High-bearing slow-rebound sponge and preparation method thereof

Abstract

The invention discloses a high-bearing-capacity slow-resilience sponge and a preparation method thereof. The sponge is prepared from the following raw materials in parts by weight: 100 parts of slow rebound polyether polyol, 5 to 15 parts of ternary deep eutectic solvent, 1 to 3 parts of diethanol amine, 1.5 to 2.5 parts of deionized water, 0.3 to 0.8 part of triethylene diamine solution, 0.2 to 0.7 part of stannous octoate, 1 to 2 parts of polysiloxane-polyether block copolymer and polyphenyl polymethylene polyisocyanate, wherein the index of the polyphenyl polymethylene polyisocyanate is 105 to 115. During preparation, the component A is mixed and defoamed at a low temperature of 15-18 DEG C, and is mixed and foamed with isocyanate. And when the core temperature is raised to 45-55 DEG C through foaming heat release, the ternary deep eutectic solvent is triggered to be dissociated by heating and participate in in-situ crosslinking. By utilizing the dissociation characteristic of the deep eutectic solvent at a specific temperature, a secondary hydrogen bond network is accessed to a main chain skeleton, and the cross-linked structure increases the interaction force between macromolecular chain segments and can disperse external compression stress, so that the support coefficient of the sponge is improved, the acting force and internal friction resistance between the macromolecular chain segments are increased, and the mechanical property of the sponge is improved. The synchronous improvement of the bearing capacity and the slow rebound characteristic of the sponge is realized.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam materials technology, specifically to a high load-bearing slow-rebound sponge and its preparation method. Background Technology

[0002] Slow rebound foam, due to its shock absorption and conformability to stressed surfaces, is widely used in home bedding, car seats, and medical rehabilitation equipment. Its slow rebound characteristic primarily relies on the internal friction of polyurethane polymer segments during compression and recovery, as well as the damping effect of the foam's internal microporous structure on airflow. However, conventional slow rebound foam typically suffers from low load-bearing capacity, easily exhibiting excessive deformation or even bottoming out under sustained or significant external compression, failing to provide sufficient support for the stressed surface.

[0003] To improve the load-bearing capacity of slow-rebound foam, existing technologies typically employ methods such as increasing the amount of isocyanate, introducing highly reactive small-molecule crosslinking agents, or directly adding rigid inorganic fillers to enhance the rigidity of the polyurethane skeleton. However, simply increasing the amount of isocyanate or highly reactive crosslinking agents can lead to excessive crosslinking density in the polyurethane backbone network, severely limiting the slippage and deformation capabilities of polymer chains. This can damage the original secondary structure within the polymer, resulting in a significant reduction in the foam's deformation recovery time and causing it to lose its original slow-rebound characteristics. On the other hand, while directly adding inorganic particulate fillers can improve the material's physical support to some extent, in actual foaming processes, the fillers can easily cause a sharp increase in the viscosity of the foaming system and uneven material dispersion, leading to structural defects such as localized bubble collapse or large-area closed cells. Simultaneously, it can significantly reduce the foam's tear resistance and long-term service life.

[0004] Therefore, how to effectively improve the compressive support of polyurethane foam while maintaining the stability of the foaming system and without damaging the slip properties of polymer chain segments, and how to solve the contradiction between high load-bearing capacity and slow rebound performance being difficult to improve simultaneously, is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The technical problem solved by this invention is that conventional slow rebound polyurethane foam has insufficient load-bearing capacity. When improving its support performance, the secondary network structure inside the polymer is often destroyed, causing it to lose or shorten its slow rebound characteristics, making it difficult to achieve a simultaneous improvement in high load-bearing capacity and slow rebound performance.

[0006] To address the above problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a high load-bearing slow-rebound sponge, which adopts the following technical solution: A high load-bearing slow-rebound sponge is made from raw materials comprising the following parts by weight: 100.0 parts of slow-rebound polyether polyol; 5.0-15.0 parts of ternary deep eutectic solvent; 1.0-3.0 parts of diethanolamine; 1.5-2.5 parts of deionized water; 0.3-0.8 parts of triethylenediamine solution; 0.2-0.7 parts of stannous octoate; 1.0-2.0 parts of polysiloxane-polyether block copolymer; and polyphenyl polymethylene polyisocyanate, the amount of which is calculated based on the total amount of active hydrogen in the system and the isocyanate index is controlled to be 105-115.

