Preparation method of high-cooling-sensation high-strength and high-modulus polyethylene fiber and fiber obtained thereby

Abstract

The present invention provides a preparation method of high-cooling-sensation high-strength and high-modulus polyethylene fibers. The preparation method is to melt and convey high-molecular-weight polyethylene raw materials through a screw extruder with a low-shear and high-conveying module, and then enter a spinning assembly. A combined spinneret that can make the macromolecules of the polyethylene melt oriented and release the elastic potential energy of the melt is used to extrude into filaments to obtain nascent fibers. Subsequently, the nascent fibers are subjected to multi-stage stretching and heat setting to obtain finished high-cooling-sensation high-strength and high-modulus polyethylene fibers. This method meets the industrialization requirements, has little pollution and high efficiency. The contact cooling sensation Qmax of the obtained fibers is above 0.4 W / cm<supgt;2< / supgt>; the fiber breaking strength is above 10 cN / dtex, the elastic modulus is above 400 cN / dtex, and the breaking elongation rate is below 6%. The polyethylene fibers have good production and processing performance, and have the quality of high-cooling-sensation, high-strength and high-modulus, and can be used in fields such as textiles, industrial materials, and military industry.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber manufacturing, and relates to a preparation method of a high-cooling-sensation, high-strength and high-modulus polyethylene fiber and the fiber obtained thereby. Background Art

[0002] High-strength and high-modulus polyethylene fibers are mostly made of ultra-high molecular weight polyethylene (UHMWPE). They have excellent fatigue resistance, chemical corrosion resistance and tensile strength properties. They are the third generation of high-strength, high-modulus and high-performance special fibers after carbon fibers and aramid fibers in the world. High-strength and high-modulus polyethylene fibers have excellent properties such as good stability, wear resistance, cut resistance, chemical corrosion resistance and high crystallinity, and are widely used in textiles, industrial materials, military and other fields.

[0003] The existing internationally common methods for producing high-strength and high-modulus polyethylene fibers are mostly gel spinning, including a dry process route (mainly using decalin as a solvent) and a wet process route (mainly using white oil as a solvent). Both processes require a solvent to uniformly dissolve the ultra-high molecular weight polyethylene resin, then spin and extrude, and then remove the solvent to prepare high-strength and high-modulus polyethylene fibers. The production process is long, the process is complex, the energy consumption is high, and it causes a certain degree of pollution to the environment. At the same time, the high-strength and high-modulus polyethylene fibers prepared by this method have pores on the surface, and at the same time, the release of elastic potential energy of the fibers is relatively low, and the disentanglement and crystallinity are insufficient, resulting in a low contact cooling sensation of the fibers.

[0004] Now, more and more people are gradually starting to explore the use of melt spinning to prepare high-strength and high-modulus polyethylene fibers. The melt spinning process is short, pollution-free and low-cost. However, for ultra-high molecular weight polyethylene, in the manufacturing process of the simple melt spinning method, the viscosity is extremely high, and the molecular chains are greatly entangled, so that there is no viscous flow state above the melting point, but a high elastic state, and the spinnability is poor. There is no industrialized melt spinning route for preparing high-strength and high-modulus polyethylene fibers in China yet. And the fibers obtained have a low contact cooling sensation.

[0005] Chinese Patent CN 114502784 A discloses a polyethylene yarn, a method for manufacturing the polyethylene yarn, and a skin-cooling-sensation fabric including the polyethylene yarn. For the fabric prepared by melt spinning of high molecular weight polyethylene with a weight average molecular weight (Mw) of 50,000 g / mol to 99,000 g / mol, the contact cooling sensation Qmax of the fibers is only 0.1 - 0.2 W / cm2, which does not meet the requirement of high contact cooling sensation.

[0006] Conventional ways to improve the cool feeling of polyethylene fibers mostly involve adding cool feeling substances such as jade powder to the polymer. Chinese Patent CN 111172619 A discloses a fiber, its preparation method, uses, and textiles. By adding and modifying polyethylene through jade powder, emery powder, double-stage stone powder, or hard carbonate powder, the contact cool feeling Qmax reaches 0.5 - 0.6 W / cm 2 , but adding a modified foreign substance in an amount is likely to cause problems such as a decline in spinning performance and strength.

[0007] Chinese Patent CN109853069A discloses a method for preparing ultra-high molecular weight polyethylene fibers by melt spinning. In this method, a certain amount of solvent oil is added during polymerization to reduce the melt viscosity of ultra-high molecular weight polyethylene, so as to promote the disentanglement and orientation of macromolecular chains. Although this method reduces macromolecular entanglement to a certain extent, it introduces a foreign substance (solvent oil) into the raw materials, which is likely to cause screw slippage and an increase in spinning pressure, and does not have mass production capacity.

[0008] Japanese PCT Patent CN1646739A discloses polyethylene fibers and their manufacturing method. This method uses polyethylene with a weight average molecular weight of less than 300,000, and the ratio of weight average molecular weight to number average molecular weight (Mw / Mn) is less than 4. At the same time, each 1000 carbons on the main chain of the polyethylene molecule contains 0.01 - 3 branched chains. By introducing branched chain segments, the flexibility of the chain segments of ultra-high molecular weight polyethylene is reduced, and the spinnability is increased. However, the introduction of branched chains will make it difficult to increase the crystallinity of molecular chain segments, resulting in a decrease in strength. At the same time, when the ratio of weight average molecular weight to number average molecular weight (Mw / Mn) is less than 4, the molecular weight distribution is concentrated, which is likely to lead to high difficulty in disentangling during melt spinning, high component pressure, and a decrease in spinnability. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing high-cooling-sensation, high-strength, and high-modulus polyethylene fibers, to obtain high-cooling-sensation, high-strength, and high-modulus polyethylene fibers without adding cool feeling substances, and at the same time solve the problem that high-strength and high-modulus polyethylene fibers cannot be melt-spun on a large scale. Different from the fibers produced by conventional gel spinning, this fiber has high-cooling-sensation characteristics and can be used in fields such as textiles, industrial materials, and military industry.

