Preparation method of polyamide high-strength short fiber

Abstract

The invention relates to a preparation method of polyamide high-strength short fibers. The production line is characterized in that raw filaments are hung on a filament frame of a filament bundling system and sequentially pass through a tension bar, a channel, an oiling wheel, a filament guide wheel, a traction roller, a feeding wheel, a filament containing barrel, a bundling frame, a filament guide machine, an oil immersion tank, a first drawing machine, a second drawing machine, a first steam heating box, a third drawing machine, a fourth drawing machine, a filament folding machine, a second steam heating box, a crimping machine and a conveyor; a slack heat setting box, a cut-off machine, a pneumatic conveying system and a packaging machine; wherein the protofilament is a polyamide high-strength FDY (Fully Drawn Yarn) filament, and the breaking strength is 6.5-8cN / dtex. The strength of the polyamide high-strength short fiber prepared by the preparation method is larger than or equal to 6.5 cN / dtex and is far higher than the industrial standard level, the breaking strength CV is smaller than or equal to 10%, and the elongation at break CV is smaller than or equal to 20%.

Description

TECHNICAL FIELD The present application relates to the field of chemical fiber production, in particular to a preparation method of polyamide high-strength short fibers. BACKGROUND Due to the high intensity of sports, outdoor activities, professional training and other fields, the wear rate of clothing fabric is fast, which easily leads to the breakage of fibers in the fabric, causing the damage of clothing and the loss of its protective performance. Therefore, there is a great demand for good wear resistance of fabric. Polyamide short fibers have good wear resistance and hand feeling, and are easy to be blended with natural fibers such as cotton to realize the complementary advantages of wear resistance and wearing comfort, which matches the use demand in this field.

[0001] In recent years, the performance requirements of clothing in these application fields are increasing, and higher wear resistance of fabric is needed, which requires polyamide short fibers to have higher strength. In some professional outdoor sports and training fields, the customers require the strength of polyamide short fibers to be more than 6.5 cN / dtex, which is much higher than the strength range of 3.7-4.5 cN / dtex of conventional products. The breaking strength of polyamide short fibers is generally 3.7-5 cN / dtex, and the conventional preparation process is difficult to achieve a breaking strength of more than 6.5 cN / dtex, especially when the fiber fineness is fine, it is more difficult to improve the strength. In order to improve the performance, multiple short fiber drawing rollers and tight heat setting equipment are equipped to improve the breaking strength of polyamide short fibers, but this causes poor drawing uniformity and uneven fiber quality.

[0002] In addition, the demand for lightweight upgrading is increasing. For example, composite materials in the fields of automobiles, aerospace, wind power blades and other fields need higher strength short fibers for reinforcement to achieve weight reduction. A 10% increase in strength can reduce weight by 5%-8%. Lightweight high-strength short fiber reinforced composite materials can reduce blade load and prolong service life. SUMMARY In view of the above needs of the prior art, the purpose of the present application is to provide a preparation method of polyamide high-strength short fibers, which can produce polyamide short fiber products with a fiber strength of ≥6.5 cN / dtex.

[0003] The preparation method of polyamide high-strength short fibers of the present application is characterized by: The original silk is hung on the silk holder of the long silk collection system and sequentially passes through the tension rod, the duct, the oiling wheel, the guide wheel, the traction roller, the feeding wheel, the silk bucket, the collection holder, the guide machine, the oil immersion tank, the first drawing machine, the second drawing machine, the first steam heating box, the third drawing machine, the fourth drawing machine, the silk stacking machine, the second steam heating box, the crimping machine, the conveyor, the relaxation heat setting box, the cutting machine, the air conveying system and the packing machine. The original silk is polyamide high-strength FDY long silk with a breaking strength of 6.5-8 cN / dtex.

[0004] Further, the above-mentioned filament collection system is arranged transversely, and the raw filaments are integrated into several bundles after being pulled out of the frame, and the tension rod is used to apply tension to avoid fiber breakage and hair caused by jumping during the collection process. The bundle is pulled into the oiling wheel through the channel.

[0005] Further, the above-mentioned oiling wheel is supplied with industrial water for the bundle, which only needs to have a wetting effect on the bundle, and does not use short fiber oil.

[0006] Further, the above-mentioned oiling tank continuously supplements industrial water to clean the oil in the bundle, and the bundle is sequentially input into the first and second drafters after being output from the oiling tank, and the draft ratio is set to 1.01-1.05.

[0007] Further, the temperature of the above-mentioned first steam heating box is set to 90-120℃, and the bundle is input into the third and fourth drafters after being output from the first steam heating box, and the overfeed rate is set to 1.5-3.0%.

[0008] Further, the crimping speed in the above-mentioned crimping machine is set to 65-105m / min, the total pressure is 0.50-0.65MPa, the main pressure is set to 3.2-3.5bar, and the pressure ratio is set to 2-2.1bar.

