn is stretched in a multi-stage roller, and after being subjected to a heat fixing process in a roller, it is wound on a roller rotating at a high speed through a relaxation process.

Considering the characteristics of a polyethylene resin chip having a melt index of 0.5 to 5 g / 10 min, melt spinning was carried out at a spinning temperature of 220 to 270 DEG C, and the stretching ratio and the stretching temperature were varied, Thereby producing a polyethylene multi-filament yarn exhibiting high strength properties.

In the spinning conditions of the present invention, the melt index of the polyethylene resin chip is preferably from 0.5 to 5 g / 10 min. When the melt index is less than 0.5 g / 10 min, the melt fracture phenomenon is significant and the spinnability is increased, And when the melt index exceeds 5 g / 10 min, there is a problem that the strength is difficult to manifest due to the low molecular weight.

The spinning temperature of the spinning machine is preferably 220 to 270 ° C. If the spinning temperature is lower than 220 ° C., the melting temperature may be low, resulting in a problem of nonuniformity, excessive shearing stress in the nozzle and melt fracture phenomenon A problem occurs in that it becomes worse. When the spinning temperature exceeds 270 캜, the thermal decomposition of the polyethylene melt accelerates and the physical properties at the target level may be difficult to manifest. The gear pump temperature and cooling conditions can then be carried out under normal conditions.

Under these conditions, the prepared non-drawn yarn is passed through a multi-stage high-precision deterioration roller and subjected to a stretching-heat fixing-relaxation-winding process.

When the stretching ratio is less than 6.0, the fiber orientation is low and the strength development is difficult. When the stretching ratio is more than 7.0, the yarn is broken and the appearance of the yarn becomes bad due to the occurrence of the single yarn thread. If the situation persists, full envoys may arise.

If the temperature is lower than 120 ° C, the heat transferred to the yarn is insufficient and the stretching yarn is broken due to the lowering of the stretching efficiency. When the temperature exceeds 130 ° C, And the yarn strength may be lowered.

Example

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the above-described embodiments. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

The measuring method in the examples is shown below

1. Melt index (M.I)

The amount of the resin flowing at 190 占 폚 under a load of 2.16 kgf for 10 minutes by the ASTM D1238 method is measured

2. How to measure the strength of yarn

The yarn is allowed to stand for 24 hours under a standard condition, that is, in a temperature and humidity chamber at a temperature of 25 ° C and a relative humidity of 65%, and then the sample is measured by a tensile tester by the method of ASTM D-885.

3. Method to measure dry heat shrinkage rate

The yarn is allowed to stand in a standard state, that is, a constant temperature and humidity chamber at a temperature of 25 DEG C and a relative humidity of 65% for 24 hours. Allow to stand in an oven at 100 ° C for 5 minutes. Allow the yarn to stand for 24 hours under standard conditions. The shrinkage percentage of the yarn is measured according to the following equation.

Shrinkage (%) = (L0-L1) / L0 100

In the above equation,

L0 is the length of the sample measured under ultra-high load (0.01 g / d) after 24 hours' standing in the standard state, and L1 is the length of the sample reduced under the ultra-high load (0.01 g / d)

Example  1 to 5

Polyethylene multifilament fibers were produced as follows using the apparatus for producing polyethylene multifilament fibers according to an embodiment of the present invention shown in FIG.

A polyethylene chip having a melt index of 0.5 to 5 g / 10 min was charged into the extruder 1, and the extrusion temperature was set to 240 캜. Using a polymer gear pump, the number of holes of the spinneret 2 The melted polymer is extruded through the 48 individual nozzles 3 and cooled with quench air at 20 to 25 ° C using the cooling device 4 and then the radial emulsion is attached using the radial emulsion applying device 5, The unstirred yarn with the emulsion attached thereto was once wound up at 250 m / min, and then stretched and heat-treated while passing through five godet rollers (6) in the box (7). Thereafter, using the entanglement device 8 and the winder 9, the resulting product was wound into a fineness of 400 denier.

Specifically, polyethylene multifilament fibers were prepared by spinning and stretching under the spinning and drawing conditions shown in Table 1 below.

