Manufacturing method of high-strength toughened sponge

Abstract

The invention discloses a manufacturing method of high-strength toughened sponge, and belongs to the technical field of foaming materials, and the manufacturing method comprises the following steps: S1, mixing furyl polyol and bismaleimide, and heating for reaction to obtain a prepolymer; s2, mixing the prepolymer with a raw material containing polyether polyol to obtain a first component; s3, mixing the prepolymer with a raw material containing polyether polyol to obtain a second component; s4, mixing a part of the first component with a part of the second component to obtain a third component; s5, respectively mixing the first component, the second component and the third component with isocyanate to obtain a first foaming solution, a second foaming solution and a third foaming solution; s6, the three foaming solutions are injected into a mold for foaming, and polyurethane sponge is obtained; the polyurethane sponge disclosed by the invention has relatively high strength and toughness, and internal cracks can be repaired through heat.

Description

Technical Field

[0001] The invention relates to the technical field of foaming materials, and in particular to a method for preparing a high-strength toughened sponge. Background Art

[0002] As a common foaming material, sponge is widely used in mechanical equipment, vehicles, electronic products and building structures. Its unique physical properties such as energy absorption and shock absorption make it an indispensable component in many fields. In industrial equipment, automotive industry, electronic products and other fields, sponge can be made into a buffering and shock-absorbing structure to extend the life of industrial equipment, automotive parts or electronic components by absorbing mechanical vibrations. However, as a buffering and shock-absorbing structure, sponge is prone to cracks after long-term compression and stretching. Once cracks appear inside the sponge, the cracks will spread rapidly when it continues to withstand external forces, thereby affecting the buffering and shock-absorbing performance of the sponge.

[0003] Based on the above situation, a Chinese patent with publication (announcement) number CN115368707A discloses a plant fiber reinforced foamed composite material, a preparation method and application thereof, wherein the foamed composite material includes a polymer matrix and a reinforcing phase, the polymer matrix is formed by a matrix material mixture including a resin matrix and an additive, and the reinforcing phase is formed by plant fiber embedded bars obtained after weaving plant fibers; the plant fiber embedded bars are obtained by weaving plant fibers, and a matrix material mixture is provided, the matrix material mixture includes a resin matrix and an additive, the resin matrix is a thermoplastic resin matrix or a thermosetting resin matrix, the plant fiber embedded bars are placed in the matrix material mixture, and foaming treatment and curing treatment are performed in sequence to obtain a plant fiber reinforced foamed composite material.

[0004] The above patent document discloses a foamed composite material with built-in fibers and a preparation method thereof. The foamed composite material uses plant fibers as a skeleton to directionally enhance the mechanical properties such as compression fatigue performance of the foamed composite material. The foamed composite material improves the overall structural stability through the internal plant fibers, but the foamed material formed by foaming the matrix material mixture serves as the main buffer structure and its own mechanical properties are not improved by the addition of plant fibers. The plant fibers can enable the foamed composite material to maintain its original structure when cracks appear in the foamed material, but the cracks in the foamed material will reduce the compressive resistance and rebound performance of its internal pore structure, thereby reducing the buffering, rebound and other properties of the foamed composite material. Once cracks appear inside the foamed composite material, the cracks will spread at a faster rate, and the foamed composite material cannot eliminate the cracks or prevent the spread of the cracks, resulting in the service life of the foamed composite material quickly reaching the end after cracks appear inside. Therefore, there is still room for improvement in extending the service life of the foamed composite material. Summary of the Invention

