Waterborne polyurethane solid-solid phase change emulsion and preparation method thereof
A solvent-free method was used to prepare waterborne polyurethane solid-solid phase change emulsions, which solved the problems of easy leakage and poor cycle stability of phase change materials. This resulted in a high enthalpy value and stable phase change material that is suitable for various environmental conditions and large-scale production.
Patent Information
- Application Number
- CN202511333620.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2025-12-12
AI Technical Summary
Existing phase change materials are prone to leakage during heat storage and have poor cycle stability. Traditional modification methods require a large amount of high molecular weight polymers, which limits the heat storage capacity and secondary processing capabilities, and the application range of the prepared materials is also limited.
A solvent-free method was used to prepare waterborne polyurethane solid-solid phase change emulsions. Through the reaction of polyethylene glycol and hexamethylene diisocyanate, a linear polymer was formed and dispersed in water to form nano-sized particles. This method avoids the use of organic solvents and is suitable for various environmental conditions.
It has achieved a high enthalpy value and stable phase change material, which is suitable for various environmental conditions, large-scale production, and has good thermal management performance and environmental protection characteristics.
Smart Images
Figure CN121108440A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of phase change thermal management technology, specifically relating to an aqueous polyurethane solid-solid phase change emulsion and its preparation method. Background Technology
[0002] Phase change materials (PCMs) are widely used in drug delivery, human body temperature management, heating, and energy storage due to their excellent heat storage and temperature regulation capabilities. However, since current PCMs are mainly organic solid-liquid PCMs, such as paraffin and polyethylene glycol, their leakage during the phase change process and poor cycle stability further hinder their widespread application.
[0003] In recent years, solid-solid phase change materials (SCTs) have gradually attracted the attention of researchers due to their stable properties, wide applications, and environmental friendliness. Currently, modifying the organic solid-liquid phase change material polyethylene glycol (PEG) to transform it into a solid-solid SCT is of great significance in overcoming its tendency to leak during heat storage and ensuring the cycle stability of the SCT. Traditional PEG modification methods utilize the chain segment entanglement and solidification of macromolecular polymers to confine PEG molecules within a polymer network to form a solid-solid SCT. Although these preparation methods are widely used in the field of phase change heat management, they require large amounts of high molecular weight polymer additives, limiting the heat storage capacity and secondary processing capabilities of solid-solid SCTs. Secondly, some materials utilize the reaction of small isocyanate monomers with the terminal hydroxyl groups of PEG to prepare intrinsic solid-solid SCTs, which exhibit good enthalpy retention. However, such polymerization generally requires an organic solvent system, and the prepared materials are solid films or powders, limiting their application range.
[0004] Therefore, there is currently a lack of a simple, environmentally friendly, high-enthalpy solid-solid phase change material that is suitable for various environmental conditions. Summary of the Invention
[0005] To address the problems existing in the prior art, this invention provides an aqueous polyurethane solid-solid phase change emulsion and its preparation method, thereby solving the current lack of simple, environmentally friendly, high-enthalpy solid-solid phase change materials suitable for various environmental conditions. By reacting polyethylene glycol and hexamethylene diisocyanate in a solvent-free manner and then using a water precipitation method, the polyurethane-based solid-solid phase change material is dispersed and emulsified in water, exhibiting good enthalpy and stability. As a solid-solid phase change thermal management material, it is solvent-free, operates under mild conditions, is highly operable, and has high production efficiency, making it suitable for large-scale production and application.
[0006] This invention is achieved through the following technical solution: A method for preparing an aqueous polyurethane solid-solid phase change emulsion includes the following steps: S1, anhydrous polyethylene glycol and hexamethylene diisocyanate were added in an oxygen-free environment at a molar ratio of 1:(1~2) to obtain a reaction solution containing a linear polymer. S2, under conditions of 60-80℃, firstly, the reaction solution described in S1 is further reacted with dibutyltin dilaurate, wherein the dibutyltin dilaurate is 0.1%-0.3% of the molar amount of hexamethylene diisocyanate, to obtain a polyurethane-based solid-solid phase change material. Then, the polyurethane-based solid-solid phase change material is dispersed in deionized water, wherein the mass of deionized water is greater than or equal to 70% of the mass of polyethylene glycol, to obtain an aqueous polyurethane solid-solid phase change emulsion.
[0007] A further improvement of the present invention is that: In S1, the molecular weight of the polyethylene glycol is 800-10000.
