Composite foamed material and its degradation and recycling method

Abstract

This application discloses a composite foam material and its degradation and recycling method, relating to the field of foam material technology. The composite foam material includes a polyol, isocyanate compounds, a foaming agent, and a dual-response degrading agent; wherein the dual-response degrading agent includes a temperature-responsive material and an enzyme-affinity material. In the composite foam material provided by this application, both temperature-responsive and enzyme-affinity materials are introduced as dual-response degrading agents to construct a "temperature-enzyme" dual-response synergistic degradation system. This gives the composite foam material dual degradation triggering characteristics. In the subsequent recycling stage, the urethane bonds of the polyurethane foam can be rapidly destroyed through the synergistic effect of appropriate heat treatment and enzyme catalysis, achieving efficient depolymerization. After simple purification, the depolymerization product yields a high-purity recycled polyol, which can be directly used in the preparation of high-end refrigerator insulation layers.

Description

Technical Field

[0001] This application relates to the field of foamed materials technology, and in particular to a composite foamed material and its degradation and recycling method. Background Technology

[0002] Polyurethane foam, due to its excellent thermal insulation, heat insulation, and cushioning properties, is widely used in building insulation, refrigerator and freezer insulation, and automotive interiors, with polyurethane foam accounting for over 35% of refrigerator insulation layers. With the disposal of various polyurethane foam-containing products, a large amount of waste polyurethane foam is generated. Statistics show that the global annual emission of waste polyurethane foam exceeds 10 million tons, and my country's annual emission exceeds 2 million tons. Because polyurethane foam has a stable structure and is difficult to degrade, long-term accumulation can cause serious environmental pollution. Furthermore, its raw materials (polyols and isocyanates) are non-renewable resources. Therefore, the recycling and utilization of waste foam has become an urgent industry problem to be solved and a key link in responding to global ESG (Environmental, Social, and Governance) circular development requirements.

[0003] Current recycling technologies for waste polyurethane foam have significant shortcomings, making it difficult to meet the demands of high-end recycling. Summary of the Invention

[0004] In view of this, this application provides a composite foaming material and a method for its degradation and recycling to solve at least one of the above problems.

[0005] The embodiments of this application are implemented as follows: a composite foaming material includes a polyol, an isocyanate compound, a foaming agent, and a dual-response degrading agent; wherein the dual-response degrading agent includes a temperature-responsive material and an enzyme-affinity material.

[0006] Optionally, in some embodiments of this application, the minimum critical dissolution temperature of the temperature-responsive material is 30°C to 45°C.

[0007] The temperature-responsive material includes one or more of N-isopropylacrylamide, N-vinylcaprolactam, and poly(N,N-diethylacrylamide).

[0008] The enzyme-affinity material includes acrylate materials containing hydrophilic groups.

[0009] The acrylate materials containing hydrophilic groups include one or more of polyethylene glycol monomethyl ether methacrylate, polyethylene glycol acrylate, and hydroxyethyl methacrylate.

[0010] Optionally, in some embodiments of this application, the dual-response degrading agent further includes a crosslinking agent.

[0011] The crosslinking agent includes one or more of N,N'-methylenebisacrylamide, trimethylolpropane triacrylate, and ethylene glycol dimethacrylate.

[0012] In the dual-response degradation agent, the mass ratio of the temperature-responsive material, the enzyme-affinity material, and the crosslinking agent is (4~6):(2~4):(1~3).

[0013] Optionally, in some embodiments of this application, the polyol comprises a polyether polyol. The molecular weight of the polyether polyol is 2000-4000.

[0014] The isocyanate compounds include one or more of isocyanates and diphenylmethane diisocyanate.

[0015] The foaming agent includes an alkane foaming agent. The alkane foaming agent includes one or more of cyclopentane and isopentane.

[0016] In the composite foaming material, the mass ratio of the polyol, the isocyanate compound, the foaming agent and the dual-response degradation agent is 100:(110~130):(3~7):(2~5).

[0017] Optionally, in some embodiments of this application, the composite foaming material further includes a catalyst.

[0018] The catalyst includes one or more of organometallic salt catalysts and amine catalysts. The organometallic salt catalyst includes one or more of dibutyltin dilaurate, bismuth octanoate, and bismuth neodecanoate. The amine catalyst includes one or more of triethylenediamine, dimethylcyclohexylamine, and N,N-dioctylcyclohexylamine.

[0019] The mass ratio of the polyol to the catalyst is 100:(0.5~1.5).

[0020] Accordingly, this application also provides a method for degrading and recycling composite foam materials, comprising the following steps: providing the above-mentioned composite foam material; providing a degradation enzyme and water, mixing them with the composite foam material, heating and degrading to obtain depolymerization products.

[0021] Optionally, in some embodiments of this application, the composite foaming material is further subjected to pretreatment before being mixed with the degradation enzyme.

[0022] The pretreatment includes one or more of the following: impurity removal, pulverization, and drying.

