Manufacturing method and application of ultra-high molecular weight polyethylene fiber with low solvent residue

Abstract

The invention relates to a manufacturing method and application of ultra-high molecular weight polyethylene fiber with low solvent residue. The manufacturing method of the ultra-high molecular weight polyethylene fiber 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 to form a spinning trickle, and 3) removing at least a part of the solvent from the spinning trickle to obtain a dry precursor, and 4) when the dry precursor is stretched, setting the melting point of the dry precursor as T, and basically completely removing the solvent from the dry precursor at the temperature of T-0. 5 DEG C to T-20 DEG C to obtain the ultra-high molecular weight polyethylene fiber. According to the present invention, the ultra-high molecular weight polyethylene fiber has very low solvent residue, and is particularly suitable for medical use.

Description

Technical Field

[0001] The present invention relates to the field of high-performance fibers, and in particular, to a manufacturing method and application of ultra-high molecular weight polyethylene fibers with low solvent residue. Background Art

[0002] The existing production technologies of ultra-high molecular weight polyethylene fibers are divided into two categories: the wet spinning process using white oil as a solvent and the dry spinning process using decalin as a solvent. For the former, since the solvent needs to be extracted first and then volatilized, the process is complex and the solvent residue in the product is high, resulting in an impure product. For the latter, it is difficult for the existing technology to achieve a low residue level of the solvent inside the fiber through volatilization, making it difficult for the product to meet the requirements of high-end application fields such as medical use. Summary of the Invention

[0003] The purpose of the present invention is to manufacture ultra-high molecular weight polyethylene fibers with low solvent residue in view of the problem of high solvent residue in ultra-high molecular weight polyethylene fibers in the prior art. During the fiber forming process of the present invention, because of the use of an easily volatile solvent, a large amount of the solvent is first volatilized to manufacture a dry-state raw fiber, and then during the drawing process, through reasonable drawing ratio, drawing rate and temperature, the solvent is fully migrated to the fiber surface and quickly volatilized, so as to achieve the purpose of fully removing the solvent and obtain ultra-high molecular weight polyethylene fibers with low solvent residue.

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

[0005] 1. A manufacturing method of ultra-high molecular weight polyethylene fibers, 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 to form a spinning filament,

[0008] 3) Removing at least a part (such as at least 50 wt%, preferably at least 70 wt%, at least 80 wt%, at least 90 wt% or at least 95 wt%) of the solvent from the spinning filament to obtain a dry-state raw fiber,

[0009] 4) While stretching the dry-state raw fiber, assuming the melting point of the dry-state raw fiber is T, at a temperature from T - 0.5 °C to T - 20 °C (preferably from T - 2 °C to T - 8 °C or from T - 3 °C to T - 5 °C), substantially completely removing the solvent from the dry-state raw fiber (such as until the content of the solvent in the dry-state raw fiber is below 20000 ppm, preferably below 10000 ppm, more preferably below 100 ppm, below 10 ppm or below 1 ppm) to obtain the ultra-high molecular weight polyethylene fiber (referred to as the nascent fiber).

[0010] 2. The manufacturing method described in any 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 described in any of the foregoing or following aspects, wherein in step 1), the solvent is selected from at least one of white oil, mineral oil, naphthalene, decahydronaphthalene, tetrahydronaphthalene, kerosene, xylene, toluene, petroleum fractions, halogenated hydrocarbons, cycloalkanes, and cycloolefins, and preferably decahydronaphthalene.

[0012] 4. The manufacturing method described in any 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 described in any of the foregoing or following aspects, wherein in step 2), with or without stretching, the extrusion temperature is 150 - 220 °C (preferably 170 - 180 °C), and the extrusion speed is 2 - 20 m / min (3 - 5 m / min); when stretching exists, the stretching ratio is 0 - 50 (preferably 2 - 20).

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

[0015] 7. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), at least a part of the solvent is removed from the spinning stream by an evaporation method.

[0016] 8. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), the operating conditions of the evaporation method include: with or without stretching, the evaporation temperature is 0.5 - 10 °C higher than the boiling point of the solvent (preferably 1 - 5 °C); when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5); and the elapsed time is not less than 2 min (preferably 4 - 8 min).

