High-resilience polyether ester elastomers based on po3g and methods of making and using the same

Abstract

This invention belongs to the field of polymer science, specifically relating to a high-resilience polyether ester elastomer based on PO3G, its preparation method, and its applications. The preparation method of the polyether ester elastomer is as follows: terephthalic acid or dimethyl terephthalate is reacted with a diol monomer and modified PO3G in the presence of a catalyst and a stabilizer to obtain a prepolymer; the obtained prepolymer is heated to a molten state, a small amount of organic titanium catalyst is added, and a melt polycondensation reaction is carried out under vacuum to obtain the product. The modified PO3G is PO3G modified with nanoparticle reinforcing agents. This invention, by using nanoparticle reinforcing agents to modify PO3G, improves the mechanical strength and resilience of the material, making it suitable as a matrix resin for high-performance foaming materials, meeting the high resilience requirements of high-end shoe midsoles.

Description

Technical Field

[0001] This invention relates to the field of polymers, and in particular to a high-resilience polyether ester elastomer based on PO3G, its preparation method, and its application. Background Technology

[0002] As a core component of footwear, the midsole's performance directly impacts cushioning, resilience, softness, lightweight design, and durability during wear. Currently, commonly used midsole foaming materials include ethylene-vinyl acetate copolymer (EVA) and polyurethane (PU). However, these materials have significant limitations: EVA midsoles have poor compression resistance and are prone to permanent deformation ("flattening") after repeated pressure, leading to a significant decrease in resilience and insufficient durability; PU midsoles, due to their high density, still struggle to achieve ideal lightweight design after foaming, and their processing is complex. Furthermore, traditional shoe material foaming often uses chemical foaming agents (such as azo compounds), which may leave harmful byproducts after decomposition, posing potential risks to the environment and human health. On the other hand, EVA and PU foamed midsoles typically require the addition of crosslinking agents for cross-linking and curing to form thermosetting foam. While this improves material performance to some extent, it makes the material non-recyclable, contradicting environmental protection principles. Currently, there is an urgent need to develop a foamed midsole material that combines high cushioning, high resilience, softness, lightweight, and excellent durability.

[0003] Thermoplastic polyester elastomers (TPEEs) have attracted attention due to their combination of the elasticity of rubber and the processability of thermoplastics. TPEEs can be processed without additional chemical crosslinking, are environmentally friendly, non-toxic, and recyclable, and have begun to be used in the field of shoe material foaming in recent years. TPEEs are typically synthesized by block copolymerization of polyester hard segments (such as polybutylene terephthalate, PBT) and polyether soft segments. The soft segments and amorphous hard segments form an amorphous phase, while the crystalline hard segments form microdomains that act as physical crosslinkers. This structure endows TPEEs with good elasticity and processability. However, existing applications of TPEEs in foaming materials still have several drawbacks: due to their relatively low melt strength, they are prone to producing large pores, open pores, or uneven pore sizes during physical foaming, leading to unstable foam structures and making it difficult to simultaneously achieve high foaming ratios and a fine, uniform cell structure. This limits the application of TPEEs in high-performance shoe midsoles.

[0004] To overcome this problem, researchers have introduced crosslinking to improve the cell stability and mechanical properties of TPEE foam materials. For example, by adding crosslinking agents such as organic peroxides, some linear TPEE molecules are bridged to form a three-dimensional network structure, enhancing melt strength and elasticity, and making it easier to form a fine and uniform closed-cell structure during the foaming process. Although crosslinking modification improves the foaming performance of TPEE to some extent, directly adding crosslinking agents in actual processing still brings new challenges: the crosslinking agent may react prematurely or unevenly during mixing and foaming, leading to excessive local crosslinking of the material, affecting cell uniformity and mechanical properties; at the same time, the violent reaction of crosslinking agents such as peroxides is difficult to control precisely, which limits the optimization effect of crosslinking modification. In particular, the resilience of polyether ester elastomers based on bio-based PO3G soft segments still needs further improvement, and they have not yet met the extreme demand for high resilience in high-end shoe midsoles. As the matrix resin of foam materials, TPEE provides basic elasticity and mechanical strength, which is a key step. Therefore, how to further optimize the performance of PO3G-based polyether ester elastomers as foaming materials has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems by providing a high-resilience polyether ester elastomer based on PO3G, its preparation method, and its application.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] The first aspect of this invention is to provide a method for preparing a high-resilience polyether ester elastomer based on PO3G, comprising the following steps:

[0008] (1) Terephthalic acid or dimethyl terephthalate is reacted with diol monomer and modified PO3G in the presence of catalyst and stabilizer to obtain a prepolymer;

[0009] (2) The obtained prepolymer is heated to the molten state, a small amount of organic titanium catalyst is added, and a melt polycondensation reaction is carried out under vacuum to obtain the product;

[0010] Wherein, the modified PO3G in step (1) is PO3G modified with nanoparticle reinforcing agent.

