Manufacturing method and application of ultra-high molecular weight polyethylene fine denier filament

Abstract

The invention relates to a manufacturing method and application of ultra-high molecular weight polyethylene fine denier filaments. 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, 3) stretching the spinning trickle at an ambient temperature higher than the boiling point of the solvent, substantially completely removing the solvent from the spinning trickle to obtain a dry precursor having longitudinal grooves on the side, 4) in the presence or absence of stretching, blowing air is provided for the dry-state precursor through at least one slit-shaped air outlet, so that the dry-state precursor is split along the longitudinal grooves, and the ultra-high molecular weight polyethylene monofilament is obtained. The ultra-high molecular weight polyethylene monofilament has the advantages of being extremely fine in fineness, soft and high in strength.

Description

Technical Field

[0001] The present invention relates to the field of high-performance fibers, and particularly to a manufacturing method and application of ultra-high molecular weight polyethylene fine denier filaments. Background Art

[0002] Ultra-high molecular weight polyethylene fiber is the fiber with the highest specific strength and specific modulus in the world. The surface structure of the fiber is smooth, with high strength, high modulus, and easy to slip when bent and knotted. At present, the single filament fineness of ultra-high molecular weight polyethylene fiber is 1.1 - 3.5 cN / dtex. This is mainly because the ultra-high molecular weight polyethylene has a large molecular weight and a high solution viscosity, making it difficult to directly spin through an ultra-fine spinneret hole. Therefore, fibers with a fineness less than 1 cN / dtex are almost non-existent. In the application of braided threads, especially in medical braided threads, it is not easy to knot, which increases the difficulty of surgical operation. At the same time, due to poor knotting, the medical braided thread becomes stiff, the strength decreases, and the touch is not good, all of which have a negative impact on the treatment effect. Summary of the Invention

[0003] The spinning process of the present invention adopts 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 nascent filaments are formed. Instead, it directly enters the flash solidification stage to form dry-state nascent filaments. By splitting the fibers at the dry-state nascent filament stage, an extremely low fineness is achieved, so that the braided thread has a super soft texture, the knotting strength is improved, and the woven patch has a better touch and conformability.

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

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

[0006] 1) Mixing ultra-high molecular weight polyethylene and a solvent to prepare a spinning solution;

[0007] 2) Extruding the spinning solution through a spinneret plate provided with at least one (such as 10 - 200) spinneret holes to form a spinning stream, wherein the cross-section of the spinneret hole is in the shape of a concave polygon (preferably selected from at least one of dumbbell shape, cross shape, star shape, and serrated shape);

[0008] 3) Stretching the spinning stream at an 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) (initial stretching), and substantially completely removing the solvent from the spinning stream (such as until the content of the solvent in the spinning stream is below 20000 ppm, preferably below 10000 ppm, more preferably below 100 ppm or below 10 ppm) to obtain dry filaments with longitudinal grooves on the side;

[0009] 4) With or without stretching, purge air (referred to as lateral purge air) is provided to the dry raw filaments through at least one (such as 2 - 100, preferably 50 - 80) slit-shaped air outlets, causing the dry raw filaments to split along the longitudinal grooves to obtain the ultra-high molecular weight polyethylene monofilaments (referred to as primary monofilaments).

[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 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 circular equivalent diameter of the cross-section of the spinneret holes is 0.1 - 5 mm (preferably 1 - 3 mm), and / or when multiple are provided, the multiple spinneret holes are linearly distributed on the spinneret plate.

[0014] 6. The manufacturing method according to any one of the foregoing or following aspects, wherein after the spun filaments leave 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 spun filaments to be 10 - 10 6 (preferably 100 - 1000), and / or the draw ratio of the initial stretching is 1 - 10 (preferably 3 - 5), and / or the ambient temperature is ≤ 250 °C (preferably 188 - 210 °C).

[0016] 8. The manufacturing method according to any one of the foregoing or following aspects, wherein step 3) is carried out in a first hollow cylinder, the first hollow cylinder comprising a top opening, a bottom opening, and a side wall (i.e., a housing) connecting the top opening and the bottom opening and formed around the central axis of the first hollow cylinder, the top opening being sealingly connected to the spinneret, the dry raw filament leaving the first hollow cylinder through the bottom opening, and a heating member being provided on at least a part of the side wall to bring the temperature of the inner cavity of the first hollow cylinder to the ambient temperature.

[0017] 9. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 3), a suction power is provided to the bottom opening to enable the solvent to leave the first hollow cylinder in the form of vapor from the bottom opening, and / or, no air flow is input into the first hollow cylinder (for example, no purging air inlet is provided on the side wall).

[0018] 10. The manufacturing method according to any one of the foregoing or following aspects, wherein step 3) is carried out under the condition of substantially no external air flow input (preferably substantially no external lateral air flow input, more preferably no lateral purging air input), and / or, the solvent leaves step 3) in the form of vapor together with the dry raw filament in a direction substantially parallel to the direction of the initial stretching.

[0019] 11. The manufacturing method according to any one of the foregoing or following aspects, wherein step 4) is carried out immediately after the end of step 3).

