Multi-stage evaporative manufacturing method of ultra-high molecular weight polyethylene monofilament and application of ultra-high molecular weight polyethylene monofilament

Abstract

The invention relates to a multi-stage evaporative manufacturing method and application of an ultra-high molecular weight polyethylene monofilament. The manufacturing method of the ultra-high molecular weight polyethylene monofilament comprises the following steps: 1) mixing ultra-high molecular weight polyethylene and a solvent to prepare a spinning solution, 2) extruding the spinning solution to pass through a spinneret plate provided with at least one spinneret orifice to form a spinning trickle, and 3) drying the spinning trickle to obtain the ultra-high molecular weight polyethylene monofilament. 3) drawing the spinning trickle at a first ambient temperature higher than the boiling point of the solvent, removing a portion of the solvent from the spinning trickle until the content of the solvent in the spinning trickle is 20000 ppm or less to obtain a dry precursor, and 4) in the presence or absence of drawing, removing a portion of the solvent from the spinning trickle until the content of the solvent in the spinning trickle is 20000 ppm or less to obtain the dry precursor. And basically completely removing the solvent from the dry precursor at a second environment temperature lower than the first environment temperature to obtain the ultra-high molecular weight polyethylene monofilament. The residual quantity of the spinning solvent of the ultra-high molecular weight polyethylene monofilament is very low.

Description

Technical Field

[0001] The present invention relates to the field of high-performance fibers, and specifically, to a multi-stage evaporation manufacturing method and application of ultra-high molecular weight polyethylene monofilaments. Background Art

[0002] Ultra-high molecular weight polyethylene has good biocompatibility due to its simple structure and consisting of only C and H elements, and is an important medical material for implantable medical devices, usually used as a building product or fiber braided wire. Ultra-high molecular weight polyethylene resin has a high molecular weight and needs to be dissolved in a solvent for spinning to form fibers, but the residual solvent usually affects the purity of the material itself. For example, decalin solvent, due to its good solubility characteristics, will dissolve cell walls and cause the failure of cytotoxicity detection. Therefore, extremely low solvent residue is the key to ensuring the application of ultra-high molecular weight polyethylene fibers in medical devices. Summary of the Invention

[0003] Existing ultra-high molecular weight polyethylene fiber spinning technologies usually use the gel spinning method, which removes the solvent by one-stage evaporation. It is difficult to achieve a solvent residue of ≤100 ppm by this method. The spinning process of the present invention uses a dry-state solidification method different from the conventional gel spinning method for ultra-high molecular weight polyethylene fibers. There is no cooling gel process during spinning and forming, and no gel-state primary filaments are formed. It directly enters the flash solidification stage to form dry-state primary filaments, and then reaches an extremely low level of solvent residue through multi-stage evaporation to ensure the cleanliness of the product.

[0004] Specifically, the present invention relates to the following aspects.

[0005] 1. A manufacturing method of ultra-high molecular weight polyethylene monofilaments, comprising the following steps:

[0006] 1) Mix ultra-high molecular weight polyethylene and a solvent to make a spinning solution.

[0007] 2) Extrude the spinning solution through a spinneret provided with at least one (such as 30 - 200) spinneret holes to form a spinning stream.

[0008] 3) Stretch the spinning stream (initial stretching) at a first ambient temperature higher than the boiling point of the solvent (preferably 0.1 - 5 °C or 0.5 - 2 °C higher than the boiling point of the solvent) to remove a part of the solvent from the spinning stream until the content of the solvent in the spinning stream is below 20000 ppm (preferably below 10000 ppm or below 1000 ppm, but above 100 ppm or above 500 ppm) to obtain dry-state filaments.

[0009] 4) In the presence or absence of stretching, at a second ambient temperature lower than the first ambient temperature (such as 10 - 150 °C lower, preferably 50 - 100 °C lower), substantially all of the solvent is removed from the dry filament (such as until the content of the solvent in the dry filament is 10 ppm or less, 1 ppm or less), to obtain the ultra-high molecular weight polyethylene monofilament (as-extruded monofilament).

[0010] 2. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 1), based on 100 parts by weight of the ultra-high molecular weight polyethylene, the amount of the solvent used is at most 2000 parts by weight (preferably 1000 - 1500 parts by weight).