[0023] The pulverization includes pulverizing the composite foam material to an average particle size of 5mm to 10mm.

[0024] Optionally, in some embodiments of this application, the enzyme activity of the degrading enzyme is greater than or equal to 1000 U / g.

[0025] The degrading enzyme includes lipases. The degrading enzyme includes lipases derived from Pseudomonas.

[0026] The mass ratio of the composite foaming material to the degrading enzyme is 100:(0.5~1.5).

[0027] The mass concentration of the degradation enzyme and the composite foaming material in the water is 0.5 g / mL to 10 g / mL.

[0028] The temperature for the heat degradation is 115℃~125℃, and the time for the heat degradation is 2.5h~3.5h.

[0029] Optionally, in some embodiments of this application, after obtaining the depolymerization product, the degradation and recycling method further includes: subjecting the depolymerization product to vacuum distillation, and then adsorbing it with an adsorbent to obtain a recycled polyol. It is understood that the recycled polyol can be reacted again with other raw materials to prepare composite foamed materials.

[0030] Optionally, in some embodiments of this application, the pressure of vacuum distillation is 0.07MPa~0.09MPa, the temperature of vacuum distillation is 140℃~160℃, and the time of vacuum distillation is 20min~40min.

[0031] The adsorbent includes one or more of activated carbon, activated alumina, silica gel, molecular sieve, and macroporous resin.

[0032] The mass ratio of the depolymerization product to the adsorbent is 100:(0.5~1.5).

[0033] The adsorption temperature is 70℃~90℃, and the adsorption time is 30min~60min.

[0034] The composite foam material provided in this application incorporates both temperature-responsive and enzyme-affinity materials as dual-response degrading agents to construct a "temperature-enzyme" dual-response synergistic degradation system. This gives the composite foam material dual degradation triggering characteristics. In the subsequent recycling stage, the urethane bonds of the polyurethane foam can be rapidly destroyed through the synergistic effect of appropriate heat treatment and enzyme catalysis, achieving efficient depolymerization. After simple purification, the depolymerization product yields a high-purity recycled polyol, which can be directly used in the preparation of high-end refrigerator insulation layers. Specifically, temperature-responsive materials can undergo conformational changes at certain temperatures, transforming from a hydrophilic extended conformation to a hydrophobic coiled conformation. This coiled conformation leads to steric hindrance changes within the polyurethane molecular chain, weakening interactions such as hydrogen bonds and van der Waals forces between molecular chains. This loosens and cracks the originally stable spatial network structure of the polyurethane, disrupting the spatial structure of the polyurethane molecular chain and creating conditions for enzyme catalysis to break the urethane bonds. Enzyme-affinity materials can form specific bindings with enzymes, improving enzyme catalytic efficiency. They can also anchor enzymes near the polyurethane molecular chain, synergizing with the conformational changes of temperature-responsive materials to make enzyme catalysis more precise and further enhance the thoroughness of degradation.

[0035] This application addresses the problems of high pollution, high energy consumption, and numerous byproducts associated with existing single chemical depolymerization technologies by introducing a dual-response degrading agent into composite foam materials to promote their recycling and reuse. It achieves a low-pollution, low-energy depolymerization process. Furthermore, it solves the problems of "downgraded use" and low recycling rates in existing physical recycling methods, as well as the low depolymerization efficiency and incomplete depolymerization in single biodegradation methods, achieving high depolymerization rates and high recycled purity. It also addresses the issue that existing recycling processes cannot meet the requirements of high-end applications (such as high-end refrigerator insulation layers), enabling the direct high-end application of recycled polyols. Finally, it overcomes the difficulty of balancing environmental friendliness, economic efficiency, and practicality in existing technologies, meeting ESG (Environmental, Social, and Governance) requirements, reducing recycling costs, and facilitating industrial-scale promotion. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of a degradation and recycling method for composite foamed materials provided in an embodiment of this application. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0039] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the orientation shown in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0040] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0041] In this application, "at least one" means one or more, and "more than one" means two or more. "One or more", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0042] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0043] Among related technologies, the recycling technologies for waste polyurethane foam are mainly divided into three categories: physical recycling methods, chemical recycling methods, and biodegradation methods.

[0044] Physical recycling methods mainly include crushing, compaction, and hot-melt regeneration. This method is simple and low-cost, but it only alters the physical morphology of the foam and cannot destroy the chemical structure of polyurethane. Recycled products are mostly fillers and low-end insulation materials, resulting in "downgrading" and low recycling rates. Furthermore, the performance of recycled products is poor, making them unsuitable for high-end applications (such as high-end refrigerator insulation layers). Simultaneously, the crushing process generates a large amount of dust, causing secondary pollution.