[0010] The technical solution of the present invention is as follows:

[0011] A method for preparing high-cooling-sensation, high-strength, and high-modulus polyethylene fibers, comprising the following steps: melting and transporting a high molecular weight polyethylene raw material through a low-shear and high-conveyance screw extruder, and then entering a spinning assembly with a combined spinneret; using a combined spinneret that can orient macromolecules of the polyethylene melt and release the melt elastic potential energy to extrude into filaments to obtain nascent fibers; subjecting the nascent fibers to multi-stage stretching and heat setting to obtain finished high-cooling-sensation, high-strength, and high-modulus polyethylene fibers.

[0012] The preparation method of the high-cooling-sensation high-strength high-modulus polyethylene fiber is further designed in that: the intrinsic viscosity of the high-molecular-weight polyethylene is 3.5 to 10 dl / g, and the ratio of the weight-average molecular weight to the number-average molecular weight (Mw / Mn) is 5 to 10.

[0013] The preparation method of the high-cooling-sensation high-strength high-modulus polyethylene fiber is further designed in that: the screw extruder is connected to a heavy-duty gearbox with a high-torque output whose output torque level reaches above 11 T / A3; and the screw extruder has a conveying element, a mixing element, and a shearing element, wherein the sum of the number of the conveying element and the mixing element is more than 5 times the number of the shearing element; thereby realizing the low-shear high-conveyance characteristic and not damaging the molecular structure of the high-molecular-weight polyethylene as much as possible under the condition of ensuring smooth spinning.

[0014] The preparation method of the high-cooling-sensation high-strength high-modulus polyethylene fiber is further designed in that: the structure of the combined spinneret plate is a spinneret plate, a first flow guiding plate, and a second flow guiding plate which are sequentially attached from the outside to the inside; wherein, the spinneret plate has spinneret holes with an aspect ratio of 5 to 15 and a pore diameter of less than 0.5 mm; the first flow guiding plate has first flow guiding holes with an aspect ratio of 10 to 5, a pore diameter of less than 1.0 mm and larger than the pore diameter of the bottom-layer spinneret holes; the second flow guiding plate contains second flow guiding holes with an aspect ratio of 8 to 3, a pore diameter of less than 1.3 mm, and a pore diameter larger than that of the first flow guiding holes.

[0015] The preparation method of the high-cooling-sensation high-strength high-modulus polyethylene fiber is further designed in that: the multi-stage stretching process of the nascent fiber is that the first-stage stretching is cold stretching, at a temperature below 40 °C, and stretched 2 to 4 times; the second-stage stretching is hot stretching, at a temperature of 110 to 140 °C, and stretched 2 to 10 times; the third-stage stretching is a heat setting process, at 110 to 140 °C, and stretched 0.9 to 1.1 times.

[0016] A high-cooling-sensation high-strength high-modulus polyethylene fiber is prepared by the aforesaid preparation method of the high-cooling-sensation high-strength high-modulus polyethylene fiber. The contact cooling sensation Qmax of the high-cooling-sensation high-strength high-modulus polyethylene fiber is 0.4 W / cm 2 or more; the fiber breaking strength is 10 cN / dtex or more, the elastic modulus is 400 cN / dtex or more, and the breaking elongation rate is 6% or less; the fiber intrinsic viscosity is 1.5 to 10 dl / g.

[0017] The preparation method of the high-cooling-sensation high-strength and high-modulus polyethylene fiber of the present invention realizes the industrialization of preparing high-cooling-sensation high-strength and high-modulus polyethylene fiber by melt spinning. At the same time, the polyethylene fiber of the present invention is different from the conventional high-strength and high-modulus polyethylene fiber, and achieves the effect of high cooling sensation without adding cooling-sensation inorganic substances. It can be applied to fields such as textiles, industrial materials, and military industry. Specifically, high-molecular-weight polyethylene with an intrinsic viscosity of 3.5-10 dl / g and a ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) of 5-10 is used as the raw material, and is combined with a screw extruder with low shear and high conveying and a combined spinneret. The shorter macromolecular chain polymers play a lubricating role in the macromolecular network, which can improve the fluidity of the material at high temperature, reduce the difficulty of unraveling and the component pressure, thereby improving the spinnability, avoiding the impurities formed by adding additional lubricants, and avoiding the degradation of the material caused by excessively increasing the temperature in order to obtain fluidity, making it possible for the present invention to have large-scale production. Description of the Drawings

[0018] Figure 1 It is a data chart of 15 examples of the present invention.

[0019] Figure 2 It is a data chart of 15 comparative examples.

[0020] Figure 3 It is a surface and cross-section photo of the high-cooling-sensation high-strength and high-modulus polyethylene fiber prepared by the present invention.