[0005] In view of the technical defects existing in the background technology, the present invention proposes a method for preparing a high-strength toughened sponge, which solves the above technical problems and meets practical needs. The specific technical solution is as follows: A method for preparing a high-strength toughened sponge comprises the following steps: S1. Put furanyl polyol and bismaleimide into a reaction kettle containing a reaction solvent and stir them evenly. After the materials are completely dissolved, heat them to react. After the reaction is complete, evaporate the reaction solvent to obtain a prepolymer; S2, mixing the prepolymer with the first polyether polyol, aramid nanofibers, a chain extender, deionized water, a crosslinking agent, a catalyst, and a dispersant to obtain a first component; S3, mixing the prepolymer with the second polyether polyol, aramid nanofibers, a chain extender, deionized water, a crosslinking agent, a catalyst, and a dispersant to obtain a second component; S4, taking a portion of the first component and mixing a portion of the second component to obtain a third component; S5, mixing the remaining first component with isocyanate and stirring evenly to obtain a first foaming liquid, mixing the remaining second component with isocyanate and stirring evenly to obtain a second foaming liquid, and mixing the third component with isocyanate and stirring evenly to obtain a third foaming liquid; S6. Inject half of the first foaming liquid, half of the third foaming liquid, all of the second foaming liquid, the other half of the third foaming liquid, and the other half of the first foaming liquid into the mold in sequence, close the mold and heat to foam, and after foaming, cool and mature, open the mold to obtain a polyurethane sponge.

[0006] As a further technical solution of the present invention, the furan-based polyol is selected from 2,5-furan dimethanol, 2,5-tetrahydrofuran dimethanol, or a mixture of the two; the bismaleimide is selected from 4,4'-bismaleimidodiphenylmethane, 1,6-bismaleimidohexane, or a mixture of the two.

[0007] As a further technical solution of the present invention, the reaction solvent is selected from one or more of acetone, toluene, and tetrahydrofuran; in the reactor of step S1, the molar ratio of the furan-based polyol and the furan group to the maleimide group in the bismaleimide is (1-1.2):1, and the reactor is heated to 60-80° C. while stirring to carry out the DA reaction.

[0008] As a further technical solution of the present invention, the functionality of the first polyether polyol is 4 to 6, and the first component includes the following components by mass percentage: 10% to 20% prepolymer, 59% to 79% first polyether polyol, 3% to 6% aramid nanofiber, 4% to 8% chain extender, 2% to 4% deionized water, 1% to 2% crosslinking agent, 0.5% to 1% catalyst, and 0.2% to 0.5% dispersant.

[0009] As a further technical solution of the present invention, the functionality of the second polyether polyol is 2 to 3, and the second component includes the following components by mass percentage: 10% to 20% prepolymer, 54% to 77% second polyether polyol, 5% to 10% aramid nanofiber, 4% to 8% chain extender, 2% to 4% deionized water, 1% to 2% crosslinking agent, 0.5% to 1% catalyst, and 0.5% to 1% dispersant.

[0010] As a further technical solution of the present invention, in step S4, the mass ratio of the first component to the second component in the third component is 1:1; In step S5, the mass ratio of the first foaming liquid, the second foaming liquid, and the third foaming liquid is 1:(1-3):0.5.

[0011] As a further technical solution of the present invention, the NCO index of the first foaming liquid is 106-115; the NCO index of the second foaming liquid is 100-105; the NCO index of the third foaming liquid is 105-110; The isocyanate is selected from 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, or a mixture of the two.

[0012] As a further technical solution of the present invention, in step S6, a layer of spandex fiber mesh is laid between the first foaming liquid and the third foaming liquid, and between the third foaming liquid and the second foaming liquid.

[0013] As a further technical solution of the present invention, the chain extender is selected from one of aliphatic diols, aromatic diols, and aromatic diamines; The cross-linking agent is selected from one of multifunctional isocyanate, melamine, triisocyanurate, vinyltrimethoxysilane and vinyltriethoxysilane; The catalyst is selected from one of an organotin catalyst and an amine catalyst, or a mixture of the two; The dispersant is selected from polyethylene glycol, polyglycerol, and fatty alcohol polyoxyethylene ether.

