Polyethylene super-coarse denier monofilament for rope and preparation method thereof

Abstract

The invention discloses a polyethylene super-coarse denier monofilament for a rope and a preparation method of the polyethylene super-coarse denier monofilament. The fineness of the monofilament ranges from 400 D to 2000 D, the strength of the monofilament is 13 cN / dtex or above, and the elongation at break ranges from 3% to 10%. The preparation method comprises the following steps: (1) raw material selection: selecting HDPE powder of which the weight-average molecular weight is 80,000-500,000, the molecular weight distribution is less than or equal to 4, and the melt index is 0.3-10.0 g / 10min under the conditions of 190 DEG C and 2.16 KG; in addition, the HDPE contains 0.1 to 5 branched chains per 1000 carbon atoms. (2) mixing the materials, namely uniformly mixing the HDPE with the antioxidant, the color master batch and the like; and (3) melt spinning: sequentially passing through a feeder 1, a single-screw extruder 2, a melt filter 3, a metering pump 4, a spinneret plate 5, a first cooling water tank 6, a second cooling water tank 7, first traction equipment 8, first heating equipment 9, second traction equipment 10, second heating equipment 11 and third traction equipment 12, and finally winding on a roller through a winding machine 13 at a winding speed of 200-800m / min. The preparation process is simple, the cost is low, and the prepared super-coarse denier monofilament is high in strength, low in elongation at break, good in wear resistance and suitable for preparing ropes.

Description

Technical Field

[0001] The invention relates to the field of polyethylene fibers for ropes, and in particular to polyethylene ultra-coarse denier monofilaments for medium- and high-strength ropes and a preparation method thereof. Background Art

[0002] At present, the fibers used for ropes mainly include polyester, nylon, polyethylene filament, polypropylene filament, etc., with a strength of 5-10cN / dtex. In addition, there are aramid, ultra-high molecular weight polyethylene fiber, etc., with a strength of 22-40cN / dtex. As for medium and high strength fibers with a strength of 10-20cN / dtex, the domestic market is blank.

[0003] Ropes made from ultra-high molecular weight polyethylene fibers are strong and have excellent performance, but for some mid-range civilian markets, they often do not require particularly high strength during use. Moreover, the high cost and pollution caused by the ultra-high molecular weight polyethylene filament spinning process are unavoidable. Ultra-high molecular weight polyethylene monofilaments are relatively thin and are easily broken and snagged during use, so ultra-high molecular weight polyethylene ropes must be coated during the preparation process before they can be used later. The strength of ordinary polyethylene coarse denier monofilaments sold on the market is below 7cN / dtex, and they need to be replaced frequently during use. In the process of preparing coarse monofilaments, there are problems with cooling difficulties and slow production speeds, and the winding speed is generally 100-150m / min.

[0004] At present, there have been many studies on modifying ultra-high molecular weight polyethylene and using screw extruders to directly melt spin it. Most of them are blended with low molecular weight polyolefins or lubricants, and the extrusion speed is slow. At the same time, these additives are not compatible with ultra-high molecular weight polyethylene, and wire breakage will occur in actual production, making it difficult to carry out large-scale production.

[0005] Some studies have also found that by adding modifiers to high-density polyethylene (HDPE) and then melt spinning, the monofilaments prepared are relatively fine, and the wear resistance is not particularly ideal when used in ropes. In addition, adding too much modifier affects the spinning continuity, strength and feel of the finished product.

[0006] Patent CN102154749A discloses a coarse denier ultra-high molecular weight polyethylene fiber yarn, which is produced by gel spinning, and has a complex process and high cost.

[0007] Patent CN115029810A discloses a high-performance polyethylene coarse-denier monofilament for wind and wave resistant fishing rope nets, with a spinneret diameter of 5-50 mm. Such a large spinneret means that the number of monofilaments produced at the same time is small. The output is low, and the diameter of the extruded raw wire is too large, making it difficult to cool evenly.

