A bio-based polyester polyol, a preparation method thereof and application thereof in spandex fibers

Abstract

A kind of bio-based polyester polyol, characterized in that 5-10% mole fraction of 12-carboxymethoxystearic acid is contained in the monomer diacid used, and its preparation method is to prepare diacid and diol composition under catalyst dehydration by heating at 220 DEG C.A kind of bio-based spandex fiber, characterized in that the bio-based polyester polyol, diphenyl methane diisocyanate, chain extender and blocking agent are used as raw materials to prepare by dry spinning.The bio-based polyester polyol of the application can ensure sufficient viscosity of spinning solution when preparing spandex fiber, and the prepared bio-based spandex fiber has good elastic recovery rate and chlorine resistance.

Description

Technical Field

[0001] This invention belongs to the field of chemical materials and relates to a bio-based polyester polyol, its preparation method, and its application in spandex fibers. Background Technology

[0002] Polyols are widely used in various polyurethane products. They react with diisocyanate compounds (such as toluene diisocyanate (TDI), diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), etc.) to prepare spandex fibers, thermoplastic polyurethane (TPU), flexible polyurethane foam, rigid polyurethane foam, coatings, adhesives, and other products. Besides polyether polyols such as polytetrahydrofuran (PTMEG), polypropylene oxide (PPG), and polyethylene oxide (PEG), another major category is polyester polyols. Compared to polyether polyols, polyester polyols have advantages such as oxidation resistance, flexible and designable polymer structures, biodegradability, abundant raw material sources, low cost, and a wide range of applications.

[0003] Existing technology CN20210388149 describes a method for preparing polyols using isophthalic acid, dimer acids, and fatty alcohols, and further preparing polyurethane elastomers; DAICEL's patent US20220089807 describes a method for preparing amide-containing polyester polyols by ring-opening with diamines and cyclocaprolactone, thereby preparing high-strength and durable polyurethane elastomers; STEPAN's patent US20220411567 describes a method for preparing polyols containing imide groups using trimellitic anhydride and amino-containing monohydric alcohols (or acids), or using phthalic anhydride and amino-containing dibasic acids as raw materials, to improve the performance of rigid polyurethane (PU) or polyisocyanate foam materials. (PIR) flame retardant properties; Covestro's patent US20230002552 describes a method for preparing a star-shaped polyester polyol using soybean oil and ethylene glycol, glycerol, ethylene oxide, and phthalic acid as raw materials, and using it to prepare polyurethane foam materials; Huntsman's patent US20240002580 describes a method for preparing aromatic ring-containing hyperbranched polyols using dimethylolpropionic acid or dimethylolbutyric acid, terephthalic acid, ethylene glycol, diethylene glycol, or triethylene glycol as raw materials; Lotte Chemicals (LOTTE) CHEMICAL's patent US20240026060 describes a method for preparing a low-crystallinity polyester polyol using terephthalic acid, isophthalic acid, and neopentyl glycol as raw materials. This polyester polyol, due to its high aromatic ring structure, imparts a high flame-retardant effect to the final polyurethane material. Kuraray uses branched diacids, diols, and a small amount (0.02-3.00% by mass of branched and hydroxyl diacids) as raw materials to prepare a hydrolysis-resistant, low-viscosity polyester polyol, which is then used to prepare polyurethane materials. BASF's patent... US20240059833 discloses a method for preparing a polyester polyol using 1,2-cyclohexanedicarboxylic acid, bio-based 1,5-dimethyloltetrahydrofuran, and THEIC (trihydroxyethyl isocyanurate) as raw materials. This polyester polyol can be used to prepare high-performance polyurethane coatings. Patent US20240124643 discloses a method for preparing a hydrolysis-resistant and yellowing-resistant polyol using adipic acid and butanediol. This preparation method requires the addition of two antioxidants (first a phosphite antioxidant, then antioxidant 1010) and carbodiimide as a hydrolysis-resistant agent during the reaction.EQUUS UK's TOPCO company prepared an acetyl-terminated polyester polyol and mixed it with acrylic-modified epoxy to produce thermoplastic polyester material (TPP) via a Michael addition reaction. 3M's patent US 20210388149 describes a method for preparing polyester polyols using phthalic acid, dimer acid, and aliphatic diols containing dangling conical oxygen, sulfur, and nitrogen (O, S, N) heteroatoms, for use in polyurethane adhesives. US 20220153654 describes a method for preparing bio-based polyester polyols using epoxidized soybean oil and diol ring-opening, and further preparing slow-release fertilizer materials.

[0004] Elastic polyurethane materials (TPU, Thermoplastic Polyurethane) can be prepared by reacting polyols (polyester or polyether polyols) with diisocyanate compounds (TDI, MDI, HDI, or IPDI, etc.). TPU fibers are also called spandex fibers, and are commercially available as Spandex fiber.

[0005] Spandex is a highly elastic fiber that began industrial production in the 1950s. With advancements in production and application technologies, its production and consumption have been strongly boosted, especially in recent years, witnessing rapid growth in both sectors. Spandex is widely used in various elastic fabrics, such as sportswear, fashion apparel, and other thin, elastic fabrics. It is an indispensable special fiber for developing high-end elastic textiles, possessing vast application value and promising development prospects. Spandex fiber exhibits superior elasticity and elastic recovery, with an elastic elongation rate as high as 400%–800%. Even at an elongation of 500%, it still retains an elastic recovery rate of over 95%, a feat unmatched by other fibers.

