Preparation method of cloud hemp silk for air-permeable fabric

Abstract

The application belongs to the technical field of textiles, and particularly relates to a preparation method of breathable fabric cloud hemp silk, wherein the silk bundle sequentially passes through a first oiling device, a pre-networker, a first guide roller, a first hot roller, a second hot roller, a third hot roller, a fourth hot roller, a second oiling device, a second guide roller, a main networker, a third guide roller and a winding device; the roughness of the periphery of the first guide roller is uniform, and the value range is 1.3-1.5 microns; the periphery of the first hot roller and the second hot roller is divided into two parts which are respectively symmetrically distributed along the central axes of the first hot roller and the second hot roller, the roughness of one part is 0.1-0.15 microns, and the roughness of the other part is 1.3-1.5 microns. The present application does not change the winding turns, only changes the roughness of the first guide roller, the roughness of the first hot roller and the roughness of the second hot roller, effectively improves the irregular bamboo joint effect of the breathable fabric cloud hemp silk, and simultaneously reduces the hairiness and broken ends.

Description

Technical Field

[0001] This invention belongs to the field of textile technology, specifically relating to a method for preparing cloud hemp yarn for breathable fabrics. Background Technology

[0002] Breathable fabrics play a vital role in everyday wear, ensuring comfort even in hot weather or during strenuous activities. Slub yarn, a type of slub yarn, exhibits irregular variations in internode length and spacing. Slub yarn is a long filament yarn with diverse characteristics along its length, including thickness, crystal orientation, dyeing depth, boiling water shrinkage, and initial modulus. Due to its irregular slub effect, breathable fabrics woven from slub yarn are highly popular with consumers. Therefore, researching methods for preparing slub yarn for breathable fabrics is of significant importance.

[0003] Patent CN101748502B discloses an FDY polyester slub filament and its preparation method. It adopts the FDY process, with a stretching speed of 2800-3200 m / min, a stretching pre-network pressure of 0.22 MPa, a stretching ratio of 1.9-2.2, hot roller speeds GR1 / GR2 of 1400-1600 m / min and 2800-3200 m / min, and hot roller temperatures GR1 / GR2 of 65-75℃ and 108-118℃, respectively. By reducing the number of filament turns, the filament bundle slips on the hot roller, thus achieving an irregular slub effect.

[0004] However, the technical solution disclosed in CN101748502B still has the following shortcomings: In order to achieve the stretching of the filament bundle before it is fully heated, the temperature of the first hot roller is low, and a smaller number of winding turns are used, which can easily lead to problems such as fuzzy filaments and broken ends, or even failure to wind and form, and is not conducive to improving the irregular bamboo joint effect.

[0005] Therefore, there is an urgent need for a method to prepare cloud hemp yarn for breathable fabrics that can effectively improve the irregular slub effect while reducing fuzz and breakage. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a method for preparing cloud hemp yarn for breathable fabrics.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing breathable fabric cloud hemp yarn (i.e. bamboo-joint drawn yarn with irregularly varying internode length and internode spacing) involves the yarn bundle sequentially passing through a first oiling device, a pre-networker, a first guide roller, a first hot roller, a second hot roller, a third hot roller, a fourth hot roller, a second oiling device, a second guide roller, a main networker, a third guide roller, and a winding device.

[0009] The surface roughness of the first guide roller is uniform, ranging from 1.3 to 1.5 μm.

[0010] The circumferential surface of the first hot roller is divided into two parts symmetrically distributed along the central axis of the first hot roller. The roughness of one part is 0.1-0.15μm, and the roughness of the other part is 1.3-1.5μm.

[0011] The circumferential surface of the second hot roller is divided into two parts symmetrically distributed along the central axis of the second hot roller. The roughness of one part is 0.1-0.15μm, and the roughness of the other part is 1.3-1.5μm.

[0012] The surface roughness of the third hot roller is uniform, ranging from 0.30 to 0.35 μm.

[0013] The surface roughness of the fourth hot roller is uniform, ranging from 0.30 to 0.35 μm.

[0014] The number of turns of the filament bundle wound on the first to fourth hot rollers is 0.5 turns each;

[0015] The surface roughness of the second and third guide rollers is uniform, ranging from 1.3 to 1.5 μm.

[0016] The first guide roller, the first hot roller, the second hot roller, the third hot roller, the fourth hot roller, the second guide roller, and the third guide roller are all cylindrical structures. The diameter of the first to third guide rollers is 110 mm, and the diameter of the first to fourth hot rollers is 220 mm.

[0017] As a preferred technical solution:

[0018] In the above-described method for preparing breathable fabric using cloud hemp fiber, the first oiling device is an oil nozzle;

[0019] The air pressure of the pre-network device is 0.38-0.45 MPa;

[0020] The pre-networker is a vertical plate with a uniform cross-section and horizontally arranged airflow nozzles. A certain cross-section of the pre-networker passes through the airflow nozzles. The cross-section is an Archimedean spiral with a polar angle of ≥360° and ≤450°. The airflow nozzles are located at a position with a polar angle of 180° on the Archimedean spiral and face the center of the Archimedean spiral.

[0021] The guide hooks at the inlet and outlet of the pre-networker are grooved guide hooks, which consist of a U-shaped guide hook and a limiting block. The U-shaped guide hook is arranged horizontally, and the limiting block is connected to the inner wall of the U-shaped guide hook to limit the wire bundle within the bottom area of ​​the U-shaped guide hook. The wire bundle passes from top to bottom through the bottom area of ​​the upper grooved guide hook, the center of the pre-networker, and the bottom area of ​​the lower grooved guide hook.

[0022] The present invention sets the air pressure of the pre-networker to 0.38-0.45 MPa (significantly higher than the air pressure of 2.8-3.0 kgf / cm² described in patent application CN109594137A). 2 This increases the strength and density of the network dots, thereby improving the density of the bamboo joints. To avoid problems such as fuzzy fibers, broken fibers, uneven network dots, and inability to complete the initial growth due to increased air pressure in the pre-networker, this invention changes the oiling method of CN109594137A from oil wheel oiling to oil nozzle oiling, replaces the pre-networker of CN109594137A with a pre-networker having an Archimedean spiral structure, and replaces the U-shaped guide hooks at the front and rear of the pre-networker of CN109594137A with grooved guide hooks. Specific details are as follows:

[0023] This invention uses an oil nozzle for oiling. After the filament bundle enters the filament channel of the oil nozzle, the oil is sprayed out from the oil spray hole of the oil nozzle to oil the filament bundle. After oiling, the individual filaments of the filament bundle also have good mutual adhesion and can be bundled. Compared with CN109594137A, the bundling distance is reduced.

[0024] This invention employs a pre-networker with an Archimedean spiral structure. Its inner chamber is a relatively closed structure that can lock the filament bundle, preventing it from jumping out of the pre-networker. At the same time, it can optimize the stress point of the filament bundle after entering the pre-networker, resulting in better cohesion of the individual filaments within the pre-networker, ensuring the networking point. Furthermore, it can allow the airflow inside the pre-networker to be discharged after rotation, making the air pressure inside the pre-networker more stable. The filament bundle is less likely to rub against the edge of the pre-networker, which can also reduce the generation of fuzz and broken ends, and improve the breaking strength of the filament bundle.

