A method for synthesizing a key monomer for polyester spandex

Abstract

The application belongs to the technical field of polymer materials, and particularly relates to a synthesis method of a lactone monomer for polyester spandex. The application uses a 'polycondensation-directional depolymerization' method, uses a suitable polyionic liquid diluent, and realizes the conversion of a series of lactone monomers from cheap and easily available dihydric alcohol and dibasic acid through molecular structure design and process optimization. After the polyionic liquid is added to the depolymerization reaction system, the depolymerization reaction rate is fast, and the byproduct is less. The application breaks through the limitation that only commercially available cyclic monomers such as lactide and caprolactone are available at present, expands the cyclic monomer system and the spandex performance condition space, and has important significance for promoting the upgrading of the green textile industry and widening the application scenarios of high-end functional materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for synthesizing and preparing a lactone-type monomer. Technical Background

[0002] Spandex is a type of elastic fiber with polyurethane as its main structure, widely used in clothing, sportswear, medical textiles, and high-elasticity functional materials. Traditional spandex is mostly composed of polyether-type soft segments, such as polytetrahydrofuran ether glycol, which has good elastic recovery properties and processing stability, but still has certain limitations in terms of chlorine resistance, sustainable sourcing, and subsequent degradation and recycling. As textile materials develop towards high performance, greenness, and low carbon emissions, developing polyester-type spandex materials with polyester polyols as soft segments has become an important technological direction for improving the overall performance of spandex and constructing sustainable elastic fibers.

[0003] Polyester-type spandex typically uses polyester polyols as the source of its soft segment structure. Its molecular chain contains a high proportion of ester bonds, which imparts better oil resistance, solvent resistance, chlorine resistance, mechanical strength, and structural controllability. Especially in applications such as swimwear, sportswear, medical care, outdoor textiles, and high-end functional fabrics, polyester-type spandex has potential performance advantages over traditional polyether-type spandex. However, the structural design of polyester soft segments is highly dependent on the type of polyester monomer and the controllable synthesis capability, particularly the lactone monomers that can be prepared into polyester polyols through ring-opening polymerization. These monomers have a decisive influence on the soft segment structure, molecular weight, crystallization behavior, softness, resilience, and chemical resistance of polyester-type spandex.

[0004] Lactones are important cyclic monomers for preparing aliphatic polyesters via ring-opening polymerization. Compared to the traditional melt polycondensation route of diacids and diols, lactone ring-opening polymerization typically offers milder reaction conditions, greater controllability, and easier adjustment of molecular weight and molecular weight distribution, making it suitable for preparing polyester polyols with well-defined structures and tunable properties. By adjusting the ring size, carbon chain length, side group structure, and proportion of flexible segments of the lactone monomer, the glass transition temperature, crystallinity, hydrophilicity / hydrophobicity, ester bond density, and chain mobility of the polyester soft segments can be further controlled, thus providing a structural basis for the high elasticity, high strength, chlorine resistance, and sustainability of polyester-type spandex.

[0005] However, the types of lactone monomers commonly used in industrial and laboratory applications are currently limited, mainly including a few conventional monomers such as lactide, glycolide, ε-caprolactone, and δ-valerolactone. These monomers have relatively simple structures, making it difficult to meet the requirements of polyester spandex for precise control of the soft segment structure. For example, some conventional polyester soft segments suffer from problems such as strong crystallization tendency, insufficient chain segment flexibility, unsatisfactory elastic recovery, insufficient hydrolysis resistance, or a narrow processing window; while overly flexible structures may lead to decreased mechanical strength and insufficient dimensional stability. Due to the limited range of key lactone monomers, the design space for existing polyester spandex soft segment structures is restricted, hindering the development and large-scale application of high-performance polyester spandex materials.

[0006] Currently, one method for preparing novel lactone monomers involves using difunctional compounds such as glycols, hydroxy acids, and diesters as raw materials. These compounds undergo transesterification or condensation reactions to generate linear oligomers or prepolymers. Then, under catalytic conditions and high temperature and vacuum, the prepolymers undergo intramolecular back-transesterification to close the ring and generate cyclic lactone monomers. The target monomers are then separated through continuous distillation. This method offers advantages such as a wide availability of raw materials, a relatively green route, and suitability for constructing lactone monomers with various ring sizes and chain segment structures. Theoretically, it can be used for the serial development of key soft segment monomers for polyester-type spandex.