[0017] 9. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), purge air is provided to the spinning stream, and the flow rate of the purge air is 30 - 300 Nm 3 / h (preferably 100 - 200 Nm 3 / h), and the temperature of the purge air is 100 - 180 °C (preferably 140 - 160 °C).

[0018] 10. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), the spun filaments are cooled to obtain gel filaments, and then at least a part of the solvent is removed by an evaporation method and / or an extraction method.

[0019] 11. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), the operating conditions for the cooling include: with or without stretching, the cooling temperature is -50 - 100 °C (preferably 20 - 50 °C); when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5).

[0020] 12. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), the operating conditions for the evaporation method include: with or without stretching, the evaporation temperature is 0.5 - 10 °C higher than the boiling point of the solvent (preferably 1 - 5 °C); when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5); the elapsed time is not less than 2 min (preferably 4 - 8 min).

[0021] 13. The manufacturing method described in any of the foregoing or following aspects, wherein in step 3), the operating conditions for the extraction method include: with or without stretching, the extractant is a volatile hydrocarbon solvent (preferably at least one selected from xylene and heptane), the extraction temperature is 10 - 150 °C (preferably 40 - 90 °C); when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5).

[0022] 14. The manufacturing method described in any of the foregoing or following aspects, wherein after step 3) ends, step 4) is immediately carried out.

[0023] 15. The manufacturing method described in any of the foregoing or following aspects, wherein in step 4), the operating conditions include: the stretching temperature is 118 - 144 °C (preferably 133 - 140 °C), the stretching ratio is 3 - 30 (preferably 6 - 20), and the elapsed time is not less than 2 min (preferably 5 - 20 min).

[0024] 16. The manufacturing method described in any of the foregoing or following aspects, wherein in step 4), purge air is provided to the dry raw filaments, the temperature of the purge air is 70 - 130 °C (preferably 100 - 120 °C), and the flow rate of the purge air is 50 - 180 Nm 3 / h (preferably 90 - 150 Nm 3 / h).

[0025] 17. The manufacturing method described in any of the foregoing or following aspects, wherein after step 4) ends, the nascent fibers are 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-drawing include: the drawing temperature is 90 - 160 °C (preferably 140 - 150 °C), and the (overall) draw ratio is 2 - 30 (preferably 5 - 15).

[0027] 19. A ultra-high molecular weight polyethylene fiber obtained by the manufacturing method described in any of the foregoing or following aspects, having a 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).

[0028] 20. The ultra-high molecular weight polyethylene fiber described in any of the foregoing or following aspects, having a single filament fineness of 0.5 - 5 dtex (preferably 1.0 - 2.7 dtex), a fiber strength of 28 - 50 cN / dtex (preferably 32 - 38 cN / dtex), and a coefficient of variation (cV) of the breaking strength ≤ 10% (preferably ≤ 5%).

[0029] 21. A fiber product comprising the ultra-high molecular weight polyethylene fiber described in any of the foregoing or following aspects or made from the ultra-high molecular weight polyethylene fiber described in any of the foregoing or following aspects.

[0030] 22. The fiber product described in any of the foregoing or following aspects, further comprising at least one other fiber selected from natural plant fibers, natural animal fibers, artificial regenerated fibers, synthetic fibers, and inorganic fibers.

[0031] Technical effects

[0032] By controlling the migration of the solvent during the fiber forming process, the present invention enables the full volatilization of the solvent inside the fiber, obtaining ultra-high molecular weight polyethylene fibers with low solvent residues. The fibers obtained by the present invention have a single filament fineness of 0.5 - 5 dtex, a fiber strength of 28 - 50 cN / dtex, a coefficient of variation (cV) of the breaking strength ≤ 10%, and low solvent residues, and are particularly suitable for medical uses. Detailed description of the specific embodiments

[0033] 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.

[0034] 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.

[0035] When this specification uses prefixes such as "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 currently but will become recognized in the art as suitable for similar purposes.

[0036] 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.

[0037] 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%.

[0038] In the context of the present invention, the measuring method for the solvent content is GB / T41671 - 2022.

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

[0040] In the context of the present invention, the measuring method for the fiber strength is GB / T19975 - 2005.

[0041] In the context of the present invention, the measuring method for the breaking 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 fibers. According to the present invention, the solvent residue amount of the ultra-high molecular weight polyethylene fibers is very low. For example, relative to the total mass of the ultra-high molecular weight polyethylene fibers, the solvent residue amount is generally 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, and is particularly suitable for medical use.

