Expanded graphite-based phase change temperature and humidity control material, dry gel in-situ synthesis method and application thereof

Abstract

The application discloses an expanded graphite-based phase change temperature and humidity control material and an in-situ dry glue synthesis method and application thereof. The synthesis method comprises the following steps: heating an organic phase change material to a molten state, adding hydrophilic modified expanded graphite powder, uniformly mixing, and then cooling and crystallizing to obtain a shaped composite phase change temperature control material powder; mixing an organic carboxylic acid ligand, sodium hydroxide and water to obtain a sodium carboxylic acid solution, adding a metal ion salt solution dropwise, continuously stirring, and forming a thick metal-organic framework sol; mixing the shaped composite phase change temperature control material powder and the metal-organic framework sol, uniformly dispersing, freeze-drying, then carrying out a constant temperature and humidity reaction, and washing, drying to obtain the expanded graphite-based phase change temperature and humidity control material. The expanded graphite-based phase change temperature and humidity control material has the advantages of simple preparation process, mild reaction, controllable temperature and humidity, large phase change enthalpy, good moisture absorption and desorption, high stability, good recyclability and the like, can meet the requirements of human comfort, and is suitable for indoor temperature and humidity control.

Description

Technical Field

[0001] This invention belongs to the technical field of building interior wall temperature and humidity control materials, specifically relating to an expanded graphite-based phase change temperature and humidity control material, its dry adhesive in-situ synthesis method, and its application. Background Technology

[0002] Indoor temperature and humidity directly affect human comfort and health, making their regulation crucial. There are two main types of technologies for regulating indoor temperature and humidity: active regulation using devices such as air conditioners and humidifiers, and passive regulation using temperature- and humidity-controlled materials. Active regulation technologies consume significant amounts of energy, while passive regulation technologies are energy-efficient and therefore green.

[0003] Currently, passive temperature control technology mainly uses phase change materials (PCMs), while passive humidity control technology mainly uses humidity control materials (HCMs). PCMs can be broadly classified into inorganic PCMs and organic PCMs based on their composition. Inorganic PCMs, including hydrated salts, molten salts, and their eutectic salts, have advantages such as high phase change enthalpy (ΔH), flame retardancy, and low price, but they also have problems such as containing water of crystallization, high melting point, and corrosivity, which cannot fully meet practical needs. Organic PCMs have advantages such as high enthalpy, non-corrosiveness, chemical inertness, high stability, and no supercooling or phase separation, making them suitable for indoor temperature control. However, organic PCMs are prone to leakage during the phase change melting process, and usually require shaping treatment in practical applications. Commonly used shaping carriers, such as porous silica and bentonite, have low thermal conductivity and cannot achieve rapid heat transfer during indoor temperature changes (heat transfer). Hygroscopic moisture compounds (HCMs) can be categorized by composition into silica gel, hydrated salts, inorganic minerals, and organic polymers. They offer advantages such as wide availability and low cost, but generally suffer from low hygroscopicity, large pore size, uneven distribution, and poor humidity controllability. Furthermore, powdered HCMs exhibit slow mass transfer (water vapor) rates, necessitating carrier formation and rapid mass transfer. Additionally, both PCMs and HCMs can only control temperature or humidity individually, not simultaneously. Therefore, developing a material capable of simultaneously regulating temperature and humidity (referred to as a phase change temperature and humidity control material) is of paramount importance. The material has the following characteristics: (1) It contains temperature regulating (PCM) and humidity controlling (HCM) components; (2) It has high phase change enthalpy and moisture absorption and desiccation performance within the human comfort range (26℃, 30%~60%RH); (3) It can shape PCM and carry HCM; (4) The carrier has pores (to shape PCM) and high thermal conductivity; (5) The carrier has good compatibility with PCM and HCM; (6) The thermophysical properties of PCM and the hygroscopic properties of HCM have little mutual influence.