[0011] Further, the modified PO3G in step (1) is to disperse the nanoparticle reinforcing agent in PO3G to form a pre-dispersion liquid (for example, by high shear mixing or ultrasonic dispersion).

[0012] Further, the nanoparticle reinforcing agent accounts for 0.1-15% of the weight of the PO3G, preferably 1-10%, and more preferably 2-6%;

[0013] Furthermore, the nanoparticle reinforcing agent is selected from at least one of organically modified montmorillonite, nano-silica, nano-calcium carbonate, and graphene / graphene oxide, preferably organically modified montmorillonite (such as commercially available Nanomer). ® I.44P), nano-silica (such as Evonik Chemical's AEROSIL) ® R 972).

[0014] This invention modifies PO3G with nanoparticles, which act as heterogeneous nucleation sites in the polymer matrix, making the physical cross-linking network denser and more uniform. This helps to improve mechanical strength, restrict the movement of soft segments, store more energy during deformation, and further enhance resilience.

[0015] Further, the PO3G mentioned in step (1) is a polytrimethylene ether glycol with a weight average molecular weight of 1000~4000, preferably a polytrimethylene ether glycol with a weight average molecular weight of 2000~3000 (such as SK ECOPROL H2700 from South Korea, Daewoong Chemical H2400).

[0016] Furthermore, the timing of adding PO3G in step (1) is controlled in the middle and late stages of the esterification / exchange reaction, preferably after two-thirds of the total esterification time. Polytrimethylene ether glycol is added in a delayed manner, and polymerization is carried out after the hard segment structure has been initially formed. On the one hand, this reduces the degradation of polyether at high temperatures, which helps to obtain a prepolymer with uniform molecular weight and light color. On the other hand, it avoids excessive participation in the hard segment polymerization process, which affects the formation of the polymer's regular structure.

[0017] Furthermore, the PO3G accounts for 15%–50% of the total mass of the raw materials, preferably 30%–40%;

[0018] Further, the diol monomer in step (1) is at least one of 1,4-butanediol or 1,3-propanediol;

[0019] The molar ratio of terephthalic acid or dimethyl terephthalate to the diol monomer is 1:1.2 to 1.5.

[0020] Furthermore, the reaction temperature in step (1) is 140~230℃, and the reaction time is 1~4 hours;

[0021] Step (2) The prepolymer is heated to 215~250℃ and the vacuum degree is controlled at 50~100Pa to carry out melt polycondensation reaction for 0.5~2 hours.

[0022] Further, the catalyst in step (1) is an organotitanium catalyst or a composite catalyst with an iron-based complex catalyst as the main catalyst, and the stabilizer includes a heat stabilizer. The catalyst in step (2) is an organotitanium catalyst.

[0023] The amount of catalyst added in step (1) is 0.01%–0.5% relative to the total mass of the reactants; the amount of heat stabilizer added is 0.01%–0.5%; and the amount of organotitanium catalyst added in step (2) is 0.001%–0.01% relative to the total mass of the reactants.

[0024] Furthermore, the composite catalyst includes a main catalyst and a co-catalyst, wherein the main catalyst is an iron-based complex catalyst, and the co-catalyst includes an organotitanium catalyst and an organozinc catalyst;

[0025] Furthermore, the iron-based complex catalyst is selected from at least one of iron triacetylacetonate, iron tri(hexafluoroacetylacetonate), and iron trifluoroacetylacetonate.

[0026] The organic titanium catalyst is selected from at least one of tetrabutyl titanate, isopropyl titanate, and tetraethyl titanate.

[0027] The organic zinc catalyst is selected from at least one of zinc acetate, zinc propionate, and zinc trifluoromethanesulfonate;

[0028] The heat stabilizer is selected from at least one of trimethyl phosphate and triphenyl phosphite;

[0029] The amount of the composite catalyst added relative to the total mass of the reactants is as follows:

[0030] The amount of the main catalyst added is 0.01%–0.1%;

[0031] The amount of the organotitanium catalyst added is 0.001%–0.01%;

[0032] The amount of the organic zinc catalyst added is 0.005%–0.05%.

[0033] The second aspect of the present invention is to provide a high-resilience polyether ester elastomer based on PO3G prepared by the above-described preparation method, wherein the polyether ester elastomer has an intrinsic viscosity of 2.02-2.33 dL / g, a tensile strength of 30.5-40.2 MPa, an elongation at break of 390-450%, and a Shore hardness of 40D-45D.

