CN110820058A - Preparation method of civil high-performance polyethylene fiber - Google Patents

Abstract

The invention relates to a preparation method of civil high-performance polyethylene fiber, which comprises the steps of extruding polyethylene raw material which has the weight-average molecular weight of 15-40 ten thousand and is polymerized by a single-activity-center catalyst into polyethylene undrawn protofilament at high temperature through a screw extruder; directly carrying out high-power drafting on the extruded protofilament at normal temperature; the high-power drafted raw silk is subjected to multiple-power drawing again at high temperature through a heat channel; and (3) rolling the polyethylene fiber after high-temperature stretching to obtain the polyethylene fiber with the tensile strength of more than 20 cN/dtex. Compared with the prior art, the fiber product obtained by the invention has the advantages of simple process flow, environmental protection, energy conservation, high safety factor, low production cost and the like under the condition of meeting the requirements of the existing civil high-performance fiber field.

Description

A kind of preparation method of civil high-performance polyethylene fiber

technical field

The invention belongs to the technical field of polymer materials, and in particular relates to a preparation method of high-strength and high-modulus polyethylene fibers.

Background technique

With the rapid development of science and technology, the demand for special fibers in the engineering and technical field is increasing. High-performance polyethylene fibers have the characteristics of light weight, high strength, long service life, wear resistance, high strength, moisture resistance and corrosion resistance. Tow rope, negative force rope, salvage rope, anti-cut gloves, etc. At the same time, high-performance polyethylene fibers can be made into protective clothing, helmets, bulletproof materials, etc. in the military. The composite material of high-performance polyethylene fiber also has high strength and strong anti-collision performance. In aerospace, it is suitable for wingtip structures of various aircraft, spacecraft structures and buoy aircraft. In sporting goods, helmets, snowboards, sailboards, fishing rods, rackets, bicycles, gliders, ultra-lightweight aircraft parts, etc. have been made. Due to the biocompatibility of UHMWPE fiber composite materials, it can also be used in dental trays, prostheses, medical gloves, etc.

In recent years, the use of high-performance fibers has gradually increased in the civilian field, and currently the main application in the civilian field is ultra-high molecular weight polyethylene fiber or aramid fiber, and the production process of these two types of high-performance fibers is more complicated and the production cost is high. , and has a large pollution in the production process. These factors also limit the expansion of high performance in the civilian field, and have not been widely used so far.

The narrow molecular weight distribution polyethylene obtained by single-site catalyst polymerization has attracted extensive attention in the industry. Because the polyethylene with narrow molecular weight distribution contains only a few low molecular weight fractions, its performance has reached a new level compared with the polyethylene obtained by the polymerization of traditional Ziegler-Natta and chromium-based catalyst systems. In the field of high-strength fibers, the processing performance of single-active center polyethylene is better than that of ultra-high molecular weight polyethylene, which makes single-active center polyethylene show its unique side.

At present, the methods of polyethylene spinning can be mainly divided into three categories:

The first category includes Chinese Patent CN200980146604, Chinese Patent CN201410264678, International Application Publication No. WO2005/066401A1, U.S. Patent US430577, etc., after first swelling and dissolving high-molecular-weight polyethylene with a solvent, it is extruded into polyethylene strands. Steps such as solvent extraction and drying are performed on the raw silk to remove the solvent, and finally multi-stage drawing is performed to obtain high-strength and high-modulus polyethylene fibers. Since the molecular weight of the raw materials used in this type of method is generally higher than 1.5 million, the strength of the obtained polyethylene fiber is relatively high. However, the production process is complicated, the cost is high, and the volatilization and recovery of the solvent in the production process is difficult to solve, which has a great impact on the environment.

The second category mainly includes those disclosed in Chinese Patent CN201010533593, Chinese Patent CN201410416669, Chinese Patent CN101230501A, etc., blending low-molecular-weight polyethylene or polyethylene-modified masterbatch with ultra-high-molecular-weight polyethylene and then melt-extruding fiber precursors, and Multistage drawing is performed to obtain polyethylene fibers. In this method, in order to ensure the fluidity of ultra-high molecular weight polyethylene, low molecular weight polyethylene and modified masterbatch are added in a large amount, and the weight ratio is generally 5% to 10% or even higher. These modified masterbatches also lead to finished products. Defects in mechanical properties, so the obtained fiber strength is not high, usually 15 ~ 25cN/dtex. At the same time, the technological process is also more complicated, so that its cost has not dropped significantly.

