Production method of high-strength low-shrinkage polyamide 66 industrial fine denier 12-head spun yarn

Abstract

The present application relates to a kind of high-strength low-shrinkage nylon 66 industrial fine denier 12 head spinning production method, first POE and PA66 are used as main raw material to obtain POE master batch, POE master batch is uniformly mixed with PA66, then melt spinning is carried out, and high-strength low-shrinkage nylon 66 industrial fine denier is prepared;The polymerization degree of POE is 6-10;The content of POE in high-strength low-shrinkage nylon 66 industrial fine denier is 1-4.5wt%;Melt spinning is carried out in the spinning assembly containing 12 spinnerets, and the spinning temperature is 260-300 DEG C.The breaking strength of the high-strength low-shrinkage nylon 66 industrial fine denier of the present application is higher, and the dry heat shrinkage rate is lower, while the high performance of product is considered, the production energy consumption is reduced by 12 head spinning process, and production efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of melt spinning and relates to a production method for spinning 12-head high-strength, low-shrinkage nylon 66 industrial fine denier yarn. Background Technology

[0002] Nylon 66 fiber possesses high mechanical strength, excellent moisture absorption and heat resistance, and its abrasion resistance surpasses that of all other fibers (10 times that of cotton and 20 times that of wool). Industrial-grade synthetic fibers with a fineness below 500D are generally referred to as industrial fine denier yarns. For industrial fine denier yarns, breaking strength is a crucial indicator. Common nylon 66 industrial fine denier yarns have a breaking strength of 6.8-7.5 cN / dtex. Improving its breaking strength can broaden its application range. To achieve high strength, the drawing temperature during the drawing process of industrial fine denier yarns is relatively high to ensure sufficient orientation of the molecular chains. Considering the molecular structure characteristics of PA66, its long and highly oriented carbon chains result in high drawing stress within the molecular chains, leading to a high dry heat shrinkage rate in PA66 fiber. For example, CN201711428528.9 discloses a method for preparing nylon 66 industrial yarns; although the breaking strength can reach 8.0 cN / dtex, the dry heat shrinkage rate is relatively high, ranging from 4% to 7%.

[0003] There is a large demand for nylon 66 both domestically and internationally, but the production capacity of commonly used nylon 66 industrial fine denier yarns (6-head and 8-head spinning) in China is limited. Therefore, it is crucial to increase production capacity and reduce energy consumption to save on the production cost of nylon 66. Summary of the Invention

[0004] The purpose of this invention is to solve the problems existing in the prior art and provide a production method for spinning high-strength, low-shrinkage nylon 66 industrial fine denier yarn in 12-head spinning.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A production method for high-strength, low-shrinkage nylon 66 industrial fine denier yarn with 12 heads involves first preparing POE masterbatch using POE and PA66 as the main raw materials, then mixing the POE masterbatch and PA66 evenly and performing melt spinning to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0007] The degree of polymerization of POE is 6-10;

[0008] The POE content in high-strength, low-shrinkage nylon 66 industrial fine denier yarn is 1-4.5 wt%.

[0009] The spinning assembly used in melt spinning contains 12 spinnerets, and the spinning temperature is 260-300℃.

[0010] One objective of this invention is to reduce the dry heat shrinkage rate of PA66 fiber. Specifically, this invention achieves this by introducing POE (ethylene-octene copolymer) with a specific degree of polymerization and content into PA66 fiber and controlling the spinning temperature within a specific range. On the one hand, without the introduction of POE, the number of network nodes formed by the orientation of PA66 molecular chains during the drawing process is relatively small, resulting in a higher dry heat shrinkage rate of PA66 fiber. After the introduction of POE, at a specific spinning temperature, POE can undergo a cross-linking reaction to form a three-dimensional network structure, which then entangles with the PA66 molecular chains, restricting the movement of the PA66 molecular chains and thus forming certain network nodes, thereby ensuring that PA66 fiber has a lower dry heat shrinkage rate. On the other hand, the dry heat shrinkage rate of PA66 fiber is also related to its crystallization behavior. PA66 has a certain degree of crystallinity, and when subjected to high temperatures, the fiber crystallizes, leading to dimensional shrinkage. The addition of POE changes the molecular chain structure of PA66 and introduces a non-crystalline elastomer. This non-crystalline elastomer can inhibit the crystallization behavior of PA66 at high temperatures and can also reduce the dry heat shrinkage rate of the fiber to a certain extent.