[0008] By adopting the above technical solution, this invention introduces a ternary deep eutectic solvent into the formulation, combined with a specific foaming reaction system, to achieve a simultaneous improvement in the sponge support coefficient and slow rebound time. The specific reaction mechanism is carried out according to the following steps: First, low-temperature premixing. The ternary deep eutectic solvent maintains a stable physical complex structure during the initial mixing stage and does not react with the polyether polyol and isocyanate. Second, foaming and pore-forming step. Deionized water reacts with isocyanate to produce carbon dioxide gas and release heat. At the same time, the slow rebound polyether polyol reacts with some isocyanate to construct the polyurethane main chain skeleton, forming a preliminary cell structure. This stage ensures a balance between the foaming rate and the gelation rate, avoiding collapse or closed cells caused by excessively rapid crosslinking in the early stage. Third, thermal dissociation step. As heat accumulates inside the foaming system, the core temperature of the foam rises. When the core temperature rises to the dissociation critical value of the ternary deep eutectic solvent, its internal hydrogen bond network dissociates under heat, releasing components with active hydroxyl and amino groups. Fourth, in-situ crosslinking step. The released active groups then undergo a covalent reaction with the residual isocyanate in the system. This reaction integrates a high-density secondary hydrogen bond network into the polyurethane backbone. Under macroscopic stress, the covalent cross-linking points enhance the interaction forces between polymer chain segments, dispersing external compressive stress and thus improving the sponge's support force under 65% compressive deformation. Simultaneously, the dense hydrogen bonds within the network generate internal friction and molecular chain slip resistance during compressive deformation and recovery, prolonging the time required for the sponge's structural recovery and maintaining its slow rebound characteristics.

[0009] Preferably, the ternary deep eutectic solvent is formed by the physical complexation of choline chloride, urea, and polyethylene glycol; the molar ratio of choline chloride, urea, and polyethylene glycol is 1:2:0.5~0.8. By adopting the above technical solution, polyethylene glycol is distributed on the outside of the basic network formed by choline chloride and urea, providing steric hindrance and additional hydrogen bonding. This structure can prevent the intrusion of water molecules at room temperature, maintain the undissociated state of the deep eutectic solvent in the early stage of foaming, and ensure that it only dissociates at specific high-temperature nodes.

[0010] Preferably, the specific preparation method of the ternary deep eutectic solvent is as follows: choline chloride is vacuum dried at 60℃~65℃ for 12~24 hours; choline chloride, urea, and polyethylene glycol are weighed according to the stated molar ratio, added to a reaction vessel, and heated to 80℃~85℃. The mixture is continuously stirred at a constant temperature of 300 rpm~500 rpm for 40 minutes~60 minutes to allow the components to undergo physical complexation. The mixture is then cooled to 20℃~25℃ to obtain a liquid ternary deep eutectic solvent. By adopting the above technical solution, under specific heating and mechanical stirring, the three raw materials are liquefied and a physical complex network is established, ensuring that the final solvent system has no free component residue and avoiding disordered side reactions in the early stage of foaming.

[0011] Preferably, the slow-rebound polyether polyol is a polypropylene oxide-ethylene oxide copolyether with glycerol as the initiator, having a number-average molecular weight of 3000 g / mol to 5000 g / mol, a functionality of 3, and a hydroxyl value of 33 mg KOH / g to 56 mg KOH / g; the polyethylene glycol has a number-average molecular weight of 200 g / mol to 400 g / mol; and the polyphenyl polymethylene polyisocyanate has an NCO group mass fraction of 30.0% to 32.0% and an average functionality of 2.6 to 2.8. By adopting the above technical solution, the reactivity and molecular chain length of the polymer monomers are defined, so that their reaction kinetics match the thermal release characteristics of the ternary deep eutectic solvent, ensuring that unreacted groups remain in the isocyanate during the system's temperature-induced dissociation stage to participate in the subsequent in-situ crosslinking.

[0012] Preferably, the product is made from the following raw materials in parts by weight: 100.0 parts of slow-rebound polyether polyol; 10.0 parts of ternary deep eutectic solvent; 2.0 parts of diethanolamine; 2.0 parts of deionized water; 0.5 parts of triethylenediamine solution; 0.4 parts of stannous octoate; 1.5 parts of polysiloxane-polyether block copolymer; and polyphenyl polymethylene polyisocyanate, the amount of which is controlled to have an isocyanate index of 110. By adopting the above technical solution, the proportions of the various raw materials are optimized, and the nucleation rate, main chain gelation rate, and component dissociation rate are synergistic, resulting in a high level of support coefficient and rebound time for the obtained sponge product.