[0007] However, in the aforementioned processes, linear oligomer prepolymers typically have high viscosity, which can lead to poor melt flowability, low mass and heat transfer efficiency, and restricted chain segment movement during high-temperature depolymerization and intramolecular cyclization, thereby reducing the efficiency of intramolecular cyclization. Simultaneously, high viscosity systems can also easily cause localized overheating, material carbonization, and an increase in intermolecular transesterification or crosslinking side reactions, affecting the yield and purity of the target lactone monomer. For key lactone monomers used in polyester-type spandex, monomer purity and structural stability directly affect the controllability of subsequent ring-opening polymerization, the molecular weight and terminal hydroxyl stability of the polyester polyol, and ultimately, the spinning stability and mechanical properties of spandex fibers. Therefore, reducing the viscosity of the prepolymer system, improving cyclization efficiency, and minimizing side reactions are crucial issues that urgently need to be addressed in the preparation of high-quality lactone monomers for polyester-type spandex.

[0008] Polyionic liquids are a class of functional polymer materials obtained by polymerizing ionic liquid monomers. They combine the characteristics of ionic liquids, such as low vapor pressure, high thermal stability, and structural designability, with the low migration and recyclability of polymers. Introducing polyionic liquids into the preparation process of lactone monomers is expected to reduce the melt viscosity of polyester prepolymers through ionic interactions, polarity regulation, and chain segment lubrication, thereby improving the mass and heat transfer efficiency of high-temperature depolymerization systems, promoting intramolecular cyclization reactions, and reducing the volatilization, residue, and separation problems associated with traditional small-molecule solvents. This strategy is of great significance for preparing high-purity, high-yield, and structurally tunable key lactone monomers for polyester-type spandex.

[0009] Therefore, developing a green, efficient, and scalable synthesis method for preparing key lactone monomers for polyester-type spandex, by controlling the prepolymer melt viscosity and cyclization reaction process with polyionic liquids, and achieving efficient conversion of inexpensive and readily available raw materials into a series of lactone monomers, is of great value for expanding the design space of soft segment structures in polyester-type spandex, improving the chlorine resistance, mechanical properties and sustainability of spandex, and promoting the industrial application of high-performance bio-based or biodegradable polyester elastic fiber materials. Summary of the Invention

[0010] The problem this invention aims to solve is a large-scale method for directly synthesizing lactones from diols and diacids. It provides a lactone synthesis method that uses diols and diacids as raw materials, and through different combinations, can synthesize a series of lactones, filling a gap in the variety of cyclic monomer systems.

[0011] To solve the above-mentioned technical problems, the technical solution adopted in this invention is to prepare lactones through a process design of "condensation-directional depolymerization".

[0012] This invention provides a class of lactones, as shown in formula (I):

[0013]

[0014] Where n is 1-14 and m is 3-14.

[0015] The specific preparation method of the lactone of formula (I) prepared by the present invention is as follows: a diol and a diacid undergo a polycondensation reaction under the action of a catalyst to obtain a polyester, a diluent is added to depolymerize, and then recrystallization is carried out to obtain the product.

[0016] The reaction equation is as follows:

[0017]

[0018] Where n is 1-14, m is 3-14, and x is the degree of polymerization.

[0019] The polycondensation reaction is preferably carried out under bulk conditions:

[0020] The molar ratio of the diol to the diacid is 1.0-2.0:1, preferably 1.4:1.