[0020] 12. The manufacturing method according to any one of the foregoing or following aspects, wherein in step 4), the temperature of the lateral purging air is 0 - 5 °C (preferably 1 - 2 °C) higher than the melting point of the dry raw filament or the temperature of the lateral purging air is ≥ 138 °C (preferably 140 - 150 °C), and / or, in step 4), the linear velocity of the lateral purging air is 0.01 - 10 m / s (preferably 0.2 - 1 m / s), and / or, in step 4), the horizontal distance between the slit-shaped air outlet and the dry raw filament (counting by the center line) is at most 0.1 - 10 cm (preferably at most 0.2 - 1 cm), and / or, in step 4), when stretching exists, the stretching ratio is 1 - 10 (preferably 3 - 5).

[0021] 13. The manufacturing method described in any of the foregoing or following aspects, wherein step 4) is carried out in a second hollow cylinder, the second hollow cylinder comprising a top opening, a bottom opening, and a side wall (i.e., a shell) connecting the top opening and the bottom opening and formed around the central axis of the second hollow cylinder, the top opening communicating with the bottom opening of the first hollow cylinder, the nascent monofilament leaving the second hollow cylinder through the bottom opening of the second hollow cylinder, and at least one slit-shaped air outlet being provided on the side wall of the second hollow cylinder (preferably evenly distributed around the side wall).

[0022] 14. The manufacturing method described in any of the foregoing or following aspects, wherein in step 4), the slit-shaped air outlet is an opening in a long and narrow shape (such as oval or rectangular), the height of the opening being 1 - 10 mm (preferably 3 - 5 mm), the width of the opening being 1 - 100 μm (preferably 3 - 50 μm), the aspect ratio of the height to the width of the opening being 20 - 2000 (preferably 50 - 500), and / or the height direction of the slit-shaped air outlet (i.e., the height direction of the opening) being substantially parallel to the traveling direction of the dry raw filament.

[0023] 15. The manufacturing method described in any of the foregoing or following aspects, wherein in step 4), the lateral purging air is provided via a plurality of (such as 2 - 100, preferably 50 - 80) slit-shaped air outlets evenly spaced around the dry raw filament.

[0024] 16. The manufacturing method described in any of the foregoing or following aspects further comprises step 5): after the end of step 4), cooling the nascent monofilament 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 nascent monofilament; if there is stretching, the stretching ratio is 1 - 30 (preferably 10 - 20).

[0025] 17. The manufacturing method described in any of the foregoing or following aspects, wherein after the end of step 5), the nascent monofilament is stretched in one or more stages (such as 1 - 8 or 2 - 5 stages) (referred to as post-stretching).

[0026] 18. 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 (overall) stretching ratio is 2 - 200 (preferably 10 - 30).

[0027] 19. A ultra-high molecular weight polyethylene monofilament, having a filament fineness of 0.1 - 1 dtex (preferably 0.4 - 0.5 dtex), and a cross-section in a flat shape, wherein the average width of the cross-section is 1 - 60 μm (preferably 5 - 10 μm), the average thickness of the cross-section is 0.1 - 10 μm (preferably 1 - 3 μm), and the ratio of the average width to the average thickness is 2 or more (preferably 5 - 6).

[0028] 20. The ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects, having a fiber strength of 5 - 40 cN / dtex (preferably 15 - 35 cN / dtex), and 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, or 1 ppm or less).

[0029] 21. The ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects, obtained by the manufacturing method described in any of the foregoing or following aspects.

[0030] 22. A fiber product (preferably a medical product such as a medical suture), comprising the ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects or made of the ultra-high molecular weight polyethylene monofilament described in any of the foregoing or following aspects. Description of the Drawings

[0031] Figure 1 is a schematic view of the second hollow cylinder.

[0032] Technical Effects

[0033] The ultra-high molecular weight polyethylene fiber monofilament of the present invention has a filament fineness of 0.33 - 0.55 dtex, and the fiber cross-section is flat, solving the technical problem that due to the high molecular weight of ultra-high molecular weight polyethylene and the high viscosity of the spinning solution, it is impossible to spin with a spinneret having ultra-fine holes. Detailed Description of the Invention

[0034] The following provides 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.

[0035] 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.

[0036] When this specification uses prefixes such as "well-known to those skilled in the art", "prior art", or similar terms to introduce materials, substances, methods, steps, devices, or components, etc., the objects introduced 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 recognized in the art as suitable for similar purposes.

[0037] 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, regardless of whether "about" actually appears before the numerical value.

[0038] In the context of the present invention, the so-called "substantially" means that deviations that are acceptable or considered reasonable to those skilled in the art are allowed, such as deviations within ±5%, within ±1%, within ±0.5%, or within ±0.1%.

[0039] In the context of the present invention, the measuring method for the fineness of monofilament is GB / T3916 - 2013.

[0040] In the context of the present invention, the measuring method for the solvent content is GB / T41671 - 2022.

[0041] In the context of the present invention, the measuring method for the fiber strength is GB / T19975 - 2005.

[0042] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this specification are based on weight, and the pressure is gauge pressure.

[0043] 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.

[0044] According to an embodiment of the present invention, it relates to a method for manufacturing ultra-high molecular weight polyethylene monofilaments.

[0045] According to an embodiment of the present invention, the method for manufacturing ultra-high molecular weight polyethylene monofilaments includes step 1): mixing ultra-high molecular weight polyethylene and a solvent to prepare a spinning solution.

[0046] According to an 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).

[0047] 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, and preferably decalin.

[0048] 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).

[0049] 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 10 - 200) spinneret holes to form a spinning stream.

