A renewable polyamide 56 fiber and its preparation method and application

Abstract

This invention relates to a renewable polyamide 56 fiber, its preparation method, and its application. The raw materials for its production include at least a tackifying renewable polyamide 56 resin. The relative viscosity of the tackifying renewable polyamide 56 resin is 2.4-2.9, and its crystallization temperature is 180-210℃. This invention uses a tackifying renewable polyamide 56 resin obtained by tackifying a recycled polyamide 56 resin produced from recycled polyamide waste fibers and waste fabrics as a raw material. This not only enables the production of fibers with mechanical and dyeing properties comparable to conventional polyamide 56 fibers but also achieves the goal of recycling polyamide waste.

Description

Technical Field

[0001] This invention relates to the field of polyamide materials technology, and in particular to a renewable polyamide 56 fiber, its preparation method, and its application. Background Technology

[0002] Polyamide fiber is one of the earliest synthetic fibers to be industrially produced worldwide, playing a pivotal role in the synthetic fiber industry. There are many types of polyamide fibers, with polyamide 6 and polyamide 66 being the most widely produced and used industrially. Civilian-grade polyamide fibers are mainly used in socks, lace underwear, shapewear, sports underwear, wedding dresses, casual jackets, sportswear, raincoats, windbreakers, quick-drying clothing, winter clothing, outdoor tents, sleeping bags, and backpacks. Industrial-grade polyamide fibers are widely used in applications such as tire cords, drive belts, hoses, ropes, fishing nets, tires, and parachutes. While polyamide products are widely used in daily life, bringing great convenience, they also generate significant amounts of waste and environmental pollution. With increasing environmental awareness, people are paying more and more attention to the recycling of waste polyamide products.

[0003] Currently, the market mainly uses nylon 6 fiber, which is prepared from recycled nylon 6 resin. However, recycled nylon 6 resin has many problems such as many impurities, low viscosity and unevenness, which leads to problems such as many broken fibers, low fiber strength and poor dyeing during the production of recycled nylon 6 fiber. Summary of the Invention

[0004] To overcome at least one of the defects of the prior art, in a first aspect, one embodiment of the present invention provides a renewable polyamide 56 fiber, the raw material of which includes at least a tackifying renewable polyamide 56 resin; the relative viscosity of the tackifying renewable polyamide 56 resin is 2.4-2.9, and the terminal amino content of the tackifying renewable polyamide 56 resin is 32-48 mmol / kg.

[0005] Secondly, one embodiment of the present invention provides a method for preparing the above-mentioned renewable polyamide 56 fiber, the method comprising:

[0006] 1) Heat the tackified renewable polyamide 56 resin to a molten state to form polyamide 56 melt;

[0007] 2) The polyamide 56 melt is fed into the spinning box and ejected through the spinneret of the spinning assembly to form nascent filaments;

[0008] 3) Cool, oil, stretch, heat set and wind the nascent filaments to obtain the renewable polyamide 56 fiber.

[0009] Thirdly, one embodiment of the present invention provides the application of the above-described renewable polyamide 56 fiber or the renewable polyamide 56 fiber prepared by the above-described preparation method in the field of woven and knitted fabrics.

[0010] The beneficial effects of this invention are as follows:

[0011] First, the renewable polyamide 56 resin produced by the present invention through the melting and granulation of recycled polyamide waste filaments and waste fabric has uniform viscosity and low impurities, making it suitable for industrial high-speed fine denier spinning production. Furthermore, it achieves the goal of recycling polyamide waste, turning waste into treasure, thus saving social resources and effectively protecting the environment.

[0012] Secondly, the renewable polyamide 56 fiber provided by this invention has good mechanical properties, low evenness, and good dyeing performance. Moreover, the renewable polyamide 56 fiber provided by this invention is prepared from renewable polyamide 56 resin, which is energy-saving and environmentally friendly, and can achieve low carbon emission reduction. The performance of the prepared fiber can reach the same performance indicators as conventional polyamide 56 fiber.