[0021] The catalyst may be stannous chloride, stannous octoate, stannous oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, stannous chloride, stannous oxalate, stannous bromide, stannous acetate, butyltin oxide hydroxide, tetraalkyltin, sodium stannate, tetraethyl stannate, tetrabutyl stannate, titanium dioxide, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetratert-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetrabenzyl titanate, etc. Hexyloxy titanium, tetra(2-ethylhexyloxy) titanium, tetraoctyloxy titanium, glycolate titanium, ethylene glycol titanium, titanium oxalate, potassium titanium oxalate, lithium oxalate titanium oxy, oxyacetylacetone titanium, tetraacetylacetone titanium, diisopropanol acetylacetone titanium, ammonium dilactic acid titanium hydroxide, ethyl acetoacetate diisopropanol titanium, triethanolamine isopropanol titanium, polyhydroxystearate titanium, lactate titanium, triethanolamine titanium, tetrabutyl titanate dimer, titanium-magnesium composite catalyst, silica-titanium dioxide composite. Antimony trioxide, antimony glycolate, antimony acetate, antimony pentoxide, sodium antimonate, potassium antimonate, germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, tetraethoxygermanium, tetra-n-butoxygermanium, zirconium oxide, sodium zirconate, tetrabutyl zirconate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, aluminum oxide, aluminum alkoxide, aluminum isopropoxide, aluminum trichloride, sodium aluminate, silicon dioxide, tetraethyl silicate, tetrabutyl silicate, silicotungstic acid, silicotungstate, tungsten trioxide, paratungsten Any one of the following: acid, metatungstic acid, tungstic acid, phosphotungstic acid, phosphotungstate, cobalt formate, cobalt acetate, cobalt stearate, cobalt oxalate, cobalt carbonate, cobalt bromide, cobalt oxide, cobalt hydroxide, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium dimethoxide, magnesium acetate, magnesium chloride, calcium oxide, calcium hydroxide, calcium carbonate, calcium acetate, calcium dimethoxide, zinc oxide, zinc acetate, zinc acetylacetonate, alkyl zinc, dialkyl zinc, zinc dimethoxide, diethyl zinc, and zinc chloride, preferably stannous chloride.

[0022] The total amount of catalyst added is 1-20% of the total mass of the raw materials, preferably 2%.

[0023] The polycondensation reaction temperature is 60-340 °C, preferably 180-230 °C.

[0024] The polycondensation reaction is characterized in that the reaction is carried out under a vacuum of 0.001 MPa to 0.1 MPa, preferably 0.098 MPa.

[0025] The polycondensation reaction time is 3-12 h, preferably 4-6 h.

[0026] The depolymerization reaction temperature is 200-300 °C.

[0027] The depolymerization reaction is characterized in that the reaction occurs at a temperature of 1 × 10⁻⁶. -3 MPa to 1×10 -7 The test is performed under a vacuum of MPa, preferably 1×10 MPa. -6MPa.

[0028] The depolymerization reaction time is 8-24 h, preferably 12 h.