[0006] The elasticity of spandex fiber comes from the soft and hard segments of the fiber molecular chain. At the microscopic structure of a single spandex macromolecule, the spandex macromolecular chain is a linear block copolymer composed of alternating polyether (soft segments) and urethane, isocyanate, and urea bonds (hard segments); the soft segments are stretchable and are interconnected by the hard segments, and the alternation of soft and hard segments is equivalent to forming a series of small springs (see...). Figure 1 In the aggregate structure of spandex molecules, the hard segments are easily crystallized urethane and urea groups, and the imino and carbonyl groups between the molecular chains can form strong hydrogen bonds. The soft segments can move freely under stress at room temperature, and the intermolecular forces are very weak. After the hard segments are stretched and oriented, they form crystalline entanglements and cross-links, while the soft segments, like springs, can move. This is equivalent to weaving many small springs into a fishing net, which has both elasticity and the ability to be pulled back and contracted using the crystal nodes of the hard segments (e.g., ...). Figure 2 (As shown). The "soft segments" in the spandex molecule mainly come from polyethers, such as poly-(1,4-butanediol) (PTMEG), poly-(1,2-propanediol) (PPG), and even polyethylene glycol, as well as aliphatic polyesters, such as polybutylene succinate (PBS) and polycaprolactone (PCL).

[0007] For example, patents US5962130 and US6096252 describe a method for preparing durable spandex fibers by dry spinning. This method uses polytetramethylene ether (PTMG) with a molecular weight of 2000 as a diol and diisocyanate compounds such as diphenylmethane diisocyanate (MDI) as raw materials to prepare spandex fibers in a DMAc (N,N-dimethylacetamide) solution.

[0008] US Patent 5000899 describes a method for preparing spandex fibers using polytetrahydrofuran or poly-(3-methyltetrahydrofuran) as a diol raw material, with a diamine as the chain extender. The prepared fibers exhibit good thermal creep and heat setting efficiency.

[0009] Patent US6063892 describes a method for preparing spandex fibers using polyethers, such as polytetrahydrofuran, as diol raw materials and bis-(4-isocyanate phenyl)propane or 1,4-bis(4-isocyanate-α,α-dimethylbenzyl)benzene as diisocyanate raw materials.

[0010] Patents US4871818 and US4767828 describe methods for preparing spandex fibers using polyester as a diol. The polyester used is a polyester diol prepared by polycondensation of neopentyl glycol and 1,12-dodecanoic acid, with a molecular weight between 2200 and 2700 and an acid value of less than 5 milliequivalents per kilogram. Both the diol and the diacid used are petrochemical-based. The spandex fibers prepared by dry spinning have good resistance to mildew and chlorine.

[0011] US4504612 describes a method for preparing spandex fibers using PTMEG (polytetrahydrofuran diol) and diisocyanate. By adding 1.0%-1.5% by mass of polyester polyol as an anti-smoke agent, and mixing it with PTMEG, the color fastness and resistance to fading from NO2 smoke can be improved. In this method, the polyester is not used as a raw material for the polymerization reaction; it is only added as an additive after polymerization.

[0012] US Patent 5118780 describes a method for preparing polyester diols from 3-methyl-1,5-pentanediol and fatty acids, and then preparing spandex fibers. All the dicarboxylic acids are azelaic acid to dodecanoic acid, and the molecular weight of the prepared polyester is between 1000 and 3500. The spandex fiber preparation method involves reacting the fibers in a twin-screw extruder followed by a hot-melt spinning process. The resulting spandex fibers exhibit hot water resistance, good low-temperature elastic recovery, and elongation.

[0013] Japanese Patent 101496 / 1973 also describes a method for preparing polyester diol using 3-methyl-1,5-pentanediol, and then melt spinning it to prepare spandex fibers; Japanese Patent 173117 / 1985 describes a method for preparing polyester diol using 1,6-hexanediol and 1,10-decanediol, and then preparing spandex, with the chain extender being a common diamine compound.

[0014] Patent CN202110922180.9 describes a method for preparing functional spandex fibers, which simply involves adding graphene and carbon nanotubes to the polymer raw materials; Patent CN202110925027.1 describes a method for preparing medium-high resilience chlorine-resistant spandex fibers, wherein the added chlorine-resistant stabilizer is 4,11-diamino-1H-naphtho[2,3-F]isoindole-1,3,5,10(2H)-tetraone; Patent CN202110943822.3 describes a high-temperature and alkali-resistant spandex and its preparation method, the main method of which is to introduce 3-methyl-2-butene caffeic acid ester into the polymer monomer; CN202110432982.1 describes a method for preparing spandex by melt spinning, which involves irradiating the melt stream ejected from the spinneret to cause the crosslinking groups introduced in advance in the melt to crosslink. Patent CN201510304961.6 describes a method for preparing a superdispersant and undyed polyurethane elastic fiber, the key point of which is to prepare the superdispersant in advance; Patent CN201610204295.3 describes an easily dyeable polyurethane elastic fiber and its preparation method, the main method of which is to add 4-amino-2,2,6,6-tetramethylpiperidine or 4-hydroxy-2,2,6,6-tetramethylpiperidine to the chain extender.

[0015] Among the polyol raw materials used in the production of spandex fibers, polytetrahydrofuran diol (PTMEG) is the most widely used. This is because, compared to polypropylene oxide diol (PPG), both terminal hydroxyl groups in PTMEG are primary carbon hydroxyl groups, exhibiting less steric hindrance and facilitating its reaction with isocyanate (NCO) functional groups. Compared to polyethylene oxide (PEG), PTMEG has better hydrophobicity and a lower ether bond density, which is beneficial for preparing high-performance spandex fibers. Spandex fibers prepared from PTMEG and diisocyanate compounds have good elongation (often >300%) and moderate tension (too much tension results in a tight feeling when worn; too little tension results in a loose feel). However, spandex fibers prepared using PTMEG have the disadvantage of poor chlorine resistance. When used to make swimwear, their strength and durability decrease in seawater and swimming pool environments (which also involve large amounts of sodium chloride and frequent chlorine bleaching). Spandex fibers prepared using PTMEG also have the disadvantages of being susceptible to mold and non-degradable.

