KR102178478B1 - High-strength polyethylene fiber having improved evenness, and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a high-strength polyethylene fiber formed of a polyethylene resin, wherein a main repeating unit is ethylene. The high-strength polyethylene fiber with improved uniformity is formed of a polyethylene resin having a melt index of 0.6 to 2 g/10min and a molecular weight distribution index of 5 to 10, and has a crystallinity of 75% or more, a crystal size of 10 Å or more, and uniformity (U%) of 4% or less.

Description

High-strength polyethylene fiber with improved uniformity and manufacturing method thereof {HIGH-STRENGTH POLYETHYLENE FIBER HAVING IMPROVED EVENNESS, AND MANUFACTURING METHOD THEREOF}

The present invention relates to a polyethylene fiber having excellent uniformity and a method for producing the same, and more particularly, to a polyethylene fiber having excellent uniformity and a method for producing the same by controlling the crystallinity and crystal size of polyethylene multifilament.

Polyethylene resin is increasingly used for engineering plastics, films, fibers and non-woven fabrics due to its low price, excellent chemical resistance, and product processability. In the textile field, it is manufactured as monofilament and multifilament, so it is used for clothing, industrial, etc. The use is expanding. In particular, interest in high-functional polyethylene fibers requiring high strength and high elastic modulus is increasing 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 then extruded into an 8-hole nozzle, and a hot drawing temperature of 115 to 132°C, a hot tube. After winding at a temperature of 200 to 335° C. at a minimum spinning speed of 30 m/min and stretching 20 times or more, fibers of 10 to 20 g/d were prepared. However, this method has a limitation in production due to the low number of nozzles and the spinning speed according to the spin-draw method in the commercial production of polyethylene fibers, and when producing tens to hundreds of multifilaments, polyethylene fibers with excellent uniformity and spinning workability are produced. I have difficulty in doing it.

In addition, in Korean Patent Registration No. 00909559, the weight average molecular weight is 300,000 or less, and the ratio (Mw/Mn) of the weight average molecular weight and the number average molecular weight, which is a molecular weight distribution index, is 4.0 or less, and it is specified for high-strength polyethylene fibers that exhibit high strength. Are doing. However, it is difficult to control the molecular weight distribution index of the raw material to 4.0 or less, and since the molecular weight distribution index is formed to be low, high elongation is required 10 times or more in order to express high strength, thereby reducing fairness in spinning workability and the like.

In general, high-strength polyethylene fibers are produced through a stretching step by discharging a polymer melted in the spinning step through tens to hundreds of spinnerets to form fibers.

The high-strength polyethylene fiber has a problem in that the uniformity is deteriorated because the cross section of the polyethylene fiber is not uniform due to shrinkage and relaxation applied during spinning and stretching.

The present invention was invented to solve the problems of the prior art as described above, and an object of the present invention is to provide a polyethylene fiber with improved cutting resistance and uniformity by controlling the crystallinity and crystal size of a polyethylene resin forming a high strength polyethylene fiber.

In addition, an object of the present invention is to provide a polyethylene fiber manufacturing method in which the uniformity is improved by controlling the crystallinity and crystal size of polyethylene fibers through the spinning speed in the spinning step and the aging step performed at a high temperature after stretching.

The present invention is a polyethylene fiber formed of a polyethylene resin and the main repeating unit is ethylene, wherein the polyethylene fiber is formed of 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, It provides a high-strength polyethylene fiber with improved uniformity, characterized in that the crystallinity is 75% or more, the crystal size is 10Å or more, and the uniformity is 4% or less.

In addition, it provides a high-strength polyethylene fiber with improved uniformity, characterized in that the crystallinity is 80% or more and a crystal size of 12Å or more.

In addition, it provides a high-strength polyethylene fiber with improved uniformity, characterized in that the strength of the polyethylene fiber is 12 to 16g/d.

In addition, in the present invention, in the method for manufacturing high-strength polyethylene fibers with improved processability, 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 melt-spun at 230 to 290°C to form undrawn yarn. Spinning step; A drawing step of drawing the undrawn yarn; And, an aging step of aging the stretched polyethylene fibers at 90-130°C. It provides a fiber manufacturing method.