[0025] This invention uses two grooved wire guide hooks to position the wire bundle in the middle of the pre-networker, resulting in a more consistent stress point after the wire bundle enters the pre-networker. If a conventional U-shaped wire guide hook (whose cross-section is as shown) is used, the wire bundle will be more evenly stressed. Figure 3 As shown in Figure a), the large angle between the filament bundle and the pre-networker can cause the filament bundle to not be fixed in the middle position of the pre-networker, resulting in inconsistent force points and uneven network points.

[0026] The method for preparing breathable fabric hemp yarn as described above has the following characteristics: the Archimedean spiral coefficient is 1-2 mm / °, and the polar diameter is 1.5-2 mm when the polar angle is 0°; the airflow nozzle is a circular hole with a diameter of 1.1-1.3 mm, and is located in the middle of the pre-network in the vertical direction; the length of the pre-network in the vertical direction is 23-27 mm.

[0027] In the above-described method for preparing breathable fabric hemp yarn, the distance between each grooved guide hook and the pre-networker is 13-17mm in the vertical direction; the angle α between the upper grooved guide hook and the vertical direction is 5-10°; and the angle β between the lower grooved guide hook and the vertical direction is 5-10°.

[0028] In the above-described method for preparing breathable fabric hemp yarn, the airflow nozzles of the pre-spinning unit at each spinning position are connected to a branch pipe, and all the branch pipes are connected to the same main pipe. An automatic pressure regulating valve is provided on the air inlet end of the main pipe.

[0029] In the above-described method for preparing breathable fabric hemp yarn, the linear speed of the first guide roller is 1580-1600 m / min, the temperature of the first hot roller is 50-60℃, and the linear speed of the first hot roller is 1590-1610 m / min; the temperature of the second hot roller is 50-60℃, and the linear speed of the second hot roller is 1690-1710 m / min; the temperature of the third hot roller is 100-110℃, and the linear speed of the third hot roller is 3100-3200 m / min; the temperature of the fourth hot roller is 100-110℃, and the linear speed of the fourth hot roller is 3100-3200 m / min; the linear speed of the second guide roller is 3110-3210 m / min; the linear speed of the third guide roller is 3125-3225 m / min; and the winding speed of the winding device is 3175-3275 m / min.

[0030] As described above, in the preparation method of breathable fabric hemp yarn, the air pressure of the main networker is 0.38-0.42 MPa; the first oiling device uses crude oil for oiling, with an oiling rate of 0.4-0.5%; the second oiling device uses an oiling agent with a concentration of 19.5-20.5 wt% (the mass of the oiling agent is the percentage of the total mass of the oiling agent and water), with an oiling rate of 0.5-0.6%. The traditional process route involves oiling once after drafting and setting, but because the air pressure of the pre-networker is high, if the yarn bundle is not oiled after cooling, fuzz is likely to occur. Therefore, this invention adds an oiling step in the spinning stage.

[0031] The above-described method for preparing breathable fabric hemp yarn contains 0.21-0.24 wt% of a matting agent in the yarn bundle, and the yarn bundle specifications are 50-61 dtex / 24f.

[0032] The preparation method of breathable fabric hemp yarn as described in any of the above claims has the following characteristics: the yarn evenness rate (CV) of the breathable fabric hemp yarn is 13.5-15.6% (a performance indicator reflecting the degree of local unevenness and irregularity in the thickness of the breathable fabric hemp yarn); the slub density is 26-30 nodes / meter; the breaking elongation is 84.8-85.7%; the breaking strength is 3.45-3.61 cN / dtex; the boiling water shrinkage rate is 34.1-36.5%; the maximum slub length before the boiling water shrinkage test is 0.43-0.71 cm; the maximum slub length after the boiling water shrinkage test is 0.28-0.46 cm; the downgrading rate of the fuzz is ≤0.05%; the number of breaks is ≤5.3 times / 18 positions·24 hours; and the network degree deviation is ≤3 nodes / meter.

[0033] Beneficial effects:

[0034] (1) The present invention does not change the number of winding turns, but adjusts the gripping force of the filament bundle on the circumferential surface by changing the roughness of the first guide roller, the roughness of the first hot roller and the roughness of the second hot roller, forming a stretching slippage. Through this stretching change, the irregular bamboo joint effect of the filament bundle is achieved.

[0035] (2) When the drawing slips, the present invention affects the spinning tension by the roughness of the first guide roller, so that the fiber crystallization in the spinning stage becomes irregular, and the irregular slub effect of the filament bundle is better.

[0036] (3) The roughness of the two halves of the first and second hot rollers of the present invention is different, and the heating efficiency is also different. The change in heating efficiency further improves the irregular bamboo joint effect of the filament bundle.

[0037] (4) By changing the circumferential surface roughness of the first guide roller, the first hot roller and the second hot roller, the present invention can adjust the holding force of the filament on the first guide roller, the first hot roller and the second hot roller, thereby reducing the breakage during the drawing process.

[0038] (5) The present invention adjusts the contact area of ​​the filament bundle on the first and second hot rollers by changing the circumferential surface roughness of the first guide roller, the first hot roller and the second hot roller, thereby adjusting the heating efficiency of the filament bundle on the first and second hot rollers, avoiding cold stretching, and thus reducing the number of filaments. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the apparatus for preparing breathable fabric hemp fiber according to the present invention;

[0040] Figure 2This is a schematic diagram of the pre-networker of the present invention, where the dashed circles represent the airflow nozzles of the pre-networker;

[0041] Figure 3 The figures are schematic diagrams of cross-sections of pre-networkers in the prior art and the present invention. a is a schematic diagram of the cross-section of a conventional pre-networker in the prior art, and b is a schematic diagram of the cross-section of the pre-networker of the present invention. The arrows in the figures represent airflow.

[0042] Figure 4 This is a schematic diagram of the grooved guide wire hook of the present invention;

[0043] In the figure, 1 is the first oiling device, 2 is the pre-networker, 3 is the first guide roller, 4 is the first hot roller, 5 is the second hot roller, 6 is the third hot roller, 7 is the fourth hot roller, 8 is the second oiling device, 9 is the second guide roller, 10 is the main networker, 11 is the third guide roller, 12 is the winding device, 13 is the yarn bundle, 14 is the U-shaped guide hook, 15 is the limiting block, 16 is the upper grooved guide hook, and 17 is the lower grooved guide hook. Detailed Implementation

[0044] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0045] The following are the test methods for the relevant performance indicators in each embodiment and comparative example:

[0046] (1) Bamboo node density: The number of bamboo nodes per meter of bamboo bundle by visual observation.

[0047] (2) Breaking strength and elongation at break: Referring to GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", the samples were tested using a fully automatic single yarn tensile testing machine (model YG023B-Ⅱ). The specific process was as follows: the sample was first placed in an environment with a temperature of 20℃ and a relative humidity of 65% for 4 hours to adjust the humidity. Then, it was clamped by upper and lower clamps with a clamping length of 500mm. A pretension of 0.05cN / dtex was applied by a robot to stabilize the sample. At the beginning of the test, the lower clamp stretched the sample at a speed of 500mm / min until the sample broke. At the same time, the real-time data of the force sensor was recorded during the stretching process. The relationship curve between strength and elongation was plotted through the data collection system. Finally, the breaking strength and elongation at break of the sample were obtained through data processing and analysis.