[0029] The diluent may be poly(1-vinyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-pentylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-hexylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-heptylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-octylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-nonylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-dec ... Poly(1-vinyl-3-butylimidazolium bis(fluorosulfonyl)imidazolium), poly(1-vinyl-3-butylimidazolium trifluoromethanesulfonate), poly(1-vinyl-3-butylimidazolium hexafluorophosphate), poly(1-allyl-3-methylimidazolium bis(fluoromethanesulfonyl)imidazolium), poly(1-allyl-3-butylimidazolium bis(fluoromethanesulfonyl)imidazolium), poly(1-hydroxyethyl-3-vinylimidazolium bis(fluoromethanesulfonyl)imidazolium), poly(1-carboxymethyl-3-vinylimidazolium bis(fluoromethanesulfonyl)imidazolium), poly(1-vinyl-2,3-dimethylimidazolium bis(fluoromethanesulfonyl)imidazolium), poly(1-vinyl-2-methyl-3-butylimidazolium bis(fluoromethanesulfonyl)imidazolium), poly(1- Vinyl-3-benzylimidazolium bis(trifluoromethanesulfonyl)imide salt, poly(1-vinyl-3-(2-methoxyethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(3-hydroxypropyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-butylimidazolium bis(perfluoroethanesulfonyl)imide salt), poly(1-vinyl-3-butylimidazolium bis(trifluoromethoxysulfonyl)imide salt), poly(1-vinyl-3-butylimidazolium p-toluenesulfonate), poly(1-vinyl-3-butylimidazolium dodecyl sulfate), poly(1-vinyl-3-butylimidazolium tetrafluoroborate), poly(1-vinyl-3-isopropylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-isobutylimidazolium tetrafluoroborate), poly(1-vinyl-3-isopropylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-isobutylimidazolium tetrafluoroborate), poly(1-vinyl-3-isobutylimidazolium tetrafluoromethanesulfonyl)imide salt, ... Imidazole bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-sec-butylimide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-tert-butylimide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-cyanoethyl)imide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(3-aminopropyl)imide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(4-hydroxybutyl)imide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-chloroethyl)imide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-bromoethyl)imide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-iodoethyl)imide bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-iodoethyl)imide bis(trifluoromethanesulfonyl)imide salt),Poly(1-vinyl-3-(2-phenylethyl)imidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-(3-phenylpropyl)imidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-(4-phenylbutyl)imidazolium bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-ethylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-propylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-pentylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-hexylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly (N-vinyl-N-methylpyrrolidine bis(fluorosulfonyl)imide), poly(N-vinyl-N-butylpyrrolidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-methylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-ethylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-propylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-butylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-methylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-butylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-methylpiperidine trifluoromethanesulfonate), poly(1-vinyl-1-butylpiperidine trifluoromethanesulfonate), poly(N-vinyl-N-methyl ... Alkenyl-N-methylpyrrolidine trifluoromethanesulfonate, poly(N-vinyl-N-butylpyrrolidine trifluoromethanesulfonate), poly(1-vinyl-1-methylpiperidine hexafluorophosphate), poly(1-vinyl-1-butylpiperidine hexafluorophosphate), poly(trimethylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(triethylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(tripropylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(tributylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(tributylmethylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(trimethylvinylphosphonium bis(trifluoromethanesulfonyl)imide), poly(triethylvinylphosphonium bis(trifluoromethanesulfonyl)imide), poly(tripropylvinylphosphonium bis(trifluoromethanesulfonyl)imide), poly(tributyl... Vinylphosphonium bis(trifluoromethanesulfonyl)imide salt, poly(tributylmethylvinylphosphonium bis(trifluoromethanesulfonyl)imide salt), poly(tetravinylammonium bis(trifluoromethanesulfonyl)imide salt, poly(tetravinylphosphonium bis(trifluoromethanesulfonyl)imide salt), poly(trimethylvinylammonium bis(fluorosulfonyl)imide salt), poly(trimethylvinylammonium trifluoromethanesulfonate), poly(tributylvinylphosphonium trifluoromethanesulfonate), poly(trimethylvinylammonium hexafluorophosphate), poly(tributylvinylphosphonium hexafluorophosphate), poly(tris(2-methoxyethyl)vinylammonium bis(trifluoromethanesulfonyl)imide salt), poly(tris(2-hydroxyethyl)vinylammonium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinylpyridine bis(trifluoromethanesulfonyl)imide salt),Poly(1-vinyl-2-methylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-3-methylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-4-methylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-4-butylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-1,2,3-triazole bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-1,2,4-triazole bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-3-methyl-1,2,3-triazole bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-4-methyl-1,2,4-triazole bis(trifluoromethanesulfonyl)imide), Poly(4-vinylmorpholine bis(trifluoromethanesulfonyl)imide The following are all of the following: (salt), poly(4-vinyl-2-methylmorpholine bis(fluorosulfonyl)imide), poly(1-vinylpyridine bis(fluorosulfonyl)imide), poly(1-vinyl-4-methylpyridine bis(fluorosulfonyl)imide), poly(1-vinyl-1,2,3-triazole bis(fluorosulfonyl)imide), poly(4-vinylmorpholine bis(fluorosulfonyl)imide), poly(1-vinylpyridine trifluoromethanesulfonate), poly(1-vinyl-4-methylpyridine trifluoromethanesulfonate), poly(1-vinyl-1,2,3-triazole trifluoromethanesulfonate), poly(4-vinylmorpholine trifluoromethanesulfonate), poly(1-vinyl-3-(2-hydroxyethyl)pyridine bis(fluoromethanesulfonyl)imide).