[0014] The beneficial effects of the present invention are: The present invention discloses a high-strength, high-toughness and heat-repairable polyurethane sponge, which is composed of multiple sponge layers with gradient changes in hardness, toughness, resilience and other properties. The polyurethane sponge is fixed to the equipment or product through the high-hardness sponge layer, and then cushioned and shock-absorbing is performed through the high-toughness sponge layer. At the same time, the polyurethane sponge has improved toughness through internal aramid nanofibers, and the slipped fibers are quickly reset through hydrogen bond recombination. After the polyurethane sponge is thermally repaired based on the internal DA adduct, the positions of the original cracks inside the polyurethane sponge are re-crosslinked and fixed with a high degree of fit, so that the repaired polyurethane sponge maintains high mechanical properties. DETAILED DESCRIPTION

[0015] The following describes the implementation of the present invention in conjunction with relevant embodiments. The implementation of the present invention is not limited to the following embodiments, and the present invention relates to relevant necessary components in this technical field and should be regarded as a well-known technology in this technical field, which can be known and mastered by technical personnel in this technical field.

[0016] A method for preparing a high-strength toughened sponge comprises the following steps: S1. Put furanyl polyol and bismaleimide into a reaction kettle containing a reaction solvent and stir them evenly. After the materials are completely dissolved, heat them to react. After the reaction is complete, evaporate the reaction solvent to obtain a prepolymer; S2, mixing the prepolymer with the first polyether polyol, aramid nanofibers, a chain extender, deionized water, a crosslinking agent, a catalyst, and a dispersant to obtain a first component; S3, mixing the prepolymer with the second polyether polyol, aramid nanofibers, a chain extender, deionized water, a crosslinking agent, a catalyst, and a dispersant to obtain a second component; S4, taking a portion of the first component and mixing a portion of the second component to obtain a third component; S5, mixing the remaining first component with isocyanate and stirring evenly to obtain a first foaming liquid, mixing the remaining second component with isocyanate and stirring evenly to obtain a second foaming liquid, and mixing the third component with isocyanate and stirring evenly to obtain a third foaming liquid; S6. Inject half of the first foaming liquid, half of the third foaming liquid, all of the second foaming liquid, the other half of the third foaming liquid, and the other half of the first foaming liquid into the mold in sequence, close the mold and heat to foam, and after foaming, cool and mature, open the mold to obtain a polyurethane sponge.

[0017] The present invention discloses a high-strength, high-toughness and heat-repairable polyurethane sponge. In the polyurethane sponge, the high strength performance is mainly achieved by selecting a polyether polyol with a specific functionality and a suitable NCO index, the high toughness performance is mainly achieved by selecting a polyether polyol with a specific functionality, a suitable NCO index and internally filled aramid nanofibers, and the heat-repairing performance is achieved by forming a DA adduct with a heat-repairing function through a Diels-Alder (DA) reaction between a furan group and a maleimide group, thereby obtaining the polyurethane sponge of the present invention that combines high strength, high toughness and heat-repairing performance. The polyurethane sponge is mainly used as a buffering and shock-absorbing structure in the fields of industrial equipment, the automotive industry, electronic products, etc., and absorbs a large amount of energy through its high strength and high toughness to achieve a buffering function. The heat-repairing function then removes internal cracks to prevent crack propagation, allowing the polyurethane sponge to maintain a stable structure, thereby increasing its service life.