[0050] According to the present invention, the cross-section of the spinneret hole is in the shape of a concave polygon, preferably selected from at least one of dumbbell shape, cross shape, star shape, and zigzag shape. The spinneret holes with such a cross-sectional shape are mainly for forming a special-shaped cross-section of the fiber during the spinning process, so that there are weak points in the circumferential direction of the fiber cross-section, which is convenient for subsequent air duct cutting to split into ultrafine fibers. According to the present invention, there is no particular limitation on the number of convex angles of the concave polygon, for example, it can be one or more (such as 1 - 10 or 1 - 5), and the present invention also has no particular limitation on the linear distance between the vertex of these convex angles and the center (centroid) of the concave polygon. Even if the center of the concave polygon is outside the concave polygon shape due to the existence of the convex angles, as long as the concave polygon is not basically completely divided into two or more independent shapes due to the existence of these convex angles.

[0051] 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).

[0052] According to an embodiment of the present invention, in step 2), the equivalent circular diameter of the cross-section of the spinneret hole is 0.1 - 5 mm (preferably 1 - 3 mm). Here, when multiple are provided, the multiple spinneret holes are linearly distributed on the spinneret, such as arranged in rows or columns.

[0053] According to an embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene monofilament includes step 3): subjecting the spinning dope stream to stretching (initial stretching) at an 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 substantially completely removing the solvent from the spinning dope stream (for example, until the content of the solvent in the spinning dope stream is 20,000 ppm or less, preferably 10,000 ppm or less, more preferably 100 ppm or less, or 10 ppm or less), to obtain a dry precursor filament having longitudinal grooves on the side surface. This step is mainly to achieve the effect of solidification during the spinning process due to the rapid and substantial evaporation of the solvent, freeze the disentangled state of the fiber macromolecular chains, facilitate subsequent further stretching, and also to more thoroughly remove the solvent to achieve a clean effect. For example, the ambient temperature is generally ≤ 250 °C (preferably 188 - 210 °C).

[0054] According to an embodiment of the present invention, after the spinning dope stream leaves the spinneret, step 3) is immediately carried out. If it is not carried out immediately, the surface of the fiber may crust and harden due to a sudden drop in temperature, resulting in the inability of the internal solvent to migrate to the surface for removal.

[0055] According to an embodiment of the present invention, in step 3), the initial stretching causes the cross-sectional shrinkage rate of the spinning dope stream to be 10 - 10 6 (preferably 100 - 1000), or the draw ratio of the initial stretching is 1 - 10 (preferably 3 - 5). A high cross-sectional shrinkage rate will cause the solvent to quickly 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 high draw ratios and breaks.

[0056] According to an embodiment of the present invention, step 3) is carried out under conditions where there is substantially no external air flow input (preferably substantially no external lateral air flow input, more preferably no lateral purge air input). Under the condition of no air disturbance, the cross-section of the monofilament is isotropic. In the next step of blowing and cracking, the difference between monofilaments will be small, more approaching uniformity, and reducing the unevenness rate. If there is an air disturbance condition, the monofilaments are weaker here and prone to deformation. During the further blowing and cracking process, the unevenness of the monofilament cross-section will be aggravated, ultimately resulting in poor consistency of the fiber. In addition, the solvent leaves step 3) in the form of vapor along a direction substantially parallel to the direction of the initial stretching together with the dry precursor filament.

[0057] According to a preferred embodiment of the present invention, step 3) is carried out in a first hollow cylinder, which includes a top opening, a bottom opening, and a side wall (i.e., a housing) connecting the top opening and the bottom opening and formed around the central axis of the first hollow cylinder. According to the present invention, the top opening is sealingly connected to the spinneret, and the dry raw filament exits the first hollow cylinder through the bottom opening. According to the present invention, a heating member may be provided on at least a part of the side wall to bring the temperature of the inner cavity of the first hollow cylinder to the ambient temperature. Optionally, suction power may also be provided to the bottom opening to enable the solvent to leave the first hollow cylinder in the form of vapor through the bottom opening. Preferably according to the present invention, no air flow is input into the first hollow cylinder, for example, no purge air inlet is provided on the side wall.

[0058] According to an embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene monofilament includes step 4): with or without stretching, a purge air (referred to as lateral purge air) is provided to the dry raw filament through at least one (such as 2 - 100, preferably 50 - 80) slit-shaped air outlet. According to the present invention, by means of the wind pressure of the lateral purge air (air knife effect), the dry raw filament is split along the longitudinal groove, thereby obtaining the ultra-high molecular weight polyethylene monofilament of the present invention (referred to as the primary monofilament). This step is an important step for fiber splitting. Without this step, the fiber will not be split due to the lack of lateral pressure. At the same time, the air outlet must be a slit. One is to increase the wind pressure as much as possible, and the other is that the slit width should be smaller than the fiber diameter width, so that the wind pressure can fully act on the fiber to achieve sufficient splitting. According to the present invention, the purge air is provided in a direction at an angle (such as 30 - 150°, preferably 60 - 120°, particularly preferably substantially 90°) to the traveling direction of the dry raw filament.

[0059] According to an embodiment of the present invention, immediately after step 3) is completed, step 4) is carried out. If it is not carried out immediately, the fiber further solidifies and a skin layer is formed on the surface, making it difficult to split with the air knife.