[0048] (3) Boiling water shrinkage rate: The boiling water shrinkage rate of the sample was tested by twisting method according to GB / T 6505-2017 "Test method for heat shrinkage rate of chemical fiber filament (after treatment)". The sample was treated with boiling water, and the sample length before boiling water treatment and the sample length after boiling water treatment were measured at the same time. The formula for calculating the boiling water shrinkage rate is as follows:

[0049] Boiling water shrinkage rate = (sample length before boiling water treatment - sample length after boiling water treatment) / sample length before boiling water treatment × 100.

[0050] (4) Maximum bamboo section length before boiling water shrinkage test: The maximum bamboo section length within 1 meter was measured using a ruler.

[0051] (5) Maximum bamboo section length after boiling water shrinkage rate test: After the boiling water shrinkage rate test, the maximum bamboo section length within 1 meter was measured using a ruler.

[0052] (6) Downgrading rate of filaments: The downgrading of the filament cake is determined by whether there are more than 2 single filament breakage defects on its surface. If there are more than 2, it is downgraded due to filaments. Then, the downgrading rate of filaments is obtained by calculation formula: Downgrading rate of filaments = (number of downgraded filaments / total number of filaments) × 100%.

[0053] (7) Number of breaks: Breakage refers to the sudden breakage of a single filament during spinning. One breakage is counted as one instance. A statistical cycle is 10 days and 18 spinning positions. The number of breaks in 18 positions in 24 hours is calculated based on the average value.

[0054] (8) Network degree deviation: Network degree deviation = |Measured network degree - Standard value of network degree|. The measured network degree is tested according to FZ / T 50001-2016 "Test method for network degree of synthetic fiber filament - manual needle moving method". The specific process is as follows: the sample is adjusted to a suitable tension through the pre-tension system, and the filament separating needle is slowly moved in the filament with a length of 1 meter. When a network knot is encountered, the filament separating needle stops moving. The number of network knots is calculated in this way, which is the measured network degree.

[0055] (9) Evenness coefficient (CV): The sample was tested using a USTER 5 evenness tester in accordance with GB / T 14346-2015 "Test Method for Evenness of Chemical Fiber Filaments - Capacitive Method". The specific process is as follows: First, the sample was placed in an environment with a temperature of 20℃ and a humidity of 65% for 2 hours to adjust the humidity. Then, the sample was passed through the two plates of a capacitor at a uniform speed. The mass of the sample in each equal interval was converted into an electrical signal. The percentage of the standard deviation of all test electrical signals to the average value is the evenness coefficient (CV). The test speed was 200 m / min and the test time for the sample was 2.5 min.

[0056] Example 1

[0057] A method for preparing breathable fabric using cloud hemp yarn, employing an apparatus such as... Figure 1 , Figure 2 , Figure 3 b, Figure 4 As shown, the filament bundle 13 passes sequentially through the first oiling device 1, the bottom area of ​​the upper grooved guide hook 16, the center position of the pre-networker 2, the bottom area of ​​the lower grooved guide hook 17, the first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second oiling device 8, the second guide roller 9, the main networker 10, the third guide roller 11, and the winding device 12;

[0058] The tow 13 contains 0.22 wt% of a matting agent, which is titanium dioxide with an average particle size of 0.35 μm. The specification of the tow 13 is 50 dtex / 24f.

[0059] The first oiling device 1 is an oil nozzle, which uses crude oil for oiling, with an oiling rate of 0.4%.

[0060] The air pressure of pre-networker 2 is 0.40 MPa;

[0061] The pre-networker 2 is a vertical plate with a uniform cross section. It is provided with horizontally arranged airflow nozzles. A certain cross section of the pre-networker 2 passes through the airflow nozzle. The cross section is an Archimedean spiral with a polar angle of 360°. The airflow nozzle is located at a position with a polar angle of 180° on the Archimedean spiral and faces the center of the Archimedean spiral.

[0062] The guide wire hooks at the inlet and outlet of the pre-networker 2 are grooved guide wire hooks; such as Figure 4 As shown, the grooved guide hook consists of a U-shaped guide hook 14 and a limiting block 15. The U-shaped guide hook 14 is arranged horizontally, and the limiting block 15 is connected to the inner wall of the U-shaped guide hook 14 to limit the wire bundle 13 in the bottom area of ​​the U-shaped guide hook 14.

[0063] The Archimedean spiral has an Archimedean spiral coefficient of 1 mm / ° and a polar diameter of 1.5 mm when the polar angle is 0°; the airflow nozzle is a circular orifice with a diameter of 1.1 mm, and is located in the middle of the pre-networker 2 in the vertical direction; the length of the pre-networker 2 in the vertical direction is 25 mm.

[0064] Along the vertical direction, the distance between each grooved guide hook and the pre-network device 2 is 15mm; the angle α between the upper grooved guide hook 16 and the vertical direction of the wire bundle 13 is 8°; the angle β between the lower grooved guide hook 17 and the vertical direction of the wire bundle 13 is 8°; the angles α and β are as follows: Figure 1 As shown;

[0065] Each pre-network device 2 at each spinning station has an airflow nozzle connected to a branch pipe, and all branch pipes are connected to the same main pipe. An automatic pressure regulating valve is installed at the air inlet end of the main pipe.

[0066] The surface roughness of the first guide roller 3 is uniform, and the value ranges from 1.3μm.

[0067] The circumferential surface of the first hot roller 4 is divided into two parts symmetrically distributed along the central axis of the first hot roller 4. The roughness of one part is 0.1 μm, and the roughness of the other part is 1.3 μm.

[0068] The circumferential surface of the second hot roller 5 is divided into two parts symmetrically distributed along the central axis of the second hot roller 5. The roughness of one part is 0.1 μm, and the roughness of the other part is 1.3 μm.

[0069] The surface roughness of the third hot roller 6 is uniform, with a value range of 0.30 μm;

[0070] The surface roughness of the fourth hot roller 7 is uniform, with a value range of 0.30 μm;

[0071] The number of turns of the filament bundle 13 wound on the first hot roller 4 to the fourth hot roller 7 is 0.5 turns each;

[0072] The second oiling device 8 uses an oil agent with a concentration of 20 wt% for oiling, with an oiling rate of 0.6%.

[0073] The surface roughness of the second guide roller 9 and the third guide roller 11 is uniform, with a value range of 1.3 μm;

[0074] The first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second guide roller 9, and the third guide roller 11 are all cylindrical structures. The diameter of the first to third guide rollers is 110 mm, and the diameter of the first to fourth hot rollers is 220 mm.

[0075] The linear speed of the first guide roller 3 is 1580 m / min, the temperature of the first hot roller 4 is 52℃, and the linear speed of the first hot roller 4 is 1590 m / min. The temperature of the second hot roller 5 is 52℃, and the linear speed of the second hot roller 5 is 1690 m / min. The temperature of the third hot roller 6 is 102℃, and the linear speed of the third hot roller 6 is 3100 m / min. The temperature of the fourth hot roller 7 is 102℃, and the linear speed of the fourth hot roller 7 is 3100 m / min. The linear speed of the second guide roller 9 is 3110 m / min. The air pressure of the main network device 10 is 0.38 MPa. The linear speed of the third guide roller 11 is 3125 m / min. The winding speed of the winding device 12 is 3175 m / min.