The third category mainly includes US Patent USP4228118, Chinese Patent CN03807737, etc. using polyethylene with a weight average molecular weight of less than 300,000 for melt extrusion spinning. This kind of method does not need to add flow-modified masterbatch or low molecular weight polyethylene. Some of the methods Due to the low molecular weight of the raw materials used, the mechanical properties of the obtained fibers are limited, and the other part is due to the traditional processing technology, which does not fully exert the inter-chain structure characteristics of high molecular weight polyethylene molecules, resulting in the obtained polyethylene fiber products have only a tensile strength of only At about 15cN/dtex, the mechanical properties are not ideal as high-performance fibers.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problems that the current civilian high-performance polyethylene production process is complex, the production cost is high, and the environmental pollution is relatively large, and the strength of the products obtained by the existing polyethylene melt spinning method is generally low. , to provide a preparation method of civilian high-performance polyethylene fiber.

The object of the present invention can be realized through the following technical solutions:

A preparation method of civilian high-performance polyethylene fiber, comprising the following steps:

(1) The polyethylene raw material obtained by polymerization of a single active site catalyst with a weight-average molecular weight of 150,000 to 400,000 is extruded through a screw extruder at high temperature to extrude polyethylene undrawn strands;

(2) Direct high-stretching of the extruded strands at room temperature;

(3) The raw yarn after high-stretching is stretched multiple times again at high temperature through the hot tunnel;

(4) winding up the polyethylene fiber stretched at high temperature to obtain a polyethylene fiber with a tensile strength of 20 cN/dtex or more.

The single site catalyst is selected from metallocene catalysts or late transition metal catalysts.

The ratio of the weight-average molecular weight to the number-average molecular weight of the polyethylene raw material is Mw/Mn<3.0, the number of methyl groups in one thousand carbons is less than 0.1, and the density is greater than 0.94 g/cm ³ .

The polyethylene raw material does not need to add processing aids at the stage of extrusion into undrawn strands. For the processing of fiber products, a small amount of additives will become impurities in the ultrafine fibers, resulting in the reduction of fiber. Compared with traditional polyethylene, especially in the extrusion process of high molecular weight polyethylene, the extrusion temperature often exceeds 200 °C, so antioxidants must be added to prevent molecular chain degradation during processing, resulting in extruded fiber properties. fall, turn yellow. The invention controls the processing temperature of polyethylene by utilizing the unique rheological characteristics of single-active polyethylene at 150,000 to 400,000, and because the single-active center has a narrow molecular weight distribution and a small number of extremely high molecular weight parts, the processing technology of the present invention After melt extrusion, there is almost no molecular chain degradation phenomenon, which avoids the addition of antioxidants before processing, greatly reduces the influence of impurities on the fiber drawing process, and reduces the blending equipment and equipment before feeding in the traditional process. process steps, again reducing costs.

The temperature of the extrusion section is 145°C to 200°C, preferably 150°C to 180°C, and the temperature from the melt pump to the die is 145°C to 220°C, preferably 150°C to 180°C.

After the polyethylene is extruded, it does not need to be cooled, and is directly stretched at a high magnification, and the stretch ratio is 5 to 30 times, preferably 10 to 20 times.

The high temperature multi-fold stretching ratio of the hot tunnel is 5-15 times, preferably 7-12 times.

The temperature of the hot tunnel is controlled at 100-130°C, preferably 110-125°C.

The residence time of the fibers in the hot shaft is greater than 5 seconds, preferably greater than 10 seconds, more preferably greater than 20 seconds.

The diameter of the wire outlet hole of the die of the screw extruder is 0.5-10 mm.

In order to further improve the performance of the product under the premise of ensuring the simplification of the processing technology, the present invention selects polyethylene with a weight average molecular weight of 150,000 to 400,000 as the raw material. The ultra-high molecular weight polyethylene with a molecular weight of more than 1 million is used as the base material to provide strength, and then the processing performance is improved by adding low molecular weight polyethylene or processing aids. Due to the low molecular weight, the present invention does not need to add any processing aids during processing. The smooth filament can be obtained by extrusion, and due to the structural characteristics of the molecular weight segment and narrow molecular weight distribution, it is guaranteed that it has the characteristics of excellent mechanical properties and processability.