[0013] Third, the method for preparing renewable polyamide 56 fiber provided by this invention makes the production of renewable polyamide 56 fiber stable, with fewer broken monofilaments during spinning, high fiber production rate, long component replacement cycle, high production efficiency, and low production cost. Detailed Implementation

[0014] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0015] One embodiment of the present invention provides a renewable polyamide 56 fiber, the raw material of which includes at least a tackifying renewable polyamide 56 resin; the relative viscosity of the tackifying renewable polyamide 56 resin is 2.4-2.9, and the terminal amino content of the tackifying renewable polyamide 56 resin is 32-48 mmol / kg.

[0016] In one embodiment, the relative viscosity of the tackifying renewable polyamide 56 resin is 2.5-2.85, further 2.6-2.8, and even further 2.7-2.8, for example 2.55, 2.6, 2.65, 2.68, 2.70, 2.72, 2.75, 2.76, 2.78, 2.8, 2.83, 2.85.

[0017] In one embodiment, the terminal amino content of the tackifying renewable polyamide 56 resin is 34-46 mmol / kg, more specifically 36-44 mmol / kg, for example 35 mmol / kg, 36 mmol / kg, 37 mmol / kg, 38 mmol / kg, 39 mmol / kg, 40 mmol / kg, 41 mmol / kg, 42 mmol / kg, 43 mmol / kg, 44 mmol / kg, 45 mmol / kg, 46 mmol / kg, 47 mmol / kg, or 48 mmol / kg.

[0018] In one embodiment, the crystallization temperature of the tackifying renewable polyamide 56 resin is 180-210°C, further 190-210°C, even further 200-210°C, and still further 206-210°C, for example 190°C, 191°C, 192°C, 193°C, 194°C, 195°C, 196°C, 197°C, 198°C, 199°C, 200°C, 201°C, 202°C, 203°C, 204°C, 205°C, 206°C, 207°C, 208°C, 209°C, and 210°C.

[0019] In one embodiment, the melting point of the tackifying renewable polyamide 56 resin is 250-255°C, further 252-254°C, for example 250°C, 251°C, 252°C, 253°C, 254°C, 255°C.

[0020] In one embodiment, the moisture content of the tackifying renewable polyamide 56 resin is 300-600 ppm, further 300-500 ppm, even further 300-400 ppm, and still even further 300-380 ppm, for example 310 ppm, 320 ppm, 330 ppm, 340 ppm, 350 ppm, 360 ppm, 370 ppm, 380 ppm, 390 ppm, and 400 ppm.

[0021] In one embodiment, the tackifying renewable polyamide 56 resin is obtained by tackifying renewable polyamide 56 resin; wherein, based on the total weight of the renewable polyamide 56 resin, the content of the renewable polyamide 56 resin is ≥99.0 wt%, more preferably ≥99.5 wt%, for example ≥99.8 wt% or ≥99.9 wt%.

[0022] In one embodiment, the relative viscosity of the renewable polyamide 56 resin is 2.0-2.6, further 2.1-2.5, and even further 2.2-2.4, for example 2.1, 2.2, 2.3, 2.4, 2.5, 2.6.

[0023] In one embodiment, the terminal amino content of the renewable polyamide 56 resin is 35-50 mmol / kg, further 38-50 mmol / kg, and even further 42-50 mmol / kg, for example 36 mmol / kg, 37 mmol / kg, 38 mmol / kg, 39 mmol / kg, 40 mmol / kg, 41 mmol / kg, 42 mmol / kg, 43 mmol / kg, 44 mmol / kg, 45 mmol / kg, 46 mmol / kg, 47 mmol / kg, 48 mmol / kg, 49 mmol / kg, and 50 mmol / kg.

[0024] In one embodiment, the regenerated polyamide 56 fiber has a breaking strength of 3.0-5.0 cN / dtex, further 3.3-4.8 cN / dtex, even further 3.5-4.5 cN / dtex, and still further 3.8-4.5 cN / dtex, and still further 4.0-4.5 cN / dtex, for example 3.6 cN / dtex, 3.7 cN / dtex, 3.8 cN / dtex, 3.9 cN / dtex, 4.0 cN / dtex, 4.1 cN / dtex, 4.2 cN / dtex, 4.3 cN / dtex, and 4.4 cN / dtex.