[0016] Using polyester polyol instead of PTMEG in the preparation of spandex fibers can improve the fibers' chlorine and mildew resistance. This is because ester bonds have better chlorine and mildew resistance than ether bonds (US5871818). Simultaneously, spandex fibers prepared using polyester polyols exhibit better post-consumer degradation properties. However, spandex fibers prepared using ordinary polyester polyols often have poorer elastic recovery compared to spandex fibers prepared using PTMEG. This is because polyester polyols have better crystallinity and a higher melting point than PTMEG. Therefore, during the preparation of polyester polyols, it is often necessary to introduce branches into the polyester chain to reduce the crystallinity and melting point of the polyester polyol, thereby improving the elastic recovery rate of the prepared spandex fibers. For example, patents US4767828, US5871818, and US5118780 all use neopentyl glycol or 3-methyl-1,5-pentylene glycol as raw materials.

[0017] The technical problem this invention aims to solve is to address the shortcomings of existing technologies. The commonly used process for preparing spandex fibers using solution polyester and dry spinning involves first reacting a diol compound (PTMEG or polyester diol) with a diisocyanate compound (usually MDI) to produce an isocyanate (NCO)-terminated prepolymer. Then, a diamine compound (such as ethylenediamine, 1,2-propanediamine, etc.) is used for chain extension, followed by prolonged curing at 30-40°C for over 48 hours to produce a polyurethane fiber solution. During chain extension, the strong alkalinity of the diamine compound and the long curing time easily cause hydrolysis of the ester bonds in the polyester diol structure, resulting in a sharp decrease in the viscosity of the polymer solution and affecting spinning performance. To solve this technical problem and improve the hydrolysis resistance of polyester polyols, branches can be introduced into the polyester structure. More and longer branches can shield the ester bonds from the attack of alkaline ions, protecting them from hydrolysis. Summary of the Invention

[0018] The bio-based dicarboxylic acid used in this invention has the structure shown in Formula 1. The polyester polyol prepared using this bio-based dicarboxylic acid has a large number of long branches, which can reduce the crystallinity and melting point of the polyester polyol, and improve the elastic elongation and elastic recovery rate of the prepared spandex fibers. Simultaneously, the long branches can improve the hydrolysis resistance of the polyester, ensure the viscosity stability during the preparation of the polyurethane solution, and improve the spinning performance of the polyurethane solution.

[0019]

[0020] Formula 1. 12-Carboxymethoxystearic acid

[0021] (12-(carboxymethoxy)stearic acid)

[0022] The 12-carboxymethylmethoxystearic acid in Formula 1 can be obtained by condensing 12-hydroxystearic acid with sodium chloroacetate in sodium hydroxide solution, then adjusting the pH to acidic with hydrochloric acid, filtering the white solid, washing the filter cake several times with water, and drying. The reaction formula is shown in Formula 2 below:

[0023]

[0024] Formula 2. Preparation method of 12-carboxymethoxystearic acid

[0025] The diols used in the preparation of polyester polyols in this invention are the same raw materials used in the production of conventional polyester polyols, and can be 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, etc. Preferred diols are 1,4-butanediol, 1,3-propanediol, and 1,6-hexanediol.

[0026] The catalyst used in this invention to prepare bio-based polyester polyols is a titanium-based catalyst, such as tetrabutyl titanate or tetraisopropyl titanate.

[0027] The method for preparing spandex fibers described in this invention is the same as the conventional method for producing spandex fibers using PTMEG as raw material. First, a bio-based polyester polyol is prepolymerized with diphenylmethane diisocyanate (MDI) to obtain an isocyanate (NCO)-terminated prepolymer. Then, N,N-dimethylacetamide (DMAc) is added to dissolve the prepolymer. Next, 1,2-ethylenediamine, a chain extender, is added sequentially to initiate a chain extension reaction. After the reaction is complete, n-butylamine, a terminator, is added to initiate a termination reaction. The mixture is then aged at 40°C for 36 hours until the polymer solution reaches a stable spinning viscosity. Finally, the polymer is spun from a spinneret for dry spinning. The solvent DMAc is then recovered.

[0028] This invention provides a bio-based polyester polyol and its preparation method, as well as spandex fibers prepared from the polyol and their preparation method. The bio-based polyester polyol involved in this invention is obtained by polymerizing a diacid with a diol, wherein the diacid contains at least the following formula ( The structure of the dicarboxylic acid is shown in the diagram; the diol is one or more combinations of 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol.

[0029]

[0030] Mode( 12-Carboxymethylmethoxystearic acid

[0031] The preparation method of the bio-based polyol of the present invention is as follows:

[0032] (1) Add the dicarboxylic acid and diol to the reaction vessel, stir, continuously introduce nitrogen gas, raise the temperature to 220°C, and react for 4-10 hours to carry out polycondensation;

[0033] (2) Add catalyst to the reaction system, continue to purge with nitrogen, and react at 220°C for 2-3 hours;

[0034] (3) Stop the nitrogen gas supply, draw a vacuum at 220℃ with negative pressure (-0.01-0.1Mpa), and cool down and discharge the material after 1 hour of reaction.

[0035] Preferably, the dicarboxylic acid used in step (1) of the preparation method is 1,10-sebacic acid, 1,4-succinic acid, and 12-carboxymethoxystearic acid, and 12-carboxymethoxystearic acid accounts for 5%-10% of the total molar ratio of all dicarboxylic acids.

[0036] Preferably, the diol used in step (1) of the preparation method is one or a combination of 1,3-propanediol, 1,4-butanediol, neopentyl glycol and 1,6-hexanediol.

[0037] Preferably, the ratio of the total number of moles of diol to the total number of moles of diacid used in step (1) of the preparation method is 1.1:1 to 1.02:1.

[0038] Preferably, the catalyst used in step (2) of the preparation method is tetrabutyl titanate or tetraisopropyl titanate, and the amount added is 50-100 ppm of the total weight of the dicarboxylic acid and diol raw materials.

[0039] The preparation method of the bio-based spandex of the present invention comprises the following five steps:

[0040] (1) Prepolymerization: In a reactor, 1 mole of polyester diol is added, and then 2.0-2.02 moles of diisocyanate compound are added while stirring. Prepolymerization is carried out at 80-85°C for 2-3 hours.