[0008] Therefore, in order to solve the above problems, it is necessary to develop a medium-high strength polyethylene ultra-thick denier monofilament that can be used for ropes with low cost and simple preparation process. Summary of the invention

[0009] In view of the shortcomings of the prior art, the present invention provides a polyethylene ultra-coarse denier monofilament for ropes and a preparation method thereof. The monofilament production process is simple and the cost is low. Compared with ordinary polyethylene ropes, the prepared ropes have greatly improved tensile and wear resistance, thereby improving the durability of ropes and are suitable for the mid-range civilian market.

[0010] The polyethylene monofilament prepared by the invention has a fineness of 400D-2000D, a strength of more than 13cN / dtex, and a breaking elongation of 3-10%.

[0011] The objective of the present invention is to achieve by the following means:

[0012] One of the technical solutions of the present invention provides a method for preparing polyethylene ultra-coarse denier monofilament for ropes, characterized in that it comprises the following steps:

[0013] (1) Raw material selection

[0014] Select HDPE powder with a weight average molecular weight of 80,000-500,000, a molecular weight distribution of less than or equal to 4, and a melt index of 0.3-10.0g / 10min at 190°C and 2.16KG. This type of polyethylene raw material has good fluidity and is easy to process, and no lubricant needs to be added. In addition, HDPE contains 0.1-5 branches per 1,000 carbon atoms. The fewer the branches, the higher the crystallinity of the polyethylene, and the higher the strength of the finished product.

[0015] (2) Material mixing

[0016] Calculated on the basis of the weight of HDPE, 0.1-1% antioxidant is added, and 0.5-5% polyethylene masterbatch is added according to the color requirements. The mixture can be directly mixed evenly by stirring in a high-speed mixer for 5-10 minutes to obtain a mixture for use.

[0017] (3) Melt spinning

[0018] The melt spinning process is: feeder → single screw extruder → melt filter → metering pump → spinneret → first cooling water tank → second cooling water tank → first traction equipment → first heating equipment → second traction equipment → second heating equipment → third traction equipment → winding machine.

[0019] Among them, the single screw extruder has an aspect ratio of 30-35 and a screw diameter of more than 65mm. The temperature of each zone is set as follows: the temperature of the screw feeding section is 150-230℃, the temperature of the melting section is 220-320℃, and the temperature of the metering section is 220-320℃.

[0020] Due to the large extrusion volume of ultra-thick denier monofilament, the metering pump is 50cc, 100cc or 150cc, the speed is 10-50r / min, and one inlet and one outlet are adopted. The spinneret temperature is 220-320℃. The spinneret hole diameter is 0.8-3mm, the aspect ratio is 6-15, and the spinneret hole gap is larger than the conventional gap to prevent the extruded original filament from sticking. The nozzle draft ratio is 5-50.

[0021] The first and second cooling water tanks are cooled by circulating water. The diameter of the extruded raw yarn is relatively thick, and it is difficult to achieve the cooling effect by air cooling. The use of circulating water cooling can not only make the raw yarn cool evenly, but also save energy. At the same time, two-stage cooling is adopted to increase the crystallization time of polyethylene and improve the crystallinity. The length of the first cooling water tank and the second cooling water tank are both 1.5-3m. By controlling the water inlet valve and the water outlet valve, the temperature of the first cooling water tank is maintained at 50-70℃, and the temperature of the second cooling water tank is 15-30℃. The spinneret is 1-5cm away from the water surface of the first cooling water tank.

[0022] The first heating device adopts water bath heating, the water tank length is 4-8m, the temperature is controlled at 90-100°C, and it is equipped with a temperature controller with an accuracy of ±1°C. The thermal conductivity of water is high, which is conducive to uniform heating of the thick monofilament and full drawing.

[0023] The second heating device uses a steam oven for heating, and hot air dries the monofilaments while heat drawing. Because the monofilaments are thicker in diameter, in order to ensure that the filaments are heated evenly at a certain pulling speed, the oven length is longer than that of a conventional oven, 8-12m, and the temperature is set at 105-115°C.

[0024] The speed ratio of the second traction device to the first traction device is 2 to 5 times, and the speed ratio of the third traction device to the second traction device is 3 to 7 times, so that the cooled raw yarn is stretched 8 to 25 times. The fully stretched single yarn has high strength and small elongation, and is more suitable for making ropes.

[0025] The winding speed is 200-800m / min. When the speed is too fast, the wire strip cannot be fully cooled, and the heating during the drawing process is uneven, which affects the strength of the final product.