[0025] In one embodiment, the breaking strength (CV%) of the renewable polyamide 56 fiber is ≤5.0%, further ≤4.0%, and even further ≤3.0%.

[0026] In one embodiment, the elongation at break of the renewable polyamide 56 fiber is ≤50%, further ≤45%, and even further ≤40%.

[0027] In one embodiment, the elongation at break (CV%) of the renewable polyamide 56 fiber is ≤6.0%, further ≤5.0%, and even further ≤4.0%.

[0028] In one embodiment, the evenness of the renewable polyamide 56 fiber is ≤1.5%, further ≤1.3%, and even further ≤1.1%.

[0029] In one embodiment, the dyeing uniformity (grey card) of the renewable polyamide 56 fiber is ≥4.0, further ≥4.5, and even further ≥4.7.

[0030] In one embodiment, the dyeing double A rate of the renewable polyamide 56 fiber is ≥95%, further ≥96%, and even further ≥97%.

[0031] In one embodiment, the renewable polyamide 56 fiber includes one or more of fully drawn yarn, pre-oriented yarn, textured yarn, highly oriented yarn, and short fiber, and is further defined as fully drawn yarn or textured yarn.

[0032] One embodiment of the present invention provides a method for preparing the above-mentioned renewable polyamide 56 fiber, the method comprising:

[0033] 1) Heat the tackified renewable polyamide 56 resin to a molten state to form polyamide 56 melt;

[0034] 2) The polyamide 56 melt is fed into the spinning box and ejected through the spinneret of the spinning assembly to form nascent filaments;

[0035] 3) Cool, oil, stretch, heat set and wind the nascent filaments to obtain the renewable polyamide 56 fiber.

[0036] In one embodiment, in step 1), the tackifying renewable polyamide 56 resin is obtained by tackifying renewable polyamide 56 resin.

[0037] In one embodiment, in step 1), the thickening treatment is performed using vacuuming or inert gas protection, wherein the vacuum level during vacuuming is -0.05 to -0.1 MPa.

[0038] In one embodiment, in step 1), the temperature of the thickening treatment is 130-180°C, and more specifically 140-170°C.

[0039] In one embodiment, in step 1), the thickening treatment time is 10-30 hours, or more specifically 15-25 hours.

[0040] In one embodiment, in step 1), the thickening treatment is carried out using a vacuum drum dryer or a continuous nitrogen dryer.

[0041] In one embodiment, the method for preparing the renewable polyamide 56 resin includes the following steps:

[0042] S1. Sorting, pre-cutting and crushing the waste polyamide 56 filaments and waste cloth, heating them to a molten state, and drawing a vacuum to form polyamide 56 melt;

[0043] S2. The polyamide 56 melt is filtered, cooled, stretched, pelletized, and dried to obtain the renewable polyamide 56 resin.

[0044] In one embodiment, the heating in step S1 is performed using a screw, which employs a five-zone heating system: zone one temperature is 250-270℃; zone two temperature is 260-280℃; zone three temperature is 270-285℃; zone four temperature is 275-290℃; and zone five temperature is 270-285℃.

[0045] In one embodiment, the filtration in step S2 is performed using a melt filter, wherein the mesh size of the melt filter is 3-20 μm, further 5-15 μm, and even further 8-10 μm, for example 6 μm, 7 μm, 9 μm, 12 μm, 14 μm, or 18 μm.

[0046] In one embodiment, in step 1), the heating is performed using a screw, which employs four-zone heating: zone one temperature is 260-280℃; zone two temperature is 270-285℃; zone three temperature is 275-290℃; and zone four temperature is 280-290℃.

[0047] In one embodiment, in step 2), the temperature of the spinning box is 273-288°C, further 275-285°C, and even further 278-283°C, for example 279°C, 280°C, 281°C, or 282°C.

[0048] In one embodiment, in step 2), the spinning assembly contains a 5-25μm nonwoven filter, further contains a 10-20μm nonwoven filter, and even further contains a 10-15μm nonwoven filter, for example, a 13μm nonwoven filter, a 16μm nonwoven filter, or an 18μm nonwoven filter.