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

[0046] According to one embodiment of the present invention, in step 1), the amount of the solvent used is at most 2000 parts by weight (preferably 1000-1500 parts by weight) relative to 100 parts by weight of the ultra-high molecular weight polyethylene.

[0047] According to one 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 fractions, halogenated hydrocarbons, cycloalkanes, and cycloolefins, preferably decalin.

[0048] According to one 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 to 7 million).

[0049] According to one embodiment of the present invention, the method for producing ultra-high molecular weight polyethylene fiber comprises step 2): extruding the spinning solution through a spinneret to form a spinning fine flow.

[0050] According to one embodiment of the present invention, in step 2), stretching is present or absent, the extrusion temperature is 150-220° C. (preferably 170-180° C.), and the extrusion speed is 2-20 m / min (3-5 m / min).

[0051] According to one embodiment of the present invention, in step 2), when stretching is present, the stretching ratio is 0-50 (preferably 2-20).

[0052] According to one embodiment of the present invention, the method for manufacturing ultra-high molecular weight polyethylene fiber comprises step 3): removing at least a portion of the solvent from the spinning stream to obtain dry precursor. The so-called at least a portion, for example, removes at least 50wt%, preferably at least 70wt%, at least 80wt%, at least 90wt% or at least 95wt% of the solvent relative to the total mass of the spinning stream. The inventors of the present invention have found that if the dry precursor with a large amount of volatile solvent prepared without this step is directly stretched, firstly, the spinning solution cannot be solidified and formed into fibers, and secondly, even if it is barely formed, during the continuous stretching process in step 4), the fiber strength is low due to excessive residual solvent, and the technical effect cannot be achieved.

[0053] According to one embodiment of the present invention, the spinning stream is immediately subjected to step 3) after leaving the spinneret.

[0054] According to an embodiment of the present invention, in step 3), at least a part of the solvent is removed from the spinning stream by an evaporation method.

[0055] According to an embodiment of the present invention, in step 3), the operating conditions of the evaporation method include: with or without stretching, the evaporation temperature is 0.5 - 10 °C (preferably 1 - 5 °C) higher than the boiling point of the solvent; when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5). The inventors of the present invention have found that if the evaporation temperature is too high, a skin layer is formed due to rapid surface volatilization, and the solvent inside the tissue migrates to the surface layer, resulting in a decrease in fiber strength and an increase in solvent residue. If the evaporation temperature is too low, the evaporation rate of the surface solvent is slow, the fiber contains moisture, and it is easy to fluff during the stretching process, resulting in a decrease in strength.

[0056] According to an embodiment of the present invention, in step 3), the elapsed time of the evaporation method is not less than 2 min (preferably 4 - 8 min). The inventors of the present invention have found that if the elapsed time is too short, there is not enough time for the fiber solvent residue to volatilize completely to reach a low residue level, and if the elapsed time is too long, the damage to the fiber by high temperature is aggravated, resulting in a decrease in strength.

[0057] According to an embodiment of the present invention, in step 3), purge air is provided to the spinning stream, and the flow rate of the purge air is 30 - 300 Nm 3 / h (preferably 100 - 200 Nm 3 / h), and the temperature of the purge air is 100 - 180 °C (preferably 140 - 160 °C). The inventors of the present invention have found that if the purge air flow rate is too small, the surface evaporation rate of the solvent is slower than the solvent migration rate, the fiber contains moisture, and it is easy to fluff during drawing, resulting in a decrease in strength; if the purge air flow rate is too large, the solvent on the fiber surface volatilizes rapidly, forming a skin-core structure, and the internal solvent is difficult to escape, resulting in an increase in solvent residue.

[0058] According to an embodiment of the present invention, in step 3), the spinning stream is cooled to obtain a gel fiber, and then at least a part of the solvent is removed by an evaporation method and / or an extraction method.

[0059] According to an embodiment of the present invention, in step 3), the operating conditions of the cooling include: with or without stretching, the cooling temperature is -50 - 100 °C (preferably 20 - 50 °C); when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5).