[0045] Chemical recycling methods, including alcoholysis, hydrolysis, and ammonolysis, break the urethane bonds in polyurethane using chemical reagents to depolymerize and regenerate polyols. While this method achieves chemical depolymerization, it has several drawbacks: First, the depolymerization conditions are demanding, requiring high temperature and pressure environments, resulting in extremely high energy consumption. Second, the amount of chemical reagents (such as strong acids, alkalis, and highly reactive alcohols) used is large, easily generating toxic and harmful byproducts and causing serious secondary pollution. Third, the depolymerization products have low purity, requiring complex purification processes, further increasing recycling costs.

[0046] Single-enzyme biodegradation method: This method utilizes enzymes such as lipases and esterases to catalyze the degradation of polyurethane. While this method is environmentally friendly and operates under mild conditions, the efficiency of a single enzyme is extremely low, the depolymerization time is long, and the depolymerization is incomplete, resulting in a typically low depolymerization rate, which cannot meet the needs of industrial production.

[0047] In summary, existing technologies cannot simultaneously achieve the recycling goals of "high depolymerization rate, high regeneration purity, low energy consumption, and low pollution" for waste polyurethane foam, and are insufficient to meet ESG recycling requirements and the recycling needs of high-end fields.

[0048] The technical solution of this application is as follows: In a first aspect, embodiments of this application provide a composite foaming material, comprising a polyol, an isocyanate compound, a foaming agent, and a dual-response degrading agent; wherein the dual-response degrading agent comprises a temperature-responsive material and an enzyme-affinity material.

[0049] It should be noted that temperature-responsive materials refer to thermosensitive materials that exhibit temperature responsiveness. These materials possess a minimum critical dissolution temperature (LCST) in aqueous solutions; below the LCST, they dissolve in water to form a homogeneous solution; above the LCST, phase separation occurs due to hydrophobic interactions (precipitation, gelation, or precipitation). Enzyme-affinity materials refer to materials that can form specific interactions with target enzymes, thereby enhancing enzyme catalytic efficiency.

[0050] It should also be noted that the composite foaming material provided in the embodiments of this application is a polyurethane foam prepared by reacting polyols, isocyanate compounds, foaming agents and dual-response degrading agents together to carry out nucleation foaming.

[0051] The composite foam material provided in this application incorporates both temperature-responsive and enzyme-affinity materials as dual-response degrading agents to construct a "temperature-enzyme" dual-response synergistic degradation system. This gives the composite foam material dual degradation triggering characteristics. In the subsequent recycling stage, the urethane bonds of the polyurethane foam can be rapidly destroyed through the synergistic effect of appropriate heat treatment and enzyme catalysis, achieving efficient depolymerization. After simple purification, the depolymerization product yields a high-purity recycled polyol, which can be directly used in the preparation of high-end refrigerator insulation layers. Specifically, temperature-responsive materials can undergo conformational changes at certain temperatures, transforming from a hydrophilic extended conformation to a hydrophobic coiled conformation. This coiled conformation leads to steric hindrance changes within the polyurethane molecular chain, weakening interactions such as hydrogen bonds and van der Waals forces between molecular chains. This loosens and cracks the originally stable spatial network structure of the polyurethane, disrupting the spatial structure of the polyurethane molecular chain and creating conditions for enzyme catalysis to break the urethane bonds. Enzyme-affinity materials can form specific bindings with enzymes, improving enzyme catalytic efficiency. They can also anchor enzymes near the polyurethane molecular chain, synergizing with the conformational changes of temperature-responsive materials to make enzyme catalysis more precise and further enhance the thoroughness of degradation.

[0052] This application addresses the problems of high pollution, high energy consumption, and numerous byproducts associated with existing single chemical depolymerization technologies by introducing a dual-response degrading agent into composite foam materials to promote their recycling and reuse. It achieves a low-pollution, low-energy depolymerization process. Furthermore, it solves the problems of "downgraded use" and low recycling rates in existing physical recycling methods, as well as the low depolymerization efficiency and incomplete depolymerization in single biodegradation methods, achieving high depolymerization rates and high recycled purity. It also addresses the issue that existing recycling processes cannot meet the requirements of high-end applications (such as high-end refrigerator insulation layers), enabling the direct high-end application of recycled polyols. Finally, it overcomes the difficulty of balancing environmental friendliness, economic efficiency, and practicality in existing technologies, meeting ESG (Environmental, Social, and Governance) requirements, reducing recycling costs, and facilitating industrial-scale promotion.

[0053] In some embodiments, the polyol comprises a polyether polyol. Further, the molecular weight of the polyether polyol is 2000-4000, for example, it can be 2000, 2500, 3000, 3500, 4000, or any range between two of the above values. A suitable molecular weight of the polyether polyol can improve the performance of the composite foam material.

[0054] In some embodiments, the isocyanate compound includes one or more of isocyanates and diphenylmethane diisocyanate (MDI).

[0055] In some embodiments, the foaming agent includes an alkane foaming agent.

[0056] Furthermore, the alkane blowing agent includes one or more of cyclopentane and isopentane.