[0034] A third aspect of this invention is to provide the application of a PO3G-based high-resilience polyether ester elastomer in the preparation of foamed materials.

[0035] Furthermore, the foaming material comprises the following raw material components in parts by weight: 100 parts of polyether ester elastomer, 1-10 parts of MOF material loaded with crosslinking agent, and 2-5 parts of additives;

[0036] The MOF material is selected from at least one of ZIF-8, MIL-101, UiO-66, and MOF-5.

[0037] The crosslinking agent is selected from at least one of epoxy, isocyanate, and acid anhydride crosslinking agents. Specifically, the epoxy crosslinking agent is selected from compounds containing two or more epoxy groups (such as glycerol triglycidyl ether); the isocyanate crosslinking agent is selected from diphenylmethane diisocyanate and toluene diisocyanate; and the acid anhydride crosslinking agent is selected from maleic anhydride, maleic anhydride, trimellitic anhydride, and other multifunctional acid anhydrides.

[0038] The crosslinking agent is loaded onto the MOF material by the following method: the crosslinking agent is dissolved in an organic solvent, the MOF material powder is impregnated to fill the pores with the crosslinking agent solution, and after drying, the crosslinking agent is adsorbed and retained in the pore structure of the MOF.

[0039] The additives include nucleating agents, stabilizers, antioxidants, and lubricants. Specifically, the nucleating agents can be inorganic microparticles such as talc, calcium carbonate, and silica, used to increase the nucleation density of micropores, making the pores smaller and more uniform. The antioxidants are hindered phenols (such as antioxidants 168 and 1010) to prevent TPEE from yellowing due to thermal and oxidative aging during processing. The lubricant is microcrystalline wax, which can improve melt flow and additive dispersion.

[0040] Furthermore, the foamed material is prepared by a supercritical N2 physical foaming process. The specific preparation process is as follows: after uniformly mixing the raw materials, they are fed into an extruder or injection molding machine for heating and melting. Then, in the metering and mixing stage, supercritical nitrogen is introduced as a physical foaming agent to induce the formation of a uniform microporous structure.

[0041] During the foaming process, the MOF gradually releases the adsorbed crosslinking agent, which reacts with the TPEE melt to form a crosslinked network. Supercritical nitrogen is introduced as a physical foaming agent. Under high temperature and pressure, the nitrogen fully dissolves and diffuses into the molten TPEE matrix. Subsequently, the melt is rapidly depressurized through a die or mold, causing the dissolved gas to quickly precipitate and expand, inducing the formation of a uniform microporous structure. The introduced crosslinked network improves the melt strength, providing better support for the cells during growth, making them less prone to merging or rupture, thus resulting in a fine and uniformly distributed closed-cell foam structure.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] This invention provides a high-resilience polyether ester elastomer based on PO3G. By using PO3G modified with nanoparticle reinforcing agents, the physical cross-linking network of the polymer is made denser and more uniform, improving mechanical strength and resilience. It can be used as a matrix resin for high-performance foaming materials to meet the extreme demand for high resilience in high-end shoe midsoles, providing excellent elasticity and mechanical strength.

[0044] This invention utilizes MOF (Metal-Oxide-Foil) controlled-release crosslinking agent to achieve a more balanced crosslinking structure within TPEE (Polymer-Total-Effective) foam materials, thereby improving the overall performance of the foam materials. MOFs possess a large internal pore surface area, allowing for the pre-adsorption of a certain amount of crosslinking agent molecules through impregnation or mixing. This invention leverages MOF adsorption and storage of the crosslinking agent, gradually releasing it into the polymer matrix during heating, melting, and foaming. Specifically, during the TPEE melt foaming process, temperature triggers the gradual release and diffusion of the crosslinking agent into the polymer matrix to participate in the crosslinking reaction, significantly improving the spatiotemporal uniformity and stability of crosslinking. This solves the problems of uneven dispersion and uncontrolled reaction associated with directly adding crosslinking agents. The foam material formulation provided by this invention outperforms traditional TPEE foam systems in key indicators such as foaming ratio, dimensional stability, support, and resilience, meeting the stringent requirements of high-performance sports shoe midsoles for lightweight, high elasticity, and durable cushioning, and has broad application prospects. Attached Figure Description

[0045] Figure 1 SEM image of the polymer foam material prepared in Example 7;

[0046] Figure 2 The image shows a SEM image of the polymer foam material prepared in Comparative Example 5. Detailed Implementation

