A multifilament version of the anti-lodging PBT monofilament and its preparation method

Abstract

The present application relates to polybutylene terephthalate (PBT) material toothbrush filament technical field, specifically relates to a kind of multifilament version anti-lodging PBT monofilament and preparation method thereof;The preparation method is realized with the basic concept of multifilament to realize the basic form of monofilament, in the drawing process, every three monofilaments are gathered into a multifilament, in the subsequent water cooling, oiling etc. Process path, with the mode of multifilament, drafting, winding forming are completed.In the condition that monofilament specification remains unchanged, corresponding design is carried out to production process, and the quality indexes such as breaking strength, breaking strength variation coefficient, breaking elongation, breaking elongation variation coefficient of monofilament are controlled.In the realization equipment efficiency is improved three times target, product quality is upgraded, and the anti-lodging performance of PBT monofilament is improved.

Description

Technical Field

[0001] This invention relates to the field of toothbrush bristle technology using polybutylene terephthalate (PBT) materials, specifically to a multifilament anti-collapse PBT monofilament and its preparation method. Background Technology

[0002] Globally, all monofilament production lines extrude a single monofilament from a single hole in a spinneret, which is then wound onto a yarn bobbin. This is the basic concept and form of monofilament. In contrast, multifilament production involves dozens, hundreds, or even thousands of monofilaments bundled together and wound onto a yarn bobbin. To significantly improve production efficiency, this invention uses the basic concept of multifilament to achieve the basic form of monofilament, while simultaneously designing the production process accordingly, thus solving the persistent industry problems of poor anti-collapse properties and lack of toughness in PBT toothbrush bristles. Toothbrushes are indispensable teeth cleaning and care tools in daily life, and their quality largely depends on the quality of their bristles. Compared to top international brands, a prominent problem currently facing the domestic industry is the anti-collapse property of toothbrush bristles, commonly known as "frizzing" or "bristle breakage," resulting in short toothbrush lifespan, poor cleaning effect, and uncomfortable tooth feel. Against this backdrop, developing anti-collapse PBT toothbrush bristles has been a long-standing goal for the domestic industry. We use a monofilament production line to produce multifilament versions of anti-collapse PBT toothbrush monofilaments, forming a unique monofilament manufacturing process for toothbrushes. Summary of the Invention

[0003] The purpose of this invention is to achieve the basic form of monofilament through process design based on the basic concept of multifilament, thereby doubling the efficiency and solving the problem of poor lodging resistance of existing PBT monofilaments.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing multifilament anti-lodging PBT monofilament includes the following steps:

[0006] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate. The set temperatures of each zone of the screw extruder from front to back are 240±2℃, 255±2℃, 270±2℃, 285±2℃, 290±2℃, 295±2℃, and 295±2℃; the melt pressure is 120±0.1 bar.

[0007] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35±0.1℃; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group;

[0008] S3: After cooling, the nascent fibers are separated by a splitting device with 80 splitting holes, then enter the oiling system for oiling, and then enter the drawing machine. The total drawing ratio is 4.5-5.5 times, the temperature of the feed drawing roller is 65±0.1℃, and the temperature of the output drawing roller is 100±0.1℃.

[0009] S4: After stretching, the product is wound up, graded, and packaged.

[0010] The industry practice for setting the temperatures of different zones within a screw extruder, from front to back, is generally to be 265±2℃, 275±2℃, 280±2℃, 285±2℃, 285±2℃, 275±2℃, and 270±2℃. In this application, when the melt flow rate is tripled, lowering the temperatures of the first three zones of the screw extruder can stabilize the melt pressure and reduce the unevenness of the breaking strength and elongation at break of the monofilament. When the extrusion volume of the screw extruder is tripled, the temperatures of the last four zones of the screw extruder must be significantly increased for normal production to proceed; otherwise, severe filament breakage will prevent production from continuing. The appropriateness of the breaking strength and elongation at break indicators can be achieved by lowering or raising the temperatures of the last four zones of the screw extruder. If it is necessary to increase the breaking strength of the monofilament and decrease its elongation at break, this can be achieved by gradually lowering the temperatures of the last four zones of the screw extruder.

