A high-toughness polyphenylene sulfide monofilament and its preparation method and application

Abstract

The present invention discloses a high-toughness polyphenylene sulfide monofilament and its preparation method and application. The tensile strength S of the high-toughness polyphenylene sulfide monofilament satisfies the formula S=F(D)±0.15, where F(D)=1.636D 2 ‑3.5326D+4.61, where D is the monofilament diameter (mm) and is selected from 0.10 to 0.90 mm, and S is the monofilament tensile strength (cN / dtex). The relationship between the knotting strength and tensile strength of this high-toughness polyphenylene sulfide monofilament is: 70% ≤ knotting strength / tensile strength ≤ 90%. The polyphenylene sulfide monofilament disclosed in the present invention combines high toughness and high tensile strength, with toughness comparable to polyester monofilament. It can be woven into spiral mesh belts or woven in warp and weft, without breaking the yarn during the weaving process. The finished mesh surface is highly flat, and is widely used in food drying mesh belts, papermaking conveyor drying mesh belts, automotive pipeline sheathing, industrial filter screens, and other fields.

Description

Technical Field

[0001] The present invention relates to the technical field of polyphenylene sulfide, and in particular to a high-toughness polyphenylene sulfide monofilament and a preparation method and application thereof. Background Art

[0002] Polyphenylene sulfide (PPS) is a special engineering plastic with excellent performance. It has many advantages such as high temperature resistance, corrosion resistance, and high strength. It is widely used in electronics, machinery, automobiles, and chemical industries.

[0003] PPS is a crystalline polymer and is inherently brittle. This brittleness is particularly pronounced when it is made into large-diameter monofilaments (0.1 to 0.90 mm) using traditional spinning processes. Fiber breakage is common during the weaving and bending process, impacting both the yield rate and the lifespan of the monofilament.

[0004] The production process of PPS monofilament is continuous integrated production. The extruder melts the granulated resin into plastics, filters it, and extrudes it from the spinneret. It is cooled and solidified in the cooling water tank. The solidified raw yarn is sequentially drawn with hot water, drawn with hot air, heat-set, oiled, and wound. The conventional production process is as follows: Figure 1 shown.

[0005] The production of PPS monofilament is relatively difficult, and the production cycle time is relatively short (a production cycle refers to the longest time that the machine can operate stably from start to stop), generally 5 to 7 days. Since PPS melt has strong adhesion to metal, and PPS is prone to oxidation if it stays in a high-temperature molten state for too long, forming a gel-like melt, the melt pressure rises rapidly, resulting in uneven wire diameter, and it is necessary to stop the machine and replace components. In addition, if the material contains trace amounts of PPS molecular chains with low molecular weight, it is easy to agglomerate at the spinneret hole after a long period of operation, resulting in uneven melt flow and easy wire breakage during the drawing process. Therefore, it is also necessary to stop the machine regularly to clean the dirt on the spinneret surface (generally once every 1 to 2 days). In the production process of PPS monofilament, multiple monofilaments are arranged in parallel in the equipment without contact, and are wound up individually. Therefore, the production line speed is relatively low. It takes 1 to 35 hours to produce one roll of monofilament (conventional 2.5 kg / roll) depending on the wire diameter. The production process cannot be paused. The various parameters of the equipment must be constant and wire breakage is not allowed. As long as wire breakage or fluctuations in process parameters occur, the monofilament produced in this batch will be scrapped. Each roll of monofilament needs to be of a fixed length and weight and the wire diameter deviation must be within a reasonable range to meet the requirements of use. Otherwise, it will be treated as waste wire.

[0006] At present, the mechanical strength of PPS monofilament prepared by conventional production technology is generally only about 2.5cN / dtex, and the knot strength ratio (knotting strength / tensile strength) is between 50% and 70%. The toughness is poor and cannot meet the downstream weaving and use application requirements.