[0008] S1 adds hexamethylene diisocyanate dropwise to anhydrous polyethylene glycol at a rate of 0.01~0.02 mL / s to carry out the reaction.
[0009] The addition reaction described in S1 was carried out at 60-80°C with a stirring rate of 100-300 rpm for 1-4 h.
[0010] S2 adds dibutyltin dilaurate to the reaction solution described in S1 and reacts under stirring.
[0011] The dibutyltin dilaurate described in S2 and the reaction solution described in S1 continued to react for 1-3 h at a stirring rate of 100-300 rpm.
[0012] The mass of deionized water mentioned in S2 is less than or equal to 200% of the mass of polyethylene glycol.
[0013] S3 adds deionized water to the polyurethane-based solid-solid phase change material and stirs at 300-500 rpm for 10-60 min to complete the emulsification of the polyurethane-based solid-solid phase change material, thus obtaining an aqueous polyurethane solid-solid phase change emulsion.
[0014] An aqueous polyurethane solid-solid phase change emulsion obtained by the preparation method of the aqueous polyurethane solid-solid phase change emulsion described in any one of the above-mentioned methods.
[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing an aqueous polyurethane solid-solid phase change emulsion. In anhydrous polyethylene glycol (PEG), intramolecularly adsorbed water molecules are removed, ensuring complete addition reaction between the terminal hydroxyl groups of PEG and the isocyanate groups of hexamethylene diisocyanate (HDI), thus preparing a linear polymer prepolymer. HDI acts as a reactant for blocking the terminal hydroxyl groups of PEG. When its addition amount is less than the molar amount of PEG, the reaction of the terminal hydroxyl groups of PEG is incomplete, and part of the PEG remains in a solid-liquid phase change. When its addition amount is greater than twice the molar amount of PEG, due to the self-polymerization reaction of HDI, its intramolecular self-polymerization intensifies, forming a more stable cross-linked network. This increases the restriction on the phase change process of PEG, leading to a significant decrease in the phase change heat storage capacity. Dibutyltin dilaurate is used as a catalyst to catalyze the self-polymerization of incompletely reacted hexamethylene diisocyanate, forming cyclic urea molecules. These molecules then attach to the end groups of synthesized small linear polymers, forming cyclic macromolecular cross-linked polymers, resulting in polyurethane-based solid-solid phase change particles. This process can improve reaction efficiency and degree. However, when the addition amount exceeds 0.3%, the system viscosity increases rapidly, and solid agglomerates appear in the reactants, making aqueous emulsification impossible. The aforementioned polyurethane-based solid-solid phase change particles can be shear-dispersed with water to form uniformly dispersed nanoparticles in the aqueous phase. When the water addition amount is less than 70% of the polyethylene glycol content, the high-viscosity reactant system cannot be uniformly dispersed in water, leading to uneven emulsion particle size dispersion and decreased stability. Based on this, the amount of water added can be adjusted to prepare aqueous dispersions with different solid contents as required. This invention prepares aqueous polyurethane solid-solid phase change emulsions through solvent-free reaction. The reaction process does not involve the addition of organic solvents, conforming to environmental protection principles. The aqueous polyurethane solid-solid phase change emulsion can be industrially produced, offering significant benefits.
[0016] The polyurethane-based solid-solid phase change material of this invention can form an emulsion when uniformly dispersed in an aqueous phase, and shows no significant sedimentation or stratification after one month of storage. Its phase change heat storage capacity is very close to the original value of polyethylene glycol. The aqueous polyurethane solid-solid phase change emulsion of this invention operates stably within a temperature range of 20℃-60℃ and can exhibit phase change capability at 20℃-70℃. It is an environmentally friendly, efficient, and reliable alternative, playing an important role in the field of solid-solid phase change materials. Attached Figure Description
[0017] Figure 1 These are physical images of samples of the waterborne polyurethane solid-solid phase change emulsion prepared in Example 1 of this invention at different temperatures.
[0018] Figure 2 This is a transmission electron microscope (TEM) image of the aqueous polyurethane solid-solid phase change emulsion prepared in Example 5 of this invention after drying.
[0019] Figure 3This is a phase transition enthalpy test chart of the waterborne polyurethane solid-solid phase change emulsion prepared in Example 4 of the present invention.