[0047] The following description is provided to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples and are not intended to limit the scope of the invention; other obvious variations will occur to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0048] Unless otherwise specified, the reagents used in the embodiments of this invention are all conventional commercial reagents. The main reagent information or sources used are as follows:

[0049] Terephthalic acid, CAS: 100-21-0;

[0050] Dimethyl terephthalate, CAS: 120-61-6;

[0051] 1,4-Butanediol, CAS: 110-63-4;

[0052] 1,3-Propanediol, CAS: 504-63-2;

[0053] Iron triacetylacetonate, CAS No.: 14024-18-1, Aladdin;

[0054] Tri-(hexafluoroacetylacetone) iron, CAS: 17786-67-3, Aladdin;

[0055] Ferric trifluoroacetylacetonate, CAS No.: 14526-22-8, Myriel;

[0056] Tetrabutyl titanate, CAS No.: 5593-70-4;

[0057] Zinc acetate, CAS No.: 557-34-6;

[0058] Triphenyl phosphite, CAS: 101-02-0;

[0059] Trimethyl phosphate, CAS: 512-56-1;

[0060] MOF-5(Zn) powder, CAS No.: 255367-66-9;

[0061] Glycerol triglycidyl ether, CAS No.: 13236-02-7;

[0062] Microcrystalline wax, CAS No.: 8001-75-0;

[0063] Example 1

[0064] The polyether ester elastomer was prepared by the following method: After purging with nitrogen, about 150.0 g (0.90 mol) of terephthalic acid, about 117.0 g (1.3 mol) of 1,4-butanediol, 0.2 g of catalyst (tetrabutyl titanate), and 0.15 g of stabilizer triphenyl phosphite were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to about 200 °C under normal pressure and stirring, and the reaction was carried out for 80 min. During the reaction, the by-products were discharged through a condenser.

[0065] In the later stage of the esterification reaction, under stirring and nitrogen protection, 125.0g of the pre-prepared PO3G pre-dispersion (PO3G is Daxiong Chemical H2400, and 4% by mass of organic montmorillonite Nanomer is added to the dried PO3G) ® I.44P (fully dispersed by ultrasound) was slowly added to the reactor, and the reaction continued for 40 min.

[0066] After esterification, the reaction temperature was raised to approximately 250°C for polycondensation. 0.12 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤50 Pa. The reaction continued under vacuum for 80 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0067] Example 2

[0068] The polyether ester elastomer was prepared by the following method: After purging with nitrogen, approximately 155.2 g (0.80 mol) of dimethyl terephthalate, approximately 108.0 g (1.2 mol) of 1,4-butanediol, 0.2 g of catalyst (tetrabutyl titanate), and 0.15 g of stabilizer triphenyl phosphite were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to approximately 200 °C under atmospheric pressure and stirring conditions, and the reaction was carried out for 80 min. During the reaction, the byproducts were discharged through a condenser.

[0069] In the later stage of the transesterification reaction, under stirring and nitrogen protection, 120.0 g of pre-prepared PO3G pre-dispersion (PO3G was SK ECOPROL H2700 from South Korea, dried PO3G) was mixed with 4.5% nano-silica from Evonik Chemicals AEROSIL. ® R 972 (fully dispersed by ultrasound) was slowly added to the reactor, and the reaction continued for 40 min.

[0070] After the transesterification reaction was completed, the reaction temperature was raised to approximately 250°C for polycondensation. 0.12 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤50 Pa. The reaction continued under vacuum for 80 min until the melt viscosity in the reactor significantly increased and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0071] Example 3

[0072] The polyether ester elastomer was prepared by the following method: After purging with nitrogen, approximately 155.2 g (0.80 mol) of dimethyl terephthalate, approximately 108.0 g (1.2 mol) of 1,4-butanediol, catalyst (0.07 g of iron triacetylacetone, 0.01 g of tetrabutyl titanate, and 0.035 g of zinc acetate) and stabilizer triphenyl phosphite (0.15 g) were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to approximately 160 °C under atmospheric pressure and stirring, and the reaction was carried out for 90 min. During the reaction, the byproducts were discharged through a condenser.

[0073] In the later stage of the transesterification reaction, under stirring and nitrogen protection, 126.0 g of the pre-prepared PO3G pre-dispersion solution (PO3G is SK ECOPROL H2700 from South Korea, and 4.5% of nano-silica AEROSIL® R 972 from Evonik Chemicals was added to the dried PO3G and it was fully dispersed by ultrasound) was slowly added to the reactor, and the reaction continued for 30 min.