[0011] The second objective of this invention is to improve the tensile strength of PA66 fibers. Specifically, this invention achieves this by introducing POE with a specific degree of polymerization and a specific content into PA66 fibers. On the one hand, POE, as an elastomer, has a high energy absorption capacity. When PA66 fibers are subjected to external forces, POE can absorb and disperse some of the stress, thereby slowing down the crack propagation rate, and energy absorption can delay the fiber breaking process. On the other hand, as an additive, the presence of POE in the fiber has a certain degree of filling effect. The filling effect can reduce the voids inside the fiber and increase the density of the fiber, thereby improving the tensile strength of PA66 fibers.

[0012] The content of POE in PA66 should not be too high or too low. If the content is too low, it cannot effectively absorb the tensile stress between PA66 molecular chains, nor can it form enough network nodes, thus failing to achieve the purpose of improving fiber breaking strength and reducing dry heat shrinkage. If the content is too high, it will destroy the regularity of PA66 molecular chains, which is not conducive to the orientation of molecular chains during the drawing process. At the same time, it will form a large number of three-dimensional network nodes, resulting in increased rigidity and reduced processability of PA66. Therefore, the amount of POE added needs to be moderate.

[0013] The degree of polymerization of POE should not be too high or too low. If the polymerization is too low, the POE chain segment length will be too small, making it difficult to entangle with the PA66 molecular chain. As a result, the number of network nodes between the molecular chains cannot be guaranteed, which is not conducive to reducing the dry heat shrinkage rate of PA66 fiber. At the same time, if the polymerization is too low, it will also greatly increase the flowability of PA66 and reduce its processability. If the polymerization is too high, it will significantly reduce the flowability of PA66, which will also reduce its processability.

[0014] Meanwhile, existing technologies suffer from low production efficiency and high energy consumption in the production of fine denier nylon 66 industrial yarn. This invention improves the fluidity of PA66 melt by introducing an appropriate degree of polymerization POE, while also meeting the melt strength requirements of melt spinning, thus improving the melt conveying efficiency. The melt spinning process can be changed from the original 8-head spinning to 12-head spinning, thereby increasing production efficiency.

[0015] As a preferred technical solution:

[0016] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning as described above, wherein the POE content in the POE masterbatch is 10-20 wt%.

[0017] In the production method of 12-head spinning of high-strength, low-shrinkage nylon 66 industrial fine denier yarn as described above, when POE masterbatch and PA66 are mixed evenly, the mass ratio of POE masterbatch to PA66 is 1:8-10.

[0018] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning as described above involves the following process for preparing POE masterbatch: POE and PA66 chips are melt-blended, extruded and pelletized, and dried sequentially to obtain POE masterbatch.

[0019] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning as described above involves a melt blending temperature of 240-260℃. Compared to the PA66 matrix molecule, POE has a low degree of polymerization, which can reduce the viscosity of PA66 to a certain extent during processing. Therefore, granulation can be carried out at a relatively low temperature (240-260℃).

[0020] The production method of 12-head spinning of high-strength, low-shrinkage nylon 66 industrial fine denier yarn as described above, the melt spinning process is as follows: melt extrusion by single screw extruder → metering pump metering and conveying → spinning and forming by 12-head spinning assembly → side blowing drying → oiling device oiling → drawing and forming → main networker (dual-nozzle main network nozzle, the airflow direction of the two nozzles is at a 90° angle, which can form a high degree of network on the yarn bundle) → winding.

[0021] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning described above uses a single-screw extruder with a length-to-diameter ratio of 25-34:1, a screw diameter of 90-105mm, and a die pressure of 5-15MPa. The screw diameter of the single-screw extruder used in this invention (90-105mm) is greater than that of the single-screw extruder used in 6-head spinning (65mm) and also greater than that of the single-screw extruder used in 8-head spinning (80mm). This greatly improves the efficiency of melt conveying, and thus the production capacity will also increase accordingly. The production capacity will increase from 600kg / day / position for 6-head spinning and 800kg / day / position for 8-head spinning to 1200kg / day / position for 12-head spinning. This significantly increases production efficiency without affecting product quality, thereby increasing enterprise benefits.

[0022] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning described above has a number of spinneret holes of 8-48 in a single spinneret.