[0020] Figure 4 This is the 1H NMR spectrum of the aqueous polyurethane solid-solid phase change emulsion prepared in Example 5 of this invention after drying and dissolving in deuterated dimethyl sulfoxide. Detailed Implementation
[0021] The technical solution of the present invention will be clearly and completely described below with reference to specific accompanying drawings, process steps, implementation conditions, and materials. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Waterborne polyurethane solid-solid phase change emulsions have excellent physicochemical properties and environmental advantages. They can be uniformly dispersed into nano-sized particles in the aqueous phase and exist stably. They have high phase change heat storage capacity and are suitable for various processing methods such as spraying, impregnation, and blending.
[0023] This invention discloses a method for preparing an aqueous polyurethane solid-solid phase change emulsion, comprising the following steps: 1) Polyethylene glycol is vacuum dried at 110°C for 12 h. The molecular weight of the polyethylene glycol is 800-10000, and can be further reduced to 2000-8000, to obtain oven-dried polyethylene glycol that is free of water after drying and dehydration.
[0024] 2) Add 100g of completely dried polyethylene glycol to a 500ml three-necked flask, evacuate the flask, and then purge with nitrogen three times to ensure complete removal of air. Then, slowly add hexamethylene diisocyanate dropwise at a rate of 0.01~0.02 mL / s and react at 60-80℃ with a stirring speed of 100-300 rpm for 1-4 hours for prepolymerization. The reaction is carried out under a nitrogen atmosphere. The amount of hexamethylene diisocyanate added is 1:(1~2) molar ratio of polyethylene glycol, and can further be 1:(1.5~1.75).
[0025] Polyethylene glycol and hexamethylene diisocyanate undergo an end-group addition reaction as shown below. The isocyanate groups on both sides of the hexamethylene diisocyanate react with the terminal hydroxyl groups of polyethylene glycol to form a linear polymer. However, due to the excess of hexamethylene diisocyanate, the degree of polymerization is low, which inhibits the growth of the polymer chain.
[0026]
[0027] 3) Then, dibutyltin dilaurate is added to the three-necked flask, and the reaction is continued for 1-3 hours at 60-80℃ and a stirring speed of 100-300 rpm to obtain a polyurethane-based solid-solid phase change material. The amount of dibutyltin dilaurate added is 0.1%-0.3% of the molar amount of hexamethylene diisocyanate.
[0028] With the addition of dibutyltin dilaurate as a catalyst, the incompletely reacted hexamethylene diisocyanate underwent self-polymerization as shown below at 60-80℃, forming cyclic urea molecules. These molecules then attached small linear polymers synthesized in the first step to their end groups, forming cyclic macromolecular cross-linked polymers. After a reaction time of 2 hours or more, the hexamethylene diisocyanate was completely reacted, and the preparation of polyurethane solid-solid phase change particles was completed.
[0029]
[0030] 4) Add at least 70 g of deionized water to the three-necked flask, but generally no more than 200 g. Shear emulsify at 80°C and a stirring speed of 300-500 rpm for 10-60 min to obtain an aqueous polyurethane-based solid-solid phase change emulsion. The amount of deionized water added is calculated to be 70%-200% of the mass of polyethylene glycol.
[0031] Example 1 First, polyethylene glycol with a molecular weight of 10,000 was dried in a vacuum oven at 110°C for 12 hours to obtain oven-dried polyethylene glycol.
[0032] Next, 100 g of oven-dry polyethylene glycol was added to a 500 ml flask, and after evacuation, nitrogen gas was introduced. This process was repeated three times to ensure complete removal of air. Then, 1.68 g of hexamethylene diisocyanate was slowly added dropwise at a rate of 0.05 mL every 3 seconds. The reaction was carried out at 60 °C with a stirring speed of 100 rpm for 1 h under a nitrogen atmosphere for prepolymerization.
[0033] Then, 0.02 g of dibutyltin dilaurate was added to a three-necked flask, and the reaction was continued for 2 h at 60 °C and a stirring speed of 100 rpm to obtain a polyurethane-based solid-solid phase change material.
[0034] Finally, 200 g of deionized water was added to a three-necked flask, and shear emulsification was carried out at 80°C and 300 rpm for 10 min to obtain an aqueous polyurethane-based solid-solid phase change emulsion.
[0035] Example 2 First, polyethylene glycol with a molecular weight of 8000 was dried in a vacuum oven at 110°C for 12 hours to obtain oven-dried polyethylene glycol.
[0036] Next, 100 g of oven-dry polyethylene glycol was added to a 500 ml flask, and after evacuation, nitrogen gas was introduced, repeated three times to ensure complete removal of air. Then, 2.625 g of hexamethylene diisocyanate was slowly added dropwise at a rate of 0.05 mL every 3 seconds, and the reaction was carried out at 70 °C with a stirring speed of 150 rpm for 2 h under a nitrogen atmosphere for prepolymerization.