[0076] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 14.5%, a slub density of 28 nodes / meter, a breaking elongation of 85.7%, a breaking strength of 3.45 cN / dtex, a boiling water shrinkage rate of 34.1%, a maximum slub length of 0.51 cm before the boiling water shrinkage test, a maximum slub length of 0.34 cm after the boiling water shrinkage test, a fiber degradation rate of 0.05%, a breakage count of 5.3 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0077] Comparative Example 1

[0078] A method for preparing breathable fabric hemp yarn differs from Example 1 only in that the surface roughness of the first guide roller is uniform, and the roughness value is 1.0 μm.

[0079] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 10.9%, a slub density of 21 nodes / meter, a breaking elongation of 85.7%, a breaking strength of 3.46 cN / dtex, a boiling water shrinkage rate of 34.1%, a maximum slub length of 0.42 cm before the boiling water shrinkage test, a maximum slub length of 0.28 cm after the boiling water shrinkage test, a fiber degradation rate of 0.05%, a breakage count of 5.3 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0080] Compared with Example 1, Comparative Example 1 showed no significant changes in elongation at break, breaking strength, boiling water shrinkage, filament degradation rate, number of breakages, and network density deviation. However, the uniformity (CV) of the bamboo strands decreased by 24.8%, the bamboo node density decreased by 25%, and the maximum bamboo node length before and after the boiling water shrinkage test decreased by 17.6%. This is because roughness is characterized by the difference between the peaks and valleys of a solid surface. Smaller roughness indicates a smaller difference between the peaks and valleys, resulting in a smoother connection between the filament bundle and the solid surface. The larger contact area of ​​the surface results in better gripping force of the filament bundle on the solid surface. The circumferential surface roughness of the first guide roller is 1.0 μm, which is relatively small. The gripping force of the filament bundle on the first guide roller is better, and it is not easy to slip. Therefore, the bamboo node density is reduced and the CV value of the unevenness of the yarn is reduced. Moreover, because the gripping force of the filament bundle on the first guide roller is better, the vibration of the filament bundle after entering the hot roller is smaller, which makes the heating of the filament bundle on the hot roller more uniform and makes it easier to heat some network points thoroughly. Therefore, the maximum bamboo node length before and after the boiling water shrinkage rate test is smaller.

[0081] Comparative Example 2

[0082] A method for preparing breathable fabric hemp yarn differs from Example 1 only in that the surface roughness of the first guide roller is uniform, with a roughness value of 1.8 μm.

[0083] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 15.4%, a slub density of 30 nodes / meter, a breaking elongation of 85.1%, a breaking strength of 3.45 cN / dtex, a boiling water shrinkage rate of 34.2%, a maximum slub length of 0.56 cm before the boiling water shrinkage test, a maximum slub length of 0.37 cm after the boiling water shrinkage test, a fiber degradation rate of 0.09%, a breakage count of 7.6 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0084] Compared with Example 1, the changes in elongation at break, breaking strength, boiling water shrinkage rate, and network density deviation in Comparative Example 2 were not significant. The maximum bamboo joint length before the boiling water shrinkage rate test increased by 9.8%, and the maximum bamboo joint length after the boiling water shrinkage rate test increased by 8.8%. The rate of fuzz downgrading increased by 80%, and the number of breaks increased by 43.4%. This is because: the circumferential surface roughness of the first guide roller is 1.8 μm. The roughness is relatively large, resulting in poor holding force of the filament bundle on the first guide roller, which leads to the inability of the filament bundle to form stretch on the first guide roller, and even the problem of being unable to produce by winding around the roller, thus increasing the number of breaks; at the same time, due to the large circumferential surface roughness of the first guide roller, the filament bundle vibrates greatly after entering the hot roller from the first guide roller, resulting in a small contact area of ​​the filament bundle on the hot roller, which leads to poor heating efficiency on the hot roller and easy cold stretching, thus increasing the number of fuzz; because the contact area of ​​the filament bundle on the hot roller is small, the network points cannot be completely heated through, so the maximum bamboo joint length increases before and after the boiling water shrinkage rate test.

[0085] Comparative Example 3

[0086] A method for preparing breathable fabric hemp fiber differs from Example 1 only in that: the surface roughness of the first hot roller is uniform and is 0.1 μm, and the surface roughness of the second hot roller is also uniform and is 0.1 μm.

[0087] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 10.5%, a slub density of 20 nodes / meter, a breaking elongation of 84.0%, a breaking strength of 3.51 cN / dtex, a boiling water shrinkage rate of 34.1%, a maximum slub length of 0.40 cm before the boiling water shrinkage test, a maximum slub length of 0.26 cm after the boiling water shrinkage test, a fiber degradation rate of 0.05%, a breakage count of 5.1 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0088] Compared with Example 1, Comparative Example 3 showed no significant changes in boiling water shrinkage rate, filament degradation rate, number of breakages, and network density deviation. The evenness rate (CV) decreased by 27.6%, the bamboo node density decreased by 28.6%, the maximum bamboo node length before the boiling water shrinkage test decreased by 21.6%, and the maximum bamboo node length after the boiling water shrinkage test decreased by 23.5%. The elongation at break decreased by 2%, and the breaking strength increased by 1.7%. This is because the circumferential surface roughness of the first and second hot rollers is uniform and consistent, both with a roughness of 0.1 μm, and the roughness is relatively small, resulting in the filament bundle exhibiting uniformity on the first and second hot rollers. The better gripping force on the rollers reduces slippage, thus decreasing the bamboo node density and the CV value of unevenness. Simultaneously, due to the lower roughness, the contact area of ​​the filament bundle on the first and second hot rollers is larger, resulting in higher heating efficiency on these rollers. This leads to more uniform heating of the filament bundle on the first hot roller, making it easier to thoroughly heat some network points, thus reducing the maximum bamboo node length. Furthermore, the better gripping force on the first and second hot rollers results in a higher effective draw ratio and a higher degree of molecular orientation between the third and second hot rollers, leading to increased breaking strength and decreased breaking elongation.

[0089] Comparative Example 4

[0090] A method for preparing breathable fabric hemp fiber differs from Example 1 only in that: the surface roughness of the first hot roller is uniform and is 1.3 μm, and the surface roughness of the second hot roller is also uniform and is 1.3 μm.