[0060] According to an embodiment of the present invention, in step 4), the temperature of the lateral purge air is 0 - 5°C (preferably 1 - 2°C) higher than the melting point of the dry raw filament or the temperature of the lateral purge air is ≥138°C (preferably 140 - 150°C). If the temperature is too high, the fiber strength will be damaged. If the temperature is too low, the fiber has not reached the molten state and is difficult to split.

[0061] According to an embodiment of the present invention, in step 4), the linear velocity of the lateral purge air is 0.01 - 10 m / s (preferably 0.2 - 1 m / s). If the wind speed is too fast, the fiber strength is easily damaged. If the wind speed is too low, the fiber cannot be split.

[0062] According to an embodiment of the present invention, in step 4), the horizontal distance L between the slit-shaped air outlet and the dry raw filament (counting from the center line) is at most 0.1 - 50 cm (preferably at most 1 - 10 cm). Here, the maximum horizontal distance refers to the horizontal distance of the dry raw filament that is farthest from the air outlet. If the distance is too large, the wind pressure will decay and the fibers cannot be split. If the distance is too small, the fiber strength will be damaged. The horizontal distance L is as Figure 1 shown.

[0063] According to an embodiment of the present invention, in step 4), when there is stretching, the stretching ratio is 1 - 10 (preferably 3 - 5). Appropriate stretching can make the fibers split more easily and can also remove the solvent in one step.

[0064] According to a preferred embodiment of the present invention, step 4) is carried out in the second hollow cylinder. The second hollow cylinder includes a top opening, a bottom opening, and a side wall (i.e., a housing) connecting the top opening and the bottom opening and formed around the central axis of the second hollow cylinder. According to the present invention, the top opening communicates with the bottom opening of the first hollow cylinder, and the nascent single filaments pass through the bottom opening of the second hollow cylinder and leave the second hollow cylinder. According to the present invention, the at least one slit-shaped air outlet can be provided on the side wall of the second hollow cylinder (preferably evenly distributed around the side wall). Here, the structure of the second hollow cylinder is as Figure 1 schematically shown, but the present invention is not limited thereto.

[0065] According to an embodiment of the present invention, in step 4), the slit-shaped air outlet is an opening in a long and narrow shape (such as oval or rectangular). By way of example, the height of the opening is generally 1 - 10 mm (preferably 3 - 5 mm), the width of the opening is generally 1 - 100 μm (preferably 3 - 50 μm), and the height-width ratio of the opening is 20 - 2000 (preferably 50 - 500). The opening width of the slit should be smaller than the fiber diameter so that the wind pressure can act fully on the fibers to achieve sufficient splitting of the fibers. If the slit is too large, the wind pressure will decay and it is not easy to split the fibers. If the slit is too small, it is not easy for the air to flow out and equipment blockage is likely to occur. Insufficient height-width ratio will cause the fibers not to be fully split and adhesion will occur. Excessive height-width ratio results in insufficient wind pressure and it is difficult to split the fibers. Preferably, the height direction of the slit-shaped air outlet (i.e., the height direction of the opening) is substantially parallel to the traveling direction of the dry raw filament.

[0066] According to an embodiment of the present invention, in step 4), the lateral purge air is provided via a plurality of (such as 2 - 100, preferably 50 - 80) slit-shaped air outlets evenly spaced around the dry raw filament.

[0067] According to an embodiment of the present invention, the manufacturing method further includes step 5): after the end of step 4), cooling the nascent monofilament 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 nascent monofilament. Herein, if there is stretching, the draw ratio is 1 - 30 (preferably 10 - 20).

[0068] According to an embodiment of the present invention, after the end of step 5), the nascent monofilament is stretched (referred to as post - stretching) in one or more stages (such as 1 - 8 or 2 - 5 stages). Herein, the operating conditions of the post - stretching include: the stretching temperature is 90 - 160 °C (preferably 130 - 150 °C), and the (overall) draw ratio is 2 - 200 (preferably 10 - 30).

[0069] According to an embodiment of the present invention, there is also provided an ultra - high molecular weight polyethylene monofilament, with a filament fineness of 0.1 - 1.0 dtex (preferably 0.4 - 0.5 dtex), and a cross - section in a flat shape, wherein the average width of the cross - section is 1 - 60 μm (preferably 5 - 10 μm), the average thickness of the cross - section is 0.1 - 10 μm (preferably 1 - 3 μm), and the ratio of the average width to the average thickness is 2 or more (preferably 5 - 6). According to the present invention, the fiber strength of the ultra - high molecular weight polyethylene monofilament is generally 5 - 40 cN / dtex (preferably 15 - 35 cN / dtex). According to the present invention, the spinning solvent content of the ultra - high molecular weight polyethylene monofilament is generally 20000 ppm or less (preferably 10000 ppm or less, more preferably 100 ppm or less, 10 ppm or less, or 1 ppm or less). Herein, the ultra - high molecular weight polyethylene monofilament can be obtained by the manufacturing method described in any aspect of the present invention before or after this.

[0070] According to an embodiment of the present invention, there is also provided a fiber product, preferably a medical product such as a medical suture, comprising the ultra - high molecular weight polyethylene monofilament described in any aspect of the present invention before or after this, or made of the ultra - high molecular weight polyethylene monofilament described in any aspect of the present invention before or after this.

[0071] Examples

[0072] 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.