[0011] 3. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 1), the solvent is selected from at least one of white oil, mineral oil, naphthalene, decalin, tetralin, kerosene, xylene, toluene, petroleum fraction, halogenated hydrocarbon, cycloalkane, cycloolefin, preferably decalin.

[0012] 4. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 1), the viscosity-average molecular weight of the ultra-high molecular weight polyethylene is from 1 million to 9 million (preferably 3 million - 7 million).

[0013] 5. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 2), the extrusion temperature is 150 - 220 °C (preferably 170 - 180 °C), the extrusion speed is 2 - 20 m / min (3 - 5 m / min), and / or, the equivalent circular diameter of the cross-section of the spinneret hole is 0.1 - 3 mm (preferably 0.5 - 1.5 mm), and / or, when multiple are provided, the multiple spinneret holes are annularly distributed on the spinneret plate.

[0014] 6. The manufacturing method according to any one of the foregoing or following aspects, wherein after the spinning stream exits the spinneret plate, step 3) is immediately carried out.

[0015] 7. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 3), the initial stretching causes the cross-sectional shrinkage rate of the spinning stream to be 10 - 10 6 (preferably 100 - 1000), and / or, the stretching ratio of the initial stretching is 1 - 15 (preferably 6 - 8), and / or, the first ambient temperature is ≤ 250 °C (preferably 190 - 200 °C), and / or, the second ambient temperature is 30 - 150 °C (preferably 50 - 120 °C).

[0016] 8. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), purge air is provided to the spinning stream from one side, both sides, or in a surrounding manner of the spinning stream, preferably providing the purge air in a continuous or evenly spaced manner around the spinning stream.

[0017] 9. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), the operating conditions include: the temperature of the purge air is ≥140 °C (preferably 145 - 160 °C), and the (total) flow rate of the purge air is 80 - 500 Nm 3 (preferably 100 - 300 Nm 3 ).

[0018] 10. The manufacturing method described in any of the foregoing or following aspects further includes an additional step: after step 3) and before step 4) starts, cooling the dry raw filament in one or more stages (such as 1 - 8 or 2 - 5 stages) at a temperature 1 - 120 °C lower (preferably 30 - 50 °C lower) than the melting point of the dry raw filament.

[0019] 11. The manufacturing method described in any of the foregoing or following aspects, wherein in the additional step, there is or is no stretching; if there is stretching, the stretching ratio is 1 - 15 (preferably 5 - 12).

[0020] 12. The manufacturing method described in any of the foregoing or following aspects, wherein in step 4), the operating conditions include: the dry raw filament is not wound up, the residence time is 1 - 120 min (preferably 10 - 20 min), and the stretching ratio is 1 - 10 (preferably 3 - 8).

[0021] 13. The manufacturing method described in any of the foregoing or following aspects, wherein after step 4) ends, the nascent monofilament is stretched in one or more stages (such as 1 - 8 or 2 - 5 stages) (referred to as post - stretching).

[0022] 14. The manufacturing method described in any of the foregoing or following aspects, wherein the operating conditions of the post - stretching include: the stretching temperature is 90 - 160 °C (preferably 130 - 150 °C), and the (total) stretching ratio is 2 - 200 (preferably 10 - 30).

[0023] 15. A ultra - high molecular weight polyethylene monofilament obtained by the manufacturing method described in any of the foregoing or following aspects, having a spinning solvent content of 20000 ppm or less (preferably 10000 ppm or less, more preferably 100 ppm or less, 10 ppm or less, 1 ppm or less, or not detected).

[0024] 16. The ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects has a monofilament fineness of 0.5 - 5 dtex (preferably 0.6 - 2.5 dtex) and a fiber strength of ≥ 28 cN / dtex (preferably 30 - 40 cN / dtex).

[0025] 17. A fiber product (preferably a medical product such as a medical suture) comprises the ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects or is made of the ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects. Description of the Drawings

[0026] Figure 1 is the infrared spectrum of the ultra-high molecular weight polyethylene fiber of the present invention.

[0027] Figure 2 is the infrared spectrum of a conventional ultra-high molecular weight polyethylene fiber.