The present invention also finds that the special processing characteristics of single-active-site polyethylene of 150,000 to 400,000 are reflected in that, for this raw material, when the traditional processing temperature is used, that is, when the processing temperature is higher than 200 ° C, the raw yarn extruded by the die head The stretchability is poor, and the fibers require a rapid cooling process before subsequent steps to prevent the occurrence of fiber-to-fiber adhesion. In response to this phenomenon, when the processing temperature can be controlled at a specific temperature below 200 °C, single-active center polyethylene with a weight average molecular weight of 150,000 to 400,000 is used, and high-stretching can be performed directly after extruding through the extruder head. , the stretching ratio can even reach 30 times the extrusion rate, it has excellent ductility and a certain melt strength, and there is no wire breakage. Below mm, the ultra-fine strands effectively alleviate the problem of untimely cooling after extrusion. The cooling effect on the inside of the fiber strands is much better than the traditional air-cooling or water-cooling process, which greatly reduces the probability of large grains and reduces the later stage. The difficulty of high-temperature and high-fold stretching greatly improves the mechanical properties of the fiber products after subsequent high-temperature stretching, and the step of cooling after extrusion is omitted, which once again reduces the input and processing costs in the traditional process.

The present invention further finds that, in order to obtain polyethylene fibers with higher performance by the method of melt spinning, when the extruded fibers are stretched at high times through a hot shaft, compared with the traditional hot stretching process of ultra-high molecular weight polyethylene fibers, the need for With a longer residence time, the molecular chains of the obtained fibers can be fully oriented and crystallized at a longer residence time.

The invention is a preparation method of high-performance polyethylene fiber for civilian use. The polyethylene raw material obtained by polymerization of a single active site catalyst can be directly melted and extruded at a high temperature without using a solvent or any processing aid. Performance polyethylene fibers.

At present, ultra-high molecular weight polyethylene is generally used in the preparation method of high-strength and high-modulus polyethylene fibers. By increasing the molecular weight of polyethylene, the properties of polyethylene fibers are improved. However, as the molecular weight increases, the processability of polyethylene decreases significantly. By introducing a large amount of solvent in the processing process, the processing performance can be increased, and the introduction of the solvent will bring about a series of problems such as the influence of desolvation on the performance of the product, a substantial increase in the preparation cost, and environmental protection issues. Therefore, there is a need to find a spinning method that can obtain high-performance fibers and does not require the addition of solvents.

It is well known that the molecular chain part of high molecular weight in polyethylene is the key to affecting the processing performance. The present invention uses the high molecular weight polyethylene raw material obtained by polymerization of a single active site catalyst to prepare fibers. The characteristics of the single active site catalyst are the polyethylene obtained by polymerization. The molecular weight distribution is narrow, taking into account the processability of polyethylene raw materials and the mechanical properties of products. In the single-active-site polyethylene with a weight-average molecular weight of 150,000 to 400,000, this characteristic is more obvious. Compared with the ultra-high molecular weight polyethylene, the single-active-site polyethylene with high molecular weight has a processability. , while the mechanical properties are comparable to those of ultra-high molecular weight polyethylene, and are better than those of traditional high molecular weight polyethylene (see Table 1).

Table 1 Comparison of mechanical properties of polyethylene with single active center

The present invention obtains high-performance polyethylene fiber products by using polyethylene raw materials with reasonable molecular weight distribution and molecular weight range, and targeted processing technology without adding auxiliary agents, and the performance indicators of the products are suitable for the current High-performance consumer fibers. Compared with the current preparation method of high-performance civil fiber, the disclosed technical solution has the following advantages under the condition that the high-performance fiber preparation method of the present patent meets the performance requirements of the current high-performance civil fiber:

1) No solvent is needed in the spinning process, no mixing and cooling process, which greatly simplifies the spinning process of high-performance polyethylene fibers.

2) Significantly reduce the production cost due to solvent processing and solvent recovery.