[0073] Example 1

[0074] 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 6 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 a pentagram, the equivalent diameter is 0.8 mm, and the spinneret holes are linearly distributed on the spinneret plate.

[0075] After the spinning solution exits the spinneret holes, it is immediately stretched (initial stretching) in the first hollow cylinder at 190 °C. The initial stretching ratio is 4, there is no input air flow, and the solvent is basically completely removed to obtain a dry raw filament with longitudinal grooves on the side. Then it immediately enters the second hollow cylinder, and purge air (referred to as lateral purge air) is provided to the dry raw filament through 50 slit-shaped air outlets, causing the dry raw filament to split along the longitudinal grooves to obtain the ultra-high molecular weight polyethylene monofilaments (referred to as primary monofilaments). The temperature of the purge air is 142 °C, and the linear velocity of the purge air is 0.5 m / s. The horizontal distance (maximum distance) between the slit-shaped air outlets and the dry raw filament (counting from the center line) is 5 cm. The stretching ratio is 4. The height of the slit opening is 4 mm, the width of the opening is 15 μm, and the aspect ratio of the opening is 267. After one-step cooling, the stretching ratio is 6, the cooling temperature is 80 °C, and then stretching is carried out in 3 stages (referred to as post-stretching). The stretching temperature is 145 °C, and the (overall) stretching ratio is 20.

[0076] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.44 dtex, the cross-section is flat, the average width of the cross-section is 6 μm, the average thickness of the cross-section is 1 μm, and the ratio of the average width to the average thickness is 6. The strength of the monofilaments is 35 cN / dtex, and the solvent content is 0.8 ppm.

[0077] The above monofilaments can be used for medical products such as medical sutures.

[0078] Example 2

[0079] 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 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 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 180 °C, the extrusion speed is 5 m / min, the cross-sectional shape of the spinneret holes is a cross, the equivalent diameter is 1.0 mm, and the spinneret holes are linearly distributed on the spinneret plate.

[0080] After the spinning solution exits the spinneret holes, it is immediately stretched (initial stretching) in the first hollow cylinder at 200 °C. The initial stretching ratio is 5, there is no input air flow, and the solvent is basically completely removed. Then it immediately enters the second hollow cylinder, and purge air (referred to as lateral purge air) is provided to the dry precursor filaments through 80 slit-shaped air outlets, causing the dry precursor filaments to split along the longitudinal grooves to obtain the ultra-high molecular weight polyethylene monofilaments (referred to as nascent monofilaments). The temperature of the purge air is 150 °C, and the linear velocity of the purge air is 0.9 m / s. The horizontal distance (maximum distance) between the slit-shaped air outlets and the dry precursor filaments (counting from the center line) is 10 cm. The stretching ratio is 5. The height of the slit opening is 5 mm, the width of the opening is 20 μm, and the aspect ratio of the opening is 250. After one-step cooling, the stretching ratio is 8, the cooling temperature is 90 °C, and then stretching is carried out in 3 stages (referred to as post-stretching), the stretching temperature is 140 °C, and the (overall) stretching ratio is 30.

[0081] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.4 dtex, the cross-section is flat, the average width of the cross-section is 5 μm, the average thickness of the cross-section is 1 μm, and the ratio of the average width to the average thickness is 5. The strength of the monofilaments is 30 cN / dtex, and the solvent content is 0.5 ppm.

[0082] The above monofilaments can be used for medical products such as medical sutures.

[0083] Example 3

[0084] Ultra-high molecular weight polyethylene and a solvent are mixed to make 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 make a spinning solution. The spinning solution is extruded through a spinneret plate with 50 spinneret holes to form spinning streams. The extrusion temperature is 175 °C, the extrusion speed is 5 m / min. The cross-sectional shape of the spinneret holes is serrated, the equivalent diameter is 1.5 mm, and the spinneret holes are linearly distributed on the spinneret plate.

[0085] After the spinning solution exits the spinneret holes, it is immediately stretched (initial stretching) in the first hollow cylinder at 200 °C. The initial stretching ratio is 3, there is no input air flow, and the solvent is basically completely removed. Then it immediately enters the second hollow cylinder, and purge air (referred to as lateral purge air) is provided to the dry precursor fiber through 60 slit-shaped air outlets, causing the dry precursor fiber to split along the longitudinal groove to obtain the ultra-high molecular weight polyethylene monofilament (referred to as the nascent monofilament). The temperature of the purge air is 145 °C, and the linear velocity of the purge air is 0.2 m / s. The horizontal distance (maximum distance) between the slit-shaped air outlet and the dry precursor fiber (counting from the center line) is 2 cm. The stretching ratio is 3. The height of the slit opening is 3 mm, the width of the opening is 50 μm, and the aspect ratio of the opening is 60. After one-step cooling, the stretching ratio is 8, the cooling temperature is 90 °C, and then stretching is carried out in 3 stages (referred to as post-stretching). The stretching temperature is 130 °C, and the (overall) stretching ratio is 12.

[0086] Finally, an ultra-high molecular weight polyethylene monofilament is obtained. The fineness of the monofilament is 0.5 dtex, the cross-section is flat, the average width of the cross-section is 8 μm, the average thickness of the cross-section is 1.2 μm, and the ratio of the average width to the average thickness is 6.7. The strength of the monofilament is 28 cN / dtex, and the solvent content is 0.9 ppm.