[0057] In some embodiments, the minimum critical dissolution temperature of the temperature-responsive material is 30°C to 45°C, for example, it can be 30°C, 32°C, 35°C, 40°C, 42°C, 45°C, or any range between two of the above values. The appropriate minimum critical dissolution temperature of the temperature-responsive material is beneficial for its uniform distribution in the composite foam material and its degradation effect during the degradation process.

[0058] In some embodiments, the temperature-responsive material includes one or more of N-isopropylacrylamide (NIPAM), N-vinylcaprolactam (PVCL), and poly(N,N-diethylacrylamide) (PDEA). The molecular chains of the temperature-responsive material possess both hydrophilic amide bonds and hydrophobic alkyl substituents, exhibit a low critical dissolution temperature close to room temperature in aqueous solution, undergo reversible phase separation at temperatures above the LCST, and all demonstrate good water solubility and biocompatibility.

[0059] In some embodiments, the enzyme-affinity material comprises an acrylate material containing hydrophilic groups.

[0060] In some embodiments, the acrylate material containing hydrophilic groups includes one or more of polyethylene glycol monomethyl ether methacrylate (PEGMA), polyethylene glycol acrylate (PEGAcrylate), and hydroxyethyl methacrylate (HEMA). The molecular structure of the enzyme-affinity material contains both polymerizable carbon-carbon double bonds and hydrophilic groups (PEG segments or hydroxyl groups), exhibiting good water solubility, compatibility, and reactivity.

[0061] In some embodiments, the dual-response degrader further includes a crosslinking agent. The crosslinking agent can regulate the degree of crosslinking in the "temperature-responsive material-enzyme-crosslinking agent" compound system, ensuring that the dual-response degrader is uniformly dispersed and does not agglomerate during foam preparation; maintaining the structural stability of the dual-response degrader and preventing premature failure during recycling; and ensuring the efficient performance of the synergistic function of temperature-responsive conformational change and enzyme affinity binding.

[0062] In some embodiments, the crosslinking agent includes one or more of N,N'-methylenebisacrylamide (MBA), trimethylolpropane triacrylate (TMPTA), and ethylene glycol dimethacrylate (EGDMA). The crosslinking agent has two or more reactive double bonds and a linking backbone in its molecular structure, exhibiting good compatibility and crosslinking activity.

[0063] In some embodiments, the mass ratio of the temperature-responsive material, the enzyme-affinity material, and the crosslinking agent in the dual-response degrading agent is (4~6):(2~4):(1~3), for example, it can be 4:2:3, 5:3:2, 6:2:1, 4:4:3, 5:4:2, or any range between two of the above ratios. Within the range of the stated mass ratio, the components work synergistically to promote the beneficial effects of the temperature-responsive material and the enzyme-affinity material in degradation and recycling.

[0064] In some embodiments, the mass ratio of the polyol, the isocyanate compound, the foaming agent, and the dual-response degrading agent in the composite foam material is 100:(110~130):(3~7):(2~5), for example, it can be 100:110:7:5, 100:115:6:3, 100:120:5:2, 100:125:4:3, 100:130:3:4, or any range between two of the above ratios. Within the range of the above mass ratio, it is beneficial to prepare composite foam materials with excellent performance. The dual-response degrading agent can play a role in promoting degradation in the subsequent degradation and recycling process without excessively occupying the volume and cost of the composite foam material.

[0065] In some embodiments, the composite foam material further includes a catalyst. The catalyst is introduced during the preparation of the composite foam material to catalyze and improve the foaming nucleation efficiency.

[0066] Furthermore, the catalyst includes one or more of organometallic salt catalysts and amine catalysts.

[0067] The organometallic salt catalyst includes one or more of dibutyltin dilaurate, bismuth octanoate, and bismuth neodecanoate.

[0068] The amine catalyst includes one or more of triethylenediamine, dimethylcyclohexylamine, and N,N-dioctylcyclohexylamine.

[0069] In some embodiments, the mass ratio of the polyol to the catalyst is 100:(0.5~1.5), for example, it can be 100:0.5, 100:0.8, 100:1, 100:1.2, 100:1.5, or any range between two of the above ratios. Within the range of the mass ratio, it is beneficial to accelerate the rate of foaming nucleation and improve the performance of the composite foam material.

[0070] It should be noted that the composite foamed material can be prepared using conventional foaming methods, simply by adding a dual-response degrading agent to the raw materials. For example, polyols, isocyanate compounds, foaming agents, and dual-response degrading agents can be mixed in a suitable ratio, stirred at 60°C for 5 minutes, then injected into a mold and foamed at room temperature to obtain a composite foamed material containing the dual-response degrading agent.

[0071] Secondly, please refer to Figure 1 This application also provides a method for degrading and recycling the above-mentioned composite foam material, comprising the following steps: Step S11: Provide the above-mentioned composite foaming material; Step S12: Provide a degrading enzyme and water, mix with the composite foaming material, heat to degrade, and obtain depolymerization products.