[0009] Further, the bundle after crimping is sent into the relaxation heat setting box through the conveyor, the residence time is set to 15min, the relaxation heat setting box has five temperature zones, the first zone temperature is 85-95℃, the second zone temperature is 100-110℃, the third zone temperature is 120-130℃, the fourth zone temperature is 130-150℃, and the fifth zone temperature is 80-95℃. The crimped bundle is heated to release stress and maintain crimping.

[0010] The polyamide semi-dull high-strength short fiber with a linear density of 1.63dtex and a nominal length of 38mm is prepared according to the process: the raw filament is polyamide FDY semi-dull 222dtex / 136f, the breaking strength is 6.81cN / dtex, and the breaking elongation is 24.79%; the godet is 600m / min, and the pulling roller is 600m / min; the first drafter is 86.8m / min, the second drafter is 91.0m / min, and the draft ratio is 1.05; the first steam heating box temperature is 100℃, the third drafter is 100.8m / min, the fourth drafter is 99.0m / min, and the overfeed rate is 1.8%; the crimping speed of the crimping machine is 101.3m / min, the total pressure is 0.55MPa, the main pressure is 3.5bar, and the pressure ratio is 2bar; the relaxation heat setting box has a first zone temperature of 85℃, a second zone temperature of 110℃, a third zone temperature of 125℃, a fourth zone temperature of 138℃, and a fifth zone temperature of 95℃.

[0011] The polyamide bright high-strength short fiber with linear density 1.98 dtex and nominal length 38 mm is prepared by the following process: the original yarn is polyamide FDY bright 230 dtex / 120 f, the breaking strength is 7.51 cN / dtex, the elongation at break is 22.50%, the godet wheel is 600 m / min, the traction roller is 600 m / min, the first drafting machine is 62.9 m / min, the second drafting machine is 63.9 m / min, the draft ratio is 1.015; the first steam heating box temperature is 120 DEG C, the third drafting machine is 65.7 m / min, the fourth drafting machine is 64.2 m / min, the overfeed rate is 2.3%; the crimping machine crimping speed is 68.9 m / min, the total pressure is 0.61 MPa, the main pressure is 3.2 bar, and the multiple pressure is 2.1 bar; the relaxation heat setting box zone one temperature is 95 DEG C, zone two temperature is 105 DEG C, zone three temperature is 120 DEG C, zone four temperature is 148 DEG C, and zone five temperature is 80 DEG C.

[0012] Advantages of the present application: 1. The prepared polyamide high-strength short fiber has a strength of greater than or equal to 6.5 cN / dtex, which is much higher than the industry standard level (FZT52057-2021, FZT52002-2021), and the final short fiber has uniform quality, with a breaking strength CV of less than or equal to 10% and an elongation at break CV of less than or equal to 20%; 2. Without increasing multiple pairs of drafting rollers, special equipment such as tension heat setting, etc., the main body can use conventional polyamide short fiber production equipment to prepare polyamide high-strength short fiber products, saving equipment investment cost; 3. The total denier of the filament bundle can be flexibly adjusted to adapt to different yield requirements, short fiber specification requirements, and short fiber post-processing equipment of different capacity. BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a front spinning process flow chart of the present application; Figure 2 is a back spinning process flow chart of the present application; Figure 3 is a schematic diagram of a filament bundle system. DETAILED DESCRIPTION It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict, and the present application will be described in detail below with reference to the drawings and in combination with the embodiments; it should be pointed out that the following detailed description is exemplary and is intended to provide further description of the present application; unless otherwise specified, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art to which the present application belongs.

[0013] The preparation method of the polyamide high-strength short fiber comprises the following steps: the original yarn is hung on the yarn frame of the long yarn collection system and sequentially passes through the tension rod, the duct, the oiling wheel, the guide wheel, the traction roller, the feeding wheel, the yarn barrel, the collection frame, the guide machine, the oil immersion tank, the first drafting machine, the second drafting machine, the first steam heating box, the third drafting machine, the fourth drafting machine, the yarn stacking machine, the second steam heating box, the crimping machine, the conveyor, the relaxation heat setting box, the cutting machine, the air conveying system and the packing machine; wherein the original yarn is the polyamide high-strength FDY long yarn, and the breaking strength is 6.5-8 cN / dtex.

[0014] The yarn frame of the long yarn collection system is arranged in the transverse direction, the original yarn is integrated into several bundles after being pulled out of the yarn frame, the tension rod is used to apply tension to avoid the fiber breakage and the lint caused by the jumping of the yarn bundle during the collection traction, and the yarn bundle is pulled into the oiling wheel through the duct.