[0087] The above monofilament can be used for medical products such as medical sutures.

[0088] Example 4

[0089] Same as Example 1, except that the spinneret is cross-shaped and the temperature of the first hollow cylinder is 220 °C until the solvent is basically completely removed.

[0090] Finally, an ultra-high molecular weight polyethylene monofilament is obtained. The fineness of the monofilament is 0.44 dtex, the cross-section is flat, the average width of the cross-section is 8 μm, the average thickness of the cross-section is 1.2 μm, and the ratio of the average width to the average thickness is 6.7. The strength of the monofilament is 18 cN / dtex, and the solvent content is 1.5 ppm.

[0091] Example 5

[0092] Same as Example 1, except that the spinneret is four-pointed star-shaped, and after passing through the first hollow cylinder, the solvent residue is 15000 ppm.

[0093] Finally, an ultra-high molecular weight polyethylene monofilament is obtained. The fineness of the monofilament is 0.44 dtex, the cross-section is flat, the average width of the cross-section is 10 μm, the average thickness of the cross-section is 1.5 μm, and the ratio of the average width to the average thickness is 6.7. The strength of the monofilament is 16 cN / dtex, and the solvent content is 89 ppm.

[0094] Example 6

[0095] Same as Example 1, except that the spinneret is four - corner star - shaped. After passing through the first hollow cylinder, the solvent residue is 18000 ppm. When passing through the second hollow cylinder, there is no stretching.

[0096] Finally, ultra - high - molecular - weight polyethylene monofilaments are obtained. The fineness of the monofilament is 0.8 dtex, the cross - section is flat, the average width of the cross - section is 16 μm, the average thickness of the cross - section is 2 μm, and the ratio of the average width to the average thickness is 8. The strength of the monofilament is 14 cN / dtex, and the solvent content is 291 ppm.

[0097] Example 7

[0098] 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, and the spinneret is five - corner star - shaped.

[0099] Finally, a serious shell layer is formed on the fiber surface, and the decalin inside cannot escape, resulting in the inability to form fibers.

[0100] Example 8

[0101] Same as Example 1, except that the spinneret is cross - shaped. After passing through the first hollow cylinder, the solvent residue is 20000 ppm, and the initial draw ratio is 2.

[0102] Finally, ultra - high - molecular - weight polyethylene monofilaments are obtained. The fineness of the monofilament is 1.0 dtex, the cross - section is flat, the average width of the cross - section is 56 μm, the average thickness of the cross - section is 4.0 μm, and the ratio of the average width to the average thickness is 15. The strength of the monofilament is 13 cN / dtex, and the solvent content is 389 ppm.

[0103] Example 9

[0104] Same as Example 1, except that the spinneret is cross - shaped. After passing through the first hollow cylinder, the solvent residue is basically removed, and the initial draw ratio is 10.

[0105] Finally, ultra - high - molecular - weight polyethylene monofilaments are obtained. The fineness of the monofilament is 0.2 dtex, the cross - section is flat, the average width of the cross - section is 4 μm, the average thickness of the cross - section is 0.8 μm, and the ratio of the average width to the average thickness is 5. The strength of the monofilament is 10 cN / dtex, and the solvent content is 1 ppm.

[0106] Example 10

[0107] Same as Example 1, except that the spinneret is cross - shaped. After passing through the first hollow cylinder, the solvent residue is basically removed, and there is an input air interference during the first hollow cylinder stage.

[0108] In this embodiment, the fiber is damaged in the initial stage and cannot form uniform single filaments.

[0109] Example 11

[0110] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is basically removed. Through the second hollow cylinder stage, the temperature of the purging air is 170 °C.

[0111] Finally, ultra-high molecular weight polyethylene single filaments are obtained. The fineness of the single filaments is 0.3 dtex, the cross-section is flat, the average width of the cross-section is 6 μm, the average thickness of the cross-section is 1 μm, and the ratio of the average width to the average thickness is 6. The strength of the single filaments is 12 cN / dtex, and the solvent content is 1 ppm.

[0112] Example 12

[0113] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 15000 ppm. Through the second hollow cylinder stage, the temperature of the purging air is 120 °C.

[0114] Finally, ultra-high molecular weight polyethylene single filaments are obtained. The fineness of the single filaments is 1.0 dtex, the cross-section is flat, the average width of the cross-section is 60 μm, the average thickness of the cross-section is 2.3 μm, and the ratio of the average width to the average thickness is 30. The strength of the single filaments is 8 cN / dtex, and the solvent content is 687 ppm.

[0115] Example 13

[0116] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is basically removed. Through the second hollow cylinder stage, the speed of the purging air is 10 m / s.

[0117] Finally, ultra-high molecular weight polyethylene single filaments are obtained. The fineness of the single filaments is 0.1 dtex, the cross-section is flat, the average width of the cross-section is 4 μm, the average thickness of the cross-section is 1 μm, and the ratio of the average width to the average thickness is 4. The strength of the single filaments is 6 cN / dtex, and the solvent content is 0.5 ppm.

[0118] Example 14

[0119] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 20000 ppm. Through the second hollow cylinder stage, the speed of the purging air is 0.05 m / s.

[0120] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 1.0 dtex, the cross-section is flat, the average width of the cross-section is 42 μm, the average thickness of the cross-section is 10 μm, and the ratio of the average width to the average thickness is 6. The strength of the monofilaments is 17 cN / dtex, and the solvent content is 1005 ppm.

