Preparation method and application of a double-hole structure temperature regulating foam

Abstract

This invention discloses a method for preparing and applying a biporous temperature-regulating foam, belonging to the interdisciplinary field of functional materials and phase change energy storage. The method uses melamine foam as a matrix, fills some of the foam pores with phenolic resin, and then foams it again to form a biporous foam skeleton. Polyethylene glycol is then added under vacuum adsorption to modify the foam, resulting in a temperature-regulating foam with high enthalpy and dual encapsulation characteristics, while also possessing temperature regulation and photothermal conversion functions. This method is highly operable, uses simple equipment, has a short process, and is energy-efficient, ensuring full utilization of all component materials without waste. The resulting temperature-regulating foam generally does not leak phase change materials and can be recycled multiple times. It also possesses a large melting enthalpy and crystallization enthalpy, achieving excellent temperature regulation effects.

Description

Technical Field

[0001] This invention relates to the field of functional materials and phase change energy storage technologies, specifically to a method for preparing and applying a dual-pore structure temperature-regulating foam. Background Technology

[0002] Against the backdrop of the global energy structure's low-carbon transformation, phase change energy storage technology, with its advantages of high thermal density and isothermal heat release, is widely used in fields such as building energy conservation, intelligent temperature regulation of textiles, and industrial waste heat recovery. Solid-liquid phase change materials (such as polyethylene glycol) have excellent thermal storage performance, but they have shortcomings such as easy leakage when melted and poor flame retardancy. Three-dimensional porous foam, with its capillary adsorption and spatial confinement effect, has become the mainstream carrier for encapsulating phase change materials. Among them, melamine foam (MF) is lightweight, highly porosilicate, flame retardant, and has outstanding resilience, making it an ideal supporting framework.

[0003] Existing technologies using melamine foam to support phase change materials have several drawbacks. For example, patent CN122037299 A discloses a process for preparing biomimetic temperature-regulating foam by impregnating melamine foam with phenolic resin and vacuum adsorbing polyethylene glycol. This method relies solely on phenolic resin to fill the pores of the foam framework; the resin does not foam in situ within the foam, and the increase in adsorption sites is limited by resin adhesion, resulting in limited pore refinement. In practical applications, two major shortcomings exist: first, the effective adsorption pore volume inside the foam is relatively small, leading to a low loading of phase change materials; second, there is significant room for improvement in the material's melting enthalpy and crystallization enthalpy, resulting in insufficient heat storage capacity and a significant decrease in temperature regulation effect after long-term cycling, making it difficult to meet the demands of high heat storage conditions.

[0004] Meanwhile, existing patents related to resin foaming all adopt a mold-based integral foaming molding route, which is fundamentally different from the process logic of this invention. For example, patent CN 103435969 A discloses a process for preparing epoxy-modified phenolic open-cell foam, which involves uniformly mixing modified phenolic resin, compound surfactant, alkane foaming agent, and mixed acid curing agent, and then injecting the mixture into a preheated mold. Foaming and curing are completed inside the mold cavity, and after demolding, a whole rigid phenolic foam is obtained. The cells are generated entirely within the mold space, making it impossible to build a composite multi-level porous structure based on existing flexible porous frameworks. The foam is brittle and cannot be used as a flexible phase change carrier. For example, patent CN 103146016 A uses rosin as a pore-forming agent. After premixing melamine-formaldehyde resin, it is cured in a mold at room temperature. Then, rosin is dissolved in a solvent to create pores. The entire process involves forming a single-component melamine foam in the mold. It relies solely on the dissolution of the pore-forming agent to form single-scale pores. There is no design for the resin to foam again inside the existing foam to build a two-level pore structure, nor does it have the function of loading phase change materials to achieve energy storage and temperature regulation.

[0005] Although both patents use similar additives such as foaming agents, surfactants, and acid curing agents, the foaming and curing reactions occur independently in the closed space of the mold, aiming to synthesize a single piece of resin foam. They cannot reconstruct the internal pore structure of the finished porous foam, and cannot simultaneously meet the triple requirements of flexible skeleton, multi-level adsorption channels, and high phase change load.