[0004] Existing literature reports the formation of PCHCMs by combining PCMs with organic carboxylic acid eutectic PCMs using montmorillonite, fumed SiO2, expanded perlite, etc. as shaping carriers and desiccant. The above PCHCMs can be used to regulate temperature using PCMs; however, the moisture absorption and desiccant properties of all these carriers as HCMs are too weak, and regardless of whether it is a natural porous carrier or synthetic fumed SiO2, the pore size is different and the distribution is wide, so PCMs cannot selectively enter the pores, making it difficult to quantify the temperature and humidity control (Shang Jianli, Tian Ye, Zong Zhifang. Experimental study on modified montmorillonite-shaped composite materials and their thermal and humidity properties. [J]. Bulletin of the Chinese Ceramic Society, 2016, 35: 4184-4190; Shang Jianli, Zhang Hao. Preparation and characterization of decanoic acid-palmitic acid / SiO2 phase change moisture storage composite materials. [J]. Journal of Composite Materials, 2016, 33: 341-349). Summary of the Invention

[0005] To address the problems of weak moisture absorption and difficulty in quantifying temperature and humidity control in existing temperature and humidity control materials, the present invention aims to provide an expanded graphite-based phase change temperature and humidity control material, its dry adhesive in-situ synthesis method, and its application.

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

[0007] This invention provides a method for in-situ synthesis of dry adhesives for expanded graphite-based phase change temperature and humidity control materials, comprising the following steps:

[0008] (1) Preparation of shaped composite phase change temperature regulating material: Under stirring, the organic phase change material is heated to a molten state, and the pre-prepared hydrophilic modified expanded graphite powder is slowly added. After mixing evenly, it is transferred to a cold box to cool and crystallize, and the shaped composite phase change temperature regulating material powder is obtained.

[0009] (2) Preparation of metal-organic framework sol: Take organic carboxylic acid ligand, sodium hydroxide and water to obtain organic carboxylic acid sodium solution; slowly add the pre-prepared metal ion salt solution to organic carboxylic acid sodium solution and stir continuously. The metal ions will hydrolyze and coordinate with organic carboxylic acid ions to form a thick metal-organic framework sol.

[0010] (3) In-situ synthesis of expanded graphite-based phase change temperature and humidity control material by dry gel method: Under stirring, the shaped composite phase change temperature control material powder obtained in step (1) is mixed with the metal-organic framework sol obtained in step (2). After uniform dispersion, it is transferred to a freeze dryer for freeze drying, and the sol particles are transformed into dry gel particles that are deposited on the surface of expanded graphite. The shaped composite phase change temperature control material containing dry gel particles is transferred to a constant temperature and humidity chamber for reaction. After washing the crude product, it is dried at low temperature under vacuum to obtain the expanded graphite-based phase change temperature and humidity control material.

[0011] Preferably, in step (1), the hydrophilic modified expanded graphite is formed by a sol-gel reaction of expanded graphite (EG) and oxide sol; the oxide sol includes any one of zirconium oxide (ZrO2) sol, silica (SiO2) sol, titanium dioxide (TiO2) sol, and alumina (Al2O3) sol; the mass of the oxide in the oxide sol is 5% to 20% of the mass of the hydrophilic modified expanded graphite.

[0012] More preferably, the oxide sol is zirconium oxide. Zirconia sol has excellent hydrophilicity and stability; the mass percentage of oxide sol in hydrophilically modified expanded graphite is 10% to 15%. Too high a mass fraction of sol can easily cause the expanded graphite to agglomerate, while too low a mass fraction can easily cause insufficient hydrophilicity.

[0013] The preferred method for preparing hydrophilic modified expanded graphite is as follows: calcination of expanded graphite removes some oily substances from its surface, and further expansion of the expanded graphite at high temperature yields expanded graphite powder. While stirring, the expanded graphite powder is weighed and added to a crystallizing dish, along with ethanol and stirring. ZrO2 sol is added, and stirring is continued to ensure uniform dispersion of the system. The crystallizing dish is placed in a water bath to allow the solvent to evaporate and a sol-gel reaction to occur, resulting in ZrO2 deposition on the surface of the expanded graphite powder. The solid powder sample is then calcined to obtain ZrO2-modified expanded graphite powder.