[0049] In one implementation, in step 3), the draw ratio is 1.3-2.0, further 1.4-1.8, and even further 1.5-1.7, for example 1.6.

[0050] In one embodiment, the heat setting temperature is 160-190°C, further 165-185°C, and even further 170-180°C, for example 172°C, 175°C, 183°C, or 188°C.

[0051] In one embodiment, the winding speed is ≥4000m / min, further ≥4300m / min, and even further ≥4500m / min, for example 4600m / min or 4800m / min.

[0052] In one embodiment, the number of broken monofilaments of the renewable polyamide 56 fiber is ≤4 per spinning position 24h, further ≤3 per spinning position 24h, even further ≤2 per spinning position 24h, and still further ≤1 per spinning position 24h.

[0053] In one embodiment, the yield of the renewable polyamide 56 fiber is ≥95%, further ≥96%, and even further ≥97%.

[0054] In one embodiment, the spinning assembly is used for ≥10 days, more specifically ≥13 days, and even more specifically ≥15 days during the preparation of the renewable polyamide 56 fiber.

[0055] One embodiment of the present invention provides the application of the above-described renewable polyamide 56 fiber or the renewable polyamide 56 fiber prepared by the above-described method in the fields of woven and knitted fabrics.

[0056] One embodiment of the present invention discloses a renewable polyamide 56 fiber, which is produced by granulating recycled polyamide waste filaments and waste fabrics using renewable polyamide 56 resin as raw material. The resin is thickened to improve its relative viscosity and thermal crystallization properties, resulting in fewer broken monofilaments during spinning, a higher fiber yield, longer component replacement cycles, and higher production efficiency. The resulting renewable polyamide 56 fiber exhibits excellent mechanical and dyeing properties, achieving performance indicators comparable to conventional polyamide 56 fibers. Furthermore, it achieves the goal of recycling polyamide waste, turning waste into treasure, saving social resources, and effectively protecting the environment.

[0057] The following describes a specific embodiment of the renewable polyamide 56 fiber and its preparation therein. The testing methods used in each embodiment and comparative example are as follows.

[0058] (1) Relative viscosity: determined by concentrated sulfuric acid method using Ubbelohde viscometer.

[0059] (2) Terminal amino group: determined by automatic titrator.

[0060] (3) Moisture content: determined by Karl Fischer moisture titrator.

[0061] (4) Melting point and crystallization temperature: determined by DSC.

[0062] (5) Fracture strength, fracture strength CV%: determined in accordance with GB / T 14344-2008.

[0063] (6) Elongation at break, CV%: determined according to GB / T 14344-2008.

[0064] (7) Unevenness of the strip: determined by the Uster strip apparatus.

[0065] (8) Number of times a single filament breaks: counted manually.

[0066] (9) Production rate: Production rate = (mass of finished fiber prepared / total mass of polyamide resin or melt added) × 100%.

[0067] (10) Dyeing uniformity (grey card) / grade: according to FZ / T 50008 Test method for dyeing uniformity of nylon filament.

[0068] (11) Dyeing double A rate: Dyeing double A rate = (weight of fibers with dyeing uniformity ≥ 4.5 grade / total weight of all dyed fibers) × 100%.

[0069] Example 1

[0070] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0071] S1. The semi-dull polyamide 56 waste filaments are sorted, pre-cut and crushed, heated to a molten state, and vacuumed to remove water and oil, forming polyamide 56 melt; wherein, a screw is used for five-zone heating: zone 1 temperature is 260℃; zone 2 temperature is 265℃; zone 3 temperature is 270℃; zone 4 temperature is 280℃; zone 5 temperature is 285℃.

[0072] S2. The polyamide 56 melt is filtered using a melt filter, cooled, stretched, pelletized, and dried to obtain recyclable polyamide 56 resin; wherein the mesh size of the melt filter is 15μm.

[0073] The relative viscosity, terminal amino content, and purity of renewable polyamide 56 resin are shown in Table 1.

