A method for preparing a polyether ester polyol and its product

Abstract

The present invention provides a method for preparing polyether ester polyol and its products. In this method, polyether diol and polyester are added as raw materials into a reaction kettle, the reaction kettle is heated to the reaction temperature for transesterification reaction, and the small molecule polyol produced by the transesterification reaction is distilled out by vacuum distillation, thereby preparing polyether ester polyol. Among them, the polyester contains an aromatic dicarboxylic acid polyol ester structure, the polymerization degree of the polyether diol is 2 - 20, the molecular weight is 100 - 1000, the molar ratio of the aromatic group structure in the polyether diol and polyester is greater than 1.05:1, the reaction temperature is above the boiling point of the small molecule polyol and below the boiling point of the polyether diol. The method provided by the present invention can directly process recycled polyester into polyether ester polyol suitable for the production of polyurethane elastic fibers, simplifies the production process of polyether ester polyol suitable for the production of spandex, and while utilizing recycled resources, also broadens the raw material sources of polyurethane elastic fibers.

Description

Technical Field

[0001] The present invention relates to the field of methods for preparing polymers, and particularly to a method for preparing polyether ester polyols and products thereof. Background Art

[0002] Polyester is a type of engineering material with excellent properties and wide applications. In particular, polyesters with benzene rings in their structures such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PPT), and polybutylene terephthalate (PBT) are particularly common. They can be used as fibers, bottles, films, or other plastic products and are indispensable plastic varieties in people's daily lives. With the increasingly widespread use of polyester plastic products, the environmental problems brought about by non-degradable polyester plastics have attracted more and more attention from people. Plastic recycling is an effective means to solve environmental problems. Currently, the main method for recycling polyester plastics is to remelt and pelletize plastic bottle flakes as recycled materials and then remanufacture them into plastic products after further processing. However, this method has high requirements for the quality of the recycled plastic bottle flakes, requiring less impurities, small color differences, and small molecular weight differences. Many plastic wastes that do not meet the above standards are difficult to recycle and reuse. In addition to recycling and pelletizing, there is also a method of decomposing recycled polyester plastics into terephthalic acid (PTA) or dimethyl terephthalate (DMT) by chemical methods after removing impurities and then reusing them as chemical raw materials. However, this method has a complex process, and it is difficult to guarantee the purity of the obtained products, and the uses of the recycled products are limited.

[0003] Spandex is short for polyurethane elastic fiber and is currently the most widely used elastic fiber. Spandex is a block copolymer of soft segments and hard segments. The soft segments are generally composed of flexible chain segments, which are generally obtained by the reaction of polyols such as polyethers, polyesters, hydroxyl-terminated polybutadiene, and polyisocyanates used to connect the polyols; the hard segments are composed of chain segments with excellent crystallization properties, which are generally obtained by the reaction of polyisocyanates with small molecule polyols and small molecule amine chain extenders. The mainstream spandex in the market is dry-process polyether-based spandex. The main raw materials of dry-process polyether-based spandex are polytetrahydrofuran ether diol, diphenylmethane diisocyanate, and chain-extending amines. A polyurethane urea solution is prepared through a two-step polymerization reaction, and then necessary additives are added to prepare a polyurethane urea spinning dope, and spandex fibers are obtained through spinneret spinning. This method uses polytetrahydrofuran ether diol as the soft chain segment, and the obtained spandex fibers have relatively balanced properties, usually having a high elastic elongation rate, and its tensile modulus can basically meet the requirements of daily clothing. However, the cost is relatively high, and this method cannot use recycled materials.

[0004] In the long-term research, the inventors found that using polyether ester polyols with aromatic group-polyether segments as the soft segments of spandex can also produce spandex with high elongation and high elastic recovery rate. Adding a small amount of small molecule diol structure to the segment structure of the above polyether ester polyols can adjust the elastic modulus and elastic recovery rate of spandex. Moreover, the structure of this polyether ester polyol is similar to that of common polyesters, which provides the possibility of using recycled polyester as the raw material for spandex. Generally speaking, the preparation idea of this kind of polyether ester polyol is to react dicarboxylic acid with aromatic group and polyether diol. However, the process of preparing terephthalic acid from recycled polyester is complex, energy-consuming, and difficult to purify. Therefore, the present invention attempts to provide a method for preparing polyether ester polyols suitable for producing spandex from recycled polyester, in order to simplify the production process of this polyether ester polyol. Summary of the Invention

[0005] To solve the above problems, the present invention provides a method for preparing polyether ester polyols suitable for producing spandex using polyester as the raw material, the polyether ester polyols prepared by this method, and polyurethane elastic fibers, non-woven fabrics, films and elastomers prepared using this polyether ester polyols and their methods. The specific solutions are as follows:

[0006] A method for preparing polyether ester polyols, characterized by comprising the following steps:

[0007] Step 1) Add polyether diol and polyester as raw materials to a reaction kettle, wherein the polyester contains an aromatic dicarboxylic acid polyol ester structure, the degree of polymerization of the polyether diol is 2-20, the molecular weight is 100-1000, and the molar ratio of the aromatic groups in the polyether diol and polyester is greater than 1.05:1;

[0008] Step 2) Heat the reaction kettle to the reaction temperature for transesterification reaction, and use vacuum distillation to distill out the small molecule polyols produced by the transesterification reaction to prepare polyether ester polyols, wherein the reaction temperature is above the boiling point of the small molecule polyols and below the boiling point of the polyether diol.

[0009] In the above method, the aromatic dicarboxylic acid polyol ester structure refers to the ester structure formed by aromatic dicarboxylic acid and polyol in the polyester. Among them, the aromatic includes aromatic ring structure and heteroaromatic ring structure. The aromatic ring can be at least one of aromatic rings such as benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, etc.; the heteroaromatic ring can be at least one of pyridine, furan ring, thiazole ring, pyrimidine ring, etc. Specifically, the aromatic dicarboxylic acid can be one or more of terephthalic acid, phthalic acid, isophthalic acid, biphenyl dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 2,6-naphthalene dicarboxylic acid, 2,3-naphthalene dicarboxylic acid, 2,5-furandicarboxylic acid, terephthalic diacetic acid, isophthalic diacetic acid, phthalic diacetic acid. The polyol is one or more of diol, triol, and tetrol, preferably diol, and more preferably one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol.

[0010] Optionally, the polyester containing the aromatic dicarboxylic acid polyol ester structure in the present invention can be one or several of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), copolymer of butanediol adipate and butanediol terephthalate (PBAT), polyethylene furanoate (PEF). The polyester containing the aromatic dicarboxylic acid polyol ester structure can also be any other common polyester containing polyether ester structure or triol and tetrol residue structures, as long as the main chain contains the aromatic dicarboxylic acid polyol ester structure, it can be used as the raw material in the method of the present invention.