[0072] It should be noted that in the actual preparation process, the above-mentioned composite foam material is used in devices (such as refrigerators). After the device is used for a long time and is scrapped, the composite foam material is taken out and then degraded and recycled.

[0073] This application provides an in-depth analysis of the pain points in existing waste polyurethane foam recycling technologies. Addressing the issue that single degradation technologies cannot simultaneously achieve efficiency, environmental friendliness, and recycled quality, it innovatively proposes a "temperature-enzyme" dual-response synergistic degradation approach. By customizing a dual-response degradation agent, the foam material possesses the dual characteristics of "temperature-triggered structural destruction + enzyme-catalyzed bond breaking." Combined with the selection of high-temperature resistant lipases and process optimization, a highly efficient and gentle depolymerization process is achieved. This application not only solves the recycling problem of waste insulation materials but also enables high-end applications of recycled products, possessing significant industrial value and promising prospects for widespread adoption.

[0074] In some embodiments, before mixing the composite foaming material with the degrading enzyme, a pretreatment process is further included. The pretreatment includes one or more of impurity removal, pulverization, and drying. Pretreatment can improve purity, allowing for targeted degradation and recycling of the composite foaming material. Pulverization increases the contact area, which is beneficial for the heating degradation temperature and for the degrading enzyme to fully exert its effect.

[0075] Furthermore, the pulverization includes pulverizing the composite foam material to an average particle size of 5mm to 10mm, for example, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, or any two of the above values. A suitable particle size facilitates degradation and recycling operations, improving degradation efficiency.

[0076] In some embodiments, the activity of the degrading enzyme is greater than or equal to 1000 U / g, for example, it can be 1000 U / g, 1050 U / g, 1100 U / g, 1150 U / g, 1200 U / g, etc. The high activity of the degrading enzyme can effectively improve the efficiency of degrading composite foam materials, and it forms a specific binding with enzyme-affinity monomers, anchoring lipases near the polyurethane molecular chain. This synergistic effect with the conformational changes of temperature-responsive monomers allows for more precise catalysis by the degrading enzyme, further enhancing the thoroughness of degradation. It should be noted that in this application, the enzyme activity is determined by the olive oil emulsion titration method, measuring the amount of fatty acids produced by the enzyme-catalyzed hydrolysis of fats, and converting this amount into enzyme activity.

[0077] In some embodiments, the degrading enzyme comprises a lipase. Further, the degrading enzyme comprises a lipase derived from Pseudomonas. Lipases exhibit highly specific catalytic activity towards the urethane bonds of polyurethanes, are heat-resistant, and adaptable to dual-response degradation systems, thus avoiding the degradation of enzyme activity by the high temperatures of heat degradation.

[0078] In some embodiments, the mass ratio of the composite foaming material to the degrading enzyme is 100:(0.5~1.5), for example, it can be 100:0.5, 100:0.8, 100:1, 100:1.2, 100:1.5, or any range between two of the above ratios. Within the range of the mass ratio, it is beneficial to improve the degradation efficiency of the composite foaming material.

[0079] It is understood that the water is used to dissolve the degradation enzymes and create a suitable degradation environment for them.

[0080] In some embodiments, the mass concentration of the degrading enzyme and the composite foaming material in the water is 0.5 g / mL to 10 g / mL, for example, it can be 0.5 g / mL, 1 g / mL, 2 g / mL, 5 g / mL, 8 g / mL, 10 g / mL, or any range between two of the above values. Within this mass concentration range, it is beneficial to create a suitable degradation environment. It should be noted that the mass concentration of the degrading enzyme and the composite foaming material in the water refers to (the sum of the masses of the degrading enzyme and the composite foaming material) / the volume of water.

[0081] In some embodiments, the temperature for thermal degradation is 115℃~125℃, for example, it can be 115℃, 118℃, 120℃, 122℃, 125℃, or any range between two of the above values; the time for thermal degradation is 2.5h~3.5h, for example, it can be 2.5h, 2.8h, 3h, 3.2h, 3.5h, or any range between two of the above values. Under the conditions of thermal degradation, the temperature-responsive materials in the composite foam material are more likely to fully exert their degradation effect, disrupting the spatial structure of the polyurethane molecular chain through conformational changes, and promoting the binding degradation effect of degrading enzymes and enzyme-affinity materials, thereby improving the degradation efficiency.

[0082] It should be noted that, in order to achieve uniform degradation, stirring can be carried out during the heating and degradation process, and the stirring rate can be 180 r / min to 220 r / min.

[0083] In some embodiments, please continue reading Figure 1 After obtaining the depolymerization product, the degradation and recycling method further includes: Step S13: The depolymerization product is subjected to vacuum distillation and adsorption with an adsorbent to obtain a regenerated polyol. It can be understood that the regenerated polyol can be reacted again with other raw materials to prepare composite foam materials.