[0074] The regenerable polyamide 56 resin was subjected to thickening treatment using a vacuum drum dryer with vacuum protection at a vacuum level of -0.05 MPa. The thickening treatment temperature was 160℃ and the thickening treatment time was 12 h. The thickened regenerable polyamide 56 resin was obtained, and its relative viscosity, terminal amino content, melting point, crystallization temperature and moisture content are shown in Table 1.

[0075] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0076] 1) The tackifying renewable polyamide 56 resin is heated to a molten state to form polyamide 56 melt; wherein, a screw is used for four-zone heating: zone 1 temperature is 270℃; zone 2 temperature is 280℃; zone 3 temperature is 285℃; and zone 4 temperature is 285℃.

[0077] 2) The polyamide 56 melt is fed into the spinning box and sprayed out through the spinneret of the spinning assembly to form nascent filaments; wherein, the temperature of the spinning box is 283℃, and the spinning assembly contains a 20μm nonwoven filter screen.

[0078] 3) The nascent yarn is cooled, oiled, drawn, heat-set, and wound to obtain a 78dtex / 48f regenerable polyamide 56 fully drawn yarn; wherein the draw ratio is 1.6, the heat setting temperature is 180℃, and the winding speed is 4500m / min.

[0079] Example 2

[0080] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0081] S1. The waste filaments of fully matte polyamide 56 are sorted, pre-cut and crushed, heated to a molten state, and vacuumed to remove water and oil, forming polyamide 56 melt; wherein, a screw is used for five-zone heating: zone 1 temperature is 270℃; zone 2 temperature is 275℃; zone 3 temperature is 280℃; zone 4 temperature is 285℃; zone 5 temperature is 285℃.

[0082] S2. The polyamide 56 melt is filtered using a melt filter, cooled, stretched into strips, granulated, and dried to obtain recyclable polyamide 56 resin; wherein the mesh size of the melt filter is 10μm.

[0083] The relative viscosity, terminal amino content, and purity of renewable polyamide 56 resin are shown in Table 1.

[0084] The regenerable polyamide 56 resin was subjected to thickening treatment using a vacuum drum dryer with vacuum protection at a vacuum level of -0.06 MPa. The thickening treatment temperature was 170℃ and the thickening treatment time was 13 h. The thickened regenerable polyamide 56 resin was obtained, and its relative viscosity, terminal amino content, melting point, crystallization temperature and moisture content are shown in Table 1.

[0085] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0086] 1) The tackifying renewable polyamide 56 resin is heated to a molten state to form polyamide 56 melt; wherein, a screw is used for four-zone heating: zone 1 temperature is 270℃; zone 2 temperature is 280℃; zone 3 temperature is 283℃; and zone 4 temperature is 288℃.

[0087] 2) The polyamide 56 melt is fed into the spinning box and sprayed out through the spinneret of the spinning assembly to form nascent filaments; wherein, the temperature of the spinning box is 283℃, and the spinning assembly contains a 15μm nonwoven filter screen.

[0088] 3) The nascent yarn is cooled, oiled, drawn, heat-set, and wound to obtain a 78dtex / 48f regenerable polyamide 56 fully drawn yarn; wherein the draw ratio is 1.5, the heat setting temperature is 185℃, and the winding speed is 4600m / min.

[0089] Example 3

[0090] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0091] S1. The semi-dull polyamide 56 waste filaments are sorted, pre-cut and crushed, heated to a molten state, and vacuumed to remove water and oil, forming polyamide 56 melt; wherein, a screw is used for five-zone heating: zone 1 temperature is 265℃; zone 2 temperature is 268℃; zone 3 temperature is 272℃; zone 4 temperature is 278℃; zone 5 temperature is 280℃.

[0092] S2. The polyamide 56 melt is filtered using a melt filter, cooled, stretched into strips, granulated, and dried to obtain recyclable polyamide 56 resin; wherein the mesh size of the melt filter is 10μm.

[0093] The relative viscosity, terminal amino content, and purity of renewable polyamide 56 resin are shown in Table 1.