[0060] According to an embodiment of the present invention, in step 3), the operating conditions of the evaporation method include: with or without stretching, the evaporation temperature is 0.5 - 10 °C (preferably 1 - 5 °C) higher than the boiling point of the solvent; when stretching exists, the stretching ratio is 1 - 10 (preferably 2 - 5); the elapsed time is not less than 2 min (preferably 4 - 8 min).

[0061] According to an embodiment of the present invention, in step 3), the operating conditions of the extraction method include: with or without stretching, the extractant is a volatile hydrocarbon solvent (preferably at least one selected from xylene and heptane), the extraction temperature is 10 - 150 °C (preferably 40 - 90 °C); when stretching is present, the draw ratio is 1 - 10 (preferably 2 - 5).

[0062] According to an embodiment of the present invention, the method for manufacturing the ultra-high molecular weight polyethylene fiber includes step 4): while stretching the dry raw filaments, substantially completely removing the solvent from the dry raw filaments to obtain the ultra-high molecular weight polyethylene fiber (referred to as the nascent fiber). By substantially completely removing, for example, until the content of the solvent in the dry raw filaments is 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. The inventors of the present invention have found that when the stretching is carried out at a specific operating temperature, the solvent evaporation rate on the fiber surface and the migration rate of the internal solvent reach a suitable ratio, and at the same time, it is adapted to the drawing speed. During the extreme solvent removal process, since the solvent is not suddenly removed, but the fiber still has good stretchability under the action of solvent small molecules until the solvent reaches an extremely low residue. As the operating temperature, assuming the melting point of the dry raw filaments is T, the operating temperature is from T - 0.5 °C to T - 20 °C, preferably from T - 2 °C to T - 8 °C or from T - 3 °C to T - 5 °C. The inventors of the present invention have found that if the temperature is too low, the solvent evaporation is insufficient, resulting in a high solvent residue; if the temperature is too high, the solvent evaporation rate on the fiber surface is faster than the migration rate of the internal solvent, the stretchability of the fiber decreases, it is easy to fluff, and the strength decreases. According to the present invention, the melting point of the dry raw filaments is generally 138 - 144 °C.

[0063] According to an embodiment of the present invention, immediately after the end of step 3), step 4) is carried out.

[0064] According to an embodiment of the present invention, in step 4), the operating conditions include: the stretching temperature is 120 - 145 °C (preferably 130 - 143 °C), and the draw ratio is 3 - 30 (preferably 6 - 20).

[0065] According to an embodiment of the present invention, the elapsed time of step 4) is not less than 2 min (preferably 5 - 20 min). The inventors of the present invention have found that if the residence time is too short, the solvent is difficult to be completely removed, and if the residence time is too long, the fiber is damaged under high temperature conditions and the strength decreases.

[0066] According to one embodiment of the present invention, in step 4), purge air is provided to the dry precursor filaments, the temperature of the purge air is 70 - 130 °C (preferably 100 - 120 °C), and the flow rate of the purge air is 50 - 180 Nm 3 / h (preferably 90 - 150 Nm 3 / h). The inventors of the present invention have found that if the purge air volume is too small, the surface evaporation rate of the solvent is slower than the solvent migration rate, the fiber contains moisture, and it is easy to fluff during stretching, resulting in a decrease in strength; if the purge air volume is too large, the solvent on the fiber surface evaporates rapidly, forming a skin-core structure, and the internal solvent is difficult to escape, resulting in an increase in solvent residue.

[0067] According to one embodiment of the present invention, after step 4) is completed, the as-spun fiber is stretched in one or more stages (such as 1 - 8 or 2 - 5 stages) (referred to as post-drawing).

[0068] According to one embodiment of the present invention, the operating conditions of the post-drawing include: the drawing temperature is 90 - 160 °C (preferably 140 - 150 °C), and the (overall) draw ratio is 2 - 30 (preferably 5 - 15).

[0069] According to one embodiment of the present invention, it also relates to a ultra-high molecular weight polyethylene fiber obtained by the manufacturing method described in any of the foregoing or following aspects of the present invention. According to the present invention, the solvent content of the ultra-high molecular weight polyethylene fiber is generally 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, based on 100 wt% of the total mass of the ultra-high molecular weight polyethylene fiber.