[0028] Technical Effects

[0029] The ultra-high molecular weight polyethylene fiber of the present invention has no residual solvent, no characteristic peak of decalin in infrared spectrum detection, high fiber strength, pure components, and meets medical requirements. Detailed Description of the Invention

[0030] The following is a detailed description of the specific embodiments of the present invention. However, it should be noted that the protection scope of the present invention is not limited by these specific embodiments, but is determined by the appended claims.

[0031] All publications, patent applications, patents and other references mentioned in this specification are hereby incorporated by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0032] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art" or their similar terms to derive materials, substances, methods, steps, devices or components, etc., the objects derived by such prefixes cover those commonly used in the art at the time when this application is filed, but also include those that are not commonly used at present but will become commonly recognized in the art as suitable for similar purposes.

[0033] In the context of the present invention, all numerical values of parameters (e.g., quantities or conditions) should be understood to be modified by the term "about" in all cases, whether or not "about" actually appears before the numerical value.

[0034] In the context of the present invention, "substantially" means allowing deviations that are acceptable or considered reasonable to those skilled in the art, such as within ±5%, within ±1%, within ±0.5%, or within ±0.1%.

[0035] In the context of the present invention, the measurement method for the solvent content is GB / T41671-2022.

[0036] In the context of the present invention, the measurement method for the denier of monofilament is GB / T3916-2013.

[0037] In the context of the present invention, the measurement method for the fiber strength is GB / T19975-2005.

[0038] In the context of the present invention, the measurement method for the infrared spectrum is YY_T 0814-2010.

[0039] In the context of the present invention, "not winding up" means maintaining the same state as the previous step, with the fiber in a straightened state and not wound around the bobbin shaft.

[0040] In the context of the present invention, "not detected" means ≤1 ppm.

[0041] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, and the pressure is gauge pressure.

[0042] In the context of the present invention, any two or more embodiments or aspects of the present invention can be arbitrarily combined, and the technical solutions formed thereby belong to a part of the original public content of this specification and also fall within the protection scope of the present invention.

[0043] According to one embodiment of the present invention, it relates to a method for manufacturing ultra-high molecular weight polyethylene monofilaments. According to the present invention, the ultra-high molecular weight polyethylene monofilaments have the characteristics of low residual spinning solvent. The fibers have extremely high purity and meet the biocompatibility requirements for medical use.

[0044] According to one embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene monofilaments includes step 1): mixing ultra-high molecular weight polyethylene and a solvent to prepare a spinning solution.

[0045] According to one embodiment of the present invention, in step 1), relative to 100 parts by weight of the ultra-high molecular weight polyethylene, the amount of the solvent used is at most 2000 parts by weight (preferably 1000-1500 parts by weight).

[0046] According to an embodiment of the present invention, in step 1), the solvent is selected from at least one of white oil, mineral oil, naphthalene, decalin, tetralin, kerosene, xylene, toluene, petroleum fraction, halogenated hydrocarbon, cycloalkane, and cycloolefin, preferably decalin.

[0047] According to an embodiment of the present invention, in step 1), the viscosity-average molecular weight of the ultra-high molecular weight polyethylene is 1 million to 9 million (preferably 3 million - 7 million).

[0048] According to an embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene monofilament includes step 2): extruding the spinning solution through a spinneret provided with at least one (such as 30 - 200) spinneret holes to form a spinning filament stream.

[0049] According to an embodiment of the present invention, in step 2), the extrusion temperature is 150 - 220°C (preferably 170 - 180°C), and the extrusion speed is 2 - 20 m / min (3 - 5 m / min).

[0050] According to an embodiment of the present invention, in step 2), the circular equivalent diameter of the cross-section of the spinneret hole is 0.1 - 3 mm (preferably 0.5 - 1.5 mm). Additionally, when multiple are provided, the multiple spinneret holes are annularly distributed on the spinneret.

[0051] According to an embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene monofilament includes step 3): stretching the spinning filament stream at a first ambient temperature higher than the boiling point of the solvent (preferably 0.1 - 5°C or 0.5 - 2°C higher than the boiling point of the solvent) to remove a part of the solvent from the spinning filament stream until the content of the solvent in the spinning filament stream is 20,000 ppm or less (preferably 10,000 ppm or less or 1,000 ppm or less, but 100 ppm or more or 500 ppm or more), to obtain a dry state raw filament. If the first ambient temperature is too high, the solvent diffusion rate is less than the volatilization rate, and the surface quickly forms a skin and the solvent cannot be completely removed, and the too high temperature also damages the initial fiber. If the first ambient temperature is too low, the solvent volatilizes too slowly, the solvent residue is too large, and even filament formation cannot occur. For example, the first ambient temperature is generally ≤250°C (preferably 190 - 200°C).