[0013] Secondly, the present invention provides a method for preparing high load-bearing slow-rebound sponge, which adopts the following technical solution: A method for preparing high load-bearing slow-rebound sponge includes the following steps: S1, preparing component A: mixing slow-rebound polyether polyol, ternary deep eutectic solvent, diethanolamine, deionized water, triethylenediamine solution, stannous octoate and polysiloxane-polyether block copolymer, stirring at a constant temperature under cooling conditions, and then vacuum degassing to obtain component A; S2, preparing component B: taking polyphenyl polymethylene polyisocyanate As component B, the isocyanate index is calculated and controlled, and component B is kept at a constant temperature for later use; S3, mixing and foaming: component B is poured into component A at one time and mixed quickly, and then quickly poured into a preheated mold for free foaming; the exothermic foaming reaction causes the core temperature of the foam to rise, triggering the dissociation of the ternary deep eutectic solvent and participating in in-situ crosslinking; after the foam stops rising, it is placed in the mold to close and cure; S4, curing: the cured sponge is demolded and transferred to a drying oven for continuous curing, and cooled to room temperature to obtain the final product.

[0014] By adopting the above technical solution, this preparation method allows for segmented control of the material mixing process and the polymer polymerization and curing process in terms of temperature and time. Early-stage cooling control maintains the stability of the deep eutectic components; the mid-stage foaming and molding utilizes the exothermic properties of the polyurethane reaction itself as a thermal dissociation trigger to complete in-situ chemical crosslinking; and the late-stage curing eliminates internal structural stress within the macromolecules, improving the overall mechanical properties of the polymer.

[0015] Preferably, in step S1, the feed solution temperature is cooled and maintained at 15°C~18°C, and mechanically stirred at 1000 rpm~1500 rpm for 10 to 15 minutes at this temperature, followed by degassing under a vacuum of 0.08 MPa~0.1 MPa for 3 to 5 minutes. By adopting the above technical solution, the feed solution temperature of 15°C to 18°C ​​provides a low-temperature environment, preventing the frictional heat generated by stirring from prematurely damaging the deep eutectic solvent network. Vacuum degassing removes microbubbles from the inside of the material, preventing structural inhomogeneity and large pores inside the sponge.

[0016] Preferably, in step S2, component B is kept at a constant temperature of 20°C to 25°C; in step S3, the mixing speed is 2500 rpm to 3000 rpm, and the mixing time is 6 to 8 seconds. By adopting the above technical solution, high-speed shearing is used to ensure uniform mixing of the two components, guaranteeing the synchronicity of foaming and nucleation and the consistency of cell distribution.

[0017] Preferably, in step S3, the preheated mold temperature is 35°C~40°C; when the foam core temperature rises to 45°C~55°C, the ternary deep eutectic solvent is triggered to dissociate; the ambient temperature for static mold closing and curing is 20°C~25°C, and the time is 10 minutes~15 minutes. By adopting the above technical solution, the mold bottom temperature of 35°C to 40°C reduces the surface heat loss-induced surface closed-cell phenomenon. 45°C to 55°C is used as the trigger threshold. At this temperature, the main foaming reaction rate decreases, the skeleton is initially shaped, the deep eutectic solvent dissociates and replenishes crosslinking points in this temperature range, without interfering with the formation of the main network, and at the same time, the crosslinking points are solidified between the main chains, achieving synchronous adjustment of load-bearing and resilience performance.

[0018] Preferably, in step S4, the continuous curing temperature is 60°C to 65°C, and the time is 24 to 48 hours. By adopting the above technical solution, the remaining free groups in the system are fully reacted, thereby improving the stability of the polymer structure and the dimensional stability of the final product.

[0019] This invention provides a high-load-bearing, slow-rebound sponge and its preparation method. It has the following beneficial effects:

[0020] 1. This invention introduces a ternary deep eutectic solvent and combines it with a temperature-controlled heat release process, enabling the sponge to maintain slow rebound characteristics while possessing high load-bearing capacity. The ternary deep eutectic solvent dissociates upon heating at a core foaming temperature of 45°C to 55°C, releasing active hydroxyl and amino groups that undergo in-situ crosslinking reactions with residual isocyanates in the system, integrating a secondary hydrogen bond network into the polyurethane backbone. This crosslinking structure increases the interaction forces between polymer chain segments, dispersing external compressive stress and thus improving the sponge's support coefficient. Simultaneously, the dense hydrogen bonds within the network generate internal friction and molecular chain slip resistance during compression deformation and recovery, extending the sponge's deformation recovery time.