3) The production process is in a solvent-free state, which greatly improves the safety factor in the production process.

4) No hazardous waste is generated in the production process, making the production process of high-strength and high-modulus polyethylene fibers more environmentally friendly.

5) There is no swelling step in the production process, which makes the production process more stable.

6) There is no need to add any processing aids during processing, which greatly reduces the influence of impurities on the fiber drawing process, and reduces the blending equipment and process steps before feeding in the traditional process.

7) The extrusion process temperature is greatly reduced, which greatly saves energy in the production process.

Detailed ways

The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

A preparation method of civilian high-performance polyethylene fiber, comprising the following steps:

(1) The polyethylene raw material obtained by polymerizing a single active site catalyst, such as a metallocene catalyst or a late transition metal catalyst with a weight average molecular weight of 150,000 to 400,000, is extruded through a screw extruder at high temperature to extrude polyethylene undrawn strands , the ratio of weight-average molecular weight to number-average molecular weight of the polyethylene raw material used is Mw/Mn < 3.0, the number of thousand carbon methyl groups is < 0.1, and the density is > 0.94g/cm ³ . In the above extrusion process, there is no need to add processing aids, extrusion The temperature of the exit section is 145℃～200℃, the temperature from the melt pump to the die is 145℃～220℃, and the diameter of the exit hole of the die of the screw extruder is 0.5～10mm;

(2) The extruded filaments do not need to be cooled, and directly carry out 5 to 30 times of high drafting at normal temperature;

(3) The high-stretched raw yarn is stretched again by 5-15 times at a high temperature through a 100-130°C hot tunnel;

(4) winding up the polyethylene fiber stretched at high temperature to obtain a polyethylene fiber with a tensile strength of 20 cN/dtex or more.

The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

Characterization data of polyethylene raw materials in the examples are obtained by the following methods:

Tensile properties

Using the method and equipment of "ASTM D885M", the tensile strength and tensile modulus of the finished yarn are tested.

Example 1

The weight-average molecular weight obtained by the polymerization of the rear transition metal catalyst is 150,000, the Mw/Mn is 2.8, the number of methyl groups in one thousand carbons is less than 0.1, and the polyethylene with a density of 0.945g/cm ³ is fed into a screw extruder for melt extrusion. out. The temperature of the twin-screw from the feeding section to the discharge temperature is 145℃～180℃, the rotation speed is 90 rpm, and the diameter of the extrusion die is 0.5mm.

The extruded strands are directly stretched for multiple times and then wound up, and the stretch ratio is 10 times the extrusion rate. The coiled fibers were drawn again at high temperature and multiple times, with a draw ratio of 7 times and a hot tunnel temperature of 100°C.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 21.19cN/dtex.

Example 2

The weight-average molecular weight obtained by the polymerization of the metallocene catalyst is 200,000, the Mw/Mn is 2.9, the number of thousand carbon methyl groups is less than 0.1, and the polyethylene with a density of 0.943 g/cm ³ is fed into a screw extruder for melt extrusion. . The temperature of the twin-screw from the feeding section to the discharge temperature is 145℃～190℃, the rotation speed is 90 rpm, and the diameter of the extrusion die is 0.9mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 15 times the extrusion rate. The wound fibers were drawn again at high temperature and multiple times, with a draw ratio of 8 times and a hot tunnel temperature of 110°C.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 23.32cN/dtex.

Example 3

The weight-average molecular weight obtained by the polymerization of the metallocene catalyst is 400,000, the Mw/Mn is 2.9, the number of thousand carbon methyl groups is less than 0.1, and the polyethylene with a density of 0.941 g/cm ³ is fed into a screw extruder for melt extrusion. . The temperature of the twin screw from the feeding section to the discharge temperature is 145℃～190℃, the rotation speed is 110 rpm, and the diameter of the extrusion die is 1mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 5 times of the extrusion rate. The wound fibers were drawn again at high temperature and multiple times, with a draw ratio of 9 times and a hot tunnel temperature of 120°C.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 25.92cN/dtex.