[0018] In the polyurethane sponge production method of the present invention, step S1 mainly involves reacting furanyl polyol with bismaleimide to obtain a DA adduct containing a hydroxyl group, i.e., a prepolymer. In step S1, the furanyl polyol is selected from 2,5-furan dimethanol and 2,5-tetrahydrofuran dimethanol, or a mixture of the two. The molecule of 2,5-furan dimethanol contains a rigid furan ring and two primary hydroxyl groups, and thus has high reactivity. After subsequent reaction with isocyanate, the 2,5-furan dimethanol can impart high mechanical strength, heat resistance, and other properties to the polyurethane sponge. The saturated ring structure of 2,5-tetrahydrofuran dimethanol is beneficial for improving the hydrolysis resistance and flexibility of the polyurethane sponge, thereby improving the weather resistance and fatigue resistance of the polyurethane sponge. Furthermore, in step S1, the bismaleimide is selected from one of 4,4'-bismaleimidodiphenylmethane and 1,6-bismaleimidohexane, or a mixture of the two. Both raw materials are bismaleimides, each of which contains two maleimide groups in a single molecule and has high reactivity with furanyl polyol. In addition, the reaction solvent is selected from one or more of acetone, toluene, and tetrahydrofuran. The reaction solvent provides a solvent environment for the DA reaction between the furanyl polyol and the bismaleimide. The DA adduct formed after the reaction of the two is used as a raw material to participate in the foaming reaction of the polyurethane sponge, which is beneficial to improving the toughness of the polyurethane sponge. Furthermore, in the reactor of step S1, the molar ratio of the furan group to the maleimide group in the furan polyol and the bismaleimide is (1-1.2):1, and the reactor is heated to 60-80°C while stirring to perform a DA reaction; in the DA reaction, the furan polyol acts as a diene and the bismaleimide acts as a dienophile, and the two are heated in a reaction solvent environment to perform a DA reaction and form a furan-maleimide adduct (DA adduct), which is a product that can achieve thermal repair properties. The DA adduct can be heated to 100-150°C and then decrosslinked to restore a certain fluidity, and then During the cooling process, the cross-linking reaction is carried out again. After the raw materials with DA adducts are used to make polyurethane sponges, the polyurethane molecular chains of the polyurethane sponges have DA adducts. When cracks appear inside the polyurethane sponge, the polyurethane sponge can be heated to 100~150℃ to decrosslink the DA adducts and flow in the cracks. Then, during the cooling and re-cross-linking process, the DA adducts are re-cross-linked to connect the polyurethane molecular chains on both sides of the cracks, thereby repairing the cracks inside the polyurethane sponge, improving the service life of the polyurethane sponge, and maintaining good cushioning and shock-absorbing performance when the polyurethane sponge is used as a cushioning and shock-absorbing structure.

[0019] In steps S2 and S3 of the present invention, the functionality of the first polyether polyol is 4-6, and the first component includes the following components by mass percentage: 10%-20% prepolymer, 59%-79% first polyether polyol, 3%-6% aramid nanofiber, 4%-8% chain extender, 2%-4% deionized water, 1%-2% crosslinking agent, 0.5%-1% catalyst, and 0.2%-0.5% dispersant; the functionality of the second polyether polyol is 2-3, and the second component includes the following components by mass percentage: 10%-20% prepolymer, 54%-77% second polyether polyol, 5%-10% aramid nanofiber, 4%-8% chain extender, 2%-4% deionized water, 1%-2% crosslinking agent, 0.5%-1% catalyst, and 0.5%-1% dispersant; After the prepolymer is mixed with raw materials such as polyether polyol, it needs to react with isocyanate and foam simultaneously to produce polyurethane sponge. During the process of polyurethane molecular chain extension, the prepolymer will introduce DA adduct into the polyurethane molecular chain, so that the final polyurethane sponge has thermal repair function; in addition, the polyurethane sponge is dispersed with aramid nanofibers, which form a three-dimensional network in the polyurethane sponge. The aramid nanofibers can improve the toughness of the polyurethane sponge by consuming energy during fiber slippage, and the slipped fibers can be quickly reset through hydrogen bond reorganization, thereby improving the resilience of the polyurethane sponge. Even if cracks appear inside the polyurethane sponge, the aramid nanofibers can avoid dislocation of the sponge structure at the cracks by reset, so that the polyurethane sponge maintains a stable structure. After the polyurethane sponge is thermally repaired, the position of the original cracks inside it is re-crosslinked and fixed with a high degree of fit, so that the repaired polyurethane sponge maintains high mechanical properties.

[0020] In step S4 of the present invention, the mass ratio of the first component to the second component in the third component is 1:1; in step S5, the mass ratio of the first foaming liquid, the second foaming liquid, and the third foaming liquid is 1:(1-3):0.5; the third component is formed by mixing the first component and the second component, the first component adopts a polyether polyol with higher functionality, and the first sponge layer formed by foaming after the first component is mixed with isocyanate has higher strength and lower toughness, while the second component adopts a polyether polyol with lower functionality, and the second sponge layer formed by foaming after the second component is mixed with isocyanate has lower hardness and higher toughness. In order to avoid layer separation of the polyurethane sponge due to poor compatibility between the two sponge structures, the third sponge layer with moderate hardness and toughness is formed by foaming by mixing the third component with isocyanate. The third sponge layer serves as a transition layer between the first sponge layer and the second sponge layer, and has high compatibility with both the first sponge layer and the second sponge layer, thereby forming a polyurethane sponge with good structural stability and a multi-layer structure.