[0021] 2. This invention ensures the stability of cell formation in the early stage of sponge foaming by controlling the initial solution temperature and utilizing the structural characteristics of the ternary deep eutectic solvent. The polyethylene glycol in the ternary deep eutectic solvent provides steric hindrance by distributing on the outer side of the basic network. Combined with a low-temperature premixing condition of 15°C to 18°C, the solvent remains in a physically complexed state in the early stage of foaming and does not participate in the foaming reaction. This avoids the premature participation of active groups in the reaction, which would disrupt the foaming balance between water and isocyanate, maintains the synergy between the early foaming rate and gelation rate, and prevents defects such as foam collapse or closed cells in the sponge.

[0022] 3. This invention improves the structural uniformity and mechanical stability of the finished sponge by optimizing each step of the preparation method. In the component formulation stage, vacuum degassing is used to remove microbubbles from the materials, combined with subsequent short-time high-speed stirring and molding, ensuring uniform mixing of the reactants and guaranteeing the consistency of pore size and distribution within the sponge. After demolding, a continuous curing step at 60°C to 65°C is added to promote the complete reaction of residual free groups in the system, eliminate internal structural stress within the macromolecules, and improve the dimensional stability of the final sponge product. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Please see the appendix Figure 1 This invention provides a high load-bearing slow-rebound sponge and its preparation method.

[0026] I. Raw materials:

[0027] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0028] The slow-rebound polyether polyol, chemically named a glycerol-initiated polypropylene oxide-ethylene oxide copolyether, has the CAS number 9003-11-6. This polymer is formed by ring-opening copolymerization of propylene oxide and ethylene oxide, with repeating units arranged in a random copolymer structure. Its number-average molecular weight is 3000 g / mol to 5000 g / mol, its functionality is 3, and its hydroxyl value is 33 mg KOH / g to 56 mg KOH / g.

[0029] Choline chloride, chemical formula C5H14ClNO, CAS number 67-48-1, purity greater than or equal to 98.0%.

[0030] Urea, with the chemical formula CH4N2O and CAS number 57-13-6, has a purity of ≥99.0%.

[0031] Polyethylene glycol, chemically known as α-hydro-ω-hydroxypoly(oxy-1,2-ethylenediol), CAS number 25322-68-3, is a linear polymer with hydroxyl groups at the ends. Its weight-average molecular weight ranges from 200 g / mol to 400 g / mol, and its hydroxyl value ranges from 280 mg KOH / g to 560 mg KOH / g.

[0032] Polyphenyl polymethylene polyisocyanate, CAS number 9016-87-9. This polymer contains isocyanate groups, with an NCO group mass fraction of 30.0% to 32.0% and an average functionality of 2.6 to 2.8.

[0033] Example of preparation of ternary deep eutectic solvent: Choline chloride was dried in a vacuum drying oven at 60°C to 65°C for 12 to 24 hours. Choline chloride, urea, and polyethylene glycol were accurately weighed according to a molar ratio of 1:2:0.5 to 1:2:0.8. The weighed substances were added to a jacketed glass reactor equipped with a mechanical stirrer, condenser, and temperature sensor. The reaction was started, and the system temperature was raised to 80°C to 85°C by the jacket heating system. Within this temperature range, the mixture was continuously stirred at a constant speed of 300 rpm to 500 rpm for 40 to 60 minutes. During this process, solid choline chloride and urea liquefied under the action of polyethylene glycol and under heating conditions, forming a colorless or pale yellow homogeneous and transparent liquid. Heating was stopped, and the mixture was cooled to 20°C to 25°C with stirring at 100 rpm to obtain a liquid ternary deep eutectic solvent. This solvent was sealed and stored away from light for later use.

[0034] II. Preparation Example:

[0035] Preparation Example 1: This preparation example provides a ternary deep eutectic solvent, comprising the following steps: Choline chloride is dried in a vacuum drying oven at 60°C for 12 hours. Based on a molar ratio of choline chloride, urea, and polyethylene glycol (using a product with a number average molecular weight of 200 g / mol), 139.6 g of choline chloride, 120.1 g of urea, and 100.0 g of polyethylene glycol are accurately weighed. The weighed substances are added to a jacketed glass reactor equipped with a mechanical stirrer, a condenser, and a temperature sensor. The reactor jacket heating system is turned on to raise the system temperature to 80°C. At this temperature, the mixture is continuously stirred at a constant speed of 300 rpm for 40 minutes. During this process, the components undergo physical complexation through intermolecular hydrogen bonding, transforming from a solid to a liquid state. Heating is stopped, and the mixture is stirred at 100 rpm while cooling to 20°C to obtain a homogeneous and transparent liquid ternary deep eutectic solvent. This solvent is sealed and stored in a light-proof container for later use.