[0023] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning as described above uses four pairs of drafting rollers for drafting.

[0024] The temperature of the first pair of drafting rollers (i.e. the drafting rollers that come into contact with the yarn bundle first during its travel) is 80-120℃, the temperature of the second pair of drafting rollers is 130-150℃, the temperature of the third pair of drafting rollers is 180-200℃, and the temperature of the fourth pair of drafting rollers is 200-240℃.

[0025] The spinning speed of the first pair of drafting rollers is 400-500 m / min; the spinning speed of the second pair of drafting rollers is 1200-1500 m / min; the spinning speed of the third pair of drafting rollers is 2200-2500 m / min; and the spinning speed of the fourth pair of drafting rollers is 2500-280 m / min.

[0026] The present invention employs four pairs of drawing rollers during the drawing process to ensure the stability of the filament bundle on the roller surface. The stability of the filament bundle can be adjusted by regulating the surface roughness of the drawing rollers. When the temperature is too high, the filament bundle jumps violently on the drawing rollers, while when the temperature is too low, fuzz is easily generated. Therefore, the stability of the filament bundle is improved by regulating the temperature of the drawing rollers. Compared with the traditional six pairs of drawing rollers, the number of drawing rollers is reduced by four pairs, thereby reducing energy consumption by 33%, reducing enterprise production costs, and further increasing enterprise benefits.

[0027] The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning described above, wherein the fineness of the multifilament corresponding to each spinneret is 40-300D, the breaking strength is greater than 7.8cN / dtex, and the dry heat shrinkage rate is less than 2%.

[0028] Beneficial effects:

[0029] The method of the present invention has high production efficiency, low energy consumption, and produces nylon 66 industrial fine denier yarn with high breaking strength and low dry heat shrinkage. Detailed Implementation

[0030] 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.

[0031] The following are the performance testing methods described in the examples:

[0032] Fineness: determined according to GB / T 14343.

[0033] Fracture strength: determined according to GB / T 14344.

[0034] Dry heat shrinkage rate: determined according to GB / T 6505.

[0035] Example 1

[0036] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-end spinning, comprising the following steps:

[0037] (1) Preparation of raw materials:

[0038] POE: Degree of polymerization is 6-10;

[0039] PA66 chips: intrinsic viscosity is 2.6 dL / g;

[0040] (2) Preparation of POE masterbatch;

[0041] POE and PA66 chips were sequentially melt-blended, extruded, pelletized, and dried to obtain POE masterbatch; wherein the melt-blending temperature was 240℃.

[0042] The POE content in the obtained POE masterbatch is 20 wt%.

[0043] (3) Preparation of high-strength, low-shrinkage nylon 66 industrial fine denier yarn;

[0044] POE masterbatch and PA66 chips were mixed evenly at a mass ratio of 1:10 and then melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0045] The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

[0046] The single-screw extruder has a length-to-diameter ratio of 25:1, a screw diameter of 90 mm, a die head pressure of 5 MPa, and temperatures of 260℃ in zone 1, 270℃ in zone 2, 285℃ in zone 3, 295℃ in zone 4, 295℃ in zone 5, and 300℃ in zone 6. The melt spinning assembly contains 12 spinnerets, with 48 spinneret holes in each spinneret.

[0047] The drafting process uses four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 80℃ and the spinning speed is 500m / min. The temperature of the second pair of drafting rollers is 130℃ and the spinning speed is 1200m / min. The temperature of the third pair of drafting rollers is 180℃ and the spinning speed is 2200m / min. The temperature of the fourth pair of drafting rollers is 200℃ and the spinning speed is 2500m / min.

[0048] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 100D, a breaking strength of 7.84cN / dtex, and a dry heat shrinkage rate of 1.82%.

[0049] Comparative Example 1

[0050] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filaments in 12-head spinning is basically the same as in Example 1, except that the degree of polymerization of POE is 3-5.

[0051] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 100D, a breaking strength of 7.6cN / dtex, and a dry heat shrinkage rate of 3.8%.

[0052] Comparing Example 1 and Comparative Example 1, it can be seen that when Comparative Example 1 was preparing high-strength, low-shrinkage nylon 66 industrial fine denier yarn, the degree of polymerization of POE was low (the molecular weight was too low), which would weaken the cross-linking effect of POE in the fiber and weaken the binding effect on the PA66 molecular chain. This would result in fewer network nodes formed between POE and PA66 molecules, leading to a higher dry heat shrinkage rate of PA66 fiber.