[0041] (2) Chain extension: Reduce the reaction system to 40°C, add solvent N,N-dimethylacetamide (DMAc) to the reactor, dissolve the prepolymer in step (1), prepare a 30% concentration solution, then add 1 mole of chain extender to the reactor, and carry out chain extension reaction on the prepolymer prepared in step (1) at 40-45°C for 2-3 hours;

[0042] (3) End capping: Add 0.1-0.15 molar amount of end capping agent to end cap the polymer prepared in step (2) at 40-45℃ for 3 hours;

[0043] (4) Curing: The bio-based polyurethane solution prepared in step (3) is cured by stirring continuously at 37-45°C for 28-36 hours;

[0044] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as dispensing, spraying, stretching, false twisting and oiling to produce spandex fiber.

[0045] Preferably, the polyester diol mentioned in step (1) is the polyester polyol containing 12-carboxymethyl methoxy stearic acid in this invention, and the number-average molecular weight of the polyester polyol is between 1600 and 2200.

[0046] Preferably, the chain extender described in step (2) is 1,5-pentanediamine, or 1,2-ethylenediamine, or 1,2-propanediamine.

[0047] Preferably, the capping agent described in step (3) is furfurylamine or n-butylamine.

[0048] Beneficial effects:

[0049] The bio-based diacid of this invention has a long branched chain structure, and the polyester polyol prepared from it has low crystallinity and melting point, while also exhibiting high hydrolysis resistance. When using the polyester polyol obtained from this bio-based diacid to prepare spandex fibers, no decrease in polymer solution viscosity occurs during the chain extension and curing stages of solution polymerization, ensuring smooth polyurethane solution bonding and dry spinning processes. The spandex fibers prepared using this bio-based polyol exhibit good elongation, elastic recovery, chlorine bleach resistance, and mildew resistance. Attached Figure Description

[0050] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0051] Figure 1 This is a schematic diagram of the "soft segment" and "hard segment" in the molecular chain structure of spandex fiber.

[0052] Figure 2 This is a schematic diagram showing the crystalline entanglement and cross-linking formed after the "hard segments" of the spandex fiber molecular chain are stretched and oriented.

[0053] Figure 3 This is a typical 1H NMR spectrum of the raw material 12-hydroxystearic acid.

[0054] Figure 4 The image shows a typical 1H NMR spectrum of the product 12-(carboxymethoxy)octadecanoic acid. Detailed Implementation

[0055] The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the descriptions in the embodiments are for illustrative purposes only and should not, and will not, limit the invention as detailed in the claims.

[0056] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0057] Determination of hydroxyl value in polyester polyols: HG / T 2709-1995.

[0058] Determination of acid value in polyester polyols: HG / T 2708-1995.

[0059] Method for determining the color of transparent liquids (Gardner colorimetry): GB / T 22295-2008.

[0060] Moisture content: determined by Karl Fischer coulometric method for trace moisture analysis, JJG 1044-2008.

[0061] The synthetic route for preparing 12-(carboxymethoxy)octadecanoic acid using 12-hydroxystearic acid and sodium chloroacetate as raw materials in this invention is as follows:

[0062]

[0063] Example 1:

[0064] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0065] 300 kg of 12-hydroxystearic acid was added to an enamel-lined reactor, heated to 80°C, and stirred until melted. 90 kg of sodium hydroxide was added in batches, followed by 120 kg of sodium chloroacetate. The temperature was raised to 140°C, and the substitution reaction was carried out under high pressure (0.5 MPa) for 12 hours. The reaction system was then cooled to 90°C, and 800 kg of warm water (80°C) was added to the reactor while stirring. The mixture became a transparent colloidal state (the warm water accelerated the dissolution of 2-((12-hydroxyoctadecyloxy)acetic acid). After the warm water was added, 400 kg of 20% hydrochloric acid solution was added to the reactor for acidification, while stirring and cooling to 20°C until stirring was stopped. After standing for 12 hours, the lower layer of the reactor was an aqueous solution, and the upper layer was a white solid product. After draining the lower aqueous solution, the reactor was washed again with 800 kg of deionized water, allowed to stand for further separation, and the wash water was drained. After washing and drying three times, 350 kg of 12-(carboxymethoxy)octadecanoic acid was obtained, with a yield of 97.6%.

[0066] (2) Synthesis of polyester polyol (B-1)

[0067] 112.2 kg of bio-based 1,4-succinic acid (produced by Anhui Huaheng Biotechnology Co., Ltd.), 17.92 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), and 99.2 kg of bio-based 1,4-butanediol (produced by Shandong Yuanli Group) were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 4 hours for prepolymerization. Then, 10 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under nitrogen atmosphere for 2 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa, and the reaction was continued at 220°C for 1 hour. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-1).

[0068] Polyester polyol B-1, with a hydroxyl value of 67.59 mg KOH / g, an acid value of 0.03 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0069] Example 2:

[0070] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0071] 450 kg of 12-hydroxystearic acid was added to an enamel-lined reactor, heated to 80°C, and stirred until melted. 140 kg of sodium hydroxide was added in batches, followed by 185 kg of sodium chloroacetate. The temperature was raised to 140°C, and the substitution reaction was carried out under high pressure (0.5 MPa) for 14 hours. The reaction system was then cooled to 90°C, and 1000 kg of warm water (80°C) was added to the reactor while stirring. The mixture became a transparent colloidal state (the warm water accelerated the dissolution of 2-((12-hydroxyoctadecyloxy)acetic acid). After the warm water was added, 700 kg of 20% hydrochloric acid solution was added to the reactor for acidification, while stirring and cooling to 20°C until stirring was stopped. After standing for 12 hours, the lower layer of the reactor was an aqueous solution, and the upper layer was a white solid product. After draining the lower aqueous solution, the reactor was washed again with 900 kg of deionized water, allowed to stand for further separation, and the wash water was drained. After washing and drying three times, 528 kg of 12-(carboxymethoxy)octadecanoic acid was obtained, with a yield of 98.2%.