[0026] The beneficial effects of the present invention are:

[0027] (1) The strength of the prepared polyethylene monofilament is above 13cN / dtex, and the elongation is 3-10%. Compared with ordinary polyethylene monofilament, the strength is improved, the elongation is reduced, the spinning and winding speed is increased, and the output is increased. The cost is much lower than that of ultra-high molecular weight polyethylene filament, and it is widely used in the civil cable market.

[0028] (2) The fineness of the prepared monofilament is 400D-2000D. The higher the monofilament fineness, the better the wear resistance of the prepared rope, and no coating is required.

[0029] (3) Direct extrusion spinning is carried out by the melt method, which has a simple process flow, low cost and no pollution.

[0030] (4) There is no need to add too much additives such as flow aids, which reduces costs and reduces the phenomenon of broken fibers during the spinning process, without affecting the strength and feel of the finished product too much. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 2 is a diagram of equipment for preparing and using an embodiment of the present invention.

[0032] In the figure, 1-feeder, 2-single screw extruder, 3-melt filter, 4-metering pump, 5-spinneret, 6-first cooling water tank, 7-second cooling water tank, 8-first traction device, 9-first heating device, 10-second traction device, 11-second heating device, 12-third traction device, 13-winding machine. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with embodiments.

[0034] Example 1

[0035] Select HDPE powder with a weight average molecular weight of 110,000, a molecular weight distribution of 2.8, a branch number of 0.5 per 1,000 carbon atoms, and a melt index of 1.0g / 10min at 190°C and 2.16KG, add 0.3% antioxidant of HDPE raw material, and mix evenly through a high-speed mixer. The mixture is melted and extruded through a single screw extruder with a diameter of 65mm and an aspect ratio of 30. The temperature of the screw feed section is 180°C, the temperature of the melting section is 260°C, the temperature of the metering section is 260°C, and the temperature of the spinneret is 260°C. The metering pump is 50cc. The spinneret hole diameter is 1.0mm, the aspect ratio is 10, the nozzle draft ratio is 45, the extruded raw yarn enters the water tank for cooling, the temperature of the first cooling water tank is 50-55℃, the temperature of the second cooling water tank is 20-25℃, the temperature of the first heating device is 95℃, the temperature of the second heating device is 110℃, the speed ratio of the second traction device to the first traction device is 3.2 times, the speed ratio of the third traction device to the second traction device is 6 times, the draft of the cooled raw yarn is 19.2 times, and the winding speed is 700m / min. The prepared single yarn has a fineness of 460D, a strength of 14.2cN / dtex, and an elongation at break of 5.3%.

[0036] Example 2

[0037] Select HDPE powder with a weight average molecular weight of 200,000, a molecular weight distribution of 2.5, 2 branches per 1,000 carbon atoms, and a melt index of 0.6g / 10min at 190°C and 2.16KG, add 0.3% antioxidant of HDPE raw material, and mix evenly through a high-speed mixer. The mixture is melted and extruded through a single screw extruder with a diameter of 65mm and an aspect ratio of 30. The temperature of the screw feed section is 180°C, the temperature of the melting section is 280°C, the temperature of the metering section is 280°C, and the temperature of the spinneret is 280°C. The metering pump is 50cc. The spinneret hole diameter is 1.0mm, the aspect ratio is 10, the nozzle draft ratio is 45, the extruded raw yarn enters the water tank for cooling, the temperature of the first cooling water tank is 50-55℃, the temperature of the second cooling water tank is 20-25℃, the temperature of the first heating device is 95℃, the temperature of the second heating device is 110℃, the speed ratio of the second traction device to the first traction device is 3.5 times, the speed ratio of the third traction device to the second traction device is 6 times, the draft of the cooled raw yarn is 21 times, and the winding speed is 600m / min. The prepared single yarn has a fineness of 460D, a strength of 14.9cN / dtex, and an elongation at break of 5.0%.