[0052] According to an embodiment of the present invention, after the spinning filament stream leaves the spinneret, step 3) is immediately carried out. If it is not carried out immediately, the fiber surface may form a skin and harden due to a sudden temperature drop, resulting in the inability to migrate the internal solvent to the surface for removal.

[0053] According to an embodiment of the present invention, in step 3), the initial stretching causes the cross-sectional shrinkage rate of the spinning stream to be 10-10 6 (preferably 100-1000), or the draw ratio of the initial stretching is 1-15 (preferably 6-8). A high cross-sectional shrinkage rate will cause the solvent to rapidly migrate to the surface. If the shrinkage rate is too low, the solvent migration is insufficient and there is a lot of residue. If the shrinkage rate is too high, the monofilament cannot withstand the high draw ratio and breaks.

[0054] According to an embodiment of the present invention, preferably, in step 3), purge air is provided to the spinning stream from one side, both sides, or in a surrounding manner of the spinning stream, preferably providing the purge air in a continuous or evenly spaced manner around the spinning stream. Preferably, the purge air is provided in a direction at a certain angle (such as 30-150°, preferably 60-120°, particularly preferably substantially 90°) to the direction of the initial stretching. The purge air can, on the one hand, shape the fiber cross-section and increase the specific surface area, and on the other hand, can drive the gas flow in the system and accelerate the solvent volatilization.

[0055] According to an embodiment of the present invention, in step 3), the temperature of the purge air is ≥140°C (preferably 145-160°C), and the (total) flow rate of the purge air is 80-500 Nm 3 (preferably 100-300 Nm 3 ). Excessively high temperature and flow rate will affect the mechanical properties such as the strength of the initial fiber and increase defects. Excessively low temperature and flow rate will cause insufficient solvent volatilization.

[0056] According to an embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene monofilament includes step 4): in the presence or absence of stretching, at a second ambient temperature lower (such as 10-150°C lower, preferably 50-100°C lower) than the first ambient temperature, substantially completely remove the solvent from the dry filament (such as until the content of the solvent in the dry filament is below 10 ppm, below 1 ppm), to obtain the ultra-high molecular weight polyethylene monofilament (as-spun monofilament). This step is to further remove the solvent residue. If the temperature is too high, the fiber will be damaged and the strength will decrease. If the temperature is too low, the solvent volatilization is slow and the effect of fully removing the solvent cannot be achieved. For example, the second ambient temperature is generally 30-150°C (preferably 50-120°C).

[0057] According to an embodiment of the present invention, in step 4), the dry filament is not wound up, and the residence time is 1-120 min (preferably 10-20 min). Without winding up, the fiber is in a straightened state, and the solvent can be removed with the largest cross-section. When stretching is required, the draw ratio is generally 1-10 (preferably 3-5).

[0058] According to an embodiment of the present invention, after the end of step 4), the as-formed monofilament is drawn (referred to as post-drawing) in one or more stages (such as 1-8 or 2-5 stages). Herein, the operating conditions of the post-drawing include: the drawing temperature is 90-160°C (preferably 130-150°C), and the (overall) draw ratio is 2-200 (preferably 10-30).

[0059] According to an embodiment of the present invention, the manufacturing method further includes an additional step. According to this additional step, after the end of step 3) and before the start of step 4), the dry precursor filaments are cooled in one or more stages (such as 1-8 or 2-5 stages) at a temperature 1-120°C lower (preferably 30-50°C lower) than the melting point of the dry precursor filaments. Additionally, in the additional step, there is or there is no drawing; if there is drawing, the draw ratio is 1-15 (preferably 5-12). Cooling solidifies the disentangled and oriented state of the molecular chains and maintains the high strength of the fiber.