[0091] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 14.7%, a slub density of 29 nodes / meter, a breaking elongation of 84.9%, a breaking strength of 3.42 cN / dtex, a boiling water shrinkage rate of 34.2%, a maximum slub length of 0.62 cm before the boiling water shrinkage test, a maximum slub length of 0.41 cm after the boiling water shrinkage test, a fiber degradation rate of 0.10%, a breakage count of 8.4 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0092] Compared with Example 1, the changes in the uniformity (CV) of the bamboo strands, bamboo node density, elongation at break, breaking strength, boiling water shrinkage rate, and network density deviation of Comparative Example 4 were not significant. The maximum bamboo node length before the boiling water shrinkage rate test increased by 21.6%, and the maximum bamboo node length after the boiling water shrinkage rate test increased by 20.6%. The downgrading rate of the fibrous strands increased by 100%, and the number of breakages increased by 58.5%. This is because the surface roughness of the first and second hot rollers is uniform and consistent, both with a roughness of 1.3 μm, and the roughness is relatively large, which causes the fibrous strands to have a larger impact on the fiber bundles in the first... The gripping force on the first and second hot rollers is relatively small, which easily leads to problems with stretching, thus increasing the number of breakages. At the same time, due to the large circumferential roughness of the first and second hot rollers, the contact area of ​​the filament bundle on the first and second hot rollers is small, resulting in poor heating efficiency on the first and second hot rollers and easy cold stretching, thus increasing the number of fuzzy filaments. Because the contact area of ​​the filament bundle on the first and second hot rollers is small, the network points cannot be fully heated, thus increasing the maximum bamboo joint length before and after the boiling water shrinkage rate test.

[0093] Example 2

[0094] A method for preparing breathable fabric using cloud hemp yarn, employing an apparatus such as... Figure 1 , Figure 2 , Figure 3 b, Figure 4 As shown, the filament bundle 13 passes sequentially through the first oiling device 1, the bottom area of ​​the upper grooved guide hook 16, the center position of the pre-networker 2, the bottom area of ​​the lower grooved guide hook 17, the first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second oiling device 8, the second guide roller 9, the main networker 10, the third guide roller 11, and the winding device 12;

[0095] The tow 13 contains 0.21 wt% of a matting agent, which is titanium dioxide with an average particle size of 0.35 μm. The specification of the tow 13 is 55 dtex / 24f.

[0096] The first oiling device 1 is an oil nozzle; the first oiling device 1 uses crude oil for oiling, and the oiling rate is 0.45%;

[0097] The air pressure of pre-networker 2 is 0.38 MPa;

[0098] The pre-networker 2 is a vertical plate with a uniform cross-section and horizontally arranged airflow nozzles. A certain cross-section of the pre-networker 2 passes through the airflow nozzles. The cross-section is an Archimedean spiral with a polar angle of 400°. The airflow nozzles are located at a position with a polar angle of 180° on the Archimedean spiral and face the center of the Archimedean spiral.

[0099] The guide wire hooks at the inlet and outlet of the pre-networker 2 are grooved guide wire hooks; such as Figure 4 As shown, the grooved guide wire hook consists of a U-shaped guide wire hook 14 and a limiting block 15, as... Figure 4 As shown; the U-shaped guide hook 14 is arranged horizontally, and the limiting block 15 is connected to the inner wall of the U-shaped guide hook 14 to limit the wire bundle 13 in the bottom area of ​​the U-shaped guide hook 14.

[0100] The Archimedean spiral has an Archimedean spiral coefficient of 1.6 mm / ° and a polar diameter of 1.7 mm when the polar angle is 0°. The airflow nozzle is a circular orifice with a diameter of 1.2 mm. In the vertical direction, the airflow nozzle is located in the middle of the pre-network device 2. In the vertical direction, the length of the pre-network device 2 is 23 mm.

[0101] Along the vertical direction, the distance between each grooved guide hook and the pre-network device 2 is 13mm; the angle α between the wire bundle 13 at the upper grooved guide hook 16 and the vertical direction is 6°; the angle β between the wire bundle 13 at the lower grooved guide hook 17 and the vertical direction is 6°; the angles α and β are as follows: Figure 1 As shown;

[0102] Each pre-network device 2 at each spinning station has an airflow nozzle connected to a branch pipe, and all branch pipes are connected to the same main pipe. An automatic pressure regulating valve is installed at the air inlet end of the main pipe.

[0103] The surface roughness of the first guide roller 3 is uniform, and the value ranges from 1.4 μm.

[0104] The circumferential surface of the first hot roller 4 is divided into two parts symmetrically distributed along the central axis of the first hot roller 4. The roughness of one part is 0.14 μm, and the roughness of the other part is 1.4 μm.

[0105] The circumferential surface of the second hot roller 5 is divided into two parts symmetrically distributed along the central axis of the second hot roller 5. The roughness of one part is 0.14 μm, and the roughness of the other part is 1.4 μm.

[0106] The surface roughness of the third hot roller 6 is uniform, with a value range of 0.33 μm;

[0107] The surface roughness of the fourth hot roller 7 is uniform, with a value range of 0.33 μm;

[0108] The number of turns of the filament bundle 13 wound on the first hot roller 4 to the fourth hot roller 7 is 0.5 turns each;

[0109] The second oiling device 8 uses an oil agent with a concentration of 19.5 wt% for oiling, with an oiling rate of 0.55%.

[0110] The surface roughness of the second guide roller 9 and the third guide roller 11 is uniform, with a value range of 1.4 μm.

[0111] The first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second guide roller 9, and the third guide roller 11 are all cylindrical structures. The diameter of the first to third guide rollers is 110 mm, and the diameter of the first to fourth hot rollers is 220 mm.

[0112] The linear speed of the first guide roller 3 is 1590 m / min, the temperature of the first hot roller 4 is 50℃, and the linear speed of the first hot roller 4 is 1600 m / min. The temperature of the second hot roller 5 is 50℃, and the linear speed of the second hot roller 5 is 1700 m / min. The temperature of the third hot roller 6 is 100℃, and the linear speed of the third hot roller 6 is 3130 m / min. The temperature of the fourth hot roller 7 is 100℃, and the linear speed of the fourth hot roller 7 is 3130 m / min. The linear speed of the second guide roller 9 is 3140 m / min. The air pressure of the main network device 10 is 0.4 MPa. The linear speed of the third guide roller 11 is 3155 m / min. The winding speed of the winding device 12 is 3205 m / min.

[0113] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 14.1%, a slub density of 26 nodes / meter, a breaking elongation of 85.3%, a breaking strength of 3.47 cN / dtex, a boiling water shrinkage rate of 36.5%, a maximum slub length of 0.61 cm before the boiling water shrinkage test, a maximum slub length of 0.39 cm after the boiling water shrinkage test, a fiber degradation rate of 0.04%, a breakage count of 4.7 times / 18 positions·24 hours, and a network density deviation of 2 nodes / meter (the standard network density value is 22 nodes / meter).

[0114] Example 3

[0115] A method for preparing breathable fabric using cloud hemp yarn, employing an apparatus such as... Figure 1 , Figure 2 , Figure 3 b, Figure 4 As shown, the filament bundle 13 passes sequentially through the first oiling device 1, the bottom area of ​​the upper grooved guide hook 16, the center position of the pre-networker 2, the bottom area of ​​the lower grooved guide hook 17, the first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second oiling device 8, the second guide roller 9, the main networker 10, the third guide roller 11, and the winding device 12;

[0116] The tow 13 contains 0.23 wt% of a matting agent, which is titanium dioxide with an average particle size of 0.35 μm. The specification of the tow 13 is 56 dtex / 24f.

