Self-curling bio-based furan polyester filament and direct spinning preparation method thereof

Abstract

The present invention discloses a self-curling bio-based furan polyester filament and a direct spinning method for preparing the same. Using 2,5-furandicarboxylic acid, ethylene glycol, a catalyst, and a stabilizer as raw materials, the filaments are continuously polymerized, melt-spun, and expanded in a hot and humid environment to form a unique spiral or wavy morphology. The resulting bio-based furan polyester filaments possess a permanently curled structure. During the melt-spinning process, multiple evenly distributed static mixers are utilized, and their fork or vane angles are improved and optimized to achieve better heat dissipation and mixing. This addresses the poor heat resistance of bio-based furan polyester melts during long-distance transport, avoids degradation due to reverse reactions, and improves the chemical stability and uniformity of the filament product.

Description

Technical Field

[0001] The invention relates to the preparation of polyester filaments, in particular to self-curling bio-based furan polyester filaments, and a method for preparing the filaments by continuous polymerization and direct spinning, belonging to the technical field of fiber processing. Background Art

[0002] With the dwindling availability of petroleum resources and the intensification of white pollution, the country has successively introduced "dual carbon" goals and plastic restrictions, restricting the use of petroleum-based polyesters. Bio-based polyester raw materials, derived entirely or partially from biomass, can effectively reduce carbon emissions and conserve energy. Compared to PET, bio-based furan polyester (PEF) has higher gas barrier properties to oxygen, carbon dioxide, and water vapor, making it a suitable alternative for bottles, films, and food packaging applications. Furthermore, PEF has higher melt strength, and fiber products produced from PEF have higher mechanical properties, making it a suitable alternative to polyester fibers. This not only reduces the carbon footprint of polyester products but also improves the sustainability of fiber applications. Furthermore, PEF is a bio-based polyester made from lignocellulose. Its raw material, 2,5-furandicarboxylic acid, is a furan derivative that can be obtained through bio-fermentation or bio-fermentation of renewable cellulosic biomass feedstocks such as corn, straw, and sugar beets. It has been recognized by the U.S. Department of Energy as one of 12 important bio-based platform compounds. It has a planar aromatic ring and a rigid structure, primarily used to replace benzene rings in petroleum-based platform compounds. As early as 2004, 2,5-furandicarboxylic acid was rated as one of the 12 most promising bio-based platform compounds. It has a structure similar to terephthalic acid, and the polymer synthesized with ethylene glycol has excellent mechanical properties, mechanical properties and processing properties.

[0003] In the existing technology, bio-based furan polyester fibers are mainly produced by melt spinning pure PEF chips. See the following existing technology solutions for details:

[0004] 1) Chinese patent CN117209735 discloses a method for preparing a cationic dyeable bio-based furan dicarboxylic acid polyester and fiber. The method involves drying cationic dyeable bio-based furan dicarboxylic acid polyester chips to a moisture content of less than 30 ppm. The chips are then melt-spinned into a screw extruder, followed by metering, cooling, bundling, hot drawing, and winding to produce the cationic dyeable bio-based furan dicarboxylic acid polyester fiber. This invention primarily addresses issues such as uneven dyeing and low dye uptake in PEF fibers.

[0005] 2) Chinese patent CN117286598 discloses a melt-spinning method for preparing low-heat-shrinkage bio-based furandicarboxylic acid copolyester fibers. By formulating the bio-based monomer 2,5-furandicarboxylic acid with a mixed diol, a polymerization process is conducted to produce a bio-based furan copolyester with excellent overall performance. This method then combines this with a heat-setting and stretching process to produce a low-heat-shrinkage bio-based furan copolyester fiber. This invention primarily addresses the problems of high dry-heat and boiling-water shrinkage of the fiber, as well as relatively low mechanical strength.

[0006] 3) Chinese patent CN106544754 discloses a melt-spinning method for preparing 2,5-furandicarboxylic acid polyester fibers. The melt-spinning method involves drying the 2,5-furandicarboxylic acid polyester; then adding a catalyst to solid-phase thicken the 2,5-furandicarboxylic acid polyester under vacuum or an inert atmosphere; then adding a decarboxylation inhibitor and an antioxidant to the treated 2,5-furandicarboxylic acid polyester; and finally, melting the filaments through a spinning screw, which enters a spinning manifold, passes through a metering pump, and is ejected from a spinning assembly into filaments. The fibers are then cooled on a cooling plate, wound, and stretched to produce the 2,5-furandicarboxylic acid polyester fibers. This invention primarily addresses the issues of performance stability, recyclability, and biodegradability that PET polyester fibers lack.

