CN102505158A - High-concentration preparation method for ultra-high molecular weight polyethylene fiber - Google Patents

Abstract

The invention relates to a high-concentration preparation method of ultra-high molecular weight polyethylene fibers. Existing methods are difficult to prepare high-concentration spinning solutions. In the method of the present invention, firstly, the ultra-high molecular weight polyethylene resin is uniformly mixed with an antioxidant and a solvent to swell to obtain a swelling liquid; High-molecular-weight polyethylene spinning solution; then the jelly-like ultra-high molecular weight polyethylene spinning solution is spun through a metering pump and a spinneret, and shaped in a water bath to obtain a jelly-like yarn; finally, the dried jelly-like yarn 2-4 stages of ultra-heated drawing are carried out to obtain ultra-high molecular weight polyethylene fibers. The invention increases the concentration of ultra-high molecular weight polyethylene spinning liquid, obtains ultra-high molecular weight polyethylene fibers with high strength and high modulus, and greatly improves production efficiency.

Description

A high-concentration preparation method of ultra-high molecular weight polyethylene fiber

technical field

The invention belongs to the technical field of polymer materials and relates to a high-concentration preparation method of ultra-high molecular weight polyethylene (UHMWPE) fibers.

Background technique

Ultra-high molecular weight polyethylene fiber is a high-strength and high-modulus fiber that was successfully developed in the late 1970s and industrialized in the early 1980s. Ultra-high molecular weight polyethylene fiber, carbon fiber and aramid fiber are called the three high-performance fibers. Due to the ultra-high molecular weight polyethylene fiber has multiple excellent properties such as ultra-light, high specific strength, high specific modulus, superior energy absorption, good wear resistance, corrosion resistance, and light resistance, it has been used in aerospace, national defense, military, security, etc. It has been widely used in protection, marine engineering, sports equipment, power communication, medical materials and civil rope nets.

UHMWPE fibers are usually prepared by gel spinning process. The jelly spinning process is to make a spinning solution from ultra-high molecular weight polyethylene and a suitable solvent, then extrude it to form a jelly yarn, then extract and dry the solvent in the jelly yarn, and finally undergo super-heating Drawing to obtain ultra-high molecular weight polyethylene fibers.

The key technology of the existing ultra-high molecular weight polyethylene fiber jelly spinning process is to prepare a fully dissolved uniform solution, so as to obtain the spinnability of the resin. However, due to its ultra-high molecular weight, the viscosity of all resin raw materials is very large when they are dissolved at the same time. It needs to be dissolved at high temperature with a high-boiling point solvent. The conditions for preparing a uniform and completely dissolved solution are harsh, so it is difficult to prepare a high-concentration spinning solution; and because The dissolution temperature required by the resin is very high, and the molecular weight of ultra-high molecular weight polyethylene is greatly reduced, which affects the performance of the final fiber. The only way to improve the dissolution conditions and fiber performance is to further reduce the concentration. Due to the above reasons, the concentration of the spinning solution in the existing gel spinning process can only reach about 10%, the production efficiency of the single machine is low, the energy consumption is large, and the manufacturing cost is high, which greatly limits the use of UHMWPE fiber in high-strength cables and cables with huge demand. Popularization and application of industrial cloth, fishing nets, safety nets and other civilian fields. The analysis of ultra-high molecular weight polyethylene resin shows that the resin contains amorphous parts, folded chain lamellar crystals and extended chain crystals. It is usually 148-150°C. There is a big difference in the melting points of the two crystals, and since the extended chain crystals have a larger ordered size than the folded chain lamellar crystals, the dissolution of the extended chain crystals is much more difficult than that of the folded chain lamellar crystals. There are many, and the extended chain crystals oriented along the fiber axis are just the key to the structure of ultra-high molecular weight polyethylene fibers to obtain high strength and high modulus. Therefore, if the extended chain crystals in the resin are not dissolved during the preparation of the UHMWPE spinning solution, its high rigidity can be used to form a liquid crystal solution, which can greatly reduce the UHMWPE spinning solution. Increase the viscosity of the silk solution, improve its fluidity, and reduce the large decrease in molecular weight caused by the high temperature of spinning solution preparation. The jelly filaments containing extended chain crystals prepared by this method can be called jelly-like fibers. In order to arrange the extended chain crystals of UHMWPE maintained in the spinning solution preparation process along the axial direction of the fiber, the jelly-like fiber is formed by using a nozzle to draw, and after passing through a cold water bath, it is directly extracted and dried. The stretched chain crystals are arranged axially along the jelly filament under the action of the stretching field drawn by the nozzle and the orientation is fixed. In order to obtain a stable stretching field, a spinneret with a hyperboloid guide hole is preferred to make the jelly solution continuous. It enters the spinneret hole smoothly to ensure the continuous stability of the stretching field. Using the above method, breaking through the current technical bottleneck that can only obtain resin spinnability at a narrow solution concentration, a new high-concentration UHMWPE fiber preparation process has been developed, and increasing the spinning solution concentration in the UHMWPE fiber preparation process is the key to reducing UHMWPE fiber. It is an important way to reduce production and application costs, increase production capacity, and realize energy saving, emission reduction, environmental protection and low carbon in the fiber preparation process.