[0117] The first oiling device 1 is an oil nozzle; the first oiling device 1 uses crude oil for oiling, and the oiling rate is 0.45%;

[0118] The air pressure of pre-networker 2 is 0.42 MPa;

[0119] The pre-networker 2 is a vertical plate with a uniform cross-section and horizontally arranged airflow nozzles. A certain cross-section of the pre-networker 2 passes through the airflow nozzles. The cross-section is an Archimedean spiral with a polar angle of 420°. The airflow nozzles are located at a position with a polar angle of 180° on the Archimedean spiral and face the center of the Archimedean spiral.

[0120] The guide wire hooks at the inlet and outlet of the pre-networker 2 are grooved guide wire hooks; such as Figure 4 As shown, the grooved guide hook consists of a U-shaped guide hook 14 and a limiting block 15. The U-shaped guide hook 14 is arranged horizontally, and the limiting block 15 is connected to the inner wall of the U-shaped guide hook 14 to limit the wire bundle 13 in the bottom area of ​​the U-shaped guide hook 14.

[0121] The Archimedean spiral has an Archimedean spiral coefficient of 1.8 mm / ° and a polar diameter of 1.8 mm when the polar angle is 0°. The airflow nozzle is a circular orifice with a diameter of 1.2 mm. In the vertical direction, the airflow nozzle is located in the middle of the pre-network device 2. In the vertical direction, the length of the pre-network device 2 is 26 mm.

[0122] Along the vertical direction, the distance between each grooved guide hook and the pre-network device 2 is 15mm; the angle α between the upper grooved guide hook 16 and the vertical direction of the wire bundle 13 is 5°; the angle β between the lower grooved guide hook 17 and the vertical direction of the wire bundle 13 is 5°; the angles α and β are as follows: Figure 1 As shown;

[0123] Each pre-network device 2 at each spinning station has an airflow nozzle connected to a branch pipe, and all branch pipes are connected to the same main pipe. An automatic pressure regulating valve is installed at the air inlet end of the main pipe.

[0124] The surface roughness of the first guide roller 3 is uniform, and the value ranges from 1.5μm.

[0125] The circumferential surface of the first hot roller 4 is divided into two parts symmetrically distributed along the central axis of the first hot roller 4. The roughness of one part is 0.15 μm, and the roughness of the other part is 1.5 μm.

[0126] The circumferential surface of the second hot roller 5 is divided into two parts symmetrically distributed along the central axis of the second hot roller 5. The roughness of one part is 0.15 μm, and the roughness of the other part is 1.5 μm.

[0127] The surface roughness of the third hot roller 6 is uniform, with a value range of 0.35μm;

[0128] The surface roughness of the fourth hot roller 7 is uniform, with a value range of 0.35 μm;

[0129] The number of turns of the filament bundle 13 wound on the first hot roller 4 to the fourth hot roller 7 is 0.5 turns each;

[0130] The second oiling device 8 uses an oil agent with a concentration of 20.5 wt% for oiling, with an oiling rate of 0.5%.

[0131] The surface roughness of the second guide roller 9 and the third guide roller 11 is uniform, with a value range of 1.5μm.

[0132] The first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second guide roller 9, and the third guide roller 11 are all cylindrical structures. The diameter of the first to third guide rollers is 110 mm, and the diameter of the first to fourth hot rollers is 220 mm.

[0133] The linear speed of the first guide roller 3 is 1590 m / min, the temperature of the first hot roller 4 is 55℃, and the linear speed of the first hot roller 4 is 1600 m / min. The temperature of the second hot roller 5 is 55℃, and the linear speed of the second hot roller 5 is 1700 m / min. The temperature of the third hot roller 6 is 105℃, and the linear speed of the third hot roller 6 is 3150 m / min. The temperature of the fourth hot roller 7 is 105℃, and the linear speed of the fourth hot roller 7 is 3150 m / min. The linear speed of the second guide roller 9 is 3160 m / min. The air pressure of the main network device 10 is 0.42 MPa. The linear speed of the third guide roller 11 is 3175 m / min. The winding speed of the winding device 12 is 3225 m / min.

[0134] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 14.4%, a slub density of 27 nodes / meter, a breaking elongation of 85.4%, a breaking strength of 3.5 cN / dtex, a boiling water shrinkage rate of 35.1%, a maximum slub length of 0.43 cm before the boiling water shrinkage test, a maximum slub length of 0.28 cm after the boiling water shrinkage test, a fiber degradation rate of 0.04%, a breakage count of 3.6 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 22 nodes / meter).

[0135] Example 4

[0136] A method for preparing breathable fabric using cloud hemp yarn, employing an apparatus such as... Figure 1 , Figure 2 , Figure 3 b, Figure 4As shown, the filament bundle 13 passes sequentially through the first oiling device 1, the bottom area of ​​the upper grooved guide hook 16, the center position of the pre-networker 2, the bottom area of ​​the lower grooved guide hook 17, the first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second oiling device 8, the second guide roller 9, the main networker 10, the third guide roller 11, and the winding device 12;

[0137] The tow 13 contains 0.24 wt% of a matting agent, which is titanium dioxide with an average particle size of 0.35 μm. The tow 13 has a specification of 61 dtex / 24f.

[0138] The first oiling device 1 is an oil nozzle; the first oiling device 1 uses crude oil for oiling, with an oiling rate of 0.5%; the air pressure of the pre-network device 2 is 0.45 MPa;

[0139] The pre-networker 2 is a vertical plate with a uniform cross-section and horizontally arranged airflow nozzles. A certain cross-section of the pre-networker 2 passes through the airflow nozzles. The cross-section is an Archimedean spiral with a polar angle of 450°. The airflow nozzles are located at a position with a polar angle of 180° on the Archimedean spiral and face the center of the Archimedean spiral.

[0140] The guide wire hooks at the inlet and outlet of the pre-networker 2 are grooved guide wire hooks; such as Figure 4 As shown, the grooved guide hook consists of a U-shaped guide hook 14 and a limiting block 15. The U-shaped guide hook 14 is arranged horizontally, and the limiting block 15 is connected to the inner wall of the U-shaped guide hook 14 to limit the wire bundle 13 in the bottom area of ​​the U-shaped guide hook 14.

[0141] The Archimedean spiral has an Archimedean spiral coefficient of 2 mm / ° and a polar diameter of 2 mm when the polar angle is 0°; the airflow nozzle is a circular orifice with a diameter of 1.3 mm, and is located in the middle of the pre-networker 2 in the vertical direction; the length of the pre-networker 2 in the vertical direction is 27 mm.

[0142] Along the vertical direction, the distance between each grooved guide hook and the pre-network device 2 is 17mm; the angle α between the wire bundle 13 at the upper grooved guide hook 16 and the vertical direction is 10°; the angle β between the wire bundle 13 at the lower grooved guide hook 17 and the vertical direction is 10°; the angles α and β are as follows... Figure 1 As shown;

[0143] Each pre-network device 2 at each spinning station has an airflow nozzle connected to a branch pipe, and all branch pipes are connected to the same main pipe. An automatic pressure regulating valve is installed at the air inlet end of the main pipe.

[0144] The surface roughness of the first guide roller 3 is uniform, and the value ranges from 1.4 μm.

[0145] The circumferential surface of the first hot roller 4 is divided into two parts symmetrically distributed along the central axis of the first hot roller 4. The roughness of one part is 0.13 μm, and the roughness of the other part is 1.4 μm.