[0015] The industrial water is supplied to the yarn bundle in the oiling wheel, only the wetting and holding effects are needed, and the short yarn oil agent is not used; the industrial water is continuously supplied to the oil immersion tank to clean the oil agent in the yarn bundle, and the yarn bundle is sequentially pulled into the first drafting machine and the second drafting machine after being output from the oil immersion tank, and the drafting multiple is set to be 1.01-1.05.

[0016] The temperature of the first steam heating box is set to be 90-120 DEG C, the yarn bundle is sequentially pulled into the third drafting machine and the fourth drafting machine after being output from the first steam heating box, the overfeed rate is set to be 1.5-3.0%, the crimping speed of the crimping machine is set to be 65-105 m / min, the total pressure is set to be 0.50-0.65 MPa, the main pressure is set to be 3.2-3.5 bar, and the multiple pressure is set to be 2-2.1 bar.

[0017] The yarn bundle after crimping is sent into the relaxation heat setting box through the conveyor, the residence time is set to be 15 min, the relaxation heat setting box has five temperature zones, the temperature of the first zone is 85-95 DEG C, the temperature of the second zone is 100-110 DEG C, the temperature of the third zone is 120-130 DEG C, the temperature of the fourth zone is 130-150 DEG C, and the temperature of the fifth zone is 80-95 DEG C, the crimped yarn bundle is heated to release the stress and keep the crimping.

[0018] The polyamide high-strength short fiber is prepared by using the above process steps. Example 1, process setting: original yarn is polyamide FDY semi-dull 222 dtex / 136 f, breaking strength 6.81 cN / dtex, elongation at break 24.79%, oiling wheel 40 Hz, godet 600 m / min, traction roller 600 m / min; first drafting machine 86.8 m / min, second drafting machine 91.0 m / min, draft ratio 1.05; large steam heating box temperature 100℃, third drafting machine 100.8 m / min, fourth drafting machine 99.0 m / min, overfeed ratio 1.8%; crimping machine crimping speed 101.3 m / min, total pressure 0.55 MPa, main pressure 3.5 bar, pressure ratio 2 bar; relaxation heat setting box zone 1 temperature 85℃, zone 2 temperature 110℃, zone 3 temperature 125℃, zone 4 temperature 138℃, zone 5 temperature 95℃.

[0019] The polyamide semi-dull high-strength short fiber prepared by the above process steps has the following physical indexes: linear density 1.63 dtex, nominal length 38 mm, breaking strength 6.68 cN / dtex, breaking strength CV 9.7%, elongation at break 47.5%, elongation at break CV 18.6%, crimp number 13.4 per 25 mm (detection standard refers to GB / T 14335-2008, GB / T 14337-2022, GB / T14338-2008).

[0020] Example 2, process setting: original yarn is polyamide FDY bright 230 dtex / 120 f, breaking strength 7.51 cN / dtex, elongation at break 22.50%, oiling wheel 40 Hz, godet 600 m / min, traction roller 600 m / min, first drafting machine 62.9 m / min, second drafting machine 63.9 m / min, draft ratio 1.015; large steam heating box temperature 120℃, third drafting machine 65.7 m / min, fourth drafting machine 64.2 m / min, overfeed ratio 2.3%; crimping machine crimping speed 68.9 m / min, total pressure 0.61 MPa, main pressure 3.2 bar, pressure ratio 2.1 bar, relaxation heat setting box zone 1 temperature 95℃, zone 2 temperature 105℃, zone 3 temperature 120℃, zone 4 temperature 148℃, zone 5 temperature 80℃.

[0021] The polyamide bright high-strength short fiber prepared by the above process steps has the following physical indexes: linear density 1.98 dtex, nominal length 38 mm, breaking strength 7.29 cN / dtex, breaking strength CV 8.7%, elongation at break 42.9%, elongation at break CV 12.5%, crimp number 12.2 per 25 mm (detection standard refers to GB / T 14335-2008, GB / T 14337-2022, GB / T14338-2008).

[0022] The present application has the advantages of: 1. The prepared polyamide high-strength short fiber has a strength of greater than or equal to 6.5 cN / dtex, which is much higher than the industry standard level (FZT52057-2021, FZT52002-2021), and the final short fiber has uniform quality, with a breaking strength CV of less than or equal to 10% and a breaking elongation CV of less than or equal to 20%; 2. Without the need to increase multiple pairs of drafting rollers, special equipment such as tension heat setting, etc., the main body can use conventional polyamide short fiber production equipment to prepare polyamide high-strength short fiber products, saving equipment investment costs; 3. The total denier of the filament bundle can be flexibly adjusted to adapt to different yield requirements, short fiber specification requirements, and short fiber post-processing equipment of different capacities.