[0021] Figure 4 It is a surface and cross-section photo of the high-strength and high-modulus polyethylene fiber prepared by wet spinning. Detailed Embodiments

[0022] The preparation method of the high-cooling-sensation high-strength and high-modulus polyethylene fiber described in the present invention is to use the melt spinning method. The polyethylene raw material is melt-conveyed through a screw extruder with a low shear and high conveying module, and then enters the spinning assembly. A combined spinneret that can release the orientation and elastic potential energy of the polyethylene melt is used to extrude into filaments to obtain nascent fibers. The nascent fibers are subjected to multi-stage stretching and heat setting to obtain the finished high-cooling-sensation high-strength and high-modulus polyethylene fiber.

[0023] Using the melt spinning method, different from the traditional wet and dry spinning methods, it has high spinning efficiency, low pollution, and stable product performance. Without adding cooling-sensation inorganic substances, the obtained product has a smooth surface without pores and a high contact cooling sensation.

[0024] The preparation method of the high-cooling-sensation high-strength and high-modulus polyethylene fiber described in the present invention has a characteristic viscosity of polyethylene of 3.5 to 10 dl / g, and the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is 5 to 10. When the polyethylene characteristics are within the above range, while meeting the basic requirements of melt spinning, the characteristics of high strength and high modulus of the polyethylene fiber can be maintained. Among them, the preferred characteristic combination is that when the characteristic viscosity is relatively low, the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is relatively low; when the characteristic viscosity is relatively high, the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is relatively high. In this way, while maintaining the high-strength and high-modulus characteristics, the spinnability of melt spinning can be maintained. When the characteristic viscosity of the raw material is relatively low, it is difficult to obtain high-strength and high-modulus properties for the finished product; when the characteristic viscosity of the raw material is too high, it is difficult to extrude during spinning, and it cannot be achieved by the melt spinning method. When the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is less than 5, the molecular weight distribution is concentrated, the viscosity is large and the stress is concentrated during melt spinning, and it is difficult to melt extrude, and it cannot be achieved by the melt spinning method; when the ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) is greater than 10, the molecular weight distribution is too wide, which easily leads to a decrease in fiber strength and spinnability.

[0025] Melt transportation is carried out through a screw extruder with a low-shear and high-conveyance module, and a heavy-duty gearbox with a high-torque output whose gearbox output torque level reaches above 11 T / A3 is used, which is beneficial to the high-conveyance performance of ultra-high molecular weight polyethylene melt in the screw at a low-shear rotation speed. When the gearbox output torque level is less than 11 T / A3, high rotation speed and high shear are required to complete the melt transportation, which will lead to too high screw pressure and breakage of the melt molecular chains, reducing the spinnability and also causing a decrease in fiber strength.

[0026] In the screw combination, the screw elements include conveying elements, mixing elements, and shearing elements. In the present invention, the conveying elements mainly refer to screw elements containing low lead, medium lead, and high lead, the mixing elements refer to tooth-shaped elements (including straight teeth and helical teeth), and the shearing elements refer to engaging blocks. Among them, the sum of the number of conveying elements and mixing elements is more than 5 times the number of shearing elements to achieve low shear while maintaining efficient mixing and conveying. When the sum of the number of conveying elements and mixing elements is less than 5 times the number of shearing elements, the shearing force is too high, which easily leads to too high screw pressure and breakage of the melt molecular chains, reducing the spinnability and also causing a decrease in fiber strength.

[0027] The structure of the combined spinneret plate described in the present invention is that the combined spinneret plate is composed of a spinneret plate, a first flow guide plate, and a second flow guide plate that are sequentially attached from the outside to the inside; among them, the spinneret plate has spinneret holes with a length-to-diameter ratio of 5 to 15 and a hole diameter of less than 0.5 mm; the first flow guide plate has first flow guide holes with a length-to-diameter ratio of 10 to 5, a hole diameter of less than 1.0 mm and larger than the hole diameter of the bottom-layer spinneret holes; the second flow guide plate contains second flow guide holes with a length-to-diameter ratio of 8 to 3, a hole diameter of less than 1.3 mm, and a hole diameter ratio larger than that of the first flow guide holes.

[0028] The spinneret holes, the first flow guiding holes, and the second flow guiding holes correspond to each other one by one and are in a gradually thickening form, which is beneficial to the full release of elastic potential energy while the melt molecules are untangled and highly oriented, obtaining a stable oriented structure to improve the thermal conductivity and contact cool feeling of the fiber, effectively controlling the creep of the polyethylene fiber after forming, and maintaining a relatively low spinning pressure to maintain the sustainability of spinning. The conventional single-component spinneret for melt spinning has a one-layer structure. When ultra-high molecular weight polyethylene is spun, due to its high molecular weight and difficulty in untangling, a spinneret with spinneret holes having a high length-diameter ratio (L / D greater than 20) is usually set. Such a spinneret can achieve a certain degree of untangling of polyethylene molecules and reduce the creep of the fiber after forming, but the fiber molecular chains are not sufficiently untangled, the contact cool feeling is not high, and at the same time, due to the high length-diameter ratio, the spinning pressure is extremely high, affecting the sustainability of spinning. When the number of spinneret plates in combination exceeds three layers, it is easy to cause slurry leakage from the spinneret plate, affecting spinnability.