[0007] While modifying PPS monofilaments by adding toughening agents or other additives can improve their toughness, this method not only increases the number of production steps and production costs, but also significantly diminishes the inherent advantages of polyphenylene sulfide, affecting the monofilament's heat resistance, corrosion resistance, and mechanical properties. Furthermore, the spinning assembly pressure rises rapidly during the spinning process, necessitating equipment downtime for repairs to prevent yarn breakage, further shortening the production cycle and increasing production costs. If the toughness of the monofilament product could be improved without changing the raw materials, the production cost of polyphenylene sulfide monofilament could be significantly reduced, potentially expanding its application.

[0008] A Chinese patent application with publication number CN 104532436 A discloses a multi-stage stretching and heat-setting method for polyphenylene sulfide filaments. The method utilizes raw polyphenylene sulfide fibers and employs a combination of cold drawing, multi-zone hot drawing, intense high-temperature heat setting, extended cooling zones, and winding molding to rationally distribute the drawing zones and temperatures. High-temperature, intense heat setting is utilized to control the dimensional stability of the PPS filaments, thereby improving the production stability, effective draw ratio, mechanical properties, and yarn uniformity of the PPS filaments.

[0009] Chinese patent application publication number CN 163477A discloses a method for melt-spinning, stretching, and heat-setting linear high-molecular-weight polyphenylene sulfide fibers. The method includes high-temperature spinning, delayed heating and cooling, solidification, slow heating, multi-stage stretching, and multi-stage, multi-temperature zone heating relaxation / tension heat-setting. The fibers produced by this method exhibit high breaking strength, low breaking elongation, and excellent thermal stability.

[0010] Although the above technical solutions all disclose improving the mechanical properties of PPS fibers by regulating the production process, the objects being processed are not PPS monofilaments. In fact, there are significant differences in the production processes of PPS monofilaments and PPS fibers. As mentioned above, PPS monofilaments are produced in a continuous integrated manner, while the production process of PPS fibers is a segmented intermittent production process, which is divided into front spinning and back spinning. The front spinning process melts and plasticizes the granulated resin through an extruder, filters it, and extrudes it through a spinneret. It is cooled and solidified by blowing air in an annular direction under the spinneret, and then oiled after pre-stretching at room temperature in the tunnel. The filament bundles coming out of multiple parallel tunnels are combined into one strand, immersed in oil again, and dropped into a barrel. The filaments in the barrel are raw silk, which is stored in the barrel at room temperature for more than 24 hours before being transferred to the back spinning process for the next step of processing. The front spinning process diagram is as follows Figure 2 After spinning, the raw yarns in the barrels are placed side by side under the bunching frame, and the yarn bundles in multiple barrels are combined into one strand, and then the yarns are drawn, shaped, wound, and other operations are performed to produce fibers. The specific process steps are shown in Figure 3 .

[0011] While PPS fiber production lines are long and complex, their production is relatively straightforward. Spinning and drafting are performed in stages, allowing for easy interruption in the event of an anomaly. Cleaning the spinneret during production by simply cutting the yarns does not significantly impact the final product, which is either multi-strand or clump-shaped. However, PPS monofilament production requires extremely stable equipment operation; even slight fluctuations can result in uneven diameters, impairing mechanical strength and other performance. Since downstream applications rely on individual strands, even the slightest instability can compromise performance. Therefore, the production processes for PPS monofilament and PPS fiber differ significantly and are significantly more challenging. Summary of the Invention

[0012] In response to the above-mentioned problems existing in the prior art, the present invention discloses a high-toughness polyphenylene sulfide monofilament, which uses only PPS as raw material and is prepared without adding any external additives to obtain a polyphenylene sulfide monofilament with both high strength and high toughness, thereby ensuring that the monofilament is not broken during the continuous production process, and significantly extending the production time of a production cycle, thereby improving production efficiency and reducing production costs; the polyphenylene sulfide monofilament prepared by this method has excellent weavability, is not broken during the weaving process, and has a high flatness of the woven mesh surface. The woven mesh can be used as a food drying mesh belt, a papermaking conveyor drying mesh belt, an automobile pipeline sheath, an industrial filter mesh, and the like.