[0037] Then, 0.03 g of dibutyltin dilaurate was added to a three-necked flask, and the reaction was continued for 1 h at 70 °C and a stirring speed of 150 rpm to obtain a polyurethane-based solid-solid phase change material.
[0038] Finally, 150 g of deionized water was added to a three-necked flask, and shear emulsification was carried out at 80°C and 400 rpm for 40 min to obtain an aqueous polyurethane-based solid-solid phase change emulsion.
[0039] Example 3 First, polyethylene glycol with a molecular weight of 6000 was dried in a vacuum oven at 110°C for 12 hours to obtain oven-dried polyethylene glycol.
[0040] Next, 100 g of oven-dry polyethylene glycol was added to a 500 ml flask, and after evacuation, nitrogen gas was introduced. This process was repeated three times to ensure complete removal of air. Then, 4.2 g of hexamethylene diisocyanate was slowly added dropwise at a rate of 0.05 mL every 3 seconds. The reaction was carried out at 75°C and a stirring speed of 200 rpm for 3 h under a nitrogen atmosphere for prepolymerization.
[0041] Then, 0.03 g of dibutyltin dilaurate was added to a three-necked flask, and the reaction was continued for 3 h at 75 °C and a stirring speed of 200 rpm to obtain a polyurethane-based solid-solid phase change material.
[0042] Finally, 120 g of deionized water was added to a three-necked flask, and shear emulsification was carried out at 80°C and 500 rpm for 60 min to obtain an aqueous polyurethane-based solid-solid phase change emulsion.
[0043] Example 4 First, polyethylene glycol with a molecular weight of 4000 was dried in a vacuum oven at 110°C for 12 hours to obtain oven-dried polyethylene glycol.
[0044] Next, 100 g of oven-dry polyethylene glycol was added to a 500 ml flask, and after evacuation, nitrogen gas was introduced, repeated three times to ensure complete removal of air. Then, 6.3 g of hexamethylene diisocyanate was slowly added dropwise at a rate of 0.05 mL every 3 seconds, and the reaction was carried out at 80 °C with a stirring speed of 200 rpm for 2 h under a nitrogen atmosphere for prepolymerization.
[0045] Then, 0.02 g of dibutyltin dilaurate was added to a three-necked flask, and the reaction was continued for 2 h at 80 °C and a stirring speed of 200 rpm to obtain a polyurethane-based solid-solid phase change material.
[0046] Finally, 100 g of deionized water was added to a three-necked flask, and shear emulsification was carried out at 80°C and 500 rpm for 30 min to obtain an aqueous polyurethane-based solid-solid phase change emulsion.
[0047] Example 5 First, polyethylene glycol with a molecular weight of 2000 was dried in a vacuum oven at 110°C for 12 hours to obtain oven-dried polyethylene glycol.
[0048] Next, 100 g of oven-dry polyethylene glycol was added to a 500 ml flask, and after evacuation, nitrogen gas was introduced. This process was repeated three times to ensure complete removal of air. Then, 16.8 g of hexamethylene diisocyanate was slowly added dropwise at a rate of 0.05 mL every 3 seconds. The reaction was carried out at 80 °C and a stirring speed of 100 rpm for 4 h under a nitrogen atmosphere for prepolymerization.
[0049] Then, 0.02 g of dibutyltin dilaurate was added to a three-necked flask, and the reaction was continued for 2 h at 80 °C and a stirring speed of 100 rpm to obtain a polyurethane-based solid-solid phase change material.
[0050] Finally, 70 g of deionized water was added to a three-necked flask, and shear emulsification was carried out at 80°C and 300 rpm for 20 min to obtain an aqueous polyurethane-based solid-solid phase change emulsion.
[0051] Example 6 First, polyethylene glycol with a molecular weight of 1000 was dried in a vacuum oven at 110°C for 12 hours to obtain oven-dried polyethylene glycol.
[0052] Next, 100 g of oven-dry polyethylene glycol was added to a 500 ml flask, and after evacuation, nitrogen gas was introduced. This process was repeated three times to ensure complete removal of air. Then, 16.8 g of hexamethylene diisocyanate was slowly added dropwise at a rate of 0.05 mL every 3 seconds. The reaction was carried out at 80 °C with a stirring speed of 100 rpm for 1 h under a nitrogen atmosphere for prepolymerization.