[0006] It is worth noting that, unlike free foaming in a hollow environment within a mold, the process of directly completing resin foaming and curing within the pores of melamine foam has extremely high technological barriers and requires targeted and systematic research: the three-dimensional network skeleton of melamine foam constrains the free expansion of the resin foaming system, and the foam fibers hinder the uniform diffusion of foaming gas, which easily leads to problems such as insufficient local foaming, uneven cell size, resin agglomeration and pore blockage, and insufficient generation of secondary pores. Ultimately, this results in an unsatisfactory overall foaming effect. The composite skeleton has a simple pore structure, which cannot achieve the high load and double-layer leak-proof effect of phase change materials. This is also the key reason why existing technologies have not adopted the in-situ foaming solution within the foam.

[0007] Based on the above-mentioned existing technologies, it can be found that: simple melamine foam has a relatively large pore size, making it prone to localized accumulation and leakage of phase change materials; CN 122037299 A only involves simple coating and filling resin without in-situ foaming and pore-forming, resulting in low phase change adsorption capacity and heat storage enthalpy; CN 103435969 A and CN 103146016 A use mold-based integral foaming, which cannot generate fine secondary channels inside the finished foam, resulting in high foam rigidity and no heat storage and temperature regulation function; and directly foaming and curing resin inside melamine foam lacks mature process support, and without parameter exploration, the foaming effect is poor, making it difficult to form a multi-level dual-pore structure. Therefore, there is currently a lack of a complete process exploration method that can stably foam resin in-situ inside the flexible melamine foam skeleton to construct a dual-pore hierarchical structure, achieving integrated temperature-regulating foam preparation with high load capacity, leak prevention, and high enthalpy value of phase change materials. Summary of the Invention

[0008] Technical issues Existing temperature-controlled foams suffer from low adsorption capacity of phase change materials and insufficient melting enthalpy. At the same time, there is a lack of mature preparation processes that can stably complete resin foaming and construct a biporous structure inside melamine foam, while taking into account a flexible skeleton, high phase change load and leak-proof effect.

[0009] Technical content To address the aforementioned technical challenges, this invention utilizes a three-dimensional porous foam as a matrix, modifying it with resin and phase change materials (PCMs) to impart dual encapsulation and temperature regulation capabilities. This method is simple to operate, has low preparation costs, and improves the thermal performance of PCMs. The design constructs a biporous composite foam by foaming and curing phenolic resin (PR) in a microfiber matrix (MF). This foam possesses abundant interfacial bonding sites, synergistically combining capillary action and physical adsorption to achieve a high loading capacity for the PCM. Simultaneously, it enhances the mechanical strength of the framework, preventing leakage due to extrusion of the PCM in its molten state. The resulting temperature-regulating foam exhibits excellent shape stability and durability. The preparation process of this temperature-regulating foam is simple, maintaining not only a high phase change enthalpy and cyclic thermal stability but also, leveraging the intrinsic properties of the framework, simultaneously integrating high photothermal conversion and flame-retardant properties. This solves the problem of the single function of conventional MF matrices and provides a new strategy for developing integrated, multifunctional temperature-regulating foams for various applications such as waste heat recovery and high-temperature protection.

[0010] The first objective of this invention is to provide a method for preparing a dual-pore structure temperature-regulating foam, the method comprising the following steps: (1) Preparation of resin foaming solution: Dissolve resin in ethanol, stir evenly to obtain resin solution, then add foaming agent to it, stir evenly to obtain resin foaming solution; (2) Preparation of a dual-pore composite foam skeleton: clean and dry the foam, then place the treated foam in a resin foaming solution, squeeze and impregnate it, then foam, cure and dry to obtain a dual-pore composite foam skeleton. (3) Preparation of temperature-regulating foam: The composite foam prepared in step (2) is immersed in molten phase change material and vacuum adsorption is performed. Then, excess phase change material on the surface of the composite foam is removed, and finally, temperature-regulating foam is obtained.