[0070] According to one embodiment of the present invention, the single filament fineness of the ultra-high molecular weight polyethylene fiber is 0.5 - 5 dtex (preferably 1.0 - 2.7 dtex), the fiber strength is 28 cN / dtex - 50 cN / dtex (preferably 32 cN / dtex - 38 cN / dtex), and the coefficient of variation of the breaking strength cV ≤ 10% (preferably ≤ 5%).

[0071] According to one embodiment of the present invention, it also relates to a fiber product comprising the ultra-high molecular weight polyethylene fiber described in any of the foregoing or following aspects of this specification or made of the ultra-high molecular weight polyethylene fiber described in any of the foregoing or following aspects of this specification.

[0072] According to one embodiment of the present invention, the fiber product further comprises at least one other fiber selected from natural plant fibers, natural animal fibers, artificial regenerated fibers, synthetic fibers, and inorganic fibers.

[0073] Examples

[0074] The present invention will be further described in detail below by way of examples and comparative examples, but the present invention is not limited to these examples.

[0075] Example 1

[0076] The low-solvent-residue ultra-high molecular weight polyethylene fiber of this example is obtained through the following process:

[0077] Ultra-high molecular weight polyethylene and a solvent are mixed to form a spinning solution. With respect to 100 parts by weight of the ultra-high molecular weight polyethylene, the amount of the solvent used is 1200 parts by weight. The solvent is decalin. The viscosity-average molecular weight of the ultra-high molecular weight polyethylene is 5 million.

[0078] The spinning solution is extruded through a spinneret to form a spinning filament. Under stretching conditions, the extrusion temperature is 175 °C, the extrusion speed is 4 m / min, and the draw ratio is 10. At least 95 wt% of the solvent is removed from the spinning filament with respect to the total mass of the spinning filament. After the spinning filament leaves the spinneret, at least 95 wt% of the solvent is immediately removed from the spinning filament by an evaporation method. The operating conditions of the evaporation method include: under stretching, the evaporation temperature is 3 °C higher than the boiling point of the solvent, and the draw ratio is 4. The elapsed time of the evaporation method is not less than 5 min. At the same time, purge air is provided to the spinning filament. The flow rate of the purge air is 150 Nm 3 / h, the temperature of the purge air is 150 °C, to form a dry precursor filament. Subsequently, the dry precursor filament is immediately stretched. The stretching temperature is 140 °C, the draw ratio is 8, the elapsed time is not less than 10 min, the temperature of the purge air is 110 °C, and the flow rate of the purge air is 130 Nm 3 / h, to form a nascent fiber. After completion, the nascent fiber is stretched in 3 stages (referred to as post-stretching). The stretching temperature is 145 °C, and the (overall) draw ratio is 10.

[0079] Finally, an ultra-high molecular weight polyethylene fiber is obtained. The residual solvent content is 0.23 ppm, based on 100 wt% of the total mass of the ultra-high molecular weight polyethylene fiber. The denier per filament of the ultra-high molecular weight polyethylene fiber is 1.2 dtex, the fiber strength is 38 cN / dtex, and the coefficient of variation of the breaking strength cV ≤ 3%.

[0080] The above fiber can be used as a braided wire for an implantable suture anchor.

[0081] Example 2

[0082] Same as Example 1, except that 7 million ultra-high molecular weight polyethylene is used, with 100 parts by weight of ultra-high molecular weight polyethylene, and the amount of the solvent is 1500 parts by weight. The solvent content of the obtained ultra-high molecular weight polyethylene fiber is 8.0 ppm, the monofilament fineness is 1.7 dtex, the fiber strength is 36 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 2%.

[0083] The above fibers can be used as implant-grade wire-tied titanium plates.

[0084] Example 3

[0085] Same as Example 1, except that blowing air is provided for the spinning stream, and the flow rate of the blowing air is 200 Nm 3 / h, and the temperature of the blowing air is 160 °C. The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 25.0 ppm, the monofilament fineness is 2.0 dtex, the fiber strength is 32 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 5%.

[0086] The above fibers can be used as sports medicine sutures.

[0087] Example 4

[0088] Same as Example 1, except that the evaporation temperature of the spinning stream is 1 °C higher than the boiling point of the solvent, and the draw ratio is 2. The elapsed time of the evaporation method is not less than 4 min. The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 30.0 ppm, the monofilament fineness is 1.7 dtex, the fiber strength is 34 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 5%.