Example 4

The weight-average molecular weight obtained by the polymerization of the metallocene catalyst is 200,000, the Mw/Mn is 2.7, the number of thousand carbon methyl groups is less than 0.1, and the polyethylene with a density of 0.943 g/cm ³ is fed into a screw extruder for melt extrusion. . The temperature of the twin-screw from the feeding section to the discharge temperature is 145℃～190℃, the rotation speed is 200 rpm, and the diameter of the extrusion die is 5mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 30 times the extrusion rate. The coiled fibers were drawn again at high temperature multiple times, the draw ratio was 9 times, and the hot tunnel temperature was 125°C.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 24.39cN/dtex.

Example 5

The weight-average molecular weight obtained by the polymerization of the post-transition metal catalyst is 400,000, Mw/Mn is 2.4, the number of thousand carbon methyl groups is less than 0.1, and the polyethylene with a density of 0.941g/cm ³ is fed into a screw extruder for melt extrusion. out. The temperature of the twin screw from the feeding section to the discharge temperature is 145℃～200℃, the rotation speed is 220 rpm, and the diameter of the extrusion die is 10mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 27 times the extrusion rate. The coiled fibers were drawn again at high temperature and multiple times, with a draw ratio of 15 times and a hot tunnel temperature of 130°C.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 28.21cN/dtex.

Example 6

The weight-average molecular weight obtained by the polymerization of the post-transition metal catalyst is 300,000, Mw/Mn is 2.0, the number of methyl groups in one thousand carbons is less than 0.1, and the polyethylene with a density of 0.95g/cm ³ is fed into a screw extruder for melt extrusion. out. The temperature of the twin screw from the feeding section to the discharge temperature is 145℃～200℃, the rotation speed is 220 rpm, the temperature from the melt pump to the die is 145℃～220℃, and the diameter of the extrusion die is 5mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 25 times the extrusion rate. The coiled fibers were drawn again at high temperature and multiple times, the draw ratio was 10 times, the temperature of the hot tunnel was 100°C, and the residence time of the fibers in the hot tunnel was 10s.

The high-temperature multi-stretched fibers were tested to obtain high-performance fibers with a tensile strength of 26.10 cN/dtex.

Example 7

The weight-average molecular weight obtained by the polymerization of the post-transition metal catalyst is 150,000, Mw/Mn is 2.5, the number of thousand carbon methyl groups is less than 0.1, and the polyethylene with a density of 0.942g/cm ³ is fed into a screw extruder for melt extrusion. out. The temperature from the feeding section to the discharge temperature of the twin-screw is 150℃～180℃, the rotation speed is 200 rpm, the temperature from the melt pump to the die head is 150℃～180℃, and the diameter of the extrusion die is 0.5mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 5 times of the extrusion rate. The coiled fibers were drawn again at high temperature and multiple times, the draw ratio was 5 times, the temperature of the hot tunnel was 110°C, and the residence time of the fibers in the hot tunnel was 15s.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 25.33cN/dtex.

Example 8

The weight-average molecular weight obtained by the polymerization of the post-transition metal catalyst is 250,000, Mw/Mn is 2.8, the number of thousand carbon methyl groups is less than 0.1, and the polyethylene with a density of 0.945g/cm ³ is fed into a screw extruder for melt extrusion. out. The temperature from the feeding section to the discharge temperature of the twin-screw is 150℃～180℃, the rotation speed is 200 rpm, the temperature from the melt pump to the die head is 150℃～180℃, and the diameter of the extrusion die is 0.5mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 20 times of the extrusion rate. The coiled fibers were drawn again at high temperature and multiple times, the draw ratio was 12 times, the temperature of the hot tunnel was 125°C, and the residence time of the fibers in the hot tunnel was 25s.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 25.31cN/dtex.

Example 9

The weight-average molecular weight obtained by the polymerization of the rear transition metal catalyst is 400,000, Mw/Mn is 2.6, the number of methyl groups in one thousand carbons is less than 0.1, and the polyethylene with a density of 0.945g/cm ³ is fed into the screw extruder for melt extrusion. out. The temperature from the feeding section to the discharge temperature of the twin-screw is 150℃～170℃, the rotation speed is 200 rpm, the temperature from the melt pump to the die is 150℃～200℃, and the diameter of the extrusion die is 10mm.