[0011] In one embodiment of the present invention, the resin mentioned in step (1) is selected from any one or more of the following: phenolic resin, phthalic acid nitrile resin, polyurethane, epoxy resin, and urea-formaldehyde resin.

[0012] Preferably, the resin mentioned in step (1) is selected from phenolic resin, epoxy resin or urea-formaldehyde resin.

[0013] In one embodiment of the present invention, the ethanol mentioned in step (1) is anhydrous ethanol or an ethanol solution with a water content of less than 10 wt%.

[0014] In one embodiment of the present invention, the ethanol mentioned in step (1) can be replaced with acetone.

[0015] In one embodiment of the present invention, the mass concentration of resin in the resin foaming solution in step (1) is 1~50 wt%.

[0016] In one embodiment of the present invention, the mass concentration of resin in the resin foaming solution in step (1) is 5~20 wt%.

[0017] In one embodiment of the present invention, the resin concentration in the resin foaming solution in step (1) is 10~15 wt%.

[0018] In one embodiment of the present invention, the foaming agent in step (1) is determined according to the type of resin; If the resin is phenolic resin, the foaming aid consists of a foaming agent, a curing agent, and a surfactant. The foaming agent can be one or more of Freon, dichloromethane, n-pentane, isopentane, n-butane, and petroleum ether. The curing agent can be one or more of sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, benzenesulfonic acid, p-toluenesulfonic acid, and acetic acid. The surfactant can be one or more of Tween-80, Tween-20, alkylphenol polyoxyethylene ether, and sodium fatty alcohol polyoxyethylene ether sulfate. If the resin is epoxy resin, the foaming agent is a foaming agent and a curing agent; the foaming agent can be one or more of sodium bicarbonate, sodium borohydride, hydrogen peroxide, azodicarbonamide, and dinitrosopeptimide; the curing agent can be one or more of aliphatic amines, alicyclic amines, aromatic amines, polyamides, polysulfides, polyetheramines, phthalic anhydride, and pyromellitic dianhydride. If the resin is urea-formaldehyde resin, the foaming aid consists of a foaming agent, a curing agent, and a surfactant. The foaming agent can be one or more of sodium bicarbonate, sodium carbonate, ammonium bicarbonate, and toluene diisocyanate. The curing agent can be one or more of ammonium chloride, ammonium sulfate, phosphoric acid, acetic acid, tartaric acid, citric acid, and oxalic acid. The surfactant can be one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and Tween-80.

[0019] In one embodiment of the present invention, the mass ratio of resin to surfactant is 3-10:1.

[0020] In one embodiment of the present invention, the mass ratio of resin to foaming agent is 3-10:1.

[0021] In one embodiment of the present invention, the mass ratio of resin to curing agent is 3-30:1.

[0022] In one embodiment of the present invention, the mass ratio of resin to curing agent is 3-10:1.

[0023] In one embodiment of the present invention, the stirring speed in step (1) is 800~1000 rpm and the time is 20-30 min.

[0024] In one embodiment of the present invention, the foam mentioned in step (2) is selected from any of the following: melamine foam, polyurethane foam, polyvinyl chloride foam, porous carbon foam, nickel foam, copper foam, and boron nitride foam.

[0025] In one embodiment of the present invention, the volume of the foam in step (2) is not limited; the density of the foam is 0.001-5.000 g / cm³. 3 .

[0026] In one embodiment of the present invention, the number of times of squeezing and impregnation in step (2) is 5-50 times.

[0027] In one embodiment of the present invention, the foaming, curing and drying temperature in step (2) is 60-100 °C.

[0028] In one embodiment of the present invention, the foaming, curing and drying time in step (2) is 1-5 h.