[0038] Example 3

[0039] Select HDPE powder with a weight average molecular weight of 110,000, a molecular weight distribution of 2.8, a branch number of 0.5 per 1,000 carbon atoms, and a melt index of 1.0g / 10min at 190°C and 2.16KG, add 0.3% antioxidant of HDPE raw material, and mix evenly through a high-speed mixer. The mixture is melted and extruded through a single screw extruder with a diameter of 65mm and an aspect ratio of 30. The temperature of the screw feed section is 180°C, the temperature of the melting section is 270°C, the temperature of the metering section is 270°C, and the temperature of the spinneret is 270°C. The metering pump is 50cc. The spinneret hole diameter is 1.5mm, the aspect ratio is 10, the nozzle draft ratio is 32, the extruded raw yarn enters the water tank for cooling, the temperature of the first cooling water tank is 50-55℃, the temperature of the second cooling water tank is 20-25℃, the temperature of the first heating device is 98℃, the temperature of the second heating device is 110℃, the speed ratio of the second traction device to the first traction device is 3.5 times, the speed ratio of the third traction device to the second traction device is 6.1 times, the draft of the cooled raw yarn is 21.4 times, and the winding speed is 550m / min. The prepared single yarn has a fineness of 850D, a strength of 14.0cN / dtex, and an elongation at break of 4.9%.

[0040] Example 4

[0041] HDPE powder with a weight average molecular weight of 110,000, a molecular weight distribution of 2.8, a branch number of 0.5 per 1,000 carbon atoms, and a melt index of 0.9 g / 10 min at 190°C and 2.16 kg was selected, and an antioxidant of 0.3% of the HDPE raw material was added, and mixed evenly by a high-speed mixer. The mixture was melted and extruded by a single screw extruder with a diameter of 80 mm and an aspect ratio of 30. The temperature of the screw feed section was 220°C, the temperature of the melting section was 280°C, and the temperature of the metering section was 280°C. The metering pump was 100cc. The spinneret temperature was 280°C. The spinneret hole diameter is 2.0mm, the aspect ratio is 12, the nozzle draft ratio is 25, the extruded raw yarn enters the water tank for cooling, the temperature of the first cooling water tank is 55-60℃, the temperature of the second cooling water tank is 15-20℃, the temperature of the first heating device is 100℃, the temperature of the second heating device is 115℃, the speed ratio of the second traction device to the first traction device is 4.2 times, the speed ratio of the third traction device to the second traction device is 4.8 times, the draft of the cooled raw yarn is 20.2 times, and the winding speed is 450m / min. The prepared monofilament fineness is 1200D, the strength is 13.8cN / dtex, and the elongation at break is 5.3%.

[0042] Comparative Example 1

[0043] HDPE pellets with a weight average molecular weight of 100,000, a molecular weight distribution of 4.5, 5 branches per 1,000 carbon atoms, and a melt index of 1.0 g / 10 min at 190°C and 2.16 kg were selected, and 0.3% antioxidant of HDPE raw material was added, and mixed evenly by a high-speed mixer. The mixture was melted and extruded by a single screw extruder with a diameter of 65 mm and an aspect ratio of 30. The temperature of the screw feed section was 180°C, the temperature of the melting section was 260°C, the temperature of the metering section was 260°C, and the temperature of the spinneret was 260°C. The metering pump was 50cc. The spinneret hole diameter is 1.0mm, the aspect ratio is 10, the nozzle draft ratio is 45, the extruded raw yarn enters the water tank for cooling, the temperature of the first cooling water tank is 50-55℃, the temperature of the second cooling water tank is 20-25℃, the temperature of the first heating device is 95℃, the temperature of the second heating device is 110℃, the speed ratio of the second traction device to the first traction device is 3 times, the speed ratio of the third traction device to the second traction device is 4.2 times, the draft of the cooled raw yarn is 12.6 times, and the winding speed is 550m / min. The prepared monofilament has a fineness of 450D, a strength of 7.5cN / dtex, and an elongation at break of 6.3%.