[0011] Optionally, the polyether diol is a homopolymer or copolymer polyether diol prepared by condensation polymerization of small molecule diols with C2-C5 or ring-opening polymerization of epoxides with C2-C5. Specifically, preferably one or several of polyethylene glycol (PEG), poly-1,3-propanediol (P3OG), poly-1,2-propanediol (PPG), polytetrahydrofuran (PTG), copolymer of polyethylene glycol-1,2-propanediol, copolymer of polytetrahydrofuran-3-methyltetrahydrofuran.

[0012] Optionally, the molar ratio of the aromatic group structure in the polyether diol and the polyester is calculated by the following formula:

[0013] R = (W + P - 36) / (W - A)

[0014] In the formula,

[0015] R is the molar ratio of the aromatic group structure in the polyether diol and the polyester,

[0016] W is the molecular weight of the target polyether ester polyol, and W is 1000 - 5000,

[0017] P is the molecular weight of the aromatic dicarboxylic acid in the raw materials of the polyester,

[0018] A is the average molecular weight of the polyether diol.

[0019] Among them, the aromatic dicarboxylic acid in the raw materials of the polyester is a dicarboxylic acid raw material forming the aromatic dicarboxylic acid polyol ester structure, such as terephthalic acid, phthalic acid, 2,5-furandicarboxylic acid, etc. as described above.

[0020] The polyether ester polyol prepared by the method for preparing polyether ester polyol described above, characterized in that the polyether ester polyol contains the structures and end-capped alcoholic hydroxyl groups shown in the following formula (1) and the following formula (2):

[0021]

[0022] Wherein R1 is an aromatic group, and the mass content of R1 in the repeating unit of formula (1) is 4.5% - 44%, R2 is at least one of saturated alkane groups with 2 - 5 carbon atoms, x is 2 - 20, and R3 is the residue of the polyol in the polyester raw materials;

[0023] The mass ratio of formula (2) in the structure of the polyether ester polyol is less than 20%, preferably less than 10%;

[0024] The number average molecular weight of the polyether ester polyol is 1000 - 5000;

[0025] The average functionality of the end-capped alcoholic hydroxyl group is 1.95 - 2.00.

[0026] Preferably, the R2 is at least two of saturated alkane groups with 2 - 5 carbon atoms.

[0027] The above polyether ester polyol can not only be used for preparing spandex, but also for preparing other polyurethane products. Therefore, the present invention also provides a method for preparing polyurethane elastic fibers, non-woven fabrics, films or elastomers by using the above polyether ester polyol as a raw material in a solution processing or melt processing manner. And polyurethane elastic fibers, non-woven fabrics, films or elastomers prepared according to the method.

[0028] Beneficial effects:

[0029] The method for preparing polyether ester polyol provided by the present invention uses polyester as a raw material, can directly process recycled polyester into polyether ester polyol suitable for producing spandex, simplifies the production process of polyether ester polyol suitable for producing spandex, utilizes recycled resources, and also broadens the raw material sources of polyurethane elastic fibers. Specific embodiments

[0030] For the recycling of polyester materials, the most common method at present is to recycle by melting and pelletizing, or to chemically decompose it into terephthalic acid (PTA) or dimethyl terephthalate (DMT) for reuse as chemical raw materials. The present invention discovers a method for preparing polyether ester polyol, which uses polyester as the raw material, and the obtained polyether ester polyol can be used as the soft segment raw material of spandex. Through the method of the present invention, polyester can be used as the direct raw material of polyurethane elastic fiber, broadening the uses of recycled polyester while also expanding the raw material sources of spandex.

[0031] Specifically, the present invention provides a method for preparing polyether ester polyol, and the polyether ester polyol obtained by this method, the polyether ester polyol contains the structures and end-capped alcohol hydroxyl groups shown in the following formula (1) and the following formula (2):

[0032]

[0033]

[0034] Wherein R1 is an aromatic group structure, and the mass content of R1 in the repeating unit of formula (1) is 4.5% - 44%, R2 is at least one of saturated alkane groups with 2 - 5 carbon atoms, x is 2 - 20, and R3 is the residue of the polyol in the polyester raw material;

[0035] The mass ratio of formula (2) in the structure of the polyether ester polyol is less than 20%, preferably less than 10%, and more preferably 0;

[0036] The number average molecular weight of the polyether ester polyol is 1000 - 5000;

[0037] The average functionality of the end-capped alcohol hydroxyl group is 1.95 - 2.00.

[0038] Hereinafter, unless otherwise specified, the polyether ester polyol specifically refers to the polyether ester polyol having the above characteristics.

[0039] The aromatic group structure described in the present invention includes aromatic rings and heteroaromatic rings, wherein the aromatic ring can be at least one of aromatic rings such as benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, etc.; the heteroaromatic ring can be at least one of pyridine, furan ring, thiazole ring, pyrimidine ring, etc. When the content of the aromatic group R1 in the polyether ester polyol is too high, it will cause the final polyether ester polyol to be too rigid, and then cause the viscosity to be too large, which is not conducive to the production process of polyurethane elastic fiber. Therefore, the mass content of R1 in the repeating unit of formula (1) is 4.5% - 44%.

[0040] The structure of formula (2) is the residual structure of polyester in which the reaction in the method of the present invention is not complete. Since the reaction of the present invention usually cannot be 100% complete, a part of the group structure of the polyester raw material will remain. Therefore, a part of the structural unit of the above formula (2) may exist in the finally prepared polyether ester polyol. However, by controlling the reaction conditions, the transesterification reaction can be made as complete as possible. The structure of formula (2) will significantly increase the melting point of the polyether ester polyol and also increase the intermolecular force of the polyether ester diol. During prepolymerization, it will cause the viscosity of the prepolymer to be too high to complete the prepolymerization reaction. Moreover, the structure of the aromatic dicarboxylic acid polyol ester will also affect the elastic recovery of the final polyurethane, resulting in a lower elastic recovery rate and a larger permanent deformation. Therefore, in the present invention, the mass ratio of formula (2) in the structure of the polyether ester polyol is less than 20%, preferably less than 10%, and more preferably 0.