[0029] In one embodiment of the present invention, the phase change material mentioned in step (3) is selected from any one or more of the following: Inorganic salts: crystalline hydrated salts (calcium chloride hexahydrate, sodium sulfate decahydrate, disodium hydrogen phosphate dodecahydrate, etc.), molten salts (nitrates, chlorides, etc.), metals and alloys (low-melting-point metals, aluminum-based alloys, etc.); Organic compounds: paraffins (alkanes), fatty acids (decanoic acid, lauric acid, palmitic acid, stearic acid and their eutectics, etc.), polyols (such as pentaerythritol, neopentyl glycol, etc.), and polyethylene glycols; Eutectic systems: organic-organic, inorganic-inorganic, and organic-inorganic mixed systems.

[0030] Specifically, the phase change material may be selected from polyethylene glycol (PEG1000, PEG2000), lauric acid, or stearic acid.

[0031] In one embodiment of the present invention, the temperature of the molten phase change material in step (3) is 30-100 °C.

[0032] In one embodiment of the present invention, the vacuum adsorption time in step (3) is 2 to 6 hours.

[0033] In one embodiment of the present invention, the vacuum degree of vacuum adsorption in step (3) is -0.4 to -0.8 bar.

[0034] A second objective of this invention is to provide a temperature-regulating foam prepared by the above-described method.

[0035] The third objective of this invention is to apply the above-mentioned temperature-regulating foam to the fields of textiles and building energy conservation.

[0036] Beneficial effects (1) This invention abandons the overall foaming of the mold and foams phenolic resin in situ inside the melamine foam to construct a primary and secondary interconnected double-pore structure, generating a large number of 60~90 μm secondary pores, providing sufficient interface binding sites; relying on the synergistic capillary adsorption of the double pores, the loading of polyethylene glycol is greatly improved, the melting enthalpy and crystallization enthalpy are significantly increased, the heat storage capacity is higher, and the thermal cycling stability is excellent.

[0037] (2) The double-hole skeleton of the present invention can form a double-layer encapsulation and confinement effect, which enhances the mechanical strength of the composite foam, avoids leakage of the phase change material after melting due to compression, and greatly improves the material shape stability and durability, thus solving the problem of easy leakage of traditional foam phase change materials.

[0038] (3) This invention solves the problems of uneven foaming and pore blockage in foam by systematically exploring key parameters such as resin concentration, foaming agent, impregnation and curing. The whole preparation process is short, the equipment requirements are low, the operation is simple, the raw material utilization rate is high, the production cost is low, and it is easy to scale up production. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the process for temperature-controlled foam. Figure 2 This is a scanning electron microscope image of the dual-pore composite foam skeleton prepared in Example 1; Figure 3 This is a scanning electron microscope image of the temperature-controlled foam prepared in Example 1. Figure 4 The stress-strain curves of the dual-pore composite foam skeletons prepared in Examples 1-3 are shown. Figure 5 The image shows the pore size distribution of the dual-pore composite foam skeleton prepared in Example 1. Figure 6 Phase change energy storage curves of the temperature-controlled foams prepared in Examples 1-3; Figure 7 Leakage-resistant images of the temperature-regulating foams prepared in Examples 1-3; Figure 8 The thermal cycling stability of the temperature-controlled foam prepared in Example 1. Detailed Implementation

[0040] Source of raw materials Melamine foam was purchased from Sichuan Chaoju New Material Technology Co., Ltd., measuring 3.5 × 3 × 1 cm. 3 The mass is 0.09±0.01 g under the specified conditions.

[0041] Example 1 Preparation of temperature-regulating foam with a dual-pore structure: (1) Preparation of resin foaming solution: Weigh 1.5 g of phenolic resin (PR), 8.5 g of anhydrous ethanol (EtOH), 0.3 g of Tween-80, and 0.27 g of n-pentane, place them in a 50 mL beaker and dissolve them at 25 °C. Stir at 800 rpm for 15 min, add 0.3 g of 40% sulfuric acid (H2SO4), and stir for 30 min to form a phenolic resin foaming solution (the mass concentration of phenolic resin is about 15 wt%).

[0042] (2) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The sample was ultrasonically cleaned in ethanol for 30 min, then repeatedly rinsed with deionized water, and finally dried in an 80 °C oven for 2 h. MF was then immersed in a prepared phenolic resin foaming solution, repeatedly squeezed and impregnated, and placed in an 80 °C oven for foaming and curing for 3 h. This sample was designated MF / PF-15.