[0072] (2) Synthesis of polyester polyol (B-2)

[0073] 1062.9 kg of bio-based 1,4-succinic acid (produced by Anhui Huaheng Biotechnology Co., Ltd.), 358.4 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 395.7 kg of bio-based 1,3-propanediol (produced by Anhui Huaheng Biotechnology Co., Ltd.), and 450.6 kg of 1,4-butanediol (produced by Shandong Yuanli Group) were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 6 hours for prepolymerization. Then, 70 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa. The reaction was continued at 220°C for 2 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-2).

[0074] Polyester polyol B-2, with a hydroxyl value of 51.0 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0075] Example 3:

[0076] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0077] The experimental method is the same as step (1) in Example 2.

[0078] (2) Synthesis of polyester polyol (B-3)

[0079] 190.1 kg of bio-based 1,10-sebacic acid (produced by Yihai Kerry Corporation), 21.5 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 38.1 kg of bio-based 1,3-propanediol (produced by Anhui Huaheng Biotechnology), and 45.15 kg of 1,4-butanediol (produced by Shandong Yuanli Group) were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 8 hours for prepolymerization. Then, 13.5 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 4 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.02 MPa. The reaction was continued at 220°C for 2 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-3).

[0080] Polyester polyol B-3, with a hydroxyl value of 62.0 mg KOH / g, an acid value of 0.03 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0081] Example 4:

[0082] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0083] The experimental method is the same as step (1) in Example 2.

[0084] (2) Synthesis of polyester polyol (B-4)

[0085] 910.1 kg of 1,10-sebacic acid (produced by Yihai Kerry Corporation), 179.15 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 247.3 kg of bio-based 1,3-propanediol (produced by Anhui Huaheng Biotechnology), and 180.2 kg of 1,4-butanediol (produced by Shandong Yuanli Group) were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 8 hours of prepolymerization. Then, 160 g of tetraisopropyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 5 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.005 MPa, and the reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-4).

[0086] Polyester polyol B-4, with a hydroxyl value of 60.3 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0087] Example 5:

[0088] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0089] The experimental method is the same as step (1) in Example 2.

[0090] (2) Synthesis of polyester polyol (B-5)

[0091] 186.1 kg of 1,10-sebacic acid (produced by Yihai Kerry Corporation), 28.7 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 46.0 kg of bio-based 1,3-propanediol (produced by Anhui Huaheng Biotechnology), and 41.7 kg of neopentyl glycol (produced by LG Chem) were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 7 hours for prepolymerization. Then, 20 g of tetraisopropyl titanate was added to the system, and the reaction was continued at 220°C under nitrogen atmosphere for 3.5 hours. Then, nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa, and the reaction was continued at 220°C for 2.5 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-5).

[0092] Polyester polyol B-5, with a hydroxyl value of 59.0 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0093] Example 6:

[0094] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0095] The experimental method is the same as step (1) in Example 2.

[0096] (2) Synthesis of polyester polyol (B-6)

[0097] 106.3 kg of 1,4-succinic acid, 35.8 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 61.0 kg of 1,3-propanediol, and 20.8 kg of neopentyl glycol were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 5 hours of prepolymerization. Then, 30 g of tetraisopropyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 4 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa. The reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-6).

[0098] Polyester polyol B-6, with a hydroxyl value of 65.2 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <20 Gardner, and a moisture content of <0.005%.

[0099] Example 7:

[0100] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0101] The experimental method is the same as step (1) in Example 2.

[0102] (2) Synthesis of polyester polyol (B-7)

[0103] 202.2 kg of 1,4-succinic acid, 627.0 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 76.1 kg of 1,3-propanediol, and 125.0 kg of 1,6-hexanediol were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 5 hours of prepolymerization. Then, 110 g of tetraisopropyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 4 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa, and the reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-7).

[0104] Polyester polyol B-7, with a hydroxyl value of 66.0 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <20 Gardner, and a moisture content of <0.005%.

[0105] Example 8:

[0106] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0107] The experimental method is the same as step (1) in Example 2.

[0108] (2) Synthesis of polyester polyol (B-8)

[0109] 111.0 kg of 1,4-succinic acid, 21.5 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 38.4 kg of 1,3-propanediol, and 59.1 kg of 1,6-hexanediol were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 6 hours of prepolymerization. Subsequently, 50 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa, and the reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-8).

[0110] Polyester polyol B-8, with a hydroxyl value of 56.1 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <20 Gardner, and a moisture content of <0.005%.

[0111] Example 9:

[0112] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0113] The experimental method is the same as step (1) in Example 2.

[0114] (2) Synthesis of polyester polyol (B-9)

[0115] 106.3 kg of succinic acid, 35.8 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 61.5 kg of 1,3-propanediol, and 23.6 kg of 1,6-hexanediol were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 6 hours of prepolymerization. Then, 30 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa, and the reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-9).

[0116] Polyester polyol B-9, with a hydroxyl value of 64.9 mg KOH / g, an acid value of 0.02 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.007%.

[0117] Example 10:

[0118] (1) Synthesis of 12-(carboxymethoxy)octadecanoic acid

[0119] The experimental method is the same as step (1) in Example 2.

[0120] (2) Synthesis of polyester polyol (B-10)

[0121] 106.3 kg of succinic acid, 35.8 kg of 12-(carboxymethoxy)octadecanoic acid (prepared in step 1 of this example), 45.4 kg of 1,4-butanediol, and 38.4 kg of 1,3-propanediol were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 6 hours of prepolymerization. Then, 30 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa, and the reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (denoted as B-10).

[0122] Polyester polyol B-10 has a hydroxyl value of 64.9 mg KOH / g, an acid value of 0.02 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.007%.

[0123] The bio-based spandex in this invention is produced by solution prepolymerization, chain extension, end-capping, and then dry spinning. Specific production parameters for the bio-based spandex are shown in Examples 11 to 20 of Tables 1 and 2.