[0060] According to an embodiment of the present invention, there is also provided an ultra-high molecular weight polyethylene monofilament obtained by the manufacturing method described in any aspect of the present invention before or after. According to the present invention, the residual amount of the spinning solvent in the ultra-high molecular weight polyethylene monofilament is very low, for example, the solvent content is generally 20,000 ppm or less (preferably 10,000 ppm or less, more preferably 100 ppm or less, 10 ppm or less, 1 ppm or less, or not detected). As Figure 1 and Figure 2 shown, Figure 1 compared Figure 2 with, in the characteristic peak region of decalin (800 cm -1 -1400 cm -1 ), there are no obvious peaks, and decalin has been almost completely removed.

[0061] According to an embodiment of the present invention, the fineness of the monofilament of the ultra-high molecular weight polyethylene monofilament is generally 0.5-5 dtex (preferably 0.6-2.5 dtex), and the fiber strength is generally ≥28 cN / dtex (preferably 30-40 cN / dtex).

[0062] According to an embodiment of the present invention, there is also provided a fiber product, preferably a medical product such as a medical suture, including the ultra-high molecular weight polyethylene monofilament described in any aspect of the present invention before or after or made of the ultra-high molecular weight polyethylene monofilament described in any aspect of the present invention before or after.

[0063] Examples

[0064] The present invention will be further described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0065] Example 1

[0066] The ultra-low solvent residue ultra-high molecular weight polyethylene fiber of this example is obtained through the following process:

[0067] Mix ultra-high molecular weight polyethylene and a solvent to make a spinning solution. The viscosity-average molecular weight of the ultra-high molecular weight polyethylene is 6 million. 100 parts by weight of ultra-high molecular weight polyethylene and 1300 parts by weight of the solvent are used. The solvent is decalin. The above components are mixed to make a spinning solution. The spinning solution is extruded through a spinneret with 50 spinneret holes to form spinning filaments. The extrusion temperature is 175 °C, the extrusion speed is 4 m / min, the cross-sectional shape of the spinneret holes is circular, the diameter is 1 mm, and the spinneret holes are annularly distributed on the spinneret.

[0068] After the spinning solution exits the spinneret holes, it is immediately stretched (initial stretching) at the first ambient temperature of 195 °C. The initial stretching ratio is 7. Purge air is provided circumferentially to the spinning filaments. The temperature of the purge air is 148 °C, and the (total) flow rate of the purge air is 200 Nm 3 , to obtain dry-state raw filaments. The dry-state raw filaments are cooled in one step, the cooling temperature is 80 °C, the stretching ratio is 6, and then the dry-state raw filaments are not wound up and immediately further stretched to remove the solvent at the second ambient temperature of 110 °C. The residence time is 15 min, the stretching ratio is 4, and almost all the solvent in the dry-state raw filaments is removed to obtain ultra-high molecular weight polyethylene monofilaments (nascent monofilaments). The nascent monofilaments are stretched in 3 stages (referred to as post-stretching), the stretching temperature is 145 °C, and the (total) stretching ratio is 20.

[0069] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 0.8 ppm, a monofilament fineness of 1.1 dtex, and a fiber strength of 39 cN / dtex.

[0070] The above monofilaments can be used for medical products such as medical sutures.

[0071] Example 2

[0072] Mix ultra-high molecular weight polyethylene and a solvent to make a spinning solution. The viscosity-average molecular weight of the ultra-high molecular weight polyethylene is 7 million. 100 parts by weight of ultra-high molecular weight polyethylene and 1400 parts by weight of the solvent are used. The solvent is decalin. The above components are mixed to make a spinning solution. The spinning solution is extruded through a spinneret with 50 spinneret holes to form spinning filaments. The extrusion temperature is 180 °C, the extrusion speed is 5 m / min, the cross-sectional shape of the spinneret holes is circular, the diameter is 1.2 mm, and the spinneret holes are annularly distributed on the spinneret.