[0030] Beneficial effects

[0031] (1) Lactones with the structure of formula (I) have not been reported before. They are bio-based, green, and environmentally friendly products with the dual benefits of saving petroleum resources and protecting the environment. They are of great significance to promoting the sustainable development of the polyester industry.

[0032] (2) The raw materials used in this invention are biologically derived diols and dicarboxylic acids, which have the advantages of being inexpensive, readily available, green and non-toxic. A cyclic lactone with the structure of formula (I) can be obtained through simple polycondensation and depolymerization reactions, and can be produced on a large scale using existing chemical equipment.

[0033] (3) After adding polyionic liquid to the depolymerization reaction system, the depolymerization reaction rate is fast and there are few by-products. The diluent contains no highly toxic raw materials or highly corrosive waste. Attached Figure Description

[0034] The embodiments of the present invention will be described in detail with reference to the accompanying drawings, wherein...

[0035] Figure 1 Example 1 (I) of implementation: lactone E24 1 H NMR image

[0036] Figure 2 Example 2 (I) Implementation of lactone E34 1 H NMR image

[0037] Figure 3 Example 3 (I) of implementation: lactone E35 1 H NMR image

[0038] Figure 4 Example 4 (I) of implementation: lactone E45 1 H NMR image

[0039] Figure 5 Example 5 (I) of implementation: lactone E46 1 H NMR image

[0040] Figure 6 Example 6 (I) of implementation: lactone E54 1 H NMR image

[0041] Figure 7 Example 7 (I) of implementation: lactone E56 1 H NMR image

[0042] Figure 8 Example 8 (I) of implementation: lactone E57 1 H NMR image

[0043] Figure 9 Example 9 (I) of implementation: lactone E59 1 H NMR image

[0044] Figure 10 Example 10 (I) Implementation of lactone E510 1 H NMR image

[0045] Figure 11 Example 11 (I) of implementation: lactone E66 1 H NMR image

[0046] Figure 12 Example 12 (I) Implementation of lactone E84 1 H NMR image Detailed Implementation

[0047] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are as follows:

[0048] Unless otherwise specified, all items are available through commercial channels.

[0049] The 1H NMR spectra involved in the examples were measured using a Bruker Ascend TM-400 NMR spectrometer, and the deuterated reagent used was deuterated chloroform (CDCl3).

[0050] Example 1

[0051] (I) Preparation of lactone E24: Ethylene glycol (33.91 g, 0.546 mol, 1.4 eq) and succinic acid (46.08 g, 0.39 mol, 1 eq) totaling 80 g were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120°C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 200 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized with ethanol to obtain lactone E24.

[0052] Example 2

[0053] (I) Preparation of lactone E34: 80 g of 1,3-propanediol (37.94 g, 0.498 mol, 1.4 eq) and succinic acid (42.06 g, 0.356 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 220 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized from ethanol to obtain lactone E34.

[0054] Example 3

[0055] (I) Preparation of lactone E34: 80 g of 1,3-propanediol (37.94 g, 0.498 mol, 1.4 eq) and succinic acid (42.06 g, 0.356 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 220 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized with ethanol to obtain lactone E35.

[0056] Example 4

[0057] (I) Preparation of lactone E45: 80 g of 1,4-butanediol (39.07 g, 0.433 mol, 1.4 eq) and glutaric acid (40.92 g, 0.309 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 230 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized from ethanol to obtain lactone E45.

[0058] Example 5

[0059] (I) Preparation of lactone E46: 80 g of 1,4-butanediol (37.06 g, 0.411 mol, 1.4 eq) and adipic acid (42.93 g, 0.293 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 230 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-pentylimidazolium bis(trifluoromethanesulfonylimide) salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized from ethanol to obtain lactone E46.

[0060] Example 6

[0061] (I) Preparation of lactone E54: 80 g of 1,5-pentanediol (44.2 g, 0.424 mol, 1.4 eq) and succinic acid (35.79 g, 0.303 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the polycondensation product. Poly(1-vinyl-3-hexylimidazolium bis(trifluoromethanesulfonylimide) salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized with ethanol to obtain lactone E54.