[0014] Preferably, the calcination temperature during the expansion of the graphite to remove some oily substances from its surface and the expansion process is 400-500℃.

[0015] Preferably, the temperature of the water bath is 60-80℃.

[0016] Preferably, the temperature of the water bath is 70°C.

[0017] Preferably, the solid powder sample obtained after the sol-gel reaction is calcined at 400-500℃ for 2-4 hours.

[0018] Preferably, the solid powder sample obtained after the sol-gel reaction is calcined at 400℃ for 2-3 hours.

[0019] Preferably, in step (1), the mass percentage of hydrophilic modified expanded graphite in the shaped composite phase change temperature regulating material is 10% to 30%.

[0020] More preferably, in step (1), the mass percentage of hydrophilic modified expanded graphite in the shaped composite phase change temperature regulating material is 15% to 25%. A low content of hydrophilic modified expanded graphite results in poor sizing effect on organic phase change materials; a high content of hydrophilic modified expanded graphite can achieve a good sizing effect, but the phase change enthalpy of the obtained material is small.

[0021] Preferably, the organic phase change material is an alkane wax, fatty acid, or fatty alcohol.

[0022] Preferably, the alkane wax is one of octadecane, RT28, RT25, etc., the fatty acid is decanoic acid, and the fatty alcohol is one of dodecanol, tridecanol, etc.

[0023] Further preferably, considering the phase change enthalpy, melting point (within the range of human thermal comfort 23-28°C), and price of the phase change material itself, and at the same time minimizing the influence of polar hygroscopic agents on the enthalpy of the phase change material (if the phase change material is highly polar, the hygroscopic agent has a significant impact on its enthalpy), the organic phase change material is selected as RT28, which has high hydrophobicity.

[0024] Preferably, in step (2), the metal ion salt solution is a ferrous sulfate solution.

[0025] Preferably, in step (3), the reaction temperature in the constant temperature and humidity chamber is 40-90℃.

[0026] Preferably, in step (3), the relative humidity of the reaction in the constant temperature and humidity chamber is 70%RH-90%RH.

[0027] More preferably, in step (3), the relative humidity of the reaction in the constant temperature and humidity chamber is 90%RH.

[0028] This invention provides an expanded graphite-based phase change temperature and humidity control material synthesized by the aforementioned dry adhesive in-situ synthesis method.

[0029] Furthermore, the expanded graphite-based phase change temperature and humidity control material is composed of the following components (by mass percentage):

[0030] Shaped composite phase change temperature regulating materials: 30%–70%;

[0031] Metal-organic framework moisture control material: 30% to 70%, the metal-organic framework moisture control material is prepared by steps (2) and (3).

[0032] Preferably, the expanded graphite-based phase change temperature and humidity control material is composed of the following components by mass percentage:

[0033] Shaped composite phase change temperature regulating material: 40%–60%;

[0034] Metal-organic framework moisture-controlling materials: 40%–60%.

[0035] Preferably, the shaped composite phase change temperature-regulating material comprises hydrophilic modified expanded graphite and an organic phase change material. Expanded graphite has abundant pore structure and high thermal conductivity, making it suitable as a carrier for the organic phase change material. The capillary action generated by its pores fixes the molten organic phase change material within the channels, thus achieving sizing. Hydrophilic modification of the expanded graphite surface solves the problem that hydrophilic organic-metal framework hygroscopic agents (grains) cannot grow in situ on the hydrophobic expanded graphite surface, improving the compatibility between expanded graphite and the hygroscopic agent.

[0036] Preferably, the metal-organic framework material is selected from one of MIL-100 (Fe), Al-fumaric acid MOF, and CAU-10 (Al). Metal-organic framework materials have a microporous structure and, as desiccant, possess advantages such as high adsorption capacity and low desorption temperature. Furthermore, they exhibit an S-shaped water vapor adsorption isotherm characteristic, making them ideal humidity control materials.