[0121] Example 15

[0122] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 20000 ppm, and the maximum horizontal distance passed through is 25 cm.

[0123] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 1.0 dtex, the cross-section is flat, the average width of the cross-section is 40 μm, the average thickness of the cross-section is 12 μm, and the ratio of the average width to the average thickness is 4. The strength of the monofilaments is 18 cN / dtex, and the solvent content is 2870 ppm.

[0124] Example 16

[0125] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 5000 ppm, and when passing through the second hollow cylinder, the draw ratio is 2.

[0126] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.6 dtex, the cross-section is flat, the average width of the cross-section is 13 μm, the average thickness of the cross-section is 2.5 μm, and the ratio of the average width to the average thickness is 5.6. The strength of the monofilaments is 19 cN / dtex, and the solvent content is 137 ppm.

[0127] Example 17

[0128] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 20000 ppm, and the aspect ratio of the slit is 15.

[0129] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 1.2 dtex, the cross-section is flat, the average width of the cross-section is 75 μm, the average thickness of the cross-section is 4.5 μm, and the ratio of the average width to the average thickness is 16.7. The strength of the monofilaments is 14 cN / dtex, and the solvent content is 4017 ppm.

[0130] Example 18

[0131] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 5000 ppm, and there is no cooling step.

[0132] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.6 dtex, the cross-section is flat, the average width of the cross-section is 14 μm, the average thickness of the cross-section is 2 μm, and the ratio of the average width to the average thickness is 7. The strength of the monofilaments is 13 cN / dtex, and the solvent content is 168 ppm.

[0133] Example 18

[0134] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 5000 ppm, and the total draw ratio of the multifilament is 5.

[0135] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.8 dtex, the cross-section is flat, the average width of the cross-section is 16 μm, the average thickness of the cross-section is 2 μm, and the ratio of the average width to the average thickness is 8. The strength of the monofilaments is 15 cN / dtex, and the solvent content is 207 ppm.

[0136] Comparative Example 1

[0137] Same as Example 1, except that the spinneret holes are circular.

[0138] The monofilaments in this example cannot be split to make ultra-fine monofilaments.

[0139] Comparative Example 2.

[0140] Same as Example 1, except that there is no solvent removal process in the first hollow cylinder.

[0141] Finally, dry tow cannot be obtained, resulting in the inability to form fibers.

[0142] Comparative Example 3

[0143] Same as Example 1, except that the spinneret is cross-shaped. After the solvent removal of the spinning stream in the first hollow cylinder, the solvent residue is more than 40000 ppm.

[0144] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.9 dtex, the cross-section is flat, the average width of the cross-section is 18 μm, the average thickness of the cross-section is 3.5 μm, and the ratio of the average width to the average thickness is 5.1. The strength of the monofilaments is 5 cN / dtex, and the solvent content is 38960 ppm.

[0145] Comparative Example 4

[0146] Same as Example 1, except that the spinneret is cross-shaped. When the solvent is removed from the spinning stream in the first hollow cylinder, the initial draw ratio is 0, and the solvent residue is 33000 ppm.

[0147] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.8 dtex, the cross-section is flat, the average width of the cross-section is 16 μm, the average thickness of the cross-section is 3.5 μm, and the ratio of the average width to the average thickness is 4.6. The strength of the monofilaments is 8 cN / dtex, and the solvent content is 23780 ppm.

[0148] Comparative Example 5

[0149] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 30000 ppm, and the temperature of the first hollow cylinder is 150 °C.

[0150] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 0.8 dtex, the cross-section is flat, the average width of the cross-section is 16 μm, the average thickness of the cross-section is 3.5 μm, and the ratio of the average width to the average thickness is 4.6. The strength of the monofilaments is 10 cN / dtex, and the solvent content is 17800 ppm.

[0151] Comparative Example 6

[0152] This example is the gel method process.

[0153] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 3.0 dtex, the cross-section is nearly circular, the strength of the monofilaments is 30 cN / dtex, and the solvent content is 206 ppm.

[0154] Comparative Example 7

[0155] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 15000 ppm, and there is no second hollow cylinder process.

[0156] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 1.5 dtex, the cross-section is nearly circular. The strength of the monofilaments is 28 cN / dtex, and the solvent content is 16731 ppm.

[0157] Comparative Example 8

[0158] Same as Example 1, except that the spinneret is cross-shaped. After passing through the first hollow cylinder, the solvent residue is 15000 ppm, and the air outlet is square.

[0159] Finally, ultra-high molecular weight polyethylene monofilaments are obtained. The fineness of the monofilaments is 1.5 dtex, the cross-section is nearly circular. The strength of the monofilaments is 32 cN / dtex, and the solvent content is 387 ppm.