[0036] Preparation Example 2: This preparation example provides a ternary deep eutectic solvent, comprising the following steps: Choline chloride is dried in a vacuum drying oven at 62°C for 18 hours. Based on a molar ratio of choline chloride, urea, and polyethylene glycol (using a product with a number average molecular weight of 200 g / mol), 139.6 g of choline chloride, 120.1 g of urea, and 130.0 g of polyethylene glycol are accurately weighed. The weighed substances are added to a jacketed glass reactor equipped with a mechanical stirrer, a condenser, and a temperature sensor. The reactor jacket heating system is turned on to raise the system temperature to 82°C. At this temperature, the mixture is continuously stirred at a constant speed of 400 rpm for 50 minutes. During this process, the components undergo physical complexation through intermolecular hydrogen bonding, transforming from a solid to a liquid state. Heating is stopped, and the mixture is stirred at 100 rpm to cool to 22°C to obtain a homogeneous and transparent liquid ternary deep eutectic solvent. This solvent is sealed and stored in a light-proof container for later use.

[0037] Preparation Example 3: This preparation example provides a ternary deep eutectic solvent, comprising the following steps: Choline chloride is dried in a vacuum drying oven at 65°C for 24 hours. Based on a molar ratio of choline chloride, urea, and polyethylene glycol (using a product with a number average molecular weight of 200 g / mol), 139.6 g of choline chloride, 120.1 g of urea, and 160.0 g of polyethylene glycol are accurately weighed. The weighed substances are added to a jacketed glass reactor equipped with a mechanical stirrer, a condenser, and a temperature sensor. The reactor jacket heating system is turned on to raise the system temperature to 85°C. At this temperature, the mixture is continuously stirred at a constant speed of 500 rpm for 60 minutes. During this process, the components undergo physical complexation through intermolecular hydrogen bonding, transforming from a solid to a liquid state. Heating is stopped, and the mixture is stirred at 100 rpm while cooling to 25°C to obtain a homogeneous and transparent liquid ternary deep eutectic solvent. This solvent is sealed and stored in a light-proof container for later use.

[0038] III. Implementation Examples:

[0039] Example 1: This example provides a high-load-bearing slow-rebound sponge based on a temperature-controlled heat release process. Its preparation includes the following steps: In a mixing tank equipped with a jacketed cooling device, 100.0 parts by weight of slow-rebound polyether polyol (number-average molecular weight of 3000 g / mol), 5.0 parts by weight of the ternary deep eutectic solvent obtained in Preparation Example 1, 1.0 parts by weight of diethanolamine, 1.5 parts by weight of deionized water, 0.3 parts by weight of triethylenediamine solution, 0.2 parts by weight of stannous octoate, and 1.0 parts by weight of polysiloxane-polyether block copolymer are added sequentially. Cooling water circulation is activated to cool the liquid in the mixing tank and maintain it at 15°C. At this temperature, the mixture is mechanically stirred at 1000 rpm for 10 minutes, followed by degassing under a vacuum of 0.08 MPa for 3 minutes to obtain component A. Polyphenyl polymethylene polyisocyanate was used as component B. The isocyanate index was calculated and controlled to be 105 based on the total active hydrogen content of each substance in component A. Component B was kept at a constant temperature of 20°C for later use. The heated component B was poured into a mixing container containing component A and immediately mixed at 2500 rpm for 6 seconds. Then, it was quickly poured into a mold preheated to 35°C for free foaming. As the foaming reaction exothermicly increased the core temperature of the foam to 45°C, the ternary deep eutectic solvent dissociated and participated in in-situ crosslinking. After the foam stopped rising, it was left to stand in the mold at room temperature (20°C) for 10 minutes to cure. After demolding, it was transferred to a constant temperature forced-air drying oven and continuously cured at 60°C for 24 hours. The finished product was obtained after cooling to room temperature.