[0074] After the transesterification reaction was completed, the reaction temperature was raised to approximately 245°C for polycondensation. 0.05 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 80 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0075] Example 4

[0076] The polyether ester elastomer was prepared as follows: After purging with nitrogen, approximately 165 g (0.85 mol) of dimethyl terephthalate, approximately 108.0 g (1.2 mol) of 1,4-butanediol, 0.05 g of tri(hexafluoroacetylacetone)ferric oxide, 0.02 g of tetrabutyl titanate, and 0.04 g of zinc acetate and 0.18 g of triphenyl phosphite stabilizer were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to approximately 170 °C under atmospheric pressure and stirring, and the reaction was carried out for 90 min. During the reaction, the byproducts were discharged through a condenser.

[0077] In the later stage of the transesterification reaction, under stirring and nitrogen protection, 130.0 g of pre-prepared PO3G pre-dispersion (PO3G was SK ECOPROL H2700 from South Korea, dried PO3G) was mixed with 5% by weight of nano-silica from Evonik Chemicals AEROSIL. ® R 972 (fully dispersed by ultrasound) was slowly added to the reactor, and the reaction continued for 30 min.

[0078] After the transesterification reaction was completed, the reaction temperature was raised to approximately 245°C for polycondensation. 0.06 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 90 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0079] Example 5

[0080] The polyether ester elastomer was prepared as follows: After purging with nitrogen, approximately 165 g (0.85 mol) of dimethyl terephthalate, approximately 91.3 g (1.2 mol) of 1,3-propanediol, 0.045 g of catalyst (0.03 g of iron trifluoroacetylacetone, 0.05 g of tetrabutyl titanate, and 0.05 g of zinc acetate) and 0.15 g of stabilizer trimethyl phosphate were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to approximately 175 °C under atmospheric pressure and stirring, and the reaction was carried out for 90 min. During the reaction, the byproducts were discharged through a condenser.

[0081] In the later stage of the transesterification reaction, under stirring and nitrogen protection, 115.0 g of the pre-prepared PO3G pre-dispersion (PO3G was Daxiong Chemical H2400, and 3% by weight of nano-silica AEROSIL from Evonik Chemical was added to the dried PO3G) ® R 972 (fully dispersed by ultrasound) was slowly added to the reactor, and the reaction continued for 30 min.

[0082] After the transesterification reaction was completed, the reaction temperature was raised to approximately 230°C for polycondensation. 0.03 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 90 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0083] Example 6

[0084] The polyether ester elastomer was prepared by the following method: After purging with nitrogen, about 150.0 g (0.90 mol) of terephthalic acid, about 99 g (1.3 mol) of 1,3-propanediol, catalyst (0.05 g of iron triacetylacetone, 0.02 g of tetrabutyl titanate, and 0.04 g of zinc acetate) and stabilizer trimethyl phosphate were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to about 160 °C under normal pressure and stirring, and the reaction was carried out for 90 min. During the reaction, the by-products were discharged through a condenser.

[0085] In the later stage of the esterification reaction, under stirring and nitrogen protection, 115.0 g of the pre-prepared PO3G pre-dispersion (PO3G was Daxiong Chemical H2400, and 6% by weight of nano-silica AEROSIL from Evonik Chemical was added to the dried PO3G) ® R972 (fully dispersed by ultrasound) was slowly added to the reactor, and the reaction continued for 30 minutes.

[0086] After esterification, the reaction temperature was raised to approximately 230°C for polycondensation. 0.02 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 90 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0087] Comparative Example 1

[0088] Compared to Example 3, unmodified PO3G was used, that is, PO3G without the addition of nanoparticle reinforcing agents.

[0089] The polyether ester elastomer was prepared by the following method: After purging with nitrogen, approximately 155.2 g (0.80 mol) of dimethyl terephthalate, approximately 108.0 g (1.2 mol) of 1,4-butanediol, catalyst (0.07 g of iron triacetylacetone, 0.01 g of tetrabutyl titanate, and 0.035 g of zinc acetate) and stabilizer triphenyl phosphite (0.15 g) were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to approximately 160 °C under atmospheric pressure and stirring, and the reaction was carried out for 90 min. During the reaction, the byproducts were discharged through a condenser.

[0090] In the later stage of the transesterification reaction, under stirring and nitrogen protection, 126.0 g of PO3G (PO3G is SKECOPROL H2700 from South Korea) was slowly added to the reactor, and the reaction continued for 30 min.

[0091] After the transesterification reaction was completed, the reaction temperature was raised to approximately 245°C for polycondensation. 0.05 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 80 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0092] Comparative Example 2

[0093] Compared to Example 3, the nanoparticle reinforcing agent is not premixed with PO3G; both are added together.