[0073] After the spinning solution exits the spinneret holes, it is immediately stretched (initial stretching) at a first ambient temperature of 200 °C. The initial stretching ratio is 8. A purge air is provided from one side of the spinning filaments. The temperature of the purge air is 155 °C, and the (total) flow rate of the purge air is 300 Nm 3 , and dry precursor filaments are obtained. The dry precursor filaments are cooled in one step at a cooling temperature of 90 °C with a stretching ratio of 8. Then, the dry precursor filaments are not wound up and are immediately further stretched to remove the solvent at a second ambient temperature of 100 °C with a residence time of 12 min and a stretching ratio of 5. Almost all of the solvent in the dry precursor filaments is removed, and ultra-high molecular weight polyethylene monofilaments (nascent monofilaments) are obtained. The nascent monofilaments are stretched in 3 stages (referred to as post-stretching) at a stretching temperature of 140 °C with a (total) stretching ratio of 30.

[0074] Finally, ultra-high molecular weight polyethylene monofilaments are obtained with a residual solvent content of 0.6 ppm, a monofilament fineness of 0.8 dtex, and a fiber strength of 40 cN / dtex.

[0075] The above monofilaments can be used in medical products such as medical sutures.

[0076] Example 3

[0077] Ultra-high molecular weight polyethylene and a solvent are mixed to prepare a spinning solution. The viscosity-average molecular weight of the ultra-high molecular weight polyethylene is 5 million. 100 parts by weight of ultra-high molecular weight polyethylene and 1200 parts by weight of the solvent are used. The solvent is decalin. The above components are mixed to prepare a spinning solution. The spinning solution is extruded through a spinneret plate provided with 50 spinneret holes to form spinning filaments. The extrusion temperature is 170 °C, the extrusion speed is 3 m / min. The cross-sectional shape of the spinneret holes is circular with a diameter of 0.8 mm, and the spinneret holes are annularly distributed on the spinneret plate.

[0078] After the spinning solution exits the spinneret holes, it is immediately stretched (initial stretching) at a first ambient temperature of 190 °C. The initial stretching ratio is 6. A purge air is provided from one side of the spinning filaments. The temperature of the purge air is 155 °C, and the (total) flow rate of the purge air is 300 Nm 3 , and dry precursor filaments are obtained. The dry precursor filaments are cooled in one step at a cooling temperature of 90 °C with a stretching ratio of 8. Then, the dry precursor filaments are not wound up and are immediately further stretched to remove the solvent at a second ambient temperature of 110 °C with a residence time of 18 min and a stretching ratio of 3. Almost all of the solvent in the dry precursor filaments is removed, and ultra-high molecular weight polyethylene monofilaments (nascent monofilaments) are obtained. The nascent monofilaments are stretched in 3 stages (referred to as post-stretching) at a stretching temperature of 130 °C with a (total) stretching ratio of 12.

[0079] Finally, ultra-high molecular weight polyethylene monofilaments are obtained with a residual solvent content of 3 ppm, a monofilament fineness of 1.5 dtex, and a fiber strength of 33 cN / dtex.

[0080] The above monofilaments can be used in medical products such as medical sutures.

[0081] Example 4

[0082] Same as Example 1, except that the first ambient temperature is 210 °C.

[0083] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 10 ppm, a monofilament fineness of 2.2 dtex, and a fiber strength of 29 cN / dtex.

[0084] Example 5

[0085] Same as Example 1, except that the draw ratio at the second ambient temperature is 0.

[0086] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 25 ppm, a monofilament fineness of 2.2 dtex, and a fiber strength of 30 cN / dtex.

[0087] Example 6

[0088] Same as Example 1, except that the second ambient temperature is 160 °C.

[0089] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 20 ppm, a monofilament fineness of 1.5 dtex, and a fiber strength of 28 cN / dtex.

[0090] Example 7

[0091] Same as Example 1, except that after the spinning solution exits the spinneret, it first passes through an air layer and then enters the first temperature zone.

[0092] Finally, a severe shell layer is formed on the fiber surface, and the decalin inside cannot escape, resulting in the inability to form fibers.

[0093] Example 8

[0094] Same as Example 1, except that the initial draw ratio is 3.

[0095] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 1350 ppm, a monofilament fineness of 3.3 dtex, and a fiber strength of 22 cN / dtex.

[0096] Example 9

[0097] Same as Example 1, except that the initial draw ratio is 13.

[0098] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 1135 ppm, a monofilament fineness of 1.0 dtex, and a fiber strength of 25 cN / dtex.

[0099] Example 10

[0100] Same as Example 1, except that there is no purge air.

[0101] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 15070 ppm, a monofilament fineness of 3.0 dtex, and a fiber strength of 14 cN / dtex.