[0124] Example 11: Preparation of Bio-based Spandex

[0125] (1) Prepolymerization: 180 kg of bio-based polyester polyol (polyester polyol B-1 prepared in Example 1) was added to the reactor, the temperature was raised to 80°C, and 54.5 kg of diphenylmethane diisocyanate (produced by BASF Chemical) was added while stirring. The prepolymerization reaction was carried out at 80°C for 2 hours to obtain isocyanate-terminated prepolymer.

[0126] (2) Chain extension: 615 kg of N,N-dimethylacetamide (DMAc) was added to the reactor and stirred to dissolve the isocyanate-terminated prepolymer obtained in step (1). Then, 1.8 kg of pentanediamine (produced by Shanghai Kaisai Biotechnology) was added to extend the chain of the isocyanate-terminated prepolymer prepared in step (1). The chain extension reaction was carried out at 40°C for 2 hours to obtain the extended polymer.

[0127] (3) End-capping: Add 0.15 kg of the end-capping agent furfural (produced by Sinopharm Group) to end-cap the chain extended polymer prepared in step (2). The end-capping reaction is carried out at 40°C for 2 hours to obtain a bio-based polyurethane solution.

[0128] (4) Curing: The bio-based polyurethane solution prepared in step (3) was continuously stirred at 45°C for 28 hours to cure. The stirring speed was 6 rpm. After 20 hours of curing, the viscosity of the system was measured to be 3600 poise, and the spinning solution was finally obtained.

[0129] (5) Spinning: The spinning solution prepared in step (4) is spun through operations such as dispensing, spraying, stretching, false twisting and oiling to produce bio-based spandex, which is numbered 1#.

[0130] Examples 12-15:

[0131] The experimental method is the same as in Example 11, except that the experimental parameters are adjusted. The specific adjustments to the experimental parameters are shown in Table 1.

[0132] Table 1. Examples 11-15 of Bio-based Spandex Production

[0133] spandex number 1# 2# 3# 4# 5# Bio-based polyester polyols B-1 B-2 B-3 B-4 B-5 The molar ratio of isocyanate groups in MDI to hydroxyl groups in bio-based polyester polyols 2.00 2.01 2.02 2.00 2.02 Prepolymerization temperature / °C 80 85 85 84 80 Prepolymerization time / h 2.0 2.3 2.5 3.0 3.0 Chain extender Pentylene diamine ethylenediamine 1,2-Propanediamine ethylenediamine ethylenediamine Chain extension temperature / ℃ 40 45 40 40 45 Chain extension time / h 2 3 3 3 2 End capping agent furfurylamine furfurylamine furfurylamine furfurylamine n-Butylamine Molar ratio of capping agent to bio-based polyester polyol 0.1 0.1 0.15 0.12 0.14 maturation time / h 28 30 28 30 30 Spinning solution viscosity / poise 3600 4000 3700 3800 4900

[0134] Examples 16-20:

[0135] The experimental method is the same as in Example 11, except that the experimental parameters are adjusted. The specific adjustments to the experimental parameters are shown in Table 2.

[0136] Table 2 Examples 16-20 of Bio-based Spandex Production

[0137] spandex number 6# 7# 8# 9# 10# Bio-based polyester polyols B-6 B-7 B-8 B-9 B-10 The molar ratio of isocyanate groups in MDI to hydroxyl groups in bio-based polyester polyols 2.02 2.01 2.0 2.02 2.02 Prepolymerization temperature / °C 85 85 85 84 80 Prepolymerization time / h 2.0 2.3 2.5 3.0 3.0 Chain extender Pentylene diamine Pentylene diamine Pentylene diamine 1,2-Propanediamine ethylenediamine Chain extension temperature / ℃ 40 45 40 40 45 Chain extension time / h 2 3 3 3 2 End capping agent furfurylamine furfurylamine furfurylamine n-Butylamine n-Butylamine Molar ratio of capping agent to bio-based polyester polyol 0.12 0.11 0.15 0.12 0.14 maturation time / h 30 30 36 36 34 Spinning solution viscosity / poise 4500 5500 5000 4500 5600

[0138] Adipic acid, succinic acid, and sebacic acid, along with hexanediol, butanediol, propylene glycol, and neopentyl glycol, were selected to prepare polyester polyols. The preparation experiments are shown in Comparative Examples 1 to 5. The polyols prepared in Comparative Examples 1 to 5 were polymerized, the viscosity of the spinning solution was measured, and spandex spinning was performed. The results are shown in Comparative Examples 6 to 10 in Table 3.

[0139] Comparative Example 1: Synthesis of Polyester Polyol (D-1)

[0140] 106.3 kg of succinic acid, 20.2 kg of 1,10-sebacic acid, 61.5 kg of 1,3-propanediol, and 23.6 kg of 1,6-hexanediol were added to a reactor. Nitrogen gas was introduced and the mixture was heated until the raw materials melted. The temperature was then increased to 220°C while stirring, and nitrogen gas was continuously introduced for a prepolymerization reaction for 6 hours. Subsequently, 10 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, nitrogen gas was stopped, and a vacuum was drawn while stirring, reducing the pressure to -0.01 MPa. The reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (D-1).

[0141] Polyester polyol D-1, with a hydroxyl value of 65.1 mg KOH / g, an acid value of 0.02 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.007%.

[0142] Comparative Example 2: Synthesis of Polyester Polyol (D-2)

[0143] 1062.9 kg of bio-based 1,4-succinic acid (produced by Anhui Huaheng Biotechnology Co., Ltd.), 202.1 kg of 1,10-sebacic acid, 395.7 kg of bio-based 1,3-propanediol (produced by Anhui Huaheng Biotechnology Co., Ltd.), and 450.6 kg of 1,4-butanediol (produced by Shandong Yuanli Group) were added to the reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for 6 hours of prepolymerization. Subsequently, 70 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa. The reaction was continued at 220°C for 2 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (D-2).