[0021] In step S5 of the present invention, the NCO index of the first foaming liquid is 106-115; the NCO index of the second foaming liquid is 100-105; and the NCO index of the third foaming liquid is 105-110. The isocyanate is selected from 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, or a mixture of the two. The NCO index reflects the degree of excess isocyanate. In the polyurethane sponge production method of the present invention, the first foaming liquid uses a higher NCO index, so that a first sponge layer with higher hardness is formed on one side of the polyurethane sponge, while the second foaming liquid has a lower NCO index, and the second sponge layer formed on the other side has good elasticity. The third foaming liquid has a moderate NCO index, and the third sponge layer formed by foaming serves as a compatibility transition layer between the first sponge layer and the second sponge layer. The polyurethane sponge of the present invention is composed of a first sponge layer, a third sponge layer, a second sponge layer, a third sponge layer, and a first sponge layer in sequence. The hardness, toughness, resilience and other properties of the five sponge layers vary in a gradient. The first sponge layer has a higher hardness and mainly serves as a structure for fixing the polyurethane sponge to equipment or products, so that the polyurethane sponge is firmly fixed in the equipment or products. The second sponge layer serves as the main buffering and shock-absorbing structure in the polyurethane sponge and has high toughness and resilience. When the polyurethane sponge is subjected to external force, the external force impact is mainly absorbed by the second sponge layer and rebounds after the external force disappears, thereby achieving buffering of the equipment or product. The third sponge layer is mainly used to improve the structural stability between the various structural layers in the polyurethane sponge and plays a role in force transmission, so that the force applied to the first sponge layer is transmitted to the second sponge layer.

[0022] In step S6 of the present invention, a layer of spandex fiber mesh is laid between the first foaming liquid and the third foaming liquid, and between the third foaming liquid and the second foaming liquid; the spandex fiber mesh is a mesh structure woven with spandex fibers. The spandex fiber mesh can improve the interlayer interface bonding strength between the first sponge layer and the third sponge layer, and between the third sponge layer and the second sponge layer, thereby preventing the polyurethane sponge from stratifying. The spandex fiber mesh can also improve the overall toughness of the polyurethane sponge, and improve the compressive resistance of the polyurethane sponge when it is squeezed by external force and the subsequent rebound performance.

[0023] In steps S2 and S3 of the present invention, the chain extender is selected from one of aliphatic diols, aromatic diols, and aromatic diamines; the crosslinking agent is selected from one of multifunctional isocyanates, melamine, triisocyanurate, vinyltrimethoxysilane, and vinyltriethoxysilane; the catalyst is selected from one of an organotin catalyst and an amine catalyst, or a mixture of the two; and the dispersant is selected from one of polyethylene glycol, polypropylene glycol, and fatty alcohol polyoxyethylene ether.

[0024] In summary, the present invention discloses a high-strength, high-toughness and heat-repairable polyurethane sponge, which is composed of multiple layers of sponge layers with gradient changes in hardness, toughness, resilience and other properties. The polyurethane sponge is fixed to the equipment or product through the high-hardness sponge layer, and then cushioned and shock-absorbing is performed through the high-toughness sponge layer. At the same time, the polyurethane sponge improves its toughness through the internal aramid nanofibers, and the slipped fibers are quickly reset through hydrogen bond reorganization. After the polyurethane sponge is thermally repaired based on the internal DA adduct, the position of the original cracks inside it is re-crosslinked and fixed with a high degree of fit, so that the repaired polyurethane sponge maintains high mechanical properties.

[0025] The present invention is further described below by way of examples and comparative examples.