[0023] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing high-strength polyamide short fibers, characterized in that: The raw yarn is hung on the yarn frame of the filament bundling system and passes through the tension bar, tunnel, upper oil roller, guide roller, traction roller, feed roller, yarn holding drum, bundling frame, yarn guide machine, oil soaking tank, first drawing machine, second drawing machine, first steam heating box, third drawing machine, fourth drawing machine, yarn stacking machine, second steam heating box, crimping machine, conveyor, relaxation heat setting box, cutting machine, pneumatic conveying system and packaging machine in sequence; the raw yarn is polyamide high-strength FDY filament with a breaking strength of 6.5-8 cN / dtex.

2. The method for preparing high-strength polyamide short fibers according to claim 1, characterized in that: The filament bundling system has a horizontally arranged wire frame. After the raw filaments are drawn out on the wire frame, they are bundled into several bundles. Tension is applied by a tension bar to prevent the filament bundles from jumping and breaking or becoming fuzzy during the bundling and traction process. The filament bundles are then pulled through a channel into the upper oil tanker.

3. The method for preparing high-strength polyamide short fibers according to claim 2, characterized in that: The oiler supplies industrial water to the filament bundle, which only needs to wet and bind the filament bundle, and does not use short fiber oiling agents.

4. The method for preparing high-strength polyamide short fibers according to claim 3, characterized in that: The oil immersion tank is continuously replenished with industrial water to clean the oil in the filament bundle. After being output from the oil immersion tank, the filament bundle enters the first drawing machine and the second drawing machine in sequence, with the drawing ratio set to 1.01-1.

05.

5. The method for preparing high-strength polyamide short fibers according to claim 4, characterized in that: The temperature of the first steam heating box is set to 90-120℃. After the yarn is output from the first steam heating box, it enters the third and fourth drawing machines, with an overfeed rate of 1.5-3.0%.

6. The method for preparing high-strength polyamide short fibers according to claim 5, characterized in that: The curling machine has a curling speed set to 65-105 m / min, a total pressure of 0.50-0.65 MPa, a main pressure set to 3.2-3.5 bar, and a multiplier pressure set to 2-2.1 bar.

7. The method for preparing high-strength polyamide short fibers according to claim 6, characterized in that: After being curled, the bundle of filaments is conveyed into a relaxation heat setting chamber with a set dwell time of 15 minutes. The relaxation heat setting chamber has five temperature zones: zone 1 (85-95℃), zone 2 (100-110℃), zone 3 (120-130℃), zone 4 (130-150℃), and zone 5 (80-95℃). The heat is used to release the stress of the curled filaments and maintain their curled shape.

8. The method for preparing high-strength polyamide short fibers according to claim 7, characterized in that: High-strength semi-dull polyamide staple fibers with a linear density of 1.63 dtex and a nominal length of 38 mm were produced. The process settings were as follows: the precursor yarn was semi-dull polyamide FDY 222 dtex / 136f, with a breaking strength of 6.81 cN / dtex and a breaking elongation of 24.79%; the guide roller speed was 600 m / min, the traction roller speed was 600 m / min; the first drafting machine speed was 86.8 m / min, the second drafting machine speed was 91.0 m / min, and the drafting ratio was 1.05; the temperature of the first steam heating box was 100℃, the speed of the third drafting machine was 100.8 m / min, the speed of the fourth drafting machine was 99.0 m / min, and the overfeed rate was 1.8%; the crimping machine speed was 101.3 m / min, the total pressure was 0.55 MPa, the main pressure was 3.5 bar, and the double pressure was 2 bar; the relaxation heat setting box temperatures were 85℃ in zone 1, 110℃ in zone 2, 125℃ in zone 3, 138℃ in zone 4, and 95℃ in zone 5.

9. The method for preparing high-strength polyamide short fibers according to claim 7, characterized in that: High-strength polyamide staple fiber with a linear density of 1.98 dtex and a nominal length of 38 mm was produced. The process settings were as follows: the precursor yarn was polyamide FDY bright 230 dtex / 120f, with a breaking strength of 7.51 cN / dtex and a breaking elongation of 22.50%. The guide roller speed was 600 m / min, the traction roller speed was 600 m / min, the first drafting machine speed was 62.9 m / min, the second drafting machine speed was 63.9 m / min, and the drafting ratio was 1.

015. The temperature of the first steam heating chamber was 120℃, the speed of the third drafting machine was 65.7 m / min, the speed of the fourth drafting machine was 64.2 m / min, and the overfeed rate was 2.3%. The crimping machine speed was 68.9 m / min, the total pressure was 0.61 MPa, the main pressure was 3.2 bar, and the double pressure was 2.1 bar. The relaxation heat setting chamber temperatures were 95℃ in zone 1, 105℃ in zone 2, 120℃ in zone 3, 148℃ in zone 4, and 80℃ in zone 5.

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