[0013] The specific technical solutions are as follows:

[0014] A high-toughness polyphenylene sulfide monofilament, wherein the tensile strength S of the high-toughness polyphenylene sulfide monofilament satisfies the following formula:

[0015] S = F(D) ± 0.15;

[0016] Where F(D)=1.636D 2 -3.5326D+4.61, D is the diameter of the monofilament (mm), D is selected from 0.10 to 0.90 mm, and S is the tensile strength of the monofilament (cN / dtex);

[0017] The relationship between the knotting strength and the tensile strength of the high-toughness polyphenylene sulfide monofilament is: 70%≤knotting strength / tensile strength≤90%.

[0018] The polyphenylene sulfide monofilament prepared by the present invention has a monofilament diameter that can be selected from 0.10 to 0.90 mm and has both high tensile strength and high knotting strength.

[0019] Preferably, the relationship between the knotting strength and the tensile strength of the high-toughness polyphenylene sulfide monofilament is: 80%≤knotting strength / tensile strength≤87%.

[0020] The high-toughness polyphenylene sulfide monofilament has a dry heat shrinkage at 180°C of 1.3-6.0%;

[0021] The strand CV value of the high-tenacity polyphenylene sulfide monofilament is not higher than 1.8%.

[0022] The polyphenylene sulfide monofilament prepared by the present invention also has a low and appropriate shrinkage rate, which is convenient for downstream weaving processes.

[0023] The polyphenylene sulfide monofilament prepared by the present invention also has a low strand CV value, indicating that the polyphenylene sulfide monofilament prepared by the present invention has high wire diameter uniformity, more stable mechanical properties, and small numerical fluctuation.

[0024] The density of the high-toughness polyphenylene sulfide monofilament and the diameter of the monofilament are in the following relationship:

[0025] ρ=f(D)±0.001;

[0026] Where f(D) = -0.0112D + 1.351, D is the diameter of the monofilament (mm), ρ is the density of the monofilament (g / cm 3 ).

[0027] The present invention also discloses a method for preparing the high-toughness polyphenylene sulfide monofilament, comprising the following steps:

[0028] (1) The polyphenylene sulfide resin is melt-extruded, melt-filtered, spun, and then solidified to obtain a raw yarn;

[0029] (2) the raw yarn is sequentially subjected to hot water drawing, hot air drawing, heat setting, secondary heat setting, and then winding to obtain the high-toughness polyphenylene sulfide monofilament;

[0030] The hot water drawing temperature is selected from 89 to 97°C, and the drawing ratio is 3.2 to 3.4;

[0031] The hot air drawing temperature is selected from 115 to 130°C, and the drawing ratio is 1.15 to 1.30;

[0032] The heat setting temperature is selected from 150 to 190°C, and the draft ratio is 0.94 to 0.98;

[0033] The secondary heat setting temperature is selected from 190 to 240° C., and the draft ratio is 1.0.

[0034] The preparation method of polyphenylene sulfide monofilament disclosed in the present invention adds a secondary heat setting process after heat setting on the basis of the conventional preparation process. More importantly, the processing temperature and draw ratio of hot water drawing, hot air drawing, heat setting, and secondary heat setting are strictly limited. It has been verified through experiments that only when the process parameters of each step are limited to the above range can high-toughness polyphenylene sulfide monofilament with the above properties be prepared.

[0035] Preferably, in step (2):

[0036] The hot water drawing temperature is selected from 89 to 95°C;

[0037] The secondary heat setting temperature is selected from 190 to 230°C;

[0038] The polyphenylene sulfide monofilament prepared using the above-mentioned preferred process conditions has better surface properties and is more conducive to downstream weaving applications.

[0039] Further preferred:

[0040] The temperature of the hot water drawing is selected from 92 to 95°C, more preferably 92°C;

[0041] The temperature of the hot air drawing is selected from 125 to 130°C; more preferably 125°C;

[0042] The temperature of the secondary heat setting is selected from 220 to 230°C;

[0043] The polyphenylene sulfide monofilament prepared by adopting the above further preferred process conditions not only has better apparent properties, but also has higher toughness.