[0011] The industry practice for setting the melt pressure within a screw extruder is generally to set it to 80 ± 0.5 bar. In this application, the melt pressure is set to 120 ± 0.1 bar; this setting, which increases the pressure and maintains it at a relatively stable level, can significantly reduce the unevenness of PBT monofilaments.

[0012] The industry practice for setting the cooling bath temperature is generally 50±1℃. In this application, the cooling temperature is set to 35±0.1℃; this setting of lowering the temperature while maintaining a basically stable temperature is beneficial to the crystallization of PBT monofilaments and the smooth progress of subsequent drawing.

[0013] Regarding drawing temperature, the industry practice is to set the feed drawing roller temperature to 90±0.1℃, the output drawing roller temperature to 130±0.1℃, and the draw ratio to 3.8-4.5. In this application, the feed drawing roller temperature is 65±0.1℃, the output drawing roller temperature is 100±0.1℃, and the draw ratio is 4.5-5.5. Both the feed and output drawing rollers consist of seven rollers. If the temperature is not uniform among the seven rollers, it will lead to uneven and discontinuous macromolecular crystallinity between the monofilaments. This application improves the resilience of the monofilament by using low-temperature drawing and reduces the elongation at break of the monofilament by using a relatively high draw ratio, thereby improving the toughness of the monofilament.

[0014] Preferably, in step S2, the spacing between the spinnerets in each group is relatively close, denoted as d1; the spacing between adjacent groups of spinnerets is kept at an appropriate distance, denoted as d2, where d1 < d2; the existing wire separating device on the production line maintains 80 wire separating hole positions unchanged, with every 3 wires passing through one wire separating hole position; the wire separating device, like a comb, can separate the wires and maintain the spacing, and can be set between each process as needed. In this application, from the cooling stage to the winding stage, a wire separating device is provided in each process; in addition, the diameter of the wire guide hole on the winding device should be appropriately increased.

[0015] Preferably, the temperature of the constant temperature chamber of the drawing machine is 85±0.1℃.

[0016] The industry practice for setting the temperature of the constant temperature chamber is to set it to 120±0.1℃; in this application, the temperature of the constant temperature chamber is 85±0.1℃; it is necessary to ensure that the transverse and longitudinal temperatures inside the constant temperature chamber are consistent to improve the uniformity of molecular crystallinity between monofilaments.

[0017] Preferably, the screw of the screw extruder has a length-to-diameter ratio of 30:1 and a rotational speed of 150-250 rpm.

[0018] Preferably, the nascent fibers after cooling need to undergo dehumidification treatment before entering the drawing machine.

[0019] Another object of the present invention is to provide a multifilament anti-lodging PBT monofilament prepared by the above preparation method.

[0020] Preferably, the diameter of the multifilament anti-lodging PBT monofilament is 0.08-1.0 mm, such as 0.08 mm, 0.1 mm, 0.2 mm, 0.4 mm, 0.6 mm, 0.8 mm, etc.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] During the drawing process, three monofilaments are bundled into a multifilament bundle. After leaving the water cooler, the bundle is oiled, bundled, bound, and antistatic treated. The multifilaments are then drawn and wound into shape, achieving a multifilament version of PBT monofilament production technology while maintaining the same monofilament specifications. Furthermore, by further reducing the temperature of the first three zones of the screw extruder and increasing the draw ratio, the unevenness of the PBT filament's breaking strength and elongation at break is reduced; low-temperature drawing improves the monofilament's resilience and flexibility; maintaining a consistent temperature in the constant-temperature chamber improves the uniformity and continuity of crystallinity between monofilament molecules; increasing melt pressure reduces the unevenness of the PBT monofilament's yarn; and lowering the cooling bath temperature improves the pre-crystallization of the PBT monofilament and the smoothness of subsequent drawing. In summary, the anti-collapse performance of PBT toothbrush filaments is improved through the comprehensive optimization of the above process parameters. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] A method for preparing multifilament anti-lodging PBT monofilament includes the following steps:

[0026] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate. The temperature settings of each zone of the screw extruder, from front to back, are 240℃, 255℃, 270℃, 285℃, 290℃, 295℃, and 295℃; the melt pressure is 120 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.1 bar; the PBT granules are dried in an oven for 2-3 hours at a drying temperature of 80℃ to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0027] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35°C with a temperature tolerance of ±0.1°C; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; the hole spacing in each group of spinneret holes is relatively close, denoted as d1; the hole spacing between adjacent groups of spinneret holes is kept at an appropriate distance, denoted as d2, where d1 < d2.

[0028] S3: After cooling, the nascent fibers are processed using the existing drawing and dehumidification system and filament separating device before entering the oiling system for oiling. They then enter the drawing system and are drawn into filaments with a diameter of 0.08 mm. The filament separating device has 80 separating holes, with three filaments passing through each hole. The total drawing ratio of the drawing system is 5.0-5.5 times, the feed drawing roller temperature is 65℃, the output drawing roller temperature is 100℃, and the constant temperature chamber temperature is 85℃, with a temperature tolerance of ±0.1℃. Both the feed and output drawing rollers have seven rollers. If the temperature is uneven between the seven rollers or between different zones of the drawing rollers, it will lead to uneven and discontinuous macromolecular crystallinity between the filaments. Similarly, if there is a temperature difference between the transverse and longitudinal directions within the constant temperature chamber, it will also lead to uneven molecular crystallinity between the filaments. Furthermore, during step S3, static electricity is generated due to friction between the filaments, between the filaments and the drafting rollers, and between the filaments and the guide ceramic parts. Conventional spinning oils have low viscosity, resulting in insufficient oil film thickness after oiling the multifilaments. Increasing the oil concentration by 15% and raising the fiber oil content to 1.2% significantly improves the cohesion, bundling, and antistatic properties between the filaments.

[0029] S4: After traction is completed, it is wound up, graded and packaged.

[0030] Comparative Example 1

[0031] A method for preparing PBT monofilaments includes the following steps:

[0032] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate (PET). The set temperatures of each zone of the screw extruder, from front to back, are 240℃, 255℃, 270℃, 285℃, 290℃, 295℃, and 295℃; the melt pressure is 120 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.1 bar; the PBT granules are dried for 2-3 hours at 80℃ using a drying system to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0033] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35°C with a temperature tolerance of ±0.1°C; the spinneret assembly has 80 spinneret holes.

[0034] S3: After cooling, the nascent fibers are treated using the existing dehumidification system and filament splitting device before entering the oiling system for oiling. Then, they enter the drafting system and are drawn into filaments with a diameter of 0.08 mm. The filament splitting device has 80 filament splitting holes, with one filament passing through each hole. The total drafting ratio of the drafting machine is 5.0-5.5 times, the temperature of the feed drafting roller is 65℃, the temperature of the output drafting roller is 100℃, and the temperature of the constant temperature chamber is 85℃. The above temperature tolerance is ±0.1℃. There are seven feed drafting rollers and seven output drafting rollers.

[0035] S4: After stretching, it is obtained by winding, grading and packaging.

[0036] Comparative Example 2

[0037] A method for preparing PBT monofilaments includes the following steps:

[0038] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate. The temperature settings of each zone of the screw extruder, from front to back, are 265℃, 275℃, 280℃, 285℃, 285℃, 275℃, and 270℃; the melt pressure is 120 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.1 bar; the PBT granules are dried for 2-3 hours at 80℃ using a drying system to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0039] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35°C with a temperature tolerance of ±0.1°C; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; the hole spacing in each group of spinneret holes is relatively close, denoted as d1; the hole spacing between adjacent groups of spinneret holes is kept at an appropriate distance, denoted as d2, where d1 < d2.