The physical properties of the prepared polyethylene multifilament fiber were measured, and the results of the total draw ratio and physical properties of the stretched yarn are shown in Table 1. In each of the examples, the melt index, spinning temperature, stretching ratio, and stretching temperature conditions were the same as those in the following Table 1 and the other spinning conditions were the same.

According to the following Table 1, it was confirmed that the polyethylene multifilament fibers of Examples 1 to 5 had a high strength property of 7.0 g / d or more.

Example 1 Example 2 Example 3 Example 4 Example 5 The melt index (g / 10 min) 1.0 1.1 1.1 0.6 0.6 Radiation temperature (℃) 240 230 230 250 250 Stretching cost 6.5 6.5 7.0 6.0 6.2 Stretching temperature (占 폚) 120 120 120 120 120 Strength (g / d) 7.5 7.2 7.5 7.0 7.2 Shinto (%) 20 22 21 27 22 Dry Heat Shrinkage (%) 4 5 4 4 4 Exterior Good Good Good Good Good

Comparative Example  1 to 7

Polyethylene multifilament fibers were prepared in the same manner as in Example 1, except that the fibers were spinnable and drawn at a melt index, a spinning temperature, a stretching ratio, a stretching temperature,

The properties of the obtained polyethylene multifilament fibers were measured, and the results are shown in Table 2.

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 The melt index (g / 10 min) 0.2 20 1.0 1.0 1.0 1.0 1.0 Radiation temperature (℃) - 220 200 280 240 240 240 Stretching cost - 7.0 - 7.0 5.0 6.5 7.5 Stretching temperature (占 폚) - 120 - 120 120 140 120 Strength (g / d) - 2.0 - 6.5 6.0 6.5 8.0 Shinto (%) - 100 - 30 33 30 17 Dry Heat Shrinkage (%) - - - 3 3 3 6 Exterior Difficulty in radiating Good Difficulty in radiating Good Good Good Mud bad

In Comparative Example 1, spinning was difficult due to melt fracture due to excessive shear stress at the nozzle using a resin having a low melt index. In Comparative Example 2, the result of using a resin having a melt index of 20 g / 10 min The desired level of strength was not expressed.

Also, in Comparative Example 3, the spinning temperature was too low, and the spinning itself was difficult due to the melt fracture due to excessive shear stress at the nozzle. In Comparative Example 4, the spinning temperature was too high to cool, The strength of the final yarn was lowered.

Further, in Comparative Example 5, the stretching ratio was low and the strength of the final yarn was not sufficiently developed. In Comparative Example 6, the stretching temperature was too high, so that fusion occurred between some filaments and the overall strength was lowered. In Comparative Example 7, As a result, some filaments, etc., were broken, resulting in product appearance.

1: extruder, 2: spinneret, 3: nozzle, 4: cooling device
5: radial emulsion applying device, 6: high-precision roller, 7: box, 8: interlocking device 9: winder

Claims (5)

Melt-spinning a high-density polyethylene resin (HDPE) having a melt index of 0.5 to 5 g / 10 min and cooling and solidifying to form an undrawn filament; And
And a step of subjecting the undrawn yarn to a stretching-heat fixing-relaxation-winding step using a multi-stage stretching roller,
In the step of forming the non-drawn filament, the spinning temperature of the spinning machine for melt spinning the high-density polyethylene resin is adjusted to 220 to 270 캜,
Wherein said stretching step is carried out at a stretching ratio of 6.0 to 7.0 and a stretching temperature of 120 to 130 캜 to exhibit a strength of 7.0 to 12.0 g / d and an elongation of 20 to 27%, wherein said high-strength polyethylene multifilament Method of making fiber. The method according to claim 1,
Wherein the winding step is carried out at a winding speed of 1,500 m / min or more. A high strength polyethylene multifilament fiber produced by the method of claim 1 or 2. The method of claim 3,
Wherein said polyethylene multifilament fibers have a fineness of 100 to 2,000 denier and a mono-fineness of 1 to 20 denier. delete

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