In addition, in the spinning step, it provides a method for producing a high-strength polyethylene fiber with improved uniformity, characterized in that the spinning speed is 120 to 160 mpm.

In addition, the aging step provides a method for producing a high-strength polyethylene fiber with improved uniformity, characterized in that aging for 5 to 20 seconds.

In addition, the manufacturing method provides a method for manufacturing a high-strength polyethylene fiber with improved uniformity, characterized in that it satisfies the following equation (1).

Equation (1) 210≤S+T≤290

However, S is an integer of the spinning speed (mpm) of the spinning step, and T is an integer of the aging temperature (℃) of the aging step.

In addition, it provides an article comprising the polyethylene fiber or polyethylene fiber produced by the above production method.

In addition, the article provides an article characterized in that the level according to the cut resistance standard (Level) is 3 or more.

In addition, the article provides an article, characterized in that the cutting resistance is 4.0N or more.

The high-strength polyethylene fiber with improved uniformity according to the present invention has the effect of improving the cutting resistance and uniformity of the polyethylene fiber by controlling the crystallinity and crystal size of the polyethylene resin.

In addition, the present invention has the effect of controlling the crystallinity and crystal size of the polyethylene fiber through the spinning speed in the spinning step during the manufacturing process of the polyethylene fiber and the aging step performed at a high temperature after stretching.

1 is a flow chart showing a method of manufacturing a high-strength polyethylene fiber with improved uniformity according to the present invention.
Figure 2 is a schematic view showing the aging step of the high-strength polyethylene fiber manufacturing process according to the present invention.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. First of all, it should be noted that in the drawings, the same components or parts represent the same reference numerals as possible. In describing the present invention, detailed descriptions of related known functions or configurations are omitted so as not to obscure the subject matter of the present invention.

The terms'about','substantially', etc. of the degree used in the present specification are used at or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and are used in the sense of the present invention. To assist, accurate or absolute figures are used to prevent unfair use of the stated disclosure by unscrupulous infringers.

1 is a process chart showing a method of manufacturing a high-strength polyethylene fiber with improved uniformity according to the present invention, and FIG. 2 is a schematic view showing an aging step in a high-strength polyethylene fiber manufacturing process according to the present invention.

The present invention relates to polyethylene fibers formed of a polyethylene resin so that the main repeating unit is ethylene.

The polyethylene fiber is formed of 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, so that the polyethylene fiber has a crystallinity of 75% or more, a crystal size of 10 Å or more, and a uniformity of U% is 4%. It is characterized by the following.

The present invention is an invention that improves the cutting resistance of high-strength polyethylene fibers by controlling the crystallinity and crystal size, and the factors expressing the cutting resistance have not been specifically identified, but the paper J. Polym. Sci. Part B Polym. Phys., vol. 48, pp. 1861-1872 (2010), thesis Mater. Sci. Eng. A, vol. 500, 216-224 (2009), referring to the Fibril Formation and Fracture Mechanism of the crystallization of polyethylene, the slippage of the surface crystal from the point when the crystal becomes maximum as the polyethylene multifilament is elongated to express mechanical strength. Because of this, it can be estimated that the cutting resistance is expressed.

The cutting resistance measurement method is defined by calculating the number of repetitions when repeatedly cutting a woven or knitted fabric made of polyethylene by applying a certain load to a sharp circular blade, or using a straight blade for a woven or knitted fabric made of polyethylene It can be defined as the load to be cut, and in the present invention, for polyethylene fibers having a certain strength or more, which has a certain strength or more, crystal slippage occurs due to an external force on the fiber surface caused by the blade when cutting. It is assumed that is expressed, and it can be seen that crystallinity and crystal size have a certain relationship with the cutting resistance.

The polyethylene fiber of the present invention preferably has a crystallinity of 75% or more and a crystal size of 10 Å or more, and more preferably 80% or more and a crystal size of 12 Å or more.

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

If the melt index is less than 0.6g/10min, the flowability of the melt of the polyethylene resin in the extruder is not good, so that the spinning speed cannot be increased, and there may be a problem that acts as a cause of the nozzle face trimming during spinning. In addition, when the melt index exceeds 2.0 g/10 min, spinning workability is excellent, but flowability is not suitable at an appropriate spinning temperature, so it may be difficult to obtain high-strength polyethylene fibers after stretching.