[0053] Comparative Example 2

[0054] A production method for high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning is basically the same as in Example 1, except that the POE content in the POE masterbatch is 8.8 wt%.

[0055] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 100D, a breaking strength of 7.4cN / dtex, and a dry heat shrinkage rate of 4.2%.

[0056] Comparing Example 1 and Comparative Example 2, it can be seen that the POE content in the high-strength, low-shrinkage nylon 66 industrial fine denier yarn prepared in Comparative Example 2 is too low. This results in a weaker stress dispersion effect of POE in the fiber, which cannot effectively absorb and disperse the stress in the fiber, leading to a reduction in its strength. At the same time, the low POE content cannot form a sufficient number of network nodes with PA66 molecules, thus failing to provide a good binding effect on the PA66 molecular chains, resulting in a higher dry heat shrinkage rate of PA66 fiber.

[0057] Comparative Example 3

[0058] A production method for high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning is basically the same as in Example 1, except that the POE content in the POE masterbatch is 55wt%.

[0059] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 100D, a breaking strength of 6.8cN / dtex, and a dry heat shrinkage rate of 1.2%.

[0060] Comparing Example 1 and Comparative Example 3, it can be seen that the high POE content in the high-strength, low-shrinkage nylon 66 industrial fine denier yarn prepared in Comparative Example 3 is too high. This leads to a significant increase in the number of network nodes formed between POE and PA66 molecular chains, which greatly restricts the movement of PA66 molecular chains. It also restricts the absorption and dispersion of forces by POE, which increases the brittleness of the fiber itself. Under the action of external forces, microcracks are very easy to propagate and cause fiber breakage, ultimately leading to a decrease in fiber strength.

[0061] Example 2

[0062] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-end spinning, comprising the following steps:

[0063] (1) Preparation of raw materials:

[0064] POE: Degree of polymerization is 6-10;

[0065] PA66 chips: intrinsic viscosity is 2.8 dL / g;

[0066] (2) Preparation of POE masterbatch;

[0067] POE and PA66 chips were sequentially melt-blended, extruded, pelletized, and dried to obtain POE masterbatch; wherein the melt-blending temperature was 240℃.

[0068] The POE content in the obtained POE masterbatch is 15 wt%.

[0069] (3) Preparation of high-strength, low-shrinkage nylon 66 industrial fine denier yarn;

[0070] After uniformly mixing POE masterbatch and PA66 chips at a mass ratio of 1:8, the mixture is melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0071] The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

[0072] The single-screw extruder has a length-to-diameter ratio of 25:1, a screw diameter of 90 mm, a die head pressure of 8 MPa, and temperatures of 260℃ in zone 1, 270℃ in zone 2, 285℃ in zone 3, 295℃ in zone 4, 295℃ in zone 5, and 300℃ in zone 6. The melt spinning assembly contains 12 spinnerets, with 48 spinneret holes in each spinneret.

[0073] The drafting process uses four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 80℃ and the spinning speed is 500m / min. The temperature of the second pair of drafting rollers is 150℃ and the spinning speed is 1200m / min. The temperature of the third pair of drafting rollers is 180℃ and the spinning speed is 2200m / min. The temperature of the fourth pair of drafting rollers is 220℃ and the spinning speed is 2800m / min.

[0074] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 300D, a breaking strength of 7.88cN / dtex, and a dry heat shrinkage rate of 1.85%.

[0075] Example 3

[0076] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-end spinning, comprising the following steps:

[0077] (1) Preparation of raw materials:

[0078] POE: Degree of polymerization is 6-10;

[0079] PA66 chips: intrinsic viscosity is 2.7 dL / g;

[0080] (2) Preparation of POE masterbatch;

[0081] POE and PA66 chips were sequentially melt-blended, extruded, pelletized, and dried to obtain POE masterbatch; wherein the melt-blending temperature was 250℃.

[0082] The POE content in the obtained POE masterbatch is 10 wt%.