[0094] The regenerable polyamide 56 resin was subjected to thickening treatment using a vacuum drum dryer with vacuum protection at a vacuum level of -0.05 MPa. The thickening treatment temperature was 150℃ and the thickening treatment time was 15 h. The thickened regenerable polyamide 56 resin was obtained, and its relative viscosity, terminal amino content, melting point, crystallization temperature and moisture content are shown in Table 1.

[0095] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0096] 1) The tackifying renewable polyamide 56 resin is heated to a molten state to form polyamide 56 melt; wherein, a screw is used for four-zone heating: zone 1 temperature is 270℃; zone 2 temperature is 282℃; zone 3 temperature is 288℃; and zone 4 temperature is 288℃.

[0097] 2) The polyamide 56 melt is fed into the spinning box and sprayed out through the spinneret of the spinning assembly to form nascent filaments; wherein, the temperature of the spinning box is 285℃, and the spinning assembly contains a 15μm nonwoven filter screen.

[0098] 3) The nascent yarn is cooled, oiled, drawn, heat-set, and wound to obtain a 22dtex / 24f regenerable polyamide 56 fully drawn yarn; wherein the draw ratio is 1.5, the heat setting temperature is 170℃, and the winding speed is 4600m / min.

[0099] Example 4

[0100] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0101] The thickened renewable polyamide 56 resin was prepared using essentially the same raw materials and processes as in Example 1, except that the mesh size of the melt filter was 10 μm.

[0102] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0103] The thickened renewable polyamide 56 resin prepared above was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0104] Example 5

[0105] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0106] Tackified renewable polyamide 56 resin was prepared using the same raw materials and processes as in Example 1.

[0107] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0108] The above-prepared tackifying renewable polyamide 56 resin was used as raw material for spinning. The specific spinning process was basically the same as in Example 1, except that in step 2), the spinning assembly contained a 15μm nonwoven filter screen.

[0109] Example 6

[0110] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0111] The tackifying regenerable polyamide 56 resin was prepared using essentially the same raw materials and processes as in Example 1, except that the regenerable polyamide 56 resin was subjected to tackifying treatment using a vacuum drum drying device at a temperature of 165°C and a treatment time of 18 hours.

[0112] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0113] The thickened renewable polyamide 56 resin prepared above was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0114] Comparative Example 1

[0115] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0116] The thickened renewable polyamide 56 resin was prepared using essentially the same raw materials and processes as in Example 1, except that a melt filter was not used for filtration in step S2.

[0117] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0118] The thickened renewable polyamide 56 resin prepared above was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0119] Comparative Example 2

[0120] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0121] The tackifying renewable polyamide 56 resin was prepared using essentially the same raw materials and processes as in Example 1. The difference was that in step S1, a screw was used for five-zone heating: zone 1 temperature was 230°C; zone 2 temperature was 250°C; zone 3 temperature was 260°C; zone 4 temperature was 265°C; and zone 5 temperature was 260°C.

[0122] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0123] The thickened renewable polyamide 56 resin prepared above was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0124] Comparative Example 3

[0125] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0126] The tackifying renewable polyamide 56 resin was prepared using essentially the same raw materials and processes as in Example 1. The difference was that in step S1, a screw was used for five-zone heating: zone 1 temperature was 280°C; zone 2 temperature was 290°C; zone 3 temperature was 300°C; zone 4 temperature was 305°C; and zone 5 temperature was 300°C.

[0127] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0128] The thickened renewable polyamide 56 resin prepared above was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0129] Comparative Example 4

[0130] I. Preparation of Renewable Polyamide 56 Resin

[0131] Renewable polyamide 56 resin was prepared using the same raw materials and processes as in Example 1, except that there was no thickening process.

[0132] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0133] The above-prepared renewable polyamide 56 resin was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0134] Comparative Example 5

[0135] I. Preparation of Tackifying Renewable Polyamide 56 Resin

[0136] The tackifying renewable polyamide 56 resin was prepared using essentially the same raw materials and processes as in Example 1, except that the tackifying treatment temperature was 180°C and the tackifying treatment time was 16 hours.

