WO2019135466A1 - High-strength polyethylene fiber having improved processability - Google Patents

Abstract

The present invention relates to a high-strength polyethylene fiber having improved processability, the polyethylene fiber being formed from a polyethylene resin, thereby having ethylene as a major repeating unit thereof, wherein the polyethylene resin has a melt index of 0.6 to 2g/10min, and a melt index ratio (HLMI/MI) of 20 to 40.

Description

High Strength Polyethylene Fiber with Improved Fairness

The present invention relates to a high strength polyethylene fiber having improved processability, and more particularly, to a high strength polyethylene fiber having improved processability by controlling the melt index of a polyethylene resin forming a polyethylene fiber.

Polyethylene resin is used for engineering plastics, films, fibers and nonwoven fabrics because of its low price, excellent chemical resistance and product processability. In the textile field, it is made of monofilaments and multifilaments, Applications are being expanded. Particularly, there is an increasing interest in high-performance polyethylene fibers which require high strength and high elasticity according to the latest fiber trends.

In U.S. Patent No. 4,228,118, a polyethylene resin having a number average molecular weight of 20,000 or more and a weight average molecular weight of 125,000 or less is melted at a spinning temperature of 220 to 335 ° C and extruded into a nozzle having 8 holes to obtain a hot- At a temperature of 200 to 335 DEG C at a minimum spinning speed of 30 m / min, and then stretched 20 times or more to produce fibers of 10 to 20 g / d. However, this method has a limitation in the production rate due to the low spinning speed according to the nozzle odd number and the spin draw method in the commercial production of the polyethylene filament, and produces the polyethylene filament having excellent uniformity and radiation workability when producing tens to hundreds of multifilament .

In addition, Korean Patent No. 0909559 discloses a high strength polyethylene fiber having a weight average molecular weight of 300,000 or less and a ratio (Mw / Mn) of a weight average molecular weight to a number average molecular weight of 4.0 or less, . However, it is difficult to control the molecular weight distribution index of the raw material to 4.0 or less. In order to form a low molecular weight distribution index and exhibit high strength, 10 times or more of high stretching is required.

Generally, high-strength polyethylene fibers are excellent in cutting resistance and are widely used in industrial products such as safety gloves for industrial purposes. However, the cutting resistance of conventional industrial products made of high-strength polyethylene fibers is a property of being manifested only by the strength of polyethylene fibers. There is a problem that the cut resistance may be lowered when the strength is not uniform or the strength is weakened at a specific portion.

In addition, high-strength polyethylene fibers using a solvent among high-strength polyethylene fibers produced by conventional techniques have a problem that the whiteness of the polyethylene fibers is lowered due to the influence of the solvent, which limits the use of the fibers.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made in an effort to solve the above problems of the prior art, and it is an object of the present invention to provide a polyethylene fiber having improved fixability by controlling the melt index ratio of a polyethylene resin forming high-

Also, the polyethylene fiber according to the present invention is intended to provide a high-strength polyethylene fiber having improved cutting resistance by forming a node on the surface of the fiber.

The present invention relates to a polyethylene fiber, which is formed of a polyethylene resin and whose main repeating unit is ethylene, wherein the polyethylene resin has a melt index of 0.6 to 2 g / 10 min and a melt index ratio (HLMI / MI) of 20 to 40 Thereby providing the improved high strength polyethylene fiber.

Further, there is provided a high strength polyethylene fiber having improved processability, wherein a plurality of nodules are formed on the surface of the polyethylene fiber.

Further, the polyethylene resin has a molecular weight distribution index of 5 to 10, and provides a high-strength polyethylene fiber with improved processability.

Further, the present invention provides a high-strength polyethylene fiber having improved processability, wherein the polyethylene fiber has a strength of 12 to 16 g / d.

The present invention also provides an article comprising the above polyethylene fibers.

In addition, the polyethylene article has a level of 3 or more according to the cutting resistance standard.

Further, the polyethylene article has an intrinsic breaking strength of 4.0 N or more.