[0043] (3) MF / PF-15 was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. During this process, the filter paper was changed continuously until the sample no longer leaked PEG. The sample was labeled PEG / MF / PF-15.

[0044] The process of preparing the temperature-regulating foam in the above steps is as follows: Figure 1 As shown. Scanning electron microscope images of the biporous composite foam skeleton and the temperature-regulating foam obtained in steps (2) and (3) are shown below. Figure 2 , Figure 3 As shown. The mechanical properties of the foam skeleton obtained in step (2) are as follows. Figure 4 As shown.

[0045] from Figure 2 , 3 It can be seen that after phenolic resin impregnation, the pores of the MF skeleton are filled and covered by the phenolic resin, and pores remain on the resin surface, proving that the foaming and curing were successful. After vacuum adsorption of PEG, the pores of MF / PF-15 are filled, resulting in a rough surface, which increases the contact area between PEG and heat, thus improving the material's heat transfer efficiency. From Figure 4 , 5It can be seen that the mechanical strength of MF / PF-15 is improved due to the modification of phenolic resin. MF / PF-15 generates smaller pores than pure MF, mainly distributed at around 60-70 μm and 90 μm, which can achieve the effect of double-layer encapsulation of PEG.

[0046] Phase change energy storage of the above-mentioned temperature-regulating foam ( Figure 6 ), leak-proof ( Figure 7 Analysis of the PEG / MF / PF-15 and its thermal conductivity (Table 1) showed that the melting temperature was 54.7 °C, the enthalpy of melting was 172.1 J / g, the crystallization temperature was 28.7 °C, and the enthalpy of crystallization was 165.7 J / g. A leak-resistance test was conducted on a 60 °C heating platform, and no leakage was found in the PEG / MF / PF-15. The thermal conductivity was 0.229 W·m. -1 ·K -1 .

[0047] The thermal cycling stability of the aforementioned temperature-regulating foam was evaluated, such as... Figure 8 As shown, after 100 heating and cooling cycles, the melting and crystallization curves of the temperature-controlled foam did not change significantly before and after the cycles. Furthermore, the melting enthalpy of PEG / MF / PF-15 after the cycles was 171.0 J / g, and the crystallization enthalpy was 165.7 J / g, with almost no change in enthalpy values. This indicates that the temperature-controlled foam has excellent cycling stability and good thermal reliability.

[0048] Table 1 Thermal conductivity of temperature-regulating foam

[0049] Example 2 Preparation of temperature-regulating foam with a dual-pore structure: (1) Preparation of resin foaming solution: Weigh 1.0 g of phenolic resin (PR), 9.0 g of anhydrous ethanol (EtOH), 0.2 g of Tween-80, and 0.18 g of n-pentane, place them in a 50 mL beaker and dissolve them at 25 °C. Stir at 800 rpm for 15 min, add 0.2 g of 40% sulfuric acid (H2SO4), and stir for 30 min to form a phenolic resin foaming solution (the mass concentration of phenolic resin is about 10 wt%).

[0050] (2) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The sample was ultrasonically cleaned in ethanol for 30 min, then repeatedly rinsed with deionized water, and finally dried in an 80 °C oven for 2 h. MF was then immersed in a prepared phenolic resin foaming solution, repeatedly squeezed and impregnated, and placed in an 80 °C oven for foaming and curing for 3 h. This sample was designated MF / PF-10.

[0051] (3) MF / PF-10 was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. During this process, the filter paper was changed continuously until the sample no longer leaked PEG. The sample was labeled PEG / MF / PF-10.

[0052] Phase change energy storage and leakage resistance studies were conducted on the above-mentioned temperature-regulating foam. The prepared foam has a melting temperature of 57.0°C, a melting enthalpy of 166.7 J / g, a crystallization temperature of 27.9°C, and a crystallization enthalpy of 153.1 J / g. Leakage resistance tests conducted on a 60°C heating platform revealed no leakage in the prepared temperature-regulating foam.