[0062] Example 7

[0063] (I) Preparation of lactone E56: 80 g of 1,5-pentanediol (39.95 g, 0.383 mol, 1.4 eq) and adipic acid (40.04 g, 0.274 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-heptylimidazolium bis(trifluoromethanesulfonylimide) salt was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized from ethanol to obtain lactone E56.

[0064] Example 8

[0065] (I) Preparation of lactone E57: 80 g of 1,5-pentanediol (38.12 g, 0.366 mol, 1.4 eq) and pimelic acid (41.84 g, 0.261 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the polycondensation product. Poly(1-vinyl-3-octylimidazolium bis(trifluoromethanesulfonylimide) salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized with ethanol to obtain lactone E57.

[0066] Example 9

[0067] (I) Preparation of lactone E59: 80 g of 1,5-pentanediol (34.92 g, 0.335 mol, 1.4 eq) and azelaic acid (45.07 g, 0.239 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain the polycondensation product. Poly(1-vinyl-3-nonylimidazolium bis(trifluoromethanesulfonyl)imide salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain the crude product. The crude product was then recrystallized with ethanol to obtain lactone E59.

[0068] Example 10

[0069] (I) Preparation of lactone E510: 80 g of 1,5-pentanediol (33.51 g, 0.321 mol, 1.4 eq) and sebacic acid (46.48 g, 0.229 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-decylimidazolium bis(trifluoromethanesulfonylimide) salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized with ethanol to obtain lactone E510.

[0070] Example 11

[0071] (I) Preparation of lactone E66: 80 g of 1,6-hexanediol (42.47 g, 0.359 mol, 1.4 eq) and adipic acid (37.52 g, 0.256 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-butylimidazolium bis(fluorosulfonyl)imide salt) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized from ethanol to obtain lactone E66.

[0072] Example 12

[0073] (I) Preparation of lactone E84: 80 g of 1,8-octanediol (50.73 g, 0.346 mol, 1.4 eq) and succinic acid (29.26 g, 0.247 mol, 1 eq) were added to a 250 mL round-bottom flask. The mixture was heated and stirred, and the vacuum was adjusted to 0.098 MPa. The mixture was dehydrated at 120 °C for 2 h. Stannous chloride (1.6 g, 2 wt%) was added, and the temperature was gradually increased from 180 °C to 250 °C. The reaction was carried out for 4 h to obtain a condensation product. Poly(1-vinyl-3-butylimidazolium trifluoromethanesulfonate) (30 g) was added, and the mixture was distilled under reduced pressure at 270 °C for 12 h to obtain a crude product. The crude product was then recrystallized with ethanol to obtain lactone E84.

Claims

1. A method for synthesizing a lactone monomer for polyester-type spandex: lactone is prepared by a process design of "condensation-directional depolymerization".

2. A lactone, characterized in that... It has a structure as shown in equation (I): Where n is 1-14 and m is 3-14.

3. The specific preparation method of the lactone according to formula (I) in claim 2 is as follows: a diol and a diacid undergo a polycondensation reaction under the action of a catalyst to obtain a polyester, a diluent is added for depolymerization, and then recrystallization is carried out to obtain the product. The reaction equation is as follows: in, n is 1-14, m is 3-14, and x is the degree of polymerization.

4. The polycondensation reaction as described in claim 3 preferably occurs under bulk conditions. The molar ratio of the diol to the diacid is 1.2-1.6:1, preferably 1.4:

1.