[0044] Comparative Example 2

[0045] HDPE pellets with a weight average molecular weight of 100,000, a molecular weight distribution of 4.5, 5 branches per 1,000 carbon atoms, and a melt index of 1.0 g / 10 min at 190°C and 2.16 kg were selected, and 0.3% antioxidant of HDPE raw material was added, and mixed evenly by a high-speed mixer. The mixture was melted and extruded by a single screw extruder with a diameter of 65 mm and an aspect ratio of 30. The temperature of the screw feed section was 180°C, the temperature of the melting section was 260°C, the temperature of the metering section was 260°C, and the temperature of the spinneret was 260°C. The metering pump was 50cc. The spinneret hole diameter is 0.6mm, the aspect ratio is 10, the nozzle draft ratio is 45, the extruded raw yarn enters the water tank for cooling, the temperature of the first cooling water tank is 50-55℃, the temperature of the second cooling water tank is 20-25℃, the temperature of the first heating device is 95℃, the temperature of the second heating device is 110℃, the speed ratio of the second traction device to the first traction device is 3 times, the speed ratio of the third traction device to the second traction device is 4 times, the draft of the cooled raw yarn is 12 times, and the winding speed is 600m / min. The prepared single yarn has a fineness of 50D, a strength of 7.8cN / dtex, and an elongation at break of 5.2%.

[0046] Comparative Example 3

[0047] Select HDPE pellets with a weight average molecular weight of 100,000, a molecular weight distribution of 4.5, 5 branches per 1,000 carbon atoms, and a melt index of 1.0g / 10min at 190°C and 2.16KG, add 0.3% antioxidant of HDPE raw material, and mix evenly through a high-speed mixer. The mixture is melted and extruded through a single screw extruder with a diameter of 65mm and an aspect ratio of 30. The temperature of the screw feed section is 180°C, the temperature of the melting section is 260°C, the temperature of the metering section is 260°C, and the temperature of the spinneret is 260°C. The metering pump is 50cc. The diameter of the spinneret hole is 0.8mm, the aspect ratio is 10, and the nozzle draft ratio is 45. The extruded raw silk is cooled only by a water tank, and the water tank temperature is 20-25°C. Then it passes through the first traction device and the second traction device. The speed ratio of the second traction device to the first traction device is 8.5. The steam oven is used for heating in the middle, the temperature is 100°C, the oven length is 4m, and the winding speed is 130m / min. The prepared monofilament has a fineness of 200D, a strength of 6.5 cN / dtex, and an elongation at break of 9.8%.

[0048] Comparative Example 4

[0049] Select HDPE pellets with a weight average molecular weight of 100,000, a molecular weight distribution of 4.5, 5 branches per 1,000 carbon atoms, and a melt index of 1.0g / 10min at 190°C and 2.16KG, add 0.3% antioxidant of HDPE raw material, and mix evenly through a high-speed mixer. The mixture is melted and extruded through a single screw extruder with a diameter of 80mm and an aspect ratio of 30. The temperature of the screw feed section is 180°C, the temperature of the melting section is 260°C, the temperature of the metering section is 260°C, and the temperature of the spinneret is 260°C. The metering pump is 100cc. The diameter of the spinneret hole is 2.0mm, the aspect ratio is 12, and the nozzle draft ratio is 25. The extruded raw silk is cooled only by a water tank, and the water tank temperature is 20-25°C. Then it passes through the first traction device and the second traction device. The speed ratio of the second traction device to the first traction device is 8.5. The oven is used for heating in the middle, the temperature is 100°C, the oven length is 4m, and the winding speed is 50m / min. The prepared monofilament has a fineness of 1200D, a strength of 5.3 cN / dtex, and an elongation at break of 11.2%.

[0050] Test Case

[0051] The monofilaments prepared in Example 1, Example 4, Comparative Example 1, Comparative Example 2, and Comparative Example 4 were respectively used, and the same process parameters were used to prepare three-strand ropes of 6 mm in size. The corresponding ropes were numbered 1, 2, 3, 4, and 5, respectively, and then strength and wear resistance tests were carried out. The strength test was carried out with reference to the standard "GB / T8834-2016 Determination of Physical and Mechanical Properties of Fiber Ropes". The wear resistance test was carried out with reference to the standard "FZ / T 60049-2022 Determination of Wear Resistance of Fiber Ropes - Drum Friction Method". The experimental tension was set to 10KG, the operating speed was 30r / min, and the number of revolutions was 12,000. The wear resistance test results are expressed by the rope strength retention rate, and the rope strength retention rate calculation formula is as follows:

[0052] Strength retention rate = (strength of rope after 12,000 turns test / strength before wear test) × 100%

[0053] The higher the result, the better the wear resistance of the rope. The test results are shown in Table 1.