The high-strength polyethylene fiber having improved processability according to the present invention has a high strength and multi-step stretchability by using a polyethylene resin whose melt index ratio is adjusted to 20 to 40, and has an excellent strength. The yarn has a small number of spinning and stretching yarns, It is effective.

In addition, the high-strength polyethylene fiber of the present invention has an effect of increasing the surface area of the fiber, such as a bamboo shape, on the surface thereof, and lubricating the blade when the blade is in contact with the blade.

1 is a photograph showing a high-strength polyethylene fiber with improved processability according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that, in the drawings, the same components or parts have the same reference numerals as much as possible. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted so as to avoid obscuring the subject matter of the present invention.

As used herein, the terms " about, " " substantially, " " etc. ", when used to refer to a manufacturing or material tolerance inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

In the present invention, the melt index ratio means a ratio (HLMI / MI) of a high load melt index (HLMI) to a melt index (MI). The high load melt index (HLMI) Melt Index (MI) means the weight discharged when the measurement temperature is 190 ° C and the weight is 2.16 kg.

1 is a photograph showing a high-strength polyethylene fiber with improved processability according to the present invention.

The present invention relates to a polyethylene fiber which is formed of a polyethylene resin and whose main repeating unit is ethylene. The polyethylene resin is a high-strength polyethylene having a melt index of 0.6 to 2 g / 10 min and a melt index ratio (HLMI / MI) Fiber.

The polyethylene resin forming the high-strength polyethylene fiber of the present invention preferably uses a polyethylene resin having a melt index of 0.6 to 2.0 g / 10 min, preferably 0.8 to 1.4 g / 10 min.

If the melt index is less than 0.6 g / 10 min, the flowability of the melt of the polyethylene resin in the extruder is not good and the spinning speed can not be increased, which may cause problems such as nozzle face refinement during spinning. When the melt index exceeds 2.0 g / 10 min, the spinning workability is excellent, but the flowability at an appropriate spinning temperature is not suitable, and it may be difficult to obtain polyethylene fibers having high strength after stretching.

In addition, the polyethylene resin forming the high-strength polyethylene fiber of the present invention preferably has a melt index ratio (HLMI / MI) adjusted to 20 to 40. [

Polyethylene resin having a melt index ratio of less than 20 requires control of polyethylene raw material, catalyst technology, and dedicated equipment for the catalyst only, and is difficult to control at less than 20 in raw material companies because of high density control, and manufacturing reproducibility is poor. When the melt index ratio is 40 or more, high stretch ratio and multi-step stretching are difficult during spinning, stretching, low strength, and cut resistance.

The polyethylene resin used in the present invention preferably has a weight average molecular weight (Mw) of 100,000 to 300,000 and a molecular weight distribution index (weight average molecular weight / number average molecular weight, Mw / Mn) of 5 to 10.

When the weight average molecular weight (Mw) is less than 100,000, the spinning workability of spinning is improved, but there is a limit in manifesting high strength. When the weight average molecular weight is more than 300,000, Workability can be adversely affected.

When the molecular weight distribution index is less than 5, high-magnification elongation of 10 times or more is required in order to exhibit high strength, and defects of the mowing and elongating rollers are increased, which may deteriorate quality as the number of stretching is increased. In addition, when the molecular weight distribution index is more than 10, since a large number of high molecular weight polyethylene and low molecular weight polyethylene in polyethylene resin are mixed, a smooth drawing process can not be performed, and thus there is a limitation in expressing high strength.

Using the polyethylene resin as described above, the polyethylene fiber of the present invention in which the repeating unit is substantially ethylene has a node like the bamboo shape of the surface shape of the fiber as shown in Fig.

The node is repeatedly formed as a curved portion curved inward between the protruded node portion and the node portion.

As described above, the nodes formed on the surface of the fiber increase the surface area of the fiber and lubricate when the blade contacts, thereby improving the cut resistance.

In addition, the nodules formed on the fiber surface irregularly reflect light, thereby improving the whiteness of the fiber.

In addition, when the number of the nodules is less than 5, the improvement of cutting resistance and whiteness due to nodules may be insignificant. When the number of nodules exceeds 10, Can be degraded.