[0041] According to the present invention, the average functionality of the end-capped alcohol hydroxyl groups of the polyether ester polyol can be 1.95 - 2.00, preferably 1.96 - 2.00, and more preferably 1.98 - 2.00. This can ensure that the polyether ester polyol can be smoothly end-capped with isocyanate and then chain-extended with a small molecule amine or alcohol. If the average functionality is greater than 2.00, when the polyether ester polyol is used as a raw material for preparing polyurethane, it may cause the prepared polyurethane to have a crosslinked structure, thus unable to form a chain-like polyurethane; such polyurethane will form gels during continuous production, hindering the continuous production of spandex. If the average functionality is small, the molecular weight of the prepared polyurethane will also be low, thereby affecting the performance of the polyurethane elastic fiber. In the actual reaction, due to the possible dehydration of the end hydroxyl groups to form double bonds during the polycondensation / ring-opening polymerization process of the polyether diol, and due to the limitation of the actual reaction effect, the polycondensation reaction or transesterification reaction of the polyether diol to form the polyether ester polyol cannot be 100% completed. Therefore, the average functionality of the finally prepared polyether ester polyol generally cannot reach 2.00.

[0042] Herein, the "average functionality" represents the average number of moles of alcohol hydroxyl groups that can participate in the reaction per mole of the polyether ester polyol. In the present invention, considering the dehydration of the end hydroxyl groups of the polyether diol to form double bonds and the existence of unreacted carboxyl groups, the average functionality of the alcohol hydroxyl groups can be calculated by the following formula:

[0043] Functionality = 2 * number of moles of alcohol hydroxyl groups / (number of moles of alcohol hydroxyl groups + number of moles of carboxyl groups + number of moles of double bonds)

[0044] The melting point of the polyether ester polyol of the present invention can be lower than 80°C, preferably in a liquid state at room temperature, so as to avoid its solidification during storage or transportation to ensure the realization of industrial continuous operation. Otherwise, it needs to be melted by heating, increasing energy consumption.

[0045] The inventors found that the polyether ester polyol with the above characteristics can replace polytetrahydrofuran ether diol as the soft segment raw material of spandex, and the spandex prepared has a high elastic recovery rate. On this basis, the inventors proposed a method for preparing the above polyether ester polyol. Compared with the conventional method of reacting dicarboxylic acid with polyether diol, the recycled polyester can be used as the raw material to prepare the polyether ester polyol, which broadens the utilization mode of recycled polyester, broadens the source of spandex raw materials, and is also more in line with the concept of environmental protection.

[0046] The specific preparation method of the polyether ester polyol proposed by the present invention includes the following steps:

[0047] Step 1) Add polyether diol and polyester as raw materials into a reaction kettle. Among them, the polyester contains an aromatic dicarboxylic acid polyol ester structure, the polymerization degree of the polyether diol is 2 - 20, preferably 3 - 10, and the molecular weight is 100 - 1000. The molar ratio of the aromatic groups in the polyether diol and the polyester is greater than 1.05:1;

[0048] Step 2) Heat the reaction kettle to the reaction temperature for transesterification reaction, and use the method of vacuum distillation to distill out the small molecule polyol produced by the transesterification reaction to prepare the polyether ester polyol. Among them, the reaction temperature is above the boiling point of the small molecule polyol and below the boiling point of the polyether diol.

[0049] In the method of the present invention, an ester exchange reaction is carried out using a polyester containing an aromatic group structure and a specific polyether diol as raw materials to obtain a polyether ester polyol that meets the above characteristics. The molecular structure of the polyether ester polyol to be prepared in the present invention is an aromatic group-polyether structure connected by an ester bond. Therefore, the above method selects a polyester containing an aromatic group structure as the raw material to introduce the aromatic group structure in the polyester into the molecular structure of the polyether ester polyol. Specifically, the polyester containing an aromatic group structure can be any common polyester material copolymerized from an aromatic group and a small molecule polyol, such as polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), adipic acid butanediol ester and butylene terephthalate copolymer (PBAT), etc. containing aromatic acid esters in the structure; or a polyester containing aromatic heterocyclic acid esters such as polyethylene 2,5-furandicarboxylate (PEF), etc. The above polyesters can all be obtained from recycled polyester plastic bottles, polyester fibers, polyester films, etc. Compared with the rigid aromatic group structure, the polyether segment in the polyether ester polyol of the present invention provides elasticity for the molecule. In order to make the finally prepared spandex have sufficient elastic recovery ability, the polyether segment should have a certain length. If the polyether segment is too short, the viscosity of the polyether ester polyol will be too high, which is not conducive to the continuous progress of the large-scale production process of spandex and will cause poor rebound performance of the spandex; while if the polyether segment is too long, the elastic modulus of the spandex will be too poor. Therefore, in the present invention, the molecular weight of the polyether segment raw material is preferably a polymerization degree of 2-20, more preferably 3-10, and the molecular weight is 100-1000, preferably 300-1000, more preferably 600-900 polyether diol. Specifically, the polyether diol can be obtained by ring-opening polymerization of an epoxy monomer or by polycondensation of a small molecule diol; it can be a homopolymer synthesized from a single monomer or a copolymer synthesized from two or more monomers. As an example, the polyether diol applicable to the present invention can be one or more of diethylene glycol (DEG), triethylene glycol (TEG), polyethylene glycol (PEG), poly-1,3-propanediol (P3OG), polypropylene glycol (PPG), polytetrahydrofuran (PTG), or a copolymer diol obtained by reacting tetrahydrofuran with monomers such as ethylene oxide, propylene oxide, 2-methyltetrahydrofuran or 3-methyltetrahydrofuran.

[0050] The number-average molecular weight of the polyether ester polyol of the present invention should be 1000 - 5000, preferably 1000 - 3500, more preferably 1400 - 2500, and most preferably 1500 - 2300. The larger the number-average molecular weight of the polyether ester polyol, the greater its viscosity, and it is difficult to carry out continuous operation on an industrial scale. However, if the molecular weight of the polyether ester polyol is too small, when the molecular weight of the polyurethane prepolymer is required to be consistent, more diisocyanate needs to participate in the synthesis, resulting in a relatively high content of urethane groups in the prepolymer. As a result, the interaction between prepolymer molecules is enhanced, and the viscosity will also increase. Moreover, at this time, the length of the soft segment in the formed polyurethane is relatively short, which will affect the recovery performance of the final polyurethane elastic fiber. In a preferred embodiment, the polyether ester polyol of the present invention has a viscosity at 90 °C and a shear rate of 1S -1 less than 500 poises, preferably less than 200 poises.