[0146] The circumferential surface of the second hot roller 5 is divided into two parts symmetrically distributed along the central axis of the second hot roller 5. The roughness of one part is 0.13 μm, and the roughness of the other part is 1.4 μm.

[0147] The surface roughness of the third hot roller 6 is uniform, with a value range of 0.32μm;

[0148] The surface roughness of the fourth hot roller 7 is uniform, with a value range of 0.32 μm;

[0149] The number of turns of the filament bundle 13 wound on the first hot roller 4 to the fourth hot roller 7 is 0.5 turns each;

[0150] The second oiling device 8 uses an oil agent with a concentration of 20 wt% for oiling, with an oiling rate of 0.53%.

[0151] The surface roughness of the second guide roller 9 and the third guide roller 11 is uniform, with a value range of 1.4 μm.

[0152] The first guide roller 3, the first hot roller 4, the second hot roller 5, the third hot roller 6, the fourth hot roller 7, the second guide roller 9, and the third guide roller 11 are all cylindrical structures. The diameter of the first to third guide rollers is 110 mm, and the diameter of the first to fourth hot rollers is 220 mm.

[0153] The linear speed of the first guide roller 3 is 1600 m / min, the temperature of the first hot roller 4 is 60℃, and the linear speed of the first hot roller 4 is 1610 m / min. The temperature of the second hot roller 5 is 60℃, and the linear speed of the second hot roller 5 is 1710 m / min. The temperature of the third hot roller 6 is 110℃, and the linear speed of the third hot roller 6 is 3200 m / min. The temperature of the fourth hot roller 7 is 110℃, and the linear speed of the fourth hot roller 7 is 3200 m / min. The linear speed of the second guide roller 9 is 3210 m / min. The air pressure of the main network device 10 is 0.4 MPa. The linear speed of the third guide roller 11 is 3225 m / min. The winding speed of the winding device 12 is 3275 m / min.

[0154] The final breathable fabric made from cloud hemp fibers had a yarn unevenness CV value of 15.6%, a slub density of 30 nodes / meter, a breaking elongation of 84.8%, a breaking strength of 3.61 cN / dtex, a boiling water shrinkage rate of 34.7%, a maximum slub length of 0.71 cm before the boiling water shrinkage test, a maximum slub length of 0.46 cm after the boiling water shrinkage test, a fiber degradation rate of 0.05%, a breakage count of 4.1 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0155] Example 5

[0156] A method for preparing breathable fabric hemp fiber differs from Example 1 only in that the polar angle of the Archimedes spiral is 350°.

[0157] The breathable fabric finally obtained in Example 5 has a yarn unevenness CV value of 13.7%, a slub density of 25 nodes / meter, a breaking elongation of 85.6%, a breaking strength of 3.47 cN / dtex, a boiling water shrinkage rate of 33.9%, a maximum slub length of 0.50 cm before the boiling water shrinkage test, a maximum slub length of 0.33 cm after the boiling water shrinkage test, a fiber degradation rate of 0.06%, a breakage count of 6.3 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard network density value is 23 nodes / meter).

[0158] Compared with Example 1, the breathable fabric made of cloud hemp yarn obtained in Example 5 showed a decrease in the evenness CV value and slub density, but an increase in the filament downgrading rate and breakage number. The remaining performance indicators did not change significantly. This is because when the polar angle of the Archimedes spiral is 350°, the larger network air pressure will be discharged from the pre-networker earlier, resulting in a decrease in network density, which in turn affects the slub density and evenness CV value. Furthermore, the earlier discharge of network air pressure will also cause the air pressure in the pre-networker to be unstable, and the yarn bundles will easily rub against the edge of the pre-networker, leading to an increase in filament downgrading and breakage.

[0159] Example 6

[0160] A method for preparing breathable fabric hemp fiber differs from Example 4 only in that the polar angle of the Archimedes spiral is 460°.

[0161] The breathable fabric finally obtained in Example 6 has a yarn unevenness CV value of 15.3%, a slub density of 29 nodes / meter, a breaking elongation of 84.6%, a breaking strength of 3.60 cN / dtex, a boiling water shrinkage rate of 34.9%, a maximum slub length of 0.72 cm before the boiling water shrinkage test, a maximum slub length of 0.47 cm after the boiling water shrinkage test, a fiber grade reduction rate of 0.07%, a breakage count of 5.9 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard value for network density is 23 nodes / meter).

[0162] Compared with Example 4, the breathable fabric made in Example 6 has an increased rate of fuzz downgrading and breakage of hemp fibers, while the remaining performance indicators do not change significantly. This is because when the polar angle of the Archimedes spiral is 460°, it will cause a large network air pressure to be unable to be discharged from the pre-networker in time, causing airflow turbulence in the pre-networker, which in turn leads to an increase in fuzz and breakage.

[0163] Example 7

[0164] A method for preparing breathable fabric hemp fiber differs from Example 1 only in that: in the pre-networker, the airflow nozzle is located at a position with a polar angle of 170° on the Archimedean spiral.

[0165] The breathable fabric finally obtained in Example 7 has a yarn unevenness CV value of 13.5%, a slub density of 25 nodes / meter, a breaking elongation of 85.9%, a breaking strength of 3.44 cN / dtex, a boiling water shrinkage rate of 33.8%, a maximum slub length of 0.49 cm before the boiling water shrinkage test, a maximum slub length of 0.32 cm after the boiling water shrinkage test, a fiber degradation rate of 0.07%, a breakage count of 6.0 times / 18 positions·24 hours, and a network density deviation of 3 nodes / meter (the standard value for network density is 23 nodes / meter).

[0166] Compared with Example 1, the breathable fabric made of cloud hemp yarn obtained in Example 7 showed a decrease in the evenness CV value and slub density, but an increase in the downgrade rate of fuzz and the number of breaks. The remaining performance indicators did not change significantly. This is because the airflow nozzle is located at a position with a polar angle of 170° on the Archimedean spiral, which easily causes the airflow in the pre-networker to blow directly into another spiral after being blown towards the yarn bundle. This causes the air pressure in the inner chamber of the pre-networker to be unstable, resulting in a decrease in the slub density and evenness CV value. At the same time, it also makes the yarn bundle more likely to rub against the edge of the pre-networker, leading to an increase in fuzz and the number of breaks.

[0167] Example 8

[0168] A method for preparing breathable fabric hemp yarn differs from Example 1 only in that the guide hooks at the inlet and outlet of the pre-networker are U-shaped guide hooks, and no limiting blocks are provided.

[0169] The breathable fabric finally obtained in Example 8 has a yarn unevenness CV value of 14.1%, a slub density of 27 nodes / meter, a breaking elongation of 85.9%, a breaking strength of 3.44 cN / dtex, a boiling water shrinkage rate of 34.2%, a maximum slub length of 0.49 cm before the boiling water shrinkage test, a maximum slub length of 0.32 cm after the boiling water shrinkage test, a fiber degradation rate of 0.08%, a breakage count of 7.0 times / 18 positions·24 hours, and a network density deviation of 4 nodes / meter (the standard network density value is 23 nodes / meter).