In addition, it is preferable that the polyethylene resin used in the present invention 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.

If the weight average molecular weight (Mw) is less than 100,000, spinning workability improves during spinning, but there is a limit to expressing high strength, and if it exceeds 300,000, it affects the flowability of the resin inside the extruder during melt spinning, so that the spinning uniformity and Workability can be adversely affected.

When the molecular weight distribution index is less than 5, a high magnification of 10 times or more is required in order to exhibit high strength, and the defects of the wool or the drawing roller increase accordingly, and the quality may be degraded as the number of draw trimmings increases. In addition, when the molecular weight distribution index exceeds 10, since a large number of high molecular weight polyethylene and low molecular weight polyethylene are mixed in the polyethylene resin, a smooth stretching process cannot be achieved, and accordingly, there is a limitation in expressing high strength.

As described above, the high-strength polyethylene fiber with improved uniformity according to the present invention is manufactured including a spinning step 100, a stretching step 200, and an aging step 300 as shown in FIG. 1.

The high-strength polyethylene fiber with improved uniformity of the present invention controls the crystallinity and crystal size of the polyethylene fiber through the spinning speed in the spinning step 100 and the aging step 300 performed at a high temperature after stretching.

The spinning step 100 is a step of forming undrawn yarn by melt spinning. The polyethylene resin having the molecular weight distribution index and the melt index controlled is melted in an extruder, and a nozzle hot tube may be installed to manufacture an undrawn yarn.

In controlling the crystallinity and crystal size of the polyethylene fiber, the spinning temperature in the spinning step is preferably 230 to 290°C, and the spinning speed is preferably 120 to 160 mpm.

During the spinning, a spinning nozzle having 60 to 400 holes may be used to prepare high strength polyethylene fibers with improved uniformity of the present invention.

If the spinning speed in the spinning step is less than 120mpm, the manufacturing processability of the undrawn yarn is improved, but the stretchability is lowered in the stretching step, making it difficult to control fineness and may cause a hair or loop of the fiber.

In addition, if the spinning speed in the spinning step exceeds 160mpm, the possibility of occurrence of trimming at the nozzle face or cooling may increase, and thus fairness may be deteriorated. Therefore, the spinning speed is preferably 120 to 160mpm.

The spinning temperature and spinning speed are deeply related to the orientation of the high-strength polyethylene fiber, and in the case of a polyethylene fiber having a well-oriented fiber, fairness is advantageous during stretching.

The stretching step 200 is a step of stretching the undrawn yarn manufactured in the spinning step, and the stretching step may be performed using a multistage stretching roller, and it is preferable to stretch in two or three steps at 60 to 120°C. will be.

In the drawing step, it is preferable that the total draw ratio (DR) is 6 to 10. If the total draw ratio (DR) is lower than 6, the strength of the polyethylene fiber is lowered, and if it is higher than 10, the quality of the polyethylene fiber is severely trimmed during drawing. It can be degraded.

The aging step 300 is a step of aging (aging) the stretched polyethylene fibers by staying at 90 to 130°C.

In the aging step 300, as shown in FIG. 2, the polyethylene fibers drawn at a certain temperature may be aged using a plurality of aging rollers 330 inside the heating chamber 310.

The aging step does not use a heating roller that directly transfers heat to the roller in order to prevent defects of fibers due to the roller having a high temperature, and performs the aging step in a non-contact manner using a heating chamber as shown in FIG. Would be desirable.

When the aging step 300 is performed through the heating chamber as shown in FIG. 3, the polyethylene fibers may sag due to the aging temperature in the heating chamber maintained at a constant high temperature on the roller surface. , It would be desirable to control a certain tension in the second guide rollers 210 and 230 and the tension roller 250.

The heating chamber 310 maintains the heat received by the polyethylene fiber by controlling the ambient temperature in the chamber, not a heating roller method.

Since the high-strength polyethylene fiber of the present invention has a high crystallization rate and can form crystals in a short time and increase the crystal size, it is preferable to control the crystal aging time by the time passing through the plurality of aging rollers 330.