[0040] S3: After cooling, the nascent fibers are treated using the existing dehumidification system and filament separating device before entering the oiling system for oiling. They then enter the drafting system and are drawn into filaments with a diameter of 0.08 mm. The filament separating device has 80 separating holes, with three filaments passing through each hole. The total drafting ratio of the drafting machine is 5.0-5.5 times, the feed drafting roller temperature is 65℃, the output drafting roller temperature is 100℃, and the constant temperature chamber temperature is 85℃, with a temperature tolerance of ±0.1℃. There are seven feed and seven output drafting rollers. The oiling concentration is increased by 15%, raising the fiber oil content to 1.2%.

[0041] S4: After stretching, it is obtained by winding, grading and packaging.

[0042] Comparative Example 3

[0043] A method for preparing PBT monofilaments includes the following steps:

[0044] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate (PET). The temperature settings of each zone of the screw extruder, from front to back, are 240℃, 255℃, 270℃, 285℃, 290℃, 295℃, and 295℃; the melt pressure is 80 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.1 bar; the PBT granules are dried for 2-3 hours at 80℃ using a drying system to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0045] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35°C with a temperature tolerance of ±0.1°C; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; the hole spacing in each group of spinneret holes is relatively close, denoted as d1; the hole spacing between adjacent groups of spinneret holes is kept at an appropriate distance, denoted as d2, where d1 < d2.

[0046] S3: After cooling, the nascent fibers are treated using the existing dehumidification system and filament separating device before entering the oiling system for oiling. They then enter the drawing machine and are drawn into filaments with a diameter of 0.08 mm. The filament separating device has 80 separating holes, with three filaments passing through each hole. The total draw ratio of the drawing system is 5.0-5.5 times, the feed drawing roller temperature is 65℃, the output drawing roller temperature is 100℃, and the constant temperature chamber temperature is 85℃, with a temperature tolerance of ±0.1℃. There are seven feed and seven output drawing rollers. The oil concentration is increased by 15%, raising the fiber oil content to 1.2%.

[0047] S4: After stretching, it is obtained by winding, grading and packaging.

[0048] Comparative Example 4

[0049] A method for preparing PBT monofilaments includes the following steps:

[0050] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate. The temperature settings of each zone of the screw extruder, from front to back, are 240℃, 255℃, 270℃, 285℃, 290℃, 295℃, and 295℃; the melt pressure is 120 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.1 bar; the PBT granules are dried for 2-3 hours at 80℃ using a drying system to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0051] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 50°C with a temperature tolerance of ±1°C; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; the hole spacing in each group of spinneret holes is relatively close, denoted as d1; the hole spacing between adjacent groups of spinneret holes is kept at an appropriate distance, denoted as d2, where d1 < d2.

[0052] S3: After cooling, the nascent fibers are treated using the existing dehumidification system and filament separating device before entering the oiling system for oiling. They then enter the drafting system and are drawn into filaments with a diameter of 0.08 mm. The filament separating device has 80 separating holes, with three filaments passing through each hole. The total drafting ratio of the drafting system is 5.0-5.5 times, the feed drafting roller temperature is 65℃, the output drafting roller temperature is 100℃, and the constant temperature chamber temperature is 85℃, with a temperature tolerance of ±0.1℃. There are seven feed and seven output drafting rollers. The oil concentration is increased by 15%, increasing the fiber oil content to 1.2%.

[0053] S4: After stretching, it is obtained by winding, grading and packaging.

[0054] Comparative Example 5

[0055] A method for preparing PBT monofilaments includes the following steps:

[0056] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate. The temperature settings of each zone of the screw extruder, from front to back, are 240℃, 255℃, 270℃, 285℃, 290℃, 295℃, and 295℃; the melt pressure is 120 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.1 bar; the PBT granules are dried for 2-3 hours at 80℃ using a drying system to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0057] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35°C with a temperature tolerance of ±1°C; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; the hole spacing in each group of spinneret holes is relatively close, denoted as d1; the hole spacing between adjacent groups of spinneret holes is kept at an appropriate distance, denoted as d2, where d1 < d2.