[0040] Example 2: This example provides a high-load-bearing slow-rebound sponge based on a temperature-controlled heat release process. Its preparation includes the following steps: In a mixing tank equipped with a jacketed cooling device, 100.0 parts by weight of slow-rebound polyether polyol (number-average molecular weight 4000 g / mol), 10.0 parts by weight of the ternary deep eutectic solvent obtained in Preparation Example 2, 2.0 parts by weight of diethanolamine, 2.0 parts by weight of deionized water, 0.5 parts by weight of triethylenediamine solution, 0.4 parts by weight of stannous octoate, and 1.5 parts by weight of polysiloxane-polyether block copolymer are added sequentially. Cooling water circulation is activated to cool the liquid in the mixing tank and maintain it at 16°C. At this temperature, the mixture is mechanically stirred at 1200 rpm for 12 minutes, followed by degassing under a vacuum of 0.09 MPa for 4 minutes to obtain component A. Polyphenyl polymethylene polyisocyanate was used as component B. Based on the total active hydrogen content of each substance in component A, the isocyanate index was calculated and controlled to be 110. Component B was kept at a constant temperature of 22°C for later use. The heated component B was poured into a mixing container containing component A and immediately mixed at 2800 rpm for 7 seconds. Then, it was quickly poured into a mold preheated to 38°C for free foaming. As the foaming reaction exothermicly increased the core temperature of the foam to 50°C, the ternary deep eutectic solvent dissociated and participated in in-situ crosslinking. After the foam stopped rising, it was left to stand in the mold at room temperature (22°C) for 12 minutes to cure. After demolding, it was transferred to a constant temperature drying oven and continuously cured at 62°C for 36 hours. The finished product was obtained after cooling to room temperature.

[0041] Example 3: This example provides a high-load-bearing slow-rebound sponge based on a temperature-controlled heat release process. Its preparation includes the following steps: In a mixing tank equipped with a jacketed cooling device, 100.0 parts by weight of slow-rebound polyether polyol (number-average molecular weight of 5000 g / mol), 15.0 parts by weight of the ternary deep eutectic solvent obtained in Preparation Example 3, 3.0 parts by weight of diethanolamine, 2.5 parts by weight of deionized water, 0.8 parts by weight of triethylenediamine solution, 0.7 parts by weight of stannous octoate, and 2.0 parts by weight of polysiloxane-polyether block copolymer are added sequentially. Cooling water circulation is activated to cool the liquid in the mixing tank and maintain it at 18°C. At this temperature, the mixture is mechanically stirred at 1500 rpm for 15 minutes, followed by degassing under a vacuum of 0.1 MPa for 5 minutes to obtain component A. Polyphenyl polymethylene polyisocyanate was used as component B. Based on the total active hydrogen content of each substance in component A, the isocyanate index was calculated and controlled to be 115. Component B was kept at a constant temperature of 25°C for later use. The heated component B was poured into a mixing tank containing component A and immediately mixed at 3000 rpm for 8 seconds. Then, it was quickly poured into a mold preheated to 40°C for free foaming. As the foaming reaction exothermicly increased the core temperature of the foam to 55°C, the ternary deep eutectic solvent dissociated and participated in in-situ crosslinking. After the foam stopped rising, it was left to stand in the mold at room temperature (25°C) for 15 minutes to cure. After demolding, it was transferred to a constant temperature drying oven and continuously cured at 65°C for 48 hours. The finished product was obtained after cooling to room temperature.

[0042] IV. Comparative Examples:

[0043] Comparative Example 1: Compared with Example 2, the difference is that the ternary deep eutectic solvent obtained from Preparation Example 2 was not added to the formulation of component A, and because this part of the active hydrogen-rich component was removed, the amount of polyphenyl polymethylene polyisocyanate in component B was recalculated based on the total amount of remaining active hydrogen in component A and the isocyanate index was controlled to be 110. All other aspects are the same.

[0044] Comparative Example 2: Compared with Example 2, the difference is that the binary deep eutectic solvent obtained in Preparation Example 2 was replaced with an equal weight of binary deep eutectic solvent in the formulation of component A. This binary deep eutectic solvent was prepared solely by physical complexation of choline chloride and urea at a molar ratio of 1:2 at 82°C, and did not contain polyethylene glycol, i.e., it lacked the steric hindrance protective layer of liquid-phase solvation. Everything else was the same.

[0045] Comparative Example 3: Compared with Example 2, the difference is that the ternary deep eutectic solvent was not prepared in advance. Instead, the same amount of free choline chloride, free urea and free polyethylene glycol as in 10.0 parts by weight of the product of Example 2 was directly added to the mixing tank to prepare component A. That is, the components did not form a hydrogen bond eutectic network in advance. All other aspects are the same.