The aging temperature is preferably in the range of 90 to 130°C, and it is preferable to control the speed of the roller with a draw ratio of 0.98 to 1.02.

When the aging temperature is less than 90°C, the tension in the aging roller 330 increases, resulting in a phenomenon in which the fiber is cut, thereby reducing fairness. If the aging temperature exceeds 130°C, the fiber is fused to the roller surface or is uneven. As a result, the physical properties of the polyethylene fiber may be deteriorated, resulting in defects such as hair and loops.

The aging step is preferably from 5 seconds to 20 seconds. If the aging time is less than 5 seconds, the control of crystallinity and crystal size may be insignificant, and if the aging time is more than 20 seconds, the polyethylene fibers may relax and physical properties may decrease.

The high-strength polyethylene fibers that have passed through the aging step 300 may be wound through a variable guide roller 410.

The aging step improves the uniformity of the fiber cross-section by stabilizing the irregularity of the fiber cross-section caused by shrinkage and relaxation applied to the high-strength polyethylene fiber in the spinning step and the stretching step, thereby increasing the uniformity of the high-strength polyethylene fiber.

As described above, in the high-strength polyethylene fiber with improved uniformity according to the present invention, the crystallinity and crystal size are controlled through the spinning speed in the spinning step and the aging temperature in the aging step. It would be desirable to satisfy ).

Equation (1) 210≤S+T≤290

However, S is an integer of the spinning speed (mpm) of the spinning step, and T is an integer of the aging temperature (℃) of the aging step.

When the S+T is less than 210 or exceeds 290, crystallinity and crystal size may be lowered, and thus the effect of improving cutting resistance may be lowered.

As described above, the high-strength polyethylene fiber with improved uniformity according to the present invention manufactured including the spinning step 100, the stretching step 200, and the aging step 300 is continuously performed in the spinning step, the stretching step, and the aging step. It may be carried out as a one-step process, or it may be manufactured in a two-step process in which the stretching step and the aging step are successively performed after the spinning step for producing the undrawn yarn.

The high-strength polyethylene fiber with improved uniformity according to the present invention has excellent uniformity, and is easy to manufacture, weaving, and knitting a covering yarn, thereby improving the quality of the final product, and minimizing defects occurring in subsequent processes.

It is preferable that the high-strength polyethylene fiber with improved uniformity of the present invention has a cross-sectional variation (%) of 3% or less and a uniformity of U% of 4% or less.

The high-strength polyethylene fiber with improved uniformity according to the present invention prepared as described above preferably has a strength of 12 to 16 g/d. When manufactured as a fabric or knitted fabric, it is excellent in cutting resistance and has a cut index. It is possible to manufacture articles with a cut level of 7 or higher and a cutting resistance of 4N or higher.

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

Non-limiting examples include, for example, insulating materials for refrigeration units (eg, refrigerators, freezers, vending machines, etc.); Automotive parts (eg, front or rear seats, headrests, armrests, donor panels, rear shelf/package trays, steering wheel and interior trim, dashboards, etc.); Architectural panels and components (eg roof, wall cavity, underfloor, etc.); Clothing (eg, coats, shirts, pants, gloves, aprons, work clothes, shoes, boots, hats, sock liners, etc.); Furniture and bedding (eg, sleeping bags, duvets, etc.); Fluid storage/transport systems (eg, pipes or tanks of liquid/gas hydrocarbons, liquid nitrogen, oxygen, hydrogen, or crude oil); Extreme environments (eg underwater or space); Food and beverage products (eg cups, cup holders, plates, etc.); Containers and bottles; And the like.

In addition, high-strength polyethylene fibers can be used in "garment", which is generally meant to include any article having a shape that fits against a part of the body. Examples of such articles include, without limitation, clothing (e.g., shirts, pants, jeans, slacks, skirts, coats, active wear, sportswear, aerobics, and gym suits, swimwear, cycling jerseys or shorts, swimwear/bathing suits suit), lace suit, sweat suit, body suit, etc.); Footwear (eg, shoes, socks, boots, etc.); Protective clothing (e.g., firefighter coats), clothing accessories (e.g. belts, bra straps, side panels, gloves, socks, leggings, orthopedic braces, etc.), underwear (e.g., underwear, t-shirts, etc.), compression clothing, and wearing clothing (e.g., kilt sash, toga, poncho, cloak, shawl, etc.).