[0058] S3: After cooling, the nascent fibers are treated using the existing dehumidification system and filament separating device before entering the oiling system for oiling. They then enter the drafting system and are drawn into filaments with a diameter of 0.08 mm. The filament separating device has 80 separating holes, with three filaments passing through each hole. The total drafting ratio of the drafting system is 3.8-4.0 times, the feed drafting roller temperature is 90℃, the output drafting roller temperature is 130℃, and the constant temperature chamber temperature is 120℃, with a temperature tolerance of ±0.1℃. There are seven feed and seven output drafting rollers. The oil concentration is increased by 15%, raising the fiber oil content to 1.2%.

[0059] S4: After stretching, it is obtained by winding, grading and packaging.

[0060] Comparative Example 6

[0061] A method for preparing PBT monofilaments includes the following steps:

[0062] S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate (PET). The temperature settings of each zone of the screw extruder, from front to back, are 265℃, 275℃, 280℃, 285℃, 285℃, 275℃, and 270℃; the melt pressure is 80 bar; the temperature tolerance is ±2℃, and the melt pressure tolerance is ±0.5 bar; the PBT granules are dried for 2-3 hours at 80℃ using a drying system to achieve a moisture content of 30 PPM; the screw length-to-diameter ratio of the screw extruder is 30:1, and the rotation speed is 150-250 rpm.

[0063] S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 50°C with a temperature tolerance of ±0.1°C; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; the hole spacing in each group of spinneret holes is relatively close, denoted as d1; the hole spacing between adjacent groups of spinneret holes is kept at an appropriate distance, denoted as d2, where d1 < d2.

[0064] S3: After cooling, the nascent fibers are treated using the existing dehumidification system and filament separating device before entering the oiling system for oiling. They then enter the drafting system and are drawn into filaments with a diameter of 0.08 mm. The filament separating device has 80 separating holes, with three filaments passing through each hole. The total drafting ratio of the drafting system is 3.8-4.0 times, the feed drafting roller temperature is 90℃, the output drafting roller temperature is 130℃, and the constant temperature chamber temperature is 120℃, with a temperature tolerance of ±0.1℃. There are seven feed and seven output drafting rollers. The oil concentration is increased by 15%, raising the fiber oil content to 1.2%.

[0065] S4: After stretching, it is obtained by winding, grading and packaging.

[0066] The difference between Comparative Example 1 and Example 1 is that the spinneret on the spinneret assembly and the filament splitting device both have 80 spinneret holes, with only one filament passing through each filament splitting hole.

[0067] The difference between Comparative Example 2 and Example 1 is that the set temperature of the first three zones of the screw extruder is increased, while the set temperature of the last three zones of the screw extruder is decreased.

[0068] The difference between Comparative Example 3 and Example 1 is that the melt pressure inside the screw extruder is reduced.

[0069] The difference between Comparative Example 4 and Example 1 is that the cooling temperature of the nascent fibers in the cooling bath system is increased.

[0070] The difference between Comparative Example 5 and Example 1 is that the temperature of the feed drafting roller is increased, the temperature of the output drafting roller is increased, the temperature of the constant temperature chamber is increased, and the drafting ratio is decreased.

[0071] The difference between Comparative Example 6 and Example 1 is that the set temperature of the first three zones of the screw extruder is increased, the set temperature of the last three zones of the screw extruder is decreased, the melt pressure inside the screw extruder is decreased, the cooling temperature of the cooling bath system for spinning is increased, the temperature of the feed drafting roller is increased, the temperature of the output drafting roller is increased, the temperature of the constant temperature chamber is increased, and the drafting ratio is decreased.