[0084] In some embodiments, the pressure of the vacuum distillation is 0.07 MPa to 0.09 MPa, for example, 0.07 MPa, 0.075 MPa, 0.08 MPa, 0.085 MPa, 0.09 MPa, or any range between two of the above values; the temperature of the vacuum distillation is 140°C to 160°C, for example, 140°C, 145°C, 150°C, 155°C, 160°C, or any range between two of the above values; the time of the vacuum distillation is 20 min to 40 min, for example, 20 min, 25 min, 30 min, 35 min, 40 min, or any range between two of the above values. Thus, under the above-described vacuum distillation conditions, it is beneficial to thoroughly remove low-boiling-point impurities.

[0085] In some embodiments, the adsorbent comprises one or more of activated carbon, activated alumina, silica gel, molecular sieves, and macroporous resins. The adsorbent can remove pigments and residual degrading enzymes without introducing additional impurities, yielding high-purity regenerated polyols.

[0086] In some embodiments, the mass ratio of the depolymerization product to the adsorbent is 100:(0.5~1.5), for example, it can be 100:0.5, 100:0.8, 100:1, 100:1.2, 100:1.5, or any range between two of the above ratios. Within the range of the mass ratio, it is beneficial for the adsorption of pigments and impurities from the depolymerization product.

[0087] In some embodiments, the adsorption temperature is 70℃~90℃, for example, it can be 70℃, 75℃, 80℃, 85℃, 90℃, or any range between two of the above values; the adsorption time is 30min~60min, for example, it can be 30min, 40min, 50min, 55min, 60min, or any range between two of the above values. Thus, under the above adsorption conditions, the purification effect is enhanced.

[0088] This application constructs a temperature-enzyme dual-response synergistic degradation system. By adding a customized dual-response degradation agent during the polyurethane foam preparation stage, combined with the synergistic treatment of "thermal degradation and enzyme catalysis," the spatial structure destruction of the polyurethane molecular chain and the cleavage of urethane bonds are achieved simultaneously. This innovation overcomes the limitations of existing single degradation mechanisms, effectively improving the depolymerization rate and the purity of the regenerated polyol, while reducing energy consumption and pollution. This application also develops a high-temperature resistant lipase selection and process parameter optimization scheme adapted to the dual degradation system. A Pseudomonas-derived lipase with an enzyme activity ≥1000 U / g is selected, which can maintain more than 85% activity at 120℃, perfectly matching the trigger temperature of the temperature-responsive degradation agent. Simultaneously, parameters such as the amount of lipase added are optimized to ensure synergistic degradation efficiency, solving the problems of existing room-temperature enzymes being unable to adapt to high-temperature environments and having low catalytic efficiency, thus improving the industrial feasibility of the process. This application establishes an integrated process of "depolymerization and simplified purification" and enables high-end applications. Through a simplified process of "reduced pressure distillation and adsorbent adsorption", high-purity regenerated polyols can be obtained without complex purification equipment. These polyols can be directly used in the preparation of high-end refrigerator insulation layers, breaking through the bottleneck of "downgraded use" of existing recycled products, reducing recycling costs, and enhancing the market competitiveness of the technology.

[0089] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0090] Example 1 This embodiment provides a composite foam material and its degradation and recycling method. It should be noted that, in order to accelerate performance testing, the embodiment describes the degradation and recycling of the prepared composite foam material. In actual process, the composite foam material after it has been scrapped can be degraded and recycled.

[0091] The preparation method of composite foamed materials is as follows: Step S20: Mix the raw materials in the following mass ratio: polyether polyol (molecular weight 3000): isocyanate (MDI-50): dual-response degrading agent: foaming agent (cyclopentane): catalyst (dibutyltin dilaurate) = 100:120:3:5:1. Stir and react at 60°C for 5 minutes, then inject into a mold and foam at room temperature to obtain a composite foam material containing the dual-response degrading agent. The dual-response degrading agent is obtained by mixing raw materials in the following mass ratio: N-isopropylacrylamide: polyethylene glycol monomethyl ether methacrylate: N,N'-methylenebisacrylamide = 5:3:2.

[0092] The degradation and recycling methods for composite foam materials are as follows: Step S21: Pre-treat the composite foam material: crush it to an average particle size of 5mm~10mm, remove impurities, and dry it to a moisture content of ≤1%; Step S22: Add the pretreated composite foaming material to the reactor, add lipase (from Pseudomonas, enzyme activity 1200 U / g) and deionized water. The amount of lipase added is 1% of the mass of the composite foaming material. The ratio of the mass of lipase to the composite foaming material and the volume of lipase to deionized water is 1g:100mL. After sealing, heat to 120℃ for degradation treatment. Stir at 200r / min and react for 3h to obtain the depolymerization product. Step S23: The depolymerization product is distilled at 150℃ and 0.08MPa under reduced pressure for 30 min, and then activated carbon with a mass fraction of 1% of the depolymerization product is added and adsorbed at 80℃ for 30 min. The product is then filtered to obtain the regenerated polyol.

[0093] Example 2 Example 2 is basically the same as Example 1, except that: In step S20, the mass ratio of polyether polyol to dual-response degrading agent is 100:2.