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

Example 1 to 9, Comparative example 1 to 4

A polyethylene resin having a melt index of 1.0 g/10min, a molecular weight distribution index of 7.0, and a weight average molecular weight of 120,000 g/mol is introduced into the extruder to extrude the molten polymer, cooled using a cooling device, and then spun using a spinning emulsion imparting device. The emulsion was attached, and the undrawn yarn to which the emulsion was attached was wound.

The undrawn yarn was stretched at a total draw ratio (DR) of 8.5 by two-stage stretching at about 70 to 90°C, and an aging step was performed on the stretched polyethylene fiber using an apparatus as shown in FIG. 3. Thereafter, a high-strength polyethylene fiber with improved uniformity according to the present invention was manufactured by winding up using a entanglement device and a winder.

In each of the Examples and Comparative Examples, the melt index, weight average molecular weight, molecular weight distribution index, spinning temperature, spinning speed, and aging temperature were the same as those of Tables 3 and 4 below, and other spinning conditions were the same.

◈ Measurement method

The strength, elongation, cut resistance index and level, cutting resistance, and fiber cross-section of Examples 1 to 9 and Comparative Examples 1 to 4 were measured.

The cutting resistance index, level, and cutting resistance were measured after preparing a knitted fabric from the polyethylene fibers of Examples 1 to 9 and Comparative Examples 1 to 4.

The cut resistance evaluation was evaluated by covering with polyethylene fibers using span yarn 140D and PET 140D for examination, and knitting the prepared covering yarn with a glove using a 13Guage L size glove knitting machine to prepare a knitted fabric.

The cutting resistance level, cutting resistance, and uniformity of U% of the examples are shown in Table 3, and the cutting resistance level, cutting resistance, and uniformity of U% of the comparative examples are shown in Table 4.

* Polyethylene raw material properties: The weight average molecular weight and molecular weight distribution were measured using high-temperature GPC, and measured using Tosoh's HLC-8331 model. The measurement solvent was TCB+0.4%BHT and the column temperature was measured at 160°C. . The sample concentration was 3mg/mol, and polystyrene was used as the standard sample, but the molecular weight of polyethylene was corrected by Mark-Houwink Equation to secure smooth data.

* Melt index measurement: measured in accordance with ASTM D1238, the measurement temperature was 190℃ and the weight was defined as 2.16kg. During the measurement, preheating was performed for 5 minutes and free running for 3 minutes, and the measured value of 10 times was defined as the average value. I did.

* Crystallinity/crystal size: Crystallinity and crystal size were measured using a D8 DISCOVER made by BRUKER.

* Strength/elongation measurement method: In accordance with ASTM D2256 standard, fiber strength and elongation were measured using an Instron universal testing machine (UTM, Universal Testing Machine) at a measurement temperature of 20℃ and 65% humidity.

* Cross-sectional average, cross-sectional deviation: Put polyethylene fiber and short black polyester fiber together in a cross-section measuring frame and cut using a cross-sectional view. The cross section of the cut fiber is enlarged 50 to 1,000 times using a Keyence Digital Microscope VHX600, and the polyethylene cross section is measured using an instrument measurement option. The cross section of the fiber was randomly measured 90 times per sample, and the average value was calculated by measuring it on 5 identical samples. The cross-sectional deviation is expressed as ±% by dividing the difference between the maximum value and the minimum value among the total number of N numbers by the average value of the cross section of the total number of N numbers by 2, and the formula is as follows.

Section average = (sum of each section size)/total N number of measurements)

Section deviation=[{(maximum value of total section-minimum value of total section)/average value of section}*100]/2

* Fiber uniformity U%: It is the uniformity of fineness, and it is defined as the degree of fluctuation of the weight with respect to the thickness of the section or the unit length of the section. The weight change per unit length is expressed as an average deviation percentage, and the formula is as follows.

U%=100 * {a/(χ * T)}

χ: average fineness

a: area between instantaneous fineness and average fineness

T: measurement time

Fiber uniformity can be measured by standardized equipment, and in the present invention, KEISOKKI's EVENNESS TESTER 80 TYPE C measuring equipment is used for the uniformity of U%.