[0094] The polyether ester elastomer was prepared by the following method: After purging with nitrogen, approximately 155.2 g (0.80 mol) of dimethyl terephthalate, approximately 108.0 g (1.2 mol) of 1,4-butanediol, catalyst (0.07 g of iron triacetylacetone, 0.01 g of tetrabutyl titanate, and 0.035 g of zinc acetate) and stabilizer triphenyl phosphite (0.15 g) were added to a 500 mL reactor. After nitrogen purging, the temperature was raised to approximately 160 °C under atmospheric pressure and stirring, and the reaction was carried out for 90 min. During the reaction, the byproducts were discharged through a condenser.

[0095] In the later stages of the transesterification reaction, under stirring and nitrogen protection, approximately 5.7 g of nano-silica (Evonik Chemical AEROSIL) was added. ® R 972) and 120.3g of dry PO3G (SK ECOPROL H2700 from South Korea) were added together into the reactor and the reaction was continued for 30 min.

[0096] After the transesterification reaction was completed, the reaction temperature was raised to approximately 245°C for polycondensation. 0.05 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 80 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0097] Comparative Example 3

[0098] Compared to Example 3, the PO3G predispersant was added along with dimethyl terephthalate, 1,4-butanediol, and the catalyst.

[0099] The polyether ester elastomer was prepared as follows: After nitrogen purging, approximately 155.2 g (0.80 mol) of dimethyl terephthalate, approximately 108.0 g (1.2 mol) of 1,4-butanediol, catalyst (0.07 g of iron triacetylacetone, 0.01 g of tetrabutyl titanate, and 0.035 g of zinc acetate), stabilizer 0.15 g of triphenyl phosphite, and 126.0 g of pre-prepared PO3G pre-dispersion (PO3G was SK ECOPROL H2700 from South Korea; 4.5% by weight of nano-silica AEROSIL from Evonik Chemical was added to the dried PO3G). ® R 972 (fully dispersed by ultrasound), after nitrogen purging, is heated to about 160°C under normal pressure and stirring conditions, and reacted for 120 min. During the reaction, byproducts are discharged through a condenser.

[0100] After the transesterification reaction was completed, the reaction temperature was raised to approximately 245°C for polycondensation. 0.05 g of tetrabutyl titanate catalyst was added, and the system was gradually evacuated until the absolute pressure was ≤80 Pa. The reaction continued under vacuum for 80 min until the melt viscosity in the reactor increased significantly and the stirring torque stabilized. Heating was stopped, nitrogen was introduced to restore atmospheric pressure, and the molten polymer was extruded, cooled, and shaped to obtain polyether ester elastomer strips, which were then pelletized to obtain samples.

[0101] [Performance Testing of Polyether Elastomer Samples]

[0102] The samples prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to performance tests using conventional testing methods, specifically including:

[0103] 1. Intrinsic viscosity: Tested according to standard ISO1628-5, solvent is phenol-tetrachloroethane (mass ratio 1:1), test temperature is 25°C, and measured with an Ubbelohde viscometer.

[0104] 2. Mechanical properties: Tensile strength and elongation at break: According to the standard ASTM D638-14 "Standard Plastics - Tensile Properties Test Method", the specimens were tested using a universal testing machine at a tensile rate of 50 mm / min.

[0105] 3. Hardness: According to the standard ASTM D2240-15 "Standard Rubber Performance Test Methods - Determination of Hardness by Hardness Tester", a Shore D hardness tester was used to measure the hardness on a multi-layered laminated sample.

[0106] 4. Thermal stability: Thermogravimetric analysis (TGA) was used for testing according to general operating procedures. The 5% thermal weight loss temperature was measured in air at a rate of 10°C / min from room temperature to 600°C.

[0107] 5. Appearance and color: Visual inspection.

[0108] For detailed test results, please refer to Table 1.

[0109] Table 1. Performance test results of polyether ester elastomer samples

[0110]

[0111] As shown in Table 1, by pre-dispersing the nano-reinforcing particles with PO3G soft segments and introducing the pre-dispersion liquid in the later stage of the esterification / exchange reaction, a high-performance polyether ester elastomer was obtained. This elastomer exhibited high intrinsic viscosity (2.02-2.33 dL / g), indicating that the polymer has a high molecular weight and excellent tensile strength (30.5-40.2 MPa), elongation at break (390-450), while also possessing balanced hardness (40D-45D) and good thermal stability. Compared to the tetrabutyl titanate catalyst used in Examples 1 and 2, the iron-titanium-zinc composite catalyst system used in Examples 3-6 resulted in products with superior performance and a nearly colorless appearance.