[0037] More preferably, considering factors such as the price of raw materials for the synthetic adsorbent, adsorption capacity, adsorption-desorption curve (with a steep curve in the range of relative humidity 30% to 65%), and reaction conditions, the metal-organic framework material is MIL-100(Fe).

[0038] The present invention also provides the application of the expanded graphite-based phase change temperature and humidity control material in indoor temperature and humidity control.

[0039] The beneficial effects of the present invention are as follows: The expanded graphite-based phase change temperature and humidity control material of the present invention has the advantages of controllable temperature and humidity, large phase change enthalpy, good moisture absorption and desiccation, high thermal conductivity, high stability, and good circulation performance. It can meet the requirements of human comfort and is suitable for indoor temperature and humidity control.

[0040] Specifically, it has the following advantages:

[0041] (1) The phase change temperature of the expanded graphite-based phase change temperature and humidity control material of the present invention is within the range of human thermal comfort; RT28 temperature control, MIL-100(Fe) humidity control, and highly thermally conductive, porous hydrophilic modified expanded graphite are selected as carriers.

[0042] (2) The expanded graphite-based phase change temperature and humidity control material of the present invention has the advantages of precise indoor temperature and humidity control, good moisture absorption and dehumidification performance, and good circulation performance. As a functional building material, it can reduce air conditioning energy consumption and achieve building energy conservation.

[0043] (3) The preparation method of the expanded graphite-based phase change temperature and humidity control material of the present invention is simple (dry adhesive method) and the process conditions are mild (around 60°C).

[0044] (4) Based on the shaped composite phase change temperature regulating material synthesized in step (1), the adsorbent is synthesized in situ. Compared with simple physical mixing, the combination of the shaped phase change material and the adsorbent is stronger and more uniform, and the adsorbent and the hydrophobic phase change material have less mutual influence. Attached Figure Description

[0045] Figure 1 SEM images of expanded graphite, 10% ZrO2 modified expanded graphite, the shaped composite phase change temperature regulating material prepared in Example 1, and the expanded graphite-based phase change temperature regulating and humidity controlling material prepared in Example 1.

[0046] Figure 2 Figure 1 shows the experimental results of the contact angle of expanded graphite and expanded graphite modified with ZrO2 at different mass fractions (5%, 10%, 15%) with water.

[0047] Figure 3 DSC curves of the shaped composite phase change temperature regulating material prepared for RT28, Example 1, and the expanded graphite-based phase change temperature regulating and humidity controlling materials prepared for Examples 1-2.

[0048] Figure 4 The static adsorption curves of water vapor of the expanded graphite-based phase change temperature and humidity control materials prepared in Examples 1-3 and pure MIL-100(Fe) at 25°C and 90% RH are shown.

[0049] Figure 5 The XRD spectra of the expanded graphite-based phase change temperature and humidity control material prepared in Example 1, MIL-100(Fe), and RT28 are shown. Detailed Implementation

[0050] The present invention will be further explained and described below with reference to specific embodiments.

[0051] Material pretreatment:

[0052] Expanded graphite was calcined in a muffle furnace at 400℃ for 5 hours to remove some oily substances from its surface and simultaneously expand to obtain expanded graphite powder.

[0053] Preparation method of hydrophilic modified expanded graphite:

[0054] Under magnetic stirring at room temperature, 9g of expanded graphite powder was weighed and added to a 1500mL crystallizing dish, and 800mL of ethanol was added and stirred for 2h. 50g of ZrO2 sol with a mass percentage concentration of 2% (Examples 1-7) was weighed and added at a rate of 1mL / min, and the system was continuously stirred to disperse it evenly. The crystallizing dish was placed in an 80℃ water bath for 24h to allow the solvent to evaporate and a sol-gel reaction to occur, and the generated ZrO2 was deposited on the surface of the expanded graphite powder. The solid powder sample was calcined at 400℃ for 2h to obtain ZrO2 modified expanded graphite powder (the mass of ZrO2 is 10% of the mass of ZrO2 modified expanded graphite, denoted as 10% ZrO2 modified expanded graphite).