[0046] Comparative Example 4: Compared with Example 2, the difference is that the temperature control of the liquid in the A group during the distribution and degassing process is the conventional room temperature of 25°C, instead of strictly cooling and maintaining it at 16°C, that is, the low temperature locking process is not performed, and the rest are the same.

[0047] V. Test Example:

[0048] Test Example 1: Testing of the Physical and Mechanical Properties and Rebound Characteristics of Sponge

[0049] This test example is used to determine the density, indentation hardness, support coefficient, and recovery time of the sponge samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4.

[0050] The cured sponge samples obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were placed in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 24 hours. The samples were cut into test blocks with a length of 380mm, a width of 380mm, and a thickness of 50mm using a band saw. The volume and mass of the test blocks were measured and the apparent density was calculated according to GB / T6343 standard. The indentation hardness and support coefficient were determined using a universal testing machine according to GB / T10807 standard. A circular pressure plate with a diameter of 200mm was used to compress the sample downwards at a speed of 100mm / min. The indentation force values ​​when the deformation reached 25% and 65% were recorded, denoted as IFD25 and IFD65, respectively. The support coefficient was calculated from the ratio of IFD65 to IFD25. Referring to the relevant testing standards for slow-rebound polyurethane foam, the sponge sample was compressed to 25% of its original thickness and held for 1 minute. The pressure plate was then released, and the time required for the sponge to recover to 90% of its original thickness from the moment of release was recorded. Each test was independently repeated 3 times, and the arithmetic mean was taken.

[0051] The test data is shown in the table below.

[0052] Table 1. Test results of physical and mechanical properties of sponge samples from each embodiment and comparative example.

[0053]

[0054] Data and Mechanism Conclusions:

[0055] Test results show that the support coefficients of the sponge samples in Examples 1 to 3 ranged from 2.72 to 2.98, and the recovery times ranged from 4.3 seconds to 7.1 seconds. Compared with Comparative Example 1, the addition of a ternary deep eutectic solvent improved the IFD65 value and support coefficient of the sponge, and prolonged the recovery time. Choline chloride and urea in the ternary deep eutectic solvent release hydroxyl and amino groups after thermally triggered dissociation, undergoing in-situ crosslinking reactions with isocyanates in the system. This crosslinking integrates a physical hydrogen bond network into the polyurethane backbone, increasing the interaction forces between polymer chains, dispersing stress, and improving the support force under 65% compression. During deformation recovery, secondary hydrogen bonds generate internal friction and molecular chain slip resistance, prolonging the deformation recovery time of the sponge. Comparative Example 2 used a polyethylene glycol-free binary deep eutectic solvent. Due to the lack of steric hindrance in the macromolecular chains, choline chloride and urea had their hydrogen bond structures disrupted by water molecules and participated in the reaction during the initial foaming stage, leading to an imbalance between foaming and gelation reactions and uneven crosslinking of the polymer network, resulting in a support coefficient of 2.18. Comparative Example 3 directly added each free component without pre-complexation, resulting in a disordered reaction during component mixing. This failed to provide concentrated network crosslinking points at specific temperature nodes, with an IFD65 value of 201.7N. Comparative Example 4 was premixed at room temperature (25°C) without low-temperature locking. The deep eutectic solvent dissociated during the A-component stage. The dissociated active groups reacted upon the addition of component B, affecting the delayed milky period and cell nucleation, with a support coefficient of 2.11 and a recovery time of 2.1 seconds. The low-temperature premixing and self-exothermic foaming unlocking process of the embodiments allowed the initial foaming and pore-forming reactions of water and isocyanate to proceed independently. When the system temperature reached the critical value of 45°C to 55°C, the ternary deep eutectic solvent underwent thermal dissociation and participated in the later in-situ crosslinking, maintaining the integrity of the cell structure and the orderliness of the network crosslinking.

[0056] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-load-bearing, slow-rebound sponge, characterized in that, Made from the following ingredients in parts by weight: 100.0 parts of slow-rebound polyether polyol; 5.0–15.0 parts of ternary deep eutectic solvent; Diethanolamine 1.0–3.0 parts; 1.5 to 2.5 parts deionized water; 0.3–0.8 parts of triethylenediamine solution; Stannous octoate 0.2–0.7 parts; 1.0 to 2.0 parts of polysiloxane-polyether block copolymer; The amount of polyphenyl polymethylene polyisocyanate added is calculated based on the total amount of active hydrogen in the system and the isocyanate index is controlled to be 105~115.