[0007] 4) International patent PCJ / JP2016 / 00486 discloses a melt-spinning method for preparing PEF fibers with high storage modulus. The resulting PEF fibers have the advantages of being environmentally friendly and biodegradable.

[0008] However, none of the above inventions mention PEF melt direct spinning, melt delivery technology, or the special spiral morphology and permanent curl structure of PEF fibers. The melt spinning process of PEF chips involves the crystallization, drying, and re-melting and heating of the chips. During long-distance transportation, the polymer is easily degraded due to unstable pressure, and the finished product has a high oligomer content, which to a certain extent affects the spinning and drawing processes and the mechanical properties and dyeing uniformity of the fiber products. In addition, PEF has poor crystallization ability and is difficult to dry and crystallize. The fibers produced by melt spinning have poor uniformity, which in turn causes many problems in the subsequent weaving, dyeing and finishing processes, limiting the application of PEF fibers.

[0009] Furthermore, bio-based furan polyester produced using existing technologies has relatively poor thermal stability. During secondary melt processing, it easily degrades to form oligomers that are prone to carbonization and precipitation, resulting in reduced fiber performance. This, in turn, leads to various problems during the spinning process, such as shortened scraping cycles, increased number of strand breakages, and shortened assembly cycles. Therefore, further research is necessary on the entire process of bio-based furan polyester filaments, from polymerization of raw materials to spinning, to improve the overall performance of the resulting filaments and optimize their subsequent applications. Summary of the Invention

[0010] The purpose of the present invention is to solve the above problems and provide a self-curling bio-based furan polyester filament and a continuous polymerization direct spinning preparation method thereof, so as to solve the problems existing in the direct spinning production process of bio-based furan polyester filament: unstable melt pressure over long distances, reverse reaction degradation, poor overall performance of the filament product, etc.

[0011] The technical solution of the present invention is: a self-curling bio-based furan polyester filament, which is made from bio-based furan polyester as raw material through melt spinning and puffing treatment. Its characteristics are: calculated by weight, the raw materials for preparing the bio-based furan polyester include: 30 to 80 parts of 2,5-furandicarboxylic acid, 45 to 200 parts of ethylene glycol, 5 to 8 parts of a catalyst and 5 to 8 parts of a stabilizer.

[0012] The catalyst is one or more metal catalysts selected from titanium, germanium, antimony, tin, zinc, etc., and the added amount accounts for 5 to 100 ppm of the total amount of the bio-based furan polyester; the stabilizer is one or more phosphorus-containing organic compounds such as triphenyl phosphate, and the added amount accounts for 10 to 500 ppm of the total amount of the bio-based furan polyester.

[0013] The preparation method of 2,5-furandicarboxylic acid comprises the following steps: (1) adding furfural and then adding potassium oxide aqueous solution to a reactor, wherein the amount of potassium oxide aqueous solution added is 150% to 300% of the amount of furfural added by mole, and oxidizing the furfural to potassium furate by catalysis of nano-copper oxide; (2) adding zinc salt in an amount of 5% to 30% of the amount of potassium furate added by weight, and using zinc salt to catalyze potassium furate to carry out Henkel reaction to generate dipotassium furandicarboxylate and furan; (3) acidifying the dipotassium furandicarboxylate at a pH value of ≤4.5 and a temperature of 40 to 75° C. to obtain the 2,5-furandicarboxylic acid.

[0014] The present invention also provides a method for preparing the self-curling bio-based furan polyester filaments by direct spinning, comprising the following steps:

[0015] Step (1): dissolving 2,5-furandicarboxylic acid in ethylene glycol and stirring to dissolve the mixture to obtain a mixed solution A, wherein the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1:1.6-2.4; adding a catalyst and a stabilizer to the mixed solution A to obtain a mixed solution B; beating the mixed solution B to obtain a mixed solution C; placing the mixed solution C in an esterification kettle for esterification reaction to obtain a mixed solution D; and then sequentially introducing the mixed solution D into a pre-polycondensation kettle and a final polycondensation kettle for polycondensation reaction to obtain a bio-based furan polyester melt;