[0044] Preferably, in step (2):

[0045] The heat setting temperature is selected from 160 to 190°C; more preferably, the heat setting temperature is selected from 175°C.

[0046] The dry heat shrinkage of the polyphenylene sulfide monofilament prepared at the further preferred heat setting temperature is more appropriate.

[0047] In step (1), the melt index of the polyphenylene sulfide resin is selected from 50 to 300 g / 10 min (test temperature is 315.6° C.), and the molecular weight is selected from 45,000 to 75,000.

[0048] Preferably, the melt index of the polyphenylene sulfide resin is selected from 100 to 200 g / 10 min.

[0049] In step (1), the temperature of the melt extrusion is 305-330°C.

[0050] In step (1), the spinning is specifically:

[0051] The filtered melt is pressed into the spinneret, a thin stream of melt is ejected, and then the single filament bundle is cooled and solidified by a cooling device.

[0052] The PPS monofilament prepared by the above method has toughness comparable to that of polyester monofilament, can be woven into a spiral mesh belt, and can also be woven in warp and weft. The monofilament is not broken during the weaving process, and the mesh surface has high flatness after weaving. It can be widely used in food drying mesh belts, papermaking conveyor drying mesh belts, automobile pipeline sheaths, industrial filter screens and other fields.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The present invention discloses a polyphenylene sulfide monofilament with high toughness and high tensile strength, and also has a low strand CV value. The prepared polyphenylene sulfide monofilament has high wire diameter uniformity, stable mechanical properties, and stable thermal shrinkage. The PPS monofilament disclosed in the present invention has toughness comparable to that of polyester monofilament, can be woven into a spiral mesh belt, and can also be woven through warp and weft. The monofilament is not broken during the weaving process, and the mesh surface after weaving has high flatness. The monofilament can be widely used in the fields of food drying mesh belts, papermaking conveying drying mesh belts, automobile pipeline sheaths, industrial filter screens, and the like.

[0055] The present invention also discloses a method for preparing the polyphenylene sulfide monofilament, which uses only PPS as raw material and is prepared by optimizing the process flow without adding any external additives to obtain the PPS monofilament with the above-mentioned excellent properties. The method can also ensure that the yarn is not broken during the continuous production process, thereby significantly extending the production time of a production cycle, improving production efficiency, and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 This is the conventional production process flow chart of PPS monofilament;

[0057] Figure 2 This is the process flow chart of PPS fiber pre-spinning;

[0058] Figure 3 This is the process flow chart of PPS fiber post-spinning. DETAILED DESCRIPTION

[0059] In order to make the objects, features and advantages of the present invention more apparent, the following examples are further cited to illustrate the present invention in detail. The following examples are only used to further illustrate the present invention and are not to be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the principles described in the present invention are also within the scope of protection of the present invention.

[0060] The properties of the PPS monofilaments prepared in the following examples and comparative examples were tested using the following method:

[0061] 1. The tensile strength, knotting strength, hook strength and elongation at break of PPS monofilament are tested using the method in national standard GB / T14344-2008;

[0062] Knotting strength / tensile strength is the ratio of knotting strength to tensile strength, which is used in this article to characterize the toughness of monofilaments. When the tensile strength of the monofilament meets the requirements, the higher this ratio is, the better the toughness of the monofilament is.

[0063] 2. The dry heat shrinkage of PPS monofilament at 180°C is tested using the method in GB / T6505-2017.

[0064] 3. The CV value of the yarn is tested using the method in the national standard GB / T14346-2015. The test yarn CV value is obtained by calculating the standard deviation / average value of the test data. Generally, the lower the CV value, the better the quality of the monofilament yarn and the more uniform the monofilament diameter. The industry generally requires the yarn CV value of superior products to be less than 1.5%, the industry requires the yarn CV value of first-class products to be less than 1.8%, and the industry requires the yarn CV value of qualified products to be less than 2.5%.