[0051] Since the method provided by the present invention prepares polyether ester polyol by transesterification of polyether diol with polyester containing aromatic groups, therefore, the molecular weight of the polyether ester polyol can be adjusted by adjusting the molar ratio R of the aromatic groups in the polyether diol and polyester. Hereinafter, the molar ratio R always refers to the molar ratio of the aromatic groups in the polyether diol and polyester. The higher the above molar ratio R, that is, the more the proportion of polyether diol in the raw materials, the more terminal hydroxyl groups left after the small-molecule polyol residues in the polyester high-molecular compound are replaced by polyether diol, and the smaller the number-average molecular weight of the prepared polyether ester polyol; conversely, the less the proportion of polyether diol in the raw materials, the larger the number-average molecular weight of the prepared polyether ester polyol. To play the role of adjusting the molecular weight of the polyether ester polyol, the molar number of the polyether diol should be greater than the molar number of the aromatic group structure in the polyester. In theory, when the transesterification reaction is complete, the polyether diol replaces all the small-molecule polyol residues in the polyester, and the excess polyether diol cuts the macromolecular polyester molecular chain to form a polyether ester polyol with a relatively small molecular weight. Therefore, the difference between the molar number of the polyether diol and the molar number of the aromatic group structure in the polyester is the molar number of the finally obtained polyether ester polyol. From the above analysis, the calculation method for the theoretically expected molecular weight of the finally prepared polyether ester polyol is:

[0052]

[0053] For the specific molar ratio R of the aromatic groups in the polyether diol and polyester, it can be inversely deduced through the above formula, and the specific process is as follows:

[0054] Let the molecular weight of the finally obtained polyether ester polyol be W, the molecular weight of the polyether diol be A, and the molar amount of the feedstock be M. Then the feedstock mass of the polyether diol is M·A. Let the polyester be obtained by reacting an aromatic dicarboxylic acid with a molecular weight of P and a small molecule polyol with a molecular weight of Q. Then the molecular weight of the polyester repeating unit is (P + Q - 36), and the molar amount of the aromatic group structure in the feedstock polyester is M / R. Then the feedstock mass of the polyester is (P + Q - 36)·M / R. Substituting the above letters into Equation (1), the following formula is obtained:

[0055]

[0056] Simplifying the above Equation (4) gives the relationship between the molecular weight W of the polyether ester polyol and the feedstock molar ratio R as follows:

[0057]

[0058] According to Equation (5), when a polyether ester polyol with a specific molecular weight needs to be prepared, the feedstock molar ratio R can be calculated by the following formula:

[0059]

[0060] It can be seen from Equation (6) that to prepare a polyether ester polyol with a molecular weight W of 1000 - 5000, in addition to the molar ratio R, it is also related to the molecular weight P of the aromatic dicarboxylic acid and the molecular weight A of the polyether diol. However, it can be determined that the molar amount of the polyether diol in step (1) should be greater than the molar amount of the aromatic groups in the polyester. Therefore, in the present invention, the molar ratio of the polyether diol to the aromatic groups in the polyester is greater than 1.05:1, preferably greater than 1.1:1.

[0061] In step (2), the temperature of the transesterification reaction should be controlled above the boiling point of the small molecule polyol and below the boiling point of the polyether diol, so that the exchanged small molecule polyol can be distilled out as much as possible to promote the complete progress of the transesterification.

[0062] During the transesterification reaction, a catalyst is preferably added to promote the reaction. In the present invention, the catalyst is selected from one or more of titanium, vanadium, tin, antimony, zirconium, bismuth, and rare earth catalysts. Preferably, it is selected from one or more of tetra-isopropyl titanate, tetra-butyl titanate, dibutyltin dilaurate, stannous octoate, and bismuth laurate.

[0063] The present invention also provides a method for preparing polyurethane products such as polyurethane elastic fibers, non-woven fabrics, films, or elastomers using the above polyether ester polyol or the polyether ester polyol prepared by the above method as a raw material. The preparation method of polyurethane can adopt the two-step method of synthesizing prepolymers or the one-pot method of feeding all materials together.

[0064] Among them, the two-step method for preparing polyurethane includes the following steps: (1) reacting a polyether ester polyol with a diisocyanate to form a prepolymer; and (2) polymerizing the prepolymer with a chain extender and a chain terminator. The one-pot method for preparing polyurethane includes the following steps: (1) separately feeding a polyether ester polyol, a diisocyanate, and a small molecule polyol chain extender, that is, adding each material into a reaction vessel separately; (2) mixing the polyether ester polyol, the diisocyanate, and the small molecule polyol chain extender in the reaction vessel, heating the mixture for reaction, or heating during the mixing process. The diisocyanate can be selected from one or more of diphenylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, and its isomers. The chain extender can be an amine-based or alcohol-based chain extender. Among them, the amine-based chain extender can be a diamine with 2 to 30 carbon atoms, for example, it can be selected from one or more of ethylenediamine, propylenediamine, trimethylenediamine, pentamethylenediamine, methylpentamethylenediamine, methylpropylenediamine, hexamethylenediamine, triethylenediamine, xylylenediamine, phenylenediamine, dicyclohexylamine, hexamethylenediamine, dopamine; the alcohol-based chain extender can be one or more of common chain extenders such as ethylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, 1,3-propanediol, 1,4-bis(hydroxymethyl)cyclohexane. The chain terminator can be a primary amine with 2 to 20 carbon atoms, and can be selected from one or more of ethylamine, isopropylamine, n-butylamine, tert-butylamine, hexylamine, dimethylamine, diethylamine, dipropylamine, di-n-butylamine, di-tert-butylamine, diisobutylamine, diisopropylamine, cyclohexylamine, or ethanolamine.

[0065] Unless otherwise specified in this specification, the corresponding operating conditions in the existing methods for preparing polyurethane products such as polyurethane elastic fibers, non-woven fabrics, films, and elastomers using polyether diols, such as solution processing or melt processing methods, can be applied to the present invention. For example, polyurethane elastic fibers can be prepared by dry spinning of a polyurethane solution using the methods and equipment described in patent document CN1147628C, or by melt spinning of polyurethane chips using the melt spinning method described in patent document CN1180137C; non-woven fabrics can be processed by melt blowing, solution electrospinning, etc. Specifically, the melt blown non-woven fabric manufacturing method described in patent document CN101400838A and the non-woven fabric prepared by the solution electrospinning method described in patent document JP2009108422A; polyurethane film sheets can be processed by solution blade coating, dip coating, melt extrusion, blown film, casting, etc. Specifically, the blade coating method described in patent document JP2005205787A, the dip coating method described in patent document WO2015064776A1, the extrusion method described in patent document GB1137520A, the blown film method described in patent document DE2239478A1, and the casting method described in patent document JP2004203933A are used to prepare polyurethane film sheets; elastomers can be processed by extrusion, injection molding, casting, etc. Specifically, the extrusion method described in patent document JP1996027376A, the injection molding method described in patent document US3917792A, and the casting method described in patent document CA1251294A are used to prepare polyurethane elastomers. The production methods of polyurethane products described in the above patent documents are all incorporated into the present invention. The preparation methods of the above-mentioned polyurethane elastic fibers, non-woven fabrics, films, and elastomers are only examples. In addition to the forms mentioned above, the polyether ester polyols of the present invention can be used as diol raw materials to produce polyurethane products by any existing techniques or means.