[0102] Example 11

[0103] Same as Example 1, except that purge air is provided from both sides.

[0104] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 90 ppm, a monofilament fineness of 2.1 dtex, and a fiber strength of 28 cN / dtex.

[0105] Example 12

[0106] Same as Example 1, except that purge air is provided from one side.

[0107] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 95 ppm, a monofilament fineness of 2.1 dtex, and a fiber strength of 26 cN / dtex.

[0108] Example 13

[0109] Same as Example 1, except that the purge air temperature is 170 °C.

[0110] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 21 ppm, a monofilament fineness of 1.5 dtex, and a fiber strength of 24 cN / dtex.

[0111] Example 14

[0112] Same as Example 1, except that the purge air temperature is 120 °C.

[0113] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 5315 ppm, a monofilament fineness of 1.5 dtex, and a fiber strength of 20 cN / dtex.

[0114] Example 15

[0115] Same as Example 1, except that the purge air flow rate is 500 Nm 3 .

[0116] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 16 ppm, a monofilament fineness of 1.1 dtex, and a fiber strength of 18 cN / dtex.

[0117] Example 16

[0118] Same as Example 1, except that the purge air flow rate is 50 Nm 3 .

[0119] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 18750 ppm, a monofilament fineness of 2.5 dtex, and a fiber strength of 12 cN / dtex.

[0120] Example 17

[0121] Same as Example 1, except that there is no cooling step.

[0122] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 15 ppm, a monofilament fineness of 1.1 dtex, and a fiber strength of 23 cN / dtex.

[0123] Example 18

[0124] Same as Example 1, except that the dry tow is wound up.

[0125] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 3560 ppm, a monofilament fineness of 2.1 dtex, and a fiber strength of 23 cN / dtex.

[0126] Example 19

[0127] Same as Example 1, except that the residence time is 100 min.

[0128] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 3 ppm, a monofilament fineness of 1.1 dtex, and a fiber strength of 29 cN / dtex.

[0129] Example 20

[0130] Same as Example 1, except that the total draw ratio of the multifilament is 5.

[0131] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 2.7 ppm, a monofilament fineness of 3.4 dtex, and a fiber strength of 25 cN / dtex.

[0132] Comparative Example 1

[0133] Same as Example 1, except that there is no solvent removal process at the first ambient temperature.

[0134] Finally, dry raw filaments cannot be obtained, resulting in the inability to form fibers.

[0135] Comparative Example 2

[0136] Same as Example 1, except that after removing the solvent at the first ambient temperature, the solvent residue is more than 40,000 ppm.

[0137] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 32,113 ppm, a monofilament fineness of 2.1 dtex, and a fiber strength of 11 cN / dtex.

[0138] Comparative Example 3

[0139] Same as Example 1, except that after removing the solvent at the first ambient temperature, the solvent residue is 0.

[0140] Finally, ultra-high molecular weight polyethylene monofilaments are obtained, with a residual solvent content of 0 ppm, a monofilament fineness of 1.1 dtex, and a fiber strength of 18 cN / dtex. There are many hairy filaments during the subsequent drawing process of the fiber, making it difficult to draw.

[0141] Comparative Example 4

[0142] Same as Example 1, except that when removing the solvent at the first ambient temperature, the initial draw ratio is 0.

[0143] Ultra-high molecular weight polyethylene fibers are obtained with a residual solvent content of 13,485 ppm, a monofilament fineness of 1.5 dtex, and a fiber strength of 15 cN / dtex.

[0144] Comparative Example 5

[0145] Same as Example 1, except that the first ambient temperature is 150 °C.

[0146] Ultra-high molecular weight polyethylene fibers are obtained with a residual solvent content of 13,956 ppm, a monofilament fineness of 1.5 dtex, and a fiber strength of 14 cN / dtex.

[0147] Comparative Example 6

[0148] This example is a gel process. Ultra-high molecular weight polyethylene fibers are obtained with a residual solvent content of 206 ppm, a monofilament fineness of 3.0 dtex, and a fiber strength of 30 cN / dtex.

[0149] Comparative Example 7

[0150] Same as Example 1, except that there is no solvent removal process at the second ambient temperature.

[0151] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 117 ppm, the denier per filament is 1.5 dtex, and its fiber strength is 32 cN / dtex.