The high-strength polyethylene fiber having improved processability according to the present invention may be produced by melt spinning to form an undrawn yarn and a drawing step to draw the non-drawn yarn.

The step of forming a non-drawn filament by the melt-spinning comprises melting the polyethylene resin having the controlled molecular weight distribution index and melt index in an extruder, spinning it at a low speed of 1000 m / min or less by installing a nozzle hot tube, Can be produced.

The inside of the extruder can be divided into four zones, and the temperature range of each temperature zone can be set to 200 to 270 ° C, preferably 220 to 250 ° C. When the temperature range is less than 200 ° C, the uniformity of the non-drawn yarn is good, but there is a high possibility of occurrence of static electricity during spinning, and the workability in the stretching process is low. If the temperature range is higher than 270 캜, the stretching magnification can be improved in the stretching step, but cooling and solidification of the unstretched yarn becomes difficult to lower the uniformity of the unstretched yarn, and the number of stretch- Can fall.

The spinning nozzle for spinning may be from 60 to 400 holes to produce a high strength polyethylene fiber having improved processability of the present invention.

The non-drawn yarn produced as described above can be subjected to the stretching step using a multi-stage stretching roller.

It is preferable that the high-strength polyethylene fiber with improved processability of the present invention is stretched by a three-stage stretching process, wherein the stretching temperature is from 60 to 100 占 폚, the stretching temperature is from 80 to 120 占 폚 and the stretching temperature is from 100 to 120 占 폚 Lt; / RTI >

Preferably, the two-step stretching temperature is higher than the first-step stretching temperature, and the third-step stretching temperature is also preferably higher than the second-step stretching temperature.

Under the first stage stretching temperature and the second stage stretching temperature range, sufficient heat is not supplied to the fibers when the stretching is carried out, so that the stretching is non-uniformly formed to increase the yarn forming rate at the roller surface, If the stretching temperature and the two-stage stretching temperature range are exceeded, the melt of the fibers may occur on the surface of the rollers, resulting in an increase in the number of times the surface of the rollers is cut and the number of the rollers is increased.

The three-step stretching is carried out in order to fix the fiber heat and to prevent the fiber from shrinking, and it is preferable that the stretching is practically carried out in the first-stage and second-stage stretching.

The nodes of the surface of the high-strength polyethylene fiber according to the present invention are presumed to be formed by the use of the polyethylene resin whose molecular weight distribution index and melt index are controlled and the step of stretching as described above. And it is presumed that the nodes formed in the three-step stretching step are fixed.

When the total draw ratio DR is lower than 6, the strength of the polyethylene fibers is lowered. When the total draw ratio DR is higher than 10, the filament is more likely to occur during drawing, May be deteriorated.

As described above, the high-strength polyethylene fiber having improved processability according to the present invention formed by using and stretching the polyethylene resin whose molecular weight distribution index and melt index are controlled has a strength of 12 to 16 g / d, a mono-fineness of 0.5 to 2.5, And the number of strands is 60 to 400. [

The high strength polyolefin fibers may also be used in a wide variety of other types of articles.

Non-limiting examples include, for example, insulating materials for refrigeration units (e.g., refrigerators, freezers, vending machines, etc.); Automotive parts (eg, front or back sheet, headrest, arm rest, donor panel, rear shelf / package tray, steering wheel and interior trim, dashboard, etc); Architectural panels and components (eg roofs, wall joints, underfloor, etc.); Clothing (eg, coat, shirt, trousers, gloves, apron, work clothes, shoes, boots, hats, sock liner etc); Furniture and bedding (eg, sleeping bags, comforters, etc.); Fluid storage / transfer systems (eg, liquid / gas hydrocarbons, liquid nitrogen, oxygen, hydrogen, or crude oil pipes or tanks); Extreme environments (eg underwater or universe); Food and beverage products (eg cups, cup holders, plates, etc.); Containers and bottles; And the like.