[0066] Examples

[0067] The present invention will be described in more detail below through examples, and the test methods for the parameters involved are as follows:

[0068] 1. Average functionality:

[0069] Functionality = 2 * moles of alcohol hydroxyl groups / (moles of alcohol hydroxyl groups + moles of carboxyl groups + moles of double bonds).

[0070] Among them, the acid value is measured by the method described in HG / T 2708-1995; the hydroxyl value is measured by the method described in HG / T 2709 / 1995; the unsaturation is measured by the method described in GB / T 12008.6-2010. The corresponding acid value, hydroxyl value, and unsaturation are converted into the molar numbers of the corresponding end groups in the polyether ester diol.

[0071] 2. Tensile stress at 300%, breaking strength, and elongation at break: All are in accordance with the "Test Method for Tensile Properties of Spandex Yarns" of the Textile Industry Standard of the People's Republic of China, FZ / T 50006 - 2013.

[0072] 3. Plastic deformation experiment:

[0073] Clamp one end of the prepared specimen into the upper gripper, apply a pre - tension to the other end, straighten the specimen axially and clamp it into the lower gripper, then start the instrument.

[0074] The specimen is stretched from the 0% elongation point L0 to the 300% elongation point L1 at a speed of 500 mm / min, and then returned to 0% elongation. This stretching - recovery cycle is repeated four times; during the fifth stretching to 300% elongation, record the force value F1 at 200% elongation, delay for 30 s, and then return to 0% elongation. During this process, record the force value F2 at 200% elongation; delay for 30 s, perform the sixth stretching, and record the length L2 of the specimen when stretched to the pre - tension point.

[0075] Calculation formula for plastic deformation rate: (L2 - L0) / L0 * 100%

[0076] Among them, "5LP200%" represents the stress value at 200% elongation during the fifth stretching, that is, F1; "5UP200%" represents the resilience stress value when returning from 300% elongation to 200% elongation during the fifth stretching, that is, F2, which can be used to characterize the recovery modulus; "plastic deformation rate" represents the increase ratio of the length of the spandex yarn compared to the original length after five stretches; "5UP200% / 5LP 200%" represents the ratio of the 200% recovery stress to the 200% tensile stress during the fifth stretching cycle test.

[0077] In addition, the antioxidant mentioned in the following examples is antioxidant 245, the dyeing assistant is DH300R or 2462B, and the light stabilizer is Tinuvin 791, all of which are commercially available substances on the market.

[0078] In the following examples, due to the small - molecule polyols distilled out as non - condensable gases during the reaction process and the influence of the volatilization of small - molecule components in the polyether diol, the actual alcohol - acid ratio participating in the reaction is less than the theoretical value. Therefore, the molecular weight of the final product is larger than the theoretical value, but the deviation value is within an acceptable range.

[0079] Examples 1 - 6 below are about using polyethylene terephthalate (PET) as a raw material for the preparation of polyether ester polyols.

[0080] Preparation of polyether ester polyol with a molecular weight of 1200 in Example 1

[0081] First, crush polyethylene terephthalate. Take 2081.9 g of crushed polyethylene terephthalate (PET) and 3000 g of polyethylene glycol with a number-average molecular weight of 200 (PEG200) and add them into a reaction kettle (i.e., the molar ratio is about 1.38). Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 235 °C, start the transesterification reaction, maintain at 235 °C until the reaction system becomes homogeneous, and use the method of vacuum distillation to distill out ethylene glycol in the reaction system until the distillation amount of ethylene glycol is close to the theoretical value. 650 g of ethylene glycol is distilled out from the reaction system. A polyether ester polyol with a molecular weight of 1200 is obtained. The viscosity of this polyether ester polyol at 40 °C for 1S -1 is 100 Poise, the acid value is 0.3, and it is a light yellow liquid at room temperature.

[0082] Example 2 Preparation of polyether ester polyol with a molecular weight of 2100

[0083] First, crush polyethylene terephthalate. Take 2428.9 g of crushed polyethylene terephthalate (PET) and 3000 g of polyethylene glycol with a number-average molecular weight of 200 (PEG200) and add them into a reaction kettle (i.e., the molar ratio is about 1.19). Add 3 g of magnesium acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 235 °C, start the transesterification reaction, maintain at 235 °C until the reaction system becomes homogeneous, and use the method of vacuum distillation to distill out ethylene glycol in the reaction system until the distillation amount of ethylene glycol is close to the theoretical value. 781.9 g of ethylene glycol is distilled out from the reaction system. A polyether ester polyol with a molecular weight of 2100 is obtained. The viscosity of this polyether ester polyol at 40 °C for 1S -1 is 210 Poise, the acid value is 0.3, and it is a light yellow liquid at room temperature.

[0084] Example 3 Preparation of polyether ester polyol with a molecular weight of 3400

[0085] First, crush polyethylene terephthalate. Take 2602.4 g of crushed polyethylene terephthalate (PET) and 3000 g of polyethylene glycol with a number-average molecular weight of 200 (PEG200) and add them into a reaction kettle (i.e., the molar ratio is about 1.11). Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 235 °C, start the transesterification reaction, maintain at 235 °C until the reaction system becomes homogeneous, and use the method of vacuum distillation to distill out ethylene glycol in the reaction system until the distillation amount of ethylene glycol is close to the theoretical value. 842.3 g of ethylene glycol is distilled out from the reaction system. A polyether ester polyol with a molecular weight of 3400 is obtained. The viscosity of this polyether ester polyol at 40 °C for 1S -1 is 650 Poise, the acid value is 0.3, and it is a light yellow liquid at room temperature.

[0086] Preparation of Polyether Ester Polyol with a Molecular Weight of 1500 in Example 4

[0087] First, crush polyethylene terephthalate. Take 1296.5 g of crushed polyethylene terephthalate (PET) and 4203 g of polyethylene glycol (PEG400) with a number-average molecular weight of 400 and add them into a reaction kettle (i.e., the molar ratio is about 1.57). Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 245 °C, start the transesterification reaction, and maintain 245 °C until the reaction system becomes homogeneous. Use the method of vacuum distillation to distill out ethylene glycol from the reaction system until the distillation amount of ethylene glycol is close to the theoretical value. 418.6 g of ethylene glycol is distilled out from the reaction system. Obtain polyether ester polyol with a molecular weight of 1500. The viscosity of this polyether ester polyol at 40 °C for 1S -1 is 73.5 Poise, the acid value is 0.3, and it is a light yellow liquid at room temperature.