[0055] To prepare ZrO2 modified expanded graphite powder (denoted as 15% ZrO2 modified expanded graphite) with a ZrO2 mass of 15% of the mass of ZrO2 modified expanded graphite, the steps are the same as those for preparing 10% ZrO2 modified expanded graphite, except that the above 50g of ZrO2 sol with a mass percentage concentration of 2% is replaced with 79g of ZrO2 sol with a mass percentage concentration of 2%.

[0056] Examples 1-7 below use 10% ZrO2 modified expanded graphite (50g of ZrO2 sol with a mass percentage concentration of 2%), while Example 8 uses 15% ZrO2 modified expanded graphite (79g of ZrO2 sol with a mass percentage concentration of 2%).

[0057] Example 1:

[0058] (1) 3.2g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 0.8g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The mixture was then transferred to a -20℃ freezer to crystallize the phase change paraffin RT28 and mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of 10% ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 20%).

[0059] (2) In a 100mL beaker, dissolve 2.386g of ferrous sulfate tetrahydrate in 20mL of deionized water to form a ferrous sulfate solution; in another 100mL beaker, dissolve 1.680g of trimellitic acid (H3BTC) and 0.960g of sodium hydroxide in 40mL of deionized water to form a sodium trimellitate solution; add the ferrous sulfate solution to the sodium trimellitate solution at a rate of 1mL / min and stir continuously for 1h. The ferrous ions will undergo oxidation and hydrolysis to obtain Fe. 3+ -BTC thick colloid.

[0060] (3) Add 4.0g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.026g of Fe 3+ -In a BTC thick colloidal suspension, stir for 30 min to obtain a mixture. Freeze-dry the mixture for 12 h to allow Fe to precipitate. 3+ -BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH (relative humidity) and 70℃ for 3 hours, washed three times with deionized water, filtered, and the filter material is dried in a vacuum drying oven at 60℃ for 24 hours to obtain the expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 6.834g, and the shaped composite phase change temperature-regulating material accounts for 58.6% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0061] Example 2:

[0062] (1) 2.24g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 0.56g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The system was then transferred to a -20℃ freezer to crystallize the phase change paraffin RT28 and mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 20%).

[0063] (2)Fe 3+ The preparation method of the BTC thick colloid is the same as step (2) of Example 1.

[0064] (3) Add 2.8g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.026g of Fe 3+ -In a thick BTC colloid, stir for 30 minutes. Freeze-dry the mixture for 12 hours to allow Fe to precipitate. 3+ -BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH and 70℃ for 3 hours to obtain expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 5.653g, and the shaped composite phase change temperature-regulating material accounts for 49.5% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0065] Example 3:

[0066] (1) 1.6g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 0.4g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The system was then transferred to a -20℃ freezer to crystallize the phase change paraffin RT28 and mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 20%).

[0067] (2)Fe 3+ The preparation method of the BTC thick colloid is the same as step (2) of Example 1.

[0068] (3) Add 2g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.026g of Fe 3+ - In a BTC thick colloid, stir for 30 minutes to obtain a mixture. Freeze-dry the mixture for 12 hours to allow Fe to precipitate. 3+ -BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH and 70℃ for 3 hours, washed three times with deionized water, filtered, and the filter material is dried in a vacuum drying oven at 60℃ for 24 hours to obtain the expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 4.812g, and the shaped composite phase change temperature-regulating material accounts for 41.6% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0069] Example 4:

[0070] (1) 3.4g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 0.6g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The system was then transferred to a -20℃ freezer to crystallize the phase change paraffin RT28 and mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 15%).

[0071] (2)Fe 3+ The preparation method of the BTC thick colloid is the same as step (2) of Example 1.