Contents of the invention

The object of the present invention is to provide a high-concentration spinning method for preparing ultra-high-molecular-weight polyethylene fibers with high production efficiency and good product quality in view of the deficiencies in the prior art.

The concrete steps of the inventive method are:

Step (1). Mix the antioxidant and the ultra-high molecular weight polyethylene resin with a molecular weight greater than 8×10 ⁵ at a mass ratio of 0.1 to 1:100, and stir and mix evenly with the solvent at room temperature in an emulsifier, and the ultra-high molecular weight per kilogram Add 1.5 to 5.67 kg of solvent to the polyethylene resin, then put it into a swelling kettle and stir to swell to obtain a swelling liquid with a swelling temperature of 70 to 110°C and a swelling time of 30 to 180 minutes;

The solvent is one or more of decahydronaphthalene, tetralin, paraffin oil, kerosene and white oil.

Step (2). The swelling liquid is transported into a storage tank, cooled to 30-60° C., and then sent into a twin-screw extruder, and extruded to obtain a high-concentration jelly-like ultra-high molecular weight polyethylene spinning solution. This step is to use the characteristics of the large difference in melting point between the folded chain lamellar crystals and the extended chain crystals in the UHMWPE resin, and prepare the resin by dissolving the folded chain lamellar crystals in the UHMWPE resin while retaining the extended chain crystals. A jelly-like ultra-high molecular weight polyethylene spinning solution with partially dissolved crystals.

The inlet temperature of the twin-screw extruder is 80-130°C, the temperature of the middle extrusion dissolving section is 130-180°C, the outlet temperature is 160-180°C, and the rotation speed of the twin-screw extruder is 30-400r /min.

Step (3). The jelly-like ultra-high molecular weight polyethylene spinning solution is spun through a metering pump and a spinneret, and shaped in a water bath to obtain a jelly-like yarn. The vertical distance between the spinneret and the water surface of the tank is 1 ~8 cm; during the spinning process, a draft of 1.5 to 6 times is applied between the spinneret and the water surface of the tank, so that the stretched chain crystals are arranged axially along the gel filament under the action of the stretching field; the gel-like filament passes through Extract and dry directly after the water bath, so that the orientation and arrangement of the extended chain crystals along the fiber axis are fixed. The extraction temperature is 20-60°C, and the drying temperature is 20-60°C;

The guide hole of the spinneret is semi-hyperboloid, the minimum aperture is 0.5-1.5 mm, the aspect ratio is 2-20, and the exit angle is 0.5-2°; it can also be cylindrical or conical, and the minimum aperture is 0.5 to 1.5 mm, and an aspect ratio of 2 to 20.