In addition, the polyolefin fibers can be used in "garments " which means that they include any article having a shape that is generally adapted to a portion of the body. Examples of such items include, but are not limited to, clothing (e.g., shirts, trousers, jeans, slacks, skirts, coats, activewear, sportswear, aerobics and gym clothes, swimwear, cycling jerseys or shorts, bathing suit, lace suit, sweat suit, body suit, etc.); Footwear (for example, shoes, socks, boots, etc.); (E.g., undergarment, undergarment, undergarment, undergarment, undergarment, undergarment, undergarment, t-shirts, etc.), compression garments, and hanging garments (e.g., kilt nappa, toga, poncho, cloak, shawl, etc.).

Hereinafter, high-strength polyethylene fibers having improved processability were prepared according to the present invention. But the present invention is not limited to these examples.

Examples 1 to 5 and Comparative Examples 1 to 5

A polyethylene resin having a melt index of 0.6 to 2 g / 10 min and a molecular weight distribution index of 5 to 10 is put into an extruder to extrude the molten polymer and cooled using a cooling device, And an unstiffened yarn with an emulsion was wound thereon, and the unstretched yarn was subjected to stretching and heat treatment. Thereafter, a high strength polyethylene fiber with improved processability according to the present invention was produced by winding using an interlocking device and a winder.

The stretching was performed by a three-stage stretching using a multi-stage stretching roller. The stretching was carried out at a stretching temperature of about 70 占 폚, a stretching temperature of about 92 占 폚 of about 3 占 폚, and a stretching temperature of about 105 占Respectively.

The weight average molecular weight, the molecular weight distribution index, the melt index, the melt index ratio, and the total draw ratio (DR) were the same as in Tables 3 and 4 and the other spinning conditions were the same in the respective Examples and Comparative Examples.

FIG. 1 is a SEM photograph of a polyethylene fiber of Example 1 showing that nodes are formed at regular intervals.

◈ Measurement method

The strength, the occurrence frequency, the index of cut resistance, the level and the breaking strength of the examples 1 to 5 and the comparative examples 1 to 5 were measured.

The index of cut resistance, level and endurance were measured after knitting with the polyethylene fibers of Examples 1 to 5 and Comparative Examples 1 to 5.

Table 3 shows the blade occurrence frequency, cutting resistance level and cutting strength of the examples. Table 3 shows the blade occurrence frequency, cutting strength level and cutting strength of the comparative examples.

* Measurement of melt index: Measured according to ASTM D1238dp. The measurement temperature was 190 ° C, and the weight was defined as 21.6 kg of high-load melt index and 2.16 kg of melt index. Preheating was performed for 5 minutes and free run for 3 minutes , And the value measured 10 times was defined as an average value.

* Strength measurement method: Measured according to ASTM D-2256 using a universal testing machine UTM (Universal Testing Mechine, INSTRON), and measured 10 times at a rate of 300 mm / min under a relative humidity of 65% The intensity was defined as the mean value.

Strength is defined as the value of g / d divided by the denier, when the tensile fibers are cut, by holding the fibers in an universal testing machine and applying tensile load at the above speed to yield a stress-strain curve.

* Frequency of occurrence of moth (process stability evaluation): The frequency of occurrence was evaluated according to the number of moths per 100,000 m of total produced yarn.

* Index and level of cut resistance: Mesdan Yarn cut tester, a device manufactured in accordance with EN388 standard, was used to evaluate the cut resistance of fabric or knitted fabric. The measurement was performed by placing an aluminum foil wrapped with a filter paper on a rubber support, placing the control sample and the test sample, measuring the control sample and the test sample five times before the test, and evaluating the index as follows.