[0029] The bottommost spinneret plate contains spinneret holes with a length-diameter ratio of 5 to 15 and a pore diameter of less than 0.5 mm, which is beneficial to the formation of melt spinning and maintains a relatively low spinning pressure. When the length-diameter ratio is less than 5, it is not conducive to the release of elastic potential energy of the melt polyethylene, the untangling of molecules, reduces the contact cool feeling of the fiber, and also causes a relatively high creep of the polyethylene fiber. When the length-diameter ratio is greater than 15, the assembly pressure is relatively high, affecting the sustainability of spinning. When the pore diameter is greater than 0.5 mm, the spinneret holes are too thick to be conducive to fiber formation, easily causing filament breakage and reducing spinnability.

[0030] The first flow guiding plate from bottom to top contains first flow guiding holes with a length-diameter ratio of 10 to 5 and a pore diameter of less than 1.0 mm, and the second flow guiding plate contains second flow guiding holes with a length-diameter ratio of 8 to 3 and a pore diameter of less than 1.3 mm. It is beneficial to the full release of elastic potential energy while the melt molecular segments are fully oriented, the untangling of polyethylene molecules, and at the same time maintains a relatively low spinning pressure to maintain the sustainability of spinning. When the length-diameter ratio of the first flow guiding holes of the first flow guiding plate is greater than 10, the assembly pressure is relatively high, affecting the sustainability of spinning; when the length-diameter ratio is less than 5, it is not conducive to the untangling of melt polyethylene molecules and reduces the contact cool feeling of the fiber. When the pore diameter of the first flow guiding holes of the first flow guiding plate is smaller than the pore diameter of the spinneret holes, the assembly pressure is relatively high, affecting the sustainability of spinning; when the pore diameter of the flow guiding holes of the first flow guiding plate is greater than 1.0 mm, the pore diameter is too thick to achieve the release of elastic potential energy and the untangling of polyethylene molecules, reducing the contact cool feeling of the fiber. When the pore diameter of the second flow guiding holes of the second flow guiding plate is smaller than the pore diameter of the first flow guiding holes, the assembly pressure is relatively high, affecting the sustainability of spinning, and the second flow guiding holes lose the design significance of reducing the assembly pressure, and only using the first flow guiding holes can achieve it; when the pore diameter of the second flow guiding holes is greater than 1.3 mm, the pore diameter is too thick to achieve the release of elastic potential energy and the untangling of polyethylene molecules, reducing the contact cool feeling of the fiber.

[0031] The preparation method of the high-cooling-sensation high-strength high-modulus polyethylene fiber is as follows. The multi-stage stretching process of the nascent fiber is as follows: the first-stage stretching is cold stretching, at a temperature below 40°C, with a stretching ratio of 2 to 4 times; the second-stage stretching is hot stretching, at a temperature of 110 to 140°C, with a stretching ratio of 2 to 10 times; the third-stage stretching is a heat setting process, at 110 to 140°C, with a stretching ratio of 0.9 to 1.1 times. Under this process, after the polyethylene melt is highly oriented and unwound in the spinneret, it is quenched into filaments, and can be well stretched and oriented and crystallized to achieve high strength and high modulus. When the temperature of the first-stage stretching is higher than 40°C, the unwound and oriented macromolecular chain segments are prone to disorientation, reducing the fiber strength; when the stretching ratio of the first-stage stretching is lower than 2 times, high-stretching orientation cannot be carried out during the first-stage stretching, which will reduce the fiber strength and modulus; when the stretching ratio of the first-stage stretching is higher than 4 times, it is easy to cause filament breakage and reduce the fiber yield. When the temperature of the second-stage stretching is lower than 110°C, the fiber cannot be highly stretched and oriented and crystallized, reducing the fiber strength and modulus; when the temperature of the second-stage stretching is higher than 140°C, it is easy to cause partial melting of the fiber, reducing the fiber strength and quality. When the stretching ratio of the second-stage stretching is lower than 2 times, the fiber cannot be highly stretched and oriented and crystallized, reducing the fiber strength and modulus; when the stretching ratio of the second-stage stretching is higher than 10 times, it is easy to cause filament breakage and reduce the fiber yield. When the temperature of the third-stage stretching is lower than 110°C, high setting cannot be achieved, and the thermal shrinkage rate and creep of the fiber are relatively high; when the temperature of the third-stage stretching is higher than 140°C, it is easy to cause the fiber to have no thermal shrinkage rate, making post-processing difficult. When the stretching ratio of the third-stage stretching is lower than 0.9 times, the fiber is too loose, affecting the stretching processability; when the stretching ratio of the third-stage stretching is higher than 1.1 times, it is easy to cause filament breakage and reduce the fiber yield.

[0032] The high-cooling-sensation high-strength high-modulus polyethylene fiber of the present invention has a contact cooling sensation Qmax of more than 0.4 W / cm 2 Above, by utilizing the high thermal conductivity characteristics, a relatively high contact cooling sensation can be achieved, and it can be applied in high-cooling-sensation textiles and industrial materials. If the contact cooling sensation is less than 0.4 W / cm 2 then ordinary wet spinning can achieve it, but the characteristics of high-cooling sensation cannot be achieved. The breaking strength of the fiber is above 10 cN / dtex, the elastic modulus is above 400 cN / dtex, and the elongation at break is below 6%, meeting the characteristics of high strength and high modulus, and achieving characteristics such as tensile strength and high performance. If the breaking strength is less than 10 cN / dtex, high strength cannot be achieved; if the elastic modulus is less than 400 cN / dtex, high modulus cannot be achieved; if the elongation at break is greater than 6%, it is difficult to obtain a high degree of crystal orientation and difficult to achieve high strength and high modulus.