[0170] Compared with Example 1, the downgrade rate of lint, the number of breaks, and the network degree deviation of the breathable fabric made in Example 8 all increased. The remaining performance indicators did not change significantly. This is because the angle of the filament bundle before and after the pre-networker is large. The use of U-shaped guide hooks will cause the filament bundle to not be locked in the middle position of the pre-networker under the large pre-network air pressure, resulting in inconsistent force points, uneven network points, and increased network degree deviation. At the same time, due to the inconsistent force points, the filament bundle is more likely to rub against the edge of the pre-networker, which in turn leads to an increase in lint and the number of breaks.

[0171] Example 9

[0172] A method for preparing breathable fabric using cloud hemp yarn differs from Example 1 only in that the pre-network device is replaced with the pre-network device from patent application CN109594137A (cross-section as shown in the image). Figure 3 (as shown in a).

[0173] The breathable fabric finally obtained in Example 9 has a yarn unevenness CV value of 14.4%, a slub density of 28 nodes / meter, a breaking elongation of 85.4%, a breaking strength of 3.44 cN / dtex, a boiling water shrinkage rate of 33.9%, a maximum slub length of 0.50 cm before the boiling water shrinkage test, a maximum slub length of 0.33 cm after the boiling water shrinkage test, a fiber degradation rate of 0.07%, a breakage count of 6.9 times / 18 positions·24 hours, and a network density deviation of 4 nodes / meter (the standard value for network density is 23 nodes / meter).

[0174] Compared with Example 1, the downgrade rate of lint, the number of breaks, and the deviation of the network density of the breathable fabric made in Example 9 all increased. The remaining performance indicators did not change significantly. This is because the pre-networking air pressure was high, and the filament bundles swayed significantly in the pre-networking device. This resulted in inconsistent impact forces of the vertical jet airflow on the filament bundles in the pre-networking device, leading to uneven network points and a large deviation in the network density. At the same time, the spiral airflow in the pre-networking device could not be discharged, causing friction between the filament bundles and the pre-networking device, which in turn led to an increase in lint and the number of breaks.

Claims

1. A method for preparing cloud hemp yarn for breathable fabrics, characterized in that, The filament bundle passes sequentially through the first oiling device, the pre-networker, the first guide roller, the first hot roller, the second hot roller, the third hot roller, the fourth hot roller, the second oiling device, the second guide roller, the main networker, the third guide roller, and the winding device. The surface roughness of the first guide roller is uniform, ranging from 1.3 to 1.5 μm. The circumferential surface of the first hot roller is divided into two parts symmetrically distributed along the central axis of the first hot roller. The roughness of one part is 0.1-0.15μm, and the roughness of the other part is 1.3-1.5μm. The circumferential surface of the second hot roller is divided into two parts symmetrically distributed along the central axis of the second hot roller. The roughness of one part is 0.1-0.15μm, and the roughness of the other part is 1.3-1.5μm. The surface roughness of the third hot roller is uniform, ranging from 0.30 to 0.35 μm. The surface roughness of the fourth hot roller is uniform, ranging from 0.30 to 0.35 μm. The number of turns of the filament bundle wound on the first to fourth hot rollers is 0.5 turns each; The pre-networker is a vertical plate with a uniform cross-section and horizontally arranged airflow nozzles. A certain cross-section of the pre-networker passes through the airflow nozzles. The cross-section is an Archimedean spiral with a polar angle of ≥360° and ≤450°. The airflow nozzles are located at a position with a polar angle of 180° on the Archimedean spiral and face the center of the Archimedean spiral. The air pressure of the pre-networker is 0.38-0.45 MPa.

2. The method for preparing breathable fabric hemp fiber according to claim 1, characterized in that, The initial oiling device is an oil nozzle; The guide hooks at the inlet and outlet of the pre-networker are grooved guide hooks. The grooved guide hook consists of a U-shaped guide hook and a limiting block. The U-shaped guide hook is arranged horizontally, and the limiting block is connected to the inner wall of the U-shaped guide hook to limit the wire bundle in the bottom area of ​​the U-shaped guide hook. The wire bundle passes from top to bottom through the bottom area of ​​the upper grooved guide hook, the center of the pre-networker, and the bottom area of ​​the lower grooved guide hook.

3. The method for preparing breathable fabric hemp fiber according to claim 2, characterized in that, The Archimedean spiral has an Archimedean spiral coefficient of 1-2 mm / ° and a polar diameter of 1.5-2 mm when the polar angle is 0°. The airflow nozzle is a circular orifice with a diameter of 1.1-1.3 mm. In the vertical direction, the airflow nozzle is located in the middle of the pre-network. In the vertical direction, the length of the pre-network is 23-27 mm.

4. The method for preparing cloud hemp yarn for breathable fabric according to claim 2, characterized in that, Along the vertical direction, the distance between each grooved guide hook and the pre-networker is 13-17mm; the angle α between the wire bundle at the upper grooved guide hook and the vertical direction is 5-10°; the angle β between the wire bundle at the lower grooved guide hook and the vertical direction is 5-10°.

5. The method for preparing breathable fabric hemp fiber according to claim 2, characterized in that, Each pre-spinning unit's airflow nozzle is connected to a branch pipe, and all branch pipes are connected to the same main pipe, which has an automatic pressure regulating valve at its air inlet.

6. The method for preparing cloud hemp yarn for breathable fabric according to claim 1, characterized in that, The linear speed of the first guide roller is 1580-1600 m / min, the temperature of the first hot roller is 50-60℃, and the linear speed of the first hot roller is 1590-1610 m / min. The temperature of the second hot roller is 50-60℃, and the linear speed of the second hot roller is 1690-1710 m / min. The temperature of the third hot roller is 100-110℃, and the linear speed of the third hot roller is 3100-3200 m / min. The temperature of the fourth hot roller is 100-110℃, and the linear speed of the fourth hot roller is 3100-3200 m / min. The linear speed of the second guide roller is 3110-3210 m / min, and the linear speed of the third guide roller is 3125-3225 m / min. The winding speed of the winding device is 3175-3275 m / min.

7. The method for preparing cloud hemp yarn for breathable fabric according to claim 1, characterized in that, The air pressure of the main network device is 0.38-0.42MPa; the first oiling device uses crude oil for oiling, with an oiling rate of 0.4-0.5%; the second oiling device uses an oil agent with a concentration of 19.5-20.5wt% for oiling, with an oiling rate of 0.5-0.6%.

8. The method for preparing breathable fabric hemp fiber according to claim 1, characterized in that, The tow contains 0.21-0.24 wt% matting agent, and the tow specifications are 50-61 dtex / 24f.

9. A method for preparing cloud hemp yarn for breathable fabrics according to any one of claims 2 to 8, characterized in that, The breathable fabric made of cloud hemp silk has a yarn unevenness CV value of 13.5-15.6%, a slub density of 26-30 nodes / meter, a breaking elongation of 84.8-85.7%, a breaking strength of 3.45-3.61 cN / dtex, a boiling water shrinkage rate of 34.1-36.5%, a maximum slub length of 0.43-0.71 cm before the boiling water shrinkage test, a maximum slub length of 0.28-0.46 cm after the boiling water shrinkage test, a fiber degradation rate of ≤0.05%, a breakage count of ≤5.3 times / 18 positions·24 hours, and a network density deviation of ≤3 nodes / meter.

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