Step (4). The dried jelly-like silk is subjected to 2 to 4 stages of super-double thermal drawing to obtain ultra-high molecular weight polyethylene fibers. The temperature of thermal drawing is 80-150 ° C, and the total multiple of thermal drawing is 10 to 60 times.

The present invention adopts the method of dissolving folded chain lamellar crystals and retaining straight chain lamellar crystals during the preparation process of ultra-high molecular weight polyethylene spinning liquid, and maintaining the straight chain lamellar crystals during the preparation process of ultra-high molecular weight polyethylene fibers. The new high-concentration spinning process route (usually the jelly fiber prepared by the jelly spinning process with fully dissolved crystals has no orientation in the fiber after extraction and drying, while the jelly fiber prepared by the high-concentration new spinning process has no orientation after extraction and drying. The fiber axis orientation is higher, and its crystallinity is increased from 30% to 48% of the usual jelly fiber, indicating that there are a large number of extended chain crystals arranged along the fiber axis in the jelly fiber prepared by the high-concentration spinning process) , increased the concentration of ultra-high molecular weight polyethylene spinning solution (20-40%), and obtained ultra-high molecular weight polyethylene fibers with high strength (above 28cN/dtex) and high modulus (above 1000cN/dtex), which greatly improved Productivity.

Detailed ways

Embodiments of the invention are further described below through examples, but the scope of the present invention is not limited to these examples, and these examples given are only illustrative and cannot be construed as limitations of the present invention. Some non-essential improvements and adjustments made by ordinary professionals in the field according to the content of the invention still belong to the protection scope of the present invention.

The molecular weight of the ultra-high molecular weight polyethylene resin in the following examples is greater than 8×10 ⁵ , and the antioxidant used is a conventional antioxidant in the ultra-high molecular weight polyethylene gel spinning process, such as 2,6-di-tert-butyl- 4-methylphenol, 3-(3,5-di-tert-butyl-4-hydroxybenzene) octadecyl propionate, tris(dodecyl) phosphite, tris(octadecyl) phosphite ) ester, tri(dodecyl) trithiophosphite, tris(2,4-dimethylphenyl) phosphite or tris(2,4-di-tert-butylphenyl) phosphite.

Example 1

Stir 10kg of ultra-high molecular weight polyethylene resin, 40kg of decahydronaphthalene and 10g of antioxidant in an emulsifier at room temperature, then put it into a swelling kettle, heat it to 70°C, stir and swell for 180 minutes, and transport the suspension to Storage tank, the suspension is cooled to 30°C in the storage tank and then sent to a twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 80°C, the temperature of the middle extruding and dissolving section is 130°C, the outlet temperature is 160°C, and the rotation speed of the twin-screw extruder is 30r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 20%. After this type of jelly solution is passed through a metering pump and a spinneret, it is shaped in a water bath to obtain a jelly-like fiber, wherein the guide hole of the spinneret is cylindrical, the hole diameter is 1 mm, and the aspect ratio is 10. The spinneret and the water tank The vertical distance between the water surfaces was 1 cm, and a nozzle draft of 1.5 times was applied. The jelly-like filaments are directly extracted and dried after passing through a water bath. The extraction temperature is 20°C and the drying temperature is 20°C. The dried jelly fiber is subjected to two-stage hot drawing, wherein, the first-stage hot drawing temperature is 80° C., the draw ratio is 4 times, and the second stage hot drawing temperature is 120° C., and the draw ratio is 2.5 times. Ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1.