[0054] Table 1 Test results of strength and wear resistance of prepared ropes serial number Monofilament strength Monofilament fineness Rope strength Rope strength retention rate 1 14.2cN / dtex 460D 13.7KN 50％ 2 13.8cN / dtex 1200 D 13.1KN 66％ 3 7.5cN / dtex 450D 7.3KN 49％ 4 7.8cN / dtex 50D 7.5KN 41％ 5 5.3cN / dtex 1200D 5.2KN 60％

[0055] It can be seen from Table 1 that the rope made of polyethylene monofilament prepared in the present invention has greatly improved strength and wear resistance compared with ordinary polyethylene ropes.

Claims

1. A polyethylene ultra-thick denier monofilament for ropes, characterized in that The single yarn fineness is 400D-2000D, the strength is above 13cN / dtex, and the elongation is 3-10%.

2. A method for preparing polyethylene ultra-coarse denier monofilament for ropes, characterized in that: The following steps are involved: (1) Raw material selection HDPE powder with a weight average molecular weight of 80,000-500,000, a molecular weight distribution of less than or equal to 4, and a melt index of 0.3-10.0 g / 10 min at 190°C and 2.16 kg is selected. In addition, HDPE contains 0.1-5 branches per 1,000 carbon atoms. (2) Material mixing Calculated on the basis of the weight of HDPE, 0.1-1% antioxidant is added, and 0.5-5% polyethylene masterbatch is added according to the color requirements. The mixture can be directly mixed evenly by stirring in a high-speed mixer for 5-10 minutes to obtain a mixture for use. (3) Melt spinning The melt spinning process flow is: feeder 1→single screw extruder 2→melt filter 3→metering pump 4→spinneret 5→first cooling water tank 6→second cooling water tank 7→first traction device 8→first heating device 9→second traction device 10→second heating device 11→third traction device 12→winding machine 13.

3. The method for preparing a polyethylene ultra-coarse denier monofilament for rope according to claim 2, characterized in that: The single screw extruder in step 3 has an aspect ratio of 30-35 and a screw diameter of more than 65 mm. The temperature settings of each area of ​​the screw are: the feeding section temperature is 150-230°C, the melting section temperature is 220-320°C, and the metering section temperature is 220-320°C.

4. The method for preparing a polyethylene ultra-coarse denier monofilament for rope according to claim 2, characterized in that: In step 3, the metering pump is 50cc, 100cc or 150cc, the speed is 10-50r / min, and one inlet and one outlet are adopted. The spinneret temperature is 220-320°C, the spinneret hole diameter is 0.8-3mm, the aspect ratio is 6-15, and the nozzle draft ratio is 5-50.

5. The method for preparing a polyethylene ultra-thick denier monofilament for rope according to claim 2, characterized in that: In step 3, cooling is performed in two stages, and circulating water is controlled to make the temperature of the first cooling water tank 50-70°C, the length of the water tank 1.5-3m, the temperature of the second cooling water tank 15-30°C, the length of the water tank 1.5-3m. The spinneret is 1-5cm away from the water surface of the first cooling water tank.

6. The method for preparing a polyethylene ultra-coarse denier monofilament for rope according to claim 2, characterized in that: In the step 3, the first heating device adopts water bath heating, the water tank is 4-8m long, and is equipped with a temperature controller with an accuracy of ±1°C and a temperature control of 90-100°C.

7. The method for preparing a polyethylene ultra-coarse denier monofilament for rope according to claim 2, characterized in that: In the step 3, the second heating device adopts a steam oven for heating, the oven length is 8-12m, and the temperature is set at 105-115°C.

8. The method for preparing polyethylene ultra-coarse denier monofilament for rope according to claim 2, characterized in that: In the step 3, the speed ratio of the second traction device to the first traction device is 2 to 5 times, and the speed ratio of the third traction device to the second traction device is 3 to 7 times, so that the cooled raw silk is stretched 8 to 25 times.

9. The method for preparing polyethylene ultra-coarse denier monofilament for rope according to claim 2, characterized in that: In the step 3, the winding speed of the winding machine is 200-800m / min.

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