[0016] Step (2): Under the action of a booster pump, the bio-based furan polyester melt prepared in step (1) is sequentially pressed into a melt filter, a first heat exchanger, a static mixer, and a second heat exchanger through a transmission pipeline for impurity removal and sufficient mixing, and then transported to a spinning line device for direct spinning processing. After the spinning line is metered, extruded, cooled, stretched, heat-set, and wound, a bio-based furan polyester drawn yarn is obtained;

[0017] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature range of 60 to 100° C. and a relative humidity of 30 to 95%. After the wet heat treatment for 15 to 20 minutes, the yarn is dried to obtain a helical bio-based furan polyester filament having a permanent curl structure.

[0018] Furthermore, in the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, the intrinsic viscosity of the bio-based furan polyester melt is 0.4 to 0.8 dl / g.

[0019] Furthermore, in the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, the pressure of the esterification reaction is 12 to 50 mmHg, the temperature is 210 to 240° C., and the esterification reaction time is 2 to 3 hours.

[0020] Furthermore, in the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, the pressure of the polycondensation reaction is 0.5-5.0 mmHg, the temperature is 220-260° C., and the reaction time of the polycondensation reaction is 3.5-5 hours.

[0021] Furthermore, the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, wherein: in step (2), the static mixer is provided with at least one, preferably a Kenics type static mixer with a rotor angle of 90 to 180 degrees, or an LPD type static mixer with a fork angle of 30 to 90 degrees; in particular, a Kenics type static mixer with a rotor angle of 90 degrees, 120 degrees or 180 degrees, or an LPD type static mixer with a fork angle of 30 degrees, 60 degrees or 90 degrees.

[0022] Furthermore, in the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, the direct spinning processing temperature required for the bio-based furan polyester melt is 230-270° C. and the post-pump pressure is 15-30 MPa.

[0023] Furthermore, in the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, the drying time is 1 to 1.5 hours and the drying temperature is 60 to 120°C.

[0024] Furthermore, the above-mentioned direct spinning preparation method of self-curling bio-based furan polyester filaments, wherein: the main process parameters of melt direct spinning in the spinning line equipment are: the spinning box temperature is 220~275℃; the first hot roller speed is 800~1500m / min, and the temperature is 80~120℃; the second hot roller speed is 2500~4500m / min, and the temperature is 100~160℃; the cooling air temperature is 20~25℃; the cooling air speed is 0.2~3m / s; and the winding speed is 800~4500m / min.

[0025] Compared with the prior art, after adopting the technical solution of the present invention, the self-curling bio-based furan polyester filaments obtained have a unique spiral morphology and permanent curling structure, high chemical stability and uniformity, so as to expand the application range of bio-based furan polyester fibers; moreover, the continuous polymerization direct spinning preparation method of the self-curling bio-based furan polyester filaments has a short process, fewer steps, low oligomer content, high melt quality, reduced processing viscosity, and excellent spinning performance; in addition, multiple static mixers are evenly distributed and the fork angle or rotor angle therein is improved and optimized, and each static mixer is used in combination to have better heat dissipation and mixing effects, thereby improving the uniformity of the mixing temperature, reducing the temperature difference in the pipeline, and improving the phenomenon of local temperature rise caused by the poor fluidity of the bio-based furan polyester, thereby solving the problem of poor heat resistance of the melt during long-distance transport of the bio-based furan polyester melt direct spinning, maintaining pressure stability, and avoiding reverse reaction degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The electron microscope images of the spiral and wavy structures of the polyester filaments of the present invention are shown;

[0027] Figure 2 This is a graph showing the elongation at break test results of the filament product of Example 3 of the present invention;

[0028] Figure 3 This is a graph showing the elongation at break test results of the filament product of Example 6 of the present invention;

[0029] Figure 4 This is a graph showing the elongation at break test results of the filament product of Comparative Example 3 of the present invention;

[0030] Figure 5 This is a graph showing the elongation at break test results of the filament product of Comparative Example 5 of the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described below with reference to specific examples, but it should not be understood that the scope of protection of the above subject matter of the present invention is limited to the following examples. Among them, the raw materials used are all commercially available or homemade using methods known in the industry. Example 1