[0088] Preparation of Polyether Ester Polyol with a Molecular Weight of 3450 in Example 5

[0089] First, crush polyethylene terephthalate. Take 1019.2 g of crushed polyethylene terephthalate (PET) and 4480 g of polyethylene glycol (PTG650) with a number-average molecular weight of 650 and add them into a reaction kettle (i.e., the molar ratio is about 1.30). Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 245 °C, start the transesterification reaction, and maintain 245 °C until the reaction system becomes homogeneous. Use the method of vacuum distillation to distill out ethylene glycol from the reaction system until the distillation amount of ethylene glycol is close to the theoretical value. 329 g of ethylene glycol is distilled out from the reaction system. Obtain polyether ester polyol with a molecular weight of 3450. The viscosity of this polyether ester polyol at 40 °C for 1S -1 is 35.2 Poise, the acid value is 0.3, and it is a light yellow liquid at room temperature.

[0090] Preparation of Polyether Ester Polyol with a Molecular Weight of 3500 in Example 6

[0091] First, pulverize polyethylene terephthalate. Take 699 g of pulverized polyethylene terephthalate (PET) and 4800.2 g of poly(1,3 - propanediol) with a number - average molecular weight of 1000 (P3OG1000) and add them to a reaction kettle (i.e., the molar ratio is about 1.32). Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 250 °C, and start the transesterification reaction. Keep the temperature at 250 °C until the reaction system becomes homogeneous. Use the method of vacuum distillation to distill out ethylene glycol from the reaction system until the distillation amount of ethylene glycol is close to the theoretical value. 286 g of ethylene glycol is distilled out from the reaction system. A polyether ester polyol with a molecular weight of 3500 is obtained. The polyether ester polyol has a viscosity of 28.5 Poise at 40 °C, an acid value of 0.3, and is a light - yellow liquid at room temperature. -1 The viscosity of the polyether ester polyol at 40 °C is 28.5 Poise, the acid value is 0.3, and it is a light - yellow liquid at room temperature.

[0092] Preparation of polyether ester polyol with a molecular weight of 3480 in Example 7

[0093] First, pulverize polybutylene terephthalate. Take 1137.14 g of pulverized polybutylene terephthalate (PBT) and 4362.85 g of polytetrahydrofuran with a number - average molecular weight of 650 (PTG650) and add them to a reaction kettle (i.e., the molar ratio is about 1.30). Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 260 °C, and start the transesterification reaction. Keep the temperature at 260 °C until the reaction system becomes homogeneous. Use the method of vacuum distillation to distill out 1,4 - butanediol from the reaction system until the distillation amount of 1,4 - butanediol is close to the theoretical value. 465 g of 1,4 - butanediol is distilled out from the reaction system. A polyether ester polyol with a molecular weight of 3480 is obtained. The polyether ester polyol has a viscosity of 35.8 Poise at 40 °C, an acid value of 0.3, and is a light - yellow liquid at room temperature. -1 The viscosity of the polyether ester polyol at 40 °C is 35.8 Poise, the acid value is 0.3, and it is a light - yellow liquid at room temperature.

[0094] In the following, Examples 8 - 10 use the polyether ester polyol to prepare polyurethane elastic fibers

[0095] In Example 8, the polyether ester polyol of Example 1 is used to prepare polyurethane elastic fibers

[0096] Add 100 kg of the polyether ester polyol prepared in Example 1 to a reaction kettle that has been thermostatically controlled at 45 °C, start stirring, with a stirring speed of 150 rpm, add 31 kg of diphenylmethane diisocyanate, stir for 5 min, and then heat it up to 90 °C; let it react at 90 °C for 2 h to obtain a prepolymer.

[0097] Cool the prepolymer to 50°C, dissolve the prepolymer using 166.72 kg of dimethylacetamide (DMAc), then add an amine solution with a mass concentration of 3.2% containing 2.40 kg of ethylenediamine and 0.29 kg of diethylamine, increase the stirring speed to 300 rpm, and carry out the chain extension reaction. After the chain extension reaction is completed, add necessary additives such as antioxidants and auxochromes, and then cure for 30 h to obtain a spinning dope with a solid content of 35%. Carry out dry spinning on the above dope to obtain polyurethane elastic fiber PUU-3 with a denier of 40D.

[0098] Example 9 The polyether ester polyol of Example 6 is used to prepare polyurethane elastic fiber

[0099] Add 100 kg of the polyether ester polyol prepared in Example 1 to a reaction kettle that has been kept at a constant temperature of 45°C, start stirring at a stirring speed of 150 rpm, add 16.15 kg of diphenylmethane diisocyanate, and after stirring for 5 min, heat it up to 90°C; let it react at 90°C for 2 h to obtain a prepolymer.

[0100] Cool the prepolymer to 50°C, dissolve the prepolymer using 147.82 kg of dimethylacetamide (DMAc), then add an amine solution with a mass concentration of 3.2% containing 2.13 kg of ethylenediamine and 0.26 kg of diethylamine, increase the stirring speed to 300 rpm, and carry out the chain extension reaction. After the chain extension reaction is completed, add necessary additives such as antioxidants and auxochromes, and then cure for 30 h to obtain a spinning dope with a solid content of 35%. Carry out dry spinning on the above dope to obtain polyurethane elastic fiber PUU-4 with a denier of 40D.

[0101] Example 10 The polyether ester polyol of Example 7 is used to prepare polyurethane elastic fiber

[0102] Add 100 kg of the polyether ester polyol prepared in Example 1 to a reaction kettle that has been kept at a constant temperature of 45°C, start stirring at a stirring speed of 150 rpm, add 16.20 kg of diphenylmethane diisocyanate, and after stirring for 5 min, heat it up to 90°C; let it react at 90°C for 2 h to obtain a prepolymer.

[0103] Cool the prepolymer to 50°C, dissolve the prepolymer using 147.89 kg of dimethylacetamide (DMAc), then add an amine solution with a mass concentration of 3.2% containing 2.14 kg of ethylenediamine and 0.27 kg of diethylamine, increase the stirring speed to 300 rpm, and carry out the chain extension reaction. After the chain extension reaction is completed, add necessary additives such as antioxidants and auxochromes, and then cure for 30 h to obtain a spinning dope with a solid content of 35%. Carry out dry spinning on the above dope to obtain polyurethane elastic fiber PUU-5 with a denier of 40D.

[0104] Poly(tetramethylene glycol) (PTMG) with a number-average molecular weight of 2000 was used to prepare polyurethane elastic fibers

[0105] 100 kg of poly(tetramethylene glycol) PTMG2000 (number-average molecular weight of 2000) was added to a reaction kettle that had been heated to a constant temperature of 45 °C, and stirring was started at a stirring speed of 150 rpm. 22.2 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90 °C, and it was reacted at 90 °C for 2 h to obtain a prepolymer.