[0065] Example 1

[0066] The moisture content of polyphenylene sulfide granules (Zhejiang Xinhecheng Special Materials Co., Ltd., specification: 3514, molecular weight 51,000-68,000, MFR (315.6°C) = 125-150 g / 10 min) was adjusted to about 80 ppm using a dehumidifying dryer. The dried granules were extruded and melted into a 320°C melt through an extruder. The melt was metered and transported to a melt filter by a metering pump and then entered into a spinning assembly. After secondary filtration through a filter screen, it was pressed into a porous spinneret with an aperture of 0.60 mm, ejecting a thin stream of the melt. The cooling and solidification equipment cooled and solidified the monofilament bundle.

[0067] The cooled monofilament is sequentially drawn using hot water and hot air, heat-set, heat-set again, oiled and wound.

[0068] The hot water drawing temperature is 92°C, and the hot water drawing ratio is 3.30; the hot air drawing temperature is 125°C, and the hot air drawing ratio is 1.20; the heat setting temperature is 175°C, and the heat setting ratio is 0.95; the secondary heat setting temperature is 220°C, and the secondary heat setting ratio is 1.0, and the spinning line speed is 130m / min.

[0069] In this example, high-toughness polyphenylene sulfide monofilaments were prepared. The monofilament diameter was 0.10 mm. The performance data of the prepared monofilaments are shown in Table 1.

[0070] By using the spinneret in this embodiment, the diameter of the prepared monofilament can be adjusted within the range of 0.10 to 0.15 mm by adjusting the feed rate of the metering pump. Due to space constraints, we will not elaborate on each of these.

[0071] Example 2

[0072] The preparation process is exactly the same as that in Example 1, except that:

[0073] Spinnerets of different sizes were used, specifically: a circular spinneret with an aperture of 0.80 mm was used; and the spinning line speed was changed to 110 m / min.

[0074] The high-toughness polyphenylene sulfide monofilament produced in this example has a monofilament diameter of 0.20 mm. The performance data of the produced monofilament are shown in Table 1. Using the spinneret in this example, the monofilament diameter can be adjusted within a range of 0.15 to 0.25 mm by adjusting the feed rate of the metering pump. Due to space constraints, a detailed description is not provided here.

[0075] Example 3

[0076] The preparation process is exactly the same as that in Example 1, except that:

[0077] Spinnerets of different sizes were used, specifically: a circular hole spinneret with an aperture of 1.00 mm was used; and the spinning linear speed was changed to 90 m / min.

[0078] The high-toughness polyphenylene sulfide monofilament prepared in this embodiment has a monofilament diameter of 0.30 mm. The performance data of the prepared monofilament are shown in Table 1. Using the spinneret in this embodiment, by adjusting the feed amount of the metering pump, the diameter of the prepared monofilament can be adjusted within 0.25 to 0.35 mm. Due to space constraints, they will not be described one by one. Using a circular hole spinneret with an aperture of 1.20 mm, the spinning line speed is replaced with 70 m / min. By adjusting the feed amount of the metering pump, the diameter of the prepared monofilament can be adjusted within 0.35 to 0.45 mm. Due to space constraints, they will not be described one by one.

[0079] Example 4

[0080] The preparation process is exactly the same as that in Example 1, except that:

[0081] Spinnerets of different sizes were used, specifically: a circular hole spinneret with an aperture of 1.40 mm was used; and the spinning line speed was changed to 60 m / min.

[0082] The high-toughness polyphenylene sulfide monofilament produced in this example has a monofilament diameter of 0.50 mm. The performance data of the produced monofilament are shown in Table 1. Using the spinneret in this example, the monofilament diameter can be adjusted within a range of 0.45 to 0.60 mm by adjusting the feed rate of the metering pump. Due to space constraints, a detailed description is not provided here.