[0033] The following is an explanation of the method for achieving high cool feeling of the present invention: The above-mentioned melt spinning, different from dry and wet spinning, improves the spinnability of melt spinning without adding cool feeling inorganic substances. The obtained fibers have a high degree of orientation and no pores on the surface, which is beneficial to improving the contact cool feeling. At the same time, using a screw with low shear and high conveying and a combined spinneret plate makes the molecular chains arranged orderly, releases elastic potential energy, reduces the entanglement of molecular chains, increases the thermal conductivity while improving the spinnability, and thus increases the contact cool feeling.

[0034] The following will list examples to specifically illustrate the fibers and their preparation methods of the present invention.

[0035] The following evaluations are carried out in the examples and comparative examples:

[0036] (1)Intrinsic viscosity

[0037] Referring to the GB / T 10247-2008 standard, the intrinsic viscosity is measured using the fully automatic Ubbelohde viscometer IV3400X produced by Hangzhou Zhuoxiang, and the unit is dl / g.

[0038] (2)Weight-average molecular weight

[0039] Referring to the GB / T 36214.4-2018 standard, the weight-average molecular weight is measured using the Agilent 1260 Infinity II multi-detector GPC / SEC system by high-temperature gel permeation chromatography.

[0040] (3)Number-average molecular weight

[0041] Referring to the GB / T 36214.4-2018 standard, the weight-average molecular weight is measured using the Agilent 1260 Infinity II multi-detector GPC / SEC system by high-temperature gel permeation chromatography.

[0042] (4)Fiber breaking strength, breaking elongation and fiber elastic modulus

[0043] Using the tensile testing machine "Tensilon" manufactured by Intec Co., Ltd., the stress-strain curve is measured under the conditions of a sample length of 20 cm and a tensile speed of 100% / min. Read the load at break, divide this load by the initial fineness to calculate the breaking strength, read the deformation at break, divide it by the sample length, and multiply the obtained value by 100 times to calculate the breaking elongation. At the same time, using the stress-strain curve, the Young's modulus is calculated by using the fiber density and fineness. All these values are the simple average of the results obtained by repeating this operation 5 times with the same standard. The breaking strength is the value obtained by rounding the second decimal place, and the breaking elongation is the value obtained by rounding after the decimal point. Calculate the fiber elastic modulus from the tangent line with the maximum gradient near the origin of the stress-strain curve.

[0044] (5) Fiber contact cool feeling

[0045] Referring to the GB / T 35263-2017 standard, using a KES-QM contact cool feeling tester, making the fiber into a woven fabric test piece, and testing the contact cool feeling Qmax, with the unit of W / cm 2 .

[0046] (6) Observation of fiber surface and cross-section

[0047] The fiber is embedded with epoxy resin, frozen in a Reichert Cryosectioning System Model FC•4E, cut with a Reichert-Nissei ultracut N (ultramicrotome) with a diamond knife, and then the cut surface is observed and photographed with a transmission electron microscope (TEM) H-7100FA manufactured by Hitachi, Ltd. at an appropriate magnification.

[0048] The present invention will be specifically described based on the embodiments below.

[0049] Example 1

[0050] Using the method of melt spinning, using ultra-high molecular weight polyethylene raw materials with an intrinsic viscosity of 5.5 dl / g and a ratio of weight average molecular weight to number average molecular weight (Mw / Mn) of 7.5, feeding them into a screw extruder. The screw extruder uses a heavy-duty gearbox with a gearbox torque rating of 12, and the ratio of the sum of the number of screw conveying elements and mixing elements to the number of shear elements in the screw thread elements is 7, and melt conveying is carried out at a temperature of 150°C to 250°C. Then it enters a spinning box at 260°C. The spinneret is a three-layer combined spinneret. Among them, the bottom layer spinneret contains spinneret holes with an aspect ratio of 10 and a pore diameter of 0.4 mm. The first deflector from bottom to top contains deflector holes with an aspect ratio of 7 and a pore diameter of 0.8 mm. The third layer deflector contains deflector holes with an aspect ratio of 5 and a pore diameter of 1.15 mm. After being extruded from the spinneret, it is cooled and wound to obtain as-spun fibers. Under this process, the pressure of the spinning pack is 18 MPa, and the pressure rises by 0.2 MPa after continuous operation for 24 h, meeting the conditions for continuous melt spinning.

[0051] The above as-spun fibers are subjected to multi-stage stretching: the first stage stretching is cold stretching, at a temperature below 40°C, stretching 3 times; the second stage stretching is hot stretching, at a temperature of 130°C, stretching 8 times; the third stage stretching is a heat setting process, at 110°C, stretching 1.0 times, to obtain finished high-cooling-sensation, high-strength, and high-modulus polyethylene fibers. The mechanical properties of the high-cooling-sensation, high-strength, and high-modulus polyethylene fibers obtained in Example 1 are as follows: the breaking strength reaches 18 cN / dtex, the elastic modulus reaches 700 cN / dtex, and the breaking elongation rate is 4.8%, meeting the characteristics of high strength and high modulus.

[0052] As Figure 3 shown, the surface of the high-cooling-sensation high-strength and high-modulus polyethylene fiber obtained from Example 1 is dense and pore-free. The contact cooling sensation Qmax of the woven fabric specimen made of the high-cooling-sensation high-strength and high-modulus polyethylene fiber obtained from Example 1 is 0.51 W / cm 2 , having a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The result data is as Figure 1 shown.