<Cutting resistance index>

Sequence	CControl specimen	TTest specimen	CControl specimen	IIndex
One	C 1	T 1	C 2	i1
2	C 2	T 2	C 3	i2
3	C 3	T 3	C 4	i3
4	C 4	T 4	C 5	i4
5	C 5	T 5	C 6	i5

[Cutting resistance index (I) formula]

<Cutting resistance level>

Cutting resistance index	> 1.2	> 2.5	> 5	> 10	> 20
Cutting resistance level	One	2	3	4	5

* Cutting force (N): The method of evaluating the cutting force of a fabric or a knitted fabric was a model STM610 of Satara, manufactured according to the ISO13997 standard. Cutting is measured by the cutting force required when cutting the material to a blade quality of 20 mm when the range of force is applied to the blade perpendicular to the surface of the sample. The measuring sequence is a gradual application of a constant force between the sample and the blade. And repeat the test with different forces until at least 15 records with a cut length between 5 mm and 50 mm are obtained. The cutting force is obtained in the range of 5 mm to 15 mm, 15 mm to 30 mm, and 30 mm to 50 mm, and the value obtained by multiplying the correction factor C by the cutting length is plotted and the force at a cutting length of 20 mm is measured by the cutting force.

<Cutting Force Correction Factor>

C = K / l

C is a correction coefficient, l is 5.0N neoprene phase cutting operation length mm, K = 20

division	Example 1	Example 2	Example 3	Example 4	Example 5
Weight average molecular weight (g / mol)	250000	250000	250000	110000	130000
Molecular weight distribution index	7.6	7.8	7.6	5.8	7.8
The melt index (g / 10 min)	0.9	0.75	0.9	1.2	1.2
Melt index ratio (HLMI / MI)	31	38	31	26	38
Drawing Ratio (DR)	8	7.8	8	8.8	7.5
The island (De)	400	425	200	390	400
Strength (g / d)	15.2	15.5	15.1	15.8	14.3
Frequency of occurrence of mow (100,000 m / person)	4	8	4	8	8
Cutting resistance level	3	3	3	3	3
Cutting force (N)	10.4	10.4	11.6	9.4	8.2

division	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4	Comparative Example 5
Weight average molecular weight (g / mol)	250000	130000	80000	330000	330000
Molecular weight distribution index	8.2	8.5	5.8	8.2	10
The melt index (g / 10 min)	0.9	2.2	5.0	0.6	0.4
Melt index ratio (HLMI / MI)	46	52	35	43	80
Drawing Ratio (DR)	7.1	7.5	8.5	6	4
The island (De)	430	430	410	260	850
Strength (g / d)	13.2	12.1	12.2	14.1	8.5
Frequency of occurrence of mow (100,000 m / person)	26	15	16	32	60
Cutting resistance level	2	2	2	2	One
Cutting force (N)	6.2	3.5	3.8	7.8	2.6

As shown in Tables 3 and 4, in Examples 1 to 5 formed from a polyethylene resin having a melt index of 0.6 to 2 g / 10 min and a melt index ratio (HLMI / MI) of 20 to 40, 10, the process stability is excellent. However, in Comparative Examples 1 to 5, in which the melt index ratio exceeds 40, it is found that the processability is very low due to the occurrence frequency of moths of 15 to 60. In addition, To 5 are superior in strength to those of Comparative Examples 1 to 5, and that the cutting resistance level and the cutting strength are also superior to those of Comparative Examples 1 to 5.

Claims (8)

1. 1. A polyethylene fiber which is formed of a polyethylene resin and whose main repeating unit is ethylene,

   Wherein the polyethylene resin has a melt index of 0.6 to 2 g / 10 min and a melt index ratio (HLMI / MI) of 20 to 40. The high-
2. The method according to claim 1,

   Wherein a plurality of nodules are formed on a surface of the polyethylene fiber.
3. The method according to claim 1,

   Wherein said polyethylene resin has a molecular weight distribution index of 5 to 10. &lt; Desc / Clms Page number 24 &gt;
4. The method according to claim 1,

   Wherein the polyethylene fiber has a strength of 12 to 16 g / d.
5. The method according to claim 1,

   Wherein said polyethylene fibers have ten or less per 100,000 m of hair growth.
6. An article comprising the polyethylene fiber of any one of claims 1 to 5.
7. The method according to claim 6,

   Characterized in that the polyethylene article has a level of 3 or more according to the cutting resistance standard.
8. The method according to claim 6,

   Wherein the polyethylene article has a breaking strength of 4.0 N or more.

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