[0089] The above fibers can be used as sports medicine sutures.

[0090] Example 5

[0091] Same as Example 1, except that the evaporation temperature of the spinning stream is the boiling point of the solvent.

[0092] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 9530 ppm, the monofilament fineness is 2.0 dtex, the fiber strength is 28 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 8%.

[0093] Example 6

[0094] Same as Example 1, except that the evaporation temperature of the spinning stream is 15 °C higher than the boiling point of the solvent.

[0095] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 500 ppm, the monofilament fineness is 1.7 dtex, the fiber strength is 30 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 7%.

[0096] Example 7

[0097] Same as Example 1, except that the evaporation time of the spinning jet is 1 min.

[0098] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 8260 ppm, the fineness of the monofilament is 1.5 dtex, the fiber strength is 29 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 10%.

[0099] Example 8

[0100] Same as Example 1, except that the evaporation time of the spinning jet is 12 min.

[0101] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 210 ppm, the fineness of the monofilament is 1.2 dtex, the fiber strength is 39 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 10%.

[0102] Example 9

[0103] Same as Example 1, except that the flow rate of the purging air during the evaporation of the spinning jet is 80 Nm 3 / h.

[0104] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 7250 ppm, the fineness of the monofilament is 1.1 dtex, the fiber strength is 40 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 7%.

[0105] Example 10

[0106] Same as Example 1, except that the flow rate of the purging air during the evaporation of the spinning jet is 400 Nm 3 / h.

[0107] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 333 ppm, the fineness of the monofilament is 1.2 dtex, the fiber strength is 29 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 8%.

[0108] Example 11

[0109] Same as Example 1, except that the drawing temperature of the as-spun fiber is 137 °C.

[0110] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 413 ppm, the fineness of the monofilament is 1.5 dtex, the fiber strength is 30 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤ 9%.

[0111] Example 12

[0112] Same as Example 1, except that the drawing temperature of the as-spun fiber is 128 °C.

[0113] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 670 ppm, the filament fineness is 1.7 dtex, the fiber strength is 29 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤7%.

[0114] Example 13

[0115] Same as Example 1, except that the flow rate of the purge air for the dry tow is 80 Nm 3 / h.

[0116] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 1760 ppm, the filament fineness is 1.1 dtex, the fiber strength is 42 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤6%.

[0117] Example 14

[0118] Same as Example 1, except that the flow rate of the purge air for the dry tow is 220 Nm 3 / h.

[0119] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 315 ppm, the filament fineness is 1.7 dtex, the fiber strength is 31 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤6%.

[0120] Example 15

[0121] Same as Example 1, except that the solvent removal method is the gel method.

[0122] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 18000 ppm, the filament fineness is 1.6 dtex, the fiber strength is 28 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤6%.

[0123] Example 16

[0124] Same as Example 1, except that the stretching time of the dry tow is 1 min.

[0125] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 16000 ppm, the filament fineness is 1.4 dtex, the fiber strength is 28 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤8%.

[0126] Example 17

[0127] Same as Example 1, except that the stretching time of the dry tow is 30 min.

[0128] The residual solvent content of the ultra-high molecular weight polyethylene fiber obtained is 12000 ppm, the filament fineness is 1.5 dtex, the fiber strength is 29 cN / dtex, and the coefficient of variation (cV) of the breaking strength is ≤8%.

[0129] Comparative Example 1

[0130] Same as Example 1, except for the step (3) of removing the solvent from the spinning solution.

[0131] Fiber formation cannot be achieved.

[0132] Comparative Example 2

[0133] Same as Example 1, except that the solvent removal rate in step (3) is 30 wt%.

[0134] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 24000 ppm, the monofilament fineness is 2.8 dtex, the fiber strength is 25 cN / dtex, and the coefficient of variation of the breaking strength cV ≤ 12%.

[0135] Comparative Example 3

[0136] Same as Example 1, except that the drawing temperature in step (4) is 160 °C.

[0137] Melting and fiber formation cannot be achieved.

[0138] Comparative Example 4

[0139] Same as Example 1, except that the drawing temperature in step (4) is 146 °C.

[0140] The residual solvent content of the obtained ultra-high molecular weight polyethylene fiber is 1000 ppm, the monofilament fineness is 1.2 dtex, the fiber strength is 23 cN / dtex, and the coefficient of variation of the breaking strength cV ≤ 12%.