[0053] Example 2

[0054] Ultra-high molecular weight polyethylene raw materials with a characteristic viscosity of 3.5 dl / g and a ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) of 5.0 are used, and all other finished high-cooling-sensation high-strength and high-modulus polyethylene fibers are obtained according to the method of Example 1.

[0055] The high-cooling-sensation high-strength and high-modulus polyethylene fiber obtained from Example 2 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0056] The contact cooling sensation Qmax of the woven fabric specimen made of the high-cooling-sensation high-strength and high-modulus polyethylene fiber obtained from Example 2 is 0.47 W / cm 2 , having a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0057] Example 3

[0058] Ultra-high molecular weight polyethylene raw materials with a characteristic viscosity of 10 dl / g and a ratio of weight-average molecular weight to number-average molecular weight (Mw / Mn) of 10 are used, and all other finished high-cooling-sensation high-strength and high-modulus polyethylene fibers are obtained according to the method of Example 1.

[0059] The high-cooling-sensation high-strength and high-modulus polyethylene fiber obtained from Example 3 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0060] The contact cooling sensation Qmax of the woven fabric specimen made of the high-cooling-sensation high-strength and high-modulus polyethylene fiber obtained from Example 3 is 0.42 W / cm 2 , having a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0061] Example 4

[0062] A heavy-duty gearbox with a gearbox torque rating of 11 is used for the screw extruder, and all other finished high-cooling-sensation high-strength and high-modulus polyethylene fibers are obtained according to the raw materials and methods of Example 1.

[0063] The high-cooling-sensation high-strength and high-modulus polyethylene fibers obtained in Example 4 have relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0064] For the woven fabric specimen made of the high-cooling-sensation high-strength and high-modulus polyethylene fibers obtained in Example 4, the measured contact cooling sensation Qmax is 0.48 W / cm 2 , which has a relatively high contact cooling sensation and cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0065] Example 5

[0066] The ratio of the sum of the number of screw conveying elements and mixing elements to the number of shear elements used in the screw extruder is 7. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength and high-modulus polyethylene fibers.

[0067] The high-cooling-sensation high-strength and high-modulus polyethylene fibers obtained in Example 5 have relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0068] For the woven fabric specimen made of the high-cooling-sensation high-strength and high-modulus polyethylene fibers obtained in Example 5, the measured contact cooling sensation Qmax is 0.47 W / cm 2 , which has a relatively high contact cooling sensation and cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0069] Example 6

[0070] The spinneret plate in the spinning box is a two-layer combined spinneret plate. Among them, the bottommost spinneret plate contains spinneret holes with a length-diameter ratio of 14 and a pore diameter of 0.4 mm, and the first deflector plate from bottom to top contains deflector holes with a length-diameter ratio of 9 and a pore diameter of 0.8. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength and high-modulus polyethylene fibers.

[0071] The high-cooling-sensation high-strength and high-modulus polyethylene fibers obtained in Example 6 have relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0072] For the woven fabric specimen made of the high-cooling-sensation high-strength and high-modulus polyethylene fibers obtained in Example 6, the measured contact cooling sensation Qmax is 0.46 W / cm 2 , which has a relatively high contact cooling sensation and cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0073] Examples 7 and 8

[0074] The spinneret in the spinning box is a 3-layer combined spinneret. Among them, the bottom-layer spinneret contains spinneret holes with an aspect ratio of 15 (Example 7) or 10 (Example 8) and a pore diameter of 0.4 mm. All other steps are carried out according to the raw materials and methods of Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0075] The high-cooling-sensation high-strength high-modulus polyethylene fibers obtained in Examples 7 and 8 have relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0076] The woven fabric test pieces made of the high-cooling-sensation high-strength high-modulus polyethylene fibers obtained in Examples 7 and 8 have a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 2 shown.

[0077] Example 9

[0078] The spinneret in the spinning box is a 3-layer combined spinneret. Among them, the bottom-layer spinneret contains spinneret holes with an aspect ratio of 10 and a pore diameter of 0.5 mm. All other steps are carried out according to the raw materials and methods of Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0079] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Example 9 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0080] The woven fabric test pieces made of the high-cooling-sensation high-strength high-modulus polyethylene fibers obtained in Example 9 have a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0081] Examples 10 and 11

[0082] The spinneret in the spinning box is a 3-layer combined spinneret. Among them, the first flow guide plate from bottom to top contains flow guide holes with an aspect ratio of 10 (Example 10) or 5 (Example 11) and a pore diameter of 0.8 mm. All other steps are carried out according to the raw materials and methods of Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0083] The high-cooling-sensation high-strength high-modulus polyethylene fibers obtained in Examples 10 and 11 have relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0084] The woven fabric test pieces made of the high-cooling-sensation high-strength high-modulus polyethylene fibers obtained in Examples 10 and 11 have a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0085] Example 12

[0086] The spinneret in the spinning box is a three-layer combined spinneret. Among them, the first flow guide plate from bottom to top contains flow guide holes with a length-diameter ratio of 7 and a pore diameter of 1.0 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation, high-strength, and high-modulus polyethylene fiber.