[0112] Compared to the examples, Comparative Example 1, which did not include nanoparticles, showed significantly worse intrinsic viscosity and tensile strength, as well as a significant decrease in mechanical properties and thermal stability due to the lack of nanoparticle reinforcement. In Comparative Example 2, the nanoparticles were not pre-dispersed, resulting in deteriorated intrinsic viscosity and tensile strength, and decreased thermal stability, possibly related to the nanoparticles' ineffective participation in polymerization. In Comparative Example 3, the premature addition of PO3G was detrimental to product performance; premature addition may have led to its excessive participation in the hard segment polymerization process, affecting the formation of the polymer's regular structure and resulting in poor mechanical properties.

[0113] Preparation of Polymer Foaming Materials

[0114] Using the samples prepared in Examples 3, 4, and 6 as examples, polymer foaming materials were prepared.

[0115] Example 7

[0116] Polymer foaming materials are prepared using the following method:

[0117] Preparation of MOF material loaded with crosslinking agent: 10g of dried MOF-5(Zn) powder was impregnated in 80 ml of ethanol solution containing 8g of glycerol triglycidyl ether. After standing for 12 hours, the mixture was filtered and dried under reduced pressure at below 60°C to remove the ethanol, thus obtaining MOF-5 powder loaded with crosslinking agent (the effective crosslinking agent was 2.5g as determined by TGA).

[0118] Material mixing: Using 100g of the polyether ester elastomer (TPEE) prepared in Example 3 as the base resin, add 6g of the prepared MOF-5 powder loaded with crosslinking agent, 2g of nucleating agent talc powder, 0.5g of antioxidant 1010, and 1g of lubricant microcrystalline wax, and mix evenly in a high-speed mixer.

[0119] Melt foaming molding: The mixture is vacuum dried at 80°C for 2 hours, and then fed into a twin-screw extruder. The extruder temperatures from zone one to the die head are set to 180°C, 210°C, 230°C, and 225°C, respectively. In the metering section of the barrel, supercritical nitrogen gas (approximately 15 MPa pressure) accounting for 1.0% of the matrix resin mass is injected through a metering pump. After a uniform TPEE / nitrogen saturated melt system is formed by a static mixer, the melt is injected through a nozzle into a mold cavity preheated to 140°C. Rapid decompression foaming is performed, and after holding at this temperature for 5 minutes to set the shape, the material is cooled and demolded to obtain the polymer foam material.

[0120] Example 8

[0121] Using 100g of the polyether ester elastomer (TPEE) prepared in Example 4 as the base resin, and with all other aspects the same as in Example 7, a polymer foam material was prepared.

[0122] Example 9

[0123] Using 100g of the polyether ester elastomer (TPEE) prepared in Example 6 as the base resin, and with all other aspects the same as in Example 7, a polymer foam material was prepared.

[0124] Comparative Example 4

[0125] Compared to Example 7, polyether ester elastomer was directly used for foaming. The specific method is as follows: 100g of polyether ester elastomer (TPEE) prepared in Example 3 was used as the base resin, and additives (2g of nucleating agent talc, 0.5g of antioxidant 1010, and 1g of lubricant microcrystalline wax) were added. The mixture was mixed evenly in a high-speed mixer, and melt foaming was carried out in the same way to obtain a polymer foam material.

[0126] Comparative Example 5

[0127] Compared with Example 7, the following method was used to prepare the material: 100g of the polyether ester elastomer (TPEE) prepared in Example 3 was used as the base resin, and 1.5g of crosslinking agent glycerol triglycidyl ether, 2g of nucleating agent talc, 0.5g of antioxidant 1010, and 1g of lubricant microcrystalline wax were added. The mixture was mixed evenly in a high-speed mixer and then melt-foamed in the same way to obtain the polymer foam material.

[0128] [Performance Testing of Foamed Material Samples]

[0129] The performance of the polymer foam material samples prepared in Examples 7-9 and Comparative Examples 4-5 was tested, and the specific methods are as follows:

[0130] 1. Apparent density: Tested according to standard ASTM D792-2022;

[0131] 2. Rebound rate: Tested using a falling ball rebound tester according to standard ASTM D3574-21;

[0132] 3. Compression set: Tested according to standard ASTM D395-2016, method B (constant deformation), under the following conditions: 50% compression at 70°C for 22 hours.

[0133] 4. Microstructure of the bubble: The cross-sectional morphology of the sample after brittle fracture was observed using a scanning electron microscope. Figure 1 Here is an electron microscope image of the foamed material sample from Example 7. Figure 2 This is an electron microscope image of the foam material sample from Comparative Example 5.

[0134] For detailed results, please refer to Table 2.

[0135] Table 2 Performance test results of foamed material samples

[0136]

[0137] Note: "—" indicates that it has not been tested.