Example 2

Stir 10kg ultra-high molecular weight polyethylene resin, 15kg tetralin, and 20g antioxidant in an emulsifier at room temperature, then put it into a swelling kettle, heat to 80°C, stir and swell for 150 minutes, and transport the suspension to Storage tank, the suspension is cooled to 40°C in the storage tank and then sent to a twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 90°C, the temperature of the middle extruding and dissolving section is 140°C, the outlet temperature is 160°C, and the rotation speed of the twin-screw extruder is 60r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 20%. After this type of jelly solution is passed through a metering pump and a spinneret, it is shaped in a water bath to obtain a jelly-like fiber, wherein the guide hole of the spinneret is conical, the minimum hole diameter is 0.5mm, and the aspect ratio is 20. The vertical distance between it and the water surface of the tank is 2 cm, and the nozzle draft is applied twice. The jelly-like filaments are directly extracted and dried after passing through a water bath. The extraction temperature is 30°C and the drying temperature is 30°C. The dried jelly fiber is subjected to three-stage hot drawing, wherein, the first-stage hot drawing temperature is 80° C., the draw ratio is 4 times, and the second stage hot drawing temperature is 120° C., and the draw ratio is 2.5 times. The temperature of the three-stage hot drawing is 150°C, and the drawing ratio is 1.8 times, and ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1.

Example 3

Stir 10kg ultra-high molecular weight polyethylene resin, 20kg paraffin oil, and 30g antioxidant in an emulsifier at room temperature, then put it into a swelling kettle, heat it to 90°C, stir and swell for 120 minutes, and transport the suspension to the storage tank through a pipeline. The suspension is cooled to 40°C in the storage tank and then sent to a twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 100°C, the temperature of the middle extruding and dissolving section is 150°C, the outlet temperature is 170°C, and the rotation speed of the twin-screw extruder is 90r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 25%. After this type of jelly solution passes through the metering pump and spinneret, it is shaped in a water bath to obtain jelly-like fibers, wherein the guide hole of the spinneret is conical, the minimum hole diameter is 1.5mm, and the aspect ratio is 2. The vertical distance between it and the water surface of the tank is 3 cm, and the nozzle draft is applied 3 times. The jelly-like filaments are directly extracted and dried after being passed through a water bath, wherein the extraction temperature is 40°C and the drying temperature is 40°C. The dried jelly fiber is subjected to three-stage hot drawing, wherein the first-stage hot drawing temperature is 90° C., the draw ratio is 4 times, the second stage hot drawing temperature is 130° C., and the draw ratio is 3 times. The temperature of the three-stage hot drawing is 150°C, and the drawing ratio is 1.8 times, and ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1.

Example 4

Stir 10kg ultra-high molecular weight polyethylene resin, 30kg kerosene, and 40g antioxidant in the emulsifier at room temperature, then put it into the swelling kettle, heat it to 100°C, stir and swell for 60 minutes, and transport the suspension to the storage material through the pipeline The suspension is cooled to 45°C in the storage tank and then sent to the twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 110°C, the temperature of the middle extruding and dissolving section is 160°C, the outlet temperature is 170°C, and the rotation speed of the twin-screw extruder is 120r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 30%. After this type of jelly solution is passed through a metering pump and a spinneret, it is shaped in a water bath to obtain a jelly-like fiber, wherein the spinneret guide hole is conical, the minimum aperture is 1 mm, and the aspect ratio is 5. The spinneret and The vertical distance between the tank water surfaces was 4 cm, and 4 times the nozzle draft was applied. The jelly-like filaments are directly extracted and dried after being passed through a water bath, wherein the extraction temperature is 50°C and the drying temperature is 50°C. The dried jelly fiber is subjected to three-stage hot drawing, wherein, the first-stage hot drawing temperature is 100° C., and the draw ratio is 5 times, and the second-stage hot drawing temperature is 130° C., and the draw ratio is 3 times. The temperature of the three-stage hot drawing is 150°C, and the drawing ratio is 1.8 times, and ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1.