[0032] Step (1): the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1 to 2.4, 2,5-furandicarboxylic acid is dissolved in ethylene glycol, and stirred to dissolve to obtain a mixed solution A; titanium ethylene glycol (the amount of titanium ethylene glycol added is 40ppm of the total amount of bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added is 100ppm of the bio-based furan polyester) are added to the mixed solution A to obtain a mixed solution B; the mixed solution B is pulped to obtain a mixed solution The mixed solution C was placed in an esterification kettle for esterification reaction at a temperature of 170°C and a pressure of 20 kPa to obtain a mixed solution D; the mixed solution D was then introduced into a pre-polycondensation kettle and a final polycondensation kettle in sequence for polycondensation reaction at a temperature of 210°C and a vacuum degree of 12 mmHg, and a final polycondensation temperature and a vacuum degree of 220°C and 0.5 mmHg to obtain a bio-based furan polyester melt with an esterification rate of 94% and a melt intrinsic viscosity of 0.50 dl / g.

[0033] Step (2): Using a booster pump, the bio-based furan polyester melt produced in step (1) is introduced from the feed port into the bio-based furan polyester yarn drawing apparatus. The melt is then sequentially pressed through a transmission pipeline into a melt filter (melt temperature of 240°C, pump pressure of 20 MPa), a first heat exchanger, a Kenics static mixer (rotor angle of 120°), and a second heat exchanger for thorough mixing and removal of impurities. The melt is then transferred to the spinning line equipment for direct spinning. The spinning line equipment parameters are set as follows: spinning manifold temperature of 235°C, first heated roller speed of 1400 m / min, temperature of 110°C, second heated roller speed of 3025 m / min, temperature of 150°C, cooling air temperature of 20°C, cooling air velocity of 0.3 m / s, and winding speed of 2980 m / min. After spinning line metering, extrusion, cooling, drawing, heat setting and winding treatments, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0034] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature of 90° C. and a relative humidity of 90%. After the wet heat treatment for 15 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Example 2

[0035] Step (1): the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1.3 to 2.4, 2,5-furandicarboxylic acid is dissolved in ethylene glycol, and stirred to dissolve to obtain a mixed solution A; titanium ethylene glycol (the amount of titanium ethylene glycol added is 40ppm of the total amount of bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added is 100ppm of the bio-based furan polyester) are added to the mixed solution A to obtain a mixed solution B; the mixed solution B is pulped to obtain a mixed solution. The mixed solution C was placed in an esterification kettle for esterification reaction at a temperature of 190° C. and a pressure of 70 kPa to obtain a mixed solution D; the mixed solution D was then introduced into a pre-polycondensation kettle and a final polycondensation kettle in sequence for polycondensation reaction at a pre-polycondensation temperature of 220° C. and a vacuum degree of 30 mmHg, and at a final polycondensation temperature of 240° C. and a vacuum degree of 3.0 mmHg to obtain a bio-based furan polyester melt with an esterification rate of 94% and a melt intrinsic viscosity of 0.51 dl / g.

[0036] Step (2): The bio-based furan polyester melt produced in step (1) was introduced into the bio-based furan polyester yarn drawing apparatus through a booster pump. The melt was then sequentially pressed through a transfer pipeline into a melt filter (melt temperature: 240°C, pump pressure: 20 MPa), a first heat exchanger, a Kenics static mixer (rotor angle: 120°), and a second heat exchanger for thorough mixing and removal of impurities. The melt was then transferred to the spinning line equipment for direct spinning. The spinning line equipment parameters were set as follows: spinning box temperature: 236°C, first heated roller speed: 1400 m / min, temperature: 110°C, second heated roller speed: 3025 m / min, temperature: 150°C, cooling air temperature: 22°C, cooling air velocity: 0.6 m / s, and winding speed: 2980 m / min. After spinning line metering, extrusion, cooling, drawing, heat setting and winding treatments, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0037] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature of 90° C. and a relative humidity of 90%. After the wet heat treatment for 18 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Example 3

[0038] Step (1): the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1.6 to 2.4, 2,5-furandicarboxylic acid is dissolved in ethylene glycol, and stirred to dissolve to obtain a mixed solution A; titanium ethylene glycol (the amount of titanium ethylene glycol added is 40ppm of the total amount of bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added is 100ppm of the bio-based furan polyester) are added to the mixed solution A to obtain a mixed solution B; the mixed solution B is pulped to obtain a mixed solution. The mixed solution C was placed in an esterification kettle for esterification reaction at a temperature and pressure of 245°C and 100 kPa to obtain a mixed solution D; the mixed solution D was then introduced into a pre-polycondensation kettle and a final polycondensation kettle in sequence for polycondensation reaction at a pre-polycondensation temperature and a vacuum degree of 240°C and 50 mmHg, and a final polycondensation temperature and a vacuum degree of 260°C and 5.0 mmHg to obtain a bio-based furan polyester melt with an esterification rate of 94% and a melt intrinsic viscosity of 0.53 dl / g.