[0087] The high-cooling-sensation, high-strength, and high-modulus polyethylene fiber obtained in Example 12 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0088] The woven fabric test piece made of the high-cooling-sensation, high-strength, and high-modulus polyethylene fiber obtained in Example 12 has a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0089] Examples 13 and 14

[0090] The spinneret in the spinning box is a three-layer combined spinneret. Among them, the third flow guide plate from bottom to top contains flow guide holes with a length-diameter ratio of 8 (Example 13) or 3 (Example 14) and a pore diameter of 1.15 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation, high-strength, and high-modulus polyethylene fiber.

[0091] The high-cooling-sensation, high-strength, and high-modulus polyethylene fiber obtained in Examples 13 and 14 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0092] The woven fabric test piece made of the high-cooling-sensation, high-strength, and high-modulus polyethylene fiber obtained in Examples 13 and 14 has a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0093] Example 15

[0094] The spinneret in the spinning box is a three-layer combined spinneret. Among them, the third flow guide plate from bottom to top contains flow guide holes with a length-diameter ratio of 5 and a pore diameter of 1.3 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation, high-strength, and high-modulus polyethylene fiber.

[0095] The high-cooling-sensation, high-strength, and high-modulus polyethylene fiber obtained in Example 15 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus.

[0096] The woven fabric test piece made of the high-cooling-sensation, high-strength, and high-modulus polyethylene fiber obtained in Example 15 has a relatively high contact cooling sensation, which cannot be achieved by conventional wet or dry spinning, as well as ordinary melt spinning. The results are as Figure 1 shown.

[0097] Comparative Example 1

[0098] Using the wet spinning method, a ultra-high molecular weight polyethylene raw material with an intrinsic viscosity of 5.5 dl / g and a ratio of weight average molecular weight to number average molecular weight (Mw / Mn) of 7.5 is dissolved in an organic solvent, extruded through a screw extruder, filtered through a filter, and then extruded into filaments through a spinneret. After being cooled in a water bath, stretched, and dried, high-strength and high-modulus polyethylene fibers are obtained.

[0099] For the high-cooling-sensation, high-strength and high-modulus polyethylene fibers obtained in Comparative Example 1, as Figure 4 shown, pores are observed on the surface. The woven fabric test pieces made thereof have a lower contact cooling sensation and a narrow application range.

[0100] Comparative Example 2

[0101] Using a ultra-high molecular weight polyethylene raw material with a property of 2.0 dl / g and a ratio of weight average molecular weight to number average molecular weight (Mw / Mn) of 4.5, and obtaining the finished polyethylene fibers by all other methods according to Example 1. The polyethylene fibers obtained in Comparative Example 2 have lower breaking strength and elastic modulus. The results are as Figure 2 shown.

[0102] Comparative Example 3

[0103] Using a ultra-high molecular weight polyethylene raw material with a property of 10.5 dl / g and a ratio of weight average molecular weight to number average molecular weight (Mw / Mn) of 10.5, and obtaining the finished polyethylene fibers by all other methods according to Example 1. The polyethylene fibers obtained in Comparative Example 3 have lower breaking strength and elastic modulus, and have poor spinnability, more broken filaments, and poor continuous productivity. The results are as Figure 2 shown.

[0104] Comparative Example 4

[0105] When a heavy-duty gearbox with a gearbox torque rating of 10 is used for the screw extruder, and all other raw materials and methods are according to Example 1, it is found that screw extrusion is difficult, continuous extrusion cannot be carried out, and the spinnability is poor.

[0106] Comparative Example 5

[0107] The ratio of the sum of the number of screw conveying elements and mixing elements to the number of shear elements used for the screw element of the screw extruder is 4, and the finished polyethylene fibers are obtained by all other raw materials and methods according to Example 1.

[0108] The polyethylene fibers obtained in Comparative Example 5 have lower breaking strength and elastic modulus. The results are as Figure 2 shown.

[0109] Comparative Example 6

[0110] The spinneret in the spinning box is a 1-layer combined spinneret, and the spinneret contains spinneret holes with a length-to-diameter ratio of 20 and a pore diameter of 0.4 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0111] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 6 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, due to the large length-to-diameter ratio, the pressure of the spinning assembly is extremely high and rises rapidly, making it impossible to produce continuously for 24 hours, and the spinnability is poor.

[0112] Comparative Examples 7 and 8

[0113] The spinneret in the spinning box is a 3-layer combined spinneret. Among them, the bottom-layer spinneret contains spinneret holes with a length-to-diameter ratio of 16 (Comparative Example 7) or 4 (Comparative Example 8) and a pore diameter of 0.4 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0114] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 7 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, due to the large length-to-diameter ratio, the pressure of the spinning assembly is extremely high and rises rapidly, making it impossible to produce continuously for 24 hours, and the spinnability is poor.

[0115] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 8 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, the contact cooling sensation of the woven fabric test piece made of the high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Example 8 is relatively low, and the application range is relatively narrow. The results are as Figure 2 shown.

[0116] Comparative Example 9

[0117] The spinneret in the spinning box is a 3-layer combined spinneret. Among them, the bottom-layer spinneret contains spinneret holes with a length-to-diameter ratio of 10 and a pore diameter of 0.6 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished polyethylene fiber.

[0118] In Comparative Example 9, due to the relatively large pore diameter of the spinneret holes, it is not conducive to fiber formation, there are many broken filaments, and the spinnability is poor. The obtained polyethylene fiber has relatively low breaking strength and elastic modulus. The results are as Figure 2 shown.