[0138] As shown in Table 2, the TPEE foam materials prepared using the TPEE material provided by this invention and the process employing a MOF-loaded crosslinking agent (Examples 7-9) exhibit low density (0.12-0.15 g / cm³), high resilience (≥78%), low compression set (≤7.1%), and uniform, fine cellular structure. These characteristics make the materials suitable for manufacturing midsole components for high-end athletic or casual shoes, providing lightweight, cushioning, durability, and high-resilience support. Comparative Example 4 shows high foam material density and deteriorating performance, indicating that the crosslinking step plays a crucial role in improving the foaming process of the TPEE foam material. Comparative Example 5 shows increased foam material density and deteriorating performance, with cell structure collapse, demonstrating that directly physically mixing the crosslinking agent cannot yield high-quality foam material. MOF loading allows for controlled release of the crosslinking agent, playing a positive role in stabilizing the cell structure and optimizing various properties during dynamic foaming.

[0139] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A process for the preparation of a PO3G group based high resilience polyether ester elastomer characterized in that, Includes the following steps: (1) Terephthalic acid or dimethyl terephthalate is reacted with diol monomer and modified PO3G in the presence of catalyst and stabilizer to obtain a prepolymer; (2) The obtained prepolymer is heated to the molten state, a small amount of organic titanium catalyst is added, and a melt polycondensation reaction is carried out under vacuum to obtain the product; Wherein, the modified PO3G in step (1) is PO3G modified with nanoparticle reinforcing agent; The modified PO3G in step (1) is formed by dispersing nanoparticle reinforcing agents in PO3G to form a pre-dispersion liquid; The nanoparticle reinforcing agent accounts for 0.1-15% of the weight of the PO3G; The nanoparticle reinforcing agent is selected from at least one of organic modified montmorillonite, nano silica, nano calcium carbonate, and graphene / graphene oxide. Step (1) The timing of adding modified PO3G is controlled in the middle and late stages of the esterification / exchange reaction.

2. The preparation method according to claim 1, characterized in that, The nanoparticle reinforcing agent accounts for 1-10% of the weight of the PO3G.

3. The preparation method according to claim 1, characterized in that, The PO3G mentioned in step (1) is a polytrimethylene ether diol with a weight-average molecular weight of 1000~4000; The PO3G accounts for 15%–50% of the total mass of the raw materials.

4. The preparation method according to claim 3, characterized in that, The PO3G accounts for 30%–40% of the total mass of the raw materials.

5. The preparation method according to claim 1, characterized in that, The diol monomer in step (1) is at least one of 1,4-butanediol or 1,3-propanediol; The molar ratio of terephthalic acid or dimethyl terephthalate to the diol monomer is 1:1.2 to 1.

5.

6. The preparation method according to claim 1, characterized in that, Step (1) The reaction temperature is 140~230℃ and the time is 1~4 hours; Step (2) The prepolymer is heated to 215~250℃ and the vacuum degree is controlled at 50~100Pa to carry out melt polycondensation reaction for 0.5~2 hours.

7. The preparation method according to claim 1, characterized in that, The catalyst in step (1) is an organotitanium catalyst or a composite catalyst with an iron-based complex catalyst as the main catalyst, and the stabilizer includes a heat stabilizer; the catalyst in step (2) is an organotitanium catalyst.

8. The high-resilience polyether ester elastomer based on PO3G group prepared by the preparation method according to any one of claims 1-7, characterized in that, The polyether ester elastomer has an intrinsic viscosity of 2.02-2.33 dL / g, a tensile strength of 30.5-40.2 MPa, an elongation at break of 390-450%, and a Shore hardness of 40D-45D.

9. The application of the PO3G-based high-resilience polyether ester elastomer as described in claim 8 in the preparation of foamed materials.

10. The application according to claim 9, characterized in that, The foaming material comprises the following raw material components in parts by weight: 100 parts of polyether ester elastomer, 1-10 parts of MOF material loaded with crosslinking agent, and 2-5 parts of additives; The MOF material is selected from at least one of ZIF-8, MIL-101, UiO-66, and MOF-5. The crosslinking agent is selected from at least one of epoxy, isocyanate, and acid anhydride crosslinking agents; The additives include nucleating agents, stabilizers, antioxidants, and lubricants.

11. The application according to claim 10, characterized in that, The foamed material is prepared by a supercritical N2 physical foaming process. The specific preparation process is as follows: after the raw materials are uniformly mixed, they are fed into an extruder or injection molding machine for heating and melting. Then, in the metering and mixing stage, supercritical nitrogen is introduced as a physical foaming agent to induce the formation of a uniform microporous structure.

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