Example 5

Stir 10kg ultra-high molecular weight polyethylene resin, 56.7kg white oil, and 100g antioxidant in an emulsifier at room temperature, then put it into a swelling kettle, heat to 100°C, stir and swell for 60 minutes, and transport the suspension to Storage tank, the suspension is cooled to 50°C in the storage tank and then sent to a twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 120°C, the temperature of the middle extruding and dissolving section is 170°C, the outlet temperature is 170°C, and the rotation speed of the twin-screw extruder is 150r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 35%. After this type of jelly solution is passed through a metering pump and a spinneret, it is shaped in a water bath to obtain a jelly-like fiber, wherein the guide hole of the spinneret is a semi-hyperbolic shape, the minimum hole diameter is 0.5mm, the aspect ratio is 20, and the exit angle is 1o, the vertical distance between the spinneret and the water surface of the tank is 5 cm, and the draft of the nozzle is 5 times. The jelly-like silk is directly extracted and dried after being passed through a water bath, wherein the extraction temperature is 60°C and the drying temperature is 60°C. The dried jelly fiber is subjected to three-stage hot drawing, wherein, the first-stage hot drawing temperature is 110° C., and the draw ratio is 6 times, and the second-stage hot drawing temperature is 130° C., and the draw ratio is 3 times. The temperature of the three-stage hot drawing is 150°C, and the drawing ratio is 1.8 times, and ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1.

Example 6

Stir 10kg ultra-high molecular weight polyethylene resin, 25kg decahydronaphthalene, 25kg tetralin, and 80g antioxidant in an emulsifier at room temperature, then put it into a swelling kettle, heat to 110°C, stir and swell for 30 minutes, and dissolve the suspension It is transported to the storage tank through pipelines, and the suspension is cooled to 60°C in the storage tank, and then sent to a twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 130°C, the temperature of the middle extruding and dissolving section is 180°C, the outlet temperature is 180°C, and the rotation speed of the twin-screw extruder is 200r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 35%. After this type of jelly solution is passed through the metering pump and spinneret, it is shaped in a water bath to obtain jelly-like fibers, wherein the guide hole of the spinneret is semi-hyperbolic, the minimum aperture is 1mm, the aspect ratio is 10, and the outlet angle is 0.5o, the vertical distance between the spinneret and the water surface of the flume is 6 cm, and the nozzle draft is applied 5 times. The jelly-like fibers are directly extracted and dried after passing through a water bath, wherein the extraction temperature is 40°C and the drying temperature is 60°C. The dried jelly fiber is subjected to three-stage hot drawing, wherein, the first-stage hot drawing temperature is 120° C., the draw ratio is 7 times, and the second stage hot drawing temperature is 135° C., and the draw ratio is 3.4 times. The temperature of the three-stage hot drawing is 150°C, and the drawing ratio is 1.8 times, and ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1. .

Example 7

Stir 10kg ultra-high molecular weight polyethylene resin, 15kg white oil, 15kg paraffin oil, 15kg kerosene, and 60g antioxidant in an emulsifier at room temperature, then put it into a swelling kettle, heat to 110°C, stir and swell for 90 minutes, and suspend The liquid is transported to the storage tank through the pipeline, and the suspension is cooled to 60°C in the storage tank, and then sent to the twin-screw extruder for extrusion and dissolution. Wherein, the inlet temperature of the twin-screw extruder is 130°C, the temperature of the middle extruding and dissolving section is 180°C, the outlet temperature is 180°C, and the rotation speed of the twin-screw extruder is 400r/min. The suspension was dissolved by twin-screw extrusion to prepare a uniform ultra-high molecular weight polyethylene jelly solution with a concentration of 40%. After this type of jelly solution is passed through the metering pump and spinneret, it is shaped in a water bath to obtain jelly-like fibers, wherein the guide hole of the spinneret is semi-hyperbolic, the minimum hole diameter is 1.5mm, the aspect ratio is 2, and the exit angle The vertical distance between the spinneret and the water surface of the tank is 8 cm, and the draft of the nozzle is 6 times. The jelly-like fibers are directly extracted and dried after passing through a water bath, wherein the extraction temperature is 50°C and the drying temperature is 60°C. The dried jelly fiber is subjected to four-stage hot drawing, wherein, the first-stage hot drawing temperature is 90° C., the draw ratio is 4 times, the second-stage hot drawing temperature is 120° C., and the draw ratio is 3 times. The third-stage hot drawing temperature is 135°C, and the draw ratio is 2.5 times. The third-stage hot drawing temperature is 150°C, and the draw ratio is 2 times. Ultra-high molecular weight polyethylene fibers are obtained after hot drawing.