[0137] II. Preparation of Renewable Polyamide 56 Fully Drawn Yarn

[0138] The thickened renewable polyamide 56 resin prepared above was used as raw material for spinning, and the specific spinning process was the same as in Example 1.

[0139] Table 1. Parameters of renewable polyamide 56 resin and tackified renewable polyamide 56 resin in each example and comparative example.

[0140]

[0141] Table 2. Properties of Renewable Polyamide 56 Fibers in Each Example and Comparative Example

[0142]

[0143]

[0144] As shown in Tables 1 and 2, compared to Comparative Examples 1 to 5, the renewable polyamide 56 fibers obtained in Examples 1 to 6 of this invention exhibit higher breaking strength, lower breaking strength CV%, lower breaking elongation CV%, and lower yarn unevenness, as well as higher dyeing uniformity and dyeing double A rate. This indicates that the mechanical and dyeing properties of the renewable polyamide 56 fibers in Examples 1 to 6 are significantly superior to those in Comparative Examples 1 to 5. Therefore, by using a tackified renewable polyamide 56 resin with specific parameters obtained by tackifying a recycled polyamide 56 resin produced from recycled polyamide waste yarn and waste fabric as raw material, this invention not only achieves mechanical and dyeing properties comparable to conventional polyamide 56 fibers but also realizes the goal of recycling polyamide waste.

[0145] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0146] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A renewable polyamide 56 fiber characterized in that, Its raw materials include at least tackifying renewable polyamide 56 resin; the relative viscosity of the tackifying renewable polyamide 56 resin is 2.4-2.9, and the terminal amino content of the tackifying renewable polyamide 56 resin is 32-48 mmol / kg.

2. The renewable polyamide 56 fiber according to claim 1, characterized in that, The relative viscosity of the tackifying renewable polyamide 56 resin is 2.5-2.85, more preferably 2.6-2.8; and / or, The tackifying renewable polyamide 56 resin has a terminal amino content of 34-46 mmol / kg, more specifically 36-44 mmol / kg; and / or, The crystallization temperature of the tackified renewable polyamide 56 resin is 180-210°C, further 190-210°C, and even further 200-210°C; and / or, The tackifying renewable polyamide 56 resin has a melting point of 250-255°C, more specifically 252-254°C; and / or, The moisture content of the thickened renewable polyamide 56 resin is 300-600 ppm, further 300-500 ppm, and even further 300-400 ppm.

3. The renewable polyamide 56 fiber according to claim 1, wherein, The thickened renewable polyamide 56 resin is obtained by thickening renewable polyamide 56 resin; wherein, based on the total weight of the renewable polyamide 56 resin, the content of renewable polyamide 56 resin is ≥99.0wt%, and more specifically ≥99.5wt%.

4. The renewable polyamide 56 fiber according to claim 3, characterized in that, The relative viscosity of the renewable polyamide 56 resin is 2.0-2.6, more preferably 2.1-2.5, and even more preferably 2.2-2.4; and / or, The terminal amino content of the renewable polyamide 56 resin is 35-50 mmol / kg, further 38-50 mmol / kg, and even further 42-50 mmol / kg.

5. The renewable polyamide 56 fiber according to any one of claims 1 to 4, characterized in that, The regenerated polyamide 56 fiber has a breaking strength of 3.0-5.0 cN / dtex, further 3.3-4.8 cN / dtex, even further 3.5-4.5 cN / dtex, and still further 3.8-4.5 cN / dtex; and / or, The regenerated polyamide 56 fiber has a breaking strength CV% of ≤5.0%, further ≤4.0%, and even further ≤3.0%; and / or, The elongation at break of the renewable polyamide 56 fiber is ≤50%, further ≤45%, and even further ≤40%; and / or, The elongation at break (CV%) of the renewable polyamide 56 fiber is ≤6.0%, further ≤5.0%, and even further ≤4.0%; and / or, The evenness of the renewable polyamide 56 fiber is ≤1.5%, further ≤1.3%, and even further ≤1.1%; and / or, The dyeing uniformity (grey scalar) of the renewable polyamide 56 fiber is ≥4.0, further ≥4.5, and even further ≥4.7; and / or, The dyeing double A rate of the renewable polyamide 56 fiber is ≥95%, further ≥96%, and even further ≥97%.