[0072] (3) Add 4.0g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.026g of Fe 3+ - In a BTC thick colloid, stir for 30 minutes to obtain a mixture. Freeze-dry the mixture for 12 hours to allow Fe to precipitate. 3+-BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH and 70℃ for 3 hours, washed three times with deionized water, filtered, and the filter material is dried in a vacuum drying oven at 60℃ for 24 hours to obtain the expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 6.811g, and the shaped composite phase change temperature-regulating material accounts for 58.7% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0073] Example 5:

[0074] (1) 3.0g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 1.0g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The system was then transferred to a -20℃ freezer to crystallize the phase change paraffin RT28 and mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 25%).

[0075] (2)Fe 3+ The preparation method of the BTC thick colloid is the same as step (2) of Example 1.

[0076] (3) Add 4.0g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.026g of Fe 3+ - In a BTC thick colloid, stir for 30 minutes to obtain a mixture. Freeze-dry the mixture for 12 hours to allow Fe to precipitate. 3+ -BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH and 70℃ for 3 hours, washed three times with deionized water, filtered, and the filter material is dried in a vacuum drying oven at 60℃ for 24 hours to obtain expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 6.775g, and the shaped composite phase change temperature-regulating material accounts for 59% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0077] Example 6:

[0078] (1) 3.2g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 0.8g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The system was then transferred to a -20℃ freezer to crystallize the phase change paraffin RT28 and mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 20%).

[0079] (2)Fe 3+ The preparation method of the BTC thick colloid is the same as step (2) of Example 1.

[0080] (3) Add 4.0g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.032g of Fe 3+ - In a BTC thick colloid, stir for 30 minutes to obtain a mixture. Freeze-dry the mixture for 12 hours to allow Fe to precipitate. 3+ -BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH and 50℃ for 3 hours, washed three times with deionized water, filtered, and the filter material is dried in a vacuum drying oven at 60℃ for 24 hours to obtain the expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 6.582g, and the shaped composite phase change temperature-regulating material accounts for 60.7% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0081] Example 7:

[0082] (1) 3.2g of phase change paraffin RT28 was added to a 100mL beaker and placed in a 60℃ constant temperature water bath and stirred for 30min to completely melt the phase change paraffin RT28; then 0.8g of 10% ZrO2 modified expanded graphite powder was added and stirred for 2h to disperse the system evenly. The mixture was naturally cooled to room temperature and transferred to a -20℃ freezer to crystallize the phase change paraffin RT28. The mixture was then mechanically crushed to obtain a shaped composite phase change temperature regulating material powder (the mass percentage of ZrO2 modified expanded graphite in the shaped composite phase change temperature regulating material is 20%).

[0083] (2)Fe 3+ The preparation method of the BTC thick colloid is the same as step (2) of Example 1.

[0084] (3) Add 4.0g of the shaped composite phase change temperature-regulating material obtained in step (1) to 65.032g of Fe 3+ - In a BTC thick colloid, stir for 30 minutes to obtain a mixture. Freeze-dry the mixture for 12 hours to allow Fe to precipitate. 3+-BTC sol is converted into dry gel particles and deposited on the surface of ZrO2 modified expanded graphite-based shaped composite phase change temperature-regulating material; it is then transferred to a constant temperature and humidity chamber at 90% RH and 90℃ for 3 hours, washed three times with deionized water, filtered, and the filter material is dried in a vacuum drying oven at 60℃ for 24 hours to obtain the expanded graphite-based phase change temperature-regulating and humidity-regulating material. The mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material is 7.134g, and the shaped composite phase change temperature-regulating material accounts for 56% of the mass of the expanded graphite-based phase change temperature-regulating and humidity-regulating material.

[0085] Example 8:

[0086] Except for replacing the 10% ZrO2 modified expanded graphite in step (1) of Example 1 with 15% ZrO2 modified expanded graphite, the rest is the same as in Example 1. The mass of the expanded graphite-based phase change temperature and humidity control material is 6.727 g, and the shaped composite phase change temperature control material accounts for 63.8% of the total mass of the expanded graphite-based phase change temperature and humidity control material.