[0152] Comparative Example 8

[0153] Same as Example 1, except that the second ambient temperature is 5 °C higher than the first ambient temperature.

[0154] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 1 ppm, the denier per filament is 1.1 dtex, and its fiber strength is 21 cN / dtex.

Claims

1. A manufacturing method of ultra-high molecular weight polyethylene monofilament, comprising the following steps: 1) Mix ultra-high molecular weight polyethylene and a solvent to prepare a spinning solution, 2) Extrude the spinning solution through a spinneret provided with at least one (such as 30 - 200) spinneret holes to form a spinning filament stream, 3) Perform stretching (initial stretching) on the spinning filament stream at a first ambient temperature higher than the boiling point of the solvent (preferably 0.1 - 5 °C or 0.5 - 2 °C higher than the boiling point of the solvent), and remove a part of the solvent from the spinning filament stream until the content of the solvent in the spinning filament stream is below 20,000 ppm (preferably below 10,000 ppm or below 1,000 ppm, but above 100 ppm or above 500 ppm) to obtain a dry raw filament, 4) In the presence or absence of stretching, at a second ambient temperature lower than the first ambient temperature (such as 10 - 150 °C lower, preferably 50 - 100 °C lower), substantially completely remove the solvent from the dry raw filament (such as until the content of the solvent in the dry raw filament is below 10 ppm, below 1 ppm) to obtain the ultra-high molecular weight polyethylene monofilament (nascent monofilament).

2. The manufacturing method according to claim 1, wherein in step 2), the extrusion temperature is 150 - 220 °C (preferably 170 - 180 °C), the extrusion speed is 2 - 20 m / min (3 - 5 m / min), and / or, the circular equivalent diameter of the cross-section of the spinneret hole is 0.1 - 3 mm (preferably 0.5 - 1.5 mm), and / or, when multiple are provided, the multiple spinneret holes are annularly distributed on the spinneret.

3. The manufacturing method according to claim 1, wherein the step 3) is immediately performed after the spinning filament stream leaves the spinneret.

4. The manufacturing method according to claim 1, wherein in step 3), the initial stretching causes the cross-sectional shrinkage rate of the spun filament stream to be 10 - 10 6 (preferably 100 - 1000), and / or the stretching ratio of the initial stretching is 1 - 15 (preferably 6 - 8), and / or the first ambient temperature is ≤ 250°C (preferably 190 - 200°C), and / or the second ambient temperature is 30 - 150°C (preferably 50 - 120°C).

5. The manufacturing method according to claim 1, wherein in step 3), purge air is provided to the spinning filament stream from one side, both sides, or in a surrounding manner, preferably providing the purge air in a continuous or evenly spaced manner around the spinning filament stream.

6. The manufacturing method according to claim 5, wherein the temperature of the purging air is ≥ 140 °C (preferably 145 - 160 °C), and the (total) flow rate of the purging air is 80 - 500 Nm 3 (preferably 100 - 300 Nm 3 ).

7. The manufacturing method according to claim 1 further comprises an additional step: after the end of step 3) and before the start of step 4), cooling the dry raw filament in one or more stages (such as 1 - 8 or 2 - 5 stages) at a temperature 1 - 120 °C lower than the melting point of the dry raw filament (preferably 30 - 50 °C lower).

8. The manufacturing method according to claim 7, wherein in the additional step, there is stretching or no stretching; if there is stretching, the stretching ratio is 1 - 15 (preferably 5 - 12).

9. The manufacturing method according to claim 1, wherein in step 4), the operating conditions include: the dry raw filament is not wound up, the residence time is 1 - 120 min (preferably 10 - 20 min), and the stretching ratio is 1 - 10 (preferably 3 - 8).

10. A ultra-high molecular weight polyethylene monofilament obtained by the manufacturing method described in claim 1, having a spinning solvent content of 20,000 ppm or less (preferably 10,000 ppm or less, more preferably 100 ppm or less, 10 ppm or less, 1 ppm or less, or not detected).

11. A fiber product (preferably a medical product such as a medical suture), comprising the ultra-high molecular weight polyethylene monofilament described in claim 10 or made of the ultra-high molecular weight polyethylene monofilament described in claim 10.

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