[0083] (3) Preparation of high-strength, low-shrinkage nylon 66 industrial fine denier yarn;

[0084] After uniformly mixing POE masterbatch and PA66 chips at a mass ratio of 1:8, the mixture is melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0085] The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

[0086] The single-screw extruder has a length-to-diameter ratio of 34:1, a screw diameter of 95 mm, a die head pressure of 8 MPa, and temperatures of 260℃ in zone 1, 270℃ in zone 2, 285℃ in zone 3, 295℃ in zone 4, 295℃ in zone 5, and 300℃ in zone 6. The melt spinning assembly contains 12 spinnerets, with 36 spinneret holes in each spinneret.

[0087] The drafting process uses four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 80℃ and the spinning speed is 400m / min. The temperature of the second pair of drafting rollers is 130℃ and the spinning speed is 1200m / min. The temperature of the third pair of drafting rollers is 180℃ and the spinning speed is 2400m / min. The temperature of the fourth pair of drafting rollers is 220℃ and the spinning speed is 2500m / min.

[0088] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 80D, a breaking strength of 7.98cN / dtex, and a dry heat shrinkage rate of 1.88%.

[0089] Example 4

[0090] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-end spinning, comprising the following steps:

[0091] (1) Preparation of raw materials:

[0092] POE: Degree of polymerization is 6-10;

[0093] PA66 chips: intrinsic viscosity is 2.6 dL / g;

[0094] (2) Preparation of POE masterbatch;

[0095] POE and PA66 chips were sequentially melt-blended, extruded, pelletized, and dried to obtain POE masterbatch; wherein the melt-blending temperature was 250℃.

[0096] The POE content in the obtained POE masterbatch is 11 wt%.

[0097] (3) Preparation of high-strength, low-shrinkage nylon 66 industrial fine denier yarn;

[0098] POE masterbatch and PA66 chips were mixed evenly at a mass ratio of 1:10 and then melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0099] The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

[0100] The single-screw extruder has a length-to-diameter ratio of 30:1, a screw diameter of 105 mm, a die head pressure of 10 MPa, and temperatures of 260℃ in zone 1, 270℃ in zone 2, 285℃ in zone 3, 295℃ in zone 4, 295℃ in zone 5, and 300℃ in zone 6. The melt spinning assembly contains 12 spinnerets, with 24 spinneret holes in each spinneret.

[0101] The drafting process uses four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 100℃ and the spinning speed is 500m / min. The temperature of the second pair of drafting rollers is 130℃ and the spinning speed is 1500m / min. The temperature of the third pair of drafting rollers is 190℃ and the spinning speed is 2400m / min. The temperature of the fourth pair of drafting rollers is 220℃ and the spinning speed is 2800m / min.

[0102] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 40D, a breaking strength of 7.92cN / dtex, and a dry heat shrinkage rate of 1.95%.

[0103] Example 5

[0104] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-end spinning, comprising the following steps:

[0105] (1) Preparation of raw materials:

[0106] POE: Degree of polymerization is 6-10;

[0107] PA66 chips: intrinsic viscosity is 2.6 dL / g;

[0108] (2) Preparation of POE masterbatch;

[0109] POE and PA66 chips were sequentially melt-blended, extruded, pelletized, and dried to obtain POE masterbatch; wherein the melt-blending temperature was 260℃.

[0110] The POE content in the obtained POE masterbatch is 10 wt%.

[0111] (3) Preparation of high-strength, low-shrinkage nylon 66 industrial fine denier yarn;

[0112] POE masterbatch with a mass ratio of 1:9 was mixed evenly with PA66 chips and then melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0113] The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

[0114] The single-screw extruder has a length-to-diameter ratio of 25:1, a screw diameter of 105mm, a die head pressure of 12MPa, and temperatures of 260℃ in zone 1, 270℃ in zone 2, 285℃ in zone 3, 295℃ in zone 4, 295℃ in zone 5, and 300℃ in zone 6. The melt spinning assembly contains 12 spinnerets, with 24 spinneret holes in each spinneret.

[0115] The drafting process uses four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 80℃ and the spinning speed is 400m / min. The temperature of the second pair of drafting rollers is 130℃ and the spinning speed is 1300m / min. The temperature of the third pair of drafting rollers is 180℃ and the spinning speed is 2500m / min. The temperature of the fourth pair of drafting rollers is 220℃ and the spinning speed is 2600m / min.

[0116] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 120D, a breaking strength of 7.94cN / dtex, and a dry heat shrinkage rate of 1.91%.

