A phase change material, a preparation method thereof and an application thereof

Abstract

The present invention relates to the technical field of coatings, and discloses a phase change material, a preparation method thereof and an application. The method includes adding polyethylene glycol into dehydrated toluene, sequentially adding γ-isocyanatopropyltriethoxysilane and dibutyltin dilaurate after dissolution, volatilizing the solvent after reaction to obtain RPEG, adding preheated hydrochloric acid at 60-62 °C, and obtaining a reactive polyethylene glycol prepolymer solution after the reaction; drying the obtained reactive polyethylene glycol prepolymer solution to obtain a phase change material film. The method for preparing the phase change material provided by the present invention, after volatilizing the solvent to obtain RPEG, without drying, directly adding preheated hydrochloric acid at 60-62 °C, and continuing the reaction under the condition of keeping the solution temperature constant. After film formation, the flexibility is very good, and it has phase change morphology stability, and is used for preparing phase change coatings.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and specifically to a phase change material, a preparation method thereof, and an application thereof. Background Art

[0002] Phase change materials (PCMs) are well-known for their energy storage and thermal regulation functions. They can absorb and release a large amount of latent heat at a constant transition temperature and have been widely used in thermal management. They utilize their high latent heat capacity to store energy and synergistically cool the target environment during the phase change process from solid to liquid. They have been widely used in thermal management. Solid-liquid and solid-solid are the two basic phase change states that have been studied the most in the literature. However, for PCMs based on solid-liquid phase change, preventing the leakage and deformation of the material is the primary requirement in practical applications because some components, such as paraffin wax, fatty acids, and poly(ethylene glycol) (PEG), will melt into liquids above the intersection temperature. Although many studies have been dedicated to improving their stability through physical packaging, the inherent properties of liquids remain unchanged at high temperatures. In contrast, PCMs based on solid-solid phase change rarely leak or deform due to chemical cross-linking. PCMs can operate within a narrow temperature range within an adjustable temperature range and have great potential for regulating the imbalance between heat supply and demand. However, most phase change materials are in the form of powders, flakes, or rigid blocks, making it difficult to adhere to heat sources or target substrates.

[0003] The prior art reacts PEG with γ-isocyanatopropyltriethoxysilane (IPTS), rotary evaporates the product, dries it at 60 °C for 3 h, and then hydrolyzes it in weak acid to obtain reactive polyethylene glycol (RPEG) with highly active silanol groups. By simply pouring the prepolymer into a PS plastic mold, a cross-linked phase change material (RPCMs) coating is prepared. The RPCMs coating can adhere to various substrates, including cotton fabrics, wood, tinplate, and even irregular objects. The coating exhibits obvious solid-solid phase change properties and a high energy storage density. However, this preparation method involves steps of rotary evaporation, drying, and then weak acid hydrolysis after the reaction to obtain reactive polyethylene glycol, and the PCMs film prepared therefrom has poor flexibility. Summary of the Invention

[0004] The present invention discloses a phase change material, a preparation method thereof, and an application thereof, and solves the problem that when preparing a phase change material in the prior art, by reacting PEG with IPTS, rotary evaporating the product, drying it, and then hydrolyzing it in weak acid to obtain reactive polyethylene glycol, the PCMs film prepared therefrom has poor flexibility.

[0005] A phase change material, in which the raw materials in the phase change material react according to the following weight ratio:

[0006]

[0007] The preparation method of the phase change material is as follows:

[0008] (a) Add polyethylene glycol to dehydrated toluene. After dissolution, add γ-isocyanatopropyltriethoxysilane and dibutyltin dilaurate in sequence. After reaction, volatilize the solvent to obtain RPEG. Add preheated hydrochloric acid at 60-62°C, and after the reaction, obtain a reactive polyethylene glycol prepolymer solution.

[0009] (b) After drying the reactive polyethylene glycol prepolymer solution obtained in step (a), obtain a phase change material thin film.

[0010] Preferably, in step (a), the polyethylene glycol is dried in a vacuum drying oven at 60-80°C for 12-14 hrs, and the toluene is dehydrated with 4A molecular sieve for 72-96 hrs.

[0011] Preferably, in step (a), when dissolving polyethylene glycol, the temperature is raised to 65-70°C, and after complete dissolution, it is cooled to 40-42°C.

[0012] Preferably, the concentration of the hydrochloric acid in step (a) is 0.1 mol / L.

[0013] Preferably, the hydrochloric acid in step (a) is preheated to 60-65°C.

[0014] Preferably, the reaction conditions after dropping hydrochloric acid in step (a) are reaction at 60-62°C for 3-4 hrs.

[0015] Preferably, the drying conditions in step (b) are 50-55°C for 10-12 hrs.

[0016] Preferably, the phase change material prepared by the preparation method.

[0017] Preferably, the phase change material has phase change morphology stability.

[0018] The second object of the present invention is that the phase change material is used for preparing a phase change coating.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. For the method for preparing a phase change material provided by the present invention, after volatilizing the solvent to obtain RPEG, without drying, directly add preheated hydrochloric acid at 60-62°C, and continue the reaction under the condition of keeping the solution temperature constant. After film formation, the flexibility is very good, and it has phase change morphology stability and is used for preparing a phase change coating; the present invention also changes the dosage of IPTS. By simultaneously changing the preparation method and the dosage of IPTS, the film formation effect is greatly improved.