[0026] Example 1 S1. Add 2,5-tetrahydrofuran dimethanol and 1,6-bismaleimidohexane into a reaction kettle containing a mixed solvent of acetone and tetrahydrofuran, and stir evenly. After the materials are completely dissolved, heat to 70° C. to react. After the reaction is complete, evaporate the reaction solvent to obtain a prepolymer. Wherein, the molar ratio of furan group to maleimide group in the reaction system of step S1 is 1.2:1; S2. Mixing the prepolymer with the first polyether polyol, aramid nanofibers, aliphatic diol, deionized water, melamine, an organotin catalyst, and polyethylene glycol to obtain a first component; The first component includes the following components by mass percentage: 15% prepolymer, 69% first polyether polyol, 4.5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.3% polyethylene glycol; S3, mixing the prepolymer with a second polyether polyol, aramid nanofibers, aliphatic diol, deionized water, melamine, an organotin catalyst, and polyethylene glycol to obtain a second component; The second component includes the following components by mass percentage: 15% prepolymer, 65.5% second polyether polyol, 7.5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.8% polyethylene glycol; S4, taking a portion of the first component and mixing a portion of the second component to obtain a third component; Wherein, the mass ratio of the first component to the second component in the third component is 1:1; S5, mixing the remaining first component with 4,4'-diphenylmethane diisocyanate and stirring evenly to obtain a first foaming liquid, mixing the remaining second component with 4,4'-diphenylmethane diisocyanate and stirring evenly to obtain a second foaming liquid, and mixing the third component with 4,4'-diphenylmethane diisocyanate and stirring evenly to obtain a third foaming liquid; The NCO index of the first foaming liquid is 110, the NCO index of the second foaming liquid is 103, the NCO index of the third foaming liquid is 107, and the mass ratio of the first foaming liquid, the second foaming liquid, and the third foaming liquid is 1:1:0.5; S6. Inject half of the first foaming liquid, half of the third foaming liquid, all of the second foaming liquid, the other half of the third foaming liquid, and the other half of the first foaming liquid into the mold in sequence, close the mold and heat to foam, and after foaming, cool and mature, open the mold to obtain a polyurethane sponge.

[0027] Example 2 The difference between this embodiment and the above-mentioned embodiment 1 is that in step S5, the mass ratio of the first foaming liquid, the second foaming liquid, and the third foaming liquid is 1:2:0.5; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0028] Example 3 The difference between this embodiment and the above-mentioned embodiment 1 is that in step S5, the mass ratio of the first foaming liquid, the second foaming liquid, and the third foaming liquid is 1:3:0.5; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0029] Example 4 The difference between this embodiment and the above-mentioned embodiment 1 is that, in step S2, the first component includes the following components in mass percentage: 10% prepolymer, 74% first polyether polyol, 4.5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.3% polyethylene glycol; and, in step S3, the second component includes the following components in mass percentage: 10% prepolymer, 70.5% second polyether polyol, 7.5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.8% polyethylene glycol; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0030] Example 5 The difference between this embodiment and the above-mentioned embodiment 1 is that, in step S2, the first component includes the following components in mass percentage: 20% prepolymer, 64% first polyether polyol, 4.5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.3% polyethylene glycol; and in step S3, the second component includes the following components in mass percentage: 20% prepolymer, 60.5% second polyether polyol, 7.5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.8% polyethylene glycol; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0031] Example 6 The difference between this embodiment and the above-mentioned embodiment 1 is that, in step S2, the first component includes the following components in mass percentage: 15% prepolymer, 70.6% first polyether polyol, 3% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.2% polyethylene glycol; and, in step S3, the second component includes the following components in mass percentage: 15% prepolymer, 68.3% second polyether polyol, 5% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.5% polyethylene glycol; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0032] Example 7 The difference between this embodiment and the above-mentioned embodiment 1 is that, in step S2, the first component includes the following components in mass percentage: 15% prepolymer, 67.3% first polyether polyol, 6% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 0.5% polyethylene glycol; and, in step S3, the second component includes the following components in mass percentage: 15% prepolymer, 62.8% second polyether polyol, 10% aramid nanofiber, 6% aliphatic diol, 3% deionized water, 1.5% melamine, 0.7% organotin catalyst, and 1% polyethylene glycol; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0033] Example 8 The difference between this embodiment and the above-mentioned embodiment 1 is that in step S6, half of the first foaming liquid, half of the third foaming liquid, all of the second foaming liquid, the other half of the third foaming liquid, and the other half of the first foaming liquid are injected into the mold in sequence, and at the same time, a layer of spandex fiber mesh is laid between the first foaming liquid and the third foaming liquid and between the third foaming liquid and the second foaming liquid, the mold is closed and heated for foaming, and after foaming is completed, it is cooled and matured, and then the mold is opened to obtain a polyurethane sponge; the operations and raw material ratios of the remaining steps are based on the above-mentioned embodiment 1.