The mechanical properties of the fiber samples were tested, and the results are listed in Table 1.

Table 1, ultra-high molecular weight polyethylene fiber embodiment performance comparison table

the concentration(%) The total multiple of hot draft Denier (dtex) Strength (cN/dtex) Modulus (cN/dtex) Elongation(%) Example 1 20 10.0 5.0 28.1 1023 5.0 Example 2 20 18.0 4.5 28.9 1086 4.6 Example 3 25 21.6 4.2 29.2 1123 4.4 Example 4 30 27.0 3.6 29.7 1176 4.1 Example 5 35 32.4 4.0 30.5 1210 3.6 Example 6 35 42.8 4.0 31.2 1244 3.2 Example 7 40 60.0 2.2 33.7 1325 2.4

Claims (5)

1. the high concentration preparation method of a superhigh molecular weight polyethylene fibers is characterized in that the concrete steps of this method are:

Step (1). with antioxidant and molecular weight greater than 8 * 10 ⁵Polyvinyl resin with super-high molecular weight press mass ratio 0.1～1:100 and mix; Mix with solvent stirring at normal temperature in mulser; Every kilogram of polyvinyl resin with super-high molecular weight adds 1.5～5.67 kilograms of solvents; Put into the swelling still then and stir swelling, obtain swelling solution, swelling temperature is that 70～110 ℃, swelling time are 30～180 minutes;

Step (2). swelling solution is delivered in the material storage kettle, is cooled to 30～60 ℃, send into double screw extruder then, extrude the class frozen glue ultra-high molecular weight polyethylene spinning solution that obtains high concentration;

Step (3). with class frozen glue ultra-high molecular weight polyethylene spinning solution process measuring pump and spinnerets spinning, typing type of obtaining gel fiber in water-bath, the vertical range between the spinnerets and the tank water surface is 1～8 centimetre; In the spinning process, apply 1.5～6 times drawing-off between the spinnerets and the tank water surface; Type gel fiber directly extracts through after the water-bath, drying, and extraction temperature is that 20～60 ℃, baking temperature are 20～60 ℃;

Step (4). dried type gel fiber is carried out 2～4 grades of ultra doubly hot drawing-offs, obtain superhigh molecular weight polyethylene fibers, the temperature of hot drawing-off is that 80～150 ℃, the general times of hot drawing-off are 10～60 times.

2. the high concentration preparation method of a kind of superhigh molecular weight polyethylene fibers as claimed in claim 1 is characterized in that the solvent described in the step (1) is one or more in decahydronaphthalenes, tetrahydronaphthalene, paraffin oil, kerosene, the white oil.

3. the high concentration preparation method of a kind of superhigh molecular weight polyethylene fibers as claimed in claim 1; The inlet temperature that it is characterized in that the double screw extruder described in the step (2) is that 80～130 ℃, the temperature of middle extruding lysing segment are that 130～180 ℃, outlet temperature are 160～180 ℃, and the slewing rate of double screw extruder is 30～400r/min.

4. the high concentration preparation method of a kind of superhigh molecular weight polyethylene fibers as claimed in claim 1; The guide hole that it is characterized in that the described spinnerets of step (3) is half hyperboloid shape, and its minimum-value aperture is that 0.5～1.5mm, draw ratio are 2～20, the angle of outlet is 0.5～2o.

5. the high concentration preparation method of a kind of superhigh molecular weight polyethylene fibers as claimed in claim 1 is characterized in that the guide hole of the described spinnerets of step (3) is cylindrical or conical, and its minimum-value aperture is that 0.5～1.5mm, draw ratio are 2～20.