[0144] Polyester polyol D-2, with a hydroxyl value of 51.0 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0145] Comparative Example 3: Synthesis of Polyester Polyol (D-3)

[0146] 106.3 kg of 1,4-succinic acid, 146.1 kg of 1,6-adipic acid, 61.0 kg of 1,3-propanediol, and 20.8 kg of neopentyl glycol were added to a reactor. Nitrogen gas was introduced and the mixture was heated until the raw materials melted. The temperature was then increased to 220°C while stirring, and nitrogen gas was continuously introduced for a prepolymerization reaction for 5 hours. Subsequently, 30 g of tetraisopropyl titanate was added to the system, and the reaction continued at 220°C under a nitrogen atmosphere for 4 hours. Then, nitrogen gas was stopped, and a vacuum was drawn while stirring, reducing the pressure to -0.01 MPa. The reaction continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (D-3).

[0147] Polyester polyol D-3, with a hydroxyl value of 65.2 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <20 Gardner, and a moisture content of <0.005%.

[0148] Comparative Example 4: Synthesis of Polyester Polyol (D-4)

[0149] 146.1 kg of 1,6-adipic acid, 38.2 kg of 1,3-propanediol, and 59.1 kg of 1,6-hexanediol were added to a reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for prepolymerization for 6 hours. Subsequently, 30 g of tetrabutyl titanate was added to the system, and the reaction was continued at 220°C under a nitrogen atmosphere for 3 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa. The reaction was continued at 220°C for 3 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (D-4).

[0150] Polyester polyol D-4, with a hydroxyl value of 56.1 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <20 Gardner, and a moisture content of <0.005%.

[0151] Comparative Example 5: Synthesis of Polyester Polyol (D-5)

[0152] 146.1 kg of 1,6-adipic acid, 118.0 kg of 1,4-succinic acid, 87.5 kg of bio-based 1,3-propanediol (produced by Anhui Huaheng Biotechnology), and 104.2 kg of neopentyl glycol (produced by LG Chem) were added to a reactor. Nitrogen gas was introduced and the temperature was raised. After the raw materials melted, the temperature was raised to 220°C while stirring, and nitrogen gas was continuously introduced for prepolymerization for 7 hours. Subsequently, 40 g of tetraisopropyl titanate was added to the system, and the reaction continued at 220°C under a nitrogen atmosphere for 3.5 hours. Then, the nitrogen gas was stopped, and a vacuum was drawn while stirring, with the negative pressure reduced to -0.01 MPa. The reaction continued at 220°C for 2.5 hours. After the reaction was completed, the temperature was lowered to 60°C and the product was discharged to obtain polyester polyol (D-5).

[0153] Polyester polyol D-5, with a hydroxyl value of 58.7 mg KOH / g, an acid value of 0.04 mg KOH / g, a color of <30 Gardner, and a moisture content of <0.01%.

[0154] Comparative Examples 6 to 10:

[0155] The experimental method was the same as in Example 11, except that the experimental parameters were adjusted and the polyester polyols produced by Comparative Examples 1 to 5 were used as raw materials. The specific adjustments to the experimental parameters are shown in Table 3.

[0156] Table 3 Comparative Examples 6 to 10 of Bio-based Spandex Production

[0157] spandex number D1# D2# D3# D4# D5# Bio-based polyester polyols D-1 D-2 D-3 D-4 D-5 The molar ratio of isocyanate groups in MDI to hydroxyl groups in bio-based polyester polyols 2.02 2.01 2.00 2.02 2.02 Prepolymerization temperature / °C 85 85 85 84 80 Prepolymerization time / h 2.0 2.3 2.5 3.0 3.0 Chain extender Pentylene diamine Pentylene diamine Pentylene diamine 1,2-Propanediamine ethylenediamine Chain extension temperature / ℃ 40 45 40 40 45 Chain extension time / h 2 3 3 3 2 End capping agent furfurylamine furfurylamine furfurylamine n-Butylamine n-Butylamine Molar ratio of capping agent to bio-based polyester polyol 0.12 0.11 0.15 0.12 0.14 maturation time / h 30 30 36 36 34 Spinning solution viscosity / poise 2300 2500 3000 2700 2800

[0158] As can be seen from the data in Tables 1, 2 and 3, the viscosity of the spinning solution in Comparative Examples 6 to 10 is significantly lower than that in Examples 11 to 20. This is because the polyester polyols used in Examples 11 to 20 contain a polymer monomer 12-(carboxymethoxy)octadecanoic acid monomer with a long side group. The long-chain side group in its molecular structure has a good shielding effect on the ester group in the polyester polyol, which improves the resistance of the polyester polyol to alkaline environment during chain extension and end capping.

[0159] Example 21: Fiber Performance Testing

[0160] The bio-based spandex fiber samples prepared in Examples 11-20 and Comparative Examples 6-10 were tested according to standards FZ / T 50006-2013 (Test Method for Tensile Properties of Spandex Fibers) and FZ / T 50007-2012 (Test Method for Elasticity of Spandex Yarns). The relevant results are shown in Table 4.

[0161] Table 4 Mechanical properties of spandex fiber

[0162] 1# 15D 66.4 400 15.5 99.1 98.5 2# 15D 64.3 410 16.2 99.2 99.2 3# 70D 134.1 430 45.3 99.1 98.2 4# 70D 120.5 422 35.5 99.4 99.2 5# 40D 82.1 416 17.6 99.4 98.2 6# 40D 82.1 415 17.6 99.2 98.4 7# 40D 85.5 422 18.9 99.1 98.4 8# 70D 132.4 415 29.5 99.2 97.8 9# 70D 140.5 425 28.8 99.1 98.1 10# 70D 137.5 408 28.5 76 65.0 D1# 15D 58.2 400 15.4 80.4 64.2 D2# 15D 57.5 410 14.2 78.5 72.2 D3# 40D 87.4 410 32.5 80.1 64.5 D4# 70D 136.2 380 28.5 78.5 64.2 D5# 70D 135.4 391 27.5 80.2 65.5

[0163] Note: In Table 4, TEN is breaking strength; ELO (%) is elongation at break; elongation recovery rate 1 refers to the degree to which a 40cm long fiber returns to its original length after being stretched to 200% elongation, fixed for 30 seconds, and then released; elongation recovery rate 2 refers to the degree to which a 40cm long fiber returns to its original length after being stretched to 300% elongation, fixed for 30 seconds, and then released.