Claims

1. A method for manufacturing ultra-high molecular weight polyethylene fibers, 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 to form a spinning filament, 3) Remove at least a portion (such as at least 50 wt%, preferably at least 70 wt%, at least 80 wt%, at least 90 wt% or at least 95 wt%) of the solvent from the spinning filament to obtain a dry precursor filament, 4) While stretching the dry precursor filament, assuming the melting point of the dry precursor filament is T, at a temperature from T - 0.5 °C to T - 20 °C (preferably from T - 2 °C to T - 8 °C or from T - 3 °C to T - 5 °C), substantially completely remove the solvent from the dry precursor filament (such as until the content of the solvent in the dry precursor filament is below 20,000 ppm, preferably below 10,000 ppm, more preferably below 100 ppm, 10 ppm or 1 ppm) to obtain the ultra-high molecular weight polyethylene fiber (referred to as the nascent fiber).

2. The manufacturing method according to claim 1, wherein in step 2), with or without stretching, the extrusion temperature is 150 - 220 °C (preferably 170 - 180 °C), the extrusion speed is 2 - 20 m / min (3 - 5 m / min); when stretching exists, the draw ratio is 0 - 50 (preferably 2 - 20).

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

4. The manufacturing method according to claim 1, wherein in step 3), at least a portion of the solvent is removed from the spinning filament by an evaporation method, or the spinning filament is cooled to obtain a gel filament, and then at least a portion of the solvent is removed by an evaporation and / or extraction method.

5. The manufacturing method according to claim 4, wherein in step 3), at least a portion of the solvent is removed from the spinning filament by an evaporation method, and the operating conditions of the evaporation method comprise: with or without stretching, the evaporation temperature is 0.5 - 10 °C higher than the boiling point of the solvent (preferably 1 - 5 °C); when stretching exists, the draw ratio is 1 - 10 (preferably 2 - 5); the elapsed time is not less than 2 min (preferably 4 - 8 min).

6. The manufacturing method according to claim 4, wherein in step 3), at least a part of the solvent is removed from the spinning stream by an evaporation method, and purge air is supplied to the spinning stream, the flow rate of the purge air being 30-300 Nm 3 / h (preferably 100-200 Nm 3 / h), and the temperature of the purge air being 100-180 °C (preferably 140-160 °C).

7. The manufacturing method according to claim 1, wherein after step 3) is completed, step 4) is immediately carried out.

8. The manufacturing method according to claim 1, wherein in step 4), the operating conditions comprise: the stretching temperature is 118 - 144 °C (preferably 133 - 140 °C), the draw ratio is 3 - 30 (preferably 6 - 20), and the elapsed time is not less than 2 min (preferably 5 - 20 min).

9. The manufacturing method according to claim 1, wherein in step 4), purge air is provided to the dry roving, the temperature of the purge air is 70-130 °C (preferably 100-120 °C), and the flow rate of the purge air is 50-180 Nm 3 / h (preferably 90-150 Nm 3 / h).

10. The manufacturing method according to claim 1, wherein after step 4) is completed, the nascent fiber is stretched in one or more stages (such as 1 - 8 or 2 - 5 stages) (referred to as post-stretching).

11. The manufacturing method according to claim 10, wherein the operating conditions of the post-stretching comprise: The drawing temperature is 90 - 160°C (preferably 140 - 150°C), and the (overall) drawing ratio is 2 - 30 (preferably 5 - 15).

12. A ultra-high molecular weight polyethylene fiber obtained by the manufacturing method described in claim 1, with a solvent content of 20000 ppm or less (preferably 10000 ppm or less, more preferably 100 ppm or less, 10 ppm or less, or 1 ppm or less).

13. The ultra-high molecular weight polyethylene fiber described in claim 12, with a single filament fineness of 0.5 - 5 dtex (preferably 1.0 - 2.7 dtex), a fiber strength of 28 cN / dtex - 50 cN / dtex (preferably 32 cN / dtex - 38 cN / dtex), and a coefficient of variation of breaking strength cV ≤ 10% (preferably ≤ 5%).

14. A fiber product comprising the ultra-high molecular weight polyethylene fiber described in claim 12 or made of the ultra-high molecular weight polyethylene fiber described in claim 12.