[0087] Figure 1 SEM images (magnification 10K) of expanded graphite, 10% ZrO2-modified expanded graphite, the 10% ZrO2-modified expanded graphite shaped composite phase change material prepared in Example 1, and the expanded graphite-based phase change temperature and humidity control material prepared in Example 1. Figure 1 It can be seen that: expanded graphite ( Figure 1 (a) shows a loosely stacked layered structure with numerous pores; after ZrO2 modification, a ZrO2 coating can be seen uniformly covering the surface of the expanded graphite. The expanded graphite modified with 10% ZrO2 ( Figure 1 (b) still retains the original loosely stacked layered structure, and the original pore structure is basically preserved. The shaped composite phase change temperature-regulating material prepared in Example 1 ( Figure 1 As can be seen in (c) of the figure, due to capillary action, RT28 is embedded in the modified expanded graphite layered structure, making it less prone to leakage (shaping) during melting; for the expanded graphite-based phase change temperature and humidity control material prepared in Example 1 ( Figure 1 In (d), it can be observed that a large number of MIL-100(Fe) octahedral crystals are stacked on the surface of the shaped composite phase change temperature-regulating material, proving the feasibility of in-situ loading of MIL-100(Fe) on the surface of hydrophilic modified expanded graphite using the dry adhesive method.

[0088] Figure 2 The figures show the experimental results of hydrophilic contact angles for expanded graphite and expanded graphite modified with different ZrO2 contents (5%, 10%, 15%). Figure 2It can be seen that the contact angle of unmodified expanded graphite with water is 83.05°, indicating that its hydrophilicity is low (high hydrophobicity), which is not conducive to the in-situ growth of the hydrophilic adsorbent MIL-100(Fe) on its surface. ZrO2 sol particles can form a thin and uniform ZrO2 hydrophilic coating on the surface of expanded graphite, increasing the hydrophilicity of expanded graphite. Among them, the contact angles of 5% ZrO2 modified expanded graphite (5% ZrO2-EG), 10% ZrO2 modified expanded graphite (10% ZrO2-EG), and 15% ZrO2 modified expanded graphite (15% ZrO2-EG) with water are 55.30°, 37.95°, and 47.10°, respectively. It is obvious that the addition of ZrO2 coating on the surface of expanded graphite can improve its hydrophilicity, with 10% ZrO2-EG being the best.

[0089] Figure 3 The DSC curves are for the expanded graphite-based phase change temperature and humidity control materials prepared in Examples 1-2, RT28, and the shaped composite phase change temperature control material prepared in Example 1. Figure 3 It is known that RT28 has a high phase change enthalpy (218.02 J / g) and a suitable phase change temperature (28.79℃), making it suitable as a phase change temperature regulating material. The addition of 20% hydrophilic modified expanded graphite (i.e., the mass percentage of hydrophilic modified expanded graphite in the shaped composite phase change temperature regulating material is 20%) slightly lowers the melting point of RT28 (26.78℃), bringing it closer to the human body's comfortable temperature, while still maintaining a high phase change enthalpy (171.94 J / g). When combined with MIL100-(Fe) humidity control agent, the phase change enthalpies in Examples 1 and 2 are 71.93 J / g and 53.32 J / g, respectively, and the phase change temperatures are 26.70℃ and 26.26℃, respectively. This indicates that the addition of the humidity control agent does not affect the temperature regulating performance of the phase change temperature regulating and humidity controlling material (the phase change temperature change is very small, and the enthalpy value is high). The decrease in enthalpy values ​​in Examples 1 and 2 is due to the reduction in the proportion of shaped composite phase change temperature regulating material in the phase change temperature regulating and humidity controlling material.

[0090] Figure 4 The images show the static water vapor adsorption curves of the expanded graphite-based phase change temperature and humidity control materials prepared in Examples 1-3 and pure MIL-100(Fe) at 25°C and 90% RH. Figure 4It is known that MIL-100(Fe) as a humidity regulator (HCM) has high water absorption capacity, with a saturated adsorption capacity as high as 0.780 g / g. After loading it onto modified expanded graphite shaped phase change material, the resulting expanded graphite-based phase change temperature and humidity control material still exhibits strong water absorption capacity. The saturated adsorption capacities of Examples 1, 2, and 3 are 0.297 g / g, 0.343 g / g, and 0.423 g / g, respectively. The increase in moisture absorption is due to the increased proportion of MIL-100(Fe) in the phase change temperature and humidity control material. Its moisture absorption performance is far superior to conventional moisture-absorbing materials, making it suitable as an indoor humidity control material.