2. The high load-bearing slow-rebound sponge according to claim 1, characterized in that, The ternary deep eutectic solvent is formed by the physical complexation of choline chloride, urea and polyethylene glycol; the molar ratio of choline chloride, urea and polyethylene glycol is 1:2:0.5~0.

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3. The high load-bearing slow-rebound sponge according to claim 2, characterized in that, The specific preparation method of the ternary deep eutectic solvent is as follows: choline chloride is vacuum dried at 60℃~65℃ for 12~24 hours; choline chloride, urea and polyethylene glycol are weighed according to the molar ratio, added to a reaction vessel, heated to 80℃~85℃, and stirred continuously at a constant temperature of 300 rpm~500 rpm for 40 minutes~60 minutes to allow the components to undergo physical complexation, and then cooled to 20℃~25℃ to obtain a liquid ternary deep eutectic solvent.

4. The high load-bearing slow-rebound sponge according to claim 1, characterized in that, The slow-rebound polyether polyol is a polypropylene oxide-ethylene oxide copolyether with glycerol as the initiator, having a number-average molecular weight of 3000 g / mol to 5000 g / mol, a functionality of 3, and a hydroxyl value of 33 mg KOH / g to 56 mg KOH / g; the polyethylene glycol has a number-average molecular weight of 200 g / mol to 400 g / mol; and the polyphenyl polymethylene polyisocyanate has an NCO group mass fraction of 30.0% to 32.0% and an average functionality of 2.6 to 2.

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5. The high load-bearing slow-rebound sponge according to claim 1, characterized in that, It is made from the following raw materials in parts by weight: 100.0 parts of slow-rebound polyether polyol; 10.0 parts of ternary deep eutectic solvent; 2.0 parts of diethanolamine; 2.0 parts of deionized water; 0.5 parts of triethylenediamine solution; 0.4 parts of stannous octoate; 1.5 parts of polysiloxane-polyether block copolymer; and polyphenyl polymethylene polyisocyanate, the amount of which is controlled to have an isocyanate index of 110.

6. A method for preparing a high-load-bearing slow-rebound sponge according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of component A: Mix slow rebound polyether polyol, ternary deep eutectic solvent, diethanolamine, deionized water, triethylenediamine solution, stannous octoate and polysiloxane-polyether block copolymer, stir at a constant temperature under cooling conditions, and then degas under vacuum to obtain component A. S2. Preparation of component B: Take polyphenyl polymethylene polyisocyanate as component B, calculate and control the isocyanate index, and keep component B at a constant temperature for later use. S3. Mixing and foaming molding: Pour component B into component A at once and mix quickly, then quickly pour into a preheated mold for free foaming; the exothermic foaming reaction causes the core temperature of the foam to rise, triggering the dissociation of the ternary deep eutectic solvent and its participation in in-situ crosslinking; after the foam stops rising, let it stand in the mold to close and solidify. S4. Curing: Demold the solidified sponge and transfer it to a drying oven for continuous curing. Cool to room temperature to obtain the final product.

7. The method for preparing a high load-bearing slow-rebound sponge according to claim 6, characterized in that, In step S1, the temperature of the liquid is cooled and maintained at 15°C to 18°C. At this temperature, the liquid is mechanically stirred at a speed of 1000 rpm to 1500 rpm for 10 to 15 minutes, followed by degassing under a vacuum of 0.08 MPa to 0.1 MPa for 3 to 5 minutes.

8. The method for preparing a high load-bearing slow-rebound sponge according to claim 6, characterized in that, In step S2, component B is kept at a constant temperature of 20℃~25℃; in step S3, the mixing speed is 2500 rpm~3000 rpm and the mixing time is 6 seconds~8 seconds.

9. The method for preparing a high load-bearing slow-rebound sponge according to claim 6, characterized in that, In step S3, the preheated mold temperature is 35℃~40℃; when the foam core temperature rises to 45℃~55℃, the ternary deep eutectic solvent dissociation is triggered; the ambient temperature for static mold closing and curing is 20℃~25℃, and the time is 10 minutes~15 minutes.

10. The method for preparing a high load-bearing slow-rebound sponge according to claim 6, characterized in that, In step S4, the continuous aging temperature is 60℃~65℃, and the time is 24 hours~48 hours.

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