[0021] 2. When hydrochloric acid was initially added, the solution was milky white, and it gradually became translucent as the stirring time increased. After the reaction was completed, the prepolymer solution was dried to form a transparent phase change material film, while the prior art formed a translucent film. Description of the Drawings

[0022] Figure 1 Thermal stability diagrams of the PCMs provided in Example 1 of the present invention at 30 °C (a), 60 °C (b), and 70 °C (c);

[0023] Figure 2 Thermal stability diagrams of PEG at 30 °C (a), 60 °C (b), and 70 °C (c);

[0024] Figure 3 DSC curves of different examples and comparative examples provided by the present invention;

[0025] Figure 4 Flexibility diagram of the phase change material prepared in Example 1 of the present invention. Detailed Description of the Invention

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] In the embodiments of the present invention, the experimental methods are all conventional methods unless otherwise specified. The materials, reagents, etc. used are all commercially available unless otherwise specified.

[0028] Example 1

[0029] A method for preparing a phase change material, comprising the following steps:

[0030] (a) PEG was dried in a vacuum drying oven at 60 °C for 12 hrs, and toluene was dehydrated with 4A molecular sieve for 72 h; 10 parts by weight of PEG was poured into a three-necked flask containing 100 parts by weight of toluene, and the temperature was raised to 65 °C; after complete dissolution, it was cooled to 40 °C, 0.66 parts by weight of γ-isocyanatopropyltriethoxysilane (IPTS) and 0.25 parts by weight of dibutyltin dilaurate (DBT) were added in sequence, then magnetically stirred for 6 hrs, and finally toluene was removed by vacuum rotary evaporation to obtain RPEG;

[0031] (b) 150 parts by weight of hydrochloric acid (0.1 mol / L) preheated to 60 °C was added dropwise to the RPEG under stirring and at the rotary evaporation temperature, and stirred at 60 °C for 3 hrs to obtain an RPEG prepolymer solution;

[0032] (c) Pour the RPEG prepolymer solution into a polystyrene-based petri dish with a diameter of 53 mm and place it in an oven at 50 °C. After drying for 10 hrs, peel it off from the plastic substrate to obtain the PCMs film.

[0033] Example 2

[0034] A method for preparing a phase change material, comprising the following steps:

[0035] (a) PEG is dried in a vacuum drying oven at 70 °C for 13 hrs, and toluene is dehydrated with 4A molecular sieve for 84 h; 10 parts by weight of PEG is poured into a three-necked flask containing 100 parts by weight of toluene, and the temperature is raised to 68 °C; after complete dissolution, it is cooled to 41 °C, 0.79 part by weight of IPTS and 0.05 part by weight of DBT are added in sequence, then magnetically stirred for 6 hrs, and finally toluene is removed by vacuum rotary evaporation to obtain RPEG;

[0036] (b) 50 parts by weight of hydrochloric acid (0.1 mol / L) preheated to 60 °C is added dropwise to the stirring RPEG at the rotary evaporation temperature, and stirred at 61 °C for 3 hrs to obtain the RPEG prepolymer solution;

[0037] (c) Pour the RPEG prepolymer solution into a polystyrene-based petri dish with a diameter of 53 mm and place it in an oven at 53 °C. After drying for 12 hrs, peel it off from the plastic substrate to obtain the PCMs film.

[0038] Example 3

[0039] A method for preparing a phase change material, comprising the following steps:

[0040] (a) PEG is dried in a vacuum drying oven at 80 °C for 14 hrs, and toluene is dehydrated with 4A molecular sieve for 96 h; 10 parts by weight of PEG is poured into a three-necked flask containing 100 parts by weight of toluene, and the temperature is raised to 70 °C; after complete dissolution, it is cooled to 42 °C, 0.52 part by weight of IPTS and 0.15 part by weight of DBT are added in sequence, then magnetically stirred for 6 hrs, and finally toluene is removed by vacuum rotary evaporation to obtain RPEG;

[0041] (b) 100 parts by weight of hydrochloric acid (0.1 mol / L) preheated to 65 °C is added dropwise to the stirring RPEG, and stirred at 62 °C for 4 hrs to obtain the RPEG prepolymer solution;

[0042] (c) Pour the RPEG prepolymer solution into a polystyrene-based petri dish with a diameter of 53 mm and place it in an oven at 55 °C. After drying for 12 hrs, peel it off from the plastic substrate to obtain the PCMs film.