[0039] Step (2): Using a booster pump, the bio-based furan polyester melt produced in step (1) is introduced from the feed port into the bio-based furan polyester yarn drawing apparatus. The melt is then sequentially pressed through a transfer pipeline into a melt filter (melt temperature: 240°C, pump pressure: 20 MPa), a first heat exchanger, a Kenics static mixer (rotor angle: 120°), and a second heat exchanger for thorough mixing and removal of impurities. The melt is then transferred to the spinning line equipment for direct spinning. The spinning line equipment parameters are set as follows: spinning box temperature: 238°C, first heated roller speed: 1400 m / min, temperature: 110°C, second heated roller speed: 3025 m / min, temperature: 150°C, cooling air temperature: 25°C, cooling air velocity: 1.0 m / s, and winding speed: 2980 m / min. After spinning line metering, extrusion, cooling, drawing, heat setting and winding treatments, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0040] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature of 90° C. and a relative humidity of 90%. After the wet heat treatment for 20 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Example 4

[0041] Step (1): dissolving 2,5-furandicarboxylic acid in ethylene glycol and stirring to dissolve it to obtain a mixed solution A, wherein the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1 to 2.4; adding titanium glycolate (the amount of titanium glycolate added is 50 ppm of the total amount of the bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added is 100 ppm of the bio-based furan polyester) to the mixed solution A to obtain a mixed solution B; beating the mixed solution B to obtain a mixed solution C; placing the mixed solution C in an esterification kettle for an esterification reaction (esterification rate is 96%) to obtain a mixed solution D; and then sequentially introducing the mixed solution D into a pre-polycondensation kettle and a final polycondensation kettle for a polycondensation reaction to obtain a bio-based furan polyester melt with a melt intrinsic viscosity of 0.64 to 0.67 dl / g.

[0042] Step (2): Using a booster pump, the bio-based furan polyester melt produced in step (1) is introduced from the feed port into the bio-based furan polyester yarn drawing apparatus. The melt is then sequentially pressed through a transmission pipeline into a melt filter (melt temperature: 240°C, pump pressure: 20 MPa), a first heat exchanger, an LPD static mixer (LPD static mixer with a fork angle of 30°), and a second heat exchanger for thorough mixing and removal of impurities. The melt is then transferred to the spinning line equipment for direct spinning. The spinning line equipment parameters are as follows: spinning beam temperature: 260°C; first heated roller speed: 1400 m / min, temperature: 110°C; second heated roller speed: 3950 m / min, temperature: 150°C; cold air temperature: 20°C, cold air speed: 0.6 m / s; and winding speed: 3900 m / min. After spinning line metering, extrusion, cooling, drawing, heat setting and winding treatments, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0043] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature of 90° C. and a relative humidity of 90%. After the wet heat treatment for 15 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Example 5

[0044] Step (1): dissolving 2,5-furandicarboxylic acid in ethylene glycol and stirring to dissolve it to obtain a mixed solution A, wherein the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 12 to 2.4; adding titanium glycolate (the amount of titanium glycolate added is 50 ppm of the total amount of the bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added is 100 ppm of the bio-based furan polyester) to the mixed solution A to obtain a mixed solution B; beating the mixed solution B to obtain a mixed solution C; placing the mixed solution C in an esterification kettle for an esterification reaction (esterification rate is 96%) to obtain a mixed solution D; and then sequentially introducing the mixed solution D into a pre-polycondensation kettle and a final polycondensation kettle for a polycondensation reaction to obtain a bio-based furan polyester melt having a melt intrinsic viscosity of 0.65 dl / g;