[0119] Comparative Examples 10 and 11

[0120] The spinneret in the spinning box is a 3-layer combined spinneret. Among them, the first flow guide plate from bottom to top contains flow guide holes with a length-to-diameter ratio of 11 (Comparative Example 10) or 4 (Comparative Example 11) and a pore diameter of 0.8 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0121] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 10 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, due to its relatively large aspect ratio, the pressure of the spinning pack is extremely high and increases rapidly, making it impossible to continuously produce for 24 hours, and its spinnability is poor.

[0122] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 11 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, the contact cooling sensation of the woven fabric test piece made of the high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 11 is relatively low, and its application range is relatively narrow.

[0123] Comparative Example 12

[0124] The spinneret in the spinning box is a three-layer combined spinneret. Among them, the first flow guide plate from bottom to top contains a flow guide hole with an aspect ratio of 7 and a pore diameter of 1.1 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0125] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 12 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, the contact cooling sensation of the woven fabric test piece made of the high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 12 is relatively low, and its application range is relatively narrow. The results are as Figure 2 shown.

[0126] Comparative Examples 13 and 14

[0127] The spinneret in the spinning box is a three-layer combined spinneret. Among them, the third flow guide plate from bottom to top contains a flow guide hole with an aspect ratio of 9 (Example 13) or 2 (Example 14) and a pore diameter of 1.15 mm. All other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0128] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 13 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, due to its relatively large aspect ratio, the pressure of the spinning pack is extremely high and increases rapidly, making it impossible to continuously produce for 24 hours, and its spinnability is poor.

[0129] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 14 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, the contact cooling sensation of the woven fabric test piece made of the high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 14 is relatively low, and its application range is relatively narrow. The results are as Figure 2 shown.

[0130] Comparative Example 15

[0131] The spinneret in the spinning box is a three-layer combined spinneret. Among them, the third-layer flow guide plate from bottom to top contains flow guide holes with an aspect ratio of 5 and a pore diameter of 1.4 mm. All the other raw materials and methods are the same as those in Example 1 to obtain the finished high-cooling-sensation high-strength high-modulus polyethylene fiber.

[0132] The high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 15 has relatively high breaking strength and elastic modulus, meeting the characteristics of high strength and high modulus. However, for the woven fabric test piece made of the high-cooling-sensation high-strength high-modulus polyethylene fiber obtained in Comparative Example 15, the contact cooling sensation is relatively low and the application range is relatively narrow. The results are as Figure 2 shown.

Claims

1. A preparation method of high-cooling-sensation high-strength and high-modulus polyethylene fiber, characterized in that The invention comprises the following steps: high molecular weight polyethylene raw material is melt-transported by a low shear and high conveying screw extruder, and then enters a spinning assembly with a combined spinneret; the combined spinneret is used to orient polyethylene melt macromolecules and release the elastic potential energy of the melt, and extrude the fibers to obtain nascent fibers; the nascent fibers are subjected to multi-stage stretching and heat setting to obtain finished high-cooling high-strength and high-modulus polyethylene fibers; the structure of the combined spinneret is a spinneret, a first guide plate and a second guide plate which are sequentially bonded from outside to inside; wherein the spinneret has spinneret holes with an aspect ratio of 5 to 15 and an aperture of less than 0.5 mm; the first guide plate has a first guide hole with an aspect ratio of 10 to 5, an aperture of less than 1.0 mm and a larger aperture than the bottom spinneret hole; the second guide plate contains a second guide hole with an aspect ratio of 8 to 3, an aperture of less than 1.3 mm and a larger aperture than the first guide hole.

2. The preparation method of the high-cooling-sensation high-strength and high-modulus polyethylene fiber according to claim 1, wherein: The high molecular weight polyethylene has an intrinsic viscosity of 3.5-10 dl / g, and a ratio of weight average molecular weight to number average molecular weight (Mw / Mn) of 5-10.

3. The preparation method of the high-cooling-sensation high-strength and high-modulus polyethylene fiber according to claim 1, wherein: The screw extruder is connected to a heavy-duty gearbox with a high torque output whose output torque level reaches 11T / A3 or above; and the screw extruder has a conveying element, a mixing element, and a shearing element, wherein the sum of the number of the conveying elements and the mixing elements is more than 5 times the number of the shearing elements; thereby achieving the low shear and high conveying characteristics, while ensuring smooth spinning without destroying the molecular structure of the high molecular weight polyethylene as much as possible.

4. The preparation method of the high-cooling-sensation high-strength and high-modulus polyethylene fiber according to claim 1, wherein: The multi-stage stretching process of the nascent fiber is as follows: the first-stage stretching is cold stretching, at a temperature below 40°C, stretching is 2 to 4 times; the second-stage stretching is hot stretching, at a temperature of 110 to 140°C, stretching is 2 to 10 times; the third-stage stretching is a heat setting process, at a temperature of 110 to 140°C, stretching is 0.9 to 1.1 times.

5. A high-cooling-sensation high-strength and high-modulus polyethylene fiber, characterized in that: Prepared by the method for preparing high-cooling-sensation high-strength and high-modulus polyethylene fiber according to any one of claims 1-4, the contact cooling sensation Qmax of the high-cooling-sensation high-strength and high-modulus polyethylene fiber is 0.4 W / cm 2 or more; the fiber breaking strength is 10 cN / dtex or more, the elastic modulus is 400 cN / dtex or more, and the breaking elongation rate is 6% or less; the intrinsic viscosity of the fiber is 1.5-10 dl / g.

Images