[0043] Comparative Example 1

[0044] A preparation method of a phase change material, comprising the following steps:

[0045] (a) PEG is dried in a vacuum drying oven at 80 °C for 14 hrs, and toluene is dehydrated with 4A molecular sieve for 96 hrs; 10 parts by weight of PEG is poured into a three-necked flask containing 100 parts by weight of toluene, and the temperature is raised to 70 °C; after complete dissolution, it is cooled to 40 °C, 0.52 parts by weight of IPTS and 0.15 parts by weight of DBT are added in sequence, then magnetically stirred for 6 hrs, and finally toluene is removed by vacuum rotary evaporation and baked at 60 °C for 3 hrs to obtain RPEG;

[0046] (b) 100 parts by weight of hydrochloric acid (0.1 mol / L) is added dropwise to the stirred RPEG, and stirred at 60 °C for 3 hrs to obtain an RPEG prepolymer solution;

[0047] (c) The RPEG prepolymer solution is poured into a polystyrene-based petri dish with a diameter of 53 mm and placed in an oven at 50 °C. After drying for 12 hrs, it is peeled off from the plastic substrate to obtain a PCMs film.

[0048] Figure 1 It shows the phase change material prepared in Example 1 placed on a heating platform and observes its morphological changes, and studies the phase change stability of the PCMs film. Figure 2 In it, PEG is solid at 30 °C and gradually melts into a solid-liquid intermediate state at 60 °C. On the contrary, due to the dehydration condensation of silanol groups and the formation of crosslinked silicon, the PCMs film ( Figure 1 ) has no obvious change at this temperature. When the temperature is further raised to 70 °C, PEG is completely transformed into a liquid state, while the PCMs film maintains its original shape, showing an obvious solid-solid phase change behavior. There are two hydroxyl groups at both ends of the original PEG molecular chain, and covalent bonds cannot be formed between molecules. Therefore, when the temperature is higher than the melting point, the mobility of each single chain greatly increases, and macroscopically it becomes a liquid state, that is, it shows a solid-liquid phase change behavior. For the PCMs film, the formation of the Si-O-Si network prevents the free movement of the PEG chain, making the composite film have good phase change stability, and the formation of a good crosslinked network makes the PCMs film ( Figure 4 ) have a certain flexibility.

[0049] Table 1 Mechanical properties of the prepared PCMs film

[0050] Example 1 Example 2 Example 3 Comparative Example 1 Elongation at break (%) 556.52 532.78 451.38 409.69 Tensile strength (MPa) 12.53 14.59 11.58 10.81

[0051] As can be seen from Table 1, the elongation at break and tensile strength of Examples 1 to 3 are superior to those of Comparative Example 1. Moreover, when the addition amount of IPTS increases, the tensile strength increases significantly, and the elongation at break increases remarkably.

[0052] Table 2 Different enthalpy values and phase change temperatures of the prepared PCMs films

[0053]

[0054] The phase change enthalpy and phase change temperature of the PCMs films were analyzed by differential scanning calorimetry (DSC). From Figure 3 and Table 2, it can be seen that compared with the PCMs film of Comparative Example 1, the PCMs films in Examples 1 to 3 show partial latent heat loss. This is due to the limitation of PEG chain crystallization caused by the cross-linked structure. Compared with Comparative Example 1, the phase change enthalpy is further reduced because the magnitude of the phase change enthalpy depends on the free movement of PEG molecules.

[0055] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0056] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for preparing a phase change material, characterized in that, The raw materials in the phase change material react according to the following weight ratio: Polyethylene glycol: 10 parts Toluene: 100 parts γ-Isocyanatopropyltriethoxysilane: 0.52 - 0.79 parts Dibutyltin dilaurate: 0.05 - 0.25 parts Hydrochloric acid: 50 - 150 parts; The preparation method of the phase change material is as follows: (a)Add polyethylene glycol into dehydrated toluene. After dissolution, add γ-isocyanatopropyltriethoxysilane and dibutyltin dilaurate in sequence. After reaction, evaporate the solvent to obtain RPEG. Add preheated hydrochloric acid at 60 - 62 °C, and after the reaction, obtain a reactive polyethylene glycol prepolymer solution; (b)Dry the reactive polyethylene glycol prepolymer solution obtained in step (a) to obtain a phase change material film; The hydrochloric acid described in step (a) is hydrochloric acid preheated to 60 - 65 °C, and the reaction condition after dropping hydrochloric acid is to react at 60 - 62 °C for 3 - 4 hrs.

2. The method for preparing a phase change material according to claim 1, characterized in that, The polyethylene glycol described in step (a) is dried in a vacuum drying oven at 60 - 80 °C for 12 - 14 hrs, and the toluene is dehydrated with 4A molecular sieve for 72 - 96 hrs.

3. The method for preparing a phase change material according to claim 2, characterized in that, When dissolving polyethylene glycol in step (a), heat up to 65 - 70 °C, and after complete dissolution, cool to 40 - 42 °C for standby.

4. The method for preparing a phase change material according to claim 3, characterized in that, The concentration of the hydrochloric acid described in step (a) is 0.1 mol / L.

5. The method for preparing a phase change material according to claim 1, characterized in that, The drying condition in step (b) is 50 - 55 °C for 10 - 12 hrs.

6. A phase change material prepared by the preparation method according to any one of claims 1 to 5.

7. The phase change material prepared by the preparation method according to claim 6, characterized in that, The phase change material has phase change morphological stability.

8. The application of the phase change material according to claim 7, characterized in that, The phase change material is used for preparing phase change coatings.

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