5. The catalyst as described in claim 3 may be stannous chloride, stannous octoate, stannous oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, stannous chloride, stannous oxalate, stannous bromide, stannous acetate, butyltin oxide hydroxide, tetraalkyltin, sodium stannate, tetraethyl stannate, tetrabutyl stannate, titanium dioxide, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, tetratert-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, or titanium dioxide. Tetrabenzyl oxalate, tetrahexyloxy titanium, tetra(2-ethylhexyloxy) titanium, tetraoctyloxy titanium, titanium glycolate, titanium glycolate, titanium oxalate, potassium titanium oxalate, lithium oxalate titanium oxide, titanium oxyacetylacetone, titanium tetraacetylacetone, diisopropanol acetylacetone titanium, ammonium dilactic acid titanium hydroxide, ethyl diacetoacetate diisopropanol titanium, triethanolamine isopropanol titanium, titanium polyhydroxystearate, titanium lactate, triethanolamine titanium, titanium tetrabutyl titanate dimer, titanium-magnesium composite catalyst, silicon dioxide titanium dioxide Complex, antimony trioxide, antimony glycolate, antimony acetate, antimony pentoxide, sodium antimonate, potassium antimonate, germanium dioxide, germanium tetroxide, germanium hydroxide, germanium oxalate, tetraethoxy germanium, tetra-n-butoxy germanium, zirconium oxide, sodium zirconate, tetrabutyl zirconate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, aluminum oxide, aluminum alkoxide, aluminum isopropoxide, aluminum trichloride, sodium aluminate, silicon dioxide, tetraethyl silicate, tetrabutyl silicate, silicotungstic acid, silicotungstate, tungsten trioxide, Any one of paratungstic acid, metatungstic acid, tungstic acid, phosphotungstic acid, phosphotungstate, cobalt formate, cobalt acetate, cobalt stearate, cobalt oxalate, cobalt carbonate, cobalt bromide, cobalt oxide, cobalt hydroxide, magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium dimethyl ether, magnesium acetate, magnesium chloride, calcium oxide, calcium hydroxide, calcium carbonate, calcium acetate, calcium dimethyl ether, zinc oxide, zinc acetate, zinc acetylacetonate, alkyl zinc, dialkyl zinc, zinc dimethyl ether, diethyl zinc, and zinc chloride, preferably stannous chloride.

6. The total amount of catalyst added as described in claim 3 is 1-20% of the total mass of the raw materials, preferably 2%.

7. The polycondensation reaction temperature as described in claim 3 is 60-340 °C, preferably 180-230 °C. The reaction is carried out under a vacuum of 0.001 MPa to 0.1 MPa, preferably 0.098 MPa. The reaction time is 3-12 h, preferably 4-6 h.

8. The depolymerization reaction temperature as described in claim 3 is 200-300 °C. The reaction occurs at a temperature of 1 × 10⁻⁶ °C. -3 MPa to 1×10 -7 The test is performed under a vacuum of MPa, preferably 1×10 MPa. -6 MPa. The reaction time is 8-24 h, preferably 12 h.