[0053] Example 3 Preparation of temperature-regulating foam with a dual-pore structure: (1) Preparation of resin foaming solution: Weigh 0.5 g of phenolic resin (PR), 9.5 g of anhydrous ethanol (EtOH), 0.1 g of Tween-80, and 0.09 g of n-pentane, place them in a 50 mL beaker and dissolve them at 25 °C. Stir at 800 rpm for 15 min, add 0.1 g of 40% sulfuric acid (H2SO4), and stir for 30 min to form a phenolic resin foaming solution (the mass concentration of phenolic resin is about 5 wt%).

[0054] (2) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The sample was ultrasonically cleaned in ethanol for 30 min, then repeatedly rinsed with deionized water, and finally dried in an 80 °C oven for 2 h. MF was then immersed in a prepared phenolic resin foaming solution, repeatedly squeezed and impregnated, and placed in an 80 °C oven for foaming and curing for 3 h. This sample was designated MF / PF-5.

[0055] (3) MF / PF-5 was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. During this process, the filter paper was changed continuously until the sample no longer leaked PEG. The sample was labeled PEG / MF / PF-5.

[0056] Phase change energy storage and leakage resistance studies were conducted on the above-mentioned temperature-controlled foam. The prepared foam has a melting temperature of 56.1°C, a melting enthalpy of 152.0 J / g, a crystallization temperature of 29.2°C, and a crystallization enthalpy of 140.0 J / g. Leakage resistance tests conducted on a 60°C heating platform showed that the prepared temperature-controlled foam did not leak.

[0057] Comparative Example 1 (1) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The sample was ultrasonically cleaned in ethanol for 30 minutes, then repeatedly cleaned with deionized water, and finally dried in an oven at 80 °C for 2 hours.

[0058] (2) MF was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. During this process, the filter paper was changed continuously until the sample no longer leaked PEG. The sample was recorded as PEG / MF.

[0059] Analysis of PEG adsorption and leakage of the above-mentioned temperature-controlled foam showed that the amount of PEG adsorbed by the prepared temperature-controlled foam was significantly less than that of the PEG / MF / PF temperature-controlled foam; and leakage tests conducted on a 60 °C heating platform revealed that a small amount of PEG flowed out of this temperature-controlled foam.

[0060] Comparative Example 2 (1) Preparation of resin solution: Weigh 2 g of phenolic resin (PR), 8 g of anhydrous ethanol (EtOH), 0.4 g of Tween-80, and 0.36 g of n-pentane, place them in a 50 mL beaker and dissolve them at 25 °C. Stir at 800 rpm for 15 min, add 0.4 g of 40% sulfuric acid (H2SO4), and stir for 30 min to form a foaming solution of phenolic resin (the mass concentration of phenolic resin is about 20 wt%).

[0061] (2) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The sample was ultrasonically cleaned in ethanol for 30 min, then repeatedly rinsed with deionized water, and finally dried in an 80 °C oven for 2 h. MF was then immersed in a prepared phenolic resin foaming solution, repeatedly squeezed and impregnated, and placed in an 80 °C oven for foaming and curing for 3 h. This sample was designated MF / PF-20.

[0062] (3) MF / PF-20 was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. During this process, the filter paper was changed continuously until the sample no longer leaked PEG. The sample was labeled PEG / MF / PF-20.

[0063] Phase change energy storage analysis was performed on the above-mentioned temperature-regulating foam. The prepared foam had a melting temperature of 58.4 °C, a melting enthalpy of 161.3 J / g, a crystallization temperature of 28.8 °C, and a crystallization enthalpy of 147.8 J / g. This material has a certain heat storage capacity, but compared with the optimal embodiment 1, both the melting enthalpy and the crystallization enthalpy are lower, indicating that excessive resin filling squeezes out the pores and reduces the upper limit of PEG loading.