[0106] The prepolymer was cooled to 50 °C, and 155.5 kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer. Then, an amine solution with a concentration of 3.2% containing 2.26 kg of ethylenediamine and 0.28 kg of diethylamine was added, and the stirring speed was increased to 300 rpm for chain extension reaction. After the chain extension reaction was completed, necessary additives such as antioxidants and dyeing assistants were added, and it was cured for 30 h to obtain a spinning dope with a solid content of 35%. The above dope was subjected to dry spinning to obtain polyurethane elastic fibers PUU-0 with a denier of 40D.

[0107] Polyethylene glycol with a number-average molecular weight of 1500 was used to prepare polyurethane elastic fibers in Comparative Example 2

[0108] 100 kg of polyethylene glycol with a number-average molecular weight of 1500 was added to a reaction kettle that had been heated to a constant temperature of 45 °C, and stirring was started at a stirring speed of 150 rpm. 26.5 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90 °C; it was reacted at 90 °C for 2 h to obtain a prepolymer.

[0109] The prepolymer was cooled to 50 °C, and 161 kg of dimethylacetamide (DMAc) was used to dissolve the prepolymer. Then, an amine solution with a concentration of 3.2% containing 2.32 kg of ethylenediamine and 0.28 kg of diethylamine was added, and the stirring speed was increased to 300 rpm for chain extension reaction. After the chain extension reaction was completed, necessary additives such as antioxidants and dyeing assistants were added, and it was cured for 30 h to obtain a spinning dope with a solid content of 35%. The above dope was subjected to dry spinning to obtain polyurethane elastic fibers PUU-1 with a denier of 40D.

[0110] Polypropylene glycol with a number-average molecular weight of 2000 was used to prepare polyurethane elastic fibers in Comparative Example 3

[0111] 100 kg of polypropylene glycol with a number-average molecular weight of 2000 was added to a reaction kettle that had been heated to a constant temperature of 45 °C, and stirring was started at a stirring speed of 150 rpm. 21.98 kg of diphenylmethane diisocyanate was added, and after stirring for 5 minutes, the temperature was raised to 90 °C; it was reacted at 90 °C for 2 h to obtain a prepolymer.

[0112] Cool the prepolymer to 50°C, dissolve the prepolymer using 155.24 kg of dimethylacetamide (DMAc), then add an amine solution with a concentration of 3.2% containing 2.24 kg of ethylenediamine and 0.28 kg of diethylamine, increase the stirring speed to 300 rpm, and carry out the chain extension reaction. After the chain extension reaction is completed, add necessary additives such as antioxidants and dyeing assistants, and then cure for 30 h to obtain a spinning dope with a solid content of 35%. Carry out dry spinning on the above dope to obtain polyurethane elastic fiber PUU-2 with a denier of 40D.

[0113] Preparation of polyether ester polyol with a molecular weight of 1200 in Comparative Example 4

[0114] First, crush polyethylene terephthalate. Take 2602.4 g of crushed polyethylene terephthalate (PET) and 3000 g of polyethylene glycol with a number average molecular weight of 200 (PEG200) and add them to the reaction kettle. Add 3 g of zinc acetate and 1.5 g of Sb2O3 as catalysts, gradually heat up to 235°C, and start the transesterification reaction. Keep at 235°C until the reaction system becomes homogeneous. Use the method of vacuum distillation to distill out ethylene glycol from the reaction system. 681 g of ethylene glycol is distilled out from the reaction system. Obtain polyether ester diol with a molecular weight of 1200. This polyether ester diol is a solid at 40°C, has a melting point of 60°C, an acid value of 0.3, and the molar ratio of this ethylene glycol ester structure is 20%.

[0115] Use the polyether ester polyol of Comparative Example 4 to prepare polyurethane elastic fiber in Comparative Example 5

[0116] Add 100 kg of the polyether ester polyol prepared in Comparative Example 4 to a reaction kettle that has been thermostatically controlled to 90°C, start stirring, with a stirring speed of 150 rpm, add 31 kg of diphenylmethane diisocyanate, and start the prepolymerization reaction; when the reaction proceeds to 57 min, the viscosity of the prepolymer is too high to continue the prepolymerization reaction.

[0117] According to the above test method, test the following parameters of the polyurethane elastic fibers (i.e., spandex filaments) obtained in Examples 8, 9, 10 and Comparative Examples 1, 2, 3. The test results are summarized in the following table.

[0118]

[0119] As can be seen from the data in the above table, the polyurethane elastic fibers prepared using the polyether ester polyol of the present invention have significantly improved tensile stress and breaking strength compared to the polyurethane elastic fibers prepared using polyethylene glycol as a raw material, and are close to or exceed the polyurethane elastic fibers prepared using polytetrahydrofuran ether glycol commonly used, and can meet the performance requirements of spandex filaments for clothing; in addition, the plastic deformation rate of the polyurethane elastic fibers prepared using the polyether ester polyol of the present invention has significantly decreased; judging from the value of 5UP200%, the polyurethane elastic fibers using the polyether ester diol of the present invention have a greater 5UP200% recovery stress, that is, a greater recovery modulus, which indicates a greater resilience and can make the fabric have better shape retention. In summary, the method for preparing polyether ester polyol provided by the present invention can use post-consumer polyester as a raw material to prepare a polyether ester polyol raw material for spandex that is comparable in performance to existing polytetrahydrofuran, and the spandex prepared has properties similar to those of spandex prepared from polytetrahydrofuran, with good mechanical properties and effectively improved wearing performance. Therefore, the polyether ester polyol prepared by the method for preparing polyether ester polyol using polyester provided by the present invention can be used as the soft segment raw material of spandex, broadening the application path of polyester recycling materials and also broadening the raw material source of spandex.

[0120] Dilute the spinning dope in Examples 8, 9, 10 and Comparative Examples 1, 2, 3 from a solid content of 35% to a solid content of 20%, and then use the dip coating method to prepare polyurethane film gloves, and cut to obtain the corresponding Example film strips PUU-F3, PUU-F4, PUU-F5, and the corresponding Comparative Example film strips PUU-F0, PUU-F1, PUU-F2. The specific preparation steps of the film strips are as follows:

[0121] First, slowly immerse the hand mold into the tank filled with the diluted dope, then slowly lift the hand mold out of the dope tank, slowly rotate the hand mold to make the dope have a uniform thickness on the surface of the hand mold, and then dry the hand mold in an oven. After drying, peel off the glove to obtain a polyurethane film glove with a wall thickness of about 150 microns. In order to test the mechanical properties of the glove film, cut the film from the palm part of the glove and cut it into strips with a width of 6 mm and a length of 10 cm to test the mechanical properties.