The extruded raw yarn is directly stretched for multiple times and then wound up, and the stretching ratio is 30 times the extrusion rate. The coiled fiber was stretched again at high temperature and multiple times, the stretching ratio was 15 times, the temperature of the hot tunnel was 130°C, and the residence time of the fiber in the hot tunnel was 22s.

The high-temperature multi-stretched fiber was tested to obtain a high-performance fiber with a tensile strength of 24.22cN/dtex.

Comparative Example 1

The ultra-high molecular weight polyethylene powder resin with a molecular weight of 1.5 million to 2 million is selected as the raw material, 3% to 8% (weight ratio) of polyethylene modified masterbatch is added, and the screw melt extrusion spinning and Polyethylene fibers with high strength and high elongation are obtained by super-stretching, the fiber strength is 15CN/dtex～25CN/dtex, and the elongation at break is 5%～8%.

The specific production process implementation steps are as follows:

The first step Preparation of polyethylene modified masterbatch:

1. Select LDPE low density polyethylene or LLDPE linear low density polyethylene as raw material, add (weight ratio) 7% to 15% of POE polyolefin elastomer, 3% to 5% of PE foaming agent, and 5% to 10% ethylene propylene rubber EPDM or SEBS for uniform mixing;

2. The above-mentioned polymer that has been uniformly mixed is mixed and granulated by twin-screw: the temperature of each section of the twin-screw is between 150 and 220°C, and the speed of the twin-screw is controlled at 200 to 250 revolutions per minute to prepare polyethylene modification. masterbatch.

Its compound polyethylene modified masterbatch has excellent functions such as low melting point, low viscosity, lubricity, good fluidity and easy dispersion.

The second step UHMWPE melt spinning preparation:

1. Select ultra-high molecular weight polyethylene resin with a molecular weight of 1.5 to 2 million, and add 3% to 8% (weight ratio) of the compounded polyethylene modified masterbatch to mix evenly;

2. The above-mentioned mixture is transported into the screw extrusion melt spinning: the screw length-diameter ratio is 1:40, the temperature of each section of the screw is 150 ℃ ~ 250 ℃, the screw extrusion speed is 200 ~ 250 rpm, the spinneret 100～150 holes, aperture 0.5～0.8mm, temperature of spinneret melt is controlled at 200℃～220℃, nozzle draft is 5～15m/min; ℃; water-bath cooling the fiber for winding into a tube;

3. The fiber that has been wound into a cylinder is then subjected to two super-stretching, drying and shaping, and finally the finished fiber is made: the first stage of super-stretching is stretched in a water bath, and the temperature of the water bath is 80 ℃ ~ 95 ℃, The stretching ratio is 5 to 10 times; the second pass is stretched with superheated steam, the steam temperature is 110 ℃ ~ 130 ℃, and the stretching ratio is 3 to 6 times; after super-stretching, dry, use hot air circulation drying, drying temperature It is 120℃～130℃, and the tension is 1.1～1.2 times; after setting, the setting temperature is 130℃～145℃, and the setting line speed is 20～40 meters per minute; finally, UHMWPE finished fiber is made; The fiber strength of the produced ultra-high molecular weight polyethylene fiber is 15CN/dtex～20CN/dtex.

Comparative Example 2

Polyethylene having a weight-average molecular weight of 150,000 and Mw/Mn of 5.1 was extruded from a spinneret having a configuration of φ0.8 mm at a rate of 0.5 g/min per hole at 270°C. The extruded fiber passed through a 15 cm holding section, and was then quenched and cooled at 20° C. and 0.5 m/s, and wound up.

The extruded strands are cooled by air and then enter the post-stretching stage. The first-stage stretching temperature is 25°C, and the stretching is 2 times. The temperature of the second-stage stretching was 100°C, and the stretching was 7 times. After multi-stage stretching, the strength of polyethylene fiber obtained is 12.5cN/dtex, and the modulus is 503cN/dtex.

Comparative Example 3

Take high-density polyethylene with a weight-average molecular weight of 300,000 and a ratio of weight-average molecular weight to number-average molecular weight of 4.5, add antioxidants for spinning, the temperature of the screw extrusion section is 230 °C, and the temperature of the extruder head is 290 °C, High-magnification stretching cannot be performed directly after extrusion. The high-temperature fiber was cooled by water cooling and then wound up and stretched again at a high magnification. The stretching ratio was 6 times, and the tensile strength of the obtained fiber was 7 cN/dtex.