* Cut resistance index and level: Mesdan's Glove cut tester, a device manufactured in accordance with EN388 standards, was used to evaluate the cut resistance of knitted fabrics. For the measurement, after attaching the aluminum foil wrapped with filter paper on the rubber support and placing the control sample and the test sample, before the test, the control sample and the test sample were measured and measured five times, and the index was calculated as follows.

<cut resistance index>

Sequence C
Control specimen T
Test specimen C
Control specimen I
Index 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}

[Cutability index (I) formula]

<Cutting resistance level>

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

* Cutting resistance (N): Satara's STM610 model, a device manufactured according to ISO13997 standards, was used to evaluate the cutting resistance of fabrics or knitted fabrics. When the range of force is applied to the blade perpendicular to the sample surface, the cutting force is measured by the cutting resistance required when cutting the material with a blade of 20 mm.The measurement sequence is cut within 5 seconds with a constant force applied gradually between the sample and the blade. Start and evaluate by repeating the test with different forces until at least 15 records are obtained with a cut length between 5 mm and 50 mm.

The cutting resistance is obtained in the range of 5mm to 15mm, 15mm to 30mm, and 30mm to 50mm, and the value obtained by multiplying the correction factor C by the cutting length is graphed, and the force at the cutting length of 20mm is measured as the cutting resistance.

<Cutting resistance correction factor>

C = K/l

C is correction factor, l is 5.0N neoprene cutting motion length mm, K=20

division Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Melt index
(g/10min) 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Weight average
Molecular weight (g/mol) 120,000 120,000 120,000 120,000 120,000 120,000 120,000 120,000 120,000 Molecular weight distribution
Indices 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 Radiation temperature
(℃) 290 290 290 290 290 290 290 290 290 Spinning speed
(mpm) 120 120 120 140 140 140 160 160 160 Aging temperature
(℃) 90 110 130 90 110 130 90 110 130 Crystallinity (%) 77.8 82.2 83.1 79.3 83.5 82.7 83.1 82.9 82.2 Crystal size
(Å) 10.4 12.1 12.3 10.8 12.5 12.2 12.4 12.6 11.5 Fineness (De') 400 400 400 400 400 400 400 400 400 Strength (g/d) 15.2 15.2 15 15 15.1 15.3 15.4 15.1 15 Elongation (%) 8.4 8.8 8.8 8.2 9.2 9.5 8.1 8.6 8.7 Cut Index 8.1 8.2 8.3 7.8 7.9 8.0 8.2 8.1 7.8 Cut Level 3 3 3 3 3 3 3 3 3 Cutting resistance (N) 4.2 4.6 4.8 4.2 4.2 4.2 4.6 4.4 4.3 Section average (㎛) 16.2 16.3 16.3 16.2 16.2 16.1 16.2 16.1 16.2 Sectional deviation (%) 2.6 2.5 2.5 2.5 2.4 2.3 2.3 2.2 2.2 Uniformity is also U% (%) 3.3 3.1 3.0 3.1 2.8 2.7 3.1 2.6 2.4

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Melt Index (g/10min) 1.0 1.0 1.0 1.0 Weight average molecular weight
(g/mol) 120,000 120,000 120,000 120,000 Molecular weight distribution index 7.0 7.0 7.0 7.0 Spinning temperature (℃) 290 290 290 290 Spinning speed (mpm) 160 160 120 160 Aging temperature (℃) 80 135 80 40 Crystallinity (%) 71.8 73.2 67.7 68.9 Crystal size (Å) 8.6 9.2 8.2 8.3 Fineness (De') 400 400 400 400 Strength (g/d) 15.5 14.2 14.9 15.2 Elongation (%) 7.7 10.5 7.9 7.9 Cut Index 4.6 4.9 4.8 4.8 Cut Level 2 2 2 2 Cutting resistance (N) 3.8 3.6 3.6 3.8 Section average (㎛) 16.1 16.2 16.2 16.4 Sectional deviation (%) 3.1 4.5 3.2 3.5 Uniformity is also U% (%) 4.2 5.3 4.6 4.2

As in Tables 3 and 4, in Examples 1 to 9 and Comparative Examples 1 to 4, polyethylene resins having a melt index of 1.0 g/10min, a molecular weight distribution index of 7.0, and a weight average molecular weight of 120,000 g/mol were used, Although spun at a spinning temperature of 290° C., high-strength polyethylene fibers were prepared by varying the spinning speed and aging temperature.