[0122] The mechanical properties are as follows:

[0123]

[0124] As can be seen from the data in the above table, for the film product gloves prepared with the polyether ester polyol of the present invention, when testing the film pieces cut from the palm thereof, it can be seen that compared with the film pieces of thin-walled products prepared with polyethylene glycol and polypropylene glycol as raw materials, both the tensile stress and the breaking strength have been significantly improved, approaching or exceeding the mechanical properties of the film pieces of the film products prepared with polytetrahydrofuran, which can meet the mechanical property requirements of elastic film gloves, consistent with the phenomenon found in spandex filaments; at the same time, the polyurethane film gloves prepared with the polyether ester diol prepared by the present invention have the characteristic of low plastic deformation, which makes the shape of the film glove products more stable; from the value of 5UP200%, the polyurethane film pieces prepared with the polyether ester diol of the present invention have a greater 5UP200% recovery force, which will make the glove have better wrapping property, and at the same time, on the premise of ensuring the wrapping force, the glove can be made thinner, thereby reducing the raw material cost of the film gloves. The polyether ester polyol provided by the invention effectively improves the mechanical properties of the film pieces when the polyether ester polyol is used as the fiber soft segment of the polyurethane film pieces. On this basis, at the same time, the thin-walled glove film products have a lower plastic deformation rate and a higher recovery modulus, maintain the shape of the film glove products, improve the wrapping property of the film glove products, and at the same time can reduce the raw material production cost.

[0125] The melt-spun spandex prepared with the polyether ester polyol of Example 2 in Example 11

[0126] The polyether ester polyol of Example 2, 1,4-butanediol and diphenylmethane diisocyanate were respectively metered into a twin-screw extruder at a molar ratio of 1.2:2:3.2, and continuously polymerized and extruded at 195°C, granulated underwater, and after drying to a moisture content of the polyurethane particles lower than 100 ppm, necessary antioxidants, light stabilizers and other additives were added and melt-spun together to obtain spandex TPU-1 with a denier of 20D.

[0127] The melt-spun spandex prepared with polytetrahydrofuran with a number average molecular weight of 2000 in Comparative Example 6

[0128] Polytetrahydrofuran PTMG2000 (with a number average molecular weight of 2000), 1,4-butanediol and diphenylmethane diisocyanate were respectively metered into a twin-screw extruder at a molar ratio of 1.2:2:3.2, and continuously polymerized and extruded at 190°C, granulated underwater, and after drying to a moisture content of the polyurethane particles lower than 100 ppm, necessary antioxidants, light stabilizers and other additives were added and melt-spun together to obtain TPU-0 with a denier of 20D.

[0129] The melt-spun spandex prepared with polyethylene glycol with a number average molecular weight of 1500 in Comparative Example 7

[0130] Polyethylene glycol with a number-average molecular weight of 1500, 1,4-butanediol and diphenylmethane diisocyanate were respectively metered into a twin-screw extruder in a molar ratio of 1.2:2:3.2, and continuously polymerized and extruded at 190 °C, granulated underwater, dried until the moisture content of the polyurethane particles was lower than 100 ppm, and then necessary additives such as antioxidants and light stabilizers were added and melt-spun together to obtain TPU-2 with a denier of 20D.

[0131]

[0132] From the comparison of the mechanical properties of the above comparative examples and examples, it can be seen that the melt-spun spandex filaments processed in the melt form with polyether ester as the raw material have significantly higher tensile stress and recovery modulus than those of the melt-processed melt-spun spandex using polytetrahydrofuran as the raw material, showing similar mechanical property characteristics and advantages to those of the dry-spun spandex processed in the solvent form.

Claims

1. A method for preparing a polyether ester polyol, characterized in that, It includes the following steps: Step 1) Add polyether diol and polyester as raw materials into a reaction kettle. Among them, the polyester contains an aromatic dicarboxylic acid polyol ester structure. The degree of polymerization of the polyether diol is 2-20, and the molecular weight is 100-1000. The molar ratio of the aromatic group structure in the polyether diol and polyester is greater than 1.05:1; Step 2) Heat the reaction kettle to the reaction temperature for transesterification reaction, and use the method of vacuum distillation to distill out the small molecule polyol produced by the transesterification reaction to prepare polyether ester polyol. Among them, the reaction temperature is above the boiling point of the small molecule polyol and below the boiling point of the polyether diol; The polyether ester polyol contains the structures and capped alcohol hydroxyl groups shown in the following formula (1) and formula (2): Where R1 is an aromatic group structure, and the mass content of R1 in the repeating unit of formula (1) is 4.5% - 44%. R2 is at least one of saturated alkane groups with 2-5 carbon atoms. x is 2-20. R3 is the residue of the polyol in the polyester raw material; The mass ratio of formula (2) in the structure of the polyether ester polyol is less than 20%; The number average molecular weight of the polyether ester polyol is 1000-5000; The average functionality of the capped alcohol hydroxyl group is 1.95-2.

00.

2. The method for preparing a polyether ester polyol according to claim 1, characterized in that, The mass ratio of formula (2) in the structure of the polyether ester polyol is less than 10%.

3. The method for preparing a polyether ester polyol according to claim 1, characterized in that, The polyether diol is one or several of polyethylene glycol, poly-1,3-propanediol, poly-1,2-propanediol, polytetrahydrofuran, polyethylene glycol-1,2-propanediol copolymer, and polytetrahydrofuran-3-methyltetrahydrofuran copolymer.

4. The method for preparing a polyether ester polyol according to claim 1, characterized in that, The molar ratio of the aromatic group structure in the polyether diol and polyester is calculated by the following formula: R=(W + P - 36) / (W - A) In the formula, R is the molar ratio of the aromatic group structure in the polyether diol and polyester, W is the molecular weight of the target polyether ester polyol, and W is 1000-5000, P is the molecular weight of the aromatic dicarboxylic acid in the polyester, A is the average molecular weight of the polyether diol.

5. The polyether ester polyol according to claim 1, characterized in that, The R2 is at least two of saturated alkane groups with 2-5 carbon atoms.

6. A method for preparing polyurethane elastic fibers, non-woven fabrics, films or elastomers by solution processing or melt processing using the polyether ester polyol prepared by the method for preparing polyether ester polyol according to any one of claims 1 to 5 or the polyether ester polyol according to claim 1 as a raw material.

7. Polyurethane elastic fibers, non-woven fabrics, films or elastomers prepared by the method according to claim 6.

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