[0083] Example 5

[0084] The preparation process is exactly the same as that in Example 1, except that:

[0085] Spinnerets of different sizes were used, specifically: a circular hole spinneret with an aperture of 1.60 mm was used; and the spinning line speed was changed to 55 m / min.

[0086] The high-toughness polyphenylene sulfide monofilament produced in this example had a monofilament diameter of 0.68 mm. The performance data of the produced monofilament are shown in Table 1. Using the spinneret in this example, the monofilament diameter can be adjusted within a range of 0.60 to 0.72 mm by adjusting the feed rate of the metering pump. Due to space constraints, a detailed description is not provided here.

[0087] Example 6

[0088] The preparation process is exactly the same as that in Example 1, except that:

[0089] Spinnerets of different sizes were used, specifically: a circular hole spinneret with an aperture of 1.80 mm was used; and the spinning line speed was changed to 45 m / min.

[0090] The high-toughness polyphenylene sulfide monofilament produced in this example had a monofilament diameter of 0.80 mm. The performance data of the produced monofilament is shown in Table 1. Using the spinneret in this example, the monofilament diameter can be adjusted within a range of 0.72 to 0.85 mm by adjusting the feed rate of the metering pump. Due to space constraints, a detailed description is not provided here.

[0091] Example 7

[0092] The preparation process is exactly the same as that in Example 1, except that:

[0093] Spinnerets of different sizes were used, specifically: a circular hole spinneret with an aperture of 2.00 mm was used; and the spinning line speed was changed to 40 m / min.

[0094] The high-toughness polyphenylene sulfide monofilament produced in this example had a monofilament diameter of 0.90 mm. The performance data of the produced monofilament are shown in Table 1. Using the spinneret in this example, the monofilament diameter can be adjusted within a range of 0.85 to 0.90 mm by adjusting the feed rate of the metering pump. Due to space constraints, a detailed description is not provided here.

[0095] Example 8

[0096] The preparation process is basically the same as that in Example 4, except that the hot water drawing temperature is replaced with 89° C. and the hot water drawing ratio is replaced with 3.40.

[0097] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0098] Example 9

[0099] The preparation process is basically the same as that in Example 4, except that the hot water drawing temperature is replaced with 95° C. and the hot water drawing ratio is replaced with 3.20.

[0100] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0101] Example 10

[0102] The preparation process is basically the same as that in Example 4, except that the hot water drawing temperature is replaced with 97°C.

[0103] The polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The monofilament performance data are shown in Table 2.

[0104] The experiment found that the PPS monofilament prepared in this embodiment has a large CV value and a slight whitening phenomenon occurs on the surface of the monofilament. Analysis shows that this may be due to a small amount of crystallization, slight whitening, poor apparent performance, and wavy patterns on the mesh surface after being woven into a mesh, which is not conducive to downstream applications.

[0105] Example 11

[0106] The preparation process is basically the same as that in Example 4, except that the hot air drawing temperature is replaced with 115° C. and the hot air drawing ratio is replaced with 1.30.

[0107] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0108] Example 12

[0109] The preparation process is basically the same as that in Example 4, except that the hot air stretching temperature is replaced with 130° C. and the hot air stretching ratio is replaced with 1.15.

[0110] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0111] Example 13

[0112] The preparation process is basically the same as that in Example 4, except that the heat setting temperature is replaced with 150° C. and the heat setting draw ratio is replaced with 0.98.

[0113] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0114] Example 14

[0115] The preparation process is basically the same as that in Example 4, except that the heat setting temperature is replaced with 190° C. and the heat setting draw ratio is replaced with 0.94.

[0116] Examples 15-16

[0117] The preparation process is basically the same as that in Example 4, except that the secondary heat setting temperature is replaced with 190° C. and 230° C. respectively.

[0118] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0119] Example 17

[0120] The preparation process is basically the same as that in Example 4, except that the secondary heat setting temperature is replaced with 240°C.

[0121] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 2.