[0045] Step (2): Using a booster pump, the bio-based furan polyester melt produced in step (1) is introduced from the feed port into the bio-based furan polyester yarn drawing apparatus. The melt is then sequentially pressed through a transmission pipeline into a melt filter (melt temperature: 240°C, pump pressure: 20 MPa), a first heat exchanger, an LPD static mixer (LPD static mixer with a fork angle of 30°), and a second heat exchanger for thorough mixing and removal of impurities. The melt is then transferred to the spinning line equipment for direct spinning. The spinning line equipment parameters are as follows: spinning beam temperature: 261°C; first heated roller speed: 1400 m / min, temperature: 110°C; second heated roller speed: 3950 m / min, temperature: 150°C; cold air temperature: 23°C, cold air speed: 0.6 m / s; and winding speed: 3900 m / min. After spinning line metering, extrusion, cooling, drawing, heat setting and winding treatments, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0046] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature of 90° C. and a relative humidity of 95%. After the wet heat treatment for 17 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Example 6

[0047] Step (1): dissolving 2,5-furandicarboxylic acid in ethylene glycol and stirring to dissolve it to obtain a mixed solution A, wherein the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1.6 to 2.4; adding titanium glycolate (the amount of titanium glycolate added is 50 ppm of the total amount of the bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added is 100 ppm of the bio-based furan polyester) to the mixed solution A to obtain a mixed solution B; beating the mixed solution B to obtain a mixed solution C; placing the mixed solution C in an esterification kettle for an esterification reaction (esterification rate is 96%) to obtain a mixed solution D; and then sequentially introducing the mixed solution D into a pre-polycondensation kettle and a final polycondensation kettle for a polycondensation reaction to obtain a bio-based furan polyester melt with a melt intrinsic viscosity of 0.67 dl / g.

[0048] Step (2): Using a booster pump, the bio-based furan polyester melt produced in step (1) is introduced from the feed port into the bio-based furan polyester yarn drawing apparatus. The melt is then sequentially pressed through a transmission pipeline into a melt filter (melt temperature: 240°C, pump pressure: 20 MPa), a first heat exchanger, an LPD static mixer (LPD static mixer with a fork angle of 30°), and a second heat exchanger for thorough mixing and removal of impurities. The melt is then transferred to the spinning line equipment for direct spinning. The spinning line equipment parameters are as follows: spinning beam temperature: 262°C; first heated roller speed: 1400 m / min, temperature: 110°C; second heated roller speed: 3950 m / min, temperature: 150°C; cold air temperature: 25°C, cold air speed: 0.6 m / s; and winding speed: 3900 m / min. After spinning line metering, extrusion, cooling, drawing, heat setting and winding treatments, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0049] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature of 90° C. and a relative humidity of 98%. After the wet heat treatment for 20 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Example 7

[0050] Step (1): dissolving 2,5-furandicarboxylic acid in ethylene glycol and stirring to dissolve it to obtain a mixed solution A, wherein the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1 to 2.4; adding titanium glycolate (the amount of titanium glycolate added accounts for 60 ppm of the total amount of the bio-based furan polyester) and triphenyl phosphate (the amount of triphenyl phosphate added accounts for 100 ppm of the bio-based furan polyester) to the mixed solution A to obtain a mixed solution B; beating the mixed solution B to obtain a mixed solution C; placing the mixed solution C in an esterification kettle for an esterification reaction (esterification rate is 98%) to obtain a mixed solution D; and then sequentially introducing the mixed solution D into a pre-polycondensation kettle and a final polycondensation kettle for a polycondensation reaction to obtain a bio-based furan polyester melt with a melt intrinsic viscosity of 0.75 dl / g.

[0051] Step (2): Using a booster pump, the bio-based furan polyester melt produced in step (1) is introduced from the feed port into the bio-based furan polyester yarn drawing apparatus. The melt is then sequentially pressed through a transmission pipeline into a melt filter (melt delivery temperature of 270°C and pump pressure of 26 MPa), a first heat exchanger, a Kenics static mixer (rotor angle of 90°), and a second heat exchanger for thorough mixing and removal of impurities. The melt is then conveyed to the spinning line equipment for direct spinning. The spinning line equipment parameters are set as follows: spinning box temperature of 270°C; first heated roller speed of 1400 m / min and temperature of 110°C; second heated roller speed of 3950 m / min and temperature of 150°C; cooling air temperature of 24°C and cooling air speed of 0.6 m / s; and winding speed of 3900 m / min. Therefore, after the spinning line metering, extrusion, cooling, drawing heat setting and winding treatment, the bio-based furan polyester drawn yarn is produced by discharging the material from the discharging end.