[0164] As shown in Table 4 above, the bio-based spandex fibers prepared by this invention not only have good tensile elongation (>400%), but also high breaking strength. Compared with spandex fibers prepared using ordinary polyester polyols, the spandex fibers of this invention have longer branches in their structure, more amorphous regions, and lower melting points. Therefore, the elastic recovery rates of the prepared spandex fibers are all higher (>98%). In contrast, the molecular chains in the amorphous regions of ordinary polyester fibers are more regular, and they are prone to permanent elastic deformation after fiber stretching, resulting in lower elastic recovery rates.

[0165] Example 22: Chlorine Resistance Test of Fibers

[0166] The chlorine resistance of spandex fibers was tested according to Chinese standard FZ / T 50034-2016 (Test Method for Chlorine Resistance of Spandex Filament). Polyether-based spandex fibers were purchased from the market and compared with the spandex fibers in the examples and comparative examples. The experimental results are shown in Table 5 below.

[0167] Table 5 Evaluation of Chlorine Resistance of Spandex Fiber

[0168] 1# 15D 88.4 3# 70D 89.4 5# 40D 90.1 7# 40D 89.2 D1# 15D 83.7 D3# 40D 82.4 D5# 70D 83.4 Polyether-based spandex fiber (a commercially available product manufactured by Jiangsu Shuangliang Company) 15D 65.4 Polyether-based spandex fiber (a commercially available product manufactured by Jiangsu Shuangliang Company) 40D 66.7 Polyether-based spandex fiber (a commercially available product manufactured by Jiangsu Shuangliang Company) 70D 67.5

[0169] As shown in Table 5, the spandex fibers prepared using the polyester polyol of this invention exhibit better chlorine resistance and higher strength retention than commercially available polyether-based spandex fibers. This is because ester bonds have better oxidation resistance than ether bonds, thus the spandex fibers prepared by this invention have better chlorine resistance. Furthermore, the spandex fibers in Examples 1, 3, 5, and 7 of this invention exhibit better chlorine resistance than the D1#, D2#, and D3# spandex fibers in the comparative examples. This is because the longer branches in the polyester polyol of this invention shield the ester bonds, reducing the attack of chlorine on the ester bonds, thus resulting in a higher strength retention.

[0170] This invention provides a bio-based polyester polyol, its preparation method, and its application in spandex fibers. Many methods and approaches exist to achieve this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A bio-based polyester polyol, characterized in that... Its structure contains 12-carboxymethoxystearic acid.

2. The 12-carboxymethoxystearic acid as described in claim 1, wherein the structural formula is ( As shown in the image: （ ）。 3. The preparation method of the bio-based polyester polyol as described in claim 1 comprises the following three steps: S1.

1. Add the diacid and diol to the reactor, stir, continuously introduce nitrogen gas, raise the temperature to 220°C, and react for 4-10 hours to carry out polycondensation; S1.

2. Add catalyst to the reaction system, continue to purge with nitrogen, and react at 220°C for 2-3 hours; S1.

3. Stop the nitrogen supply, evacuate at 220℃ under negative pressure (-0.01-0.1Mpa), and cool down and discharge the material after 1 hour of reaction.

4. The dicarboxylic acid described in S1.1 of claim 3 is 1,10-sebacic acid, 1,4-succinic acid, and 12-carboxymethoxystearic acid, wherein 12-carboxymethoxystearic acid accounts for 5%-10% of the total molar ratio of the dicarboxylic acids; the diol is one or a combination of 1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,6-hexanediol.

5. The ratio of the total number of moles of the diol to the total number of moles of the diacid as described in S1.1 of claim 3 is 1.1:1 to 1.02:

1.

6. The catalyst described in S1.2 of claim 3 is tetrabutyl titanate or tetraisopropyl titanate, and its addition amount is 50-100 ppm of the total weight of the dicarboxylic acid and diol raw materials.

7. A bio-based spandex fiber, characterized in that... The polyester polyol used contains 12-carboxymethyl methoxy stearic acid, and the number-average molecular weight of the polyester polyol is between 1600 and 2200.

8. The bio-based spandex fiber as described in claim 7, wherein its preparation method comprises the following five steps: S2.

1. Prepolymerization: In a reactor, 1 mole of polyester diol is added, followed by 2.0-2.02 moles of diisocyanate compound while stirring. Prepolymerization is carried out at 80-85°C for 2-3 hours. S2.

2. Chain extension: Lower the reaction system to 40°C, add solvent N,N-dimethylacetamide (DMAc) to the reactor to dissolve the prepolymer in step S2.

1. and prepare a 30% concentration solution. Then add 1 mole of chain extender to the reactor to carry out the chain extension reaction of the prepolymer prepared in step S2.

1. Chain extension is carried out at 40-45°C for 2-3 hours. S2.

3. End-capping: Add 0.1-0.15 molar amounts of end-capping agent to end-cap the polymer prepared in step S2.

2. End-capping at 40-45°C for 3 hours; S2.

4. Curing: The bio-based polyurethane solution prepared in step S2.3 is cured by stirring continuously at 37-45℃ for 28-36 hours; S2.

5. Spinning: The spinning solution prepared in step S2.4 is spun through operations such as dispensing, spraying, stretching, false twisting and oiling to produce spandex fibers.

9. Step S2.1 of claim 8. The polyester diol contains 12-carboxymethyl methoxy stearic acid in its molecular structure, and the number-average molecular weight of the polyester polyol is between 1600 and 2200.

10. The chain extender in step S2.2 of claim 8 is 1,5-pentanediamine, or 1,2-ethylenediamine, or 1,2-propanediamine.

11. The capping agent in step S2.3 of claim 8 is furfurylamine or n-butylamine.

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