[0122] According to experiments, when the secondary heat setting temperature is slightly higher, thermal oxygen cross-linking will occur on the surface of the monofilament, the monofilament will become dull, and the color will change from golden to light brown. The apparent performance is poor, and the monofilament is harder, which affects weaving.

[0123] Comparative Example 1

[0124] The preparation process is basically the same as that in Example 4, except that the hot water drawing temperature is replaced with 85°C.

[0125] Tests have shown that when the hot water drawing temperature is below the lower limit, the raw yarn breaks continuously in the hot water drawing tank during spinning, making spinning impossible. Single yarn properties cannot be measured.

[0126] Comparative Example 2

[0127] The preparation process is basically the same as that in Example 4, except that the hot water drawing ratio is replaced with 3.0.

[0128] According to the test, when the hot water drawing ratio is lower than the lower limit of the drawing ratio, the raw yarn breaks frequently in the heat setting oven during the spinning process, and the diameter of the spun single yarn is uneven, making it impossible to perform strength testing.

[0129] Comparative Example 3

[0130] The preparation process is basically the same as that in Example 4, except that the hot water drawing ratio is replaced with 3.6.

[0131] Tests have shown that when the hot water draw ratio exceeds the upper limit, spinning is possible and the resulting monofilament has high tensile strength. However, the knotting strength, hook strength, and elongation at break are low, resulting in poor toughness. This leads to frequent yarn breakage during weaving, making netting difficult and unfavorable for downstream applications. The performance data of the monofilament produced in this comparative example are shown in Table 3.

[0132] Comparative Example 4

[0133] The preparation process is basically the same as that in Example 4, except that the hot air drawing temperature is replaced with 105°C.

[0134] Tests have shown that when the hot air drawing temperature is below the lower limit, the tensile strength, knotting strength, and hooking strength of the monofilament are significantly reduced. When woven into a mesh, the mesh surface strength is low and does not meet the strength requirements for use. The performance data of the monofilament prepared in this comparative example are shown in Table 3.

[0135] Comparative Example 5

[0136] The preparation process is basically the same as that in Example 4, except that the hot air drawing temperature is replaced with 140°C.

[0137] Tests showed that when the hot air drawing temperature was higher than the upper temperature limit, yarn breakage occurred occasionally during the spinning process, the yarn evenness CV value was higher, and the single-filament tensile strength increased slightly, but the mechanical properties of the single-filament were unstable and fluctuated greatly. The performance data of the single-filament prepared in this comparative example are shown in Table 3.

[0138] Comparative Example 6

[0139] The preparation process is basically the same as that in Example 4, except that the hot air stretching ratio is replaced with 1.05.

[0140] Tests have shown that when the hot air draft ratio is below the lower limit, the tensile strength, knotting strength, and hooking strength of the monofilament are significantly reduced. When woven into a mesh, the mesh surface strength is low and does not meet the strength requirements for use. The performance data of the monofilament prepared in this comparative example are shown in Table 3.

[0141] Comparative Example 7

[0142] The preparation process is basically the same as that in Example 4, except that the hot air drawing ratio is replaced with 1.40.

[0143] Tests have shown that when the hot air draft ratio is higher than the upper limit of the draft ratio, the mechanical properties of the monofilament are acceptable, but frequent breakage of the yarn occurs, which is not conducive to monofilament production. The performance data of the monofilament prepared in this comparative example are shown in Table 3.

[0144] Comparative Example 8

[0145] The preparation process is basically the same as that in Example 4, except that the heat setting temperature is replaced with 140°C.

[0146] The high-toughness polyphenylene sulfide monofilament prepared in this example has a monofilament diameter of 0.50 mm. The performance data of the prepared monofilament are shown in Table 3.

[0147] According to tests, when the heat setting temperature is slightly lower, the dry heat shrinkage rate of the single yarn is higher and the numerical fluctuation range is wider. After being woven into a net, the dimensional stability is poor and the net surface is uneven.

[0148] Comparative Example 9

[0149] The preparation process is basically the same as that in Example 4, except that the heat setting temperature is replaced with 200°C.