[0052] Step (3): The bio-based furan polyester drawn yarn obtained in step (2) is subjected to a wet heat treatment at a temperature range of 90° C. and a relative humidity of 90%. After the wet heat treatment for 15 to 20 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying. Comparative Example 1

[0053] Bio-based furan polyester with an intrinsic viscosity of 0.52 dl / g was chipped and crystallized and dried in a rotary drum oven at 140°C for 12 hours. The filament was then produced through screw extrusion, metering, cooling, drawing, heat setting, and winding. The main spinning parameters were: spinning beam temperature of 235°C; first hot roller speed of 1500 m / min and temperature of 110°C; second hot roller speed of 3025 m / min and temperature of 150°C; cooling air temperature of 20°C and cooling air speed of 0.3 m / s; winding speed of 2980 m / min; and wet heat treatment: relative humidity of 90% and temperature of 90°C. Comparative Example 2

[0054] Bio-based furan polyester with an intrinsic viscosity of 0.52 dl / g was chipped and crystallized and dried in a rotary drum oven at 140°C for 12 hours. The filament was then produced through screw extrusion, metering, cooling, drawing, heat setting, and winding. The main spinning parameters were: spinning beam temperature of 236°C; first hot roller speed of 1500 m / min and temperature of 110°C; second hot roller speed of 3025 m / min and temperature of 150°C; cold air temperature of 21°C and cold air speed of 0.6 m / s; winding speed of 2980 m / min; and wet heat treatment: relative humidity of 90% and temperature of 90°C. Comparative Example 3

[0055] Bio-based furan polyester with an intrinsic viscosity of 0.52 dl / g was chipped and crystallized and dried in a rotary drum oven at 140°C for 12 hours. The bio-based furan polyester filament was then produced through screw extrusion, metering, cooling, drawing, heat setting, and winding. The main spinning process parameters were: spinning beam temperature of 238°C; first hot roller speed of 1500 m / min and temperature of 110°C; second hot roller speed of 3025 m / min and temperature of 150°C; cold air temperature of 25°C and cold air speed of 1 m / s; winding speed of 2980 m / min; and wet heat treatment: relative humidity of 90% and temperature of 90°C. Comparative Example 4

[0056] Bio-based furan polyester with an intrinsic viscosity of 0.66 dl / g was chipped and crystallized and dried in a rotary drum oven at 140°C for 12 hours. The bio-based furan polyester filament was then produced through screw extrusion, metering, cooling, drawing, heat setting, and winding. The main spinning process parameters were: spinning beam temperature of 262°C; first hot roller speed of 1500 m / min and temperature of 110°C; second hot roller speed of 3025 m / min and temperature of 150°C; cold air temperature of 25°C and cold air speed of 1 m / s; winding speed of 2980 m / min; and wet heat treatment: relative humidity of 90% and temperature of 90°C. Comparative Example 5

[0057] Bio-based furan polyester with an intrinsic viscosity of 0.75 dl / g was chipped and crystallized and dried in a rotary drum oven at 140°C for 12 hours. The filament was then produced through screw extrusion, metering, cooling, drawing, heat setting, and winding. The main spinning parameters were: spinning beam temperature of 270°C; first hot roller speed of 1500 m / min and temperature of 110°C; second hot roller speed of 3025 m / min and temperature of 150°C; cold air temperature of 25°C and cold air speed of 1 m / s; winding speed of 2980 m / min; and wet heat treatment: relative humidity of 90% and temperature of 90°C.

[0058] Figure 1 : is an electron microscope image of the spiral and wavy structures of the polyester filament of the present invention; as an example, Figure 2 and Figure 3 These are the elongation at break test results for the filament products of Example 3 and Example 6, Figure 4 and Figure 5 They are respectively the elongation at break test result diagrams of the filament products of Comparative Examples 3 and 5; Table 1 fully gives the comparison of the physical property test results of the materials prepared in Examples 1 to 7 and Comparative Examples 1 to 5.