As shown in Tables 3 and 4, when the crystallinity and crystal size of Examples 1 to 9 and Comparative Examples 1 to 4 are increased, it can be seen that the cut index and the cutting resistance are improved.

Examples 1 to 9 are high-strength polyethylene fibers manufactured with a spinning speed of 120 to 160 mpm and an aging temperature of 90 to 130°C. It can be seen that all of them have a crystallinity of 75% or more, a crystal size of 10 Å or more, and a strength of 12 g/d or more. . In addition, it can be seen that the cut index is 7 or more, the cut level is 3, and the cutting resistance is 4N or more.

The comparative examples 1 to 4 were carried out at a spinning speed of 120 to 160 mpm, but an aging temperature of less than 90°C or more than 130°C, and a crystallinity of less than 75% and a crystal size of less than 10 Å were measured, even at the same spinning speed. It can be seen that there is a large difference in crystallinity and crystal size depending on the aging temperature.

In addition, Comparative Examples 1 to 4 had a cut index of less than 7, a cut level of 2, and a cutting resistance of less than 4N, so that physical properties were lower than those of Examples 1 to 9.

When looking at the relationship between the spinning speed (S) and the aging temperature (T), as can be seen from the results of Examples 1 to 3 in which the spinning speed is 120 mpm, when the spinning speed is low, the higher the aging temperature, the higher the crystallinity and crystal size. It can be seen that the increase in the cut index and the cutting resistance are improved, and Examples 4 to 6 with a spinning speed of 140 mpm have crystallinity, crystal size, and aging temperature of 110°C (Example 5). Examples 7 to 9, which had excellent strength and cutting resistance, and a spinning speed of 160 mpm, were excellent in crystallinity, crystal size, strength, and cutting resistance when the aging temperature was 90°C (Example 7), and the spinning speed was increased. In this case, it can be seen that an appropriate aging temperature exists.

That is, the spinning speed (S) + aging temperature (T) is preferably in the range of 210 to 290, more preferably 230 to 270.

As shown in Tables 3 and 4, the cross-sectional deviation of Examples 1 to 9 is 3% or less, and the uniformity is 3 to 4%, but Comparative Examples 1 to 4 have a cross-sectional deviation of 3% or more, and the uniformity is U%. It can be seen that the cross section of the high-strength polyethylene fiber of the present invention is very uniform as exceeding 4%.

As can be seen from the examples 1 to 9, it can be seen that the cross-sectional deviation and uniformity of U% decrease as the spinning speed increases and the aging temperature increases.

Claims (9)

delete delete In the high-strength polyethylene fiber manufacturing method with improved fairness,
A spinning step of melt spinning a polyethylene resin having a melt index of 0.6 to 2 g/10min and a molecular weight distribution index of 5 to 10 at 230 to 290°C to form undrawn yarn;
A drawing step of drawing the undrawn yarn; And,
Including the aging step of aging the stretched polyethylene fibers at 90-130°C, the crystallinity of the polyethylene fibers is 75% or more, the crystal size is 10Å or more, and the uniformity is U% or less,
High-strength polyethylene fiber production method with improved uniformity, characterized in that satisfying the following formula (1).
Equation (1) 210≤S+T≤290
However, S is an integer of the spinning speed (mpm) of the spinning step, and T is an integer of the aging temperature (℃) of the aging step. The method of claim 3,
In the spinning step, the spinning speed is 120 to 160 mpm, characterized in that the uniformity is improved high strength polyethylene fiber manufacturing method. The method of claim 3,
The aging step is a high-strength polyethylene fiber manufacturing method with improved uniformity, characterized in that aging for 5 to 20 seconds. delete An article comprising polyethylene fibers manufactured by the method of any one of claims 3 to 5. The method of claim 7,
The article according to the cut resistance standard (Level) is 3 or more, characterized in that the article. The method of claim 7,
The article is an article, characterized in that the cutting resistance is 4.0N or more.

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