[0150] Experiments have shown that when the heat setting temperature is higher than the upper limit of the optimal temperature, the raw yarn will break in the setting oven during the spinning process, making spinning difficult and unable to measure the single yarn performance.

[0151] Comparative Example 10

[0152] The preparation process is basically the same as that in Example 4, except that no secondary heat setting is performed.

[0153] The test showed that the strength of the monofilament without secondary heat setting was slightly lower. The performance data of the monofilament prepared in this comparative example are shown in Table 3.

[0154] Comparative Example 11

[0155] The preparation process is basically the same as that in Example 4, except that the secondary heat setting temperature is replaced with 180°C.

[0156] The test showed that when the secondary heat setting temperature was lower than the lower limit of the optimal temperature, the performance of the monofilament was not improved after the secondary setting, and the advantage of the secondary setting disappeared. The performance data of the monofilament prepared in this comparative example are shown in Table 3.

[0157] Table 1

[0158]

[0159] Table 2

[0160]

[0161] Table 3

[0162]

[0163] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for preparing high-toughness polyphenylene sulfide monofilament, characterized in that: The steps include: (1) The polyphenylene sulfide resin is melt-extruded, melt-filtered, spun, and then solidified to obtain raw yarn; (2) The raw yarn is then subjected to hot water drawing, hot air drawing, heat setting, secondary heat setting and then winding to obtain the high-toughness polyphenylene sulfide monofilament; The hot water drawing temperature is selected from 89 to 97°C, and the drawing ratio is 3.2 to 3.4; The hot air drawing temperature is selected from 115 to 130 ° C, and the drawing ratio is 1.15 to 1.30; The heat setting temperature is selected from 150 to 190°C, and the draft ratio is 0.94 to 0.98; The secondary heat setting temperature is selected from 190 to 240°C and the draft ratio is 1.0; The tensile strength S of the high-toughness polyphenylene sulfide monofilament satisfies the following formula: S = F (D) ± 0.15; Where, F(D)=1.636D 2 -3.5326D+4.61, D is the diameter of the monofilament (mm), D is selected from 0.10 to 0.90 mm, and S is the tensile strength of the monofilament (cN / dtex); The relationship between the knotting strength and the tensile strength of the high-toughness polyphenylene sulfide monofilament is: 70%≤knotting strength / tensile strength≤90%.

2. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (1), the melt index of the polyphenylene sulfide resin is selected from 50 to 300 g / 10 min, and the molecular weight is selected from 40,000 to 80,000.

3. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (1), the temperature of the melt extrusion is 305-330°C.

4. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (1), the spinning is specifically: The filtered melt is pressed into the spinneret, a thin stream of melt is ejected, and then the single filament bundle is cooled and solidified by a cooling device.

5. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (2): The hot water drawing temperature is selected from 89 to 95°C; The heat setting temperature is selected from 160 to 190°C; The secondary heat setting temperature is selected from 190 to 230°C.

6. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (2): The high-toughness polyphenylene sulfide monofilament has a dry heat shrinkage at 180°C of 1.3-6.0%; The CV value of the high-tenacity polyphenylene sulfide monofilament is not higher than 1.8%.

7. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (2): The density of the high-toughness polyphenylene sulfide monofilament and the diameter of the monofilament are in the following relationship: ρ = f (D) ± 0.001; Where f(D)=-0.0112D+1.351, D is the diameter of the monofilament (mm), ρ is the density of the monofilament (g / cm 3 ).

8. The method for preparing high-toughness polyphenylene sulfide monofilament according to claim 1, characterized in that: In step (2): The relationship between the knotting strength and the tensile strength of the high-toughness polyphenylene sulfide monofilament is: 80%≤knotting strength / tensile strength≤87%.

9. Use of high-toughness polyphenylene sulfide monofilament prepared by the method according to any one of claims 1 to 8 in food drying mesh belts, papermaking conveyor drying mesh belts, automobile pipeline sheaths, and industrial filter screens after weaving.

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