[0064] Comparative Example 3 (1) Preparation of resin solution: Weigh 5 g of phenolic resin (PR), 5 g of anhydrous ethanol (EtOH), 1 g of Tween-80, and 0.9 g of n-pentane, place them in a 50 mL beaker and dissolve them at 25 °C. Stir at 800 rpm for 15 min, add 1 g of 40% sulfuric acid (H2SO4), and stir for 30 min to form a foaming solution of phenolic resin (the mass concentration of phenolic resin is about 50 wt%).

[0065] (2) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The sample was ultrasonically cleaned in ethanol for 30 minutes, then repeatedly rinsed with deionized water, and finally dried in an oven at 80 °C for 2 hours. MF was then immersed in a prepared phenolic resin foaming solution, repeatedly squeezed and impregnated, and placed in an oven at 80 °C for foaming and curing for 3 hours. This was designated as sample MF / PF-50.

[0066] (3) MF / PF-50 was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. During this process, the filter paper was changed continuously until the sample no longer leaked PEG. The sample was labeled PEG / MF / PF-50.

[0067] Mechanical property analysis of the foam skeleton formed in step (2) above showed large fluctuations in the compressive stress-strain curve. The main reason was that the excessive resin content led to increased brittleness of the foam skeleton, and under certain pressure, the resin skeleton collapsed, causing the entire skeleton to be destroyed. PEG adsorption tests were performed on the temperature-regulating foam formed in step (3) above, and it was found that due to the excessive resin content, most of the pores were filled, and the adsorbed PEG content decreased sharply compared to PEG / MF / PF-15.

[0068] Comparative Example 4 (1) Preparation of resin solution: Weigh 1.5 g of phenolic resin (PR) and 8.5 g of anhydrous ethanol (EtOH), place them in a 50 mL beaker, dissolve them at 25 °C, stir at 800 rpm for 15 min to form a homogeneous solution, add 0.3 g of 40% sulfuric acid (H2SO4) as a curing agent, stir for 30 min to form a resin solution.

[0069] (2) Cut the melamine foam (MF) into a certain size (3.5×3×1 cm). 3 The mixture was ultrasonically cleaned in ethanol for 30 minutes, then repeatedly rinsed with deionized water, and finally dried in an oven at 80 °C for 2 hours. MF was then immersed in the prepared resin solution, repeatedly squeezed and impregnated, and placed in an oven at 80 °C for foaming and curing for 3 hours, denoted as MF / PR.

[0070] (3) MF / PR was placed in an 80 °C vacuum oven (-0.6 bar) to adsorb PEG2000 for 4 h. After adsorption was complete, it was removed and dried on neutral filter paper, and then placed in the 80 °C oven again to remove excess PEG from the sample surface. The filter paper was changed continuously during this process until the sample no longer leaked PEG.

[0071] Surface morphology analysis of the above-mentioned temperature-regulating foam revealed that the phenolic resin did not foam inside the melamine foam. The resin was mostly in a closed state when solidified on the skeleton, and the resin concentration was relatively high, resulting in a large number of foam pores, which is not conducive to the subsequent encapsulation of phase change materials.

[0072] Comparative Example 5 Melamine foam (MF) was cut into a certain size (3.5×3×1 cm). 3The mixture was ultrasonically cleaned in ethanol for 30 min, then repeatedly rinsed with deionized water, and dried in an oven at 80 °C for 2 h. 1.5 g of phenolic resin (PR), 0.3 g of Tween-80, 0.24 g of n-pentane, and 0.3 g of 40% sulfuric acid (H2SO4) were mixed and stirred at 200 rpm for 10 min. MF was then immersed in the mixture, repeatedly pressed and impregnated, and finally placed in an oven at 80 °C for foaming and curing for 3 h.

[0073] During the preparation process, it was found that the high viscosity of phenolic resin led to uneven impregnation of the melamine foam, resulting in localized areas of excessive or unfilled resin, primarily distributed on the foam surface. Therefore, the foam skeleton preparation methods in Examples 1-3 are the optimal solutions.