[0094] Example 3 Example 3 is basically the same as Example 1, except that: In step S20, the mass ratio of polyether polyol to dual-response degrading agent is 100:5.

[0095] Example 4 Example 4 is basically the same as Example 1, except that: In step S22, the amount of lipase added is 0.5% of the mass of the composite foaming material.

[0096] Example 5 Example 5 is basically the same as Example 1, except that: In step S22, the amount of lipase added is 1.5% of the mass of the composite foaming material.

[0097] Example 6 Example 6 is basically the same as Example 1, except that: In step S22, after sealing, the temperature is raised to 115°C for degradation treatment.

[0098] Example 7 Example 7 is basically the same as Example 1, except that: In step S22, after sealing, the temperature is raised to 125°C for degradation treatment.

[0099] Comparative Example 1 Comparative Example 1 uses an alcoholysis recovery process to degrade and recover the composite foam material in Example 1: ethylene glycol is used as the depolymerization agent, the degradation temperature is 200℃, the pressure is 0.5MPa, and the degradation time is 4h.

[0100] Comparative Example 2 Comparative Example 2 uses a physical crushing and recycling process to degrade and recycle the composite foam material in Example 1: waste polyurethane foam is crushed to a particle size of 1 mm.

[0101] Comparative Example 3 Comparative Example 3 uses a single enzyme degradation process to degrade and recover the composite foam material in Example 1: At 25°C, 1.0% by mass of conventional lipase (non-thermal resistant type) is added to the pretreated composite foam material, and the degradation time is 24 hours.

[0102] Comparative Example 4 Comparative Example 4 is basically the same as Example 1, except that no dual-response degradation agent was added to the composite foam material.

[0103] The depolymerization rate of the composite foamed material, the purity of the recycled polyol, and the thermal conductivity of the recycled polyol after being applied to the recycled composite foamed material were tested in the degradation and recycling methods of the composite foamed material in Examples 1-7 and Comparative Examples 1-4. The test results are shown in Table 1.

[0104] The depolymerization rate refers to the percentage of the mass of the composite foam material converted into recycled polyols after degradation relative to the mass of the original composite foam material. It is calculated by weighing the pretreated composite foam material and the insoluble matter after depolymerization, using the formula: "(mass after pretreatment - mass of insoluble matter) / mass after pretreatment × 100%".

[0105] The purity of the regenerated polyols was quantitatively analyzed using gel permeation chromatography (GPC) with standard polyether polyols as a reference.

[0106] The thermal conductivity of recycled polyols used in recycled composite foam materials refers to the thermal conductivity of the recycled composite foam material prepared by the recycled polyols according to the corresponding methods, and tested using the GB / T 10294-2008 standard "Determination of Steady-State Thermal Resistance and Related Properties of Insulation Materials - Protective Hot Plate Method". It should be noted that, typically, high-end refrigerators require recycled composite foam materials with a thermal conductivity requirement of less than or equal to 0.022 mW / (m·K).

[0107] Table 1

[0108] From Table 1, we can obtain: In Examples 1-7 of this application, the addition of a dual-response degrading agent and the use of "temperature-enzyme" dual degradation treatment resulted in a depolymerization rate of ≥95% and a regenerated polyol purity of ≥99.2%. In contrast, the depolymerization rate of Control Example 4 (without dual-response degrading agent) was only 82.5%, and the regenerated polyol purity was 96.8%. This indicates that the dual-response synergistic degradation system can significantly improve depolymerization efficiency and regeneration purity. Examples 1-7 of this application use lipases derived from Pseudomonas, which maintain high catalytic activity at 120°C and can complete efficient depolymerization within 3 hours; while the depolymerization rate of control example 3 (single room temperature enzyme degradation) is only 78.3% after 24 hours, indicating that the selection of heat-resistant lipase and parameter optimization can significantly improve degradation efficiency. The recycled polyols in Examples 1-7 of this application have a purity of ≥99.2% after simple purification, and the prepared recycled foam has a thermal conductivity of ≤0.022W / (m·K), which meets the requirements of high-end refrigerator insulation layers. In contrast, the purity of Control Example 1 (chemical depolymerization) is only 94.5%, and Control Example 2 (physical recycling) cannot be used in high-end fields. This shows that the integrated "depolymerization-simple purification" process of this invention can realize the high-end application of recycled products. Furthermore, it was found that in the degradation and recycling process, Comparative Example 1 produces toxic byproducts and has a large amount of wastewater discharge; Comparative Example 2 generates a large amount of dust pollution during crushing; Comparative Example 3 has low efficiency and the degradation and recycling process in the comparative examples consumes a lot of energy, which can easily cause secondary pollution.