[0034] It should be noted that in all embodiments of the present invention, the first polyether polyol is compounded in a 1:1:1 ratio with common polyether polyols having functionalities of 4, 5, and 6, such as polyether 403, polyether 4110, and polyether 635 to obtain the first polyether polyol. At the same time, the second polyether polyol is compounded in a 1:1 ratio with common polyether polyols having functionalities of 2 and 3, such as polyether 210 and polyether 3600 to obtain the second polyether polyol. In addition, in all the above embodiments, except for Example 8, no spandex fiber mesh is laid in the polyurethane sponge of the other embodiments.

[0035] Comparative Example 1 With reference to Chinese patent publication (announcement) number CN115368707A, a foamed composite material was obtained according to Example 1 in the specification of the patent document.

[0036] It should be noted that the thickness of the sponges and foamed composite materials obtained in all the above examples and comparative examples are the same.

[0037] The sponges and foamed composite materials obtained in all the above examples and comparative examples were subjected to five performance tests, including compression set, indentation rate, tear strength, elongation at break, and tensile strength, in accordance with the standard documents GB / T 6669-2008, GB / T 10807-2006, GB / T 10808-2008, and GB / T 6344-2008. The test results are shown in Table 1 below.

[0038]

[0039] Table 1 According to the data in Table 1, by comparing Example 1, Example 2, and Example 3, it can be seen that as the proportion of the second foaming layer in the polyurethane sponge increases, the deformation resistance and tear resistance of the polyurethane sponge can be improved, thereby having higher toughness, while the increase in the proportion of the first foaming layer can increase the tensile strength of the polyurethane sponge; Comparing Example 1, Example 4, and Example 5, it can be seen that the addition ratio of the prepolymer has a relatively obvious effect on the deformation resistance and tear resistance of the polyurethane sponge. Increasing the addition ratio of the prepolymer can improve the toughness of the polyurethane sponge. Comparing Example 1, Example 6, and Example 7, it can be seen that the addition ratio of aramid nanofibers has a relatively obvious effect on the various properties of the polyurethane sponge. Increasing the addition ratio of aramid nanofibers can improve the toughness and strength of the polyurethane sponge. Comparing Example 1 with Example 8, it can be seen that the polyurethane sponge with the spandex fiber mesh inside has higher toughness and strength because the spandex fiber mesh has a certain elasticity and increases the interlayer interface bonding strength between adjacent sponge layers in the polyurethane sponge.

[0040] The polyurethane sponges obtained in Examples 1, 4, and 5 were subjected to the following tests: several polyurethane sponges were stretched to cause cracks on the surface and inside. A portion of the cracked polyurethane sponges was subjected to five performance tests, including compression set, indentation rate, tear strength, elongation at break, and tensile strength. Another portion of the cracked polyurethane sponges was heated to 120° C. and then cooled for thermal repair. The thermally repaired polyurethane sponges were then subjected to five performance tests, including compression set, indentation rate, tear strength, elongation at break, and tensile strength.

[0041] The test results of the polyurethane sponge before repair are shown in Table 2 below, and the test results of the polyurethane sponge after repair are shown in Table 3 below.

[0042]

[0043] Table 2

[0044] Table 3 According to the data in Tables 2 and 3, the various properties of the polyurethane sponge that was stretched to cracks were significantly reduced. The cracked polyurethane sponge could only barely meet or had difficulty meeting the performance requirements of a buffer and shock-absorbing structure. However, after heat repair, the performance of the polyurethane sponge could reach more than 80% of the performance of the intact polyurethane sponge, which could meet the performance requirements of a buffer and shock-absorbing structure and enable it to continue to serve as a buffer and shock-absorbing structure. This shows that the polyurethane sponge can continue to work after heat repair, thereby increasing the service life of the polyurethane sponge.