[0091] Figure 5 The XRD patterns of the expanded graphite-based phase change temperature and humidity control material, MIL-100(Fe), and RT28 prepared in Example 1 are shown. The characteristic diffraction peaks of the expanded graphite-based phase change temperature and humidity control material can all be found in the spectra of the shaped composite phase change temperature control material and the MIL-100(Fe) humidity control agent, only with variations in peak intensity. No new diffraction peaks appear, indicating that the preparation of the composite temperature and humidity control material involves physical mixing without any chemical reaction.

[0092] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for in-situ dry gel synthesis of expanded graphite-based phase change temperature and humidity control materials, characterized in that, Includes the following steps: (1) Preparation of shaped composite phase change temperature regulating material: Under stirring, the organic phase change material is heated to a molten state, hydrophilic modified expanded graphite powder is added, and after mixing evenly, it is cooled and crystallized to obtain shaped composite phase change temperature regulating material powder. (2) Preparation of metal-organic framework sol: Take organic carboxylic acid ligand, sodium hydroxide and water to obtain organic carboxylic acid sodium solution; add metal ion salt solution dropwise to organic carboxylic acid sodium solution and stir continuously to form a thick metal-organic framework sol; (3) In-situ synthesis of expanded graphite-based phase change temperature and humidity control material by dry gel method: Under stirring, the shaped composite phase change temperature control material powder obtained in step (1) is mixed with the metal-organic framework sol obtained in step (2). After uniform dispersion, it is freeze-dried and then subjected to constant temperature and humidity reaction to obtain crude product. After washing, it is dried to obtain expanded graphite-based phase change temperature and humidity control material.

2. The method for in-situ dry gel synthesis of expanded graphite-based phase change temperature and humidity control material according to claim 1, characterized in that, In step (1), the hydrophilic modified expanded graphite is formed by the sol-gel reaction of expanded graphite and oxide sol. The oxide sol includes any one of zirconium oxide sol, silica sol, titanium dioxide sol, and alumina sol. The mass of the oxide in the oxide sol is 5% to 20% of the mass of the hydrophilic modified expanded graphite.

3. The method for in-situ dry gel synthesis of expanded graphite-based phase change temperature and humidity control material according to claim 1, characterized in that, In step (1), the mass percentage of hydrophilic modified expanded graphite in the shaped composite phase change temperature regulating material is 10% to 30%.

4. The method for in-situ dry gel synthesis of an expanded graphite-based phase change temperature and humidity control material according to claim 1, characterized in that, In step (1), the organic phase change material is an alkane wax, fatty acid, or fatty alcohol.

5. The method for in-situ dry gel synthesis of an expanded graphite-based phase change temperature and humidity control material according to claim 1, characterized in that, In step (2), the metal ion salt solution is a ferrous sulfate solution.

6. The method for in-situ dry gel synthesis of an expanded graphite-based phase change temperature and humidity control material according to claim 1, characterized in that, In step (3), the constant temperature is 40-90℃.

7. The method for in-situ dry gel synthesis of an expanded graphite-based phase change temperature and humidity control material according to claim 1, characterized in that, In step (3), the constant humidity is 70%RH-90%RH.

8. Expanded graphite-based phase change temperature and humidity control material synthesized by the dry glue in-situ synthesis method according to any one of claims 1-7.

9. The expanded graphite-based phase change temperature and humidity control material according to claim 8, characterized in that, The expanded graphite-based phase change temperature and humidity control material is composed of the following components by mass fraction: Shaped composite phase change temperature regulating materials: 30%–70%; Metal-organic framework sol: 30%–70%.

10. The application of the expanded graphite-based phase change temperature and humidity control material according to claim 8 in indoor temperature and humidity control.

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