[0109] The degradation and recycling process of composite foam materials provided in this application has multiple benefits, specifically: (1) Environmental benefits: It avoids the toxic byproducts of chemical depolymerization and the dust pollution of physical crushing, realizes the green recycling of waste polyurethane foam, reduces environmental accumulation and pollution, and meets the requirements of ESG circular development; (2) Economic benefits: The depolymerization energy consumption is low, the purification process is simple, and the recycling cost is reduced; the recycled polyol can be directly used in high-end fields, which increases the added value of recycled products and realizes "turning waste into treasure"; (3) Technical benefits: It achieves the synergistic optimization of high depolymerization rate, high recycling purity (and short depolymerization time), which solves the core pain points of existing technologies; the process parameters are mild and easy to scale up industrially; (4) Social benefits: It promotes the technological upgrading of the waste insulation material recycling industry, alleviates the resource shortage problem, and helps green and low-carbon development.

[0110] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composite foaming material, characterized in that, It includes polyols, isocyanate compounds, foaming agents, and dual-response degrading agents; wherein the dual-response degrading agents include temperature-responsive materials and enzyme-affinity materials.

2. The composite foamed material as described in claim 1, characterized in that, The minimum critical dissolution temperature of the temperature-responsive material is 30℃~45℃; The temperature-responsive material includes one or more of N-isopropylacrylamide, N-vinylcaprolactam, and polyN,N-diethylacrylamide; The enzyme-affinity material includes acrylate materials containing hydrophilic groups; The acrylate materials containing hydrophilic groups include one or more of polyethylene glycol monomethyl ether methacrylate, polyethylene glycol acrylate, and hydroxyethyl methacrylate.

3. The composite foamed material as described in claim 1 or 2, characterized in that, The dual-response degradative agent also includes a crosslinking agent; wherein... The crosslinking agent includes one or more of N,N'-methylenebisacrylamide, trimethylolpropane triacrylate, and ethylene glycol dimethacrylate; In the dual-response degradation agent, the mass ratio of the temperature-responsive material, the enzyme-affinity material, and the crosslinking agent is (4~6):(2~4):(1~3).

4. The composite foamed material as described in claim 3, characterized in that, The polyol includes polyether polyols; the molecular weight of the polyether polyol is 2000~4000; The isocyanate compounds include one or more of isocyanates and diphenylmethane diisocyanate; The foaming agent includes an alkane foaming agent; the alkane foaming agent includes one or more of cyclopentane and isopentane; In the composite foaming material, the mass ratio of the polyol, the isocyanate compound, the foaming agent and the dual-response degradation agent is 100:(110~130):(3~7):(2~5).

5. The composite foamed material as described in claim 1, characterized in that, The composite foaming material also includes a catalyst; wherein... The catalyst includes one or more of organometallic salt catalysts and amine catalysts; the organometallic salt catalyst includes one or more of dibutyltin dilaurate, bismuth octanoate, and bismuth neodecanoate; the amine catalyst includes one or more of triethylenediamine, dimethylcyclohexylamine, and N,N-dioctylcyclohexylamine. The mass ratio of the polyol to the catalyst is 100:(0.5~1.5).

6. A method for degrading and recycling composite foamed materials, characterized in that, Includes the following steps: Provide a composite foaming material as described in any one of claims 1 to 5; A degrading enzyme and water are provided, mixed with the composite foaming material, and heated to degrade it, yielding a depolymerization product.

7. The degradation and recycling method as described in claim 6, characterized in that, Before the composite foaming material is mixed with the degradation enzyme, the process further includes: pretreatment; The pretreatment includes one or more of the following: impurity removal, pulverization, and drying; The pulverization includes pulverizing the composite foam material to an average particle size of 5mm to 10mm.

8. The degradation and recycling method as described in claim 6, characterized in that, The enzyme activity of the degrading enzyme is greater than or equal to 1000 U / g; The degrading enzyme includes lipase; the degrading enzyme includes lipase derived from Pseudomonas. The mass ratio of the composite foaming material to the degrading enzyme is 100:(0.5~1.5). The mass concentration of the degradation enzyme and the composite foaming material in the water is 0.5 g / mL to 10 g / mL; The temperature for the heat degradation is 115℃~125℃, and the time for the heat degradation is 2.5h~3.5h.

9. The degradation and recycling method as described in claim 6, characterized in that, After obtaining the depolymerization product, the degradation and recycling method of the composite foam material further includes: The depolymerization product is subjected to vacuum distillation and adsorption with an adsorbent to obtain a regenerated polyol. It can be understood that the regenerated polyol can be reacted with other raw materials again to prepare composite foamed materials.

10. The degradation and recycling method as described in claim 9, characterized in that, The pressure of the vacuum distillation is 0.07MPa~0.09MPa, the temperature of the vacuum distillation is 140℃~160℃, and the time of the vacuum distillation is 20min~40min. The adsorbent includes one or more of activated carbon, activated alumina, silica gel, molecular sieve, and macroporous resin; The mass ratio of the depolymerization product to the adsorbent is 100:(0.5~1.5). The adsorption temperature is 70℃~90℃, and the adsorption time is 30min~60min.

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