Table 2

weight average molecular weight Mw/Mn Intensity cN/dtex Auxiliary content % Example 1 15 2.8 21.19 0 Example 2 20 2.9 23.32 0 Example 3 40 2.9 25.92 0 Example 4 20 2.7 24.39 0 Example 5 40 2.4 28.21 0 Example 6 30 2.0 26.10 0 Example 7 15 2.5 25.33 0 Example 8 25 2.8 25.31 0 Example 9 40 2.6 24.22 0 Comparative Example 1 150～200 - 15～20 3 to 8 Comparative Example 2 15 5.1 12.5 0 Comparative Example 3 82 4.5 - 0

As can be seen from the above table, this method uses polyethylene obtained by polymerization of a weight-average molecular weight of 150,000 to 400,000, a density higher than 0.94 g/cm ³ , and a single active site catalyst as a raw material after melt extrusion, and then processed in a targeted manner. process, the obtained polyethylene fiber has better mechanical properties than the low molecular weight polyethylene used in the comparative example and the melt spinning product of ultra-high molecular weight polyethylene fiber obtained by blending with the modified masterbatch, and the cost, process The complexity and environmental aspects are far superior to the method of preparing high-performance fibers using solution dissolution and current melt extrusion methods.

In the description of this specification, description with reference to the terms "one embodiment," "example," "specific example," etc. means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one aspect of the present invention. in one embodiment or example. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (10)

1. a preparation method of civilian high-performance polyethylene fiber, is characterized in that, comprises: (1) The polyethylene raw material obtained by polymerization of a single active site catalyst with a weight-average molecular weight of 150,000 to 400,000 is extruded through a screw extruder at high temperature to extrude polyethylene undrawn strands; (2) Direct high-stretching of the extruded strands at room temperature; (3) The high-stretched raw yarn is stretched multiple times again at high temperature through the hot tunnel; (4) winding up the polyethylene fiber stretched at high temperature to obtain a polyethylene fiber with a tensile strength of 20 cN/dtex or more. 2 . The method for preparing a civil high-performance polyethylene fiber according to claim 1 , wherein the single active site catalyst is selected from a metallocene catalyst or a late transition metal catalyst. 3 . 3. the preparation method of a kind of civil high-performance polyethylene fiber according to claim 1, is characterized in that, the ratio Mw/Mn<3.0 of described polyethylene raw material weight-average molecular weight and number-average molecular weight is less than 3.0, and the number of thousands of carbon methyl groups <0.1, density >0.94 g/cm ³ . 4 . The method for preparing a high-performance polyethylene fiber for civilian use according to claim 1 , wherein the polyethylene raw material does not need to be added with processing aids at the stage of extrusion into undrawn strands. 5 . 5. The preparation method of a civil high-performance polyethylene fiber according to claim 1, wherein the temperature of the extrusion section is 145°C to 200°C, preferably 150°C to 180°C, and the melt is pumped to the temperature of the die head. It is 145°C to 220°C, preferably 150°C to 180°C. 6 . The method for preparing high-performance polyethylene fibers for civil use according to claim 1 , wherein the polyethylene is directly stretched at high times without cooling after extrusion, and the stretching ratio is 5 to 30 times, preferably 10 times. 7 . ~20 times. 7 . The method for preparing high-performance polyethylene fibers for civil use according to claim 1 , wherein the high-temperature multi-stretching ratio of the hot tunnel is 5-15 times, preferably 7-12 times. 8 . 8 . The method for preparing high-performance polyethylene fibers for civil use according to claim 1 , wherein the temperature of the hot tunnel is controlled at 100-130° C., preferably 110-125° C. 9 . 9 . The method for preparing high performance polyethylene fibers for civil use according to claim 1 , wherein the residence time of the fibers in the hot tunnel is greater than 5 seconds, preferably greater than 10 seconds, and more preferably greater than 20 seconds. 10 . 10 . The method for preparing a civil high-performance polyethylene fiber according to claim 1 , wherein the diameter of the exit hole of the die of the screw extruder is 0.5-10 mm. 11 .