[0072] To characterize the anti-lodging performance of the PBT monofilaments prepared in the above embodiments and comparative examples, the monofilaments were fabricated into standard toothbrushes and tested with a 335g weight. The testing speed was 13mm / s, and the testing time was 24 hours. The anti-lodging effect of the monofilaments was determined based on the proportion of lodged monofilaments. The evaluation criteria were: no lodging: 0-30%; slight lodging: 30-50%; lodging: 50-70%; significant lodging: 70-90%; complete lodging: 100%. The test results of the anti-lodging performance of the PBT monofilaments prepared in each example are as follows:

[0073] Table 1. Lodging resistance test results of PBT monofilaments

[0074] Group Lodging resistance Example 1 No lodging Comparative Example 1 lodging Comparative Example 2 Slight lodging Comparative Example 3 Slight lodging Comparative Example 4 Slight lodging Comparative Example 5 Slight lodging Comparative Example 6 lodging

[0075] To characterize the breaking properties of the PBT monofilaments prepared in the above examples and comparative examples, the breaking strength and elongation at break of the PBT monofilaments prepared in each example were tested according to the FZ / T 54064-2012 polyester monofilament industry standard, and the spinning draw properties were evaluated. The following test results were obtained:

[0076] Table 2. Test results of the breaking properties and spinning draw properties of PBT monofilaments.

[0077]

[0078]

[0079] As shown in Tables 1 and 2, the process method described in this application for producing multifilament PBT monofilament achieves the basic shape of the monofilament by using the fundamental concept of multifilament. During the drawing process, every three monofilaments are bundled into a multifilament bundle. In subsequent processes such as water cooling and oiling, the drawing and winding are completed in a multifilament pattern. This solves the problem of poor lodging resistance of PBT monofilament while maintaining the same monofilament specifications. In addition to maintaining its breaking strength and elongation at break without significant reduction, it also makes PBT monofilament easier to draw and stretch.

[0080] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a multifilament anti-lodging PBT monofilament, characterized in that: S1: The dried and vacuum-packed PBT granules are fed into a screw extruder and heated to melt, resulting in molten polybutylene terephthalate. The set temperatures of each zone of the screw extruder from front to back are 240±2℃, 255±2℃, 270±2℃, 285±2℃, 290±2℃, 295±2℃, and 295±2℃; the melt pressure is 120±0.1 bar. S2: The molten polybutylene terephthalate is filtered through a melt filtration system; the filtered molten polybutylene terephthalate is then extruded through a screw extruder and spinneret to form viscous nascent fibers, which are then cooled in a cooling bath system at a temperature of 35±0.1℃; the spinneret assembly has 240 spinneret holes, with 3 spinneret holes forming a group; S3: After cooling, the nascent fibers are separated by a splitting device with 80 splitting holes, and then enter the oiling system for oiling. The oil content of each filament is controlled at 1.0%±0.

1. Then, they enter the drawing machine, with a total drawing ratio of 4.5-5.5 times. The temperature of the feed drawing roller is 65±0.1℃, and the temperature of the output drawing roller is 100±0.1℃. S4: After stretching, the product is wound up, graded and packaged; in step S2, the hole spacing in each group of spinnerets is d1, and the hole spacing between adjacent groups of spinnerets is d2, where d1 < d2; the temperature of the constant temperature chamber of the stretching machine is 85 ± 0.1℃.

2. The preparation method according to claim 1, characterized in that... The screw extruder has a length-to-diameter ratio of 30:1 and a rotational speed of 150-250 rpm.

3. The preparation method according to claim 2, characterized in that... The nascent fibers, after cooling, need to undergo dehumidification treatment before entering the drawing machine.

4. A multifilament anti-lodging PBT monofilament, characterized in that, It is prepared by the preparation method described in any one of claims 1-3.

5. The multifilament anti-lodging PBT monofilament as described in claim 4, characterized in that, The diameter of the multifilament anti-loosening PBT monofilament is 0.08-1.0 mm.

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