[0045] The above description is only a preferred embodiment of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a high-strength toughened sponge, characterized in that: The following steps are involved: S1. Put furanyl polyol and bismaleimide into a reaction kettle containing a reaction solvent and stir them evenly. After the materials are completely dissolved, heat them to react. After the reaction is complete, evaporate the reaction solvent to obtain a prepolymer; S2, mixing the prepolymer with the first polyether polyol, aramid nanofibers, a chain extender, deionized water, a crosslinking agent, a catalyst, and a dispersant to obtain a first component; S3, mixing the prepolymer with the second polyether polyol, aramid nanofibers, a chain extender, deionized water, a crosslinking agent, a catalyst, and a dispersant to obtain a second component; S4, taking a portion of the first component and mixing a portion of the second component to obtain a third component; S5, mixing the remaining first component with isocyanate and stirring evenly to obtain a first foaming liquid, mixing the remaining second component with isocyanate and stirring evenly to obtain a second foaming liquid, and mixing the third component with isocyanate and stirring evenly to obtain a third foaming liquid; S6. Inject half of the first foaming liquid, half of the third foaming liquid, all of the second foaming liquid, the other half of the third foaming liquid, and the other half of the first foaming liquid into the mold in sequence, close the mold and heat to foam, and after foaming, cool and mature, open the mold to obtain a polyurethane sponge.

2. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: The furan-based polyol is selected from 2,5-furan dimethanol and 2,5-tetrahydrofuran dimethanol, or a mixture of the two; the bismaleimide is selected from 4,4'-bismaleimidodiphenylmethane and 1,6-bismaleimidohexane, or a mixture of the two.

3. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: The reaction solvent is selected from one or more of acetone, toluene, and tetrahydrofuran; in the reactor of step S1, the molar ratio of the furanyl polyol and the furan group to the maleimide group in the bismaleimide is (1-1.2):1, and the reactor is heated to 60-80° C. while stirring to carry out the DA reaction.

4. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: The functionality of the first polyether polyol is 4 to 6, and the first component includes the following components by mass percentage: 10% to 20% prepolymer, 59% to 79% first polyether polyol, 3% to 6% aramid nanofiber, 4% to 8% chain extender, 2% to 4% deionized water, 1% to 2% crosslinking agent, 0.5% to 1% catalyst, and 0.2% to 0.5% dispersant.

5. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: The functionality of the second polyether polyol is 2-3, and the second component includes the following components by mass percentage: 10%-20% prepolymer, 54%-77% second polyether polyol, 5%-10% aramid nanofiber, 4%-8% chain extender, 2%-4% deionized water, 1%-2% crosslinking agent, 0.5%-1% catalyst, and 0.5%-1% dispersant.

6. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: In step S4, the mass ratio of the first component to the second component in the third component is 1:1; In step S5, the mass ratio of the first foaming liquid, the second foaming liquid, and the third foaming liquid is 1:(1-3):0.

5.

7. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: The NCO index of the first foaming liquid is 106-115; the NCO index of the second foaming liquid is 100-105; the NCO index of the third foaming liquid is 105-110; The isocyanate is selected from 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, or a mixture of the two.

8. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: In step S6, a layer of spandex fiber mesh is laid between the first foaming liquid and the third foaming liquid, and between the third foaming liquid and the second foaming liquid.

9. The method for preparing the high-strength toughened sponge according to claim 1, characterized in that: The chain extender is selected from one of aliphatic diols, aromatic diols, and aromatic diamines; The cross-linking agent is selected from one of multifunctional isocyanate, melamine, triisocyanurate, vinyltrimethoxysilane and vinyltriethoxysilane; The catalyst is selected from one of an organotin catalyst and an amine catalyst, or a mixture of the two; The dispersant is selected from polyethylene glycol, polyglycerol, and fatty alcohol polyoxyethylene ether.

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