[0059]

[0060] from Figure 1 The electron microscope image shows that the following data are compared with those in Table 1:

[0061] 1) The bio-based furan polyester filaments produced in this case by direct spinning exhibit a unique micro-helical morphology and a permanent curled structure after wet heat treatment, which effectively improves crystallization properties and thermal stability;

[0062] 2) Fibers produced by traditional melt spinning have a weak spiral morphology and an unstable curl structure. The melt-spinning viscosity drops significantly and the oligomer content in the fiber is high. The oligomers act as heterogeneous nuclei during the thermal crystallization process of the fiber, increasing the ratio of the crystalline region to the amorphous region of the fiber.

[0063] 3) In this case, the continuous polyester direct spinning method is used to produce bio-based furan polyester filaments, which have higher retained viscosity, fiber breaking strength, elongation at break and shrinkage.

[0064] The above describes the technical solution, working process and implementation effect of the present invention in detail. It should be noted that what is described is only a typical example of the present invention. In addition, the present invention can also have many other specific implementation methods. Any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection required by the present invention.

Claims

1. A self-curling bio-based furan polyester filament, made from bio-based furan polyester as raw material through melt spinning and expansion treatment, characterized by: Calculated by weight, the raw materials for preparing the bio-based furan polyester include: 30-80 parts of 2,5-furandicarboxylic acid 45-200 parts of ethylene glycol 5-8 parts of catalyst 5-8 parts of stabilizer The catalyst is one or more of titanium, germanium, antimony, tin, and zinc metal catalysts, and the addition amount accounts for 5 to 100 ppm of the total amount of the bio-based furan polyester; the stabilizer is triphenyl phosphate, and the addition amount accounts for 10 to 500 ppm of the total amount of the bio-based furan polyester; The self-crimped bio-based furan polyester filament is produced by a direct spinning process, which specifically includes the following steps: Step S21: dissolving 2,5-furandicarboxylic acid in ethylene glycol and stirring to dissolve the mixture to obtain a mixed solution A, wherein the molar ratio of 2,5-furandicarboxylic acid to ethylene glycol is 1:1.6-2.4; adding a catalyst and a stabilizer to the mixed solution A to obtain a mixed solution B; beating the mixed solution B to obtain a mixed solution C; placing the mixed solution C in an esterification kettle for esterification reaction to obtain a mixed solution D; and then sequentially introducing the mixed solution D into a pre-polycondensation kettle and a final polycondensation kettle for polycondensation reaction to obtain a bio-based furan polyester melt; Step S22: Under the action of a booster pump, the bio-based furan polyester melt produced in step S21 is sequentially pressed into a melt filter, a first heat exchanger, a static mixer, and a second heat exchanger through a transmission pipeline for impurity removal and thorough mixing, and then transported to a spinning device for direct spinning. After spinning line metering, extrusion, cooling, drawing and heat setting, and winding, a bio-based furan polyester drawn yarn is produced; Step S23: The bio-based furan polyester drawn yarn obtained in step S22 is subjected to a wet heat treatment at a temperature range of 60 to 100° C. and a relative humidity of 30 to 95%. After the wet heat treatment for 15 to 20 minutes, the helical bio-based furan polyester filament having a permanent curled structure is obtained by drying.

2. The self-crimped bio-based furan polyester filament according to claim 1, characterized in that: In step S21 , the intrinsic viscosity of the bio-based furan polyester melt is 0.4 to 0.8 dl / g.

3. The self-crimped bio-based furan polyester filament according to claim 1, characterized in that: In step S21, the esterification reaction pressure is 12-50 mmHg, the temperature is 210-240° C., and the esterification reaction time is 2-3 hours.

4. The self-crimped bio-based furan polyester filament according to claim 1, characterized in that: In step S21, the pressure of the polycondensation reaction is 0.5-5.0 mmHg, the temperature is 220-260° C., and the polycondensation reaction time is 3.5-5 hours.

5. The self-crimped bio-based furan polyester filament according to claim 1, characterized in that: In step S22, at least one static mixer is provided, and the static mixer is a Kenics static mixer with a vane angle of 90 to 180 degrees or an LPD static mixer with a fork angle of 30 to 90 degrees.

6. The self-crimped bio-based furan polyester filament according to claim 1, characterized in that: In step S22, the direct spinning processing temperature required for the bio-based furan polyester melt is 230-270°C, and the pump pressure is 15-30 MPa.

7. The self-crimped bio-based furan polyester filament according to claim 1, characterized in that: In step S23, the drying time is 1 to 1.5 hours, and the drying temperature is 60 to 120°C.

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