[0053] Then, 0.03 g of dibutyltin dilaurate was added to a three-necked flask, and the reaction was continued for 2 h at 80 °C and a stirring speed of 100 rpm to obtain a polyurethane-based solid-solid phase change material.
[0054] Finally, 100 g of deionized water was added to a three-necked flask, and the mixture was sheared and emulsified for 50 min at 80 °C and a stirring speed of 400 rpm to obtain an aqueous polyurethane-based solid-solid phase change emulsion.
[0055] like Figure 1 As shown, the prepared aqueous polyurethane solid-solid phase change emulsion was in a sample bottle. The prepared phase change emulsion was dispersed stably at 20℃ and 60℃ without obvious sedimentation or stratification, indicating that the aqueous polyurethane solid-solid phase change emulsion of the present invention can exist stably at different temperatures and remains stable in the working temperature range of 20℃-60℃.
[0056] like Figure 2 The TEM image of the prepared aqueous polyurethane solid-solid phase change emulsion after drying clearly shows that the phase change material exhibits obvious spherical particles with uniform particle size distribution and all smaller than 500 nm.
[0057] The heat storage enthalpy of the aqueous polyurethane-based solid-solid phase change emulsion of Example 4 was tested, and it can be seen that... Figure 3 The crystallization and melting peak intensities (obtained by integrating the area) of the blue polyethylene glycol 4000 are basically consistent with those of the red aqueous polyurethane-based solid-solid phase change emulsion. The difference in their integrated area is not significant, demonstrating their endothermic and exothermic temperature range. This indicates that the prepared aqueous polyurethane-based solid-solid phase change emulsion has good heat storage capacity and can exhibit phase change capability at 20℃-70℃.
[0058] The aqueous polyurethane-based solid-solid phase change emulsion from Example 5 was dried and then dissolved in deuterated dimethyl sulfoxide. Its 1H NMR spectrum was then measured. Figure 4 The hydrogen NMR spectrum of the red curve is completely consistent with the hydrogen element distribution in the structural formula of the waterborne polyurethane-based solid-solid phase change emulsion corresponding to the black curve, indicating that the reaction between polyethylene glycol and hexamethylene diisocyanate has successfully occurred, thus demonstrating the successful preparation of the waterborne polyurethane-based solid-solid phase change emulsion.
Claims
1. A method for preparing an aqueous polyurethane solid-solid phase change emulsion, characterized in that, Includes the following steps: S1, anhydrous polyethylene glycol and hexamethylene diisocyanate were added in an oxygen-free environment at a molar ratio of 1:(1~2) to obtain a reaction solution containing a linear polymer. S2, under conditions of 60-80℃, firstly, the reaction solution described in S1 is further reacted with dibutyltin dilaurate, wherein the dibutyltin dilaurate is 0.1%-0.3% of the molar amount of hexamethylene diisocyanate, to obtain a polyurethane-based solid-solid phase change material. Then, the polyurethane-based solid-solid phase change material is dispersed in deionized water, wherein the mass of deionized water is greater than or equal to 70% of the mass of polyethylene glycol, to obtain an aqueous polyurethane solid-solid phase change emulsion.
2. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, In S1, the molecular weight of the polyethylene glycol is 800-10000.
3. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, S1 adds hexamethylene diisocyanate dropwise to anhydrous polyethylene glycol at a rate of 0.01~0.02 mL / s to carry out the reaction.
4. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, The addition reaction described in S1 is carried out at 60-80°C.
5. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, The addition reaction described in S1 was carried out at a stirring rate of 100-300 rpm for 1-4 h.
6. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, S2 adds dibutyltin dilaurate to the reaction solution described in S1 and reacts under stirring.
7. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 6, characterized in that, The dibutyltin dilaurate described in S2 and the reaction solution described in S1 continued to react for 1-3 h at a stirring rate of 100-300 rpm.
8. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, The mass of deionized water mentioned in S2 is less than or equal to 200% of the mass of polyethylene glycol.
9. The method for preparing the aqueous polyurethane solid-solid phase change emulsion according to claim 1, characterized in that, S3 adds deionized water to the polyurethane-based solid-solid phase change material and stirs at 300-500 rpm for 10-60 min to complete the emulsification of the polyurethane-based solid-solid phase change material, thus obtaining an aqueous polyurethane solid-solid phase change emulsion.
10. An aqueous polyurethane solid-solid phase change emulsion obtained by the preparation method of the aqueous polyurethane solid-solid phase change emulsion according to any one of claims 1 to 9.