[0117] Example 6

[0118] A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-end spinning, comprising the following steps:

[0119] (1) Preparation of raw materials:

[0120] POE: Degree of polymerization is 6-10;

[0121] PA66 chips: intrinsic viscosity is 2.8 dL / g;

[0122] (2) Preparation of POE masterbatch;

[0123] POE and PA66 chips were sequentially melt-blended, extruded, pelletized, and dried to obtain POE masterbatch; wherein the melt-blending temperature was 260℃.

[0124] The POE content in the obtained POE masterbatch is 20 wt%.

[0125] (3) Preparation of high-strength, low-shrinkage nylon 66 industrial fine denier yarn;

[0126] After uniformly mixing POE masterbatch and PA66 chips at a mass ratio of 1:8, the mixture is melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn.

[0127] The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

[0128] The single-screw extruder has a length-to-diameter ratio of 25:1, a screw diameter of 105mm, a die head pressure of 15MPa, and temperatures of 260℃ in zone 1, 270℃ in zone 2, 285℃ in zone 3, 295℃ in zone 4, 295℃ in zone 5, and 300℃ in zone 6. The melt spinning assembly contains 12 spinnerets, with each spinneret having 8 spinneret holes.

[0129] The drafting process uses four pairs of drafting rollers. The temperature of the first pair of drafting rollers is 120℃ and the spinning speed is 500m / min. The temperature of the second pair of drafting rollers is 150℃ and the spinning speed is 1500m / min. The temperature of the third pair of drafting rollers is 200℃ and the spinning speed is 2500m / min. The temperature of the fourth pair of drafting rollers is 240℃ and the spinning speed is 2800m / min.

[0130] A total of 12 multifilaments were obtained, with one multifilament corresponding to one spinneret. Each multifilament had a fineness of 40D, a breaking strength of 7.82cN / dtex, and a dry heat shrinkage rate of 1.76%.

Claims

1. A method for producing high-strength, low-shrinkage nylon 66 industrial fine denier filament 12-head spinning, characterized in that, First, POE masterbatch is prepared using POE and PA66 as the main raw materials. Then, the POE masterbatch and PA66 are mixed evenly and melt-spun to obtain high-strength, low-shrinkage nylon 66 industrial fine denier yarn. The degree of polymerization of POE is 6-10; The POE content in high-strength, low-shrinkage nylon 66 industrial fine denier yarn is 1-4.5 wt%. The spinning assembly used in melt spinning contains 12 spinnerets, and the spinning temperature is 260-300℃; The fineness of the multifilaments corresponding to each spinneret is 40-300D, the breaking strength is greater than 7.8cN / dtex, and the dry heat shrinkage rate is less than 2%.

2. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 1, characterized in that, The POE content in the POE masterbatch is 10-20 wt%.

3. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 2, characterized in that, When POE masterbatch and PA66 are mixed evenly, the mass ratio of POE masterbatch to PA66 is 1:8-10.

4. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 1, characterized in that, The preparation process of POE masterbatch is as follows: POE and PA66 chips are melt-blended, extruded and pelletized, and dried to obtain POE masterbatch.

5. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 4, characterized in that, The melt blending temperature is 240-260℃.

6. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 1, characterized in that, The melt spinning process is as follows: melt extrusion by a single screw extruder → metering pump metering and conveying → spinning and forming by a 12-head spinning assembly → side blowing drying → oiling by an oiling device → drawing and forming → main networker → winding.

7. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 6, characterized in that, The length-to-diameter ratio of the single-screw extruder is 25-34:1, the screw diameter is 90-105mm, and the die pressure is 5-15MPa.

8. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 6, characterized in that, The number of spinneret holes in a single spinneret is 8-48.

9. The production method of high-strength, low-shrinkage nylon 66 industrial fine denier 12-head spinning according to claim 6, characterized in that, The drawing process uses four pairs of drawing rollers; The temperature of the first pair of drafting rollers is 80-120℃, the temperature of the second pair of drafting rollers is 130-150℃, the temperature of the third pair of drafting rollers is 180-200℃, and the temperature of the fourth pair of drafting rollers is 200-240℃. The spinning speed of the first pair of drafting rollers is 400-500 m / min; the spinning speed of the second pair of drafting rollers is 1200-1500 m / min; the spinning speed of the third pair of drafting rollers is 2200-2500 m / min; and the spinning speed of the fourth pair of drafting rollers is 2500-280 m / min.