Claims

1. A method for manufacturing ultra-high molecular weight polyethylene monofilament, comprising the following steps: 1) Mix ultra-high molecular weight polyethylene and a solvent to form a spinning solution, 2) Extrude the spinning solution through a spinneret provided with at least one (such as 10 - 200) spinneret holes to form a spinning filament stream, wherein the cross-section of the spinneret hole is in the shape of a concave polygon (preferably selected from at least one of dumbbell shape, cross shape, star shape, and serrated shape), 3) Stretch the spinning filament stream (initial stretching) at an 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 substantially completely remove the solvent from the spinning filament stream (such as until the content of the solvent in the spinning filament stream is below 20,000 ppm, preferably below 10,000 ppm, more preferably below 100 ppm or below 10 ppm) to obtain a dry precursor filament with longitudinal grooves on the side, 4) With or without stretching, provide purge air (referred to as lateral purge air) to the dry precursor filament through at least one (such as 2 - 100, preferably 50 - 80) slit-shaped air outlets, so that the dry precursor filament splits along the longitudinal grooves to obtain the ultra-high molecular weight polyethylene monofilament (referred to as the primary 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 equivalent circular diameter of the cross-section of the spinneret hole is 0.1 - 5 mm (preferably 1 - 3 mm), and / or, when multiple spinneret holes are provided, the multiple spinneret holes are linearly distributed on the spinneret.

3. The manufacturing method according to claim 1, wherein the step 3) is carried out immediately 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 spinning stream to be 10-10 6 (preferably 100-1000), and / or the stretching ratio of the initial stretching is 1-10 (preferably 3-5), and / or the ambient temperature is ≤250°C (preferably 188-210°C).

5. The manufacturing method according to claim 1, wherein the step 3) is carried out in a first hollow cylinder, the first hollow cylinder includes a top opening, a bottom opening, and a side wall (i.e., a housing) connecting the top opening and the bottom opening and formed around the central axis of the first hollow cylinder, the top opening is sealingly connected to the spinneret, the dry precursor filament passes through the bottom opening and leaves the first hollow cylinder, and a heating member is provided on at least a part of the side wall to make the internal cavity temperature of the first hollow cylinder reach the ambient temperature.

6. The manufacturing method according to claim 5, wherein in the step 3), suction power is provided to the bottom opening so that the solvent leaves the first hollow cylinder in the form of vapor from the bottom opening, and / or, no air flow is input into the first hollow cylinder (such as no purge air inlet is provided on the side wall).

7. The manufacturing method according to claim 1, wherein step 3) is carried out under conditions of substantially no external air flow input (preferably substantially no external lateral air flow input, more preferably no lateral purging air input), and / or, the solvent leaves step 3) in the form of vapor together with the dry raw filaments in a direction substantially parallel to the direction of the initial stretching.

8. The manufacturing method according to claim 1, wherein step 4) is carried out immediately after the end of step 3).

9. The manufacturing method according to claim 1, wherein in step 4), the temperature of the lateral purging air is 0 - 5 °C (preferably 1 - 2 °C) higher than the melting point of the dry raw filaments or the temperature of the lateral purging air is ≥ 138 °C (preferably 140 - 150 °C), and / or, in step 4), the linear velocity of the lateral purging air is 0.01 - 10 m / s (preferably 0.2 - 1 m / s), and / or, in step 4), the horizontal distance (maximum distance) between the slit-shaped air outlet and the dry raw filaments (counting from the center line) is 0.1 - 50 cm (preferably at most 1 - 10 cm), and / or, in step 4), when stretching exists, the stretching ratio is 1 - 10 (preferably 3 - 5).

10. The manufacturing method according to claim 1, wherein step 4) is carried out in a second hollow cylinder, the second hollow cylinder includes a top opening, a bottom opening, and a side wall (i.e., a shell) connecting the top opening and the bottom opening and formed around the central axis of the second hollow cylinder, the top opening communicates with the bottom opening of the first hollow cylinder, the nascent single filaments leave the second hollow cylinder through the bottom opening of the second hollow cylinder, and at least one slit-shaped air outlet is provided on the side wall of the second hollow cylinder (preferably evenly distributed around the side wall).

11. The manufacturing method according to claim 1, wherein in step 4), the slit-shaped air outlet is an opening in a long and narrow shape (such as oval or rectangular), the height of the opening is 1 - 10 mm (preferably 3 - 5 mm), the width of the opening is 1 - 100 μm (preferably 3 - 50 μm), the height-width ratio of the opening is 20 - 2000 (preferably 50 - 500), and / or, the height direction of the slit-shaped air outlet (i.e., the height direction of the opening) is substantially parallel to the traveling direction of the dry raw filaments.

12. The manufacturing method according to claim 1, wherein in step 4), the lateral purging air is provided through a plurality of (such as 2 - 100, preferably 50 - 80) slit-shaped air outlets evenly spaced around the dry raw filaments.

13. A ultra-high molecular weight polyethylene monofilament, the fineness of the monofilament is 0.1 - 1.0 dtex (preferably 0.4 - 0.5 dtex), and the cross-section is in a flat shape, wherein the average width of the cross-section is 1 - 60 μm (preferably 5 - 10 μm), the average thickness of the cross-section is 0.1 - 10 μm (preferably 1 - 3 μm), and the ratio of the average width to the average thickness is 2 or more (preferably 5 - 6).

14. The ultra-high molecular weight polyethylene monofilament according to claim 13, having a fiber strength of 5-40 cN / dtex (preferably 15-35 cN / dtex), and 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, or 1 ppm or less).

15. The ultra-high molecular weight polyethylene monofilament according to claim 13, obtained by the manufacturing method according to claim 1.

16. A fiber product (preferably a medical product such as a medical suture), comprising the ultra-high molecular weight polyethylene monofilament according to any one of claims 13-15 or made of the ultra-high molecular weight polyethylene monofilament according to any one of claims 13-15.

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