[0074] The above are merely specific application examples of the present invention and do not constitute any limitation on the scope of protection of the present invention. All technical solutions formed by equivalent transformations or substitutions fall within the scope of protection of the present invention.

Claims

1. A method for preparing a dual-pore structure temperature-regulating foam, characterized in that, The method includes the following steps: (1) Preparation of resin foaming solution: Dissolve resin in ethanol, stir evenly to obtain resin solution, then add foaming agent to it, stir evenly to obtain resin foaming solution; (2) Preparation of a dual-pore composite foam skeleton: clean and dry the foam, then place the treated foam in a resin foaming solution, squeeze and impregnate it, then foam, cure and dry to obtain a dual-pore composite foam skeleton. (3) Preparation of temperature-regulating foam: The composite foam prepared in step (2) is immersed in molten phase change material and vacuum adsorption is performed. Then, excess phase change material on the surface of the composite foam is removed, and finally, temperature-regulating foam is obtained. The resin concentration in the resin foaming solution in step (1) is 10~15 wt%; The resin mentioned in step (1) is selected from phenolic resin, epoxy resin or urea-formaldehyde resin; the foaming aid is a foaming agent, a curing agent and a surfactant.

2. The preparation method according to claim 1, characterized in that, If the resin is phenolic resin, the foaming aid consists of a foaming agent, a curing agent, and a surfactant; the foaming agent is selected from one or more of Freon, dichloromethane, n-pentane, isopentane, n-butane, and petroleum ether; the curing agent is selected from one or more of sulfuric acid, hydrochloric acid, phosphoric acid, boric acid, benzenesulfonic acid, p-toluenesulfonic acid, and acetic acid; the surfactant is selected from one or more of Tween-80, Tween-20, alkylphenol polyoxyethylene ether, and sodium fatty alcohol polyoxyethylene ether sulfate. If the resin is epoxy resin, the foaming agent is a foaming agent and a curing agent; the foaming agent is selected from one or more of sodium bicarbonate, sodium borohydride, hydrogen peroxide, azodicarbonamide, and dinitrosopeptimethylenetetramine; the curing agent is selected from one or more of aliphatic amines, alicyclic amines, aromatic amines, polyamides, polysulfides, polyetheramines, phthalic anhydride, and pyromellitic dianhydride. If the resin is urea-formaldehyde resin, the foaming aid consists of a foaming agent, a curing agent, and a surfactant; the foaming agent is selected from one or more of sodium bicarbonate, sodium carbonate, ammonium bicarbonate, and toluene diisocyanate; the curing agent is selected from one or more of ammonium chloride, ammonium sulfate, phosphoric acid, acetic acid, tartaric acid, citric acid, and oxalic acid; and the surfactant is selected from one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfonate, and Tween-80.

3. The preparation method according to claim 1, characterized in that, The mass ratio of resin to surfactant is 3-10:1; the mass ratio of resin to foaming agent is 3-10:1; the mass ratio of resin to curing agent is 3-30:

1.

4. The preparation method according to claim 1, characterized in that, The foam mentioned in step (2) is selected from any of the following: melamine foam, polyurethane foam, polyvinyl chloride foam, porous carbon foam, nickel foam, copper foam, and boron nitride foam.

5. The preparation method according to claim 1, characterized in that, The number of times of squeezing and impregnation is 5-50 times in step (2).

6. The preparation method according to claim 1, characterized in that, The foaming, curing and drying temperature in step (2) is 60-100 °C and the time is 1-5 h.

7. The preparation method according to claim 1, characterized in that, The phase change material mentioned in step (3) is selected from polyethylene glycol, lauric acid or stearic acid.

8. The preparation method according to claim 1, characterized in that, The vacuum adsorption time in step (3) is 2~6 h, and the vacuum degree is -0.4~-0.8 bar.

9. A dual-pore structure temperature-regulating foam, characterized in that, The dual-pore structure temperature-regulating foam is prepared by the method according to any one of claims 1 to 8.

10. The application of the dual-pore structure temperature-regulating foam as described in claim 9 in the fields of textiles and building energy conservation.

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