6. The renewable polyamide 56 fiber according to claim 1, wherein, The renewable polyamide 56 fiber includes one or more of fully drawn yarn, pre-oriented yarn, textured yarn, highly oriented yarn, and short fiber, and is further defined as fully drawn yarn or textured yarn.

7. A method for preparing renewable polyamide 56 fiber according to any one of claims 1 to 6, characterized in that, The preparation method includes: 1) Heat the tackified renewable polyamide 56 resin to a molten state to form polyamide 56 melt; 2) The polyamide 56 melt is fed into the spinning box and ejected through the spinneret of the spinning assembly to form nascent filaments; 3) Cool, oil, stretch, heat set and wind the nascent filaments to obtain the renewable polyamide 56 fiber.

8. The method for preparing renewable polyamide 56 fiber according to claim 7, characterized in that, In step 1), the tackifying renewable polyamide 56 resin is obtained by tackifying renewable polyamide 56 resin. The thickening treatment is performed under vacuum or inert gas protection, wherein the vacuum level during vacuuming is -0.05 to -0.1 MPa; and / or, The temperature for the thickening treatment is 130-180℃, more specifically 140-170℃; and / or, The thickening treatment is performed for 10-30 hours, more specifically 15-25 hours; and / or, The thickening treatment is carried out using a vacuum drum dryer or a continuous nitrogen dryer.

9. The method for preparing renewable polyamide 56 fiber according to claim 8, characterized in that, The preparation method of the renewable polyamide 56 resin includes the following steps: S1. Sorting, pre-cutting and crushing the waste polyamide 56 filaments and waste cloth, heating them to a molten state, and drawing a vacuum to form polyamide 56 melt; S2. The polyamide 56 melt is filtered, cooled, stretched, pelletized, and dried to obtain the renewable polyamide 56 resin. In step S1, the heating is performed using a screw, which employs a five-zone heating system: zone one temperature is 250-270℃; zone two temperature is 260-280℃; zone three temperature is 270-285℃; zone four temperature is 275-290℃; and zone five temperature is 270-285℃. The filtration in step S2 is performed using a melt filter, wherein the mesh size of the melt filter is 3-20μm, further 5-15μm, and even further 8-10μm.

10. The method for preparing renewable polyamide 56 fiber according to claim 7, characterized in that, In step 1), the heating is performed using a screw, which employs a four-zone heating system: zone one temperature is 260-280℃; zone two temperature is 270-285℃; zone three temperature is 275-290℃; and zone four temperature is 280-290℃; and / or, In step 2), the temperature of the spinning box is 273-288℃, further 275-285℃, and even further 278-283℃; and / or, the spinning assembly contains a 5-25μm nonwoven filter, further containing a 10-20μm nonwoven filter, and even further containing a 10-15μm nonwoven filter; and / or, In step 3), the draw ratio is 1.3-2.0, further 1.4-1.8, and even further 1.5-1.7; and / or, the heat setting temperature is 160-190℃, further 165-185℃, and even further 170-180℃; and / or, the winding speed is ≥4000m / min, further ≥4300m / min, and even further ≥4500m / min.

11. The method for preparing renewable polyamide 56 fiber according to any one of claims 7 to 10, characterized in that, The number of broken monofilaments in the renewable polyamide 56 fiber is ≤4 per spinning position in 24 hours, further ≤3 per spinning position in 24 hours, even further ≤2 per spinning position in 24 hours, and still further ≤1 per spinning position in 24 hours; and / or, The yield of the renewable polyamide 56 fiber is ≥95%, further ≥96%, and even further ≥97%; and / or, The spinning assembly used in the preparation of the renewable polyamide 56 fiber has a service life of ≥10 days, further ≥13 days, and even further ≥15 days.

12. The application of the renewable polyamide 56 fiber according to any one of claims 1 to 6 or the renewable polyamide 56 fiber prepared by any one of claims 7 to 11 in the field of weaving and knitting.

Images