9. The diluent as described in claim 3 may be poly(1-vinyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-propylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-pentylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-hexylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-heptylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-octylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-nonylimidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-ethyl ... Alkenyl-3-decylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-butylimidazolium bis(fluorosulfonyl)imide salt), poly(1-vinyl-3-butylimidazolium trifluoromethanesulfonate), poly(1-vinyl-3-butylimidazolium hexafluorophosphate), poly(1-allyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-allyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-hydroxyethyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-carboxymethyl-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-2-methyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-2-methyl-3-butylimidazolium bis(trifluoromethanesulfonyl)imide salt), Poly(1-vinyl-3-benzylimidazolium bis(trifluoromethanesulfonylimide), poly(1-vinyl-3-(2-methoxyethyl)imidazolium bis(trifluoromethanesulfonylimide), poly(1-vinyl-3-(3-hydroxypropyl)imidazolium bis(trifluoromethanesulfonylimide), poly(1-vinyl-3-butylimidazolium bis(perfluoroethanesulfonyl)imide), poly(1-vinyl-3-butylimidazolium bis(trifluoromethoxysulfonyl)imide), poly(1-vinyl-3-butylimidazolium p-toluenesulfonate), poly(1-vinyl-3-butylimidazolium dodecyl sulfate), poly(1-vinyl-3-butylimidazolium tetrafluoroborate), poly(1-vinyl-3-isopropylimidazolium bis(trifluoromethanesulfonylimide), poly(1-vinyl-3-isopropylimidazolium bis(trifluoromethanesulfonylimide)), poly(1-vinyl-3-isopropylimidazolium p-toluenesulfonate) Butylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-sec-butylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-tert-butylimidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-cyanoethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(3-aminopropyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(4-hydroxybutyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-chloroethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-bromoethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-iodoethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinyl-3-(2-iodoethyl)imidazolium bis(trifluoromethanesulfonyl)imide salt),Poly(1-vinyl-3-(2-phenylethyl)imidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-(3-phenylpropyl)imidazolium bis(trifluoromethanesulfonyl)imide), poly(1-vinyl-3-(4-phenylbutyl)imidazolium bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-methylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-ethylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-propylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-butylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-pentylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly(N-vinyl-N-hexylpyrrolidine bis(trifluoromethanesulfonyl)imide), poly (N-vinyl-N-methylpyrrolidine bis(fluorosulfonyl)imide), poly(N-vinyl-N-butylpyrrolidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-methylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-ethylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-propylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-butylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-methylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-butylpiperidine bis(fluorosulfonyl)imide), poly(1-vinyl-1-methylpiperidine trifluoromethanesulfonate), poly(1-vinyl-1-butylpiperidine trifluoromethanesulfonate), poly(N-vinyl-N-methyl ... Alkenyl-N-methylpyrrolidine trifluoromethanesulfonate, poly(N-vinyl-N-butylpyrrolidine trifluoromethanesulfonate), poly(1-vinyl-1-methylpiperidine hexafluorophosphate), poly(1-vinyl-1-butylpiperidine hexafluorophosphate), poly(trimethylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(triethylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(tripropylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(tributylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(tributylmethylvinylammonium bis(trifluoromethanesulfonyl)imide), poly(trimethylvinylphosphonium bis(trifluoromethanesulfonyl)imide), poly(triethylvinylphosphonium bis(trifluoromethanesulfonyl)imide), poly(tripropylvinylphosphonium bis(trifluoromethanesulfonyl)imide), poly(tributyl... Vinylphosphonium bis(trifluoromethanesulfonyl)imide salt, poly(tributylmethylvinylphosphonium bis(trifluoromethanesulfonyl)imide salt), poly(tetravinylammonium bis(trifluoromethanesulfonyl)imide salt, poly(tetravinylphosphonium bis(trifluoromethanesulfonyl)imide salt), poly(trimethylvinylammonium bis(fluorosulfonyl)imide salt), poly(trimethylvinylammonium trifluoromethanesulfonate), poly(tributylvinylphosphonium trifluoromethanesulfonate), poly(trimethylvinylammonium hexafluorophosphate), poly(tributylvinylphosphonium hexafluorophosphate), poly(tris(2-methoxyethyl)vinylammonium bis(trifluoromethanesulfonyl)imide salt), poly(tris(2-hydroxyethyl)vinylammonium bis(trifluoromethanesulfonyl)imide salt), poly(1-vinylpyridine bis(trifluoromethanesulfonyl)imide salt),Poly(1-vinyl-2-methylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-3-methylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-4-methylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-4-butylpyridine bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-1,2,3-triazole bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-1,2,4-triazole bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-3-methyl-1,2,3-triazole bis(trifluoromethanesulfonyl)imide), Poly(1-vinyl-4-methyl-1,2,4-triazole bis(trifluoromethanesulfonyl)imide), Poly(4-vinylmorpholine bis(trifluoromethanesulfonyl)imide The following are all of the following: (salt), poly(4-vinyl-2-methylmorpholine bis(fluorosulfonyl)imide), poly(1-vinylpyridine bis(fluorosulfonyl)imide), poly(1-vinyl-4-methylpyridine bis(fluorosulfonyl)imide), poly(1-vinyl-1,2,3-triazole bis(fluorosulfonyl)imide), poly(4-vinylmorpholine bis(fluorosulfonyl)imide), poly(1-vinylpyridine trifluoromethanesulfonate), poly(1-vinyl-4-methylpyridine trifluoromethanesulfonate), poly(1-vinyl-1,2,3-triazole trifluoromethanesulfonate), poly(4-vinylmorpholine trifluoromethanesulfonate), poly(1-vinyl-3-(2-hydroxyethyl)pyridine bis(fluoromethanesulfonyl)imide).

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